Modeling data creation device, three-dimensional additive manufacturing system, and three-dimensional additive manufacturing method

Abstract

To provide a technique to reduce a variation of sparsity / density of scanning lines when generating the scanning lines for molding an article by three-dimensional laminate molding.SOLUTION: A molding data creation device creates molding data for controlling a three-dimensional laminate molding device configured to melt cross-sectional shapes of respective layers by irradiation of beams to mold an article. The molding data creation device includes a molding date generation part configured to: generate a plurality of scanning lines in a prescribed beam scanning method to a region of a cross-sectional shape cut out from three-dimensional shape data of an article; and generate a correction scanning line to a portion where an arrangement of the scanning lines is sparse and / or a portion where the arrangement is dense.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a modeling data creation device, a three-dimensional layer manufacturing system, and a three-dimensional layer manufacturing method.

Background Art

[0002] As one of the modeling methods for modeling an article, a powder bed fusion bonding method is known. The powder bed fusion bonding method is a modeling method in which a beam is selectively irradiated onto the surface of a powder layer (hereinafter also referred to as a "modeling surface") formed by spreading powder with a predetermined thickness, thereby melting and solidifying a portion of the cross-sectional shape of the article to be modeled. In the powder bed fusion bonding method, each powder layer is stacked one by one to model an article (such as a part) by sequentially lowering a modeling plate every time the powder of each layer is melted and solidified. A three-dimensional layer manufacturing apparatus adopting the powder bed fusion bonding method is described in, for example, Patent Document 1.

[0003] The operation of the three-dimensional layer manufacturing apparatus is controlled according to an operation sequence program (hereinafter also referred to as "modeling data") prepared in advance based on three-dimensional shape data. The three-dimensional shape data is data for specifying the three-dimensional shape of an article generated by three-dimensional CAD (Computer-Aided Design) or the like. The modeling data is generally created by a computer device (hereinafter referred to as a "modeling data creation device") incorporated with a program generally called CAM (Computer Aided Manufacturing) software, using the three-dimensional shape data of the article for the modeling purpose. The CAM software can be executed on any computer.

[0004] As the processing of the CAM software in the modeling data creation device, first, cross-sectional shapes of each layer are cut out from the input three-dimensional shape data at intervals of the thickness of one layer. Next, modeling data for melting the cross-sectional shape of each layer is generated. The modeling data includes data of scanning lines for melting a portion of the cross-sectional shape of each layer by beam scanning.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-7065 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, in conventional 3D printing data creation devices, when multiple scan lines are generated in the cross-sectional area of ​​each layer using a predetermined beam scanning method, there are instances where the scan lines are too far apart or too close together. As a result, when a 3D additive manufacturing device is operated based on the 3D printing data created by the 3D printing data creation device, melting defects due to insufficient melting are more likely to occur in areas where the scan lines are too far apart, and melting defects due to excessive melting are more likely to occur in areas where the scan lines are too close together.

[0007] The present invention was made to solve the above problems, and its purpose is to provide a technology that can reduce variations in the density of scan lines when generating scan lines for fabricating an article by three-dimensional additive manufacturing. [Means for solving the problem]

[0008] The present invention relates to a manufacturing data creation apparatus that creates manufacturing data for controlling a three-dimensional additive manufacturing apparatus that creates an article by melting the cross-sectional shape of each layer by beam irradiation, and comprises a manufacturing data generation unit that generates a plurality of scan lines in a predetermined beam scanning method in a region of the cross-sectional shape cut out from the three-dimensional shape data of an article, and generates correction scan lines in parts where the arrangement of the scan lines is sparse and / or dense.

[0009] The present invention provides a three-dimensional additive manufacturing system comprising: a three-dimensional additive manufacturing apparatus that forms an article by melting the cross-sectional shape of each layer by beam irradiation; and a manufacturing data creation apparatus that creates manufacturing data for controlling the three-dimensional additive manufacturing apparatus, wherein the manufacturing data creation apparatus includes a manufacturing data generation unit that generates a plurality of scan lines in a predetermined beam scanning method in a region of the cross-sectional shape cut out from the three-dimensional shape data of the article, and generates correction scan lines in parts where the arrangement of the scan lines is sparse and / or dense, and the three-dimensional additive manufacturing apparatus forms an article by scanning the beam along the plurality of scan lines and correction scan lines.

[0010] The present invention relates to a three-dimensional additive manufacturing method that forms an article by melting the cross-sectional shape of each layer by beam irradiation. The method involves generating multiple scan lines in a region of the cross-sectional shape extracted from the three-dimensional shape data of the article using a predetermined beam scanning method, generating correction scan lines in areas where the arrangement of the scan lines is sparse and / or dense, and forming the article by scanning the beam along the multiple scan lines and the correction scan lines. [Effects of the Invention]

[0011] According to the present invention, when generating scan lines for fabricating an article by three-dimensional additive manufacturing, it is possible to reduce variations in the density of scan lines. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic side view showing the configuration of a three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. [Figure 2] This is a block diagram showing an example of the configuration of a control system for a three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. [Figure 3] This is a flowchart showing the processing procedure of a three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. [Figure 4] This figure shows an example configuration of a three-dimensional additive manufacturing system according to the first embodiment of the present invention. [Figure 5]This is a block diagram showing an example configuration of a molding data creation apparatus according to the first embodiment of the present invention. [Figure 6] This flowchart shows an example of the processing procedure for a molding data creation apparatus according to the first embodiment of the present invention. [Figure 7] This is a diagram (part 1) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 8] This is a diagram (part 2) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 9] This is a diagram (part 3) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 10] This is Figure (4) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 11] This is Figure (5) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 12] This is Figure (6) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 13] This is Figure (7) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 14] This is Figure (8) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 15] This is Figure (9) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 16] This is a diagram (10) illustrating the processing performed by the molding data generation unit of the molding data creation device in the first embodiment of the present invention. [Figure 17]FIG. (11) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the first embodiment of the present invention. [Figure 18] FIG. (12) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the first embodiment of the present invention. [Figure 19] FIG. (13) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the first embodiment of the present invention. [Figure 20] FIG. (14) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the first embodiment of the present invention. [Figure 21] FIG. (1) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the second embodiment of the present invention. [Figure 22] FIG. (2) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the second embodiment of the present invention. [Figure 23] FIG. (3) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the second embodiment of the present invention. [Figure 24] FIG. (4) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the second embodiment of the present invention. [Figure 25] FIG. (5) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the second embodiment of the present invention. [Figure 26] FIG. (6) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the second embodiment of the present invention. [Figure 27] FIG. (7) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the second embodiment of the present invention. [Figure 28] FIG. (8) for explaining the content of the process performed by the modeling data generation unit of the modeling data creation device in the second embodiment of the present invention. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described in detail below with reference to the drawings. In this specification and the drawings, elements having substantially the same function or configuration are denoted by the same reference numerals, and redundant descriptions are omitted. Furthermore, the following description and drawings are illustrative for explaining the present invention and may be omitted or simplified for the sake of clarity. Unless otherwise specified, each component may be singular or plural. In addition, the position, size, shape, and range of each component shown in the drawings may not represent the actual position, size, shape, and range in order to facilitate understanding of the invention. For this reason, the present invention is not necessarily limited to the position, size, shape, and range disclosed in the drawings.

[0014] <First Embodiment> Figure 1 is a schematic side view showing the configuration of a three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. In the following description, in order to clarify the shape and positional relationships of each part of the three-dimensional additive manufacturing apparatus, the left-right direction in Figure 1 will be referred to as the X direction, the depth direction in Figure 1 as the Y direction, and the up-down direction in Figure 1 as the Z direction. The X, Y, and Z directions are mutually orthogonal directions. Furthermore, the X and Y directions are parallel to the horizontal direction, and the Z direction is parallel to the vertical direction.

