MODELING APPARATUS, METHOD, AND ANNEALING APPARATUS

A modeling apparatus is configured to laminate a modeling material to model a three-dimensional modeled object. The modeling apparatus includes a local heating unit, a local cooling unit, and an annealing unit. The local heating unit is configured to locally heat the modeling material during lamination of the modeling material is being laminated. The local cooling unit is configured to locally cool the modeling material during the lamination. The annealing unit is configured to anneal the resultant three-dimensional modeled object at a temperature equal to or higher than a predetermined temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2019-051911, filed on Mar. 19, 2019. The contents of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a modeling apparatus and method, and an annealing apparatus.

2. Description of the Related Art

Recently, modeling apparatuses have come to a wide use, as an apparatus capable of modeling a modeled object without the use of any mold, for example.

For example, when a modeled object is formed using a crystalline resin, the modeled object becomes more susceptible to warping, because, as a result of the modeled object being cooled unevenly in the process of modeling, the modeled object goes through an uneven shrinkage and the internal stress is generated thereby. Japanese Patent No. 6235717 discloses a technology for modeling a modeled object using one or more semi-crystalline polymers, and one or more second materials configured to delay the crystallization of the one or more semi-crystalline polymers.

As a solution for suppressing such warpage, a thin plate, which is referred to as a brim, may be formed around the bottom part of the modeled object. However, depending on the size of the modeled object, it has been difficult to suppress warpage merely with a brim.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a modeling apparatus is configured to laminate a modeling material to model a three-dimensional modeled object. The modeling apparatus includes a local heating unit, a local cooling unit, and an annealing unit. The local heating unit is configured to locally heat the modeling material during lamination of the modeling material is being laminated. The local cooling unit is configured to locally cool the modeling material during the lamination. The annealing unit is configured to anneal the resultant three-dimensional modeled object at a temperature equal to or higher than a predetermined temperature.

DESCRIPTION OF THE EMBODIMENTS

An embodiment has an object to obtain a high-quality three-dimensional object with warpage or deformation suppressed, using a simple structure.

A three-dimensional modeling apparatus according to an embodiment will now be explained in detail with reference to the appended drawings. This embodiment is, however, not intended to limit the scope of the present invention in any way.

As one example of the modeling apparatus, fused deposition modeling will now be explained. With fused deposition modeling, a modeling material containing a thermo-plastic resin is heated and melted to a semi-liquid state. This modeling material is then discharged based on a piece of 3D data representing a three-dimensional modeled object that is to be modeled, and a modeling layer is formed thereby. By laminating modeling layers repeatedly, a three-dimensional modeled object can be formed more easily, compared with other methods.

As a modeling material used in such a fused deposition modeling apparatus, it is possible to use a multi-layered modeling material including a hard-to-handle resin, being hard-to-handle when the modeling material is fabricated or stored, or when a three-dimensional modeled object is manufactured, as a core layer, covered by a super engineering plastic, such as polyetheretherketone, serving as a sheath layer.

One embodiment of the present invention will now be explained with reference to the drawings.

Overall Structure

Explained now is one embodiment of a modeling apparatus that laminates modeling layers on a modeling stage, using a modeling material, and a modeling apparatus for modeling a three-dimensional modeled object using the fused deposition modeling using a filament made of a thermo-plastic resin as a modeling material.

The modeling apparatus is, however, not limited to that using fused deposition modeling using a filament of a thermo-plastic resin, and may be applied to various modeling materials or modeling methods, and it is possible to use any modeling apparatus that models a three-dimensional modeled object on the placement surface of a modeling stage.

FIG. 1is a block diagram illustrating an overall structure of the modeling apparatus. This modeling apparatus100includes a housing101, a placement board102, a shutter104, a slider105, an elevator unit106, a placement board support110.

The housing101has a modeling area101A as a modeling unit, and an annealing area101B as an annealing unit. Specifically, the housing101is divided into two areas, one of which is a modeling area (modeling chamber)101A for performing additive manufacturing, and the other of which is an annealing area (annealing chamber)101B where heat treatment (annealing) is performed on the manufactured three-dimensional modeled object MO at a temperature equal to or higher than a predetermined temperature.

Here, annealing means a treatment for performing heat treatment on the three-dimensional modeled object MO at a temperature equal to or higher than a predetermined temperature to eliminate (remove) distortions caused by a residual stress. When the modeling material has a glass transition temperature, annealing is a heat treatment at a temperature equal to or higher than the glass transition temperature.

The three-dimensional modeled object MO is placed on the placement board102. The placement board102on which the three-dimensional modeled object MO is placed can be moved between the two areas101A,101B by a conveying unit103. The placement board support110is integrated with the placement board102, and supports the placement board102. The term “conveying unit103” herein means the motor, the slider105, and the placement board support110, collectively. The placement board102is conveyed via the placement board support110.

The slider105is disposed in the horizontal direction with respect to the conveying unit103so that the placement board102can be conveyed between the two areas101A,101B.

The annealing area101B has a space in which a plurality of placement boards102can be stacked (housed), and is provided with the elevator unit106capable of driving the placement board102in vertical directions.

The shutter104is a heat-insulating member for adjusting the heat by being opened and closed. The shutter104is provided between the two areas101A,101B. When the placement board102is to be moved, the shutter104is opened to ensure the passage, and then the shutter104is closed. In this manner, these two areas101A,101B are thermally insulated from each other. Therefore, it is possible to maintain the annealing atmosphere in the annealing area101B.

The modeling apparatus illustrated inFIG. 1is a modeling apparatus in which the modeling area101A is integrated with the annealing area101B, but the modeling area101A and the annealing area101B may be separate bodies. Specifically, the modeling apparatus may be implemented as a modeling system including the modeling area101A as a three-dimensional modeling apparatus, and the annealing area101B as an annealing apparatus.

The shutter104is a heat-insulating member for adjusting the heat by being opened and closed. The shutter104is provided between the two areas101A,101B. When the placement board102is to be moved, the shutter104is opened to ensure the passage, and then the shutter104is closed. In this manner, these two areas101A,101B are thermally insulated from each other. Therefore, it is possible to maintain the annealing atmosphere in the annealing area101B.

