JP2000161937A - Surface inspection device for cylindrical object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide which can highly efficiently inspect the both end faces of cylindrical works and whole surface of the works including outer peripheral surfaces, without requiring rotation of works nor using special mechanisms for switch the front sides and rear sides of the works. SOLUTION: A surface inspection device for cylindrical object is provided with an inspection table 21, having a slope on which cylindrical works 1 roll on their outer peripheral surfaces, a passage sensor 4 which detects that the works 1 passed through the slope 21, and a stroboscopic light source 51 which illuminate the area, where the works 1 passing on the slope 21 must pass through from both sides a prescribed time, after the works 1 pass through the detecting position of the sensor 4. The inspection device is also provided with an optical unit 5, which guides reflected light rays from both end faces of the works 1 irradiated with the light from the light source 51, so that an image pickup device 6 picks up the images of both end faces of the works 1 on one screen and a computer 7, which detects the surface defects on both end faces of the works 1 from the brightness of the images of the end faces picked up by means of the device 6 and surfaces defects on the outer peripheral surfaces of the works 1 from the positions of the images of both end faces of the works 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting the surface shape of a cylindrical object by image processing.

[0002]

2. Description of the Related Art Techniques for inspecting the surface of various objects, such as industrial products and agricultural products, by image processing have become widespread. In particular, when inspecting subtle irregularities, scratches, and the like on the surface of the inspection target object (work), a specular reflection image is used. Specifically, when light is emitted from a light source to a surface to be inspected of a work and an image is taken using an optical system designed so that specularly reflected light is incident on the center of a camera lens, the work is inspected. When the target surface is in an ideal state, a bright image can be obtained over the entire area. However, when there are irregularities, scratches, etc., specular reflection light from that part does not reach the camera lens. A slightly darker image is obtained. By utilizing such characteristics of the specular reflection image, it is possible to determine the presence or absence of a defect or whether or not the defect is within an allowable range from the distribution state of light and darkness and the ratio of the obtained image, the absolute amount of a dark part, and the like. Becomes possible.

[0003]

However, in the surface inspection technique using specular reflection light as described above, in order to inspect the entire surface of the work, the inspection is repeated by the number of faces of the work, or the work is inspected. It is necessary to prepare an optical system capable of simultaneously inspecting all surfaces. For example, to inspect the entire surface of a cylindrical work, devise the optical system so that both end surfaces and the outer peripheral surface can be inspected simultaneously, or rotate the work using some mechanism, or Each side must be individually inspected by swapping the front and back. However, in the former case, the equipment configuration requires additional cost and maintenance, and in the latter case, the time required for inspection per work is longer, and the mechanical mechanism that rotates the work or swaps the front and back. Is required.

The present invention has been made in view of the above circumstances, and it is not necessary to rotate a work on both end surfaces of a columnar work and on the entire surface including an outer peripheral surface, and it is also necessary to turn the work on both sides. It is an object of the present invention to provide a device capable of performing inspection with high efficiency without using a special mechanism for replacement.

[0005]

SUMMARY OF THE INVENTION A cylindrical object surface inspection apparatus according to the present invention is an inspection apparatus for inspecting a surface defect of a cylindrical object to be inspected. An inspection table having a surface, an imaging device for imaging the end surface of the inspection target object passing on the inclined surface at a position halfway on the inclined surface, and brightness of an image of the end surface of the inspection object imaged by the imaging device And a defect detecting device for detecting a surface defect on an end face of the inspection target object by detecting the defect.

In such a surface inspection apparatus for a columnar object according to the present invention, the end face of the inspection object rolling on the inclined surface of the inspection table is imaged by the imaging device, and the image of the imaged end face of the inspection object is taken. Is detected, the surface defect on the end face of the inspection object is inspected.

