A transverse stretching process for polyimide films

Abstract

This invention belongs to the field of polyimide film performance testing technology, specifically a transverse stretching process for polyimide films, including the following steps: Step 1, film preparation; Step 2, film clamping; Step 3, transverse stretching and marking. The device used in this invention employs a transverse stretching mechanism. When the transverse stretching drive block gradually moves to the maximum transverse stretching position, it drives the lower pressure plug to squeeze the fluorescent liquid inside the fluorescent liquid cylinder, extruding the fluorescent liquid from the fluorescent liquid nozzle and applying it to the surface of the polyimide film. The fluorescent liquid emits fluorescence under ultraviolet light. A buffer spring counteracts the initial stretching deformation of the polyimide film during deformation. Fluorescent liquid is only ejected after the polyimide film is transversely stretched to its limit position. This avoids waste of fluorescent liquid and ensures that marking is only performed when the film is fully stretched and reaches the predetermined deformation state.

Description

Technical Field

[0001] This invention belongs to the field of polyimide film performance testing technology, specifically a transverse stretching process for polyimide films. Background Technology

[0002] Polyimide films, due to their superior physical properties such as high strength, high modulus, high temperature resistance, and good electrical insulation, are widely used in electronics, aerospace, and automotive fields. These physical properties make polyimide films occupy an important position in the field of high-performance materials. Polyimide films are produced by polycondensation of pyromellitic dianhydride and diaminodiphenyl ether in a highly polar solvent, followed by casting and imidization. After preparation, the transverse elongation of the polyimide film needs to be tested using a stretching device.

[0003] A search revealed Chinese patent CN118464673A, which discloses a transverse stretching device for polyimide film, comprising a support unit, a first clamping unit, a second clamping unit, a stretching unit, and a locking unit. This invention, by incorporating a locking unit, allows the film to move during stretching if the second clamping unit is not tightly secured. This movement causes the locking roller on the surface to rotate, and the swing arm on the locking roller rotates synchronously, pushing a strip plate slidably mounted on the surface to move. This, in turn, moves the baffle and partition away from the first clamping unit, bringing the positioning rack and gear into contact, thus locking the rotation of the clamping rod. Since the clamping rod is inserted into the slot, the first and second clamping units do not move relative to each other, and the transverse stretching test automatically stops. The operator then needs to re-tighten the film, improving the accuracy of the stretching test and making it suitable for widespread application.

[0004] However, after using this equipment to stretch the polyimide film laterally, the deformation of the polyimide film, especially the characteristics such as tiny cracks and necking, is difficult to observe directly with the naked eye. Summary of the Invention

[0005] The purpose of this invention is to provide a transverse stretching process for polyimide films to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a transverse stretching process for polyimide films, comprising the following steps:

[0007] Step 1, Film Preparation: Place the polyimide film to be tested for transverse tensile strength on the winding roller, guide it with the guide roller and keep it flat, and cut it with the electric clamp and electric push rod driven by the cutting scissors.

[0008] Step 2, Film clamping: The cut polyimide film is moved to the transverse stretching mechanism by the electric guide rail and electric slider, and both ends of the polyimide film are clamped by electric clamps.

[0009] Step 3, Lateral Stretching and Marking: Start the motor of the lateral stretching mechanism, and stretch the polyimide film laterally through the transmission rod and the lateral stretching drive block; at the same time, through the action of the linkage plate, linkage rod, linkage pressure plate, buffer spring and lower pressure plug, when the stretching reaches the maximum position, the fluorescent liquid cylinder is squeezed, and the fluorescent liquid is squeezed out from the fluorescent liquid nozzle and applied to the surface of the polyimide film.

[0010] The transverse stretching mechanism is located behind the film cutting table. The transverse stretching mechanism includes an L-shaped connecting arm, a transmission rod, a transverse stretching drive block, a fixed bracket, an electric clamp, a linkage rod, a linkage pressure plate, a buffer spring, a lower pressure plug, and a fluorescent liquid cylinder.

