Build Data Generating Device, Three-Dimensional Powder Bed Fusion Additive Manufacturing System, and Three-Dimensional Powder Bed Fusion Additive Manufacturing Method

Provided is a technique capable of reducing variation in density of scanning lines when generating the scanning lines for manufacturing an article by three-dimensional powder bed fusion additive manufacturing. A build data generating device generates build data for controlling the three-dimensional powder bed fusion additive manufacturing apparatus that melts the cross-sectional shape of each layer by irradiation of a beam to manufacture the article. The build data generating device includes a build data generating unit that generates a plurality of scanning lines in a region of the cross-sectional shape cut out from three-dimensional shape data of the article by a predetermined beam scanning method, and generates correction scanning lines in a portion where the arrangement of the scanning lines becomes sparse and/or a portion where the arrangement of the scanning lines becomes dense.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2023-137393 filed Aug. 25, 2023, the disclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a build data generating device, a three-dimensional powder bed fusion additive manufacturing (PBF-AM) system, and a three-dimensional PBF-AM method.

Description of Related Art

As one of additive manufacturing methods for manufacturing an article, a powder bed fusion method is known. The powder bed fusion method is a shaping method in which a surface (hereinafter, also referred to as a “manufactured surface”) of a powder layer formed by spreading powder with a predetermined thickness is selectively irradiated with a beam to melt and solidify a portion having a cross-sectional shape of an article to be manufactured. In the powder bed fusion method, a build plate is sequentially lowered each time the powder of each layer is melted and solidified, and the powder layers are stacked one by one to manufacture an article (component or the like). A three-dimensional PBF-AM apparatus employing a powder bed fusion method is disclosed in, for example, JP 2019-7065 A.

The operation of the three-dimensional PBF-AM apparatus is controlled according to an operation sequence program (hereinafter, also referred to as “build data”) prepared in advance based on three-dimensional shape data. The three-dimensional shape data is data for specifying a three-dimensional shape of an article generated by three-dimensional CAD (Computer-Aided Design) or the like. The build data is generated by a computer device (hereinafter, referred to as a “build data generating device”) in which a program generally called CAM (Computer Aided Manufacturing) software is incorporated using three-dimensional shape data of an article to be manufactured. The CAM software is executable on any computer.

As the processing of the CAM software in the build data generating device, first, the cross-sectional shape of each layer is cut out at an interval of a thickness corresponding to one layer from the input three-dimensional shape data. Next, build data for melting the cross-sectional shape of each layer is determined. The build data includes data of a scanning line for melting a portion having a cross-sectional shape of each layer by beam scanning.

SUMMARY OF THE INVENTION

However, in the build data generating device in the related art, when the plurality of scanning lines is generated in the region of the cross-sectional shape of each layer by a predetermined beam scanning method, a portion where the scanning lines are too far apart or a portion where the scanning lines are too close may occur. Therefore, when the three-dimensional PBF-AM apparatus is operated based on the build data generated by the build data generating device, a melting defect due to insufficient melting is likely to occur at the portion where the scanning lines are too far apart, and a melting defect due to excessive melting is likely to occur at the portion where the scanning lines are too close.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a technique capable of reducing variation in density of scanning lines when generating the scanning lines for manufacturing an article by three-dimensional powder bed fusion additive manufacturing.

A build data generating device according to the present invention is a build data generating device generating build data for controlling a three-dimensional PBF-AM apparatus that manufactures an article by melting a cross-sectional shape of each layer by irradiation of a beam, and includes a build data generating unit that generates a plurality of scanning lines in a region of a cross-sectional shape cut out from three-dimensional shape data of the article by a predetermined beam scanning method, and generates correction scanning lines in a portion where arrangement of the scanning lines becomes sparse and/or a portion where arrangement of the scanning lines becomes dense.

A three-dimensional PBF-AM system according to the present invention is a three-dimensional PBF-AM system including: a three-dimensional PBF-AM apparatus that manufactures an article by melting a cross-sectional shape of each layer by irradiation of a beam; and a build data generating device that generates build data for controlling the three-dimensional PBF-AM apparatus, in which the build data generating device includes a build data generating unit that generates a plurality of scanning lines in a region of a cross-sectional shape cut out from three-dimensional shape data of the article by a predetermined beam scanning method, and generates a correction scanning line in a portion where arrangement of the scanning lines becomes sparse and/or a portion where arrangement of the scanning lines becomes dense, and the three-dimensional PBF-AM apparatus manufactures the article by performing scanning with the beam along the plurality of scanning lines and the correction scanning lines.

A three-dimensional PBF-AM method according to the present invention is a three-dimensional PBF-AM method for melting a cross-sectional shape of each layer by irradiation of a beam to manufacture an article, the method including: generating a plurality of scanning lines in a region of a cross-sectional shape cut out from three-dimensional shape data of the article by a predetermined beam scanning method; generating correction scanning lines in a portion where arrangement of the scanning lines becomes sparse and/or a portion where arrangement of the scanning lines becomes dense; and manufacturing the article by performing scanning with the beam along the plurality of scanning lines and the correction scanning lines.

According to the present invention, it is possible to reduce variation in density of scanning lines when generating the scanning lines for manufacturing an article by three-dimensional powder bed fusion additive manufacturing.

DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present specification and the drawings, elements having substantially the same function or configuration are denoted by the same reference numerals, and redundant description is omitted. Further, the following description and drawings are examples for describing the present invention, and may be omitted and simplified for convenience of description. Each component may be singular or plural unless otherwise specified. In addition, the position, size, shape, range, and the like of each component illustrated in the drawings may not represent the actual position, size, shape, range, and the like in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, and the like disclosed in the drawings.

First Embodiment

FIG.1is a side view schematically illustrating a configuration of a three-dimensional PBF-AM apparatus according to a first embodiment of the present invention; In the following description, in order to clarify the shape, positional relationship, and the like of each part of the three-dimensional PBF-AM apparatus, the left-right direction inFIG.1is referred to as an X direction, the depth direction inFIG.1is referred to as a Y direction, and the vertical direction inFIG.1is referred to as a Z direction. The X direction, the Y direction, and the Z direction are directions orthogonal to each other. Further, the X direction and the Y direction are parallel to the horizontal direction, and the Z direction is parallel to the perpendicular direction.

As illustrated inFIG.1, a three-dimensional PBF-AM apparatus10includes a vacuum chamber12, a beam irradiation device14, a powder applying device16, a build table18, a build box20, a collection box21, a build plate22, an inner base24, and a plate moving device26. The three-dimensional PBF-AM apparatus10manufactures an article (hereinafter, also referred to as a “manufactured object”) by the above-described powder bed fusion method. In the present embodiment, a case where the beam with which the surface of a powder layer is irradiated is a charged particle beam, more specifically, an electron beam will be described as an example. However, the beam is not limited to the charged particle beam, and may be, for example, a laser beam. When a laser beam is employed, it is not necessary to vacuum the chamber.

The vacuum chamber12is a chamber for creating a vacuum state by evacuating the air in the chamber by a vacuum pump (not illustrated). The vacuum chamber12corresponds to a build chamber that forms a space for manufacturing a three-dimensional manufactured object38. The build chamber forms a space for manufacturing a three-dimensional manufactured object.

