Visual inspection device for cylindrical workpiece and visual inspection method for cylindrical workpiece

Abstract

To provide a visual inspection device for cylindrical workpiece and visual inspection method for cylindrical workpiece that can perform inspections using regular reflection light and diffuse reflection light while suppressing an extension in an inspection time.SOLUTION: In a visual inspection device 10 for cylindrical workpiece which comprises: an illumination device 14 that irradiates an outer circumferential surface of a rotating cylindrical workpiece 20 with light; and an imaging device 12 that images an inspection area 30 of the cylindrical workpiece 20 irradiated with the light by the illumination device 14, the illumination device 14 includes: a first illumination device 15 that irradiates a first inspection area 31 being a portion of the inspection area 30 with light for regular reflection light; and second illumination devices 16, 17 that irradiate a second inspection area 32 being a portion of the inspection area 30 and different from the first inspection area 31 with light for diffuse reflection light.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an appearance inspection device and an appearance inspection method for a cylindrical workpiece.

[0002] After machining, cylindrical workpieces such as camshafts are subjected to visual inspection to check for scratches on the surface of the cylindrical workpiece. Conventionally, visual inspection devices that use an optical method of irradiating light onto the surface of a cylindrical workpiece and detecting the presence or absence of surface defects using the reflected light are known as devices for performing visual inspection.

[0003] For example, Patent Document 1 describes an appearance inspection device that uses an illumination device to illuminate the entire upper peripheral surface of a cylindrical workpiece extending in the horizontal direction, and captures an image of the inspection area of ​​the rotating cylindrical workpiece with an imaging device located directly above the cylindrical workpiece. This appearance inspection device uses specular reflection light that occurs when the surface of the cylindrical workpiece specularly reflects the light illuminated by the illumination device, and can detect the presence or absence of scratches on the cylindrical workpiece surface from the image captured by the imaging device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-174705 Summary of the Invention [Problem to be solved by the invention]

[0005] Visual inspection using specular reflected light can detect dents on the surface of a cylindrical workpiece, but cannot properly detect scratches with small surface angles, such as bite scratches caused by cutting chips that get caught in the surface of a cylindrical workpiece during cutting. Such bite scratches can be detected by using diffuse reflected light from the cylindrical workpiece instead of specular reflected light, but performing an inspection using diffuse reflected light after an inspection using specular reflected light takes a long time.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide an external inspection device for cylindrical workpieces and an external inspection method for cylindrical workpieces that are capable of performing inspection using direct reflected light and diffuse reflected light while suppressing extension of inspection time. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, one embodiment of the present invention is an appearance inspection device for cylindrical workpieces, which comprises an illumination device that irradiates light onto the outer peripheral surface of a rotating cylindrical workpiece, and an imaging device that images an inspection area of ​​the cylindrical workpiece irradiated with light by the illumination device, wherein the illumination device comprises a first illumination device that irradiates light for specular reflection light onto a first inspection area that is part of the inspection area, and a second illumination device that irradiates light for diffuse reflection light onto a second inspection area that is part of the inspection area and different from the first inspection area.

[0008] In addition, in order to achieve the above-mentioned object, one embodiment of the present invention relates to a method for visual inspection of a cylindrical workpiece, in which light is irradiated onto the outer peripheral surface of a rotating cylindrical workpiece by an illumination device, and the inspection area of ​​the cylindrical workpiece irradiated with the light is imaged by an imaging device, wherein the illumination device comprises a first illumination device and a second illumination device, and the first illumination device irradiates light for specular reflection onto a first inspection area that is part of the inspection area, and the second illumination device irradiates light for diffuse reflection onto a second inspection area that is part of the inspection area and different from the first inspection area. Effect of the Invention