[0011] Preferably, the fluorescent liquid cylinder has a lower pressure plug inside, and a limit rod is fixedly connected to the upper end of the lower pressure plug. The upper end of the limit rod passes through a linkage pressure plate. A buffer spring is provided between the linkage pressure plate and the lower pressure plug, and the buffer spring is sleeved on the outside of the limit rod. Linkage rods are rotatably connected to both sides of the linkage pressure plate. The ends of the two linkage rods away from the linkage pressure plate are rotatably connected to the upper surfaces of the two linkage plates, respectively. The two linkage plates are fixedly connected to the outside of the two horizontal pull drive blocks, and a transmission rod is provided through the middle of the lower side of the two horizontal pull drive blocks. The left and right end surfaces of the transmission rod (402) are provided with threaded structures, and the thread directions of the two threaded structures are opposite. The two horizontal pull drive blocks are threadedly connected to the transmission rod through the threaded structures. A connecting groove is opened above the two L-shaped connecting arms. The two horizontal pull drive blocks are slidably connected inside the corresponding connecting grooves. Fixed brackets are fixedly connected to the left and right sides of the two horizontal pull drive blocks. An electric clamp is provided on the front side of each fixed bracket. A limit plate is fixedly connected to the upper end of the limit rod. The limit plate is located above the linkage pressure plate.

[0012] Preferably, a motor is provided on the outer side of the L-shaped connecting arm on the right, and the output end of the motor is connected to the transmission rod.

[0013] Preferably, the fluorescent liquid cylinder is filled with fluorescent liquid, and a fluorescent liquid nozzle is provided at the lower end of the fluorescent liquid cylinder.

[0014] Preferably, a winding roller is provided on the front side of the film cutting table, and a polyimide film is wound on the outer side of the middle part of the winding roller.

[0015] Preferably, a support frame is fixedly connected to the upper rear side of the film cutting table, an electric push rod is provided in the middle of the upper surface of the support frame, a cutting scissor is connected to the free end of the electric push rod, a cutting support plate is provided below the cutting scissor, the cutting support plate is fixedly connected to the film cutting table, and a through groove is provided in the middle of the cutting support plate.

[0016] Preferably, the front side of the cutting support plate is provided with three guide rollers, which are horizontally and evenly distributed inside the upper end of the film cutting table, and all three guide rollers are rotatably connected to the film cutting table.

[0017] Preferably, a positioning rod is fixedly connected to the rear side of the fluorescent liquid cylinder, and the end of the positioning rod away from the fluorescent liquid cylinder is fixedly connected to the side of the outer bracket. The left and right ends of the lower end of the outer bracket are fixedly connected to the left and right sides of the tensile testing table.

[0018] Preferably, electric guide rails are fixedly connected to both the left and right sides of the upper surface of the tensile testing platform, electric sliders are slidably connected to the upper surfaces of the two electric guide rails, a film-stretching plate is fixedly connected between the two electric sliders, and three electric clamps are provided on the front side of the film-stretching plate.

[0019] Preferably, a film-pulling plate is fixedly connected between the two electric sliders, and three electric clamps are provided on the front side of the film-pulling plate.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention includes a transverse stretching mechanism. The polyimide film to be tested is placed on a film cutting table and cut into appropriate sizes as needed. The cut polyimide film is then moved to the transverse stretching mechanism on the tensile testing table. Both ends of the polyimide film are clamped by two electric clamps. When the motor starts, the transmission rod rotates, and the two transverse stretching drive blocks, due to their opposite thread directions, move in opposite directions, thereby stretching the polyimide film laterally. As the two transverse stretching drive blocks move, the outer end of the linkage rod connected to the upper end of the transverse stretching drive block via a linkage plate extends outward, while the inner end of the linkage rod swings towards the fluorescent liquid cylinder. This causes the linkage pressure plate to move downward and compress the buffer spring between the linkage pressure plate and the lower pressure plug. When the transverse stretching drive block gradually moves to the maximum transverse stretching position, the linkage plate and linkage rod drive the... As the linkage plate moves downward, the buffer spring stops deforming, causing the lower pressure plug to squeeze the fluorescent liquid inside the fluorescent liquid cylinder. The fluorescent liquid is then extruded from the fluorescent liquid nozzle and applied to the surface of the polyimide film. Under ultraviolet light, the fluorescent liquid emits fluorescence, creating a sharp contrast with the color and material of the polyimide film itself. This high-contrast marking makes features such as the deformed area after stretching, crack propagation, and necking more clearly visible, facilitating visual observation and subsequent accurate measurement. The buffer spring can counteract the initial stretching deformation of the polyimide film during the deformation process. Fluorescent liquid is only sprayed out after the polyimide film is stretched laterally to its limit. This avoids waste of fluorescent liquid and ensures that the fluorescent liquid is applied precisely according to the stretching state of the film, as the fluorescent liquid application timing corresponds precisely to the stretching state of the film.

