Surface inspection device and surface inspection method

Abstract

To enable a surface inspection over the entire section of a side peripheral face of a long inspected object with a simple configuration.SOLUTION: A surface inspection device includes: a pattern display member 1 having a planar section 1b in which a predetermined bright and dark pattern 4 is displayed; a through hole 1a penetrating the pattern display member 1 in a vertical direction to the planar section 1b; a drive unit 2 for relatively moving an inspected object W in a vertical direction to the plane section 1b and passing it through the through hole 1a; a camera 3 for imaging the bright and dark pattern 4 projected to a surface Wa of the inspected object W projecting from the through hole to the plane section side; and a calculation device 5 for calculating the shape of a surface Wa of an inspected object on the basis of a bright and dark pattern image 4A captured by the camera 3.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a surface inspection apparatus and a surface inspection method for inspecting the surface of an object to be inspected. [Background technology]

[0002] A conventional method is known, as shown in Patent Document 1, for example, in which an inspection plate (pattern display member) on which a striped pattern of a fixed pitch is recorded is moved relatively in a direction parallel to the surface of an object to be inspected, while a camera captures an image of the striped pattern of the inspection plate reflected on the surface of the object to be inspected, and distortions and scratches on the surface of the object to be inspected are inspected from the shape of the striped pattern in the captured image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 61-223605 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the object to be inspected is, for example, a long rectangular or cylindrical material, and one wishes to inspect the entire side surface using this method, a complex setup is required in which the inspection plate and camera are moved along the longitudinal direction of the object to be inspected while being rotated.

[0005] The present invention has been made in consideration of these problems, and its main object is to enable surface inspection of the entire side peripheral surface of a long-sized inspection object with a simple configuration. [Means for solving the problem]

[0006] That is, the surface inspection apparatus of the present invention comprises a pattern display member having a planar portion on which a predetermined light and dark pattern is displayed, a through hole that passes through the pattern display member in a direction perpendicular to the planar portion, a drive device that moves an object to be inspected relatively in a direction perpendicular to the planar portion and passes it through the through hole, a camera that images the light and dark pattern that is reflected on the surface of the object to be inspected protruding from the through hole towards the planar portion, and a calculation device that analyzes the surface shape of the object to be inspected based on the light and dark pattern image captured by the camera. Effect of the Invention

[0007] According to the present invention configured in this manner, even if the object to be inspected is long, the side surface (the surface parallel to the direction of movement of the object to be inspected) of the object to be inspected in both the circumferential and longitudinal directions can be inspected simply by passing the object through the through hole of the pattern display member. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic overall view of a surface inspection device according to an embodiment of the present invention, viewed from the side; [Diagram 2] FIG. 2 is a schematic overall perspective view of the surface inspection device according to the embodiment. [Diagram 3] FIG. 4 is a front view showing a planar portion and a light and dark pattern of the pattern display member in the embodiment. [Figure 4] FIG. 2 is a functional block diagram of a calculation device according to the embodiment. [Diagram 5] FIG. 4 is a perspective view showing a reflected light and dark pattern image when the object to be inspected is normal in the embodiment. [Figure 6] FIG. 13 is a perspective view showing a light-and-dark pattern image that is reflected when the surface of the object to be inspected is distorted in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] The surface inspection device 100 of this embodiment is used to detect distortions and scratches on the surface of a long-sized inspection object, such as a cylindrical material, and as shown in Figures 1 and 2, etc., is equipped with a pattern display member 1, a drive device 2 that holds the inspection object W and moves it back and forth, multiple cameras 3, and a calculation device 5.

[0011] The pattern display member 1 here has a rectangular flat plate shape and is provided in the center with a circular through hole 1a large enough for the object to be inspected W to pass through. As shown in Figures 2 and 3, a plurality of circular light and dark patterns 4 are displayed at a constant pitch in the radial direction around the through hole 1a on a flat surface 1b, which is the front surface of the pattern display member 1. The pattern display member 1 may be configured to emit the light and dark patterns 4 using a backlight.

[0012] The driving device 2 moves the test object W linearly in its longitudinal direction while holding it in a position perpendicular to the planar portion 1b. Here, as shown in FIG. 1, the test object W is inserted into the through hole 1a from the back side of the pattern display member 1 and protrudes from the front side. Specifically, as shown in the figure, the driving device 2 in this embodiment includes a holding unit 21 such as a chuck that detachably holds one end of the object to be inspected W, and a moving mechanism 22 that moves the holding unit 21. Here, the moving mechanism 22 is configured using, for example, an electric cylinder arranged so that its rod is perpendicular to the flat surface portion 1b, and the holding unit 21 is attached to the tip of the rod of the electric cylinder.

