Casting machine and polypropylene film preparation method

Abstract

The invention relates to the technical field of casting polypropylene film preparation, in particular to a casting machine and a polypropylene film preparation method.The casting machine comprises a rack, a smelting system, an extruder, a control system, a cooling system, a traction assembly, a cutting assembly and a roll changing assembly; the traction assembly, the cutting assembly and the roll changing assembly are arranged in the casting machine, a polypropylene film subjected to tape casting is cut and wound after being pulled, and finally roll changing is conducted, so that the problems that a finished polypropylene film roll cannot be automatically replaced, and when a first layer of polypropylene film is wound by a roll core, the roll core cannot be replaced automatically are solved. The problems that due to the fact that a polypropylene film cannot be stably fixed to a roll core, the polypropylene film is loosened and cannot be rolled, the rolled polypropylene film is prone to wrinkling due to unstable rolling work, and the quality of a polypropylene film finished product is reduced are solved, the working efficiency of the casting machine is guaranteed, and the production cost is reduced. And meanwhile, the quality of the finished polypropylene film is ensured.

Description

Technical Field

[0001] This invention relates to the field of polypropylene film casting technology, specifically to a casting machine and a method for preparing polypropylene film. Background Technology

[0002] Cast film is a non-stretched, non-oriented flat extrusion film produced by melt casting and rapid cooling. Depending on the actual application requirements, various materials can be used to prepare cast film, including polypropylene film, polyethylene film, polyvinyl chloride film, polyimide film, and polyurethane film. All of the above cast films have excellent heat-sealing performance and light transmittance. Among them, polypropylene cast film has the best chemical stability. Therefore, polypropylene film is widely used in the packaging of food, pharmaceuticals, textiles, flowers, and daily necessities.

[0003] Polypropylene film is typically produced by a casting machine, which includes a melting system, an extrusion system, a cooling system, a tension control system, and a winding system. During the production process, the melting system melts polypropylene granules and then extrudes the molten polypropylene through the extrusion system to the cooling system. The cooling system then cools the extruded polypropylene film. Finally, the winding system winds the cooled polypropylene film onto a core. The tension control system primarily controls the tension of the polypropylene film between the extrusion and winding systems, preventing wrinkles due to insufficient tension or uneven thickness due to excessive tension. Once the polypropylene film on the core reaches the specified length, it needs to be cut in the width direction. Simultaneously, a new core is used to wind up the cut polypropylene film. Currently, the film roll replacement process is mostly manual, resulting in low automation, time-consuming, labor-intensive, and inefficient operations.

[0004] To address the aforementioned issues, existing technologies offer several solutions. One such solution involves incorporating a rotating mechanism within the winding system. This mechanism comprises two symmetrical turntables, each with several symmetrical slots on adjacent surfaces. A core is placed within each slot, and rotating rods at both ends of the core engage with it. Motors are mounted on these rotating rods, and the turntables also have multiple push rods. When the polypropylene film wound onto the core reaches the specified length, the turntable rotates, allowing empty cores from subsequent stations to replace those from the previous station and continue the winding process. Fully wound cores are ejected by the push rods, and the cores on the slide plate roll in an inclined direction, falling into the slots on the turntable, thus achieving automatic roll changing. However, this solution overlooks the issue that during the winding of the first layer of polypropylene film, the film cannot be stably fixed to the core, leading to detachment and preventing successful winding. Furthermore, unstable winding can cause wrinkles in the wound polypropylene film, reducing the quality of the finished product.

[0005] Therefore, a casting machine and a method for preparing polypropylene film are proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a casting machine and a method for preparing polypropylene film, in order to solve the problems that the finished polypropylene film roll cannot be automatically replaced, resulting in a decrease in production efficiency, and that when the core is winding the first layer of polypropylene film, the polypropylene film cannot be stably fixed on the core, causing the polypropylene film to loosen and preventing the winding work from being completed. Furthermore, the unstable winding work easily leads to wrinkles in the wound polypropylene film, reducing the quality of the finished polypropylene film.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A casting machine includes a frame, a melting system, an extruder, a control system, a cooling system, traction rollers, a winding change assembly, and a take-up motor. The extruder is fixedly mounted on the frame and located at the rear of the frame. The extruder has a feed inlet and a discharge outlet. The melting system is fitted onto the extruder. The cooling system, traction rollers, winding change assembly, and take-up motor are all located at the front end of the discharge outlet and are arranged sequentially forward and connected to the frame. The control system controls the operation of the melting system, extruder, cooling system, traction rollers, winding change assembly, and take-up motor. The winding change assembly is mounted on the frame, and the take-up motor is mounted on the winding change assembly. A core is also mounted on the winding change assembly. Mounted on a take-up motor, and with an adsorption assembly on the roll core, a fixed traction plate is installed between the traction roller and the roll changing assembly. The fixed traction plate is connected to the frame, and a traction assembly and a cutting assembly are mounted on the fixed traction plate. The traction assembly is used to pull the polypropylene film guided by the traction roller onto the roll core. When the control system detects that the polypropylene film on the roll core has reached a specified length, the cutting assembly cuts the completed polypropylene film into segments from the fixed traction plate. At the same time, the roll changing assembly removes the completed roll core from the take-up motor and replaces it with a new roll core. The adsorption assembly adsorbs the polypropylene film in the fixed traction plate onto the replaced roll core.