[0022] 2. This invention is equipped with a cutting scissors. When it is necessary to cut the polyimide film, the polyimide film is pulled out from the winding roller into the electric clamp two. The electric clamp two clamps the rear edge of the polyimide film, and the electric push rod on the upper surface of the support frame is activated. The free end of the electric push rod pushes the cutting scissors downward, so that the cutting scissors cooperate with the cutting support plate below. The through groove in the middle of the cutting support plate allows the cutting scissors to pass smoothly, realizing the cutting of the polyimide film. Then, the electric guide rail drives the electric slider to move backward with the electric clamp two, pulling out the cut polyimide film. This realizes the automation of film cutting, clamping and stretching preparation, improving work efficiency and accuracy. Attached Figure Description

[0023] Figure 1 This is a front-view perspective three-dimensional structural diagram of the device used in this invention;

[0024] Figure 2 This is a rear-view perspective structural diagram of the device used in this invention;

[0025] Figure 3This is a schematic diagram of the front half of the device used in this invention.

[0026] Figure 4 This is a schematic diagram of the rear half of the device used in this invention.

[0027] Figure 5 This is a bottom view of the rear half of the device used in this invention.

[0028] Figure 6 This is a schematic diagram of the transverse tensioning mechanism of the device used in this invention.

[0029] Figure 7 The apparatus used in this invention Figure 5 Enlarged structural diagram at point A;

[0030] Figure 8 The apparatus used in this invention Figure 6 A magnified structural diagram at point B in the middle.

[0031] In the diagram: 1. Tensile testing table; 2. Film cutting table; 3. Polyimide film; 4. Transverse tensile mechanism; 401. L-shaped connecting arm; 402. Transmission rod; 403. Threaded structure; 404. Transverse pulling drive block; 405. Fixed bracket; 406. Electric clamp one; 407. Connecting groove; 408. Linkage plate; 409. Linkage rod; 410. Linkage pressure plate; 411. Limiting rod; 412. Buffer spring; 413. Lower pressure plug; 414. Fluorescent liquid cylinder; 415. Fluorescent liquid nozzle; 416. Limiting plate; 417. Motor; 5. Outer bracket; 6. Guide roller; 7. Support frame; 8. Electric push rod; 9. Cutting shears; 10. Electric guide rail; 11. Electric slider; 12. Film pulling plate; 13. Positioning rod; 14. Electric clamp two; 15. Winding roller; 16. Cutting support plate. Detailed Implementation

[0032] 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.

[0033] Please see Figures 1-8 The present invention provides two technical solutions, specifically including the following embodiments:

[0034] Example 1:

[0035] A transverse stretching process for a polyimide film includes the following steps:

[0036] Step 1, Film Preparation: Place the polyimide film 3 to be tested for transverse tensile strength on the winding roller 15, guide it with the guide roller 6 and keep it flat, and cut it with the electric clamp 14 and the electric push rod 8.

[0037] Step 2, film clamping: The cut polyimide film 3 is moved to the transverse stretching mechanism 4 by the electric guide rail 10 and the electric slider 11, and both ends of the polyimide film 3 are clamped by the electric clamp 406 respectively.