[0013] 1 and 2, the camera 3 captures an image of a light and dark pattern (hereinafter also referred to as a captured light and dark pattern) reflected on the side peripheral surface Wa of the object to be inspected W, and is disposed radially outward of the object to be inspected W with its optical axis inclined relative to the central axis (movement axis) C of the object to be inspected W so that light from the light and dark pattern 4 reflected by the side peripheral surface Wa is incident on the camera 3. In this embodiment, four cameras 3 are disposed around the central axis C of the object to be inspected W with a phase difference of 90 degrees so that the entire circumference of the side peripheral surface Wa of the object to be inspected W can be captured at once.

[0014] The arithmetic device 5 is a so-called computer equipped with a CPU, memory, I / O ports, etc., and by the CPU and peripheral devices working together in accordance with the program stored in the memory, it functions as an image data acquisition unit 51 that acquires image data from the camera 3 and a surface analysis unit 52 that detects defects and distortions on the surface of the object to be inspected W based on the acquired image data, as shown in Figure 4.

[0015] Next, the operation of the surface inspection apparatus 100 having such a configuration will be described.

[0016] First, an operator places the inspection object W on the driving device 2 and operates the surface inspection device 100, whereupon the driving device 2 moves the inspection object W from the rear side to the front side of the through-hole 1a at a constant speed.

[0017] When the tip of the object W to be inspected protrudes from the front side of the through-hole 1a, that is, from the flat portion 1b, each camera 3 starts capturing an image of the light and dark pattern reflected on the side peripheral surface Wa of the object W to be inspected.

[0018] The imaging is performed multiple times at regular time intervals, and each captured light-and-dark pattern image 4A is transmitted together with the imaging time to the calculation device 5. Note that since the inspection object W continues to move at a constant speed even during imaging, each captured light-and-dark pattern image 4A is an image of a different position on the side peripheral surface Wa of the inspection object W.

[0019] Each transmitted reflected light and dark pattern image 4A is acquired by the image data acquisition unit 51 of the calculation device 5 and stored in a pattern image storage unit 53 set in a specified area of ​​memory together with the imaging position on the inspection object W.

[0020] Here, the imaging position of each reflected light and dark pattern image 4A on the inspection object W is calculated by the image data acquisition unit 51 based on the fact that the inspection object W moves at a constant speed and the movement start time is known.

[0021] Next, the surface analysis section 52 analyzes each of the reflected light and dark pattern images 4A, and identifies the size, depth, position, etc. of distortions and scratches on the surface of the object W to be inspected.

[0022] In principle, the analysis by the surface analysis unit 52 is performed by detecting the difference between a normal reflected light and dark pattern image 4A as shown in Fig. 5 and a distorted reflected light and dark pattern image 4A as shown in Fig. 6. As the analysis algorithm, various algorithms can be used, such as a simple image comparison with a normal reflected light and dark pattern image or an algorithm using the phase change of the reflected light and dark pattern image.

[0023] According to the above-described surface inspection device 100, since it is only necessary to prepare a single thin plate-like pattern display member 1 in addition to the camera 3 and the computing device 5, it is possible to make the structure extremely compact and simple.

[0024] In addition, even if the inspection object W is long, it is possible to perform surface inspection of the entire side peripheral surface Wa in the circumferential and longitudinal directions, even though it is compact. <Other embodiments> The present invention is not limited to the above-described embodiment.

[0025] The object to be inspected preferably has a mirror surface, but is not limited to this. The object to be inspected is not limited to a cylindrical material having a circular cross-sectional outline, but may be a square, rectangular, polygonal, elliptical, or other cross-sectional outline, and may be a hollow cylinder. The inspection target area of ​​the object to be inspected may be a portion of the length or circumference.

[0026] The pattern display member only needs to have a flat surface, and other portions, such as the back side of the flat surface, may have any shape.

[0027] The light and dark pattern is not limited to a concentric stripe pattern, but may be, for example, a square, rectangular, or polygonal ring, a checkered pattern, etc. Also, the light and dark pattern does not need to be divided into two values, black and white, and may have a gradation of brightness that changes, for example, in a sinusoidal wave shape.

