Void visualization method

Abstract

This invention provides a void visualization method that allows for direct, three-dimensional identification of voids within a component under inspection. [Solution] In the CT scan step S1 of the void visualization method, an internal image of the part to be inspected, manufactured by metal die casting or resin molding, is captured by an X-ray CT scanner. In the data transmission step S2, the X-ray CT scanner transmits STL data showing the shape of the part to be inspected, as well as STL data showing the location and size of the voids in the part to be inspected, to a 3D printer. In the molding step S3, based on the received STL data, the 3D printer fills the base corresponding to the material parts other than the voids of the part to be inspected with a transparent model material, and fills the void visualization part corresponding to the voids of the part to be inspected with a colored support material to create a three-dimensional object. In the inspection step S5, the quality of the part to be inspected is inspected based on the location and size of the void visualization part of the three-dimensional object.

Description

【Technical Field】 【0001】 The present invention relates to a method for visualizing voids generated during the manufacture of metal die-cast parts, resin molded parts, and the like. 【Background Art】 【0002】 Conventionally, a method of inspecting internal defects (voids) using an X-ray CT scanner has been known. For example, Patent Document 1 discloses a method for detecting internal defects of an aluminum die-cast part based on an image of X-ray CT. 【0003】 Further, in the casting internal defect inspection support device disclosed in Patent Document 2, the display image forming means forms a display image in which the three-dimensional shape model of the casting is made translucent and the portion corresponding to the cavity is emphasized in a color different from that of the three-dimensional model, and displays it on the display device. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2013-88310 【Patent Document 2】 Japanese Patent Application Laid-Open No. 2004-34144 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 Since the image used in the method of Patent Document 1 is a black-and-white image, it is difficult to grasp the three-dimensional position and size of internal defects, and skilled skills are required for quality inspection. Further, since a plurality of cross-sectional photographs are output for one sample, data management becomes complicated. Furthermore, depending on the cross-sectional pitch of the X-ray CT scan, there is a possibility of underestimating large voids or overlooking small voids. 【0006】 Patent Document 2 states that the inspection support device makes it easier to inspect the condition of internal defects, but the display image of the display device is not disclosed in drawings or other documents, so it is unclear to what extent it actually makes the inspection easier. Furthermore, the user can only visually confirm the image of the three-dimensional model displayed on the display device, and cannot directly grasp the location or size of the internal defects in three dimensions. 【0007】 This invention was created in view of these points, and its purpose is to provide a void visualization method that can directly grasp voids inside a part to be inspected in three dimensions. [Means for solving the problem] 【0008】 The void visualization method according to the present invention includes a CT scan step (S1), a data transmission step (S2), a molding step (S3), and an inspection step (S5). In the CT scan step, an internal image of the part to be inspected (10), manufactured by metal die casting or resin molding, is captured by an X-ray CT scanner (5). 【0009】 In the data transmission step, the X-ray CT scanner transmits STL data to the 3D printer (6) that shows the shape of the part to be inspected, as well as the location and size of any voids (18) in the part to be inspected. 【0010】 In the fabrication step, the 3D printer, based on the received STL data, fills the base (23) corresponding to the material parts (13) of the part to be inspected, excluding voids, with transparent model material, and fills the void visualization parts (28) corresponding to the voids of the part to be inspected with colored support material to fabricate a three-dimensional object (20). In the inspection step, the quality of the part to be inspected is checked based on the position and size of the void visualization parts of the three-dimensional object. 【0011】 In this invention, in a 3D printed object, the void visualization area is filled with, for example, a milky white support material against a transparent base, making it easily recognizable visually. Moreover, inspectors can not only view the 3D image displayed on a display device, but also directly grasp the position and size of the voids in 3D by touching the real 3D printed object. Therefore, quality inspection of the parts to be inspected can be easily performed. 【0012】 The void visualization method of the present invention may further include a coloring step (S4) in which, after the molding step, the three-dimensional object is impregnated with a coloring liquid (7) and the void visualization portion exposed on the surface of the three-dimensional object is colored with a different color from the support material. This makes it possible to visualize voids in contact with the surface of the part to be inspected more clearly. 