[0009] The polypropylene resin enters the extruder through the inlet and outlet. The extruder conveys the polypropylene resin to the melting system, where it is heated and melted. The extruder then extrudes the melted polypropylene resin into a polypropylene film. The polypropylene film is cooled by a cooling system. The traction roller pulls the polypropylene film to the rear end of the traction assembly, which in turn pulls it into the winding assembly. The control system controls the winding motor to rotate, which drives the core to rotate and wind up the polypropylene film. The control system detects when the polypropylene film on the core reaches a specified length. The cutting component cuts the wound polypropylene film into segments from the traction component. Simultaneously, the roll-changing component removes the wound core from the winding motor and replaces it with a new core. This solves the problems of the finished polypropylene film rolls not being automatically replaced, and the polypropylene film not being stably fixed to the core during the winding of the first layer, causing it to loosen and preventing winding. Unstable winding also easily leads to wrinkles in the wound polypropylene film, reducing the quality of the finished polypropylene film. This ensures the working efficiency of the casting machine while also guaranteeing the quality of the finished polypropylene film.

[0010] Optionally, the traction component can be a belt, chain, or gear. All three types of traction components can transmit and guide the movement of the components. The belt needs to be rotated by a motor to guide the movement of the polypropylene film. During the transmission process, the surface of the belt comes into contact with the surface of the polypropylene film, which can easily scratch the outer surface of the polypropylene film and cause quality problems. The chain and gear have the same problems as the belt. Therefore, none of the above three types of traction components are preferred solutions of the present invention.

[0011] Preferably, the traction assembly includes a fixed traction plate, a movable traction plate, and an air pump. The air pump is mounted on the frame and electrically connected to the control system. The fixed traction plate is connected to the frame. The traction roller includes an upper roller and a lower roller, which are on the same vertical plane. The minimum gap between the upper and lower rollers is equal to the thickness of the polypropylene film. The rear end of the movable traction plate is hinged to the front end of the fixed traction plate. A corrugated pipe is installed at the hinge point between the fixed and movable traction plates. The rear end of the corrugated pipe is connected to the fixed traction plate. The front end of the guide plate is connected to the front end of the corrugated pipe and the rear end of the movable traction plate. Traction air passages are provided in the fixed traction plate and the movable traction plate. One end of the traction air passage is connected to the front end of the traction roller and the other end is connected to the front end of the movable traction plate. The width of the traction air passage is greater than the thickness of the polypropylene film. The rear end of the fixed traction plate is slidably connected to the front end of the traction roller. A driving air passage is provided on the upper surface of the fixed traction plate. One end of the driving air passage is connected to the traction air passage and the other end is connected to the air pump through an air pipe.

[0012] The traction roller pulls the polypropylene film to the rear end of the fixed traction plate. The air pump delivers high-pressure gas to the traction air passage through an air pipe. As the high-pressure gas flows through the traction air passage, a negative pressure is generated at the rear end of the fixed traction plate, thereby adsorbing the polypropylene film at the front end of the traction roller and drawing it into the traction air passage. The polypropylene film is then pulled onto the winding core in the winding state through the traction air passage. This solves the problem of polypropylene film loosening and being unable to be wound, and the unstable winding operation is prone to causing wrinkles in the wound polypropylene film, reducing the quality of the finished polypropylene film. This ensures the working efficiency of the casting machine and also guarantees the quality of the finished polypropylene film.

[0013] Optionally, the cutting assembly can be a laser cutting head, a plasma cutting head, or a water jet cutting head. All three types of cutting assemblies can cut polypropylene films into segments. The laser cutting head uses a laser beam for cutting, which generates heat during cutting, causing the polypropylene film to shrink and wrinkle. The plasma cutting head uses high-temperature plasma for cutting, which also causes the above problems. Although the water jet cutting head avoids the above problems, the accumulation of water can also cause quality problems in the finished polypropylene film. Therefore, none of the above three cutting assemblies are preferred solutions of the present invention.

[0014] Preferably, the cutting assembly includes a cutting cylinder, a piston rod, a return spring, and a cutter. The cylinder is mounted on the upper surface of the fixed traction plate. A first air hole is opened on the upper side of the cylinder, and the first air hole is connected to an air pump through an air pipe. The piston rod is slidably connected inside the cutting cylinder. The return spring is installed inside the cutting cylinder, and its two ends are respectively connected to the cutting cylinder and the piston rod. The cutter is connected to the lower end of the piston rod. A cutter groove is opened on the upper side of the fixed traction plate, and the cutter is slidably connected inside the cutter groove, with all four blade surfaces of the cutter fitting against the inner wall of the cutter groove. The driving air passage is located between the cutting assembly and the traction roller. When the control system detects that the polypropylene film on the core has reached the specified length, the control system controls the air pump to deliver high-pressure gas to the cutting cylinder. The air pressure inside the cutting cylinder gradually increases. When the air pressure inside the cutting cylinder is greater than the return pressure of the return spring, the piston rod is pressed and moves towards the fixed traction plate. The cutter is pushed by the piston rod and moves towards the bottom of the drive air passage. When the blade of the cutter comes into contact with the polypropylene film, it will cut the polypropylene film, preparing for the subsequent roll changing process.

[0015] The driving air passage is located between the cutting assembly and the traction roller. The four sides of the cutter are all in contact with the inner wall of the cutter groove. This prevents high-pressure gas from flowing out of the fixed traction plate through the cutter groove when the traction air passage is pulling the polypropylene film. This would cause the polypropylene film to deviate during the traction process, affecting the working efficiency of the casting machine. Furthermore, the deviated polypropylene film may also cause the polypropylene film to stack and block, affecting the quality of the finished polypropylene film. This ensures the working efficiency of the casting machine and also ensures the quality of the finished polypropylene film.