The modeling area101A and the annealing area101B illustrated inFIG. 1will now be explained with reference toFIGS. 2 and 3.

FIG. 2is a schematic front view illustrating an internal structure of the modeling area. Explanations of the structures assigned with the same reference numerals as those inFIG. 1will be omitted as appropriate. Explanations will be provided denoting the up-and-down direction inFIG. 2as a Z-axis direction, denoting the right-to-left direction of the apparatus as an X-axis direction, and denoting the depth direction of the apparatus as a Y-axis direction.

In the modeling area101A, the placement board support110is provided inside of a treatment space of the housing101, and the three-dimensional modeled object MO is modeled on the placement board102supported on the placement board support110. The modeling area101A includes the housing101, the placement board102, the placement board support110, an modeling module10, a modeling head20, a nozzle21, a heating block22, a cooling block24, an extruder25, local heaters27,29, a reel31, a supporting member28, a Z-axis driving motor41, a Z-axis feed screw42, a Z-axis coordinate detecting mechanism43, placement board guide shafts44, a heating unit400, an X-axis driving motor51, an X-axis feed screw52, an X-axis coordinate detecting mechanism53, an X-axis guide shaft54, a Y-axis driving motor61, a feed screw holding unit61a, a Y-axis feed screw62, a Y-axis coordinate detecting mechanism63, a Y-axis guide shaft64, a nozzle cleaning unit70, a brush71, a brush motor72, a collection box73, a rotating table82, a table rotating motor83, and a motor gear83A.

The placement board guide shafts44penetrate through the placement board support110, near the respective ends of the placement board support110in the X-axis direction. The Z-axis feed screw42penetrates through the placement board102, near one end of the placement board102in Y-axis direction. The placement board support110has a female screw on the inner circumferential surface of a through-hole through which the Z-axis feed screw42is passed. The Z-axis feed screw42is then screwed onto the placement board support110.

The bottom end of the Z-axis feed screw42is connected to the Z-axis driving motor41provided on the bottom surface of the housing101. The Z-axis coordinate detecting mechanism43for detecting the position of the placement board102on the placement board support110in the Z-axis direction is also provided to the bottom surface of the housing101.

As the Z-axis feed screw42is driven in rotation by the driving force of the Z-axis driving motor41, the placement board support110screwed onto the Z-axis feed screw42moves in the Z-axis direction, by being guided along the pair of the placement board guide shafts44, thereby moving the placement board102supported on the placement board support110in the Z-axis direction. The Z-axis driving motor41is controlled based on the detection result of the Z-axis coordinate detecting mechanism43.

The board heating unit400heats the placement board102. The board heating unit400heats a surface of the placement board102, the surface being a surface where the three-dimensional modeled object MO is placed, to a specified temperature.

By heating the placement board102to a specified temperature, cooling of the modeling material layers of the three-dimensional modeled object MO placed on the placement board102is suppressed. In this manner, shrinkage due to the cooling of the modeling material layer is suppressed, so that deformation such as warpage of the three-dimensional modeled object MO can be suppressed.

The reel31having a winding of a filament F that has a thin and long wire shape, which is one example of the modeling material, is rotatably attached to the outer surface of the housing101. The wound filament F is taken out of the reel31by being drawn and rotated by the extruder25that sends out the filament F.

The modeling module10is provided, as a discharging unit, above the placement board102, inside of the modeling area101A. The modeling module10includes the modeling head20, the rotating table82serving as a holding unit, and the supporting member28.

The modeling head20includes the extruder25serving as an introducing unit for sending out the filament F, the cooling block24serving as a cooling unit that cools the filament F, the heating block22that heats and causes the filament F to melt, and the nozzle21serving as a pushing unit through which the melted filament F is pushed out.

The modeling head20models the three-dimensional modeled object MO by pushing out and discharging the melted filament F through the nozzle21, thereby laminating layers made of the modeling material one after another on the placement board102, and by solidifying the laminated layers. A local heater27and a local cooler29are installed near the nozzle21. The local heater27locally heats the three-dimensional modeled object MO while the three-dimensional modeled object MO is being modeled. The local cooler29locally cools the three-dimensional modeled object MO while the three-dimensional modeled object MO is being modeled.

In the modeling module10, two modeling heads20are provided side by side along the Y-axis direction, and these two modeling heads20are integrated, except for their nozzles21.

The rotating table82holds the modeling head20, and the rotating table82is mounted rotatably on the supporting member28.

Among the two modeling heads20provided, the nozzle21of one of the two modeling heads20discharges the melted filament F of the modeling material, with which the three-dimensional modeled object is modeled, and the nozzle21of the other modeling head20discharges the melted filament F of the support material.

The support material is a modeling-support material that is usually made of a material different from the filament F of the modeling material with which the three-dimensional modeled object is modeled, and is removed from the three-dimensional modeled object upon completion of the three-dimensional modeled object. The melted filament F of the support material discharged from the other nozzle21is also laminated in layers one after another, in the same manner as the melted filament F of the modeling material.

The rotating table82is provided rotatably on the supporting member28. The table rotating motor83for rotating the rotating table82is attached to the supporting member28. Outer teeth are provided to the outer circumferential surface of the rotating table82, for example, and are engaged with the motor gear83A of the table rotating motor83. With this structure, the driving force from the table rotating motor83is transferred to the rotating table82, and causes the rotating table82to rotate.

The X-axis guide shaft54and the X-axis feed screw52both of which extend in X-axis direction penetrate through the supporting member28. The supporting member28has a female screw on the inner circumferential surface of a through-hole through which the X-axis feed screw52is passed. The X-axis feed screw52is then screwed onto the supporting member28.

The Y-axis guide shaft64is provided to one end (the left side in the drawing) of the upper part of the housing101in the X-axis direction, and the Y-axis feed screw62is provided to the other end (the right side in the drawing) of the upper part of the housing in the X-axis direction. A member-to-be-guided66is mounted on the Y-axis guide shaft64, in a movable manner along the Y-axis direction. A moving member65is screwed onto the Y-axis feed screw62.