[0015] As shown in Figure 1, the three-dimensional additive manufacturing apparatus 10 comprises a vacuum chamber 12, a beam irradiation device 14, a powder coating device 16, a build table 18, a build box 20, a recovery box 21, a build plate 22, an inner base 24, and a plate moving device 26. The three-dimensional additive manufacturing apparatus 10 creates an object (hereinafter also referred to as "manufactured object") by the powder bed fusion method described above. In this embodiment, the case in which the beam irradiated onto the surface of the powder layer is a charged particle beam, more specifically an electron beam, will be used as an example. However, the beam is not limited to a charged particle beam; for example, it may be a laser beam. When a laser beam is used, it is not necessary to create a vacuum in the chamber.

[0016] The vacuum chamber 12 is a chamber that creates a vacuum by exhausting the air inside the chamber using a vacuum pump (not shown). The vacuum chamber 12 corresponds to a build chamber that forms a space for creating a three-dimensional object 38. The build chamber forms a space for creating a three-dimensional object.

[0017] The beam irradiation device 14 is a device that irradiates the surface of the powder layer 32a, i.e., the fabrication surface 32b, with an electron beam 15. The electron beam 15 is an example of a charged particle beam. The beam irradiation device 14 includes an electron gun 141 which is the source of the electron beam 15, a focusing lens 142 which focuses the electron beam 15 generated by the electron gun 141, and a deflection device 143 which deflects the electron beam 15.

[0018] The focusing lens 142 is constructed using a focusing coil, and the magnetic field generated by the focusing coil focuses the electron beam 15. The size of the electron beam 15 on the build surface 32b can be adjusted by the focusing lens 142. The deflection device 143 is constructed using a deflection coil, and the magnetic field generated by the deflection coil deflects the electron beam 15. Scanning of the electron beam 15 on the build surface 32b is achieved by the deflection device 143.

[0019] The powder coating apparatus 16 is a device that applies metal powder 32, which is the raw material for the molded object 38, onto the molding plate 22 to form a powder layer 32a. The metal powder 32 is an example of a powder that is the raw material for the molded object 38. The powder coating apparatus 16 has a hopper 16a, a powder dispenser 16b, and a squeegee 16c. The hopper 16a is a container for storing powder. The powder dispenser 16b is a device that dispenses the powder stored in the hopper 16a onto the molding table 18. The squeegee 16c is a long, elongated member that is long in the Y direction. The squeegee 16c moves horizontally across the molding plate 22 from one end to the other of the molding table 18 to spread the metal powder 32. This forms a powder layer 32a on the molding plate 22. The squeegee 16c is provided to be movable in the X direction in order to spread the metal powder 32 over the entire surface of the molding table 18.

[0020] The build table 18 is positioned horizontally inside the vacuum chamber 12. The build table 18 is positioned below the powder coating device 16. The central part of the build table 18 is open. The shape of the opening of the build table 18 is circular or rectangular in plan view (for example, a quadrilateral in plan view).

[0021] The build box 20 is a box that supports the inner base 24 so that it can move vertically. The build box 20 forms a space for layering metal powder 32, which is applied by the powder coating device 16, onto the inner base 24. The upper end of the build box 20 is connected to the opening edge of the build table 18. The lower end of the build box 20 is connected to the bottom wall of the vacuum chamber 12.

[0022] The recovery box 21 is a box for recovering excess metal powder 32 supplied onto the build table 18 by the powder coating device 16. One recovery box 21 is provided on one side in the X direction and one on the other side.

[0023] The build plate 22 is a plate for forming an object 38 using metal powder 32. The object 38 is formed by stacking on the build plate 22. The build plate 22 is formed in a circular or rectangular shape in plan view to match the opening shape of the build table 18. The build plate 22 is connected (grounded) to the inner base 24 by an earth wire 34 to prevent it from becoming electrically floating. The inner base 24 is maintained at GND (ground) potential. Metal powder 32 is spread on top of the build plate 22 and the inner base 24.

[0024] The inner base 24 is provided to be movable in the vertical direction (Z direction). The build plate 22 moves vertically together with the inner base 24. The inner base 24 has larger external dimensions than the build plate 22. The inner base 24 slides vertically along the inner surface of the build box 20. A sealing member 36 is attached to the outer circumference of the inner base 24. The sealing member 36 is a member that maintains sliding properties and airtightness between the outer circumference of the inner base 24 and the inner surface of the build box 20. The sealing member 36 is made of a material that has heat resistance and elasticity.

[0025] The plate moving device 26 is a device that moves the build plate 22 and the inner base 24 in the vertical direction. The plate moving device 26 comprises a shaft 26a and a drive mechanism 26b. The shaft 26a is connected to the lower surface of the inner base 24. The drive mechanism 26b comprises a motor (not shown) and a power transmission mechanism, and by driving the power transmission mechanism with the motor as the drive source, the build plate 22 and the inner base 24 are moved vertically together with the shaft 26a. The power transmission mechanism is composed of, for example, a rack and pinion mechanism or a ball screw mechanism.

[0026] Figure 2 is a block diagram showing an example of the configuration of the control system of a three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. In Figure 2, the control unit 50 is composed of a computer equipped with a processor 50a such as a CPU (Central Processing Unit) and a storage unit 50b such as ROM (Read Only Memory), RAM (Random Access Memory), HDD (Hard Disk Drive), and SSD (Solid State Drive). The control unit 50 comprehensively controls the operation of the three-dimensional additive manufacturing apparatus 10 by having the processor read a program pre-written in ROM into RAM and execute it. The control unit 50 also controls the operation of the entire three-dimensional additive manufacturing apparatus 10 according to the manufacturing data described later. The beam irradiation device 14, powder coating device 16, and plate moving device 26 are connected to the control unit 50 as control targets.

[0027] The beam irradiation device 14 irradiates the electron beam 15 based on control commands provided by the control unit 50. At this time, the control unit 50 controls the electron beam 15 via the electron gun 141, focusing lens 142, and deflection device 143. For example, the control unit 50 controls the beam current of the electron beam 15 via the beam irradiation device 14. The control unit 50 also controls the spot size of the electron beam 15 via the focusing lens 142. The spot size of the electron beam 15 is the size of the electron beam 15 on the build surface 32b. Furthermore, the control unit 50 controls the deflection angle and deflection speed of the electron beam 15 via the deflection device 143. The deflection angle of the electron beam 15 is a control parameter that determines the irradiation position of the electron beam 15. The deflection speed of the electron beam 15 is a control parameter that determines the scanning speed of the electron beam 15. The scanning speed of the electron beam 15 can be rephrased as the movement speed of the electron beam 15 on the build surface 32b.

[0028] The plate moving device 26 moves the build plate 22 and inner base 24 based on control commands provided by the control unit 50. The powder coating device 16 applies metal powder 32 onto the build plate 22 based on control commands provided by the control unit 50 to form a powder layer 32a. The operation of the hopper 16a, powder dispenser 16b, and squeegee 16c of the powder coating device 16 is controlled by the control unit 50.

[0029] <Operation of a 3D additive manufacturing device> Figure 3 is a flowchart showing the processing procedure of a three-dimensional additive manufacturing apparatus according to the first embodiment of the present invention. The processing operations shown in this flowchart are performed under the control of the control unit 50.

[0030] Before the start of the printing process, the area around the build plate 22 is covered with metal powder 32, except for the top surface of the build plate 22. The top surface of the build plate 22 is positioned at approximately the same height as the top surface of the metal powder 32 spread on the build table 18.

[0031] (Plate heating process) First, the beam irradiation device 14 heats the molding plate 22 by operating based on control commands provided by the control unit 50 (step S1). In step S1, the beam irradiation device 14 irradiates the build plate 22 with an electron beam 15. This heats the build plate 22 to a temperature at which the metal powder 32 is partially sintered.

