Plastic film blowing forming device and method capable of preventing film bubble wrinkles from being uneven

Abstract

The invention relates to the technical field of plastic films, in particular to a plastic film blowing forming device and method capable of preventing film bubble wrinkles from being uneven. Comprising a film blowing mechanism and a water cooling mechanism arranged below the film blowing mechanism, the water cooling mechanism comprises a water cooling shell and a water jacket, in the film blowing state, a water cooling gap is formed between film bubbles and the water jacket, a drainage part is arranged on the inner wall of the water jacket, a stabilizing assembly is arranged on the water cooling shell, and the stabilizing assembly comprises a pull-down structure and a pressure stabilizing structure matched with the pull-down structure. And a linkage structure is arranged between the pull-down structure and the pressure stabilizing structure. Through the synergistic effect of the pull-down structure and the pressure stabilizing structure, the whole water jacket is kept in a uniform tensioning state, the consistency of water cooling gaps is maintained, it is ensured that spiral lines are attached to the surface of a film bubble all the time, the wrinkle defect of the film bubble caused by uneven cooling is avoided, and the film forming quality is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic films, and in particular to a plastic film blowing molding device and method for preventing uneven wrinkles of film bubbles. Background Art

[0002] During the blown film forming process of plastic films, the stability and uniformity of the film bubble directly impact the quality of the finished film. Currently, common bubble cooling methods are categorized as upward air cooling and downward water cooling. While water cooling theoretically outperforms air cooling due to its higher cooling efficiency, particularly in high-temperature and humid environments, ensuring sufficient contact between the cooling water and the film bubble for effective cooling requires the bubble to be in close contact with the water-cooling fixture.

[0003] However, after water cooling, residual liquid will flow down the bubble surface, forming scattered, unevenly distributed strips of water. This phenomenon leads to uneven heat dissipation and stress on the bubble surface, causing subtle wrinkles and local brightness differences in the bubble, further affecting the quality and aesthetics of the film.

[0004] The currently disclosed Chinese patent authorization announcement number CN118683049B is a plastic film forming device, which includes a bracket, a co-extrusion blown film die head fixed on the upper end of the bracket, and the co-extrusion blown film die head is connected to an external screw extruder. After the raw materials are added to the screw extruder, they are transported to the co-extrusion blown film die head and extruded into film bubbles of required size along the internal set shape. A variable diameter water cooling mechanism is provided under the co-extrusion blown film die head, and the variable diameter water cooling mechanism is fixed in the middle of the bracket. The variable diameter water cooling mechanism is used to cool the film bubbles produced in the co-extrusion blown film die head so that they can be quickly shaped and improve the mechanical properties and optical properties of the film. Cooling water is connected to the outside of the variable diameter water cooling mechanism. During the production process, cooling water continuously flows into the variable diameter water cooling mechanism. The variable diameter water cooling mechanism can adjust the diameter of its center hole according to the diameter of the film bubble to make it adapt to the size of the film bubble, so that the cooling water continuously acts on the surface of the film bubble.

[0005] According to the above patent, the diameter of the center hole of the variable diameter water cooling mechanism of the patent can be adjusted to different values ​​to adapt to membrane bubbles of different sizes, and the spray shaping mechanism therein can rotate and spray the surface of the membrane bubble to make the heat dissipation of the membrane bubble surface more uniform, reduce the interference of the upper cooling water on the membrane bubble surface, and improve the performance of the membrane bubble surface.

[0006] However, in the process of cooling the bubble surface by the spray shaping mechanism, after the spray droplets contact the bubble surface, they are affected by factors such as surface tension, cooling airflow disturbance and the bubble's own movement, and the bubble will vibrate during the cooling process. If the bubble vibrates during the cooling process, the cooling droplets sprayed on its surface will not be evenly spread. It is still easy to form scattered strips of water flow with varying widths. This leads to differences in the cooling rate in local areas, which causes uneven distribution of surface tension of the film. This may further affect the deformation behavior of the film during traction and stretching, resulting in slight wrinkles and lateral thickness fluctuations after the film is wound. Although the spray droplets are small and the single-point impact force is weak, the non-uniform flow path formed on the surface still has a significant impact on the surface quality of the film.

[0007] Therefore, to improve the cooling effect of the film bubble, a plastic film blowing molding device is needed to prevent uneven bubble wrinkles. Direct contact water cooling can be used to evenly coat the outer surface of the film bubble with cooling water, ensuring stable, continuous and sufficient contact between the film bubble and the cooling water. Summary of the Invention

[0008] In response to the problems existing in the existing technology, a plastic film blown film forming device is provided to prevent uneven wrinkles in the film bubble. Through the synergistic effect of the pull-down structure and the pressure-stabilizing structure, the water jacket as a whole is kept in a uniform tension state, the consistency of the water cooling gap is maintained, and the spiral pattern is ensured to always fit the surface of the film bubble, avoiding wrinkle defects in the film bubble due to uneven cooling, and improving the film forming quality.

