JP4023295B2 - Surface inspection method and surface inspection apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface inspection method and a surface inspection apparatus for a steel pipe as an inspection object.
[0002]
[Prior art]
In the manufacturing process of the seamless steel pipe, the billet is processed into a steel pipe having a predetermined size by hot working, and then passed through a straightener to remove the bending of the steel pipe. At that time, if there are defects such as holes or wrinkles in the steel pipe after hot working, the steel pipe may be damaged in the straightener, and the sensor part of the ultrasonic flaw detector and magnetic flaw detector performed thereafter will be damaged. There are things to do. Therefore, it is necessary to inspect the steel pipe for holes, wrinkles or the like that cause such troubles before passing through the straightener, and to prevent the steel pipe having such holes or wrinkles from passing through the straightener.
[0003]
Therefore, an apparatus for inspecting the shape of the steel pipe after hot working is installed to inspect the surface of the steel pipe. In many cases, an optical inspection apparatus using a relatively inexpensive CCD camera or the like is used for this apparatus (for example, see Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-37949 (FIG. 1)
[0005]
[Problems to be solved by the invention]
In the optical inspection device, if the position of the steel pipe to be inspected shifts, accurate measurement becomes difficult, so a line dedicated for inspection is provided and fixed with a chuck so that the position of the steel pipe is constant, Then, it is necessary to rotate the steel pipe in the circumferential direction. Therefore, since it is necessary to modify the production line, a considerable cost is required, and a separate inspection process may be required.
[0006]
Moreover, it is also possible to install an optical inspection apparatus in the production line in which a normal steel pipe is conveyed. FIG. 8 is a schematic diagram for explaining a conventional inspection process. In the figure, reference numeral 5 denotes a steel pipe 5 that is conveyed while rotating on the conveyor roller 3. Light is irradiated to the steel pipe 5 that is the inspection object by the illumination 2, and the reflected light is imaged by the one-dimensional camera 1. When defects such as wrinkles, dirt, dents, wrinkles, etc. are generated on the surface of the steel pipe 5, the reflection intensity becomes weak, so that the defect is detected by measuring the brightness of the reflected light by the one-dimensional camera 1. be able to. When a defect is detected, generally, a reference level for the detected luminance is set, and when a luminance lower than the reference level is detected, it is determined that a defect has been detected.
[0007]
However, since the steel pipe 5 to be conveyed is not fixed in a normal production line, the position of the steel pipe 5 fluctuates on the skewer 3. For this reason, the way in which the light 2 strikes the light varies depending on the position of the steel pipe 5. At this time, if a fixed reference level is used when detecting a defect, there is a case where an erroneous detection of the defect may occur, resulting in a problem that the accuracy of the inspection is deteriorated.
[0008]
The present invention has been made in view of such circumstances, and irradiates an inspection object with light, measures the amount of reflected light from the first region, and calculates a reference luminance as a reference when detecting a defect. Then, the brightness of the reflected light from the second region is measured and compared with the reference brightness, and based on the comparison result, the presence or absence of a defect on the surface of the inspection object is detected. An object of the present invention is to provide a surface inspection method and a surface inspection apparatus that can detect defects on the surface of an inspection object at a low cost even when they are displaced during inspection.
[0009]
Another object of the present invention is to use a two-dimensional image sensor that obtains a two-dimensional image by imaging an inspection object as the first light receiving means, and measures the amount of reflected light based on the obtained two-dimensional image. Thus, an object of the present invention is to provide a surface inspection apparatus capable of detecting defects on the surface of an inspection object even when the position of the inspection object is shifted during inspection.
[0010]
Still another object of the present invention is to use a one-dimensional image pickup device that obtains a one-dimensional image by imaging an inspection object as the second light receiving means, and measures the brightness of reflected light based on the obtained one-dimensional image. It is in providing the surface inspection apparatus which can detect the defect of the surface of a test target object accurately by setting it as a structure.
[0011]
Still another object of the present invention is to provide a surface inspection apparatus capable of detecting a defect of an inspection object under various environmental conditions by adopting a configuration in which the second light receiving means removes light in a predetermined wavelength range. is there.