【0013】 Furthermore, the void visualization method of the present invention may be used not only for visual inspection by an inspection worker, but also for inspection using an image recognition device (8). In the inspection step, the image recognition device compares the image of the void visualization section recognized by the image recognition device with a pre-stored or learned inspection standard image to determine whether the part to be inspected is a good product or a defective product. This eliminates variations in judgment by inspection workers and allows for the mechanical identification of defective products based on a uniform standard. [Brief explanation of the drawing] 【0014】 [Figure 1] A block diagram of a system in which a void visualization method according to one embodiment is implemented. [Figure 2] (a) Front view of the part sample to be inspected, (b) Cross-sectional view along line IIb-IIb in Figure 2(a), and (c) Cross-sectional view along line IIc-IIc in Figure 2(b). [Figure 3] A schematic front view of a three-dimensional model sample. [Figure 4] Figure 3(a) is a magnified view of the area around the colored part, and (b) is a view taken along arrow IVb in Figure 4(a). [Figure 5] A flowchart of a void visualization method according to one embodiment. [Modes for carrying out the invention] 【0015】 <One Embodiment> A void visualization method according to one embodiment of the present invention will be described with reference to the drawings. This void visualization method is a method for visualizing voids that occur during the manufacturing of metal die-cast parts, resin molded parts, etc., in order to support quality inspection. In this embodiment, an aluminum die-cast product is assumed as a typical part to be inspected. 【0016】 In Figure 1, voids 18 inside the part 10 to be inspected are schematically shown as white circles. The parts of the part 10 other than the voids 18 are called the material part 13. The void visualization system 9 includes an X-ray CT scanner 5 and a 3D printer 6. The X-ray CT scanner 5 captures an internal image of the part 10 to be inspected and identifies the voids 18 inside the part 10. The X-ray CT scanner 5 transmits STL data to the 3D printer 6 that shows the shape of the part 10, as well as the location and size of the voids 18 in the part 10. 【0017】 The 3D printer 6 fabricates a three-dimensional object 20 based on the received STL data. In the three-dimensional object 20, the part corresponding to the material part 13 of the part to be inspected 10 is called the base part 23, and the part corresponding to the voids 18 is called the void visualization part 28. The 3D printer 6 fills the base part 23 of the three-dimensional object 20 with a transparent model material and fills the void visualization part 28 with a support material, for example, a milky white colored material. The fabricated three-dimensional object 20 may be further impregnated for several hours in a coloring liquid 7 containing a different color from the support material, for example, a black pigment. As a result, the void visualization part 28 exposed on the surface of the three-dimensional object 20 is colored. 【0018】 Based on the position and size of the void visualization part 28 of the three-dimensional shaped object 20, the quality of the inspection target part 10 is inspected by the inspection operator or the image recognition device 8. The image recognition device 8 acquires an image of the void visualization part 28 by means such as a camera. Then, the image recognition device 8 compares the recognized image of the void visualization part 28 with a pre-stored or learned inspection reference image to determine whether the inspection target part 10 is a good product or a defective product. 【0019】 As an example in FIG. 2, the shape of a sample of the inspection target part 10, which is an aluminum die-cast part, is shown. The surface shown in FIG. 2(a) is taken as the front. The sample of the inspection target part 10 has a substantially L-shaped or arc-shaped with a central angle of 90° that is symmetric with respect to the symmetry line M when viewed from the front, and includes a thick part 15 and a thin part 16. As shown in FIGS. 2(a) and 2(c), the thick part 15 consists of an outer curved part 151 forming the outer side of the diameter of the L-shaped curve and an inner column part 152 formed along the symmetry line M inside the diameter of the outer curved part 151. One end of the outer curved part 151 shown on the left side of FIGS. 2(a) and 2(c) is the gate side end 14A where the molten metal is injected, and the other end of the outer curved part 151 shown on the lower side of the figure is the anti-gate side end 14B in front of the flow of the molten metal (arrow F). 【0020】 As shown in FIG. 2(b), the sample of the inspection target part 10 is symmetric with respect to the symmetry line Z in the depth direction. Two pairs of thin parts 16 extending plate-like inward from the edges on the front side and the back side of the outer curved part 151 are provided. On the gate side and the anti-gate side, a concave space with both sides sandwiched by the thin parts 16 is formed. The bottom surface of the concave space is the surface of the outer curved part 151. The boundary between the outer curved part 151 and the inner column part 152 is the in-corner part 17. 【0021】 When a sample of the inspection target part 10 is cast, the molten metal mainly flows from the gate side end 14A toward the counter gate side end 14B through the outer curved part 151, and a part of the molten metal is filled into the inner column part 152 and the thin wall part 16. Voids 18 are more likely to occur in the counter gate side part after the curve than in the gate side part before the curve of the outer curved part 151. Also, on the bottom surface of the concave space on the inner diameter side, the generated voids 18 are likely to contact the surface of the outer curved part 151. In the X-ray CT scanner 5, images of those voids 18 are taken. 