[0016] Optionally, the roll changing assembly can be manual roll changing or semi-automatic roll changing. Both types of roll changing assemblies can change the rolled polypropylene film after it has been wound up. Manual roll changing is done manually, which can meet the roll changing requirements, but the efficiency of roll changing is unstable and increases labor costs. Semi-automatic roll changing improves the efficiency of roll changing, but the production cost also increases. Therefore, neither of the above two roll changing methods is considered a preferred solution of the present invention.

[0017] Preferably, the winding assembly includes a tilting shaft, tilting rods, a tilting motor, a pneumatic-electric rotary joint, a spline, a first winding piston, a second winding piston, a vacuum pump, a loading platform, and a unloading platform. The tilting shaft is rotatably connected to the frame and is located in front of the movable traction plate. Two tilting rods are fixedly installed on the tilting shaft, with the connection points between the two tilting rods and the tilting shaft located in the middle of the tilting rods. The two tilting rods are parallel to each other, and the distance between the two rods is equal to the length of the core. The tilting motor is coaxially connected to the tilting shaft and electrically connected to the control system. There are two winding motors, which are installed at both ends of the left tilting rod. The spline is fixedly installed on the rotating shaft of the winding motor, and the winding motor is electrically connected to the control system via wires. Both ends of the two flipping rods are provided with piston chambers, and both ends of the two flipping rods are provided with second air holes. The two ends of the multiple second air holes are respectively connected to the piston chambers and the air pump. There are two first-order changing pistons, which are slidably connected in the left piston chamber. There are two second-order changing pistons, which are slidably connected in the right piston chamber. Both the first-order and second-order changing pistons are provided with spline grooves, which are slidably connected in the spline grooves. The multiple piston chambers are connected to the air pump through air pipes. The loading platform and unloading platform are fixedly installed on the frame. The loading platform is located behind the flipping rod, and the unloading platform is located in front of the flipping rod. The front ends of the loading platform and the unloading platform are lower than the rear ends.

[0018] After the cutter cuts the polypropylene film, the control system controls the rotating motor to rotate, which drives the rotating rods to rotate. When the rotating rods are aligned with the rear end of the unloading platform and the front end of the loading platform, the control system controls the vacuum pump to draw out the gas from the piston chambers at the front ends of the two rotating rods, creating a negative pressure in the piston chambers. The first and second rewinding pistons simultaneously retract towards the two rotating rods, and the fully wound core rolls from the rear side of the unloading platform to the front side of the loading platform. At the same time, the control system controls the air pump to pressurize the piston chambers at the rear ends of the two rotating rods, increasing the pressure in the piston chambers. The first and second rewinding pistons at the rear end of the flipping rod simultaneously eject towards the bisecting plane of the two flipping rods. The core of the feeding platform will be clamped by the first and second rewinding pistons. After the core of the feeding platform is clamped by the first and second rewinding pistons, the control system controls the flipping motor to rotate. The flipping motor drives the flipping rod to flip. When the flipping angle of the flipping rod is aligned with the front end of the movable traction plate, the winding motor drives the core to wind up. This solves the problem of the finished polypropylene film rolls not being able to be automatically replaced, which leads to a decrease in production efficiency and ensures the working efficiency of the casting machine.

[0019] Preferably, the adsorption assembly includes air slits and adsorption channels. The core also has multiple air slits, which are evenly distributed circumferentially on the outer surface of the core and are parallel to the central axis of the core. The left and right ends of the multiple air slits are not connected to the left and right ends of the core. The second rewinding piston is also provided with adsorption channels. When the core is rewound, one end of the adsorption channel is connected to the inside of the core, and the other end is connected to the air pump through an air pipe. The ends of the multiple air slits near the central axis of the core are connected to the adsorption channels, and the ends of the multiple air slits away from the central axis of the core are connected to the outside of the core.

[0020] When the flipping rod is aligned with the front end of the movable traction plate, the vacuum pump starts, creating negative pressure between the adsorption air passage and the inside of the core. The air gap will generate suction. When the polypropylene film is pulled to the front end of the movable traction plate, the air gap will adsorb the polypropylene film onto the outer surface of the core. Then, the winding motor rotates to drive the core to rotate, completing the winding process. This solves the problem that when winding the first layer of polypropylene film, the polypropylene film cannot be stably fixed to the core, causing it to loosen and preventing winding. Furthermore, unstable winding can easily lead to wrinkles in the wound polypropylene film, reducing the quality of the finished polypropylene film. This ensures the working efficiency of the casting machine while also guaranteeing the quality of the finished polypropylene film.

[0021] Preferably, the movable traction plate includes a top plate and a bottom plate. The traction air duct is located between the top plate and the bottom plate. The top plate is located above the bottom plate. A first roller and a second roller are respectively rotatably connected to the front ends of the top plate and the bottom plate. The center distance from the turning shaft to the winding motor is A, the center distance from the turning shaft to the first roller is B, and the center distance from the turning shaft to the second roller is C. B < A < C. When the core is being wound, both the first roller and the second roller are in rolling connection with the outer surface of the core.

[0022] When the winding motor winds the polypropylene film, the first roller and the second roller will be in rolling connection with the surface of the polypropylene film, and the pressure of the movable traction plate is applied to the polypropylene film, avoiding the generation of wrinkles during the winding process of the polypropylene film, solving the quality problems of the finished polypropylene film caused by wrinkles, and ensuring the quality of the finished polypropylene film.

[0023] Preferably, a limiting block is fixedly installed on the frame. The limiting block is installed below the movable traction plate. When the upper end surface of the limiting block is in contact with the lower end surface of the movable traction plate, the included angle between the bottom of the movable traction plate and the fixed traction plate is E, and the value range of E is 90° < E < 180°.

