A flatness detection device and method for protective film production

Abstract

This invention discloses a flatness testing device and method for protective film production. The device includes multiple sets of laser displacement sensors opposite to a support ring, and a protective film re-inspection structure including a movable camera. The camera can move to the corresponding position on the support ring based on the measurement results of the laser displacement sensors for re-inspection of that portion of the protective film. The method includes the following steps: S1 protective film winding arrangement, S2 protective film detection, and S3 protective film re-inspection. This invention, through a dual detection method of "pressure displacement detection + visual re-inspection," achieves precise positioning of wrinkles in the width direction, significantly improves detection accuracy, and reduces the false judgment rate. It solves the technical problems of inaccurate positioning, inconvenient installation and maintenance, and low detection accuracy in existing technologies. It can effectively guide production line workers to eliminate wrinkle defects in a timely manner, improve the product qualification rate and production quality of protective films, and has good industrial application value.

Description

Technical Field

[0001] This invention relates to the field of protective film testing technology, and in particular to a flatness testing device and method for protective film production. Background Technology

[0002] In automated production lines for protective film production, slitting, and coating, the flatness of the protective film directly determines the product quality. If wrinkles appear on the surface of the protective film, it will not only affect the stability of subsequent processing steps, but also cause defects such as creases and damage to the finished protective film, reducing the product qualification rate. Therefore, flatness detection during the protective film transportation process is crucial.

[0003] Currently, the industry commonly uses a technical solution to test the flatness of protective films by installing pressure sensors or force sensors under the bearing seats of guide rollers or drive rollers. The core principle of this solution is to take advantage of the characteristic that the local pressure change of the roller body when the wrinkles of the protective film pass through the guide roller. By detecting the pressure fluctuations at the bearing seats at both ends of the roller body, it can be determined whether there is an abnormality in the flatness of the protective film.

[0004] In existing technologies, numerous publicly available solutions employ the aforementioned detection approach. For instance, the PET flatness detection device (CN202422291150.1) discloses a structure with front / rear guide rollers, pressure sensors at both ends of the bearing housing, and a PLC. It uses the localized pressure increase caused by film wrinkles to trigger a sudden change in the sensor signal, thereby determining that the protective film is uneven. Similarly, the optical film detection device (CN202511697853.1) uses a structure with guide rollers and bearing housing force sensors to identify wrinkles and flatness anomalies in the optical film by detecting pressure fluctuations. Furthermore, industry-standard configurations such as the tension detection system for Xiamen Delishi slitting machines, as well as earlier patents such as CN109373964A and CN214747893U, all disclose technology for detecting flatness using roll guide rollers and bearing housing pressure sensors. This type of technology has become an industry standard for detecting wrinkles, uneven tension, and deviation in film and protective film production lines, and is considered common knowledge in the field.

[0005] However, the aforementioned existing technical solutions have many insurmountable defects and cannot meet the requirements for high-precision and convenient flatness detection: First, the existing technologies all use the method of detecting the total pressure of the bearing seats at both ends of the roller body, which can only determine whether there are wrinkles in the protective film, but cannot locate the specific position of the wrinkles in the width direction of the protective film, which is not conducive to subsequent targeted adjustment and elimination of wrinkle defects; Second, some existing technologies attempt to install miniature pressure sensors on the inside of the roller body or ring to achieve local detection, but such solutions require the installation of sensors and wires in a narrow space, which is not only difficult to process and inconvenient to install, but also easily damaged by friction and extrusion between the sensor and the roller body or ring, reducing the service life of the detection system and increasing the later maintenance costs.

[0006] In view of the shortcomings of the existing technology, there is an urgent need for a protective film flatness detection solution that can avoid installing pressure sensors in confined spaces, achieve precise wrinkle positioning, provide stable detection and convenient maintenance, so as to solve the technical problems of inaccurate positioning and inconvenient installation and maintenance in the existing technology, and improve the detection accuracy and production efficiency of the protective film production line. Summary of the Invention

[0007] The purpose of this invention is to solve the above-mentioned technical problems by providing a flatness testing device and method for protective film production.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A flatness testing device for protective film production includes a frame with a guide roller assembly for guiding the protective film. It also includes a test roller rotatably mounted on the frame, with multiple test sections distributed axially at its upper end. Each test section includes a fixed ring fixed to the test roller, a support ring on the outer side of the fixed ring, and a floating cavity formed between the fixed ring and the support ring. An elastic support member fixed to the fixed ring and the support ring is disposed within the floating cavity. When a wrinkled protective film passes through the support ring, the pressure on the support ring increases. It also includes multiple sets of laser displacement sensors opposite to the support ring, used to detect the displacement of the support ring and determine the specific wrinkles in the protective film; It also includes a protective film re-inspection structure, which includes a movable camera that can move to the position of the corresponding support ring based on the measurement results of the laser displacement sensor, for re-inspection of the protective film of that part.

[0009] Preferably, the frame includes a support base, on which two sets of support plates are fixed. The two sets of support plates are vertically arranged on the support base and are arranged in parallel.

[0010] Preferably, the guide roller group includes a first guide roller, a second guide roller, and a third guide roller. The first guide roller, the second guide roller, the third guide roller, and the detection roller are arranged in a diamond shape. The first guide roller, the second guide roller, the third guide roller, and the detection roller are all rotatably mounted on the support plate via bearings. The protective film is sequentially wound around the first guide roller, the detection roller, the third guide roller, and the second guide roller. The protective film is finally led out through the second guide roller and can be wound up by a take-up roller or subjected to subsequent processing.

[0011] Preferably, it also includes a support plate, and both ends of the support plate are fixed with a plurality of first mounting posts, which are detachably mounted on the support plate.

[0012] Preferably, the protective film re-inspection structure further includes a re-inspection box located between two support plates and an alarm light at its upper end. A drive box is installed at the upper end of the re-inspection box, and a drive mechanism for moving the camera is installed on the drive box.

[0013] Preferably, the driving mechanism includes a motor mounted on a driving box, a ball screw fixed at the output end of the motor, the other end of the ball screw being rotatably connected to the inner wall of the driving box, a guide rail fixed inside the driving box, a slider slidably mounted on the guide rail, the ball screw passing through the slider and threadedly connected to it, a mounting block fixed at the bottom of the slider, and the camera fixed at the bottom of the mounting block.

[0014] Preferably, the drive box is arranged in a rectangular frame shape, and two baffles are fixed at both ends of the drive box. The four baffles and the drive box enclose a detection dark chamber. A gap is formed between the two baffles at the same end, and the protective film moves through the gap.

[0015] Preferably, both ends of the re-inspection box are fixed with second mounting posts, and multiple second mounting posts are fixed on the support plate.

[0016] Preferably, the inner wall of the re-inspection box is fixed with multiple light strips, which are arranged opposite to the protective film through which the light strips pass.

[0017] This invention also discloses a method for detecting the flatness of protective film during production, which specifically includes the following steps: S1, Protective film winding arrangement: The protective film is wound around the guide roller group and the detection roller; S2, Protective film detection: When a wrinkled protective film passes through the detection section, it causes a change in the pressure of the detection section opposite to the wrinkled part, causing the support ring of that part to shift. The specific location of the detection section can be measured by a laser displacement sensor. S3, Protective film re-inspection: The laser displacement sensor transmits a signal to the camera, the motor drives the ball screw to rotate, and moves the slider and camera to a position relative to the pressure change detection part. The camera re-inspects this part. If there are wrinkles, the alarm light will sound; if there are no wrinkles, the alarm light will not work.

[0018] Compared with the prior art, the beneficial effects of this invention are as follows: 1. Overcoming the shortcomings of existing technologies that only detect the total pressure at both ends of the roller and cannot determine the specific location of wrinkles, this technology sets up multiple independent detection units along the axial direction of the detection roller and equips them with corresponding laser displacement sensors. This allows for precise capture of the displacement change of the support ring at any position in the width direction of the protective film, directly locating the specific area of ​​the wrinkle in the width direction. This facilitates targeted adjustments to production equipment and rapid elimination of wrinkle defects.

[0019] 2. An automated closed-loop detection method of "pressure displacement initial inspection + visual high-definition re-inspection" is adopted. The laser displacement sensor realizes the initial detection and positioning of wrinkles, and the camera then moves to the suspected position for high-definition visual re-inspection. Combined with the assistance of the detection darkroom and dedicated light source, it effectively avoids misjudgment caused by factors such as equipment vibration and impurities on the surface of the protective film, and the accuracy of the detection results is greatly improved.

[0020] 3. By avoiding the design of installing miniature pressure sensors in confined spaces in existing technologies, the elastic support is set in the floating cavity of the detection unit, and the laser displacement sensor is externally mounted on the support plate. There is no need to arrange sensors and wires in confined spaces, which significantly reduces the difficulty of processing and assembly. At the same time, the detection unit has a modular structure, and vulnerable parts such as support rings and elastic support can be replaced individually. The cleaning and calibration of components such as laser displacement sensors and cameras are convenient, resulting in low maintenance costs and high efficiency in the later stage.

[0021] 4. The testing equipment is seamlessly integrated with the production line. After the protective film is wrapped, it can be tested as it is transported normally along the production line. The testing roller rolls synchronously with the protective film. The entire testing process does not require stopping production, and the testing frequency can be flexibly adjusted according to the production line transmission speed, realizing automated online real-time testing and effectively improving the overall testing efficiency of protective film production.

[0022] 5. The support ring of the detection section is made of wear-resistant plastic material, and the guide roller group is made of hard rubber roller body with polished roller surface. The detection roller and the protective film are in rolling contact, which greatly reduces the risk of friction and scratches on the surface of the protective film during the detection process. At the same time, the guide roller group is diamond-shaped, which ensures full contact between the protective film and the detection section, while effectively avoiding deviation and uneven tension during the transmission process, thus balancing the effectiveness of detection and the integrity of the product.

[0023] 6. With precise wrinkle positioning and high-accuracy detection results, it can guide staff to eliminate wrinkle defects in production in a timely manner, effectively reduce the scrap of finished protective films due to creases and damage, and significantly improve the product qualification rate and production quality of protective films; at the same time, the testing equipment is stable in operation and easy to maintain, and is suitable for industrial continuous production, providing a guarantee for the efficient and high-quality operation of the protective film production line, and has high practical industrial application value.

[0024] In summary, this invention, through a dual detection method of "pressure displacement detection + visual re-inspection," not only achieves precise positioning of the wrinkle location in the width direction but also significantly improves detection accuracy and reduces the false judgment rate. It solves the technical problems of inaccurate positioning, inconvenient installation and maintenance, and low detection accuracy in existing technologies. It can effectively guide production line workers to eliminate wrinkle defects in a timely manner, improve the product qualification rate and production quality of protective films, and has good industrial application value. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the flatness testing equipment for protective film production proposed in this invention; Figure 2 This is a schematic diagram of the guide roller group and the detection roller in a flatness testing device for protective film production proposed in this invention. Figure 3 This is a schematic diagram of the protective film arrangement in a flatness testing device for protective film production proposed in this invention; Figure 4 This is a schematic diagram of the structure between two support plates in a flatness testing device for protective film production proposed in this invention; Figure 5 This is a side view of the structure of the detection unit in a flatness detection device for protective film production proposed in this invention; Figure 6 This is a schematic diagram of the re-inspection box in a flatness testing device for protective film production proposed in this invention; Figure 7 This is a schematic diagram of the structure of the light strip in the flatness testing equipment for protective film production proposed in this invention; Figure 8 This is a schematic diagram of the guide rail structure in a flatness testing device for protective film production proposed in this invention; Figure 9 This is a schematic diagram of the ball screw structure in a flatness testing device for protective film production proposed in this invention; Figure 10 This is a flowchart illustrating the steps of a flatness testing method for protective film production proposed in this invention.

[0026] In the diagram: 1 Support base, 2 Support plate, 3 First guide roller, 4 Second guide roller, 5 Detection roller, 6 Third guide roller, 7 Protective film, 8 Bearing plate, 9 Laser displacement sensor, 10 Re-inspection box, 11 Drive box, 12 Detection section, 13 First mounting post, 14 Second mounting post, 15 Motor, 16 Baffle, 17 Gap, 18 Light strip, 19 Slider, 20 Guide rail, 21 Ball screw, 22 Mounting block, 23 Camera, 24 Fixing ring, 25 Support ring, 26 Floating cavity, 27 Elastic support component. Detailed Implementation

[0027] 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.

[0028] Reference Figures 1-9 A flatness testing device for protective film production includes a frame, which serves as the load-bearing foundation for the entire testing device. The frame includes a support base 1 and two sets of support plates 2. The support base 1 adopts an integrated metal casting structure, using high-strength aluminum alloy material, combining structural stability and lightweight advantages to prevent vibration from affecting the testing accuracy during operation. The two sets of support plates 2 are rectangular metal plates, vertically fixed to the upper surface of the support base 1 by welding, and the two sets of support plates 2 are strictly parallel. The inner end faces of the support plates 2 are precision milled to ensure that the flatness error does not exceed 0.02mm, providing a precise assembly benchmark for the subsequent rotation and installation of the guide roller group and the testing roller 5. Multiple uniform mounting holes and positioning grooves are pre-drilled on the support plates 2 to facilitate the detachable assembly of subsequent components such as the bearing plate 8 and the re-inspection box 10.

[0029] The guide roller assembly is used to guide and transport the protective film 7. It includes a first guide roller 3, a second guide roller 4, and a third guide roller 6. All three guide rollers are made of hard rubber and have polished surfaces to avoid scratching the surface of the protective film 7. High-precision deep groove ball bearings are installed at both ends of the rollers. The first guide roller 3, the second guide roller 4, and the third guide roller 6 are arranged in a diamond shape with the detection roller 5 and are all rotatably mounted in the preset mounting holes between the two sets of support plates 2 via bearings. The bearings and support plates 2 are interference-fitted to ensure coaxiality during the rotation of the rollers.

[0030] After assembly, the levelness of the four rollers needs to be adjusted to ensure that the roller axes are on the same horizontal plane with a deviation of no more than 0.03mm, thus preventing the protective film 7 from deviating or experiencing uneven tension during transmission. The winding path of the protective film 7 on the guide roller group is as follows: it is sequentially wound around the lower side of the first guide roller 3, the upper side of the detection roller 5, the lower side of the third guide roller 6, and the upper side of the second guide roller 4, and finally led out through the second guide roller 4 to connect with the take-up roller of the production line or subsequent processing equipment. The diamond-shaped winding structure ensures that the protective film 7 makes full contact with the detection part 12 of the detection roller 5, ensuring the effectiveness of the detection.

[0031] The detection roller 5 adopts a metal roller shaft structure and is rotatably mounted between two sets of support plates 2, located at the center of the rhomboid structure formed by the guide roller group. Multiple detection sections 12 are equidistantly sleeved on the upper end of the detection roller 5 along the axial direction. The number of detection sections 12 can be adjusted according to the width of the protective film 7. The spacing between two adjacent detection sections 12 is 0.5-1mm, with no blind spots, ensuring full coverage detection of the protective film 7 in the width direction, and ensuring that adjacent detection sections 12 do not interfere with each other.

[0032] Each detection unit 12 consists of a fixed ring 24, a support ring 25, and an elastic support 27. The fixed ring 24 is fixed to the surface of the detection roller 5 with a set screw and rotates synchronously with the detection roller 5. The support ring 25 is coaxially arranged on the outer side of the fixed ring 24. The support ring 25 is made of wear-resistant plastic to avoid scratches when in contact with the protective film 7. An annular floating cavity 26 is formed between the fixed ring 24 and the support ring 25. The gap of the floating cavity 26 is 0.5-1mm to ensure that the support ring 25 can make slight radial floating.

[0033] Multiple elastic support members 27 are evenly arranged inside the floating cavity 26. In this embodiment, the elastic support members 27 are stainless steel compression springs or metal spring sheets. The two ends of the compression springs or metal spring sheets are fixedly connected to the outer side wall of the fixed ring 24 and the inner side wall of the support ring 25 by welding, respectively.

[0034] The elastic coefficient of the elastic support 27 is precisely calibrated. When wrinkles appear on the surface of the protective film 7, the increased thickness at the wrinkles will exert downward pressure on the support ring 25, causing the elastic support 27 to compress and the support ring 25 to make a slight displacement. After the pressure disappears, the elastic support 27 can drive the support ring 25 to quickly reset, ensuring the real-time nature of the detection.

