A film blowing production process of heat-shrinkable film and a film blowing equipment thereof

Abstract

The application discloses a blowing film production process and blowing film equipment of heat-shrinkable film, and the process comprises the following steps: setting the starting temperature, heating and keeping the temperature of the cylinder; adding different raw materials into different heating cavities through a hopper in proportion, and heating, melting, conveying and mixing the different raw materials by using different temperatures and rotating speeds of the heating screw, and conveying the melted different raw materials into a die head at the same time; the die head is provided with high-density material as an outer layer, foaming layer as an intermediate layer and low-density material as an inner layer, so as to form a multilayer parison; vacuum is applied to the die cavity where the foaming layer is located, so that the cell of the foaming layer is split to form a slot hole structure; then the multilayer parison is extruded through the die head to form a multilayer film; the multilayer film is stretched to a required size through a stretching and cooling device; the static electricity of the multilayer film is cleaned and eliminated; and the multilayer film is wound. The application has the characteristics of improving the compactness of the multilayer heat-shrinkable film and work efficiency.

Description

Technical Field

[0001] This invention relates to a blown film process and equipment, particularly a blown film production process and equipment for heat shrink film. Background Technology

[0002] In the blown film process of heat shrink film, an appropriate amount of polymer resin and other additives are generally mixed in a certain proportion by a blown film machine and melted into a plastic melt. Then, it is extruded through a die under high heat and high pressure to form a cylindrical plastic film bubble. The bubble is cooled at the die to make it cool and harden quickly. After being guided and stretched by a series of traction rollers, the bubble is stretched into a planar film and finally wound up.

[0003] For the blow molding production of multilayer heat shrink film, different layers generally use different raw materials, and these raw materials have different physicochemical properties and compatibility, thus requiring high-level processing. Currently, the multilayer heat shrink film process still has certain shortcomings. The processing and co-extrusion technology for different raw materials is not yet perfect, leading to insufficient density between layers and weak interfacial adhesion between different films in the resulting multilayer structure. This results in easy peeling or cracking between the layers of the multilayer heat shrink film, structural instability, material waste, and reduced work efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a blown film production process and equipment for heat shrink film. This invention improves the density and working efficiency of multilayer heat shrink film.

[0005] The technical solution of this invention: a blown film production process for heat shrink film, comprising the following steps:

[0006] S1. Set the start-up temperature and heat and maintain the temperature of the barrel for 1-3 hours;

[0007] S2. Different raw materials are added to different heating chambers in proportion through the hopper, and the different raw materials are heated, melted and transported and mixed by the heating screw at different temperatures and speeds. The melted different raw materials are simultaneously transported to the die head.

[0008] S3. The mold head uses a high-density material as the outer layer, a foamed layer as the middle layer, and a low-density material as the inner layer to form a multi-layer preform.

[0009] S4. Apply vacuum to the mold cavity where the foam layer is located, causing the foam cells of the foam layer to split and form a slotted structure; then extrude through the die head to ensure the compactness between each layer and the correct stacking order, forming a multilayer film;

[0010] S5. The multilayer film is stretched to the required size using a stretching and cooling device;

[0011] S6. Clean and eliminate static electricity from the multilayer film;

[0012] S7. Roll up.

[0013] In the aforementioned blown film production process of heat shrink film, before step S1, the die head, screen changer, and flow channel are set at 100℃-120℃ and kept at a constant temperature for 1 hour; the barrel temperature is set at 100℃ and kept at a constant temperature for 0.5-1 hour.

[0014] In the aforementioned blown film production process of a heat shrinkable film, in step S3, the outer layer is composed of 50% high-density polyethylene and 50% metallocene polyethylene by mass, the inner layer is composed of linear low-density polyethylene, and the foaming layer is composed of ethylene propylene diene monomer (EPDM) copolymer.

[0015] In the aforementioned blown film production process of heat shrink film, in step S4, when the die head is extruding, it first runs at a speed of 300-400 r / min for 3-5 minutes, and then the rotation speed is increased and the feeding speed is adjusted to meet the discharge requirements.

