Device for fabricating three-dimensional fabrication object and method of manufacturing three-dimensional fabrication object

A device for fabricating a three-dimensional fabrication object includes a fabrication part, a flattening member to place powder in the fabrication part to form an excessively thick powder layer and remove the powder on the top surface side of the excessively thick powder layer multiple times to obtain a powder layer while moving in a direction orthogonal to a lamination direction of the powder layer, and a fabrication unit to bind the powder in the powder layer to form a laminar fabrication object, (wherein the laminar fabrication object is formed repeatedly to fabricate the three-dimensional fabrication object), wherein the amount of a layer thickness of the powder removed for the last time is less than that for any other time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based on and claims priority pursuant to 35 U.S.C. § 119 to Japanese Patent Application Nos. 2017-094972 and 2017-103119, filed on May 11, 2017 and May 24, 2017, respectively, in the Japan Patent Office, the entire disclosures of which are hereby incorporated by reference herein.

BACKGROUND

Technical Field

The present disclosure relates to a device for fabricating a three-dimensional fabrication object and a method of manufacturing a three-dimensional fabrication object.

Description of the Related Art

A device for fabricating a three-dimensional fabrication object is known which repeats forming a powder layer having a predetermined thickness in a fabrication unit and binding powder of the powder layer in a predetermined form to form a laminar fabrication structure and laminates the laminar fabrication structure to fabricate a three-dimensional fabrication object.

For example, a device for fabricating a three-dimensional fabrication object has been proposed in which, in the powder layer forming, an excessively thick powder layer thicker than a predetermined thickness is formed and thereafter the powder on the top surface side of the excessively thick powder layer is removed by a removing device to form a powder layer having a predetermined thickness. Such a three-dimensional device includes and moves a flattening roller (removing member) in parallel with the stage surface of a stage of a fabrication part multiple times to form a single powder layer having a predetermined thickness. During the flattening operation for the first time, the flattening roller supplies the powder to the stage and at the same time flattens the supplied powder to form a powder layer having a thickness greater than the predetermined thickness. Thereafter, while the flattening member removes the powder on the top surface side of the powder layer having a thickness greater than the predetermined thickness, the flattening member simultaneously flattens the upper surface of the powder layer remaining on the stage during the flattening operation for the second time to form a powder layer having the predetermined thickness. In addition, it is possible to remove the powder twice or more during the flattening operation.

SUMMARY

According to the present invention, provided is an improved device for fabricating a three-dimensional fabrication object, which includes a fabrication part, a flattening member to place powder in the fabrication part to form an excessively thick powder layer and remove the powder on the top surface side of the excessively thick powder layer multiple times to obtain a powder layer while moving in a direction orthogonal to a lamination direction of the powder layer, and a fabrication unit to bind the powder in the powder layer to form a laminar fabrication object, wherein the amount of a layer thickness of the powder removed for the last time is less than that for any other time.

As another aspect of the present disclosure, an improved device for fabricating a three-dimensional fabrication object is provided which includes a fabrication part, a flattening member to place powder all over the fabrication part to form a pre-powder layer and remove the powder on the top surface side of the pre-powder layer to form a powder layer while being rotationally driven around a rotation axis orthogonal to a direction of movement of the flattening member against the fabrication part, and a fabrication unit to bind the powder in the powder layer to form a laminar fabrication object, wherein the rotation speed or the moving speed of the flattening member is faster during removing the powder on the top surface side of the pre-powder layer than during forming the pre-powder layer.

As another aspect of the present disclosure, an improved method of manufacturing a three-dimensional fabrication object, which includes forming an excessively thick powder layer in a fabrication part, removing powder on a top surface side of the excessively thick powder layer multiple times to obtain a powder layer, binding powder in the powder layer to form a laminar fabrication structure and repeating the forming, the removing, and the binding to fabricate a three-dimensional fabrication object, wherein an amount of the powder in the excessively thick powder layer removed for the last time is smaller than that for any other time.

DESCRIPTION OF THE EMBODIMENTS

To improve quality of a three-dimensional fabrication object, it is desirable that powder density of a powder layer is high and the deviation from the desired fabrication from is small when the powder is bound to obtain a desired fabrication form. However, for a typical device for fabricating a three-dimensional fabrication object, powder density of a powder layer is insufficient when binding powder to obtain a desired form during fabrication and the fabrication accuracy of the thus-obtained three-dimensional fabrication object tends to deteriorate.

An embodiment of the device for fabricating a three-dimensional object (three-dimensional fabrication object) relating to the present disclosure is described below.

FIG. 1is a diagram illustrating a schematic planar view of a device100for fabricating a three-dimensional object of the embodiment, andFIG. 2is a diagram illustrating a schematic side view of the device100illustrated inFIG. 1from the right.FIG. 3is a diagram illustrating an enlarged side view of a powder holding unit1illustrated inFIG. 2during fabrication.

FIG. 4is a diagram illustrating a perspective view of the main part (the powder holding unit1and a fabrication unit5) of the device100. The powder holding unit1and the fabrication unit5can relatively move to each other in the Y direction. A liquid discharging unit50of the fabrication unit5is configured relatively movable to the powder holding unit1in the X direction.FIG. 3is a schematic cross section on line A-A ofFIG. 4.

The device100is a fabrication device with powder. The device100includes the powder holding unit1and the fabrication unit5. The powder holding unit1forms a laminar fabrication structure30in which powder20is bound. The fabrication unit5discharges a liquid fabrication10against the powder layer of the powder20placed in laminate in the powder holding unit1.

The powder holding unit1includes a powder storage tank11and a flattening roller12as a rotary member (rotating body) as a flattening member constituting a flattening device (recoater, also a removing member). The flattening member can take, for example, a member having a plate-like form (blade) instead of the rotary member.

The powder storage tank11includes a fabrication tank22(fabrication part) in which the laminar fabrication structure30is laminated to fabricate a three-dimensional fabrication object, a supply tank21to store the powder20supplied to the fabrication tank22, and an extra powder collection tank29to collect the extra amount of the powder20supplied to the fabrication tank22. The fabrication tank22and the supply tank21are disposed side by side in the Y direction.

A supply stage23constituting the base of the supply tank21freely elevates up and down in the vertical direction (height direction). The powder20as fabrication material is placed on the supply stage23.

A supply stage24constituting the base of the fabrication tank22freely elevates up and down in the vertical direction (height direction). On the fabrication stage24, a three-dimensional fabrication object is fabricated in which the laminar fabrication structure30is laminated.

FIG. 5is a block diagram illustrating a control unit500of the device100. The control unit500controls driving a supply stage elevation motor27to elevate up and down the supply stage23in the Z direction (height direction). In addition, the control unit500controls driving a fabrication stage elevation motor28to elevate up and down the fabrication stage24in the Z direction (height direction).

The side of the supply stage23is disposed to abut on the inner surface of the supply tank21. The side of the fabrication stage24is disposed to abut on the inner surface of the fabrication tank22. The upper surfaces of the supply stage23and the fabrication stage24are held to be horizontal.

A powder supply device554is disposed in the supply tank21. At the time of starting fabrication or when the amount of the powder20in the supply tank21decreases, the control unit500controls driving a powder supply drive unit517to supply the powder20in the tank constituting the powder supply device554to the supply tank21. As the method of conveying powder for powder supply, for example, a screw conveyor method using a screw and an air transfer method using air are suitable.

The flattening roller12has a length along its axis (length along the X direction) longer than the widths of the inside dimension of the fabrication tank22and the supply tank21and is disposed reciprocally movable relatively to the stage surface in the Y direction along the stage surface (on which the powder20is placed) of the fabrication stage24. The control unit500controls driving a flattening roller reciprocation motor25to cause the flattening roller12to horizontally move along the upper surfaces of the supply stage23and the fabrication stage24. To supply the powder20to the fabrication tank22, the flattening roller12is horizontally moved. As a result, the flattening roller12partially pushes the powder20present on the supply stage23of the supply tank21to the fabrication tank22. At the same time, the flattening roller12smooths and flattens the surface (upper surface) of the powder20supplied to the fabrication tank22to form a powder layer31having a predetermined thickness.

In addition, a flattening roller rotation motor26drives and rotates the flattening roller12. The flattening roller12reciprocally moves in the horizontal direction to pass over the supply tank21and the fabrication tank22while being rotated by the flattening roller rotation motor26. Consequently, the flattening roller12pushes the upper part of the powder20present on the supply tank21to the fabrication tank22and also flattens the powder20while passing over the fabrication tank22to form the powder layer31having a predetermined thickness.

The fabrication unit5includes the liquid discharging unit50to discharge or apply the liquid fabrication10to the powder layer31to bind the powder20on the fabrication stage24to form the laminar fabrication structure30as a laminar structure in which the powder20is bound.

The liquid discharging unit50includes a carriage51and two liquid discharging heads, i.e., a first head52aand a second head52b(collectively referred to as head52) carried by the carriage51. The number of the heads is not limited to two and can be one or three or more.

A first guiding member54and a second guiding member55hold the carriage51movable in the X direction indicated by the arrow (hereinafter referred to as X direction as well as Y direction and Z direction) as the main scanning direction. A first supporting member75aand a second supporting member75bas the supporting members support the first guiding member54and the second guiding member55at both ends in the X direction in such a manner that both of the first guiding member54and the second guiding member55are held movable up and down against side plates70(a first side plate70aand a second side plate70b). An X direction scanning motor constituting a main scanning direction mobile mechanism550reciprocates this carriage51in the X direction as the main scanning direction via a pully and a belt.

Each of a first head52aand a second head52b(collectively referred to as head52) includes two nozzle lines, each having multiples nozzles through which the liquid fabrication10is discharged. The two nozzle lines of the first head52aseparately discharge cyan liquid fabrication and magenta liquid fabrication. The two nozzle lines of the second head52bseparately discharge yellow liquid fabrication and black liquid fabrication. The configuration of the head52and the color of the liquid fabrication discharged by the head52are not limited thereto.

As illustrated inFIG. 1, multiple tanks60accommodating each liquid fabrication of the cyan liquid fabrication, magenta liquid fabrication, yellow liquid fabrication, and black liquid fabrication are mounted onto a tank mounting portion56to supply the liquid fabrication of each color to the heads52via a supply tube, etc.

On one side (on the right hand side inFIG. 1) of the mobile range of the carriage51in the X direction, a maintenance mechanism61is disposed to maintain and restore the head52of the liquid discharging unit50. The maintenance mechanism61is mainly constituted of a cap62and a wiper63. In the maintenance mechanism61, the cap62is caused to adhere to the nozzle surface (on which the nozzle is formed) of the head52in order to suction the liquid fabrication from the nozzle. This is to eject the powder20and highly-thickened liquid fabrication10clogged in the nozzle. Thereafter, the maintenance mechanism61wipes off the nozzle surface with a wiper63to form a meniscus of the nozzle. In addition, except when the liquid fabrication10is discharged, the maintenance mechanism61covers the nozzle surface of the head52with the cap62to prevent contamination of the powder20into the nozzle or drying of the liquid fabrication10.

The fabrication unit5includes a slider part72held movable by the guiding member71disposed on a base member7and the whole of the fabrication unit5can reciprocate in the Y direction (sub-scanning direction) perpendicular to the X direction. A sub-scanning direction mobile mechanism552reciprocates the whole of the fabrication unit5in the Y direction.

The liquid discharging unit50is disposed movable up and down together with the first guiding member54and the second guiding member55in the Z direction by an elevation mechanism551for discharging unit.

Next, the control unit500of the device100is described with reference toFIG. 5.

The control unit500includes a main control unit500A including a central processing unit (CPU)501, a read only memory (ROM)502, and a random access memory (RAM)503. The CPU501controls the entire of the device100. The ROM502stores programs including a program for the CPU501to execute the three-dimensional fabrication and other fixed data. The RAM503temporarily saves fabrication data.

The control unit500includes a non-volatile random access memory (NVRAM)504to hold data while the power to the device100is blocked off. In addition, the control unit500includes an application specific integrated circuit (ASIC)505for image processing of various signal processing for image data and processing input and output signals to control the entire of the device100.

The control unit500includes an external interface (I/F)506to send and receive data and signals to be used on receiving fabrication data from an external fabrication data creating device600. The fabrication data creating device600creates fabrication data of the final (i.e., target) three-dimensional fabrication object sliced into each laminar structure and is configured with an information processing device such as a home computer. The control unit500includes an input-output (I/O)507to take in the detected signals of various sensors. Detected signals of a temperature and humidity sensor560to detect the temperature and the humidity as the environment condition of the device and detected signals from other sensors are input into the I/O507.

The control unit500includes a head drive control unit508to drive and control the head52of the liquid discharging unit50.

In addition, the control unit500includes a main scanning direction drive unit510and a sub-scanning direction drive unit512. The main scanning direction drive unit510drives a motor constituting the main scanning direction mobile mechanism550to move the carriage51of the liquid discharging unit50in the X direction (main scanning direction).

The sub-scanning direction drive unit512drives a motor constituting the sub-scanning direction mobile mechanism552to move the fabrication unit5in the Y direction (sub-scanning direction).

The control unit500further includes an elevation drive unit511for discharging unit to drive a motor constituting the elevation mechanism551for discharging unit to move (elevate up and down) the carriage51of the liquid discharging unit50in the Z direction. It is also possible to have a configuration to elevate up and down the entire of the fabrication unit5in the Z direction.

The control unit500includes a supply stage drive unit513to drive the supply stage elevation motor27to elevate up and down the supply stage23and a fabrication stage drive unit514to drive the fabrication stage elevation motor28to elevate up and down the fabrication stage24. In addition, the control unit500includes a reciprocation drive unit515for flattening to drive a flattening roller reciprocation motor25to move the flattening roller12and a rotation drive unit516for flattening to drive the flattening roller rotation motor26to rotationally drive the flattening roller12.

The control unit500includes a powder supply drive unit517to drive a powder supply device554to supply the powder20to the supply tank21and a maintenance drive unit518to drive a maintenance mechanism61of the liquid discharging unit50.

The control unit500is connected with an operation panel522through which information for the device is input by a user and displayed for a user.

The powder20is supplied to the fabrication tank22, for example, in such a manner that the supply stage23is elevated 200 μm, the fabrication stage24is lowered 100 μm, and the flattening roller12is moved in the Y2 direction indicated by the arrow inFIG. 4. Consequently, the flattening roller12pushes the powder20in an amount corresponding to the elevation of the supply stage23in the Y2 direction so that a new powder layer (which is a pre-powder layer31a) having a thickness of 100 μm is laminated in the fabrication tank22. Of the powder layer pushed and conveyed by the flattening roller12, the extra powder20that is not allowed to enter into the fabrication tank22is collected by an extra powder collection tank29.

As the powder20, stainless powder coated with a resin material is used. As the stainless powder, gas atomized powder (PSS316L—20 μm grade, manufactured by SANYO SPECIAL STEEL Co., Ltd.) is used. In addition, the resin material for coating is acetoacetyl group-modified polyvinyl alcohol (Gohsenx™ Z-100, manufactured by The Nippon Synthetic Chemical Industry Co., Ltd.).

Next, an example of formation of the powder layer by the device100is described with reference toFIG. 6.

FIGS. 6A to 6Fare diagrams illustrating an example of the formation of the powder layer31having a predetermined thickness in this embodiment.

First, as illustrated inFIG. 6A, a single or multiple layers of the laminar fabrication structure30is assumed to be formed on the fabrication stage24of the fabrication tank22.

