A method for detecting metal surface defects

Abstract

The present invention relates to the technical field of metal surface defect detection, and discloses a metal surface defect detection method, which includes detecting two circular surfaces of a circular metal sheet, and marking specific points on the first detection surface and the second detection surface; performing a coating operation on the first detection surface to obtain a first workpiece, performing rubbing and marking new points to obtain a first rubbing pattern; performing two coating operations on the second detection surface to obtain a second workpiece, performing rubbing and marking new points to obtain a second rubbing pattern; collecting images of the two rubbing patterns, and forming a first image and a second image after processing; obtaining normal and abnormal regions on the detection surface according to the images, and classifying the workpiece to be detected after comparison; classifying the workpiece according to the number and corresponding relationship of the concave positions and convex positions on the detection surface, distinguishing different defect types of the workpiece, helping to better select corresponding processing solutions in the production process, reducing production costs, and improving the utilization rate of the workpiece.

Description

Technical Field

[0001] The present invention relates to the technical field of metal surface defect detection, and particularly to a method for detecting metal surface defects. Background Art

[0002] In industrial production, metal materials are widely used, especially for manufacturing various parts and equipment. The quality of the metal surface to a certain extent determines the performance and service life of metal products. Therefore, defect detection of the metal surface is an extremely important technological step. Especially in the field of precision manufacturing, the control of surface quality directly affects the overall performance of the product.

[0003] Currently, the methods for detecting metal surface defects can be roughly divided into two categories: manual detection and automated detection. Manual detection is usually carried out by experienced technical workers to judge the quality of the metal surface by visual inspection or with the aid of simple tools. Although this detection method has a certain degree of flexibility, it also has obvious defects. First, manual detection is limited by the personal ability of the detector, with strong subjectivity and low stability. Different detectors may give different detection results. Second, manual detection is easily affected by factors such as fatigue. Under long-term work or high detection intensity, misjudgment or missed detection is likely to occur. In addition, manual detection has low efficiency and is difficult to meet the requirements of large-scale production.

[0004] With the progress of technology, automated detection technology has gradually been applied in the field of metal surface detection. The common automated detection method is visual detection, which is based on computer image processing technology. Metal surface images are collected through a camera, and then image processing algorithms are used to identify defects on the metal surface. Compared with manual detection, this method has higher detection accuracy and efficiency, but there are also some technical difficulties in practical applications. For example, the reflective characteristics of the metal surface are likely to affect the clarity and recognition accuracy of the image. Especially for metal materials with high reflectivity, it is difficult for the detection system to obtain high-quality images. In addition, when visual detection faces metal products with complex shapes, the detection equipment often needs to be adjusted multiple times, increasing the detection difficulty and cost.

[0005] In summary, the present method proposes a method for detecting metal surface defects. By imprinting the metal surface and collecting and analyzing the imprinted image of the metal surface, defects on the metal surface can be detected, solving the subjectivity and fatigue susceptibility of manual detection. At the same time, it also solves the influence of the reflective characteristics of the metal surface in visual detection. Summary of the Invention

[0006] The present invention provides a method for detecting metal surface defects, which helps to solve the problems mentioned in the above background art.

[0007] The present invention provides the following technical solution: a method for detecting metal surface defects, comprising:

[0008] Each circular metal sheet to be detected is denoted as a test workpiece;

[0009] The circular metal sheet is a thin sheet made of metal material;

[0010] Detect the surfaces of the two circular faces of the test workpiece;

[0011] Obtain the two surfaces to be detected of each test workpiece, and denote them as the first detection surface and the second detection surface of the test workpiece respectively;

[0012] Arbitrarily select a test workpiece and denote it as the workpiece to be tested;

[0013] Mark the points X1 and X2 on the first detection surface and the points Y1 and Y2 on the second detection surface of the workpiece to be tested;

[0014] Obtain the first detection surface of the workpiece to be tested, and perform a coating operation on the workpiece to be tested once;

[0015] Denote the workpiece to be tested that has completed one coating operation as the first workpiece;

[0016] Perform a rubbing operation on the first workpiece, and mark the points X3 and X4 to obtain the first rubbing pattern;

[0017] Obtain the second detection surface of the first workpiece, and perform a secondary coating operation on the first workpiece;

[0018] Denote the first workpiece that has completed the secondary coating operation as the second workpiece, and perform a rubbing operation on the second workpiece, mark the points Y3 and Y4 to obtain the second rubbing pattern;

[0019] Collect the images of the first rubbing pattern and the second rubbing pattern respectively, and denote them as the first image and the second image;

[0020] Process the first image and the second image to form the first image and the second image;

[0021] According to the first image and the second image, obtain the normal areas and abnormal areas on the first detection surface and the second detection surface of the workpiece to be tested respectively;

[0022] Compare the normal areas and abnormal areas of the first detection surface and the second detection surface, and classify the workpiece to be tested.

[0023] Optionally, the step of marking the points X1 and X2 on the first detection surface and the points Y1 and Y2 on the second detection surface of the workpiece to be tested includes:

[0024] Obtain the edge contour line of the first detection surface or the second detection surface of the workpiece to be tested, and denote it as the surface contour line;

[0025] Adjust the workpiece to be measured so that the plane enclosed by the surface contour line is parallel to the horizontal plane;

[0026] Make two perpendicular lines to the horizontal plane, so that the perpendicular lines intersect with the edge contours of the first detection surface and the second detection surface of the workpiece to be measured, and record the two perpendicular lines as the first perpendicular line and the second perpendicular line respectively;

[0027] Record the intersection point of the first perpendicular line and the first detection surface as point X1, and the intersection point with the second detection surface as point Y1;

[0028] Record the intersection point of the second perpendicular line and the first detection surface as point X2, and the intersection point with the second detection surface as point Y2.