【0022】 Fig. 3 schematically shows a sample of the three-dimensional shaped object 20 formed by the 3D printer 6 using the STL data of the sample of the inspection target part 10 generated by the X-ray CT scanner 5. Also, Figs. 4(a) and (b) show enlarged views of samples in which the void visualization parts exposed on the surface of the three-dimensional shaped object 20 are colored with the coloring liquid 7. In this example, after the three-dimensional shaped object 20 was impregnated with the coloring liquid 7 containing a black pigment for several hours, it was washed. The applicant submits color photographs corresponding to Figs. 3, 4(a), and 4(b) to the Patent Office with the submission document. 【0023】 For each part of the three-dimensional shaped object 20, numbers are used in which the first digit of the reference numerals of each part of the inspection target part 10 is replaced from "1" to "2". The base 23 of the three-dimensional shaped object 20 corresponding to the material part 13 of the inspection target part 10 is filled with a model material of a transparent material. The void visualization part  28 of the three-dimensional shaped object 20 corresponding to the void 18 of the inspection target part 10 is filled with a support material of a coloring material (for example, milky white). For those generated in the bulk of the thick wall part 25 of the void visualization part 28, the reference numeral with parentheses "28b" is also noted, and for those generated on the surface of the thick wall part 2 , the reference numeral with parentheses "28s" is also noted. 【0024】 As shown in Figure 3, void visualization areas 28 are not very formed near the gate-side end 24A of the thick-walled section 25. On the other hand, void visualization areas 28b are formed in a continuous line near the center (bulk) of the outer curved section 251, which corresponds to the flow path of the molten metal, from near the symmetry line M to the opposite gate-side end 24B. Some void visualization areas 28b can also be seen near the boundary between the outer curved section 251 and the inner column section 252. In addition, fine void visualization areas 28s are formed scattered near the surface of the outer curved section 251, which corresponds to the bottom surface of the concave space sandwiched between the thin-walled sections 26. 【0025】 As shown in Figure 4(a), a black-colored void visualization area 28s is visible along the gate-side in-corner area 27 (P area). On the opposite gate side in-corner area 27 (Q area), a smaller number of void visualization areas 28s are also visible compared to the gate side. In this way, by coloring the void visualization areas 28s exposed on the surface of the three-dimensional molded object 20 with a different color from the support material, voids 18 in contact with the surface of the part to be inspected 10 can be made more easily visible. 【0026】 Next, a void visualization method according to one embodiment will be described with reference to the flowchart in Figure 5. The symbol "S" in the flowchart represents a step. In the CT scan step S1, an internal image of the part to be inspected 10 is captured by the X-ray CT scanner 5. In the data transmission step S2, the X-ray CT scanner 5 transmits STL data to the 3D printer 6 that shows the shape of the part to be inspected 10, as well as the location and size of the voids 18 in the part to be inspected 10. 【0027】 In the S3 fabrication step, the 3D printer 6 fabricates a three-dimensional object 20 based on the received STL data. This three-dimensional object 20 has a base 23 corresponding to the material parts 13 of the part to be inspected 10 other than the voids 18, filled with a transparent model material, and a void visualization part 28 corresponding to the voids 18 of the part to be inspected 10, filled with a colored support material. 【0028】 After the molding step S3, in the coloring step S4, the three-dimensional object 20 is impregnated with a coloring liquid 7, and the void visualization areas 28 exposed on the surface of the three-dimensional object 20 are colored with a different color from the support material. Note that the coloring step S4 is not a mandatory step but an optional step, so it is represented by a dashed line. In the inspection step S5, the quality of the part to be inspected 10 is inspected by an inspector or an image recognition device 8 based on the position and size of the void visualization areas 28 of the three-dimensional object 20. 【0029】 In this embodiment, in the three-dimensional object 20 produced by the 3D printer 6, the void visualization section 28 is filled with, for example, a milky white support material relative to the transparent base 23, making it easily recognizable visually. Moreover, the inspector can not only view the three-dimensional image displayed on the display device, but also directly grasp the position and size of the voids in three dimensions by touching the real three-dimensional object 20. Therefore, quality inspection of the part 10 to be inspected can be easily performed. 【0030】 Furthermore, by using the image recognition device 8 in inspection step S5, variations in judgment by inspection workers can be eliminated, and defective products can be mechanically identified based on a uniform standard. 【0031】 <Other Embodiments> The inspection method is not limited to aluminum die-cast parts; it can also be applied to parts manufactured using metal die-casting (such as magnesium or zinc) or resin molding. 【0032】 The present invention is not limited in any way to the embodiments described above, and can be implemented in various forms without departing from its spirit. [Explanation of symbols] 【0033】 10...Parts to be inspected, 13...Material parts, 18...Voids, 20... Three-dimensional molded object, 23... Base, 28... Void visualization section, 5. X-ray CT scanner, 6. 3D printer, 7. Coloring liquid; 8. Image recognition device.

