Patent Publication Number: US-2016236422-A1

Title: Device and method for removing powder and apparatus for fabricating three-dimensional object

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is based on and claims priority pursuant to 35 U.S.C. §119(a) to Japanese Patent Application Nos. 2015-026852, filed on Feb. 13, 2015, and 2015-127085, filed on Jun. 24, 2016, in the Japan Patent Office, the entire disclosure of each of which is hereby incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     Aspects of this disclosure relate to a device and a method for removing powder and an apparatus for fabricating a three-dimensional object. 
     2. Related Art 
     A solid (three-dimensional) fabricating apparatus uses, for example, a lamination fabrication method to fabricate a solid (three-dimensional) object. In this method, for example, a flattened metal or non-metal powder layer is formed on a fabrication stage, and fabrication liquid is discharged from a head to the powder layer on the fabrication stage to form a thin fabrication layer in which powders are bonded together. A step of forming another powder layer on the fabrication layer to reform the fabrication layer is repeated to laminate the fabrication layers one on another, thus producing a three-dimensional object. 
     SUMMARY 
     In an aspect of the present disclosure, there is provided a powder removal device that includes an air spray configured to blow an airflow including powder against a three-dimensional object including a plurality of fabrication layers, to remove unbonded powder from the three-dimensional object. Each of the plurality of fabrication layers includes bonded powder. 
     In another aspect of the present disclosure, there is provided an apparatus for fabricating a three-dimensional object. The apparatus includes the powder removal device. 
     In still another aspect of the present disclosure, there is provided an apparatus for fabricating a three-dimensional object. The apparatus includes the powder removal device, a fabrication chamber, and a fabrication stage. The three-dimensional object is to be fabricated in the fabrication chamber. The plurality of fabrication layers are to be laminated one on another on the fabrication stage. The fabrication stage is movable upward and downward in the fabrication chamber. The powder removal device includes a post-processing space at a bottom side of the fabrication chamber. The post-processing space is communicated with the fabrication chamber. The fabrication stage is movable downward from the fabrication chamber into the post-processing space. The air spray is configured to blow the airflow including the powder against the three-dimensional object on the fabrication stage. 
     In still yet another aspect of the present disclosure, there is provided a method of removing powder from a three-dimensional object. The method includes blowing an airflow including the powder to the three-dimensional object including a plurality of fabrication layers to remove unbonded powder from the three-dimensional object. Each of the plurality of fabrication layers includes bonded powder. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The aforementioned and other aspects, features, and advantages of the present disclosure would be better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a partial perspective view of a three-dimensional fabricating apparatus according to an embodiment of this disclosure; 
         FIG. 2  is a cross-sectional view of a fabrication section of the three-dimensional fabricating apparatus; 
         FIGS. 3A through 3E  are schematic cross-sectional views of the fabrication section at fabrication steps; 
         FIG. 4  is a flow chart of an entire process of fabricating a three-dimensional object according to an embodiment of this disclosure; 
         FIG. 5A  is an illustration of an example of three-dimensional data of a target three-dimensional object; 
         FIG. 5B  is an illustration of a three-dimensional object taken from a fabrication chamber; 
         FIG. 6  is an illustration of a method of removing powder according to an embodiment of this disclosure; 
         FIGS. 7A and 7B  are schematic views of a powder removal device according to a first embodiment of this disclosure; 
         FIG. 8  is a schematic view of a second embodiment of the present disclosure; 
         FIG. 9  is a schematic view of a third embodiment of the present disclosure; 
         FIG. 10  is a schematic view of a fourth embodiment of the present disclosure; 
         FIGS. 11A and 11B  are schematic views of a fifth embodiment of the present disclosure; 
         FIG. 12  is a flow chart of an entire process of fabricating a three-dimensional object according to an embodiment of this disclosure; 
         FIG. 13  is a schematic view of a sixth embodiment of the present disclosure; 
         FIG. 14  is a schematic view of a seventh embodiment of the present disclosure; 
         FIGS. 15A and 15B  are schematic views of an eighth embodiment of the present disclosure; and 
         FIG. 16  is a schematic view of a ninth embodiment of the present disclosure. 
     
    
    
     The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. 
     DETAILED DESCRIPTION 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results. 
     Although the embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the disclosure and all of the components or elements described in the embodiments of this disclosure are not necessarily indispensable. 
     Referring now to the drawings, embodiments of the present disclosure are described below. In the drawings for explaining the following embodiments, the same reference codes are allocated to elements (members or components) having the same function or shape and redundant descriptions thereof are omitted below. 
