JP2003107009A - Apparatus and method for inspecting flaw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make clear images for detecting flaws of steel plates. SOLUTION: A polarized light for illuminating a steel plate 3 is generated with the use of a laser light including a wavelength component determined from a surface roughness Ra of the steel plate 3. The generated polarized light is guided to an optical fiber, and a polarized laser light 2 corresponding to the surface roughness of the steel plate 3 is applied to a flaw inspection illumination region of the steel plate 3. Since a larger amount of reflecting light can be caught by an imaging means 18, images for detecting flaws of the steel plate 3 are made clear.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flaw inspection device and a flaw inspection method, and is particularly suitable for use in illuminating the surface of a strip-shaped or plate-shaped steel sheet to detect flaws.

[0002]

2. Description of the Related Art In the field of iron and steel industry, it is general to image the reflected light obtained by illuminating the surface of a steel sheet to inspect the steel sheet for defects.

In the past, when illuminating the steel sheet, a metal halide lamp was used as a light source, and of the light generated from the metal halide lamp, polarized light transmitted through a polarizing plate was used as illumination light.

[0004]

However, in the above-mentioned conventional illumination method, the light generated by the metal halide lamp is used as the light source, and for example, the polarized light is constituted by extracting the S-polarized light component. Since it is not possible to obtain the amount of light, the following problems have occurred.

First, the distance between the camera for picking up an image of the steel plate and the steel plate could not be increased. Secondly, the amount of light received on the light receiving side decreases depending on the angle difference with respect to the normal line of the steel plate, and diffuse reflection reduces the angle difference,
Diffuse reflected light is less than regular reflection. Therefore, a clear image could not be obtained. Thirdly, in order to increase the amount of light, it is necessary to equip a large number of metal halide lamps, which causes a problem of high maintenance cost.

In view of the above problems, it is an object of the present invention to make a clear image for detecting flaws on a steel sheet.

[0007]

The flaw inspection apparatus of the present invention comprises:
In a flaw inspection device for performing a flaw inspection by illuminating a flaw inspection object, while generating a laser light for illuminating the flaw inspection object, while irradiating the laser light to a predetermined range of the flaw inspection object It is characterized in that an image is picked up to generate an image, and a flaw inspection is performed based on the image. Another feature of the present invention is that polarized light for illuminating the flaw inspection object is generated from the laser light, and the generated polarized light is irradiated to a predetermined range of the flaw inspection object. I am trying. Another feature of the present invention is that in a flaw inspection device that illuminates a flaw inspection object to perform a flaw inspection, a laser beam generation unit that generates a laser beam according to the surface roughness of the flaw inspection object. , A flaw inspection area illuminating means for illuminating a predetermined range of the flaw inspection object by using the laser light generated by the laser light generating means, and a flaw obtained by imaging the flaw inspection area illuminated by the flaw inspection area illuminating means. It is characterized by having an image pickup means for generating an image of the inspection area and a flaw detection means for detecting a flaw based on the image generated by the image pickup means. Another feature of the present invention is that the laser beam generating means generates a laser beam containing a wavelength component corresponding to the surface roughness of the inspection object. Another feature of the present invention is that it has polarization generating means for generating one or more polarized lights for illuminating the flaw inspection object from the laser light generated by the laser light generating means, and the polarization generating means generates the polarized light. The polarized light is irradiated onto a predetermined range of the flaw inspection object. Another feature of the present invention is that the flaw inspection region illuminating means has a plurality of base end portions connected to the laser light generating means and a tip portion directed toward a predetermined range of the flaw inspection object. Comprised of optical fibers, the polarized light generated by the polarized light generation means is guided from the base end portions of the plurality of optical fibers, and emitted from the distal end portion toward a predetermined range of the flaw inspection target to illuminate. It has a feature. Another feature of the present invention is that the polarization change amount identification means for identifying the change in polarization when the polarization generated by the polarization generation means passes through the plurality of optical fibers from the length of the plurality of optical fibers. A polarization change canceling means for canceling the change in polarization when passing through the plurality of optical fibers is generated by generating polarized light for canceling the change in polarization identified by the polarization change amount identifying means. It is characterized in that the polarized light, which has been compensated for the change occurring when passing through the plurality of optical fibers, is output to the base ends of the plurality of optical fibers.

