A visual inspection system and working method for surface crack defects

Abstract

The application discloses a kind of visual inspection systems of surface crack defects, including horizontal belt linear conveying platform, and a plurality of interval distribution annular workpieces are horizontally placed on linear conveying platform;The upside of the local position of linear conveying platform has a roller curve array and b roller curve array with curve bending in overhead view angle;Under the overhead view angle, a roller curve array and b roller curve array form a curve constraint channel between them;During the process that linear conveying platform conveys annular workpiece, annular workpiece will be under the joint constraint of a roller curve array and b roller curve array along curve and pass through curve constraint channel;The middle segment of curve constraint channel has lens downward visual camera directly above it.Effective scanning can be carried out to the image of inner circle surface and outer circle surface of annular workpiece.

Description

Technical Field

[0001] This invention belongs to the field of visual inspection. Background Technology

[0002] Visual inspection of surface defects in ring-shaped workpieces with a certain thickness, such as ring-shaped iron cores, ring-shaped bearings, and magnetic tiles, often employs a linear conveyor platform in conjunction with a fixed overhead camera. This method can only acquire images of the upper surface of the workpiece. Since ring-shaped workpieces have a certain height along the axial direction, it is also necessary to scan the inner and outer surfaces of the workpiece. However, because the inner and outer surfaces of the workpiece are cylindrical and perpendicular to the overhead scanning angle, they cannot be effectively captured by the camera, resulting in a blind spot in the inspection. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a visual inspection system and working method for surface crack defects, which can effectively scan the images of the inner and outer ring surfaces of annular workpieces.

[0004] Technical Solution: To achieve the above objectives, the present invention provides a visual inspection system for surface crack defects, comprising a horizontal linear conveyor platform on which several annular workpieces are horizontally placed at intervals; on the upper side of a portion of the linear conveyor platform, there are curved arrays of rollers a and b, which are curved from a top-view perspective; from a top-view perspective, a curved constraint channel is formed between the curved arrays of rollers a and b; during the conveying of the annular workpieces by the linear conveyor platform, the annular workpieces will pass along the curved constraint channel under the joint constraint of the curved arrays of rollers a and b; a downward-facing visual camera is located directly above the middle section of the curved constraint channel.

[0005] Furthermore, both the a-roller curve array and the b-roller curve array are formed by several vertical rollers arranged along the curve constraint channels corresponding to the top view angle; each vertical roller is rotatably mounted on the roller shaft through bearings, and the lower end of each roller shaft is fixed on the flat curve mounting frame; the flat curve mounting frame is a fixed structure and maintains a gap with the upper surface of the linear conveyor platform.

[0006] Furthermore, the two ends of the curved constraint channel are the workpiece inlet and the workpiece outlet, respectively. Both the workpiece inlet and the workpiece outlet are centered in the width direction of the linear conveyor platform, and the widths of both the workpiece inlet and the workpiece outlet are greater than the outer diameter of the annular workpiece.

[0007] Furthermore, the curve constraint channel, from the workpiece slide entrance to the workpiece slide exit, includes the workpiece slide entrance, centerline deviation channel, inflection point channel, centerline return channel, and workpiece slide exit in sequence; the vision camera is located directly above the inflection point channel.

[0008] Furthermore, on the path where the centerline deviates from the channel, the closer to the inflection point the channel deviates from the centerline of the linear conveyor platform, thus causing the annular workpiece conveyed on the linear conveyor platform to gradually deviate from the platform centerline during the displacement along the path where the centerline deviates from the channel.

[0009] On the path of the centerline return channel, the further away from the inflection point the channel is from the centerline of the linear conveyor platform, the closer it gets to the centerline of the linear conveyor platform. As the annular workpiece being transported on the linear conveyor platform moves along the path of the centerline return channel, it will gradually approach the centerline of the linear conveyor platform.

[0010] From a top-down perspective, the edge outline of the linear conveyor platform passes through the inflection point channel, creating a partial hollow section on the edge of the inflection point channel away from the platform's centerline.