[0029] Optionally, obtaining the first detection surface of the workpiece to be measured and performing a coating operation on the workpiece to be measured, specifically:

[0030] Obtain the first detection surface of the workpiece to be measured;

[0031] On the first detection surface of the workpiece to be measured, evenly apply the pigment and make the pigment completely cover the first detection surface of the workpiece to complete a coating operation on the workpiece to be measured.

[0032] Optionally, performing a rubbing operation on the first workpiece and marking points X3 and X4 to obtain the first rubbing pattern, including:

[0033] Set a rubbing paper for carrying the rubbing pattern;

[0034] Obtain a circular metal sheet with a shape and size meeting the production requirements, and record it as the standard workpiece;

[0035] Obtain the two circular surfaces of the standard workpiece, and arbitrarily select one of the circular surfaces as the reference circular surface;

[0036] Make the reference circular surface parallel to the plane where the rubbing paper is located and perpendicularly project it onto the rubbing paper, and depict the edge contour line of the projection on the rubbing paper, and record the edge contour line as the reference contour diagram;

[0037] Place the first workpiece above the rubbing paper, so that the first detection surface of the first workpiece is below the second detection surface;

[0038] Project the first workpiece onto the rubbing paper, and record the projection of the first workpiece on the rubbing paper as the first projection;

[0039] Adjust the position of the first workpiece so that the edge contour line of the first projection on the rubbing paper coincides with the reference contour diagram, and take this position as the first rubbing preparation position of the first workpiece;

[0040] Control the first workpiece to move vertically downward from the first stamping preparation position. When it touches the stamping paper, stop moving and hold for six seconds. At the same time, project points X1 and X2 vertically onto the stamping paper and mark them, and record them as points X3 and X4 respectively;

[0041] When the contact time between the first workpiece and the stamping paper is six seconds, control the first workpiece to move vertically upward to separate from the stamping paper, and complete the stamping operation on the first workpiece;

[0042] Record the pattern on the stamping paper and points X3 and X4 as the first stamping pattern.

[0043] Optionally, obtaining the second detection surface of the first workpiece and performing a secondary coating operation on the first workpiece specifically includes:

[0044] Obtain the second detection surface of the first workpiece;

[0045] On the second detection surface of the first workpiece, evenly apply the pigment and make the pigment completely cover the second detection surface of the first workpiece to complete the secondary coating operation on the first workpiece.

[0046] Optionally, recording the first workpiece after the secondary coating operation as the second workpiece and performing a stamping operation on the second workpiece, marking points Y3 and Y4, and obtaining the second stamping pattern, including:

[0047] Reset a stamping paper for carrying the stamping pattern, and record it as the second stamping paper;

[0048] Obtain a standard workpiece and select a reference circular surface;

[0049] Make the reference circular surface parallel to the plane where the second stamping paper is located and project it vertically onto the second stamping paper. Depict the edge contour line of the projection on the second stamping paper, and record this edge contour line as the second reference contour diagram;

[0050] Place the second workpiece above the second stamping paper so that the second detection surface of the second workpiece is below the first detection surface;

[0051] Project the second workpiece onto the second stamping paper, and record the projection of the second workpiece on the second stamping paper as the second projection;

[0052] Adjust the position of the second workpiece so that the edge contour line of the second projection on the second stamping paper coincides with the second reference contour diagram, and take this position as the second stamping preparation position of the second workpiece;

[0053] Control the second workpiece to move vertically downward from the second stamping preparation position. When it touches the second stamping paper, stop moving and hold for six seconds. At the same time, project points Y1 and Y2 vertically onto the second stamping paper and mark them, and record them as points Y3 and Y4 respectively;

[0054] When the contact time between the second workpiece and the second transfer paper is six seconds, control the second workpiece to move vertically upward to separate from the second transfer paper, and complete the transfer operation on the second workpiece;

[0055] Record the pattern on the second transfer paper, as well as points Y3 and Y4, as the second transfer pattern.

[0056] Optionally, the processing of the first image and the second image to form the first image and the second image includes:

[0057] For the first image, taking point X3 as the pole, drawing a ray in the direction pointing to X4 as the polar axis, and taking the direction from X3 to X4 as the positive direction, establish a first polar coordinate system on the first image to form the first image;

[0058] For the second image, taking point Y3 as the pole, drawing a ray in the direction pointing to Y4 as the polar axis, and taking the direction from Y3 to Y4 as the positive direction, establish a second polar coordinate system on the second image to form the second image.

[0059] Optionally, the obtaining of the normal area and the abnormal area on the first detection surface and the second detection surface of the workpiece to be measured according to the first image and the second image includes:

[0060] For the first image:

[0061] If the area within the reference contour in the first image is completely covered by the pigment and there is no pigment in the area outside the reference contour, then record the area covered by the entire first image as the normal area of the first detection surface;

[0062] If there are both areas covered by the pigment and areas not covered by the pigment within the reference contour in the first image, then obtain the area of the area covered by the pigment and record it as the first covered area, and obtain the area of the area not covered by the pigment and record it as the first blank area;

[0063] Compare the first covered area and the first blank area. If the first covered area is greater than or equal to the first blank area, then record the area corresponding to the first blank area on the first detection surface as the abnormal concave area of the first detection surface;

[0064] If the first covered area is less than the first blank area, then record the area corresponding to the first covered area on the first detection surface as the abnormal convex area of the first detection surface;

[0065] For the second image:

[0066] If the area within the second reference contour in the second image is completely covered by the pigment and there is no pigment in the area outside the second reference contour, then record the area covered by the entire second image as the normal area of the second detection surface;

[0067] If there are both areas covered by pigment and areas not covered by pigment within the second reference contour in the second image, obtain the area of the area covered by pigment and record it as the second covered area, and obtain the area of the area not covered by pigment and record it as the second blank area;

[0068] Compare the second covered area and the second blank area. If the second covered area is greater than or equal to the second blank area, record the area corresponding to the second blank area on the second detection surface as the abnormal concave area of the second detection surface;

[0069] If the second covered area is less than the second blank area, record the area corresponding to the second covered area on the second detection surface as the abnormal convex area of the second detection surface.

[0070] Optionally, comparing the normal areas and abnormal areas of the first detection surface and the second detection surface, and classifying the workpiece to be tested includes:

[0071] If the first detection surface is a normal area and the second detection surface is a normal area, mark the workpiece to be tested as a type-one workpiece;

[0072] If there are simultaneously abnormal concave areas or abnormal convex areas on the first detection surface and the second detection surface, respectively obtain the polar coordinates of the center points of the abnormal concave areas and the center points of the abnormal convex areas on the first detection surface in the first polar coordinate system, and record them as the concave position of the first detection surface and the convex position of the first detection surface respectively. Respectively obtain the polar coordinates of the center points of the abnormal convex areas and the center points of the abnormal concave areas on the second detection surface in the second polar coordinate system, and record them as the convex position of the second detection surface and the concave position of the second detection surface respectively;

[0073] If the number of concave positions on the first detection surface is the same as the number of convex positions on the second detection surface, the number of convex positions on the first detection surface is the same as the number of concave positions on the second detection surface, and at the same time, the concave positions on the first detection surface and the convex positions on the second detection surface correspond one by one and are the same, and the convex positions on the first detection surface and the concave positions on the second detection surface correspond one by one and are the same, then mark the workpiece to be tested as a type-two workpiece;

[0074] If the workpiece to be tested is not marked as a type-one workpiece and is not marked as a type-two workpiece, then perform rejection processing on the workpiece to be tested;

[0075] Perform retention processing on the workpiece to be tested marked as a type-one workpiece, and perform repair processing on the workpiece to be tested marked as a type-two workpiece.

[0076] The present invention has the following beneficial effects:

[0077] 1. By marking four points X1, X2, Y1, and Y2 on the first detection surface and the second detection surface of the workpiece to be measured, it is possible to make subsequent operations have clear reference points, which plays an important role in the subsequent rubbing and detection processes. By marking these points, the error caused by the deviation of the workpiece placement can be effectively reduced, ensuring that the morphological information of the area to be measured can be accurately obtained during the rubbing process, reducing the manual alignment error, and thus guaranteeing the reliability and accuracy of the detection results.

[0078] 2. In the rubbing operation, by obtaining the reference contour map of the standard workpiece and adjusting the rubbing projection of the first workpiece or the second workpiece to coincide with the reference contour, the accuracy of the rubbing position can be guaranteed. At the same time, each workpiece has a unified standard during detection, ensuring the consistency and repeatability during the defect detection process.

[0079] 3. By uniformly applying the coating on the first detection surface and the second detection surface of the workpiece to be measured, it is possible to ensure that the complete information of the surface to be measured is captured. This uniform coating operation can ensure that no matter how complex the surface morphology of the workpiece is, all concave and convex areas can be completely covered and accurately reflected in the subsequent rubbing process, enabling the complete capture of the surface state of the entire workpiece, improving the effectiveness and accuracy of defect detection, and helping to comprehensively identify the defects on the metal surface. At the same time, this detection method of applying paint on the workpiece to be measured and then rubbing can eliminate the influence of the surface reflection of the workpiece to be measured in visual inspection.

[0080] 4. When processing the first image and the second image, by establishing a polar coordinate system with a specific point as the pole, it is possible to make the processing of the entire image and the marking of the defect area more convenient. The polar coordinate system is convenient for describing and comparing the defect characteristics at different positions, making the analysis more concise and intuitive. At the same time, the polar coordinate system can better describe the relative position relationship and judge whether the positions are the same, helping to quickly locate and compare the concave and convex defects on the detection surface, thereby improving the analysis efficiency and accuracy.

[0081] 5. By comparing the regions on the first image and the second image, it is possible to determine whether the region within the reference contour map is completely covered, as well as the comparison between the covered area and the blank area, so as to accurately determine the abnormal region on the detection surface, and distinguish between the normal region and the abnormal region. If the reference contour map is completely covered by the pigment, it indicates that the detection surface is a normal region. If there are both pigment-covered and non-pigment-covered parts within the reference contour map, it indicates that there is an abnormal region on the detection surface. If the covered area on the detection surface is greater than or equal to the blank area, it indicates that there is an abnormal concave region on the detection surface. If the covered area on the detection surface is less than the blank area, it indicates that there is an abnormal convex region on the detection surface. This distinction between the normal region and the abnormal region, and further subdivision into abnormal concavities and abnormal convexities, helps to accurately identify different types of surface defects, makes the classification of workpieces clearer, and helps to adopt different treatment methods for different defects.

