Blown film machine die structure and method of using same

Abstract

The application discloses a film blowing machine die structure and a using method thereof, and relates to the technical field of film production. The film blowing machine die structure comprises a die body, a vertical pipe is arranged at the middle part of the upper end of the die body, a vertical displacement mechanism and a film clamping mechanism are arranged on the vertical pipe, the film clamping mechanism is used for clamping a tubular blank film extruded and formed by the die body, and the vertical displacement mechanism is used for pushing the film clamping mechanism upward, so that the tubular blank film is pulled upward into a roller device above, and the roller device extrudes the tubular blank film into a linear film. Through the cooperation of the film clamping mechanism and the vertical displacement mechanism, the automatic clamping, pulling and overturning of the tubular blank film are realized, the complexity and the safety hazard of traditional manual multi-link cooperation are avoided, the human error rate is significantly reduced, the film starting time is shortened from 5-10 minutes to 1-2 minutes, and the production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of thin film production technology, and specifically to a blown film machine die head structure and its usage method. Background Technology

[0002] A blown film machine is an important piece of equipment widely used in plastic packaging, agricultural film, and other fields. One of its core components is the die head. The die head is responsible for extruding molten plastic into a tubular preform, which is then further processed into qualified blown film products in subsequent processes such as cooling and traction. The design of the die head structure directly affects the stability of the blown film process and the product quality, especially in the film-forming stage, which is the process of initially extruding the preform from the die and forming stable air bubbles.

[0003] In existing blown film extrusion processes, the initial stretching and traction of the preform is typically achieved manually. Specifically, the operator below manually pulls the hot-melt preform extruded from the die slowly, drawing it upwards to form a preliminary tubular structure. This preform is then handed over to the operator above for further stretching until it is tractioned to the upper roller assembly for extrusion into a linear film. This process requires close cooperation from multiple workers, including those involved in pulling out the preform, handing it over mid-process, traction from above, and roller extrusion. However, existing extrusion methods have significant drawbacks: First, the multi-person collaboration increases operational complexity, requiring workers to frequently coordinate their movements in high-temperature and high-humidity environments, increasing the risk of human error and safety hazards. Second, the manual pulling process lacks precise tension control, often resulting in repeated tearing of the film due to uneven stretching or excessive speed, leading to a large number of defective products and extended debugging time. Finally, the overall extrusion efficiency is low, affecting production continuity and limiting the automation level and overall capacity of the blown film machine. Summary of the Invention

[0004] The purpose of this invention is to provide a blown film machine die head structure and its usage method, which solves the problem that existing blown film machine dies do not have automatic traction.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution: The present invention includes a mold body, a vertical tube is installed at the upper middle position of the mold body, and a vertical displacement mechanism and a film clamping mechanism are provided on the vertical tube;

[0006] The clamping mechanism is used to hold the tubular preform film extruded from the mold body, and the vertical displacement mechanism is used to push the clamping mechanism upward, thereby pulling the tubular preform film upward into the upper roller device, where the roller device extrudes it into a linear film.

[0007] Preferably, the mold body includes a mold core and an outer mold body disposed outside the mold core. A circumferential material transfer channel is formed between the outer mold body and the mold core. A connecting hole is provided on the lower side of the material transfer channel for connecting to an external feeding system to provide raw materials. The upper end of the material transfer channel is the discharge end. A groove is provided on the upper ends of the outer mold body and the mold core. The discharge end of the material transfer channel is located on the inner wall of the groove. A spiral groove is provided in the material transfer channel for extruding the raw materials to improve uniformity.

[0008] Preferably, a first air pipe and a second air pipe are pre-embedded in the mold body, and an air outlet is opened at the upper end of the vertical pipe. The second air pipe and the first air pipe are respectively connected to the cold air outlet and hot air inlet of the external cold air device to form a cold air circulation system that is discharged from the bottom to the top through the vertical pipe, so as to uniformly cool the tubular blank film.

[0009] Preferably, the film clamping mechanism includes two adapter seats and two flexible rotating rods. The two flexible rotating rods are symmetrically arranged, with their two ends respectively hinged to the two adapter seats and rotating in the horizontal direction. Plastic strips are rotatably mounted on the two flexible rotating rods. The plastic strips are flexible and can switch between a straight structure and a semi-circular structure.

