A dry method diaphragm stretching production line and a dry method diaphragm processing method

Abstract

The application discloses a dry-method diaphragm stretching production line and a dry-method diaphragm processing method, and relates to the diaphragm processing field.The production line comprises a drying box, a plurality of preheating rollers, a fixed pressure roller and a movable pressure roller.The plurality of preheating rollers are arranged in the accommodating cavity of the drying box and are used for conveying the base film.The fixed pressure roller is fixedly arranged in the accommodating cavity.The movable pressure roller is slidably arranged in the accommodating cavity, and a pressing space for pressing the plurality of base films is formed between the movable pressure roller and the fixed pressure roller.A driving member is arranged to drive the movable pressure roller to move and the preheating rollers to rotate.Through the above technical scheme, the holes in the casting base film are relatively uniform.Through controlling the size of the pressing space, the holes in the base film are more uniform in the early stage.

Description

Technical Field

[0001] This invention relates to the field of diaphragm processing and production, specifically to a dry diaphragm stretching production line and a dry diaphragm processing method. Background Technology

[0002] The related technology discloses a preparation process for a longitudinally and transversely stretched reinforced lithium-ion battery separator, including the following steps: First, select homopolymer powdered PP to prepare masterbatch; second, add the mixed masterbatch to an extruder for granulation; third, melt extrude the prepared particles to cast sheets; fourth, place the cast sheets into a longitudinal stretching machine to stretch them into a film; fifth, stretch the longitudinally stretched film into a transverse stretching machine; sixth, stretch the transversely stretched film longitudinally again; seventh, perform traction cooling treatment on the film after the second longitudinal stretching; eighth, perform dual-station winding; ninth, slit the separator. The separator assembled with the above process has a narrow and uniform capacity distribution, improving the capacity consistency of the battery and further increasing the battery yield.

[0003] Later, based on the above process (dry biaxial stretching process), corresponding dry biaxial stretching production lines for diaphragms were set up, including a drying chamber. Multiple preheating rollers are placed inside the drying chamber to preheat the cast base film wound on them. The free ends of multiple cast base films pass through two pressing rollers, and the cast base films are stretched through friction between adjacent films. The characteristic of the cast base film easily forming holes under tensile stress is utilized to create pores. During the stretching process, the influence of temperature on pore formation must also be considered. Therefore, an airflow system is also installed inside the drying chamber to ensure a constant temperature within the chamber.

[0004] While the above method can achieve pore formation in the cast film, the pore size is affected by both temperature and friction during the pore-forming process. However, the cast film has poor thermal conductivity, and its temperature continuously rises during unwinding from the preheating roller, while its tensile force remains constant. Therefore, the pore size cannot meet the expected requirements during pore formation. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a dry diaphragm stretching production line and a dry diaphragm processing method, thereby solving the technical problem of uneven pore size during the pore-making process of existing cast film rolls.

[0006] First aspect

[0007] To achieve the above objectives, the present invention provides a dry diaphragm stretching production line, comprising:

[0008] The drying oven is equipped with a receiving cavity.

[0009] Multiple preheating rollers are arranged inside the receiving cavity, and the preheating rollers are used to convey the base film;

[0010] A pressure roller is fixedly installed inside the receiving cavity;

[0011] A movable pressure roller is slidably disposed within the receiving cavity, and a pressing space is formed between the movable pressure roller and the fixed pressure roller for pressing a multilayer base film;

[0012] A driving element for driving the moving pressure roller closer to or away from the fixed pressure roller, and for driving the preheating roller to unwind.

[0013] By adopting the above technical solution, relatively uniform pore formation in the cast film can be achieved. Controlling the size of the pressing space ensures more uniform pores in the early stages of film formation. Since the tensile force of the film originates from the friction between the films, as the temperature of the film to be stretched continuously rises until it approaches the stretching temperature, the pressure between the films is gradually reduced by changing the pressing space. Ultimately, during the film stretching and pore formation process, the temperature and tensile force of the film to be stretched are brought to a balance point, thereby achieving effective stretching of the film and producing uniform pores.

[0014] Optionally, the driving element includes:

[0015] Power components;

[0016] The first gear is driven to rotate by the power component.

[0017] Multiple second gears mesh with the first gear, and one of the second gears is coaxially and fixedly connected to one of the preheating rollers;

[0018] The transmission component connects the first gear and the moving pressure roller.

