Additive manufacturing method and additive manufacturing device

Abstract

The additive manufacturing method has the following procedures: when forming a bead layer, for each machining path, detecting whether a bead (BD) exists in the lower layer; skipping machining from the first machining path (Pn) where no bead (BD) is detected to the last machining path (Pn+1) where no bead (BD) is detected; forming a bead (BD) with a second cross-sectional area in the corrected machining path (Pcn1) where the position of the machining path (Pn) is corrected; and forming a bead (BD) or a bead (BD) with a third cross-sectional area in the machining paths from the next machining path (Pn+1) of the corrected machining path (Pcn1) to the last machining path (Pn+1) where no bead (BD) is detected.

Description

Technical Field

[0001] This invention relates to an additive manufacturing method and apparatus for manufacturing 3D objects. Background Technology

[0002] Additive manufacturing (AM) is a known technique for creating 3D objects. In Directed Energy Deposition (DED), one of the many methods of additive manufacturing, material is supplied to a designated location while a beam irradiates the material and the workpiece, thereby forming weld beads. The object is then created by stacking these weld beads sequentially.

[0003] It is desirable to manufacture a cavity-shaped object with an elongated hole using the additional manufacturing method described above. The cavity-shaped object is used, for example, as a mold, and refrigerant flows within the cavity of a circular cross-section in order to control the temperature of the mold. In Non-Patent Document 1, the cavity cross-sectional shape is set to a teardrop shape, and by reducing the angle of the top of the cavity, weld beads are prevented from sag into the cavity of the object.

[0004] Non-Patent Document 1: Jack Holmes and Joe Pike, “Autodesk study Class_Handout_TR501949_ClassHandout-TR501949-Holmes-AU2022”, [online], Autodesk University, [retrieved June 19, 2023], Internet, <URL: Using Autodesk Fusion 360 and Metal AM to Optimize Automotive Mold Cooling Solutions | Autodesk University> Summary of the Invention

[0005] If a teardrop-shaped cavity is manufactured using existing manufacturing methods, stress concentration may occur starting from the corner of the teardrop shape, potentially reducing the product's lifespan and causing problems such as deterioration in product size and shape due to impurity deposition.

[0006] The present invention was made in view of the above circumstances, and its object is to provide an additional manufacturing method that can prevent the weld bead at the top of the cavity from sagging due to the effects of gravity and thermal strain.

[0007] To solve the above-mentioned problems and achieve the objective, the additional manufacturing method of the present invention moves the processing point along multiple processing paths extending in the first direction to form a weld bead layer in which multiple first cross-sectional areas of first weld beads are arranged in a second direction perpendicular to the first direction. By stacking the weld bead layer in a third direction perpendicular to the first and second directions, a weld bead layer accumulation is formed, i.e., a 3D shape with a cavity. The additional manufacturing method includes: an inspection step, which, during the formation of the weld bead layer, inspects for the presence of a first weld bead in the lower layer for each processing path; a skipping step, which skips the processing in the processing paths arranged in the second direction from the first processing path (i.e., the first processing path) where the absence of a first weld bead in the lower layer is detected to the last processing path (i.e., the second processing path) where the absence of a first weld bead in the lower layer is detected; a second weld bead forming step, which forms a second weld bead having a second cross-sectional area in the corrected first processing path where the position of the first processing path has been corrected; and a third weld bead forming step, which forms a first weld bead or a third weld bead having a third cross-sectional area in the processing path from the next processing path of the corrected first processing path to the second processing path.

[0008] The effects of the invention

[0009] According to the additional manufacturing method of the present invention, the weld bead at the top of the cavity is prevented from sagging due to the effects of gravity and thermal strain. Attached Figure Description

[0010] Figure 1 This is a diagram showing the structure of the additional manufacturing apparatus involved in Embodiment 1.

[0011] Figure 2 This is a perspective view showing an example of a design model of a finished product formed by the additional manufacturing apparatus involved in Embodiment 1.

[0012] Figure 3 It is a perspective view of the model of the finished product formed by the additional manufacturing apparatus involved in Embodiment 1.

[0013] Figure 4 This is a diagram used to illustrate the intermediate processing path introduced by the additional manufacturing apparatus involved in Embodiment 1.

[0014] Figure 5 This is a diagram used to explain the skipping process and the intermediate processing path formation process in the additional manufacturing apparatus according to Embodiment 1.

[0015] Figure 6 This is a diagram used to explain the processing position and the cross-sectional area of ​​the weld bead on the intermediate processing path in the additional manufacturing apparatus according to Embodiment 1.

[0016] Figure 7 This is a flowchart illustrating the skipping process and intermediate processing path formation process of the processing path executed by the control device in the additional manufacturing apparatus according to Embodiment 1.

[0017] Figure 8 This is a flowchart illustrating the first example of the overall operation flow executed by the control device in the additional manufacturing apparatus according to Embodiment 1.