The beam irradiation device14is a device that irradiates the surface of a powder layer32a, that is, a manufactured surface32bwith an electron beam15. The electron beam15is an example of the charged particle beam. The beam irradiation device14includes an electron gun141that is a generation source of the electron beam15, a converging lens142that converges the electron beam15generated by the electron gun141, and a deflection device143that deflects the electron beam15.

The converging lens142is configured using a converging coil, and converges the electron beam15by a magnetic field generated by the converging coil. The size of the electron beam15in the manufactured surface32bcan be adjusted by the converging lens142. The deflection device143is configured using a deflection coil, and deflects the electron beam15by a magnetic field generated by the deflection coil. The scanning of the electron beam15on the manufactured surface32bis achieved by the deflection device143.

The powder application device16is a device that applies a metal powder32, which is a raw material of the manufactured object38, onto the build plate22to form the powder layer32a. The metal powder32is an example of a powder to be the raw material of the manufactured object38. The powder application device16includes a hopper16a, a powder dropping device16b, and a squeegee16c. The hopper16ais a chamber for storing powder. The powder dropping device16bis a device that drops the powder stored in the hopper16aonto the build table18. The squeegee16cis an elongated member elongated in the Y direction. The squeegee16chorizontally moves on the build plate22from one end side toward the other end side of the build table18to spread the metal powder32. Thus, the powder layer32ais formed on the build plate22. The squeegee16cis provided to be movable in the X direction in order to spread the metal powder32over the entire surface of the build table18.

The build table18is horizontally arranged inside the vacuum chamber12. The build table18is disposed below the powder application device16. A central portion of the build table18is opened. The opening shape of the build table18is a circle in plan view or a square in plan view (for example, a quadrangle in plan view).

The build box20is a box that supports the inner base24so as to be movable in the vertical direction. The build box20forms a space for stacking the metal powder32applied by the powder application device16on the inner base24. An upper end portion of the build box20is connected to an opening edge of the build table18. A lower end portion of the build box20is connected to a bottom wall of the vacuum chamber12.

The collection box21is a box that recovers the metal powder32supplied more than necessary among the metal powders32supplied onto the build table18by the powder application device16. One collection box21is provided on each of one side and the other side in the X direction.

The build plate22is a plate for forming the manufactured object38using the metal powder32. The manufactured object38is layered and formed on the build plate22. The build plate22is formed in a circular shape in plan view or a square shape in plan view in accordance with the opening shape of the build table18. The build plate22is connected (grounded) to the inner base24by a ground wire34so as not to be in an electrically floating state. The inner base24is held at a ground (GND) potential. The metal powder32is spread over the build plate22and the inner base24.

The inner base24is provided to be movable in the vertical direction (Z direction). The build plate22moves in the vertical direction integrally with the inner base24. The inner base24has a larger outer dimension than the build plate22. The inner base24slides in the vertical direction along the inner surface of the build box20. A seal member36is attached to an outer peripheral portion of the inner base24. The seal member36is a member that maintains slidability and sealability between the outer peripheral portion of the inner base24and the inner surface of the build box20. The seal member36is made of a material having heat resistance and elasticity.

The plate moving device26is a device that moves the build plate22and the inner base24in the vertical direction. The plate moving device26includes a shaft26aand a drive mechanism unit26b. The shaft26ais connected to the lower surface of the inner base24. The drive mechanism unit26bincludes a motor and a power transmission mechanism (not illustrated), and drives the power transmission mechanism using the motor as a drive source to move the build plate22and the inner base24integrally with the shaft26ain the vertical direction. The power transmission mechanism includes, for example, a rack and pinion mechanism, a ball screw mechanism, and the like.

FIG.2is a block diagram illustrating a configuration example of a control system of the three-dimensional PBF-AM apparatus according to the first embodiment of the present invention;

InFIG.2, the control unit50is configured by a computer including a processor50asuch as a central processing unit (CPU) and a storage unit50bsuch as a read only memory (ROM), a random access memory (RAN), a hard disk drive (HDD), and a solid state drive (SSD). Then, the control unit50comprehensively controls the operation of the three-dimensional PBF-AM apparatus10by the processor reading a program written in the ROM in advance into the RAM and executing the program. Furthermore, the control unit50controls the operation of the entire three-dimensional PBF-AM apparatus10according to build data to be described later. The beam irradiation device14, the powder application device16, and the plate moving device26are connected to the control unit50as control targets.

The beam irradiation device14emits the electron beam15based on a control command given from the control unit50. When the electron beam15is emitted, the control unit50controls the electron beam15via the electron gun141, the converging lens142, and the deflection device143. For example, the control unit50controls the beam current amount of the electron beam15via the beam irradiation device14. In addition, the control unit50controls the spot size of the electron beam15via the converging lens142. The spot size of the electron beam15is the size of the electron beam15on the manufactured surface32b. In addition, the control unit50controls the deflection angle and the deflection speed of the electron beam15via the deflection device143. The deflection angle of the electron beam15is a control parameter that determines the irradiation position of the electron beam15. The deflection speed of the electron beam15is a control parameter that determines the scanning speed of the electron beam15. The scanning speed of the electron beam15can be rephrased as a moving speed of the electron beam15on the manufactured surface32b.

The plate moving device26moves the build plate22and the inner base24based on a control command given from the control unit50. The powder application device16applies the metal powder32onto the build plate22based on a control command given from the control unit50to form the powder layer32a. The operations of the hopper16a, the powder dropping device16b, and the squeegee16cincluded in the powder application device16are controlled by the control unit50.

FIG.3is a flowchart illustrating a procedure of a processing operation of the three-dimensional PBF-AM apparatus according to the first embodiment of the present invention; The processing operation illustrated in this flowchart is performed under the control of the control unit50.

In the state before starting the manufacturing, the periphery of the build plate22is covered with the metal powder32except for the upper surface of the build plate22. Furthermore, the upper surface of the build plate22is arranged at substantially the same height as the upper surface of the metal powder32laid on the build table18.

First, the beam irradiation device14heats the build plate22by operating based on a control command given from the control unit50(step S1).

In step S1, the beam irradiation device14irradiates the build plate22with the electron beam15. Thus, the build plate22is heated to a temperature at which the metal powder32is pre-sintered.

Next, the plate moving device26lowers the build plate22by a predetermined amount by operating based on a control command given from the control unit50(step S2).

In step S2, the plate moving device26lowers the inner base24by a predetermined amount so that the upper surface of the build plate22is slightly lower than the upper surface of the metal powder32laid on the build table18. At this time, the build plate22is lowered by the predetermined amount together with the inner base24. The predetermined amount (hereinafter, also referred to as “AZ”) corresponds to a thickness of one layer when the manufactured object38is manufactured by layering.

Next, the powder application device16operates based on a control command given from the control unit50to apply the metal powder32onto the build plate22to form the powder layer32a(step S3).

In step S3, the powder application device16drops the metal powder32supplied from the hopper16ato the powder dropping device16bonto the build table18by the powder dropping device16b, and then moves the squeegee16cin the X direction to spread the metal powder32on the build plate22. At this time, the metal powder32is spread on the build plate22with a thickness corresponding to AZ. Thus, the powder layer32ais formed on the build plate22. Further, the excess metal powder32is collected in the collection box21.