[0009] According to the cylindrical workpiece appearance inspection device and cylindrical workpiece appearance inspection method of the present invention, inspection can be performed using specular reflected light and diffuse reflected light while suppressing an extension of the inspection time. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic front view showing an appearance inspection device for a cylindrical workpiece according to one embodiment of the present invention; [Diagram 2] FIG. 2 is a side view of the appearance inspection apparatus shown in FIG. [Diagram 3] FIG. 2 is a plan view of the appearance inspection apparatus shown in FIG. [Figure 4] FIG. 11 is an explanatory diagram illustrating the direction of light irradiation by a second lighting device. [Diagram 5] 1 is a photograph of an image captured by an imaging device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] FIG. 1 is a schematic front view showing an appearance inspection device 10 for cylindrical workpieces according to an embodiment of the present invention, FIG. 2 is a side view of the appearance inspection device 10, and FIG. 3 is a plan view of the appearance inspection device 10 seen from above. The appearance inspection device 10 of this embodiment inspects the presence or absence of scratches or the like on the surface of the cylindrical workpiece 20 by using light reflected from the cylindrical workpiece 20. The appearance inspection device 10 includes a rotation drive device 11 that supports the cylindrical workpiece 20 rotatably around the central axis 21 of the cylindrical workpiece 20 as the center of rotation, an imaging device 12, an image processing device 13, an illumination device 14, and a control device 18. Note that the rotation drive device 11, the image processing device 13, and the control device 18 are omitted in FIGS. 2 and 3.

[0012] The imaging device 12 captures an image of an inspection area 30 of the cylindrical workpiece 20 set on the rotary drive device 11. The imaging device 12 can be, for example, a camera capable of capturing still images and videos. In this embodiment, a single camera capturing monochrome images is used as the imaging device 12. In this embodiment, the outer peripheral surface on the upper side of the cylindrical workpiece 20 set on the rotary drive device 11 so that the axial direction coincides with the horizontal direction is the inspection area 30 captured by the single camera, and the imaging device 12 is disposed vertically above the inspection area 30.

[0013] The lighting device 14 irradiates light onto the outer peripheral surface of the cylindrical workpiece 20 rotated by the rotary drive device 11. The lighting device 14 includes a first lighting device 15 that irradiates light for specular reflection and second lighting devices 16 and 17 that irradiate light for diffuse reflection. Each of the lighting devices 15, 16, and 17 has a light source unit 15a, 16a, and 17a that emits white light and is attached to a light-shielding cover 15b, 16b, and 17b.

[0014] As shown in FIG. 2 and FIG. 3, the first lighting device 15 irradiates a first inspection area 31, which is a part of the inspection area 30 of the cylindrical workpiece 20, with light for specular reflection. The second lighting devices 16, 17 irradiate a second inspection area 32, which is a part of the inspection area 30 of the cylindrical workpiece 20 and is different from the first inspection area 31, with light for diffuse reflection. Here, irradiating different areas with light means that the areas targeted for irradiation with light are different, and it means that a small amount of light is allowed to reach the other area. In addition, a partition plate (not shown) may be placed between the adjacent first inspection area 31 and second inspection area 32 to prevent light from reaching the other area so as not to interfere with the rotation of the cylindrical workpiece 20 or the imaging by the imaging device 12. In this embodiment, the first inspection area 31 and the second inspection area 32 are adjacent to each other in the circumferential direction of the cylindrical workpiece 20, and the areas obtained by dividing the upper outer peripheral surface of the cylindrical workpiece 20, which constitutes the inspection area 30, into two equal parts in the circumferential direction are the first inspection area 31 and the second inspection area 32, respectively.

[0015] The white arrows in Fig. 2 and the arrows extending in the vertical direction of the paper in Fig. 3 indicate the direction of light irradiation by the first lighting device 15, and the white arrows in Fig. 1 and the arrows extending in the horizontal direction of the paper in Fig. 3 indicate the direction of light irradiation by the second lighting devices 16, 17. The thick black arrows in Figs. 1 and 2 indicate specularly reflected light by the first lighting device 15, and the thin black arrows in Figs. 1 and 2 indicate diffusely reflected light by the second lighting devices 16, 17.

[0016] The first lighting device 15 is arranged so as to overlap with the imaging device 12 in the axial direction of the cylindrical workpiece 20 and irradiate light onto the first inspection area 31 of the cylindrical workpiece 20 from below the lens of the camera, which is the imaging device 12. The second lighting devices 16, 17 are arranged on both sides of the first lighting device 15 in the axial direction of the cylindrical workpiece 20, and specifically, are arranged at positions symmetrical with respect to the optical axis of the imaging device 12 in the front view shown in FIG. 1. Note that the appearance inspection device 10 may be configured to include at least one of the second lighting devices 16, 17, and may be configured to include only one of the second lighting devices 16, 17 shown in FIG. 1. By arranging two second lighting devices 16, 17 as in this embodiment, a wide area can be secured for irradiating light for diffuse reflection.