[0009] In order to solve the problems of the prior art, the present invention provides a plastic film blowing forming device for preventing uneven wrinkles of film bubbles, comprising a film blowing mechanism and a water-cooling mechanism arranged thereunder, the water-cooling mechanism comprising a water-cooling shell and a water jacket arranged thereon for the film bubble to pass through, in the film blowing state, a water-cooling gap is formed between the film bubble and the water jacket for cooling water to flow from top to bottom, the inner wall of the water jacket has a drainage portion that fits with the outer surface of the film bubble to maintain uniform flow of cooling water, the upper end of the water jacket is fixedly connected to the water-cooling shell, the lower end of the water jacket extends vertically downward, the water-cooling shell is provided with a water inlet and a water outlet at positions corresponding to the upper and lower ends of the water jacket, respectively, the water-cooling shell The bottom is provided with a rubber base support that can fit tightly with the outer surface of the membrane bubble to prevent cooling water leakage. The rubber base support has a drainage channel connecting the water cooling gap and the water outlet. The water-cooling shell is also provided with a stabilizing component for maintaining stable operation of the water jacket. The stabilizing component includes a pull-down structure connected to the lower end of the water jacket and a pressure-stabilizing structure that acts synchronously with the upper half of the water jacket. A linkage structure is provided between the pull-down structure and the pressure-stabilizing structure. When the water jacket is pulled downward by the pull-down structure, the pressure-stabilizing structure is in a synchronous upward state under the action of the linkage structure, so that the water jacket forms an annular cooling area around the membrane bubble for uniform and stable flow of cooling water.

[0010] Preferably, the linkage structure has an active part arranged on the pull-down structure and a driven part cooperating with the pressure-stabilizing structure. The active part and the driven part respectively have a force-applying point and a force-receiving point in contact with each other. When the pull-down structure moves downward, the driven part gradually applies an upward force to the pressure-stabilizing structure under the action of the active part, so that the upper and lower parts of the water jacket remain coordinated and tensioned.

[0011] Preferably, the pressure stabilizing structure has an upper ring sleeve coaxial with the water jacket, and the inner side of the upper ring sleeve is provided with a plurality of pressure stabilizing rings that fit tightly with the outer surface of the water jacket along its axial direction, and the outer side of the upper ring sleeve is provided with a plurality of balls, and the water-cooling shell is provided with a vertical slide rail that cooperates with the corresponding balls.

[0012] Preferably, the pull-down structure has a lower ring sleeve that is coaxial with the water jacket, and the lower end of the water jacket is fixedly connected to the lower ring sleeve. The lower ring sleeve is slidably sleeved on the rubber base support. The water jacket, the lower ring sleeve, the rubber base support and the membrane bubble together form the water-cooling gap. The water-cooling shell is provided with a pull-down driver for driving the lower ring sleeve to move downward.

[0013] Preferably, an upper compression spring is provided between the upper ring sleeve and the water-cooled shell, and a lower compression spring is provided between the lower ring sleeve and the rubber base. When the upper ring sleeve and the lower ring sleeve are away from each other, the upper compression spring and the lower compression spring are in a synchronous compression state. At this time, the water body is in a deformed and stretched state. Conversely, the water jacket gradually returns to its initial state.

[0014] Preferably, the drainage portion of the inner wall of the water jacket is a spiral pattern that can expand and contract synchronously with the deformation of the water jacket. When the bubble passes through the water jacket, the spiral pattern is in close contact with the outer surface of the bubble, allowing the cooling water to flow from top to bottom along the spiral path.

[0015] Preferably, the water jacket is provided with a pressure-maintaining airbag for further maintaining the stability of the water jacket, and the water-cooling shell is provided with an air pipe connected to the pressure-maintaining airbag. When the pressure-maintaining airbag expands to contact the water jacket, the water jacket is in an elastically supported state, making the water jacket more stable.

[0016] Preferably, the follower has a first extension portion in contact with the active member and a second extension portion in contact with the lower end of the upper ring sleeve. The follower is rotatably arranged on the water-cooled shell. When the active member moves downward with the lower ring sleeve, the first extension portion is in a downward swing state under the pressure of the active member, and the second extension portion is in an upward swing state.

[0017] Preferably, the pull-down drive has a guide rod and a guide sleeve, and a guide rod is vertically provided around the lower ring sleeve. Each guide rod is sleeved with a guide sleeve provided on the water-cooled shell. When compressed gas flows into the guide sleeve from top to bottom, the guide rod is in a compressed downward state inside the guide sleeve.

[0018] The present invention also provides a plastic film blown film forming method for preventing uneven bubble wrinkles, comprising the following steps: S1. The plastic melt is extruded and inflated to form a film bubble through the film blowing mechanism, so that the film bubble is continuously pulled downward and is in a stable expansion state; S2, cooling water enters from the water inlet on the upper part of the water-cooled shell, flows along the spiral pattern in the annular water-cooling gap formed between the water jacket and the membrane bubble, and performs circumferential uniform cooling; S3. The pull-down structure and the pressure-stabilizing structure work together to keep the water jacket in a tensioned state, maintain the consistency of the water-cooling gap, and provide elastic support to the water jacket through the pressure-maintaining airbag, further stabilizing the water jacket. S4: The film bubble in the cooling process is continuously pulled downward, and the film is evenly rolled into a finished product, completing the entire film blowing process.

[0019] Compared with the prior art, the present invention has the following advantages: 1. The present invention prevents residual liquid from flowing downward through a rubber base, preventing the surface of the bubble from heat dissipating and unevenly stressed, resulting in fine wrinkles. And through the coordinated work of the pull-down structure and the pressure-stabilizing structure, forces in opposite directions are simultaneously applied to the upper and lower ends of the water jacket, so that the water jacket as a whole remains in a uniform tension state, thereby maintaining the consistency of the water-cooling gap around the bubble. It effectively prevents uneven distribution of cooling water due to displacement, looseness or deformation of the water jacket, ensuring a stable and uniform cooling process; at the same time, the coordinated action of the pull-down structure and the pressure-stabilizing structure is achieved through the linkage structure, which improves the adaptability of the water jacket to bubble deformation, keeps the drainage part in close contact with the bubble, avoids the defect of wrinkles in the bubble caused by uneven cooling, and improves the quality stability of film forming; 2. The present invention uses spiral lines on the inner wall of the water jacket that can expand and contract synchronously with deformation, ensuring that it always fits tightly with the outer surface of the film bubble, forming a stable and continuous cooling water flow channel and maintaining the consistency of the water-cooling gap. The spiral water flow path formed effectively prolongs the contact time between the cooling water and the film bubble, improving the heat exchange efficiency, while avoiding water short-circuiting or stagnation, making the cooling process more uniform and stable. This improves the uniformity of film bubble cooling and enhances the adaptability of the film bubble, thereby ensuring the stability of film forming quality. 3. This invention utilizes a pressure-retaining airbag on the outside of the water jacket, utilizing the uniform pressure generated by gas expansion to elastically support the water jacket, ensuring it maintains a stable fit with the bubble during the cooling process. This effectively prevents the water jacket from shifting or shaking due to external vibrations, water flow impacts, or fluctuations in bubble operation, thereby indirectly stabilizing the bubble and improving the cooling effect. Furthermore, the pressure-retaining airbag possesses elastic deformation capability, compressing or recovering synchronously with the deformation of the water jacket, absorbing dynamic stress, further enhancing the stability and adaptability of the water jacket's operation, and ensuring a continuous and uniform cooling process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the three-dimensional structure of a plastic film blowing and forming device for preventing uneven wrinkles of film bubbles according to the present invention; Figure 2 This is a partial three-dimensional structural cross-sectional view of a plastic film blowing and forming device for preventing uneven bubble wrinkles according to the present invention; Figure 3 It is a partial planar cross-sectional view of a plastic film blowing and forming device for preventing uneven bubble wrinkles according to the present invention; Figure 4 The present invention Figure 3 A magnified schematic diagram of point A; Figure 5 This is a partial three-dimensional structural section of a water jacket, film bubble and stabilizing component of a plastic film blown film forming device for preventing uneven film bubble wrinkles of the present invention. Figure 1 ; Figure 6 It is a partial planar cross-sectional view of a water jacket, a film bubble and a stabilizing component of a plastic film blown film forming device for preventing uneven film bubble wrinkles according to the present invention; Figure 7 This is a partial three-dimensional structural section of a water jacket, film bubble and stabilizing component of a plastic film blown film forming device for preventing uneven film bubble wrinkles of the present invention. Figure 2 ; Figure 8 This is a partial three-dimensional structural cross-sectional view of a water jacket and a stabilizing component of a plastic film blown film forming device for preventing uneven bubble wrinkles according to the present invention; Figure 9 This is a partial three-dimensional structural section of a water jacket, film bubble and stabilizing component of a plastic film blown film forming device for preventing uneven film bubble wrinkles of the present invention. Figure 3 ; Figure 10 The present invention Figure 9 Enlarged schematic diagram of point B.

