A method for detecting small defects on the surface of a gravure roller

Abstract

The application relates to a method for detecting small defects on the surface of a gravure roller, and relates to the technical field of small defect detection on the surface of a gravure roller, which comprises the following steps: step one, cleaning treatment is performed on the surface of the gravure roller, and specifically, oil stains on the surface of the gravure roller are removed, and the cleaning operation is repeated 2-3 times; step two, the cleaned gravure roller is installed on a detection device to perform defect detection, and the gravure roller is kept rotating at a constant speed during the detection process; step three, the gravure roller completing the detection is taken off from the detection device, and the detected defect positions are marked. The servo motor drives the screw rod to rotate, on the one hand, dynamic defect detection is realized on the whole surface of the gravure roller, the detection efficiency and the detection precision of the detection device are improved, on the other hand, the effect of real-time cleaning is realized, the use effect of the detection device is improved, and on the other hand, the effect of automatic area isolation is realized, and the operation safety of the detection device is improved.

Description

Technical Field

[0001] This invention relates to the field of gravure printing roller surface micro-defect detection technology, specifically a method for detecting micro-defects on the surface of gravure printing rollers. Background Technology

[0002] Gravure printing rollers are core components of the printing industry, and their surface quality directly determines the final quality of printed products. As the printing industry continues to demand higher precision and clarity in its prints, the need for accurate detection of minute defects on the roller surface, such as scratches, pits, and uneven coating, is becoming increasingly urgent.

[0003] Currently, the industry still widely uses manual visual inspection combined with magnifying glasses for inspection. This method is not only inefficient but also easily affected by factors such as the subjective experience and fatigue of the inspectors, leading to a high rate of missed defects and false positives. In recent years, machine vision technology has been gradually applied to the field of industrial surface inspection. However, for highly reflective curved workpieces such as gravure printing rollers, existing technologies still face technical bottlenecks such as poor imaging quality and difficulty in extracting defect features, making it difficult to meet the actual needs of high-precision inspection.

[0004] Therefore, it is necessary to invent a method for detecting minute defects on the surface of gravure printing rollers to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for detecting minute defects on the surface of gravure printing rollers, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for detecting minute defects on the surface of gravure printing rollers, comprising the following steps;

[0007] Step 1: Clean the surface of the gravure printing roller, specifically removing oil and dirt from the roller surface. Repeat the cleaning operation 2-3 times.

[0008] Step 2: Install the cleaned gravure printing roller on the detection device for defect detection, and keep the roller rotating at a constant speed during the detection process;

[0009] Step 3: Remove the gravure printing roller that has completed the inspection from the inspection device and mark the location of the detected defects;

[0010] The detection device in step two includes a frame and a support. A pneumatic center tailstock is detachably mounted on the upper end of the frame via bolts. A support frame is fixed to the upper end of the frame. A sliding groove is opened in the middle of the support frame. A servo motor is fixed to one end of the support frame. A lead screw is fixed to the drive end of the servo motor. A connecting structure is provided on the lead screw. A detection camera is provided on the connecting structure. The connecting structure can move the detection camera along the length of the sliding groove and rotate the printing roller around its own central axis to perform dynamic defect detection on the printing roller.

[0011] Preferably, the connection structure includes a ball nut and a drive wheel. The lower end of the ball nut is detachably mounted with a mounting bracket by bolts. A detection camera is fixed at the lower end of the mounting bracket. The detection camera is equipped with a ring light source. A first filter is attached to the surface of the ring light source. A second filter is attached to the lens of the detection camera. The drive wheel is connected to the driven wheel by a synchronous belt. A rotating frame is fixed in the middle of the driven wheel. A pressing frame is fixed at one end of the rotating frame.

[0012] Preferably, the spiral raceway of the lead screw and the inner raceway of the ball nut are engaged by rolling balls, the outer surface of the ball nut is slidably connected to the inner wall of the groove, the middle part of the drive wheel is fixed to the other end of the lead screw, the outer surface of the lead screw is rotatably connected to the inner wall of the support frame, the two ends of the support frame are fixed to the middle of both sides of the frame body, and the vertical section of the support frame is U-shaped.

[0013] Preferably, the driving wheel and the driven wheel are connected by a synchronous belt, the middle of the driven wheel is fixed to one side of the rotating frame, the outer surface of the rotating frame is rotatably connected to the inner wall of one side of the support frame, the vertical cross-section of the rotating frame is cross-shaped, one end of the rotating frame is fixed to the middle of the extrusion frame, the outer surface of the other side of the extrusion frame abuts and is positioned against the outer surface of one end of the printing roller, and the output shaft of the pneumatic center tailstock abuts and is positioned against the outer surface of the other end of the printing roller.

[0014] Preferably, a drive gear is fixed to the other end of the rotating frame, the drive gear meshes with a driven gear, a connecting rod is fixed to the middle of the driven gear, a fan impeller is fixed to the other end of the connecting rod, a connecting ring is fixed to the outside of the fan impeller, a ventilation slot is opened through one side of the frame, and a number of ventilation holes are opened on the side of the ventilation slot away from the opening, and a guide frame is fixed to the other end of each ventilation hole.

[0015] Preferably, the middle part of the driving gear is fixed to the end of the rotating frame away from the extrusion frame, the driving gear is meshed with the driven gear, the middle part of the driven gear is fixed to one end of the connecting rod, the other end of the connecting rod is fixed to the middle of the fan impeller, and the outer side of the fan impeller is fixed to the middle of the connecting ring.

[0016] Preferably, the outer surface of the connecting ring is rotatably connected to the inner wall of the ventilation slot near the opening, the vertical cross-section of the connecting ring is circular, the ventilation slot is connected to a plurality of ventilation holes, the plurality of ventilation holes are connected to a plurality of air guides, and the vertical cross-section of each air guide is V-shaped.

[0017] Preferably, the frame has limit grooves on both sides, and slide plates are slidably connected to the inner walls of the two limit grooves. A fixing frame is fixed to one side of the two slide plates, a connecting frame is fixed in the middle of the fixing frame, and a compression block is fixed to the upper end of the ball nut.

[0018] Preferably, the outer surfaces of the two slide plates are slidably connected to the inner walls of the two limiting grooves, and one side of the two slide plates is fixed to both ends of the fixing frame, wherein the vertical section of the fixing frame is U-shaped.

[0019] Preferably, one end of the connecting frame is fixed in the middle of the fixing frame, the outer surface of the connecting frame is in contact with the outer surface of the extrusion block, the outer surface of the fixing frame is in contact with the outer surface of the extrusion block, and the vertical cross-section of the extrusion block is set as a right-angled triangle.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] (1) The present invention uses a servo motor to drive the lead screw to rotate, so that the pneumatic center tailstock, lead screw, ball nut, mounting frame, detection camera, ring light source, first filter, second filter, driving wheel, driven wheel, rotating frame and extrusion frame work together to realize dynamic defect detection on the entire surface of the printing roller; through real-time image processing, defect features are identified, a detection report is generated and the defect location is marked, thereby improving the detection efficiency and detection accuracy of the detection device;

[0022] (2) The present invention uses a servo motor to drive the lead screw to rotate, so that the driving gear, driven gear, connecting rod, fan impeller, connecting ring, ventilation slot, ventilation hole and air guide frame work together to achieve the effect of real-time cleaning, avoid dust and impurities from affecting the test results, and thus improve the effect of the test device.

[0023] (3) The present invention uses a servo motor to drive the lead screw to rotate, so that the limiting groove, slide plate, fixing frame, connecting frame and extrusion block work together to achieve the effect of automatic area isolation, play a protective shielding role, and effectively improve the operation safety of the detection device. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the process principle of the present invention;

[0025] Figure 2 This is an overall structural diagram of the present invention;

[0026] Figure 3 This is a partial structural cross-sectional view of the present invention;

[0027] Figure 4 For the present invention Figure 3 Enlarged view of the structure of section A in the middle;

[0028] Figure 5 This is a cross-sectional view of the frame of the present invention;

[0029] Figure 6 This is a schematic diagram of the detection camera structure of the present invention;

[0030] Figure 7 The pneumatic tip tailstock of this invention;

[0031] Figure 8 This is a partial structural diagram of the present invention;

[0032] Figure 9 This is a schematic diagram of the frame structure of the present invention.

