Additive manufacturing equipment

Abstract

In powder bed additive manufacturing, the table position control is highly accurate, improving additive manufacturing accuracy. [Solution] The additive manufacturing device 1 comprises a table 12 on which the powder material is spread, a master linear motion mechanism 13 extending in the vertical direction, a slave linear motion mechanism 21 extending in the vertical direction and arranged on the opposite side of the master linear motion mechanism in the horizontal direction with the table as the reference, a base part 19 whose base end in the horizontal direction is attached to the master linear motion mechanism and whose tip end in the horizontal direction is attached to the slave linear motion mechanism, and a support 18 connecting the underside of the table to the base part, the base part 19 having an asymmetric shape with respect to the support, and configured so that the second moment of area on the base end side is greater than the second moment of area on the tip end side.

Description

[Technical Field]

[0001] The present invention relates to an additive manufacturing apparatus. [Background technology]

[0002] Additive manufacturing machines are known as devices that build three-dimensional objects by layering and hardening materials. There are various methods for additive manufacturing, one of which is powder bed additive manufacturing. In powder bed additive manufacturing, powder material is first spread on a table inside the machine to form a thin layer of powder material. Next, a beam such as a laser is irradiated at a desired position on the powder material to harden the powder material at that position. After the powder material has selectively hardened, more powder material is formed on top of that powder material and hardened by the beam. This process is repeated to create the object.

[0003] In powder bed additive manufacturing, powder material is layered sequentially on a table, and the thickness of the powder material layer increases as the layering progresses. Therefore, in additive manufacturing devices, the vertical position of the table is adjusted as the layering progresses. This adjustment of the table position is generally performed based on the thickness of the powder material layer. However, in additive manufacturing, the weight of the powder material loaded on the table increases as the layering progresses. Therefore, the weight of the powder material may cause the table position to deviate from the specified position. Since deviation of the table position from the specified position affects the accuracy of additive manufacturing, it is desirable to precisely adjust the table position.

[0004] An additive manufacturing apparatus is disclosed in, for example, Patent Document 1. In this additive manufacturing apparatus, the table is driven by a drive unit, which is controlled by a control unit. The control unit controls the drive unit to match the current load on the table based on factors such as the amount of material laid per layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-25762 Summary of the Invention [Problem to be solved by the invention]

[0006] The additive manufacturing device of Patent Document 1 controls the table position taking into account the load on the table, thereby improving the accuracy of table position control. However, even with this additive manufacturing device, the table position may still deviate from the target position. In additive manufacturing, the thickness of the powder material spread on the table in one supply is, for example, several tens of micrometers, so it is desirable to control the table position with higher accuracy. In particular, in additive manufacturing of large objects or multi-cavity additive manufacturing, a large amount of powder material is supplied onto the table, which increases the load on the table. As a result, the table position is likely to deviate from the target position.

[0007] An object of the present invention is to improve the accuracy of additive manufacturing by controlling the position of a table with high precision in powder bed additive manufacturing. [Means for solving the problem]

[0008] The additive manufacturing apparatus according to the present invention is an additive manufacturing apparatus that manufactures a model by powder bed additive manufacturing, in which a beam is irradiated onto powder material spread on a table to harden the powder material, and is characterized in that it comprises: a table on which the powder material is spread; a master linear motion mechanism that extends in the vertical direction; a slave linear motion mechanism that also extends in the vertical direction and is provided on the opposite side of the master linear motion mechanism in the horizontal direction with the table as a reference; a base part whose base end in the horizontal direction is attached to the master linear motion mechanism and whose tip end in the horizontal direction is attached to the slave linear motion mechanism; and a support pillar that connects the underside of the table to the base part, wherein the base part has an asymmetric shape with respect to the support pillar, and the second moment of area on the base end side is greater than the second moment of area on the tip end side.