The member-to-be-guided66holds one end of the X-axis guide shaft54and one end of the X-axis feed screw52. The member-to-be-guided66holds the X-axis feed screw52rotatably. The moving member65holds the other end of the X-axis guide shaft54, the X-axis driving motor51, and the X-axis coordinate detecting mechanism53for detecting the position of the modeling module10in the X-axis direction. The other end of the X-axis feed screw52is connected to the X-axis driving motor51. With this structure, the Y-axis feed screw62and the Y-axis guide shaft64hold the supporting member28, supporting elements such as the modeling head20in a manner suspended on the X-axis guide shaft54and the X-axis feed screw52.

One end of the Y-axis feed screw62is rotatably supported by the feed screw holding unit61a, and the other end is connected to the Y-axis driving motor61provided on a side surface of the housing101. On the feed screw holding unit61a, the Y-axis coordinate detecting mechanism63for detecting the position of the modeling module10in the Y-axis direction is mounted.

As the Y-axis feed screw62is driven in rotation by the Y-axis driving motor61, the Y-axis feed screw62screwed on the moving member65is moved in the Y-axis direction. With this movement, the modeling module10held on the moving member65via the X-axis guide shaft54and the X-axis feed screw52is moved in the Y-axis direction, by being guided along the Y-axis guide shaft64. The Y-axis driving motor61is controlled based on the detection result of the Y-axis coordinate detecting mechanism63.

When the X-axis feed screw52is driven in rotation by receiving the driving force of the X-axis driving motor51, the modeling module10is moved in the X-axis direction, together with the supporting member28screwed onto the X-axis feed screw52, by being guided by the X-axis guide shaft54. The X-axis driving motor51is controlled based on the detection result of the X-axis coordinate detecting mechanism53.

The nozzle cleaning unit70for cleaning the nozzle21of the modeling head20is provided inside of the housing101. When the melted filament F is kept being discharged continuously, the filament may become accumulated around the nozzle21, due to the melted filament dripping or residual filament attached to the nozzle21, and proper discharging operations may be obstructed thereby. Therefore, the nozzle needs to be cleaned regularly.

The nozzle cleaning unit70is provided on one end of the placement board102in the X-axis direction, and mainly includes the brush71for removing foreign substances such as the residual filament from the nozzle21, the brush motor72for rotating the brush71, and the collection box73in which the foreign substance removed by the brush71is collected.

The nozzle21is cleaned in the manner described below. To begin with, the placement board102placed on the placement board support110and the modeling module10are moved so that the nozzle21is brought into contact with the brush71. The foreign substances such as the residual filament attached on the nozzle21are then removed by causing the brush motor72to rotate the brush71.

It is preferable to perform cleaning before the temperature of residual filament attached on the nozzle21drops completely, from the viewpoint of adhesion. It is also preferable to use a heat-resistant resin as the brush71.

The foreign substances removed from the nozzle21fall into the collection box73, and collected into the collection box73. The collection box73is provided removably from the placement board support110, and the foreign substances housed in the collection box73removed from the placement board support110are regularly discarded by a worker. Although the collection box73is provided inside of the housing101in this modeling area101A, it is also possible for the collection box73to be provided outside of the housing101, and for the foreign substances removed from the nozzle21by the brush71to be conveyed into the collection box73provided outside of the housing101, using a suction device or the like.

FIG. 3is a schematic front view illustrating an internal structure of the annealing area. Explanations of structures assigned with the same reference numerals as those inFIGS. 1 and 2will be omitted as appropriate. The annealing area101B includes the placement board102, the slider105, the elevator unit106, rods121, a heated-air unit122, an air intake port123, and an exhaust port124.

The placement board support110with the placement board102placed thereon is conveyed from the modeling area101A into the annealing area101B via the slider105.

In the annealing area101B, the elevator unit106becoming engaged with the placement board102and sliding the placement board102upwards is provided so that a plurality of the placement boards102are stored.

The rods121that are extendable and contractible are provided on both sides of the apparatus so that the placement boards102can be stored in the annealing area101B sequentially from the highest level. When the placement board102is elevated by the elevator unit106to a Z coordinate at which the placement board102is able to be stored, the rods121are extended, and the placement board102is placed on the rods121.

An annealing mechanism will now be explained.

The heated-air unit122that is a heat source air source is provided. In the annealing area101B, the heated-air unit122serving as a heat source as well as a blower air source is disposed. The heated-air unit122is provided as a cartridge, and a predetermined number of the cartridges (only two are illustrated inFIG. 3) are disposed on the bottom of the apparatus. In this configuration, it is preferable to give a consideration to positioning of the heated-air units122in such a manner that the heated air does not strike the modeled objects directly.

The air intake port123and the exhaust port124are also disposed, as a slow-cooling mechanism. In this configuration, too, it is preferable to determine how these ports are disposed, through airflow designing, in such a manner that the cooling air does not strike the modeled objects directly, in the same manner as the heated-air unit122.

Crystallization of a modeled object is promoted by designing the airflow through annealing area101B, the air intake port123, and the exhaust port124, and performing control variably in such a manner that the modeled object can go through a temperature change sufficiently gradually. In addition, to detect the temperature inside of the chamber, a temperature sensor (thermocouple) is provided at a plurality of locations, and the amount of air to be supplied by the heated-air unit122and the air intake port123, and the amount of air to be exhausted from the exhaust port124are controlled based on the detection results.

The modeling head20inside of the modeling area101A will now be explained.FIG. 4is a schematic for explaining a general structure of a modeling head. Explanations of structures assigned with the same reference numerals as those inFIG. 2will be omitted as appropriate.

The modeling head20includes the extruder25that sends out the filament F toward the nozzle21, the cooling block24that cools the filament F, the heating block22that heats and causes the filament F to melt, and the nozzle21that discharges the melted filament F. A guide block23for guiding the filament F having passed through the cooling block24to the heating block22is disposed between the cooling block24and the heating block22. A transfer channel26for transferring the filament F sent out of the extruder25into the nozzle21is provided inside of the heating block22, the guide block23, the cooling block24.

The heating block22includes a heat source (heater)22athat functions as a heating unit for heating the filament F, and a thermocouple22bserving as a temperature detecting unit that detects the temperature of the filament F heated by the heat source22a.

The thermocouple22bis positioned on the opposite side of where the heat source22ais disposed, with the transfer channel26through which the filament F is transferred interposed therebetween. The heating block22heats and causes the filament F in the transfer channel26to melt. The melted filament Fa is then transferred to the nozzle21.

It is unfavorable for the heat from the heating block22to propagate to the filament F upstream in the transfer channel26and to cause the filament F to melt, in addition to the filament F inside of the transfer channel26.

Specifically, when the heating block22stops heating, or when the heating operation thereof is interrupted, the melted filament F in the transfer channel26solidifies in the transfer channel26. When the heating by the heating block22is then restarted, the filament F having a history of having melted and solidified in the transfer channel26quickly becomes melted again.

If the filament F has melted and solidified on the upstream side of the transfer channel26in the transfer direction, however, it takes some time for this part of the filament F to become melted again when the heating is restarted.

As a result, the filament F becomes clogged, without being transferred into the nozzle21.

Hence, it is desirable to suppress such clogging of the filament F by preventing the heat of the heating block22from being propagated to the upstream filament F in the transfer channel26in the transfer direction, as much as possible.

To address this point, the cooling block24is provided on the upstream side of the transfer channel26of the heating block22, in the transfer direction.

The cooling block24is made of a highly thermally conductive material, such as aluminum, and a channel24athrough which coolant flows is provided around the transfer channel26in the cooling block24. The cooling block24cools the filament F by allowing the heat of the filament F in the transfer channel26to transfer to the coolant flowing through the channel24a.

As a result, the filament F in the upstream section of the transfer channel26in the heating block22in the transfer direction is prevented from melting by the heat propagated from the heating block22.

The guide block23disposed between the heating block22and the cooling block24is made of a heat-insulating material, and suppresses propagation of the heat from the heating block22to the filament on the upstream side in the transfer direction. The guide block23further suppresses melting of the filament F in the upstream section in the transfer direction of the transfer channel26in the heating block22by the heat propagated from the heating block22. In addition, by suppressing the propagation of the heat from the heating block22to a section of the filament F other than the section in the transfer channel26, the filament F in the transfer channel26can be heated efficiently.

A pair of feeder rollers25aare provided to the extruder25, and feed the filament F into the transfer channel26. The melted filament Fa having been heated in the heating block22and become melted is discharged from the nozzle21, by receiving the feeding force of the extruder25.

FIG. 5is a block diagram illustrating an overall structure of a driving control system for the modeling head. As driving control of the modeling head20, at least a heating temperature control unit202, an extrusion amount control unit203, a driving control unit204, a local heating/cooling control unit205, a coordinate detecting unit80, a driving unit90, a modeled object surface temperature detecting unit81, and the driving unit90are provided.

FIG. 6is a block diagram illustrating an overall structure of a control system for the modeling apparatus. As a control device200for the modeling apparatus100, at least a data generating unit201, the heating temperature control unit202, the extrusion amount control unit203, the driving control unit204, the local heating/cooling control unit205, the coordinate detecting unit80, the driving unit90, the modeled object surface temperature detecting unit81, and the driving unit90, a micro-processing unit (MPU)402, a random access memory (RAM)404, a read-only memory (ROM)406, and a non-volatile memory408are provided. The structures assigned with the same reference numerals inFIGS. 5 and 6are common elements, so these elements will now be explained with reference toFIGS. 5 and 6.

The control device200functioning as a control unit is configured as what is called a micro-computer, and includes the MPU402functioning as a processing unit, the RAM404, the ROM406, and the non-volatile memory408functioning as a data storage unit. The control device200then performs various operations and executes control programs.

The driving unit90includes the X-axis, Y-axis, and Z-axis driving motors41,51,61, the table rotating motor83, and the X-axis, Y-axis, and Z-axis coordinate detecting mechanisms43,53,63.

The data generating unit201generates data that is broken up into multiple layers in the up-and-down direction (slice data for modeling a modeled object) based on modeled object data received from an external device such as a personal computer that is data-communicatively connected to the modeling apparatus100over the wire or wirelessly.

The slice data corresponding to each layer corresponds to a layer formed with the filament F discharged from the modeling head20, and the thickness of each layer is set as appropriate, depending on the capacity of the modeling apparatus100. It is also possible to configure an external device to generate slice data, and to input the slice data to the modeling apparatus100.

The slice data is described as G-code text data having an extension “.gcode”, for example.

The text data with an extension “.gcode” basically includes descriptions of the following three types of data, excluding a preparation operation and an ending operation of the main unit:

(1) data specifying the coordinates of the vertices of the modeled object;

(2) data specifying the speed at which the nozzle21of the modeling head20is moved to each vertex of the modeled object; and

(3) data specifying the rate at which the filament F is fed.

In this example, the data specifying the filament feed rate includes data related to the timing to start feeding, and timing to stop feeding.

The data generating unit201also generates data of heating temperature, for example, in addition to the slice data.

The data generating unit201transmits the data specifying the heating temperature to the heating temperature control unit202.

As a result of this, the heating temperature control unit202feedback-controls the heat source22aof the heating block22based on the temperature detection result of the thermocouple22bso that the heating temperature is adjusted to the specified heating temperature received from the data generating unit201.

In order to ensure the temperature stability of the nozzle21in the modeling head20, it is preferable for the heating temperature control unit202to start its operation before the filament feeding operation is started, so that the heating block22has been heated to the specified heating temperature before the filament feed operation is started. Specifically, it is preferable to predict the timing at which the filament feed operation is to be started based on data for causing feeding of the filament F to be started and the data representing the vertices of the modeled object, and to perform feed-forward control to control the heat source22a. It is also possible to use a feedback operation to start a modeling operation when the thermocouple22bdetects that the temperature has reached the specified heating temperature.