Next, the beam irradiation device14operates based on a control command given from the control unit50to preheat the powder layer32aon the build plate22(step S4). In the preheating step S4, the powder layer32ais preheated in order to pre-sinter the metal powder32. The preheating step S4is performed before a sintering step S5described later. As described above, the preheating step performed before the sintering step is also referred to as a powder-heat step.

InFIG.1, reference numeral E1denotes an unsintered region where the unsintered metal powder32exists, and reference numeral E2denotes a pre-sintered region where the pre-sintered metal powder32exists.

Next, the beam irradiation device14operates based on a control command given from the control unit50to sinter the metal powder32by melting and solidification (step S5).

In step S5, the metal powder32as a pre-sintered body is sintered by melting and solidifying the metal powder32pre-sintered as described above by irradiation with the electron beam15. In step S5, the control unit50sets the cross-sectional shape of each layer cut out from the three-dimensional shape data of the target manufactured object38as a melting target region, and controls the beam irradiation device14according to the build data associated with the cross-sectional shape of each layer. As a result, in the metal powder32on the build plate22, a melting target region represented by a two-dimensional cross-sectional shape is melted by irradiation with the electron beam15. The metal powder32melted by the irradiation of the electron beam15is solidified by natural cooling after the electron beam15passes. Thus, the manufactured object of the first layer is formed.

Next, the plate moving device26lowers the build plate22by a predetermined amount (AZ) by operating based on a control command given from the control unit50(step S6).

In step S6, the plate moving device26lowers the build plate22and the inner base24by AZ.

Subsequently, the beam irradiation device14operates based on a control command given from the control unit50to preheat the powder layer32aon the build plate22(step S7). In the first preheating step S7, as a preparation for spreading the metal powder32in the next layer, the powder layer32athat has completed the sintering step in the previous layer is preheated. As a result, the powder layer32ais heated to such an extent that the metal powder32of the next layer is pre-sintered. The preheating step S7may be performed after the sintering step S5described above or may be performed after a sintering step S10described later. As described above, the preheating step performed after the sintering step is also referred to as an after-heat step.

Next, the powder application device16operates based on a control command given from the control unit50to apply the metal powder32onto the build plate22to form the powder layer32a(step S8).

In step S8, the powder application device16operates similarly to step S3described above. Thus, on the build plate22, the second layer of metal powder32is spread over the sintered body formed of the first layer of metal powder32to form the powder layer32a.

Next, the beam irradiation device14operates based on a control command given from the control unit50to preheat the metal powder32forming the second powder layer32a(step S9). The preheating step S9is performed before a sintering step S10described later. Therefore, the preheating step S9is also referred to as a powder-heat step.

In step S9, the beam irradiation device14operates similarly to step S4described above.

As a result, the metal powder32forming the second powder layer32ais pre-sintered.

Next, the beam irradiation device14operates based on a control command given from the control unit50to sinter the metal powder32forming the second powder layer32aby melting and solidification (step S10).

In step S10, the beam irradiation device14operates similarly to step S5described above. Thus, the manufactured object of the second layer is formed.

Next, the control unit50checks whether or not the manufacturing of the target manufactured object38is completed (step S11). When it is determined that the manufacturing of the manufactured object38is not completed, the control unit50returns to step S6described above. As a result, the control unit50repeats the processes of steps S6to S10for each of the third and subsequent layers. When it is determined that the manufacturing of the manufactured object38is completed, the series of processes is ended.

By the three-dimensional powder bed fusion additive manufacturing (PBF-AM) process described above, the target manufactured object38is obtained.

FIG.4is a diagram illustrating a configuration example of a three-dimensional PBF-AM system according to the first embodiment of the present invention;

As illustrated inFIG.4, the three-dimensional PBF-AM system100includes the three-dimensional PBF-AM apparatus10and the build data generating device30. The configuration and operation of the three-dimensional PBF-AM apparatus10are as described above. The build data generating device30generates build data using three-dimensional shape data of an article generated by three-dimensional CAD or the like. The build data generated by the build data generating device30is recorded, for example, in a portable recording medium, and the build data is provided to the three-dimensional PBF-AM apparatus10using this recording medium. The provided build data is read by the control unit50of the three-dimensional PBF-AM apparatus10. The control unit50controls the operation of the three-dimensional PBF-AM apparatus10based on the build data read from the recording medium. Thus, the three-dimensional PBF-AM apparatus10manufactures the article according to the build data generated by the build data generating device30.

The method of providing the build data from the build data generating device30to the three-dimensional PBF-AM apparatus10is not limited to the above-described method using the portable recording medium. For example, the build data generated by the build data generating device30may be provided to the three-dimensional PBF-AM apparatus10via a cable or a network. Furthermore, the three-dimensional PBF-AM apparatus10may have a configuration having each function (seeFIG.5) of the build data generating device30.

The build data generated by the build data generating device30includes build data for controlling operations of the electron gun141, the converging lens142, and the deflection device143, build data for controlling the powder application device16, build data for controlling the plate moving device26, and the like.

However, in the present specification, the generation of build data for controlling the operation of the beam irradiation device14will be described, and the description regarding the generation of other build data will be omitted.

<Configuration of Build Data Generating Device>

FIG.5is a block diagram illustrating a configuration example of a build data generating device according to the first embodiment of the present invention; As illustrated inFIG.5, the build data generating device30includes a capturing unit301, a cutout unit302, a build data generating unit303, and an output unit304. Although not illustrated, the build data generating device30is configured by a computer including a processor such as a CPU and a storage unit such as a ROM, a RAM, an HDD, and an SSD. Each function of the build data generating device30is implemented by the processor reading a program written in advance in the ROM into the RAM and executing the program.

The capturing unit301captures three-dimensional shape data necessary for generating build data. The three-dimensional shape data is data for specifying a three-dimensional shape of an article generated by three-dimensional CAD or the like.

The cutout unit302cuts out the cross-sectional shape of each layer with a predetermined thickness from the three-dimensional shape data captured by the capturing unit301. This cross-sectional shape is a two-dimensional cross-sectional shape representing a shape of a region to be melted by irradiation with a beam (the electron beam15in the present embodiment), that is, a melting target region in each powder layer32a. Further, the cross-sectional shape cut out by the cutout unit302is a shape represented by one or more closed lines.

The build data generating unit303generates build data by applying a predetermined manufacturing condition to the cross-sectional shape cut out by the cutout unit302. This build data corresponds to build data (operation sequence program) for the control unit50to control the operation of the beam irradiation device14in the sintering steps S5and S10(FIG.3). The manufacturing condition includes a beam scanning condition and a beam irradiation condition. The beam scanning condition is a condition applied when the surface of the powder layer32ais scanned by the deflection device143with the electron beam15. The beam irradiation condition is a condition regarding the electron gun141and the converging lens142applied when the surface of the powder layer32ais irradiated with the electron beam15. There are various beam scanning conditions, and there are also various beam irradiation conditions. Hereinafter, a specific example of the beam scanning conditions and a specific example of the beam irradiation conditions will be described.