[0033] In the diagram: 1. Frame; 2. Bracket; 3. Pneumatic center tailstock; 4. Support frame; 5. Slide groove; 6. Servo motor; 7. Lead screw; 8. Ball nut; 9. Mounting frame; 10. Detection camera; 11. Ring light source; 12. First filter; 13. Second filter; 14. Drive wheel; 15. Driven wheel; 16. Rotating frame; 17. Extrusion frame; 18. Drive gear; 19. Driven gear; 20. Connecting rod; 21. Fan impeller; 22. Connecting ring; 23. Ventilation slot; 24. Ventilation hole; 25. Air guide frame; 26. Limiting slot; 27. Slide plate; 28. Fixing frame; 29. ​​Connecting frame; 30. Extrusion block. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] Please see Figure 1 - Figure 9 As shown, this embodiment of the invention provides a method for detecting minute defects on the surface of gravure printing rollers, including the following steps;

[0037] Step 1: Clean the surface of the gravure printing roller, specifically removing oil and dirt from the roller surface. Repeat the cleaning operation 2-3 times.

[0038] Step 2: Install the cleaned gravure printing roller on the detection device for defect detection, and keep the roller rotating at a constant speed during the detection process;

[0039] Step 3: Remove the gravure printing roller that has completed the inspection from the inspection device and mark the location of the detected defects;

[0040] The detection device in step two includes a frame 1 and a support 2. A pneumatic center tailstock 3 is detachably mounted on the upper end of the frame 1 via bolts. A support frame 4 is fixed to the upper end of the frame 1. A sliding groove 5 is provided in the middle of the support frame 4. A servo motor 6 is fixed to one end of the support frame 4. A lead screw 7 is fixed to the drive end of the servo motor 6. A connecting structure is provided on the lead screw 7, which includes a ball nut 8 and a drive wheel 14. A mounting frame 9 is detachably mounted on the lower end of the ball nut 8 via bolts. A detection camera 10 is fixed to the lower end of the mounting frame 9. A ring light source is provided on the detection camera 10. 11. A first filter 12 is attached to the surface of the ring light source 11, and a second filter 13 is attached to the lens of the detection camera 10. The driving wheel 14 is connected to the driven wheel 15 via a synchronous belt. A rotating frame 16 is fixed in the middle of the driven wheel 15, and a pressing frame 17 is fixed at one end of the rotating frame 16. The pressing frame 17 works with the pneumatic center tailstock 3 to position the printing roller. The shaft of the pneumatic center tailstock 3 is rotatable. During the positioning process, the pneumatic center tailstock 3 is driven by an air source to extend forward, forming a bidirectional clamping force with the pressing frame 17 to firmly clamp the printing roller. Between the two, the printing roller is coaxially positioned to ensure that the axis of the printing roller coincides with the transmission axis of the detection device, avoiding radial runout during the detection process. When the lead screw 7 drives the drive wheel 14 to rotate and drives the rotating frame 16 to rotate, the extrusion frame 17 rotates synchronously with the rotating frame 16. At this time, the rotatable output shaft of the pneumatic tip tailstock 3 rotates passively, providing a continuous and stable clamping force for the printing roller without hindering its rotational movement, ensuring that the printing roller can rotate smoothly with the extrusion frame 17. This design of the rotatable tip structure and the extrusion frame 17 solves the wear and jamming problems that are prone to occur when the traditional fixed tip drives the workpiece to rotate, effectively reducing the frictional resistance during the rotation of the printing roller and ensuring that the printing roller is always in a uniform rotational state. At the same time, the bidirectional clamping positioning method can also be adapted to printing rollers of different lengths. By adjusting the extension stroke of the pneumatic tip tailstock 3, diverse detection needs can be met, greatly improving the adaptability and versatility of the detection device, providing a stable workpiece movement basis for the dynamic scanning imaging of the subsequent detection camera 10, and further ensuring the accuracy of micro-defect detection.

[0041] Please refer to it again. Figure 1 - Figure 9As shown, the spiral raceway of the lead screw 7 and the inner raceway of the ball nut 8 are engaged by rolling balls. The outer surface of the ball nut 8 is slidably connected to the inner wall of the groove 5. The middle part of the drive wheel 14 is fixed to the other end of the lead screw 7. The outer surface of the lead screw 7 is rotatably connected to the inner wall of the support frame 4. The two ends of the support frame 4 are fixed to the middle of both sides of the frame 1. The vertical section of the support frame 4 is U-shaped. The drive wheel 14 and the driven wheel 15 are connected by a synchronous belt. The middle part of the driven wheel 15 is fixed to one side of the rotating frame 16. The outer surface of the rotating frame 16 is rotatably connected to the inner wall of one side of the support frame 4. The vertical section of the rotating frame 16 is cross-shaped. One end of the rotating frame 16 is fixed to the middle of the extrusion frame 17. The outer surface of the other side of the extrusion frame 17 abuts and is positioned against the outer surface of one end of the printing roller. The output shaft of the pneumatic center tailstock 3 abuts and is positioned against the outer surface of the other end of the printing roller.

[0042] The specific implementation process is as follows: The servo motor 6 drives the lead screw 7 to rotate. The spiral raceway of the lead screw 7 engages with the inner raceway of the ball nut 8 through the rolling of the balls, so that the ball nut 8 slides along the axial direction of the lead screw 7 under the limiting and guiding action of the slide groove 5. The sliding ball nut 8 drives the mounting frame 9, which is detachably connected to its lower end by bolts, to move synchronously. This, in turn, drives the detection camera 10, which is fixed at the lower end of the mounting frame 9, to move synchronously. The lens of the detection camera 10 is set at a 45° angle with the horizontally placed printing roller generatrix. At the same time, the driving wheel 14, which is fixedly connected to the other end of the lead screw 7, rotates synchronously with the lead screw 7 and drives the driven wheel 15 to rotate synchronously through the synchronous belt. The driven wheel 15 drives the rotating frame 16, which is fixed in the middle, to rotate stably under the support and limiting action of the support frame 4. The extrusion frame 17, which is fixed at one end of the rotating frame 16, cooperates with the pneumatic center tailstock 3 installed on the other side of the frame 1 to achieve coaxial contact and positioning of the printing roller placed between the two, and drives the printing roller to rotate synchronously.

[0043] While the inspection camera 10 moves axially along the lead screw 7, the printing roller rotates synchronously. Combined with the 45° angled arrangement of the inspection camera 10, and the ring light source 11, the first filter 12 attached to the ring light source 11, and the second filter 13 attached to the lens of the inspection camera 10, the specular reflection light on the surface of the printing roller can be effectively suppressed, realizing dynamic defect detection of the entire surface of the printing roller. By identifying defect features through real-time image processing, an inspection report is generated and the defect location is marked, thereby improving the inspection efficiency and accuracy of the inspection device.

[0044] Example 2

[0045] Dust and impurities easily adhere to the surface of the printing roller during the inspection process. Such foreign objects can interfere with the imaging accuracy of defect identification, leading to misjudgment or missed judgment in the inspection results. Therefore, it is necessary to clean the dust and impurities on the surface of the printing roller in real time during the inspection operation to ensure the accuracy of the inspection data and improve the actual application effect of the inspection device.

[0046] Please see Figure 1 - Figure 9 As shown, a real-time cleaning function has been added based on Embodiment 1;

[0047] Please refer to it again. Figure 1 - Figure 9 As shown, a drive gear 18 is fixed to the other end of the rotating frame 16. The drive gear 18 is meshed with a driven gear 19. A connecting rod 20 is fixed to the middle of the driven gear 19. A fan impeller 21 is fixed to the other end of the connecting rod 20. A connecting ring 22 is fixed to the outside of the fan impeller 21. A ventilation slot 23 is opened through one side of the frame 1. Several ventilation holes 24 are opened on the side of the ventilation slot 23 away from the opening. A guide frame 25 is fixed to the other end of each ventilation hole 24. The drive gear 18 is fixed to the middle of the rotating frame 16. The moving frame 16 is located away from the end of the extrusion frame 17. The driving gear 18 meshes with the driven gear 19. The middle of the driven gear 19 is fixed to one end of the connecting rod 20, and the other end of the connecting rod 20 is fixed to the middle of the fan impeller 21. The outer side of the fan impeller 21 is fixed to the middle of the connecting ring 22. The outer surface of the connecting ring 22 is rotatably connected to the inner wall of the ventilation groove 23 near the opening. The vertical section of the connecting ring 22 is circular. The ventilation groove 23 is connected to several ventilation holes 24, and the several ventilation holes 24 are connected to several... The air guide frames 25 are interconnected, and each air guide frame 25 has a V-shaped vertical section. The air guide frame 25 blows the air drawn in by the rotating impeller 21 toward the printing roller, realizing directional blowing and cleaning of the printing roller detection area. The air guide frame 25 has a guide channel inside, which can rectify and pressurize the drawn-in air, so that the blown airflow forms a stable linear air curtain, accurately covering the printing roller surface area corresponding to the detection camera 10. At this time, the printing roller is in a rotating state, and the airflow can act evenly on its surface along the circumference of the printing roller, quickly blowing away the attached dust and impurities, avoiding such foreign objects from interfering with the imaging accuracy of the detection camera 10, and preventing false or missed defects. At the same time, the stable blowing airflow can also form an air film on the surface of the printing roller, reducing the secondary adhesion of suspended particles in the air during subsequent detection, providing a clean surface environment for defect detection. This directional blowing structure works in conjunction with the rotation of the printing roller to realize real-time dynamic cleaning of the detection area, further ensuring the accuracy and reliability of the detection results.

[0048] The specific implementation process is as follows: The servo motor 6 drives the lead screw 7 to rotate, which drives the driving wheel 14 fixed at the other end of the lead screw 7 to rotate synchronously; the rotating driving wheel 14 drives the driven wheel 15 to rotate through the synchronous belt, and rotates synchronously with the rotating frame 16 fixed in the middle of the driven wheel 15 under the limiting action of the inner wall of the support frame 4, thereby driving the driving gear 18 fixed at one end of the rotating frame 16 to rotate.

[0049] The driving gear 18 meshes with the driven gear 19. Since the driving gear 18 has more teeth than the driven gear 19, the driven gear 19 rotates at a faster speed. The rapidly rotating driven gear 19 drives the connecting rod 20, which is fixed in the middle, to rotate synchronously. The fan impeller 21, which is fixed at the other end of the connecting rod 20, rotates at high speed along the inner wall of the ventilation slot 23 opened in the frame 1 under the limiting and guiding of the side connecting ring 22. The high-speed rotating fan impeller 21 draws in air, which enters the air guide frame 25 fixed at the other end of the ventilation slot 24 through several ventilation holes 24 opened in the middle of the ventilation slot 23. Under the guiding action of the air guide frame 25, the air is blown onto the surface of the rotating printing roller, which cleans the detection area of ​​the detection camera 10 in real time, achieving the effect of real-time cleaning and avoiding the adhesion of dust and impurities that affect the detection results, thereby improving the effectiveness of the detection device.

[0050] Example 3

[0051] During the printing roller inspection process, the printing roller needs to be flipped to complete the full surface inspection. However, during the flipping process, the printing roller is prone to position displacement or even slippage, posing a safety hazard of squeezing the operator's hand. Therefore, it is necessary to set up an isolation and protection structure in the inspection work space to avoid safety risks and improve the operational safety of the inspection device.

[0052] Please see Figure 1 - Figure 9 As shown, an automatic region isolation function has been added based on Embodiment 1;

[0053] Please refer to it again. Figure 1 - Figure 9 As shown, limit grooves 26 are provided on both sides of the frame 1. Slide plates 27 are slidably connected to the inner walls of the two limit grooves 26. A fixing frame 28 is fixed to one side of the two slide plates 27. A connecting frame 29 is fixed in the middle of the fixing frame 28. An extrusion block 30 is fixed to the upper end of the ball nut 8. The outer surfaces of the two slide plates 27 are slidably connected to the inner walls of the two limit grooves 26. One side of the two slide plates 27 is fixed to both ends of the fixing frame 28. The vertical section of the fixing frame 28 is U-shaped. One end of the connecting frame 29 is fixed in the middle of the fixing frame 28. The outer surface of the connecting frame 29 is in contact with the outer surface of the extrusion block 30. The outer surface of the fixing frame 28 is in contact with the outer surface of the extrusion block 30. The vertical section of the extrusion block 30 is a right triangle.

[0054] The specific implementation process is as follows: The servo motor 6 drives the lead screw 7 to rotate. The spiral raceway of the lead screw 7 engages with the inner raceway of the ball nut 8 through the rolling of the balls. Under the limiting action of the slide groove 5, the ball nut 8 slides along the axial direction of the lead screw 7, thereby driving the pressing block 30 fixed at the upper end of the ball nut 8 to move synchronously. When the pressing block 30 initially moves, its inclined surface contacts the surface of the fixed frame 28. Under the pressing action of the inclined surface, the fixed frame 28 drives the two slide plates 27 fixed at both ends to slide steadily upward along the limiting grooves 26 opened on both sides of the frame 1. Until the pressing block 30 slides to the position of the connecting frame 29 fixed in the middle of the fixed frame 28, the fixed frame 28 moves synchronously to the highest point, and the two slide plates 27 also move with the fixed frame 28 to the highest point of the limiting groove 26. At this time, the two slide plates 27 isolate the detection area, leaving only the observation space above.

[0055] After the inspection is completed, the ball nut 8 drives the extrusion block 30 to reset in the opposite direction. The two slide plates 27 lose the extrusion force and move down along the limit groove 26 to reset to the initial position under their own gravity. This does not affect the disassembly and assembly of the printing roller, achieves the effect of automatic area isolation, plays a protective and shielding role, and effectively improves the operational safety of the inspection device.

[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for detecting minute defects on the surface of gravure printing rollers, characterized in that, Includes the following steps; Step 1: Clean the surface of the gravure printing roller, specifically removing oil and dirt from the roller surface. Repeat the cleaning operation 2-3 times. Step 2: Install the cleaned gravure printing roller on the detection device for defect detection, and keep the roller rotating at a constant speed during the detection process; Step 3: Remove the gravure printing roller that has completed the inspection from the inspection device and mark the location of the detected defects; The detection device in step two includes a frame (1) and a support (2). A pneumatic center tailstock (3) is detachably installed on the upper end of the frame (1) by bolts. A support frame (4) is fixed on the upper end of the frame (1). A slide groove (5) is opened in the middle of the support frame (4). A servo motor (6) is fixed on one end of the support frame (4). A lead screw (7) is fixed on the drive end of the servo motor (6). A connecting structure is provided on the lead screw (7). A detection camera (10) is provided on the connecting structure. The connecting structure can move the detection camera (10) along the length of the slide groove (5) on one hand, and rotate the printing roller around its own central axis on the other hand, so as to perform dynamic defect detection on the printing roller.

2. The method for detecting minute defects on the surface of gravure printing rollers according to claim 1, characterized in that: The connection structure includes a ball nut (8) and a drive wheel (14). The lower end of the ball nut (8) is detachably mounted with a mounting bracket (9) by bolts. The lower end of the mounting bracket (9) is fixed with a detection camera (10). The detection camera (10) is provided with a ring light source (11). A first filter (12) is pasted on the surface of the ring light source (11). A second filter (13) is pasted on the lens of the detection camera (10). The drive wheel (14) is connected to the driven wheel (15) by a synchronous belt. A rotating frame (16) is fixed in the middle of the driven wheel (15). A pressing frame (17) is fixed at one end of the rotating frame (16).

3. The method for detecting minute defects on the surface of gravure printing rollers according to claim 2, characterized in that: The spiral raceway of the lead screw (7) and the inner wall raceway of the ball nut (8) are engaged by rolling balls. The outer surface of the ball nut (8) is slidably connected to the inner wall of the groove (5). The middle part of the drive wheel (14) is fixed to the other end of the lead screw (7). The outer surface of the lead screw (7) is rotatably connected to the inner wall of the support frame (4). The two ends of the support frame (4) are fixed to the middle of both sides of the frame (1). The vertical section of the support frame (4) is U-shaped.

4. The method for detecting minute defects on the surface of a gravure printing roller according to claim 2, characterized in that: The driving wheel (14) and the driven wheel (15) are connected by a synchronous belt. The middle part of the driven wheel (15) is fixed on one side of the rotating frame (16). The outer surface of the rotating frame (16) is rotatably connected to the inner wall of one side of the support frame (4). The vertical section of the rotating frame (16) is arranged in a cross shape. One end of the rotating frame (16) is fixed in the middle of the extrusion frame (17). The outer surface of the other side of the extrusion frame (17) abuts against the outer surface of one end of the printing roller for positioning. The output shaft of the pneumatic center tailstock (3) abuts against the outer surface of the other end of the printing roller for positioning.

5. The method for detecting minute defects on the surface of gravure printing rollers according to claim 2, characterized in that: The rotating frame (16) is fixed with a drive gear (18) at the other end. The drive gear (18) is meshed with a driven gear (19). A connecting rod (20) is fixed in the middle of the driven gear (19). A fan impeller (21) is fixed at the other end of the connecting rod (20). A connecting ring (22) is fixed on the outside of the fan impeller (21). A ventilation slot (23) is opened through one side of the frame (1). Several ventilation holes (24) are opened on the side of the ventilation slot (23) away from the opening. A guide frame (25) is fixed at the other end of each ventilation hole (24).

6. The method for detecting minute defects on the surface of a gravure printing roller according to claim 5, characterized in that: The driving gear (18) is fixed in the middle at one end of the rotating frame (16) away from the extrusion frame (17). The driving gear (18) meshes with the driven gear (19). The driven gear (19) is fixed in the middle at one end of the connecting rod (20). The other end of the connecting rod (20) is fixed in the middle of the fan impeller (21). The outer side of the fan impeller (21) is fixed in the middle of the connecting ring (22).

7. A method for detecting minute defects on the surface of a gravure printing roller according to claim 5, characterized in that: The outer surface of the connecting ring (22) is rotatably connected to the inner wall of the ventilation slot (23) near the opening. The vertical section of the connecting ring (22) is circular. The ventilation slot (23) is connected to several ventilation holes (24). The several ventilation holes (24) are connected to several air guides (25). The vertical section of each air guide (25) is V-shaped.

8. A method for detecting minute defects on the surface of a gravure printing roller according to claim 2, characterized in that: The frame (1) has limit grooves (26) on both sides. The inner walls of the two limit grooves (26) are slidably connected with slide plates (27). A fixing frame (28) is fixed on one side of the two slide plates (27). A connecting frame (29) is fixed in the middle of the fixing frame (28). A pressing block (30) is fixed at the upper end of the ball nut (8).

9. A method for detecting minute defects on the surface of a gravure printing roller according to claim 8, characterized in that: The outer surfaces of the two slide plates (27) are slidably connected to the inner walls of the two limiting grooves (26), and one side of the two slide plates (27) is fixed to both ends of the fixing frame (28). The vertical section of the fixing frame (28) is U-shaped.

10. A method for detecting minute defects on the surface of a gravure printing roller according to claim 8, characterized in that: One end of the connecting frame (29) is fixed in the middle of the fixing frame (28). The outer surface of the connecting frame (29) is in contact with the outer surface of the extrusion block (30). The outer surface of the fixing frame (28) is in contact with the outer surface of the extrusion block (30). The vertical section of the extrusion block (30) is set as a right triangle.

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