JP2018171799A - Three-dimensional laminate molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional laminate molding machine capable of accurately forming a powder material in a layer form and improving accuracy of a molded object.SOLUTION: A three-dimensional laminate molding machine has: a recoater 13 capable of storing a powder material in a 3D printer 1 and discharging the stored powder material in a layer form; and a control unit 20 controlling an operation of the recoater 13. The recoater 13 is provided with: a container 15 capable of storing the powder material; and a screw member 21 rotatable with respect to the container 15 and conveying the powder material inside the container 15 in a direction in which a rotation axis extends. The control unit 20 controls a rotation direction of the screw member 21 so that it can be switched between a first rotation direction and a second rotation direction that is an opposite direction to the first rotation direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a three-dimensional additive manufacturing apparatus.

  An additive manufacturing apparatus that manufactures a three-dimensional structure by repeating layer formation of a powder material and solidification of a predetermined portion in the layer of the powder material is known.

  As such an additive manufacturing apparatus, for example, an additive manufacturing apparatus including a recoater unit that stores sand as a powder material and a print head unit that discharges a binder that binds sand is proposed (for example, a patent). Reference 1).

  And in such a layered modeling apparatus, after the recoater unit moves and spreads sand on the modeling table to form a sand layer, the print head unit discharges and applies a binder on the sand layer, Solidify the binder coating part of the sand layer.

Japanese Patent Laying-Open No. 2015-189035

  However, in the additive manufacturing apparatus described in Patent Document 1, sand may be biased without being uniformly stored inside the recoater unit. In this case, when the recoater unit grinds the sand to form a sand layer, the sand layer has a non-uniform thickness due to the sand unevenness inside the recoater unit, and there is a possibility that it cannot be accurately modeled.

  Therefore, the present invention provides a three-dimensional additive manufacturing apparatus that can form a powder material in a layer shape with high accuracy and can improve the accuracy of a modeled object.

  The present invention [1] is a three-dimensional additive manufacturing apparatus that forms a powder material in layers and then repeatedly molds the powder material layer, and can store the powder material. A discharge unit that discharges the stored powder material in a layered manner, and a control unit that controls the operation of the discharge unit, and the discharge unit includes a container capable of storing the powder material; A screw member that is rotatable relative to the container and that conveys the powder material in the container in a direction in which a rotation axis extends, and the control unit changes a rotation direction of the screw member to a first direction. A three-dimensional additive manufacturing apparatus is included that controls to be switchable between a rotation direction and a second rotation direction that is opposite to the first rotation direction.

  However, as shown to FIG. 3A, the container of a discharge part stores powder material by supplying powder material. The powder material stored in the container may be biased near the supply port formed in the container. Then, as shown to FIG. 3B, providing a screw member in a container and conveying powder material is considered.

  However, when the powder material is transported by the screw member, the powder material is collected in the downstream portion in the powder material transport direction, and the powder material may not be uniformly stored inside the container.

  On the other hand, according to said structure, a control part is controlled so that the rotation direction of a screw member can be switched to a 1st rotation direction and the 2nd rotation direction opposite to a 1st rotation direction. Therefore, after rotating the screw member in the first rotation direction and conveying the powder material from one side of the direction in which the rotation axis extends to the other side, the rotation direction of the screw member is switched to the second rotation direction. Thus, the powder material can be conveyed from the other side in the direction in which the rotation axis extends to one side. Thereby, powder material can be uniformly stored inside the container. As a result, the discharge part can form the powder material in a layered shape with high accuracy, and the accuracy of the shaped article can be improved.

  According to the three-dimensional layered manufacturing apparatus of the present invention, the powder material can be formed in a layered shape with high accuracy, and the accuracy of the model can be improved.