[0011] A lifting seat is installed in the partially hollowed-out section. A lifting arm parallel to the edge contour line is fixedly connected to one side of the lifting seat. Several lifting support rollers are rotatably installed on the lifting arm along its length direction via bearings. From a top view, each lifting support roller is located in the partially hollowed-out section. A vertical shaft is fixed on the upper side of the lifting seat. A lifting rotation limit cylinder is rotatably installed on the outside of the vertical shaft via bearings. When the lifting rotation limit cylinder is higher than the upper surface of the linear conveyor platform, the annular workpiece entering the inflection point channel cannot move forward further due to the limitation of the lifting rotation limit cylinder.

[0012] Furthermore, the width of the inflection point channel is adapted to the outer diameter of the annular workpiece; from a top-down view, the maximum width of the local hollowed-out portion does not exceed one-third of the outer diameter of the annular workpiece.

[0013] Furthermore, a lifter is installed below the lifting base, and the lifter is connected to the lifting base via a lifting rod.

[0014] Furthermore, in the initial state, the lifting and rotating limiting cylinder is higher than the upper surface of the linear conveyor platform, and several lifting support rollers are not higher than the upper surface of the linear conveyor platform. When the linear conveyor platform is running, a ring-shaped workpiece conveyed on the linear conveyor platform smoothly slides into the workpiece sliding entrance. Subsequently, under the forward conveying of the linear conveyor platform, the ring-shaped workpiece is displaced along the path of the channel deviating from the centerline under the constraints of the a roller curve array and the b roller curve array, thus causing the ring-shaped workpiece to gradually deviate from the centerline of the linear conveyor platform. Until the ring-shaped workpiece reaches the inflection point channel, it is limited by the lifting and rotating limiting cylinder and cannot continue to move forward. At this time, the forward conveying of the linear conveyor platform is paused. At this time, the vision camera acquires an image of the upper surface of the ring-shaped workpiece from a top-down perspective. The lifting device drives the lifting seat to rise, causing several lifting support rollers to move upward, thus causing several lifting support rollers to lift the ring-shaped workpiece away from the channel. One end of the platform's centerline is tilted upwards, causing the end of the annular workpiece furthest from the platform's centerline to curve upwards, while the end closer to the platform's centerline remains supported by the upper surface of the linear conveyor platform. The vision camera scans two crescent-shaped partial images of the outer and inner surfaces of the annular workpiece from a top-down perspective. The linear conveyor platform continues to move forward. Since only the end of the annular workpiece tilted upwards is in contact with the support of the linear conveyor platform, and the annular workpiece cannot move forward due to the limitation imposed by the lifting and rotating limit cylinder, the continued forward movement of the linear conveyor platform will cause the annular workpiece to rotate around its own axis under the influence of friction. Because the vision camera can only scan partial images of the outer and inner surfaces of the annular workpiece in this posture, the vision camera continuously scans the complete outer and inner surfaces of the annular workpiece from a top-down perspective during at least one full rotation.

[0015] Subsequently, the lifting device lowers the lifting seat, causing several lifting support rollers and the lifting rotation limit cylinder to descend below the upper surface of the linear conveyor platform. This releases the limiting effect of the lifting rotation limit cylinder on the annular workpiece. At the same time, the end of the annular workpiece away from the platform centerline loses the support of the lifting support rollers and returns to a horizontal state. The annular workpiece, now in a horizontal state, enters the centerline return channel under the transmission of the linear conveyor platform. Under the forward transmission of the linear conveyor platform, the annular workpiece is displaced along the path of the centerline return channel under the constraints of the a-roller curve array and the b-roller curve array, gradually bringing the annular workpiece closer to the platform centerline. Finally, the annular workpiece exits from the workpiece slide outlet and continues to be transmitted on the linear conveyor platform, centered again.

[0016] Beneficial effects: The curved roller array of the present invention constructs a smooth curved constraint channel, guiding the annular workpiece to gradually deviate from the center line of the conveyor platform. A suitable local hollow structure is set at the inflection point of the channel, and with the support rollers driven by the lifting and the rotating limiting cylinder, the posture adjustment of the workpiece can be controlled to tilt on one side, so that the inner and outer ring surfaces that were originally impossible to scan are exposed in the field of view of the top-view camera.

[0017] The workpiece is driven to rotate around its own axis by the contact friction between the conveyor platform and the workpiece. No additional rotation drive components are required. A single top-view camera can complete the 360° continuous scanning and inspection of the inner and outer ring surfaces of the annular workpiece.

[0018] The width of the local cutouts is strictly controlled to ensure the stability of the workpiece support. The curved channel enables smooth guidance and centerline return of the workpiece when entering and leaving the inspection station. This not only eliminates the blind spots in the inspection of the inner and outer ring surfaces of the annular workpiece, but also simplifies the overall structure of the inspection equipment. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the device;

[0020] Figure 2 This is a schematic diagram from a top view before and after the ring-shaped workpiece is tilted up.

[0021] Figure 3 This is a partial structural diagram of the device;

[0022] Figure 4 This is a schematic diagram of the roller curve array a and roller curve array b from an upward viewing angle;

[0023] Figure 5 This is a schematic diagram of the lifting structure. Detailed Implementation

[0024] The invention will now be further described with reference to the accompanying drawings.

[0025] like Figures 1 to 5 The visual inspection system for surface crack defects shown includes a horizontal linear conveyor platform 11, on which several annular workpieces 1 are horizontally placed at intervals; on the upper side of a local position of the linear conveyor platform 11, there are curved arrays 12 of rollers a and b from a top-view perspective; from a top-view perspective, a curved constraint channel 14 is formed between the curved arrays 12 of rollers a and b.

[0026] During the process of conveying the annular workpiece 1 by the linear conveyor platform 11, the annular workpiece 1 will pass along the curve constraint channel 14 under the joint constraint of the a roller curve array 12 and the b roller curve array 12; a downward-facing vision camera 10 is set directly above the middle section of the curve constraint channel 14. The vision camera 10 is a high-definition industrial area array camera, which works in conjunction with a ring-shaped supplementary light source.

[0027] Both roller curve array 12 (a) and roller curve array 12 (b) are formed by arranging several vertical rollers 19 along the curve constraint channel corresponding to the top view. Each vertical roller 19 is rotatably mounted on a roller shaft 20 via bearings, and the lower end of each roller shaft 20 is fixed to a flat curve mounting frame 18. The flat curve mounting frame 18 is a fixed structure and maintains a gap of 1mm-2mm with the upper surface of the linear conveyor platform 11 to avoid interference with the conveyor platform and to prevent the annular workpiece 1 from getting stuck in the gap.

[0028] The two ends of the curved constraint channel 14 are the workpiece inlet 15a and the workpiece outlet 15e, respectively. Both the workpiece inlet 15a and the workpiece outlet 15e are centered in the width direction of the linear conveyor platform 11, and the width of both the workpiece inlet 15a and the workpiece outlet 15e is greater than the outer diameter of the annular workpiece 1. This allows the annular workpiece 1 conveyed on the linear conveyor platform 11 to slide smoothly into the workpiece inlet 15a. The curved constraint channel 14 includes the workpiece inlet 15a, the centerline deviation channel 15b, the inflection point channel 15c, the centerline return channel 15d, and the workpiece outlet 15e in sequence from the workpiece inlet 15a to the workpiece outlet 15e. The vision camera 10 is located directly above the inflection point channel 15c.

[0029] On the path where the centerline deviates from channel 15b, the closer to the inflection point channel 15c is, the more it deviates from the centerline of the linear conveyor platform 11. As a result, the annular workpiece 1 conveyed on the linear conveyor platform 11 will gradually deviate from the platform centerline 29 of the linear conveyor platform 11 during the displacement along the path where the centerline deviates from channel 15b. The slope of the deviation of the centerline from channel 15b is gentle and controllable. The lateral displacement rate of the annular workpiece 1 in this channel is uniform and will not cause inertial overturning due to sudden deviation.