[0018] Figure 9 This is a flowchart illustrating a second example of the overall operation flow performed by the control device in the additional manufacturing apparatus according to Embodiment 1.

[0019] Figure 10 This is a perspective view of an example of a design model of a finished product formed by the additional manufacturing apparatus involved in Embodiment 2.

[0020] Figure 11 It is a cross-sectional view of the model of the finished product formed by the additional manufacturing apparatus involved in Embodiment 2.

[0021] Figure 12 It is a cross-sectional view of the model of the finished product formed by the additional manufacturing apparatus involved in Embodiment 2.

[0022] Figure 13 It is a sectional view that represents the shaping method in a scale.

[0023] Figure 14 This is a cross-sectional view showing the shaping method in the additional manufacturing apparatus according to Embodiment 2.

[0024] Figure 15 This is a diagram showing an example of the height measurement result of the height measuring device in the additional manufacturing apparatus according to Embodiment 2. Detailed Implementation

[0025] The additional manufacturing method and additional manufacturing apparatus involved in the embodiments will now be described in detail based on the accompanying drawings.

[0026] Implementation Method 1

[0027] Figure 1This diagram illustrates the structure of the auxiliary manufacturing apparatus 100 according to Embodiment 1. The auxiliary manufacturing apparatus 100 is a DED (Dual Engraving and Finishing) type auxiliary manufacturing apparatus. The auxiliary manufacturing apparatus 100 supplies material to the workpiece 9 and stacks weld beads formed by the material molten using a beam, thereby manufacturing the shaped object 1. The beam is a heat source that melts the material, such as a laser beam L or an electron beam. The heat source is not limited to a beam and can also be an electric arc. In Embodiment 1, the case where the heat source is a laser beam L will be described. Furthermore, in Embodiment 1, the material is a metallic wire 3. The material is not limited to wire 3 and can also be powder. Additionally, a stacking method other than DED can also be used.

[0028] The auxiliary manufacturing apparatus 100 supplies wire 3 to the indicated processing point 13 while irradiating the wire 3 and the workpiece 9 with a laser beam L, thereby forming a weld bead. The weld bead is a solidified product obtained by molten material solidifying at the workpiece. The weld bead is formed in a molten pool. The molten pool is an accumulation of molten metal formed by melting the workpiece 9 and the wire 3 through irradiation with the laser beam L.

[0029] On the substrate 2, a weld bead layer is formed by arranging multiple weld beads. Through the stacking of weld bead layers, a weld bead accumulation, i.e., the shaped object 1, is formed. As described above, the auxiliary manufacturing apparatus 100 manufactures the 3D shaped object, i.e., the shaped object 1, by stacking the weld bead layers. The workpiece 9 is an object to which molten material is applied, comprising the substrate 2 and the shaped object 1 during the forming process. The shaped object 1 is formed on the substrate 2.

[0030] The X, Y, and Z axes are three mutually perpendicular axes. The X and Y axes are two horizontal axes. The Z axis is a vertical axis. In each of the X, Y, and Z axes, the direction indicated by the arrow is designated as positive, and the opposite direction is designated as negative. The positive Z direction is vertically upward. The weld beads BD are stacked in the positive Z direction. In Embodiment 1, for ease of explanation, it is assumed that the weld beads extend in the Y direction (a first direction), the weld beads extending in the Y direction are arranged in the X direction (a second direction) to form a weld bead layer, and the weld bead layer is stacked in the Z direction (a third direction).

[0031] The auxiliary manufacturing apparatus 100 includes a laser oscillator 11, a gas supply device 20, a wire supply device 30, a processing head 7, a worktable 40, a processing head drive device 50, a height measuring device 8, and a control device 15. The control device 15 is, for example, a numerical control (NC) device, connected to an external computer 16. The external computer 16 is equipped with CAD (Computer Aided Design) and CAM (Computer Aided Manufacturing).

[0032] The laser oscillator 11, serving as the beam source, outputs a laser beam L. The laser beam L output by the laser oscillator 11 is transmitted within the optical fiber 10, which serves as the optical transmission path, and is directed into the processing head 7. An optical system (not shown) is disposed inside the processing head 7.

[0033] The processing head 7 is equipped with: a beam nozzle (not shown), through which a laser beam L emitted from the processing head 7 towards the processing point 13 passes; and a gas nozzle 14, which sprays protective gas towards the processing point 13. The laser beam L passes through the optical system inside the processing head 7, passes through the beam nozzle, and exits from the processing head 7. The processing point 13 is the irradiation position of the laser beam L on the workpiece 9, and is the area where the attached wire 3 is applied. In the additional processing of the molten material, the additional manufacturing apparatus 100 moves the processing point 13 along a processing path that serves as a moving path. The position of the processing point 13 is the position where the heat source and material are supplied, and is located on the central axis of the beam nozzle. The processing path that serves as the moving path is specified by the processing program.