[0021] The numbers in the figure are: 1. membrane bubble; 2. water-cooling shell; 21. water inlet; 22. water outlet; 3. water jacket; 31. water-cooling gap; 32. spiral pattern; 33. pressure-maintaining airbag; 331. air pipe; 4. rubber base; 41. drainage channel; 5. stabilizing component; 51. pull-down structure; 511. lower ring sleeve; 5111. lower compression spring; 512. pull-down drive; 5121. guide rod; 5122. guide sleeve; 52. pressure-stabilizing structure; 521. upper ring sleeve; 5211. upper compression spring; 522. pressure-stabilizing ring; 523. ball; 5231. vertical slide rail; 53. linkage structure; 531. active part; 532. driven part; 5321. first extension part; 5322. second extension part. DETAILED DESCRIPTION

[0022] In order to further understand the features, technical means, specific objectives and functions achieved by the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] See also Figure 1-Figure 7 As shown, a plastic film blown film forming device for preventing uneven wrinkles of film bubbles comprises a film blowing mechanism and a water cooling mechanism arranged thereunder, the water cooling mechanism comprises a water cooling shell 2 and a water jacket 3 arranged thereon for the film bubble 1 to pass through, in the film blowing state, a water cooling gap 31 is formed between the film bubble 1 and the water jacket 3 for cooling water to flow from top to bottom, the inner wall of the water jacket 3 has a drainage portion that fits with the outer surface of the film bubble 1 to maintain uniform flow of cooling water, the upper end of the water jacket 3 is fixedly connected to the water cooling shell 2, and the lower end of the water jacket 3 extends vertically downward, the water cooling shell 2 is provided with a water inlet 21 and a water outlet 22 at positions corresponding to the upper and lower ends of the water jacket 3, respectively, and the bottom of the water cooling shell 2 is provided with a water outlet 22 that can fit with the outer surface of the film bubble 1 A rubber base support 4 is provided which fits tightly to prevent leakage of cooling water. The rubber base support 4 has a drainage channel 41 connecting the water-cooling gap 31 and the water outlet 22. The water-cooling shell 2 is also provided with a stabilizing component 5 for maintaining stable operation of the water jacket 3. The stabilizing component 5 includes a pull-down structure 51 connected to the lower end of the water jacket 3 and a pressure-stabilizing structure 52 which acts synchronously on the upper half of the water jacket 3 in cooperation with the pull-down structure 51. A linkage structure 53 is provided between the pull-down structure 51 and the pressure-stabilizing structure 52. When the water jacket 3 is tightened downward by the pull-down structure 51, the pressure-stabilizing structure 52 is in a synchronous upward state under the action of the linkage structure 53, so that the water jacket 3 forms an annular cooling area around the membrane bubble 1 for uniform and stable flow of cooling water.

[0024] The film blowing mechanism is not shown in the figures.

[0025] While the pull-down structure 51 pulls the water jacket 3 downward, the pressure-stabilizing structure 52 simultaneously moves upward. This is to create symmetrical and coordinated forces at the upper and lower ends of the water jacket 3, thereby maintaining overall tension on the water jacket 3 and uniformly maintaining the consistency of the water-cooling gap 31. This effectively balances the tension distribution of the water jacket 3 during the cooling process, preventing uneven water-cooling gap 31 caused by local loosening or offset, ensuring a stable and uniform flow of cooling water around the membrane bubble 1, and ultimately achieving a stable shape of the membrane bubble 1 during the cooling process, avoiding defects such as uneven wrinkles.

[0026] Specifically, when the film bubble 1 is in an expanded state during the blown film molding process, it is susceptible to deformation or surface vibration due to the multiple influences of internal air pressure, temperature fluctuations, and external airflow. This instability directly leads to uneven cooling gaps 31 between the water jacket 3 and the film bubble 1, causing localized differences in cooling rates. If the cooling water flows unevenly, it will be unevenly distributed on the surface of the film bubble 1, ultimately causing quality defects such as uneven wrinkles.