FIG. 1 is a plan view of a 3D printer as an embodiment of the three-dimensional additive manufacturing apparatus of the present invention. FIG. 2 is a cross-sectional view of the recoater shown in FIG. 3A is a BB cross-sectional view of the recoater shown in FIG. 1 and shows a state where the powder material is biased in the vicinity of the supply port. FIG. 3B shows a state in which the powder material is conveyed by the screw member following FIG. 3A. FIG. 3C shows a state where the powder material is uniformly stored inside the container following FIG. 3B. FIG. 4A is a perspective view of the 3D printer shown in FIG. 2 and shows a process in which the recoater forms a first powder material layer. FIG. 4B is an explanatory diagram for explaining the process illustrated in FIG. 4A. FIG. 5A is a perspective view of the 3D printer shown in FIG. 2 and shows a process in which the jet head supplies a binder to the first powder material layer. FIG. 5B is an explanatory diagram for explaining the process illustrated in FIG. 5A. FIG. 6A shows a step of forming a second powder material layer on the first powder material layer following FIG. 5B. FIG. 6B shows a step of supplying a binder to the second powder material layer following FIG. 6A. FIG. 7A shows a step of forming a modeled object by successively repeating the layer formation of the powder material and the supply of the binder sequentially from FIG. 6B. FIG. 7B is a perspective view of the shaped article shown in FIG. 7A. FIG. 8 is a schematic configuration diagram of foundry sand as one embodiment of the powder material stored in the recoater shown in FIG. 1.

<3D printer>
With reference to FIGS. 1-4B, the 3D printer 1 as one Embodiment of the three-dimensional layered modeling apparatus of this invention is demonstrated.

  The 3D printer 1 is an apparatus that can form a modeled object based on 3D-CAD data. After forming the powder material into a layer, the binder is supplied to the powder material layer so that the powder material layer is formed. Repeat the hardening process.

As shown in FIG. 1, the 3D printer 1 includes a modeling unit 10, a recoater 13 as an example of a discharge unit, a jet head 14, and a control unit 20.
(1) Modeling unit As shown in FIGS. 4A and 4B, the modeling unit 10 includes a job box 11, a stage 12, and a support shaft 18.

  The job box 11 has a substantially rectangular frame shape in plan view, and extends in the vertical direction. The upper end of the job box 11 is open.

The stage 12 has a substantially rectangular plate shape in plan view, and is arranged in the job box 11. The stage 12 is fixed to the upper end of a support shaft 18 that can be moved up and down. The stage 12 can move up and down in the job box 11 by raising and lowering the support shaft 18.
(2) Recoater As shown in FIGS. 3C and 4B, the recoater 13 is capable of storing a powder material, and is configured to discharge the stored powder material in a layered form on the stage 12. The The recoater 13 is movable in one direction of the surface direction of the stage 12 so as to pass above the stage 12 in a state parallel to the stage 12 with a space therebetween. In the following description, the direction in which the recoater 13 can move is defined as the horizontal direction (X direction), and the direction perpendicular to both the horizontal direction and the vertical direction is defined as the vertical direction (Y direction).

  As shown in FIGS. 2 and 3A, the recoater 13 includes a container 15, a blade 16, and a screw member 21.

  The container 15 can store a powder material. The container 15 has a trapezoidal shape with a lower bottom shorter than the upper bottom, and extends in the vertical direction. The container 15 includes a first side wall 15A and a second side wall 15B that are spaced apart from each other in the vertical direction, a third side wall 15C and a fourth side wall 15D that are spaced apart from each other in the lateral direction, and the container 15 A bottom wall 15E located at the lower end of the container 15 and an upper wall 15F located at the upper end of the container 15.

  As shown in FIG. 3A, the first side wall 15A is located at one end of the container 15 in the vertical direction. The second side wall 15B is located at the other end of the container 15 in the vertical direction.

  As shown in FIG. 2, the third side wall 15C is located at one end of the container 15 in the lateral direction. The third side wall 15C connects one end of the first side wall 15A in the horizontal direction and one end of the second side wall 15B in the horizontal direction. The lower end portion of the third side wall 15C is located at a distance from the bottom wall 15E.