[0034] The gas supply device 20 supplies protective gas from a gas supply source (not shown) to the gas nozzle 14. The gas supply device 20 can adjust the flow rate of the protective gas based on a gas supply command from the control device 15. The injection of the protective gas reduces oxidation of the material and the workpiece 9, and cools the molded object 1. The protective gas is preferably an inert gas such as argon.

[0035] The wire supply device 30 includes a wire feeder 5 and a wire nozzle 4. The wire 3 is fed to the processing point 13 by the wire feeder 5 through the wire nozzle 4. The wire nozzle 4 is supported at an angle relative to the shape 1 on the worktable 40.

[0036] The machining head drive device 50 moves the machining head 7 in the X-axis, Y-axis and Z-axis directions based on instructions from the control device 15.

[0037] The object 1 is mounted and fixed on the base material 2 of the worktable 40. The worktable 40 sometimes rotates about the Z-axis, and sometimes rotates about both the Z-axis and the X-axis.

[0038] The height measuring device 8, acting as a detection device, detects the presence of weld beads in the lower layer for each processing path. In this case, the height measuring device 8 detects the height of the processing path, i.e., the height of the shaping object 1 during the shaping process, along the processing path for each processing path. In other words, the height measuring device 8 detects the height of the previous layer's shaping object 1, i.e., the weld beads of the previous layer, at the XY position corresponding to the current processing path along the processing path. The height measuring device 8 detects cavities in the shaping object 1 based on the detected height. The processing path, as described above, is the movement path of the processing point 13. When the height measuring device 8 identifies that there are no weld beads of the previous layer at the XY position of the current processing based on the detected height, it determines that a cavity exists. Although the detection principle of the height measuring device 8 may vary, in the case where the height measuring device 8 cannot perform height detection at the position where there are no weld beads of the previous layer, it detects the existence of a cavity when height detection is not possible. In addition, in the case where the height measuring device 8 can also perform height detection at the position where there are no weld beads of the previous layer, it detects the existence of a cavity when the detected height is less than a preset threshold. The height measuring device 8 can be, for example, a laser displacement meter or a camera. Furthermore, the height measuring device 8 is also used when determining the formation position of the weld bead formed by the machining path preceding the machining path of interest during the formation of intermediate machining paths, as described later.

[0039] The control device 15 drives and controls the laser oscillator 11, the wire feeder 5, the processing head drive device 50, the gas supply device 20, the height measuring device 8, and the worktable 40. In addition, the worktable 40 under the object 1 can rotate, so height measurement and layering can be performed while the object 1 is tilted to an appropriate position.

[0040] Based on this structure, the object 1 can rotate, and the processing head 7 can move in the XYZ axis direction. Therefore, while irradiating the laser beam L to any position of the object 1, the metal wire 3 can be extracted and welded to form the desired 3D object.

[0041] In Embodiment 1, if a cavity is detected in the shape 1 by the height measuring device 8, the machining path is skipped until the cavity disappears. If a machining path exists at the location where the cavity disappears, machining is performed, and the process returns to the first skipped location. Furthermore, at the first skipped location, the normal machining path set by the machining program is corrected, and machining with a weld diameter different from the normal weld diameter is performed at the corrected machining location. Then, the skipped weld portion is machined, for example, while maintaining the original machining position and the original weld diameter. The machining performed through the skipped machining path is referred to as machining under the intermediate machining path. The details will be explained below.

[0042] Figure 2 This is a perspective view showing an example of a design model of a finished product formed by the additional manufacturing apparatus 100 according to Embodiment 1. The design model is a circular tube shape with a through cavity K having a circular cross-section. In this design model, the shape of the elements in the water pipe is extracted as the design model.

[0043] Figure 3 This is a perspective view of a model of a finished product formed by the additional manufacturing apparatus 100 according to Embodiment 1. In this case, in the model, weld beads BD extending in the Y direction are arranged in the X direction to form one weld bead layer. Multiple weld bead layers are stacked in the Z direction. In the model, a portion of the intermediate layer corresponding to the cavity K is not processed and no processing is performed, thereby forming the cavity K.

[0044] Figure 4 This is a diagram used to illustrate the intermediate processing path introduced by the additional manufacturing apparatus 100 according to Embodiment 1. Figure 4 The left and right figures show the process of... Figure 3 The processing details corresponding to the shown model. Figure 4 In the process, each weld bead BD extends in the Y direction. Figure 4 In the left image, the topmost machining path contains three machining paths: Pn-1, Pskip, and the skipped machining path Pskip, which forms the weld bead BD represented by the dashed line. Figure 4 In the right figure, the machining path used to form the weld bead BD surrounded by thick lines in the uppermost machining path is the aforementioned intermediate machining path Pcn.