     Hereinafter, embodiments of the present disclosure are described with reference to the attached drawings. First, a three-dimensional fabricating apparatus according to a first embodiment of the present disclosure is described with reference to  FIGS. 1 and 2 .  FIG. 1  is a partial perspective view of the three-dimensional fabricating apparatus according to the first embodiment of the present disclosure.  FIG. 2  is a cross-sectional view of a fabricating section of the three-dimensional fabricating apparatus. In  FIG. 2 , a state of the fabricating section in fabrication. 
     In this embodiment, a three-dimensional fabricating apparatus  1000  is a powder fabricating apparatus (also referred to as a powder fabricating apparatus). The three-dimensional fabricating apparatus  1000  includes a fabrication section  1  and a fabrication unit  5 . The fabrication section  1  forms a fabrication layer  30  that is a layered fabrication object in which powders are bonded together. The fabrication unit  5  fabricates a three-dimensional object by discharging fabrication liquid  10  onto a powder layer  31  that is overlaid in layers in the fabrication section  1 . 
     The fabrication section  1  includes a powder chamber  11  and a flattening roller  12  as a rotator that is a flattening member (recoater). Note that the flattening member may be, for example, a plate member (blade) instead of the rotator. 
     The powder chamber  11  includes a supply chamber  21  to supply powder  20  and a fabrication chamber  22  to fabricate an object. A bottom portion of the supply chamber  21  serves as a supply stage  23  and is movable upward and downward in a vertical direction (height direction). Similarly, a bottom portion of the fabrication chamber  22  serves as a fabrication stage  24  and is movable upward and downward in the vertical direction (height direction). A three-dimensional object is fabricated on the fabrication stage  24 . 
     The flattening roller  12  supplies the powder  20  supplied on the supply stage  23  of the supply chamber  21 , to the fabrication chamber  22  and flattens the powder  20  with the flattening roller  12  to form a powder layer  31 . 
     With a reciprocal moving assembly, the flattening roller  12  is movable relatively reciprocally with respect to a stage surface (a surface on which powder  20  is stacked) of the fabrication stage  24  in a direction indicated by arrow Y in  FIG. 2 , which is a direction along the stage surface of the fabrication stage  24 . When the flattening roller  12  moves, the flattening roller  12  is driven to rotate. 
     The fabrication unit  5  includes a liquid discharge unit  50  to discharge fabrication liquid  10  to the powder layer  31  on the fabrication stage  24 . 
     The liquid discharge unit  50  includes a carriage  51  and one or more liquid discharge heads (hereinafter referred to as simply “head(s)”)  52  mounted on the carriage  51 . 
     The carriage  51  is movably held with guides  54  and  55 . The guides  54  and  55  are held with holders  70  at lateral ends. 
     A main scan moving unit including, e.g., a motor, a pulley, and a belt reciprocally moves the carriage  51  along the direction indicated by arrow X (hereinafter simply referred to as “X direction”) that is a main scanning direction. 
     The head  52  includes nozzle arrays, each including multiple nozzles arrayed in line, to discharge cyan fabrication liquid, magenta fabrication liquid, yellow fabrication liquid, and clear color fabrication liquid. Note that the configuration of head is not limited to the above-described configuration of the head  52  and may be any other suitable configuration. 
     The entire fabrication unit  5  is reciprocally movable in the Y direction perpendicular to a direction indicated by arrow X (hereinafter, “X direction”) . 
     The liquid discharge unit  50  is disposed to be movable upward and downward along a direction indicated by arrow Z (hereinafter, “Z direction”) together with the guides  54  and  55 . 
     In the following, the fabrication section  1  is further described. 
     The powder chamber  11  has a box shape and includes two chambers, the supply chamber  21  and the fabrication chamber  22 , each of which is open at the upper side thereof. The supply stage  23  and the fabrication stage  24  are arranged inside the supply chamber  21  and the fabrication chamber  22 , respectively, so as to be movable upward and downward in the Z direction. 
     Lateral faces of the supply stage  23  are disposed to contact inner lateral faces of the supply chamber  21 . Lateral faces of the fabrication stage  24  are disposed to contact inner lateral faces of the fabrication chamber  22 . The upper faces of the supply stage  23  and the fabrication stage  24  are held horizontally. 
     A powder falling groove (powder receive portion)  29  is disposed at the periphery of the powder chamber  11  and has a recessed shape with the upper side thereof being open. A surplus of the powder  20  supplied with the flattening roller  12  in formation of a powder layer  31  falls to the powder receive portion  29 . 
     A powder supplier is disposed above the supply chamber  21 . In an initializing operation of fabrication or when the amount of powder in the supply chamber  21  decreases, the powder supplier supplies powder to the supply chamber  21 . Examples of a powder transporting method for supplying powder include a screw conveyor method utilizing a screw and an air transport method utilizing air. 
     The flattening roller  12  transfers and supplies powder  20  from the supply chamber  21  to the fabrication chamber  22  and forms a desired thickness of powder layer  31 . 