[0012]
Still another object of the present invention is to detect a wrinkle of an inspection object based on the calculated first reference luminance, and to detect a plurality of types of defects by detecting holes generated in the inspection object based on the second reference luminance. An object of the present invention is to provide a surface inspection apparatus capable of detecting a single measurement.
[0013]
Still another object of the present invention is to provide a surface inspection apparatus that can easily detect defects on the entire surface of an inspection object by further comprising means for conveying the inspection object while rotating it. It is in.
[0014]
[Means for Solving the Problems]
The surface inspection method according to the first invention is an inspection object. For cylindrical or columnar steel Irradiate with light, Steel Based on the amount of light received. Steel In the surface inspection method for detecting the presence or absence of surface defects, The steel material is imaged with a two-dimensional camera to obtain a two-dimensional image, the amount of light from the first region of the steel material surface is measured based on the obtained two-dimensional image, and the steel material is imaged with a one-dimensional camera. A dimensional image is acquired, based on the acquired one-dimensional image, the luminance in the second region on the steel material surface that is narrower than the first region is measured, and based on the amount of light from the first region One or more reference luminances used for defect detection Set and set Reference brightness and In the measured second region The brightness is compared, and based on the comparison result, On steel surface The presence or absence of a defect is detected.
[0015]
In the first invention, the inspection object is irradiated with light, the reflected light is received from the first region on the surface of the inspection object, the light amount is measured, and the defect is detected based on the measured light amount. Calculate the reference brightness, receive the reflected light from the second area on the surface of the inspection object, measure the brightness, compare the calculated reference brightness with the measured brightness, and based on the comparison result, The presence or absence of defects on the object surface is detected. In the manufacturing process of the seamless steel pipe, in order to remove the bending of the steel pipe, the steel pipe is conveyed while being rotated on a scroll roller provided on a conveyor, and is put into a straightener. In order to prevent damage on the straightener, it is necessary to inspect defects on the surface of the steel pipe. However, when the present invention is applied, even if the position of the steel pipe fluctuates on the scroll roller, a relatively wide area Since the reference luminance for defect detection can be calculated by obtaining the amount of light from the reflected light from the (first region), such as wrinkles, dirt, wrinkles, etc. on the surface of the steel pipe without being affected by fluctuations in the steel pipe position Defects can be detected. Further, the production line needs to be improved as much as possible, and an inspection-dedicated rotating device such as a turning roller and a chucking device is not necessary, so that an increase in cost can be suppressed.
[0016]
The surface inspection apparatus according to the second invention is an inspection object. For cylindrical or columnar steel A light irradiator for irradiating light, and Steel Based on the amount of light received. Steel In a surface inspection apparatus provided with a detection part which detects the presence or absence of a surface defect, the detection part is the above-mentioned A two-dimensional camera that captures a steel material to obtain a two-dimensional image, and a first region on the surface of the steel material based on the two-dimensional image obtained by the two-dimensional camera. First measuring means for measuring the amount of light, and In a second area on the surface of the steel material that is narrower than the first area, based on a one-dimensional camera that captures a steel material and obtains a one-dimensional image, and a one-dimensional image obtained by the one-dimensional camera. Based on the second measuring means for measuring the luminance and the light quantity measured by the first measuring means, one or a plurality of reference luminances used for defect detection are obtained. Setting means for setting and the setting means Comparing means for comparing the reference brightness with the brightness measured by the second measuring means, and based on the comparison result of the comparing means, On steel surface And detecting means for detecting the presence or absence of a defect.
[0017]
In the second invention, the inspection object is irradiated with light, the reflected light is received from the first area on the surface of the inspection object, the light amount is measured, and the defect is detected based on the measured light amount. Calculate the reference brightness, receive the reflected light from the second area on the surface of the inspection object, measure the brightness, compare the calculated reference brightness with the measured brightness, and based on the comparison result, The presence or absence of defects on the object surface is detected. For example, when applied to the detection of defects in the steel pipe manufacturing process, even if the position of the steel pipe fluctuates on the scroll roller, the amount of light reflected from a relatively wide area (first area) is obtained, Since the reference luminance for defect detection can be calculated, defects such as wrinkles, dirt, wrinkles, etc. on the surface of the steel pipe can be detected without being affected by fluctuations in the position of the steel pipe. Further, the production line needs to be improved as much as possible, and an inspection-dedicated rotating device such as a turning roller and a chucking device is not necessary, so that an increase in cost can be suppressed.