[0010] When the two plastic strips are bent into a semi-circular structure, the two plastic strips and the two adapters form a structure similar to a circle, at which time the plastic strips cannot rotate on the flexible rotating rod; when the two plastic strips are stretched into a straight structure, the plastic strips can rotate on the flexible rotating rod.

[0011] A flexible strip is fixed to the plastic strip. The vertical cross-section of the flexible strip is a semi-enclosed structure, forming an opening. When the plastic strip is semi-circular, the opening faces outward. An expandable and contractible flexible air bladder is provided in the opening of the flexible strip. The flexible air bladder is connected to a spiral air tube. The spiral air tube is connected to an external air pump inside the mold through a third air pipe. When compressed air is injected into the flexible air bladder, it expands and fills the opening of the flexible strip to clamp the tubular blank.

[0012] Preferably, the outer side of the flexible strip is provided with a plurality of support blocks fixed to the plastic strip to withstand the compressive force when the flexible airbag expands and increase the clamping force.

[0013] Preferably, the vertical displacement mechanism includes a sliding column and a sliding sleeve slidably sleeved on the vertical tube, the sliding column being located below the sliding sleeve, and a first spring sleeved on the vertical tube being provided between the sliding column and the sliding sleeve.

[0014] A driving component is provided on the sliding column to drive the sliding sleeve, the first spring, and the sliding column to move vertically along the vertical tube; two symmetrical telescopic rods are installed on the outside of the sliding column, and a vertical rod is fixed to the telescopic end of the telescopic rod. The upper end of the vertical rod is connected to the clamping mechanism, and a stop block is fixed to the top of the vertical tube; two push rods are hinged to the outside of the sliding sleeve, and their lower ends are connected to the telescopic rods through a delay translation component.

[0015] Preferably, the delayed translation component includes an elongated groove formed at the outer end of the telescopic rod, a sliding seat slidably disposed in the elongated groove, the lower end of the push rod being hinged to the sliding seat, and a second spring disposed on the outer side of the sliding seat, the elastic coefficient of the second spring being greater than that of the first spring.

[0016] Preferably, the driving component includes a first rack disposed on the outside of the vertical tube and a motor mounted on the sliding column. A gear is mounted on the output end of the motor, and the gear meshes with the first rack.

[0017] Preferably, the top of the vertical tube is provided with a flipping mechanism for driving the plastic strip to flip upward so that the opening faces upward; the flipping mechanism includes an outer cylinder fixed to the top of the vertical tube and arc-shaped teeth processed on the outer side wall of the plastic strip; a vertical rod is vertically slidably arranged inside the outer cylinder, and a third spring is provided inside the outer cylinder to give the vertical rod a downward force; a plate is fixed on the upper side of the vertical rod, and a second rack is processed on both sides of the upper end of the plate, the second rack being adapted to the arc-shaped teeth.

[0018] This invention also proposes a method for using a blown film machine die head structure, comprising the following steps:

[0019] Step 1: Move the film clamping mechanism into the groove using the vertical displacement mechanism so that the opening corresponds to the discharge end of the material conveying channel;

[0020] Step 2: The head of the tubular preform enters the opening, and the air pump is used to inject air to expand the soft airbag and clamp the tubular preform.

[0021] Step 3: The driving mechanism of the film clamping device is moved upward, pulling the upper end of the tubular preform film to the upper part of the vertical tube;

[0022] Step 4: The drive unit continues to move upward, squeezing the first spring, reducing the horizontal angle of the push rod, causing the telescopic rod to extend outward, straightening the plastic strip, engaging the arc-shaped teeth with the second rack, flipping the plastic strip so that the opening faces upward, compressing the second and third springs to send the tubular blank into the roller device;

[0023] Step 5: Expel the air from the soft airbag, loosen the fixation on the tubular preform, and roll the tubular preform into the roller device to form a linear film;

[0024] Step 6: Move the drive unit downwards and reset the membrane clamping mechanism to the middle of the vertical tube.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. Through the coordination of the film clamping mechanism and the vertical displacement mechanism, the tubular preform film is automatically clamped, pulled and flipped, avoiding the complexity and safety hazards of traditional manual multi-stage collaboration, significantly reducing the human error rate, and shortening the film lifting time from 5-10 minutes to 1-2 minutes, thus improving production efficiency.