[0027] During the specific forming process, the film bubble 1 is pulled downward by the film blowing mechanism and continues to expand. After entering the water jacket 3 area in the water-cooled shell 2, it begins to cool. The film continues to pass through the water-cooled shell 2 without stopping during the pulling process. At this time, cooling water is injected from the water inlet 21 on the upper part of the water-cooled shell 2, and flows evenly from top to bottom along the annular water-cooling gap 31 formed between the water jacket 3 and the film bubble 1. Finally, the water flow is guided by the rubber base 4 to be discharged smoothly from the water outlet 22. At this time, the stabilizing component 5 applies a controlled reverse force to the upper and lower ends of the water jacket 3 during its operation, so that the water jacket 3 as a whole remains in a stable tension state, indirectly stabilizing the film bubble 1 and preventing it from vibrating due to the influence of external airflow or during the pulling process.

[0028] The water jacket 3 is made of a flexible and elastic material, adapting to the expansion of the membrane bubble 1 and deforming accordingly, ensuring a close fit with the surface of the membrane bubble 1 while maintaining the consistency of the water-cooling gap 31. The film continuously passes through the water jacket 3 and possesses strong toughness. Furthermore, the water-cooling gap 31 is open, with upward and downward circulation, and flows in the direction of film traction. This allows the cooling water to flow evenly across the surface of the membrane bubble 1 without forming a closed pressure environment. This ensures uniformity and stability during the cooling process, preventing changes in the water-cooling gap 31 or wrinkles in the membrane bubble 1 due to water pressure.

[0029] The rubber base 4 is used to fit tightly with the expanded membrane bubble 1, blocking most of the cooling water from flowing down with the membrane bubble 1. The inner wall surface of the rubber base 4 has a hydrophilic coating, which enhances the sealing effect of the fit with the membrane bubble 1 and reduces the slipping of water droplets. Although the fit between the rubber base 4 and the membrane bubble 1 helps to guide the water flow and reduce leakage, when the membrane bubble 1 vibrates frequently, it will still cause a large amount of cooling water to flow out from the gap between the rubber base 4 and the membrane bubble 1. Therefore, in order to overcome this problem, a stabilizing component 5 is provided to maintain the stability of the water jacket 3. By synchronously adjusting the tension at the upper and lower ends of the water jacket 3, it is ensured that the water jacket 3 remains in a stable tensioned state. Since the water jacket 3 is sleeved on the membrane bubble 1, the membrane bubble 1 therein is indirectly stabilized. The effect of stabilizing the membrane bubble 1 is achieved, so that the fit between the membrane bubble 1 and the rubber base 4 remains stable, avoiding the situation where the cooling water flows down from the rubber base 4 in large quantities due to the shaking or deformation of the membrane bubble, and instead flows out from the water outlet 22 along the rubber base 4.

[0030] A drying mechanism, surrounding the film bubble 1, is located beneath the rubber base 4 to promptly dry out any traces of cooling water that might leak, preventing it from flowing downward. This drying mechanism utilizes low-temperature hot air, combined with a low wind speed and oblique, circular airflow pattern, ensuring that the hot air evenly covers the surface of the film bubble 1, effectively drying out any traces of cooling water that might leak while avoiding impact or thermal deformation of the film bubble 1. This drying mechanism is not shown in the figure.

[0031] Alternatively, a ring of absorbent sponge or polymer absorbent material surrounding the membrane bubble 1 is provided below the rubber base 4 to physically absorb a small amount of cooling water leaking from the rubber base 4 to prevent it from continuing to flow down.

[0032] When cooling water flows through the annular water-cooling gap 31 between the water jacket 3 and the film bubble 1, the rubber base 4 can effectively guide the water flow to be discharged smoothly from the water outlet 22, preventing the downstream cooling water from forming scattered strips of water with varying widths on the surface of the film bubble 1. Irregular water flow may cause local differences in cooling rates, thereby causing uneven stress distribution on the film surface, and ultimately causing wrinkles. By ensuring that the cooling water flows out evenly and orderly, it not only helps maintain the uniformity of the surface temperature of the film bubble 1, but also reduces the potential interference with the film bubble 1 caused by irregular cooling water flow, further avoiding the possibility of wrinkles on the film surface.

[0033] When the stabilizing assembly 5 operates, the pull-down structure 51 pulls the lower end of the water jacket 3 downward, keeping it vertical and stable. Simultaneously, the linkage structure 53 transmits this movement to the pressure-stabilizing structure 52, causing it to move upward synchronously, exerting upward pressure on the upper half of the water jacket 3. This synchronized, opposing force exerted from top to bottom keeps the water jacket 3 in a tensioned state, as if clamped around the film bubble 1, forming a uniform and stable annular cooling zone.

[0034] Regardless of how slightly the film bubble 1 deforms during the film blowing process due to pressure or temperature fluctuations, the drainage portion of the water jacket 3 maintains contact with the film bubble 1 and a consistent gap. With the water jacket 3 in a tensioned state, the film bubble 1 is stabilized, improving the cooling effect and preventing wrinkles on the film bubble 1 surface caused by uneven distribution of cooling water.