[0032] (Plate lowering process) Next, the plate moving device 26 lowers the molding plate 22 by a predetermined amount based on the control command provided by the control unit 50 (step S2). In step S2, the plate moving device 26 lowers the inner base 24 by a predetermined amount so that the upper surface of the build plate 22 is slightly lower than the upper surface of the metal powder 32 spread on the build table 18. At this time, the build plate 22 lowers by a predetermined amount together with the inner base 24. This predetermined amount (hereinafter also referred to as "ΔZ") corresponds to the thickness of one layer when the build object 38 is built by layering.

[0033] (Powder coating process) Next, the powder coating apparatus 16 operates based on control commands provided by the control unit 50 to coat the metal powder 32 onto the molding plate 22 to form a powder layer 32a (step S3). In step S3, the powder coating device 16 dispenses the metal powder 32 supplied from the hopper 16a to the powder dispenser 16b onto the build table 18 using the powder dispenser 16b, and then spreads the metal powder 32 onto the build plate 22 by moving the squeegee 16c in the X direction. At this time, the metal powder 32 is spread onto the build plate 22 to a thickness equivalent to ΔZ. This forms a powder layer 32a on the build plate 22. Any excess metal powder 32 is collected in the recovery box 21.

[0034] (Preheating process) Next, the beam irradiation device 14 preheats the powder layer 32a on the molding plate 22 by operating based on control commands provided by the control unit 50 (step S4). In this preheating step S4, the powder layer 32a is preheated in order to pre-sinter the metal powder 32. The preheating step S4 is performed before the main sintering step S5, which will be described later. Thus, the preheating step performed before the main sintering step is also called the powder heat step. In Figure 1, the symbol E1 indicates an unsintered region where unsintered metal powder 32 exists, and the symbol E2 indicates a partially sintered region where partially sintered metal powder 32 exists.

[0035] (Main sintering process) Next, the beam irradiation device 14 operates based on control commands provided by the control unit 50 to sinter the metal powder 32 by melting and solidifying it (step S5). In step S5, the metal powder 32 that has been pre-sintered as described above is melted and solidified by irradiation with the electron beam 15, thereby performing full sintering on the pre-sintered metal powder 32. In step S5, the control unit 50 designates the cross-sectional shape of each layer, which is cut out from the three-dimensional shape data of the target object 38, as the melting target area, and controls the beam irradiation device 14 according to the molding data associated with that cross-sectional shape. As a result, the melting target area of ​​the metal powder 32 on the molding plate 22, which is represented by a two-dimensional cross-sectional shape, is melted by irradiation with the electron beam 15. The metal powder 32 that has been melted by irradiation with the electron beam 15 solidifies by natural cooling after the electron beam 15 has passed through. This forms the first layer of the molded object.

[0036] (Plate lowering process) Next, the plate moving device 26 operates based on a control command provided by the control unit 50, causing the molding plate 22 to be lowered by a predetermined amount (ΔZ) (step S6). In step S6, the plate moving device 26 lowers the molding plate 22 and the inner base 24 by ΔZ.

[0037] (First preheating step) Next, the beam irradiation device 14 preheats the powder layer 32a on the molding plate 22 by operating based on control commands provided by the control unit 50 (step S7). In this first preheating step S7, the powder layer 32a, which has completed the main sintering process in the previous layer, is preheated in preparation for laying the next layer of metal powder 32. As a result, the powder layer 32a is heated to the extent that the metal powder 32 of the next layer is partially sintered. This preheating step S7 may be performed after the main sintering step S5 described above, or after the main sintering step S10 described later. Thus, the preheating step performed after the main sintering process is also called the afterheating step.

[0038] (Powder coating process) Next, the powder coating apparatus 16 operates based on control commands provided by the control unit 50 to coat the metal powder 32 onto the molding plate 22 to form a powder layer 32a (step S8). In step S8, the powder coating apparatus 16 operates in the same manner as in step S3. As a result, on the molding plate 22, the second layer of metal powder 32 is spread on top of the sintered body formed by the first layer of metal powder 32 to form a powder layer 32a.

[0039] (Second preheating step) Next, the beam irradiation device 14 preheats the metal powder 32 forming the second powder layer 32a by operating based on control commands provided by the control unit 50 (step S9). This preheating step S9 is performed before the main sintering step 10, which will be described later. Therefore, this preheating step S9 is also called the powder heat step. In step S9, the beam irradiation device 14 operates in the same manner as in step S4. This causes the metal powder 32 forming the second powder layer 32a to be pre-sintered.

[0040] (Main sintering process) Next, the beam irradiation device 14 operates based on control commands provided by the control unit 50 to sinter the metal powder 32 forming the second powder layer 32a by melting and solidifying it (step S10). In step S10, the beam irradiation device 14 operates in the same manner as in step S5. This forms the second layer of the fabricated object.

[0041] Next, the control unit 50 checks whether the fabrication of the target object 38 has been completed (step S11). If the control unit 50 determines that the fabrication of the object 38 has not been completed, it returns to step S6. As a result, the control unit 50 repeats the process from steps S6 to S10 for each layer from the third layer onward. When it determines that the fabrication of the object 38 has been completed, it terminates the series of processes at that point. The three-dimensional additive manufacturing process described above yields the desired object 38.

[0042] <Configuration of a 3D additive manufacturing system> Figure 4 shows an example of the configuration of a three-dimensional additive manufacturing system according to the first embodiment of the present invention. As shown in Figure 4, the three-dimensional additive manufacturing system 100 comprises a three-dimensional additive manufacturing apparatus 10 and a molding data creation device 30. The configuration and operation of the three-dimensional additive manufacturing apparatus 10 are as described above. The molding data creation device 30 creates molding data using three-dimensional shape data of an article generated by three-dimensional CAD or the like. The molding data created by the molding data creation device 30 is recorded, for example, on a portable recording medium, and the molding data is provided to the three-dimensional additive manufacturing apparatus 10 using this recording medium. The provided molding data is read into the control unit 50 of the three-dimensional additive manufacturing apparatus 10. The control unit 50 controls the operation of the three-dimensional additive manufacturing apparatus 10 based on the molding data read from the recording medium. As a result, the three-dimensional additive manufacturing apparatus 10 manufactures an article according to the molding data created by the molding data creation device 30.

[0043] The method for providing the molding data from the molding data creation device 30 to the three-dimensional additive manufacturing device 10 is not limited to the method using the portable recording medium described above. For example, the molding data created by the molding data creation device 30 may be provided to the three-dimensional additive manufacturing device 10 via a cable or network. Furthermore, the three-dimensional additive manufacturing device 10 may be configured to incorporate all the functions (see Figure 5) provided by the molding data creation device 30.

[0044] The molding data created by the molding data creation device 30 includes molding data for controlling the operation of the electron gun 141, the focusing lens 142, and the deflection device 143, molding data for controlling the powder coating device 16, and molding data for controlling the plate moving device 26. However, this specification will only describe the creation of molding data for controlling the operation of the beam irradiation device 14, and will omit descriptions of the creation of other molding data.

[0045] <Configuration of the modeling data creation device> Figure 5 is a block diagram showing an example configuration of a molding data creation apparatus according to the first embodiment of the present invention. As shown in Figure 5, the modeling data creation device 30 comprises an input unit 301, a cutting unit 302, a modeling data generation unit 303, and an output unit 304. Although not shown, the modeling data creation device 30 is composed of a computer equipped with a processor such as a CPU and storage units such as ROM, RAM, HDD, and SSD. The functions of the modeling data creation device 30 are realized by the processor reading a program pre-written in ROM into RAM and executing it.

[0046] The data acquisition unit 301 acquires the three-dimensional shape data necessary for creating the modeling data. This three-dimensional shape data is data that identifies the three-dimensional shape of an object generated by a 3D CAD system or the like.

[0047] The cutting unit 302 cuts out the cross-sectional shape of each layer with a predetermined thickness from the three-dimensional shape data captured by the acquisition unit 301. This cross-sectional shape is a two-dimensional cross-sectional shape that represents the shape of the region to be melted by irradiation with a beam (electron beam 15 in this embodiment) in each powder layer 32a, i.e., the melting target region. Furthermore, the cross-sectional shape cut out by the cutting unit 302 is a shape represented by one or more closed lines.