To form the powder layer31having a predetermined thickness to form the next laminar fabrication structure30on the uppermost laminar fabrication structure30, as illustrated inFIG. 6B, the supply stage23of the supply tank21is elevated in an amount corresponding to the amount of movement z1 in the Z1 direction (upward). At the same time, the fabrication stage24of the fabrication tank22is lowered in an amount corresponding to the amount of movement z2 in the Z2 direction (downward). The amounts of movement z1 and z2 are set to be greater than the target thickness Δt (i.e., thickness when the laminar fabrication structure30is formed upon supply of the liquid fabrication10) of the powder layer31having a predetermined thickness. This target thickness Δt is preferably about several tens μm to several hundreds μm.

For the elevation of the supply stage23in an amount of z1, the height of the uppermost surface of the powder20on the supply stage23is higher by Δt1 (nearly equal to z1) than the upper part of the side wall forming the supply tank21. In addition, for the lowering of the fabrication stage24in an amount of z2, the height of the uppermost surface of the powder20on the fabrication stage24is higher by Δt2 (nearly equal to z2) than the upper part of the side wall forming the fabrication tank22.

The relation between the amount of movement z1 of the supply stage23and the amount of movement z2 of the fabrication stage24is z1≥z2. The upper surface of the supply stage23and the upper surface of the fabrication stage24have the same area. Therefore, it is possible to supply the powder20from the supply tank21to the fabrication tank22in an amount sufficient to place the powder20on the entire of the gap appearing above the uppermost surface of the powder20in the fabrication tank22by lowering the fabrication stage24. Of the powder20conveyed from the supply tank21to the fabrication tank22, the extra powder20not allowed to be supplied to the fabrication tank22drops into the extra powder collection tank29as the extra powder20a.

If such extra powder20ais caused to exist, the extra powder20ais constantly present on the downstream in the direction of the movement of the flattening roller12while the flattening roller12conveys the powder20from the supply tank21to the downstream end of the fabrication tank22in the Y2 direction from the supply tank21toward the fabrication tank22. Due to the extra powder20abeing present on the downstream in the direction of movement of the flattening roller12, the mass of the extra powder20apresses the powder20to form the powder layer31having a predetermined thickness, which is true till the downstream end in the direction of movement of the flattening roller12in the fabrication tank22. This is advantageous to form uniform powder layer31having a predetermined thickness with a high powder density.

Next, as illustrated inFIGS. 6B and 6C, the flattening roller12is moved in the Y2 direction (outbound flattening direction) from the supply tank21to the fabrication tank22. At the same time, the flattening roller12is rotationally driven in the direction indicated by the arrow (counterclockwise inFIG. 6) inFIGS. 6B and 6C. Due to this rotational drive, the lowermost part of the periphery of the flattening roller12moves in the same direction as the Y2 direction. When the flattening roller12moves in the Y2 direction while rotating counterclockwise inFIG. 6, the powder20present above the upper surface level of the supply tank21can be smoothly conveyed to the fabrication tank22in the Y2 direction. Moreover, when the flattening roller12is passing over the fabrication tank22while rotationally further moving in the Y2 direction, the surface of the powder20supplied to the fabrication tank22is smoothed and flattened. Due to this, the pre-powder layer31ahaving a thickness thicker than the target thickness Δt of the finally formed powder layer31having a predetermined thickness is formed on the uppermost laminar fabrication structure30,

Sequentially, as illustrated inFIG. 6D, the supply stage23of the supply tank21is lowered by the amount of movement z3 in the Z2 direction and the fabrication stage24of the fabrication tank22is elevated by the amount of movement z4 in the Z1 direction. Therefore, the powder20located on the upper layer portion of the pre-powder layer31aformed on the fabrication stage24of the fabrication tank22swells upward from the upper surface level of the fabrication tank22due to the flattening outbound described above. The amount of movement z4 of the fabrication stage24at this point is set in such a manner that the gap between the upper surface of the previously formed powder layer31having a predetermined thickness and the lowermost part of the flattening roller12is the target thickness Δt1 of the powder layer31having a predetermined thickness.

Next, as illustrated inFIG. 6E, the flattening roller12is moved in the Y1 direction (inbound flattening direction) from the fabrication tank22toward the supply tank21. At the same time, the flattening roller12is rotationally driven in the direction indicated by the arrow (clockwise inFIG. 6) inFIG. 6D. Due to this rotational drive, the lowermost surface of the periphery of the flattening roller12moves in the same direction as the Y1 direction. When the flattening roller12moves in the Y1 direction while rotating clockwise inFIG. 6, the surface of the powder20of the fabrication tank22is smoothed and flattened while the powder20present above the upper surface level of the fabrication tank22is conveyed in the Y1 direction. As a result, the powder layer31having a predetermined thickness having a target thickness Δt is formed in the fabrication tank22.

Moreover, when the flattening roller12rotates and at the same time moves in the Y1 direction and passes over the fabrication tank22, unused powder20that forms the pre-powder layer31abut is not used for forming the powder layer31having a predetermined thickness is returned to the supply tank21.

After the powder layer31having a predetermined thickness is formed, the flattening roller12passes over the supply tank21and returns to the initial position (original position) as illustrated inFIG. 6F. Thereafter, back to the operation illustrated inFIG. 6A, the head52discharges liquid droplets of the liquid fabrication10and the laminar fabrication structure30having a predetermined form is formed in the formed powder layer31having a predetermined thickness.

Thereafter, the powder20is supplied and flattened to form the powder layer31having a predetermined thickness and the head52discharges the liquid fabrication10thereto to form a new laminar fabrication structure30on the previously formed laminar fabrication structure30.

For example, the laminar fabrication structure30is formed in such a manner that the powder20is mixed with the liquid fabrication10discharged from the head52thereto to dissolve the adhesive contained in the powder20so that the dissolved adhesive is bound with each other to bind the powder20. The new laminar fabrication structure30and the laminar fabrication structure formed therebelow are united to partially form a three-dimensional fabrication object.

The powder layer is formed and the liquid fabrication is discharged a required number of times to complete a three-dimensional fabrication object in which the laminar fabrication structure30is laminated.

FIG. 7is a diagram illustrating when a discharged droplet of the liquid fabrication10lands on the powder layer31having a predetermined thickness.

FIG. 7is a diagram illustrating a permeation state of a discharged liquid droplet of the liquid fabrication10when the discharged liquid droplet lands on the powder layer31having a predetermined thickness based on two-dimensional image data created at a pitch of 300 dpi×300 dpi (corresponding to about 85 μm).

In the operation of forming the powder layer31having a predetermined thickness described with reference toFIG. 6, the flattening roller12is reciprocated to flatten the powder layer inbound and outbound, i.e., twice, to form a single layer of the powder layer31having a predetermined thickness. The powder layer can be flattened three or more times. To form a single layer of the powder layer31having a predetermined thickness by flattening the powder layer multiple times, density of the powder20constituting the powder layer31having a predetermined thickness can be increased step by step, which is advantageous to form a uniform powder layer31having a predetermined thickness with high powder density.

In the configuration where the powder layer is flattened multiple times, the powder20is supplied to the fabrication tank22during the flattening for the first time. The flattening for the second time or later is also the removal of the powder20on the top surface side of the pre-powder layer31ain an amount corresponding to the thickness greater than the target thickness Δt of the powder layer31having a predetermined thickness in the pre-powder layer31aformed in the fabrication tank22.

In this embodiment, the roller member such as the flattening roller12is used as the flattening member. During the flattening, the contact surface (lower front portion in the direction of movement of the periphery of the flattening roller12) in contact with the powder20in front in the direction of the movement of the flattening member is oriented obliquely downward. Therefore, if the flattening member moves, the powder20is moved along the direction of movement with the contact surface while generating a force to push it downward. Therefore, due to the flattening member, the powder density can be increased.

The device100of the embodiment removes the powder20multiple times while forming a single layer of the powder layer31. Moreover, at least one of the thickness of the portion of the pre-powder layer31ato be removed and the rotation speed of the flattening roller12is set to be different at the removal for the last time and the removal for any other time during the removal multiple times.

A case in which the layer thickness of the powder20to be removed and the rotation speed of the flattening roller12are constant for the multiple removals to form a single layer of the powder layer31having a predetermined thickness is described below as a reference configuration example.

Reference Configuration

FIGS. 8 to 16are diagrams illustrating forming a powder layer of the reference configuration example and schematic cross sections of the supply tank21and the fabrication tank22of the powder holding unit1from the right inFIG. 1.

The powder supply in the powder layer forming of the reference configuration example is described with reference toFIGS. 8 to 10.

As illustrated inFIG. 8, the supply stage23is relatively elevated against the flattening roller12by Δt1 (=264 μm) in the Z direction (vertical direction). As illustrated inFIG. 9, the fabrication stage24is relatively elevated down against the flattening roller12by Δt2 (=240 μm) in the Z direction. Next, as illustrated inFIG. 10, the flattening roller12is relatively translated against the powder storage tank11at a speed of V1 (=50 mm/s) in the Y2 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N1 {=2 (rps)} in the direction of rolling up (counterclockwise inFIG. 10) the powder20in the powder holding unit1. The flattening roller12pushes the diagonally hatched portion inFIGS. 8 and 9of the powder20on the supply stage23toward the fabrication stage24.

Accordingly, as illustrated inFIG. 10, the flattening roller12supplies the powder20to the fabrication tank22and flattens it to form the pre-powder layer31ahaving a thickness of 240 μm. The process of moving the flattening roller12to supply the powder20and flatten the powder layer thereof is flattening for the first time.

The powder removal in the powder layer forming of the reference configuration example is described with reference toFIGS. 11 to 16.

FIGS. 11 and 12are diagrams illustrating the flattening for the second time, which is the removal for the first time.

As illustrated inFIG. 11, the supply stage23is relatively elevated down against the flattening roller12by Δt3 (=306 μm) in the Z direction for the flattening for the second time. The supply stage23is lowered against the flattening roller12to prevent the flattening roller12from bring into contact the powder20in the supply tank21while the flattening roller12horizontally moves over the supply stage23for removal.

Moreover, as illustrated inFIG. 11, the fabrication stage24is relatively elevated against the flattening roller12by Δt4 (=60 μm) in the Z direction for the flattening for the second time.

Next, as illustrated inFIG. 12, the flattening roller12is relatively translated against the powder storage tank11at a speed of V2 (=50 mm/s) in the Y1 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N2 {=5 (rps)} in the direction of rolling up (clockwise inFIG. 12) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 12, the upper layer part having a thickness of Δt4 of the pre-powder layer31aformed over the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened.

The powder20the flattening roller12pushed away and removed from the pre-powder layer31aon the fabrication stage24at the flattening for the second time is partially or entirely returned to the supply tank21.

FIGS. 13 and 14are diagrams illustrating the flattening for the third time, which is the removal for the second time.

As illustrated inFIG. 13, the fabrication stage24is relatively elevated against the flattening roller12by Δt5 (=60 μm) in the Z direction for the flattening for the third time. Next, as illustrated inFIG. 14, the flattening roller12is relatively translated against the powder storage tank11at a speed of V3 (=50 mm/s) in the Y2 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N3 {=5 (rps)} in the direction of rolling up (counterclockwise inFIG. 14) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 14, the upper layer part having a thickness of Δt5 of the pre-powder layer31aformed in the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened.

The powder20the flattening roller12pushed away and removed from the pre-powder layer31aon the fabrication stage24at the flattening for the third time is partially or entirely returned to the extra powder collection tank29.

FIGS. 15 and 16are diagrams illustrating the flattening for the fourth time, which is the removal for the third time.

As illustrated inFIG. 15, the fabrication stage24is relatively elevated against the flattening roller12by Δt6 (=60 μm) in the Z direction for the flattening for the fourth time.

Next, as illustrated inFIG. 16, the flattening roller12is relatively translated against the powder storage tank11at a speed of V4 (=50 mm/s) in the Y1 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N4 {=5 (rps)} in the direction of rolling up (clockwise inFIG. 16) of the powder20in the fabrication tank22. Due to this, the upper layer part having a thickness of Δt6 of the pre-powder layer31aformed on the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened to form the pre-powder layer31having a predetermined thickness (60 μm).

The powder20the flattening roller12pushed away and removed from the pre-powder layer31aon the fabrication stage24at the flattening for the fourth time is partially or entirely returned to the supply tank21.

Next, the evaluation test of the reference configuration example is described.

The evaluation method is as follows:

The following was used as the powder20. That is, SUS powder (PSS316L, manufactured by SANYO SPECIAL STEEL Co., Ltd.) having an average particle diameter of 8 μm was coated with an organic material (polyvinyl alcohol DF-05). 0.25 percent by mass of an acrylic resin (MP-1451, manufactured by Soken Chemical & Engineering Co., Ltd.) was added to the coated SUS powder to obtain powder mixture. Thereafter, the powder layer31having a predetermined thickness of the powder20was formed in the fabrication tank22as described above with reference toFIGS. 8 to 16to evaluate the void ratio of the powder20.

For comparison, the void ratio of the powder layer31having a predetermined thickness formed in the fabrication tank22for the configuration of flattening twice and removal once was 60.4 percent. In the configuration of removal three times like the referential configuration example, the void ratio of the powder layer31having a predetermined thickness formed in the fabrication tank22was 58.6 percent. According to this evaluation test for increasing the number of removal from once to three times, the reduction of the void ratio of the powder20of the powder layer31having a predetermined thickness formed in the fabrication tank22was confirmed.

The device100discharges liquid droplets of the liquid fabrication10to the powder layer31having a predetermined thickness and sequentially laminates the laminar fabrication structure30in which the powder20of the powder layer31having a predetermined thickness is bound to form a solid freeform fabrication object (three-dimensional fabrication object). In the reference configuration example described above, to form a single layer of the powder layer31having a predetermined thickness to form a single layer of the laminar fabrication structure30, the powder20is supplied to the fabrication tank22in an amount more than required followed by removing the powder20excessively supplied multiple times (three times).

With the removal of the extra power20once, the density of the powder20in the fabrication tank22is increased only once so that it is not possible to fully obtain the effect of increasing density of the powder20in the fabrication tank22by the removal.

In the reference configuration example, a powder layer (pre-powder layer31a) thicker than the desired lamination pitch (the target thickness Δt of the powder layer31having a predetermined thickness) is formed by the flattening for the first time. At the flattening for the jth time (2≤j<M) (removal for (j−1)th time), the extra powder20surpassing the lamination pitch supplied to the fabrication tank22is partially removed until the desired lamination pitch is obtained at the flattening for Mth time (removal for (M−1)th time).

Due to this configuration, the density of the powder layer31having a predetermined thickness formed in the fabrication tank22can be increased, thereby increasing the density of a fabrication object.

In examples described later, like the reference configuration example, in comparison with the configuration having removal once, density of the powder layer31having a predetermined thickness can be increased, thereby increasing the density of a fabrication object because the powder layer31having a predetermined thickness is formed by removal multiple times.

Next, a first example (hereinafter referred to as Embodiment 1) of the device100forming a powder layer is described.

In the powder layer forming of Embodiment 1, the layer thickness of the powder20removed for the last time in the removal process multiple times is different from that for any other time.

