Galvanized steel sheet surface defect automatic oil scraping and ink jet marking system and method

Abstract

The galvanized steel sheet surface defect automatic oil scraping and ink jet marking system comprises a base steel frame and a servo motor, conveying rollers distributed at equal intervals are rotationally arranged at the top of the base steel frame, and L-shaped fixing plates are fixed to the two sides of one end of the top of the base steel frame through bolts; industrial high-definition cameras are fixed to the two L-shaped fixing plates correspondingly, first side supporting frames are welded to the two sides of the outer wall of the top of the base steel frame correspondingly, sliding grooves are formed in the inner walls of the first side supporting frames in the length direction, and supporting plates are slidably connected to the inner walls of the sliding grooves in an inserted mode. The servo motor drives the two-way lead screw to adjust the distance to adapt to galvanized steel sheets with different widths, so that when the alloy scraper carries out oil film scraping treatment, lateral limiting support can be provided, the galvanized steel sheets are prevented from sliding to affect the oil film scraping treatment, and the service life of the alloy scraper is prolonged. And the modular layout of the first side support frame and the second side support frame is arranged on the non-driving side behind the galvanization line inspection table, so that the existing roller system and tension system are not physically interfered.

Description

Technical Field

[0001] This invention relates to the field of galvanized steel sheet technology, and in particular to an automatic oil scraping and inkjet marking system and method for surface defects of galvanized steel sheets. Background Technology

[0002] Hot-dip galvanized steel sheets, with their excellent surface quality and corrosion resistance, have become a core raw material for automotive exterior body panels (such as doors, hoods, and fenders). Their surface quality directly determines the overall aesthetics and brand image of the vehicle. Therefore, high-end automotive OEMs demand "zero-defect" delivery, requiring precise identification and control of even minor defects such as scabs, dents, and scratches. Currently, to meet the delivery demands of large coils (20-30 tons per coil), the industry commonly employs a "manual positioning-wiping-line marking" defect marking method: first, defect location data (accuracy ±0.5 meters) is obtained through a quality assessment system; operators then cross the production line or lie under the strip steel to wipe the defective area with a cloth to reduce the rust-preventive oil film; then, a 45° diagonal line (single line width ≤10cm, length ≤5 meters) is drawn along the rolling direction using a marker. Simultaneously, an "electronic defect card" is created and delivered with the coil, allowing the customer to remove defective areas based on the markings. This method is currently the main means of defect control in high-end automotive steel sheet production, but it has many unavoidable problems in practical application.

[0003] Existing technologies have three major shortcomings in practical applications: The process is extremely inefficient and labor-intensive. Handling a single defect takes ≥15 minutes, including manual positioning, wiping across the production line, drawing lines, and waiting for the ink to dry. For ultra-wide boards, an extension pole is required for operation, which is physically demanding and severely slows down the production line pace, making it difficult to meet the high-volume demand for large rolls. The quality of marking is uncontrollable and affected by the difference in operator skills. The 45° diagonal line angle deviation and line width fluctuate greatly. In addition, the 2-5 micron thick anti-rust oil film on the surface of hot-dip galvanized steel plate cannot be completely removed by manual wiping (the residual oil film is ≥2 microns). This causes the adhesion of marker ink to decrease by more than 50%. The marking is easy to become blurred and fall off due to transportation friction and humid environment. Customers often cannot accurately locate defects due to unclear markings. There are safety risks and secondary pollution. When operators cross the production line or work close to the strip steel, personal safety accidents are likely to occur. Furthermore, the undried ink can easily spread and contaminate the good product area within an 8-10 meter range during rewinding. In order to ensure "zero defects", customers need to scrap the contaminated area as well, which leads to a significant decrease in the yield rate and directly causes economic losses and customer complaints. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an automatic oil scraping and inkjet marking system and method for surface defects of galvanized steel sheets.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheets includes a base steel frame and a servo motor. The top of the base steel frame is rotatably equipped with equally spaced conveying rollers. L-shaped fixing plates are bolted to both sides of one end of the base steel frame. Industrial high-definition cameras are fixed to both L-shaped fixing plates. First side support frames are welded to both sides of the top outer wall of the base steel frame. A sliding groove is formed along the length of the inner wall of the first side support frame, and a support plate is slidably inserted into the inner wall of the sliding groove. Servo cylinders are fixed to both ends of the bottom of the support plate with screws. An equally spaced circular through-slot is formed through the top outer wall of the support plate. A threaded rod is inserted into the inner wall of the circular through-slot, and a connecting plate is connected to the bottom of the threaded rod. An alloy scraper is fixed along the length of the bottom outer wall of the connecting plate with screws. A displacement sensor is installed vertically at the bottom of the first side support frame, and oil film sensors are fixed to both sides of the first side support frame with L-shaped fixing blocks. The base steel frame has a second side support frame welded to both ends of the outer wall on the other side of the top. The second side support frame is fixed to the top of the second side support frame by bolts. The second electric slide rail is slidably inserted into the inner wall of the second electric slide rail. A mechanical arm is fixedly installed on the top of the second electric slide rail. An inkjet head is fixed to the end of the mechanical arm. An ink injection tube is connected to the top of the inkjet head. A ring-shaped hot air nozzle is fixed around the inkjet head by a bracket. A PLC controller is fixed to one side of the outer wall of the second side support frame by screws.