A surface inspection apparatus for a cylindrical object according to the present invention is an inspection apparatus for inspecting a surface defect of an object to be inspected for a cylindrical object, wherein the inspection table has an inclined surface for rolling the object to be inspected. A sensor that detects that the inspection object has passed over the inclined surface at a first position in the middle of the inclined surface, and a second position that is lower than the first position on the inclined surface. An image pickup apparatus for picking up an end face of an object to be inspected to pass on the inclined surface after a lapse of a predetermined time from the time when the passage of the object to be inspected is detected by the sensor; A defect detection device that detects a surface defect on an outer peripheral surface of the inspection target object by detecting a position of an image of an end surface of the target object.

In the surface inspection apparatus for a cylindrical object according to the present invention, the passage of the inspection object rolling on the inclined surface of the inspection table is detected by the sensor at the first position in the middle of the inclined surface. An image of the end surface of the inspection object to be passed on the inclined surface at the second position lower than the first position is imaged by the imaging device after a predetermined time has elapsed from when the passage of the inspection object is detected by the sensor. Therefore, the outer peripheral surface of the inspection object is detected by detecting the position of the image of the end surface of the inspection object in the captured image, in other words, the time required for rolling from the first position to the second position. Are inspected for surface defects.

Further, a surface inspection apparatus for a cylindrical object according to the present invention is an inspection apparatus for inspecting a surface defect of an inspection object of a cylindrical object, wherein the inspection table has an inclined surface for rolling the inspection object. A sensor that detects that the inspection object has passed over the inclined surface at a first position in the middle of the inclined surface, and a second position that is lower than the first position on the inclined surface. An imaging device that captures an end surface of the inspection target object that should pass on the inclined surface after a lapse of a predetermined time from the time when the passage of the inspection target object is detected by the sensor; and an imaging device that captures an end surface of the inspection target object captured by the imaging device. By detecting the surface defect of the end surface of the inspection object by detecting the brightness of the image of the end surface, and detecting the position of the image of the end surface of the inspection object in the captured image, the outer peripheral surface of the inspection object is detected. Surface defects Characterized by comprising a defect detecting device for output.

The apparatus for inspecting the surface of a cylindrical object according to the present invention can simultaneously inspect the surface defect on the end surface and the surface defect on the outer peripheral surface of the inspection object.

Further, the surface inspection apparatus for a columnar object according to the present invention, in each of the above-mentioned inventions, comprises two illumination devices disposed opposite to each other across the inspection table at the second position, and each illumination device. Two beam splitters that transmit the illumination light from the side and reflect the reflected light from both end faces of the illuminated inspection object in predetermined directions, respectively, and the two intersect the reflected light from these two beam splitters Further comprising an optical unit including two reflecting mirrors for reflecting in such directions, and an optical device for reflecting the reflected light from these two reflecting mirrors in the same direction at the intersection thereof, wherein the imaging device is The apparatus is characterized in that both end faces of the inspection object are imaged on one screen by imaging reflected light from the optical device.

In such a surface inspection apparatus for a columnar object according to the present invention, both end faces of the object to be inspected are illuminated by the two illumination devices at the second position, and guided by the reflected light optical units. In addition, the imaging device can image both end faces of the inspection target object on one screen. Therefore, by combining the present invention with each of the above-described inventions, it is possible to inspect both end surfaces of the object to be inspected at the same time, and also to inspect the outer peripheral surface at the same time.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. In the following embodiments, a solid cylindrical object is used as the inspection target object (work), but may be a hollow cylindrical object or an object having a lotus root-shaped cross section.

FIG. 1 is a schematic view showing a columnar workpiece (object to be inspected) to be inspected by a columnar object surface inspection apparatus according to the present invention. The surface of such a cylindrical work 1 is constituted by both end surfaces S1 and S2 and an outer peripheral surface S3.