[0019]
In the present invention, The amount of reflected light is measured based on the obtained two-dimensional image. Therefore, an image of an inspection object is imaged over a wide range using an image sensor such as a two-dimensional CCD, and the amount of reflected light is measured. Further, by using the measured light amount, a reference luminance that can be handled even when the position of the inspection object fluctuates is calculated.
[0021]
In the present invention, Based on the obtained one-dimensional image, the brightness of the reflected light is measured. Therefore, the defect on the inspection object surface is detected with high resolution.
[0024]
First 3 The surface inspection apparatus according to the invention According to the second invention In the surface inspection apparatus, the detection means is based on the first reference luminance calculated by the calculation means. Steel The upper wrinkle is detected, and the second reference brightness Steel Arise in Hole It is made to detect.
[0025]
First 3 In the invention, according to the first reference luminance Steel Since the upper wrinkle is detected and a hole generated in the inspection object is detected based on the second reference luminance, the type of defect is determined.
[0026]
First 4 The surface inspection apparatus according to the invention According to the second or third invention In the surface inspection apparatus, Steel It further comprises means for conveying while rotating.
[0027]
First 4 In the invention, since a means for conveying the object to be inspected while being rotated is provided, for example, in the steel pipe manufacturing process, it is possible to detect defects for the entire circumference and the entire length of the steel pipe from one direction.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
1 and 2 are schematic configuration diagrams of a surface inspection system according to the present embodiment. In the figure, reference numeral 50 denotes a cylindrical steel pipe that is conveyed on the conveyor 30 in the direction of the white arrow in the figure, and irradiates the steel pipe 50 with light using three halogen lamps 13, 13, 13. Then, the steel pipe 50 is photographed by the one-dimensional camera 11 and the two-dimensional camera 12 in order to detect defects on the surface of the steel pipe 50.
The conveyor 30 is provided with a plurality of skewers 31, 31,... Having a predetermined angle with respect to the conveying direction of the steel pipe 50. By conveying the steel pipe 50 over the rollers 31, 31,. The steel pipe 50 is rotated according to the angle.
A straightener (not shown) is installed at the subsequent stage of the conveyor 30. In this embodiment, the one-dimensional camera 11 and the two-dimensional camera 12 detect a defect that causes the steel pipe 50 to be damaged by the straightener. I am doing so.
[0029]
The two-dimensional image obtained by photographing with the two-dimensional camera 12 is sent to the image processing device 22 and displayed on the monitor 23, and the light quantity or average luminance value of the two-dimensional image is calculated and two-dimensional. It is transmitted to the signal processing device 21 as luminance information of the image. A one-dimensional image obtained by photographing with the one-dimensional camera 11 is sent to the signal processing device 21. The signal processing device 21 analyzes the one-dimensional image with reference to the luminance information from the image processing device 22 and detects a defect in the steel pipe 50. The defects of the steel pipe 50 detected by the signal processing device 21 are, for example, wrinkles, wrinkles, holes, dirt, and the like, and these defects are detected based on the luminance of the one-dimensional image. When there are wrinkles, wrinkles, holes, dirt, etc. on the surface of the steel pipe 50, the amount of reflected light decreases in those areas. A reference level is set in advance for the luminance value detected by the one-dimensional camera 11, and it is determined that a defect such as a flaw has been detected when a luminance value lower than the reference level is obtained. In addition, since the amount of reflected light from the surface of the steel pipe 50 varies depending on the position of the steel pipe 50 on the scroll roller 31 or the surface temperature of the steel pipe 50, in the present embodiment, an average is obtained for a relatively wide range on the steel pipe 50. The luminance value is measured using the two-dimensional camera 12, and the reference level is corrected based on the measured luminance value.
[0030]
The one-dimensional image from the one-dimensional camera 11 input to the signal processing device 21 is converted into a video signal such as an NTSC signal by the scan converter 24 and then sent to the monitor 24 and the video printer 25. The monitor 24 displays an image based on the received video signal, and the video printer 25 forms an image on a recording sheet based on the received video signal.