  4th side wall 15D is located in the other end part of the container 15 in a horizontal direction. The fourth side wall 15D connects the other end in the horizontal direction of the first side wall 15A and the other end in the horizontal direction of the second side wall 15B.

  The bottom wall 15E connects the lower end of the first side wall 15A and the lower end of the second side wall 15B. The bottom wall 15E is continuous with the lower end of the fourth side wall 15D, and is spaced from the lower end of the third side wall 15C.

  The lower end of the third side wall 15C, the one end in the lateral direction of the bottom wall 15E, and the first side wall 15A and the second side wall 15B define an outlet 17 for discharging the powder material. The discharge port 17 is located below the third side wall 15C. The discharge port 17 communicates the inside and outside of the container 15. The discharge port 17 extends in the vertical direction. The vertical dimension of the discharge port 17 is substantially the same as the vertical dimension of the stage 12.

  The upper wall 15F connects the upper end portion of the first side wall 15A and the upper end portion of the second side wall 15B. The upper wall 15F connects the upper end portion of the third side wall 15C and the upper end portion of the fourth side wall 15D.

  As shown in FIG. 1, the upper wall 15 </ b> F has a supply port 19 that receives the supply of the powder material. The supply port 19 is located at one end of the upper wall 15F in the vertical direction. Although not shown, the supply port 19 is connected to a tank in which the powder material is accommodated.

  As shown in FIG. 2, the blade 16 is disposed in the container 15. The blade 16 restricts the powder material stored in the container 15 from flowing out undesirably. The blade 16 can vibrate so that the powder material is discharged from the discharge port 17 at a desired timing. The blade 16 has an L shape when viewed from the side, and includes a plate 16A and a protrusion 16B.

  The plate 16A is disposed along the third side wall 15C. The protrusion 16B is located in the vicinity of the upper side of the discharge port 17 in the third side wall 15C. The protruding portion 16B protrudes from the lower end portion of the plate 16A toward the fourth side wall 15D. The free end portion (the end portion on the opposite side of the plate 16A) of the protruding portion 16B is disposed laterally with respect to the fourth side wall 15D. The distance L between the free end of the protrusion 16B and the fourth side wall 15D in the lateral direction is, for example, 0.3 mm or more, preferably 0.7 mm or more, for example 6.0 mm or less, preferably 1. 5 mm or less.

  As shown in FIG. 3A, the screw member 21 is configured to convey the powder material in the container 15 in the vertical direction (an example of the direction in which the rotation axis extends). The screw member 21 is disposed in the container 15. The screw member 21 includes a shaft portion 22 and screw blades 23.

  The shaft portion 22 has a substantially cylindrical shape extending in the vertical direction. Both ends of the shaft portion 22 in the vertical direction are rotatably supported by the first side wall 15A and the second side wall 15B.

  The screw blades 23 are provided on the peripheral surface of the shaft portion 22 and are located between the first side wall 15A and the second side wall 15B. The screw blades 23 have a spiral shape extending clockwise (clockwise) from one side in the vertical direction to the other side.

  The screw member 21 is rotatable with respect to the container 15 about an axis extending in the vertical direction. Specifically, the screw member 21 is rotatable in a first rotation direction and a second rotation direction that is opposite to the first rotation direction. When the screw member 21 rotates in the first rotation direction, the screw member 21 conveys the powder material in the container 15 from one side to the other side in the vertical direction (an example in which the axis extends). When the screw member 21 rotates in the second rotation direction, the screw member 21 conveys the powder material in the container 15 from the other side in the vertical direction to the one side.