[0024] When the turning rod needs to change the roll, the movable traction plate will swing downward, and the lower end surface of the movable traction plate will contact the upper end surface of the limiting block. At this time, the included angle between the bottom of the movable traction plate and the fixed traction plate is E, and the value range of E is 90° < E < 180°. When E ≤ 90°, the polypropylene film will be blocked at the hinge joint of the movable traction plate and the fixed traction plate. When E ≥ 180°, the rotation path of the turning rod will be interfered. To avoid the above problems, the value range of E is 90° < E < 180°, ensuring the smooth movement of the polypropylene film in the traction air duct, ensuring the working efficiency of the casting machine, and at the same time ensuring the quality of the finished polypropylene film.

[0025] The present invention also provides a method for preparing a polypropylene film using the above-mentioned casting machine for polypropylene film production, including the following steps:

[0026] S1: Raw material pretreatment: Prepare polypropylene resin and additives, and put the polypropylene resin and additives into a mixer for pretreatment;

[0027] S2: Extrusion production: Feed the pretreated polypropylene resin into the extruder from the feed port, heat and melt the polypropylene resin through the melting system, and then extrude it into a primary extrudate through the extruder;

[0028] S3: Casting and Cooling: The initial extruded material is introduced into the cooling system and traction rollers. In this step, the thickness of the polypropylene film can be controlled by adjusting the spacing of the traction rollers. After being stretched by the traction rollers, the polypropylene film needs to be cooled to an appropriate temperature by the cooling system to maintain its shape and mechanical properties.

[0029] S4: Winding: The stretched and cooled polypropylene film is pulled to the winding motor by the traction assembly and wound onto the core by the winding motor.

[0030] S5: Cutting: When the polypropylene film on the core is wound to a specified length, the polypropylene film is cut and shaped by the cutting component;

[0031] S6: Roll changing: The cut and shaped polypropylene film is rolled up through the roll changing assembly. After the roll changing is completed, repeat the work from S4 to S6.

[0032] S7: Packaging and Warehousing: Package the rewound polypropylene film and store the packaged polypropylene film in the warehouse.

[0033] S8: Shutdown and Maintenance: After production is completed, shut down the casting machine, perform routine maintenance on the casting machine, and replace worn parts.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. This invention solves the problems of unautomatic replacement of finished polypropylene film rolls, the inability of the polypropylene film to be stably fixed on the core during the first layer of polypropylene film winding, and the instability of the winding motor to cause wrinkles in the wound polypropylene film, thus reducing the quality of the finished polypropylene film. The invention also addresses the issues of inconsistent efficiency of the casting machine and the quality of the finished polypropylene film. Specifically, the traction component pulls the polypropylene film guided by traction rollers onto the core, while the winding motor drives the core to wind up. When the control system detects that the polypropylene film on the core has reached a specified length, the cutting component cuts the wound polypropylene film into segments from the traction component. Simultaneously, the winding component removes the wound core from the winding motor and replaces it with a new core.

[0036] 2. This invention, by setting an air gap on the core, when the flipping rod is aligned with the front end of the movable traction plate, the vacuum pump is activated, and a negative pressure is generated between the adsorption air channel and the inside of the core. The air gap will generate suction. When the polypropylene film is pulled to the front end of the movable traction plate, the air gap will adsorb the polypropylene film onto the outer surface of the core. Then, the winding motor rotates to drive the core to rotate, completing the winding process. This solves the problem that when the core is winding the first layer of polypropylene film, the polypropylene film cannot be stably fixed on the core, causing the polypropylene film to loosen and preventing winding. Furthermore, unstable winding can easily cause wrinkles in the wound polypropylene film, reducing the quality of the finished polypropylene film. This invention ensures the working efficiency of the casting machine and also guarantees the quality of the finished polypropylene film.

[0037] 3. This invention features a first roller and a second roller rotatably connected to the front ends of the top and bottom plates, respectively. When the flipping rod is aligned with the front end of the movable traction plate, both the first and second rollers roll on the outer surface of the core. When the winding motor winds up the polypropylene film, the first and second rollers roll on the surface of the polypropylene film, and the pressure of the movable traction plate is applied to the polypropylene film. This prevents wrinkles from forming on the polypropylene film during winding, solves the quality problems caused by wrinkles in the finished polypropylene film, and ensures the quality of the finished polypropylene film. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the casting machine of the present invention;

[0039] Figure 2 This is a top view of the casting machine of the present invention in the state of starting to rewind;

[0040] Figure 3 for Figure 2 AA section view;

[0041] Figure 4 This is a state diagram of the casting machine after winding is completed according to the present invention;

[0042] Figure 5 This is a state diagram of the casting machine during the roll changing process of the present invention;

[0043] Figure 6 This is a state diagram of the flipping component of the present invention when it grips the core;

[0044] Figure 7 This is a diagram showing the state of the flipping component of the present invention when the winding core is released;

[0045] Figure 8 This is a process flow diagram of the polypropylene film preparation method of the present invention.