     The flattening roller  12  is a bar longer than an inside dimension of the fabrication chamber  22  and the supply chamber  21  (that is, a width of a portion to which powder is supplied or stored). The reciprocal moving assembly reciprocally moves the flattening roller  12  in the Y direction (a sub-scanning direction) along the stage surface. 
     The flattening roller  12 , while being rotated, horizontally moves to pass an area above the supply chamber  21  and the fabrication chamber  22  from the outside of the supply chamber  21 . Accordingly, the powder  20  is transferred and supplied onto the fabrication chamber  22 , and the flattening roller  12  flattens the powder  20  while passing over the fabrication chamber  22 , thus forming the powder layer  31 . 
     A powder removal plate  13  serving as a powder remover to remove the powder  20  attached to the flattening roller  12  is disposed in contact with a circumferential surface of the flattening roller  12 . 
     The powder removal plate  13  moves together with the flattening roller  12  in contact with the circumferential surface of the flattening roller  12 . The powder removal plate  13  is arranged in a state in which the powder removal plate  13  counters the flattening roller  12  when the flattening roller  12  rotates in a direction in which the flattening roller  12  rotates to flatten the powder  20 . 
     In this embodiment, the powder chamber  11  of the fabrication section  1  includes two chambers, i.e., the supply chamber  21  and the fabrication chamber  22 . In some embodiments, a powder chamber includes only the fabrication chamber  22 , and a powder supplier supplies powder to the fabrication chamber  22  and the flattening unit flattens the powder. 
     Next, a flow of fabrication is described with reference to  FIGS. 3A through 3E .  FIGS. 3A through 3E  are schematic cross-sectional views of fabrication steps of the fabrication section. 
     A first fabrication layer  30  is formed on the fabrication stage  24  of the fabrication chamber  22 . 
     When a second fabrication layer  30  is formed on the first fabrication layer  30 , as illustrated in  FIG. 3A , the supply stage  23  of the supply chamber  21  moves upward in a direction indicated by arrow Z 1 , and the fabrication stage  24  of the fabrication chamber  22  moves downward in a direction indicated by arrow Z 2 . At this time, a downward movement distance of the fabrication stage  24  is set so that a distance between a surface of a powder layer of the fabrication chamber  22  and a lower portion (lower tangential portion) of the flattening roller  12  is Δt 1 . The distance Δt 1  corresponds to the thickness of the powder layer  31  to be formed next. The distance Δt 1  is preferably about several tens pm to about 300 μm. 
     Next, as illustrated in  FIG. 3B , by moving the flattening roller  12  in a direction indicated by arrow Y 2  toward the fabrication chamber  22  while rotating the flattening roller  12  in a forward direction (indicated by arrow R), powder  20  upper than the level of a top face of the supply chamber  21  is transferred and supplied to the fabrication chamber  22  (powder supply). 
     As illustrated in  FIG. 3C , the flattening roller  12  is moved in parallel to the stage surface of the fabrication stage  24  of the fabrication chamber  22 . As illustrated in  FIG. 3D , a powder layer  31  having a thickness of Δt 1  is formed on the fabrication layer  30  of the fabrication stage  24  (flattening). 
     After the powder layer  31  is formed, the flattening roller  12  is moved in the direction indicated by arrow Y 1  and returned to an initial position. 
     Here, the flattening roller  12  is movable while maintaining a constant distance between the fabrication chamber  22  and the level of the top face of the supply chamber  21 . Such a configuration allows formation of a uniform thickness Δt 1  of the powder layer  31  on the fabrication chamber  22  or the fabrication layer  30  already formed while transporting the powder  20  to an area above the fabrication chamber  22  with the flattening roller  12 . 
     Then, as illustrated in  FIG. 3E , droplets of fabrication liquid  10  are discharged from a head  52  of the liquid discharge unit  50  to form and laminate the next fabrication layer  30  (fabrication). 
     For the fabrication layer  30 , for example, when the fabrication liquid  10  discharged from the head  52  is mixed with the powder  20 , adhesives contained in the powder  20  dissolve and bond together. Thus, particles of the powder  20  bind together to form the fabrication layer  30 . 
     Next, the above-described powder supply and flattening steps and the step of discharging the fabrication liquid with the head are repeated to form a new fabrication layer. At this time, a new fabrication layer and a fabrication layer below the new fabrication layer are united to form part of a three-dimensional fabrication object. 
     Then, the powder supply and flattening steps and the step of discharging the fabrication liquid with the head are repeated a required number of times to finish the three-dimensional fabrication object (solid fabrication object). 
     Next, descriptions are given of a powder material (powder) for three-dimensional fabrication and a fabrication liquid used in the three-dimensional fabricating apparatus  1000  according to this embodiment of this disclosure. It is to be noted that the powder and fabrication liquid used in a three-dimensional fabricating apparatus according to an embodiment of this disclosure is not limited to the powder and fabrication liquid described below. 