[0028] The through-hole may be provided not only in the center of the flat portion, but also in a position offset from the center, such as at the end. The cross section of the through hole is not limited to a circular shape, but may be a square, rectangular, polygonal, elliptical, or the like.

[0029] The number of cameras is not limited to four, and may be one or more. When the number of cameras is small and the entire circumferential surface of the inspection object cannot be covered in one image capture, the inspection object may be rotated.

[0030] A display having the through hole formed in the center may be used as the pattern display member. In this case, the light and dark pattern is displayed on the screen of the display. The advantage of using a display is that the light and dark pattern can be easily changed to an optimal one according to the object to be inspected by programming. In addition, since the light and dark pattern itself emits light, there is no need to provide a separate lighting device, and there is also the advantage that there is no need to consider the reflection of the lighting device.

[0031] In the above embodiment, the side surface Wa (light and dark pattern reflected on the side surface Wa) of the object to be inspected protruding from the planar portion 1b was imaged by each camera 3 while the object to be inspected W was moved from the back side to the front side of the through hole 1a. However, it is also possible to image the side surface Wa (light and dark pattern reflected on the side surface Wa) of the object to be inspected W on the planar portion 1b side by each camera 3 while the object to be inspected W is moved from the front side to the back side of the through hole 1a.

[0032] Additionally, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present invention.

[0033] The features of this surface inspection device can be summarized as follows: [1] A surface inspection device comprising: a pattern display member having a planar portion on which a predetermined light and dark pattern is displayed; a through hole passing through the pattern display member in a direction perpendicular to the planar portion; a drive device for moving an object to be inspected relatively in a direction perpendicular to the planar portion and passing it through the through hole; a camera for capturing an image of the light and dark pattern that appears on a surface of the object to be inspected protruding from the through hole towards the planar portion; and a calculation device for analyzing the surface shape of the object to be inspected based on the light and dark pattern image captured by the camera.

[0034] [2] The surface inspection device according to [1], wherein a plurality of cameras are arranged around the axis of the object to be inspected. With the above configuration, the side surface of the object to be inspected can be inspected in the circumferential direction in a short period of time.

[0035] [3] The surface inspection device according to [1] or [2], wherein a light and dark pattern is formed concentrically around the through hole. With the above configuration, a light and dark pattern can be projected over the entire circumferential direction of the side surface of the object to be inspected, enabling highly accurate surface inspection.

[0036] [4] The surface inspection device according to [1], [2] or [3], wherein the pattern display member is constructed using a display having the through hole formed in the center, and the light and dark pattern is displayed on the screen of the display. With the above configuration, the light and dark pattern can be easily changed to the optimum one for the object to be inspected by programming. In addition, since the light and dark pattern itself emits light, there is no need to provide a separate lighting device, and there is also the effect that there is no need to consider the reflection of the lighting device. [Explanation of symbols]

[0037] 100 Surface inspection device 1. Pattern display member 1a...Through hole 1b...Plane part 2. Drive unit 3. Camera 4. Light and dark pattern 4A Light and dark pattern image 5...Arithmetic unit W: Inspection item

Claims

1. a pattern display member having a flat surface portion on which a predetermined light and dark pattern is displayed; a through hole passing through the pattern display member in a direction perpendicular to the planar portion; a driving device that moves the object to be inspected relatively in a direction perpendicular to the planar portion and passes the object through the through hole; a camera that captures an image of the light and dark pattern on a surface of the object to be inspected that protrudes from the through hole toward the flat portion; and a calculation device that analyzes the surface shape of the object to be inspected based on the light and dark pattern image captured by the camera.

2. 2. The surface inspection apparatus according to claim 1, further comprising a plurality of cameras disposed around the axis of the object to be inspected.

3. 3. A surface inspection device according to claim 1, wherein a light and dark pattern is formed concentrically around the through hole.

4. 2. The surface inspection device according to claim 1, wherein the pattern display member is configured by utilizing a display having the through hole formed in the center thereof, and the light and dark pattern is displayed on a screen of the display.

5. A pattern display member is used, which has a flat surface portion on which a predetermined light and dark pattern is displayed and has a through hole formed therein that penetrates the flat surface portion in a direction perpendicular to the flat surface portion, an object to be inspected is moved relative to the planar portion in a direction perpendicular to the planar portion, and while passing the object through the through hole, an image of the light and dark pattern reflected on a surface of the object to be inspected protruding from the through hole toward the planar portion is captured; The surface inspection method further comprises analyzing the surface shape of the object to be inspected based on the captured light and dark pattern image.

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