[0046] In the diagram: 1. Frame; 101. Polypropylene film; 102. Core; 103. Air gap; 2. Extruder; 3. Melting system; 4. Cooling system; 5. Traction roller; 6. Traction assembly; 601. Fixed traction plate; 602. Movable traction plate; 603. Roller No. 1; 604. Roller No. 2; 605. Limiting block; 606. Traction air passage; 607. Corrugated pipe; 608. Drive air passage; 7. Cutting assembly; 701. Cutting 702. Cylinder; 703. Piston rod; 704. Return spring; 705. No. 1 air hole; 8. Roll changing assembly; 806. Tilting rod; 807. Tilting shaft; 808. Pneumatic-electric rotary joint; 809. Loading platform; 8000. Unloading platform; 801. No. 1 roll changing piston; 802. No. 2 roll changing piston; 803. Rewinding motor; 804. Spline; 815. No. 2 air hole; 816. Adsorption air channel; 9. Control system; 10. Adsorption assembly. Detailed Implementation

[0047] Please see Figures 1 to 8 This invention provides a casting machine and a method for preparing polypropylene film, the technical solution of which is as follows:

[0048] A casting machine, please refer to Figure 1 and Figure 2 The extruder includes a frame 1, a melting system 3, an extruder 2, a control system 9, a cooling system 4, a traction roller 5, a traction assembly 6, a cutting assembly 7, an adsorption assembly 10, and a coil changing assembly 8. The extruder 2 is fixedly mounted on the frame 1 and located at the rear of the frame 1. The extruder 2 has a feed inlet and a discharge outlet. The melting system 3 is mounted on the extruder 2. The cooling system 4, traction roller 5, traction assembly 6, and coil changing assembly 8 are all located at the front end of the discharge outlet and are arranged sequentially forward and connected to the frame 1. The cutting assembly 7 is mounted on the traction assembly 6, and the adsorption assembly 10 is mounted on the coil changing assembly 8. The control system 9 is used to control the melting system 3, the extruder 2, the cooling system 4, the traction roller 5, and the traction assembly 6. The operation of the cutting assembly 7, the adsorption assembly 10, and the roll changing assembly 8 is as follows: A traction assembly 6 is installed between the traction roller 5 and the roll changing assembly 8. The traction assembly 6 is used to pull the polypropylene film 101 guided by the traction roller 5 to the roll changing assembly 8. The roll changing assembly 8 is installed on the frame 1 and a winding motor 808 is installed on it. The roll changing assembly 8 is located in front of the traction assembly 6. A core 102 is also installed on the roll changing assembly 8. The core 102 is a tube with two connected ends and is installed on the winding motor 808. The cutting assembly 7 is installed on the upper side of the traction assembly 6. The traction assembly 6, the cutting assembly 7, the roll changing assembly 8, and the winding motor 808 are all electrically connected to the control system 9.

[0049] For further details, please refer to Figure 1 , Figures 3 to 5, the traction assembly 6 includes a fixed traction plate 601, a movable traction plate 602 and an air pump (not shown in the figure). The air pump is installed on the frame 1 and is electrically connected to the control system 9. The fixed traction plate 601 is connected to the frame 1. The traction roller 5 includes an upper roller and a lower roller. The upper roller and the lower roller are in the same vertical plane, and the minimum gap between the upper roller and the lower roller is equal to the thickness of the polypropylene film 101. The rear end of the movable traction plate 602 is hinged to the front end of the fixed traction plate 601. A bellows 607 is installed at the hinge between the fixed traction plate 601 and the movable traction plate 602. The rear end of the bellows 607 is connected to the front end of the fixed traction plate 601, and the front end of the bellows 607 is connected to the rear end of the movable traction plate 602. Traction air channels 606 are provided in the fixed traction plate 601 and the movable traction plate 602. One end of the traction air channel 606 is connected to the front end of the traction roller 5, and the other end is connected to the front end of the movable traction plate 602. The width of the traction air channel 606 is greater than the thickness of the polypropylene film 101. The rear end of the fixed traction plate 601 is slidably connected to the front end of the traction roller 5. A driving air channel 608 is provided on the upper end surface of the fixed traction plate 601. One end of the driving air channel 608 is connected to the traction air channel 606, and the other end is connected to the air pump through a trachea (not shown in the figure). The movable traction plate 602 includes a top plate and a bottom plate. The traction air channel 606 is located between the top plate and the bottom plate. The top plate is located above the bottom plate. A first roller 603 and a second roller 604 are respectively rotatably connected to the front ends of the top plate and the bottom plate. The center distance from the turning shaft 802 to the winding motor 808 is A, the center distance from the turning shaft 802 to the first roller 603 is B, and the center distance from the turning shaft 802 to the second roller 604 is C, and B < A < C. When the core 102 is being wound, both the first roller 603 and the second roller 604 are in rolling connection with the outer surface of the core 102. A limiting block 605 is fixedly installed on the frame 1. The limiting block 605 is installed below the movable traction plate 602. When the upper end surface of the limiting block 605 contacts the lower end surface of the movable traction plate 602, the included angle between the bottom of the movable traction plate 602 and the fixed traction plate 601 is 169°.

[0050] Further, please refer to Figure 1 , Figures 3 to 5 , the cutting assembly 7 includes a cutting cylinder 701, a piston rod 702, a return spring 703 and a cutter. The cylinder is installed on the upper end surface of the fixed traction plate 601. A first air hole 704 is provided on the upper side of the cylinder. The first air hole 704 is connected to the air pump through a trachea. The piston rod 702 is slidably connected in the cutting cylinder 701. The return spring 703 is installed in the cutting cylinder 701. Both ends of the return spring 703 are respectively connected to the cutting cylinder 701 and the piston rod 702. The cutter is connected to the lower end of the piston rod 702. A knife groove is provided on the upper side of the fixed traction plate 601. The cutter is slidably connected in the knife groove, and the inner walls of the knife groove are in contact with the four surrounding knife surfaces of the cutter. The driving air channel 608 is located between the cutting assembly 7 and the traction roller 5.