The flaw inspection method of the present invention is a flaw inspection method for illuminating a flaw inspection object to perform a flaw inspection, wherein a laser beam for illuminating the flaw inspection object is generated and the laser light is used for the flaw inspection. It is characterized in that an image is generated by imaging while irradiating a predetermined range of the inspection object, and the flaw inspection is performed based on the image. Another feature of the present invention is that polarized light for illuminating the flaw inspection object is generated from the laser light, and the generated polarized light is irradiated to a predetermined range of the flaw inspection object. I am trying. Where the present invention and other features are, in a flaw inspection method for performing a flaw inspection by illuminating a flaw inspection object, a laser light generation process for generating a laser beam according to the surface roughness of the flaw inspection object, A flaw inspection area illumination process for illuminating a predetermined range of the flaw inspection object using the laser light generated by the laser light generation processing, and a flaw inspection in which a flaw inspection area illuminated by the flaw inspection area illumination process is imaged. It is characterized by performing an image pickup process for generating an image of a region and a flaw detection process for detecting a flaw based on the image generated by the image pickup process. Another feature of the present invention is that the laser beam generation process generates a laser beam containing a wavelength component corresponding to the surface roughness of the inspection object. Another feature of the present invention is that a polarized light generated by the polarized light generation process is generated by performing a polarized light generation process for generating one or more polarized lights for illuminating the flaw inspection object from the laser light generated by the laser light generation process. Is irradiated onto a predetermined range of the flaw inspection object. According to another feature of the present invention, in the flaw inspection area illumination processing, the polarized light generated by the polarized light generation processing is connected to a laser light generation means for generating a laser light at a base end portion thereof, and a tip end portion thereof is set to the above It is characterized in that light is guided from the base end portions of a plurality of optical fibers directed to a predetermined range of the flaw inspection target, and emitted from the tip end toward a predetermined range of the flaw inspection target to illuminate. . Another feature of the present invention is that the polarization generated when the polarization generation processing passes through the plurality of optical fibers, and the polarization change amount identification processing for identifying from the lengths of the plurality of optical fibers. The polarized light is generated by canceling the change in polarization identified by the polarization change amount identification processing, and the polarization change cancellation processing is performed to cancel the change in polarization when passing through the plurality of optical fibers. It is characterized in that the polarized light, which has been compensated for the change occurring when passing through the optical fiber, is output to the base ends of the plurality of optical fibers.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a flaw inspection apparatus and a flaw inspection method of the present invention will be described with reference to the accompanying drawings. 1 and 2 are views showing an embodiment of the present invention and showing an example of a schematic configuration of a flaw inspection apparatus, and FIG. 1 is a perspective view showing an example of a schematic configuration of a flaw inspection apparatus, FIG.
FIG. 3 is a sectional view of the flaw inspection device. Further, FIG. 3 is a block diagram showing the configuration of the flaw inspection apparatus according to the present embodiment.

1 to 3, the flaw inspection apparatus 1 according to the present embodiment irradiates a flaw inspection object 3 such as a steel plate by irradiating a polarized laser beam 2 generated as described later. And the polarized laser light 2
And a captured image processing unit 5 that processes the captured image while imaging the reflected light obtained by irradiating the defect inspection target 3 with the image.

As shown in the block diagram of FIG. 3, the illumination processing section 4 has a laser light generator 9, a flaw inspection area illuminating means 10, and a condensing means 11. Further, the laser light generator 9 is a laser light generating means 6
A polarization generation means 7 and a polarization change cancellation means 8 are included in the flaw inspection area illumination means 10.

The laser beam generator 9 is a well-known laser, and is arranged at a position where the polarized laser beam 2 is incident on the flaw inspection object 3 at a predetermined angle θ (FIG. 2).
And FIG. 5).