[0019] By adopting the above technical solution, the purpose of driving the moving pressure roller to move and the preheating roller to rotate can be achieved. Since the size of the pressing space depends on the stretching temperature of the base film to be pressed, the correlation between the rotation of the preheating roller and the pressing space needs to be considered in actual use. If the rotation of the preheating roller and the pressing space are set relatively independently, a problem in either the preheating roller or the pressing space during long-term operation of the production line will affect the subsequent stretching of the base film. To solve this problem, a first gear and a second gear are set. When the first gear rotates, the second gear also rotates synchronously. In this way, a correlation is established between the rotation of the preheating roller and the movement of the moving pressure roller, and the movement of the moving pressure roller affects the size of the pressing space. That is, there is a certain correlation between the preheating roller and the pressing space. At this time, the preheating roller acts as a signal input terminal, and the output pressing space size can effectively match the expected pressing space size. Ultimately, this makes the stretching accuracy of the base film more accurate.

[0020] Optionally, the transmission component includes:

[0021] Lead screw, a power component used to drive the lead screw to rotate;

[0022] The nut is threadedly connected to the lead screw, thereby forming a lead screw and nut pair mechanism between the lead screw and the nut, and the nut is fixedly connected to the dynamic pressure roller.

[0023] By adopting the above technical solution, the directional movement of the driving pressure roller can be achieved. Since the size of the pressing space determines the tension of the base film, the adjustment of the pressing space should be minute in actual use. Excessive adjustment will result in excessive pressure, potentially leading to film breakage. This problem can be effectively solved by using a screw and nut assembly. Because the screw and nut assembly is characterized by slow and stable movement, when the power component rotates rapidly, it can effectively convert the rapid rotation into a small movement of the nut, thus meeting the need for the base film pressing space to gradually narrow.

[0024] Optionally, a plurality of second gears are arranged in a circumferential array with the axis of the first gear as the center, and the transmission ratio between the second gear and the first gear is greater than 1.

[0025] By adopting the above technical solution, the goal of ensuring the slow movement of the moving pressure roller can be further achieved. Although the screw and nut pair mechanism can achieve small-amplitude movement of the moving pressure roller, in actual production, when the number of base film turns is large, the moving pressure roller will move a large distance when a batch of base film is unwound. In order to enable the production line of this application to produce base film with multiple turns, the transmission ratio between the second gear and the first gear is greater than 1. In this way, the screw can be further decelerated, ultimately achieving the goal of slow movement of the moving pressure roller.

[0026] Optionally, it may also include a heating element disposed within the receiving cavity.

[0027] By adopting the above technical solution, the purpose of providing stretching temperature for the casting base film can be achieved.

[0028] Optional, also includes:

[0029] The circulating air pipe is provided with an air inlet and an air outlet, both of which are connected to the receiving cavity of the drying oven.

[0030] A circulation pump is installed inside the circulation air pipe;

[0031] A heat storage device is installed inside the circulating air pipe.

[0032] By adopting the above technical solution, the stretching temperature of the cast film can be adjusted. Since the initial ambient temperature of the cast film is relatively high, but considering its poor thermal conductivity, the film's own temperature will gradually increase as it is continuously unwound. If the ambient temperature remains constant in the later stages, the film's own temperature will exceed the stretching temperature. Therefore, the ambient temperature of the later stages of the cast film should be lower than that of the initial stages to match the stretching force and thus stretch the film into relatively uniform pores. To address the temperature issue, a circulating air system is formed by installing a circulating pump and circulating air pipes. A heat storage device is used to store the heat in the initial cavity of the cast film. As the film is continuously unwound, the heat storage device releases the stored heat, ensuring that the temperature within the cavity meets the later stretching temperature requirements of the cast film.

[0033] Optionally, the heat storage element includes:

[0034] A circular tube extends along the extension direction of the circulating air pipe. The outer wall of the circular tube is fixedly connected to the inner wall of the circulating air pipe. A liquid storage chamber is provided inside the circular tube for holding water.