[0045] exist Figure 4In this process, the intermediate machining path Pcn is the machining path that replaces the skipped machining path Pskip when the cavity K is detected by the height measuring device 8. In the uppermost machining path used to fill the cavity K, after forming the weld bead BD through the end machining path Pn-1, machining is skipped through the machining path Pskip. In the opposite end machining path Pe, since the weld bead BD has already been formed in the previous layer, the weld bead BD of the intermediate machining path Pcn is formed next. In the intermediate machining path Pcn, after machining the machining path connected to the end machining path Pn-1, machining the machining path connected to the opposite end machining path Pe is performed. The lower part of the weld bead BD generated by the intermediate machining path Pcn is connected to the cavity K, and the cross-sectional area of ​​the weld bead BD generated by the intermediate machining path Pcn connected to the end machining path Pn-1 is larger than the cross-sectional area of ​​the weld bead BD that is not connected to the cavity K at the lower part. The cross-sectional area of ​​the weld bead BD generated by the intermediate machining path Pcn, which connects to the machining path Pe at the opposite end, is the same as the cross-sectional area of ​​the weld bead BD at the bottom that does not connect to the cavity K.

[0046] Next, according to Figure 5 The process of skipping the processing path and forming the intermediate processing path Pcn is explained in more detail. Figure 5 This is a diagram illustrating the skipping process and intermediate processing path formation process in the additional manufacturing apparatus 100 according to Embodiment 1. Figure 5 The image includes the top left, top middle, top right, bottom left, and bottom middle images, processed in the order indicated by the arrows. Figure 5 In the paper, each weld bead BD extends in the Y direction, which is perpendicular to the paper surface.

[0047] exist Figure 5 In the upper left figure, in the uppermost machining path used to fill cavity K, in the end machining path Pn-1, the presence of cavity K is detected based on the height measurement in the Z direction along the Y direction by the height measuring device 8. The path of the height measuring device 8 along the Y direction is the same as machining path Pn-1. In machining path Pn-1, since it is determined that cavity K does not exist, a weld bead BD is formed in machining path Pn-1. Then, in machining path Pn, the presence of cavity K is detected based on the height measurement in the Z direction along the Y direction by the height measuring device 8. In machining path Pn, since the bottom of cavity K is measured, the presence of cavity K is detected. Therefore, machining in machining path Pn is skipped. Figure 5 As shown in the upper middle figure, in the next machining path Pn+1, the existence of cavity K is also detected by the height measuring device 8, and the machining is skipped in machining path Pn+1.

[0048] like Figure 5 As shown in the upper right figure, in the processing path Pe, the weld bead BD has already been formed in the previous layer. The first processing path that detects that there is no weld bead BD in the lower layer, i.e., processing path Pn, corresponds to the first processing path. The last processing path that detects that there is no weld bead BD in the lower layer, i.e., processing path Pn-1, corresponds to the second processing path.

[0049] Next, return to the first skipped machining path Pn. Then, between the first skipped machining path Pn and the preceding machining path Pn-1, generate an intermediate machining path Pcn1 as the corrected first machining path and perform machining. The first machining path, i.e., the machining path preceding machining path Pn (maybe machining path Pn-1), corresponds to the third machining path. In the intermediate machining path Pcn1, the XZ position is obtained by correcting the XZ position of the skipped original machining path Pn, and the cross-sectional area ratio of the generated weld bead BD is adjusted accordingly. Figure 3 The machining path Pn shown in the model has a large weld cross-sectional area. In other words, the weld cross-sectional area of ​​the intermediate machining path Pcn1 is larger than the cross-sectional area of ​​the weld BD that is not connected to the cavity K at the bottom. The normal weld BD that is not connected to the cavity K at the bottom, or each weld BD specified by the design model, corresponds to the first weld, and the cross-sectional area of ​​the first weld corresponds to the first cross-sectional area. The weld BD formed by the intermediate machining path Pcn1 corresponds to the second weld, and the cross-sectional area of ​​the second weld corresponds to the second cross-sectional area.

[0050] Then, regarding the skipped machining path Pn+1, the weld bead BD of the intermediate machining path Pcn2 is formed using the original machining path Pn+1 position and the original weld bead cross-sectional area. Furthermore, although this will be described later, a third weld bead with a larger third cross-sectional area than the first cross-sectional area can also be formed in machining path Pn+1, after changing the position of the machining path and the cross-sectional area of ​​the weld bead BD.

[0051] Next, the location and weld cross-sectional area of ​​the aforementioned intermediate processing path Pcn1 will be explained. Figure 6 This is a diagram used to explain the processing position and weld cross-sectional area on the intermediate processing path Pcn1 in the auxiliary manufacturing apparatus 100 according to Embodiment 1. Figure 6 The images include the top left, top right, bottom left, and bottom right images, which will be explained in that order.