The laser light generating means 6 provided in the laser light generator 9 is, for example, a laser resonator,
A laser beam having a predetermined wavelength λ is generated. here,
The predetermined wavelength λ is a value predetermined by the representative value Ra of the surface roughness of the steel sheet that is the flaw inspection object 3.

The polarized light generation means 7 is a laser light generation means 6
In order to illuminate the flaw inspection object 3, one or more polarized lights are generated from the laser light generated by.

The polarization amount canceling means 8 is the polarization generating means 7 described above.
The amount of change caused by the polarized light generated by the above-described method when passing through an optical fiber which is a defect inspection area illuminating device, which will be described later, is identified in advance, and the amount of change in the polarized light generated when passing through the optical fiber is compensated.

FIG. 4 is a diagram showing an example of a specific configuration of the laser light generator 9. As shown in FIG.
The laser light generated by the laser light generating means 6 is
From the laser light that has been split by the half mirror (or beam splitter) 12 and is split as described above, S polarization is generated by the S polarization generation compensator 13 and P polarization is generated by the P polarization generation compensator 14 (while compensating for the polarization amount generated in the subsequent stage. ) Generate each.

As described above, the S polarization generation compensator 13 is used.
The (P polarization generation compensator 14) has the functions of both the polarization generation means 7 and the polarization amount cancellation means 8, respectively. In addition,
The P-polarized light may be reflected by the total reflection mirror 15 in a predetermined direction and then output to the polarization amount canceling means 8 (P-polarization generation compensator 14).

As described above, the laser light generated by the laser light generating means 6 is
Since it has high energy, even if it is dispersed
It is possible to obtain a sufficient amount of light to illuminate the. Therefore, a sufficient amount of light for illuminating the flaw inspection target 3 can be obtained without providing a large number of light sources, and the laser light generator 9 can be downsized.

However, for example, two laser resonators serving as the laser light generating means 6 may be provided and S-polarized light and P-polarized light may be generated from the laser light generated by each laser resonator.

As described above, the polarized light generated by the polarized light generating means 7 is changed by passing through the optical fiber which is the flaw inspection area illuminating means which will be described later. Therefore, in the present embodiment, the amount of change in the polarization is previously identified from the length of the optical fiber, and the polarization change canceling means 8 compensates the polarized light for canceling the amount of change in the polarization. There is. As a result, the polarized laser light 2 in consideration of the amount of change in polarization caused by passing through the optical fiber is emitted from the laser generator 9 to the flaw inspection object illuminating means 10.

The flaw inspection area illuminating means 10 is specifically,
A plurality of optical fibers 10 coupled with the laser generator 9 to guide the polarized laser light 2 emitted from the laser generator 9.

As shown in FIG. 2, the optical axes of the plurality of optical fibers 10 are (90) with respect to the flaw inspection object 3.
−θ) ° (θ is the incident angle of the polarized laser light 2), and the tip thereof extends in the width direction of the flaw inspection object 3 (W direction in FIG. 1). They are formed side by side evenly.

The flaw inspection area illuminating means 10 having such a structure.
Thereby, it becomes possible to uniformly irradiate the polarized laser light 2 emitted from the laser light generator 9 in the width direction of the flaw inspection object 3.

The condensing means 11 is specifically a condensing lens, and focuses the polarized laser light 2 emitted from the tip of the flaw inspection area illuminating means 10 on the flaw detection position of the flaw inspection object 3. The surface is illuminated linearly.

On the other hand, the picked-up image processing section 5 has a moving state detection means 16, an image pickup control means 17, and an image pickup means 18.
And an image processing unit 19 and a monitor 20.

The movement status detecting means 16 is arranged in the longitudinal direction (see FIG. 1).
The movement status of the flaw inspection object 3 moving in the L direction) is detected, and the movement status detection signal D1 is generated.

The image pickup control means 17 judges the start and end of the flaw inspection of the flaw inspection object 3 based on the movement state detection signal D1, and the image pickup means 18 and the laser light generator 9 of the flaw detection object 3 are determined according to the result of the determination. Control movements.