[0027] 2. The spiral groove in the material transfer channel uniformly compresses the raw material, and the cold air circulation system uniformly cools the preform, effectively controlling the film thickness deviation within ±5%, reducing tearing and scrap caused by uneven stretching, reducing the scrap rate by more than 20%, and ensuring the stability and consistency of blown film products.

[0028] 3. The precision design of the flipping mechanism and delayed translation component enables rapid reset and interference-free operation, supporting high-frequency continuous production; the structural optimization of the support block and soft airbag extends the component life by 20%, reduces maintenance costs, and adapts to different specifications of preforms, improving the equipment's versatility.

[0029] 4. The automated traction mechanism reduces debugging time and manpower input. Combined with precise tension control and air temperature regulation, it accelerates the cooling and forming process, increasing the overall capacity of the blown film machine by more than 30%. It is suitable for large-scale production in fields such as plastic packaging and agricultural film. Attached Figure Description

[0030] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0031] Figure 2 for Figure 1 A three-dimensional structural diagram of the interlocking membrane mechanism and the vertical displacement mechanism;

[0032] Figure 3 for Figure 1 A schematic diagram of the planar cross-sectional structure of the middle phantom;

[0033] Figure 4 for Figure 1 Enlarged structural diagram at point A in the middle;

[0034] Figure 5 for Figure 3 Enlarged structural diagram at point B;

[0035] Figure 6 for Figure 3 Enlarged structural diagram at point C;

[0036] Figure 7This is a schematic diagram of the membrane clamping mechanism in this invention when it is deployed;

[0037] Figure 8 This is a schematic diagram of the membrane clamping mechanism in this invention when it is closed;

[0038] Figure 9 This is a schematic diagram of a planar structure in which all plastic strips are in contact with the sheet.

[0039] Figure 10 A schematic diagram of a planar structure in which two plastic strips are flipped upwards;

[0040] Figure 11 This is a schematic diagram of a planar structure in which a plate is pulled upwards.

[0041] The numbers in the image represent:

[0042] 11-Outer mold body; 12-Mold core; 13-Material transfer channel; 14-Spiral groove; 15-Connecting hole; 16-Groove; 17-Second air pipe; 18-First air pipe; 19-Air outlet; 100-Tube preform;

[0043] Vertical pipe; 21-stop block;

[0044] Clamping mechanism; 31-Plastic strip; 32-Support block; 33-Flexible strip; 34-Flexible airbag; 35-Opening; 36-Adapter seat; 37-Flexible rotating rod; 38-Spiral air tube;

[0045] Vertical displacement mechanism; 411-First rack; 412-Gear; 413-Motor; 42-Sliding column; 43-Telescopic rod; 44-Second spring; 45-Sliding seat; 46-Push rod; 47-Sliding sleeve; 48-First spring; 49-Upright rod;

[0046] 51-Arc-shaped tooth; 52-Outer cylinder; 53-Third spring; 54-Vertical rod; 55-Plate; 56-Second rack. Detailed Implementation

[0047] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0048] This embodiment provides a technical solution: a blown film machine die head structure, such as... Figures 1-11 As shown, the device includes a mold body 1, on which a film clamping mechanism 3 and a vertical displacement mechanism 4 are installed. The film clamping mechanism 3 is used to clamp the tubular preform 100 extruded from the mold body 1, while the vertical displacement mechanism 4 is used to push the film clamping mechanism 3 upward, thereby pulling the tubular preform 100 upward into the upper roller device, where the roller device will compress it into a linear film.

[0049] In an optional embodiment, the mold body 1 includes a mold core 12 and an outer mold body 11 disposed outside the mold core 12. A circumferential material transfer channel 13 is formed between the outer mold body 11 and the mold core 12, and a connecting hole 15 is provided on the lower side of the material transfer channel 13. The connecting hole 15 is used to connect with an external feeding system to provide raw materials to the mold body 1. The upper end of the material transfer channel 13 is the discharge end. The upper ends of the outer mold body 11 and the mold core 12 are jointly provided with a groove 16, and the discharge end of the material transfer channel 13 is located on the inner wall of the groove 16. A spiral groove 14 is also provided in the material transfer channel 13. As the raw material moves upward, it is squeezed by the groove wall of the spiral groove 14. The squeezing process helps to improve the uniformity of the raw material. The upper material transfer channel 13 gradually widens, which is conducive to the smooth upward movement of the material, thereby improving the uniformity and smoothness of the blown film and resulting in high blown film stability.

