A film surface flaw on-line detection device for a film blowing production line and a working method thereof

Abstract

The present application relates to a kind of film surface flaw online detection device for blown film production line and its working method, including first detection mechanism and second detection mechanism, and film is transported between first detection mechanism and second detection mechanism;First detection mechanism is moved in cycle by chain driven adsorption seat, and the opening and closing of adsorption seat are controlled using the pressing section and separation section of annular guide base, realize the transverse stretching of film;Second detection mechanism realizes the longitudinal stretching of film by the speed difference between conveying roller and adsorption seat;The present application makes film surface flat and spread by bidirectional stretching, cooperates double-side light compensation and double scanning camera, realizes the comprehensive, accurate online detection of film surface flaw, effectively solves the problem of detection blind area caused by film wrinkle, curl.

Description

Technical Field

[0001] This invention relates to the field of thin film production inspection technology, and in particular to an online detection device for surface defects of thin films used in blown film production lines and its working method. Background Technology

[0002] During the blown film production process, various defects may appear on the film surface, such as black spots, crystal points, fisheyes, scratches, bubbles, and pinholes. These defects seriously affect the quality and performance of the film. Therefore, online defect detection on the film production line is a crucial step in ensuring product quality. Existing film surface defect detection devices mainly suffer from the following technical shortcomings: Difficulty in flattening the film: The film produced by blown film production is soft and wrinkle-prone, making it difficult to maintain a flat and unfolded state during transportation, resulting in blind spots in inspection and making it easy to miss defects; Limitations of unidirectional inspection: Traditional inspection devices typically only photograph and inspect the film from one side, and cannot simultaneously detect defects on the upper and lower surfaces of the film, resulting in blind spots in the inspection. Insufficient stretching: The existing film flattening mechanism of the detection device has limited stretching effect on the film, especially insufficient lateral stretching. Micro wrinkles still exist on the film surface, affecting the detection accuracy. Low detection rate of minute defects: For minute signals such as tiny cracks and pinholes, it is difficult to clearly image them under normal lighting conditions, resulting in a low detection rate. Summary of the Invention

[0003] The present invention addresses the problem of providing an online detection device for film surface defects in a blown film production line and its working method. By bidirectional stretching to flatten and unfold the film surface, and with the assistance of double-sided illumination and dual scanning cameras, comprehensive and accurate online detection of film surface defects can be achieved, effectively solving the problem of blind spots caused by film wrinkles and curling.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: An online detection device for film surface defects in a blown film production line includes a first detection mechanism and a second detection mechanism, wherein the film is conveyed between the first detection mechanism and the second detection mechanism. The first detection mechanism includes a frame, and chain teeth are installed at both ends of the frame. The chain teeth on the same side of the frame are connected by chain drive. Several chain plates are installed at equal intervals between the two chains through mounting seats. Slide rails are symmetrically arranged on the chain plates, and adsorption seats are slidably installed at both ends of the slide rails. The two adsorption seats are elastically connected. A lamp groove is opened in the middle of the adsorption seat, and a first supplementary light is installed in the lamp groove. Several adsorption holes are opened at the outer end of the adsorption seat and on both sides of the lamp groove. A mounting frame is installed on the frame, and a first scanning camera is installed on the mounting frame. The second detection mechanism includes symmetrically arranged uprights, on which conveying rollers and pressure rollers are installed. A first support frame and a second support frame are installed on the uprights. A second scanning camera is installed on the first support frame, and a lamp holder is installed on the second support frame, with a second supplementary light installed inside the lamp holder.

[0005] Preferably, a transmission box is installed on the frame, and the output end of the transmission box is connected to the chain teeth, and the input end of the transmission box is connected to the output end of the power motor.

[0006] Preferably, annular guide seats are symmetrically installed on the outer side of the frame, and the annular guide seats include a pressing section and a separating section with a V-shaped groove. Several spring grooves are provided at the opposite ends of the two adsorption seats, and springs are installed in the spring grooves. A ball bearing seat is installed at the outer end of the adsorption seat, and a ball bearing is installed in the ball bearing seat. The ball bearing rolls along the inner wall of the annular guide seat.