FIG. 2 is a schematic diagram showing an example of the configuration of a surface inspection apparatus for a columnar object according to the present invention (hereinafter referred to as the apparatus of the present invention). The inspection table 2 has a flat inclined surface 21 having a constant gradient.
Are in contact with, in other words, in a state in which the inclined surface 21 can be rolled, and are blocked by the cutout portion 3. The cutting section 3 releases the works 1 one by one by moving its piston 30 up and down according to an instruction given from the computer 7. The work 1 released by the cut-out unit 3 rolls on the inclined surface 21 of the inspection table 2 toward the downstream portion as shown by a white arrow.

A passage sensor 4 for detecting the passage of the workpiece 1 is provided at a downstream portion of the inclined surface 21 of the inspection table 2, and an optical unit 5 is further provided at a downstream portion thereof. On the other hand, an imaging device (CCD camera) 6 is arranged at an appropriate position. The passage sensor 4 is, for example,
The light-emitting element and the light-receiving element are arranged to face each other across the region on the inclined surface 21 of the inspection table 2 where the work 1 rolls, and the work 1 that rolls on the inclined surface 21 from the upstream side to the lower side interposes the two elements. The sensor is of a type in which the transmission and reception of the light beam is interrupted, and the detection result is given to the computer 7. When the work 1 passes through the position of the passage sensor 4, the computer 7 starts timing from that timing, and the time when the work 1 having a normal outer peripheral shape should pass through the optimal imaging position by the imaging device 6 has elapsed. At the timing, the strobe light sources 51R and 51L of the optical unit 5 emit light. Then, in synchronization with this timing, the computer 7 causes the imaging device 6 to perform imaging.

The image obtained by the imaging device 6 is provided to the computer 7 as digital data of, for example, 8-bit gradation.

FIG. 3 is a schematic diagram showing a detailed configuration example of the optical unit 5. The optical unit 5 is composed of two strobe light sources 51R and 51L which are arranged facing each other at an appropriate distance, beam splitters 52R and 52L, and reflecting mirrors 53R, 53L and 54.

Both strobe light sources 51R and 51L have circular light emitting portions corresponding to the shapes of both end faces of the work 1.
On the straight line connecting the two strobe light sources 51R and 51L, the light from the strobe light source 51R side is passed, but the strobe light source 51R
Beam splitter 52 that reflects light toward the side in a 45-degree direction
L is located near the strobe light source 51L, and the strobe light source 51R
The beam splitter 52R is arranged at a position close to the strobe light source 51L, which allows light from the side to pass, but reflects the light toward the strobe light source 51R in a 45-degree direction so as to be parallel to the reflected light from the beam splitter 52L. I have.

The two beam splitters 52L and 52R are arranged so that the optical path of the light reflected by the beam splitter 52L and the optical path of the light reflected by the beam splitter 52R are parallel to each other. 53L reflector,
53R is arranged. These reflecting mirrors 53L and 53R respectively reflect the reflected light from the beam splitters 52L and 52R in directions such that they intersect. 53L double reflector,
At the position where the reflected light of 53R intersects, an optical device having two reflecting surfaces, specifically a prism mirror 54, is arranged, and the two reflecting surfaces reflect light incident on each in the same direction. The angle is set as follows. And
The imaging device 6 is arranged such that the light reflected on the two reflecting surfaces of the prism mirror 54 enters the center of the lens.

The optical unit 5 having such a configuration
However, the straight line connecting the centers of the light emitting portions of the two strobe light sources 51R and 51L is aligned with the center of the work 1 rolling on the inclined surface 21 of the inspection table 2 and orthogonal to both end faces of the work 1. In addition, it is arranged at an appropriate position on the inspection table 2 downstream of the detection position of the passage sensor 4.