The filament feed rate data generated by the data generating unit201is sent to the extrusion amount control unit203. In response, the extrusion amount control unit203controls the extruder25so that the filament feed rate is adjusted to the filament feed rate received from the data generating unit201.

Before stopping discharging the filament F from the nozzle21(before stopping driving the extruder25), the extrusion amount control unit203drives the extruder25to be rotated reversely to perform an operation for drawing the filament F back into the nozzle21. By performing such a sucking operation, it is possible to suppress dripping of the filament F from the nozzle21, and to improve the precision of the shape of the three-dimensional modeled object MO.

The data specifying the coordinate of the vertices of the modeled object and the speed data specifying the speed for moving the nozzle21of the modeling head20to each of the modeled object vertices, generated by the data generating unit201, are also sent to the driving control unit204. In response, the driving control unit204controls the motors41,51,61,83based on these pieces of data. The driving control unit204also performs feedback control for moving the nozzle21to the target coordinate point based on the detection result of the coordinate detecting mechanisms43,53,63, so as not to result in an improper operation.

The extrusion amount control unit203is synchronized with the driving control unit204, and the amount of the filament F to be extruded (feed rate) and starting/stopping of feeding of the filament F are controlled in accordance with the operation of the modeling head20.

A surface treatment control unit205is also synchronized with the driving control unit204, and controls the local heater27that locally heats the three-dimensional modeled object MO, and the local cooler29that locally cools the three-dimensional modeled object MO in accordance with the movement of the modeling head20, while the three-dimensional modeled object MO is being modeled, the local heater27and the local cooler29being provided internal of the modeling head20.

In other words, the surface treatment control unit205suppresses a huge volume change of the modeling material by suppressing crystallization of the melted crystalline material, and allowing the material to amorphize (to go through glass transition), by controlling the local heater27locally heating the three-dimensional modeled object MO while the three-dimensional modeled object MO is being modeled.

An example of a possible specific structure of the local heater27includes a device irradiating a position to be heated with a laser beam, using a laser diode (LD).

The surface treatment control unit205can alleviate the residual stress generated while the layers are being laminated, by controlling the local cooler29for locally cooling the three-dimensional modeled object MO while the three-dimensional modeled object MO is being modeled, and by cooling the modeling material quickly after the modeling material is discharged.

As an example of a specific structure of the local cooler29, it is possible to use a device that sprays compressed air toward a position to be cooled, via an air nozzle.

However, if the three-dimensional modeled object MO is kept in an amorphous state, properties inherent to crystalline materials cannot be achieved. Therefore, in this embodiment, the three-dimensional modeled object MO having been modeled is transferred to and annealed in the annealing area101B, so that the three-dimensional modeled object MO is crystallized and the properties inherent to crystalline materials (such as mechanical characteristics and chemical resistance thereof) are achieved.

An operation according to the embodiment will now be explained.

When a modeling operation is started in response to an instructing operation performed by a user, to begin with, the control unit200starts conducting current to the heat source22aof the heating block22, and heats the heating block22to a heating temperature based on modeled object data generated by the data generating unit201.

The Z-axis driving motor41is controlled by the driving control unit204to elevate the placement board support110supporting the placement board102to a modeling position, from a predetermined standby position (e.g., the lowest level).

Upon detecting that the placement board102has reached the modeling position, the Z-axis coordinate detecting mechanism43stops the Z-axis driving motor41, and the control is shifted to a modeling process.

In the modeling process, to begin with, a modeling material layer corresponding to the bottom layer is created on the surface of the placement board102, based on the slice data of the bottom layer (first layer). Specifically, the X-axis driving motor51and the Y-axis driving motor61are controlled by the driving control unit204based on the slice data of the bottom layer (first layer), and detection results of the X-axis coordinate detecting mechanism53and the Y-axis coordinate detecting mechanism63. As a result, the tip of the nozzle21in the modeling head20is moved sequentially to target positions (target positions on the X-Y plane).

In synchronization with the driving control of the driving control unit204, the extruder25is controlled by the extrusion amount control unit203so that the filament F is fed via the nozzle21based on the slice data. As a result, as the tip of the nozzle21of the modeling head20is moved sequentially to the target positions, the filament is discharged from the nozzle21, and a modeling material layer is formed on the placement board102in accordance with the slice data of the bottom layer (first layer). The support material, which does not constitute the three-dimensional modeled object, may be created at the same time.

In synchronization with the driving control of the driving control unit204, the surface treatment control unit205also control the local heater27for locally heating the three-dimensional modeled object MO, and to control the local cooler29for locally cooling the three-dimensional modeled object MO, to suppress crystallization and to alleviate the residual stress in laminating.

Upon completion of the process of modeling the bottom layer in accordance with the slice data of the bottom layer (first layer) (unit layer modeling process), the driving control unit204controls the Z-axis driving motor41based on the detection result of the Z-axis coordinate detecting mechanism43, and descends the placement board102by a distance corresponding to the one layer of the modeling material layers.

The X-axis driving motor51and the Y-axis driving motor61are then controlled by the driving control unit204based on the slice data of the second layer, so that the tip of the nozzle21of the modeling head20is moved sequentially to the target positions. At the same time, the extruder25is controlled by the extrusion amount control unit203so that the filament F is fed via the nozzle21. As a result, a second layer is formed, in accordance with the slice data, on top of the bottom layer having been formed on the placement board102.

Once modeling of the layers is completed, the surface temperature is obtained, using a modeled object surface temperature detecting unit81such as a thermal camera or a thermography. As a result, even when a modeled object is a piece having an intended thickness deviation, it is possible to recognize the temperature deviation of the modeled object at the time of measurement. Furthermore, by feeding this information back to the local heating/cooling control unit205, it is possible to control the heating and cooling initially planned to be output, in such a manner that the outputs can be maintained at an appropriate level.

If a temperature deviation is resultant of a thickness deviation, as mentioned above, feedforward control can be performed based on the modeled object data entered by a user. However, because the modeling apparatus100according to the embodiment does not have any means for controlling the ambient temperature, such as that inside the chamber, it is necessary to consider the ambient temperature/humidity as an error factor.

