Void Visualization Method

Abstract

A void visualization method is provided that enables direct three-dimensional understanding of voids inside an inspection target part. [Solution] In the CT scan step S1 of the void visualization method, an internal image of an inspection target part 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 indicating the shape of the inspection target part as well as STL data indicating the position and size of voids in the inspection target part to a 3D printer. In the modeling step S3, the 3D printer fills a base part corresponding to the material part other than the voids of the inspection target part with a transparent model material based on the received STL data, and fills a void visualization part corresponding to the voids of the inspection target part with a colored support material to form a three-dimensional object. In the inspection step S5, the quality of the inspection target part is inspected based on the position 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 that occur during the production of metal die-cast parts, resin molded parts, and the like. [Background technology]

[0002] Conventionally, there has been known a method for inspecting internal defects (voids) using an X-ray CT scanner. For example, Patent Document 1 discloses a method for detecting internal defects in aluminum die-cast parts based on X-ray CT images.

[0003] Furthermore, 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 semi-transparent and parts corresponding to cavities are highlighted in a color different from that of the three-dimensional model, and displays the display image on the display device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-88310 A [Patent Document 2] JP 2004-34144 A Summary of the Invention [Problem to be solved by the invention]

[0005] The images used in the method of Patent Document 1 are black and white images, making it difficult to grasp the position and size of internal defects in three dimensions, and quality inspection requires skilled techniques. In addition, multiple cross-sectional photographs are output for one sample, making data management cumbersome. Furthermore, depending on the cross-sectional pitch of the X-ray CT scan, there is a possibility that large voids may be underestimated or small voids may be overlooked.

[0006] Patent Document 2 describes that the inspection support device makes it easier to inspect the state of internal defects, but does not disclose the image displayed on the display device in drawings or the like, so it is unclear to what extent it actually makes the inspection easier. In addition, the user can only visually confirm the image of the three-dimensional model displayed on the display device, and cannot directly grasp the position and size of the internal defects in three dimensions.

[0007] The present invention has been created in view of the above points, and its object is to provide a void visualization method that can directly grasp voids inside an inspection target component in three dimensions. [Means for solving the problem]

[0008] The void visualization method according to the present invention includes a CT scanning step (S1), a data transmission step (S2), a modeling step (S3), and an inspection step (S5). In the CT scanning step, an internal image of an inspection target part (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 indicating the shape of the inspected part as well as the position and size of the voids (18) in the inspected part to the 3D printer (6).

[0010] In the modeling step, the 3D printer fills a base portion (23) corresponding to the material portion (13) other than the voids of the inspection target part with a transparent model material based on the received STL data, and fills a void visualization portion (28) corresponding to the voids of the inspection target part with a colored support material, thereby modeling a three-dimensional object (20). In the inspection step, the quality of the inspection target part is inspected based on the position and size of the void visualization portion of the three-dimensional object.

[0011] In the present invention, in the three-dimensional object produced by the 3D printer, the void visualization portion is filled with, for example, a milky white support material in contrast to the transparent base portion, so that it can be easily recognized visually. Moreover, the inspector can directly grasp the position and size of the void in three dimensions while touching the real three-dimensional object, rather than just looking at the three-dimensional image displayed on the display device. Therefore, the 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) of immersing the three-dimensional object in a coloring liquid (7) after the modeling step, and coloring the void visualization portion exposed on the surface of the three-dimensional object in a color different from that of the support material. This makes it possible to more easily visualize voids in contact with the surface of the inspection target part.

[0013] Furthermore, the void visualization method of the present invention is not limited to visual inspection by an inspection operator, but may be used in an inspection method using an image recognition device (8). In the inspection step, the image recognition device compares the image of the void visualization portion recognized by the image recognition device with a previously stored or learned inspection reference image, and judges whether the inspected part is good or defective. This eliminates the variation in judgment by the inspection operator, and enables mechanical judgment of defective products based on uniform standards. [Brief description of the drawings]

[0014] [Figure 1] 1 is a block diagram of a system in which a void visualization method is implemented according to one embodiment. [Diagram 2] (a) Front view of the inspected part sample, (b) cross-sectional view taken along line IIb-IIb in Figure 2(a), and (c) cross-sectional view taken along line IIc-IIc in Figure 2(b). [Diagram 3] FIG. 4 is a schematic front view of a three-dimensional object sample. [Figure 4] FIG. 3(a) is an enlarged view of the colored portion and its surroundings, and FIG. 3(b) is a view taken along arrow IVb in FIG. 4(a). [Diagram 5] 1 is a flow chart of a void visualization method according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] <One embodiment> A void visualization method according to an 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 manufacture of metal die-cast parts, resin molded parts, etc., to support quality inspection. In this embodiment, an aluminum die-cast product is assumed as a typical part to be inspected.