[0035] The laser displacement detection assembly includes a support plate 8 and multiple sets of laser displacement sensors 9. The support plate 8 is a long strip of metal plate, with multiple first mounting posts 13 fixed at both ends. The first mounting posts 13 match the preset mounting holes on the support plate 2. The support plate 8 is detachably mounted on the support plate 2 using bolts. The installation height of the support plate 8 can be adjusted according to the position of the detection roller 5. Multiple sets of laser displacement sensors 9 are installed at equal intervals on the lower end face of the support plate 8 via brackets. The number of laser displacement sensors 9 is the same as the number of detection units 12, and the detection end of each laser displacement sensor 9 is radially aligned with the upper end face of the corresponding support ring 25. The detection accuracy of the laser displacement sensors 9 is adjusted to 0.01mm, enabling precise capture of minute displacements of the support ring 25. The laser displacement sensors 9 are electrically connected to the control system of the subsequent re-inspection structure via data cables, allowing the detected displacement signals to be transmitted to the control system in real time.

[0036] The protective film re-inspection structure is used to perform secondary visual re-inspection of suspected wrinkle positions detected by the laser displacement sensor 9. It includes components such as re-inspection box 10, drive box 11, drive mechanism, camera 23, alarm light, and light strip 18. The whole structure is installed between two sets of support plates 2, located behind the detection roller 5, corresponding to the transmission path of the protective film 7.

[0037] The re-inspection box 10 has a rectangular hollow box structure, with multiple second mounting posts 14 fixed at both its front and rear ends. The second mounting posts 14 are fixed to the pre-set mounting holes in the support plate 2 by bolts, thus achieving the fixed assembly of the re-inspection box 10. Multiple light strips 18 are symmetrically fixed on both sides of the inner wall of the re-inspection box 10. The light strips 18 are high-brightness LED cold light sources, and the illumination direction of the light strips 18 is set perpendicular to the transmission surface of the protective film 7, providing sufficient and uniform light source for visual re-inspection and avoiding re-inspection errors caused by insufficient light or uneven illumination.

[0038] The upper end of the re-inspection box 10 is fixedly mounted with the drive box 11 by bolts. An alarm light is installed on the upper end of the drive box 11. The alarm light is electrically connected to the control system. When a wrinkle is detected in the protective film 7, the alarm light emits a red flashing alarm. When there is no wrinkle, it remains in a normally off state.

[0039] The drive box 11 is rectangular in shape and houses a drive mechanism. This mechanism moves the camera 23 along the width of the protective film 7 for precise positioning and re-inspection. The drive mechanism includes a motor 15, a ball screw 21, a guide rail 20, a slider 19, and a mounting block 22. The motor 15 is a servo motor, offering advantages such as adjustable speed and precise positioning. It is mounted on the outer wall of one end of the drive box 11 via a bracket. The output end of the motor 15 passes through the side wall of the drive box 11 and is fixedly connected to one end of the ball screw 21. The other end of the ball screw 21 is rotatably connected to the inner wall of the other end of the drive box 11 via a bearing. The guide rail 20 is fixed to the inner top of the drive box 11, and the slider 19 is slidably mounted on the guide rail 20. The ball screw 21 passes through the slider 19 and is threadedly connected to it, ensuring the stability of the slider 19 during movement. The bottom of the slider 19 is fixed to the mounting block 22 by screws, and the camera 23 is fixed to the bottom of the mounting block 22 by bolts. The camera 23 is an industrial high-definition camera with a pixel of no less than 20 million, which can clearly capture the fine wrinkles on the surface of the protective film 7.

[0040] Two baffles 16 are fixed at both ends of the drive box 11. All four baffles 16 are light-shielding plates, forming a closed detection dark chamber with the drive box 11 to prevent external light from entering and affecting the shooting effect of the camera 23. A gap 17 is formed between the two baffles 16 at the same end. The width of the gap 17 is slightly larger than the thickness of the protective film 7. After the protective film 7 is transferred from the detection roller 5, it passes through the gap 17 and moves in the detection dark chamber inside the re-inspection box 10, ensuring that the camera 23 can clearly capture images of the suspected wrinkles on the protective film 7.

[0041] In addition, all electrical components of the entire testing equipment, including the laser displacement sensor 9, motor 15, camera 23, alarm light, and light strip 18, are electrically connected to the overall control system of the production line to realize automated control of the testing process. The testing frequency and camera shooting parameters can be adjusted according to the transmission speed of the production line to ensure that testing and production are synchronized.

[0042] The protective film flatness detection method of the present invention is based on the above-mentioned detection equipment. The core working principle is as follows: taking advantage of the increased thickness of the protective film 7 at the folds, which causes a change in the pressure on the corresponding support ring 25 on the detection roller 5 and thus generates radial displacement, the laser displacement sensor 9 captures the displacement signal to achieve precise positioning of the fold position; then the control system drives the camera 23 to move to the position for visual re-inspection, and an alarm is issued after confirming the fold defect. The whole process realizes an automated closed loop of "pressure displacement detection - precise positioning - visual re-inspection - defect alarm", which effectively solves the problems of inability to locate the fold position, low detection accuracy, and easy misjudgment in the prior art.

[0043] The testing method specifically includes the following steps, each of which is performed synchronously with the protective film transfer process on the production line, without requiring production to be interrupted, thus achieving online real-time testing: S1: The protective film 7 is wound and arranged before the testing equipment is started. The protective film 7 is wound onto the guide rollers and the testing roller 5. The free end of the protective film 7 to be tested in the production line is sequentially pulled and wound around the lower side of the first guide roller 3, the upper side of the testing roller 5, the lower side of the third guide roller 6, and the upper side of the second guide roller 4, ensuring that the protective film 7 is in full contact with all the support rings 25 on the testing roller 5, and that the protective film 7 is taut without any slack or sagging. Then, the free end of the protective film 7 is passed through the gaps 17 at both ends of the re-inspection box 10 and connected to the take-up roller of the production line or subsequent processing equipment. After the winding is completed, the transmission speed of the production line is adjusted to ensure that the protective film 7 is transmitted on the testing equipment at a stable speed. In this embodiment, the transmission speed of the protective film 7 is controlled at 5-20 m / min, which can be adjusted according to actual production needs.

[0044] Simultaneously, all electrical components of the testing equipment are activated, and the laser displacement sensor 9, camera 23, motor 15, etc., are preheated and calibrated: the detection zero point of the laser displacement sensor 9 is calibrated to the upper end face position of the support ring 25 when there is no pressure; the focal length of the camera 23 is adjusted so that the camera can clearly capture the surface details of the protective film 7; the rotation parameters of the servo motor 15 are adjusted to ensure that the slider 19 can drive the camera 23 to move accurately to the corresponding position of each detection part 12, with a positioning error of no more than 0.5cm; the light strip 18 in the re-inspection box 10 is turned on, the light source brightness is adjusted to a suitable value, and external stray light is turned off to ensure the light-blocking effect of the detection darkroom. After all components are calibrated, the system enters the ready-to-test state.

[0045] S2: Protective film 7 is inspected. The production line is started. The protective film 7 is continuously transported along the guide roller group and the inspection roller 5 at a set speed. The inspection roller 5 rotates synchronously under the friction of the protective film 7. The support ring 25 of the inspection section 12 keeps in synchronous contact with the protective film 7.

[0046] When the protective film 7 is wrinkle-free, the protective film 7 is in a tensioned state, the elastic support 27 is in a pre-compressed state, the protective film 7 has a uniform thickness, and the pressure on each support ring 25 is consistent. Although the support ring 25 has a slight displacement, the displacement remains constant. The displacement signal detected by the laser displacement sensor 9 remains stable and is transmitted to the control system. The control system determines that the flatness of the protective film 7 at this position is qualified.

[0047] When wrinkles appear on the surface of the protective film 7, the thickness of the wrinkled area increases significantly compared to the normal area. During transmission, the wrinkled area exerts additional downward pressure on the corresponding support ring 25. This pressure compresses the elastic support 27 within the floating cavity 26, causing the support ring 25 to move closer to the fixed ring 24, resulting in a significant increase in displacement. Since each laser displacement sensor 9 precisely corresponds to its support ring 25, it can capture the displacement changes of the support ring 25 in real time and convert the displacement signal into an electrical signal for rapid transmission to the control system. The control system makes a judgment based on a preset displacement threshold. When the displacement value exceeds the threshold, the location is determined to be a suspected wrinkled area. Simultaneously, based on the number of the laser displacement sensor 9, the specific location of the suspected wrinkled area in the width direction of the protective film 7 is accurately determined, completing the initial detection and positioning of the wrinkles.

[0048] In this step, the elastic coefficient of the elastic support 27 and the detection threshold of the laser displacement sensor 9 have been calibrated through multiple tests. These can be flexibly adjusted for protective films 7 of different thicknesses and materials. For example, for a 0.05mm thick PET protective film, the displacement threshold of the laser displacement sensor 9 is set to 0.02mm, which can accurately detect minute wrinkles while avoiding misjudgments caused by slight tension fluctuations in the protective film 7. Simultaneously, the synchronous rotation of the detection roller 5 ensures rolling contact between the support ring 25 and the protective film 7, significantly reducing friction between them. This avoids scratching the protective film 7 and reduces wear on the support ring 25, thus extending the service life of the detection components.

[0049] S3: Re-inspection of protective film 7. This step is a second visual re-inspection of the suspected wrinkled areas detected in the initial inspection. It avoids misjudgment caused by factors such as equipment vibration and impurities on the surface of protective film 7, and improves the accuracy of the test results. The entire re-inspection process is automatically controlled by the control system and does not require manual intervention.

[0050] When the control system receives a suspected wrinkle displacement signal transmitted by the laser displacement sensor 9, it immediately sends a drive command to the servo motor 15 based on the position information corresponding to the signal. After receiving the command, the motor 15 drives the ball screw 21 to rotate at a preset speed. Since the ball screw 21 and the slider 19 are threadedly connected, and the slider 19 is limited by the guide rail 20, the rotational motion of the ball screw 21 is converted into the linear motion of the slider 19 along the guide rail 20, which drives the camera 23 at the bottom of the mounting block 22 to move quickly to directly above the suspected wrinkle area, achieving precise positioning.

[0051] After camera 23 moves to the designated position, it immediately takes a high-definition picture of the area of ​​the protective film 7, and the captured image information is transmitted to the control system in real time. The control system quickly analyzes and processes the image, comparing the surface texture and flatness of the normal area of ​​the protective film 7 with the captured area. If it confirms that there is a wrinkle defect in the area, it sends a command to the alarm light, causing the alarm light to flash red, reminding the production line staff to adjust the production equipment in time, such as adjusting the tension of the protective film, correcting transmission deviation, etc., to eliminate the wrinkle defect. If the analysis finds that there is no wrinkle in the area, and the misjudgment is caused by factors such as equipment vibration or surface impurities, the control system does not issue an alarm command, the alarm light remains off, and the protective film 7 continues to be transmitted normally.

[0052] After completing one re-inspection, camera 23 quickly resets to its initial position under the drive of motor 15. If it receives a signal from the next laser displacement sensor 9, it moves directly to the corresponding suspected wrinkle location, achieving continuous re-inspection. Simultaneously, the LED light strip 18 inside the re-inspection box 10 provides camera 23 with a uniform and sufficient light source. The light-shielding design of the darkroom avoids interference from external light, ensuring the clarity of the captured images and providing a reliable basis for image analysis of the control system, further reducing the false judgment rate.

[0053] If the production line staff receives an alarm and adjusts the production equipment, after the wrinkle defect is eliminated, the pressure of the protective film 7 on the support ring 25 returns to normal, the elastic support 27 drives the support ring 25 to reset, the displacement signal detected by the laser displacement sensor 9 returns to stability, the control system determines that the test is qualified, the alarm light stops alarming, and the testing equipment resumes normal continuous testing.

[0054] When testing protective films 7 of different widths and materials, it is necessary to adjust the number and spacing of the testing units 12, recalibrate the detection threshold of the laser displacement sensor 9 and the elastic coefficient of the elastic support 27, and adjust the movement stroke of the camera 23 to ensure that the testing equipment matches the protective film 7 to be tested.

[0055] The testing equipment and method of this invention adopts a modular design, which is convenient for assembly and maintenance. The testing process is automated and online, requiring no manual intervention, thus effectively improving the testing efficiency of protective film production. At the same time, through the dual detection method of "pressure displacement detection + visual re-inspection", it not only achieves accurate positioning of wrinkle positions in the width direction, but also greatly improves detection accuracy and reduces the false judgment rate. It solves the technical problems of inaccurate positioning, inconvenient installation and maintenance, and low detection accuracy in the prior art. It can effectively guide production line workers to eliminate wrinkle defects in a timely manner, improve the product qualification rate and production quality of protective films, and has good industrial application value.

[0056] 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. A flatness testing device for protective film production, comprising a frame, wherein a set of guide rollers for guiding a protective film (7) is provided on the frame, characterized in that, It also includes a detection roller (5) that is rotatably mounted on the frame, with a plurality of detection parts (12) distributed along the axial direction on its upper end. The detection part (12) includes a fixed ring (24) fixed on the detection roller (5), a support ring (25) on the outside of the fixed ring (24), and a floating cavity (26) is formed between the fixed ring (24) and the support ring (25). An elastic support member (27) fixed to the fixed ring (24) and the support ring (25) is provided in the floating cavity (26). When the wrinkled protective film (7) passes through the support ring (25), it will cause the pressure on the support ring (25) to increase. It also includes multiple sets of laser displacement sensors (9) opposite to the support ring (25) for detecting the displacement of the support ring (25) and determining the specific folds of the protective film (7); It also includes a protective film re-inspection structure, which includes a movable camera (23) that can move to the position of the corresponding support ring (25) according to the measurement results of the laser displacement sensor (9) for re-inspecting the protective film (7) of that part.

2. The flatness testing equipment for protective film production according to claim 1, characterized in that, The frame includes a support base (1), on which two sets of support plates (2) are fixed. The two sets of support plates (2) are vertically arranged on the support base (1) and parallel to each other.

3. The flatness testing equipment for protective film production according to claim 1, characterized in that, The guide roller group includes a first guide roller (3), a second guide roller (4), and a third guide roller (6). The first guide roller (3), the second guide roller (4), the third guide roller (6), and the detection roller (5) are arranged in a rhomboid shape. The protective film (7) is sequentially wound around the first guide roller (3), the detection roller (5), the third guide roller (6), and the second guide roller (4).

4. The flatness testing equipment for protective film production according to claim 2, characterized in that, It also includes a support plate (8), both ends of which are fixed with a plurality of first mounting posts (13), which are detachably mounted on the support plate (2).

5. The flatness testing equipment for protective film production according to claim 2, characterized in that, The protective film re-inspection structure also includes a re-inspection box (10) located between two support plates (2) and an alarm light at its upper end. A drive box (11) is installed at the upper end of the re-inspection box (10), and a drive mechanism for moving the camera (23) is installed on the drive box (11).

6. The flatness testing equipment for protective film production according to claim 5, characterized in that, The driving mechanism includes a motor (15) mounted on a drive box (11). A ball screw (21) is fixed to the output end of the motor (15). The other end of the ball screw (21) is rotatably connected to the inner wall of the drive box (11). A guide rail (20) is fixed inside the drive box (11). A slider (19) is slidably mounted on the guide rail (20). The ball screw (21) passes through the slider (19) and is threadedly connected to it. A mounting block (22) is fixed to the bottom of the slider (19). The camera (23) is fixed to the bottom of the mounting block (22).

7. The flatness testing equipment for protective film production according to claim 5, characterized in that, The drive box (11) is arranged in a rectangular frame shape. Two baffles (16) are fixed at both ends of the drive box (11). The four baffles (16) and the drive box (11) enclose a detection dark chamber. A gap (17) is formed between the two baffles (16) at the same end, through which the protective film (7) moves.

8. The flatness testing equipment for protective film production according to claim 5, characterized in that, The re-inspection box (10) is fixed with a second mounting post (14) at both ends, and multiple second mounting posts (14) are fixed on the support plate (2).

9. The flatness testing equipment for protective film production according to claim 5, characterized in that, The inner wall of the re-inspection box (10) is fixed with multiple light strips (18), which are arranged opposite to the protective film (7) that passes through.

10. A method for detecting the flatness of protective film during production, characterized in that, Applied to the detection device according to any one of claims 1-9, the method specifically includes the following steps: S1, Protective film (7) winding arrangement: The protective film (7) is wound around the guide roller group and the detection roller (5); S2, Protective film (7) detection: When the wrinkled protective film (7) passes through the detection part (12), the pressure of the detection part (12) opposite to the wrinkled part will change, causing the support ring (25) of that part to be displaced. The specific position of the displaced detection part (9) can be measured by the laser displacement sensor (9), and the wrinkle will be initially located. S3, Protective film (7) re-inspection: Laser displacement sensor (9) transmits signal to camera (23), motor (15) drives ball screw (21) to rotate, driving slider (19) and camera (23) to move to the position opposite to pressure change detection part (12), and the part is re-inspected by camera (23). If there are wrinkles, the alarm light will sound an alarm. If there are no wrinkles, the alarm light will not work.

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