[0048] The molding data generation unit 303 generates molding data by applying predetermined molding conditions to the cross-sectional shape cut out by the cutting unit 302. This molding data corresponds to the molding data (operation sequence program) used by the control unit 50 to control the operation of the beam irradiation device 14 in the sintering process S5, S10 (Figure 3). The molding conditions include beam scanning conditions and beam irradiation conditions. The beam scanning conditions are those applied when the surface of the powder layer 32a is scanned with the electron beam 15 by the deflection device 143. The beam irradiation conditions are those applied to the electron gun 141 and focusing lens 142 when the electron beam 15 is irradiated onto the surface of the powder layer 32a. There are various beam scanning conditions and various beam irradiation conditions. Specific examples of beam scanning conditions and beam irradiation conditions are described below.

[0049] Beam scanning conditions include the beam scanning method, the distance between adjacent scan lines (scan line spacing), and the scanning speed. Beam scanning methods include raster scanning, ring-shaped vector scanning, and random scanning. Raster scanning is a method in which parallel scan lines are generated and the beam is scanned along the generated scan lines. There are two types of raster scanning: unidirectional raster scanning and alternating-directional raster scanning. Ring-shaped vector scanning is a method in which scan lines are generated at a fixed distance inward from the contour lines that form the cross-sectional shape, and the beam is scanned along the generated scan lines. There are other scanning methods in vector scanning besides ring-shaped vector scanning. Random scanning is a method in which the beam is scanned randomly across regions of the cross-sectional shape. When scanning the surface of the powder layer 32a with the electron beam 15, the center of the electron beam 15 spot moves along the scan line.

[0050] On the other hand, the beam irradiation conditions include the current of the charged particle beam controlled by the electron gun 141 and the beam size on the fabrication surface controlled by the focusing lens 142. The current of the charged particle beam corresponds to the beam current. In this embodiment, an electron beam 15 is used as the charged particle beam. Therefore, the current of the electron beam 15 corresponds to the current of the charged particle beam. Also, the size (spot size) of the electron beam 15 on the fabrication surface 32b corresponds to the beam size on the fabrication surface. When the beam irradiated onto the surface of the powder layer 32a is a laser beam, the beam irradiation conditions include the intensity of the laser beam (beam intensity) and the beam size on the fabrication surface.

[0051] Furthermore, the molding data generation unit 303 generates scan lines for scanning the surface of the powder layer 32a with the electron beam 15 in the sintering process described above. In other words, the molding data generated by the molding data generation unit 303 includes scan line data. The scan lines are lines that define the movement path (scanning path) of the electron beam 15 when melting the cross-sectional area (melting target area) of each layer by irradiation with the electron beam 15. In other words, in the cross-sectional area, the electron beam 15 moves along the scan lines.

[0052] Regarding the generation of scan lines, the molding data generation unit 303 generates multiple scan lines in a predetermined beam scanning method in the area of ​​the cross-sectional shape cut out by the cutting unit 302, and also generates correction scan lines in areas where the arrangement of scan lines is sparse and / or dense. The scanning line generation process by the molding data generation unit 303 will be explained in detail later.

[0053] The output unit 304 outputs the molding data generated by the molding data generation unit 303 to an electronic file. The molding data output to the electronic file is provided to the three-dimensional additive manufacturing apparatus 10 by the method described above (for example, the method using a portable recording medium). Furthermore, if the object to be molded is to be molded in, for example, 100 layers, molding data for 100 layers is provided to the three-dimensional additive manufacturing apparatus 10. The control unit 50 of the three-dimensional additive manufacturing apparatus 10 then sequentially controls the operation of the entire three-dimensional additive manufacturing apparatus 10 according to the molding data provided from the molding data creation device 30.

[0054] <Processing procedure for the modeling data creation device> Figure 6 is a flowchart showing an example of the processing procedure (modeling data creation method) of a modeling data creation apparatus according to the first embodiment of the present invention. First, the data acquisition unit 301 acquires three-dimensional shape data (step S31). Next, the cutting unit 302 cuts out a cross-sectional shape for one layer from the three-dimensional shape data (step S32). Each layer contains one or more cross-sectional shapes.

[0055] Next, the molding data generation unit 303 generates molding data by applying predetermined molding conditions to the cross-sectional shape cut out by the cutting unit 302 (step S33). The scanning line generation process by the molding data generation unit 303 is performed in step S33.

[0056] Next, the output unit 305 outputs the modeling data generated by the modeling data generation unit 303 in step S33 to an electronic file (step S34). Next, the molding data creation device 30 determines whether or not there is a next layer (step S35). This determination in step S35 is performed, for example, by the cutting unit 302. If there is a next layer (if YES in step S35), the process returns to step S32; if there is no next layer (if NO in step S35), the series of processes ends.

[0057] <Scan line generation process> Next, the scanning line generation process performed by the molding data generation unit 303 will be explained in detail using Figures 7 to 20. First, as shown in Figure 7, the molding data generation unit 303 generates a plurality of scan lines 41 to 47 in the region of the cross-sectional shape 40 cut out by the cutting unit 302 using a predetermined beam scanning method. In the first embodiment, the molding data generation unit 303 generates a plurality of scan lines in the region of the cross-sectional shape 40 using a ring-shaped vector scanning method. As mentioned above, the ring-shaped vector scanning method (hereinafter also simply referred to as the "vector scanning method") is a method that generates scan lines at a certain distance inward from the contour lines that form the cross-sectional shape. Therefore, the plurality of scan lines generated by the vector scanning method are concentric scan lines. The plurality of scan lines generated by the vector scanning method may include, as shown in Figure 7, scan lines 41, 42, and 43 that are generated along the contour lines of the cross-sectional shape 40 with a shape similar to the contour lines, as well as scan lines 44, 45, 46, and 47 that are generated in an island-like manner with a shape different from the contour lines of the cross-sectional shape 40. The plurality of scan lines 41 to 47 correspond to the concentric scan lines generated by the ring-shaped vector scanning method.

[0058] As described above, when multiple scan lines 41 to 47 are generated in the region of the cross-sectional shape 40 using a vector scanning method, areas P11 and P12 may occur where the arrangement of scan lines is sparser compared to other areas, and areas P13 and P14 may occur where the arrangement of scan lines is denser compared to other areas, as shown in Figure 7. The other areas mentioned above are, for example, the areas indicated by the symbol P10 in Figure 7. In Figure 7, for convenience, two areas with sparse and two areas with dense scan lines are shown, but other such areas also exist. In areas P11 and P12 where the arrangement of scan lines is sparse, the scan lines are too far apart from each other. Therefore, when the cross-sectional shape 40, which is the area to be melted in this sintering process, is beam-scanned along the scan lines, melting defects due to insufficient melting are more likely to occur in areas P11 and P12 where the arrangement of scan lines is sparse. Melting defects due to insufficient melting are defects caused by insufficient beam irradiation energy. On the other hand, in areas P13 and P14 where the arrangement of scan lines is dense, the scan lines are too close together. Therefore, when the cross-sectional shape 40, which is the area to be melted in this sintering process, is beam-scanned along the scan lines, melting defects due to excess melting are more likely to occur in areas P13 and P14 where the scan lines are densely arranged. Melting defects due to excess melting are defects caused by an excess amount of beam irradiation energy.

[0059] Therefore, the modeling data generation unit 303 performs processing to generate corrective scan lines in the areas P11 and P12 where the scan lines are sparsely arranged, and in the areas P13 and P14 where they are densely arranged. The corrective scan lines are generated to suppress the occurrence of the melting defects mentioned above. The modeling data generation unit 303 generates the corrective scan lines by the morphological graphic processing described below. In this morphological graphic processing, the interval between scan lines applied when generating multiple scan lines 41 to 47 using the ring-shaped vector scanning method described above is set to d (μm) (see Figure 7). The part indicated by the symbol P10 in Figure 7 corresponds to the part of the scan lines that are separated by this interval d. The scan line interval d is the interval (distance between scan lines) defined by the parallel parts of two adjacent scan lines (for example, scan line 41 and scan line 42). The value of the scan line interval d is specified (input) in advance by the user, for example, along with the beam size on the modeling surface.