[0038] Step 3, Lateral Stretching and Marking: Start the motor 417 of the lateral stretching mechanism 4, and stretch the polyimide film 3 laterally through the transmission rod 402 and the lateral stretching drive block 404; at the same time, through the action of the linkage plate 408, linkage rod 409, linkage pressure plate 410, buffer spring 412 and lower pressure plug 413, when the stretching reaches the maximum position, the fluorescent liquid cylinder 414 is squeezed, and the fluorescent liquid is squeezed out from the fluorescent liquid nozzle 415 and applied to the surface of the polyimide film 3;

[0039] The transverse stretching mechanism 4 is located behind the film cutting table 2. During the preparation of the polyimide film 3, it is used to achieve transverse stretching of the polyimide film 3 and surface fluorescent liquid marking. The transverse stretching mechanism 4 includes an L-shaped connecting arm 401, a transmission rod 402, a transverse stretching drive block 404, a fixed bracket 405, an electric clamp 406, a linkage rod 409, a linkage pressure plate 410, a buffer spring 412, a lower pressure plug 413, and a fluorescent liquid cylinder 414. The fluorescent liquid cylinder 414 has a lower pressure plug 413 inside. A limit rod 411 is fixedly connected to the upper end of the lower pressure plug 413. The upper end of the limit rod 411 passes through a linkage pressure plate 410. A buffer spring 412 is provided between the linkage pressure plate 410 and the lower pressure plug 413. The buffer spring 412 is sleeved on the outside of the limit rod 411. Linkage rods 409 are rotatably connected to both sides of the linkage pressure plate 410. The ends of the two linkage rods 409 away from the linkage pressure plate 410 are rotatably connected to the upper surfaces of two linkage plates 408. The two linkage plates 408 are fixedly connected to the outside of two horizontal pull drive blocks 404. A transmission rod 402 is provided through the middle of the lower side of the two horizontal pull drive blocks 404. Threaded structures 403 are provided on the surfaces of the left and right ends of the transmission rod 402, and the threads of the two threaded structures 403 are opposite in direction. The two horizontal pull drive blocks 404 are threadedly connected to the transmission rod 402 through the threaded structures 403. Two L-shaped... Connecting slots 407 are provided on the upper part of each connecting arm 401. Two horizontal pull drive blocks 404 are slidably connected inside the corresponding connecting slots 407. Fixed brackets 405 are fixedly connected to the left and right sides of the two horizontal pull drive blocks 404. An electric clamp 406 is provided on the front side of each fixed bracket 405. A limit plate 416 is fixedly connected to the upper end of the limit rod 411. The limit plate 416 is located above the linkage pressure plate 410. A motor 417 is provided on the outer side of the right L-shaped connecting arm 401. The output end of the motor 417 is connected to the transmission rod 402. Fluorescent liquid cylinder 414 is filled with fluorescent liquid. A fluorescent liquid nozzle 415 is provided at the lower end of the fluorescent liquid cylinder 414. A positioning rod 13 is fixedly connected to the rear side of the fluorescent liquid cylinder 414. The end of the positioning rod 13 away from the fluorescent liquid cylinder 414 is fixedly connected to the side of the outer bracket 5. The left and right ends of the lower end of the outer bracket 5 are fixedly connected to the left and right sides of the tensile testing table 1.

[0040] During operation, the polyimide film 3 to be tested is placed on the film cutting table 2 and cut into appropriate sizes as needed. The cut polyimide film 3 is then moved to the transverse stretching mechanism 4 of the tensile testing table 1. Both ends of the polyimide film 3 are clamped by two electric clamps 406. When the motor 417 starts, the transmission rod 402 rotates, and the two transverse stretching drive blocks 404, due to their opposite thread directions, move in opposite directions, thereby stretching the polyimide film 3 laterally. As the two transverse stretching drive blocks 404 move, the outer end of the linkage rod 409, which is connected to the upper end of the transverse stretching drive block 404 via the linkage plate 408, extends outward, while the inner end of the linkage rod 409 swings towards the fluorescent liquid cylinder 414. This causes the linkage pressure plate 410 to move downward and compress the buffer spring 412 between the linkage pressure plate 410 and the lower pressure plug 413. When the transverse stretching drive block 404 gradually moves to the maximum transverse stretching position, the linkage... Plate 408 and linkage rod 409 drive linkage pressure plate 410 to move downwards, buffer spring 412 no longer deforms, driving lower pressure plug 413 to squeeze fluorescent liquid inside fluorescent liquid cylinder 414, squeezing the fluorescent liquid out of fluorescent liquid nozzle 415 and applying it to the surface of polyimide film 3. The fluorescent liquid will emit fluorescence under ultraviolet light, forming a sharp contrast with the color and material of polyimide film 3 itself. This high-contrast marking makes the deformed area, crack propagation and necking phenomenon after stretching more clearly visible, which is convenient for visual observation and subsequent accurate measurement. Buffer spring 412 can counteract the initial stage of stretching deformation of polyimide film 3 during the deformation process. Fluorescent liquid will only be sprayed out after polyimide film 3 is stretched laterally to the limit position. On the one hand, it avoids waste of fluorescent liquid. On the other hand, the fluorescent liquid will only be marked when the film is fully stretched and reaches the predetermined deformation state, ensuring that the timing of fluorescent liquid application corresponds precisely to the stretching state of the film.