The powder supply in the powder layer forming of Embodiment 1 is the same as the powder supply in the powder layer forming of the reference configuration example with reference toFIGS. 8 to 10. In addition, like the reference configuration example, moving the flattening roller12to flatten the powder layer while supplying the powder20to the fabrication tank22in the powder supply is the flattening for the first time.

The powder removal in the powder layer forming of Embodiment 1 is described with reference toFIGS. 17 to 22.

FIGS. 17 and 18are diagrams illustrating the flattening for the second time, which is the removal for the first time.

As illustrated inFIG. 17, the supply stage23is relatively elevated down against the flattening roller12by Δt3 (=306 μm) in the Z direction for the flattening for the second time. Moreover, as illustrated inFIG. 17, the fabrication stage24is relatively elevated against the flattening roller12by Δt4 (=90 μm) in the Z direction for the flattening for the second time.

Next, as illustrated inFIG. 18, the flattening roller12is relatively translated against the powder storage tank11at a speed of V2 (=50 mm/s) in the Y1 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N2 {=5 (rps)} in the direction of rolling up (clockwise inFIG. 18) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 18, the upper layer part having a thickness of Δt4 of the pre-powder layer31aformed in the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened.

FIGS. 19 and 20are diagrams illustrating the flattening for the third time, which is the removal for the second time.

As illustrated inFIG. 19, the fabrication stage24is relatively elevated against the flattening roller12by Δt5 (=60 μm) in the Z direction for the flattening for the third time.

Next, as illustrated inFIG. 20, the flattening roller12is relatively translated against the powder storage tank11at a speed of V3 (=50 mm/s) in the Y2 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N3 {=5 (rps)} in the direction of rolling up (counterclockwise inFIG. 20) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 20, the upper layer part having a thickness of Δt5 of the pre-powder layer31aformed on the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened.

FIGS. 21 and 22are diagrams illustrating the flattening for the fourth time, which is the removal for the third time.

As illustrated inFIG. 21, the fabrication stage24is relatively elevated against the flattening roller12by Δt6 (=30 μm) in the Z direction for the flattening for the fourth time.

Next, as illustrated inFIG. 22, the flattening roller12is relatively translated against the powder storage tank11at a speed of V4 (=50 mm/s) in the Y1 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N4 {=5 (rps)} in the direction of rolling up (clockwise inFIG. 22) the powder20in the fabrication tank22. Due to this, the upper layer part having a thickness of Δt6 of the pre-powder layer31aformed on the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened to form the pre-powder layer31having a predetermined thickness (60 μm).

In the powder layer forming of Embodiment 1, in order to increase density of powder of the powder layer31having a predetermined thickness, the top surface of the pre-powder layer31aformed in the fabrication tank22is scraped (removed) multiple times to form a single layer of the powder layer31having a predetermined thickness like the reference configuration example described above.

In Embodiment 1, to form a single layer of the powder layer31having a predetermined thickness by scraping multiple times, as the thickness of the pre-powder layer31ais closer to the target thickness (Δt), the scraping amount (removal amount of powder) of the powder20is reduced. That is, the pre-powder layer31ais scraped less toward the removal for the last time. Specifically, in Embodiment 1, the scraping amount in the forming of the powder layer31having a predetermined thickness by scraping the pre-powder layer31athree times is 90 μm for the first time, 60 μm for the second time, and 30 μm for the third time. That is, the scraping amount for the third time, which is the last time, is the smallest.

When the pre-powder layer31ais scraped and becomes closer to the target thickness, the flattening roller12and the fabrication object (laminar fabrication structure30) further approaches each other. If the amount of scraped powder is small, the flattening roller12conveys the force of pressing the powder20downward to the powder20situated below remaining as the powder layer31having a predetermined thickness via the layer of the powder20to be scraped, so that powder density of the powder layer31having a predetermined thickness can be increased. Therefore, quality of the solid freeform fabrication object formed by binding the powder20of the powder layer31having a predetermined thickness can be improved.

If the layer thickness of the powder20scraped for the last time is large, the following problem occurs: That is, the force of the flattening roller12pressing the powder20downward in the last removal but one is not easily conveyed to the powder20remaining as the powder layer31having a predetermined thickness positioned below and distant from the flattening roller12(distant corresponding to the layer thickness scraped during the removing for the last time).

In addition, in the removal of scraping off the powder20at the upper layer portion of the pre-powder layer31asituated sufficiently above the already-formed laminar fabrication structure30, that is, the initial stage of the scraping multiple times, the layer thickness (scraping pitch) of the powder20scraped once can be large.

However, in the removal of the powder20in the powder layer situated close to the laminar fabrication structure30, that is, the final stage of the scraping multiple times, the scraping pitch is decreased to increase the force applied vertically to the powder20finally remaining as the powder layer31having a predetermined thickness. Therefore, in the removal for the last time, the force of the flattening roller12pressing downward increases the force vertically applied to the powder20remaining as the powder layer31having a predetermined thickness. Accordingly, the powder20forming the powder layer31having a predetermined thickness can be compressed, thereby increasing powder density.

In addition, in the removal for the last time, the flattening roller12directly contacts the upper surface of the powder20remaining as the powder layer31having a predetermined thickness. Therefore, in the removal for the last time, the force acting on the powder20remaining as the powder layer31having a predetermined thickness due to the force of the flattening roller12pressing downward is not affected by the degree of the scraping. For this reason, powder density of the powder layer31having a predetermined thickness can be increased during the removing for the last time but one in Embodiment 1 in which the scraping pitch is decreased for the removal for the last time. Therefore, powder density can be increased more in Embodiment 1 than in the reference configuration example in which the scraping pitch is uniform in all the removal.

In Embodiment 1, in the removal for the third time in which the powder20situated close to the powder20remaining as the powder layer31having a predetermined thickness, the layer thickness of the powder20to be removed is decreased as thin as 30 μm. Due to this, the force of the flattening roller12pressing the upper surface of the pre-powder layer31adownward in the removal for the second time, which is previous to the removal for the third time, is easily conveyed to the powder20remaining as the powder layer31having a predetermined thickness, thereby increasing powder density of the powder layer31having a predetermined thickness. In addition, in Embodiment 1, in the removal of the upper surface portion of the pre-powder layer31aimmediately after it is formed (i.e., initial stage in the scraping multiple times), the layer thickness of the powder20to be removed is set to be thicker, i.e., 90 μm. Due to such an increase in the amount of scraping in comparison with the removal for the last time, the number of removal required to remove the extra powder20surpassing the predetermined thickness can be reduced so that the time taken to form powder layers can be shortened.

Next, the second example (Example 2) of the device100forming powder layers is described.

In the powder layer forming of Example 2, the rotation speed of the flattening roller12is set different for the removal for the last time and the removal for any other time for the removal multiple times.

The powder supply during the powder layer forming of Example 2 is the same as the powder supply during the powder layer forming of the reference configuration example described with reference toFIGS. 8 to 10. In addition, like the reference configuration example, moving the flattening roller12for flattening the powder layer while supplying the powder20to the fabrication tank22during the powder supply is the flattening for the first time.

The powder removal during the powder layer forming of Example 2 is described next. The powder removal of Example 2 is the same as that of the reference configuration example described above except for the rotation speed of the flattening roller12. The powder removal of Example 2 is described with reference toFIGS. 11 to 16for use in the description of the powder removal of the reference configuration example.

FIGS. 11 and 12are diagrams illustrating the flattening for the second time, which is the removal for the first time.

As illustrated inFIG. 11, the supply stage23is relatively elevated down against the flattening roller12by Δt3 (=306 μm) in the Z direction for the flattening for the second time.

Moreover, as illustrated inFIG. 11, the fabrication stage24is relatively elevated against the flattening roller12by Δt4 (=60 μm) in the Z direction for the flattening for the second time.

Next, as illustrated inFIG. 12, the flattening roller12is relatively translated against the powder storage tank11in the Y1 direction at a speed of V2 (=50 mm/s). At this point, the flattening roller12is rotationally translated at a rotation speed of N2 {=1 (rps)} in the direction of rolling up (clockwise inFIG. 12) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 12, the upper layer part having a thickness of Δt4 of the pre-powder layer31aformed in the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened.

FIGS. 13 and 14are diagrams illustrating the flattening for the third time, which is the removal for the second time.

As illustrated inFIG. 13, the fabrication stage24is relatively elevated against the flattening roller12by Δt5 (=60 μm) in the Z direction for the flattening for the third time.

Next, as illustrated inFIG. 14, the flattening roller12is relatively translated against the powder storage tank11at a speed of V3 (=50 mm/s) in the Y2 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N3 {=2 (rps)} in the direction of rolling up (counterclockwise inFIG. 14) of the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 14, the upper layer part having a thickness of Δt5 of the pre-powder layer31aformed on the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened.

FIGS. 15 and 16are diagrams illustrating the flattening for the fourth time, which is the removal for the third time.

As illustrated inFIG. 15, the fabrication stage24is relatively elevated against the flattening roller12by Δt6 (=60 μm) in the Z direction for the flattening for the fourth time.

Next, as illustrated inFIG. 16, the flattening roller12is relatively translated against the powder storage tank11at a speed of V4 (=50 mm/s) in the Y1 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N4 {=5 (rps)} in the direction of rolling up (clockwise inFIG. 16) of the powder20in the fabrication tank22. For this reason, the upper layer part having a thickness of Δt6 of the pre-powder layer31aformed on the fabrication tank22is removed and simultaneously the upper surface of the powder20is flattened to form the pre-powder layer31having a predetermined thickness (60 μm).

In the powder layer forming of Example 2, the rotation speed of the flattening roller12is increased toward the scraping for the last time, i.e., N2<N3<N4. If the rotation speed of the flattening roller12is decreased, static friction force tends to occur between the flattening roller12and the powder20and between particles of the powder20.

The powder20contacting the periphery of the flattening roller12in motion is under a pressure to move toward the direction of flattening due to the friction force occurring between the periphery of the flattening roller12and the powder20. At this point, if static friction force is applied therebetween, the powder20tends to be displaced toward the direction of flattening because static friction force is larger than kinetic friction force. In addition, if static force is applied to the particles of the powder20, the powder20situated below contacting the powder20to which the static friction force is applied also tends to be displaced toward the direction of flattening due to friction force occurring between the powder20and the powder20situated therebelow.

Therefore, if static friction force occurs, the force by the flattening roller12in the horizontal direction is easily applicable to the powder20remaining after the removal so that displacement of particles in the horizontal direction in the layer of the powder20remaining after the removal easily occurs. In the last stage of the powder removal multiple times in which the distance between the flattening roller12and the laminar object (laminar fabrication structure30) decreases, if the force in the horizontal direction acts on the powder20remaining after the removal, particles of the powder20finally remaining as the powder layer31having a predetermined thickness tend to be displaced, which may cause non-uniformity in density. Moreover, via the powder20finally remaining as the powder layer31having a predetermined thickness, the force in the horizontal direction acts on the fabrication object (laminar fabrication object30) formed below, which may cause positional displacement and result in deformation of a solid freeform fabrication object.

Conversely, in Example 2, the rotation speed of the flattening roller12in the final stage of the removal is increased to cause kinetic friction to easily occur between the flattening roller12and the powder20and between particles of the powder20to prevent occurrence of static friction. For this reason, the force by the flattening roller12in the horizontal direction does not easily occur to the powder20remaining after the removal. That is, in the last stage of the powder removal multiple times, it is possible to prevent action of the force in the horizontal direction to the powder20remaining after the removal and displacement of particles of the powder20finally remaining as the powder layer31having a predetermined thickness so that occurrence of non-uniform density can be prevented. Prevention of occurrence of non-uniform density leads to improvement of powder density of the powder layer31having a predetermined thickness.

Moreover, it is possible to prevent action of the force in the horizontal direction to the fabrication object (laminar fabrication structure30) formed below the powder20finally remaining as the powder layer31having a predetermined thickness and deformation of a solid freeform fabrication object. Due to reduction of occurrence of non-uniform density of the powder20and deformation of a solid freeform fabrication object (three-dimensional fabrication object), quality of the solid freeform fabrication object can be improved.

In the removal (initial stage of the powder scraping multiple times) of removing the upper surface part sufficiently distant from the laminar fabrication structure30, the powder20of the pre-powder layer31ais shaken in the horizontal direction to improve powder density, thereby increasing density of the powder20finally remaining as the powder layer31having a predetermined thickness. Therefore, in the initial stage of the powder removal multiple times, the rotation speed of the flattening roller12is not necessarily fast.

In Embodiment 1, the layer thickness of the powder20removed (scraped) for the last time in the multiple-time powder removal is different from that for any other time. In Example 2, the rotation speed of the flattening roller12for the last time in the multiple-time powder removal is different from that for any other time.

In the powder layer forming by the device100, the condition that the layer thickness of the powder20removed for the last time in the multiple-time powder removal is different from that for any other time can be used in combination with the condition that the rotation speed of the flattening roller12for the last time in the multiple-time powder removal is different from that for any other time.

In such a configuration, as approaching to the removal for the last time, the layer thickness of the powder20to be removed is small and at the same time the rotation speed of the flattening roller12is increased. This makes it possible to shorten the time to be taken required for powder layer forming as in Embodiment 1 and at the same time improve powder density of the powder layer31having a predetermined thickness. Moreover, like Example 2, it is possible to reduce occurrence of non-uniformity of density and deformation of a solid freeform fabrication object.

In addition, as the rotation speed of the flattening roller12increases, the amount of the powder20moving together with the surface movement of the periphery thereof decreases, thereby reducing displacement of the layers situated below. However, as the rotation speed increases, the amount of the powder20rolled up increases. Conversely, in the condition that the rotation speed of the flattening roller12increases while the layer thickness to be scraped decreases in the last stage of multiple-time removal, the amount of the powder20rolled up ascribable to the increase in the rotation speed can be reduced.

Next, the third example (Example 3) of powder layer forming by the device100is described.

In Example 3, the condition of the powder layer forming is changed depending on the depth of the layer of the laminar fabrication structure30to be formed. The upper surface of each layer during the powder layer forming is described with reference toFIGS. 8 to 16for use in the description of the powder layer forming in the reference configuration example andFIGS. 17 to 22for use in the description of the powder layer forming in Embodiment 1.

First Layer to Twentieth Layer

In the powder supply from the first layer to the twentieth layer of Example 3, the supply stage23is relatively elevated against the flattening roller12in the Z direction (vertical direction) by 192 μm as Δt1 illustrated inFIG. 8.

In addition, the fabrication stage24is relatively lowered against the flattening roller12in the Z direction by 120 μm as Δt2 illustrated inFIG. 9.

Next, as illustrated inFIG. 10, the flattening roller12is relatively translated against the powder storage tank11at a speed of V1 (=50 mm/s) in the Y2 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N1 {=5 (rps)} in the direction of rolling up (counterclockwise inFIG. 10) the powder20in the fabrication tank22.

Accordingly, as illustrated inFIG. 10, the powder20is supplied to the fabrication tank22and flattened to form the pre-powder layer31ahaving a thickness of 120 μm. Moving the flattening roller12to flatten the powder20while supplying the powder20to the fabrication tank22during the powder supply is the flattening for the first time.

Next, the powder removal in the powder layer forming from the first layer to the twentieth layer of Example 3 is described with reference toFIGS. 11 and 12.

In the powder removal from the first layer to the twentieth layer of Example 3, the powder20is removed only once.

FIGS. 11 and 12are diagrams illustrating the flattening for the second time, which is also the powder removal.