[0060] Furthermore, in morphological figure processing, the constants a, b, and ε defined below are used. Constant a = 1 / 3 constant b = √2 The constant ε is a value that is greater than the calculation rounding error expected to occur in the computer, and less than the manufacturing dimension reproduction accuracy of the three-dimensional additive manufacturing apparatus 10. The constant ε is a value determined in the CAM software program, and its unit is μm.

[0061] Furthermore, in this embodiment, it is assumed that the cross-sectional shape 40 cut out by the cutting unit 302 is a polygon, and that this polygon is a figure that can be represented, for example, by specifying the coordinates of its vertices numerically. And, it is assumed that the polygon 1A shown in Figure 8 is the nth generation from the outermost periphery of the cross-sectional shape 40 cut out by the cutting unit 302, and that the figure is represented by the scan line determined by the modeling data generation unit 303 as the nth tree-ring-shaped scan line (excluding correction scan lines) through morphological figure processing. Specifically, polygon 1A is a figure that is generated by the following procedure. First, the modeling data generation unit 303 generates a figure that is obtained by enlarging the figure represented by the scan line 41 by a predetermined amount, as a figure represented by a fictitious scan line that is not actually output. The predetermined amount is selected to be as close as possible to the scan line interval d (see Figure 7) within the range in which self-intersection does not occur even when the figure represented by the scan line 41 is enlarged by the predetermined amount. Next, the modeling data generation unit 303 performs morphological modeling (details described later) on the figure represented by the fictitious scan lines as the first processing target, and determines the ring-shaped scan lines and corresponding correction scan lines generated by this modeling process as the first scan line and correction scan line. At this time, if a part of the correction scan line generated by the morphological modeling process extends outside the scan line 41, the modeling data generation unit 303 deletes the protruding part of the correction scan line. The polygon 1A shown in Figure 8 is the figure represented by the ring-shaped scan lines determined by the modeling data generation unit 303 as the first scan line. The polygon 1A has inwardly pointing acute vertices 48a, 48b and outwardly pointing acute vertices 49a, 49b.

[0062] First, as shown in Figure 9, the modeling data generation unit 303 generates polygon 1B (the figure shown by the dashed line in Figure 9) by reducing (shrinking) polygon 1A by a dimension of (1+a)×d. In this reduction process, the amount of movement Ls of the inward-facing acute vertices 48a and 48b is limited so that the amount of movement Ls of each acute vertex 48a and 48b is less than or equal to a×d×b. In other words, the portion of the acute vertices 48a and 48b whose movement Ls exceeds a×d×b due to the reduction process is cut off. This makes it possible to make the angle θ of the inward-facing acute vertex of polygon 1B obtuse, even if the tip of the inward-facing acute vertex 48a in polygon A1 is pointed. On the other hand, there is no need to limit the amount of movement of the outward-facing acute vertices 49a and 49b. Therefore, the outward-facing acute vertices 49a and 49b in polygon 1A may have pointed ends (shapes), as shown in polygon 1B in Figure 9.

[0063] Next, the modeling data generation unit 303 generates polygon 1C (the figure shown by the dashed line in Figure 10) by enlarging (expanding) polygon 1B by a dimension of 2 × a × d, as shown in Figure 10. In this enlargement process, the amount of movement Ls of the outward-facing acute vertices 49a and 49b mentioned above is limited so that the amount of movement Ls of the outward-facing acute vertices in polygon 1B is less than or equal to a × d × b. This makes the angle θ of the outward-facing acute vertices of polygon 1C obtuse. On the other hand, there is no need to limit the amount of movement of the inward-facing acute vertices in polygon 1B.

[0064] Next, the modeling data generation unit 303 generates polygon 1D (the shape shown by the dashed line in Figure 11) by reducing (shrinking) polygon 1C by a dimension of a × d, as shown in Figure 11. The modeling data generation unit 303 determines a single closed line representing the shape (outline) of this polygon 1D as the (n+1)th annual ring-shaped scan line.

[0065] Next, the molding data generation unit 303 generates polygon 1E (the figure shown by the dashed line in Figure 12) by reducing polygon 1A by a dimension of (1-a) × d, as shown in Figure 12.

[0066] Next, the molding data generation unit 303 generates polygon 1F (the figure shown by the dashed line in Figure 13) by scaling polygon 1D shown in Figure 11 by a dimension of a × d + ε, as shown in Figure 13.

[0067] Next, as shown in Figure 14, the molding data generation unit 303 generates (extracts) zero or more polygons 1G(i) by deleting the region of polygon 1F shown in Figure 13 from the region of polygon 1E shown in Figure 12. The subscript i in polygon 1G(i) is an integer of 1 or more and is a value that depends on the shape of the original figure (see Figure 8). As a result, if the number of polygons 1G generated by the molding data generation unit 303 is m (the maximum value of i is m), the molding data generation unit 303 generates polygons 1G(1), 1G(2), ..., 1G(m). Polygons 1G(i) are locations where melting defects (melting defects due to insufficient melting, melting defects due to excessive melting, etc.) are predicted to occur when the beam is scanned along the multiple scan lines 41 to 47 shown in Figure 7. In other words, the molding data generation unit 303 generates polygon 1G(i), thereby identifying the location of polygon 1G(i) as a location where the melting defect is expected to occur. Figure 14 shows the case where two polygons 1G(1) and 1G(2) are generated, i.e., when m=2.

[0068] Next, as shown in Figure 15, the molding data generation unit 303 generates predetermined lines 1H(i,j) in the regions of each polygon 1G(1), 1G(2), ..., 1G(m) for each polygon 1G(i). The predetermined lines 1H(i,j) are lines generated as correction scan lines. In other words, the molding data generation unit 303 generates correction scan lines at locations where melting defects are predicted to occur when the beam is scanned along the multiple scan lines 41 to 47 shown in Figure 7. The subscript i in the predetermined line 1H(i,j) is the same as the subscript i in polygon 1G(i) described above. The subscript j in the predetermined line 1H(i,j) is a natural number indicating the number of predetermined lines 1H generated in the region of one polygon 1G(i). That is, j = 1, ..., k. The maximum value k of j takes on 1 or more different values ​​depending on the shape of polygon 1G(i). Figure 15 shows the case where a predetermined line 1H(1,1) is generated in the region of polygon 1G(1) and a predetermined line 1H(2,1) is generated in the region of polygon 1G(2). Preferably, the predetermined line 1H(i,j) is a straight line, a broken line, or a branched line that forms the median of polygon 1G(i).

[0069] A predetermined line 1H(i,j) is a line that can be scanned in one direction from one end to the other. Furthermore, as shown in Figure 7 above, the multiple scan lines 41 to 47 generated by the ring-shaped vector scanning method are each represented as a single closed line, but the predetermined line 1H(i,j) is an open line. Specifically, the predetermined line 1H(i,j) is a line that is at least one of the following: a straight line, a polyline, or a branched line. If the predetermined line 1H(i,j) does not branch, the value of j is 1. If the predetermined line 1H(i,j) does branch, the value of j is 2 or greater.

[0070] Figure 16 shows the case where a predetermined line 1H(i,j) generated in the region of polygon 1G(i) is a straight line. The predetermined line 1H(i,j) is a straight line 1H(i,1) that passes from one end of polygon 1G(i) in the longitudinal direction to the other end, passing through the center of polygon 1G(i) in the short direction.

[0071] Figure 17 shows the case where a predetermined line 1H(i,j) generated in the region of polygon 1G(i) is a polyline. The predetermined line 1H(i,j) is a single polyline 1H(i,1) that passes through the center of the short side of polygon 1G(i) from one end in the longitudinal direction to the other end, and then bends along the way.