[0035] By adopting the above technical solution, the purpose of storing / releasing heat can be achieved. Since the external temperature of the cast film needs to continuously decrease, and this temperature decrease should be a slow process to match the stretching force of the cast film at different stages, a circular tube is used. In the initial stage of stretching, the temperature inside the containment cavity is high, and the heat is drawn into the circular tube by a circulating pump. Because the circular tube contains water, it absorbs a certain amount of heat. Since the circular tube is fixed to the inner wall of the circulating gas pipe, the high-temperature gas flows through the circular tube, thus achieving rapid heating of the water inside the circular tube. As the cast film is unwound, some heat is lost from the containment cavity. This lost heat is replenished by the heat released from the high-temperature water inside the circular tube. Due to the circular tube, less heat is released from the high-temperature water into the circulating gas path. Since there is also some heat loss within the containment cavity, the heat loss within the containment cavity is greater than the heat released by the water inside the circular tube. Therefore, the containment cavity can achieve a slow temperature decrease.

[0036] Optionally, the drying oven includes an inner box and an outer box, the receiving cavity is opened in the inner box, the inner box is fixedly installed in the outer box, and a gap is provided between the inner box and the outer box, the gap being vacuumed.

[0037] By adopting the above technical solution, it is possible to prevent a large amount of heat loss from the cavity.

[0038] Second aspect

[0039] A dry diaphragm processing method, utilizing the aforementioned dry diaphragm stretching production line, includes the following steps:

[0040] S1: Installation of cast base film: A cast base film is installed on a preheating roller;

[0041] S2: Synchronous preheating and heating of the cast base film: turn on the heating element and the preheating roller so that the temperature inside the receiving cavity reaches the preset temperature;

[0042] S3: Pressing of multilayer cast base film: Pass the free end of the multilayer cast base film through the pressing space and turn on the power component.

[0043] In summary, this application includes at least one of the following beneficial technical effects:

[0044] 1. By setting a movable pressing space, the goal of relatively uniform pore formation in the cast film can be achieved;

[0045] 2. By setting up a power component, a first gear, multiple second gears, a lead screw, and a nut, the pressing space can be adaptively adjusted when the cast film is unwound synchronously, thereby meeting the purpose of matching the tensile force and stretching temperature of the cast film. In addition, by setting and adjusting the positions of multiple second gears, the pressing space can be changed slowly to meet the tensile force requirements.

[0046] 3. By setting up a circular tube, the purpose of storing / releasing temperature can be achieved, so that the temperature inside the cavity can meet the external temperature of the cast base film, thereby enabling the cast base film to reach the expected stretching temperature. Attached Figure Description

[0047] Figure 1 This is a perspective view of a dry diaphragm stretching production line according to this application;

[0048] Figure 2 This is a power principle diagram of the drive component of a dry diaphragm stretching production line according to this application;

[0049] Figure 3 This is a half-sectional view of a transmission component of a dry diaphragm stretching production line according to this application.

[0050] Figure 4 This is a cross-sectional view of the connection between the circulating air pipe and the annular pipe in a dry diaphragm stretching production line according to this application.

[0051] In the picture:

[0052] 1. Drying oven; 11. Receiving cavity; 12. Film outlet; 2. Preheating roller; 3. Constant pressure roller; 4. Dynamic pressure roller; 5. Driving component; 51. First gear; 52. Second gear; 53. Transmission component; 531. Lead screw; 532. Nut; 533. Rotating rod; 534. Directional gear; 535. Fixed base; 6. Circulating air pipe; 7. Heat storage component; 71. Circular tube; 711. Liquid storage cavity; 8. Cast base film; 9. Diaphragm. Detailed Implementation

[0053] The following is in conjunction with the appendix Figures 1-4 The following describes some embodiments of the present invention in detail.

[0054] First aspect

[0055] Please see Figure 1 As shown, the present invention provides a dry diaphragm stretching production line, comprising: a drying box 1, multiple preheating rollers 2, a fixed pressure roller 3, a dynamic pressure roller 4, a drive unit 5, a heating unit (not shown in the figure), a circulating air pipe 6, a circulating pump (not shown in the figure), and a heat storage unit 7 (not shown in the figure).