[0017] FIG. 4 is an explanatory diagram for explaining the direction of irradiation of light by the second illumination device 16, and shows an enlarged cross section of the surface layer of the second inspection area 32 of the cylindrical workpiece 20, in which the cylindrical workpiece 20 is cut along a vertical plane parallel to the axial direction. The left-right direction in FIG. 4 coincides with the axial direction of the cylindrical workpiece 20. In this embodiment, a large number of cutting marks 24 (machining streaks indicated by reference numeral 24 in FIG. 5) extending along the circumferential direction are formed on the outer peripheral surface of the cylindrical workpiece 20 by cutting the surface of the cylindrical workpiece 20. As shown in the illustrated example, the second illumination device 16 is disposed so that light is irradiated from a direction substantially perpendicular to the direction of the cutting marks 24 formed on the outer peripheral surface of the cylindrical workpiece 20 (i.e., a direction approximating the axial direction of the cylindrical workpiece 20).

[0018] In this way, by irradiating light in a direction perpendicular to the cutting marks 24 by the second illumination device 16, a surface 28a on which light hits and a surface 28b on which light does not hit are generated on the cross-sectional mountain-shaped surface of the cutting marks 24, and the light and dark of the cutting marks 24 are clearly shown in the captured image. Note that FIG. 4 shows the light irradiation direction of one illumination device 16 of the two second illumination devices 16, 17, but the illumination device 17 arranged symmetrically thereto is also arranged to irradiate light from a direction approximately perpendicular to the surface inclination direction of the cutting marks 24. That is, in the area irradiated by light by the other second illumination device 17, on the cross-sectional mountain-shaped surface of the cutting marks 24 shown in FIG. 2, the surface on which light hits is surface 28b, and the surface on which light does not hit is surface 28a.

[0019] The image processing device 13 is composed of, for example, a computer, and detects the presence or absence of defects in the cylindrical workpiece 20 based on the captured image obtained by the imaging device 12. The image processing device 13 also judges whether the cylindrical workpiece 20 is a pass or fail product based on the detection result of the presence or absence of defects. The judgment of the presence or absence of defects in the cylindrical workpiece 20 and the judgment of whether it is a pass or fail product can be performed, for example, by a judgment based on a comparison with reference data that is a preset judgment criterion, or a judgment based on prior learning data using artificial intelligence (AI). The judgment result can be displayed on a display unit such as a display provided in the image processing device 13.

[0020] The control device 18 is configured with a memory that stores programs and the like for implementing the functions of each component of the visual inspection device 10, and an arithmetic processing unit such as a CPU that executes the programs in the memory. The control device 18 controls the input and output of electrical signals to and from the rotation drive device 11, the imaging device 12, the image processing device 13, and the lighting device 14, and controls their operations.

[0021] Next, a method for inspecting the appearance of a cylindrical workpiece 20 using the above-mentioned appearance inspection device 10 will be described. First, the cylindrical workpiece 20 to be inspected is set on the rotary drive device 11. After that, the first and second illumination devices 15, 16, and 17 irradiate the outer peripheral surface of the rotating cylindrical workpiece 20 with light, and the imaging device 12 images the inspection area 30 of the cylindrical workpiece 20 irradiated with the light. At this time, the first illumination device 15 irradiates the first inspection area 31 with light for specular reflection, and the second illumination devices 16 and 17 irradiate the second inspection area 32 with light for diffuse reflection.

[0022] The image processing device 13 detects the presence or absence of defects in the cylindrical workpiece 20 based on the image data captured by the imaging device 12, and judges whether the cylindrical workpiece 20 is a non-defective product or a defective product based on the detection result.