In addition, encoders 32, 32,... Are attached to the respective scroll rollers 31, 31,..., So that the rotation of the scroll rollers 31, 31,. Since the next steel pipe 50 is being conveyed during the processing by the straightener and the progress of the steel pipe 50 may stop during the inspection, the progress of the steel pipe 50 is monitored by monitoring the rotation of the scroll rollers 31, 31,. Detection is made so that no erroneous inspection occurs in the one-dimensional camera 11 or the two-dimensional camera 12.
Further, in order to prevent the steel pipe 50 from jumping out from the scrollers 31, 31,..., Side guides 33, 33 are provided on both sides of the scrollers 31, 31,. Moreover, since the side guides 33 and 33 are provided, the influence by disturbance light is prevented.
[0031]
The three halogen lamps 13, 13, 13 are installed at a height of 1300 mm from the steel pipe 50 with an interval of 800 mm in the conveying direction of the steel pipe 50. Since the temperature of the steel pipe 50 to be conveyed is 1000 ° C. or higher and may emit radiation light, the halogen lamp 13 needs to have an illuminance brighter than the radiation light from the steel pipe 50, and It is desirable that a predetermined range can be irradiated with light uniformly. Between the two halogen lamps 13 and 13 on the entry side of the steel pipe 50, a two-dimensional camera 12 is installed at a height of 2000 mm from the steel pipe 50, and between the two halogen lamps 13 and 13 on the exit side of the steel pipe 50. The one-dimensional camera 11 is installed at the same height as the two-dimensional camera 12.
The angle in the vertical plane between the one-dimensional camera 11 and the halogen lamp 13 is preferably 45 degrees. The three halogen lamps 13 do not necessarily have to be installed at the same angle, are installed at 45 degrees for detecting wrinkles in the steel pipe 50, and are installed at the same angle as the one-dimensional camera 11 for detecting holes in the steel pipe 50. It is also possible to install at 90 degrees for detecting the depression of the steel pipe 50.
The two-dimensional camera 12 is desirably installed at the same angle as that of the one-dimensional camera 11. If the entire surface of the steel pipe 50 can be detected, the angles of both may be shifted. The axes of the cameras 11 and 12 are set so as to be at a predetermined angle with respect to the surface of the steel pipe 50 when the steel pipe 50 is positioned at the center of the scroll roller 31, It is desirable to make the surface of the steel pipe 50 entering as uniform as possible.
[0032]
Thus, by arranging the one-dimensional camera 11, the two-dimensional camera 12, and the halogen lamps 13, 13, 13, it is possible to make the horizontal field of view of the one-dimensional camera 11 uniform within a range of 2500 mm. I understood.
In consideration of cost, performance, and maintainability, the arrangement as described above is desirable, but other arrangements can be taken by changing the illuminance, type, etc. of the halogen lamp 13. That is. In addition, since the steel pipe 50 is conveyed while rotating on the scroll rollers 31, 31,..., Each camera 11, 12 may be installed one by one, but by measuring by changing the angle with the halogen lamp 13. , Wrinkles, wrinkles, etc. can be detected accurately, a plurality of one-dimensional cameras 11 and two-dimensional cameras 12 may be installed, and the angle with the halogen lamp 13 and the number of halogen lamps 13 change accordingly. You may let them.
[0033]
FIG. 3 is a schematic diagram for explaining the photographing principle of the one-dimensional camera 11. The one-dimensional camera 11 includes a light-receiving unit made up of light-receiving elements such as a CCD (Charge Coupled Device) arranged in a one-dimensional shape, and as shown in FIG. Take a picture of length 2500mm). The scanning cycle of the one-dimensional camera 11 is very short, and the steel pipe 50 that is an inspection object advances while rotating on the scroll rollers 31, 31,. You can shoot.
The one-dimensional camera 11 in the present embodiment has 4096 light-receiving elements arranged in a one-dimensional manner so that a 4096-dot image signal is obtained by one scan. Specifically, the signal charge stored in the light receiving unit is transferred to the transfer unit (CCD register) via the transfer gate and sent to the signal processing device 21 as a 4096-dot image signal.
[0034]
FIG. 4 is a graph for explaining an image signal obtained by the one-dimensional camera 11. The horizontal axis represents the number of dots, and the vertical axis represents the luminance. In an ideal situation where the light from the halogen lamps 13, 13, 13 is uniformly applied to the steel tube 50 and each light receiving element of the one-dimensional camera 11 has no sensitivity unevenness, as shown in FIG. An image signal is obtained. That is, when the steel pipe 50 does not have defects such as wrinkles, wrinkles, and dirt, the magnitude (brightness) of the signal of each dot is equal, and the magnitude of the signal of the dot is reduced only when there is a defect. Therefore, the reference level C for luminance ₀ Set the reference level C ₀ And the brightness measured by each light receiving element can be used to detect the presence or absence of a defect. In the example shown in FIG. 4A, the luminance measured near the points A and B is the reference level C. ₀ It can be seen that there are defects such as wrinkles, wrinkles and dirt at the positions of the steel pipe 50 corresponding to the vicinity of the A point and the B point.
[0035]
As described above, when the light from the halogen lamps 13, 13, 13 is uniformly applied to the steel pipe 50 and the light receiving element of the one-dimensional camera 11 has no sensitivity unevenness, the entire range of the visual field is inspected uniformly. In reality, however, since the halogen lamp 13 has a finite size, the irradiated light is non-uniform, and the light receiving element of the one-dimensional camera 11 has uneven sensitivity. Furthermore, peripheral light reduction occurs due to the shading of the lens provided in the one-dimensional camera 11. Moreover, since the temperature of the steel pipe 50 being conveyed is as high as 1000 ° C., radiation light is emitted, and unevenness of the radiation light is caused by the surface temperature of the steel pipe 50.
Therefore, the actually obtained image signal of the one-dimensional camera 11 cannot obtain an ideal waveform as shown in FIG. 4A, and the luminance increases near the center dot, and the luminance near the dots at both ends. It is often small (FIG. 4B). At this time, the reference level C having the same size as described above ₀ Is set, it is possible to detect a defect near the point A, but it is impossible to detect a defect near the point B existing near the center dot. Therefore, in this embodiment, shading correction is performed on the image signal obtained by the one-dimensional camera 11 so that the entire visual field of the one-dimensional camera 11 can be inspected uniformly. Specifically, the steel pipe 50 is allowed to pass through without rotation, the amount of light received by each dot according to the position of the halogen lamps 13, 13, 13 is measured, and shading correction is performed using that value.
[0036]
FIG. 5 is a schematic diagram illustrating an example of an image obtained by the one-dimensional camera 11. As described above, since the steel pipe 50 advances while rotating on the scroll rollers 31, 31,..., When the number of dots of the one-dimensional camera 11 is taken on the horizontal axis and the elapsed time is taken on the vertical axis, A circumference is obtained as a two-dimensional image 110.
The luminance of the region 110a before the steel pipe 50 passes through the imaging range of the one-dimensional camera 11 and the luminance of the region 110b after the passage become low. The region 110d in which holes are formed in the steel tube 50, the wrinkles, the region 110c in which dirt is generated, and the region 110e in which wrinkles are generated have a small amount of reflected light with respect to light irradiated by the halogen lamps 13, 13, and 13. Therefore, the luminance is low even in those areas. In particular, it is known that the luminance of the region 110d in which the hole is formed in the steel pipe 50 is lower than the luminance of the regions 110c and 110e in which wrinkles, dirt, wrinkles, etc. are generated.
In addition, the wrinkled region 110e generally has a large area (or is long in one direction), and a wrinkle or dirt region has a small area.
Therefore, it is possible to distinguish between defects due to holes and other defects by detecting the level of brightness, and by detecting the area or length of the area where brightness is low, defects due to wrinkles are detected. And other defects can be distinguished.
[0037]
FIG. 6 is a graph showing an example of the detection result by the one-dimensional camera 11. As in FIG. 4, the horizontal axis represents the number of dots of the one-dimensional camera 11, and the vertical axis represents luminance. In the example of the detection result, the above-described shading correction is performed. As described above, the brightness measured by the one-dimensional camera 11 differs between when a defect due to a hole is detected on the surface of the steel pipe 50 and when a defect due to the other is detected. For example, in FIG. 5, time t = t _s The detection result is as shown in the graph of FIG. 6, the luminance measured in the vicinity of point C is slightly lower than the maximum luminance value, and the luminance measured in the vicinity of point D is measured in the vicinity of point C. The brightness value is further lower than the brightness value. Therefore, both can be distinguished by setting two reference levels. That is, the reference level by the two-dimensional camera 12 is set to C ₀ The first reference level C ₁ C ₀ Set to + α and set the second reference level to C ₀ Set to -β. Here, α and β are positive real numbers, the value of α is determined so that both defects are detected at the first reference level, and only defects due to holes are detected at the second reference level. Determine the value of β.
[0038]
FIG. 7 is a flowchart for explaining a processing procedure of defect detection processing by the signal processing device 21. First, the signal processing device 21 takes in a one-dimensional image sent from the one-dimensional camera 11 (step S1). Then, it is determined whether or not there is input of luminance information calculated by the image processing device 22 (step S2). When there is an input of luminance information (S2: YES), a first reference level for detecting wrinkles, wrinkles and dirt on the steel pipe 50 and holes generated in the steel pipe 50 are detected based on the input luminance information. The second reference level is set for this purpose (step S3). That is, the aforementioned reference level C ₀ Is input from the image processing device 22, and predetermined α and β values are added and subtracted. The values of α and β are not necessarily fixed values, and the reference level C ₀ You may make it increase / decrease according to the value of.
In addition, the two-dimensional camera 12 detects in which direction the steel pipe 50 is displaced with respect to the scroll roller 31, and based on the information, corrects the detected light quantity by the one-dimensional camera 11, and the first reference level C. ₁ And second reference level C ₂ May be set.
[0039]
When the luminance information is not input when the one-dimensional image is captured (S2: NO), or when the first and second reference levels are set based on the luminance information (S3), the defect determination by the binarization process is performed. Execute (step S4). That is, the first reference level C ₁ It is determined that the defect detected only at the point is a defect due to wrinkles, dirt, or wrinkles, and the second reference level C ₂ It is determined that the defect detected in is a hole defect. Furthermore, an area where the detected luminance is low over several tens to several hundred dots may be determined to be a wrinkle defect.
[0040]
Next, the signal processing device 21 determines whether or not a defect such as a defect has been detected on the surface of the steel pipe 50 (step S5). If a defect is detected (S5: YES), the inspected steel pipe 50 is defective. Information to that effect is output (step S6). The output information is transmitted to, for example, a host computer (not shown), and the host computer determines whether or not to send the steel pipe 50 to the straightener.
[0041]
If no defect is detected on the surface of the steel pipe 50 in step S5 (S5: NO), or if information indicating a defect is output in step S6, the signal processing device 21 determines whether or not the detection is completed. Is determined (step S7). Whether or not the detection is completed is determined based on the magnitude of the light amount measured based on the two-dimensional image from the two-dimensional camera 12.
If it is determined that the detection is not completed (S7: NO), the process returns to step S1, and if it is determined that the detection is completed (S7: YES), the defect detection process is terminated.
[0042]
Thus, in this Embodiment, it becomes possible to provide the surface inspection apparatus of the steel pipe applicable from normal temperature to hot, without improving a manufacturing line.
[0043]
In addition, although this Embodiment demonstrated the form which applied the test target object to the cylindrical steel pipe, it is needless to say that it can apply also to a columnar steel material, a spherical steel material, etc. Further, when it is not necessary to inspect the entire circumference, the present invention can also be applied to plate materials, square materials, and the like.
[0044]
【The invention's effect】
As described above in detail, in the case of the first invention and the second invention, the object to be inspected is irradiated with light, the reflected light is received from the first region on the surface of the object to be inspected, and the amount of light is measured and measured. Based on the measured light quantity, the reference brightness used for defect detection is calculated, the reflected light is received from the second area on the surface of the inspection object, the brightness is measured, and the calculated reference brightness is compared with the measured brightness. Based on the comparison result, the presence or absence of a defect on the surface of the inspection object is detected. For example, when applied to the detection of defects in the steel pipe manufacturing process, even if the position of the steel pipe fluctuates on the scroll roller, the amount of light reflected from a relatively wide area (first area) is obtained, By calculating the reference luminance for defect detection, defects such as wrinkles, dirt, wrinkles, etc. on the surface of the steel pipe can be detected without being affected by fluctuations in the position of the steel pipe. Further, the production line needs to be improved as much as possible, and an inspection-dedicated rotating device such as a turning roller and a chucking device is not necessary, so that an increase in cost can be suppressed.