[0016] A blown film equipment for heat shrink film, applied to the above-mentioned blown film production process of heat shrink film, includes a barrel, with several independent heating chambers equipped with exhaust vents inside the barrel. Each heating chamber contains a heating sleeve, and each heating sleeve contains a heating screw. The heating screw includes a feeding section, a heating section, and a discharging section. The feeding section has an internal air pressure chamber, and its surface has several air outlets communicating with the air pressure chamber. The surface of the heating section has two sections of a first and a second threaded portion with opposite thread directions, respectively. Several crushing teeth are provided between the first and second threaded portions. An electromagnetic heating coil is provided inside the heating section. Each heating sleeve's feed inlet is connected to a feed hopper, and each heating sleeve's discharge outlet is connected to a die head. The die head's extrusion port is connected to a stretching and cooling device, which includes an air ring and a bubble stabilizer. A herringbone plate is located above the bubble stabilizer, and several traction rollers are located above the herringbone plate. A take-up roller is located at the traction outlet of the traction rollers, and a cleaning assembly is located between the traction rollers and the take-up rollers.

[0017] In the aforementioned blown film equipment for heat shrink film, the heating sleeve has an internal interlayer with spirally distributed heating wires inside. The inner side of the heating wires is in contact with the heating sleeve, and the outer side of the heating wires is provided with several heat-insulating springs that are larger at one end and smaller at the other. The small end face of the heat-insulating springs is connected to the heating sleeve, and the large end face of the heat-insulating springs is connected to the heating wires.

[0018] In the aforementioned blown film equipment for heat shrink film, the bubble stabilizer includes a first circular frame and a second circular frame. Several circumferentially distributed uprights are provided between the first and second circular frames. The first circular frame has an elongated groove through which the uprights pass. Each upright includes a movable rod and a rotating rod. A push plate is fixedly connected to the movable rod, and a rotating gear is fixedly connected to the rotating rod. The push plate moves along the diameter of the second circular frame under the drive of a push cylinder, and the rotating gear rotates through the meshing of a drive gear under the drive of a rotating motor. Each rotating rod has several connecting rods along its height direction. A mounting frame is provided on each connecting rod, and a guide roller facing the center is provided on the mounting frame. An air bladder is fitted around the guide roller, and the air bladder is filled with compressed gas.

[0019] In the aforementioned blown film equipment for heat shrink film, the mounting frame includes a base plate connected to a connecting rod, with mounting rods movably connected to both ends of the base plate. The base plate has an internal cavity for the movable ends of the mounting rods to extend into. A guide roller is rotatably mounted between the two mounting rods. A detection spring is sleeved on the mounting rod. One end of the detection spring is connected to the base plate, and the other end of the detection spring is connected to the mounting rod. A safety switch is provided on the base plate. The safety switch is electrically connected to an alarm, and the contact of the safety switch is located in the gap of the detection spring.

[0020] In the aforementioned blown film equipment for heat shrink film, the cleaning component includes a drive roller, a plurality of swing frames are circumferentially arranged on the circumference of the drive roller, and a cleaning roller is rotatably connected to the swing frames via a conductive bracket. The cleaning roller is wrapped with cleaning felt. A squeezing roller for squeezing the cleaning felt is provided on one side of the drive roller, and a water tank is provided below the drive roller. A partition is provided inside the water tank, dividing the water tank into a cavity corresponding to the squeezing roller and a water cavity corresponding to the cleaning roller. When the drive roller rotates, the cleaning felt on part of the cleaning roller contacts the heat shrink film, and the cleaning felt on part of the cleaning roller contacts the water in the water cavity.

[0021] In the aforementioned blown film equipment for heat shrink film, the end of the drive roller is provided with a grounded wire ring, the inside of the drive roller is provided with an air supply chamber, the inside of the swing frame is provided with a conductive chamber and an air flow chamber, a conductive wire is provided in the conductive chamber, one end of the conductive wire is connected to the wire ring, and the other end of the conductive wire is connected to the conductive bracket; air jets are provided on both sides of the drive roller on the swing frame, both of which are connected to the air supply chamber through the air flow chamber.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention adds different raw materials in proportion to different heating chambers through a hopper, and heats, melts, and mixes the different raw materials at different temperatures and speeds using a heating screw. The molten raw materials are simultaneously transported to the die head, which facilitates the rapid formation of a multi-layered film, avoids extrusion deviation, and utilizes a foaming layer with grooves to improve the density between layers and the adhesion between interfaces, thereby improving the structural stability of the multi-layered film, reducing material waste, and improving work efficiency.