As illustrated inFIG. 11, the supply stage23is relatively elevated down against the flattening roller12by Δt3 (=306 μm) in the Z direction for the flattening for the second time.

Moreover, as illustrated inFIG. 11, the fabrication stage24is relatively elevated against the flattening roller12by Δt4 (=60 μm) in the Z direction for the flattening for the second time.

Next, as illustrated inFIG. 12, the flattening roller12is relatively translated against the powder storage tank11at a speed of V2 (=50 mm/s) in the Y1 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N2 {=5 (rps)} in the direction of rolling up (clockwise inFIG. 12) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 12, the upper layer part having a thickness of Δt4 of the pre-powder layer31aformed in the fabrication tank22is removed and simultaneously the upper surface of the powder20is flattened to form the pre-powder layer31having a predetermined thickness (60 μm).

In the powder removal from the first layer to the twentieth layer of Example 3, the powder20is flattened twice and one of the two is the removal.

Twenty First to Fortieth Layer

In the powder supply from the twenty first layer to the fortieth layer of Example 3, the supply stage23is relatively elevated against the flattening roller12in the Z direction (vertical direction) by 264 μm as Δt1 illustrated inFIG. 8.

In addition, the fabrication stage24is relatively lowered against the flattening roller12in the Z direction by 180 μm as Δt2 illustrated inFIG. 9.

Next, as illustrated inFIG. 10, the flattening roller12is relatively translated against the powder storage tank11at a speed of V1 (=50 mm/s) in the Y2 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N1 {=5 (rps)} in the direction of rolling up (counterclockwise inFIG. 10) the powder20in the fabrication tank22.

Accordingly, as illustrated inFIG. 10, the powder20is supplied to the fabrication tank22and flattened to form the pre-powder layer31ahaving a thickness of 180 μm. Moving the flattening roller12to flatten the powder20while supplying the powder20to the fabrication tank22in the powder supply is the flattening for the first time.

Next, the powder removal in the powder layer forming from the twenty first layer to the fortieth layer of Example 3 is described with reference toFIGS. 11 to 14.

In the powder removal from the twenty first layer to the fortieth layer of Example 3, the powder20is removed twice.

FIGS. 11 and 12are diagrams illustrating the flattening for the second time, which is the removal for the first time.

As illustrated inFIG. 11, the supply stage23is relatively elevated down against the flattening roller12by Δt3 (=306 μm) in the Z direction for the flattening for the second time. As illustrated inFIG. 11, the fabrication stage24is relatively elevated against the flattening roller12by Δt4 (=90 μm) in the Z direction.

Next, as illustrated inFIG. 12, the flattening roller12is relatively translated against the powder storage tank11at a speed of V2 (=50 mm/s) in the Y1 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N2 {=5 (rps)} in the direction of rolling up (clockwise inFIG. 12) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 12, the upper layer part having a thickness of Δt4 of the pre-powder layer31aformed in the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened.

FIGS. 13 and 14are diagrams illustrating the flattening for the third time, which is the removal for the second time.

As illustrated inFIG. 13, the fabrication stage24is relatively elevated against the flattening roller12by Δt5 (=60 μm) in the Z direction for the flattening for the third time.

Next, as illustrated inFIG. 14, the flattening roller12is relatively translated against the powder storage tank11at a speed of V3 (=50 mm/s) in the Y2 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N3 {=5 (rps)} in the direction of rolling up (counterclockwise inFIG. 14) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 14, the upper layer part having a thickness of Δt5 of the pre-powder layer31aformed in the fabrication tank22is removed and simultaneously the upper surface of the powder20is flattened to form the pre-powder layer31having a predetermined thickness (60 μm).

In the powder removal from the twenty first layer to the fortieth layer of Example 3, the powder20is flattened three times and two of the three is the removal.

Forty First Layer and Higher Layer

The powder layer forming for the forty first layer or higher layer is the same as the powder layer forming of Embodiment 1 described above.

In the powder supply from the forty first layer or higher layer of Example 3, the supply stage23is relatively elevated against the flattening roller12in the Z direction (vertical direction) by 264 μm as Δt1 illustrated inFIG. 8. In addition, the fabrication stage24is relatively lowered against the flattening roller12in the Z direction by 240 μm as Δt2 illustrated inFIG. 9.

Next, as illustrated inFIG. 10, the flattening roller12is relatively translated against the powder storage tank11at a speed of V1 (=50 mm/s) in the Y2 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N1 {=5 (rps)} in the direction of rolling up (counterclockwise inFIG. 10) the powder20in the fabrication tank22.

Accordingly, as illustrated inFIG. 10, the powder20is supplied to the fabrication tank22and flattened to form the pre-powder layer31ahaving a thickness of 240 μm. Moving the flattening roller12to flatten the powder20while supplying the powder20in the powder supply is the flattening for the first time.

The powder removal in the powder layer forming of the forty first layer and higher layers of Example 3 is described with reference toFIGS. 17 to 22.

In the powder removal of the forty first layer and higher layers of Example 3, the powder20is removed three times.

FIGS. 17 and 18are diagrams illustrating the flattening for the second time, which is the removal for the first time.

As illustrated inFIG. 17, the supply stage23is relatively elevated down against the flattening roller12by Δt3 (=306 μm) in the Z direction for the flattening for the second time. Moreover, as illustrated inFIG. 17, the fabrication stage24is relatively elevated against the flattening roller12by Δt4 (=90 μm) in the Z direction for the flattening for the second time.

Next, as illustrated inFIG. 18, the flattening roller12is relatively translated against the powder storage tank11at a speed of V2 (=50 mm/s) in the Y1 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N2 {=5 (rps)} in the direction of rolling up (clockwise inFIG. 18) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 18, the upper layer part having a thickness of Δt4 of the pre-powder layer31aformed in the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened.

FIGS. 19 and 20are diagrams illustrating the flattening for the third time, which is the removal for the second time.

As illustrated inFIG. 19, the fabrication stage24is relatively elevated against the flattening roller12by Δt5 (=60 μm) in the Z direction for the flattening for the third time.

Next, as illustrated inFIG. 20, the flattening roller12is relatively translated against the powder storage tank11at a speed of V3 (=50 mm/s) in the Y2 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N3 {=5 (rps)} in the direction of rolling up (counterclockwise inFIG. 20) the powder20in the fabrication tank22. For this reason, as illustrated inFIG. 20, the upper layer part having a thickness of Δt5 of the pre-powder layer31aformed on the fabrication tank22is removed and simultaneously the upper surface of the pre-powder layer31ais flattened.

FIGS. 21 and 22are diagrams illustrating the flattening for the fourth time, which is the removal for the third time.

As illustrated inFIG. 21, the fabrication stage24is relatively elevated against the flattening roller12by Δt6 (=30 μm) in the Z direction for the flattening for the fourth time.

Next, as illustrated inFIG. 22, the flattening roller12is relatively translated against the powder storage tank11at a speed of V4 (=50 mm/s) in the Y1 direction. At this point, the flattening roller12is rotationally translated at a rotation speed of N4 {=5 (rps)} in the direction of rolling up (clockwise inFIG. 22) the powder20in the fabrication tank22. For this reason, the upper layer part having a thickness of Δt6 of the pre-powder layer31aformed on the fabrication tank22is removed and simultaneously the upper surface of the powder20is flattened to form the pre-powder layer31having a predetermined thickness (60 μm).

In the powder removal from the forty first layer and higher layers of Example 3, the powder20is flattened four times and three of the four is the removal.

As described above, the number of removal during the powder layer forming for layers below is decreased in Example 3.

The lower layers of the laminar fabrication structure30constituting a solid freeform fabrication object enjoy the effect of powder compression by the powder removal for the upper layers so that the number of powder removal can be relatively small for the lower layers.

In Example 3, productivity can be improved by decreasing the number of removal for lower layers.

Next, the elevation amount of the supply stage23in the device100in the embodiment is described.

In a case in which the flattening roller12is used as the device for powder supply and powder removal to flatten the powder layer, the required elevation amount of the supply stage23is inferred as follows: That is inferred as: (lamination pitch)×(number of flattening)×(area ratio of fabrication stage24to supply stage23)+100 (μm) at maximum. This is because:

The lowering amount of the fabrication stage24during the flattening for the first time is 240 μm in the evaluation test of the reference configuration example described above.

This is represented by (lamination pitch: 60 μm)×(number of flattening: four times)×(area ratio of fabrication stage24to supply stage23: 1). Moreover, while the lowering amount of the fabrication stage24is 240 μm, the elevation amount of the supply stage23is 264 μm. Therefore, a uniform pre-powder layer31acan be formed in the fabrication tank22.

The elevation amount of the supply stage23can be represented by (lamination pitch: 60 μm)×(number of flattening: four times)×(area ratio of fabrication stage24to supply stage23: 1)+24 (μm).

Therefore, an estimation of the elevation amount of the supply stage23required during fabrication, which is (lamination pitch)×(number of flattening)×(area ratio of fabrication stage24to supply stage23)+100 (μm) at maximum, is sufficient. If the elevation amount of the supply stage23during the flattening for the first time is set as described above, the powder20is sufficiently supplied in the fabrication tank22to form a uniform pre-powder layer31atherein.

The device100of the present embodiment discharges liquid droplets of the liquid fabrication10to the powder layer31having a predetermined thickness and sequentially laminates the laminar fabrication structure30in which the powder20of the powder layer31having a predetermined thickness is bound to form a solid freeform fabrication object (three-dimensional fabrication object). In addition, the process of setting the thickness of the powder layer in the fabrication tank22as the lamination pitch includes powder supply of the powder20to the fabrication tank22and powder removal of the powder20supplied to the fabrication tank22. Furthermore, during the powder supply, the powder20is supplied once. During the powder removal, the powder20is removed multiple times.

In the present embodiment, the powder layer is flattened for every removal in the powder removal. It is preferable that the powder layer be flattened for at least the removal for the last time of the multiple-time removal. This makes it possible to form a flat powder surface suitable for application of the liquid fabrication10.

In the device100of the present application, the device100flattens the powder layer with the flattening roller12every time the powder is supplied and removed in the process of setting the thickness of the powder layer in the fabrication tank22as the lamination pitch. Due to this configuration, the powder20can be supplied, removed, and flattened by the flattening roller12alone, which contributes to simplification of the device100.

Variation

Next, a variation of the device100is described to which at least one of the thickness of the portion of the pre-powder layer31ato be removed and the rotation speed of the flattening roller12is different in the powder removal for the last time and the powder removal for any other time among the powder removal for the multiple times is applied.

FIG. 23is a diagram illustrating a schematic planar view of the device100for fabricating a three-dimensional fabrication object of the variation andFIG. 24is a diagram illustrating a schematic side view of the device100of the variation illustrated inFIG. 23from the right.FIG. 25is a diagram illustrating a schematic front view of the device100of the variation illustrated inFIG. 23from below andFIG. 26is a diagram illustrating a perspective view of the main part (the powder holding unit1and the fabrication unit5) of the device100of the variation. The device illustrated inFIG. 25is in the middle of fabricating a solid freeform fabrication object.

The device100of the variation is a fabrication device using powder including the powder holding unit1and the fabrication unit5. This is different from the embodiments described above in that the powder holding unit1of the variation includes no supply tank21but the carriage51of the liquid discharging unit50includes a powder supply unit80. In addition, the variation is different in that the direction of movement of the flattening roller12against the supply tank21is X axis direction while the direction of the flattening roller12is Y axis direction in the embodiments.

The device100of the variation includes a control unit500having a configuration similar to the control unit500illustrated inFIG. 5. It includes a supply drive unit to control drive of the powder supply unit80instead of the supply stage drive unit513illustrated inFIG. 5.

The powder layer31having a predetermined thickness in which the powder20is laminated is formed in the powder holding unit1and the laminar fabrication structure30is formed in which the powder20is bound having a predetermined form. The fabrication unit5discharges the liquid fabrication10to the powder layer31having a predetermined thickness placed in a laminar manner in the fabrication tank22to fabricate a solid freeform fabrication object.

The powder holding unit1includes the fabrication tank22, the flattening roller12as a rotary body serving as a flattening member (recoater), etc. The flattening member can take, for example, a member having a plate-like form (blade) instead of the rotary body.

In the fabrication tank22, the fabrication layer30is laminated to fabricate a solid freeform fabrication object. The base of the fabrication tank22freely elevates and lowers in the Z direction (height direction) as the fabrication stage24. On the fabrication stage24, a solid freeform fabrication object is fabricated in which the laminar fabrication structure30is laminated.

The flattening roller12smooths and flattens the powder20supplied to the fabrication tank22to form a powder layer.

This flattening roller12is disposed relatively and reciprocally movable against the stage surface (on which the powder20is placed) of the fabrication stage24in the X direction along the stage surface. In addition, the flattening roller12moves while rotating on the fabrication tank22.

The fabrication unit5includes a liquid discharging unit50to discharge the liquid fabrication10to the powder layer on the fabrication stage24.

The liquid discharging unit50includes the carriage51and two liquid discharging heads, i.e., the first head52aand the second head52b(collectively referred to as the head52) carried by the carriage51. The number of the heads is not limited to two and can be one or three or more.

The first guiding member54and the second guiding member55hold the carriage51movable in the X direction. A first supporting member75aand a second supporting member75bas the supporting members support the first guiding member54and the second guiding member55at both ends in the X direction in such a manner that both of the first guiding member54and the second guiding member55are held movable up and down against side plates70(a first side plate70aand a second side plate70b). An X direction scanning motor constituting a main scanning direction mobile mechanism550reciprocates this carriage51via a pully and a belt in the X direction as the main scanning direction.

The two heads52includes two nozzle lines152, each having multiples nozzles through which the liquid fabrication10is discharged (illustrated in a transparent state inFIG. 23). The two nozzle lines152of the first head52aseparately discharge cyan liquid fabrication and magenta liquid fabrication. The two nozzle lines152of the second head52bseparately discharge yellow liquid fabrication and black liquid fabrication. The configuration of the head52and the color of the liquid fabrication discharged by the head52are not limited thereto.

As illustrated inFIG. 23, multiple tanks60accommodating each liquid fabrication of the cyan liquid fabrication, magenta liquid fabrication, yellow liquid fabrication, and black liquid fabrication are mounted onto a tank mounting portion56to supply the liquid fabrication of each color to the heads52via a supply tube, etc.

In addition, the carriage51includes the powder supply unit80as the powder supply device to supply the powder20onto the powder layer of the fabrication tank22. The powder supply unit80includes a powder accommodating unit81to accommodate the powder20, a supply opening part82through which the powder20is supplied, and a shuttering member83to open and close the supply opening part82.

On one side (on the right hand side inFIG. 23) of the mobile range of the carriage51in the X direction, a maintenance mechanism61is disposed to maintain and restore the head52of the liquid discharging unit50. The maintenance mechanism61of the variation includes the same configuration as the maintenance mechanism61of the embodiments described above.

The fabrication unit5includes the slider part72held movable by the guiding member71disposed on the base member7. The sub-scanning direction mobile mechanism552can reciprocally move the entire of the fabrication unit5in the Y direction orthogonal to the X direction (main scanning direction).

The liquid discharging unit50is disposed movable up and down together with the first guiding member54and the second guiding member55in the Z direction by an elevation mechanism551for discharging unit.