[0052] like Figure 6 As shown in the upper left figure, in the design model of the finished product, machining paths Pn-1, Pn, and Pn+1 are arranged at equal intervals along the circumference. In machining path Pn-1, the segment preceding machining path Pn that detects the cavity K via the height measuring device 8, if weld bead BDn-1 is formed during actual machining, as shown... Figure 6 As shown in the upper right figure, the center position O'n-1 of weld bead BDn-1 is offset from the XZ position of processing path Pn-1 due to the influence of gravity and thermal strain. Therefore, if the weld bead of the next processing path Pn is formed under such conditions, the original overlap amount, i.e., the first overlap amount θ, cannot be maintained between processing paths Pn-1 and Pn, resulting in defects such as gaps and reduced strength. The first overlap amount θ is represented by an angle between the overlapping portions of two adjacent weld beads BD centered on the center C of the finished product's design model, and is predetermined.

[0053] Therefore, as Figure 6 As shown in the lower left figure, when forming the next weld bead BDn, the original processing path Pn is corrected, and the corrected processing path, i.e., the intermediate processing path Pcn, is imported. In the intermediate processing path Pcn, the center position O'n and the radius R (cross-sectional area of ​​the weld bead BDn are derived by overlapping the weld bead BDn-1 of the previous processing path Pn-1 and the next processing path Pn+1 with the first overlap amount θ. The derived center position O'n of the weld bead BDn is determined as the XZ position of the intermediate processing path Pcn. In addition, the formation position of the weld bead BDn-1 is derived based on the measurement results of the height measuring device 8. By changing the processing conditions, including the laser output of the laser oscillator 11, the wire supply speed of the wire feeder 5, and the XY axis movement speed generated by the processing head drive device 50, the cross-sectional area of ​​the weld bead BDn can be adjusted. The XZ position of the intermediate processing path Pcn is the same as that of the original processing path Pn, located on the circumference centered on the center C. Subsequently, a weld bead BDn with radius R is formed on the exported intermediate machining path Pcn.

[0054] Next, as Figure 6 As shown in the lower right figure, regarding the next intermediate processing path Pcn+1, a weld bead BDn+1 with the same cross-sectional area as the original processing path Pn+1 is formed on the original processing path Pn+1. However, the formation position of the weld bead BDn can also be derived based on the measurement results of the height measuring device 8. The center position of the weld bead BDn+1 and the radius R (cross-sectional area of ​​the weld bead) are derived by overlapping the weld bead BDn and the weld bead BDe on the already formed processing path Pe with the first overlap amount θ, and then processing is performed.

[0055] In addition, Figure 6 In this process, the intermediate processing path Pcn is calculated based on the position on the circumference. However, as long as the overlap θ set based on the formation position of weld BDn-1 on the previous processing path Pn-1 and the formation position of weld Bn+1 on the next processing path Pn+1 can be maintained, it is not limited to calculation based on the circumference. Calculation based on polygons or arbitrary curves can also be used.

[0056] Figure 7 This is a flowchart illustrating the skipping process and intermediate processing path formation process of the processing path executed by the control device 15 in the additional manufacturing apparatus 100 according to Embodiment 1. The control device 15 determines whether the current processing path is connected to the cavity K (step S10). Figure 7 The flowchart shown only describes the processes of skipping machining paths and forming intermediate machining paths; the description of the normal machining process is omitted. When the control device 15 determines that the current machining path is not connected to the cavity K (step S10: No), it ends the processing in the flowchart and executes the machining in the normal machining path according to the machining program.

[0057] When the current machining path is connected to cavity K (step S10: Yes), the control device 15 measures the height of the machining path using the height measuring device 8 (step S20). If the control device 15 determines, based on the measurement result of the height measuring device 8, that the lower layer of the current machining path is not a cavity (step S30: No), it ends the processing in this flowchart and executes the machining in the normal machining path according to the machining program. If the control device 15 determines, based on the measurement result of the height measuring device 8, that the lower layer of the current machining path is a cavity (step S30: Yes), it skips the current machining path (step S40) and moves the machining point to the next machining path (step S50). Next, the control device 15 measures the height of the machining path using the height measuring device 8 (step S60). If the control device 15 determines, based on the measurement result of the height measuring device 8, that the lower layer of the current machining path is a cavity (step S70: Yes), it skips the machining path (step S40) and moves the machining point to the next machining path (step S50). As described above, machining paths are skipped until it is determined that the lower layer is not a cavity.

[0058] If the control device 15 determines that the lower layer is not a cavity (step S70: No), it performs normal processing if a processing path still exists in that layer; otherwise, it jumps to the next step S90 (step S80). Next, the control device 15 generates the aforementioned intermediate processing path Pcn1 between the processing path Pn that was skipped first and the preceding processing path Pn-1 (step S90), moves the processing point to the position of the generated intermediate processing path Pcn1 (step S100), and performs processing at the position of the intermediate processing path Pcn1 (step S110). Furthermore, when the intermediate processing path Pcn1 is formed, the formation position of the weld bead BDn-1 of the processing path Pn-1 is measured by the height measuring device 8, and the position and weld bead cross-sectional area of ​​the intermediate processing path Pcn1 are determined according to the method of overlapping with the weld bead BDn-1 and the weld bead formed through the processing path Pn+1 by a first overlap amount θ. In addition, the intermediate processing path is generated by the control device 15 via an external computer 16.