[0072] Figure 18 shows the case where a predetermined line 1H(i,j) generated in the region of polygon 1G(i) is a branched line. The predetermined line 1H(i,j) is a branched line having line 1H(i,1) which bends from one end of polygon 1G(i) toward the other end, and line 1H(i,2) which branches off from the middle of line 1H(i,1). Lines 1H(i,1) and 1H(i,2) are separated from each other at section P in Figure 18. By separating lines 1H(i,1) and 1H(i,2) at section P, it is possible to avoid excessive injection of beam irradiation energy near section P.

[0073] In this way, the modeling data generation unit 303 generates a predetermined line 1H(i,j) in the region of each polygon 1G(i). In other words, the modeling data generation unit 303 generates a predetermined line 1H(i,j) for each polygon 1G(i). The modeling data generation unit 303 then determines all the generated predetermined lines 1H(i,j) as correction scan lines corresponding to the (n+1)th tree-ring-shaped scan line.

[0074] As a result, the molding data generation unit 303 generates the (n+1)th tree-ring-shaped scan line 51 and the correction scan lines 52a and 52b corresponding to the scan line 51, as shown in Figure 19. The scan line 51 is a line representing the polygon 1D shown in Figure 11. The correction scan line 52a is a line corresponding to the predetermined line 1H(1,1) shown in Figure 15. The correction scan line 52b is a line corresponding to the predetermined line 1H(1,2) shown in Figure 15. Furthermore, the scan line 51 is a single closed line, while the correction scan lines 52a and 52b are both open lines.

[0075] The modeling data generation unit 303 performs the morphological graphic processing described using Figures 8 to 19 for each polygon represented by the scan lines 41 to 47 shown in Figure 7. The modeling data generation unit 303 also starts processing with the polygon representing the contour line of the cross-sectional shape of the modeled object, or the polygon that is expanded or contracted by a certain distance from that contour line. Then, the morphological graphic processing described above is repeated for all polygons represented by the scan lines 41 to 47. As a result, the modeling data generation unit 303 generates multiple tree-ring-like scan lines 61 to 66 and multiple correction scan lines 71, 72, 73, 74, 75, 76, 77, ... in the region of the cross-sectional shape 40 extracted from the three-dimensional shape data of the article, as shown in Figure 20.

[0076] Here, the correspondence between the multiple scan lines 41-47 shown in Figure 7 and the multiple scan lines 61-66 and correction scan lines shown in Figure 20 is as follows: Scan line 41 corresponds to scan line 61, correction scan line 76, and correction scan line 78; scan line 42 corresponds to scan line 62, correction scan line 77, and correction scan line 79; scan line 43 corresponds to scan line 63, correction scan line 72, and correction scan line 80. Also, scan line 44 corresponds to scan line 64 and correction scan line 71; scan line 45 corresponds to scan line 65, correction scan line 81, and correction scan line 82; and scan line 46 corresponds to scan line 66, correction scan line 74, and correction scan line 83.

[0077] Furthermore, as can be seen from Figures 7 and 20, correction scan lines 71 are added to areas P11 where the scan lines are sparsely arranged, and correction scan lines 77 are added to areas P12 where the scan lines are sparsely arranged. In contrast, in areas P13 where the scan lines are densely arranged, scan lines 47 are replaced with correction scan lines 75, and in areas P14 where the scan lines are densely arranged, a part of scan line 41 (the pointed part) is replaced with correction scan line 76. In other words, the molding data generation unit 303 adds correction scan lines to areas where the scan lines are sparsely arranged, and replaces scan lines with correction scan lines in areas where the scan lines are densely arranged. This also applies to areas in Figures 7 and 20 that are not labeled (areas where the lines are sparse and areas where they are dense).

[0078] This suppresses scanning lines that are too far apart or too close together, which can cause melting defects, when the printing data generation unit 303 of the printing data creation device 30 generates printing data, thereby reducing variations in the density of the scanning lines. Furthermore, in this sintering process, the control unit 50 controls the beam irradiation device 14 according to the printing data previously generated by the printing data generation unit 303, so that the electron beam 15 is scanned along the plurality of scanning lines 61 to 66 and the plurality of correction scanning lines 71, 72, 73, 74, 75, 76, 77, ... and the article is formed. Therefore, in the three-dimensional additive manufacturing device 10, when an article is formed by melting the cross-sectional shape of each layer by irradiation (scanning) with the electron beam 15, the occurrence of melting defects due to insufficient or excessive melting can be suppressed.

[0079] Furthermore, the order in which the beam irradiation device 14 of the three-dimensional additive manufacturing device 10 scans the multiple scan lines (61-66) and multiple correction scan lines (71, 72, 73, 74, 75, 76, 77, ...) generated by the molding data generation unit 303 of the molding data creation device 30 with the electron beam 15 can be arbitrarily set.

[0080] For example, for multiple scan lines (61-66), the beam may be scanned starting with the outer scan lines, or starting with the inner scan lines. Alternatively, adjacent scan lines (61-66) may be scanned sequentially, or beam scanning may be repeated while skipping a few scan lines at a time. Furthermore, multiple scan lines (61-66) may be beam scanned in a completely random order. Regardless of the order in which the multiple scan lines (61-66) are beam scanned, all scan lines (61-66) must be beam scanned.

[0081] Furthermore, for multiple correction scan lines (71, 72, 73, 74, 75, 76, 77, ...), the correction scan line associated with each ring-shaped scan line may be beam-scanned each time that ring-shaped scan line is beam-scanned. Alternatively, the multiple correction scan lines (71, 72, 73, 74, 75, 76, 77, ...) may be beam-scanned before or after beam-scanning the multiple ring-shaped scan lines (61-66).

[0082] Furthermore, when beam scanning multiple scan lines (61-66) and when beam scanning multiple correction scan lines (71, 72, 73, 74, 75, 76, 77, ...), the same build conditions may be applied, or different build conditions may be applied. When applying different build conditions, at least one of the following must be different: scanning speed, beam size on the build surface, beam current, and beam intensity.

[0083] <Second Embodiment> Next, a second embodiment of the present invention will be described. The configuration and operation of the three-dimensional additive manufacturing apparatus 10 and the configuration of the three-dimensional additive manufacturing system 100 according to the second embodiment of the present invention are the same as in the first embodiment described above. However, in the second embodiment of the present invention, the content of the scan line generation process (morphological graphic processing) performed by the molding data generation unit 303 of the molding data creation apparatus 30 is different.

[0084] <Scan line generation process> First, the molding data generation unit 303 generates multiple scan lines in the region of the cross-sectional shape cut out by the cutting unit 302 using a predetermined beam scanning method. In the first embodiment described above, a tree-ring-shaped vector scanning method was adopted as the predetermined beam scanning method, but in the second embodiment, a raster scanning method is adopted. Figure 21 shows an example of a cross-sectional shape to be melted by raster scanning. The figure representing the cross-sectional shape shown in Figure 21 is called polygon 2A.

[0085] As shown in Figure 22, the modeling data generation unit 303 generates multiple scan lines 2B(j) in the area of ​​the cross-sectional shape (polygon 2A) shown in Figure 21 using a raster scanning method. The subscript j in scan line 2B(j) is a natural number. If the number of scan lines generated by the modeling data generation unit 303 in the area of ​​the cross-sectional shape is n, then j = 1, 2, 3, ..., n. The multiple scan lines 2B(j) are parallel to each other, i.e., parallel linear scan lines (hereinafter also referred to as "raster scan lines"). The modeling data generation unit 303 also generates the multiple scan lines 2B(j) at a predetermined interval p (μm). The interval p corresponds to the distance between adjacent scan lines in the direction perpendicular to the scan line 2B(j) (up and down direction in Figure 22). The value of the scan line interval p is specified (input) in advance by the user, for example, along with the beam size on the modeling surface. One possible method for generating multiple scan lines 2B(j) is to generate them as the logical AND portion of a raster scan line that completely covers polygon 2A and the region of polygon 2A.