     The powder material for three-dimensional fabrication includes a base material and a water-soluble organic material that dissolves by action of cross-linker containing water serving as fabrication liquid and turns to be cross-linkable. The base material is coated with the water-soluble organic material at an average thickness of 5 nm to 500 nm. 
     For the powder material for three-dimensional fabrication, the water-soluble organic material coating the base material dissolves by action of cross-linker containing water and turns to be cross-linkable. When cross-linker containing water is applied to the water-soluble organic material, the water-soluble organic material dissolves and cross-link by action of cross-linkers contained in the cross-linker containing water. 
     Thus, a thin layer (powder layer) is formed with the powder material for three-dimensional fabrication. When the cross-linker containing water is discharged as the fabrication liquid  10  onto the powder layer, the dissolved water-soluble organic material cross-links in the powder layer. As a result, the powder layer is bonded and hardened, thus forming the fabrication layer  30 . 
     At this time, the coverage of the water-soluble organic material coating the base material is 5 nm to 500 nm in average thickness. When the water-soluble organic material dissolves, only a minimum required amount of the water-soluble organic material is present around the base material. The minimum required amount of water-soluble organic material cross-links and forms a three-dimensional network. Accordingly, the powder layer is hardened at a good dimensional accuracy and strength. 
     Repeating the operation allows a complex three-dimensional object to be simply and effectively formed at a good dimensional accuracy without losing the shape before sintering. 
     Base Material 
     The base material is not limited to a specific material as long as the material has a shape of powder or particle. Any powder or particulate material can be selected as the base material according to the purpose. Examples of the material include metal, ceramic, carbon, polymer, wood, and biocompatible material. From a viewpoint of obtaining a relatively high strength of three-dimensional object, for example, metal or ceramic which can be finally sintered is preferable. 
     Preferable examples of metal include stainless steel (SUS), iron, copper, titan, and silver. An example of SUS is SUS316L. 
     Examples of ceramic include metal oxide, such as silica (SiO 2 ), alumina (AL 2 O 3 ), zirconia (ZrO 2 ), and titania (TiO 2 ). 
     Examples of carbon include graphite, graphene, carbon nanotube, carbon nanohorn, and fullerene. 
     An example of polymer is publicly-known water-insoluble resin. 
     Examples of wood include woodchip and cellulose. 
     Examples of biocompatible material includes polylactic acid and calcium phosphate. 
     Of such materials, one material can be solely used or two or more types of materials can be used together. 
     Note that commercially available particles or powder formed of such materials can be used as the base material. Examples of commercial products include SUS316L (PSS316L made by SANYO SPECIAL STEEL Co., Ltd), SiO 2  (Ecserica SE-15 made by Tokuyama Corporation), ZrO 2  (TZ-B53 made by Tosoh Corporation). 
     To enhance the compatibility with water-soluble organic material, known surface (reforming) treatment may be performed on the base material. 
     Water-Soluble Organic Material 
     The water-soluble organic material is not limited to a specific material as long as the material dissolves in water and is cross-linkable by action of cross-linker. In other words, if it is water-soluble and water-linkable by action of cross-linker, any material can be selected according to the purpose. 
     Here, the water solubility of water-soluble organic material means that, when a water-soluble organic material of 1 g is mixed into water 100 g at 30° C. and stirred, not less than 90 mass percentage of the water-soluble organic material dissolves in the water. 
     As the water-soluble organic material, the viscosity of four mass percentage (w/w %) solution at 20° C. is preferably not greater than 40 mPa·s, more preferably 1 to 35 mPa·s, particularly more 5 to 30 mPa·s. 
     When the viscosity of the water-soluble organic material is greater than 40 mPa·s, the hardness of a hardened material (three-dimensional object or hardened material for sintering) of the powder material (powder layer) for three-dimensional object formed by applying cross-linker containing water to the powder material for three-dimensional fabrication may be insufficient. As a result, in post-treatment, such as sintering, and handling, the hardened material may lose the shape. In addition, the hardened material may be insufficient in dimensional accuracy. 
     The viscosity of the water-soluble organic material can be measured in accordance with, for example, JISK117. 
     Cross-Linker Containing Water 
     The cross-linker containing water serving as fabrication liquid is not limited to any specific liquid as long as the liquid contains cross linker in aqueous medium, and any suitable liquid is selectable according to the purpose. The cross-linker containing water can include any other suitable component as needed in addition to the aqueous medium and the cross-linker. 
     As such other component, any suitable component is selectable in consideration of conditions, such as the type of an applicator of the cross-linker containing water or the frequency and amount of use. For example, when the cross-linker containing water is applied according to a liquid discharge method, a component can be selected in consideration with influences of clogging to nozzles of the liquid discharge head. 
     Examples of the aqueous medium include alcohol, ethanol, ether, ketone, and preferably water. The aqueous medium may be water containing a slight amount of other component, such as alcohol, than water. 
     Using the above-described powder material for three-dimensional object and cross-linker containing water serving as fabrication liquid reduces clogging of nozzles and enhances the durability of the liquid discharge head as compared to a configuration in which the liquid discharge head discharges binder to attach powder (base material). 
     Next, an entire process of fabricating the three-dimensional object is described with reference to  FIG. 4 . 
     At S 1 , a powder layer  31  is formed and at S 2  fabrication liquid  10  is discharged as described above. When the fabrication of all layers is completed (YES at S 3 ), at S 4  a three-dimensional object  300  is taken from the fabrication chamber  22 . 
     After powder removal processing for removing powder  20  remaining on the three-dimensional object  300  is performed at S 5 , at S 6  the three-dimensional object  300  is sintered to obtain a finished product. 
     If the three-dimensional object  300  is sintered without performing powder removal processing, unsolidified powder particles would bond together, thus forming a fabrication object having a shape differing from a target shape. 
     As described above, when a three-dimensional object fabricated by a powder lamination fabrication method, unbonded (unsolidified) powder remains adhered to the three-dimensional object. However, when the three-dimensional object has a complex and fine shape, unsolidified powder may not be removed from the three-dimensional object only by blowing gas. 
     Hence, as described below, according to at least one embodiment of the present disclosure, unbonded powder remaining on a three-dimensional object is effectively removed from the three-dimensional object. 
     Below, a method of removing powder according to an embodiment of the present disclosure is described with reference to  FIGS. 5A and 5B and 6 .  FIGS. 5A and 5B  are illustrations of three-dimensional data of a target three-dimensional object and a three-dimensional object taken from a fabrication chamber in this embodiment.  FIG. 6  is an illustration of the method of removing powder according to this embodiment. 
     Through fabrication of a three-dimensional object represented by three-dimensional data illustrated in  FIG. 5A , a three-dimensional object  300  is fabricated in the fabrication chamber  22 . As illustrated in  FIG. 5B , the three-dimensional object  300  is taken from the fabrication chamber  22  with the powder  20  filling an internal space of the three-dimensional object  300 , and unbonded (also referred to unsolidified) powder  20  is also adhered to the three-dimensional object  300 . 
     As described above, unbonded powder  20  adhered to the three-dimensional object  300  is removed by sintering to turn the shape of the three-dimensional object  300  into the target shape. At this time, when the three-dimensional object  300  has a shape of including an internal space or a fine and complex shape, unbonded powder  20  may not be easily removed. 
     Hence, for the method of removing powder according to this embodiment, as illustrated in  FIG. 6 , an airflow  403  including powder  20 , which is the same as the powder  20  used for fabrication of the three-dimensional object  300 , is jetted from a nozzle  402  of an ejector  401  to blow the airflow  403  including the powder  20  against the three-dimensional object  300 . 
     As described above, in this embodiment, unbonded powder  20  adhered to the three-dimensional object  300  is removed by blowing the airflow  403  including the powder  20  against the three-dimensional object  300 . Such a method effectively removes unbonded powder  20  adhered to the three-dimensional object  300 . 
     Further, in this embodiment, the powder  20  for fabrication of the three-dimensional object  300  is used for powder blown against the three-dimensional object  300 . Thus, even if the three-dimensional object  300  is sintered with powder  20  blown to the three-dimensional object  300  remaining adhered to the three-dimensional object  300 , the physical properties of the three-dimensional object  300  remain unchanged after sintering. 
     In other words, in a case in which a different type of powder from the powder used for fabrication is used in a gas blown against the three-dimensional object  300 , if the three-dimensional object  300  is sintered with the blown powder remaining adhered to the three-dimensional object  300 , the physical properties of the three-dimensional object  300  might be changed. 
     By using the powder  20  for fabrication of the three-dimensional object  300  as the powder to be blown against the three-dimensional object  300 , the powder  20  having been used for powder removal can be collected and reused. 
     Next, a powder removal device according to a first embodiment of the present disclosure is described with reference to  FIGS. 7A and 7B .  FIGS. 7A and 7B  are schematic views of the powder removal device according to the first embodiment.  FIG. 7A  is an illustration of a state of the powder removal device in which the powder removal device is in powder removal operation.  FIG. 7B  is an illustration of a state of the powder removal device in which powder is supplied to a supply chamber. 