[0051] For further details, please refer to Figure 1 , Figure 6 and Figure 7 The roll changing assembly 8 includes a tilting shaft 802, tilting rods 801, a tilting motor (not shown), a pneumatic-electric rotary joint 803, a spline 809, a first roll changing piston 806, a second roll changing piston 807, a vacuum pump (not shown), a loading platform 804, and a unloading platform 805. The tilting shaft 802 is rotatably connected to the frame 1 and is located in front of the movable traction plate 602. Two tilting rods 801 are fixedly installed on the tilting shaft 802. The connection between the two tilting rods 801 and the tilting shaft 802 is located in the middle of the tilting rods 801. The two tilting rods 801 are parallel to each other, and the distance between the two rods is equal to the length of the core 102. The tilting motor is coaxially connected to the tilting shaft 802 and is electrically connected to the control system 9. There are two winding motors 808, which are installed at both ends of the left tilting rod 801. The spline 809 is fixedly installed on the rotating shaft of the winding motor 808. The winding motor 808 is connected to the control system 9. The system is electrically connected to the control system 9 via wires. Piston chambers are provided at both ends of the two flipping rods 801, and second air holes 810 are provided at both ends of the two flipping rods 801. The ends of the multiple second air holes 810 are connected to the piston chambers and the air pump, respectively. There are two first-order changing pistons 806, which are slidably connected in the left piston chamber. There are also two second-order changing pistons 807, which are slidably connected in the left piston chamber. Inside the piston chamber on the right, both the No. 1 changing piston 806 and the No. 2 changing piston 807 are provided with spline 809 grooves. The spline 809 is slidably connected in the spline 809 groove. Multiple piston chambers are connected to the air pump through air pipes. The loading platform 804 and the unloading platform 805 are both fixedly installed on the frame 1. The loading platform 804 is located behind the tilting rod 801, and the unloading platform 805 is located in front of the tilting rod 801. The front ends of the loading platform 804 and the unloading platform 805 are lower than the rear ends.

[0052] For further details, please refer to [link / reference]. Figure 1 , Figures 3 to 5 The adsorption assembly 10 includes air slits 103 and adsorption air channels 811. Multiple air slits 103 are also provided on the core 102. The multiple air slits 103 are evenly distributed on the outer surface of the core 102 and are parallel to the central axis of the core 102. The left and right ends of the multiple air slits 103 are not connected to the left and right ends of the core 102. The second rewinding piston 807 is also provided with adsorption air channels 811. When the core 102 is wound up, one end of the adsorption air channel 811 is connected to the inside of the core 102, and the other end is connected to the air pump through an air pipe. The ends of the multiple air slits 103 near the central axis of the core 102 are connected to the adsorption air channels 811, and the ends of the multiple air slits 103 away from the central axis of the core 102 are connected to the outside of the core 102.

[0053] During operation, polypropylene resin enters the extruder 2 through the inlet and outlet. The extruder 2 conveys the polypropylene resin to the melting system 3, where it is heated and melted. The extruder 2 then extrudes the melted polypropylene resin into a polypropylene film 101. The polypropylene film 101 is cooled by the cooling system 4. The traction roller 5 pulls the polypropylene film 101 to the rear end of the fixed traction plate 601. The control system 9 controls the air pump to introduce high-pressure gas through the air pipe into the traction air passage 606 via the driving air passage 608. The high-pressure gas flows from the fixed traction plate 601 to the movable traction plate 602 within the traction air passage 606. At this time, the rear end of the fixed traction plate 601 is under negative pressure. The polypropylene film 101, pulled by the traction roller 5, enters the traction air passage 606 under this negative pressure. When the polypropylene film 101 reaches the position of the driving air passage 608, the polypropylene film 101... Under the influence of the high-pressure gas flow, the front end of the front traction airway 606 moves, and the polypropylene film 101 reaches the front end of the movable traction plate 602 under the traction of the high-pressure gas. The polypropylene film 101 contacts the surface of the core 102. At this time, the control system 9 controls the vacuum pump to start. The vacuum pump draws negative pressure inside the core 102 through the adsorption airway 811 connected by the air pipe. The ends of the multiple air gaps 103 away from the central axis of the core 102 will generate suction. Under the action of the negative pressure suction at the air gaps 103, the polypropylene film 101 is adsorbed onto the outer surface of the core 102. The control system 9 controls the winding motor 808 to rotate, which drives the core 102 to rotate and winds up the polypropylene film 101 adsorbed on the core 102. At this time, the first roller 603 and the second roller 604 are both rolled and connected to the outer surface of the core 102. The pressure of the movable traction plate 602 is applied to the polypropylene film 101.

[0054] Furthermore, when the control system 9 detects that the polypropylene film 101 on the core 102 has reached the specified length, the torque detector in the control system 9 detects that the polypropylene film 101 on the core 102 has reached the set weight. The control system controls the air pump to deliver high-pressure gas into the cutting cylinder 701. The air pressure inside the cutting cylinder 701 gradually increases. When the air pressure inside the cutting cylinder 701 is greater than the return pressure of the return spring 703, the piston rod 702 is pressed and moves towards the fixed traction plate 601. The cutter is pushed by the piston rod 702 and moves towards the bottom surface of the drive air passage 608. When the blade of the cutter contacts the polypropylene film 101, it will cut the polypropylene film 101. After the cutter cuts the polypropylene film 101, the control system 9 controls the flipping motor to rotate. The flipping motor drives the flipping rod 801 to flip. When the flipping angle of the flipping rod 801 is aligned with the rear end of the unloading table 805 and the front end of the loading table 804, the control system 9 controls the flipping motor to rotate. Normally, the No. 1 changing piston 806 and No. 2 changing piston 807 at the front end of the tilting rod 801 are controlled by an air pump to retract simultaneously towards the two tilting rods 801. The fully wound core 102 rolls from the rear side of the unloading platform 805 to the front side of the unloading platform 805. At the same time, the No. 1 changing piston 806 and No. 2 changing piston 807 at the rear end of the tilting rod 801 pop out towards the bisecting surface of the two tilting rods 801. The core 102 on the loading platform 804 will be clamped by the first changing piston 806 and the second changing piston 807. After the core 102 on the loading platform 804 is clamped by the first changing piston 806 and the second changing piston 807, the control system 9 controls the rotation motor to rotate. The rotation motor drives the rotation rod 801 to rotate. When the rotation angle of the rotation rod 801 is aligned with the front end of the movable traction plate 602, the winding motor 808 drives the core 102 to repeat the winding operation.