(3) Powder Material As shown in FIG. 3C, the powder material is stored in the container 15 of the recoater 13. Specifically, the powder material is stored in a space above the projecting portion 16 </ b> B of the blade 16 inside the container 15. The powder material is not particularly limited, and examples thereof include known modeling materials that can be applied to three-dimensional additive manufacturing. Examples of the powder material include foundry sand, resin particles, ceramic particles, glass powder, and the like, and preferably, foundry sand.

  As the foundry sand, for example, a mixed sand of sand (described later) and a curing agent (described later), the foundry sand 2 shown in FIG. 8, and the like, preferably, the foundry sand 2 shown in FIG.

  As shown in FIG. 8, the foundry sand 2 includes a sand 3, a surface modified layer 4 containing a resin cured product that covers the sand 3, and a curing agent that adheres to the surface of the surface modified layer 4. Layer 5.

  Examples of the sand 3 include natural silica sand and artificial sand.

  Examples of the cured resin contained in the surface modification layer 4 include furan resins, phenol resins, epoxy resins, silicone resins, and resol type phenol resins. From the viewpoint of heat resistance, furan resins are preferable.

  The curing agent of the curing agent layer 5 includes, for example, an acid catalyst that cures a binder described later. Examples of the acid catalyst include aliphatic sulfonic acids (for example, methanesulfonic acid, ethanesulfonic acid, etc.), aromatic sulfonic acids (for example, benzenesulfonic acid, paratoluenesulfonic acid, xylenesulfonic acid, etc.), inorganic acids (for example, Sulfuric acid, phosphoric acid, hydrochloric acid, etc.), carboxylic acids (eg, maleic acid, oxalic acid, etc.) and the like. The acid catalyst can be used alone or in combination of two or more.

  The foundry sand 2 can be prepared by mixing a sand and a resin composition corresponding to the above-mentioned cured resin, and then adding a curing agent.

(4) Jet Head As shown in FIGS. 5A and 5B, the jet head 14 is configured to supply a binder to a layer of powder material formed on the stage 12. Although not shown, the jet head 14 is connected to a binder tank that accommodates the binder, and the binder is supplied from the binder tank. The jet head 14 is movable in the vertical direction and the horizontal direction so as to pass above the stage 12 in a state parallel to the stage 12 with a space therebetween.

  The binder is not particularly limited as long as the powder material can be hardened. As a binder, a furan resin composition, a phenol resin composition, an alkali phenol resin composition etc. are mentioned, for example, Preferably, a furan resin composition etc. are mentioned.

(5) Control Unit As shown in FIG. 1, the control unit 20 is configured to control the operations of the recoater 13 and the jet head 14. Moreover, the control part 20 can switch the rotation direction of the screw member 21 to a 1st rotation direction and a 2nd rotation direction (refer FIG. 3A-FIG. 3B). The control unit 20 is electrically connected to each of the recoater 13 and the jet head 14. The control unit 20 can receive 3D-CAD data transmitted from the outside.

(6) Modeling by 3D printer Next, the modeling method in the 3D printer 1 is demonstrated with reference to FIG. 3A-FIG. 7B.

  The modeling method in the 3D printer 1 includes a preparation step (see FIGS. 3A to 3B) for making the powder material in the container 15 substantially uniform, and a layer formation step (see FIGS. 4A and 4B) for forming the powder material in layers. And a binder supply step (see FIGS. 5A and 5B) for supplying a binder to the powder material layer and solidifying the powder material layer. And at least a layer formation process and a binder supply process are repeated, and a molded article is manufactured (refer FIG. 6A-FIG. 7B).

(6-1) Preparation Step As shown in FIG. 3A, in the preparation step, first, the powder material is supplied to the container 15 through the supply port 19. Then, after supplying the powder material, the control unit 20 rotates the screw member 21 in the first rotation direction R1 so that the powder material becomes uniform inside the container 15, and then the screw member 21 is moved to the first direction. 2 in the rotation direction R2.

  Specifically, the control unit 20 rotates the screw member 21 in the first rotation direction R1 until the first time T1 elapses from the supply start of the powder material. Thereby, the screw member 21 conveys the powder material deposited under the supply port 19 toward the other side in the vertical direction.