[0009] With this arrangement, the base supporting the table can have a large bending rigidity on the side of the master linear motion mechanism. This makes it easier to reduce the influence of deflection due to the weight of the powder material on the master linear motion mechanism side, facilitating accurate vertical position control. This in turn makes it easier to control the table position while taking into account the influence of changes in the table's posture due to the weight of the powder material, thereby enabling more accurate table position control than ever before.

[0010] In order to increase the second moment of area on the master linear motion mechanism side of the base portion while reducing the weight of the mechanical structure driven by the master linear motion mechanism, the base portion may have a bottom portion extending horizontally, a base end side wall portion erected relative to the bottom portion and attached to the master linear motion mechanism, and a tip end side wall portion erected relative to the bottom portion and attached to the slave linear motion mechanism, and may be configured so that the base end side wall portion has a larger vertical dimension than the tip end side wall portion.

[0011] In order to change the second moment of area of ​​the base portion from the base end side to the tip end side and to make it difficult for the base end side wall portion and tip end side wall portion of the base portion to collapse toward the support side, the base portion may further have a connecting wall portion that is erected relative to the bottom and connects the base end side wall portion and the tip end side wall portion, and the connecting wall portion may have a portion whose vertical dimension decreases from the base end side to the tip end side of the base portion.

[0012] An example of an embodiment in which the position of the table can be accurately controlled using a simple control system is one that includes a control unit that controls the master linear motion mechanism and the slave linear motion mechanism to move the table in the vertical direction in stages, and controls the vertical position of the table when supplying the powder material to the table so that the powder material is sequentially stacked on the table by the material supply mechanism, and the control unit controls the master linear motion mechanism to control the vertical position of the table, and controls the slave linear motion mechanism to follow the master linear motion mechanism.

[0013] If the control unit corrects the vertical position of the table when supplying the powder material to the table based on changes in the posture of the master linear motion mechanism or the structure supporting it due to the weight of the powder material spread on the table, control can be achieved that takes into account not only simple sinking due to the weight of the powder material, but also changes in the posture of the entire machine due to bending and tipping caused by this.

[0014] A specific control mode of the master linear motion mechanism and the slave linear motion mechanism is one in which the master linear motion mechanism is equipped with a linear encoder extending at least in the vertical direction and is controlled by position feedback based on the linear encoder, and the slave linear motion mechanism is controlled to follow the current position obtained by the linear encoder provided in the master linear motion mechanism.

[0015] According to the layered manufacturing device of the present invention, in powder bed type layered manufacturing, it is possible to achieve high precision in table position control and improve layered manufacturing accuracy. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a front view schematically showing the configuration of an additive manufacturing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of the master linear motion mechanism and its surrounding structure. [Figure 3] FIG. 2 is an enlarged view of a slave linear motion mechanism and its surrounding configuration. [Figure 4] 10A and 10B are diagrams for explaining changes in the posture of the master linear motion mechanism and the support structure. [Figure 5] 1A-1C are diagrams showing a schematic diagram of a process in which powder material is deposited on a table of an additive manufacturing apparatus. [Figure 6] FIG. 2 is a functional block diagram showing a control unit, a master linear motion mechanism, a slave linear motion mechanism, and a material supply mechanism in the additive manufacturing apparatus of the present embodiment. [Figure 7]FIG. 10 is a diagram showing an information table describing the relationship between the powder material to be layered on the table, its weight, and the amount of change in posture of the master linear motion mechanism and the support structure. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] FIG. 1 is a front view schematically illustrating the configuration of an additive manufacturing apparatus according to this embodiment. The additive manufacturing apparatus 1 is an apparatus for performing additive manufacturing using a powder bed method. The additive manufacturing apparatus 1 includes a processing chamber 11 for performing additive manufacturing. The processing chamber 11 has a housing shape. A portion of the underside of the processing chamber 11 is formed by a table 12 (table mechanism 21) for forming an object. The table 12 is configured to be movable in the vertical direction and is driven by linear motion mechanisms 13 and 20. The linear motion mechanisms 13 and 20 are controlled by a control unit 17. Powder material is supplied onto the table 12 from a material supply mechanism 14, and a powder material M is formed. After one layer of powder material M is formed, a beam is irradiated from a beam head 15 onto any position on the powder material M, and the powder material at that position hardens. After the beam irradiation is completed, the table 12 is lowered by the linear motion mechanisms 13 and 20, and a next layer of powder material M is formed on the previously formed powder material M, and the next layer of powder material M is irradiated with the beam. By repeating this process, a three-dimensional object is created.

[0019] Here, the front of the additive manufacturing apparatus 1 refers to the side where a door for removing the molded object from the processing chamber 11 is provided. The direction from the back of the additive manufacturing apparatus 1 to the front is called the front, and the direction from the front to the back is called the back. When viewed from the front, the direction toward the left of the additive manufacturing apparatus 1 is called the left, and the direction toward the right is called the right. When viewed from the front, the direction toward the top (ceiling) of the additive manufacturing apparatus 1 is called the up, and the direction toward the bottom (floor) is called the down. The up-down direction refers to the direction that coincides with the vertical direction when the additive manufacturing apparatus 1 is placed. The horizontal direction refers to the direction included in a plane whose normal is the up-down direction. The configuration of the additive manufacturing apparatus 1 will be described in detail below.

[0020] The beam head 15 is provided outside the processing chamber 11 and irradiates the powder material M with a beam through an irradiation window provided in the processing chamber 11. The beam head 15 irradiates, for example, a laser beam. However, the beam head 15 may irradiate other beams such as an electron beam. The beam head 15 is configured to be able to irradiate the beam at any position on the powder material M spread on the table 12.

[0021] The table mechanism 21 includes a table 12, a support 18, and a base 19 (basket). The table 12 is also called a build platform, and powder material is piled up on it to form a molded object. The table 12 is configured to be movable below the bottom surface of the processing chamber 11. The table 12 moves downward as the powder material M is piled up. The shape of the table 12 is not particularly limited as long as it is capable of stacking the powder material M. A support 18 is provided on the bottom surface of the table 12. The support 18 has a cylindrical shape and extends downward from the bottom surface of the table 12. The support 18 is attached to the base 19.

[0022] The base 19 has a box shape. The base 19 is configured so that the left end is larger in the vertical direction and the right end is smaller in the vertical direction than the left end. The base 19 has a shape in which the portion on the linear motion mechanism 13 side and the portion on the linear motion mechanism 20 side are asymmetric. In other words, the base 19 has an asymmetric shape in the horizontal direction with respect to the support 18 located in the center of the base 19. Here, the side of the linear motion mechanism 13 to which the base 19 is connected is defined as the base end side in the horizontal direction, and the side of the linear motion mechanism 20 to which the base 19 is connected is defined as the tip side in the horizontal direction. The base 19 is configured so that the second moment of area of ​​the portion on the linear motion mechanism 13 side is larger than the second moment of area of ​​the portion on the linear motion mechanism 20 side. More specifically, the base 19 includes a bottom 191 to which a support column is attached, a base side wall 192 extending upward from the left end of the bottom 191, and a tip side wall 193 extending upward from the right end of the bottom 191. The bottom 191 has a flat plate shape and is provided horizontally. The base side wall 192 is longer in the up-down direction than the tip side wall 193. A front side wall may be provided extending upward from the front end of the bottom 191. A rear side wall may be provided extending upward from the rear end of the bottom 191. The base side wall 192, the tip side wall 193, the front side wall, and the rear side wall may be connected. In this case, the front side wall and the rear side wall each function as a connecting wall 194 connecting the base side wall and the tip side wall. The connecting wall portion 194 has a portion whose dimension in the vertical direction decreases from the base end side to the tip end side. The base portion 19 configured in this manner is attached to the linear motion mechanisms 13, 20. The linear motion mechanism 13 is provided on the left side of the table 12. The linear motion mechanism 20 is provided on the right side of the table 12. Hereinafter, the linear motion mechanism 13 will be referred to as the master linear motion mechanism 13, and the linear motion mechanism 20 will be referred to as the slave linear motion mechanism 20.