[0086] Here, as shown in Figure 22 above, when multiple scan lines 2B(j) are generated using a raster scanning method in the region of the cross-sectional shape represented by polygon 2A, there are areas where the arrangement of scan lines becomes sparser compared to other areas. Specifically, in the contour portions P21, P22, P23, and P24 of the contour of the cross-sectional shape represented by polygon 2A that are inclined with respect to the scan lines 2B(j), the arrangement of scan lines 2B(j) becomes sparser compared to other areas (for example, the area indicated by P20). The reason why the arrangement of scan lines 2B(j) becomes sparser in the inclined contour portions P21, P22, P23, and P24 is that the ends of each scan line 2B(j) are shifted in the left-right direction in Figure 22 due to the inclination of the contour of the cross-sectional shape (polygon 2A), and as a result, the distance between the ends of scan lines 2B(j) becomes longer than in other areas. The other areas mentioned above are, for example, the areas indicated by the symbol P20 in Figure 22. The portion indicated by the symbol P20 is perpendicular to the scan line 2B(j). In the portion indicated by the symbol P20, the ends of each scan line 2B(j) are located almost on the same line without shifting in the left-right direction of Figure 22.

[0087] When the cross-sectional shape (polygon 2A) of the melting region in this sintering process is beam-scanned along multiple scan lines 2B(j), step-like irregularities, such as those shown in Figure 24, are formed in the aforementioned contour portions P21, P22, P23, and P24. If such irregularities appear on the surface of the fabricated object, it is necessary to perform post-processing on the object obtained by additive manufacturing to remove the irregularities. In particular, if the fabricated object is made of a difficult-to-machine material, the time required for post-processing will be longer, which will worsen production efficiency.

[0088] Therefore, the molding data generation unit 303 performs processing to generate corrective scan lines in contour areas P21, P22, P23, and P24 where the scan lines are sparsely arranged. The corrective scan lines are generated to reduce surface irregularities and suppress the occurrence of melting defects. The molding data generation unit 303 generates the corrective scan lines by the morphological graphic processing described below.

[0089] First, the molding data generation unit 303 estimates (assumes) the range in which melting and solidification will occur when the beam is scanned along each of the multiple scan lines 2B(j) generated as described above, by calculation, simulation, etc. Here, as an example, as shown in Figure 23, the range in which melting and solidification will occur when the beam is scanned along the scan line 2B(1) (hereinafter also referred to as the "melting range") is defined as the range of a rectangle 2C(1), which is a polygon with appropriate widths in the direction of travel of the scan line 2B(1) and in the direction perpendicular to it. In this sintering process, the spot of the electron beam 15 moves along the scan line 2B(1). For this reason, the molding data generation unit 303 assumes that the range of melting and solidification will be the rectangle 2C(1) centered on the scan line 2B(1). Furthermore, the molding data generation unit 303 assumes that the length L of the rectangle 2C(1) is longer than the length of the scan line 2B(1). Furthermore, the molding data generation unit 303 assumes the width W of the rectangle 2C(1) centered on the position of the scan line 2B(1). In Figure 23, as an example, an example is shown in which the length L of the rectangle 2C(1) is assumed to be 0.5 times the scan line spacing p (see Figure 22) at one end and 0.5p longer at the other end compared to the length of the scan line 2B(1). Also in Figure 23, as an example, an example is shown in which the width W of the rectangle 2C(1) is assumed to be 1.2 times the scan line spacing p, i.e., 1.2p.

[0090] Thus, the molding data generation unit 303 assumes the melting range using a constant multiple of the scan line spacing p. It is preferable to define the melting range separately in the longitudinal direction of the scan line 2B(1) and in the direction perpendicular to that longitudinal direction. This is because, when scanning the electron beam 15 along the raster scan line, the amount of energy injected by the electron beam 15 differs between the ends of the raster scan line in the longitudinal direction and other parts. Specifically, the cumulative irradiation time of the electron beam 15 is shorter at the ends of the raster scan line in the longitudinal direction compared to other parts, and therefore the amount of energy injected is less. For this reason, in order to assume the melting range more accurately, it is reasonable to make the constant applied to the calculation of the length L of the rectangle 2C(1) smaller than the constant applied to the calculation of the width W of the rectangle 2C(1).

[0091] The molding data generation unit 303 also determines rectangles 2C(2), 2C(3), ..., 2C(n) representing the expected melting range for the other scan lines 2B(2), 2B(3), ..., 2B(n), in the same way as for scan line 2B(1) described above. Furthermore, the molding data generation unit 303 combines (fused) all the rectangles 2C(1), 2C(2), 2C(3), ..., 2C(n) representing the expected melting range to generate polygon 2C (the figure shown by the dashed line in Figure 24), as shown in Figure 24.

[0092] Next, as shown in Figure 25, the molding data generation unit 303 generates (extracts) zero or more polygons 2D(i) from the area remaining after removing the area of ​​polygon 2C from the area of ​​polygon 2A. The subscript i in polygon 2D(i) is an integer of 1 or more. Thus, if the number of polygons 2D generated by the molding data generation unit 303 is m (the maximum value of i is m), the molding data generation unit 303 generates polygons 2D(1), 2D(2), ..., 2D(m). In other words, the value of m indicates the number of polygons 2D(i) generated by the molding data generation unit 303. Polygons 2D(1), 2D(2), ..., 2D(m) are locations where melting defects (such as melting defects due to insufficient melting) or recesses are expected to occur when the beam is scanned along the scan line 2B(j) shown in Figure 22. In other words, the molding data generation unit 303 generates polygons 2D(i), thereby identifying the locations of these polygons 2D(i) as areas where melting defects or recesses are expected to occur. In this case, the areas where each polygon 2D(1), 2D(2), ..., 2D(m) exists correspond to the areas in the diagonal contour sections P21, P22, P23, P24 shown in Figure 22 where the scan lines 2B(j) are sparsely arranged. In Figure 25, only some of the polygons 2D(i) generated by the molding data generation unit 303 are labeled. Figure 26 is an enlarged view of section R in Figure 25. If the molding data generation unit 303 does not generate any polygons 2D(i), the molding data generation unit 303 does not generate any correction scan lines.

[0093] In contrast, if the molding data generation unit 303 generates one or more polygons 2D(i), the molding data generation unit 303 generates a predetermined line 2E(i) in the region of each polygon 2D(i), as shown in Figure 27. The predetermined line 2E(i) is a line generated as a correction scan line. In other words, the molding data generation unit 303 generates a correction scan line at locations where melting defects (such as melting defects due to insufficient melting) or depressions are expected to occur when scanning the beam along the scan line 2B(j) shown in Figure 22. The subscript i in the predetermined line 2E(i) is the same as the subscript i in the polygon 2D(i) described above. That is, the minimum value of i is 0 and the maximum value of i is m. In this case, the value of m indicates the number of correction scan lines generated by the molding data generation unit 303. The predetermined line 2E(i) is a line that can be scanned in one direction from one end to the other. Furthermore, the specified line 2E(i) is an unclosed line.

[0094] Figure 27 shows an example where the modeling data generation unit 303 generates a predetermined line 2E(1) in the region of polygon 2D(1). The predetermined line 2E(1) is a single broken line that passes through the center of the short side of polygon 2D(1) from one end in the longitudinal direction to the other end, and then bends midway. However, the predetermined line 2E(1) may also be a single straight line that passes through the center of the short side of polygon 2D(1) from one end in the longitudinal direction to the other end. The modeling data generation unit 303 generates predetermined lines 2E(2), 2E(3), ..., 2E(m) for the other polygons 2D(2), 2D(3), ..., 2D(m) in the same way as for polygon 2D(1). The molding data generation unit 303 then determines all the generated predetermined lines 2E(i) as correction scan lines corresponding to the cross-sectional shape of the polygon 2A.