[0024] The mold head uses a high-density material as the outer layer, a foam layer as the middle layer, and a low-density material as the inner layer to form a multi-layer preform; the structure of the foam layer is used to improve the sound insulation and vibration reduction effect, and the structure of the outer and inner layers ensures airtightness;

[0025] By first extruding at a slow speed and then at a normal speed, the material in each layer fills the mold cavity, ensuring the compactness between layers and the correct stacking sequence, thus forming a multi-layered film.

[0026] The feeding section inside the heating chamber is used to transport raw materials to the heating section. At the same time, airflow is introduced into the air pressure chamber of the feeding section, and the airflow is ejected through the air outlet to further impact and push the raw materials, turning and drying them, so that the raw materials are dispersed and mixed evenly, preventing them from sticking together and alleviating the accumulation and stagnation of materials. The raw materials are transported to the space between the first and second screw sections of the heating section, where they are heated, mixed and melted for a certain period of time, and crushed by crushing teeth to accelerate the melting of the raw materials. The rotation speed of the heating screw is adjusted to adjust the dwell time of different materials in the heating section, so that different materials reach the die head at the same time for co-extrusion, avoiding extrusion deviations that would affect the compactness between layers. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the blown film equipment of the present invention;

[0028] Figure 2 This is a schematic diagram of the heating chamber in a blown film equipment;

[0029] Figure 3 This is a schematic diagram of the heating screw in a blown film equipment;

[0030] Figure 4 This is a schematic diagram of the heating sleeve in a blown film equipment;

[0031] Figure 5 yes Figure 4 Enlarged view of the local structure at point A;

[0032] Figure 6 This is a schematic diagram of the bubble stabilizer in a blown film equipment.

[0033] Figure 7This is a structural diagram of the mounting bracket in the bubble stabilizer;

[0034] Figure 8 This is a schematic diagram of the structure of the upright rod in the bubble stabilizer;

[0035] Figure 9 This is a schematic diagram of the cleaning component.

[0036] The labels in the attached diagram are as follows: 1. Barrel; 2. Heating chamber; 21. Heating sleeve; 211. Jacket; 212. Heating wire; 213. Insulation spring; 22. Heating screw; 221. Feeding section; 222. Heating section; 223. Discharge section; 224. Air outlet; 225. First screw ridge; 226. Second screw ridge; 227. Crushing teeth; 228. Electromagnetic heating coil; 23. Feed hopper; 24. Die head; 31. Air ring; 32. Bubble stabilizer; 33. Herringbone plate; 34. Traction roller; 35. Rewinding roller; 4. Drive roller; 41. Swing frame; 411. Conductive wire; 412. Wire ring; 413. Air jet. 42. Head; Conductive bracket; 43. Cleaning roller; 44. Cleaning felt; 45. Squeeze roller; 46. Water tank; 47. Partition plate; 48. Cavity; 49. Water cavity; 51. First ring frame; 511. Long groove; 52. Second ring frame; 53. Upright pole; 531. Moving rod; 532. Rotating rod; 54. Connecting rod; 55. Mounting frame; 551. Base plate; 552. Mounting rod; 553. Movable cavity; 554. Detection spring; 555. Safety switch; 56. Guide roller; 57. Airbag; 58. Push plate; 581. Pushing cylinder; 59. Rotating gear; 591. Rotating motor; 592. Drive gear. Detailed Implementation

[0037] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0038] Example:

[0039] 1. A blown film production process for heat shrink film, comprising the following steps:

[0040] S1. First, set the die head 24, screen changer, and flow channel to 100℃-120℃ and maintain this temperature for 1 hour; then set the barrel temperature to 100℃ and maintain this temperature for 0.5-1 hour. Ensure that the temperature inside the die head reaches the set process temperature to avoid poor extrusion, which could affect product quality or even damage the extrusion system.