[0045]
In the case of the present invention, The amount of reflected light is measured based on the obtained two-dimensional image. Therefore, by using an image pickup device such as a two-dimensional CCD, a reference luminance that can be handled even when the position of the inspection object fluctuates is obtained by imaging the inspection object in a wide range and measuring the light amount. It can be calculated.
[0046]
In the case of the present invention, Based on the obtained one-dimensional image, the brightness of the reflected light is measured. Therefore, it is possible to increase the resolution and detect defects on the surface of the inspection object.
[0048]
First 3 In the case of the invention, since the wrinkles on the inspection object are detected by the first reference luminance and the holes generated in the inspection object are detected by the second reference luminance, the type of defect can be determined. .
[0049]
First 4 In the case of the invention, since a means for conveying the inspection object while being rotated is provided, for example, in the manufacturing process of the steel pipe, it becomes possible to detect defects for the entire circumference and the entire length of the steel pipe from one direction. Has an excellent effect.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a surface inspection system according to an embodiment.
FIG. 2 is a schematic configuration diagram of a surface inspection system according to the present embodiment.
FIG. 3 is a schematic diagram illustrating the imaging principle of a one-dimensional camera.
FIG. 4 is a graph illustrating an image signal obtained by a one-dimensional camera.
FIG. 5 is a schematic diagram illustrating an example of an image obtained by a one-dimensional camera.
FIG. 6 is a graph illustrating an example of a detection result obtained by a one-dimensional camera.
FIG. 7 is a flowchart illustrating a processing procedure of defect detection processing by the signal processing device.
FIG. 8 is a schematic diagram illustrating a conventional inspection process.
[Explanation of symbols]
11 One-dimensional camera
12 2D camera
13 Halogen lamp
21 Signal processing equipment
22 Image processing device
23 Monitor
24 scan converter
25 Video printer
31 Sculola
32 Encoder
50 steel pipes

Claims (4)

The light was irradiated to the steel cylindrical or columnar shape which is an inspection object, receiving light reflected off the steel material, the surface inspection method for detecting the presence or absence of a defect of the surface of the steel material on the basis of the amount of light received ,
The steel material is imaged with a two-dimensional camera to obtain a two-dimensional image, the amount of light from the first region of the steel material surface is measured based on the obtained two-dimensional image, and the steel material is imaged with a one-dimensional camera. A two-dimensional image is acquired, and the luminance in the second region on the steel material surface that is narrower than the first region is measured based on the acquired one-dimensional image, and is used for defect detection based on the amount of light from the first region. One or more reference luminances are set, the set reference luminance is compared with the measured luminance in the second region, and the presence or absence of a defect on the steel surface is detected based on the comparison result. Inspection method. A light irradiation section for irradiating light to the steel cylindrical or columnar shape which is an inspection object, receiving light reflected off the steel, to detect the presence or absence of a defect of the surface of the steel material on the basis of the amount of light received In a surface inspection apparatus comprising a detection unit,
The detection unit measures a light amount from a first region of the steel material surface based on a two-dimensional camera that captures the steel material and obtains a two-dimensional image, and a two-dimensional image obtained by the two-dimensional camera . A luminance in a second region on the surface of the steel material that is narrower than the first region, based on a measuring means, a one-dimensional camera that captures the steel material and obtains a one-dimensional image, and the one-dimensional image obtained by the one-dimensional camera A second measuring unit that measures the amount of light, a setting unit that sets one or a plurality of reference luminances used in defect detection based on the amount of light measured by the first measuring unit, a reference luminance set by the setting unit, and the A surface inspection apparatus comprising: comparison means for comparing brightness measured by the second measurement means; and detection means for detecting the presence or absence of a defect on the surface of the steel material based on a comparison result of the comparison means. The detection means is configured to detect wrinkles on the steel material based on the first reference luminance calculated by the calculation means, and to detect holes generated in the steel material based on the second reference luminance. The surface inspection apparatus according to claim 2 . Surface inspection apparatus according to claim 2 or claim 3, characterized by further comprising means for conveying while rotating the steel.

Images