JPH0238952A - Surface defect inspection device - Google Patents

Abstract

PURPOSE:To efficiently inspect a surface defect with high accuracy by computing the kind and grade of the surface defect by a computer, and then photographing a necessary defect by a camera with a proper visual field and obtaining a still image. CONSTITUTION:A detector 12 projects light on the surface of a steel late 10 to detects the defect from its reflection state, and then outputs surface defect information to the computer 16 through a defect detecting circuit 14. The computer 16 decides (primarily) the kind and grade of the surface defect according to the signal. A control circuit 22 selects a narrow-field camera 20B for a spot defect or a wide-field camera 20A for a linear or planar defect according to the surface defect information from the computer 16 and makes a stroboscopic device emit light when the surface defect reaches a photographic point Xa to photograph the surface defect. The photographed surface defect is displayed as the still image on a motor 30 through an image input/output circuit 28 and an image processing circuit 26.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an improvement in a surface defect inspection device that can efficiently and accurately inspect surface defects on a moving object to be inspected, such as a rolled steel plate.

[Conventional technology]

Inspection of surface defects in materials to be inspected during transportation, such as steel plates on rolling lines, has conventionally been carried out by visual inspection by an operator, or by irradiating a laser beam or the like onto the surface of the object to be inspected and using its reflection to inspect for defects. For example, as disclosed in JP-A-53-12383, JP-A-54-118289, JP-B-58-14984, etc., a still image of the surface of the specimen is captured using a camera and a strobe. There are ways to capture the defects and then conduct defect inspections.

[The problem that the invention tries to solve! a]

The above-mentioned visual inspection has a problem in that when the line speed of the material to be inspected exceeds a certain value, the number of missed inspections increases and the inspection becomes close to an uninspected state. Additionally, defect inspection equipment that uses reflection of laser light, etc. does not necessarily show a superior match rate compared to visual inspection, depending on the type of surface defect on the material being inspected, and may allow a certain degree of misjudgment. There is a problem in that it has to be used while In addition, with the surface defect inspection method using a camera and a strobe, it is not clear whether there are defects on the surface of the material to be inspected, so it is necessary to inspect the entire length of the material to be inspected. There is a problem in that it is not possible to extract only a certain portion and perform a surface defect inspection.

[Purpose of the invention]

This invention was made in view of the above-mentioned conventional problems, and is a surface defect information system that can inspect surface defects of moving materials such as steel plates at high speed and with an accuracy of 5. ! The purpose is to provide

[Means to solve the problem]

This invention is based on a detector that irradiates the surface of a moving test material with a light beam and detects surface defects of the test material based on the state of reflection, and a surface defect detection signal obtained by this detector. A calculator for calculating the type and grade of the surface defect; a light projector that irradiates light onto the defect that needs to be photographed based on the type and grade signal of the surface defect output from the computer; a plurality of cameras with different fields of view for photographing the defect, and based on the surface defect information from the total X machines, at least one camera with a field of view suitable for photographing the defect is selected, thereby The above object is achieved by configuring a surface defect inspection device that takes images of the surface defects.

[Effect]