[0007] Preferably, a rotating shaft is rotatably mounted through the middle of the frame, and an electric slip ring and a rotary joint are respectively installed at both ends of the rotating shaft. The first supplementary light is connected to the electric slip ring through a wire. An air groove communicating with the rotary joint is opened inside the rotating shaft, and the air groove is connected to the adsorption hole of the adsorption seat through a connecting hose. The rotating shaft passes through the input end of the gear transmission box mounted on the outside of the frame, and the output end of the gear transmission box is connected to the first motor.

[0008] Preferably, a speed reducer is installed on the upright frame, the input end of the speed reducer is connected to the output end of the second motor, and the output end of the speed reducer is connected to the conveyor roller.

[0009] Preferably, the upright frame is provided with a sliding groove, and a pneumatic cylinder is installed on the top of the upright frame. The telescopic end of the pneumatic cylinder is connected to the lifting roller seat in the sliding groove, and the lifting roller seat is connected to the end of the pressure roller.

[0010] Preferably, both the first scanning camera and the second scanning camera are linear scan cameras, and the scanning direction is toward the thin film above the first and second supplementary lights. The first scanning camera is located above the thin film, and the second scanning camera is located below the thin film.

[0011] Preferably, the adsorption holes on the adsorption seat are arranged in a matrix, with a hole diameter of 0.5-2 mm and a hole spacing of 5-10 mm.

[0012] An online detection device for surface defects of blown film in a blown film production line and its working method are disclosed. The specific operating steps of the working method are as follows: Step 1: The power motor drives the chain teeth to rotate through the transmission box. The chain teeth drive the chain to rotate. The chain drives the chain plate and the adsorption seat to move in a cycle through the mounting base, carrying the film forward. At this time, the first motor works, and the gear transmission box drives the rotating shaft to rotate. The wires and connecting hoses connected to the adsorption seat rotate synchronously to avoid the wires and connecting hoses from getting tangled. The upper surface of the adsorption seat contacts the film. Its adsorption holes are connected to an external vacuum source through a rotary joint, an internal air groove in the rotating shaft, and a hose to generate negative pressure to adsorb and fix the film. As the adsorption seat moves with the chain plate, the balls at its outer end always roll along the inner wall of the fixed annular guide seat to adjust the distance between the two adsorption seats. In the pressing section of the guide seat, the two adsorption seats overcome the elastic force of the spring and are in a close-to-each-other state to facilitate film coverage. When the adsorption seat enters the separating section of the guide seat, as the V-shaped groove widens, the spring is released, pushing the two adsorption seats to slide to both sides on the slide rail, realizing the lateral stretching of the film. During the lateral stretching process, the first scanning camera located on the mounting frame performs the first scan of the film surface, and the first supplementary light on the adsorption seat provides illumination. Step 2: After the transversely stretched film leaves the first inspection mechanism, it enters the area between the conveyor roller and the pressure roller of the second inspection mechanism. The linear speed of the conveyor roller driven by the second motor is greater than the conveying speed of the chain plate of the first inspection mechanism. The speed difference applies a forward pulling force to the film, thereby generating longitudinal stretching. After longitudinal stretching, the film passes under the second scanning camera with higher flatness and tension. The second supplementary light in the lamp holder provides supplementary light to detect micro-cracks and pinhole defects that are more easily exposed under longitudinal stress.