[0016] In Fig. 1, voids 18 inside the inspection target part 10 are shown diagrammatically by white circles. Portions of the inspection target part 10 other than the voids 18 are referred to as a material portion 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 inspection target part 10 and identifies the voids 18 inside the inspection target part 10. The X-ray CT scanner 5 transmits STL data indicating the shape of the inspection target part 10 as well as the positions and sizes of the voids 18 in the inspection target part 10 to the 3D printer 6.

[0017] The 3D printer 6 models a three-dimensional object 20 based on the received STL data. In the three-dimensional object 20, a portion corresponding to the material portion 13 of the inspection target part 10 is called a base portion 23, and a portion corresponding to the void 18 is called a void visualization portion 28. The 3D printer 6 fills the base portion 23 of the three-dimensional object 20 with a transparent model material, and fills the void visualization portion 28 with a support material of a milky white coloring material, for example. The modeled three-dimensional object 20 may be further immersed in a coloring liquid 7 containing a pigment of a color different from that of the support material, for example, black, for several hours. As a result, the void visualization portion 28 exposed on the surface of the three-dimensional object 20 is colored.

[0018] The quality of the inspection target part 10 is inspected by an inspection operator or an image recognition device 8 based on the position and size of the void visualization portion 28 of the three-dimensional object 20. The image recognition device 8 acquires an image of the void visualization portion 28 by means of a camera or the like. The image recognition device 8 then compares the image of the void visualization portion 28 that has been recognized with a pre-stored or learned inspection reference image, and determines whether the inspection target part 10 is a pass or fail product.

[0019] FIG. 2 shows an example of the shape of a sample of an inspection target part 10, which is an aluminum die-cast part. The surface shown in FIG. 2(a) is the front. The shape of the sample of the inspection target part 10 when viewed from the front is a substantially L-shape symmetrical with respect to a line of symmetry M, or a circular arc shape with a central angle of 90°, and includes a thick-walled part 15 and a thin-walled part 16. As shown in FIG. 2(a) and (c), the thick-walled part 15 is composed of an outer curved part 151 forming a radially outer part of the L-shaped curve, and an inner pillar part 152 formed along the line of symmetry M on the radially inner side of the outer curved part 151. One end of the outer curved part 151 shown on the left side of FIG. 2(a) and (c) is the gate side end part 14A into which molten metal is poured, and the other end of the outer curved part 151 shown on the lower side of the same figure is the anti-gate side end part 14B which is in front of the flow of molten metal (arrow F).

[0020] As shown in Fig. 2(b), the sample of the inspection target part 10 is symmetrical with respect to the line of symmetry Z in the depth direction. Two pairs of thin-walled portions 16 are provided extending radially inward from the edges of the front and back sides of the outer curved portion 151 in a plate-like shape. On the gate side and anti-gate side, a concave space is formed with both sides sandwiched between the thin-walled portions 16. The bottom surface of the concave space is the surface of the outer curved portion 151. The boundary between the outer curved portion 151 and the inner pillar portion 152 is an in-corner portion 17.

[0021] When a sample of the inspection target part 10 is cast, the molten metal mainly flows through the outer curved portion 151 from the gate side end 14A toward the anti-gate side end 14B, and a part of the molten metal fills the inner column portion 152 and the thin wall portion 16. Voids 18 are more likely to occur in the anti-gate side portion after the curve than in the gate side portion before the curve of the outer curved portion 151. Also, the generated voids 18 are more likely to come into contact with the surface of the outer curved portion 151 at the bottom surface of the radially inner concave space. The X-ray CT scanner 5 captures images of those voids 18.

[0022] FIG. 3 shows a schematic diagram of a sample three-dimensional object 20 formed by a 3D printer 6 using STL data of a sample of an inspection target part 10 generated by an X-ray CT scanner 5. Also, FIGS. 4(a) and (b) show enlarged views of a sample in which a void visualization portion exposed on the surface of the three-dimensional object 20 is colored with a coloring liquid 7. In this example, the three-dimensional object 20 is immersed in the coloring liquid 7 containing a black pigment for several hours and then washed. The applicant will submit color photographs corresponding to FIGS. 3, 4(a) and (b) to the Japan Patent Office by means of a document submission form.

[0023] The reference numerals for each part of the three-dimensional object 20 are the same as those for each part of the inspection target part 10, with the first digit replaced from "1" to "2". The base 23 of the three-dimensional object 20, which corresponds to the material part 13 of the inspection target part 10, is filled with a transparent model material. The void visualization parts 28 of the three-dimensional object 20, which correspond to the voids 18 of the inspection target part 10, are filled with a colored support material (e.g., milky white). The void visualization parts 28 generated in the bulk of the thick part 25 are indicated with the reference numeral "28b" in parentheses, and the void visualization parts 28 generated on the surface of the thick part 25 are indicated with the reference numeral "28s" in parentheses.