In this invention, first, the surface defect of the material to be inspected is detected by a detector, and based on the detection signal, the type and grade of the surface defect is calculated by the machine. Only the defects are photographed using a camera having a field of view suitable for this, a still image is obtained, and the surface defects can be efficiently and precisely inspected by an inspector.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, this embodiment includes a light emitter/receiver that irradiates a laser or light onto the surface of a steel plate 10 in a rolling line and receives the reflected light. A detector 12 for detecting surface defects, a defect detection circuit 14 for processing the surface defect detection signal obtained by this detector 12 in a hardware manner, and a signal from the defect detection circuit 14 is taken in and processed in a software manner. A device that processes and determines the type and grade of surface defects! 11116, and a strobe 18 that irradiates light onto a defect that needs to be photographed based on the type and grade signal of the surface defect output from this computer 16, and a wide-field camera 2OA and a narrow-field camera that photographs the defect at the timing of the strobe light. It is configured to include a visual field camera 20B and a defect inspection device 24 including a control circuit 22 that controls these. This defect inspection device 24 mainly includes an image processing circuit 26, an image input/output circuit 28, and timing control circuits 18A and 21.
, a monitor 30 and a keyboard 32. The calculation unit 116 also includes a CRT 16A and a CRT 16 for displaying information on surface defects determined by the computer.
Defect inspection device 2 detects the surface defect information displayed in A.
A keyboard 16B is connected to the keyboard 16B for the inspector to input whether or not to perform the inspection in step 4. Further, the calculation 8116 is configured to receive the pulse signal output from the pulse generator 34 as input. This pulse generator 34 is connected to a roll 36 that rolls into contact with the converter 10 so that no slip occurs, and outputs a pulse signal in accordance with the rotational speed of the roll 36. The #J control circuit 22 in the defect inspection device 24 has a total of x
, 8116, and a total of X machine 1
6 is based on the pulse signal from the pulse generator 34,
By tracking the surface defects detected by the detector 12, the surface defects are detected by the strobe 18 and the cameras 2OA and 20B.
Based on the timing signal indicating that the strobe 18 should not reach the position of
and operates the wide-field camera 20A or the narrow-field camera 20B. Here, the control circuit 22 selects a camera with a field of view suitable for photographing the surface defect from the wide-field camera 2OA or the narrow-field camera 20B, based on the surface defect information from the calculation fi16. That is, according to the criteria shown in FIG. 3, the narrow-field camera 20B is selected when the surface defect is a point defect, and the wide-field camera 2OA is selected when the surface defect is a linear defect or a planar defect. has been done. The image input/output circuit 28 takes in image information of surface defects on the steel plate 10 obtained by the camera 2OA or 20B. Further, the image processing circuit 26 performs image processing such as defect determination based on the image signal taken in by the image input/output circuit 28, and displays the defective image as a still image on the monitor 30. The keyboard 32 performs a secondary judgment such as the type and grade of the surface defect based on the defect image displayed on the monitor 30, and then transmits the judgment result to the image processing circuit 2 by the inspector.
6. The data is input to the computer 16 via the control circuit 22. Next, the copper plate 10 is inspected by the surface defect inspection apparatus according to the above embodiment.
The process of inspecting for surface defects will be explained. While the steel plate 10 is moving to the left in FIG. 1 on the rolling line, the detector 12 projects a laser or light onto the surface of the steel plate 10 and receives the reflected light with a light receiver to detect the reflected state. , detects defects on the surface of the steel plate 10 and outputs surface defect information to the calculation 11116 via the defect detection circuit 14 . A total of $t1116 processes the signal from the defect detection circuit 14 and determines the type and grade of the detected surface defect (primary determination). On the other hand, the total Xal16 is calculated based on the pulse signal inputted by the pulse generator 34, and the distance x the surface defect detected by the detector 12 from the detection point XO to the photographing point XcL of the cameras 2OA and 20B. open tracking,
Considering the timing adjustment time of cameras 2OA, 20B and strobe 18, the surface defect is located at the photographing point Xα.
When the timing reaches a point slightly before , a timing signal is output to the control circuit 22 in the defect inspection device 24 . Here, the surface defect information that has been primarily determined by the computer 16 is displayed on the CRT 16A.
It is sent from the calculation fi 16 to the control circuit 22 based on certain conditions set by B. Based on the surface defect information input from the computer 216, the control circuit 22 controls the narrow field camera 20B in the case of a point defect as shown in FIG. In the case of a linear or planar defect as shown, the wide-field camera 2OA is selected, and based on the input timing signal, the surface defect is located at the shooting point X.
(When reaching L, the timing control circuits 18A, 2
1, the strobe 18 is made to emit light, and at the same time, the surface defects of the steel plate 10 are photographed by the camera 2OA or 20B. The photographed surface defect information of the steel plate 10 is taken as an image into the image input/output circuit 28, and the image not taken into the image input/output circuit 28 is subjected to image processing such as defect determination in the image processing circuit 26. Furthermore, the surface defect is displayed as a still image on the monitor 30. In this way, the surface defect image displayed as a still image on the monitor 30 is subjected to secondary determination of the type, grade, etc. of the surface defect by an inspector. The inspector inputs the result of the secondary determination into the needle 3Efi 16 again from the keyboard 32 as accurate surface defect information. This input surface defect information is calculated 116 in advance.
A comparison is made with the surface defect information that was first determined in . The primary determination result of the computer 16 is displayed on the CRT 16A, as shown in FIG. 4, for example. In other words, the matrix in Figure 4 has the defect grade on the vertical axis,
The defect type is displayed on the horizontal axis, and Y in the matrix