     In  FIGS. 7A and 7B , a powder removal device  400  according to this embodiment includes an air spray  410  to blow an airflow against a three-dimensional object. The air spray  410  includes, for example, an ejector  401 , a powder reserve tank  451 , and a powder supply passage  452 . The ejector  401  jets an airflow  403  including powder  20  to a three-dimensional object  300 . The powder reserve tank  451  is a reservoir to reserve the powder  20 . The powder supply passage  452  as a powder supplier connects the powder reserve tank  451  to the ejector  401  to guide the powder  20  from the powder reserve tank  451  to the ejector  401 . 
     The powder supply passage  452  includes a pump  453  as an airflow generator to generate an airflow  403  blown from the nozzle  402  of the ejector  401 . 
     The powder supply passage  452  coupled to the ejector  401  is made of a flexible member to change a direction in which the powder  20  is blown from the ejector  401  and a position to which the powder  20  is blown from the ejector  401 . 
     Hence, when powder is removed from the three-dimensional object  300 , as illustrated in  FIG. 7A , the three-dimensional object  300  is placed on the fabrication stage  24 . While sucking the powder  20  of the powder reserve tank  451  by driving the pump  453 , the powder removal device  400  blows the airflow  403  including the powder  20  from the nozzle  402  of the ejector  401  against the three-dimensional object  300 . Thus, unbonded powder  20  adhered to the three-dimensional object  300  is removed. 
     By contrast, when the powder  20  is supplied to the supply chamber  21 , as illustrated in  FIG. 7B , the powder  20  is supplied to the supply chamber  21  with the ejector  401  removed or mounted. 
     Thus, powder removal from the three-dimensional object  300  is performed, and the powder  20  of the supply chamber  21  is replenished. 
     In such a case, the output of the pump  453  can be changed between when powder removal from the three-dimensional object  300  is performed and when the powder  20  of the supply chamber  21  is replenished. 
     For example, the output of the pump  453  when powder removal from the three-dimensional object  300  is performed is set to be greater than the output of the pump  453  when the powder  20  is supplied to the supply chamber  21 . Accordingly, when powder removal from the three-dimensional object  300  is performed, the velocity of flow in the powder supply passage  452  is relatively fast, thus allowing effective removal of the powder  20 . 
     Further, the powder supply passage  452  may be configured to be attachable to and detachable from the ejector  401  so that an ejector  401  to perform powder removal from the three-dimensional object  300  is replaceable with an ejector  401  to replenish the powder  20  to the supply chamber  21 . 
     In such a case, for example, the ejector  401  to perform powder removal from the three-dimensional object  300  has a relatively small diameter of nozzle, and the ejector  401  to supply the powder  20  to the supply chamber  21  has a relatively large diameter of nozzle. Accordingly, when powder removal from the three-dimensional object  300  is performed, the velocity of flow in the powder supply passage  452  is relatively fast, thus allowing effective removal of the powder  20 . Further, when the powder  20  is supplied to the supply chamber  21 , such a configuration prevents the powder  20  to be jetted at an unnecessary high speed, thus reducing scattering of the powder  20 . 
     Next, a second embodiment of the present disclosure is described with reference to  FIG. 8 .  FIG. 8  is a schematic view of the second embodiment. 
     In this embodiment, the powder supply passage  452  in first embodiment is coupled to a powder receive portion  29  to receive extra powder  20  generated in formation of a powder layer  31 . Powder removal from the three-dimensional object  300  is performed using the extra powder  20  accumulated in the powder receive portion  29 . In this embodiment, the powder receive portion  29  is also a reservoir to reserve the powder  20 . 
     Such a configuration allows removal of unbonded powder  20  without using unused powder  20 . Accordingly, for example, when processing, such as screen classification or dehumidification, is performed on already-used powder  20  or unbonded powder  20  for reuse, the steps of processing can be reduced. 
     Next, a third embodiment of the present disclosure is described with reference to  FIG. 9 .  FIG. 9  is a schematic view of the third embodiment. 
     In this third embodiment, the powder removal device  400  according to the above-described second embodiment further includes a suction unit  461  to suck powder  20  removed from a three-dimensional object  300 . The suction unit  461  is placeable at a side opposite the ejector  401  via the three-dimensional object  300 , in other words, at a side opposite a side of the three-dimensional object  300  against which the airflow  403  including the powder  20  is blown when the powder  20  is removed from the three-dimensional object  300 . 
     The suction unit  461  is coupled to one end of a powder collection passage  462 , and a suction pump  463  to generate a sucking air flow is disposed at the powder collection passage  462 . 
     Such a configuration sucks and collects, from the suction unit  461 , powder  20  separated by an airflow  403  from the ejector  401  or powder  20  included in the airflow  403  when the powder  20  is removed from the three-dimensional object  300 . 
     Thus, scattering the powder  20  can be reduced when powder removal from the three-dimensional object  300  is performed. 
     The other end of the powder collection passage  462  is coupled to the powder receive portion  29  or a powder reserve tank  451  described in the first embodiment, thus allowing effective circulation of the powder  20 . 