[0013] The beneficial effects of this invention are: As the adsorption seat moves with the chain plate, the balls roll along the inner wall of the annular guide seat. In the pressing section, the two adsorption seats overcome the spring force and move closer to each other to facilitate film coverage. In the separation section, the V-shaped groove gradually widens, the spring is released and pushes the two adsorption seats to slide to both sides, applying lateral tension to the film and achieving lateral stretching of the film. This allows the film to be fully laterally unfolded before testing, completely eliminating longitudinal wrinkles and improving lateral flatness. The linear speed of the conveyor roller driven by the second motor is greater than the conveying speed of the chain plate of the first detection mechanism. The speed difference applies a forward pulling force to the film, generating longitudinal stretching. The longitudinal stretching keeps the film under constant tension during the detection process, further eliminating transverse wrinkles and curling. The synergistic effect of transverse and longitudinal stretching creates bidirectional prestress within the film plane, enabling the film surface to reach a fully unfolded state. Compared to unidirectional stretching, bidirectional stretching can expand the film area, improve the uniformity of surface tension, and effectively expose minor imperfections that are not easily visible under natural conditions. The first scanning camera of the first inspection agency performs a top-side scan of the film from above, while the second scanning camera of the second inspection agency performs a second scan of the film after longitudinal stretching from above. With the help of dual supplementary lighting, comprehensive inspection of defects on the upper and lower surfaces and inside of the film can be achieved. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure of the first detection mechanism of the present invention; Figure 3 This is a schematic diagram of the first mounting structure of the adsorption seat of the present invention; Figure 4 This is a schematic diagram of the second mounting structure of the adsorption seat of the present invention; Figure 5 This is a schematic diagram of the first structure of the second detection mechanism of the present invention; Figure 6 This is a schematic diagram of the second structure of the second detection mechanism of the present invention.

[0015] Legend: 1. First inspection mechanism; 2. Second inspection mechanism; 3. Frame; 4. Chain teeth; 5. Chain; 6. Mounting base; 7. Chain plate; 8. Slide rail; 9. Adsorption seat; 10. Adsorption hole; 11. Lamp trough; 12. First supplementary light; 13. Annular guide seat; 14. Pressing section; 15. Separation section; 16. Spring groove; 17. Spring; 18. Ball bearing seat; 19. Ball bearing; 20. Rotating shaft; 21. Electric slip ring; 22. Rotary joint; 23. Gear transmission box; 24. First motor; 25. Mounting frame; 26. First scanning camera; 27. Stand; 28. Conveyor roller; 29. ​​Slide chute; 30. Lifting roller seat; 31. Pressure roller; 32. Reducer; 33. Second motor; 34. Pneumatic cylinder; 35. First support frame; 36. Second scanning camera; 37. Second support frame; 38. Lamp holder; 39. Second supplementary light. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Specific implementation examples are given below.

[0018] See Figures 1-6An online detection device for film surface defects in a blown film production line includes a first detection mechanism 1 and a second detection mechanism 2. The film is conveyed between the first detection mechanism 1 and the second detection mechanism 2. The first detection mechanism 1 is responsible for the transverse stretching and top surface detection of the film, while the second detection mechanism 2 is responsible for the longitudinal stretching and bottom surface detection of the film. The two mechanisms are connected and complementary in function to achieve comprehensive detection of the film. The first detection mechanism 1 includes a frame 3, with chain teeth 4 installed at both ends of both sides of the frame 3. The chain teeth 4 on the same side of the frame 3 are connected by a chain 5. A transmission box is installed on the upper part of the conveyor belt, with its output end connected to the chain teeth 4 and its input end connected to the output end of the power motor. The power motor drives the chain teeth 4 to rotate through the transmission box, which in turn drives the chain 5 to rotate. The chain 5 drives the chain plates 7 to move cyclically through the mounting base 6, achieving continuous and stable conveying of the film. The conveying speed is synchronized with the production line. Several chain plates 7 are installed at equal intervals between two chains 5 through the mounting base 6. Slide rails 8 are symmetrically arranged on the chain plates 7, and suction seats 9 are slidably installed at both ends of the slide rails 8. The two suction seats 9 are elastically connected. A light trough 11 is provided in the middle, and a first supplementary light 12 is installed in the light trough 11. Several adsorption holes 10 are provided on both sides of the adsorption seat 9 at its outer end, located in the light trough 11. The adsorption holes 10 on the adsorption seat 9 are arranged in a matrix. The diameter of the adsorption holes 10 is 0.5-2mm, and the spacing between the holes is 5-10mm. A mounting bracket 25 is installed on the frame 3, and a first scanning camera 26 is installed on the mounting bracket 25. Circular guide seats 13 are symmetrically installed on the outer side of the frame 3. The circular guide seats 13 include a pressing section 14 and a separating section 15 with V-shaped grooves. The two adsorption seats 9 are connected... Several spring grooves 16 are provided at opposite ends, and springs 17 are installed in the spring grooves 16. A ball seat 18 is installed at the outer end of the adsorption seat 9, and a ball 19 is installed in the ball seat 18. The ball 19 rolls along the inner wall of the annular guide seat 13. In the pressing section 14, the two adsorption seats 9 overcome the elastic force of the springs 17 and move closer to each other to facilitate film coverage. In the separating section 15, the springs 17 are released and push the two adsorption seats 9 to slide to both sides, applying a lateral pulling force to the film and realizing the lateral stretching of the film. This structure allows the film to be fully laterally unfolded before detection, completely eliminating longitudinal wrinkles. A rotating shaft 20 is rotatably mounted through the middle of the frame 3. Slip rings 21 and rotary joints 22 are mounted at both ends of the rotating shaft 20. A first supplementary light 12 is connected to the slip rings 21 via wires. An air groove communicating with the rotary joint 22 is opened inside the rotating shaft 20. The air groove is connected to the adsorption hole 10 of the adsorption seat 9 via a connecting hose. The rotating shaft 20 passes through the input end of a gear transmission box 23 mounted on the outside of the frame 3. The output end of the gear transmission box 23 is connected to a first motor 24. The adsorption hole 10 is connected to an external vacuum source via the rotary joint 22, the air groove inside the rotating shaft 20, and the connecting hose, generating negative pressure to firmly adsorb the film onto the surface of the adsorption seat 9, preventing relative slippage of the film during lateral stretching and ensuring high stretching accuracy. The first motor 24 drives the rotating shaft 20 to rotate via the gear transmission box 23, causing the wires connected to the adsorption seat 9 and the connecting hose to rotate synchronously, preventing entanglement during cyclic movement and ensuring reliable power supply and negative pressure.

[0019] The second detection mechanism 2 includes symmetrically arranged uprights 27, on which conveyor rollers 28 and pressure rollers 31 are mounted. A first support frame 35 and a second support frame 37 are also mounted on the uprights 27. A second scanning camera 36 is mounted on the first support frame 35, and a lamp holder 38 is mounted on the second support frame 37, with a second supplementary light 39 installed inside the lamp holder 38. A reducer 32 is mounted on the uprights 27, with its input end connected to the output end of a second motor 33, and its output end connected to the conveyor rollers 28. A slide groove 29 is provided on the uprights 27, and a pneumatic cylinder 34 is mounted on the top of the uprights 27. The telescopic end of the pneumatic cylinder 34 connects to the slide groove. The lifting roller seat 30 inside 29 is connected, and the lifting roller seat 30 is connected to the end of the pressure roller 31. The linear speed of the conveying roller 28 driven by the second motor 33 is greater than the conveying speed of the chain plate 7 of the first detection mechanism 1. The speed difference applies a forward pulling force to the film, generating longitudinal tension, so that the film maintains constant tension during the detection process. By adjusting the speed of the second motor 33, the speed difference between the conveying roller 28 and the chain plate 7 can be precisely controlled, thereby adjusting the magnitude of the longitudinal tension force to adapt to films of different thicknesses and materials. The pneumatic cylinder 34 drives the lifting roller seat 30 to rise and fall along the slide 29, driving the pressure roller 31 to press or release the film, which facilitates the film threading operation and tension adjustment.

[0020] Both the first scanning camera 26 and the second scanning camera 36 are linear scan cameras, and the scanning direction is towards the thin film above the first supplementary light 12 and the second supplementary light 39. The first scanning camera 26 is located above the thin film, and the second scanning camera 36 is located below the thin film. The first scanning camera 26 performs a top surface scan of the thin film from above, and the second scanning camera 36 performs a bottom surface scan of the thin film from below, so as to achieve comprehensive detection of the upper and lower surfaces of the thin film.

[0021] Working principle: The power motor drives the chain teeth 4 to rotate through the transmission box. The chain teeth 4 drive the chain 5 to rotate. The chain 5 drives the chain plate 7 and the adsorption seat 9 to move cyclically through the mounting base 6, carrying the film forward. At this time, the first motor 24 works, and the gear transmission box 23 drives the rotating shaft 20 to rotate. The wires and connecting hoses connected to the adsorption seat 9 rotate synchronously to avoid the wires and connecting hoses from getting tangled. The upper surface of the adsorption seat 9 contacts the film. Its adsorption holes 10 are connected to an external vacuum source through the rotary joint 22, the internal air groove of the rotating shaft 20 and the hose, generating negative pressure to adsorb and fix the film. As the adsorption seat 9 moves with the chain plate 7, the ball bearings 19 at its outer end always roll along the inner wall of the fixed annular guide seat 13, adjusting the distance between the two adsorption seats 9. In the pressing section 14 of the guide seat, the two adsorption seats 9 overcome the elastic force of the spring 17 and are in a close-to-each-other state, which facilitates film coverage. When adsorption... When seat 9 enters the separation section 15 of the guide seat, as the V-groove widens, spring 17 is released, pushing the two adsorption seats 9 to slide to both sides on the slide rail 8, realizing the lateral stretching of the film. During the lateral stretching process, the first scanning camera 26 located on the mounting frame 25 performs the first scan on the film surface, and the first supplementary light 12 on the adsorption seat 9 provides illumination. After the film completes the lateral stretching, it leaves the first detection mechanism 1 and enters between the conveying roller 28 and the pressure roller 31 of the second detection mechanism 2. The linear speed of the conveying roller 28 driven by the second motor 33 is greater than the conveying speed of the chain plate 7 of the first detection mechanism 1. The speed difference applies a forward pulling force to the film, thereby generating longitudinal stretching. After longitudinal stretching, the film passes under the second scanning camera 36 with higher flatness and tension. The second supplementary light 39 in the lamp holder 38 provides supplementary light to detect micro-cracks and pinhole defects that are more easily exposed under longitudinal stress.

[0022] 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 film surface defect on-line inspection device for a blown film production line, characterized by, The device includes a first testing mechanism (1) and a second testing mechanism (2), and the film is transported between the first testing mechanism (1) and the second testing mechanism (2). The first testing mechanism (1) includes a frame (3). Both ends of the frame (3) are equipped with chain teeth (4). The chain teeth (4) on the same side of the frame (3) are connected by a chain (5). Several chain plates (7) are installed at equal intervals between the two chains (5) through mounting seats (6). Slide rails (8) are symmetrically arranged on the chain plates (7). Adsorption seats (9) are slidably installed at both ends of the slide rails (8). The two adsorption seats (9) are elastically connected. A lamp groove (11) is opened in the middle of the adsorption seat (9). A first supplementary light (12) is installed in the lamp groove (11). Several adsorption holes (10) are opened at the outer end of the adsorption seat (9) and on both sides of the lamp groove (11). A mounting frame (25) is installed on the frame (3). A first scanning camera (26) is installed on the mounting frame (25). The second detection mechanism (2) includes a symmetrically arranged upright frame (27), on which a conveying roller (28) and a pressure roller (31) are installed. A first support frame (35) and a second support frame (37) are installed on the upright frame (27). A second scanning camera (36) is installed on the first support frame (35), and a lamp holder (38) is installed on the second support frame (37). A second supplementary light (39) is installed inside the lamp holder (38).

2. The online detection device for film surface defects in a blown film production line according to claim 1, characterized in that, A transmission box is installed on the frame (3), and the output end of the transmission box is connected to the chain teeth (4), and the input end of the transmission box is connected to the output end of the power motor.

3. The online detection device for film surface defects in a blown film production line according to claim 2, characterized in that, The frame (3) is symmetrically equipped with annular guide seats (13), which include a pressing section (14) and a separating section (15) with a V-shaped groove. Several spring grooves (16) are provided at opposite ends of the two adsorption seats (9), and springs (17) are installed in the spring grooves (16). A ball seat (18) is installed at the outer end of the adsorption seat (9), and a ball (19) is installed in the ball seat (18). The ball (19) rolls along the inner wall of the annular guide seat (13).

4. The online detection device for film surface defects in a blown film production line according to claim 3, characterized in that, A rotating shaft (20) is rotatably mounted through the middle of the frame (3). An electric slip ring (21) and a rotary joint (22) are respectively installed at both ends of the rotating shaft (20). The first supplementary light (12) is connected to the electric slip ring (21) through a wire. An air groove communicating with the rotary joint (22) is opened in the rotating shaft (20). The air groove is connected to the adsorption hole (10) of the adsorption seat (9) through a connecting hose. The rotating shaft (20) passes through the input end of the gear transmission box (23) installed on the outside of the frame (3), and the output end of the gear transmission box (23) is connected to the first motor (24).

5. The online detection device for film surface defects in a blown film production line according to claim 4, characterized in that, A speed reducer (32) is installed on the stand (27). The input end of the speed reducer (32) is connected to the output end of the second motor (33), and the output end of the speed reducer (32) is connected to the conveyor roller (28).

6. The online detection device for film surface defects in a blown film production line according to claim 5, characterized in that, The upright frame (27) is provided with a sliding groove (29), and a pneumatic cylinder (34) is installed on the top of the upright frame (27). The telescopic end of the pneumatic cylinder (34) is connected to the lifting roller seat (30) in the sliding groove (29), and the lifting roller seat (30) is connected to the end of the pressure roller (31).

7. The online detection device for film surface defects in a blown film production line according to claim 6, characterized in that, The first scanning camera (26) and the second scanning camera (36) are both linear scan cameras, and the scanning direction is towards the thin film above the first fill light (12) and the second fill light (39). The first scanning camera (26) is located above the thin film, and the second scanning camera (36) is located below the thin film.

8. The online detection device for film surface defects in a blown film production line according to claim 7, characterized in that, The adsorption holes (10) on the adsorption seat (9) are arranged in a matrix. The diameter of the adsorption holes (10) is 0.5-2mm and the spacing between the holes is 5-10mm.

9. The online detection device for film surface defects in a blown film production line and its working method according to claim 8, characterized in that, The specific operational steps of this working method are as follows: Step 1: The power motor drives the chain teeth (4) to rotate through the transmission box. The chain teeth (4) drive the chain (5) to rotate. The chain (5) drives the chain plate (7) and the adsorption seat (9) to move in a cycle through the mounting base (6), carrying the film forward. At this time, the first motor (24) works, and the gear transmission box (23) drives the rotating shaft (20) to rotate. The wires and connecting hoses connected to the adsorption seat (9) rotate synchronously to avoid the wires and connecting hoses from getting tangled. The upper surface of the adsorption seat (9) contacts the film. Its adsorption holes (10) are connected to an external vacuum source through the rotary joint (22), the internal air groove of the rotating shaft (20) and the hose, generating negative pressure to adsorb and fix the film. During the process of the adsorption seat (9) moving with the chain plate (7), The ball (19) at its outer end always rolls along the inner wall of the fixed annular guide (13) to adjust the distance between the two adsorption seats (9). In the pressing section (14) of the guide, the two adsorption seats (9) overcome the elastic force of the spring (17) and are in a close-to-each-other state, which is convenient for film coverage. When the adsorption seat (9) enters the separating section (15) of the guide, as the V-groove widens, the spring (17) is released, pushing the two adsorption seats (9) to slide to both sides on the slide rail (8), realizing the lateral stretching of the film. During the lateral stretching process, the first scanning camera (26) located on the mounting bracket (25) performs the first scan on the film surface, and the first supplementary light (12) on the adsorption seat (9) provides illumination. Step 2: After the film that has completed the transverse stretching leaves the first detection mechanism (1), it enters the second detection mechanism (2) between the conveyor roller (28) and the pressure roller (31). The linear speed of the conveyor roller (28) driven by the second motor (33) is greater than the conveying speed of the chain plate (7) of the first detection mechanism (1). The speed difference applies a forward pulling force to the film, thereby generating longitudinal stretching. After longitudinal stretching, the film passes under the second scanning camera (36) with higher flatness and tension. The second supplementary light (39) in the lamp holder (38) provides supplementary light to detect microcracks and pinhole defects that are more easily exposed under longitudinal stress.

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