[0035] It effectively avoids the common problems of loose, eccentric or local collapse of the water jacket 3 in traditional cooling methods. Once the water jacket 3 is offset in any position, the cooling gap will be locally reduced or expanded, resulting in uneven cooling water flow and faster or slower cooling speed in local areas. The uneven cooling process will form a thermal stress concentration area on the surface of the membrane bubble 1, which will induce defects such as wrinkles and uneven thickness. Since the water jacket 3 is always in a tensioned and stable state, the cooling water can flow smoothly at a constant flow rate throughout the circumference of the membrane bubble 1, thereby ensuring that the cooling rate of each part of the membrane bubble 1 is consistent, reducing thermal stress differences, and fundamentally preventing the occurrence of uneven wrinkles in the membrane bubble 1.

[0036] See also Figure 2-Figure 7 and Figure 10As shown, the linkage structure 53 has an active member 531 arranged on the pull-down structure 51 and a driven member 532 cooperating with the pressure-stabilizing structure 52. The active member 531 and the driven member 532 respectively have a force-applying point and a force-receiving point in contact with each other. When the pull-down structure 51 moves downward, the driven member 532 gradually applies an upward force to the pressure-stabilizing structure 52 under the action of the active member 531, so that the upper and lower parts of the water jacket 3 remain coordinated and tensioned.

[0037] When the stabilizing assembly 5 begins operating, the pull-down structure 51, driven by external power, moves downward, simultaneously driving the active member 531 mounted thereon downward. At this point, contact is established between the active member 531 and the passive member 532. As the active member 531 moves downward, its point of force application gradually pushes against the point of force received by the passive member 532, causing the passive member 532 to move upward.

[0038] Since the upper end of the driven member 532 is connected to the pressure stabilizing structure 52, it begins to exert an upward force on the pressure stabilizing structure 52 after receiving the pushing force of the active member 531. This ensures that the pressure stabilizing structure 52 can exert an appropriate supporting force on the upper half of the water jacket 3, maintaining a stable tension state in the vertical direction and keeping the water-cooling gap 31 consistent.

[0039] Through the coordinated coordination between the active element 531 and the driven element 532, a coordinated force pattern is formed at the upper and lower ends of the water jacket 3. The lower portion is pulled downward, while the upper portion is pulled upward. These two opposing but matching forces act together on the water jacket 3, maintaining a uniform tension throughout. This effectively prevents the water jacket 3 from significant deflection or relaxation due to water flow impact or vibration of the membrane bubble 1 during the cooling process, thereby ensuring that the water-cooling gap 31 remains uniform.

[0040] See also Figure 2-Figure 8 As shown, the pressure stabilizing structure 52 has an upper ring sleeve 521 coaxial with the water jacket 3, and the inner side of the upper ring sleeve 521 is provided with a plurality of pressure stabilizing rings 522 that fit tightly with the outer surface of the water jacket 3 along its axial direction, and the outer side of the upper ring sleeve 521 is provided with a plurality of balls 523, and the water-cooling shell 2 is provided with vertical slide rails 5231 that cooperate with the corresponding balls 523.

[0041] When the pressure-stabilizing structure 52 begins to operate, the upper ring 521 moves upward in the vertical direction under the action of the linkage structure 53. The contact between the balls 523 and the slide rails provides a stable guide for the upper ring 521, allowing it to remain stable and free of deviation during its ascent. This not only reduces frictional resistance during movement but also improves the flexibility and precision of the pressure-stabilizing structure 52, ensuring that the upper ring 521 can accurately adjust its position according to the movement of the linkage structure 53.

[0042] During the moving-down process of the upper ring sleeve 521, since the upper ring sleeve 521 is coaxial with the water jacket 3, the movement track of the upper ring sleeve 521 is consistent with the center line of the water jacket 3, so that the uniform force on the water jacket 3 is maintained by the stabilizing ring 522. The overall tension state of the water jacket 3 during the cooling process is effectively ensured, and the change of the water cooling gap 31 is avoided, thereby providing reliable support conditions for the uniform cooling and stable forming of the membrane bubble 1.

[0043] Referring to Figure 2-Figure 5 As shown in the drawings, the lower pull structure 51 has a lower ring sleeve 511 coaxial with the water jacket 3, the lower end of the water jacket 3 is fixedly connected with the lower ring sleeve 511, the lower ring sleeve 511 is slidably sleeved on the rubber bottom support 4, the water jacket 3, the lower ring sleeve 511, the rubber bottom support 4 and the membrane bubble 1 jointly form the water cooling gap 31, and the water cooling shell 2 is provided with a lower pull driver 512 for driving the lower ring sleeve 511 to move downward.