[0023] 2 is an enlarged view of the master linear motion mechanism and its peripheral configuration. Master linear motion mechanism 13 includes a ball screw 131, a slide portion 132 that moves along ball screw 131, a guide portion 133 that guides slide portion 132 so as to move in the vertical direction, and a drive device 134 that rotates ball screw 131. Master linear motion mechanism 13 also includes a position sensor (not shown), such as a linear encoder, to detect the vertical position of table 12.

[0024] The ball screw 131 is composed of a screw shaft 1311 and a ball nut 1312. The screw shaft 1311 is rotated around its central axis by a drive unit 134. The screw shaft 1311 extends in the vertical direction. Both ends of the screw shaft 1311 in the vertical direction are fixed to the support structure 16 via fixing members 1313. The fixing members 1313 include bearings and the like, and are configured to allow the screw shaft 1311 to rotate while immobilizing the screw shaft 1311 relative to the support structure 16. The ball nut 1312 moves in the vertical direction along the screw shaft 1311 as the screw shaft 1311 rotates. A slide portion 132 is attached to the ball nut 1312.

[0025] A base end wall portion 192 of the base portion 19 is attached to the slide portion 132. The base end wall portion 192 is an example of a first end portion of the table mechanism 21. The slide portion 132 moves in the vertical direction together with the ball nut 1312. The slide portion 132 is inserted into the guide portion 133. The guide portion 133 extends in the vertical direction. The guide portion 133 restricts the slide portion 132 from rotating due to the rotation of the screw shaft 1311, and guides the slide portion 132 to move in the vertical direction. The guide portion 133 is attached to the support structure 16.

[0026] The driving device 134 rotates the screw shaft 1311 around its central axis. The driving device 134 is not particularly limited, but may be, for example, a servo motor. The driving device 134 is provided on the screw shaft 1311. The driving device 134 is directly connected to the upper end of the screw shaft 1311. That is, the driving device 134 rotates the screw shaft 1311 by a direct drive system. However, the driving device 134 may be indirectly connected to the screw shaft 1311. That is, a power transmission mechanism such as a belt or a reducer may be interposed between the driving device 134 and the screw shaft 1311.

[0027] 3 is an enlarged view of the slave linear motion mechanism 20 and its surrounding configuration. The slave linear motion mechanism 20 includes a ball screw 201, a slide part 202 that moves along the ball screw 201, and a drive device 204 that rotates the ball screw 201.

[0028] The ball screw 201 is composed of a screw shaft 2011 and a ball nut 2012. The screw shaft 2011 is rotated around its central axis by a driving device 204. The screw shaft 2011 extends in the vertical direction. Both ends of the screw shaft 2011 in the vertical direction are fixed to the support structure 16 via fixing members 2013. The fixing members 2013 include bearings and the like, and are configured to allow the screw shaft 2011 to rotate while immobilizing the screw shaft 2011 relative to the support structure 16. The ball nut 2012 moves in the vertical direction along the screw shaft 2011 as the screw shaft 2011 rotates. A slide portion 202 is attached to the ball nut 2012.

[0029] A tip side wall portion 193 of the base portion 19 is attached to the slide portion 202. The tip side wall portion 193 is an example of a second end portion of the table mechanism 21. The slide portion 202 moves in the up and down direction together with the ball nut 2012. The drive device 204 is similar to the drive device 134, and therefore a description thereof will be omitted.

[0030] The support structure 16 is provided outside the table mechanism 21, the master linear motion mechanism 13, and the slave linear motion mechanism 20. The support structures 16 are provided on the left and right sides of the table mechanism 21. A left portion 161 (see FIG. 2) of the support structure 16 is provided adjacent to the master linear motion mechanism 13. A right portion 162 (see FIG. 3) of the support structure 16 is provided adjacent to the slave linear motion mechanism 20. The processing chamber 11 is provided on top of the support structure 16, and the support structure 16 supports the processing chamber 11. The support structure 16 forms a base for the entire additive manufacturing apparatus 1, supporting the processing chamber 11, the master linear motion mechanism 13, the slave linear motion mechanism 20, and the table mechanism 21.