[0082] 6. By comparing the normal regions and abnormal regions of the first detection surface and the second detection surface, if the first detection surface is a normal region and the second detection surface is also a normal region, it indicates that there are no defects on both surfaces of the workpiece to be tested, and the workpiece to be tested is marked as a type-one workpiece. On the basis of comparing the normal regions and abnormal regions of the first detection surface and the second detection surface, the workpieces are classified according to the number and corresponding relationship of the concave positions and convex positions on the detection surfaces. If the number of concave positions on the first detection surface is the same as the number of convex positions on the second detection surface, and the number of convex positions on the first detection surface is the same as the number of concave positions on the second detection surface, and at the same time, the concave positions on the first detection surface correspond one-to-one and are the same as the convex positions on the second detection surface, and the convex positions on the first detection surface correspond one-to-one and are the same as the concave positions on the second detection surface, it indicates that there are corresponding and identically located concave positions and convex positions on both surfaces of the workpiece to be tested, which means that during the production process of the workpiece to be tested, due to external factors, on one surface of the workpiece to be tested, there is a concave, and correspondingly, there is a convex at the same position on the other surface. By pressing down the convex, it may be possible to repair the workpiece to be tested. The workpiece to be tested that may be repaired in this way is classified as a type-two workpiece. This classification method can effectively distinguish different defect types of workpieces; it can not only determine the qualification of workpieces, but also provide a clear basis for subsequent repair and treatment; by distinguishing different defect types, it can help to better select corresponding treatment plans during the production process, reduce production costs, and improve the utilization rate of workpieces.

[0083] 7. After classifying the workpieces, different treatment methods of retention, repair or rejection are respectively adopted, which can improve the efficiency of the whole production process; retaining the first type of workpieces saves unnecessary processing time; repairing the second type of workpieces can reduce waste while ensuring the quality of the workpieces; rejecting the workpieces to be tested that do not belong to the first type and the second type ensures the product quality; this classification treatment helps to optimize the production process, reduce resource waste, improve the qualified rate of products, and thus improve the efficiency and economic benefits of the whole production line. Brief Description of the Drawings

[0084] Figure 1 It is a schematic diagram of the basic steps of the present invention. Detailed Embodiment

[0085] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0086] Embodiment 1, referring to Figure 1 , a method for detecting metal surface defects, including:

[0087] Each circular metal sheet to be detected is denoted as a test workpiece;

[0088] The circular metal sheet is a thin sheet of metal material; the thin sheet of metal material includes two circular surfaces that are opposite in position and parallel, and the sizes of the two circular surfaces are the same;

[0089] Detect the surfaces of the two circular surfaces of the test workpiece;

[0090] Obtain the two surfaces that need to be detected for each test workpiece, and denote them as the first detection surface and the second detection surface of the test workpiece respectively;

[0091] Arbitrarily select a test workpiece and denote it as the workpiece to be tested;

[0092] Mark point X1 and point X2 on the first detection surface and point Y1 and point Y2 on the second detection surface of the workpiece to be tested; by marking four points X1, X2, Y1, and Y2 on the first detection surface and the second detection surface of the workpiece to be tested, subsequent operations can have clear reference points, which play an important role in the subsequent rubbing and detection processes. By marking these points, the error caused by the deviation of the workpiece placement can be effectively reduced, ensuring that the morphological information of the area to be tested can be accurately obtained during the rubbing process, reducing the manual alignment error, and thus ensuring the reliability and accuracy of the detection results.

[0093] Obtain the first detection surface of the workpiece to be measured, and perform a coating operation on the workpiece to be measured;

[0094] Record the workpiece to be measured that has completed one coating operation as the first workpiece;

[0095] Perform a rubbing operation on the first workpiece, mark points X3 and X4, and obtain the first rubbing pattern;

[0096] Obtain the second detection surface of the first workpiece, and perform a secondary coating operation on the first workpiece;

[0097] Record the first workpiece that has completed the secondary coating operation as the second workpiece, and perform a rubbing operation on the second workpiece, mark points Y3 and Y4, and obtain the second rubbing pattern;

[0098] Collect the images of the first rubbing pattern and the second rubbing pattern respectively, and record them as the first image and the second image;

[0099] Process the first image and the second image to form the first image and the second image;

[0100] According to the first image and the second image, obtain the normal areas and abnormal areas on the first detection surface and the second detection surface of the workpiece to be measured respectively;

[0101] Compare the normal areas and abnormal areas of the first detection surface and the second detection surface, and classify the workpiece to be measured.

[0102] Marking points X1 and X2 on the first detection surface and points Y1 and Y2 on the second detection surface of the workpiece to be measured includes:

[0103] Obtain the edge contour line of the first detection surface or the second detection surface of the workpiece to be measured, and record it as the surface contour line;

[0104] Adjust the workpiece to be measured so that the plane enclosed by the surface contour line is parallel to the horizontal plane;

[0105] Draw two perpendicular lines to the horizontal plane, so that the perpendicular lines intersect with the edge contours of the first detection surface and the second detection surface of the workpiece to be measured, and record the two perpendicular lines as the first perpendicular line and the second perpendicular line respectively;

[0106] Record the intersection point of the first perpendicular line and the first detection surface as point X1, and the intersection point with the second detection surface as point Y1;

[0107] Record the intersection point of the second perpendicular line and the first detection surface as point X2, and the intersection point with the second detection surface as point Y2.