[0056] Please see Figure 1As shown, the drying chamber 1 is used to maintain the temperature inside the drying chamber and prevent excessive temperature loss. The drying chamber 1 includes an inner chamber (not shown in the figure) and an outer chamber (not shown in the figure). The inner chamber is fixedly installed inside the outer chamber, thus creating a gap between the inner and outer chambers. The air in this gap is treated by vacuuming, thereby isolating the temperature transfer between the inner and outer chambers and achieving effective temperature insulation. A receiving cavity 11 is provided inside the inner chamber to provide space for the installation of other components. A film outlet 12 is located on the right side of the drying chamber 1, and a hinged door (not shown in the figure) is located at the front of the drying chamber 1. The receiving cavity 11 can be opened by opening the hinged door to allow operators to perform internal operations, and the receiving cavity 11 can be kept relatively sealed by closing the hinged door. It should be noted that sealing strips are installed on the hinged door and drying chamber 1, which can reduce heat loss to a certain extent. Of course, heat exchange will also occur between the inside of the receiving cavity 11 and the outside at the membrane outlet 12, but the heat loss at this point is relatively low.

[0057] Please see Figure 1 As shown, a multi-roll cast base film 8 is arranged in a circumferential array within a receiving cavity 11. A fixed pressure roller 3 is fixedly installed within the receiving cavity 11, while a movable pressure roller 4 is installed within the receiving cavity 11, moving up and down. A pressing space is formed between the movable pressure roller 4 and the fixed pressure roller 3. The free end of the multi-roll cast base film 8 passes through the pressing space and is pressed to form a diaphragm 9 product. The diaphragm 9 exits from the film outlet 12 and then enters the next processing step.

[0058] Please combine Figure 2 As shown, the driving component 5 is used to drive the unwinding of the cast base film 8. The driving component 5 includes a power component (not shown in the figure), a first gear 51, multiple second gears 52, and a transmission component 53. In this embodiment, the driving component 5 is a servo motor, which is fixedly installed at the rear of the drying chamber 1. The output end of the servo motor is fixedly connected to the first gear 51, thereby driving the rotation of the first gear 51. Multiple second gears 52 are distributed in a circumferential array around the first gear 51. Each second gear 52 is fixedly connected to a preheating roller 2, ultimately achieving synchronous rotation of the first gear 51, the second gears 52, and the preheating roller 2 driven by the servo motor. The preheating roller 2 is prior art and will not be described in detail here. The function of the preheating roller 2 is not only to unwind the cast base film 8 on it, but also to heat the cast base film 8 on it.

[0059] Please see Figure 2 and Figure 3As shown, the transmission component 53 is used to synchronously transmit the power of the servo motor to the up-and-down movement of the moving pressure roller 4. The transmission component 53 includes: a lead screw 531, a nut 532, a rotating rod 533, multiple steering gears 534, and multiple fixed seats 535. The first gear 51 and the rotating rod 533 are fixedly connected by a connecting key, thereby ensuring that the power of the servo motor can be effectively transmitted to the first gear 51 and the rotating rod 533. A steering gear 534 is keyed to the rotating rod 533. The steering gear 534 meshes with another steering gear 534. The lower rear steering gear 534 is keyed and fixedly connected to the lead screw 531. The lead screw 531 is rotatably mounted in the fixed seat 535 (the fixed seat 535 is fixedly connected to the drying chamber 1). The nut 532 is threadedly connected to the lead screw 531. The moving pressure roller 4 is fixedly connected to the nut 532. In this way, when the lead screw 531 rotates, the moving pressure roller 4 can move up and down.

[0060] Please see Figure 1 As shown, the heating element (not shown in the figure) provides the external temperature for the cast base film 8 inside the drying chamber 1. In this embodiment, the heating element can be an electric heating wire. The circulating air pipe 6 is fixedly connected to the upper end of the drying chamber 1, so that the air inlet and outlet of the circulating air pipe 6 are interconnected with the receiving cavity 11.

[0061] Please see Figure 4 The heat storage unit 7 shown is used to store / release heat. The heat storage unit includes an annular tube 71, which extends along the extension direction of the circulating air pipe 6. The outer wall of the annular tube 71 is fixedly connected to the inner wall of the circulating air pipe 6. A liquid storage chamber 711 is formed inside the annular tube 71 for holding water. Furthermore, a circulation pump (not shown in the figure) is connected to the annular tube 71 and the circulating air pipe 6, thereby forming an air circulation system within the drying chamber 1 and the annular tube 71.