According to such an optical unit 5, when the work 1 exists at the center of a straight line connecting the two strobe light sources 51R and 51L on the inclined surface 21 of the inspection table 2, the two strobe light sources are used.
When 51R and 51L emit light, the light is emitted to the beam splitter 52L,
The light passes through 52R and is reflected at both end faces of the work 1 in the direction of the two strobe light sources 51R and 51L, which are the respective light emitting sources. The light is reflected by the reflecting mirrors 53L and 53R in the direction of the prism mirror 54, and finally reflected by the two reflecting surfaces of the prism mirror 54 in a direction parallel to the lens direction of the imaging device 6.
Therefore, the imaging device 6 can capture the reflected light from both end surfaces of the work 1 with one lens, so that images of both end surfaces of the work 1 can be taken on one screen.

FIG. 4 shows an image 60 obtained when the normal work 1 is imaged by the imaging device 6 through the optical unit 5 as described above.
FIG. In the optical unit 5 having the above-described configuration, since both end faces of the work 1 can be simultaneously imaged on one screen, an image 61L of the left end face of the work 1 is symmetrically displayed on the image 60 obtained by the imaging device 6. And an image 61R of the right end face. Then, in the image of the normal work 1 shown in FIG. 4, the images 61L and 61R of both end faces are both imaged to have uniform brightness by the regular reflection light from each. In FIG. 4 and FIG. 5 described later,
Reference numeral CL indicates the center line of the image 60, and arrow D1 indicates the moving direction of the work 1 in the image 60.

FIG. 5 is a schematic diagram showing an image 60 when the work 1 having a defect on the right end face is picked up by the image pickup device 6 through the optical unit 5 as described above. In the image of the work 1 having the defect shown in FIG. 5, the image 61L of the left end face having no defect is the end face 61L, 6L shown in FIG.
Although the brightness is uniform as in the 1R image, the portion F corresponding to the defective portion is dark in the image 61R on the right end face having the defect because the specularly reflected light from the defective portion does not reach the imaging device 6. The image is captured in a state (lightness is low).

FIG. 6 is a graph showing a density (brightness) waveform of an image for explaining a method of analyzing the image obtained from the end face having the defect of the work 1 by the computer 7 as described above. An image 61R of the right end face having a defect of the work 1 shown in FIG.
When sampling is performed at 56 gradations (8 bits), as shown in FIG.
Is greatly reduced in brightness. Therefore, the computer 7 can easily detect the presence or absence of a defect by slicing such a detected defect at an appropriate threshold value TH.

Incidentally, whether or not there is a defect on the outer peripheral surface of the work 1 cannot be inspected by the above-described method. However, by detecting the position of the workpiece 1 on the image 60 captured by the imaging device 6 based on the timing at which the workpiece 1 has passed the passage sensor 4, it is possible to detect the presence or absence of a defect on the outer peripheral surface of the workpiece 1. Is possible. More specifically, when there is any defect on the outer peripheral surface of the work 1, even if the rolling friction is slight, it changes in a direction to increase, as compared with the case where no defect exists.

FIG. 7 is a schematic diagram showing an image 60 when the work 1 having a defect on the outer peripheral surface is picked up by the image pickup device 6 through the optical unit 5 as described above. When the image pickup device 6 takes an image after a predetermined time from the timing when the work 1 has passed the position of the passage sensor 4, and when the work 1 having no defect on the outer peripheral surface is taken, for example, an image 60 shown in FIG. Images 61L and 61R of both end faces of work 1 at similar position P0
In the image 60 obtained by imaging the work 1 having a defect on the outer peripheral surface, the centers of the images 61L and 61R of the both end surfaces of the work 1 are located at different positions P1 as shown in FIG. It is imaged. In this way, the computer 7 detects the center position of the images 61L and 61R of the both end faces of the work 1 in the image 60 picked up by the image pickup device 6 and obtains the deviation D between them, so that the computer 7 Can be detected.

FIG. 8 is a flowchart showing a control procedure by the computer 7 when inspecting the work 1 by the apparatus of the present invention. Hereinafter, the inspection procedure executed by the computer 7 will be described with reference to this flowchart.

