3D printing apparatus and method

Abstract

This invention provides a 3D printing apparatus and method that can improve the accuracy of 3D printed objects by uniformly spreading powdered printing material, and can also increase the strength of 3D printed objects. [Solution] The system comprises a molding tank 12 into which powder molding material is supplied, a flattening roller 15 that flattens the surface of the molding material supplied to the molding tank 12 to form a powder layer, a solidification unit 3 that solidifies a predetermined area after the powder layer has been formed by the flattening roller 15, and a control unit 50 that builds a molded object by repeatedly forming and solidifying the powder layer and stacking it. The molding material is secondary particles, which are aggregates of primary particles, and the control unit 50 controls the flattening roller 15 to flatten the powder layer while crushing and compressing the secondary particles.

Description

Technical Field

[0001] The present invention relates to a three-dimensional shaping apparatus and method for forming a three-dimensional shaped object by repeatedly performing formation of a powder layer using a powder shaping material and solidification of the powder layer.

Background Art

[0002] Conventionally, an operation of forming a powder layer with a predetermined thickness in a shaping part and a shaping operation of binding the powder of the powder layer into a required shape to form a layered shaped object are repeatedly performed to shape a three-dimensional shaped object in which the layered shaped objects are stacked. The powder is solidified into a three-dimensional shaped object and becomes a final product through a degreasing and firing process. However, if the density of the three-dimensional shaped object is low, the sintering reaction does not proceed during firing, and the strength of the final product becomes low.

[0003] Therefore, in the powder layer formation operation of Patent Document 1, a method of increasing the average density of the powder layer by performing powder supply and flattening treatment a plurality of times has been proposed. Further, in Patent Document 2, it has been proposed to provide a mechanism for compressing the powder layer by bringing a pressing member having a planar shape into contact in order to increase the density of the powder layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In conventional methods such as those described in Patent Document 1, the ceramic powder has a particle size of 2 μm or larger, resulting in a small contact area between powder particles. This leads to a lower strength in the final product due to the sintering reaction during firing. For example, using powder smaller than 2 μm would allow the sintering reaction to proceed more easily, thus increasing the strength of the final product. However, its low fluidity makes it difficult to supply into the molding tank and flatten the powder. In addition, the powder would be scattered, requiring consideration for worker safety.

[0006] In view of the above circumstances, the present invention aims to provide a three-dimensional molding apparatus and method that can improve the accuracy of a three-dimensional molded object by uniformly spreading powder molding material, and can also increase the strength of a three-dimensional molded object. [Means for solving the problem]

[0007] The present invention provides a three-dimensional molding apparatus comprising: a molding tank to which powder molding material is supplied; a flattening unit to flatten the surface of the molding material supplied to the molding tank to form a powder layer; a solidification unit to solidify a predetermined area after the powder layer has been formed by the flattening unit; and a control unit to build a molded object by repeatedly forming and solidifying the powder layer and stacking the layers. The molding material is secondary particles, which are aggregates of primary particles, and the control unit controls the flattening unit to flatten the powder layer while crushing and compressing the secondary particles. [Effects of the Invention]

[0008] According to the 3D printing apparatus of the present invention, secondary particles are used as the printing material, allowing for a uniform spread of the powdered printing material and improving the accuracy of the 3D printed object. Furthermore, according to the 3D printing apparatus of the present invention, the powder layer is flattened by crushing and compressing the secondary particles in the planarization section, eliminating gaps between the secondary particles and improving density. This facilitates the sintering reaction and increases the strength of the 3D printed object. [Brief explanation of the drawing]

[0009] [Figure 1]A schematic diagram of one embodiment of the 3D printing apparatus body of the present invention, viewed from above. [Figure 2] A schematic diagram showing the process of forming a powder layer. [Figure 3] Microscope images showing the state of the 3D printing material before and after compression. [Figure 4] Figure 1 shows a block diagram illustrating the configuration of the control system for the 3D printing device. [Figure 5] Figure 1 is a diagram illustrating the 3D printing process of a 3D modeling device. [Figure 6] Block diagram showing the configuration of a control system when controlling the rotation speed of a flattening roller according to the load on the flattening roller. [Figure 7] A flowchart illustrating a specific method for controlling the rotation speed of a flattening roller according to the load on the flattening roller. [Figure 8] This diagram shows an example of controlling the load and rotational speed of a flattening roller. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the 3D printing apparatus of the present invention will be described in detail with reference to the drawings. The 3D printing apparatus of this embodiment is characterized by its printing material and its planarization method, but first, the overall configuration of the 3D printing apparatus body will be described. Figure 1 is a diagram showing the schematic configuration of the 3D printing apparatus body 1. Figure 1 is a view of the 3D printing apparatus body 1 from above, and the front, back, left, and right directions shown in Figure 1 are the front, back, left, and right directions of the 3D printing apparatus body 1, with the front side of the paper being the top and the back side of the paper being the bottom.