[0031] As described above, in the additive manufacturing apparatus 1, the table mechanism 21, the master linear motion mechanism 13, the slave linear motion mechanism 20, and the support structure 16 are directly or indirectly connected. Therefore, the load applied to the table 12 is applied to the support structure 16 via the table mechanism 21, the master linear motion mechanism 13, and the slave linear motion mechanism 20. In other words, the additive manufacturing apparatus 1 is configured such that the load of the powder material M stacked on the table 12 is applied to the master linear motion mechanism 13, the slave linear motion mechanism 20, and the support structure 16. Therefore, the weight of the powder material loaded on the table 12 may cause the postures of the master linear motion mechanism 13, the slave linear motion mechanism 20, and the support structure 16 to change. A change in posture refers to the linear motion mechanism 13 and the support structure 16 tilting or deforming due to bending more than when no powder material is loaded on the table 12.

[0032] FIG. 4 is a diagram illustrating the posture changes of the master linear motion mechanism and the support structure. For example, when the weight of powder material M is loaded onto the table 12, the weight is transferred to the slide portion 132 via the support column 18 and the base portion 19. Because the slide portion 132 is inserted into the guide portion 133, the weight of the powder material M is transferred to the guide portion 133 and the left portion 161 of the support structure 16 that supports the guide portion 133. Furthermore, because the ball nut 1312 fixed to the slide portion 132 is inserted into the screw shaft 1311, the weight of the powder material M is transferred to the screw shaft 1311 and the left portion 161 of the support structure 16 that supports the screw shaft 1311. This causes the master linear motion mechanism 13 and the left portion 161 of the support structure 16 to tilt toward the table mechanism 21. As a result, the table 12 may deviate from the target position, which may affect the accuracy of additive manufacturing. Furthermore, if the table 12 tilts from the horizontal, the distance to the beam head may deviate from the design value depending on the location on the table 12. In the drawing, the inclination of the inner wall of the left part 161 of the support structure 16 is shown by a two-dot chain line, but the inclination is exaggerated for ease of understanding.

[0033] The weight of the powder material M is also applied to the slave linear motion mechanism 20 and the right portion of the support structure 16. However, unlike the master linear motion mechanism 13, the slave linear motion mechanism 20 does not include a guide unit. Furthermore, the slave linear motion mechanism 20 does not include a linear encoder for detecting its vertical position. Therefore, the slave linear motion mechanism 20 and the right portion 162 of the support structure 16 do not constrain the position of the base portion 19 as much as the master linear motion mechanism 13 and the left portion 161 of the support structure 16 do. Therefore, in this embodiment, changes in the posture of the master linear motion mechanism 13 and the left portion 161 of the support structure 16 can be considered to affect the positional accuracy of the table 12. In other words, the table mechanism 21 can be considered to be substantially cantilevered by the base end side wall portion 192 of the base portion 19.

[0034] In response to the above-described changes in posture of the master linear motion mechanism 13 and the left part 161 of the support structure 16, the additive manufacturing apparatus 1 of this embodiment controls the position of the table 12 by taking into account the changes in posture of the master linear motion mechanism 13 and the left part 161 of the support structure 16. This point will be described in detail below, but first, the control of the position of the table 12 when the weight of the powder material loaded on the table 12 is not taken into account will be described.