Therefore, it is preferable to perform the feedback control using the modeled object surface temperature detecting unit81at the same time, in order to ensure a stable quality.

In the manner described above, by repeating the operation of laminating the layers of the modeling material, sequentially from the bottom layer, while controlling the Z-axis driving motor41to descend the placement board support110, thereby causing the placement board102be lowered sequentially, the three-dimensional modeled object MO is modeled on the placement board102, in accordance with the three-dimensional modeled object data.

When modeling of the three-dimensional modeled object MO is completed, the Z-axis driving motor41is controlled to descend the placement board support110and the placement board102to the standby position.

When a shutter103is then opened, the placement board support110on which the placement board102is placed is conveyed from the modeling area101A into the annealing area101B via the slider105.

Once the placement board support110on which the placement board102is placed is conveyed into the annealing area101B, the placement board102becomes engaged with the elevator unit106, and the elevator unit106conveys the placement board102upwards by sliding.

The placement board support110is then returned to the modeling area101A via the slider105, and the shutter103is closed.

When the elevator unit106elevates the placement board102to a Z coordinate where there is an available storage space, the rods121are extended, and the placement board102is placed on top of the rods121, and annealed for predetermined time so that the crystallization of the three-dimensional modeled object MO is promoted.

As a result, according to the embodiment, even when a crystalline or semi-crystalline material is used as the modeling material of the three-dimensional modeled object MO, the three-dimensional modeled object MO can be brought to the state inherent to the modeling material (crystallized or semi-crystallized state). Therefore, a high mechanical strength and chemical resistance can be ensured.

Explained above is an example of the modeling apparatus100having a modeling area (modeling chamber) and an annealing area (annealing chamber), but it is also possible to use a modeling system in which a modeling apparatus having a modeling area is connected to an annealing apparatus having an annealing area (annealing chamber) via a conveyor apparatus having a heat-insulating mechanism, and in which the three-dimensional modeled object MO having been modeled in the modeling apparatus is conveyed into the annealing apparatus via the conveyor apparatus, in a manner insulated from the heat, and then annealed in the annealing apparatus. Even when the conveyor apparatus does not have any heat-insulating mechanism, as long as the conveyor apparatus is capable of transferring the three-dimensional modeled object MO before the temperature goes out of a predetermined temperature range, such a structure is also usable, likewise.

Explained above is an example of the fused deposition modeling, but even with another three-dimensional modeling method, it is possible to achieve a three-dimensional modeled object exhibiting even higher performance, with the internal stress reduced.

EXAMPLES

More specific examples will now be explained.

Modeling conditions inside of the modeling area101A and evaluations of samples of the modeled three-dimensional modeled object MO will now be explained.

FIG. 7is a schematic for explaining modeling conditions and results of qualitative evaluations of the examples and some comparative examples. As an evaluation of warpage, the warpage and the lamination strength were evaluated for each example.

Modeling Apparatus

The modeling apparatus having performed the manufacture according to the examples and the comparative examples has a structure illustrated inFIGS. 2, 4, 5, and 6, with additional structures described below.

As the extruder25, two rollers having a diameter of 12 [mm] and manufactured by SUS304 were used side by side.

As the nozzle21, a nozzle made of brass and having an opening with a size of 0.5 [mm] at the tip was used.

As the filament passage in the modeling head20, a passage having a diameter of 2.5 [mm] was used. The diameter of the transfer channel26in the heating block22was also set to 2.5 [mm].

Modeling Material

In the examples and the comparative examples, as the modeling material, either PLA (polylactic acid manufactured by Polymaker, under the product name PolyLite PLA, model number: PolyLite PLA11-natural) or PEEK (polyetherketone manufactured by Victrex, with a model number 381G, and ISO11357 compliant glass transition temperature of 143 degrees Celsius) was used. As the modeling material, a filament having a diameter of ϕ1.75 was used.

Temperature Condition

As the cooling block24, a cooling block manufactured by SUS304 and having a conduit pipe was used, and the cooling water circulation device was connected to the conduit pipe. The temperature setting of the cooling water circulation device was set to 10 [° C.]. As the heating block22, a heat block having the same structure as the cooling block24was used, and a fluid circulation device was connected to the conduit pipe. A cartridge heater was then disposed inside of the conduit pipe of the heating block22, and power supply to the cartridge heater was controlled in such a manner that the cartridge heater was turned ON/OFF based on the detection result of the thermocouple22b.

The temperature setting of the cartridge heater was configured to 200 [° C.] when PLA was used as the modeling material, and set to 400 [° C.] when PEEK was used as the modeling material.

In all of these tests, the modeling speed was set to 20 mm/sec.

Cooling Condition

In the examples and the comparative examples, experiments were carried out with and without cooling by the local cooler29, and the results were compared. In the experiments with the cooling, 12 kPa was used as a cooling condition. As the local cooler29, a precision regulator (cooling nozzle) installed in a piping route was used.

Heating Condition

In the examples and the comparative examples, experiments were carried out with and without the heating by the local heater27, and the results were compared. The heating condition was set to 4 W to 12 W, and this condition was changed for each of the experimental examples and the comparative examples. As the local heater27, a semiconductor laser (LD) was used. The wavelength of the LD was set to 780 nm.

The examples and the comparative examples were then evaluated qualitatively, in views of warpage of a cuboid, and the strength in the lamination direction.

Three-Dimensional Modeled Object MO and Evaluation Method Used in Qualitative Evaluations of Warpage of Cuboid

As a three-dimensional modeled object MO used in the qualitative evaluation of warpage in a cuboid, a cuboid-shaped modeled object having a size of W30×D30×H7.5 (mm) was used. While the amount of warpage can be measured with a height gauge as long as the warpage is in the order of a few millimeters or so, but it is also possible to use a contactless 3D scanner or the like and to obtain a cross-sectional profile of the modeled object. When a 3D scanner is to be used, the amount of warpage can be measured easily by calculating a difference with respect to the modeled object data entered by a user.