[0095] As a result, the molding data generation unit 303 generates multiple scan lines 2B(j) and multiple correction scan lines 2E(i), as shown in Figure 28. The multiple scan lines 2B(j) are parallel scan lines generated by the raster scanning method, as shown in Figure 22. The correction scan lines 2E(i) are generated between adjacent scan lines 2B(j) in a direction perpendicular to the scan lines 2B(j) (the vertical direction in Figure 28), as can be seen from Figure 28. Specifically, taking the correction scan line 2E(1) as an example, this correction scan line 2E(1) is generated between adjacent scan lines 2B(12) and scan line 2B(13) in the vertical direction in Figure 28.

[0096] This suppresses excessive spacing of scan lines, which can cause melting defects and depressions, when the molding data generation unit 303 of the molding data creation device 30 generates molding data, thereby reducing variations in the density of scan lines. Furthermore, in this sintering process, the control unit 50 controls the beam irradiation device 14 according to the molding data previously generated by the molding data generation unit 303, so that the electron beam 15 is scanned along the plurality of scan lines 2B(j) and the plurality of correction scan lines 2E(i), and the article is formed. Therefore, in the three-dimensional additive manufacturing device 10, when an article is formed by melting the cross-sectional shape of each layer by irradiation (scanning) with the electron beam 15, the occurrence of melting defects and depressions due to insufficient melting can be suppressed. As a result, the occurrence of irregularities in the contour portions P21, P22, P23, and P24 (see Figure 22) can be suppressed.

[0097] Furthermore, the order in which the beam irradiation device 14 of the three-dimensional additive manufacturing device 10 scans the multiple scan lines 2B(j) and multiple correction scan lines 2E(i) generated by the molding data generation unit 303 of the molding data creation device 30 with the electron beam 15 can be arbitrarily set.

[0098] For example, for multiple scan lines 2B(j), the beam scan may start with the upper scan line 2B(1) in Figure 28, or it may start with the lower scan line 2B(n) in Figure 28. Alternatively, adjacent scan lines in the vertical direction of Figure 28 may be scanned sequentially, or beam scanning may be repeated while skipping several scan lines. Furthermore, multiple scan lines 2B(j) may be beam scanned in a completely random order. Regardless of the order in which the multiple scan lines 2B(j) are scanned, it is necessary to beam scan all of the multiple scan lines 2B(j).

[0099] Furthermore, for multiple correction scan lines 2E(i), for example, each time a scan line is beam-scanned, the correction scan line located between that scan line and the adjacent scan line may be beam-scanned. To give a specific example, in Figure 28, after beam-scanning scan line 2B(12), correction scan line 2E(1) is beam-scanned, then scan line 2B(13), and then correction scan line 2E(2) is beam-scanned. Alternatively, multiple correction scan lines 2E(i) may be beam-scanned before or after beam-scanning multiple scan lines 2B(j).

[0100] Furthermore, when scanning multiple scan lines 2B(j) and when scanning multiple correction scan lines 2E(i), the same or different build conditions may be applied. When applying different build conditions, at least one of the following must be different: scanning speed, beam size on the build surface, beam current, and beam intensity.

[0101] Incidentally, one technique for suppressing the occurrence of irregularities in the contour portions P21, P22, P23, and P24 (see Figure 22) is to generate contour scanning lines along the contour lines of the cross-sectional shape of the fabricated object, and then perform beam scanning (vector scanning) along these contour scanning lines. Contour scanning lines are lines that represent a figure similar in shape to the cross-sectional shape of the fabricated object. In this technique, contour scanning lines are generated only in the surface area of ​​the fabricated object, within the area of ​​the cross-sectional shape of the fabricated object. Then, in the area inside the surface area of ​​the fabricated object, multiple scanning lines are generated using a raster scanning method. As a result, in this sintering process, beam scanning (vector scanning) along the contour scanning lines and beam scanning (raster scanning) along multiple scanning lines are performed. Therefore, it is possible to suppress the occurrence of irregularities on the surface of the fabricated object, including the contour portions P21, P22, P23, and P24 (see Figure 22). Furthermore, when applying the raster scanning method to an area inside the surface area of ​​the fabricated object, there is the advantage that a wide area can be melted uniformly and at high speed when the cross-sectional shape of the fabricated object is melted by beam scanning.

[0102] However, even when contour scan lines are generated on the surface area of ​​the fabricated object as described above, and multiple scan lines are generated in the area inside the surface area of ​​the fabricated object using the raster scanning method, if polygon 2A is considered as the area to which the raster scanning method is applied, melting defects may occur due to insufficient or excessive melting in the contour portions P21, P22, P23, and P24 (see Figure 22). In such cases, the fabrication data generation unit 303 generates multiple scan lines 2B(j) and multiple correction scan lines 2E(i), as shown in Figure 28, thereby eliminating insufficient or excessive melting and suppressing the occurrence of melting defects.

[0103] <Examples of variations, etc.> The technical scope of the present invention is not limited to the embodiments described above, but also includes various modified and improved forms to the extent that specific effects can be obtained by the constituent elements of the invention or combinations thereof.

[0104] For example, when the molding data generation unit 303 generates multiple scan lines using a predetermined beam scanning method, if there are areas where the scan lines are sparsely arranged and areas where they are densely arranged, it may generate correction scan lines only in the sparse areas or only in the dense areas. However, it is preferable for the molding data generation unit 303 to generate correction scan lines in both the areas where the scan lines are sparsely arranged and the areas where they are densely arranged. [Explanation of Symbols]

[0105] 10…Three-dimensional additive manufacturing equipment 15… Electron beam (charged particle beam) 30…Modeling data creation device 38...Sculpted object (article) 303...Modeling data generation unit 40…Cross-sectional shape 41-47... scan lines 61-66... ​​scan lines 71-77... Correction scan lines 2A…Polygon (cross-sectional shape) 2B(j)...Scan line 2E(i)...Correction scan line P21, P22, P23, P24... Outline section

Claims

1. A three-dimensional additive manufacturing device that creates an object by melting the cross-sectional shape of each layer by beam irradiation. A device for creating modeling data for control purposes, The molding data generation unit generates concentric scan lines using a tree-ring-like vector scanning method in the region of the cross-sectional shape extracted from the three-dimensional shape data of the article, adds a single unclosed correction scan line in areas where the arrangement of the concentric scan lines is sparse, and replaces the concentric scan lines with a single unclosed correction scan line in areas where the arrangement of the concentric scan lines is dense. Modeling data creation device.

2. A three-dimensional additive manufacturing apparatus that creates an object by melting the cross-sectional shape of each layer by beam irradiation, A three-dimensional additive manufacturing system comprising: a manufacturing data creation device for creating manufacturing data for controlling the three-dimensional additive manufacturing device; The aforementioned modeling data creation apparatus includes a modeling data generation unit that generates concentric scan lines in the region of the cross-sectional shape cut out from the three-dimensional shape data of the article using a tree-ring-like vector scanning method, adds a single unclosed correction scan line in areas where the arrangement of the concentric scan lines is sparse, and replaces the concentric scan lines with a single unclosed correction scan line in areas where the arrangement of the concentric scan lines is dense. The three-dimensional additive manufacturing apparatus fabricates the article by scanning the beam along the plurality of scan lines and the correction scan line. Three-dimensional additive manufacturing system.

3. A three-dimensional additive manufacturing method in which an object is formed by melting the cross-sectional shape of each layer by beam irradiation, The process involves generating concentric scan lines in a ring-shaped vector scanning method within the cross-sectional area extracted from the three-dimensional shape data of the article, adding a single open correction scan line where the arrangement of the concentric scan lines is sparse, replacing the concentric scan lines with a single open correction scan line where the arrangement of the concentric scan lines is dense, and then scanning the beam along the concentric scan lines and the correction scan line to fabricate the article. Three-dimensional additive manufacturing method.

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