[0035] FIG. 5 is a diagram schematically illustrating the process of layering powder material on the table of an additive manufacturing device. The process proceeds in the order of (A) to (C) in the figure. Referring to (A) in the figure, first, the table 12, which is positioned on the same plane as the bottom surface of the processing chamber 11 as its initial position, is lowered so that it is positioned below the bottom surface of the processing chamber 11. The amount of downward movement of the table 12 is not particularly limited, but it corresponds to, for example, the thickness of the first layer of powder material M1 to be spread. In other words, the table 12 is moved to the target position P1 for spreading the first layer of powder material M1.

[0036] Referring to (B) in the figure, next, the material supply mechanism 14 moves horizontally under the processing chamber 11 and spreads the first layer of powder material M1 on the table 12. The material supply mechanism 14 spreads the powder material on the table 12, for example, by using a roller. Thereafter, the beam head 15 irradiates a beam at a predetermined position in accordance with the processing program to harden the powder material.

[0037] Referring to (C) in the figure, next, the table 12 is lowered to a target position P2 below the target position P1. The target position P2 is the position of the table 12 for spreading the second layer of powder material M2. At the target position P2, the powder material M1 on the table 12 is located below the bottom surface of the processing chamber 11. In this case, the amount of downward movement of the table 12 is not particularly limited, but may be, for example, equivalent to the thickness of the second layer of powder material M2 to be spread. Thereafter, as described above, the material supply mechanism 14 spreads new powder material M2 on top of the already spread powder material M1. Then, the beam emitted by the beam head 15 hardens the powder material at a predetermined position of the new powder material M2. The additive manufacturing apparatus 1 repeats this process to form a three-dimensional object.

[0038] However, in reality, the weight of the powder material is loaded onto the table 12, causing the attitudes of the master linear motion mechanism 13 and the left part 161 of the support structure 16 to change, causing the position of the table 12 to deviate from the target position. The deviation of the table 12 from the target position increases as the amount of powder material spread on the table 12 increases. Therefore, in the additive manufacturing apparatus 1 of this embodiment, the control unit 17 controls the position of the table 12 so as to reduce the deviation (displacement) of the table 12 from the target position.

[0039] 6 is a functional block diagram showing the control unit, master linear motion mechanism, slave linear motion mechanism, and material supply mechanism in the layered manufacturing apparatus of this embodiment. The control unit 17 is configured by a computer including a processor, memory, etc., and controls each unit of the layered manufacturing apparatus.

[0040] When a processing program for forming a molded object is executed based on an external input or the like, the control unit 17 transmits a position command to the master linear motion mechanism 13 to move the table 12 to a target position for spreading the first layer of powder material. Upon receiving the position command, the master linear motion mechanism 13 moves the table 12 to the target position. The position of the table 12 is transmitted to the control unit 17 as position information from a position sensor (position feedback).

[0041] When the control unit 17 receives the position information of the master linear motion mechanism 13, it transmits a follow-up command to the slave linear motion mechanism 20 to operate the slave linear motion mechanism 20 so as to align it with the master linear motion mechanism 13. The control unit 17 transmits the follow-up command to the slave linear motion mechanism 20 so that the slave linear motion mechanism 20 corrects the tilt of the table 12 by adjusting the position of the tip side wall portion 193 of the base portion 19. The control unit 17 transmits the follow-up command to the slave linear motion mechanism 20 so that the tilt of the table 12 falls within a predetermined range.

[0042] When the control unit 17 determines that the table 12 has reached the target position based on information from the position sensor, it sends a material supply command to the material supply mechanism 14. Upon receiving the material supply command, the material supply mechanism 14 moves horizontally and spreads the powder material over the table 12. When the material supply mechanism 14 has finished spreading the powder material, it sends supply completion information to the control unit 17.

[0043] When the control unit 17 receives the supply completion information, it moves the table 12 to the target position for spreading the powder material in the second layer. In this case, the control unit 17 sends a corrected position command that corrects the position command sent to the master linear motion mechanism 13. The corrected position command is the amount of movement of the table 12 from the target position P1 for spreading the powder material in the first layer to the target position P2 for spreading the powder material in the second layer, corrected by the amount of displacement of the table 12 from the target position P2 due to the weight of the powder material. The corrected position command is written in an information table stored in advance in the memory of the control unit 17.