[0024] As shown in Fig. 3, few void visualization portions 28 are generated near the gate side end 24A of the thick-walled portion 25. Meanwhile, a series of void visualization portions 28b are generated near the center (bulk) of the outer curved portion 251 corresponding to the flow path of the molten metal from near the symmetry line M to the anti-gate side end 24B. Some void visualization portions 28b are also observed near the boundary between the outer curved portion 251 and the inner column portion 252. In addition, fine void visualization portions 28s are generated so as to be scattered near the surface of the outer curved portion 251 corresponding to the bottom surface of the recessed space sandwiched between the thin-walled portions 26.

[0025] As shown in Fig. 4(a), a void visualization portion 28s colored black appears along the in-corner portion 27 (portion P) on the gate side. Although there are fewer void visualization portions 28s in the in-corner portion 27 (portion Q) on the anti-gate side compared to the gate side, the void visualization portions 28s still appear. In this way, by coloring the void visualization portions 28s exposed on the surface of the three-dimensional object 20 a color different from the color of the support material, the voids 18 in contact with the surface of the inspection target part 10 can be more easily visualized.

[0026] Next, a void visualization method according to one embodiment will be described with reference to the flowchart of Fig. 5. The symbol "S" in the flowchart denotes a step. In a CT scan step of S1, an internal image of the inspection target part 10 is captured by the X-ray CT scanner 5. In a data transmission step of S2, the X-ray CT scanner 5 transmits STL data indicating the shape of the inspection target part 10 as well as the positions and sizes of voids 18 in the inspection target part 10 to the 3D printer 6.

[0027] In the modeling step S3, the 3D printer 6 models a three-dimensional object 20 based on the received STL data. This three-dimensional object 20 is obtained by filling a base 23 corresponding to the material portion 13 other than the voids 18 of the inspection target part 10 with a transparent model material, and filling a void visualization portion 28 corresponding to the voids 18 of the inspection target part 10 with a support material of a colored material.

[0028] After the modeling step S3, in a coloring step S4, the three-dimensional object 20 is immersed in a coloring liquid 7, and the void visualization portions 28 exposed on the surface of the three-dimensional object 20 are colored a color different from that of the support material. Note that the coloring step S4 is represented by a dashed line because it is not a required step and can be performed as an option. In an inspection step S5, an inspection operator or an image recognition device 8 inspects the quality of the inspection target part 10 based on the position and size of the void visualization portions 28 of the three-dimensional object 20.

[0029] In this embodiment, in the three-dimensional model 20 of the 3D printer 6, the void visualization portion 28 is filled with, for example, a milky white support material, while the base portion 23 is transparent, so that the void visualization portion 28 can be easily recognized visually. Moreover, the inspector can directly grasp the position and size of the void in three dimensions while touching the real three-dimensional model 20, rather than just looking at the three-dimensional image displayed on the display device. Therefore, the quality inspection of the inspection target part 10 can be easily performed.

[0030] Furthermore, by using the image recognition device 8 in the inspection step S5, it is possible to eliminate variations in judgment among inspectors and to mechanically determine whether a product is defective based on a uniform standard.

[0031] <Other embodiments> The parts to be inspected are not limited to aluminum die-cast products, but can also be parts manufactured by metal die-casting such as magnesium or zinc, or by resin molding.

[0032] As described above, the present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the present invention. [Explanation of symbols]

[0033] 10... Inspection target part, 13... Material part, 18... Void, 20...3D object, 23...base, 28...void visualization part, 5. X-ray CT scanner, 6. 3D printer, 7···Coloring liquid, 8···Image recognition device.

Claims

1. A CT scanning step (S1) in which an internal image of an inspection target part (10) manufactured by metal die casting or resin molding is captured by an X-ray CT scanner (5); A data transmission step (S2) in which the X-ray CT scanner transmits STL data indicating the shape of the inspection target part as well as the position and size of the void (18) of the inspection target part to the 3D printer (6); A modeling step (S3) in which the 3D printer fills a base (23) corresponding to a material portion (13) other than the void of the inspection target part with a transparent model material based on the received STL data, and fills a void visualization portion (28) corresponding to the void of the inspection target part with a support material of a coloring material to form a three-dimensional object (20); an inspection step (S5) of inspecting quality of the inspection target part based on the position and size of the void visualization portion of the three-dimensional object; A void visualization method comprising:

2. The void visualization method according to claim 1, further comprising a coloring step (S4) of, after the modeling step, immersing the three-dimensional object in a coloring liquid (7) and coloring the void visualization portion (28s) exposed on the surface of the three-dimensional object in a color different from that of the supporting material.

3. It is used in an inspection method using an image recognition device (8), 3. 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 portion that has been image-recognized with a pre-stored or learned inspection reference image, and determines whether the inspected part is good or defective.

Images