[0023] FIG. 5 is a photograph of an image of the inspection area 30 of the cylindrical workpiece 20 captured by the imaging device 12, with the lower side of FIG. 5 showing the first inspection area 31 and the upper side showing the second inspection area 32. In the visual inspection of the first inspection area 31 using specular reflection light, dents and other defects present on the surface of the cylindrical workpiece 20 can be detected with high accuracy. In the second inspection area 32, a large number of cutting marks 24 extending in the circumferential direction on the surface of the cylindrical workpiece 20 are more clearly visible than in the first inspection area 31. In the visual inspection using diffuse reflection light, scratches with small face angles, such as chip marks caused by chips getting caught in the surface of the cylindrical workpiece 20 during cutting processing of the cylindrical workpiece 20, can be detected with high accuracy.

[0024] In the above-mentioned appearance inspection device 10, a first inspection area 31 for specular reflected light and a second inspection area 32 for diffuse reflected light are provided within an inspection area 30 imaged by one imaging device 12, so that appearance inspection using specular reflected light and appearance inspection using diffuse reflected light can be performed simultaneously over the entire circumference of the cylindrical workpiece 20 while the cylindrical workpiece 20 is rotated once. As a result, the appearance inspection device 10 of this embodiment can reduce the inspection time to about half the time compared to an apparatus that performs appearance inspection using specular reflected light and diffuse reflected light separately, so that highly accurate appearance inspection using specular reflected light and diffuse reflected light is possible while suppressing an extension of the inspection time.

[0025] In addition, in the visual inspection device 10 of this embodiment, the second lighting devices 16, 17 are set to irradiate light perpendicular to the cutting marks 24 on the surface of the cylindrical workpiece 20, so that the cutting marks 24 can be clearly seen in the captured image. In the cutting process of the cylindrical workpiece 20 performed before the visual inspection, if chips generated during cutting bite into the surface of the cylindrical workpiece 20, a chip trace portion remains on the surface of the cylindrical workpiece 20. If there is a chip trace portion on the surface of the cylindrical workpiece 20 where the cutting marks 24 are present, the surface of the chip trace portion becomes smooth and appears dark in the captured image of the second inspection area 32. In this way, the difference between the chip trace portion and the cutting marks 24 is clearly seen in the second inspection area 32, so that the inspection accuracy by diffuse reflection light is improved.

[0026] In addition, since the above-mentioned appearance inspection device 10 uses a monochrome camera as the imaging device 12, costs can be reduced compared to those using a color camera, and image processing can be simplified compared to those using color images.

[0027] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the invention. [Explanation of symbols]

[0028] 10. Cylindrical workpiece appearance inspection device 12 Imaging device 14 Lighting equipment 15 First lighting device 16,17 Second lighting device 20 Cylindrical workpiece 24 cutting marks 30 Inspection Area 31 First Inspection Area 32 Second Inspection Area

Claims

1. An illumination device that irradiates light onto the outer peripheral surface of the rotating cylindrical workpiece; An imaging device that images an inspection area of ​​the cylindrical work irradiated with light by the illumination device, The lighting device includes: a first illumination device that irradiates a first inspection area, which is a part of the inspection area, with light for specular reflection; a second illumination device that irradiates a second inspection area, which is a part of the inspection area and is different from the first inspection area, with light for diffuse reflection light; A cylindrical workpiece appearance inspection device comprising:

2. 2. The cylindrical workpiece appearance inspection device according to claim 1, wherein the second illumination device irradiates light from a direction substantially perpendicular to the direction of the cutting marks formed on the outer peripheral surface of the cylindrical workpiece.

3. 3. The visual inspection device for a cylindrical workpiece according to claim 1, wherein the first inspection area and the second inspection area are adjacent to each other in the circumferential direction of the cylindrical workpiece.

4. 3. The visual inspection device for a cylindrical workpiece according to claim 1 or 2, characterized in that the second lighting device is arranged on both sides of the first lighting device in the axial direction of the cylindrical workpiece.

5. A method for visually inspecting a cylindrical workpiece, comprising: irradiating an outer peripheral surface of a rotating cylindrical workpiece with light by an illumination device; and imaging an inspection area of ​​the cylindrical workpiece irradiated with light by an imaging device, the lighting device includes a first lighting device and a second lighting device; A method for visual inspection of a cylindrical workpiece, characterized in that the first lighting device irradiates a first inspection area, which is a part of the inspection area, with light for specular reflection light, and the second lighting device irradiates a second inspection area, which is a part of the inspection area and different from the first inspection area, with light for diffuse reflection light.

Images