[0044] FIG. 7 is a diagram showing an information table describing the relationship between the powder material layered on the table, its weight, and the posture change amount of the master linear motion mechanism and the left part of the support structure. The information table describes weight information, which is the weight of each powder material layered on the table 12. For example, the weight information describes that the weight of the powder material L1 in the first layer is W1 and the weight of the powder material L2 in the second layer is W2. In this embodiment, all the powder material layers layered on the table 12 have the same weight, but the weights of the powder material layers may be different. The information table also describes posture change amount information regarding the posture change amount of the master linear motion mechanism 13 and the left part 161 of the support structure 16 corresponding to the number of times (number of layers) the powder material is fed. For example, when the second layer of powder material L2 is spread on the table 12, the table 12 is loaded with the total weight W1 + W2 of the powder material layers in the first and second layers. Therefore, in this case, the posture change amount information describes the posture change amount C2 of each of the master linear motion mechanism 13 and the left part 161 of the support structure 16 when the total weight W1+W2 of the powder material for the first and second layers is loaded onto the table 12. In this case, the information table describes the displacement amount d2, which is the deviation from the target position of the table 12 when the posture change amount is C2 (i.e., the target position when the next, third layer of powder material is to be spread on the table 12 with the weights of the powder material for the first and second layers loaded on the table 12). When spreading the powder material for the third layer, the control unit 17 sends a corrected position command to the master linear motion mechanism 13, correcting the movement amount to the target position by the displacement amount d2. The posture change amount described in the information table can be obtained in advance, for example, by numerical simulation.

[0045] In this way, in the additive manufacturing apparatus 1 of this embodiment, the position of the table 12 is controlled taking into account deviation of the table 12 from the target position due to the weight of the powder material sequentially piled up on the table 12. Therefore, when spreading the powder material and when irradiating the powder material with a beam, the table 12 is positioned at or near the target position. This maintains an appropriate distance between the powder material and the beam head 15, improving the accuracy of additive manufacturing.

[0046] In the additive manufacturing apparatus 1, the master linear motion mechanism 13 supports a base end wall portion 192 (a first end portion of the table mechanism 21) of the base portion 19, and the slave linear motion mechanism 20 supports a tip end wall portion 193 (a second end portion of the table mechanism 21) opposite the base end wall portion 192. The master linear motion mechanism 13 predominantly determines the vertical position of the table mechanism 21, and the slave linear motion mechanism 20 operates to follow the master linear motion mechanism 13. This configuration makes it easy to align the vertical positions of the base end wall portion 192 and the tip end wall portion 193 of the base portion 19. In other words, the tilt of the table 12 can be corrected. Correcting the tilt of the table 12 prevents the distance from the beam head to the powder material from deviating from the design value. Therefore, the additive manufacturing apparatus 1 can improve the accuracy of additive manufacturing.

[0047] Furthermore, in the additive manufacturing apparatus 1, the table 12, which moves in the vertical direction, is supported by a master linear motion mechanism 13 and a slave linear motion mechanism 20, which are provided on the left and right sides of the table 12 and extend in the vertical direction. In an additive manufacturing apparatus 1 configured in this manner, the master linear motion mechanism 13 is prone to tilting (deflecting) due to the load applied to the table 12, and its posture is prone to change. In other words, the weight of the powder material easily causes the table 12 to deviate from the target position. However, the control unit 17 controls the position of the table 12 by taking into account the deviation of the table 12 from the target position due to the weight of the powder material. Therefore, with the additive manufacturing apparatus 1, the accuracy of additive manufacturing is improved even in a configuration in which the weight of the powder material easily causes the table 12 to deviate from the target position.

[0048] The above-described embodiments are illustrative in all respects and are not limiting. Modifications and variations are possible for those skilled in the art. The scope of the present invention is defined not by the above-described embodiments but by the claims. Furthermore, the scope of the present invention includes modifications from the embodiments within the scope of the claims and their equivalents.