[0041] S2. Set the start-up temperature and heat and keep the barrel 1 warm for 1-3 hours;

[0042] S3. Different raw materials are added to different heating chambers 2 in proportion through the hopper, and the different raw materials are heated, melted and transported and mixed by the heating screw 22 at different temperatures and speeds, and the melted different raw materials are simultaneously transported to the die head 24.

[0043] S4 and the die head 24 form a multi-layer preform with a high-density material as the outer layer, a foamed layer as the middle layer, and a low-density material as the inner layer. The outer layer can be 50% high-density polyethylene and 50% metallocene polyethylene by mass, the inner layer can be linear low-density polyethylene, and the foamed layer can be ethylene propylene diene monomer (EPDM) copolymer.

[0044] S5. Apply a vacuum to the mold cavity containing the foam layer to cause the foam cells to split and form a slotted structure. Then, extrude the foam through die 24. When extruding through die 24, first run at a speed of 300-400 r / min for 3-5 minutes, then increase the speed and adjust the feed rate to meet the discharge requirements. Extrude slowly first, then at normal speed to ensure that each layer of material fills the mold cavity, ensuring the compactness between layers and the correct stacking order, forming a multi-layer film. The structure of the foam layer improves the sound insulation and vibration reduction effect, the structure of the outer and inner layers ensures airtightness, and the slotted foam layer improves the compactness between layers and the adhesion between interfaces, improving the structural stability of the multi-layer film, reducing material waste, and improving work efficiency.

[0045] S6. The multilayer film is stretched to the required size using a stretching and cooling device;

[0046] S7. Clean and eliminate static electricity from the multilayer film;

[0047] S8. Rewinding: Maintain the tension of the forming die at 5-30 kg during rewinding.

[0048] like Figures 1-9A blown film equipment for heat shrink film, applied to the above-mentioned blown film production process of heat shrink film, includes a barrel 1, which has several independent heating chambers 2 with exhaust vents. The heating chambers 2 have heating sleeves 21, and the heating sleeves 21 have heating screws 22. The heating screws 22 include a feeding section 221, a heating section 222, and a discharging section 223. The feeding section 221 has an internal air pressure chamber, and the surface of the feeding section 221 has several air outlets 224 communicating with the air pressure chamber. The surface of the heating section 222 has two sections of first threaded ridges 225 and second threaded ridges 226 with opposite thread directions. The density of the first threaded ridges 225 is greater than that of the second threaded ridges 226, which pushes the material more towards the second threaded ridges 226. Several crushing teeth 227 are provided between the first helical section 225 and the second helical section 226. An electromagnetic heating coil 228 is provided inside the heating section 222. The feed inlet of each heating sleeve 21 is connected to a feed hopper 23. The discharge outlet of each heating sleeve 21 is connected to a die head 24. The extrusion outlet of the die head 24 is connected to a stretching and cooling device. The stretching and cooling device includes an air ring 31 and a bubble stabilizer 32. A herringbone plate 33 is provided above the bubble stabilizer 32. Several traction rollers 34 are provided above the herringbone plate 33. A take-up roller 35 is provided at the traction outlet of the traction rollers 34. A cleaning component is provided between the traction rollers 34 and the take-up rollers 35.

[0049] Different raw materials are injected into different heating chambers 2. The feeding section 221 is used to transport the raw materials to the heating section 222. At the same time, airflow is introduced into the air pressure chamber of the feeding section 221, and the airflow is ejected through the air outlet 224 to further impact and push the raw materials, turning and drying them, so that the raw materials are dispersed and mixed evenly, preventing them from sticking together and alleviating the accumulation and stagnation of materials. The raw materials are transported to the space between the first screw section 225 and the second screw section 226 of the heating section 222, where they are heated, mixed and melted for a certain period of time, and crushed by the crushing teeth 227 to accelerate the melting of the raw materials. The rotation speed of the heating screw is adjusted to adjust the dwell time of different raw materials in the heating section, so that different materials reach the die head 24 at the same time for co-extrusion, avoiding extrusion deviation and affecting the compactness between layers. The extruded multi-layer preform is cooled and stretched to the required size by the stretching and cooling device and then wound up.