     Next, a fourth embodiment of the present disclosure is described with reference to  FIG. 10 .  FIG. 10  is a schematic view of the fourth embodiment. 
     In the fourth embodiment, the powder removal device  400  according to the above-described third embodiment further includes another suction unit  464  to suck powder  20  rebounded from a three-dimensional object  300 . The suction unit  461  is placeable adjacent to the ejector  401 , in other words, at the same side as the side of the three-dimensional object  300  against which the airflow  403  including the powder  20  is blown when the powder  20  is removed from the three-dimensional object  300 . 
     The suction unit  464  is coupled to one end of a powder collection passage  465 , and a suction pump  466  to generate a suction airflow is disposed at the powder collection passage  465 . 
     Such a configuration sucks and collects, from the suction unit  464 , powder  20  blown from the ejector  401  against the three-dimensional object  300  and rebounded from the three-dimensional object  300  when the powder  20  is removed from the three-dimensional object  300 . 
     Thus, scattering the powder  20  can be reduced when powder removal from the three-dimensional object  300  is performed. 
     The other end of the powder collection passage  465  is coupled to the powder receive portion  29  or a powder reserve tank  451  described in first embodiment, thus allowing effective circulation of the powder  20 . 
     The powder removal device according to any one of the above-described embodiments is configured to be part of the above-described three-dimensional fabricating apparatus. Alternatively, as a device independent of the three-dimensional fabricating apparatus, the powder removal device may be disposed in, for example, a blast case to perform powder removal. 
     Next, a fifth embodiment of the present disclosure is described with reference to  FIGS. 11A and 11B .  FIGS. 11A and 11B  are schematic views of the fifth embodiment. 
     In this embodiment, a post-processing space formation member  40  molded with the fabrication chamber  22  as a single component is disposed at a bottom side of the fabrication chamber  22  to form a post-processing space  41  connected to the interior of the fabrication chamber  22 . 
     A fabrication stage  24  is disposed in the fabrication chamber  22  to be movable upward and downward. The fabrication stage  24  is also movable downward from the fabrication chamber  22  into the post-processing space  41  and movable within the post-processing space  41 . 
     In this embodiment, the post-processing space formation member  40  includes a bottom mouth  40   a  When the fabrication stage  24  fits in the bottom mouth  40   a  of the post-processing space formation member  40 , the post-processing space  41  becomes a substantially closed space. 
     In the post-processing space  41  is disposed an ejector  401  to blow an airflow  403  including powder  20  against a three-dimensional object  300 . 
     Next, an entire process of fabricating a three-dimensional object in this embodiment is described with reference to  FIG. 12 . 
     At S 101 , a powder layer  31  is formed and at S 102  fabrication liquid  10  is discharged. When the fabrication of all layers is completed (YES at S 103 ), at S 104  the fabrication stage  24  moves from a fabrication position illustrated in  FIG. 11A  into the post-processing space  41  as illustrated in  FIG. 11B  and fits in the bottom mouth  40   a  of the post-processing space formation member  40 . 
     Then, as illustrated in  FIG. 11B , at S 105  powder removal processing is performed to blow the airflow  403  including the powder  20  against the three-dimensional object  300  by the ejector  401  to remove unsolidified powder from the three-dimensional object  300 .  FIG. 11B  is an illustration of a state in which, after blowing unsolidified powder  20  around the three-dimensional object  300  with the airflow  403 , the powder removal device  400  blows unsolidified powder  20  in the internal space of the three-dimensional object  300 . After the three-dimensional object  300  is taken from the fabrication chamber  22  at S 106 , at S 107  the three-dimensional object  300  is sintered to obtain a finished product. 
     In such a configuration, after fabrication, the three-dimensional object  300  filled in unsolidified powder  20  in the fabrication chamber  22  is moved into the post-processing space  41  with downward movement of the fabrication stage  24  without scattering the powder  20  around the powder removal device  400 . 
     Then, unsolidified powder  20  is removed from the three-dimensional object  300  within the post-processing space  41 . Thus, powder removal is performed without scattering the powder  20  around the powder removal device  400   
     In such a case, the removal of unsolidified powder  20  may be performed by jetting an airflow including blast material other than powder  20  from the ejector  401 . However, use of the powder  20  allows already-used powder to be easily reused without mixture of foreign substance. 
     Further, setting a larger volume of the post-processing space  41  than the volume of the fabrication chamber  22  secures good workability in removing unsolidified powder  20  and prevents powder from being discharged to the outside of the powder removal device  400  from an upper portion  41   a  of the post-processing space  41 . 
     Next, a sixth embodiment of the present disclosure is described with reference to  FIG. 13 .  FIG. 13  is a schematic view of the sixth embodiment. 