[0041] Example 2:

[0042] Based on Embodiment 1, a winding roller 15 is provided on the front side of the film cutting table 2. A polyimide film 3 is wound on the outer side of the middle part of the winding roller 15. A support frame 7 is fixedly connected to the upper rear side of the film cutting table 2. An electric push rod 8 is provided in the middle of the upper surface of the support frame 7. A cutting scissors 9 is connected to the free end of the electric push rod 8. A cutting support plate 16 is provided below the cutting scissors 9. The cutting support plate 16 is fixedly connected to the film cutting table 2. A through groove is opened in the middle of the cutting support plate 16. Three guide rollers 6 are provided on the front side of the cutting support plate 16. The three guide rollers 6 are horizontally and evenly distributed inside the upper end of the film cutting table 2. The three guide rollers 6 are rotatably connected to the film cutting table 2. The function of the guide rollers 6 is to guide the direction of film movement and keep the polyimide film 3 flat when passing through, avoiding wrinkles or twisting, and ensuring the accuracy of subsequent cutting and stretching. The surface of the tensile testing table 1 is shown. Electric guide rails 10 are fixedly connected to both sides of the surface. Electric sliders 11 are slidably connected to the upper surfaces of the two electric guide rails 10. A film-pulling plate 12 is fixedly connected between the two electric sliders 11. Three electric clamps 14 are set on the front side of the film-pulling plate 12. When the polyimide film 3 needs to be cut, the polyimide film 3 is pulled out from the winding roller 15 into the electric clamps 14. The electric clamps 14 clamp the rear edge of the polyimide film 3. The electric push rod 8 on the upper surface of the support frame 7 is activated. The free end of the electric push rod 8 pushes the cutter 9 to move downward, so that the cutter 9 cooperates with the cutting support plate 16 below. The through slot in the middle of the cutting support plate 16 allows the cutter 9 to pass smoothly, realizing the cutting of the polyimide film 3. Then the electric guide rails 10 drive the electric sliders 11 and the electric clamps 14 to move backward, pulling out the cut polyimide film 3.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the application should be included within the protection scope of the present invention.

Claims

1. A transverse stretching process for polyimide films, comprising the following steps: Step 1, Film preparation: Place the polyimide film (3) to be tested for transverse tensile strength on the winding roller (15), guide it with the guide roller (6) and keep it flat, and cut it with the cutting scissors (9) driven by the electric clamp (14) and the electric push rod (8); Step 2, film clamping: The cut polyimide film (3) is moved to the transverse stretching mechanism (4) by the drive of the electric guide rail (10) and the electric slider (11), and the two ends of the polyimide film (3) are clamped by the electric clamp (406) respectively. Step 3, Lateral stretching and marking: Start the motor (417) of the lateral stretching mechanism (4), and stretch the polyimide film (3) laterally through the transmission rod (402) and the lateral stretching drive block (404); at the same time, through the action of the linkage plate (408), linkage rod (409), linkage pressure plate (410), buffer spring (412) and lower pressure plug (413), when the stretching reaches the maximum position, squeeze the fluorescent liquid cylinder (414), squeeze the fluorescent liquid out from the fluorescent liquid nozzle (415) and apply it to the surface of the polyimide film (3); The transverse stretching mechanism (4) is located behind the film cutting table (2). The transverse stretching mechanism (4) includes an L-shaped connecting arm (401), a transmission rod (402), a transverse stretching drive block (404), a fixed bracket (405), an electric clamp (406), a linkage rod (409), a linkage pressure plate (410), a buffer spring (412), a lower pressure plug (413), and a fluorescent liquid cylinder (414). The fluorescent liquid cylinder (414) is equipped with a lower pressure plug (413). The upper part of the lower pressure plug (413) is... A limiting rod (411) is fixedly connected to the end. The upper end of the limiting rod (411) passes through the linkage pressure plate (410). A buffer spring (412) is provided between the linkage pressure plate (410) and the lower pressure plug (413). The buffer spring (412) is sleeved on the outside of the limiting rod (411). Linkage rods (409) are rotatably connected to both the left and right sides of the linkage pressure plate (410). The ends of the two linkage rods (409) away from the linkage pressure plate (410) are rotatably connected to the upper surfaces of the two linkage plates (408).