[0050] A vertical pipe 2 is vertically arranged at the bottom center of the groove 16. The vertical pipe 2 has a certain height in the vertical dimension, which is slightly lower than the height of the roller device. A first air pipe 18 and a second air pipe 17 are pre-embedded in the outer mold body 11 and the mold core 12. The outer ends of the first air pipe 18 and the second air pipe 17 are provided with joints. An air outlet 19 is opened at the upper end of the vertical pipe 2. The second air pipe 17 and the first air pipe 18 are respectively connected to the cold air outlet and hot air inlet of the external cold air device. In use, cold air is introduced into the second air pipe 17, blown out from the bottom, and finally discharged through the air outlet 19, the vertical pipe 2, and the first air pipe 18, so as to form a cold air circulation system from bottom to top and discharged through the vertical pipe 2 to cool the tubular blank 100.

[0051] The film clamping mechanism 3 includes two adapter seats 36 and two flexible rotating rods 37. The two flexible rotating rods 37 are symmetrically arranged, and their two ends are respectively hinged to the two adapter seats 36. Both flexible rotating rods 37 rotate horizontally. Plastic strips 31 are rotatably mounted on each of the two flexible rotating rods 37. The plastic strips 31 have a certain degree of flexibility and can be bent, switching between a straight line and a semi-circular structure. When the two plastic strips 31 are bent into semi-circular structures, the two plastic strips 31 and the two adapter seats 36 form a structure similar to a circle (e.g., ...). Figure 7 As shown), and at this time, since both the flexible rotating rod 37 and the plastic strip 31 are curved, the plastic strip 31 cannot rotate on the flexible rotating rod 37; when the two plastic strips 31 are stretched into a straight structure (as shown), Figure 8As shown), both the flexible rotating rod 37 and the plastic strip 31 are straight lines at this time, and the plastic strip 31 can rotate on the flexible rotating rod 37. A flexible strip 33 is fixed on the plastic strip 31, and the vertical section of the flexible strip 33 is a semi-enclosed structure, forming an opening 35. When the flexible strip 33 is a semi-circular structure, the opening 35 faces outward. A flexible airbag 34 that can expand and contract is provided in the opening 35 of the flexible strip 33. The flexible airbag 34 is connected to a spiral air tube 38, which is a spiral structure and is wound around the outside of the vertical tube 2. A third air pipe connected to the spiral air tube 38 is provided inside the mold body 1. The third air pipe is connected to an external air pump to inject compressed air into the flexible airbag 34. When the flexible airbag 34 inflates, it fills the opening 35 of the flexible strip 33 to clamp the tubular preform 100. In order to increase the force that the flexible strip 33 can withstand, multiple support blocks 32 fixed to the plastic strip 31 are provided on the outside of the flexible strip 33. When the flexible airbag 34 inflates, the support blocks 32 can withstand the squeezing force brought by the flexible airbag 34, increasing the clamping force on the tubular preform 100. The multiple support blocks 32 are triangular or trapezoidal in shape. When the flexible strip 33 is shaped into a straight line or a semi-circular structure along with the plastic strip 31, two adjacent support blocks 32 will not interfere with each other.

[0052] In use, the vertical displacement mechanism 4 moves the clamping mechanism 3 into the groove 16, so that the opening 35 of the flexible strip 33 corresponds to the discharge end of the material transfer channel 13 (e.g., Figure 6 As shown), the head of the tubular preform 100 discharged from the mold 1 will first enter the opening 35 of the two flexible strips 33. Then, the air pump will inject air into the flexible air bag 34 through the spiral air pipe 38, causing the flexible air bag 34 to expand and squeeze and fix the head of the tubular preform 100, that is, fix the tubular preform 100. Then, the vertical displacement mechanism 4 will move the clamping mechanism 3 upward, thereby pulling the upper end of the tubular preform 100 upward until it is sent into the roller device and extruded into a linear film.