The image pickup means 18 is, for example, a linear array camera, and is arranged on the optical path of the polarized laser light 2 which is irradiated from the illumination processing portion 4 and reflected by hitting the flaw inspection object 3 as shown in FIG. The flaw detection range of the flaw inspection object 3 illuminated by the polarized laser light 2 is imaged to generate an image signal D2.

The image processing means 19 takes in the image signal D2 generated by the image pickup means 18 and performs predetermined image processing, and generates an image processing signal D3 for displaying the image processing result on the monitor 20, for example.

Next, the operation of the flaw inspection apparatus 1 of this embodiment will be described with reference to the flowchart of FIG.

First, in the first step S1, the image pickup control means 17 waits until the flaw inspection object 3 is detected based on the movement state detection signal D1 output from the movement state detection means 16, and then the flaw inspection object is detected. When the object 3 is detected, the process proceeds to step 2 and the laser light generator 9 and the imaging means 18
The linear array camera is activated.

Next, in step S3, the polarized laser beam 2 is generated by the laser beam generator 9 as described above.
To illuminate the flaw inspection target 3.

Next, in step S4, the image pickup means 1
8 is used to image the flaw inspection object 3 moving in the longitudinal direction (for example, the L direction in FIG. 1).

Next, in step S5, the image processing means 19 waits until the image signal D2 is input from the image pickup means 18, and when the image signal D2 is input, the process proceeds to step S6, in which the defect is detected based on the image signal D2. Image processing for detecting a flaw on the surface of the inspection object 3 is performed, and an image processing signal D3 for causing the monitor 20 to display information necessary for the defect inspection, such as an actual image of the defect inspection object 3, is generated. Output to the monitor 20. Information necessary for the flaw inspection is displayed on the monitor 20 based on the image processing signal D3.

Next, in step S7, the image pickup control means 17 determines whether or not the flaw inspection of the flaw inspection object 3 is completed based on the movement state detection signal D1 detected by the movement state detection means 16. To do.

As a result of the judgment, if the flaw inspection is completed, the process proceeds to step S8, and the image pickup control means 17 stops the operations of the laser light generator 9 and the image pickup means 18. on the other hand,
If the flaw inspection has not been completed, return to step S5,
The processes from step S5 to step S7 are repeated until the flaw inspection is completed.

As described above, in the present embodiment, the flaw inspection is performed based on the image generated by imaging while illuminating the predetermined range of the flaw inspection object 3 with the laser light. As described above, it is possible to obtain a sufficient amount of light for performing the flaw inspection without providing a large number of light sources. As a result, the device can be downsized, and the cost of the device such as the initial cost and maintenance cost of the device can be reduced.

Further, from the representative value Ra of the surface roughness of the steel sheet as the flaw inspection object 3, the laser beam 2 containing the wavelength λ (λ << Ra) component which can favorably perform the flaw inspection is generated. Therefore, it is possible to illuminate the defect inspection target 3 by using the laser light that is appropriately reflected on the surface of the defect inspection target 3. As a result, more reflected light is captured by the image pickup means 18
The image of the flaw inspection object 3 can be satisfactorily generated and the flaw inspection can be satisfactorily performed, and a clear image can be obtained even when diffuse reflection is large.

Since the polarized light required for illumination is generated from the laser beam and the generated polarized light is used to illuminate the flaw inspection object 3, a polarized light stronger than the polarized light obtained from the conventional metal halide lamp is obtained. be able to. As a result, a clearer image can be generated by the image pickup means 18 and the flaw inspection can be performed.

Further, the optical fiber 1 required for the above illumination
The change in polarization that occurs when passing 0 is identified in advance,
Since the polarized light that cancels the change is compensated for the polarized light when passing through the optical fiber 10, the polarized light that is more suitable for illuminating the flaw inspection target 3 is used for the flaw inspection target. The object 3 can be illuminated. As a result, a clearer image can be generated by the image pickup means 18 and the flaw inspection can be performed.

(Other Embodiments of the Present Invention) In order to operate various devices in order to realize the functions of the above-mentioned embodiments, the above-mentioned embodiment is applied to a computer in an apparatus or system connected to the various devices. To supply the program code of software for realizing the functions of the
Alternatively, those implemented by operating the above various devices according to the program stored in the MPU) are also included in the scope of the present invention.