  The first time T1 is a time during which the screw member 21 rotating in the first rotation direction can transport the powder material located at one end in the vertical direction to the other end in the vertical direction inside the container 15. It is.

  Next, as illustrated in FIG. 3B, the control unit 20 switches the rotation direction of the screw member 21 from the first rotation direction R1 to the second rotation direction R2 after the first time T1 has elapsed. And the control part 20 rotates the screw member 21 to 2nd rotation direction R2 until 2nd time T2 passes since switching of a rotation direction. Thereby, the screw member 21 conveys the powder material which accumulates in the other end part of the vertical direction inside the container 15 toward the one side of the vertical direction so that it may become uniform.

  The second time T2 is a time during which the screw member 21 rotating in the second rotation direction can convey the powder material accumulated at the other end in the vertical direction in the container 15 so as to be uniform.

  Thereafter, the control unit 20 switches the rotation direction of the screw member 21 from the second rotation direction R2 to the first rotation direction R1 as necessary, and repeats the above operation.

  As described above, as shown in FIG. 3C, the powder material becomes substantially uniform inside the container 15, and the preparation of the recoater 13 is completed.

(6-2) Layer Formation Step Next, as shown in FIGS. 4A and 4B, in the layer formation step, the control unit 20 moves the recoater 13 that stores the powder material in the lateral direction while slightly vibrating the blade 16. Move to. Then, the recoater 13 discharges the powder material from the discharge port 17 onto the stage 12 in a layered manner (see FIG. 2). Thereby, the first powder material layer 25 (powder material layer) is formed on the stage 12.

(6-3) Binder Supply Process Next, as shown in FIGS. 5A and 5B, in the binder supply process, the control unit 20 uses the jet head 14 to generate the first powder material based on the received 3D-CAD data. A binder is supplied to a portion of the layer 25 that is to be a shaped object. As a result, a first supply portion 26 to which the binder is supplied is formed in the first powder material layer 25. In the first supply part 26, the supplied binder bonds the powder materials together. Thereby, the 1st supply part 26 is hardened.

  In addition, the control part 20 can implement the above-mentioned preparatory process simultaneously with a binder supply process. That is, while the jet head 14 supplies the binder to the first powder material layer 25, the powder material can be supplied to the container 15, and the powder material can be made substantially uniform inside the container 15.

(6-4) Repeating Layer Formation Step and Binder Supply Step Next, as shown in FIG. 6A, after the stage 12 is lowered by the thickness of the first powder material layer 25, the recoater 13 is moved to the first powder material. On the layer 25, the powder material is discharged again in a layered manner to form a second powder material layer 27 (powder material layer). Thereafter, as shown in FIG. 6B, the jet head 14 supplies the binder to the sand-shaped portion of the second powder material layer 27 to form the second supply portion 28.

  Similarly, as shown in FIG. 7A, the powder material layer formation by the recoater 13 and the binder supply by the jet head 14 are sequentially repeated. When the layer formation of the powder material is repeated n times, the first powder material layer 25 to the nth powder material layer are sequentially stacked, and the first supply portion 26 to the nth supply portion are sequentially formed.

  Thereafter, as shown in FIG. 7B, the portion of the powder material layer where the binder is not supplied is removed.

  The molded article 30 is manufactured by the above. In FIG. 7A, for convenience, the surface of the modeled object 30 is shown as having a step, but actually, the surface of the modeled object 30 is formed substantially smooth as shown in FIG. 7B. .