First, the computer 7 gives a control signal to the cutting section 3 to release one work 1 (step S1).
1), and waits until a detection signal is given from the passage sensor 4 (step S12). The work 1 released by the cutout unit 3 starts rolling downward on the inclined surface 21 of the inspection table 2, and eventually passes through the detection position of the passage sensor 4. At this time, since a detection signal is given from the passage sensor 4 to the computer 7 ("YES" in step S12), the computer 7 starts counting time (step S13).

When the clocking of the predetermined time T1 ends, in other words, when the predetermined time T1 has elapsed from the time when the workpiece 1 is detected by the passage sensor 4 ("YES" in step S13), the computer 7 emits light from the strobe light source 51. (Step S14),
At the same time, the imaging device 6 is caused to perform imaging in synchronization, and the data of the image obtained as a result is taken in (step S15).

The computer 7 which has taken in the image from the image pickup device 6 obtains the density waveform by the method as shown in FIG. Judge the presence and degree of defects
(Step S16). Further, the computer 7 determines whether or not there is a surface defect on the outer peripheral surface of the work 1 by detecting a position where both end surfaces of the work 1 are imaged in the image taken from the imaging device 7 (step S17). ), And performs processing such as outputting to a display as necessary or rejecting a work having a defect by a device not shown (step S18).

By executing the above procedure,
The computer 7 judges the presence and degree of surface defects on both end surfaces and the outer peripheral surface of one work, outputs the result to an appropriate output device, for example, a CRT display or the like, and ends the sequential procedure. It is of course possible to return the processing to step S11 and inspect the next work 1.

In the above-described embodiment, both end surfaces and the outer peripheral surface of the work 1 are inspected at the same time. However, for example, when it is not necessary to inspect the outer peripheral surface of the work 1, the passage sensor 4 is required. Is not necessary, and it is sufficient that the work 1 can be imaged at a position where an optimum image can be obtained by the imaging device 6. For example, when inspecting only the outer peripheral surface of the work 1, the optical unit 5 and the imaging device 6 It is not necessary, and it is of course possible to adopt a configuration in which two sets of sensors similar to the passage sensor 4 are arranged at appropriate intervals and the time that the work 1 passes between both sensors is measured. Furthermore,
Without using the optical unit, the imaging devices 6 are provided on both sides of the inspection table 2.
It is needless to say that a configuration is possible in which the images of both end faces of the work 1 are simultaneously taken by arranging the images to face each other.

[0034]

As described above in detail, according to the surface inspection apparatus for a columnar object according to the present invention, the end surface of the columnar inspection object is imaged while rolling on the slope. In addition, the surface inspection of the end face of the cylindrical inspection object can be performed without applying special energy from the outside.

According to the surface inspection apparatus for a cylindrical object according to the present invention, the second object is passed after a predetermined time elapses from the time when the cylindrical object to be inspected passes through the first position while rolling on the slope. By capturing an image of the end face at the position, the time required for rolling from the first position to the second position is detected, and as a result, a surface defect on the outer peripheral surface of the inspection object is inspected.

Further, according to the surface inspection apparatus for a cylindrical object according to the present invention, the defect inspection of the entire surface of the inspection object is performed by combining the surface inspection of the end surface and the outer peripheral surface of the cylindrical inspection object as described above. Since a special mechanism for rotating the object to be inspected or exchanging the front and back is not required, the cost is low and maintenance is not required.

Further, according to the surface inspection apparatus for a cylindrical object according to the present invention, both end faces of the object to be inspected are illuminated from both sides by the illumination device at the second position, and the reflection is performed by one optical unit. The image pickup apparatus can image both end faces of the inspection target object on one screen. Therefore, by combining the present invention with each of the above-described inventions, it is possible to inspect both end faces of the inspection target object at the same time and further simultaneously inspect the outer peripheral face with one imaging device.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a columnar inspection target object to be inspected by a columnar object surface inspection apparatus according to the present invention.