As described above, the device100of the variation includes no supply tank21. Therefore, the control unit500of the variation does not include the supply stage drive unit513illustrated inFIG. 5but a supply drive part. This supply drive part opens the shutter member83of the powder supply unit80to supply the powder20therethrough.

Next, an example of the fabrication operation of the device100of the variation is described with reference toFIG. 27.

FIGS. 27A to 27Dare diagrams illustrating the example of the fabrication operation of the variation.

As illustrated inFIG. 27, the device100moves the head52and causes it to discharge the liquid fabrication10to the powder layer31having a predetermined thickness placed all over the fabrication stage24of the fabrication tank22in a laminar manner and form the first laminar fabrication structure30having a predetermined form as illustrated inFIG. 27B.

As illustrated inFIG. 27C, the fabrication stage24is moved down in the Z2 direction in a predetermined amount. At this point, the lowering distance of the fabrication stage24is determined in such a manner that the distance between the upper surface of the powder layer31having a predetermined thickness where the laminar fabrication structure30is formed in the fabrication tank22and the bottom part (bottom tangent portion) of the flattening roller12is Δt. This distance Δt corresponds to the thickness of the powder layer31having a predetermined thickness to be formed next. This distance Δt is preferably about several tens μm to several hundreds μm.

Next, as illustrated inFIG. 27C, the powder supply unit80supplies the powder20onto the powder layer31having a predetermined thickness where the laminar fabrication structure30is formed and the flattening roller12flattens the supplied powder20. Due to this, as illustrated inFIG. 27D, the next powder layer31having a predetermined thickness is formed.

When the configuration of the present disclosure is applied to the device100of the variation, the control is as follows: When the powder20is supplied from the powder supply unit80and the flattening roller12flattens the supplied powder20, the lowering distance of the fabrication stage24is determined to form a pre-powder layer31athicker than Δt instead of the powder layer31having a predetermined thickness having a target thickness of Δt. After the pre-powder layer31ais formed, the fabrication stage24is elevated and the upper layer portion of the pre-powder layer31ais scraped by the flattening roller12multiple times. This is repeated multiple times to form the powder layer31having a predetermined thickness having a target thickness of Δt. Like Embodiment 1 to Example 3 described above, at least one of the thickness of the portion of the powder20to be removed and the rotation speed of the flattening roller12is different in the powder removal for the last time and the removal for any other time among the powder removal multiple times. This makes it possible to increase powder density of the powder layer31having a predetermined thickness and improve quality of a solid freeform fabrication object formed by partially binding the powder20constituting the powder layer31having a predetermined thickness followed by stacking.

The device100described above fabricates three-dimensional objects utilizing a binder jet method. The fabrication method to which the configuration of the present disclosure can be applied is not limited to the binder jet. Laser sintering (LS), electron beam sintering (EBM) can be employed. In the embodiment described above, the binding device binds powder using liquid discharged from the liquid discharging head. Also, it is possible to use a laser irradiator to sinter and bind powder, etc. The present disclosure can be applied to a solid freeform fabrication method of binding powder in a powder layer.

For binder jetting, in general, an inkjet head discharges binder ink to plaster as the powder20to agglomerate the plaster powder to form the laminar fabrication structure30. It is also possible to discharge a binder resin through an inkjet head using sand as the powder20to fabricate a three-dimensional fabrication object that can be used as a casting mold. In addition, in the binder jet method, metal, ceramic, glass, etc. can be used as the powder20. Moreover, in the binder jet method, using the powder20coated with a material soluble in a liquid for binding, it is also possible to discharge the liquid through an inkjet head and bind powder via the coating material to form the laminar fabrication structure30.

The above-described is just an example and other aspects of the present disclosure are, for example, as follows.

Aspect A

A device for fabricating a three-dimensional fabrication object such as the device100for fabricating a three-dimensional fabrication object includes a fabrication part such as the fabrication tank22, a flattening member such as the flattening roller12configured to place powder such as the powder20in the fabrication part to form an excessively thick powder layer such as the pre-powder layer31aand thereafter remove the powder on the top surface side of the excessively thick powder layer multiple times, for example three times, to obtain a powder layer having a predetermined thickness (e.g., Δt) such as the powder layer31while moving in a direction (e.g., horizontal direction) orthogonal to the lamination direction (e.g., vertical direction) of the powder layer, and a fabrication unit such as the fabrication unit5to bind the powder to form a laminar fabrication object such as the laminar fabrication object30, wherein the laminar fabrication object is formed repeatedly to fabricate the three-dimensional fabrication object, wherein the amount of the layer thickness of the powder removed for the last time (e.g., third time) is less than that for any other time (e.g., first time).

Due to this, as described in Embodiment 1, the amount of scraping for the last time is small so that the thickness of the powder present between the flattening member to remove the powder and the powder to remain as the powder layer having a predetermined thickness can be thinner for the removal for the last time but one. Due to this, the force of the flattening member pressing the powder layer at the time of removal for the last time but one is easily conveyed to the powder remaining as the powder layer having a predetermined thickness, which contributes to increasing powder density of the powder layer having a predetermined thickness. In addition, in the removal for the last time, the removing member directly contacts the surface of the powder remaining as the powder layer having a predetermined thickness. For this reason, for the removal for the last time, the force acting on the powder remaining as the powder layer having a predetermined thickness due to the force of the flattening member pressing the powder layer is considered to be irrelevant of the amount of the scraping for the last time.

Therefore, in Aspect A, when powder is bound to form a predetermined form by the fabrication operation, powder density of the powder layer can be increased more in comparison with a typical fabrication operation.

Aspect B

Aspect B differs from Aspect A in that as the number of removal increases, the amount of scraping is gradually decreased.

Due to this, as described in Embodiment 1, the layer thickness of powder is thick in the initial stage of multiple-time powder removal, which enables the time to be taken for powder layer forming shorter.

Aspect C

Aspect C differs from Aspect A or Aspect B in that the flattening member such as the flattening roller12is a rotary body and the rotation speed {N4=5 (rpm), etc.} of the flattening member during the removal for the last time, for example, the third time is greater than the rotation speed {N2=1 (rpm), etc.} during the powder removal for any other time such as the first time.

As described in the embodiments, this shortens the time to be taken required for powder layer forming, increases powder density of the powder layer having a predetermined thickness, and moreover prevents occurrence of non-uniform density of the powder layer having a predetermined thickness and deformation of a solid freeform fabrication object.

Aspect D

A device for fabricating a three-dimensional fabrication object such as the device100for fabricating a three-dimensional object includes a fabrication part such as the fabrication tank22, a flattening member such as the flattening roller12configured to place powder such as the powder20in the fabrication part to form an excessively thick powder layer such as the pre-powder layer31aand thereafter remove the powder on the top surface side of the pre-powder layer31amultiple times, for example three times, to obtain a powder layer having a predetermined thickness (e.g., Δt) such as the powder layer31while moving in a direction (e.g., horizontal direction) orthogonal to the lamination direction (e.g., vertical direction) of the powder layer, and a fabrication unit such as the fabrication unit5configured to bind the powder to form a laminar fabrication object such as the laminar fabrication object30, wherein the laminar fabrication object is formed repeatedly to fabricate the three-dimensional fabrication object, wherein the rotation speed {N4=5 (rps)} of the flattening member for the powder removal for the last time, for example, the third time, of the multiple times is greater than the rotation speed {N2=1 (rps)} for any other time, the first time.

As described in Example 2, this enables to prevent action of the force of the removing member in the direction of movement against the powder remaining as the powder layer having a predetermined thickness during the powder removal for the last time and occurrence of partial displacement of the powder remaining as the powder layer having a predetermined thickness. This enables to prevent occurrence of non-uniformity in powder density of the powder layer having a predetermined thickness ascribable to the displacement and a decrease in powder density ascribable to non-uniform density. Therefore, when the powder is bound to form a predetermined form during the fabrication, powder density of the powder layer can be increased more in comparison with a typical fabrication operation.

Aspect E

Aspect E differs from Aspect C or Aspect D in that as the number of powder removal increases, the rotation speed of the flattening member such as the flattening roller12gradually increases.

As described in Example 2, this enables to increase powder density by shaking the powder layer in the direction of movement of the flattening member such as horizontal direction due to the decrease in the rotation speed of the removing member in the initial stage of the multiple-time powder scraping. Therefore, the density of the powder remaining as the powder layer having a predetermined thickness can be increased. In addition, increasing the rotation speed of the flattening member toward the multiple-time powder removal for the last time prevents occurrence of non-uniformity in density in the powder layer having a predetermined thickness and enables to increase powder density of the powder layer having a predetermined thickness.

Aspect F

In Aspect F, the flattening member such as the flattening roller12is cylindrical in any one of Aspect A to Aspect E.

As described in the embodiment, in this configuration, the contact surface (front lower part in the direction of movement of the periphery of the cylindrical form) of the flattening member in contact with the powder at the front in the direction of movement of the flattening member is oriented obliquely downward. Therefore, if the flattening member moves, the powder is moved along the direction of movement by the contact surface while generating a force to push it downward. Therefore, due to the usage of such a flattening member, the powder density can be increased.

Aspect G

A method of manufacturing a three-dimensional fabrication object includes forming an excessively thick powder layer such as the pre-powder layer31ain a fabrication part such as the fabrication tank22, removing powder such as the powder20on the top surface side of the excessively thick powder layer multiple times (for example, three times) to obtain a powder layer having a predetermined thickness (e.g., Δt) such as the powder layer31by a flattening member configured to move in a direction (for example, horizontal direction) orthogonal to the lamination direction (for example, vertical direction) of the powder layer; and binding the powder in the powder layer to form a laminar fabrication structure such as the laminar fabrication structure30in the fabrication part, repeating the forming, the removing, and the binding to fabricate a three-dimensional fabrication object, wherein the amount of the excessively thick powder layer scraped for the last time (e.g., third time) of the multiple times is smaller than that for any other time (e.g., first time).

According to this, as described in Embodiment 1, powder density of the powder layer can be high when the powder is bound to have a predetermined form during the fabrication.

Aspect H

A non-transitory computer readable storage medium storing one or more instructions that, when executed by one or more processors, cause the one or more processors in a device for fabricating a three-dimensional fabrication object such as the device100for fabricating a three-dimensional fabrication object to execute a method of processing setting information, the method of manufacturing a three-dimensional fabrication object includes forming an excessively thick powder layer such as the pre-powder layer31ain a fabrication part such as the fabrication tank22, removing powder such as the powder20of the top surface of the excessively thick powder layer multiple times (for example, three times) to obtain a powder layer having a predetermined thickness (e.g., Δt) such as the powder layer31by a flattening member configured to move in a direction (for example, horizontal direction) orthogonal to the lamination direction (for example, vertical direction) of the powder layer; and binding the powder in the powder layer to form a laminar fabrication structure such as the laminar fabrication structure30in the fabrication part, repeating the forming, the removing, and the binding to fabricate a three-dimensional fabrication object; wherein the amount of the excessively thick powder layer scraped for the last time (e.g., third time) of the multiple times is smaller than that for any other time (e.g., first time).

According to this, as described in Embodiment 1, powder density of the powder layer can be high when the powder is bound in the fabrication to have a predetermined form.

The device100of this embodiment relatively moves the flattening roller12as the flattening member against the fabrication tank22to convey the powder20and at the same time flatten the powder20, thereby forming a powder layer31in the fabrication tank22. During this powder layer forming, a pre-powder layer is formed and the powder20is removed to form the powder layer31. During the pre-powder layer forming, the flattening roller12pushes the powder20into the fabrication tank22to place the powder20all over the fabrication tank22to form the pre-powder layer31a. In addition, during the powder removing, the flattening roller12partially removes the powder20on the top surface side of the pre-powder layer31ato form the powder layer31.

This powder layer forming and structure forming in which the powder20of the powder layer31is bound to have a predetermined form to form the laminar structure30are repeated to form a three-dimensional fabrication object in which the laminar fabrication structure30is stacked.

In addition, in the forming of the powder layer31illustrated inFIG. 28andFIG. 29, to move the flattening roller12that has passed over the fabrication tank22to the initial position (position illustrated inFIG. 28A), the fabrication stage24is elevated to partially return the powder20of the pre-powder layer31ato the supply tank21. This enables to prevent degradation of quality of the solid freeform fabrication object (three-dimensional fabrication object) and simultaneously improve efficiency of use of the powder20.

As the device for fabricating a three-dimensional object to fabricate three-dimensional objects, for example, a device for fabricating a solid freeform fabrication object employing additive manufacturing is known. An example of the device for fabricating the solid freeform fabrication object is known as follows: The device forms a thin layer of flattened powder on a fabrication stage and discharges a liquid fabrication through a head to the formed powder layer to form a thin fabrication layer (laminar fabrication structure30) in which the powder is bound. Thereafter, the next powder layer is formed on the fabrication layer to form another fabrication layer, which is repeated until a solid freeform fabrication object is fabricated.

However, a typical device for fabricating a solid freeform fabrication object reciprocates a flattening member against a fabrication stage to increase powder density of a powder layer, so that the powder inside the formed powder layer is possibly displaced, which leads to degradation of quality of the solid freeform fabrication object.

The device100of this embodiment has a configuration in which at least one of the rotation speed of the flattening roller12and the mobile speed thereof is faster during the powder removing than during the pre-powder layer forming. This enables to prevent displacement of the powder20inside the powder layer31and at the same time increase powder density of the powder layer31, thereby improving the quality of a solid freeform fabrication object.

Next, a first example (Embodiment 2-1) of the powder layer forming of the device100of this embodiment is described.

In Embodiment 2-1, the rotation speed of the flattening roller12during the powder removing is set to be faster than during the pre-powder layer forming. Specifically, using the flattening roller12having a diameter of 10 mm, the rotation speed during the pre-powder layer forming is set to be less than 5 (rps) and the rotation speed during the powder removing is set to be 5 (rps) or greater. In Embodiment 2-1, the mobile speed of the flattening roller12in the horizontal direction along the stage surface during the pre-powder layer forming and the powder removing is set to be 50 mm/s.

The issue of the configuration is described in which both the rotation speed and the mobile speed of the flattening roller12are the same during the pre-powder layer forming and during the powder removing.

A three-dimensional fabrication object was experimentally manufactured under the conditions that the rotation speed was constant at 5 (rps) or greater during the pre-powder layer forming and during the powder removing while the mobile speed of the flattening roller12along the stage surface was kept constant. In this experiment, density of the thus-manufactured three-dimensional fabrication object fluctuated depending on the position along the horizontal direction. Specifically, the powder density decreased toward the portion formed at positions on the downstream side in the direction of movement of the flattening roller12during the pre-powder layer forming. This is inferred because non-uniformity of powder density of the powder layer31occurred depending on the position along the direction of movement of the flattening roller12.

In addition, another three-dimensional fabrication object was experimentally manufactured under the conditions that the rotation speed was constant at less than 5 (rps) during the pre-powder layer forming and during the powder removing while the mobile speed of the flattening roller12along the stage surface was kept constant. In this experiment, occurrence of non-uniformity in density of the thus-manufactured three-dimensional object fluctuating depending on the position along the horizontal direction was reduced. However, the laminar fabrication structure was misaligned in the horizontal direction, thereby degrading the fabrication accuracy of the thus-obtained three-dimensional fabrication object. This is inferred because the flattening roller12applies a force to the powder20in the horizontal direction at the time the powder layer31is formed on the already-formed laminar fabrication structure30, which produces a force to displace the already-formed laminar fabrication structure30in the horizontal direction via the powder20.