     In this embodiment, a cover  44  is disposed to open and close an opening of a fabrication chamber  22 . 
     Such a configuration allows the opening of the fabrication chamber  22  to be closed with the cover  44  when unsolidified powder is removed after fabrication. 
     Accordingly, such a configuration reliably prevents powder  20  from being scattered around the powder removal device  400  when unsolidified powder is removed. 
     Further, the cover  44  may be transparent, thus securing visibility in removal work of unsolidified powder. 
     Next, a seventh embodiment of the present disclosure is described with reference to  FIG. 14 .  FIG. 14  is a schematic view of the sixth embodiment. 
     In this embodiment, a partition  45  is disposed to open and close between the fabrication chamber  22  and the post-processing space  41 . The partition  45  is rotatably supported with, for example, a shaft  45   a.    
     Such a configuration also partitions between the fabrication chamber  22  and the post-processing space  41  with the partition  45  when unsolidified powder is removal, thus reliably preventing the powder  20  from being scattered around the device. 
     Further, the partition  45  may be transparent, thus securing visibility in removal work of unsolidified powder. 
     Next, an eighth embodiment of the present disclosure is described with reference to  FIGS. 15A and 15B .  FIGS. 15A and 15B  are schematic views of the eighth embodiment. 
     In this embodiment, only a shaft  24   a  of the fabrication stage  24  passes through a bottom portion of the post-processing space formation member  40 , and a seal  46  seals a clearance between the shaft  24   a  and the post-processing space formation member  40 . The seal  46  is made of, for example, foamed polyurethane, thus allowing sealability and mobility. 
     Further, a powder collection passage  47  communicating with the post-processing space  41  is disposed and a pump  48  is disposed at the powder collection passage  47 . 
     For such a configuration, after fabrication is finished as illustrated in  FIG. 15A , the fabrication stage  24  is moved into the post-processing space  41  as illustrated in  FIG. 15B . In  FIG. 15B , the fabrication stage  24  is placed at a lowered position and in a state before an airflow is blown. 
     At this time, the seal  46  prevents unsolidified powder  20  from being discharged from a clearance between a bottom portion of the post-processing space  41  and the shaft  24   a  of the fabrication stage  24 . 
     Then, an airflow is blown from the ejector  401  against the three-dimensional object  300  to remove unsolidified powder  20 . At this time, the pump  48  is driven to generate an airflow indicated by arrow F in the powder collection passage  47 , and powder  20  blown and removed from the three-dimensional object  300  is collected through the powder collection passage  47 . 
     Note that the fabrication stage  24  and the post-processing space formation member  40  may be connected with an accordion member. Such a configuration also prevents unsolidified powder  20  from being discharged from the clearance between the bottom portion of the post-processing space  41  and the shaft  24   a  of the fabrication stage  24  while securing the mobility of the fabrication stage  24 . 
     Next, a ninth embodiment of the present disclosure is described with reference to  FIG. 16 .  FIG. 16  is a schematic view of the ninth embodiment. 
     In this embodiment, a reserve and collection tank  441  is disposed as a reservoir to reserve powder  20 . The reserve and collection tank  441  and the ejector  401  is connected with a powder supply passage  442 , and the powder  20  in the reserve and collection tank  441  is guided to the ejector  401  through the powder supply passage  442 . 
     The powder supply passage  442  includes a pump  443  as an airflow generator to generate an airflow  403  including the powder  20  blown from a nozzle of the ejector  401 . 
     Further, a powder removal device  400  according to the ninth embodiment further includes a suction unit (suction nozzle)  444  to suck powder  20  removed from a three-dimensional object  300 . The suction unit  444  is placeable at a side opposite the ejector  401  via the three-dimensional object  300 , in other words, at a side opposite a side of the three-dimensional object  300  against which the airflow  403  including the powder  20  is blown. 
     The suction unit  444  is coupled to the pump  48  via a powder collection passage  445 . The pump  48  is coupled to the reserve and collection tank  441  via a powder collection passage  446 . 
     For such a configuration, when unsolidified powder  20  is removed from the three-dimensional object  300 , the powder  20  is supplied from the reserve and collection tank  441  to the ejector  401  with the pump  443  and jetted from the ejector  401 . Further, the pump  48  is driven to suck and collect powder  20  through the powder collection passage  47  and the suction unit  444 , and collected powder  20  is returned to the reserve and collection tank  441  through the powder collection passage  446 . 
     When the three-dimensional object  300  has a penetration portion, such a configuration prevents unsolidified powder  20  or jetted powder  20  by the ejector  401  from being scattered, thus allowing effective circulation of the powder  20  jetted by the ejector  401 . Further, the ejector  401  and the suction unit  444  is configured to be movable within the post-processing space  41 , thus obtaining good workability. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the above teachings, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims.