Surface flaw inspection method

Abstract

To provide a surface flaw inspection method that can accurately detect a white flaw.SOLUTION: A surface flaw inspection method includes: extracting a black, long and narrow defect candidate area from an inspection image (S102); creating rectangular areas respectively on both ends of the black, long and narrow defect candidate area (S104); extracting a white defect candidate area from an inspection image of the rectangular areas (S106); and detecting a white defect on the basis of the size of the white defect candidate area (S109, S110).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for inspecting surface flaws. [Background technology]

[0002] Patent Document 1 describes an inspection device for surface flaws that detects white flaws present around black flaws. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-124524 Summary of the Invention [Problem to be solved by the invention]

[0004] Black (deep) elongated scratches often have white (shallow) scratches at the ends, but Patent Document 1 had the problem of not having a specific method for detecting white scratches within the end region of an elongated scratch. [Means for solving the problem]

[0005] In one embodiment, a surface flaw inspection method detects white flaws in an area formed at the end of a black, elongated flaw. I tried to do that. [Effects of the Invention]

[0006] According to the surface flaw inspection method of the present disclosure, white flaws can be detected with high accuracy. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a flowchart showing an example of a method for inspecting surface scratches according to the present embodiment. [Figure 2] 10A and 10B are diagrams showing an example of image processing of a surface flaw in the surface flaw inspection method according to the present embodiment. [Figure 3]10A and 10B are diagrams showing an example of image processing of a surface flaw in the surface flaw inspection method according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] This embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a flowchart showing an example of a method for inspecting surface scratches according to this embodiment. Fig. 2 is a diagram showing an example of image processing of surface scratches.

[0009] First, in step S101, an inspection image is input to the inspection device. An example of the input image is shown in Fig. 2a. Then, the process proceeds to step S102. Here, the inspection device has a computing device that analyzes the image.

[0010] Next, in step S102, the inspection image is binarized. Then, defect candidate areas are extracted from the binarized inspection image. An example of the extracted image is shown in FIG. 2b. In FIG. 2b, the defect candidate areas are areas b1 and b2. Then, the process proceeds to step S103. Note that areas b1 and b2 are also used in image processing in step S107.

[0011] In step S103, the size of the candidate defect area is obtained from the candidate defect area, and the process proceeds to step S104.

[0012] In step S104, rectangular areas are created at both ends of the candidate area for the black, elongated defect. An example of an image of the rectangular areas is shown in Fig. 2c. The rectangular areas are areas c11, c12, c21, and c22. Then, the process proceeds to step S105.

[0013] In step S105, the inspection image is cut into rectangular areas. An example of the inspection image cut into rectangular areas is shown in Fig. 2d. The inspection images cut into rectangular areas are d11, d12, d21, and d22. Then, the process proceeds to step S106.

[0014] In step S106, the inspection image cut out into a rectangular area is binarized. Then, white defect candidate areas are extracted from the binarized inspection image. An example of the extracted image is shown in FIG. 2e. The white defect candidate areas are areas e1 and e2. Then, the process proceeds to step S107.

[0015] In step S107, the image extracted in step S102 (image of black, elongated defect candidate areas) and the image extracted in step S106 (image of white defect candidate areas) are combined. An example of the extracted image is shown in FIG. 2f. The white defect candidate areas are areas f1 and f2. Then, the process proceeds to step S108.

[0016] In step S108, size information of areas f1 and f2 shown in f in Fig. 2 is acquired, and the process then proceeds to step S109.

[0017] In step S109, it is determined whether the widths of regions f1 and f2 are greater than a specified size. If the widths of the regions are greater than the specified size, the process proceeds to step S110. If the widths of the regions are equal to or less than the specified size, the regions are determined not to be defective, and the process ends.

[0018] In step S110, it is determined whether the lengths of regions f1 and f2 are greater than a specified size. If the lengths of the regions are greater than the specified size, the region is determined to be defective and the process ends. If the lengths of the regions are equal to or less than the specified size, the region is determined not to be defective and the process ends.

[0019] The inspection for surface flaws is carried out through the above processing. Next, steps S103 and S104 will be described in detail. Fig. 3 is a diagram showing an example of image processing for surface flaws in the surface flaw inspection method according to this embodiment.

[0020] The rectangular area of step S104 is created by sequentially executing the following processes corresponding to a to g in FIG. a: The length (l) of the black, elongated defect (L) is calculated by dividing it into thirds. b: The black, elongated defect area is approximated as a rectangle, and the angle (θ), the length of the long side (m), and the center of gravity coordinate (p) are obtained. ⇒ Using trigonometry, calculate the two points on either end of the black, elongated defect (p1, p2) c: Using the coordinates of p1 and p2 obtained in b, the angle (θ), the long side, and the length (l) of the three divisions calculated in a, create rectangular areas at both ends of the black elongated area. d: Extract only the black, elongated area within the rectangle created in c and obtain the center of gravity coordinates (p3, p4) ⇒ Calculate the direction of increase of the long side from the two points (p1, p2) calculated in b and the center of gravity coordinates (p3, p4) of the black, elongated defect area e: Approximate the extracted black elongated area of d to a rectangle, and obtain the angle (θ1, θ2) and the length of the long side (n1, n2). f: Using the angle (θ1, θ2) and the length of the long side (n1, n2) obtained in e, calculate two points p3' and p4', and create an area in the increasing direction calculated in d. g: Combine the areas of e and f

[0021] According to the surface scratch inspection method of this embodiment, black (deep) elongated scratches often have white (shallow) scratches at their ends, so by detecting the scratches in the area formed at the ends, white scratches can be detected with high accuracy.

[0022] The present invention is not limited to the above-described embodiments and can be modified as appropriate without departing from the spirit and scope of the present invention. For example, each process shown in the drawings as a flowchart for performing various processes can be implemented in hardware using a CPU, memory, and other circuits, and in software using a program loaded into memory. Therefore, those skilled in the art will understand that these functional blocks can be implemented in various forms using hardware, software, or a combination thereof, and the present invention is not limited to any of these.

[0023] The above-described program can be stored in and supplied to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible recording media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (Random Access Memory)). The program can also be supplied to a computer by various types of temporary computer-readable media. Examples of temporary computer-readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable media can be supplied to a computer via a wired communication path such as an electric wire or optical fiber, or via a wireless communication path.

Claims

[Claim 1] Extract black, elongated defect candidate areas from the inspection image, creating rectangular areas at both ends of the black, elongated defect candidate area; extracting a white defect candidate region from the inspection image of the rectangular region; A surface flaw inspection method for detecting white defects based on the size of the white defect candidate region.

Images