Next, the relation between the rotation speed of the flattening roller12and the behavior of the powder20is described with reference toFIGS. 30 and 31.

FIG. 30is a diagram illustrating the relation between rotation speed of the flattening roller12and the behavior of the powder20during pre-powder layer forming.

FIG. 30Ais a diagram illustrating the case in which the rotation speed of the flattening roller12rotating in the direction indicated by an arrow A1 is low (less than 5 rps).FIG. 30Bis a diagram illustrating the case in which the rotation speed of the flattening roller12rotating in the direction indicated by an arrow A1 is high (5 rps or greater).

The arrow B inFIG. 30schematically represents the force of the flattening roller12acting on the powder20.

In the pre-powder layer forming, a gap Δt1 is formed between the upper surface of the already-formed pre-powder layer31bas the powder layer formed by the powder layer forming of the previous pre-powder layer31and the bottom of the periphery of the flattening roller12. On the downstream side (right hand side inFIG. 30) along the direction of movement of the flattening roller12against the bottom of the periphery of the flattening roller12forming this gap Δt1, the powder20is present not forming the pre-powder layer31ayet on the already-formed powder layer31b. This powder20is defined as a powder20bsituated downstream of the roller.

In the case of the low rotation speed illustrated inFIG. 30A, the powder20in contact with the periphery of the flattening roller12tends to trace the surface moving of the flattening roller12so that static friction force easily occurs between the flattening roller12and the powder20. In addition, static friction force tends to act on other powder20in contact with the powder20tracing the surface moving of the flattening roller12,

To the contrary, in the case of the high rotation speed illustrated inFIG. 30B, the powder20in contact with the periphery of the flattening roller12tends not to trace the surface moving of the flattening roller12so that not static friction force but kinetic friction force easily occurs between the flattening roller12and the powder20. In addition, if the powder20traces the surface moving of the flattening roller12in contact with the powder20, the powder20also moves fast. Therefore, the other powder20in contact with this powder20does not easily trace the movement of the powder20moving fast. Therefore, not static friction force but kinetic friction force tends to occur between the powder20tracing the surface moving of the flattening roller12and the other powder20.

In general, static friction force is greater than kinetic friction force. Therefore, the force of the flattening roller12acting on the powder20bsituated downstream of the roller along the direction of movement of the flattening roller12is greater at the low rotation speed at which static friction force tends to occur than the high rotation speed at which kinetic friction force tends to occur.

For this reason, as represented by the arrow B illustrated inFIGS. 30A and 30B, the force of the flattening roller12acting on the powder20is greater at the low rotation speed. Moreover, the component force of the force represented by the arrow B along the direction of the movement (Y2 direction) of the flattening roller12is sufficiently larger at the low rotation speed illustrated inFIG. 30A. However, the component force of the force represented by the arrow B pressing the powder20downward is not much different between the low rotation speed illustrated inFIG. 30Aand the high rotation speed illustrated inFIG. 30B.

Like this embodiment, when the pre-powder layer31ais formed and the pre-powder layer31aon the top surface side is partially removed to form the powder layer31having a predetermined thickness, it is suitable to place a uniform amount of the powder20all over the fabrication tank22along the horizontal direction during the pre-powder layer forming. If there is a site on which the amount of the powder20is insufficient, powder density at the site tends to be insufficient for flattening during the powder removing thereafter. As a result, non-uniformity in density of the powder layer31described above tends to occur.

In addition, if the friction force occurring between the periphery of the flattening roller12and the powder20is too small, the force of conveying the powder20bsituated downstream of the roller in contact with the flattening roller12toward the direction of movement (Y2 direction inFIG. 30) of the flattening roller12during the pre-powder layer forming weakens. For this reason, the ability of conveying the powder20bsituated downstream of the roller in the direction of the movement of the flattening roller12in accordance with the moving of the flattening roller12deteriorates. As a consequence, the amount of the powder20supplied from the supply tank21to the fabrication tank22decreases, which causes shortage of the powder20situated downstream in the direction of movement (downstream in the Y2 direction inFIG. 30) of the flattening roller12in the fabrication tank22during the pre-powder layer forming. This makes it difficult to uniformly place the powder20all over the fabrication tank22in the horizontal direction.

In addition, if a friction force occurring between the periphery of the flattening roller12and the powder20is too weak, the ability of the flattening roller12to convey the powder20bsituated downstream of the roller is weak. This increases the amount of the powder20passing under the flattening roller12moving in the Y2 direction inFIG. 30. Therefore, in the early stage of the pre-powder layer forming, a significant amount of the powder20upstream in the Y2 direction of the fabrication tank22passes under the flattening roller12. This causes shortage of the amount of the powder20downstream in the Y2 direction of the fabrication tank22, which makes it difficult to uniformly place the powder20all over the fabrication tank22.

Therefore, as illustrated inFIG. 30B, for the pre-powder layer forming at a high rotation speed at which kinetic friction force tends to occur between the periphery of the flattening roller12and the powder20, it is thought to be difficult to uniformly place the powder20all over the fabrication tank22.

In Embodiment 2-1, as illustrated inFIG. 30A, the pre-powder layer is formed at a low rotation speed at which static friction force tends to occur between the periphery of the flattening roller12and the powder20. Due to this, friction force occurring between the periphery of the flattening roller12and the powder20can be increased enough to secure the ability to uniformly convey the powder20all over the fabrication tank22. Therefore, it is possible to reduce non-uniformity in powder density of the powder layer31.

In addition, the powder20bsituated downstream of the roller is used to form the pre-powder layer31ain accordance with the moving of the flattening roller12during the pre-powder layer forming, so that the amount of the powder20decreases towards downstream of the flattening roller12. To secure the state in which the powder20bsituated downstream of the roller is present as far as the downstream end in the direction of movement of the flattening roller12in the fabrication tank22, the amount of the powder20of the powder20bsituated downstream of the roller increases upstream in the direction of movement of the flattening roller12in the fabrication tank22. During the pre-powder layer forming, the flattening roller12is moving while holding a significant amount of the powder20so that, at the high rotation speed of the flattening roller12of 5 rps or greater, the powder20easily scatters.

In Embodiment 2-1, the rotation speed of the flattening roller12during the pre-powder layer forming is the low rotation speed of less than 5 rps. Therefore, it is possible to reduce scattering of the powder20during the pre-powder layer forming which easily causes scattering of the powder20.

Whether the rotation speed of the flattening roller12during the pre-powder layer forming is high or low depends on the diameter of the flattening roller12. In embodiments, the diameter of the flattening roller12is 10 mm and the low rotation speed during the pre-powder layer forming is less than 5 rps. In addition, the high rotation speed during the pre-powder layer forming is 5 rps or greater.

FIG. 31is a diagram illustrating the relation between the rotation speed of the flattening roller12and the behavior of the powder20during the powder removing.

FIG. 31Ais a diagram illustrating the case in which the rotation speed of the flattening roller12rotating in the direction indicated by an arrow A2 is low (less than 5 rps).FIG. 31Bis a diagram illustrating the case in which the rotation speed of the flattening roller12rotating in the direction indicated by the arrow A2 is medium (5 to less than 20 rps).FIG. 31Cis a diagram illustrating the case in which the rotation speed of the flattening roller12rotating in the direction indicated by the arrow A2 is high (20 rps or greater).

During the powder removing, the fabrication stage24elevates by Δt2 more than during the pre-powder layer forming. Therefore, as illustrated inFIG. 31, the flattening roller12bites into the pre-powder layer31aformed during the pre-powder layer forming by the height of Δt2.

The arrow C inFIGS. 31A to 31Crepresents the surface moving speed of the flattening roller12and the four outline arrows D inside the powder layer31and the already-formed powder layer31brepresents the distribution of the force acting on inside the powder layer31and the already-formed powder layer31bin the horizontal direction.

As illustrated inFIG. 31A, at the low rotation speed of the flattening roller12, static friction force tends to occur between the flattening roller12and the powder20in contact therewith. Due to the action of the static friction force, which is greater than kinetic friction force, a large force of the flattening roller12is applied to the powder20in the direction of moving (horizontal direction), so that the powder20traces the surface of the flattening roller12and is displaced in the horizontal direction. Due to this displacement of the powder20, a force is applied to the powder20situated therebelow in the horizontal direction due to the static friction force occurring between the powder20displaced and the powder20situated therebelow so that the powder20situated therebelow is displaced in the horizontal direction tracing the powder20situated above. This chain of displacement of the powder20is finally conveyed to the powder20in contact with the already-formed powder layer31bsituated below the powder layer31, which causes dragging and swelling of the laminar fabrication structure30formed inside the already-formed powder layer31b.

Dragging here means a phenomenon in which the laminar fabrication structure30inside the already-formed powder layer31bis dragged in the direction of movement (flatting direction) of the flattening roller12and finally displaced. In addition, swelling here means a phenomenon in which the laminar fabrication structure30inside the already-formed powder layer31bis stretched in the flattening direction so that the dimension of the laminar fabrication structure30is enlarged. Such dragging and swelling of the laminar fabrication structure30degrades the fabrication accuracy of a three-dimensional fabrication object.

In addition, the flattening roller12pushes and moves the powder20in the range of Δt2 of the top surface side of the pre-powder layer31ato be removed in the powder removing in the Y1 direction. At this time, when the flattening roller12rotates at the low rotation speed, the powder20situated in the range of Δt2 does not easily move and a friction force is applied between this powder20and the powder20to remain after the powder removing. Therefore, the force to displace the powder20to remain after the powder removing in the horizontal direction is easily conveyed. This force may also cause dragging and swelling of the laminar fabrication structure30formed in the already-formed powder layer31b.

As illustrated inFIG. 31B, at the medium rotation speed of the flattening roller12, the powder20in contact with the periphery of the flattening roller12does not easily trace the surface movement of the flattening roller12. Therefore, not static friction force but kinetic friction force tends to occur between the flattening roller12and the other powder20. In addition, even if there is the powder20in contact with the surface of the flattening roller12and tracing the surface movement thereof, not static friction force but kinetic friction force tends to occur between this powder20tracing the surface movement and the other powder20in contact with this powder20.

In a state in which kinetic friction force, which is smaller than static friction force, acts on, the force of the flattening roller12acting on the powder20in the direction of movement (horizontal direction) decreases, so that sliding occurs between the periphery of the flattening roller12in motion and the powder20in contact therewith. Therefore, the chain of the displacement of the powder20, which easily occurs at the low rotation speed as described above, does not easily occur. Therefore, it is possible to reduce the force to displace the powder20of the already-formed powder layer31b, thereby reducing the dragging and the swelling of the laminar fabrication structure30in the already-formed powder layer31b.

Moreover, at the medium rotation speed of the flattening roller12, the powder20situated in the range of Δt2 described above is easily displaced. Accordingly, a friction force does not easily act on between the powder20and the powder20to remain after the powder removing. Therefore, the force to displace the powder20to remain after the powder removing in the horizontal direction is not easily conveyed. Therefore, it is possible to reduce the dragging and the swelling of the laminar fabrication structure30in the already-formed powder layer31bascribable to the movement of the powder20pushed by the flattening roller12.

Therefore, in Embodiment 2-1, the powder20is removed not at the low rotation speed at which a static friction force tends to act on between the periphery of the flattening roller12and the powder20but at the medium or high rotation speed at which kinetic friction force tends to act on between the periphery of the flattening roller12and the powder20. This makes it possible to prevent the force of the flattening roller12in the direction of the movement thereof from acting on the powder20of the already-formed powder layer31band the force to displace the laminar fabrication structure30in the horizontal direction from acting thereon. Also, degradation of the fabrication accuracy of a three-dimensional fabrication object can be reduced.

In addition, as indicated by the arrow D inFIGS. 31A and 31B, as the rotation speed increases, the force acting on the powder20by the flattening roller12in the horizontal direction decreases. Also, the force acting on the powder20present below from the powder20present above in the horizontal direction decreases.

However, the force of the flattening roller12pressing the powder20downward (Z2 direction) does not easily fluctuate for the change in the rotation speed and the force of the powder20present above pressing down the powder20present below does not easily fluctuate, either. Therefore, it is possible to maintain increasing powder density of the powder layer31by the force of the flattening roller12pressing down the powder20(Z2 direction) for the change in the rotation speed.

However, as illustrated inFIG. 31C, at the high rotation speed (20 rps or greater) of the flattening roller12, which is further faster than the medium rotation speed, disturbance represented by E inFIG. 31Cappears on the surface of the powder layer31after powder removing, thereby failing to form a flattened surface in some occasions. This is inferred because the scraped powder20interfered the powder layer31to remain after the powder removing.

Whether the rotation speed of the flattening roller12during the powder removing is low, medium, or high depends on the diameter of the flattening roller12. In this embodiment, the diameter of the flattening roller12is 10 mm and the low rotation speed during the powder removing is less than 5 rps. In addition, the high rotation speed during the powder removing is 20 rps or greater. In addition, the medium rotation speed during the powder removing is 5 to less than 20 rps, which is the speed range between the low rotation speed and the high rotation speed.

The rotation speed described above is when the diameter of the flattening roller12is 10 mm. The rotation speed changes as the diameter of the flattening roller12changes. Specifically, at the same rotation speed, the surface moving speed of the periphery of the flattening roller12increases as the diameter of the flattening roller12increases. Therefore, to obtain the effect described above for the pre-powder layer forming an the powder removing, the rotation speed shifts to the lower range.

In addition, at the same rotation speed, the relative speed of the moving speed of the periphery of the flattening roller12against the periphery of the flattening roller12increases as the moving speed of the flattening roller12increases in the horizontal direction. Therefore, to obtain the effect described above for the pre-powder layer forming and the powder removing, the rotation speed shifts to the lower range.

In the configuration forming the pre-powder layer31by the pre-powder layer forming and the powder removing, the force of the flattening roller12acting on the powder20in the horizontal direction is thought to increase to prevent non-uniform powder density of the pre-powder layer31. This is inferred because increasing the force in the horizontal direction secures the ability to convey the powder20in the direction along the surface of the fabrication stage24, which makes it possible to uniformly place the powder20all over the fabrication tank22.

Moreover, at the time of the powder removing, decreasing the force of the flattening roller12acting on the powder20in the horizontal direction is thought to be able to prevent degradation of the fabrication accuracy of a three-dimensional fabrication object. This is inferred because decreasing the force in the horizontal direction reduces the force in the direction of movement of the flattening roller12acting on the powder20of the already-formed powder layer31band the force to displace the laminar fabrication structure30in the horizontal direction.

In Embodiment 2-1, the rotation speed of the flattening roller12during the pre-powder layer forming is low. Therefore, the ability of the flattening roller12to convey the powder20can be secured so that the powder20can be uniformly placed all over the fabrication tank22. Therefore, non-uniform density of a three-dimensional object can be prevented. Moreover, at the medium rotation speed of the flattening roller12during the powder removing, it is possible to reduce the force of the flattening roller12acting on the powder20in the horizontal direction and degradation of the fabrication accuracy of a three-dimensional object. In addition, the powder density of the powder layer31can be increased because the force of the flattening roller12pressing the powder20downward can be maintained at the medium rotation speed of the flattening roller12during the powder removing.

FIG. 32is a schematic diagram illustrating the force acting on individual particles of the powder20during the flattening (pre-powder layer forming or powder removing) of the powder20using the flattening roller12. As illustrated inFIG. 32, the force acting on the individual particles of the powder20differs depending on the position against the flattening roller12and moreover the rotation speed of the flattening roller12.