FIG. 2 is a schematic view showing one configuration example of a columnar object surface inspection apparatus according to the present invention.

FIG. 3 is a schematic diagram showing a detailed configuration example of an optical unit of the columnar object surface inspection apparatus according to the present invention.

FIG. 4 is a schematic diagram showing an image when a normal inspection object is imaged by the cylindrical object surface inspection apparatus according to the present invention.

FIG. 5 is a schematic diagram showing an image when the inspection object having a defect on the right end face is imaged by the columnar object surface inspection apparatus according to the present invention.

FIG. 6 is a graph showing a density waveform of an image for explaining a method of analyzing an image obtained by capturing an image of an inspection object having a defect on a right end face by the columnar object surface inspection apparatus according to the present invention.

FIG. 7 is a schematic diagram showing an image when an inspection object having a defect on an outer peripheral surface is imaged by the columnar object surface inspection apparatus according to the present invention.

FIG. 8 is a flowchart showing a procedure for inspecting an inspection target object by the columnar object surface inspection apparatus according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 object to be inspected 2 inspection table 4 pass sensor 5 optical unit 6 imaging device 7 computer 21 inclined surface of inspection table 51L, 51R strobe light source 52L, 52R beam splitter 53L, 53R reflector 54 prism mirror

Claims (4)

[Claims] 1. An inspection apparatus for inspecting a surface defect of an object to be inspected for a cylindrical object, comprising: an inspection table having an inclined surface for rolling the object to be inspected; and the inclined surface at a position halfway on the inclined surface. An imaging device for imaging an end surface of an inspection object passing therethrough; and a defect for detecting a surface defect on the end surface of the inspection object by detecting brightness of an image of the end surface of the inspection object imaged by the imaging device. A surface inspection device for a cylindrical object, comprising: a detection device. 2. An inspection apparatus for inspecting a surface defect of an inspection object of a columnar object, comprising: an inspection table having an inclined surface for rolling the inspection object; and a first position in the middle of the inclined surface. A sensor for detecting that the inspection object has passed on the inclined surface; and an end surface of the inspection object to be passed on the inclined surface at a second position below the first position of the inclined surface. An image capturing apparatus that captures an image after a lapse of a predetermined time from a point in time when the passage of the inspection target object is detected by the sensor, and by detecting a position of an image of an end face of the inspection target object in an image captured by the imaging apparatus. A defect detection device for detecting a surface defect on the outer peripheral surface of the inspection target object. 3. An inspection apparatus for inspecting a surface defect of an inspection object of a cylindrical object, comprising: an inspection table having an inclined surface for rolling the inspection object; and a first position halfway on the inclined surface. A sensor for detecting that the inspection object has passed on the inclined surface; and an end surface of the inspection object to be passed on the inclined surface at a second position below the first position of the inclined surface. An imaging device for imaging a predetermined time after the passage of the inspection object by the sensor is detected by the sensor; and detecting the brightness of an image of an end surface of the inspection object captured by the imaging device. A defect detection device that detects a surface defect on an end surface of the object and detects a surface defect on an outer peripheral surface of the inspection object by detecting a position of an image of the end surface of the inspection object in a captured image. To Surface inspection apparatus of a cylindrical object to symptoms. 4. Two illumination devices arranged opposite to each other across the inspection table at the second position, and both end surfaces of the illuminated inspection object, which transmit illumination light from each illumination device side. Two beam splitters for reflecting the reflected light from the two in a predetermined direction, two reflecting mirrors for reflecting the reflected light from these two beam splitters in a direction where the two intersect, and these two reflections An optical unit that reflects the light reflected from the mirror in the same direction at the intersection thereof, the optical unit further comprising: an imaging unit configured to image both ends of the inspection target object by imaging the reflected light from the optical device. 4. The apparatus for inspecting the surface of a cylindrical object according to claim 1, wherein the apparatus is configured to capture an image on one screen.