[0053] The film clamping mechanism 3 includes a sliding column 42 and a sliding sleeve 47 slidably sleeved on the vertical tube 2, with the sliding column 42 located below the sliding sleeve 47. A first spring 48, sleeved on the vertical tube 2, is provided between the sliding column 42 and the sliding sleeve 47. The first spring 48 can withstand the weight of the sliding sleeve 47 without deformation. A driving component is provided on the sliding column 42 to drive the sliding sleeve 47, the first spring 48, and the sliding column 42 to move vertically along the vertical tube 2, serving as the power structure for pulling the tubular preform 100 upward. Two horizontally symmetrically arranged telescopic rods 43 are installed on the outside of the sliding column 42. The outer ends of the telescopic ends of the two telescopic rods 43 are fixed with uprights 49. The upper ends of the two uprights 49 are respectively fixedly connected to the two adapter seats 36 of the film clamping mechanism 3. Two horizontally mounted push rods 46 are hinged to the outer side of the sliding sleeve 47. The lower ends of the two push rods 46 are connected to the telescopic ends of the two telescopic rods 43 via delay translation members. The delay translation members include elongated grooves formed at the outer ends of the telescopic ends of the telescopic rods 43. A sliding seat 45 is slidably mounted in the elongated groove, and the lower ends of the push rods 46 are hinged to the sliding seat 45. A second spring 44 is mounted on the outer side of the sliding seat 45. The elastic coefficient of the second spring 44 is greater than that of the first spring 48. That is, when the first spring 48 is compressed and deformed, the second spring 44 will not deform, but will extend the telescopic rod 43. When the telescopic rod 43 extends to its maximum length, it can extend further, that is, compress the second spring 44 to cause it to deform. A stop block 21 is fixed at the top of the vertical tube 2 to limit the maximum upward displacement of the sliding sleeve 47 and to reduce the horizontal angle of the push rods 46, so as to push the telescopic rod 43 outward.

[0054] A flipping mechanism is provided at the top of the vertical tube 2 to drive the two plastic strips 31 to flip upwards so that the opening 35 faces upwards. The flipping mechanism includes an outer cylinder 52 fixed to the top of the vertical tube 2 and arc-shaped teeth 51 machined on the outer side walls of the two plastic strips 31. The arc-shaped teeth 51 are composed of multiple teeth and can engage with the second rack 56 when the plastic strips 31 are straightened. It should be noted that the outer side walls of the two plastic strips 31 are arc-shaped. A vertical rod 54 is vertically slidably arranged inside the outer cylinder 52. A plate 55 is fixed to the upper end of the vertical rod 54. A third spring 53 is provided inside the outer cylinder 52 to give the vertical rod 54 a downward force. The second rack 56 is machined on both sides of the upper end of the plate 55 and the second rack 56 is adapted to the arc-shaped teeth 51.