Further, in this case, the program code itself of the software realizes the function of the above-described embodiment, and the program code itself and means for supplying the program code to the computer,
For example, a recording medium storing such program code constitutes the present invention. As a recording medium for storing the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-RO.
M, a magnetic tape, a non-volatile memory card, a ROM, or the like can be used.

In addition, the computer executes the supplied program code to realize the functions of the above-described embodiment, and the program code runs on the OS (operating system) or another computer. Such program codes are included in the embodiments of the present invention even when the functions of the above-described embodiments are realized in cooperation with application software or the like.

Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the function expansion board or function expansion unit is instructed based on the instruction of the program code. The present invention also includes a case where the CPU and the like included in the above perform some or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

[0045]

As described above, according to the present invention, an image is formed by taking an image of a flaw inspection object while illuminating the flaw inspection object with laser light, and performing a flaw inspection based on the image. Since it is performed, a lot of reflected light can be obtained without providing a large number of light sources as in the case of illuminating with a conventional metal halide lamp, and it is possible to take a clear image and perform a flaw inspection. it can.

Another feature of the present invention is that the laser light having a wavelength corresponding to the surface roughness of the inspection object is generated, so that the surface roughness of the inspection object is affected. It is possible to pick up a clear image and perform a flaw inspection without the need for it.

Further, according to another feature of the present invention, since the polarized light required for illumination is generated from the laser light, it is possible to obtain a polarized light stronger than that obtained when illumination is performed using the conventional metal halide lamp. it can. This makes it possible to take a clearer image and perform a flaw inspection.

According to another feature of the present invention, the amount of change in polarization due to passage of the optical fiber is identified and the amount of change is canceled out. Therefore, polarized light more suitable for illuminating the flaw inspection target is used. The flaw inspection target can be illuminated. This makes it possible to take a clearer image and perform a flaw inspection.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention and showing an example of a schematic configuration of a flaw inspection apparatus.

FIG. 2 is a sectional view showing an embodiment of the present invention and showing an example of a schematic configuration of a flaw inspection apparatus.

FIG. 3 is a block diagram of a flaw inspection device according to the embodiment of the present invention.

FIG. 4 is a diagram showing an embodiment of the present invention and showing an example of a specific configuration of a laser light generator.

FIG. 5 is a diagram showing an embodiment of the present invention and showing how polarized laser light is reflected by a flaw inspection object.

FIG. 6 is a flowchart showing the operation of the flaw inspection device according to the embodiment of the present invention.

[Explanation of symbols]

1 Defect inspection device 2 polarized laser light 3 Defect inspection target 4 Lighting processing section 5 Captured image processing unit 6 Laser light generation means 7 Polarization generation means 8 Polarization change cancellation means 9 Laser light generator 10 Defect inspection area illumination means 11 Light collecting means 12 Half mirror or beam splitter 13 S polarization generation compensator (having the functions of 7 and 8) 14 P polarization generation compensator (having the functions of 7 and 8) 15 Total reflection mirror 18 Imaging means 20 monitors

Claims (14)

[Claims] 1. A flaw inspection apparatus for illuminating a flaw inspection object to perform a flaw inspection, wherein a laser beam for illuminating the flaw inspection object is generated, and the laser light is used for a predetermined inspection of the flaw inspection object. A flaw inspection apparatus characterized in that an image is generated by imaging while irradiating a range, and a flaw inspection is performed based on the image. 2. The polarized light for illuminating the flaw inspection object is generated from the laser light, and the generated polarized light is irradiated to a predetermined range of the flaw inspection object. The flaw inspection device described. 3. A flaw inspection apparatus for illuminating a flaw inspection object to perform a flaw inspection, comprising: a laser light generation means for generating a laser light according to the surface roughness of the flaw inspection object; and the laser light generation means. A flaw inspection area illuminating means for illuminating a predetermined range of the flaw inspection object by using the laser light generated by, and an image of the flaw inspection area obtained by imaging the flaw inspection area illuminated by the flaw inspection area illuminating means. A flaw inspection apparatus comprising: an image pickup unit for performing flaw detection and a flaw detection unit for detecting a flaw based on an image generated by the image pickup unit. 4. The flaw inspection apparatus according to claim 3, wherein the laser light generation means generates laser light containing a wavelength component corresponding to the surface roughness of the inspection object. 5. A polarization generation means for generating at least one polarization for illuminating the flaw inspection object from the laser light generated by the laser light generation means, wherein the polarization generated by the polarization generation means is subjected to the flaw inspection. The flaw inspection apparatus according to claim 3 or 4, which irradiates a predetermined range of the object. 6. The flaw inspection area illuminating means comprises a plurality of optical fibers having a base end portion connected to the laser light generating means and a tip portion directed to a predetermined range of the flaw inspection object. 6. The polarized light generated by the polarized light generation means is guided from the base end portions of the plurality of optical fibers, and emitted from the tip end portion toward a predetermined range of the flaw inspection target object for illumination. The flaw inspection device described in. 7. The change in polarization when the polarization generated by the polarization generation means passes through the plurality of optical fibers,
Polarization change amount identification means for identifying from the lengths of the plurality of optical fibers, and polarized light that cancels the change in polarization identified by the polarization change amount identification means, and changes in polarization when passing through the plurality of optical fibers. And a polarization change canceling means for canceling the polarization change canceling means for outputting the polarized light compensated for the change occurring when passing through the plurality of optical fibers by the polarization change canceling means to the base ends of the plurality of optical fibers. The flaw inspection apparatus according to item 6. 8. A flaw inspection method for illuminating a flaw inspection object by performing a flaw inspection, wherein a laser beam for illuminating the flaw inspection object is generated, and the laser light is used for a predetermined inspection of the flaw inspection object. A flaw inspection method characterized in that an image is generated by imaging while irradiating a range, and a flaw inspection is performed based on the image. 9. The polarized light for illuminating the flaw inspection object is generated from the laser light, and the generated polarized light is applied to a predetermined range of the flaw inspection object. Defect inspection method described. 10. A flaw inspection method for illuminating a flaw inspection object to perform a flaw inspection, comprising: a laser beam generation process for generating a laser beam according to the surface roughness of the flaw inspection target; and the laser beam generation process. A flaw inspection area illumination process for illuminating a predetermined range of the flaw inspection target by using the laser light generated by, and an image of the flaw inspection region obtained by imaging the flaw inspection region illuminated by the flaw inspection area illumination process. A flaw inspection method comprising: performing an image pickup process for performing the flaw detection process; and a flaw detection process for detecting a flaw based on the image generated by the image pickup process. 11. The flaw inspection method according to claim 10, wherein the laser beam generation process generates a laser beam containing a wavelength component corresponding to the surface roughness of the inspection object. 12. A polarized light generation process for generating at least one polarized light for illuminating a flaw inspection target from the laser light generated by the laser light generation process, and the polarized light generated by the polarized light generation process is subjected to the flaw inspection target. 11. Irradiating a predetermined area of the object.
Or the flaw inspection method according to item 11. 13. The flaw inspection area illumination processing, wherein the polarized light generated by the polarized light generation processing is connected to a laser beam generation means for generating a laser beam at a base end thereof, and has a tip end thereof for the defect inspection object. 13. The light is guided from the base end portions of a plurality of optical fibers directed in a predetermined range, and is emitted from the tip end portion toward a predetermined range of the flaw inspection object to illuminate it. Flaw inspection method. 14. A polarization change amount identification process for identifying a change in polarization when the polarization generated by the polarization generation process passes through the plurality of optical fibers from the lengths of the plurality of optical fibers, and the polarization change amount identification. Generates polarized light that cancels the change in polarization identified by processing, performs polarization change cancellation processing that cancels the change in polarization when passing through the multiple optical fibers, and passes through the multiple optical fibers by polarization change cancellation processing. 14. The polarized light, which is compensated for the change caused at the time, is output to the base ends of the plurality of optical fibers.
Defect inspection method described in.