[0108] The obtaining of the first detection surface of the workpiece to be measured and performing a coating operation on the workpiece to be measured specifically is:

[0109] Obtain the first detection surface of the workpiece to be measured;

[0110] On the first detection surface of the workpiece to be measured, evenly apply paint and make the paint completely cover the first detection surface of the workpiece to be measured, thus completing one paint operation on the workpiece to be measured.

[0111] Perform a rubbing operation on the first workpiece, mark points X3 and X4, and obtain the first rubbing pattern, including:

[0112] Set a rubbing paper for carrying the rubbing pattern;

[0113] Obtain a circular metal sheet that meets the production requirements in terms of shape and size, and denote it as the standard workpiece;

[0114] Obtain two circular surfaces of the standard workpiece, and arbitrarily select one of the circular surfaces and denote it as the reference circular surface;

[0115] Make the reference circular surface parallel to the plane where the rubbing paper is located, and perpendicularly project it onto the rubbing paper. On the rubbing paper, depict the edge contour line of the projection, and denote this edge contour line as the reference contour diagram; In the rubbing operation, by obtaining the reference contour diagram of the standard workpiece and adjusting the rubbing projection of the first workpiece or the second workpiece to coincide with the reference contour, the accuracy of the rubbing position can be guaranteed. At the same time, each workpiece has a unified standard during detection, ensuring the consistency and repeatability in the defect detection process.

[0116] Place the first workpiece above the rubbing paper, such that the first detection surface of the first workpiece is below the second detection surface;

[0117] Project the first workpiece onto the rubbing paper, and denote the projection of the first workpiece on the rubbing paper as the first projection;

[0118] Adjust the position of the first workpiece so that the edge contour line of the first projection on the rubbing paper coincides with the reference contour diagram, and take this position as the first rubbing preparation position of the first workpiece;

[0119] Control the first workpiece to move vertically downward from the first rubbing preparation position. When it touches the rubbing paper, stop moving and hold for six seconds. At the same time, perpendicularly project points X1 and X2 onto the rubbing paper and mark them, and denote them as points X3 and X4 respectively;

[0120] When the contact time between the first workpiece and the rubbing paper is six seconds, control the first workpiece to move vertically upward and separate from the rubbing paper, thus completing the rubbing operation on the first workpiece; The said six seconds can be adjusted accordingly so that the first workpiece remains in contact with the rubbing paper for a period of time, just allowing the paint on the first workpiece to be rubbed onto the rubbing paper;

[0121] Denote the pattern on the rubbing paper and points X3 and X4 as the first rubbing pattern.

[0122] Obtain the second detection surface of the first workpiece and perform a secondary coating operation on the first workpiece. Specifically:

[0123] Obtain the second detection surface of the first workpiece;

[0124] On the second detection surface of the first workpiece, evenly apply the pigment and make the pigment completely cover the second detection surface of the first workpiece to complete the secondary coating operation on the first workpiece. By performing a uniform coating operation on the first detection surface and the second detection surface of the workpiece to be tested, it can ensure that the complete information of the surface to be tested is captured. This uniform coating operation can ensure that regardless of how complex the surface morphology of the workpiece is, all concave and convex areas can be completely covered and accurately reflected in the subsequent rubbing process, enabling the surface state of the entire workpiece to be completely captured, improving the effectiveness and accuracy of defect detection, and helping to comprehensively identify defects on the metal surface. At the same time, this detection method of applying pigment on the workpiece to be tested and performing rubbing can eliminate the influence brought by the reflection of the surface of the workpiece to be tested in visual inspection.

[0125] Record the first workpiece after completing the secondary coating operation as the second workpiece and perform a rubbing operation on the second workpiece, mark points Y3 and Y4 to obtain the second rubbing pattern, including:

[0126] Reset a rubbing paper for carrying the rubbing pattern, denoted as the second rubbing paper;

[0127] Obtain a standard workpiece and select a reference circular surface;

[0128] Make the reference circular surface parallel to the plane where the second rubbing paper is located and perpendicularly project it onto the second rubbing paper, and depict the edge contour line of the projection on the second rubbing paper, and denote this edge contour line as the second reference contour map;

[0129] Place the second workpiece above the second rubbing paper so that the second detection surface of the second workpiece is below the first detection surface;

[0130] Project the second workpiece onto the second rubbing paper, and denote the projection of the second workpiece on the second rubbing paper as the second projection;

[0131] Adjust the position of the second workpiece so that the edge contour line of the second projection on the second rubbing paper coincides with the second reference contour map, and take this position as the second rubbing preparation position of the second workpiece;

[0132] Control the second workpiece to move vertically downward from the second rubbing preparation position. When it touches the second rubbing paper, stop moving and hold for six seconds. At the same time, project points Y1 and Y2 vertically onto the second rubbing paper and mark them, and denote them as points Y3 and Y4 respectively;

[0133] When the contact time between the second workpiece and the second transfer paper is six seconds, control the second workpiece to move vertically upward and separate from the second transfer paper to complete the transfer operation of the second workpiece; the six seconds can be adjusted accordingly so that the second workpiece and the second transfer paper remain in contact for a period of time, enabling the pigment on the second workpiece to be transferred onto the second transfer paper;

[0134] Record the pattern on the second transfer paper, as well as points Y3 and Y4, as the second transfer pattern.