[0044] When the lower pull structure 51 starts to operate, the lower ring sleeve 511 moves downward along the vertical direction under the action of the lower pull driver 512 on the water cooling shell 2. Since the lower ring sleeve 511 is coaxial with the water jacket 3, the movement track of the lower ring sleeve 511 is consistent with the center of the water jacket 3, so that the overall deviation of the water jacket 3 caused by eccentric movement is avoided. With the downward movement of the lower ring sleeve 511, the water jacket 3 is also synchronously pulled downward, so that the overall vertical state and tension of the water jacket 3 are maintained.

[0045] During the continuous moving-down process of the lower ring sleeve 511, the rubber bottom support 4 remains stationary, and the drainage channel 41 in the rubber bottom support 4 continuously guides the cooling water from the water cooling gap 31 to the water outlet 22, so that the cooling process is continuously and stably carried out.

[0046] Since the water jacket 3, the lower ring sleeve 511, the rubber bottom support 4 and the membrane bubble 1 jointly form the water cooling gap 31, when the lower ring sleeve 511 is driven to move downward, the water cooling gap 31 is uniformly maintained around the entire membrane bubble 1. During the downward flow of the cooling water, there is no local contraction or expansion phenomenon, so that the stress difference on the surface of the membrane bubble 1 caused by the uneven distribution of the cooling water is effectively prevented, and the shape stability of the membrane bubble 1 during the cooling and forming process is further ensured.

[0047] Referring to Figure 3-Figure 8 As shown in the drawings, the upper ring sleeve 521 and the water cooling shell 2 are provided with an upper compression spring 5211, and the lower ring sleeve 511 and the rubber bottom support 4 are provided with a lower compression spring 5111. When the upper ring sleeve 521 and the lower ring sleeve 511 move away from each other, the upper compression spring 5211 and the lower compression spring 5111 are in a synchronous compression state, at this time the water body is in a deformed and stretched state, and vice versa, the water jacket 3 gradually returns to the initial state.

[0048] As the upper and lower annular sleeves 521 and 511 begin to move away from each other, the upper and lower compression springs 5211 and 5111 simultaneously enter a compressed state. During this process, the water jacket 3, the structural component connecting the upper and lower annular sleeves 521 and 511, is stretched and deformed, placing the entire structure in a state of tension. This allows the drainage portion of the water jacket 3 to more stably adhere to the outer surface of the membrane bubble 1, further improving the uniform flow of cooling water in the water-cooling gap 31 and preventing localized uneven cooling or water flow disturbances caused by a loosening of the water jacket 3.

[0049] When cooling water is not flowing, the upper compression spring 5211 and the lower compression spring 5111 release the stored energy, and the water jacket 3 returns to its initial state to release the stress accumulated inside it, and drives the upper ring sleeve 521 and the lower ring sleeve 511 to move closer to each other, preventing long-term stress from causing material fatigue deformation or sealing failure, and also helping the water jacket 3 to accurately fit and adapt to the shape of the membrane bubble 1 again when it is started next time.

[0050] See also Figure 3-Figure 10 As shown, the drainage portion of the inner wall of the water jacket 3 is specifically a spiral pattern 32 that can expand and contract synchronously with the deformation of the water jacket 3. When the membrane bubble 1 passes through the water jacket 3, the spiral pattern 32 is in a tight fit with the outer surface of the membrane bubble 1, so that the cooling water can flow from top to bottom along the spiral path.

[0051] When the membrane bubble 1 enters the water jacket 3 and begins cooling, the spiral pattern 32 maintains close contact with the outer surface of the membrane bubble 1 while the water jacket 3 is tensioned, forming a continuous and regular cooling water flow path. Cooling water enters the water inlet 21 at the top of the water-cooled housing 2 and flows in a spiral pattern from top to bottom, following the path guided by the spiral pattern 32. This prolongs the contact time between the cooling water and the membrane bubble 1, enhancing heat exchange efficiency while preventing water short-circuiting or localized stagnation, ensuring a uniform and stable cooling process.

[0052] When the water jacket 3 deforms, stretches, or returns to its original shape, the spiral lines 32 also extend or retract synchronously, maintaining a good fit with the surface of the film bubble 1. This effectively ensures that the cooling water flows stably along the set path throughout the film blowing process, further improving the uniformity of the film bubble 1's cooling and the stability of the molding quality.