[0062] The working principle of this invention is described below:

[0063] The operator opens the hinged door; then, the servo motor is started to adjust the downward movement of the pressure roller 4 so that the spacing of the pressing space is the preset spacing; then, the multi-roll cast base film 8 is loaded onto the preheating roller 2, and the free end of the multi-roll cast base film 8 is passed through the pressing space and out of the film outlet 12; finally, the hinged door is closed, and the preheating and heating elements of the preheating roller 2 are turned on.

[0064] The cast base film 8 on the preheating roller 2, under the combined heating effect of the preheating roller 2 and the heating element, causes the ambient temperature inside the receiving cavity 11 to reach the preset temperature. At this time, the temperature of the cast base film 8 itself rises rapidly. Considering that the ambient temperature of the cast base film 8 should not be too high, when the temperature inside the receiving cavity 11 reaches the preset temperature, the servo motor is turned on. The servo motor drives the rotating rod 533 to rotate, and the rotating rod 533 in turn drives the first gear 51 and the steering gear 534 to rotate synchronously. On the one hand, the rotation of the first gear 51 drives the second gear 52 to rotate, and the second gear 52 drives the preheating roller 2 to rotate, thereby realizing the unwinding process of the preheating roller 2; on the other hand, the rotating steering gear 534 drives the lead screw 531 to rotate, which can drive the nut 532 to move upward, thereby continuously increasing the pressing space.

[0065] As can be seen from the above process flow, the unwinding process of the cast base film 8 and the change in the pressing space are synchronized; that is, as the cast base film 8 is continuously unwound, the pressing space gradually increases. When multiple cast base films 8 are stretched to form holes, the quality of the holes in the diaphragm 9 is affected by the stretching force and the stretching temperature of the cast base films 8. The stretching force is the frictional force between adjacent cast base films 8. Generally speaking, the higher the stretching temperature of the cast base films 8, the smaller the required stretching force. Thus, the goal of uniformly forming holes in the diaphragm 9 can be achieved.

[0066] The stretching temperature of the cast base film 8 and the temperature of the receiving cavity 11 are different. Due to the poor thermal conductivity of the cast base film 8, when the servo motor is started and the heating element is turned off, the ambient temperature inside the receiving cavity 11 is at its highest, while the temperature of the free end of the cast base film 8 is at its lowest (due to the poor thermal conductivity of the cast base film 8). Therefore, it is necessary to ensure that the stretching force of the cast base film 8 is at its maximum at this time. As the cast base film 8 is continuously unwound, although the temperature inside the receiving cavity 11 is somewhat lost, the temperature of the cast base film 8 itself will continuously rise, and the pressing space will continuously increase. Therefore, the stretching force at this time, combined with the current temperature of the cast base film 8 and the initial stretching force and initial temperature of the cast base film 8, results in a diaphragm 9 with basically consistent hole sizes, meaning that the pores in the diaphragm 9 are relatively uniform.

[0067] To slow down the temperature loss within the receiving cavity 11, a circulating air path is formed within the receiving cavity 11 and the annular tube 71 before the heating element is turned off. The hot air in the receiving cavity 11 circulates within both the receiving cavity 11 and the annular tube 71. During this process, the water in the annular tube 71 continuously exchanges heat with the hot air, storing the high temperature within the water. Since the hot air is heated by being surrounded by the water in the annular tube 71, the water has a high heat absorption efficiency and can quickly accumulate a large amount of heat. When the heating element is turned off, the water, having accumulated a large amount of heat, continuously releases the heat as the temperature within the receiving cavity 11 decreases. However, the heat release occurs through the water enveloping the hot air, resulting in relatively little heat release. In summary, on the one hand, heat in the receiving cavity 11 flows out from the membrane outlet 12; on the other hand, heat in the receiving cavity 11 is replenished by the water in the annular tube 71. This constant inflow and outflow of heat within the receiving cavity 11 slows down the temperature drop. Ultimately, this ensures that the external heat of the cast base film 8 is reduced, but the heat of the cast base film 8 itself continues to rise, which in turn matches the ever-increasing pressing space (reduced tensile force), thereby achieving the purpose of uniformly forming pores in the diaphragm 9.

[0068] As can be seen from the above process, the tensile force has a crucial effect on the stretching and hole making of the diaphragm 9. In order to ensure that the change of tensile force is also slow, the transmission ratio of the first gear 51 and the second gear 52 is set to be less than 1, and the first gear 51 and the second gear 52 are arranged in a manner similar to planetary reduction gears. With the help of the lead screw 531 and nut 532 pair mechanism, the slow movement of the moving pressure roller 4 can be achieved.