The difference of the force acting on the collective powder20depending on the rotation speed of the flattening roller12was simulated for comparison.

FIG. 33is a diagram illustrating the results of the simulation in which the force acting on the powder20is separately calculated for different rotation speeds of the flattening roller12.

In this simulation, the condition that the powder20is placed all over on the already-formed powder layer31bin accordance with the pre-powder layer forming and the condition that the powder20is removed on the top layer of the pre-powder layer31ain accordance with the powder removing are separately employed for calculation. The moving speed of the flattening roller12in the horizontal direction is 200 mm/s, and the direction of the movement of the flattening roller12is from right to left inFIG. 33for either of the pre-powder layer forming and powder removing.

The sum of the forces acting on the individual particles of the powder20from start to end of the pre-powder layer forming and the powder removing is separately calculated. Thereafter, the sum of the particles of the powder20is calculated to obtain the total of the force. The lengths of the arrows inFIG. 33represent the sizes of this total of the force and the direction of the arrows indicate the direction of the forces. The direction of the arrow is that 0° is horizontal and 90° is vertical downward. The size of the total of the forces illustrated inFIG. 33is a non-dimensional value.

The arrow in solid line inFIG. 33represents the total of the forces acting on the powder20during the pre-powder layer forming and the arrow in dotted line inFIG. 33represents the total of the forces acting on the pre-powder layer during the powder removing.

As illustrated inFIG. 33, the size of the total of the forces and the angle of the direction of action of the forces change depending on the difference between the pre-powder layer forming and the powder removing or the difference of the flattening roller12.

During the pre-powder layer forming, as the rotation speed increases from 0 rps to 50 rps, the angle of the direction of the action of the force slightly increases from 50° to 60° as indicated by the solid line arrow. Conversely, during the powder removing, the angle significantly increases from 50° to 80° as illustrated in the dotted line arrow.

During the pre-powder layer forming illustrated by the solid line arrow, the size of the total of the forces significantly decreases from 140 to 80 as indicated by the solid line arrow as the rotation speed increases from 0 rps to 50 rps. Conversely, during the powder removing, the size decreases from 100 to 80 as indicated by the dotted line arrow, which is not significant in comparison.

Moreover, during the powder removing, as the rotation speed increases from 0 rps to 50 rps, the component force in the horizontal direction of the total of the forces decreases and the component force vertically downward does not almost change. Inferring from this, for the increase in the rotation speed during the powder removing, the ability of increasing powder density of the powder layer31can be maintained by the force of the flattening roller12pressing downward while reducing the force acting on the already-formed powder layer31bin the horizontal direction.

In the simulation described with reference toFIG. 33, the calculation is made under the condition that the rotation speed of the flattening roller12is 0 rps. However, in a real device, if the rotation speed is set to 0 rps during the pre-powder layer forming suitable for low rotation speed, the laminar fabrication structure30is displaced in the horizontal direction, thereby degrading the fabrication accuracy of a three-dimensional object. For the device100of this embodiment, the rotation speed of the flattening roller12during the pre-powder layer forming is set to 2 rps or greater. A suitable value of the rotation speed of the flattening roller12changes depending on the flowability of the powder20. For the powder20having a high flowability, degradation of the fabrication accuracy of a three-dimensional fabrication object ascribable to the displacement of the laminar fabrication structure30in the horizontal direction can be reduced at a lower rotation speed.

In Embodiment 2-1, the powder20can be uniformly placed all over the total area in the direction of movement of the flattening roller12in the fabrication tank22during the pre-powder layer forming so that the powder layer31can have uniform and high powder density. Moreover, during the powder removing, it is possible to reduce the force of the flattening roller12acting on the powder20to remain as the powder layer31in the direction of movement of the flattening roller12and also prevent the displacement of the laminar fabrication structure30formed on the already-formed powder layer31bas the powder layer present below the powder layer31to be formed. This leads to reduction of the degradation of the fabrication accuracy of a three-dimensional fabrication object.

Next, a second example (Embodiment 2-2) of the powder layer forming of the device100of this embodiment is described.

In Embodiment 2-2, the moving speed of the flattening roller12in the horizontal direction along the stage surface during the powder removing is set to be faster than during the pre-powder layer forming. Specifically, using the flattening roller12having a diameter of 10 mm, the moving speed during the pre-powder layer forming is set to be less than 50 (mm/s) and the moving speed during the powder removing is set to be 50 (mm/s) or greater. In Embodiment 2-2, the rotation speed of the flattening roller12during the pre-powder layer forming and the powder removing is set to be 5 rps.

In Embodiment 2-2, the configuration is the same as that in Embodiment 2-1 except that the rotation speed and the moving speed of the flattening roller12are different.

Next, the relation between the moving speed of the flattening roller12in the horizontal direction and the behavior of the powder20is described with reference toFIGS. 34 and 35.

FIG. 34is a diagram illustrating the relation between the moving speed of the flattening roller12and the behavior of the powder20during the pre-powder layer forming.

FIG. 34Ais a diagram illustrating the case in which the moving speed of the flattening roller12moving in the horizontal direction indicated by the arrow Y2 is low (less than 50 mm/s).FIG. 34Bis a diagram illustrating the case in which the moving speed of the flattening roller12moving in the horizontal direction indicated by the arrow Y2 is high (50 mm/s or greater).

The arrow B inFIG. 34schematically represents the force of the flattening roller12acting on the powder20.

In the case of the low speed moving illustrated inFIG. 34A, the powder20in contact with the periphery of the flattening roller12tends to trace the moving of the flattening roller12so that static friction force easily occurs between the flattening roller12and the powder20. In addition, static friction force tends to be applied to the other powder20in contact with the powder20tracing the moving of the flattening roller12,

Conversely, in the case of the high speed moving illustrated inFIG. 34B, the powder20in contact with the periphery of the flattening roller12tends not to trace the moving of the flattening roller12so that not static friction force but kinetic friction force easily occurs between the flattening roller12and the powder20. In addition, even if there is the powder20in contact with the surface of the flattening roller12and tracing the movement thereof, not static friction force but kinetic friction force tends to occur between this powder20tracing the movement and the other powder20.

As illustrated inFIG. 34B, for the pre-powder layer forming at a high speed moving at which kinetic friction force tends to occur between the periphery of the flattening roller12and the powder20, the friction force occurring between the periphery of the flattening roller12and the powder20may be too small. In this state, the ability to convey the powder20bsituated downstream of the roller in the direction of movement (Y2 direction inFIG. 34) of the flattening roller12during the pre-powder layer weakens and becomes insufficient. As a consequence, the amount of the powder20supplied from the supply tank21to the fabrication tank22decreases, which causes shortage of the powder20present downstream in the direction of movement (downstream in the Y2 direction inFIG. 34) of the flattening roller12in the fabrication tank22during the pre-powder layer forming. This makes it difficult to uniformly place the powder20all over the fabrication tank22.

In addition, if the friction force described above is too weak, the ability of the flattening roller12to convey the powder20bsituated downstream of the roller is weak. This increases the amount of the powder20passing under the flattening roller12moving in the Y2 direction inFIG. 34. Therefore, in the early stage of the pre-powder layer forming, a significant amount of the powder20upstream in the Y2 direction of the fabrication tank22passes under the flattening roller12. This causes shortage of the amount of the powder20downstream in the Y2 direction of the fabrication tank22, which makes it difficult to uniformly place the powder20all over the fabrication tank22.

In Embodiment 2-2, as illustrated inFIG. 34A, the pre-powder layer is formed at a low moving speed at which static friction force tends to occur between the periphery of the flattening roller12and the powder20. Due to this, friction force occurring between the periphery of the flattening roller12and the powder20can be increased enough to secure the ability to uniformly convey the powder20all over the fabrication tank22. Therefore, it is possible to reduce non-uniformity in powder density of the powder layer31.

FIG. 35is a diagram illustrating the relation between the moving speed of the flattening roller12in the horizontal direction and the behavior of the powder20during the powder removing.

FIG. 35Ais a diagram illustrating the case in which the moving speed of the flattening roller12moving in the horizontal direction while rotating in the direction indicated by the arrow A2 is low (less than 50 mm/s).FIG. 35Bis a diagram illustrating the case in which the moving speed of the flattening roller12moving in the horizontal direction while rotating in the direction indicated by the arrow A2 is high (50 mm/s or greater).

The arrow F inFIG. 35represents the moving speed of the flattening roller12in the horizontal direction and the four outline arrows D inside the powder layer31and the already-formed powder layer31brepresent the distribution of the force acting on inside the powder layer31and the already-formed powder layer31bin the horizontal direction.

As illustrated inFIG. 35A, at the low moving speed of the flattening roller12, static friction force tends to occur between the flattening roller12and the powder20in contact therewith. Due to the action of static friction force, which is greater than kinetic friction force, a large force of the flattening roller12is applied to the powder20in the direction of moving (horizontal direction), so that the powder20traces the surface of the flattening roller12and is displaced in the horizontal direction. Due to this displacement of the powder20, a force acts on the powder20situated therebelow in the horizontal direction due to the static friction force occurring between the powder20displaced and the powder20situated therebelow so that the powder20situated therebelow is displaced in the horizontal direction tracing the powder20situated above. This chain of displacement of the powder20is finally conveyed to the powder20in contact with the already-formed powder layer31bsituated below the powder layer31, which causes dragging and swelling of the laminar fabrication structure30formed inside the already-formed powder layer31b. Such dragging and swelling of the laminar fabrication structure30degrades the fabrication accuracy of a three-dimensional fabrication object.

In addition, the flattening roller12pushes the powder20in the range of Δt2 on the top surface of the pre-powder layer31ato be removed during the powder removing along the Y1 direction. At this point, when the flattening roller12moves at low moving speed, the powder20situated in the range of Δt2 does not easily move and a friction force acts on between this powder20and the powder20to remain after the powder removing. Therefore, the force of displacing the powder20to remain after the powder removing in the horizontal direction is easily conveyed. This force may also cause dragging and swelling of the laminar fabrication structure30formed in the already-formed powder layer31b.

As illustrated inFIG. 35B, at the high moving speed of the flattening roller12, the powder20in contact with the periphery of the flattening roller12does not easily trace the movement of the flattening roller12. Therefore, not static friction force but kinetic friction force tends to occur between the flattening roller12and the other powder20. In addition, even if there is the powder20in contact with the surface of the flattening roller12and tracing the movement thereof, not static friction force but kinetic friction force tends to occur between this powder20tracing the movement and the other powder20in contact with this powder20.

In a state in which kinetic friction force, which is smaller than static friction force, acts on, the force of the flattening roller12acting on the powder20in the direction of movement (horizontal direction) of the flattening roller12decreases, so that sliding occurs between the periphery of the flattening roller12during moving and the powder in contact therewith. Therefore, the chain of the displacement of the powder20, which easily occurs at the low moving speed described above, does not easily occur. Therefore, it is possible to reduce the force to displace the powder20of the already-formed powder layer31b, thereby reducing the dragging and the swelling of the laminar fabrication structure30in the already-formed powder layer31b.

Moreover, at the high moving speed of the flattening roller12, the powder20situated in the range of Δt2 described above is easily displaced. Accordingly, a friction force does not easily act on between the powder20and the powder20to remain after the powder removing. Therefore, the force to displace the powder20to remain after the powder removing in the horizontal direction is not easily conveyed. Therefore, it is possible to reduce the dragging and the swelling of the laminar fabrication structure30in the already-formed powder layer31bascribable to the movement of the powder20pushed by the flattening roller12.

Therefore, in Embodiment 2-2, the powder20is removed not at the low rotation speed at which a static friction force tends to occur between the periphery of the flattening roller12and the powder20but at the high moving speed at which kinetic friction force tends to occur between the periphery of the flattening roller12and the powder20This makes it possible to prevent the force of the flattening roller12in the direction of the movement thereof from acting on the powder20of the already-formed powder layer31band the force to displace the laminar fabrication structure30in the horizontal direction from acting thereon. Therefore, degradation of the fabrication accuracy of a three-dimensional fabrication object can be reduced.

Therefore, it is possible to maintain increasing powder density of the powder layer31by the force of the flattening roller12pressing down the powder20(Z2 direction) for the change in the moving speed like Embodiment 2-1, in which the rotation speed is changed.

In Embodiment 2-2, the moving speed of the flattening roller12during the pre-powder layer forming is low. Therefore, the ability of the flattening roller12to convey the powder20can be secured so that the powder20can be uniformly placed all over the fabrication tank22. Therefore, non-uniform density of a three-dimensional object can be prevented. Moreover, at the high moving speed of the flattening roller12during the powder removing, it is possible to reduce the force of the flattening roller12acting on the powder20in the horizontal direction and degradation of the fabrication accuracy of a three-dimensional object. In addition, the powder density of the powder layer31can be increased because the force of the flattening roller12pressing the powder20downward can be maintained at the high moving speed of the flattening roller12during the powder removing.

Whether the moving speed of the flattening roller12during the pre-powder layer forming and the powder removing is high or low depends on the diameter of the flattening roller12. In this embodiment, the diameter of the flattening roller12is 10 mm and the moving speed being low during the pre-powder layer forming and during the powder removing means that the moving speed is less than 50 mm/s. In addition, the moving speed being high during the pre-powder layer forming and during the powder removing means that moving speed is 50 mm/s or greater.

The moving speed described above is when the diameter of the flattening roller12is 10 mm and the rotation speed is 5 rps. However, the moving speed is not limited thereto and changes as the diameter of the flattening roller12or the rotation speed changes. Specifically, at the same moving speed, the relative speed of the periphery of the flattening roller12against the fabrication stage24increases as the diameter of the flattening roller12and the rotation speed increases. Therefore, to obtain the effect described above during the pre-powder layer forming and during the powder removing, the moving speed shifts to the lower range.

In embodiments, to rotate or move the flattening roller12at low speed during the pre-powder layer forming, the densely-packed pre-powder layer31afree of the powder20during the conveyance can be formed. In addition, at the time of the powder removing, the flattening roller12is rotated or moved at high speed. Therefore, if there is the powder20tracing the surface of the flattening roller12, the connection between this powder20and the other powder20is broken and the moving of the powder20forming the powder layer31in the horizontal direction can be reduced. For this reason, while reducing displacement of the powder20forming the powder layer31in the direction of movement of the flattening roller12, the powder20positioned above the powder20forming the powder layer31can be scraped.

In embodiments, the flattening roller12is moved to relatively move against the fabrication tank22. However, it is possible to move the fabrication tank22to relatively move the flattening roller12against the fabrication tank22.

In embodiments, the rotation direction (hereinafter referred to as forward direction) of the flattening roller12is such that the surface moving direction of the flattening roller12at the part thereof facing the fabrication tank22is the same as the moving direction of the flattening roller12against the fabrication tank22. The rotation direction (hereinafter referred to as backward direction) of the flattening roller12can also be such that the surface moving direction of the flattening roller12at the part thereof facing the fabrication tank22is reverse to the moving direction of the flattening roller12against the fabrication tank22.

However, powder density and layer thickness of the powder layer31can be uniformed for the forward direction of the rotation direction of the flattening roller12. The mechanism is as follows:

In the vicinity of the lowermost part of the flattening roller12, a space having a wedge-like form is formed between the periphery of the flattening roller12situated downstream of this lowermost part in the direction of movement of the flattening roller12against the fabrication tank22and a virtual horizontal plane crossing the lowermost part of the flattening roller12.