The beam scanning conditions include a beam scanning method, a distance between adjacent scanning lines (interval between scanning lines), a scanning speed, and the like. In addition, the beam scanning method includes raster scanning, annual ring-shaped vector scanning, random scanning, and the like. The raster scanning is a method of generating parallel scanning lines and scanning a beam along the generated scanning lines. The raster scanning includes unidirectional raster scanning and alternating direction raster scanning. The annual ring-shaped vector scanning is a method in which scanning lines are generated inward by a certain distance from a contour line forming a cross-sectional shape, and a beam is scanned along the generated scanning lines. The vector scanning includes a scanning method other than the annual ring-shaped vector scanning. The random scanning is a method of randomly beam scanning a region having a cross-sectional shape. When the surface of the powder layer32ais scanned by the electron beam15, the center of the spot of the electron beam15moves on the scanning line.

Meanwhile, the beam irradiation conditions include the current amount of the charged particle beam controlled by the electron gun141, the beam size in the manufactured surface controlled by the converging lens142, and the like. The current amount of the charged particle beam corresponds to the beam current amount. In the present embodiment, the electron beam15is used as the charged particle beam. Therefore, the current amount of the electron beam15corresponds to the current amount of the charged particle beam. The size (spot size) of the electron beam15on the manufactured surface32bcorresponds to the beam size on the manufactured surface. When the beam with which the surface of the powder layer32ais irradiated is a laser beam, the beam irradiation conditions include the intensity of the laser beam (beam intensity), the beam size on the manufactured surface, and the like.

In addition, the build data generating unit303generates a scanning line for scanning the surface of the powder layer32awith the electron beam15in the sintering step described above. That is, the build data generated by the build data generating unit303includes data of the scanning line. The scanning line is a line that defines a movement path (scanning path) of the electron beam15when a region (melting target region) having a cross-sectional shape of each layer is melted by irradiation with the electron beam15. That is, the electron beam15moves on the scanning line in the region having the cross-sectional shape.

Regarding the generation of the scanning line, the build data generating unit303generates a plurality of scanning lines by a predetermined beam scanning method in a region having a cross-sectional shape cut out by the cutout unit302, and generates correction scanning lines in a portion where the arrangement of the scanning lines becomes sparse and/or a portion where the arrangement of the scanning lines becomes dense. The scanning line generation processing by the build data generating unit303will be described in detail later.

The output unit304outputs the build data generated by the build data generating unit303to the electronic file. The build data output to the electronic file is provided to the three-dimensional PBF-AM apparatus10by the above-described method (for example, a method using a portable recording medium). Furthermore, in a case where the article to be manufactured is, for example, manufactured by powder bed fusion additive manufacturing in 100 layers, build data for 100 layers is provided to the three-dimensional PBF-AM apparatus10. Then, the control unit50of the three-dimensional PBF-AM apparatus10sequentially controls the operation of the entire three-dimensional PBF-AM apparatus10according to the build data provided from the build data generating device30.

<Processing Procedure of build data Generating Device>

FIG.6is a flowchart illustrating an example of a processing procedure (build data generating method) of the build data generating device according to the first embodiment of the present invention.

Next, the cutout unit302cuts out a cross-sectional shape of one layer from the three-dimensional shape data (step S32). The one layer includes one or a plurality of cross-sectional shapes.

Next, the build data generating unit303generates build data by applying a predetermined manufacturing condition to the cross-sectional shape cut out by the cutout unit302(step S33). The scanning line generation processing by the build data generating unit303is performed in step S33.

Next, the output unit305outputs the build data generated by the build data generating unit303in step S33to the electronic file (step S34).

Next, the build data generating device30determines whether there is a next layer (step S35).

This determination in step S35is performed, for example, by the cutout unit302. Then, in a case where there is the next layer (in a case of YES in step S35), the process returns to step S32described above, and in a case where there is no next layer (in a case of No in step S35), the series of processes is ended.

Next, the scanning line generation processing performed by the build data generating unit303will be described in detail with reference toFIGS.7to20.

First, as illustrated inFIG.7, the build data generating unit303generates a plurality of scanning lines41to47in a region of the cross-sectional shape40cut out by the cutout unit302by a predetermined beam scanning method. In the first embodiment, the build data generating unit303generates a plurality of scanning lines in the region of the cross-sectional shape40by the annual ring-shaped vector scanning method. As described above, the annual ring-shaped vector scanning method (hereinafter, also simply referred to as a “vector scanning method”) is a method of generating scanning lines inward by a certain distance from a contour line forming a cross-sectional shape. Therefore, the plurality of scanning lines generated by the vector scanning method are concentric scanning lines. As illustrated inFIG.7, the plurality of scanning lines generated by the vector scanning method may include scanning lines41,42, and43generated along the contour line of the cross-sectional shape40in a shape similar to the contour line, and scanning lines44,45,46, and47generated in an island shape in a shape different from the contour line of the cross-sectional shape40. The plurality of scanning lines41to47correspond to the concentric scanning lines generated by the annual ring-shaped vector scanning method.

As described above, when the plurality of scanning lines41to47are generated in the region of the cross-sectional shape40by the vector scanning method, as illustrated inFIG.7, portions P11and P12in which the arrangement of the scanning lines is sparser than other portions, and portions P13and P14in which the arrangement of the scanning lines is denser than other portions may occur. The other portion is, for example, a portion indicated by reference numeral P10inFIG.7. InFIG.7, for convenience, two portions in which the arrangement of the scanning lines becomes sparse and two portions in which the arrangement of the scanning lines becomes dense are illustrated, but there are other portions in which the arrangement of the scanning lines becomes sparse and other portions in which the arrangement of the scanning lines becomes dense. In the portions P11and P12where the arrangement of the scanning lines becomes sparse, the scanning lines are excessively separated from each other. Therefore, when the cross-sectional shape40to be the melting target region in the sintering step is beam scanned along the scanning line, melting defects due to insufficient melting are likely to occur in the portions P11and P12where the arrangement of the scanning lines becomes sparse. The melting defects due to insufficient melting are defects caused by insufficient amount of beam irradiation energy. On the other hand, in the portions P13and P14where the arrangement of the scanning lines becomes dense, the scanning lines are excessively close to each other. Therefore, when the cross-sectional shape40to be the melting target region in the sintering step is beam scanned along the scanning line, melting defects due to excessive melting are likely to occur in the portions P13and P14where the arrangement of the scanning lines becomes dense. The melting defects due to excessive melting are defects caused by excessive amount of beam irradiation energy.

Therefore, the build data generating unit303performs processing for generating correction scanning lines in the portions P11and P12where the arrangement of the scanning lines becomes sparse and the portions P13and P14where the arrangement of the scanning lines becomes dense.

The correction scanning line is generated to prevent the occurrence of the above-described melting defect. The build data generating unit303generates the correction scanning line by morphological graphic processing described below. In this morphological graphic processing, an interval between the scanning lines applied when the plurality of scanning lines41to47are generated by the above-described annual ring-shaped vector scanning method is d (μm) (seeFIG.7). A portion denoted by reference numeral P10inFIG.7corresponds to a portion of the scanning lines arranged at the interval d. The interval d between the scanning lines is an interval (distance between the scanning lines) defined by parallel portions of two adjacent scanning lines (for example, scanning line41and scanning line42). The value of the interval d of the scanning lines is designated (input) in advance by the user together with the beam size in the manufactured surface, for example.

In the morphological graphic processing, a constant a, a constant b, and a constant ε defined below are used.