[0069] Second aspect

[0070] This invention provides a dry-process diaphragm 9 processing method, utilizing a dry-process diaphragm stretching production line according to the first aspect, comprising the following steps:

[0071] S1: Installation of cast base film 8: A cast base film 8 is installed on a preheating roller 2.

[0072] S2: Synchronous preheating and heating of the cast base film 8: Turn on the heating element and preheating roller 2 so that the temperature in the receiving cavity 11 reaches the preset temperature.

[0073] S3: Pressing of multilayer cast base film 8: Pass the free end of multilayer cast base film 8 through the pressing space and start the power unit.

[0074] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A dry diaphragm stretching production line, characterized in that, include: The drying oven (1) is equipped with a receiving cavity (11). Multiple preheating rollers (2) are arranged inside the receiving cavity (11), and the preheating rollers (2) are used to transport the base film; The pressure roller (3) is fixedly installed inside the receiving cavity (11); The moving pressure roller (4) is slidably disposed in the receiving cavity (11), and a pressing space is formed between the moving pressure roller (4) and the fixed pressure roller (3) for pressing the multilayer base film; A driving element (5) is used to drive the moving pressure roller (4) closer to or further away from the fixed pressure roller (3) and to drive the preheating roller (2) to unwind; wherein the driving element (5) includes: Power components; The first gear (51) is driven to rotate by the power component. Multiple second gears (52) mesh with the first gear (51), and one of the second gears (52) is coaxially fixedly connected to one of the preheating rollers (2); The transmission component (53) is used to drive the first gear (51) and the dynamic pressure roller (4). The transmission component (53) includes: Lead screw (531), power component used to drive lead screw (531) to rotate; The nut (532) is threadedly connected to the lead screw (531), thereby forming a lead screw (531) nut (532) pair mechanism between the lead screw (531) and the nut (532), wherein the nut (532) is fixedly connected to the moving pressure roller (4); Rotating rod (533), multiple steering gears (534). The first gear (51) and the rotating rod (533) are fixedly connected by a connecting key. A steering gear (534) is keyed to the rotating rod (533). The steering gear (534) and another steering gear (534) mesh with each other. The steering gear (534) located at the rear and the lower steering rod (531) are fixedly connected by a key.

2. The dry diaphragm stretching production line according to claim 1, characterized in that: Multiple second gears (52) are arranged in a circumferential array with the axis of the first gear (51) as the center, and the transmission ratio between the second gear (52) and the first gear (51) is greater than 1.

3. A dry diaphragm stretching production line according to any one of claims 1-2, characterized in that, Also includes: A heating element is disposed within the receiving cavity (11).

4. The dry diaphragm stretching production line according to claim 3, characterized in that, Also includes: The circulating air pipe (6) is provided with an air inlet and an air outlet, and the air inlet and the air outlet are connected to the receiving cavity (11) of the drying oven (1); A circulation pump is installed inside the circulation air pipe (6); A heat storage unit (7) is disposed inside the circulating air pipe (6).

5. A dry diaphragm stretching production line according to claim 4, characterized in that, The heat storage component (7) include: A circular tube (71) extends along the extension direction of the circulating air pipe (6). The outer wall of the circular tube (71) is fixedly connected to the inner wall of the circulating air pipe (6). A liquid storage chamber (711) is provided inside the circular tube (71) for holding water.

6. The dry diaphragm stretching production line according to claim 1, characterized in that, The drying box (1) includes an inner box and an outer box. The receiving cavity (11) is opened in the inner box. The inner box is fixedly installed in the outer box. There is a gap between the inner box and the outer box. The gap is vacuumed.

7. A dry membrane processing method, characterized in that, The dry diaphragm stretching production line as described in claim 5 includes the following steps: S1: Installation of cast base film (8): A cast base film (8) is installed on a preheating roller (2). S2: Synchronous preheating and heating of the cast base film (8): turn on the heating element and the preheating roller (2) so that the temperature in the receiving cavity (11) reaches the preset temperature; S3: Pressing of the multilayer cast base film (8): Pass the free end of the multilayer cast base film (8) through the pressing space and turn on the power unit.

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