Three-Dimensional Modeled Object MO and Evaluation Method Used in Qualitative Evaluations of Strength in Lamination Direction

FIGS. 8A and 8Bare schematics for explaining three-dimensional modeled objects used in evaluating the strength in the lamination direction.

From the viewpoint of modeling a three-dimensional modeled object, a cuboid modeled object, such as that illustrated inFIG. 8A, is easy to manufacture. However, as a standard for tensile tests, it is preferable for the modeled object to have a dumbbell shape, as illustrated inFIG. 8B.

When a dumbbell shape is to be modeled in the lamination direction, the part above the constricted portion has an overhanging shape, so this part generally requires a support region.

Therefore, to avoid formation of very small notches on the surficial shape as much as possible when the support region was removed, the inventors of the present invention obtained a three-dimensional modeled object MO that is a sample having the dumbbell shape illustrated inFIG. 8B, by modeling the cuboidal three-dimensional modeled object MO illustrated inFIG. 8A, and then cutting the modeled object into the cuboidal three-dimensional modeled object MO, and used the resultant three-dimensional modeled object MO in the evaluation of the strength in the lamination direction. The evaluation of the strength in the lamination direction was carried out using the method compliant to ASTM-D638.

First Comparative Example/Second Comparative Example

In a first comparative example and a second comparative example, PLA was used.

In the first comparative example, only the local cooler29was used, among the local heater27and the local cooler29.

In the second comparative example, only the local heater27was used, among the local heater27and the local cooler29. The heating condition was set to 8 W.

Third Comparative Example/Fourth Comparative Example/Fifth Comparative Example/Sixth Comparative Example

In a third to a sixth comparative examples, PEEK was used.

In the third comparative example, only the local cooler29was used, among the local heater27and the local cooler29.

In the fourth comparative example, only the local heater27was used, among the local heater27and the local cooler29. The heating condition was set to 8 W.

In the fifth comparative example and the sixth comparative example, the local heater27and the local cooler29were both used. In the fifth comparative example and the sixth comparative example, different heating conditions were used for the local heater27. In the fifth comparative example, the heating condition was set to 4 W. In the sixth comparative example, the heating condition was set to 12 W.

In a first to a third examples, PEEK (polyetheretherketone) was used, in the same manner as in the third to the sixth comparative examples, and the local heater27and the local cooler29were both used. In the first to the third examples, different heating conditions were used for the local heater27. In the first example, the heating condition was set to 6 W. In the second example, the heating condition was set to 8 W. In the third example, the heating condition was set to 10 W.

Results of Qualitative Evaluations of Warpage of Cuboid and Results of Qualitative Evaluations of Strength in Lamination Direction

Evaluation results of the comparative examples and the examples will now be explained.

First Comparative Example/Second Comparative Example

In both of the first and the second comparative examples, warpage was well-controlled.

However, in the first comparative example in which only the local cooler29was used, a desirable level of interfacial strength in the lamination direction was not achieved, and the strength remained at a level where the sample could be easily destroyed with hands. Therefore, a high lamination strength was not achieved.

Third Comparative Example

In the third comparative example, the modeled object warped extensively.

Not only the warpage was extensive, many cracks were found on the ends of the modeled object. In addition, an interfacial peeling phenomena, in which the layers peel off from one another along the cracks, were observed along the interface between the layers. It can be said that heating by the local heater27was required.

Fourth Comparative Example

In the fourth comparative example, the samples exhibited a high lamination strength but warped extensively, with the surface of the brim warping highly extensively. It can be said that cooling by the local cooler29was required.

Fifth Comparative Example

In the fifth comparative example, the sample warped extensively. Not only the sample warped extensively, two cracks were found on the ends of the modeled object. In addition, the interfacial peeling phenomena, in which the layers peel off from one another along the cracks, were observed along the interface between the layers. Therefore, it can be said that the heating by the local heater27was not strong enough.

First Example, Second Example, Third Example

In the first to the third examples, not only the warpage was well-controlled, but also the samples exhibited a high strength in the lamination direction.

Sixth Comparative Example

In the sixth comparative example, the sample was burnt, and neither the warpage was well-controlled, nor the sample exhibited a high strength in the lamination direction. It can be said that the heating by the local heater27was too strong.

As explained above, in the first to the third examples, conditions achieving a well-balanced combination of the warpage and the lamination strength were found within the range of 6 W to 10 W as the output settings of the LD that is the local heater27. It can be concluded that, when the cooling is relatively stronger, the lamination strength is not ensured, and when the cooling is weaker, conversely, a deterioration such as burning is promoted. Therefore, in the example illustrated inFIG. 7, when the heating condition of the local heater27was set equal to or higher than 6 W and equal to and lower than 10 W and the cooling condition of the local cooler29was set to 12 kPa, a modeled object with satisfactory levels of warpage and lamination strength was obtained, successfully.

However, these examples are provided by way of examples only, and it should be clear that the appropriate heating and cooling conditions vary, depending on the thermal capacity of the modeled object and the feed rate. Furthermore, when the modeled object has a complex shape, it is preferable to perform feedback-control of the means for heating and for cooling, using a surficial temperature profile obtained using a thermal camera, instead of using a fixed output, as did in these examples.

FIG. 9is a schematic for explaining quantitative evaluations of the amount of warpage in three-dimensional modeled objects achieved with a fixed laser output.

InFIG. 9, evaluations were carried out with the LD output fixed to 6 W, as the heating condition of the local heater27.

In the evaluations, PEEK 381G was used as the modeling material, and, as the same other conditions, such as the modeling apparatus and the temperature condition, were used as those explained withFIG. 7. No measurement was collected with a cooling condition of 20 kPa, because it was highly likely for the sample to break. The measurements were collected under the cooling conditions of 0, 6, 8, 10, 12, 14, and 16 kPa, respectively.

In the same manner as in the comparative example illustrated inFIG. 7, when there was no cooling by the local cooler29(with the cooling condition of 0 kPa), the sample exhibited the largest amount of warpage. The obtained results were very different depending on the air-cooling condition of the local cooler29, and this evaluation indicated that the warpage was reduced when the cooling condition is equal to or more than 10 kPa. Specifically, a range equal to or higher than 10 kPa and lower than 20 kPa is preferable, and a range equal to or higher than 10 kPa and equal to and lower than 16 kPa is more preferable.