[0050] The heating sleeve 21 has an inner layer 211, and a spirally distributed heating wire 212 is provided inside the inner layer 211. The inner side of the heating wire 212 is in contact with the heating sleeve 21, and a number of heat insulation springs 213 with one end larger than the other are provided on the outer side of the heating wire 212. The small end face of the heat insulation spring 213 is connected to the heating sleeve 21, and the large end face of the heat insulation spring 213 is connected to the heating wire 212. Heating wire 212 heats heating sleeve 21, thereby melting the raw material in heating chamber 2. A heat insulation spring 213 is set around the heating wire 212. The elastic force of the heat insulation spring 213 makes the heating wire 212 stick tightly to the heating sleeve 21, improving the heating efficiency and uniformity of the heating sleeve 21. The heat insulation spring 213 has a conical cross-section. The large end face contacts the heating wire 212, exerting strong pressure on the heating wire 212 and improving the clamping effect. The small end face contacts the heating sleeve 21, reducing the contact area with the heating sleeve 21, reducing heat transfer from the heating wire 212, reducing heat loss, and improving heat utilization.

[0051] The bubble stabilizer 32 includes a first circular frame 51 and a second circular frame 52. A plurality of circumferentially distributed uprights 53 are provided between the first circular frame 51 and the second circular frame 52. The first circular frame 51 is provided with an elongated groove 511 for the uprights 53 to pass through. The uprights 53 include a moving rod 531 and a rotating rod 532. A push plate 58 is fixedly connected to the moving rod 531, and a rotating gear 59 is fixedly connected to the rotating rod 532. The push plate 58 moves along the diameter direction of the second circular frame 52 driven by a push cylinder 581. The rotating gear 59 rotates through the meshing of the drive gear 592 driven by a rotating motor 591. The rotating rod 532 and the moving rod 531 are rotatably connected, and the rotating motor 591 is mounted on the push plate 58.

[0052] Each rotating rod 532 is provided with several connecting rods 54 along the height direction. The connecting rods 54 are provided with mounting brackets 55. The mounting brackets 55 are provided with guide rollers 56 facing the center. The guide rollers 56 are covered with air bladders 57, which are filled with compressed gas.

[0053] The film passes through the center of the first circular frame 51 and the second circular frame 52. The bubble stabilizer 32 drives the push plate 58 to move via the electric cylinder 581, thereby moving the upright 53 and the guide roller 56 mounted on the upright 53 along the diameter direction of the first circular frame 51 and the second circular frame 52. This adjusts the limiting range of the guide roller 56 on the film to accommodate the production of films of different sizes and widths. The guide roller 56 is wrapped with an air bladder 57, which, by contacting the film surface, reduces friction during the film's ascent, reducing surface wear and thus lowering the film's scrap rate. By adjusting the compressed gas pressure in the air bladder 57, the squeezing force of the guide roller 56 on the film can be finely adjusted, improving the dimensional adjustment accuracy and movement stability of the film. The rotating motor 591 drives the rotating gear 59 via the drive gear 592, thereby rotating the upright 53 and the guide roller 56 on the upright 53 to better match the laminating film and adapt to different bubble positions and angles.

[0054] The mounting bracket 55 includes a base plate 551 connected to a connecting rod 54. Mounting rods 552 are movably connected to both ends of the base plate 551. The interior of the base plate 551 is provided with a movable cavity 553 into which the movable end of the mounting rod 552 extends. A guide roller 56 is rotatably mounted between the two mounting rods 552. A detection spring 554 is sleeved on the mounting rod 552. One end of the detection spring 554 is connected to the base plate 551, and the other end of the detection spring 554 is connected to the mounting rod 552. A safety switch 555 is provided on the base plate 551. The safety switch 555 is electrically connected to an alarm. The contact of the safety switch 555 is located in the gap of the detection spring 554.

[0055] When the membrane bubble passes through the bubble stabilizer 32, the guide roller 56 contacts the membrane through the elastic force of the detection spring 554. If the membrane bubble becomes eccentric or swings, the deformation of the detection spring 554 on both sides of the guide roller 56 will change, thereby triggering the safety switch 555 to sound an alarm, determining the direction of eccentricity or offset, and facilitating adjustment by the staff.

[0056] The cleaning assembly includes a drive roller 4, with several swing frames 41 circumferentially arranged on the drive roller 4. The swing frames 41 are rotatably connected to cleaning rollers 43 via conductive brackets 42. The cleaning rollers 43 are wrapped with cleaning felt 44. A squeezing roller 45 for squeezing the cleaning felt 44 is provided on one side of the drive roller 4. A water tank 46 is provided below the drive roller 4. A partition 47 is provided inside the water tank 46, dividing the water tank 46 into a cavity 48 corresponding to the squeezing roller 45 and a water cavity 49 corresponding to the cleaning roller 43. When the drive roller 4 rotates, the cleaning felt 44 on some of the cleaning rollers 43 comes into contact with the heat shrink film to clean the surface of the heat shrink film, and the cleaning felt 44 on some of the cleaning rollers 43 comes into contact with the water in the water cavity 49 to clean and replenish the water in the cleaning felt 44.

[0057] As the drive roller 4 rotates, the highly moist cleaning felt 44, soaked in water, comes into contact with the membrane to remove dust, oil, and static electricity. The cleaning felt 44, now laden with impurities, is rotated to the squeeze roller 45, where it is squeezed out of the wastewater, which falls into the cavity 48. Then, with the rotation of the drive roller 4, the cleaning felt 44 is rotated into the water cavity 49 to absorb water again and continue cleaning the membrane. Drive rollers 4 can be installed on both sides of the membrane as needed to improve the overall cleaning effectiveness.

[0058] The drive roller 4 has a grounded wire ring 412 at its end. The drive roller 4 has an air supply chamber inside, and the swing frame 41 has a conductive chamber and an airflow chamber inside. A conductive wire 411 is installed in the conductive chamber; one end of the conductive wire 411 is connected to the wire ring 412, and the other end is connected to the conductive bracket 42. Air jets 413, connected to the air supply chamber via the airflow chamber, are located on both sides of the drive roller 4 on the swing frame 41. Static electricity is introduced to the wire ring 412 through the conductive bracket 42 and the conductive wire 411 and is eliminated by grounding. The air jets 413 further remove particulate impurities from the membrane and dry the areas wetted by the cleaning felt 44 with airflow, facilitating subsequent membrane winding.

Claims

1. A blown film production process for heat-shrinkable film, characterized in that: Includes the following steps: S1. Set the start-up temperature and heat and maintain the temperature of the barrel for 1-3 hours; S2. Different raw materials are added to different heating chambers in proportion through the hopper, and the different raw materials are heated, melted and transported and mixed by the heating screw at different temperatures and speeds. The melted different raw materials are simultaneously transported to the die head. S3. The mold head uses a high-density material as the outer layer, a foamed layer as the middle layer, and a low-density material as the inner layer to form a multi-layer preform. S4. Apply vacuum to the mold cavity where the foam layer is located, causing the foam cells of the foam layer to split and form a slotted structure; then extrude through the die head to ensure the compactness between each layer and the correct stacking order, forming a multilayer film; S5. The multilayer film is stretched to the required size using a stretching and cooling device; S6. Clean and eliminate static electricity from the multilayer film; S7. Roll up.

2. The blown film production process for heat-shrinkable film according to claim 1, characterized in that: Before step S1, set the die head, screen changer, and flow channel to 100℃-120℃ and maintain the temperature for 1 hour; set the barrel temperature to 100℃ and maintain the temperature for 0.5-1 hour.

3. The blown film production process for heat-shrinkable film according to claim 1, characterized in that: In step S3, the outer layer is composed of 50% high-density polyethylene and 50% metallocene polyethylene by mass, the inner layer is composed of linear low-density polyethylene, and the foaming layer is composed of ethylene propylene diene monomer (EPDM) copolymer.

4. The blown film production process for heat-shrinkable film according to claim 1, characterized in that: In step S4, when the die head is extruding, it first runs at a speed of 300-400 r / min for 3-5 minutes, and then the rotation speed is increased and the feeding speed is adjusted to meet the discharge requirements.