[0030] On the path of the centerline return channel 15d, the further away from the inflection point channel 15c, the closer to the centerline of the linear conveyor platform 11. As a result, the annular workpiece 1 conveyed on the linear conveyor platform 11 moves along the path of the centerline return channel 15d, it will gradually approach the centerline of the linear conveyor platform 11. The slope of the centerline return channel 15d matches the centerline deviation channel 15b, forming a symmetrical guide structure, so that the annular workpiece 1 returns smoothly to the platform centerline 29, ensuring that the workpiece can still be conveyed in the center on the conveyor platform after it leaves.

[0031] From a top-down perspective, the edge contour line 11a of the linear conveyor platform 11 passes through the inflection point channel 15c, forming a partial hollow section 16 on the side edge of the inflection point channel 15c away from the platform centerline 29.

[0032] The width of the inflection point channel 15c is adapted to the outer diameter of the annular workpiece 1. In order to reserve a certain space for the annular workpiece 1 to tilt upward on one side in the future, the width of the inflection point channel 15c is larger than the outer diameter of the annular workpiece 1. From the top view, the maximum width of the local hollow part 16 does not exceed one-third of the outer diameter of the annular workpiece 1, so that the annular workpiece 1 reaching the inflection point channel 15c will not tilt or fall through the local hollow part 16. By utilizing the radial dimension support of the workpiece itself, the workpiece still has sufficient support stability on the hollow area side, eliminating the risk of tilting.

[0033] A lifting seat 4 is provided in the partially hollowed-out section 16, and a lifting device 2 is provided below the lifting seat 4. The lifting device 2 is connected to the lifting seat 4 through the lifting rod 2 for lifting and lowering drive. A lifting arm 5 parallel to the edge contour line 11a is fixedly connected to one side of the lifting seat 4. Several lifting support rollers 6 are rotatably installed on the lifting arm 5 along the length direction through bearings. From a top view, each lifting support roller 6 is in the partially hollowed-out section 16. A vertical shaft 7 is fixed on the upper side of the lifting seat 4. A lifting rotation limit cylinder 9 is coaxially rotatably provided outside the vertical shaft 7 through bearings 8. When the lifting rotation limit cylinder 9 is higher than the upper surface of the linear conveyor platform 11, the annular workpiece 1 that has entered the inflection point channel 15c cannot move forward further under the limit of the lifting rotation limit cylinder 9.

[0034] Work methods:

[0035] In the initial state, the lifting and rotating limiting cylinder 9 is higher than the upper surface of the linear conveyor platform 11, and several lifting support rollers 6 are not higher than the upper surface of the linear conveyor platform 11; the upper surface of the lifting support rollers 6 is flush with or slightly lower than the upper surface of the linear conveyor platform 11, which does not affect the normal sliding of the annular workpiece 1 into the inflection point channel 15c, ensuring that the workpiece can be accurately intercepted each time it is in place.

[0036] When the linear conveyor platform 11 is running, an annular workpiece 1 smoothly slides into the workpiece inlet 15a. Subsequently, under the forward conveying of the linear conveyor platform 11, the annular workpiece 1, constrained by the roller curve array 12 (a) and roller curve array 12 (b), deviates from the path of the channel 15b along the centerline, causing the annular workpiece 1 to gradually deviate from the platform centerline 29 of the linear conveyor platform 11. Until the annular workpiece 1 reaches the inflection point channel 15c, it is limited by the lifting and rotating limiting cylinder 9 and cannot continue moving forward. At this point, the forward conveying of the linear conveyor platform 11 is paused. Figure 3 As shown in the image above.

[0037] At this time, the vision camera 10 acquires an image of the upper surface of the annular workpiece 1 from a top-down perspective, such as... Figure 2 As shown in the figure above, the vision system then analyzes the image of the upper surface of the annular workpiece 1 in real time to see if there are obvious defects such as cracks or patches. Since the annular workpiece 1 has a certain thickness in the axial direction, it is also necessary to identify whether there are defects such as cracks or patches on the outer ring surface 1b and inner ring surface 1a of the annular structure of the annular workpiece 1, which are not easy to scan. However, at this time, the vision camera 10 cannot acquire the images of the outer ring surface 1b and inner ring surface 1a of the annular structure of the annular workpiece 1.

[0038] At this time, the lifting device 2 drives the lifting seat 4 to rise, thereby causing several lifting support rollers 6 to move upward, which in turn lifts the end of the annular workpiece 1 away from the platform centerline 29, thus causing the end of the annular workpiece 1 away from the platform centerline 29 to tilt upward, as shown. Figure 3 The image below shows the workpiece, while the end near the platform centerline 29 is still supported by the upper surface of the linear conveyor platform 11; the top-view image of the annular workpiece 1 with one end raised is as follows. Figure 2 As shown in the figure below, the vision camera 10 scans partial images of the outer ring surface 1b and inner ring surface 1a of the annular workpiece 1 from a top-down view. Figure 2 The two crescent-shaped shadow areas shown in the figure below are local areas of the outer ring surface 1b and the inner ring surface 1a of the annular workpiece 1, respectively, which enter the field of view of the vision camera 10, so that the vision camera 10 can obtain local area images of the outer ring surface 1b and the inner ring surface 1a of the annular workpiece 1 in this posture.

[0039] At this time, the linear conveyor platform 11 continues to convey forward. Since the lower surface of the annular workpiece 1, which is raised at one end, only has the end near the center line 29 of the platform in contact with the linear conveyor platform 11, and the annular workpiece 1 cannot move forward under the limitation of the lifting and rotating limiting cylinder 9, the continued forward conveying of the linear conveyor platform 11 will cause the annular workpiece 1 to rotate around its own axis under the influence of friction. Since the vision camera 10 can only scan the local area image of the outer ring surface 1b and inner ring surface 1a of the annular workpiece 1 in this posture, during the complete rotation of the annular workpiece 1 at least one revolution, the vision camera 10 achieves the purpose of continuously scanning the complete outer ring surface 1b and inner ring surface 1a of the annular workpiece 1 from a top-down perspective of 360°. Subsequently, the vision system or the human eye can analyze in real time whether there are obvious cracks, spots or other defects on the outer ring surface 1b and inner ring surface 1a of the annular workpiece 1. Although the image quality of this perspective is not as good as that of a completely vertical perspective, it is more than enough to identify obvious spots and large cracks on the surface, thereby effectively improving the yield rate of the product.

[0040] Subsequently, the lifting device 2 drives the lifting seat 4 to descend, thereby causing several lifting support rollers 6 and lifting rotation limit cylinders 9 to descend below the upper surface of the linear conveyor platform 11, releasing the limiting effect of the lifting rotation limit cylinders 9 on the annular workpiece 1. At the same time, after the end of the annular workpiece 1 away from the platform centerline 29 loses the support of the lifting support rollers 6, it returns to a horizontal state. At this time, the annular workpiece 1, which has returned to a horizontal state, enters the centerline return channel 15d under the transmission of the linear conveyor platform 11. Under the forward transmission of the linear conveyor platform 11, the annular workpiece 1 is displaced along the path of the centerline return channel 15d under the constraint of the a roller curve array 12 and the b roller curve array 12, thereby causing the annular workpiece 1 to gradually approach the platform centerline 29 of the linear conveyor platform 11. Finally, the annular workpiece 1 is transmitted from the workpiece slide outlet 15e and continues to be transmitted on the linear conveyor platform 11 again in a centered position.

[0041] In order to improve the integrity of the inspection in the subsequent process, the annular workpiece 1 can be flipped over by a flipping structure and then the reverse side can be visually inspected.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A visual inspection system for surface crack defects, characterized in that: It includes a horizontal linear conveyor platform (11), on which several annular workpieces (1) are placed horizontally at intervals. The linear conveyor platform (11) has a roller curve array (12) and a roller curve array (12) that are curved from a top view on the upper side of a certain position; from a top view, a curved constraint channel (14) is formed between the roller curve array (12) and the roller curve array (12). During the process of the linear conveyor platform (11) conveying the annular workpiece (1), the annular workpiece (1) will pass through the curve constraint channel (14) along the curve under the joint constraint of the a roller curve array (12) and the b roller curve array (12); there is a visual camera (10) with the lens facing downwards directly above the middle section of the curve constraint channel (14).

2. The visual inspection system for surface crack defects according to claim 1, characterized in that: Both the roller curve array (12) a and the roller curve array (12) are formed by several vertical rollers (19) arranged along the curve constraint channel corresponding to the top view. Each vertical roller (19) is rotatably mounted on the roller shaft (20) through bearings. The lower end of each roller shaft (20) is fixed on the flat curve mounting frame (18). The flat curve mounting frame (18) is a fixed structure and maintains a gap with the upper surface of the linear conveyor platform (11).

3. The surface defect visual inspection system for annular workpieces according to claim 2, characterized in that: The two ends of the curve constraint channel (14) are the workpiece slide entrance (15a) and the workpiece slide exit (15e), respectively. The workpiece slide entrance (15a) and the workpiece slide exit (15e) are both located in the center of the width direction of the linear conveyor platform (11), and the width of the workpiece slide entrance (15a) and the workpiece slide exit (15e) is greater than the outer diameter of the annular workpiece (1).

4. The surface defect visual inspection system for annular workpieces according to claim 3, characterized in that: The curve constraint channel (14) includes the workpiece slide entrance (15a), centerline deviation channel (15b), inflection point channel (15c), centerline return channel (15d) and workpiece slide exit (15e) in sequence from the workpiece slide entrance (15a) to the workpiece slide exit (15e); the vision camera (10) is located directly above the inflection point channel (15c).

5. The surface defect visual inspection system for annular workpieces according to claim 4, characterized in that: On the path of the centerline deviation channel (15b), the closer the channel is to the inflection point (15c), the more it deviates from the centerline of the linear conveyor platform (11). As a result, the annular workpiece (1) conveyed on the linear conveyor platform (11) will gradually deviate from the platform centerline (29) of the linear conveyor platform (11) during the displacement along the path of the centerline deviation channel (15b). On the path of the centerline return channel (15d), the further away from the inflection point channel (15c) the closer to the centerline of the linear conveyor platform (11), so that the annular workpiece (1) conveyed on the linear conveyor platform (11) will gradually approach the centerline of the linear conveyor platform (11) during the displacement along the path of the centerline return channel (15d). From a top-down perspective, the edge outline (11a) of the linear conveyor platform (11) passes through the inflection point channel (15c), forming a partial hollow section (16) on the side edge of the inflection point channel (15c) away from the platform centerline (29). A lifting seat (4) is provided in the partially hollowed-out part (16). A lifting arm (5) parallel to the edge contour line (11a) is fixedly connected to one side of the lifting seat (4). Several lifting support rollers (6) are rotatably installed on the lifting arm (5) along the length direction through bearings. From a top view, each lifting support roller (6) is in the partially hollowed-out part (16). A vertical shaft (7) is fixed on the upper side of the lifting seat (4). A lifting rotation limit cylinder (9) is coaxially rotatably provided on the outside of the vertical shaft (7) through bearings (8). When the lifting and rotating limiting cylinder (9) is higher than the upper surface of the linear conveyor platform (11), the annular workpiece (1) that enters the inflection point channel (15c) cannot move forward further under the limitation of the lifting and rotating limiting cylinder (9).

6. The surface defect visual inspection system for annular workpieces according to claim 5, characterized in that: The width of the inflection point channel (15c) is adapted to the outer diameter of the annular workpiece (1); from a top view, the maximum width of the local hollow part (16) does not exceed one-third of the outer diameter of the annular workpiece (1).

7. The surface defect visual inspection system for annular workpieces according to claim 5, characterized in that: A lifter (2) is provided below the lifting seat (4), and the lifter (2) is connected to the lifting seat (4) by lifting rod (2).

8. The working method of the visual inspection system for surface defects of annular workpieces according to claim 7, characterized in that: In the initial state, the lifting and rotating limiting cylinder (9) is higher than the upper surface of the linear conveying platform (11), and several lifting support rollers (6) are not higher than the upper surface of the linear conveying platform (11); When the linear conveyor platform (11) is running, a ring-shaped workpiece (1) conveyed on the linear conveyor platform (11) smoothly slides into the workpiece slide entrance (15a). Then, under the forward conveying of the linear conveyor platform (11), the ring-shaped workpiece (1) is displaced along the path of the centerline deviating from the channel (15b) under the constraints of the a roller curve array (12) and the b roller curve array (12), thereby causing the ring-shaped workpiece (1) to gradually deviate from the platform centerline (29) of the linear conveyor platform (11); until the ring-shaped workpiece (1) reaches the inflection point channel (15c) and is limited by the lifting and rotating limiting cylinder (9), it cannot continue to move forward. At this time, the forward conveying of the linear conveyor platform (11) is paused; at this time, the vision camera (10) acquires the image of the upper surface of the ring-shaped workpiece (1) from the top view. The lifting device (2) drives the lifting seat (4) to rise, causing several lifting support rollers (6) to move upward, thereby lifting the end of the annular workpiece (1) away from the platform centerline (29), so that the end of the annular workpiece (1) away from the platform centerline (29) tilts upward, while the end close to the platform centerline (29) is still supported by the upper surface of the linear conveying platform (11); the vision camera (10) scans two crescent-shaped partial images of the outer ring surface (1b) and inner ring surface (1a) of the annular workpiece (1) from a top-down perspective; At this time, the linear conveyor platform (11) continues to convey forward. Since the lower surface of the ring-shaped workpiece (1) with one end raised only has one end close to the center line (29) of the platform in contact with the support of the linear conveyor platform (11), and the ring-shaped workpiece (1) cannot move forward under the limitation of the lifting and rotating limiting cylinder (9), the continued forward conveying of the linear conveyor platform (11) will cause the ring-shaped workpiece (1) to rotate around its own axis under the influence of friction. Since the vision camera (10) can only scan the local area image of the outer ring surface (1b) and inner ring surface (1a) of the ring-shaped workpiece (1) in this posture, during the process of the ring-shaped workpiece (1) rotating at least one full circle, the vision camera (10) realizes 360° continuous scanning of the complete outer ring surface (1b) and inner ring surface (1a) of the ring-shaped workpiece (1) from the top view. Subsequently, the lifting device (2) drives the lifting seat (4) to descend, thereby causing several lifting support rollers (6) and the lifting rotation limit cylinder (9) to descend below the upper surface of the linear conveyor platform (11), releasing the limiting effect of the lifting rotation limit cylinder (9) on the annular workpiece (1). At the same time, after the end of the annular workpiece (1) away from the center line (29) of the platform loses the support of the lifting support rollers (6), it returns to a horizontal state. At this time, the annular workpiece (1) that has returned to a horizontal state is on the linear conveyor platform (11). Under the transmission of the linear conveyor platform (11), the annular workpiece (1) enters the centerline return channel (15d). Under the forward transmission of the linear conveyor platform (11), the annular workpiece (1) is displaced along the path of the centerline return channel (15d) under the constraints of the a roller curve array (12) and the b roller curve array (12), thereby causing the annular workpiece (1) to gradually approach the platform centerline (29) of the linear conveyor platform (11). Finally, the annular workpiece (1) is transmitted from the workpiece slide outlet (15e) and continues to be transmitted on the linear conveyor platform (11) again in a centered position.

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