ES and No indicate whether the detected defect is to be output from the computer 16 to the defect inspection device 24 using the cameras 2OA, 20B and the strobe 18 (YES) or not (NO). In the display example of FIG. 4, the computer 16 determines that the point defect is A, the defect grade is C1, and the defect information is output according to the matrix (YES). Here, the YES or NO determination in the matrix is set to match the visual determination result by the inspector. For example, if everything in the matrix is set to YES, information on all surface defects detected by the detector 12 is sent to the control circuit 22, photographed by the cameras 20A and 20B, and displayed on the monitor 30. On the other hand, if everything in the matrix is set to NO, all defect information will not be sent and will not be photographed by the cameras 2OA and 20B. By the way, defects in cold-rolled steel sheets generally have the following morphology:
Defects are broadly classified into three types: point defects, linear defects, and planar defects as described above. Point defects include dents and flaking, linear defects include scale and slivers, and planar defects include oil stains and stains. In the embodiment described above, the cameras 2OA and 20B are selected according to the morphological classification of defects based on the primary determination, that is, the classification of point defects, linear defects, or planar defects.
The present invention is not limited thereto, and the cameras 20A and 20B may be selected depending on the type of defect as described above, that is, dent, chipping, scale, sliver, oil stain, or stain. 5 (A) and 6 (A) when photographing spot defects, point defects, linear defects, and planar defects using a wide-field camera 2OA.
, as shown in FIG. 7(A), and when photographed by the narrow-field camera 20B''c, as shown in FIG. 5(B), FIG. 6(B), and FIG. 7(B), respectively. As is clear from these examples, since the area of a point defect is small, it is better to take an image with the narrow field camera 20B when the inspector judges the defect on the monitor 30.
It is also advantageous when automatically determining by image processing. On the contrary, it is more advantageous to photograph linear defects and planar defects using the wide-field camera 2OA. However, the present invention is not limited to this,
For example, the same defect may be photographed simultaneously by the wide-field camera 2OA and the narrow-field camera 20B, and a screen from which the defect can be easily recognized may be selected from the obtained images. Further, in the above embodiment, two cameras 20A and 20B are arranged in the direction of movement of the steel material 10, and a strobe light 1 for illumination is provided.
However, the present invention is not limited to this, and the cameras may be three or more cameras with different fields of view, or the cameras may be arranged in the width direction of the steel material 10. Further, illumination means other than a strobe may be used. Furthermore, in the above embodiment, as an example of the defect grades in the matrix shown in FIG. 4, minor defects to major defects are displayed in the order of A to E, but generally, major defects are detected by the detector. 12. Based on the detection by the defect detection circuit 14, it can be almost detected by the primary judgment of the total Xfi 16, and the judgment by the computer 16 is also relatively accurate. Therefore, when appearance standards are relatively lenient, the frequency of secondary judgment by normal inspectors for such serious defects can be reduced. However, if the appearance inspection standards are strict, minor defects such as minor defects, grade A or B in the matrix of FIG. As a reference, a secondary judgment by the inspector is ultimately required. Therefore, in such a case, if the CRT 16A is set up as shown in the matrix in FIG. 4, defect images are taken for defects that have a lot of ambiguity in the primary judgment by the computer 16, and the second judgment by the inspector is performed. An inspection can be performed with the next determination result as the final determination. Further, in this embodiment, the inspector's secondary judgment result based on the defect image displayed on the monitor 30 is displayed on the keyboard 3.
2 to the computer 16 via the control circuit 22,
By comparing this with the primary determination result, it is possible to improve the primary determination result through online learning. Although the above embodiment is for inspecting surface defects on a steel plate 10 in a rolling line, the present invention is not limited thereto, and is applicable to inspecting surface defects on the surface of a moving test material other than a steel plate. This is generally applicable to inspections. [Effect of the invention 1] Since the present invention is configured as described above, it is sufficient for the inspector to take an image of the surface defect using the projector and camera only when defect information is output from the total X machines, and to inspect this image. , it is possible to carry out efficient inspections, and since inspectors only check still images showing surface defects, restrictions on the line speed that can be inspected can be lifted, and furthermore,
In the secondary judgment, not only can inspectors obtain accurate surface defect inspection based on still images, but also the accuracy of the primary judgment can be improved by learning from Total X81.
By taking pictures using a camera with a wide field of view, it becomes easy to detect and judge minute defects, and it also improves the efficiency of the inspector's judgment regarding defects in the pond. Traditionally, products with strict visual inspection standards were sent to the next process such as finishing for inspection in intermediate processes such as finishing, but there is no longer a need to send them for inspection, shortening the process, improving yield, and saving time for the next process. , has excellent effects such as labor saving.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the surface defect inspection device according to the present invention, Fig. 2 is a perspective view showing the arrangement of cameras in the same embodiment, and Fig. 3 is a detected defect type and selection. A diagram showing the relationship with the camera, FIG. 4 is a diagram showing the judgment results of the computer in the same example, and FIGS. 5 to 7 are:
FIG. 3 is a plan view showing images of point defects, linear defects, and planar defects taken by a wide-field camera and a narrow camera. DESCRIPTION OF SYMBOLS 10... Steel plate, 12... Detector, 14... Defect detection circuit, 16... Computer, 18... Strobe, 2OA... Wide field of view camera, 20B... Narrow field of view camera, 22 ...Control circuit, 24...Defect detection device, 26...Image processing circuit, 28...Image input/output circuit, 34...Pulse generator.

Claims (1)

[Claims] (1) A detector that irradiates the surface of a moving test material with a light beam and detects surface defects of the test material based on the state of reflection;
Based on the surface defect detection signal obtained by this detector,
A calculator for calculating the type and grade of the surface defect; a light projector that irradiates light onto the defect that needs to be photographed based on the type and grade signal of the surface defect output from the computer; a plurality of cameras with different fields of view for photographing the defect, and based on the surface defect information from the computer, at least one camera with a field of view suitable for photographing the defect is selected, thereby photographing the surface defect. A surface defect inspection device characterized by: