JP7595325B2 - Surface Inspection Equipment - Google Patents

Description

The present invention relates to a surface inspection device, for example, a surface inspection device that inspects the surface of a rod-shaped object for defects.

When manufacturing products, there is an inspection process to check the surface of the product for defects in appearance, such as scratches or dullness. Technology related to such surface inspection is described in Patent Document 1.

The surface inspection device described in Patent Document 1 includes a rotation mechanism that rotates a cylindrical or cylindrical object to be inspected in a circumferential direction, and a holding mechanism that holds down the circumferential surface of the object to be inspected rotating in the circumferential direction. The holding mechanism includes a light source unit that irradiates light onto the circumferential surface, an imaging unit that captures an image of the circumferential surface irradiated with the light, and a moving body that moves the holding mechanism that holds down the circumferential surface along the axial direction of the object to be inspected rotating in the circumferential direction.

JP 2018-179563 A

However, the technology described in Patent Document 1 has a problem in that if the test object has a bent portion, the test object cannot be rotated by the rotation mechanism, and it cannot be used for test objects with bent portions.

The present invention was made in consideration of the above circumstances, and aims to perform surface inspection of an object to be inspected that has a bent portion.

One aspect of the surface inspection device according to the present invention includes a holder that holds a first straight portion continuing from one end of a rod-shaped object to be inspected having a bent portion, a rotation drive unit that holds the other end of the object to be inspected or a second straight portion continuing from the other end and rotates the object to be inspected about the axis center of the first straight portion as the rotation center axis, a photographing unit that photographs the first straight portion, and a defect detection processing unit that detects defects in the object to be inspected based on the image photographed by the photographing unit, the holder forms a missing portion in a part of a cylinder that holds the first straight portion, and the missing portion serves as an observation window, and the photographing unit photographs the image of the surface of the object to be inspected including the observation window portion.

The surface inspection device of the present invention can perform surface inspection of an object to be inspected that has a bent portion.

1 is an overall external view of a surface inspection device according to a first embodiment; 2 is a diagram for explaining the configuration of an inspection box and a control box of the surface inspection apparatus according to the first embodiment; FIG. 2 is a diagram for explaining the configuration of an inspection subject holding unit, a camera, and lighting provided in an inspection box according to the first embodiment. FIG. 1 is a block diagram of a surface inspection device according to a first embodiment. 1 is a diagram for explaining a surface inspection method of the surface inspection device according to the first embodiment; 4 is a diagram for explaining a reflection prevention range by a shielding plate of the surface inspection device according to the first embodiment; FIG. 5A to 5C are diagrams for explaining how to move an object to be inspected during inspection in the surface inspection apparatus according to the first embodiment.

For clarity of explanation, the following description and drawings have been omitted and simplified as appropriate. Furthermore, each element shown in the drawings as a functional block performing various processes can be configured in hardware with a CPU (Central Processing Unit), memory, and other circuits, and in software, can be realized by programs loaded into memory. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms using only hardware, only software, or a combination of both, and are not limited to any of these. Furthermore, in each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

The above-mentioned program can be stored 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 may 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 supply the program to a computer via wired communication paths such as electric wires and optical fibers, or wireless communication paths.

First embodiment
In the following description, a surface inspection device for detecting surface defects of an object to be inspected will be described. FIG. 1 shows an overall external view of the surface inspection device according to the first embodiment. FIG. 1 shows a perspective view of the surface inspection device 1 as seen from the front and as seen from the rear. As shown in FIG. 1, the surface inspection device 1 according to the first embodiment has a housing in which an inspection box 10, a control box 20, and a display 30 are integrated. The inspection box 10 is provided with a lid 11. The surface inspection device 1 loads and unloads an object to be inspected into and from the inspection box 10 with the lid 11 open, and performs surface inspection of the object to be inspected with the lid 11 closed. In addition, a plurality of button interfaces are provided on the front surface of the inspection box 10 as an operation interface 31. The buttons provided on the operation interface 31 may be mechanical switches or software-implemented buttons displayed on a screen having a touch panel function.

The control box 20 is provided with a mechanism and a computing device for operating the inspection structure in the inspection box 10 based on instructions given from the operation interface 31 and displaying the inspection results on the display 30.

The internal structure of the inspection box 10 will now be described. Figure 2 is a diagram illustrating the configuration of the inspection box 10 and control box of the surface inspection device 1 according to the first embodiment. Figure 2 illustrates the internal structures of the inspection box 10 and control box 20. Note that in Figure 2, structures other than the inspection unit drive section 21 and the rotational position detection sensor 22 and the calculation device provided as the calculation device are omitted from the illustration.

As shown in FIG. 2, the inspection box 10 is provided with a lid 11, and the inspected object WK is inserted and removed from the inspection box 10 by opening and closing the lid 11. Inside the inspection box 10, a camera 12, a surface lighting unit 13, an upper lighting unit 141, a lower lighting unit 142, and an inspected object holding unit 15 are provided. The inspected object holding unit 15 is also provided with an inspection end holding unit 151, a rotation drive unit 152, and a shielding plate 153. The inspection end holding unit 151 is equipped with an inspected end holding part 154 and a holder 155 used to hold the inspected object WK.

As shown in FIG. 2, the surface inspection device 1 according to the first embodiment inspects a rod-shaped object WK to be inspected that has a bent portion. More specifically, the object WK to be inspected may be L-shaped or U-shaped, but is preferably U-shaped. The surface inspection device 1 according to the first embodiment inspects the surface of the straight portion following the bent portion of the object WK to be inspected.

The camera 12 is a photographing unit that obtains images for detecting defects such as scratches on the test object WK. The surface illumination unit 13, the upper illumination unit 141, and the lower illumination unit 142 are light-emitting units that emit light to irradiate the test object WK during inspection. The test object holding unit 15 is rotated by the inspection unit driving unit 21 provided in the control box 20. At this time, the test object holding unit 15 rotates so as to rotate the test object WK around the central axis of the straight part of the axis of the test object WK that is held by the test end holding unit 154 and the holder 155. In addition, the rotation angle of the test object holding unit 15 is transmitted to the rotation position detection sensor 22 by a belt. The rotation position detection sensor 22 transmits the detected rotation angle information of the test object holding unit 15 to the inspection control unit provided in the control box 20.

The inspected object holding unit 15 is provided with an inspected end holding unit 151 and a rotation drive unit 152. The inspected end holding unit 151 holds the straight portion of the inspected object WK on the side that is the center of rotation. More specifically, the inspected end holding unit 151 is provided with an inspected end holding portion 154 and a holder 155. The inspected end holding portion 154 rotatably holds the end of the inspected object WK held by the inspected end holding unit 151. The holder 155 rotatably holds a first straight portion continuing from one end of the rod-shaped inspected object having a bent portion.

The rotation drive unit 152 holds the other end of the test object WK or a second straight section continuing from the other end, and rotates the test object WK around the axis of the first straight section as the central axis of rotation. In the example shown in FIG. 2, the rotation drive unit 152 holds the end of the straight section of the test object WK that is not held by the inspection end holding unit 151. Note that the holding of the other end side of the test object WK may be the second straight section continuing from the other end that is not held by the holder 155.

The shielding plate 153 blocks the view between the first straight section and at least a part of the curved section following the second straight section held by the rotation drive unit 152. This prevents reflected light emitted from the second straight section and the bent section following the second straight section from being reflected on the surface of the first straight section to be inspected. The shielding plate 153 is preferably a non-reflective material. In addition, the shielding plate 153 is attached to the rotation drive unit 152 so that it can be raised and lowered in the vertical direction (for example, the extension direction of the first straight section). By attaching the shielding plate 153 so that it can be raised and lowered in the vertical direction in this way, it becomes possible to accommodate different test objects WK whose bent sections are located at various heights. In addition, by attaching the shielding plate 153 to the rotation drive unit 152, the positional relationship between the second straight section and the shielding plate can be kept constant when the test object holding unit 15 rotates.

Next, the structure provided in the inspection box 10 will be described in more detail with reference to FIG. 3. FIG. 3 is a diagram illustrating the configuration of the inspection object holding unit 15, camera 12, and lighting provided in the inspection box 10 according to the first embodiment. As shown in FIG. 3, in the inspection box 10, the camera 12, surface lighting unit 13, upper lighting unit 141, and lower lighting unit 142 are provided on a frame provided on a base plate 16. In addition, the inspection object holding unit 15 is connected to the inspection unit drive unit 21 and rotational position detection sensor 22 so as to sandwich the base plate 16.

In the surface inspection device 1 according to the first embodiment, a surface lighting unit 13 is provided to cover the camera 12. A hole is provided in the surface lighting unit 13 to expose the camera, and the camera 12 photographs the object WK to be inspected through this hole. The upper lighting unit 141 and the lower lighting unit 142 are disposed above and below the surface lighting unit 13. The surface lighting unit 13 and the upper lighting unit 141 and the lower lighting unit 142 are controlled to emit light simultaneously or only one of them depending on the type of scratches, stains, etc. to be inspected.

Also, as shown in FIG. 3, the shielding plate 153 is positioned so as to block the view between the first straight portion of the test object WK that is held by the test end holding unit 151 and is the subject of inspection, and the second straight portion that is the subject of inspection.

Here, the connection relationship between the processing blocks provided in the inspection box 10 and the control box 20 in the surface inspection device 1 according to the first embodiment will be described. Figure 4 shows a block diagram of the surface inspection device 1 according to the first embodiment. For the sake of explanation, Figure 4 additionally shows a robot arm 40 that is used simultaneously with the surface inspection device 1.

As shown in FIG. 4, in the surface inspection device 1 according to the first embodiment, the rotation control unit 23 and the inspection control unit 24 provided in the control box 20 are used to operate the camera 12, the inspection object holding unit 15, and the display 30 provided in the control box 20. Furthermore, the surface inspection device 1 according to the first embodiment detects defects such as scratches and stains on the surface of the inspection object WK by performing image processing on the image obtained from the camera 12 using the defect detection processing unit 25. In the surface inspection device 1, the detection results are displayed on the display 30, which serves as a result display unit. Furthermore, the surface inspection device 1 operates by receiving operation instructions given by the operator of the device via the operation interface 31 via the inspection control unit 24.

The inspection control unit 24 executes a preset inspection sequence based on instructions given by the operator via the operation interface 31. Specifically, the inspection control unit 24 gives an operation instruction to the robot arm 40 to insert the specimen WK into the specimen holding unit 15. Then, in response to the specimen WK being held in the specimen holding unit 15, the inspection control unit 24 closes the lid 11 (not shown in FIG. 4) to make the inside of the inspection box 10 a darkroom.

Then, the inspection control unit 24 operates the surface illumination unit 13, the upper illumination unit 141, and the lower illumination unit 142 to irradiate the object WK to be inspected. The inspection control unit 24 also gives an operation instruction to the rotation control unit 23. The rotation control unit 23 rotates the object holding unit 15 in accordance with the operation instruction given from the inspection control unit 24. At this time, the inspection control unit 24 may rotate the object WK to be inspected continuously without stopping, or may rotate the object WK while stopping it at a predetermined interval. When rotating the object WK to be inspected while stopping it at a predetermined interval, the inspection control unit 24 obtains rotation angle information of the object holding unit 15 from the rotation position detection sensor 22, which is omitted in FIG. 4, and gives an operation instruction to the rotation control unit 23 so that the object holding unit 15 rotates once while stopping at a preset angle. The details of the method of rotating the object WK to be inspected in the first embodiment will be described later.

In addition, the camera 12 acquires an image of the object WK to be inspected each time the object holding unit 15 stops, and provides the image to the defect detection processing unit 25. The defect detection processing unit 25 applies a predetermined filter process to the image received from the camera 12, and if it determines that the object WK to be inspected has a defect, it displays "inspection NG" on the display 30, and if it determines that the object WK to be inspected has no defect, it displays "inspection OK" on the display 30.

Next, the imaging range of the inspected object in the surface inspection device 1 according to the first embodiment will be explained. FIG. 5 shows a diagram for explaining the surface inspection method of the surface inspection device according to the first embodiment. Note that in the explanation with reference to FIG. 5, the contents explained in FIG. 4 and earlier will be omitted. In FIG. 5, the imaging area PA of the camera 12 is hatched. The camera 12 acquires an image of the imaging range WD of the first straight line portion WKm beyond the imaging area PA.

As shown in FIG. 5, in the surface inspection device 1 according to the first embodiment, the holder 155 holds the first straight section WKm continuing from one end of a rod-shaped inspection object having a bent section. At this time, the holder 155 holds the first straight section WKm so as to fit the first straight section WKm with a gap so that the first straight section WKm can rotate. Furthermore, the holder 155 opens its claws when it is not holding the first straight section WKm, and closes its claws when it is holding the first straight section WKm. Furthermore, the holder 155 forms a notched portion in part of the cylinder that holds the first straight section WKm, and the notched portion serves as an observation window WN.

The camera 12 then sets the inspection surface of the first straight section WKm, including the observation window WN, as the shooting range WD, and outputs an image of the shooting range WD by cutting out the captured image of the area including the shooting range WD. In the surface inspection device 1 according to the first embodiment, by providing this observation window WN, it becomes possible to inspect the entire inspection object by simply rotating the first straight section WKm once.