At the backward direction of the rotation direction of the flattening roller12, the powder20in contact with the flattening roller12in the space having a wedge-like form moves towards the apex of the wedge-like form at which the lowermost part of the flattening roller12is positioned due to the surface moving of the flattening roller12. The powder20that has reached the apex of the wedge-like form due to the surface moving of the flattening roller12tries to enter into the powder20forming the pre-powder layer31aor the powder layer31since there is no way out for the powder20due to the flattening roller12situated above and the pre-powder layer31aor the powder layer31situated below. For this reason, the amount of the powder20below the flattening roller12partially increases. Therefore, the powder layer31formed at the part where the amount of the powder20is increased may partially have high powder density in comparison with the other parts. Moreover, when the excessive powder20reaches below the flattening roller12, the powder20overflows out of the range of a predetermined thickness of the powder layer31, thereby temporarily pushing up the flattening roller12. Therefore, the surface of the powder layer31partially heightens, which may lead to an increase of the layer thickness.

Conversely, at the forward direction of the rotation direction of the flattening roller12, the powder20in contact with the flattening roller12in the space having a wedge-like form moves away from the apex of the wedge-like form due to the surface moving of the flattening roller12. Therefore, it is possible to reduce the partial increase of the amount of the powder20under the flattening roller12and the partial increase of the powder density, so that powder density of the powder layer31can be uniformed. Moreover, the excessive powder20is prevented from reaching under the flattening roller12, so that the surface of the powder layer31does not partially heighten. As a consequence, the layer thickness of the powder layer31can be uniformed.

In the embodiments, for a single operation of the powder layer forming to form a single layer laminar fabrication structure, the powder layer is formed once and the powder are removed once. However, it is also possible to conduct at least one of the powder layer forming and the powder removing multiple times for the single operation of the powder layer forming.

For example, due to the pre-powder layer forming multiple times, the powder20required for the fabrication tank22can be supplied separately in multiple occasions, which makes it possible to prevent an excessive supply of the powder20to a particular site and easily place the powder20all over the fabrication tank22in the horizontal direction.

In addition, due to this multiple-time powder removing, the amount of the powder20to be moved in the horizontal direction by a single powder removing can be lessened. Therefore, the mass of the powder20to be moved in the horizontal direction decreases so that the force acting on the powder20to remain as the powder layer31can be lessened due to the moving of the powder20. As a consequence, the displacement of the powder20forming the powder layer31can be prevented. This prevents the dragging and swelling of the laminar fabrication structure30and degradation of the fabrication accuracy of a three-dimensional fabrication object.

In embodiments, during the pre-powder layer forming, the flattening roller12pushes the powder20from the supply tank21adjacent to the fabrication tank22to supply the powder20to the fabrication tank22and flattens the powder20, thereby forming the pre-powder layer31a.

The configuration of supplying the powder20to the fabrication tank22during the pre-powder layer forming is not limited thereto. For example, it is possible to employ a configuration in which a powder supply unit is disposed above the fabrication tank22, to which the powder20is supplied, and the flattening roller12flattens the supplied powder20and places it all over the fabrication tank22to form the pre-powder layer31a.

In embodiments, the layer thickness of the pre-powder layer31aformed during the single operation of the pre-powder layer forming is thicker than the predetermined thickness of the powder layer31formed during the single operation of the pre-powder layer forming. However, it is also possible to set the layer thickness of the pre-powder layer31aformed in the single operation of the pre-powder layer forming thicker than the layer thickness of the powder layer31if the pre-powder layer forming is repeated multiple times in the single operation of the powder layer forming.

For example, if the pre-powder layer forming and the powder removing are separately repeated twice and the pre-powder layer31ahaving the same thickness as with the powder layer31is formed during the pre-powder layer forming for the first time, a half of the powder20of the formed pre-powder layer31ais removed during the powder removing for the first time. Next, the pre-powder layer31ais formed to add the layer thickness corresponding to the predetermined thickness of the powder layer31during the pre-powder layer forming for the second time and a half of the powder20corresponding to the added layer thickness is removed. The powder layer31having a predetermined thickness can be formed by such powder layer forming operations.

The device100of embodiments employs a binder jet method. The fabrication method to which the configuration of the present disclosure can be applied is not limited to binder jet. Laser sintering (LS), electron beam sintering (EBM), etc. can be employed. In embodiments, a binding device binds powder using liquid discharged from the liquid discharging head. Also, it is possible to use a laser irradiator to sinter and bind powder, etc. The present disclosure can be applied to a solid freeform fabrication method of binding powder in a powder layer.

For binder jet, in general, an inkjet head discharges binder ink to plaster as the powder20to agglomerate the plaster powder to form the laminar fabrication structure30. It is also possible to discharge a binder resin through an inkjet head using sand as the powder20to fabricate a three-dimensional fabrication object that can be used as a casting mold. In addition, in the binder jetting, metal, ceramic, glass, etc. can be used as the powder20. Moreover, in the binder jetting, using the powder20coated with a material soluble in a liquid for binding, it is also possible to discharge the liquid through an inkjet head and bind powder via the material to form the laminar fabrication structure30.

The above-described is just an example and other aspects of the present disclosure are, for example, as follows.

A device for fabricating a three-dimensional object such as the device100for fabricating a three-dimensional fabrication object includes a fabrication part such as the fabrication tank22, a flattening member such as the flattening roller12to place powder such as the powder20in the fabrication tank to form a pre-powder layer such as the pre-powder layer31aand remove the powder on the top surface side of the pre-powder layer to form a powder layer such as the powder layer31while being rotationally driven around a rotation axis orthogonal to a direction of movement of the flattening member against the fabrication tank; and a fabrication unit to bind the powder to form a laminar fabrication object such as the laminar fabrication object31in a predetermined form, wherein the rotation speed of the flattening member is faster during removing the powder on the top surface side of the pre-powder layer than during forming the pre-powder layer, and the laminar fabrication object is formed repeatedly to fabricate the three-dimensional fabrication object.

In this aspect, the rotation speed of the flattening member is slower during the pre-powder layer forming than during the powder removing. The powder in contact with the surface of the flattening member tends to trace the surface of the flattening member so that static friction force easily occurs between the flattening member and the powder. For this reason, the friction force between the flattening member and the powder is relatively large in comparison with the powder removing during which kinetic friction force easily acts on the powder. Therefore, in comparison with the configuration in which the rotation speed during the powder removing is the same as that during the pre-powder layer forming, the configuration of this aspect is capable of conveying the powder more along the flattening direction in accordance with the movement of the flattening member. Due to this conveying capability, it is possible to prevent occurrence of shortage of the powder during conveyance, uniformly place the powder all over the pre-powder layer to be formed, and uniform powder density in the powder layer formed by partially removing the powder of the pre-powder layer.

In addition, in this aspect, the friction force occurring between the flattening member and the powder during the powder removing is relatively small in comparison with during the pre-powder layer forming. Therefore, it is possible to further reduce dragging and swelling of the laminar fabrication structure in the powder layer such as the already-formed powder layer31bsituated below, which may occur during the powder removing, in comparison with the configuration in which the rotation speed and the moving speed are the same during the powder removing and during the pre-powder layer forming. As a result, the dragging and the swelling of the laminar fabrication structure occurring during the powder layer forming are reduced and degradation of the fabrication accuracy of a three-dimensional object is prevented.

In this aspect, it is possible to prevent degradation of fabrication accuracy of a three-dimensional object while uniforming powder density of the powder layer.

Aspect 2-B has the same configuration as Aspect 2-A except that the moving speed of the flattening member such as the flattening roller12against the fabrication part such as the fabrication tank22is faster during the powder removing than during the pre-powder layer forming.

According to this, as described in Embodiment 2-2, during the pre-powder layer forming, it is possible to uniformly place the powder all over the total area in the direction of movement of the flattening member in the fabrication part such as the fabrication tank22so that powder density of the powder layer to be formed can be uniformed. Moreover, during the powder removing, it is possible to reduce the force of the flattening member in the direction of movement thereof acting on the powder to remain as the powder layer and also prevent the displacement of the laminar fabrication structure formed on the powder layer situated below the powder layer to be formed. Therefore, degradation of a fabricated three-dimensional fabrication object can be reduced.

Aspect 2-C has the same configuration as Aspect 2-A or 2-B except that the rotation direction of the flattening member such as the flattening roller12is that the direction of surface moving of the flattening member at the portion facing the fabrication part such as the fabrication tank22is the same as the direction of movement of the flattening member against the fabrication part, i.e., the rotation direction is forward direction.

According to this, as described in the above embodiments, powder density and layer thickness of the powder layer can be uniformed.

A device for fabricating a three-dimensional object such as the device100for fabricating a three-dimensional fabrication object includes a fabrication part such as the fabrication tank22, a flattening member such as the flattening roller12to place powder such as the powder20in the fabrication tank to form a pre-powder layer such as the pre-powder layer31aand remove the powder on the top surface side of the pre-powder layer to form a powder layer such as the powder layer31while being rotationally driven around a rotation axis orthogonal to a direction of movement of the flattening member against the fabrication tank; and a fabrication unit to bind the powder to form a laminar fabrication object such as the laminar fabrication object31in a predetermined form, wherein the moving speed of the flattening member against the fabrication part is faster during the powder removing than the pre-powder layer forming and the laminar fabrication object is formed repeatedly to fabricate the three-dimensional fabrication object.

According to this, as described in Embodiment 2-2, during the pre-powder layer forming, it is possible to uniformly place the powder all over the total area in the direction of movement of the flattening member in the fabrication part such as the fabrication tank22so that powder density of the powder layer to be formed can be uniformed. Moreover, during the powder removing, it is possible to reduce the force of the flattening member in the direction of movement thereof acting on the powder to remain as the powder layer and also prevent the displacement of the laminar fabrication structure formed in the powder layer situated below the powder layer to be formed, thereby preventing degradation of fabrication accuracy of a fabricated three-dimensional fabrication object.

Aspect E has the same configuration as any one of the aspect A to the aspect D except that the pre-powder layer is formed multiple times to form a single powder layer.

According to this, as described in the embodiments, the powder such as the powder20required for the fabrication part such as the fabrication tank22can be supplied in multiple occasions. According to this, it is possible to prevent an excessive supply of the powder at a particular site, which makes it easier to uniformly place the powder all over the fabrication part along the direction of movement (e.g., horizontal direction) of the flattening member such as the flattening roller12over the fabrication part. Therefore, it is possible to uniform powder density of the formed powder layer.

Aspect F has the same configuration as any one of the aspect A to the aspect E except that the powder is removed multiple times to form a single powder layer.

According to this, as described in the embodiments, the amount of the powder such as the powder20moving in the horizontal direction can be reduced in a single operation of the powder removing. According to this, the mass of the powder moving in the direction of movement (e.g., horizontal direction) of the flattening member such as the flattening roller12is reduced so that the force of the flattening member acting on the powder remaining as the powder layer such as the powder layer31due to this movement of the powder can be reduced. Therefore, the displacement of the powder forming the powder layer in the horizontal direction can be prevented and the dragging and the swelling of the laminar fabrication structure such as the laminar fabrication structure30can be also prevented. Therefore, degradation of fabrication accuracy of a three-dimensional fabrication object can be prevented. In addition, the flattening member can press the powder in the fabrication part such as the fabrication tank22multiple times, thereby increasing density of the powder layer.

A method of manufacturing a three-dimensional fabrication object includes placing powder such as the powder20all over the fabrication part such as the fabrication tank22by a flattening member such as the flattening roller12to form a pre-powder layer such as the pre-powder layer31a, removing the powder on the top surface side of the pre-powder layer with the flattening member which is a rotary member that rotates around a rotation axis orthogonal to the direction of movement of the flattening member against the fabrication part to form a powder layer such as the powder layer31, binding the powder of the powder layer in a predetermined form to form a laminar fabrication structure such as the laminar fabrication structure30, and repeating the placing, the removing, and the binding, wherein the rotation speed of the flattening member is faster during the powder removing than the pre-powder layer forming.

According to this, as described in the embodiments, it is possible to prevent degradation of fabrication accuracy of a three-dimensional object while uniforming powder density of the powder layer.

Aspect 2-H is that a method of manufacturing a three-dimensional fabrication object includes placing powder such as the powder20all over the fabrication part such as the fabrication tank22by a flattening member such as the flattening roller12to form a pre-powder layer such as the pre-powder layer31a, removing the powder on the top surface side of the pre-powder layer with the flattening member which is a rotary member that rotates around a rotation axis orthogonal to the direction of movement of the flattening member against the fabrication part to form a powder layer such as the powder layer31, binding the powder of the powder layer in a predetermined form to form a laminar fabrication structure such as the laminar fabrication structure30, and repeating the placing, the removing, and the binding, wherein the moving speed of the flattening member is faster during the powder removing than the pre-powder layer forming.

According to this, as described in the embodiments, it is possible to prevent degradation of fabrication accuracy of a three-dimensional object while uniforming powder density of the powder layer.

Aspect 2-I is that a non-transitory computer readable storage medium storing one or more instructions that, when executed by one or more processors, cause the one or more processors in a device for fabricating a three-dimensional fabrication object such as the device100for fabricating a three-dimensional fabrication object to execute a method of processing setting information, the method of manufacturing a three-dimensional fabrication object includes placing powder such as the powder20all over the fabrication part such as the fabrication tank22by a flattening member such as the flattening roller12to form a pre-powder layer such as the pre-powder layer31a, removing the powder on the top surface side of the pre-powder layer with the flattening member which is a rotary member that rotates around a rotation axis orthogonal to the direction of movement of the flattening member against the fabrication part to form a powder layer such as the powder layer31, binding the powder of the powder layer in a predetermined form to form a laminar fabrication structure such as the laminar fabrication structure30, and repeating the placing, the removing, and the binding, wherein the rotation speed of the flattening member is faster during the powder removing than the pre-powder layer forming.

According to this, as described in the embodiments, it is possible to prevent degradation of fabrication accuracy of a three-dimensional object while uniforming powder density of the powder layer.

Aspect 2-J is that a non-transitory computer readable storage medium storing one or more instructions that, when executed by one or more processors, cause the one or more processors in a device for fabricating a three-dimensional fabrication object such as the device100for fabricating a three-dimensional fabrication object to execute a method of processing setting information, the method of manufacturing a three-dimensional fabrication object includes placing powder such as the powder20all over the fabrication part such as the fabrication tank22by a flattening member such as the flattening roller12to form a pre-powder layer such as the pre-powder layer31a, removing the powder on the top surface side of the pre-powder layer with the flattening member which is a rotary member that rotates around a rotation axis orthogonal to the direction of movement of the flattening member against the fabrication part to form a powder layer such as the powder layer31, binding the powder of the powder layer in a predetermined form to form a laminar fabrication structure such as the laminar fabrication structure30, and repeating the placing, the removing, and the binding, wherein the moving speed of the flattening member against the fabrication part is faster during the powder removing than the pre-powder layer forming.

According to this, as described in the embodiments, it is possible to prevent degradation of fabrication accuracy of a three-dimensional object while uniforming powder density of the powder layer.

According to the present disclosure, it is possible to reduce deterioration of fabrication accuracy of a three-dimensional fabrication object while maintaining powder density of a powder layer high when binding powder to obtain a desired form during fabrication.