[0011] The 3D printing apparatus body 1 of this embodiment comprises a printing unit 2 and a solidification unit 3. The printing unit 2 supplies powdered printing material to a printing tank 12 and forms a powder layer in the printing tank 12. The solidification unit 3 forms a printing layer by discharging a printing liquid onto the powder layer and solidifying a predetermined area. In the 3D printing apparatus body 1, a 3D object is formed by the stacking of printing layers.

[0012] Specifically, the shaping part 2 includes a powder tank 10 and a flattening roller 15. In this embodiment, the flattening roller 15 corresponds to the flattening part of the present invention, but it is not limited thereto. For example, a plate-shaped member may be used instead.

[0013] The powder tank 10 has a box shape and includes a box-shaped supply tank 11 with an open upper surface and a shaping tank 12. In the recess surrounded by the bottom plate and the side surface of the supply tank 11, the powder shaping material is stored. On the bottom plate of the supply tank 11, a plate-shaped supply stage 13 is provided.

[0014] The supply stage 13 is configured to be able to move up and down in the vertical direction. When the supply stage 13 rises, the shaping material in the supply tank 11 is lifted. The shaping material that protrudes above the opening of the supply tank 11 is supplied to the shaping tank 12 by the movement of the flattening roller 15. The supply stage 13 moves up and down by a supply stage drive motor 18 (see FIG. 4). The method of supplying the shaping material will be described in detail later.

[0015] The shaping tank 12 is provided adjacent to the front side of the supply tank 11. In the recess surrounded by the bottom plate and the side surface of the shaping tank 12, the powder shaping material supplied from the supply tank 11 is stored. On the bottom plate of the shaping tank 12, a plate-shaped shaping stage 14 is provided. The shaping stage 14 is configured to be able to move up and down in the vertical direction.

[0016] On the shaping stage 14, a powder layer is formed, and the shaping liquid is discharged onto the powder layer and solidifies to form a shaping layer. The shaping stage 14 descends each time a shaping layer is formed, whereby the shaping layers are laminated, and finally a three-dimensional shaped object is shaped on the shaping stage 14. The shaping stage 14 descends by a shaping stage drive motor 19 (see FIG. 4). The method of laminating the shaping layers will be described in detail later.

[0017] The flattening roller 15 is a roller member provided above the powder tank 10 and extending in the left - and - right direction. The flattening roller 15 is a roller member longer than the inner dimension in the left - and - right direction of the supply tank 11 and the shaping tank 12, and moves horizontally so as to pass above the supply tank 11 and the shaping tank 12. The flattening roller 15 supplies and flattens the shaping material of the powder supplied on the supply stage 13 of the supply tank 11 onto the shaping stage 14 of the shaping tank 12, forming a powder layer in the form of a layer with a predetermined thickness.

[0018] The flattening roller 15 rotates while moving forward from the rear end of the powder tank 10, thereby winding and compressing the shaping material of the powder on the supply tank 11 and transferring and supplying it toward the shaping stage 14. Thereby, a powder layer is formed on the shaping stage 14. The flattening roller 15 moves in the front - and - rear direction by a moving mechanism 16 (see FIG. 4) and rotates by a roller drive motor 17 (see FIG. 4). The flattening roller 15 rotates in its traveling direction (from the rear side to the front side) in order to wind the shaping material of the powder as described above.

[0019] Here, in the present embodiment, ceramic granules are used as the shaping material of the powder. The ceramic granules are secondary particles in which primary particles of a ceramic raw material with a diameter of 0.1 μm to several μm are solidified with a binder to form a spherical shape with a diameter of 10 μm to 100 μm. The ceramic granules are manufactured, for example, by a spray drying method or the like.