[0055] This invention also provides a method for preparing polypropylene film 101 using the above-mentioned casting machine. Please refer to [the above-mentioned method]. Figure 8 The production process includes the following steps:

[0056] S1: Raw material pretreatment: Prepare polypropylene resin and additives, and put the polypropylene resin and additives into a mixer for pretreatment.

[0057] S2: Extrusion production: The pretreated polypropylene resin is fed into the extruder 2 through the feed port, and the polypropylene resin is heated and melted through the melting system 3. Then it is extruded into a primary extruded product through the extruder 2.

[0058] S3: Casting and Cooling: The initial extruded material is introduced into the cooling system 4 and the traction roller 5. In this step, the thickness of the polypropylene film 101 can be controlled by adjusting the spacing of the traction roller 5. After the polypropylene film 101 is stretched by the traction roller 5, it needs to be cooled to an appropriate temperature by the cooling system 4 in order to maintain its shape and mechanical properties.

[0059] S4: Winding: The stretched and cooled polypropylene film 101 is pulled to the winding motor 808 by the traction assembly and wound onto the core 102 by the winding motor 808.

[0060] S5: Cutting: When the polypropylene film 101 on the core 102 is wound to a specified length, the polypropylene film 101 is cut and shaped by the cutting component 7.

[0061] S6: Rewinding: The cut and shaped polypropylene film 101 is rewound through the rewinding assembly 8. After the rewinding is completed, the work from S4 to S6 is repeated.

[0062] S7: Packaging and Warehousing: Pack the polypropylene film 101 after it has been rolled up, and store the packaged polypropylene film 101 in the warehouse.

[0063] S8: Shutdown and Maintenance: After production is completed, shut down the casting machine, perform routine maintenance on the casting machine, and replace worn parts.

[0064] The specific embodiment of the present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the embodiments described above. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and ideas of the present invention should still fall within the protection scope of the present invention.

Claims

1. A casting machine, comprising a frame (1), a melting system (3), an extruder (2), a control system (9), a cooling system (4), and a traction roller (5), characterized in that, It also includes a roll changing assembly (8) and a take-up motor (808). The roll changing assembly (8) is mounted on the frame (1), and the take-up motor (808) is mounted on the roll changing assembly (8). A core (102) is also mounted on the roll changing assembly (8). The core (102) is mounted on the take-up motor (808), and an adsorption assembly (10) is provided on the core (102). A fixed traction plate (601) is installed between the traction roller (5) and the roll changing assembly (8). The fixed traction plate (601) is connected to the frame (1). A traction assembly (6) and a cutting assembly (7) are mounted on the fixed traction plate (601). The traction assembly (6) is used for... When the polypropylene film (101) guided by the traction roller (5) is pulled onto the core (102), and the control system (9) detects that the polypropylene film (101) on the core (102) has reached the specified length, the cutting component (7) cuts the wound polypropylene film (101) into segments from the fixed traction plate (601). At the same time, the roll changing component (8) removes the wound core (102) from the winding motor (808) and replaces it with a new core (102). The adsorption component (10) adsorbs the polypropylene film (101) in the fixed traction plate (601) onto the replaced core (102).

2. The casting machine according to claim 1, characterized in that: The traction assembly includes a movable traction plate (602), a corrugated pipe (607), and an air pump. The air pump is mounted on the frame (1) and is electrically connected to the control system. The fixed traction plate (601) is connected to the frame (1). The traction roller (5) includes an upper roller and a lower roller. The axes of the upper roller and the lower roller are on the same vertical plane, and the minimum gap between the upper roller and the lower roller is equal to the thickness of the polypropylene film (101). The rear end of the movable traction plate (602) is hinged to the front end of the fixed traction plate (601). A corrugated pipe (607) is provided between the fixed traction plate (601) and the movable traction plate (602). (607) has two ends connected to the front end of the fixed traction plate (601) and the rear end of the movable traction plate (602), respectively. Traction air passages (606) are provided in the fixed traction plate (601) and the movable traction plate (602). The width of the traction air passage (606) is greater than the thickness of the polypropylene film (101). The fixed traction plate (601) is slidably connected to the traction roller (5). A driving air passage (608) is provided on the upper surface of the fixed traction plate (601). The driving air passage (608) is inclined forward. One end of the driving air passage (608) is connected to the traction air passage (606), and the other end is connected to the air pump through an air pipe.

3. A casting machine according to claim 2, characterized in that: The cutting assembly includes a cutting cylinder (701), a piston rod (702), a return spring (703), and a cutter. The cutting cylinder is mounted on the upper surface of the fixed traction plate (601). A first air hole (704) is opened on the upper side of the cutting cylinder. The first air hole (704) is connected to an air pump through an air pipe. The piston rod (702) is slidably connected inside the cutting cylinder (701). The return spring (703) is sleeved on the lower side of the piston rod (702). The two ends of the return spring (703) are respectively connected to the cutting cylinder (701) and the piston rod (702). The cutter is connected to the lower end of the piston rod (702). A cutter groove is opened on the upper side of the fixed traction plate (601). The cutter is slidably connected in the cutter groove, and the four sides of the cutter are all in contact with the inner wall of the cutter groove. The driving air passage (608) is located between the cutting assembly and the traction roller (5).