[0135] The processing of the first image and the second image to form the first image and the second image includes:

[0136] For the first image, with point X3 as the pole, draw a ray in the direction pointing to X4 as the polar axis, and use the direction from X3 to X4 as the positive direction to establish a first polar coordinate system on the first image to form the first image;

[0137] For the second image, with point Y3 as the pole, draw a ray in the direction pointing to Y4 as the polar axis, and use the direction from Y3 to Y4 as the positive direction to establish a second polar coordinate system on the second image to form the second image; when processing the first image and the second image, by establishing a polar coordinate system with a specific point as the pole, it can make the processing of the entire image and the marking of the defective area more convenient. The polar coordinate system is convenient for describing and comparing the defective features at different positions, making the analysis more concise and intuitive. At the same time, the polar coordinate system can better describe the relative position relationship, judge whether the positions are the same, and help quickly locate and compare the concave and convex defects on the detection surface, thereby improving the analysis efficiency and accuracy.

[0138] The obtaining of the normal area and the abnormal area on the first detection surface and the second detection surface of the workpiece to be measured according to the first image and the second image respectively includes:

[0139] For the first image:

[0140] If the area within the reference contour in the first image is completely covered by the pigment and there is no pigment in the area outside the reference contour, then record the area covered by the entire first image as the normal area of the first detection surface;

[0141] If there are both areas covered by the pigment and areas not covered by the pigment within the reference contour in the first image, then obtain the area of the area covered by the pigment and record it as the first covered area, and obtain the area of the area not covered by the pigment and record it as the first blank area;

[0142] Compare the first covered area and the first blank area. If the first covered area is greater than or equal to the first blank area, then record the area corresponding to the first blank area on the first detection surface as the abnormal concave area of the first detection surface;

[0143] If the covered area of the first one is less than the blank area of the first one, then the area corresponding to the covered area of the first one on the first detection surface is recorded as the abnormal convex area of the first detection surface;

[0144] For the second image:

[0145] If the area within the second reference contour in the second image is completely covered by the pigment and there is no pigment in the area outside the second reference contour, then the area covered by the entire second image is recorded as the normal area of the second detection surface;

[0146] If there are both areas covered by the pigment and areas not covered by the pigment within the second reference contour in the second image, then obtain the area of the area covered by the pigment and record it as the covered area of the second one, and obtain the area of the area not covered by the pigment and record it as the blank area of the second one;

[0147] Compare the covered area of the second one and the blank area of the second one. If the covered area of the second one is greater than or equal to the blank area of the second one, then the area corresponding to the blank area of the second one on the second detection surface is recorded as the abnormal concave area of the second detection surface;

[0148] If the covered area of the second one is less than the blank area of the second one, then the area corresponding to the covered area of the second one on the second detection surface is recorded as the abnormal convex area of the second detection surface; By comparing the areas on the first image and the second image, it is possible to determine whether the area within the reference contour is completely covered and the comparison between the covered area and the blank area, so as to accurately determine the abnormal area on the detection surface, and be able to distinguish between the normal area and the abnormal area. If the area within the reference contour is completely covered by the pigment, it means that the detection surface is a normal area. If there are both areas covered by the pigment and areas not covered by the pigment within the reference contour, it means that there is an abnormal area on the detection surface; If the covered area on the detection surface is greater than or equal to the blank area, it means that there is an abnormal concave area on the detection surface. If the covered area on the detection surface is less than the blank area, it means that there is an abnormal convex area on the detection surface; This distinction between the normal area and the abnormal area, and further subdivision into abnormal concave and abnormal convex, helps to accurately identify different types of surface defects, can make the classification of workpieces more clear, and helps to adopt different treatment methods for different defects.

[0149] Comparing the normal areas and abnormal areas of the first detection surface and the second detection surface to classify the workpiece to be tested includes:

[0150] If the first detection surface is a normal area and the second detection surface is a normal area, indicating that there are no defects on both surfaces of the workpiece to be tested, then mark the workpiece to be tested as a type-one workpiece;

[0151] If there are abnormal concave regions or abnormal convex regions on both the first detection surface and the second detection surface, the polar coordinates of the center points of the abnormal concave regions and the center points of the abnormal convex regions on the first detection surface in the first polar coordinate system are respectively obtained, and are respectively denoted as the concave position of the first detection surface and the convex position of the first detection surface. The polar coordinates of the center points of the abnormal convex regions and the center points of the abnormal concave regions on the second detection surface in the second polar coordinate system are respectively obtained, and are respectively denoted as the convex position of the second detection surface and the concave position of the second detection surface;

[0152] If the number of concave positions on the first detection surface is the same as the number of convex positions on the second detection surface, the number of convex positions on the first detection surface is the same as the number of concave positions on the second detection surface, and at the same time, the concave positions on the first detection surface and the convex positions on the second detection surface correspond one by one and are the same, and the convex positions on the first detection surface and the concave positions on the second detection surface correspond one by one and are the same, then the workpiece to be tested is marked as a type-two workpiece; By comparing the normal regions and abnormal regions of the first detection surface and the second detection surface, if the first detection surface is a normal region and the second detection surface is a normal region, it indicates that there are no defects on both surfaces of the workpiece to be tested, and the workpiece to be tested is marked as a type-one workpiece; On the basis of comparing the normal regions and abnormal regions of the first detection surface and the second detection surface, the workpiece is classified according to the number and corresponding relationship of the concave positions and convex positions of the detection surface. If the number of concave positions on the first detection surface is the same as the number of convex positions on the second detection surface, and the number of convex positions on the first detection surface is the same as the number of concave positions on the second detection surface, and at the same time, the concave positions on the first detection surface and the convex positions on the second detection surface correspond one by one and are the same, and the convex positions on the first detection surface and the concave positions on the second detection surface correspond one by one and are the same, it indicates that there are corresponding and identically-positioned concave positions and convex positions on both surfaces of the workpiece to be tested, which means that during the production process of the workpiece to be tested, due to external factors, on one surface of the workpiece to be tested, there is a concave, and correspondingly, on the same position on the other surface, there is a convex. By pressing down the convex, the workpiece to be tested may be repaired. The workpiece to be tested that may be repaired is classified into type-two workpieces. This classification method can effectively distinguish different defect types of workpieces; It can not only determine the qualification of the workpiece, but also provide a clear basis for subsequent repair and processing; By distinguishing different defect types, it can help the production process better select corresponding treatment plans, reduce production costs, and improve the utilization rate of workpieces.

[0153] If the workpiece to be tested is not marked as a type-one workpiece and is not marked as a type-two workpiece, it means that the workpiece to be tested is neither a qualified workpiece without surface defects nor a workpiece that can be repaired, but a workpiece with surface defects. Then, the workpiece to be tested is removed;

[0154] The workpieces to be measured marked as Class I workpieces are retained, and the workpieces to be measured marked as Class II workpieces are repaired; after classifying the workpieces, different treatment methods of retention, repair or rejection are adopted respectively, which can improve the efficiency of the whole production process; retaining the Class I workpieces saves unnecessary processing time; repairing the Class II workpieces can reduce waste on the basis of ensuring the quality of the workpieces; rejecting the workpieces to be measured that do not belong to Class I workpieces and Class II workpieces ensures the product quality; this classification treatment helps to optimize the production process, reduce resource waste, improve the pass rate of products, and thus improve the efficiency and economic benefits of the whole production line.

[0155] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0156] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for detecting metal surface defects, characterized in that, Including: Each circular metal sheet to be detected is denoted as a test workpiece; The circular metal sheet is a thin sheet made of metal; Detect the surfaces of the two circular faces of the test workpiece; Obtain the two surfaces that each test workpiece needs to be detected, and denote them as the first detection surface and the second detection surface of the test workpiece respectively; Arbitrarily select a test workpiece and denote it as the workpiece to be measured; Mark the X1 point and X2 point of the first detection surface and the Y1 point and Y2 point of the second detection surface on the workpiece to be measured; Obtain the first detection surface of the workpiece to be measured and perform a coating operation on the workpiece to be measured once; The workpiece to be measured that has completed one coating operation is denoted as the first workpiece; Set a transfer paper for carrying the transfer pattern; Obtain a circular metal sheet with a shape and size meeting the production requirements and denote it as the standard workpiece; Obtain the two circular faces of the standard workpiece and arbitrarily select one of the circular faces and denote it as the reference circular face; Make the reference circular face parallel to the plane where the transfer paper is located and project it vertically onto the transfer paper, and depict the edge contour line of the projection on the transfer paper, and denote this edge contour line as the reference contour diagram; Perform a transfer operation on the first workpiece and mark the X3 point and X4 point to obtain the first transfer pattern; Obtain the second detection surface of the first workpiece and perform a secondary coating operation on the first workpiece; The first workpiece that has completed the secondary coating operation is denoted as the second workpiece, and perform a transfer operation on the second workpiece, mark the Y3 point and Y4 point to obtain the second transfer pattern; Collect the images of the first transfer pattern and the second transfer pattern respectively and denote them as the first image and the second image; Process the first image and the second image to form the first image and the second image; According to the first image and the second image, obtain the normal areas and abnormal areas on the first detection surface and the second detection surface of the workpiece to be measured respectively, including: For the first image: If the area within the reference contour diagram in the first image is completely covered by the pigment and there is no pigment in the area outside the reference contour diagram, then the area covered by the entire first image is denoted as the normal area of the first detection surface; If there are both areas covered by the pigment and areas not covered by the pigment within the reference contour diagram in the first image, then obtain the area of the area covered by the pigment and denote it as the first covered area, and obtain the area of the area not covered by the pigment and denote it as the first blank area; Compare the first covered area and the first blank area. If the first covered area is greater than or equal to the first blank area, then the area corresponding to the first blank area on the first detection surface is denoted as the abnormal depression area of the first detection surface; If the first covered area is less than the first blank area, then the area corresponding to the first covered area on the first detection surface is denoted as the abnormal protrusion area of the first detection surface; Perform the same operation on the second image as on the first image to judge the abnormal depression area or abnormal protrusion area on the second detection surface; Compare the normal areas and abnormal areas of the first detection surface and the second detection surface, and classify the workpiece to be measured.

2. The method for detecting metal surface defects according to claim 1, wherein, The marking of the X1 point and X2 point of the first detection surface and the Y1 point and Y2 point of the second detection surface on the workpiece to be measured includes: Obtain the edge contour line of the first detection surface or the second detection surface of the workpiece to be measured and denote it as the surface contour line; Adjust the workpiece to be measured so that the plane enclosed by the surface contour line is parallel to the horizontal plane; Draw two perpendicular lines to the horizontal plane, so that the perpendicular lines intersect with the edge contours of the first detection surface and the second detection surface of the workpiece to be measured, and record the two perpendicular lines as the first perpendicular line and the second perpendicular line respectively; Record the intersection point of the first perpendicular line and the first detection surface as point X1, and the intersection point with the second detection surface as point Y1; Record the intersection point of the second perpendicular line and the first detection surface as point X2, and the intersection point with the second detection surface as point Y2.

3. A method for detecting metal surface defects according to claim 1, characterized in that, The first detection surface of the workpiece to be measured is obtained, and a coating operation is performed on the workpiece to be measured once. Specifically: Obtain the first detection surface of the workpiece to be measured; On the first detection surface of the workpiece to be measured, evenly apply the pigment and make the pigment completely cover the first detection surface of the workpiece to be measured, completing a coating operation on the workpiece to be measured.

4. A method for detecting metal surface defects according to claim 1, characterized in that, The rubbing operation is performed on the first workpiece, and points X3 and X4 are marked to obtain the first rubbing pattern, including: Place the first workpiece above the rubbing paper, so that the first detection surface of the first workpiece is below the second detection surface; Project the first workpiece onto the rubbing paper, and record the projection of the first workpiece on the rubbing paper as the first projection; Adjust the position of the first workpiece so that the edge contour line of the first projection on the rubbing paper coincides with the reference contour map, and take this position as the first rubbing preparation position of the first workpiece; Control the first workpiece to move vertically downward from the first rubbing preparation position. When it touches the rubbing paper, stop moving and hold for six seconds. At the same time, project points X1 and X2 vertically onto the rubbing paper and mark them, and record them as points X3 and X4 respectively; When the contact time between the first workpiece and the rubbing paper is six seconds, control the first workpiece to move vertically upward and separate from the rubbing paper, completing the rubbing operation on the first workpiece; Record the pattern on the rubbing paper and points X3 and X4 as the first rubbing pattern.

5. A method for detecting metal surface defects according to claim 1, characterized in that, The second detection surface of the first workpiece is obtained, and a secondary coating operation is performed on the first workpiece. Specifically: Obtain the second detection surface of the first workpiece; On the second detection surface of the first workpiece, evenly apply the pigment and make the pigment completely cover the second detection surface of the first workpiece, completing the secondary coating operation on the first workpiece.

6. The metal surface defect detection method according to claim 4, wherein Record the first workpiece that has completed the secondary coating operation as the second workpiece, and perform a rubbing operation on the second workpiece, mark points Y3 and Y4, and obtain the second rubbing pattern, including: Reset a rubbing paper for carrying the rubbing pattern, and record it as the second rubbing paper; Obtain a standard workpiece and select a reference circular surface; Make the reference circular surface parallel to the plane where the second rubbing paper is located, and project it vertically onto the second rubbing paper. Draw the edge contour line of the projection on the second rubbing paper, and record this edge contour line as the second reference contour map; Place the second workpiece above the second rubbing paper, so that the second detection surface of the second workpiece is below the first detection surface; Project the second workpiece onto the second rubbing paper, and record the projection of the second workpiece on the second rubbing paper as the second projection; Adjust the position of the second workpiece so that the edge contour line of the second projection on the second rubbing paper coincides with the second reference contour map, and take this position as the second rubbing preparation position of the second workpiece; Control the second workpiece to move vertically downward from the second embossing preparation position. When it touches the second embossing paper, stop moving and hold for six seconds. At the same time, project points Y1 and Y2 vertically onto the second embossing paper and mark them, and record them as points Y3 and Y4 respectively; When the contact time between the second workpiece and the second embossing paper is six seconds, control the second workpiece to move vertically upward to separate from the second embossing paper, and complete the embossing operation on the second workpiece; Record the pattern on the second embossing paper and points Y3 and Y4 as the second embossing pattern.

7. A method for detecting metal surface defects according to claim 1, characterized in that, The processing of the first image and the second image to form the first image and the second image includes: For the first image, take point X3 as the pole, draw a ray in the direction pointing to X4 as the polar axis, and take the direction from X3 to X4 as the positive direction to establish a first polar coordinate system on the first image to form the first image; For the second image, take point Y3 as the pole, draw a ray in the direction pointing to Y4 as the polar axis, and take the direction from Y3 to Y4 as the positive direction to establish a second polar coordinate system on the second image to form the second image.

8. A method for detecting metal surface defects according to claim 1, characterized in that The comparison of the normal areas and abnormal areas of the first detection surface and the second detection surface to classify the workpiece to be tested includes: If the first detection surface is a normal area and the second detection surface is a normal area, mark the workpiece to be tested as a first-class workpiece; If there are abnormal concave areas or abnormal convex areas on both the first detection surface and the second detection surface, respectively obtain the polar coordinates of the center points of the abnormal concave areas and the abnormal convex areas on the first detection surface in the first polar coordinate system, and record them as the concave position and the convex position of the first detection surface respectively. Respectively obtain the polar coordinates of the center points of the abnormal convex areas and the abnormal concave areas on the second detection surface in the second polar coordinate system, and record them as the convex position and the concave position of the second detection surface respectively; If the number of concave positions on the first detection surface is the same as the number of convex positions on the second detection surface, the number of convex positions on the first detection surface is the same as the number of concave positions on the second detection surface, and at the same time, the concave positions on the first detection surface and the convex positions on the second detection surface correspond one by one and are the same, and the convex positions on the first detection surface and the concave positions on the second detection surface correspond one by one and are the same, then mark the workpiece to be tested as a second-class workpiece; If the workpiece to be tested is not marked as a first-class workpiece and is not marked as a second-class workpiece, then perform rejection processing on the workpiece to be tested; Perform retention processing on the workpiece to be tested marked as a first-class workpiece, and perform repair processing on the workpiece to be tested marked as a second-class workpiece.

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