(7) Effects As shown in FIGS. 3A to 3C, in the 3D printer 1, the control unit 20 can switch the rotation direction of the screw member 21 between the first rotation direction R1 and the second rotation direction R2. To control. Therefore, after the screw member 21 is rotated in the first rotation direction R1 and the powder material is conveyed to the other side in the longitudinal direction, the rotation direction of the screw member 21 is switched to the second rotation direction R2, and the powder The material can be conveyed to one side in the longitudinal direction. Therefore, the powder material can be uniformly stored in the container 15. Further, since the powder material circulates inside the container 15, it is possible to suppress the powder material from staying without being discharged for a long time. As a result, the recoater 13 can accurately form the powder material in a layered shape, and the accuracy of the modeled object can be improved.

<Modification>
In the above embodiment, the start timing of the first time T1 (that is, the start timing of the first rotation direction R1 of the screw member 21) is the same as the start of supply of the powder material to the container 15, The start timing of the first time T1 is not limited to this. For example, after the supply of the powder material to the container 15 is completed, the first time T1 may be started and the screw member 21 may be rotated in the first rotation direction R1.

  In the above embodiment, the rotation direction of the screw member 21 is switched to the second rotation direction R2 after the first time T1 has elapsed, but the timing of switching the rotation direction is not limited to this. For example, the rotation of the screw member 21 may be stopped for a predetermined time during the switching between the first rotation direction R1 and the second rotation direction R2. Specifically, after the first time T1 has elapsed, the screw member 21 can be rotated in the second rotation direction R2 after the rotation of the screw member 21 is temporarily stopped.

  In said embodiment, although the control part 20 controls switching of the rotation direction of the screw member 21 on the basis of time, control of the control part 20 is not limited to this. For example, the control unit 20 may control switching of the rotation direction of the screw member 21 based on the detection result of the sensor.

  In such a modification, the 3D printer 1 further includes a sensor 50 as indicated by a virtual line in FIG. 3B. Further, the upper wall 15 </ b> F of the container 15 has a sensor opening 51 for the sensor 50 to detect the powder material in the container 15. The sensor opening 51 is located at the other end of the upper wall 15F in the vertical direction.

  When the sensor 50 detects that the amount of the powder material accumulated in the other side portion in the vertical direction inside the container 15 exceeds the predetermined amount via the sensor opening 51, the control unit 20 detects the screw member 21. The rotation direction is switched from the first rotation direction R1 to the second rotation direction R2. In addition, after the sensor 50 detects that there is a powder material on the other side portion in the vertical direction inside the container 15 through the sensor opening 51, the rotation of the screw member 21 in the first rotation direction R1 is performed. The rotation direction of the screw member 21 can also be switched to the second rotation direction R2 after maintaining for a predetermined time.

  In the above embodiment, the 3D printer 1 is an ink jet type three-dimensional additive manufacturing apparatus that supplies a binder to the powder material layer and hardens it, but the three-dimensional additive manufacturing apparatus is not limited to this. The three-dimensional additive manufacturing apparatus may be a melting or sintering type three-dimensional additive manufacturing apparatus that hardens a powder material layer by melting or sintering. In this case, the three-dimensional additive manufacturing apparatus includes, in place of the jet head 14, a melting part capable of melting the powder material or a sintering part capable of sintering the powder material.

  Also by these, the same effect as said embodiment can be show | played. These embodiments and modifications can be combined as appropriate.

DESCRIPTION OF SYMBOLS 1 3D printer 13 Recoater 15 Container 20 Control part 21 Screw member R1 1st rotation direction R2 2nd rotation direction

Claims (1)

After forming the powder material in layers, a three-dimensional additive manufacturing apparatus that repeatedly forms by solidifying the powder material layer,
A discharge unit capable of storing the powder material, and discharging the stored powder material in a layered manner;
A control unit for controlling the operation of the discharge unit,
The discharge part is
A container capable of storing the powder material;
A screw member that is rotatable relative to the container, and that conveys the powder material in the container in a direction in which a rotation axis extends.
The control unit controls the rotation direction of the screw member to be switchable between a first rotation direction and a second rotation direction that is opposite to the first rotation direction. Original additive manufacturing equipment.

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