4. A casting machine according to claim 1, characterized in that: The roll changing assembly includes a tilting shaft (802), tilting rods (801), a tilting motor, a spline (809), a first roll changing piston (806), a second roll changing piston (807), a vacuum pump, a loading platform (804), and a unloading platform (805). The tilting shaft (802) is rotatably connected to the frame (1). The tilting shaft (802) is located in front of the movable traction plate (602). Two tilting rods (801) are fixedly installed on the tilting shaft (802). The two tilting rods (801) are connected to the tilting shaft (802). The rotating shaft (801) is located in the middle of the rotating rod (801). The two rotating rods (801) are parallel to each other, and the distance between the two rods is equal to the length of the core (102). The rotating motor is coaxially connected to the rotating shaft (802) and electrically connected to the control system. There are two winding motors (808), which are installed at both ends of the left rotating rod (801). The spline (809) is fixedly installed on the rotating shaft of the winding motor (808). The winding motor (808) is connected to the control system via wires. The control system is electrically connected. Piston chambers are provided at both ends of the two flip rods (801), and second air holes (810) are provided at both ends of the two flip rods (801). The two ends of the multiple second air holes (810) are respectively connected to the piston chamber and the air pump. There are two first-stage rewinding pistons (806), which are slidably connected in the left piston chamber. There are two second-stage rewinding pistons (807), which are slidably connected in the right piston chamber. Inside the plug cavity, both the No. 1 rewinding piston (806) and the No. 2 rewinding piston (807) are provided with spline grooves, and the spline (809) is slidably connected in the spline groove. The multiple piston chambers are connected to the air pump through air pipes. The loading platform (804) and the unloading platform (805) are fixedly installed on the frame (1). The loading platform (804) is located behind the flipping rod (801), and the unloading platform (805) is located in front of the flipping rod (801). The front ends of the loading platform (804) and the unloading platform (805) are lower than the rear ends.

5. A casting machine according to claim 4, characterized in that: The adsorption component includes an air gap (103) and an adsorption air duct (811). A plurality of air gaps (103) are also provided on the core (102). The plurality of air gaps (103) are circumferentially distributed on the outer surface of the core (102), and the plurality of air gaps (103) are parallel to the central axis of the core (102). The left and right ends of the plurality of air gaps (103) are not connected to the left and right ends of the core (102). An adsorption air duct (811) is also provided on the second roll-changing piston (807). When the core (102) is winding, one end of the adsorption air duct (811) is connected to the inside of the core (102), and the other end is connected to an air pump through a trachea. One ends of the plurality of air gaps (103) close to the central axis of the core (102) are connected to the adsorption air duct (811), and the other ends of the plurality of air gaps (103) far from the central axis of the core (102) are connected to the outside of the core (102).

6. A casting machine according to claim 2, characterized in that: The movable traction plate (602) includes a top plate and a bottom plate. The traction air duct (606) is located between the top plate and the bottom plate. The top plate is located above the bottom plate. A first roller (603) and a second roller (604) are respectively rotatably connected to the front ends of the top plate and the bottom plate. The center distance from the turning shaft (802) to the winding motor (808) is A, the center distance from the turning shaft (802) to the first roller (603) is B, and the center distance from the turning shaft (802) to the second roller (604) is C. B < A < C. When the core (102) is winding, the first roller (603) and the second roller (604) are both in rolling connection with the outer surface of the core (102).

7. A casting machine according to claim 2, characterized in that: A limit block (605) is fixedly installed on the frame (1). The limit block (605) is installed on the lower side of the movable traction plate (602). When the upper end surface of the limit block (605) is connected and contacts the lower end surface of the movable traction plate (602), the included angle between the movable traction plate (602) and the bottom of the fixed traction plate (601) is E, and the value range of E is 90° < E < 180°.

8. A method for preparing a polypropylene film, characterized in that, The method for preparing the polypropylene film (101) uses at least the casting machine process according to any one of claims 1 to 7, including the following steps: S1: Raw material pretreatment: Prepare polypropylene resin and additives, and put the polypropylene resin and additives into a mixer for pretreatment; S2: Extrusion production: Feed the pretreated polypropylene resin into the extruder (2) from the feed port, heat and melt the polypropylene resin through the melting system (3), and then extrude it into a primary extrudate through the extruder (2); S3: Casting and cooling: Introduce the primary extrudate into the cooling system (4) and the traction rollers (5). In this step, the thickness of the polypropylene film (101) can be controlled by adjusting the spacing between the traction rollers (5). After the polypropylene film (101) is stretched by the traction rollers (5), it needs to be cooled to an appropriate temperature through the cooling system (4) to maintain its shape and mechanical properties; S4: Winding: The stretched and cooled polypropylene film (101) is pulled to the winding motor (808) by the traction assembly and wound onto the core (102) by the winding motor (808). S5: Cutting: When the polypropylene film (101) on the core (102) is wound to a specified length, the polypropylene film (101) is cut by the cutting assembly; S6: Rewinding: The cut and shaped polypropylene film (101) is rewound through the rewinding assembly. After the rewinding is completed, repeat steps S4 to S6. S7: Packaging and Warehousing: Pack the polypropylene film (101) after it has been rolled up, and store the packaged polypropylene film in the warehouse. S8: Shutdown and Maintenance: After production is completed, shut down the casting machine, perform routine maintenance on the casting machine, and replace worn parts.

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