It has been also confirmed that the actually modeled three-dimensional modeled object MO had an opaque color, indicating that the modeled object went through a glass transition.

FIG. 10is a schematic for explaining evaluation results of breaking stress when tensile tests were carried out with a regulator pressure setting fixed.

In the example illustrated inFIG. 10, the regulator pressure setting is fixed to 10 kPa, as a cooling condition of the local cooler29.

In this evaluation, PEEK 381G was used as the modeling material, and the same other conditions, such as the modeling apparatus and the temperature conditions, as those explained with reference toFIG. 7, were used.

Without the heating by the local heater27(with a heating condition of 0 W), the breaking stress was 0 W.

As illustrated inFIG. 10, it was confirmed that, as the output of the LD serving as the local heater27(laser PW) was increased, the breaking strength improved further. In other words, when the heating condition by the local heater27was changed from 2 W to 10 W, the breaking strength improved.

An experiment was also carried out by setting the heating condition of the local heater27to LD output=12 W, but this result was excluded from the evaluation, because the three-dimensional modeled object MO was burnt. Based on the above, from the viewpoint of the breaking strength, it is preferable for the heating condition by the local heater27to be set to a level greater than 0 W and equal to or lower than the 12 W, and it is more preferable to be set to a level equal to or higher than 2 W and equal to or lower than 10 W. Furthermore, it is preferable for the cooling condition to be set to 10 kPa, and for the heating condition by the local heater27to be set to a level greater than 0 W and equal to or lower than 12 W, and it is more preferable be set to a level equal to or higher than 2 W and equal to or lower than 10 W.

As illustrated inFIGS. 9 and 10, the effects achieved by cooling and heating are in the trade-off relation, but it is possible to find a condition in which both of a warpage reduction and a high lamination strength are achieved.

Annealing conditions in the annealing area101B, and evaluations of the resultant samples of the three-dimensional modeled object MO will now be explained.

FIG. 11is a schematic for explaining annealing conditions, and evaluation results of tensile elasticities of the resultant three-dimensional modeled objects.

Samples of Three-Dimensional Modeled Object MO

In the first example, a first example A, and a first example C illustrated inFIG. 11, the three-dimensional modeled object MO according to the first example illustrated inFIG. 7was annealed under the annealing conditions described below.

In the second example, a second example A, and a second example C illustrated inFIG. 11, the three-dimensional modeled object MO according to the second example illustrated inFIG. 7was annealed under the annealing conditions described below.

In the third example, a third example A, and a third example C illustrated inFIG. 11, the three-dimensional modeled object MO according to the third example illustrated inFIG. 7was annealed under the annealing conditions described below.

The samples illustrated inFIG. 11were provided with a dumbbell shape, in the same manner as that illustrated inFIG. 8B, and were used in evaluating the strength in the lamination direction. Because the samples of the three-dimensional modeled object MO achieved by performing the local heating and local cooling inFIG. 7were those having gone through glass transition, the tensile elasticity in the crystallized condition, which is inherent to PEEK 381G, was not indicated in the tensile test.

Annealing Conditions

In the first example 1 to the third example 3, the samples were not annealed at all. By contrast, the samples according to the first to the third examples A, the samples according to the first to the third examples B, and the samples according to the first to the third examples C were classified into these three groups, and each of these group was annealed under the same condition. The samples were annealed and crystallized by controlling the heated-air unit122, the air intake port123, and the exhaust port124in the annealing area101B illustrated inFIG. 3. For all of the samples, the evaluations were carried out by setting the heating-starting temperature to 30 degrees Celsius, the highest attainment temperature to 180 degrees Celsius, and the temperature after the cooling to 30 degrees Celsius.

In the first to the third examples A, the temperature increase rate was set to 1° C./min, the temperature sustained time was set to 30 minutes, and the cooling rate was set to 1° C./min.

In the first to the third examples B, the temperature increase rate was set to 1° C./min, the temperature sustained time was set to 1 minute, and the cooling rate was set to 1° C./min.

In the first to the third examples C, the temperature increase rate was set to 3° C./min, the temperature sustained time was set to 1 minute, and the cooling rate was set to 3° C./min.

The highest attainment temperature for the annealing was set to 180 degrees Celsius. This temperature was set considering a temperature sufficiently exceeding the glass transition temperature of the modeling material, and at which the shape of the three-dimensional modeled object MO can be maintained.

Evaluations of Tensile Elasticity

In the tensile elasticity evaluations, the tensile elasticities were calculated using the least-squares method within a load range of 10-20 N.

Results of Tensile Elasticity Evaluations

The tensile elasticity achieved in the tensile test of the sample of the three-dimensional modeled object MO in the first example was 0.49 GPa. The tensile elasticity achieved in the tensile test of the sample of the three-dimensional modeled object MO in the second example was 0.35 GPa. The tensile elasticity achieved in the tensile test of the sample of the three-dimensional modeled object MO in the third example was 0.4 GPa. Because the samples were not annealed in the first to the third examples, the samples failed to exhibit a sufficient tensile elasticity.

By contrast, because the samples were annealed in the first example A to the third example 3C, the tensile elasticity was improved successfully. The samples exhibited tensile elasticities equal to or higher than 1.00 and equal to or lower than 2.50, and high levels of strength and durability was achieved, successfully.

In the first example A to the third example 3C, although the samples were annealed, no deformations were observed in the three-dimensional modeled objects MO.

As explained above, by annealing a three-dimensional modeled object having been applied with local heating and local cooling, warpage and deformation of a three-dimensional modeled object can be suppressed using a simple structure, and a high-quality three-dimensional modeled object can be achieved.

In particular, when a crystalline material (resin) or a semi-crystalline material (resin) is used as the modeling material, a high-quality three-dimensional modeled object can be manufactured.

According to an embodiment, it is possible to obtain a high-quality three-dimensional modeled object with warpage and deformation suppressed, using a simple structure.