In addition, in the surface inspection device 1 according to the first embodiment, the shielding plate 153 is provided to prevent the reflected light emitted from the anti-reflection area MA of the second straight section WKr from being reflected in the shooting range WD. As shown in FIG. 5, the shielding plate 153 has a spoon-like shape with a wider upper end than the other parts. Since the test object WK has a bent portion, it is preferable to widen the width of the upper end of the shielding plate 153 in order to prevent the reflection of the reflected light reflected at the bent portion on the second straight section WKr side. The bending angle of this bent portion varies depending on the test object WK. Therefore, in the surface inspection device 1 according to the first embodiment, the width of the upper end of the shielding plate 153 is wider than the other parts, and the shielding plate 153 is structured to be movable up and down, so that it is possible to prevent reflection in test objects WK of various shapes.

Here, the anti-reflection range MA by the shielding plate 153 will be described in detail. Figure 6 shows a diagram explaining the anti-reflection range by the shielding plate 153 of the surface inspection device 1 according to the first embodiment. In Figure 6, as shown in the hatched area that constitutes the anti-reflection range MA, the area where the view is blocked by the shielding plate 153 when viewed from the shooting range WD of the first straight section WKm becomes the anti-reflection range MA. At this time, it is important to set the width and height of the shielding plate 153 so that the anti-reflection range MA is within a range that does not obstruct the shooting area PA. In the surface inspection device 1 according to the first embodiment, the shielding plate 153 prevents reflected light from the second straight section WKr in the anti-reflection range MA from being reflected on the first straight section WKm.

Next, in the surface inspection device 1 according to the first embodiment, the first straight section WKm is rotated by rotating the end of the second straight section WKr, which is connected to the first straight section WKm via a bent section, by the rotation drive unit 152. In the surface inspection device 1 according to the first embodiment, either of the following rotation methods can be used: a method of acquiring a surface image while continuously rotating the inspected object WK without stopping it, or a method of acquiring a surface image while stopping the inspected object WK at predetermined intervals.

By continuously rotating the object WK to be inspected, the inspection time can be shortened. Furthermore, when the object WK to be inspected is continuously rotated, an image of the surface of the object WK to be inspected is acquired at each predetermined sampling timing, and the defect detection processing unit 25 acquires an image of the inspection surface, which will be described below, from multiple captured images. At this time, the defect detection processing unit 25 may use angle information obtained by the rotational position detection sensor 22.

In addition, when an image of the inspection surface is acquired while the inspected object WK is stopped, a clear image of the inspection surface can be acquired, improving the inspection accuracy. In this case, the defect detection processing unit 25 uses the acquired image as is to analyze the defects.

Figure 7 shows a diagram explaining how to move the test object WK during inspection in the surface inspection device 1 according to the first embodiment.

As shown in FIG. 7, one of the features of the surface inspection device 1 according to the first embodiment is the relationship between the size of the observation window WN of the holder 155 and the rotation step angle of the second straight portion WKr. Specifically, in the surface inspection device 1 according to the first embodiment, if the space when the camera 12 captures the image of the image capture range WD is defined as the image capture area PA, the second straight portion WKr is controlled not to stop within the image capture area PA at the timing when the camera 12 captures the image capture range WD, or the image during the period when the second straight portion WKr crosses the image capture area PA is discarded from the captured image.

In addition, in the surface inspection device 1 according to the first embodiment, the inspected object WK is rotated so that the entire outer peripheral surface of the first straight section WKm is photographed during one rotation of the first straight section WKm. When the inspected object WK is rotated while being stopped, the surface inspection device 1 sets the rotation angle of one step of the first straight section WKm so that the entire outer peripheral surface of the first straight section WKm is photographed.

More specifically, the angle between a first window setting line L1 connecting one end of the observation window WN in the rotation direction and the rotation center axis of the first straight line portion WKm, and a second window setting line L2 connecting the other end of the observation window WN in the rotation direction and the rotation center axis of the first straight line portion WKm is defined as a first angle θ1. The angle of the rotation step of the second straight line portion WKr is defined as a second angle θ2. In the first embodiment, the second angle θ2 is set smaller than the first angle θ1. By setting in this way, the widths of the inspection surfaces A1 to A8 shown in FIG. 7 are each set smaller than the opening width of the observation window WN.

When the object WK to be inspected is rotated while being stopped, as shown in FIG. 7, the first straight section WKm is rotated while the second straight section WKr is stopped at P1 to P8 for each shooting timing, thereby sequentially photographing the inspection surfaces A1 to A8. On the other hand, when the object WK to be inspected is rotated continuously, the defect detection processing section 25 extracts images of the inspection surfaces A1 to A8 from the multiple images captured.