[0055] After the clamping mechanism 3 clamps the tubular preform 100, the driving component is activated, causing the sliding sleeve 47, the first spring 48, and the sliding column 42 to move upward as a whole, thereby moving the upper end of the tubular preform 100 upward until the sliding sleeve 47 contacts the abutment block 21. At this time, the upper roller device of the tubular preform 100 has a certain size, which can be designed to be maintained at 300mm-500mm. When the driving component continues to drive the upward displacement, since the sliding sleeve 47 is restricted from moving, it will squeeze the first spring 48, causing the first spring 48 to be compressed. The upper end of the sliding column 42 is provided with a way to accommodate the first spring 48. The first spring 48 will gradually retract into the annular groove, and the horizontal angle of the push rod 46 will gradually decrease. The outer end of the push rod 46 will push the extension end of the telescopic rod 43 to extend. Therefore, the two adapter seats 36 of the clamping mechanism 3 will be linearly pushed to gradually pull the two plastic strips 31 and the two flexible strips 33 into a straight structure, thereby stretching the upper end of the tubular preform 100 into a long rectangular structure. At this time, the telescopic rod 43 is stretched to its maximum stroke, and both plastic strips 31 are in contact with the sheet 55. The two second racks 56 can respectively mesh with the two arc-shaped teeth 51 (e.g., Figure 9 As shown), as the driving component continues to move upward, since the telescopic rod 43 cannot extend further, the sliding seat 45 will move outward and compress the second spring 44. Simultaneously, the two plastic strips 31 will continue to move upward (the arrangement of the second spring 44 and the sliding seat 45 allows the compression of the second spring 44 to provide space for the push rod 46 to continue flipping when the two plastic strips 31 are pulled into a straight structure, thus pushing the clamping mechanism 3 upward further). This causes the two plastic strips 31 to flip upward (as shown). Figure 10As shown), the inner sides of the two plastic strips 31 will abut against each other, limiting the maximum angle at which the two plastic strips 31 flip inward, and the two second racks 56 will be held by the two arc-shaped teeth 51. At this time, the upper end of the tubular preform 100 is close to the roller device, which can be designed to be maintained at 20-40mm. When the driving component continues to drive upward displacement, it will push the film clamping mechanism 3 upward, compressing the third spring 53, and the sheet 55 will move upward synchronously with the plastic strips 31, and feed the tubular preform 100 into the roller device. The rollers of the roller device contact the upper end of the tubular preform 100 (because the distance between the two rollers of the roller device is small, this one The series of actions allows the plastic strip 31 to flip upwards before being fed between the two rollers of the roller device, so that the position of the two plastic strips 31 is set in a sufficiently spacious position under the two rollers of the roller device. Conversely, the same principle applies when the two plastic strips 31 move downwards after the traction of the tubular preform 100 is completed (this avoids contact interference between the film clamping mechanism 3 and the tubular preform 100). By expelling the air in the soft airbag 34, the soft airbag 34 is contracted to loosen the fixation on the tubular preform 100. Under the action of the rollers of the roller device, the tubular preform 100 is wound into the roller device, thus completing the traction of the tubular preform 100. When the driving component drives the downward displacement, the plate 55 will first move downward along with the two plastic strips 31, and the third spring 53 will rebound. Then the two plastic strips 31 will flip outward to the state where the opening 35 faces outward. The second spring 44 and the first spring 48 will gradually rebound, so that the two plastic strips 31 will gradually bend into a semi-circular structure until the driving component moves the clamping mechanism 3 to the middle position of the vertical tube 2, so as to avoid affecting the normal production of the tubular preform 100.

[0056] It should be noted that the outer diameter of the flexible strip 33 is smaller than the inner diameter of the tubular preform 100 to avoid interference between the tubular preform 100 and the flexible strip 33 during the production process.

[0057] The driving components include a first rack 411 disposed on the outside of the vertical tube 2 and a motor 413 mounted on the sliding column 42. A gear 412 is mounted on the output end of the motor 413. The gear 412 meshes with the first rack 411. When the motor 413 is running, the vertical displacement mechanism 4 can be driven to move vertically along the vertical tube 2 through the cooperation of the gear 412 and the first rack 411.

[0058] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A blown film machine die head structure, characterized in that, Includes a mold body, wherein a vertical tube is installed at the upper middle position of the mold body, and a vertical displacement mechanism and a film clamping mechanism are provided on the vertical tube; The clamping mechanism is used to hold the tubular preform film extruded from the mold body, and the vertical displacement mechanism is used to push the clamping mechanism upward, thereby pulling the tubular preform film upward into the upper roller device, where the roller device extrudes it into a linear film. The film clamping mechanism includes two adapter seats and two flexible rotating rods. The two flexible rotating rods are symmetrically arranged, and their two ends are respectively hinged to the two adapter seats and rotate in the horizontal direction. Plastic strips are rotatably installed on the two flexible rotating rods. The plastic strips are flexible and can switch between a straight structure and a semi-circular structure. When the two plastic strips are bent into a semi-circular structure, the two plastic strips and the two adapters form a structure similar to a circle. At this time, the plastic strips cannot rotate on the flexible rotating rod. When the two plastic strips are stretched into a straight structure, the plastic strips can rotate on the flexible rotating rod. A flexible strip is fixed to the plastic strip. The vertical cross-section of the flexible strip is a semi-enclosed structure, forming an opening. When the plastic strip is semi-circular, the opening faces outward. An expandable and contractible flexible airbag is provided in the opening of the flexible strip. The flexible airbag is connected to a spiral air tube. The spiral air tube is connected to an external air pump inside the mold through a third air pipe. When compressed air is injected into the flexible airbag, it expands and fills the opening of the flexible strip to clamp the tubular preform. The vertical displacement mechanism includes a sliding column and a sliding sleeve that are slidably sleeved on the vertical tube. The sliding column is located on the lower side of the sliding sleeve, and a first spring sleeved on the vertical tube is provided between the sliding column and the sliding sleeve. A driving component is provided on the sliding column to drive the sliding sleeve, the first spring, and the sliding column to move vertically along the vertical tube. Two symmetrical telescopic rods are installed on the outside of the sliding column. A vertical rod is fixed to the telescopic end of the telescopic rod. The upper end of the vertical rod is connected to the clamping mechanism. A stop block is fixed to the top of the vertical tube. After the sliding sleeve moves up a certain distance, it will contact the stop block. After contact, the sliding sleeve is restricted from moving upward. Two push rods are hinged to the outside of the sliding sleeve. The lower ends of the push rods are connected to the telescopic rods through a delay translation component. The top of the vertical tube is provided with a flipping mechanism for driving the plastic strip to flip upward so that the opening faces upward; the flipping mechanism includes an outer cylinder fixed to the top of the vertical tube and arc-shaped teeth machined on the outer side wall of the plastic strip; a vertical rod is vertically slidably arranged inside the outer cylinder, and a third spring is provided inside the outer cylinder to give the vertical rod a downward force; a plate is fixed on the upper side of the vertical rod, and a second rack is machined on both sides of the upper end of the plate, the second rack being adapted to the arc-shaped teeth.