The constant ε is a value larger than the calculation rounding error assumed to occur in the computer and smaller than the manufacturing dimension reproduction accuracy of the three-dimensional PBF-AM apparatus10. The constant ε is a value determined on the CAM software program, and the unit is μm.

Furthermore, in the present embodiment, it is assumed that the cross-sectional shape40cut out by the cutout unit302is a polygon, and this polygon is, for example, a figure expressed by designating coordinates of vertices with a numerical value. It is assumed that a polygon1A illustrated inFIG.8is a figure represented by a scanning line generated n-th from the outermost periphery of a cross-sectional shape40cut out by the cutout unit302and determined by the build data generating unit303as an n-th annual ring-shaped scanning line (not including a correction scanning line) by morphological graphic processing. Specifically, the polygon1A is a figure generated by the following procedure. First, the build data generating unit303generates a figure obtained by enlarging the figure represented by the scanning line41by a predetermined amount as a figure represented by an imaginary scanning line that is not actually output. As the predetermined amount, a value as closest to the interval d between the scanning lines (seeFIG.7) as possible is selected within a range in which self-intersection does not occur even when the figure represented by the scanning line41is enlarged by the predetermined amount. Next, the build data generating unit303performs morphological graphic processing (details will be described later) with the figure represented by the imaginary scanning line as the first processing target, and determines the annual ring-shaped scanning line and the correction scanning line corresponding to the annual ring-shaped scanning line generated by the graphic processing as the first scanning line and the correction scanning line. When a part of the correction scanning line generated by performing the morphological graphic processing protrudes to the outside of the scanning line41, the build data generating unit303deletes the protruding portion of the correction scanning line. A polygon1A illustrated inFIG.8is a figure represented by the annual ring-shaped scanning line determined as the first scanning line by the build data generating unit303. The polygon1A has inward acute angle vertices48aand48band outward acute angle vertices49aand49b.

First, as illustrated inFIG.9, the build data generating unit303generates a polygon1B (a figure indicated by a broken line inFIG.9) by reducing (contracting) the polygon1A by a dimension of (1+a)×d. In this reduction processing, with respect to the inward acute angle vertices48aand48bdescribed above, the movement amount Ls is limited such that the movement amount Ls of each of the acute angle vertices48aand48bis equal to or less than a×d×b. That is, a portion where the movement amount Ls of the acute angle vertices48aand48bexceeds a×d×b is cut out by the reduction processing. As a result, even if the end of the inward acute angle vertex48aof the polygon A1is pointed, the angle θ of the inward acute angle vertex of the polygon1B can be made obtuse. On the other hand, regarding the outward acute angle vertices49aand49b, it is not necessary to set a limitation on the movement amount. For this reason, the outward acute angle vertices49aand49bof the polygon1A may be in a state (shape) where the end of the acute angle vertex is pointed as in the polygon1B illustrated inFIG.9.

Next, as illustrated inFIG.10, the build data generating unit303generates a polygon1C (a figure indicated by an alternate long and short dash line inFIG.10) by enlarging (expanding) the polygon1B by a dimension of 2×a×d. In this enlargement processing, with respect to the outward acute angle vertices49aand49bdescribed above, the movement amount Ls is limited such that the movement amount Ls of the outward acute angle vertices in the polygon1B is equal to or less than a×d×b. As a result, the angle θ of the outward acute angle vertex of the polygon1C can be made an obtuse angle. On the other hand, regarding the inward acute angle vertex of the polygon1B, there is no need to set a limitation on the movement amount.

Next, as illustrated inFIG.11, the build data generating unit303generates a polygon1D (a figure indicated by a two-dot chain line inFIG.11) by reducing (contracting) the polygon1C by a dimension of a×d. The build data generating unit303determines one closed line representing the shape (contour) of the polygon1D as an (n+1)-th annual ring-shaped scanning line.

Next, as illustrated inFIG.12, the build data generating unit303generates a polygon1E (a figure indicated by a broken line inFIG.12) by reducing the polygon1A by a dimension of (1−a)×d.

Next, as illustrated inFIG.13, the build data generating unit303generates a polygon1F (a figure indicated by an alternate long and short dash line inFIG.13) by enlarging the polygon1D illustrated inFIG.11by a dimension of a×d+ε.

Next, as illustrated inFIG.14, the build data generating unit303generates (extracts) 0 or more polygons1G(i) by deleting the region of the polygon1F illustrated inFIG.13from the region of the polygon1E illustrated inFIG.12. The subscript i in the polygon1G(i) is an integer of 1 or more, and has a value that depends on the shape of the original figure (seeFIG.8). Thus, when the number of polygons1G generated by the build data generating unit303is m (the maximum value of i is m), the build data generating unit303generates polygons1G(1),1G(2), . . . , and1G(m). The polygon1G(i) is a portion where occurrence of a melting defect (melting defects due to insufficient melting, melting defects due to excessive melting, and the like) is predicted when a beam is scanned along the plurality of scanning lines41to47illustrated inFIG.7. That is, the build data generating unit303generates the polygon1G(i) to specify the portion of the polygon1G(i) as the portion where the occurrence of the melting defect is predicted.FIG.14illustrates a case where two polygons1G(1) and1G(2) are generated, that is, a case where m=2.

Next, as illustrated inFIG.15, the build data generating unit303generates a predetermined line1H(i, j) in the region of each polygon1G(1),1G(2), . . . ,1G(m) for the polygon1G(i). The predetermined line1H(i, j) is a line generated as a correction scanning line. In other words, the build data generating unit303generates the correction scanning line at a portion where the occurrence of the melting defect is predicted when the beam is scanned along the plurality of scanning lines41to47illustrated inFIG.7. The subscript i in the predetermined line1H(i, j) is the same as the subscript i in the polygon1G(i) described above. The subscript j in the predetermined line1H(i, j) is a natural number indicating the number of predetermined lines1H generated in the region of one polygon1G(i). That is, j=1, . . . , k. The maximum value k of j takes one or more different values depending on the shape of the polygon1G(i).FIG.15illustrates a case where the predetermined line1H(1,1) is generated in the region of the polygon1G(1) and the predetermined line1H(2,1) is generated in the region of the polygon1G(2). The predetermined line1H(i, j) is preferably a straight line, a polygonal line, or a branched line that is a middle line of the polygon1G(i).

The predetermined line1H(i, j) is a line capable of one-way scanning from one end to the other end of the predetermined line1H(i, j). As illustrated inFIG.7, each of the plurality of scanning lines41to47generated by the annual ring-shaped vector scanning method is represented by one closed line, but the predetermined line1H(i, j) is a non-closed line. Specifically, the predetermined line1H(i, j) is a line corresponding to at least one of a straight line, a polygonal line, and a branched line. When the predetermined line1H(i, j) is not branched, the value of j becomes 1. Further, when the predetermined line1H(i, j) is branched, the value of j becomes 2 or more.

FIG.16illustrates a case where the predetermined line1H(i, j) generated in the region of the polygon1G(i) is a straight line. The predetermined line1H(i, j) is one straight line1H(i,1) passing through the center in the short direction of the polygon1G(i) from one end to the other end in the longitudinal direction of the polygon1G(i).

FIG.17illustrates a case where the predetermined line1H(i, j) generated in the region of the polygon1G(i) is a polygonal line. The predetermined line1H(i, j) is one polygonal line1H(i,1) that passes through the center in the short direction of the polygon1G(i) from one end to the other end in the longitudinal direction of the polygon1G (i) and is bent halfway.