Claims

[Claim 1] A CT scan step (S1) is performed in which an internal image of the part to be inspected (10), manufactured by metal die casting or resin molding, is captured by an X-ray CT scanner (5), The X-ray CT scanner transmits STL data to the 3D printer (6) that, in addition to the shape of the part to be inspected, indicates the position and size of the voids (18) of the part to be inspected, in a data transmission step (S2). The 3D printer, based on the received STL data, performs a fabrication step (S3) in which it fills the base portion (23) corresponding to the material portion (13) of the part to be inspected, excluding the voids, with a transparent model material, and fills the void visualization portion (28) corresponding to the voids of the part to be inspected with a colored support material to fabricate a three-dimensional object (20). An inspection step (S5) is performed in which the quality of the part to be inspected is inspected based on the position and size of the void visualization portion of the three-dimensional molded object, A void visualization method that includes this. [Claim 2] The void visualization method according to claim 1, further comprising a coloring step (S4) after the molding step, in which the three-dimensional molded object is impregnated with a coloring liquid (7), and the void visualization portion (28s) exposed on the surface of the three-dimensional molded object is colored with a color different from that of the support material. [Claim 3] Used in an inspection method using an image recognition device (8), The void visualization method according to claim 1 or 2, wherein in the inspection step, the image recognition device compares the image of the void visualization unit recognized with a pre-stored or learned inspection reference image to determine whether the part to be inspected is a good product or a defective product.

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