[0020] For example, when a powder layer is formed using the secondary particles as they are, gaps are formed between the secondary particles and the density becomes low. Therefore, in the present embodiment, as described above, it is transferred and supplied while being compressed and pulverized by the flattening roller 15, thereby forming a high - density powder layer.

[0021] FIG. 2 is a diagram schematically showing a state in which the flattening roller 15 rotates while moving, winds the shaping material, compresses it, and forms a powder layer. FIG. 3A is a micrograph showing the state of the shaping material before compression, and FIG. 3B is a micrograph showing the state of the shaping material after compression. As shown in FIG. 3B, a high - density powder layer can be realized.

[0022] As ceramics, for example, oxides, carbides, nitrides, hydroxides, etc., can be used. As oxides, for example, metal oxides such as silica (SiO2), alumina (Al2O3), zirconia (ZrO2), titania (TiO2), and silicon carbide (SiC) can be used.

[0023] Commercially available products include, for example, alumina granules A-96A, LS-711C, and MS-3N12C manufactured by Marumi Ceramics Co., Ltd. In the case of SiO2, for example, product name: Excelica SE-15K manufactured by Tokuyama Corporation can be used, and in the case of ZrO2, for example, product name: TZ-B53 manufactured by Tosoh Corporation can be used.

[0024] Examples of binders that can be used to form secondary particles include polyvinyl alcohol, polyacrylic acid, furan resin, phenolic resin, polyamide, and polyvinylprolidone.

[0025] It is preferable to create irregularities on the surface of the flattening roller 15 that are smaller than the average particle size of the molding material (secondary particles). As a method for creating these irregularities, for example, ceramic particles may be attached to the periphery of a metal roller to form the irregularities, or a diamond electroplated roller or a twill roller may be used.

[0026] Furthermore, it is preferable to form fine irregularities on the surface of the flattening roller 15 that are less than 1 / 10 of the average particle size of the molding material (secondary particles). Specifically, it is preferable to form a nano-irregular structure or a multi-scale structure by, for example, Taflat treatment (registered trademark).

[0027] Furthermore, it is preferable to form irregularities smaller than the average particle size of the material on the mounting surface of the molding stage 14.

[0028] Next, the solidification unit 3 includes a molding fluid dispensing unit 30 that dispenses the molding fluid onto the powder layer formed on the molding stage 14. The molding fluid dispensing unit 30 includes a carriage 31 and a dispensing head 32 provided on the carriage 31.

[0029] The carriage 31 is supported by guide members 33 and 34 so as to be movable in the left-right direction. The guide members 33 and 34 are held by side plates 35 on both sides. The carriage 31 moves in the left-right direction by the main scanning mechanism 37 (see Figure 4).

[0030] The ejection head 32 has a nozzle row in which multiple nozzles for ejecting the molding fluid are arranged. The molding fluid ejected from the ejection head 32 may be one type or multiple types.

[0031] The solidification unit 3 has a moving mechanism 40 that is movably held by a guide member 36 positioned on a base member 4, and the entire solidification unit 3 is configured to reciprocate in the front-rear direction. The solidification unit 3 moves in the front-rear direction by a sub-scanning mechanism 38 (see Figure 4).

[0032] The molding fluid dispensing unit 30 is configured to move up and down in the vertical direction together with the guide members 33 and 34 by a lifting mechanism 39 (see Figure 4).

[0033] The solidification unit 3 can be anything that can selectively solidify the powder layer, and may be one that sintersects by laser irradiation or one that melts by laser irradiation.

[0034] Figure 4 is a block diagram showing the configuration of the control system of the 3D printing apparatus in this embodiment. The 3D printing apparatus body 1 and the control unit 50 shown in Figure 1 are connected, for example, by a communication cable, and the 3D printing apparatus body 1 operates in response to control signals output from the control unit 50. The 3D printing apparatus body 1 and the control unit 50 may be connected via a wireless or wired communication line.

[0035] The control unit 50 includes a CPU (Central Processing Unit), semiconductor memory such as ROM (Read Only Memory) and RAM (Random Access Memory), storage such as a hard disk, and a communication interface (I / F). A 3D modeling control program is installed in the storage of the control unit 50. When this 3D modeling control program is started by the CPU, the various parts shown in Figure 4 begin to function.

[0036] Next, the manufacturing process of the 3D printed object in the 3D printing apparatus of this embodiment will be described with reference to Figure 5.

[0037] Figure 5A shows the state in which the first build layer ML is formed on the build stage 14 of the build tank 12. In this state, when forming the next build layer ML on top of the build layer ML, the supply stage 13 of the supply tank 11 is raised upward and the build stage 14 of the build tank 12 is lowered downward, as shown in Figure 3A. At this time, the raising and lowering of the supply stage 13 and the build stage 14 are controlled so that the distance between the upper surface of the build tank 12 (powder layer surface) and the lower surface of the flattening roller 15 becomes the thickness of the next powder layer PL. In other words, the amount of build material supplied by the supply tank 11 is changed according to the thickness of the next powder layer PL.

[0038] Next, as shown in Figure 5B, the flattening roller 15 moves forward and rotates in the direction of the arrow shown in Figure 5B. As a result, the powder P that has been pushed above the upper surface of the supply tank 11 is compressed by the flattening roller 15 and transferred and supplied towards the molding tank 12.

[0039] Next, as shown in Figure 5C, the flattening roller 15 is moved parallel to the mounting surface of the molding stage 14 of the molding tank 12, flattening the surface of the powder P on the molding layer ML of the molding stage 14 and forming a powder layer PL of a predetermined thickness. This forms the next powder layer PL on top of the already formed molding layer ML. After forming the powder layer PL, the flattening roller 15 moves backward and returns to its initial position, as shown in Figure 5D.

[0040] Next, the solidification unit 3 moves backward and is positioned above the molding tank 12. Then, the carriage 31 of the molding fluid discharge unit 30 moves to the right, and the discharge head 32 is positioned at a predetermined location on the powder layer PL. After that, as shown in Figure 5E, the molding fluid L is discharged from the discharge head 32, and the molding layer ML is formed by laminating it onto the next powder layer PL. The molding layer ML is formed when the molding fluid L is mixed with the powder P, the adhesive contained in the powder P dissolves, and the dissolved adhesives bond together to form the powder P.

[0041] Subsequently, the process of supplying and flattening the powder to form a powder layer PL, and the process of discharging the molding fluid by the discharge head 32 are repeated a predetermined number of times, thereby completing the three-dimensional object.

[0042] In the three-dimensional molding apparatus of the above embodiment, the flattening roller 15 moves and rotates while compressing and crushing the molding material, which is secondary particles, as described above. When the moving speed and peripheral speed of the flattening roller 15 are the same, it is the same as rolling, so the load on the flattening roller 15 is small, and therefore the load on the roller drive motor 17 is also small. On the other hand, when there is a difference between the moving speed and peripheral speed of the flattening roller 15, the load on the flattening roller 15 increases, and the load on the roller drive motor 17 increases, but the density of the compressed molding layer becomes higher, which is more preferable.

[0043] Therefore, the load on the flattening roller 15 may be detected, and the rotational speed of the flattening roller 15 may be controlled according to that load. Figure 6 is a block showing the configuration of a control system when the rotational speed of the flattening roller 15 is controlled according to the load in this way.

[0044] As shown in Figure 6, the control unit 50 includes a load detection unit 51 that detects the load on the flattening roller 15. The load detection unit 51 detects the load on the flattening roller 15 by detecting the current value of the roller drive motor 17 and calculating the load on the roller drive motor.

[0045] Figure 7 is a flowchart illustrating a specific method for controlling the rotational speed of the flattening roller 15 according to the load on the flattening roller 15, as described above. First, the control conditions for this control are shown below. 1. The moving speed of the flattening roller shall be greater than or equal to the peripheral speed of the flattening roller. 2. The parameters used for control are as follows. Note that these parameters will vary depending on other equipment conditions and materials, and should be set appropriately through experiments. Speed ​​of the flattening roller: 10 [mm / s] Upper limit of peripheral speed of the flattening roller: 10 [mm / s] Lower limit of peripheral speed of the flattening roller: 6 [mm / s] Target load torque for roller drive motor: 1 [N / m]

[0046] As shown in the flowchart in Figure 7, the control unit 50 checks whether the load amount (load torque) detected by the load amount detection unit 51 is smaller than the target value (S10). If the load amount is smaller than the target value (S10, YES), the control unit 50 lowers the rotation speed of the flattening roller 15 (S12). On the other hand, if the load amount is greater than or equal to the target value (S10, NO), the control unit 50 increases the rotation speed of the flattening roller 15 (S14).

[0047] Next, the control unit 50 checks whether the rotational speed of the flattening roller 15 is above the lower limit (S16). If the rotational speed is above the lower limit (S16, YES), the control unit 50 checks whether the rotational speed is below the upper limit (S18). If the rotational speed is below the upper limit (S18, YES), that is, if the rotational speed is above the lower limit and below the upper limit, the control unit 50 considers it to be within the acceptable range and does not change the rotational speed, and repeats the process from S10 again.

[0048] On the other hand, in S16, if the rotation speed is less than the lower limit (S16, NO), the control unit 50 controls the rotation speed of the flattening roller 15 to the lower limit (S20). Then, the control unit 50 repeats the process from S10 again. Also, in S18, if the rotation speed is greater than the upper limit (S18, NO), the control unit 50 controls the rotation speed of the flattening roller 15 to the upper limit (S22). Then, the control unit 50 repeats the process from S10 again.

[0049] By controlling the rotational speed of the flattening roller 15 according to the flowchart shown in Figure 7, the load can be controlled to approach the target value "1" as shown in Figure 8A, and the rotational speed can be kept within an acceptable range that is above the lower limit and below the upper limit, as shown in Figure 8B.

[0050] According to the 3D printing apparatus of the above embodiment, secondary particles are used as the printing material, so the powder printing material can be uniformly spread out, improving the accuracy of the 3D printed object. Furthermore, since the powder layer is flattened by crushing and compressing the secondary particles with the flattening roller 15, the gaps between the secondary particles are eliminated and the density can be improved, which facilitates the sintering reaction and increases the strength of the 3D printed object.

[0051] Furthermore, in the three-dimensional molding apparatus of the above embodiment, if irregularities smaller than the average particle size of the molding material are formed on the surface of the flattening roller 15, the frictional force between the flattening roller 15 and the powder increases, allowing more powder to be incorporated and compressed to a high density.

[0052] Furthermore, in the three-dimensional molding apparatus of the above embodiment, if the surface on which the molding material is placed on the molding stage 14 is made to have irregularities smaller than the average particle size of the molding material, the first layer of powder can be prevented from spreading on the molding stage 14, thereby allowing more powder to be incorporated and compressed to a high density.

[0053] Furthermore, in the three-dimensional molding apparatus of the above embodiment, if the load on the flattening roller 15 is detected and the rotation speed of the flattening roller 15 is controlled according to the load, it is possible to prevent excessive powder from being drawn in and damaging the roller drive motor 17, or to prevent insufficient powder from being drawn in and resulting in low density, thereby obtaining a powder layer with uniform density.

[0054] Furthermore, in the three-dimensional molding apparatus of the above embodiment, the amount of molding material supplied is changed according to the thickness of the powder layer. This also prevents damage to the roller drive motor 17 due to excessive powder entrapment, and prevents low density due to insufficient powder entrapment.

[0055] Furthermore, in the three-dimensional molding apparatus of the above embodiment, if fine irregularities of 1 / 10 or less of the average particle size of the molding material are formed on the surface of the flattening roller 15, the van der Waals force can be reduced, thereby preventing a decrease in molding accuracy due to powder adhering to the flattening roller 15 and peeling off from the powder layer.

[0056] It should be noted that the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the embodiments described above. For example, all the components shown in the embodiments may be combined as appropriate. It goes without saying that various modifications and applications are possible without departing from the spirit of the invention.

[0057] The following further notes are disclosed regarding the present invention.

[0058] (Note 1) The present invention provides a three-dimensional molding apparatus comprising: a molding tank to which powder molding material is supplied; a flattening unit to flatten the surface of the molding material supplied to the molding tank to form a powder layer; a solidification unit to solidify a predetermined area after the powder layer has been formed by the flattening unit; and a control unit to build a molded object by repeatedly forming and solidifying the powder layer and stacking the layers. The molding material is secondary particles, which are aggregates of primary particles, and the control unit controls the flattening unit to flatten the powder layer while crushing and compressing the secondary particles.

[0059] (Note 2) In the three-dimensional molding apparatus described in Appendix 1, the flattening section is a flattening roller, and the surface of the flattening roller can form irregularities smaller than the average particle size of the molding material.

[0060] (Note 3) In the three-dimensional molding apparatus described in Appendix 1 or 2, it is possible to form irregularities on the mounting surface of the molding material that are smaller than the average particle size of the molding material.

[0061] (Note 4) In the three-dimensional forming apparatus described in any of the appendices 1 to 3, the flattening unit is a flattening roller, and the apparatus includes a load detection unit for detecting the amount of load applied to the flattening roller, and the control unit can control the rotation speed of the flattening roller according to the amount of load detected by the load detection unit.

[0062] (Note 5) In the three-dimensional molding apparatus described in any of the appendices 1 to 4, a supply unit is provided to supply molding material to the molding unit, and the amount of molding material supplied by the supply unit can be changed according to the thickness of the powder layer.

[0063] (Note 6) In the three-dimensional forming apparatus described in any of Appendix 1 to 5, fine irregularities of 1 / 10 or less of the average particle size of the forming material can be formed on the surface of the flattened portion.

[0064] (Note 7) The present invention relates to a three-dimensional fabrication method in which a powder fabrication material is placed on a fabrication section and its surface is flattened to form a powder layer, a predetermined region is solidified after the formation of the powder layer, and the formation and solidification of the powder layer are repeated to build up layers and create a fabricated object. In this method, the fabrication material is secondary particles, which are aggregates of primary particles, and the powder layer is flattened while the secondary particles are crushed and compressed by the flattening section. [Explanation of Symbols]

[0065] 1. Main unit of the 3D printing device 2. Molding Section 3. Solidification section 4 Base member 10 Powder tank 11 Supply tank 12 Modeling tank 13 Supply Stages 14. Modeling Stage 15 Flattening Roller 16 Moving mechanism 17 Roller drive motor 18. Supply stage drive motor 19. Build Stage Drive Motor 30. Molding fluid ejection unit 31 Carriage 32 Discharge head 33, 34 Guide members 35 Side panel 36 Guide member 37 Main scanning mechanism 38 Sub-scanning mechanism 39 Lifting mechanism 40 Moving mechanism 50 Control Unit 51 Load detection unit L Modeling liquid ML modeling layer P powder PL powder layer

Claims

1. A molding tank from which powdered molding material is supplied, A flattening unit that flattens the surface of the molding material supplied to the molding tank to form a powder layer, A solidification section that solidifies a predetermined area after forming a powder layer by the flattening section, The system includes a control unit that repeatedly forms and solidifies the powder layer to create a stacked structure and build up the material. The aforementioned molding material is a secondary particle of an aggregate of primary particles, A three-dimensional molding apparatus in which the control unit controls the planarization unit to flatten the powder layer while crushing and compressing secondary particles.

2. The three-dimensional molding apparatus according to claim 1, wherein the flattening portion is a flattening roller, and the surface of the flattening roller has irregularities smaller than the average particle size of the molding material.

3. The three-dimensional molding apparatus according to claim 1, wherein the mounting surface of the molding material has irregularities smaller than the average particle size of the molding material.

4. The flattening section is a flattening roller, The system includes a load detection unit that detects the amount of load applied to the flattening roller, The three-dimensional molding apparatus according to claim 1, wherein the control unit controls the rotation speed of the flattening roller according to the load amount detected by the load detection unit.

5. The molding section is equipped with a supply unit for supplying the molding material, The three-dimensional molding apparatus according to claim 1, wherein the amount of molding material supplied by the supply unit is changed according to the thickness of the powder layer.

6. The three-dimensional molding apparatus according to claim 1, wherein fine irregularities of 1 / 10 or less the average particle size of the molding material are formed on the surface of the flattened portion.

7. The surface of the powder material supplied to the molding tank is flattened to form a powder layer. In a three-dimensional fabrication method in which a powder layer is formed, a predetermined region is solidified, and the formation and solidification of the powder layer is repeated to create a layered object, The aforementioned molding material is a secondary particle of an aggregate of primary particles, A three-dimensional molding method comprising flattening the powder layer while crushing and compressing secondary particles using the flattening section.

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