2. The transverse stretching process for polyimide films according to claim 1, characterized in that: Two linkage plates (408) are fixedly connected to the outside of two horizontal pull drive blocks (404). A transmission rod (402) is provided through the middle of the lower side of the two horizontal pull drive blocks (404). The left and right end surfaces of the transmission rod (402) are provided with threaded structures (403), and the thread directions of the two threaded structures (403) are opposite. The two horizontal pull drive blocks (404) are threadedly connected to the transmission rod (402) through the threaded structures (403). The two L-shaped connecting arms (401) A connecting groove (407) is provided above each of the two horizontal pull drive blocks (404). The two horizontal pull drive blocks (404) are slidably connected inside the corresponding connecting groove (407). Fixed brackets (405) are fixedly connected to the left and right sides of the two horizontal pull drive blocks (404). An electric clamp (406) is provided on the front side of each fixed bracket (405). A limit plate (416) is fixedly connected to the upper end of the limit rod (411). The limit plate (416) is located above the linkage pressure plate (410).

3. The transverse stretching process for polyimide films according to claim 1, characterized in that: A motor (417) is provided on the outer side of the L-shaped connecting arm (401) on the right side, and the output end of the motor (417) is connected to the transmission rod (402) for transmission.

4. The transverse stretching process for polyimide films according to claim 1, characterized in that: The fluorescent liquid cylinder (414) is filled with fluorescent liquid, and a fluorescent liquid nozzle (415) is provided at the lower end of the fluorescent liquid cylinder (414).

5. The transverse stretching process for polyimide films according to claim 1, characterized in that: A winding roller (15) is provided on the front side of the film cutting table (2), and a polyimide film (3) is wound on the outer side of the middle part of the winding roller (15).

6. The transverse stretching process for polyimide films according to claim 1, characterized in that: A support frame (7) is fixedly connected to the upper rear side of the film cutting table (2). An electric push rod (8) is provided in the middle of the upper surface of the support frame (7). A cutting scissors (9) is connected to the free end of the electric push rod (8). A cutting support plate (16) is provided below the cutting scissors (9). The cutting support plate (16) is fixedly connected to the film cutting table (2). A through groove is provided in the middle of the cutting support plate (16).

7. The transverse stretching process for polyimide films according to claim 6, characterized in that: The front side of the cutting support plate (16) is provided with three guide rollers (6), which are horizontally distributed in sequence inside the upper end of the film cutting table (2), and the three guide rollers (6) are rotatably connected to the film cutting table (2).

8. The transverse stretching process for polyimide films according to claim 1, characterized in that: A positioning rod (13) is fixedly connected to the rear side of the fluorescent liquid cylinder (414). The end of the positioning rod (13) away from the fluorescent liquid cylinder (414) is fixedly connected to the side of the outer bracket (5). The left and right ends of the lower end of the outer bracket (5) are fixedly connected to the left and right sides of the tensile test table (1).

9. The transverse stretching process for polyimide films according to claim 8, characterized in that: Electric guide rails (10) are fixedly connected to the left and right sides of the upper surface of the tensile test bench (1). Electric sliders (11) are slidably connected to the upper surfaces of the two electric guide rails (10). A film-pulling plate (12) is fixedly connected in the middle of the two electric sliders (11). Three electric clamps (14) are provided on the front side of the film-pulling plate (12).

10. The transverse stretching process for polyimide films according to claim 9, characterized in that: A film-pulling plate (12) is fixedly connected between the two electric sliders (11), and three electric clamps (14) are provided on the front side of the film-pulling plate (12).

Images