[0049] For example, in the above embodiment, a configuration has been described in which the master linear motion mechanism 13 includes the guide portion 133, and the slave linear motion mechanism 20 does not include a guide portion. However, the slave linear motion mechanism 20 may include a guide portion, similar to the master linear motion mechanism 13. Such a configuration is effective, for example, in cases where it is desired to suppress shaking of the slave linear motion mechanism 20 in the front-to-rear direction.

[0050] For example, the correction of the position command sent to the linear motion mechanism may be performed every time the powder material is spread on the table, or may be performed after the powder material has been spread a predetermined number of times.

[0051] For example, in the above-described embodiment, the deviation of the table from the target position is calculated in advance based on the posture changes of both the linear motion mechanism and the support structure, but the deviation of the table from the target position may also be calculated in advance based on the posture changes of either the linear motion mechanism or the support structure. [Explanation of symbols]

[0052] 1: Additive manufacturing equipment 11: Processing room 20: Table mechanism 12: Table 18: Strut 19: Base 191: Bottom 192:Proximal side wall part 193: Tip side wall 13: Master linear mechanism 131: Ball screw 1311: Screw shaft 1312: Ball nut 1313: Fixing member 132: Slide section 133: Guide section 134: Drive unit 14: Material supply mechanism 15: Beam Head 16:Support structure 17: Control section 21: Slave linear motion mechanism M,M1,M2: Powder material P1, P2: Target locations

Claims

1. 1. An additive manufacturing apparatus for manufacturing a model by powder bed additive manufacturing, in which a beam is irradiated onto a powder material spread on a table to harden the powder material, a table on which the powder material is spread; a master linear motion mechanism extending in the vertical direction; a slave linear motion mechanism extending in a vertical direction and provided on the opposite side of the master linear motion mechanism in a horizontal direction with the table as a reference; a base portion whose base end side in the horizontal direction is attached to the master linear motion mechanism and whose tip end side in the horizontal direction is attached to the slave linear motion mechanism; a support connecting the underside of the table to the base, The base portion has an asymmetric shape with respect to the support pillar, and the second moment of area on the base end side is larger than the second moment of area on the tip end side.

2. The base portion is A horizontally extending bottom, a base end side wall portion that stands upright relative to the bottom portion and is attached to the master linear motion mechanism; a tip side wall portion that stands upright relative to the bottom portion and is attached to the slave linear motion mechanism, The layered manufacturing device according to claim 1 , wherein the base end side wall portion is configured to have a larger vertical dimension than the tip end side wall portion.

3. The base portion further includes: a connecting wall portion that is erected on the bottom portion and connects the base end side wall portion and the tip end side wall portion, The layered manufacturing device according to claim 2 , wherein the connecting wall portion has a portion whose vertical dimension decreases from the base end side to the tip end side of the base portion.

4. A material supply mechanism for supplying the powder material onto the table; a control unit that controls the master linear motion mechanism and the slave linear motion mechanism to move the table in a vertical direction in a stepwise manner, and controls the vertical position of the table when the powder material is supplied to the table by the material supply mechanism so that the powder material is sequentially piled up on the table, The control unit The layered manufacturing apparatus according to claim 1 , wherein the master linear motion mechanism is controlled to control the vertical position of the table, and the slave linear motion mechanism is controlled to follow the master linear motion mechanism.

5. 5. The additive manufacturing device of claim 4, wherein the control unit corrects the vertical position of the table when supplying the powder material to the table based on a change in posture of either the master linear motion mechanism or a structure supporting it due to the weight of the powder material spread on the table.

6. the master linear motion mechanism includes a linear encoder extending at least in a vertical direction, and is controlled by position feedback based on the linear encoder; The additive manufacturing apparatus according to claim 4 , wherein the slave linear motion mechanism is controlled to follow a current position acquired by a linear encoder provided in the master linear motion mechanism.

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