FIG.18illustrates a case where the predetermined line1H(i, j) generated in the region of the polygon1G (i) is a branched line. The predetermined line1H(i, j) is a branched line having a line1H(i,1) bent from one end toward the other end of the polygon1G(i) and a line1H(i,2) branched from the middle of the line1H(i,1). The line1H(i,1) and the line1H(i,2) are separated from each other at a P portion inFIG.18. By separating the line1H(i,1) and the line1H(i,2) at the P portion, it is possible to avoid excessive injection of the beam irradiation energy into the vicinity of the P portion.

In this manner, the build data generating unit303generates the predetermined line1H(i, j) in the region of each polygon1G(i). In other words, the build data generating unit303generates the predetermined line1H(i, j) for each polygon1G(i). Then, the build data generating unit303determines all the generated predetermined lines1H(i, j) as correction scanning lines corresponding to the (n+1)-th annual ring-shaped scanning lines.

As a result, as illustrated inFIG.19, the build data generating unit303generates an (n+1)-th annual ring-shaped scanning line51and correction scanning lines52aand52bcorresponding to the scanning line51. The scanning line51is a line representing the polygon1D illustrated inFIG.11. The correction scanning line52ais a line corresponding to the predetermined line1H(1,1) illustrated inFIG.15. The correction scanning line52bis a line corresponding to the predetermined line1H(2,1) illustrated inFIG.15. The scanning line51is one closed line, and the correction scanning lines52aand52bare non-closed lines.

The build data generating unit303executes the morphological graphic processing described with reference toFIGS.8to19for each polygon for the polygon represented by each of the scanning lines41to47illustrated inFIG.7. Furthermore, the build data generating unit303starts the process from a polygon indicating the contour line of the cross-sectional shape of the manufactured object or a polygon expanded or contracted by a certain distance from the contour line. Then, the above-described morphological graphic processing is repeated for all the polygons represented by the scanning lines41to47. As a result, as illustrated inFIG.20, the build data generating unit303generates a plurality of annual ring-shaped scanning lines61to66and a plurality of correction scanning lines71,72,73,74,75,76,77, . . . in the region of the cross-sectional shape40cut out from the three-dimensional shape data of the article.

Here, the correspondence relationship between the plurality of scanning lines41to47illustrated inFIG.7and the plurality of scanning lines61to66and correction scanning lines illustrated inFIG.20is as follows. The scanning line41corresponds to the scanning line61, the correction scanning line76, and the correction scanning line78, the scanning line42corresponds to the scanning line62, the correction scanning line77, and the correction scanning line79, and the scanning line43corresponds to the scanning line63, the correction scanning line72, and the correction scanning line80. Furthermore, the scanning line44corresponds to the scanning line64and the correction scanning line71, the scanning line45corresponds to the scanning line65, the correction scanning line81, and the correction scanning line82, and the scanning line46corresponds to the scanning line66, the correction scanning line74, and the correction scanning line83.

As can be seen fromFIGS.7and20, the correction scanning line71is added to the portion P11where the arrangement of the scanning lines becomes sparse, and the correction scanning line77is added to the portion P12where the arrangement of the scanning lines becomes sparse. On the other hand, the scanning line47is replaced with the correction scanning line75in the portion P13where the arrangement of the scanning lines becomes dense, and a part (pointed portion) of the scanning line41is replaced with the correction scanning line76in the portion P14where the arrangement of the scanning lines becomes dense. That is, the build data generating unit303adds the correction scanning line to the portion where the arrangement of the scanning lines becomes sparse, and replaces the scanning line with the correction scanning line in the portion where the arrangement of the scanning lines becomes dense. The same applies to a portion not denoted by a reference numeral inFIGS.7and20(portion that becomes sparse and portion that becomes dense).

As a result, when the build data generating unit303of the build data generating device30generates the build data, it is possible to prevent the scanning lines from being too far or too close, which may cause the melting defect, and to reduce the variation in density of the scanning lines. Furthermore, in the sintering step, the control unit50controls the beam irradiation device14according to the build data generated in advance by the build data generating unit303, so that the electron beam15is scanned along the plurality of scanning lines61to66and the plurality of correction scanning lines71,72,73,74,75,76,77, . . . to manufacture the article. Therefore, in the three-dimensional PBF-AM apparatus10, when an article is manufactured by melting the cross-sectional shape of each layer by irradiation (scanning) of the electron beam15, the occurrence of melting defects due to insufficient melting or excessive melting can be prevented.

Note that the order in which the beam irradiation device14of the three-dimensional PBF-AM apparatus10scans the plurality of scanning lines (61to66) and the plurality of correction scanning lines (71,72,73,74,75,76,77, . . . ) generated by the build data generating unit303of the build data generating device30with the electron beam15can be arbitrarily set.

For example, the plurality of scanning lines (61to66) may be beam scanned first from the outer scanning line, or may be beam scanned first from the inner scanning line. Adjacent scanning lines (61to66) may be sequentially beam scanned, or beam scanning may be repeated while several scanning lines are skipped. The plurality of scanning lines (61to66) may be beam scanned in a completely random order. When the plurality of scanning lines (61to66) are beam scanned in any order, all the scanning lines (61to66) need to be beam scanned.

For the plurality of correction scanning lines (71,72,73,74,75,76,77, . . . ), each time one annual ring-shaped scanning line is beam scanned, the correction scanning line associated with the scanning line may be beam scanned. The plurality of correction scanning lines (71,72,73,74,75,76,77, . . . ) may be beam scanned before the plurality of annual ring-shaped scanning lines (61to66) are beam scanned or after the plurality of annual ring-shaped scanning lines (61to66) are beam scanned.

Furthermore, the same manufacturing condition may be applied or different manufacturing conditions may be applied when beam scanning is performed with the plurality of scanning lines (61to66) and when beam scanning is performed with the plurality of correction scanning lines (71,72,73,74,75,76,77, . . . ). When different manufacturing conditions are applied, at least one of the scanning speed, the beam size in the manufactured surface, the beam current amount, and the beam intensity may be different.

Second Embodiment

Next, a second embodiment of the present invention will be described. The configuration and operation of the three-dimensional PBF-AM apparatus10and the configuration of the three-dimensional PBF-AM system100according to the second embodiment of the present invention are similar to those of the first embodiment described above. However, in the second embodiment of the present invention, the content of the scanning line generation processing (morphological graphic processing) performed by the build data generating unit303of the build data generating device30is different.

First, the build data generating unit303generates a plurality of scanning lines in a region of the cross-sectional shape cut out by the cutout unit302by a predetermined beam scanning method. In the first embodiment described above, the annual ring-shaped vector scanning method is adopted as the predetermined beam scanning method, but in the second embodiment, the raster scanning method is adopted.FIG.21illustrates an example of a cross-sectional shape to be melted by raster scanning. A figure representing the cross-sectional shape illustrated inFIG.21is a polygon2A.