As explained above, in the surface inspection device 1 according to the first embodiment, the holder 155 has an observation window WN through which the first straight section WKm of the inspection target is exposed to the camera 12 within a predetermined range. In the surface inspection device 1 according to the first embodiment, the second angle θ2 in FIG. 7 is set to be smaller than the first angle θ1, so that the entire outer peripheral surface of the first straight section WKm is photographed by simply rotating the first straight section WKm once.

Due to the above features, the surface inspection device 1 according to the first embodiment can inspect the surface of the straight parts of the object to be inspected, even if the object has bent parts. Furthermore, the surface inspection device 1 according to the first embodiment can inspect the parts other than the bent parts of the object to be inspected, even if the object has bent parts, simply by rotating the object once. In other words, the surface inspection device 1 according to the first embodiment can complete the inspection with minimal movement of the object or the device, thereby shortening the inspection time.

In addition, in the surface inspection device 1 according to the first embodiment, the inspection time can be shortened by continuously rotating the object WK to be inspected. On the other hand, in the surface inspection device 1 according to the first embodiment, the inspection accuracy can be improved by obtaining a clear image by rotating the object WK to be inspected while stopping it.

Furthermore, in the surface inspection device 1 according to the first embodiment, the defect detection processing unit 25 switches between multiple filter processes to perform image processing, making it possible to detect multiple types of surface defects with a single device.

In addition, in the surface inspection device 1 according to the first embodiment, by providing a shielding plate 153, it is possible to prevent the light emitted by the surface lighting unit 13, the upper lighting unit 141, and the lower lighting unit 142 within the inspection box 10 from being reflected by the second straight section WKr, and the reflected light from being reflected by the first straight section WKm, resulting in the erroneous determination of a non-defective product that is actually free of scratches or blemishes as a defective product.

The present invention is not limited to the above embodiment, and can be modified as appropriate without departing from the spirit and scope of the invention.

REFERENCE SIGNS LIST 1 Surface inspection device 10 Inspection box 11 Lid 12 Camera 13 Surface illumination unit 141 Upper illumination unit 142 Lower illumination unit 15 Inspected object holding unit 151 Inspection end holding unit 152 Rotation drive unit 153 Shielding plate 154 Inspected end holding unit 155 Holder 16 Base plate 20 Control box 21 Inspection unit drive unit 22 Rotation position detection sensor 23 Rotation control unit 24 Inspection control unit 25 Defect detection processing unit 30 Display 31 Operation interface 40 Robot arm WK Inspected object WKm First straight line portion WKr Second straight line portion WN Observation window WD Shooting range PA Shooting area MA Anti-reflection range L1 First window setting line L2 Second window setting line

Claims (8)

a holder for holding a first straight portion continuing from one end of a rod-shaped test object having a bent portion;
a rotation drive unit that holds the other end of the object under test or a second straight portion continuing from the other end and rotates the object under test about the axis center of the first straight portion as a rotation center axis;
a photographing unit for photographing the first straight portion;
a defect detection processing unit that detects defects in the object to be inspected based on the image captured by the imaging unit,
the holder forms a notched portion in a part of a cylinder that holds the first straight portion, and the notched portion serves as an observation window;
The photographing unit is a surface inspection device that photographs the image of the surface of the object to be inspected including the portion of the observation window. If an angle formed by a first window setting line connecting one end of the observation window in the rotation direction of the test object and the rotation central axis and a second window setting line connecting the other end of the observation window in the rotation direction of the test object and the rotation central axis is defined as a first angle,
The surface inspection device according to claim 1 , wherein the photographing unit obtains a plurality of images including images of the first straight portion at second angles smaller than the first angle. The surface inspection device according to claim 2, wherein the rotation drive unit rotates the object to be inspected continuously without stopping. The surface inspection device according to claim 2, wherein the rotation drive unit stops the rotation of the first straight section at a step of a second angle smaller than the first angle, and rotates the object to be inspected so that the second straight section does not stop within an imaging area used by the imaging unit to acquire the image. The surface inspection device according to any one of claims 1 to 4, wherein the object to be inspected has a U-shape. The surface inspection device according to any one of claims 1 to 5, wherein the defect detection processing unit has a plurality of filter processing units that apply different filter effects to the image, and the filter effect applied to the image is switched depending on the defect to be detected. The surface inspection device according to any one of claims 1 to 6, further comprising a shielding plate that blocks visibility between the first straight section and at least a portion of the second straight section and the curved section following the second straight section. The surface inspection device according to claim 7, wherein the shielding plate is attached to the rotary drive unit so that it can move up and down.

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