[0006] Preferably, a nut is threaded onto the outer wall of the end of the threaded rod, and a disc spring is sleeved on the outer wall of the threaded rod between the connecting plate and the support plate.

[0007] Preferably, a first electric slide rail is fixed to one outer wall of the first side support frame by screws, and a first electric slider is slidably inserted into the inner wall of the first electric slide rail. A wiping sponge is adhered to the top outer wall of the first electric slider, and the first electric slide rail is distributed parallel to the width direction of the base steel frame.

[0008] Preferably, the bottom of the base steel frame is provided with a guide rail parallel to the width direction, and a guide block is slidably inserted into the inner wall of the guide rail. The middle of each guide block is threaded with a bidirectional lead screw, and one end of the bidirectional lead screw is connected to a servo motor through a coupling.

[0009] Preferably, each guide block has a side clamping roller mounted on its top in a vertical direction, and the outside of each side clamping roller is bonded with a protective rubber pad.

[0010] Preferably, the inner wall of the annular hot air nozzle has an annular guide groove along the inclined direction, and an air inlet pipe is connected through one side of the inner wall of the annular hot air nozzle, with the end of the air inlet pipe inserted into the drying shell.

[0011] Preferably, a temperature sensor is installed on the top inner wall of the drying shell, and a rectangular mounting groove is opened through the bottom inner wall of the drying shell. An air intake fan is fixedly engaged on the inner wall of the rectangular mounting groove, and electric heating rods are installed and fixed on both inner walls of the drying shell.

[0012] Preferably, the PLC controller is electrically connected to the industrial high-definition camera, servo cylinder, displacement sensor, oil film sensor, servo motor, second electric slide rail, second electric slider, robotic arm, temperature sensor, air intake fan and electric heating rod, and the PLC controller is connected to an external power supply through wires.

[0013] An automatic oil scraping and inkjet marking method for surface defects of galvanized steel sheets includes the following steps: Step 1: The operator places the galvanized steel sheet to be inspected on the conveyor roller at the top of the base steel frame. After starting the system, the external transmission mechanism drives the conveyor roller to rotate, which in turn transports the steel sheet to the defect detection area. Step 2: The PLC controller sends a control signal to the servo motor (model SGMSV-20D3A61). The servo motor drives the bidirectional lead screw to rotate. The bidirectional lead screw drives the guide block to move towards each other along the guide rail until the two lateral clamping rollers are in contact with the sides of the steel plate. Because the lateral clamping rollers have protective rubber pads attached to their outside and can rotate with the steel plate during transport, it can avoid damaging the steel plate and ensure that the steel plate remains centered during transport, preventing deviation from affecting the accuracy of subsequent detection and marking. Step 3: During the conveying process, the PLC controller receives the rotation speed signal of the conveying roller in real time (the sensor is not shown in the figure), calculates the conveying position of the steel plate, and provides a basis for subsequent defect location. When the steel plate is conveyed to the defect detection area, the PLC controller controls the industrial high-definition camera (model MV-CE200-10GM) to start. The industrial high-definition camera captures images of the steel plate surface in real time, identifies defects such as scabs, indentations, and scratches, and transmits the coordinate data of the defects (accuracy ±0.3m) to the PLC controller. Step 4: Based on the defect coordinates, the PLC controller controls the support plate on the first side support frame to move along the sliding groove, so that the alloy scraper is aligned directly above the defect area. The displacement sensor (model KTC-500) detects the height of the undulation on the steel plate surface and feeds the data back to the PLC controller. The PLC controller adjusts the downward pressure (50-200N adjustable) of the servo cylinder (model CDA2B40-50Z) according to the data to avoid excessive pressure damaging the zinc layer or insufficient pressure for thorough oil scraping. Step 5: The servo cylinder drives the connecting plate and the alloy scraper to move downwards. The alloy scraper (blade angle 60°±5°) contacts the steel plate surface and scrapes off the oil film in the defect area. During the oil scraping process, the oil film sensor (model OS101) detects the oil film thickness in real time. If the residual oil film is detected to be >0.5μm, the signal is fed back to the PLC controller. The PLC controller controls the servo cylinder to fine-tune the downward pressure or controls the support plate to move back and forth until the residual oil film is ≤0.5μm. Step Six: After the oil scraping is completed, the PLC controller controls the first electric slide rail to start, and the first electric slider drives the wiping sponge to move back and forth along the width of the steel plate to wipe the oil film adhering to the bottom of the alloy scraper. After wiping, the conveying roller continues to drive the steel plate to the inkjet marking area. Step 7: When the defective area of ​​the steel plate is transported to the inkjet area, the PLC controller sends a signal to the second electric slide rail according to the defect coordinates transmitted by the industrial high-definition camera. The second electric slider moves along the second electric slide rail. At the same time, the robotic arm (model IRB120) is started. Through three-axis adjustment, the inkjet head (model KM512LH) is precisely aligned with the defective area with a positioning accuracy of ±1mm. Step 8: The PLC controller controls the inkjet head to draw special resistant ink through the ink injection tube and spray the marking onto the defect area according to the preset parameters (the line direction required by the customer, such as 45° diagonal line, horizontal or vertical line, or custom graphic). The line width accuracy is ±0.5mm, which meets the customer's standardization requirements. Step 9: While the ink is being printed, the PLC controller sends signals to the intake fan (model AX12038) and the electric heating rod (model XDM-220). The intake fan draws in outside air, and the electric heating rod heats the air to 80℃±10℃. The hot air enters the annular hot air nozzle through the intake pipe and is evenly blown to the ink-printing area through the annular guide groove, with a wind speed of 15m / s. Step 10: The temperature sensor (model PT100) monitors the hot air temperature in real time and feeds the data back to the PLC controller. The PLC controller fine-tunes the power of the electric heating rod according to the data to ensure the hot air temperature is stable and the ink is cured within ≤3 seconds. After drying, the conveyor roller drives the steel plate to continue to be conveyed. The marked steel plate is sent out from the output end of the base steel frame. The whole process is completed. The PLC controller records the defect marking data for easy traceability later.

[0014] The beneficial effects of this invention are as follows: 1. This invention uses an alloy scraper to precisely remove the oil film from defective areas, and combines it with special ink and a ring-shaped hot air nozzle to achieve rapid drying at 80℃±10℃. This improves the adhesion of the marking and significantly reduces the contamination rate when the client unwinds the roll. At the same time, relying on the three-axis servo drive of the second electric slide rail and the robotic arm, it can realize three standard drawing directions: diagonal, horizontal and vertical lines, with an angle deviation of ≤1° and a line width fluctuation of ≤±0.3mm. This completely eliminates the problems of non-standard, blurry and detached marking caused by manual operation, reduces the defect omission rate, and thus improves work efficiency. 2. This invention achieves full-process automation through a PLC controller. After receiving the defect coordinates of the inspection system, it automatically triggers the servo cylinder to drive the alloy scraper to scrape oil and the robotic arm to drive the inkjet head to mark. The processing time for a single defect is greatly shortened, manual intervention is reduced, and annual labor costs are significantly saved. At the same time, operators do not need to cross the production line or get close to the strip steel, which completely avoids personal safety risks. In addition, the fast-drying design of the annular hot air nozzle eliminates the manual waiting time for drying. The production line speed is matched, which can be seamlessly adapted to the continuous production of large-tonnage steel coils. 3. The guide rail and side clamping rollers at the bottom of the base steel frame of this invention can be adjusted in spacing by a servo motor-driven bidirectional screw to adapt to galvanized steel plates of different widths. This provides lateral limiting support when the alloy scraper is performing oil film scraping, preventing the galvanized steel plate from sliding and affecting the oil film scraping process. Furthermore, the modular layout of the first and second side support frames is deployed on the non-drive side behind the inspection table of the galvanizing line, without physical interference with the existing roller system and tension system. In addition, during the oil scraping process of the alloy scraper, the disc spring set above, in conjunction with the servo cylinder, ensures that the oil scraping effect is not affected, while effectively buffering and protecting the galvanized steel plate. Attached Figure Description

[0015] Figure 1 This is a front view of the overall structure of an automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheets proposed in this invention. Figure 2 This is a bottom view of the overall structure of an automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheets proposed in this invention. Figure 3 This is a schematic diagram of the overall three-dimensional structure of an automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheet proposed in this invention. Figure 4 This is a side view of the overall three-dimensional structure of an automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheets proposed in this invention. Figure 5 This is a partial structural diagram of an automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheets proposed in this invention; Figure 6 This is a first-view structural schematic diagram of an automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheet proposed in this invention.

[0016] In the diagram: 1. Base steel frame; 2. Conveyor roller; 3. L-shaped fixing plate; 4. Industrial high-definition camera; 5. First side support frame; 6. Sliding groove; 7. Support plate; 8. Servo cylinder; 9. Circular through groove; 10. Threaded rod; 11. Connecting plate; 12. Nut; 13. Disc spring; 14. Alloy scraper; 15. Displacement sensor; 16. Oil film sensor; 17. First electric slide rail; 18. First electric slider; 19. Wiping sponge; 20. Guide. 21. Guide rail; 22. Guide block; 23. Bidirectional lead screw; 24. Servo motor; 25. Side clamping roller; 26. Second side support frame; 27. Second electric slide rail; 28. Second electric slider; 29. ​​Robotic arm; 30. Inkjet head; 31. Ink filling tube; 32. Annular hot air nozzle; 33. Annular guide groove; 34. Air inlet pipe; 35. Drying shell; 36. Temperature sensor; 37. Air inlet fan; 38. Electric heating rod; 39. PLC controller. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] Example 1, referring to Figure 1-6 An automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheets includes a base steel frame 1 and a servo motor 23. The top of the base steel frame 1 is rotatably equipped with equally spaced conveyor rollers 2, and L-shaped fixing plates 3 are bolted to both sides of one end of the top of the base steel frame 1. Industrial high-definition cameras 4 are fixed to both L-shaped fixing plates 3. First side support frames 5 are welded to both sides of the top outer wall of the base steel frame 1. The inner wall of the first side support frame 5 has a sliding groove 6 along its length, and the inner wall of the sliding groove 6 is slidably inserted into... There is a support plate 7, and servo cylinders 8 are fixed to both ends of the bottom of the support plate 7 by screws. The outer wall of the top of the support plate 7 has circular slots 9 that are evenly distributed. Threaded rods 10 are inserted into the inner wall of the circular slots 9, and the bottom of the threaded rods 10 is connected to a connecting plate 11. Alloy scrapers 14 are fixed to the bottom outer wall of the connecting plate 11 along the length direction by screws. A displacement sensor 15 is installed at the bottom of the first side support frame 5 along the vertical direction, and oil film sensors 16 are fixed to both sides of the first side support frame 5 by L-shaped fixing blocks. The base steel frame 1 has a second side support frame 25 welded to both ends of the outer wall on the other side of the top. The second side support frame 25 is fixed to the top of the second electric slide rail 26 by bolts. The inner wall of the second electric slide rail 26 is slidably connected to the second electric slider 27. The top of the second electric slider 27 is fixedly installed with a robotic arm 28. The end of the robotic arm 28 is fixed with an inkjet head 29. The top of the inkjet head 29 is connected to an ink injection tube 30. The inkjet head 29 is fixed around the annular hot air nozzle 31 by a bracket. The outer wall of one side of the second side support frame 25 is fixed with a PLC controller 38 by screws. The threaded rod 10 is threaded with a nut 12 on the outer wall of its end, and a disc spring 13 is sleeved on the outer wall of the threaded rod 10 between the connecting plate 11 and the support plate 7. The outer wall of one side of the first side support frame 5 is fixed with a first electric slide rail 17 by screws, and a first electric slider 18 is slidably inserted into the inner wall of the first electric slide rail 17. A wiping sponge 19 is adhered to the top outer wall of the first electric slider 18, and the first electric slide rail 17 is parallel to the width direction of the base steel frame 1. The bottom of the base steel frame 1 is provided with a guide rail 20 parallel to the width direction, and a guide block 21 is slidably inserted into the inner wall of the guide rail 20. The middle of the guide block 21 is threaded with a double screw 22, and one end of the double screw 22 is connected to a servo motor 23 through a coupling. The top of the guide block 21 is rotatably mounted with a side clamping roller 24 in the vertical direction, and a protective rubber pad is glued to the outside of the side clamping roller 24. The inner wall of the annular hot air nozzle 31 is provided with an annular guide groove 32 along the inclined direction, and an air inlet pipe 33 is provided through the inner wall of one side of the annular hot air nozzle 31. The end of the air inlet pipe 33 is inserted into the drying shell 34. A temperature sensor 35 is installed on the top inner wall of the drying housing 34, and a rectangular mounting groove is opened through the bottom inner wall of the drying housing 34. An air intake fan 36 is fixedly engaged on the inner wall of the rectangular mounting groove, and electric heating rods 37 are installed and fixed on both inner walls of the drying housing 34. The PLC controller 38 is electrically connected to the industrial high-definition camera 4, servo cylinder 8, displacement sensor 15, oil film sensor 16, servo motor 23, second electric slide rail 26, second electric slider 27, robotic arm 28, temperature sensor 35, air intake fan 36 and electric heating rods 37, and the PLC controller 38 is connected to an external power source through wires.

[0019] Example 2, refer to Figure 1-6An automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheets includes a conveying and positioning module with a base steel frame 1 as the basic carrier. The top of the base steel frame 1 is rotatably equipped with equally spaced conveying rollers 2. The conveying rollers 2 are driven by an external transmission mechanism (not shown in the figure) to achieve stable conveying of galvanized steel sheets. The conveying speed can be adjusted according to the production line requirements, with a maximum support of ≤100m / min. To ensure that the steel sheets do not deviate during the conveying process, two guide rails 20 are arranged parallel to each other along the width direction at the bottom of the base steel frame 1. Two guide blocks 21 are slidably inserted into the inner wall of each guide rail 20. A bidirectional screw 22 is threadedly connected to the middle of the four guide blocks 21. One end of the bidirectional screw 22 is fixedly connected to the output shaft of a servo motor 23 (model SGMSV-20D3A61) through a coupling. After the servo motor 23 is powered on, it can drive the bidirectional lead screw 22 to rotate in both directions, thereby driving the guide blocks 21 on both sides to move in opposite directions along the guide rail 20. Each guide block 21 has a side clamping roller 24 mounted on its top via a bearing in the vertical direction. The side clamping roller 24 has a protective rubber pad with a thickness of 5mm bonded to its outside, which can not only avoid damaging the surface of the steel plate, but also enhance the friction and ensure that the steel plate is always kept in the center position during transportation. It is suitable for galvanized steel plates with a width of 500-2000mm, and meets the transportation needs of steel plates for automotive exterior body panels of different specifications. The defect detection and oil removal module is deployed on the top of the base steel frame 1 near the input end. It is mainly responsible for defect identification and oil film removal. On both sides of the top end of the base steel frame 1, L-shaped fixing plates 3 are fixed by bolts. The two L-shaped fixing plates 3 are symmetrically distributed. The lower surface of the horizontal section of each plate is fixed with an industrial high-definition camera 4 (model MV-CE200-10GM). The lens of the camera 4 is vertically downward aimed at the surface of the steel plate on the conveying roller 2. It can capture images of the steel plate surface in real time, capture defects such as scabs, indentations, and scratches, and transmit the defect coordinate data (accuracy ±0.3m) to the PLC controller 38. On both sides of the top outer wall of the base steel frame 1, two first side support frames 5 are symmetrically welded. The two first side support frames 5 are in a portal structure spanning above the steel plate. The inner wall of the first side support frame 5 has a sliding groove 6 along the length direction (consistent with the steel plate conveying direction). A support plate 7 is slidably inserted into the inner wall of the sliding groove 6. The position of the support plate 7 can be finely adjusted along the sliding groove 6 to ensure that the oil removal component below it can accurately align with the defect area. Both ends of the bottom of the support plate 7 are fixed with servo cylinders 8 (model CDA2B40-50Z) by screws. The piston rod of the servo cylinder 8 is set vertically downward, and its output end can provide an adjustable downward pressure of 50-200N. The downward pressure is adjusted by the PLC controller 38 to avoid excessive pressure damaging the zinc layer of the steel plate (protecting the zinc layer thickness ≥3μm). The top outer wall of the support plate 7 has evenly distributed circular slots 9. A threaded rod 10 is inserted into the inner wall of each circular slot 9. The bottom of the threaded rod 10 passes through the circular slot 9 and is fixedly connected to the top of the connecting plate 11. An alloy scraper 14 is fixed along the length of the bottom outer wall of the connecting plate 11 by screws. The blade angle of the 14 is designed to be 60°±5°. The high hardness material ensures that it is not easily worn when scraping oil and its service life can reach more than 6 months. In order to achieve buffering and adjustment of oil scraping pressure, the outer wall of the threaded rod 10 is connected to the nut 12, and the outer wall of the threaded rod 10 between the connecting plate 11 and the support plate 7 is fitted with a disc spring 13. The elastic coefficient of the disc spring 13 can be selected according to the requirements. When the servo cylinder 8 drives the support plate 7 to press down, the disc spring 13 can absorb part of the impact force and avoid rigid contact between the alloy scraper 14 and the steel plate surface. At the same time, the pre-compression of the disc spring 13 can be adjusted by tightening or loosening the nut 12, thereby fine-tuning the oil scraping force of the alloy scraper 14 and ensuring that the oil film residue in the defect area is ≤0.5μm. In addition, a first electric slide rail 17 (model EJH20) is fixed to one outer wall of the first side support frame 5 by screws. The length direction of the first electric slide rail 17 is parallel to the width direction of the base steel frame 1. A first electric slider 18 is slidably inserted into its inner wall. A 10mm thick wiping sponge 19 is adhered to the top outer wall of the first electric slider 18. The wiping sponge 19 is made of high-density polyester fiber, which can absorb a small amount of residual oil. After the alloy scraper 14 finishes scraping the oil, the first electric slider 18 can move back and forth along the first electric slide rail 17, driving the wiping sponge 19 to perform a second wiping of the scraped area, further removing trace amounts of residual oil film, and providing a cleaner surface for subsequent inkjet marking. A displacement sensor 15 (model KTC-500) is also installed vertically at the bottom of the first side support frame 5. The detection end of the displacement sensor 15 is aligned with the surface of the steel plate and can detect the height of the steel plate in real time. The data is transmitted to the PLC controller 38, which then adjusts the downward pressure of the servo cylinder 8 to avoid incomplete oil scraping or damage to the zinc layer due to fluctuations in the thickness of the steel plate. Oil film sensors 16 (model OS101) are fixed on both sides of the first side support frame 5 by L-shaped fixing blocks. The detection end of the oil film sensor 16 is close to the surface of the steel plate and can detect the thickness of the oil film in the area after oil scraping. If the oil film residue is detected to be >0.5μm, a feedback signal is sent to the PLC controller 38 to trigger the alloy scraper 14 to scrape the oil a second time to ensure that the oil scraping effect meets the standard. The inkjet and drying module is deployed on the top of the base steel frame 1 near the output end. It is responsible for precise inkjet marking and rapid drying of defective areas after ink scraping. Two second-side support frames 25 are symmetrically welded to both ends of the outer wall of the other side of the top of the base steel frame 1. The tops of both second-side support frames 25 are bolted with second electric slide rails 26 (model EJH20). The length direction of the two second electric slide rails 26 is consistent with the length direction of the base steel frame 1. A second electric slider 27 is slidably inserted into their inner walls. The second electric slider 27 can reciprocate along the second electric slide rails 26 to achieve positioning along the steel plate conveying direction. A robotic arm 28 (model IRB) is fixedly installed on the top of the second electric slider 27. 120), the robotic arm 28 has a three-axis adjustment function and a positioning accuracy of ±1mm. Its end is fixed with an inkjet head 29 (model KM512LH) via a flange. The top of the inkjet head 29 is connected to an ink injection tube 30. The other end of the ink injection tube 30 is connected to an external ink supply system (not shown in the figure) to deliver special ink-resistant water. The inkjet head 29 supports dot matrix / vector dual-mode output, with a line width accuracy of ±0.5mm and a standard line width of 10mm. It can also switch between three line drawing directions—45° diagonal line, horizontal (0°), and vertical (90°)—via the PLC controller 38. It can also call the built-in graphic library (circle, rectangle, arrow) to generate customer-customized marks (such as the 9 concentric circles required by Tesla). To achieve rapid ink drying, an annular hot air nozzle 31 is fixed around the inkjet head 29 by a bracket. The axis of the annular hot air nozzle 31 coincides with the axis of the inkjet head 29. Its bottom is 50mm away from the surface of the steel plate. An annular guide groove 32 is opened on the inner wall along the inclined direction. The annular guide groove 32 can make the hot air evenly distributed and avoid local overheating and damage to the steel plate. An air inlet pipe 33 is connected through one side of the inner wall of the annular hot air nozzle 31. The end of the air inlet pipe 33 is inserted into the drying shell 34. The drying shell 34 is fixed on the second side support frame 25 by a bracket. A temperature sensor 35 (model PT100) is installed on the inner wall of its top to monitor the temperature inside the drying shell in real time. The hot air temperature is measured and the data is fed back to the PLC controller 38. A rectangular mounting slot is opened through the bottom inner wall of the drying housing 34. An air intake fan 36 (model AX12038) is fixedly attached to the inner wall of the rectangular mounting slot. After the air intake fan 36 is powered on, it can draw in external air. Electric heating rods 37 (model XDM-220) are installed and fixed on both sides of the inner wall of the drying housing 34. The electric heating rods 37 can heat the air drawn in by the air intake fan 36 to 80℃±10℃. The heated hot air enters the annular hot air nozzle 31 through the air intake pipe 33 and blows it towards the ink-printing area at a wind speed of 15m / s, so that the ink can be cured within ≤3 seconds, completely eliminating the contamination caused by the ink not being dry. The electrical control module is based on a PLC controller 38 (model S7-1200CPU1214C), which is fixed to the outer wall of one side of the second support frame 25 with screws. The input terminals of the PLC controller 38 are connected to the industrial high-definition camera 4, displacement sensor 15, oil film sensor 16, and temperature sensor 35 through wires, respectively, to receive data such as defect coordinates, steel plate displacement, oil film thickness, and hot air temperature transmitted by each sensor and camera. The output terminals of the PLC controller 38 are connected to the servo cylinder 8, servo motor 23, first electric slide rail 17, second electric slide rail 26, robotic arm 28, air intake fan 36, and electric heating rod 37 through wires, respectively, to control the actions of each actuator according to the input data. At the same time, the PLC controller 38 is connected to an external power supply through wires to provide power to the entire system, and supports parameter setting (such as pressure, hot air temperature, and line drawing direction) and status monitoring through the HMI interface to realize full-process automated control.

[0020] An automatic oil scraping and inkjet marking method for surface defects of galvanized steel sheets, characterized by comprising the following steps: Step 1: The operator places the galvanized steel sheet to be inspected on the conveyor roller 2 at the top of the base steel frame 1. After starting the system, the external transmission mechanism drives the conveyor roller 2 to rotate, which in turn transports the steel sheet to the defect detection area. Step 2: The PLC controller 38 sends a control signal to the servo motor 23 (model SGMSV-20D3A61). The servo motor 23 drives the bidirectional lead screw 22 to rotate. The bidirectional lead screw 22 drives the guide block 21 to move towards each other along the guide rail 20 until the two side clamping rollers 24 are in contact with the side of the steel plate. Since the side clamping rollers 24 have protective rubber pads on the outside and can rotate with the steel plate during transport, it can avoid damaging the steel plate and ensure that the steel plate is always centered during transport, preventing deviation from affecting the accuracy of subsequent detection and marking. Step 3: During the conveying process, the PLC controller 38 receives the rotation speed signal of the conveying roller 2 in real time (the sensor is not shown in the diagram), calculates the conveying position of the steel plate, and provides a basis for subsequent defect location. When the steel plate is conveyed to the defect detection area, the PLC controller 38 controls the industrial high-definition camera 4 (model MV-CE200-10GM) to start. The industrial high-definition camera 4 captures images of the steel plate surface in real time, identifies defects such as scabs, indentations, and scratches, and transmits the coordinate data of the defects to the PLC controller 38 with an accuracy of ±0.3m. Step 4: Based on the defect coordinates, the PLC controller 38 controls the support plate 7 on the first side support frame 5 to move along the sliding groove 6, so that the alloy scraper 14 is aligned directly above the defect area. The displacement sensor 15 (model KTC-500) detects the height of the undulation on the steel plate surface and feeds the data back to the PLC controller 38. The PLC controller 38 adjusts the downward pressure of the servo cylinder 8 (model CDA2B40-50Z) according to the data, which is adjustable from 50-200N, to avoid excessive pressure damaging the zinc layer or insufficient pressure for thorough oil scraping. Step 5: The servo cylinder 8 drives the connecting plate 11 and the alloy scraper 14 to move downwards. The alloy scraper 14 has a blade angle of 60°±5° to contact the steel plate surface and scrape off the oil film in the defect area. During the oil scraping process, the oil film sensor 16 (model OS101) detects the oil film thickness in real time. If the residual oil film is detected to be >0.5μm, the signal is fed back to the PLC controller 38. The PLC controller 38 controls the servo cylinder 8 to fine-tune the downward pressure or controls the support plate 7 to move back and forth until the residual oil film is ≤0.5μm. Step 6: After the oil scraping is completed, the PLC controller 38 controls the first electric slide rail 17 to start, and the first electric slider 18 drives the wiping sponge 19 to move back and forth along the width of the steel plate to wipe the oil film stuck to the bottom of the alloy scraper 14. After wiping, the conveying roller 2 continues to drive the steel plate to the inkjet marking area. Step 7: When the defective area of ​​the steel plate is transported to the inkjet area, the PLC controller 38 sends a signal to the second electric slide rail 26 according to the defect coordinates transmitted by the industrial high-definition camera 4. The second electric slider 27 moves along the second electric slide rail 26. At the same time, the robotic arm 28 (model IRB120) is started. Through three-axis adjustment, the inkjet head 29 (model KM512LH) is precisely aligned with the defective area, with a positioning accuracy of ±1mm. Step 8: The PLC controller 38 controls the inkjet head 29 to draw special resistant ink through the ink injection tube 30 according to the preset parameters and the customer's required line drawing direction, such as 45° diagonal lines, horizontal or vertical lines, or custom graphics, and sprays the markings onto the defect area with a line width accuracy of ±0.5mm to meet the customer's standardization requirements. Step 9: While the ink is being printed, the PLC controller 38 sends signals to the intake fan 36 (model AX12038) and the electric heating rod 37 (model XDM-220). The intake fan 36 draws in outside air, and the electric heating rod 37 heats the air to 80℃±10℃. The hot air enters the annular hot air nozzle 31 through the intake pipe 33 and is evenly blown towards the ink-printing area through the annular guide groove 32, with a wind speed of 15m / s. Step 10: Temperature sensor 35 (PT100) monitors the hot air temperature in real time and feeds the data back to PLC controller 38. PLC controller 38 fine-tunes the power of electric heating rod 37 based on the data to ensure stable hot air temperature and achieve ink curing within ≤3 seconds. After drying, conveyor roller 2 drives the steel plate to continue conveying. The marked steel plate is sent out from the output end of base steel frame 1, and the entire process ends. PLC controller 38 records defect marking data for easy traceability later.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheets, comprising a base steel frame (1) and a servo motor (23), characterized in that, The top of the base steel frame (1) is rotatably equipped with equally spaced conveying rollers (2), and both sides of the top end of the base steel frame (1) are fixed with L-shaped fixing plates (3) by bolts. Industrial high-definition cameras (4) are fixed on both L-shaped fixing plates (3). The top outer wall of the base steel frame (1) is welded with first side support frames (5). The inner wall of the first side support frame (5) is opened with a sliding groove (6) along the length direction, and a support plate (7) is slidably inserted into the inner wall of the sliding groove (6). Both ends of the bottom of the support plate (7) are connected by... A servo cylinder (8) is fixed with screws, and a circular through groove (9) with equal spacing is opened through the top outer wall of the support plate (7). A threaded rod (10) is inserted into the inner wall of the circular through groove (9), and a connecting plate (11) is connected to the bottom of the threaded rod (10). An alloy scraper (14) is fixed to the bottom outer wall of the connecting plate (11) along the length direction by screws. A displacement sensor (15) is installed at the bottom of the first side support frame (5) along the vertical direction, and an oil film sensor (16) is fixed on both sides of the first side support frame (5) by L-shaped fixing blocks. The base steel frame (1) has a second side support frame (25) welded to both ends of the outer wall on the other side of the top. The second side support frame (25) is fixed to the top of the second electric slide rail (26) by bolts. The second electric slide rail (26) is slidably inserted into the inner wall of the second electric slide rail (26). The second electric slider (27) is fixedly installed on the top of the second electric slider (27). The end of the mechanical arm (28) is fixed with an inkjet head (29). The top of the inkjet head (29) is connected to an ink injection tube (30). The inkjet head (29) is fixed around the annular hot air nozzle (31) by a bracket. The outer wall of one side of the second side support frame (25) is fixed with a PLC controller (38) by screws.

2. The automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheet according to claim 1, characterized in that, The threaded rod (10) has a nut (12) threadedly connected to the outer wall at the end, and a disc spring (13) is sleeved on the outer wall of the threaded rod (10) between the connecting plate (11) and the support plate (7).

3. The automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheet according to claim 1, characterized in that, The outer wall of one side of the first side support frame (5) is fixed with a first electric slide rail (17) by screws, and the inner wall of the first electric slide rail (17) is slidably inserted with a first electric slider (18). The top outer wall of the first electric slider (18) is adhered with a wiping sponge (19), and the first electric slide rail (17) is parallel to the width direction of the base steel frame (1).

4. The automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheet according to claim 3, characterized in that, The bottom of the base steel frame (1) is provided with a guide rail (20) parallel to the width direction, and a guide block (21) is slidably inserted into the inner wall of the guide rail (20). The middle part of the guide block (21) is threaded with a two-way screw (22), and one end of the two-way screw (22) is connected to a servo motor (23) through a coupling.

5. The automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheet according to claim 4, characterized in that, Each guide block (21) has a side clamping roller (24) mounted on its top in a vertical direction, and the outside of each side clamping roller (24) is covered with a protective rubber pad.

6. The automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheet according to claim 1, characterized in that, The inner wall of the annular hot air nozzle (31) has an annular guide groove (32) in an inclined direction, and an air inlet pipe (33) is connected through one side of the inner wall of the annular hot air nozzle (31). The end of the air inlet pipe (33) is inserted into the drying shell (34).

7. The automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheet according to claim 6, characterized in that, A temperature sensor (35) is installed on the top inner wall of the drying housing (34), and a rectangular mounting groove is opened through the bottom inner wall of the drying housing (34). An air intake fan (36) is fixedly attached to the inner wall of the rectangular mounting groove, and electric heating rods (37) are installed and fixed on both inner walls of the drying housing (34).

8. The automatic oil scraping and inkjet marking system for surface defects of galvanized steel sheet according to claim 7, characterized in that, The PLC controller (38) is electrically connected to the industrial high-definition camera (4), servo cylinder (8), displacement sensor (15), oil film sensor (16), servo motor (23), second electric slide rail (26), second electric slider (27), robotic arm (28), temperature sensor (35), air intake fan (36) and electric heating rod (37), and the PLC controller (38) is connected to an external power source through wires.

9. A method for automatic oil scraping and inkjet marking of surface defects on galvanized steel sheets, using the automatic oil scraping and inkjet marking system for surface defects on galvanized steel sheets as described in claim 1, characterized in that... Includes the following steps: Step 1: The operator places the galvanized steel plate to be inspected on the conveyor roller (2) at the top of the base steel frame (1). After starting the system, the external transmission mechanism drives the conveyor roller (2) to rotate, which in turn transports the steel plate to the defect detection area. Step 2: The PLC controller (38) sends a control signal to the servo motor (23) (model SGMSV-20D3A61). The servo motor (23) drives the bidirectional lead screw (22) to rotate. The bidirectional lead screw (22) drives the guide block (21) to move towards each other along the guide rail (20) until the two lateral clamping rollers (24) are in contact with the side of the steel plate. Since the lateral clamping rollers (24) are bonded with protective rubber pads and can rotate with the steel plate during transport, they can avoid damaging the steel plate and ensure that the steel plate is always centered during transport, preventing deviation from affecting the accuracy of subsequent detection and marking. Step 3: During the conveying process, the PLC controller (38) receives the rotation speed signal of the conveying roller (2) in real time (the sensor is not shown in the figure), calculates the conveying position of the steel plate, and provides a basis for subsequent defect location. When the steel plate is conveyed to the defect detection area, the PLC controller (38) controls the industrial high-definition camera (4) (model MV-CE200-10GM) to start. The industrial high-definition camera (4) captures images of the steel plate surface in real time, identifies defects such as scars, indentations, and scratches, and transmits the coordinate data of the defects (accuracy ±0.3m) to the PLC controller (38). Step 4: The PLC controller (38) controls the support plate (7) on the first side support frame (5) to move along the sliding groove (6) according to the defect coordinates, so that the alloy scraper (14) is aligned with the top of the defect area. The displacement sensor (15) (model KTC-500) detects the height of the undulation of the steel plate surface and feeds the data back to the PLC controller (38). The PLC controller (38) adjusts the downward pressure of the servo cylinder (8) (model CDA2B40-50Z) (50-200N adjustable) according to the data to avoid excessive pressure damaging the zinc layer or insufficient pressure for thorough oil scraping. Step 5: The servo cylinder (8) drives the connecting plate (11) and the alloy scraper (14) to move down. The alloy scraper (14) (blade angle 60°±5°) contacts the steel plate surface and scrapes off the oil film in the defect area. During the oil scraping process, the oil film sensor (16) (model OS101) detects the oil film thickness in real time. If the residual oil film is detected to be >0.5μm, the signal is fed back to the PLC controller (38). The PLC controller (38) controls the servo cylinder (8) to fine-tune the downward pressure or controls the support plate (7) to move back and forth until the residual oil film is ≤0.5μm. Step 6: After the oil scraping is completed, the PLC controller (38) controls the first electric slide rail (17) to start, and the first electric slider (18) drives the wiping sponge (19) to move back and forth along the width of the steel plate to wipe the oil film stuck to the bottom of the alloy scraper (14). After wiping, the conveying roller (2) continues to drive the steel plate to the inkjet marking area. Step 7: When the defective area of ​​the steel plate is transported to the inkjet area, the PLC controller (38) sends a signal to the second electric slide rail (26) according to the defect coordinates transmitted by the industrial high-definition camera (4). The second electric slider (27) moves along the second electric slide rail (26), and at the same time the robotic arm (28) (model IRB120) is started. Through three-axis adjustment, the inkjet head (29) (model KM512LH) is precisely aligned with the defective area, with a positioning accuracy of ±1mm. Step 8: The PLC controller (38) controls the inkjet head (29) to draw special resistant ink through the ink injection tube (30) according to the preset parameters (the line direction required by the customer, such as 45° diagonal line, horizontal or vertical line, or custom graphic), and spray the mark onto the defect area with a line width accuracy of ±0.5mm to meet the customer's standardization requirements. Step 9: While the ink is being printed, the PLC controller (38) sends a signal to the intake fan (36) (model AX12038) and the electric heating rod (37) (model XDM-220). The intake fan (36) draws in outside air, and the electric heating rod (37) heats the air to 80℃±10℃. The hot air enters the annular hot air nozzle (31) through the intake pipe (33) and is evenly blown to the ink-printing area through the annular guide groove (32), with a wind speed of 15m / s. Step 10: The temperature sensor (35) (model PT100) detects the hot air temperature in real time and feeds the data back to the PLC controller (38). The PLC controller (38) fine-tunes the power of the electric heating rod (37) according to the data to ensure that the hot air temperature is stable and that the ink is cured within ≤3 seconds. After drying, the conveying roller (2) drives the steel plate to continue to be conveyed. The marked steel plate is sent out from the output end of the base steel frame (1). The whole process ends. The PLC controller (38) records the defect marking data for easy traceability later.

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