As illustrated inFIG.22, the build data generating unit303generates a plurality of scanning lines2B(j) by the raster scanning method in a region having a cross-sectional shape (polygon2A) illustrated inFIG.21. The subscript j in the scanning line2B(j) is a natural number. When the number of scanning lines generated in the region of the cross-sectional shape by the build data generating unit303is n, j=1, 2, 3, . . . , n. The plurality of scanning lines2B(j) are scanning lines parallel to each other, that is, parallel line-shaped scanning lines (hereinafter, also referred to as a “raster scanning line”). Furthermore, the build data generating unit303generates the plurality of scanning lines2B(j) at a predetermined interval p (μm). The interval p corresponds to a distance between adjacent scanning lines in a direction orthogonal to the scanning line2B(j) (vertical direction inFIG.22). The value of the interval p of the scanning lines is designated (input) in advance by the user together with the beam size in the manufactured surface, for example. As a method of generating the plurality of scanning lines2B(j), for example, a method of generating the scanning lines2B(j) as a logical product portion of a raster scanning line that sufficiently covers the polygon2A and a region of the polygon2A can be considered.

Here, as illustrated inFIG.22, when the plurality of scanning lines2B(j) is generated in the region having the cross-sectional shape represented by the polygon2A by the raster scanning method, a portion where the arrangement of the scanning lines becomes sparse as compared with other portions occurs. Specifically, among the contours of the cross-sectional shape represented by the polygon2A, in contour portions P21, P22, P23, and P24inclined with respect to the scanning line2B(j), the arrangement of the scanning line2B(j) becomes sparse as compared with other portions (for example, a portion indicated by P20). The reason why the arrangement of the scanning lines2B(j) is sparse at the oblique contour portions P21, P22, P23, and P24is that the ends of the respective scanning lines2B(j) are shifted in the left-right direction ofFIG.22due to the inclination of the contour of the cross-sectional shape (polygon2A), whereby the distance between the ends of the scanning lines2B(j) becomes longer than the other portions. The other portion is, for example, a portion indicated by reference numeral P20inFIG.22. The portion indicated by the reference numeral P20is a portion perpendicular to the scanning line2B(j). In the portion indicated by the reference numeral P20, the ends of the respective scanning lines2B(j) are positioned substantially on the same line without being shifted in the left-right direction inFIG.22.

When the cross-sectional shape (polygon2A) to be the melting target region is subjected to beam scanning along the plurality of scanning lines2B(j) in the sintering step, the above-described contour portions P21, P22, P23, and P24are formed with stepped irregularities as shown inFIG.24, for example. When such irregularities appear on the surface of the manufactured object, it is necessary to remove the irregularities by subjecting the manufactured object obtained by powder bed fusion additive manufacturing to post-processing treatment. In particular, when the manufactured object is formed of a difficult-to-cut material, the time required for the post-processing treatment becomes long, and thus the production efficiency deteriorates.

Therefore, the build data generating unit303performs processing for generating correction scanning lines on the contour portions P21, P22, P23, and P24where the arrangement of the scanning lines becomes sparse. The correction scanning line is generated in order to reduce the irregularities of the surface or to prevent the occurrence of the melting defect. The build data generating unit303generates the correction scanning line by morphological graphic processing described below.

First, for each of the plurality of scanning lines2B(j) generated as described above, the build data generating unit303estimates (assumes) a range in which melting and solidification occur when beam scanning is performed along the scanning line2B(j) by calculation, simulation, or the like. Here, as an example, as illustrated inFIG.23, a range (hereinafter, also referred to as a “melting range”) in which melting and solidification occur when beam scanning is performed along the scanning line2B(1) is a range of a rectangle2C(1) that is a polygon having an appropriate width in each of the traveling direction of the scanning line2B(1) and a direction perpendicular to the traveling direction. In the sintering step, the spot of the electron beam15moves on the scanning line2B(1). Therefore, the build data generating unit303assumes a range of the rectangle2C(1) centered on the scanning line2B(1) as a range in which melting and solidification occur. Furthermore, the build data generating unit303assumes that the length L of the rectangle2C(1) is longer than the length of the scanning line2B(1). Furthermore, the build data generating unit303assumes the width W of the rectangle2C(1) centered on the position of the scanning line2B(1).FIG.23illustrates, as an example, an example in which the length L of the rectangle2C(1) is assumed to be longer than the length of the scanning line2B(1) by 0.5 times, that is, by 0.5p, the interval p (seeFIG.22) between the scanning lines at one end and the other end. Furthermore, inFIG.23, as an example, an example is illustrated in which the width W of the rectangle2C(1) is assumed to be 1.2 times the interval p of the scanning lines, that is, 1.2p.

Thus, the build data generating unit303assumes the melting range using a constant multiple of the interval p of the scanning lines. The melting range is preferably defined separately in a length direction of the scanning line2B(1) and a direction orthogonal to the length direction. This is because when the electron beam15is scanned along the raster scanning line, the amount of energy injected by the irradiation of the electron beam15is different between the vicinity of the end in the length direction of the raster scanning line and a portion other than the vicinity of the end. Specifically, the cumulative irradiation time of the electron beam15is shorter in the end in the length direction of the raster scanning line than in a portion other than the end in the length direction, and the amount of energy injected is less because of the shorter cumulative irradiation time of the electron beam15. Therefore, in order to more accurately assume the melting range, it is reasonable to make the constant applied to the calculation of the length L of the rectangle2C(1) smaller than the constant applied to the calculation of the width W of the rectangle2C(1).

The build data generating unit303obtains rectangles2C(2),2C(3), . . . , and2C(n) indicating assumed melting ranges for the other scanning lines2B(2),2B(3), . . . , and2B(n) as in the case of the scanning line2B(1) described above. Furthermore, the build data generating unit303combines (fuses) all the rectangles2C(1),2C(2),2C(3), . . . , and2C(n) indicating the assumed melting range to generate a polygon2C (a figure indicated by an alternate long and short dash line inFIG.24) as illustrated inFIG.24.

Next, as illustrated inFIG.25, the build data generating unit303generates (extracts) the remaining region obtained by removing the region of the polygon2C from the region of the polygon2A as 0 or more polygons2D (i). A subscript i in the polygon2D(i) is an integer of 1 or more. Thus, when the number of polygons2D generated by the build data generating unit303is m (the maximum value of i is m), the build data generating unit303generates polygons2D(1),2D(2), . . . , and2D(m). That is, the value of m indicates the number of polygons2D(i) generated by the build data generating unit303. The polygons2D(1),2D(2), . . . , and2D(m) are portions where occurrence of a melting defect (such as a melting defect due to insufficient melting) or a recess is predicted when a beam is scanned along the scanning line2B(j) illustrated inFIG.22. That is, the build data generating unit303generates the polygon2D(i) to specify the portion of the polygon2D(i) as the portion where the occurrence of the melting defect or the recess is predicted. In this case, a portion where each of the polygons2D(1),2D(2), . . . , and2D(m) exists corresponds to a portion where the arrangement of the scanning line2B(j) becomes sparse in the oblique contour portions P21, P22, P23, and P24illustrated inFIG.22. InFIG.25, only some polygons2D(i) among the plurality of polygons2D(i) generated by the build data generating unit303are denoted by reference numerals.FIG.26is an enlarged view of an R portion inFIG.25. When the build data generating unit303does not generate any polygon2D(i), the build data generating unit303does not generate the correction scanning line.

On the other hand, when the build data generating unit303generates one or more polygons2D(i), the build data generating unit303generates a predetermined line2E(i) in the region of each polygon2D(i) as illustrated inFIG.27. The predetermined line2E(i) is a line generated as a correction scanning line. In other words, the build data generating unit303generates a correction scanning line at a portion where occurrence of a melting defect (such as a melting defect due to insufficient melting) or a recess is predicted when a beam is scanned along the scanning line2B(j) illustrated inFIG.22. The subscript i in the predetermined line2E(i) is the same as the subscript i in the polygon2D(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 scanning lines generated by the build data generating unit303. The predetermined line2E(i) is a line capable of one-way scanning from one end to the other end of the predetermined line2E(i). In addition, the predetermined line2E(i) is a line that is not closed.

FIG.27illustrates, as an example, a case where the build data generating unit303generates a predetermined line2E(1) in the region of the polygon2D(1). The predetermined line2E(1) is one polygonal line that passes through the center in the short direction of the polygon2D(1) from one end to the other end in the longitudinal direction of the polygon2D(1) and is bent halfway. However, the predetermined line2E(1) may be one straight line passing through the center in the short direction of the polygon2D(1) from one end to the other end in the longitudinal direction of the polygon2D(1). The build data generating unit303generates predetermined lines2E(2),2E(3), . . . ,2E(m) for the other polygons2D(2),2D(3), . . . ,2D(m) as in the case of the polygon2D(1). Then, the build data generating unit303determines all the generated predetermined lines2E(i) as correction scanning lines corresponding to the cross-sectional shape of the polygon2A.

Thus, as illustrated inFIG.28, the build data generating unit303generates a plurality of scanning lines2B(j) and a plurality of correction scanning lines2E(i). The plurality of scanning lines2B(j) are parallel line-shaped scanning lines generated by the raster scanning method as illustrated inFIG.22. As can be seen fromFIG.28, the correction scanning line2E(i) is generated between the adjacent scanning lines2B(j) in a direction (vertical direction inFIG.28) orthogonal to the scanning line2B(j). Specifically, the correction scanning line2E(1) will be described as an example. The correction scanning line2E(1) is generated between the scanning line2B(12) and the scanning line2B(13) adjacent to each other in the vertical direction inFIG.28.

As a result, when the build data generating unit303of the build data generating device30generates the build data, it is possible to prevent the scanning lines from being too far, which may cause the melting defect and the recess, and to reduce the variation in density of the scanning lines. Furthermore, in the sintering step, the control unit50controls the beam irradiation device14according to the build data generated in advance by the build data generating unit303, so that the electron beam15is scanned along the plurality of scanning lines2B(j) and the plurality of correction scanning lines2E(i) to manufacture the article. Therefore, in the three-dimensional PBF-AM apparatus10, when an article is manufactured by melting the cross-sectional shape of each layer by irradiation (scanning) of the electron beam15, the occurrence of melting defects and recesses due to insufficient melting can be prevented. Therefore, it is possible to prevent the occurrence of irregularities in the contour portions P21, P22, P23, and P24(seeFIG.22).

Note that the order in which the beam irradiation device14of the three-dimensional PBF-AM apparatus10scans the plurality of scanning lines2B(j) and the plurality of correction scanning lines2E(i) generated by the build data generating unit303of the build data generating device30with the electron beam15can be arbitrarily set.

For example, the plurality of scanning lines2B(j) may be beam scanned first from the scanning line2B(1) on the upper side inFIG.28, or may be beam scanned first from the scanning line2B(n) on the lower side inFIG.28. Further, scanning lines adjacent in the vertical direction inFIG.28may be sequentially beam scanned, or beam scanning may be repeated while several scanning lines are skipped. The plurality of scanning lines2B(j) may be beam scanned in a completely random order. When the plurality of scanning lines2B(j) are scanned in any order, all the scanning lines2B(j) need to be beam scanned.

For the plurality of correction scanning lines2E(i), for example, every time one scanning line is beam scanned, a correction scanning line located between the scanning line and a scanning line adjacent to the scanning line may be beam scanned. As a specific example, inFIG.28, after beam scanning is performed with the scanning line2B(12), beam scanning is performed with the correction scanning line2E(1), and then beam scanning is performed with the scanning line2B(13), and beam scanning is performed with the correction scanning line2E(2). The plurality of correction scanning lines2E(i) may be beam scanned before the plurality of scanning lines2B(j) are beam scanned or after the plurality of scanning lines2B(j) are beam scanned.

Furthermore, the same manufacturing condition may be applied or different manufacturing conditions may be applied when beam scanning is performed with the plurality of scanning lines2B(j) and when beam scanning is performed with the plurality of correction scanning lines2E(i). When different manufacturing conditions are applied, at least one of the scanning speed, the beam size in the manufactured surface, the beam current amount, and the beam intensity may be different.

As a technique for suppressing the occurrence of irregularities in the contour portions P21, P22, P23, and P24(seeFIG.22), there is a technique of generating a contour scanning line along a contour line of a cross-sectional shape of a manufactured object and performing beam scanning (vector scanning) along the contour scanning line. The contour scanning line is a line representing a figure similar in shape to the cross-sectional shape of the manufactured object. In the technique, the contour scanning line is generated only in the surface region of the manufactured object with respect to the region of the cross-sectional shape of the manufactured object. A plurality of scanning lines are generated by a raster scanning method in a region inside the surface region of the manufactured object. Thus, in the sintering step, beam scanning (vector scanning) along the contour scanning line and beam scanning (raster scanning) along the plurality of scanning lines are performed. Therefore, the occurrence of irregularities on the surface of the manufactured object can be prevented including the contour portions P21, P22, P23, and P24(seeFIG.22). Furthermore, when the raster scanning method is applied to a region on the inner side of the surface region of the manufactured object, there is an advantage that a wide range can be uniformly melted at high speed when the cross-sectional shape of the manufactured object is melted by beam scanning.

However, even in a case where the contour scanning line is generated in the surface region of the manufactured object and the plurality of scanning lines is generated in the region on the inner side of the surface region of the manufactured object by the raster scanning method as described above, when the polygon2A is regarded as a region to which the raster scanning method is applied, a melting defect due to insufficient melting or excessive melting may occur in the contour portions P21, P22, P23, and P24(seeFIG.22). Even in such a case, the insufficient melting and the excessive melting are eliminated by the build data generating unit303generating the plurality of scanning lines2B(j) and the plurality of correction scanning lines2E(i) as illustrated inFIG.28, so that the occurrence of the melting defect can be prevented.

<Modifications and the Like>

The technical scope of the present invention is not limited to the above-described embodiment, and includes a mode in which various modifications and improvements are added within a range in which specific effects obtained by the constituent elements of the invention and the combination thereof can be derived.

For example, in a case where a plurality of scanning lines are generated by a predetermined beam scanning method, when there are both a portion where the arrangement of the scanning lines becomes sparse and a portion where the arrangement of the scanning lines becomes dense, the build data generating unit303may generate the correction scanning lines only in the portion where the arrangement of the scanning lines becomes sparse, or may generate the correction scanning lines only in the portion where the arrangement of the scanning lines becomes dense. However, the build data generating unit303preferably generates correction scanning lines in a portion where the arrangement of the scanning lines becomes sparse and a portion where the arrangement of the scanning lines becomes dense.