[0059] Next, the control device 15 moves the processing point to the position of the next processing path Pn+1 (step S120). Furthermore, the control device 15 generates an intermediate processing path Pcn2 between processing path Pn+1 and an intermediate processing path Pcn1 formed immediately preceding processing path Pn+1 (step S130), moves the processing point to the position of the generated intermediate processing path Pcn2 (step S140), and performs processing at the position of the intermediate processing path Pcn2 (step S150). In addition, during the formation of this intermediate processing path Pcn2, the height measuring device 8 measures the formation position of the weld bead BDcn1 of the intermediate processing path Pcn1, and determines the position and cross-sectional area of ​​the intermediate processing path Pcn2 by overlapping with weld bead BDcn1 and the weld bead formed by processing path Pn+2 by a first overlap amount θ.

[0060] Control device 15 moves the machining path to the position of the next machining path (step S160). Next, control device 15 determines whether the machining in the skipped machining path has ended (step S170). If the machining in the skipped machining path has ended (step S170: Yes), the process in this flowchart ends, and then the next process is executed according to the machining program. If the machining in the skipped machining path has not ended (step S170: No), n is updated to n+1 (step S180), and the process jumps to step S130.

[0061] Next, the control device 15 generates an intermediate machining path Pcn3 between machining path Pn+2 and an intermediate machining path Pcn2 formed immediately preceding machining path Pn+2 (step S130), moves the machining point to the position of the generated intermediate machining path Pcn3 (step S140), performs machining at the position of the intermediate machining path Pcn3 (step S150), and moves the machining path to the position of the next machining path (step S160). The process described above is repeated until the judgment in step S170 becomes Yes.

[0062] Next, use Figure 8 and Figure 9 This describes the overall operation performed by the control device 15. Figure 8 This is a flowchart illustrating a first example of the overall operation flow performed by the control device 15 in the auxiliary manufacturing apparatus 100 according to Embodiment 1. Figure 8 In the flowchart, intermediate processing paths are generated in advance.

[0063] Using an external computer 16's CAD, according to Figure 2 The finished product was created from the design model shown. Figure 3 The model shown is displayed (step S200). Next, using the CAM of the external computer 16, multiple machining paths for realizing the model are created (step S210). Next, a simulation of the machining paths implemented using the CAM of the external computer 16 is performed, and the presence or absence of cavities is detected during the simulation (step S220). If cavities are detected in the model, the aforementioned intermediate machining path is generated using the CAM of the external computer 16 (step S230). Next, using the CAM of the external computer 16, the machining shape and the interference between the machining head 7 and the wire nozzle 4, etc., are confirmed on the CAM (step S240).

[0064] Next, the control device 15 of the auxiliary manufacturing apparatus 100 performs confirmation of interference between the processing head 7 and the wire nozzle 4 on the actual machine (step S250). Next, the control device 15 of the auxiliary manufacturing apparatus 100 actually performs the processing via steps S260 to S280. At this time, as described above, the height is measured by the height measuring device 8 (step S260), the cavity is detected (step S270), and the intermediate processing path generated in step S230 is selected (step S280).

[0065] As mentioned above, in Figure 8In the process, if a cavity is detected during the simulation of the machining path, the aforementioned intermediate machining path is pre-created using a model. If a cavity is detected during actual machining, the pre-created intermediate machining path is used to perform machining. Therefore, depending on the shape and size of the cavity, creating a large intermediate machining path would require a significant amount of computation time and data communication time on the external computer 16. However, this computation time and data communication time can be eliminated, thus shortening the machining time.

[0066] Figure 9 This is a flowchart illustrating a second example of the overall operation flow performed by the control device 15 in the auxiliary manufacturing apparatus 100 according to Embodiment 1. Figure 9 In the flowchart, the intermediate processing paths are formed during actual processing. Figure 9 In the process, steps S200, S210, and S240 to S270 are... Figure 8 The same applies, so repeated descriptions are omitted. In step S225, intermediate machining paths are not created; instead, machining path simulation is performed. If a cavity is detected, in step S285, intermediate machining paths are generated during actual machining.

[0067] As mentioned above, in Figure 9 In the process, intermediate machining paths are created during actual processing. Therefore, intermediate machining paths can be created by measuring the actual machining results using the height measuring device 8, resulting in more accurate intermediate machining paths and reducing machining defects. Furthermore, in situations where it is impossible to... Figure 8 When processing via the pre-created intermediate processing path described in the instructions, it is also possible to use... Figure 9 The method shown creates intermediate processing paths by measuring the actual processing results.

[0068] As described above, according to Embodiment 1, if it is detected that there is no weld bead in the lower layer, the processing path is skipped until a weld bead exists in the lower layer. Then, a weld bead with a larger cross-sectional area than a normal weld bead is formed in the skipped processing path. Therefore, it is possible to prevent the weld bead in the upper part of the cavity from sagging due to the effects of gravity and thermal strain.

[0069] Implementation Method 2

[0070] In Embodiment 1, the cavity shape at the open end is machined, but in Embodiment 2, the cavity shape at the closed end, where the front and rear ends of the cavity in the Y direction are completely sealed, is machined. Furthermore, Embodiment 2 can be applied to shapes where a cavity exists at a location in the Y direction extending from the weld bead BD. The additional manufacturing apparatus 100 of Embodiment 2 has... Figure 1 The additional manufacturing apparatus 100 of Embodiment 1 shown has the same structure. Figure 10 This is a perspective view showing an example of a design model of a finished product formed by the additional manufacturing apparatus 100 according to Embodiment 2. The design model is in the shape of a closed-end cylindrical tube, which has a cavity K with a circular cross-section at its central portion in the Y direction. Figure 11 This is a cross-sectional view of the model of the finished product formed by the additional manufacturing apparatus 100 according to Embodiment 2. Figure 11 It is through the Y-direction position without cavity K, i.e., the XI-XI line. Figure 10 A cut-off sectional view. Figure 12 It is a cross-sectional view of the model of the finished product formed by the additional manufacturing apparatus 100 according to Embodiment 2. Figure 12 It is through the Y-direction position of the cavity K, i.e., the XII-XII line. Figure 10 A sectional view after cutting. Figure 11 Cavity K was not present, but... Figure 12 A cavity K appeared in it.

[0071] exist Figure 11 and Figure 12 In this context, the focus is on the N-layer weld bead BDq with thick lines. For example... Figure 11 As shown, regarding this weld bead BDq, it does not connect with the cavity K at the closed end in the Y direction, but as... Figure 12 As shown, in the central part of the Y direction, at the lower part of weld bead BDq, it connects with cavity K. The XZ position of weld bead BDq in layer N is related to... Figure 5 The XZ position of the weld bead formed in the processing path Pn corresponds to the position of the weld bead.

[0072] Figure 13 It is a sectional view showing the modeling method in a proportional representation. Figure 13 In the middle, along the XZ plane Figure 11 , Figure 12 The N-layer cutting of the shaping model. Figure 13 In the diagram, Lb represents the length of a single weld bead in the Y direction. Figure 13 In the comparative example shown, weld bead BDq is formed by a weld bead of length Lb. Therefore, in the method of the comparative example, the weld bead BDq is more likely to break down and sag in the central part of the Y direction where it is connected to the cavity K.

[0073] Figure 14 This is a cross-sectional view showing the shaping method in the additional manufacturing apparatus 100 according to Embodiment 2. Figure 14 In the middle, along the XZ plane Figure 11 , Figure 12The N-layer cutting of the shaping model. In Embodiment 2, if a weld bead formed by one processing path has a portion that connects to the cavity K at the bottom, the weld bead is divided into a first region that connects to the cavity K and a second region that does not connect to the cavity K. Therefore, the processing path for forming weld bead BDq is divided into a processing path for forming weld bead BDq2 that connects to the cavity K and a processing path for forming weld beads BDq1 and BDq3 that do not connect to the cavity K. In Embodiment 2, based on the height measurement result of the height measuring device 8, the processing path for forming weld bead BDq is divided into a processing path for forming weld bead BDq1, a processing path for forming weld bead BDq2, and a processing path for forming weld bead BDq3.

[0074] Figure 15 This is a diagram showing an example of the height measurement result of the height measuring device 8 in the auxiliary manufacturing apparatus 100 according to Embodiment 2. Figure 15 In the diagram, the horizontal axis represents time T, and the vertical axis represents the measured height. Figure 15 For example, the result of the height measuring device 8 measuring the machining path used to form weld bead BDq along the Y direction is shown. In the region of the machining path used to form weld bead BDq2, the height measurement result is smaller compared to other regions, indicating the presence of cavity K.

[0075] In the area where a portion of the cavity K is detected by the height measuring device 8, the intermediate processing path Pcn1 described in Embodiment 1 is introduced. In Embodiment 2, within the same weld bead BDq, the processing path for forming weld bead BDq2 is separated. Therefore, only for the processing path for forming weld bead BDq2, as described above, by changing the processing conditions including the laser output of the laser oscillator 11, the wire supply speed of the wire feeder 5, and the XY axis movement speed generated by the processing head drive device 50, processing in the intermediate processing path Pcn1 with the changed weld bead cross-sectional area can be performed.

[0076] like Figure 15 As shown, regarding the region where cavity K is detected, the region can be identified, for example, by recording the program number of the machining program. The program number corresponds to the coordinate in the Y direction. When the region where cavity K is detected corresponds to program number N10 to program number N20, in the newly selected machining path, only program numbers N10 to N20 out of program numbers N1 to N30 are changed to be machined through the intermediate machining path Pcn1. Thus, even if a weld bead connects to cavity K in the middle, by splitting the machining path, machining through the optimal intermediate machining path can be performed.

[0077] As described above, according to Embodiment 2, when a cavity K exists in a portion of the weld bead layer in the Y direction, the processing path extending in the Y direction is divided into a first region with cavity K and a second region without cavity. In the processing path corresponding to the first region, an intermediate processing path with the aforementioned weld bead cross-sectional area modified is introduced. Therefore, even when a cavity K exists in a portion of the weld bead layer in the Y direction, the sag of the weld bead above the cavity caused by the influence of gravity and thermal strain can be prevented.

[0078] The structure shown in the above embodiments is an example of the content of the present invention. It can also be combined with other known technologies, and the embodiments can be combined with each other. Without departing from the spirit of the present invention, some parts of the structure can be omitted or changed.

[0079] Explanation of the label

[0080] 1. Shape, 2. Substrate, 3. Wire, 4. Wire nozzle, 5. Wire feeder, 7. Processing head, 8. Height measuring device, 9. Workpiece, 10. Optical cable, 11. Laser oscillator, 13. Processing point, 14. Gas nozzle, 15. Control device, 16. External computer, 20. Gas supply device, 30. Wire supply device, 40. Worktable, 50. Processing head drive device, 100. Add-on manufacturing device, BD. Weld bead, K. Cavity, L. Laser beam, Pcn, Pcn1, Pcn2, Pcn3. Intermediate processing paths.

Claims

1. An additive manufacturing method wherein a processing point is moved along a plurality of processing paths extending in a first direction to form a weld bead layer consisting of a plurality of first weld beads of first cross-sectional areas arranged in a second direction perpendicular to the first direction, and the weld bead layer is stacked in a third direction perpendicular to both the first and second directions to form an accumulation of the weld bead layers, i.e., a 3D shape having cavities. This additional manufacturing method is characterized by having: In the inspection process, when the weld layer is formed, the presence of the first weld bead in the lower layer is checked for each processing path. Skip the process, and skip the first processing path (the first processing path) in the processing paths arranged in the second direction from the first processing path (the first processing path) where the first weld bead is not detected in the lower layer to the last processing path (the second processing path) where the first weld bead is not detected in the lower layer. In the second weld bead formation process, a second weld bead with a second cross-sectional area is formed in the corrected first processing path after the position of the first processing path has been corrected; and The third weld bead forming process forms the first weld bead or the third weld bead having the third cross-sectional area in the processing path from the next processing path after the corrected first processing path to the second processing path.

2. The additive manufacturing method according to claim 1, characterized in that, The second cross-sectional area is larger than the first cross-sectional area, and the third cross-sectional area is larger than the first cross-sectional area.

3. The additional manufacturing method according to claim 1 or 2, characterized in that, In the second weld bead forming process, the position of the formed first weld bead formed through the third processing path (the processing path preceding the first processing path) on the surface including the second and third directions is detected. The first processing path is corrected to form the second weld bead in such a way that the second weld bead overlaps with the formed first weld bead formed through the third processing path and the first weld bead formed through the next processing path of the first processing path by a first overlap amount.

4. The additional manufacturing method according to any one of claims 1 to 3, characterized in that, If the cavity exists in a portion of the first direction of the weld bead layer, the processing path extending in the first direction is divided into a first region where the cavity exists and a second region where the cavity does not exist. The inspection process, the skipping process, the second weld bead forming process, and the third weld bead forming process are performed through the processing path corresponding to the first region.

5. The additional manufacturing method according to any one of claims 1 to 4, characterized in that, The corrected first processing path was created during simulation using a model.

6. The additional manufacturing method according to any one of claims 1 to 4, characterized in that, The corrected first processing path is created during processing.

7. An auxiliary manufacturing apparatus that moves a processing point along a plurality of processing paths extending in a first direction to form a weld bead layer consisting of a plurality of first weld beads of first cross-sectional areas arranged in a second direction perpendicular to the first direction, and forms a deposit of the weld bead layer, i.e., a three-dimensional cavity-shaped object, by stacking the weld bead layer in a third direction perpendicular to both the first and second directions. The additional manufacturing apparatus is characterized by having: The detection device, during the formation of the weld layer, detects the presence of the first weld bead in the underlying layer for each processing path; and The control device skips the processing in the processing paths arranged in the second direction from the first processing path (i.e., the first processing path) where the first weld bead is detected not to exist in the lower layer to the last processing path (i.e., the second processing path) where the first weld bead is detected not to exist in the lower layer. In the corrected first processing path (i.e., the position of the first processing path has been corrected), a second weld bead with a second cross-sectional area is formed. In the processing path from the next processing path of the corrected first processing path to the second processing path, the first weld bead or a third weld bead with a third cross-sectional area is formed.

8. The additional manufacturing apparatus according to claim 7, characterized in that, The second cross-sectional area is larger than the first cross-sectional area, and the third cross-sectional area is larger than the first cross-sectional area.

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