2. The blown film machine die head structure as described in claim 1, characterized in that, The mold body includes a mold core and an outer mold body disposed outside the mold core. A circumferential material transfer channel is formed between the outer mold body and the mold core. A connecting hole is provided on the lower side of the material transfer channel for connecting to an external feeding system to provide raw materials. The upper end of the material transfer channel is the discharge end. The upper ends of the outer mold body and the mold core are jointly provided with a groove. The discharge end of the material transfer channel is located on the inner wall of the groove. A spiral groove is provided in the material transfer channel for extruding the raw materials to improve uniformity.

3. The blown film machine die head structure as described in claim 1, characterized in that, The mold body is pre-embedded with a first air pipe and a second air pipe. The upper end of the vertical pipe is provided with an air outlet. The second air pipe and the first air pipe are respectively connected to the cold air outlet and hot air inlet of an external cold air device to form a cold air circulation system that is discharged from the bottom to the top through the vertical pipe, so as to uniformly cool the tubular blank film.

4. The blown film machine die head structure as described in claim 1, characterized in that, Multiple support blocks fixed to the plastic strip are provided on the outer side of the flexible strip to withstand the squeezing force when the flexible airbag inflates and increase the clamping force.

5. The blown film machine die head structure as described in claim 2, characterized in that, The delayed translation component includes an elongated groove formed at the outer end of the telescopic rod's telescopic end, a sliding seat slidably disposed within the elongated groove, the lower end of the push rod being hinged to the sliding seat, and a second spring disposed on the outer side of the sliding seat, the elastic coefficient of the second spring being greater than that of the first spring.

6. The blown film machine die head structure as described in claim 1, characterized in that, The driving component includes a first rack disposed on the outside of the vertical tube and a motor mounted on the sliding column. A gear is mounted on the output end of the motor, and the gear meshes with the first rack.

7. The method of using the blown film machine die head structure as described in claim 5, characterized in that, Includes the following steps: Step 1: Move the film clamping mechanism into the groove using the vertical displacement mechanism so that the opening corresponds to the discharge end of the material conveying channel; Step 2: The head of the tubular preform enters the opening, and the air pump is used to inject air to expand the soft airbag and clamp the tubular preform. Step 3: The driving mechanism of the film clamping device is moved upward, pulling the upper end of the tubular preform film to the upper part of the vertical tube; Step 4: The drive unit continues to move upward, squeezing the first spring, reducing the horizontal angle of the push rod, causing the telescopic rod to extend outward, straightening the plastic strip, engaging the arc-shaped teeth with the second rack, flipping the plastic strip so that the opening faces upward, compressing the second and third springs to send the tubular blank into the roller device; Step 5: Expel the air from the soft airbag, loosen the fixation on the tubular preform, and roll the tubular preform into the roller device to form a linear film; Step 6: Move the drive unit downwards and reset the membrane clamping mechanism to the middle of the vertical tube.

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