5. A blown film equipment for heat shrink film, applied to the blown film production process of heat shrink film according to any one of claims 1-4, characterized in that: The device includes a barrel (1), which contains several independent heating chambers (2) with exhaust vents. Each heating chamber (2) contains a heating sleeve (21), and the heating sleeve (21) contains a heating screw (22). The heating screw (22) includes a feeding section (221), a heating section (222), and a discharge section (223). The feeding section (221) has an internal air pressure chamber, and its surface has several air outlets (224) communicating with the air pressure chamber. The heating section (222) has two sections of oppositely oriented first threaded portion (225) and second threaded portion (226) on its surface. (226) There are several crushing teeth (227) between them, and an electromagnetic heating coil (228) is provided inside the heating section (222); the feed inlet of each heating sleeve (21) is connected to a feed hopper (23), the discharge outlet of each heating sleeve (21) is connected to a die head (24), the extrusion outlet of the die head (24) is connected to a stretching cooling device, the stretching cooling device includes an air ring (31) and a bubble stabilizer (32), a herringbone plate (33) is provided above the bubble stabilizer (32), several traction rollers (34) are provided above the herringbone plate (33), a take-up roller (35) is provided at the traction outlet of the traction roller (34), and a cleaning component is provided between the traction roller (34) and the take-up roller (35); The heating sleeve (21) has an inner jacket (211) with spirally distributed heating wires (212) inside. The inner side of the heating wires (212) is in contact with the heating sleeve (21), and the outer side of the heating wires (212) is provided with several heat insulation springs (213) with one end larger than the other. The small end face of the heat insulation springs (213) is connected to the heating sleeve (21), and the large end face of the heat insulation springs (213) is connected to the heating wires (212). The bubble stabilizer (32) includes a first ring frame (51) and a second ring frame (52). Several circumferentially distributed uprights (53) are provided between the first ring frame (51) and the second ring frame (52). The first ring frame (51) has an elongated groove (511) through which the uprights (53) pass. Each upright (53) includes a movable rod (531) and a rotating rod (532). A push plate (58) is fixedly connected to the movable rod (531), and a rotating gear (59) is fixedly connected to the rotating rod (532). (58) Driven by the electric cylinder (581), it moves along the diameter direction of the second ring frame (52). The rotating gear (59) is driven by the rotating motor (591) and rotates through the meshing of the drive gear (592). Each rotating rod (532) is provided with several connecting rods (54) along the height direction. The connecting rod (54) is provided with a mounting bracket (55). The mounting bracket (55) is provided with a guide roller (56) facing the center. The guide roller (56) is covered with an air bag (57). The air bag (57) is filled with compressed gas.

6. The blown film equipment for heat-shrinkable film according to claim 5, characterized in that: The mounting bracket (55) includes a base plate (551) connected to a connecting rod (54). Mounting rods (552) are movably connected to both ends of the base plate (551). The interior of the base plate (551) is provided with a movable cavity (553) into which the movable end of the mounting rod (552) extends. A guide roller (56) is rotatably mounted between the two mounting rods (552). A detection spring (554) is sleeved on the mounting rod (552). One end of the detection spring (554) is connected to the base plate (551), and the other end of the detection spring (554) is connected to the mounting rod (552). A safety switch (555) is provided on the base plate (551). The safety switch (555) is electrically connected to an alarm. The contact of the safety switch (555) is located in the gap of the detection spring (554).

7. The blown film equipment for heat-shrinkable film according to claim 5, characterized in that: The cleaning assembly includes a drive roller (4), and several swing frames (41) are arranged around the circumference of the drive roller (4). The swing frames (41) are rotatably connected to the cleaning roller (43) via a conductive bracket (42). The cleaning roller (43) is wrapped with a cleaning felt (44). A squeezing roller (45) for squeezing the cleaning felt (44) is provided on one side of the drive roller (4). A water tank (46) is provided below the drive roller (4). A partition (47) is provided inside the water tank (46). The partition (47) divides the water tank (46) into a cavity (48) corresponding to the squeezing roller (45) and a water cavity (49) corresponding to the cleaning roller (43). When the drive roller (4) rotates, the cleaning felt (44) on some of the cleaning rollers (43) comes into contact with the heat shrink film, and the cleaning felt (44) on some of the cleaning rollers (43) comes into contact with the water in the water cavity (49).

Images