[0053] The contact of spiral lines 32 with the surface of bubble 1 does not result in spiral wrinkles in the film. This is because during the blown film forming process, bubble 1 is only in an expanded state during the cooling process and gradually returns to a flat film during the subsequent traction and winding stages, rather than being in a constant expanded state. During this process, the film is continuously subjected to longitudinal traction, exhibiting good ductility and resilience, allowing it to quickly return to a flattened shape after leaving the water jacket 3.

[0054] Furthermore, the spiral lines 32 are formed on the inner wall of the flexible water jacket 3, and their structure possesses a certain degree of elasticity, allowing them to adapt to the changing shape of the bubble 1 without causing any rigid pressure on the surface of the bubble 1. Furthermore, the film itself possesses a certain degree of toughness, and residual surface deformation may only occur when the bubble 1 overexpands to the point of near-rupture, a condition that should be avoided during normal production, as overexpansion is not tolerated. Therefore, under normal traction, cooling, and material properties, the film will not develop spiral wrinkles due to contact with the spiral lines 32, instead achieving more uniform cooling and more stable molding quality.

[0055] Specifically, in order to ensure that the cooling gap 31 between the external water jacket 3 and the membrane bubble 1 is uniform, the water jacket 3 is flexible and elastic, and the inner wall of the water jacket 3 is provided with spiral patterns 32. When the membrane bubble 1 expands and is continuously pulled through the water jacket 3, the water jacket 3 deforms due to its elastic properties and adapts to the expansion state of the membrane bubble 1, and always maintains a close fit with the surface of the membrane bubble 1.

[0056] During the process of the film bubble 1 passing through the water jacket 3, compared with the rigid contact with the film bubble 1 in the prior art, the water jacket 3 not only provides stable support, but also prevents the film bubble 1 from being subjected to excessive pressure after expansion, thereby preventing wrinkles on the film surface due to friction.

[0057] Furthermore, the pull-down structure 51 and the pressure-stabilizing structure 52 in the stabilizing assembly 5 act synchronously on the upper and lower ends of the water jacket 3. When the pull-down structure 51 pulls the water jacket 3 downward, the pressure-stabilizing structure 52 simultaneously pulls it upward, keeping the entire water jacket 3 in a tensioned state. This ensures the vertical stability of the water jacket 3 and reduces high-frequency vibrations caused by external airflow on the film bubble 1. This not only maintains the consistency of the cooling gap 31 but also ensures the shape stability of the film bubble 1 during the molding process.

[0058] See also Figure 3-Figure 8 and Figure 10 As shown, the water jacket 3 is provided with a pressure-maintaining airbag 33 for further maintaining the stability of the water jacket 3, and the water-cooling shell 2 is provided with an air pipe 331 connected to the pressure-maintaining airbag 33. When the pressure-maintaining airbag 33 expands to contact the water jacket 3, the water jacket 3 is in an elastically supported state, making the water jacket 3 more stable.

[0059] When the pressure-maintaining airbag 33 starts working, the air pipe 331 on the water-cooled shell 2 delivers gas to the interior thereof, gradually expanding the pressure-maintaining airbag 33. As the volume of the pressure-maintaining airbag 33 increases, its outer surface gradually approaches and eventually contacts the outer wall of the water jacket 3, forming an elastic support layer.

[0060] When the pressure-maintaining airbag 33 is fully inflated and fits tightly against the water jacket 3, the air pressure inside the pressure-maintaining airbag 33 applies a uniform radial support force to the water jacket 3. This creates a stable force environment around the water jacket 3, effectively preventing the water jacket 3 from deflecting or shaking due to external vibrations, water flow impacts, or unstable operation of the membrane bubble 1.

[0061] At the same time, the pressure-maintaining airbag 33 has a certain elastic deformation capability, and can be appropriately compressed or restored when subjected to deformation of the water jacket 3 or external disturbance, thereby absorbing dynamic stress and maintaining the stability of the water jacket 3 operation.

[0062] Furthermore, the pressure-maintaining airbag 33 provides additional radial support to the water jacket, absorbing dynamic stress and ensuring the stability of the film bubble 1 as it continues to pass through the water jacket 3. Even if the film bubble 1 undergoes expansion and contraction changes during the film blowing process, it can achieve uniform cooling and maintain a high-quality film surface.

[0063] See also Figure 3-Figure 5 and Figure 10 As shown, the follower 532 has a first extension portion 5321 in contact with the active member 531 and a second extension portion 5322 in contact with the lower end of the upper ring sleeve 521. The follower 532 is rotatably arranged on the water-cooled shell 2. When the active member 531 moves downward with the lower ring sleeve 511, the first extension portion 5321 is in a downward swing state under the pressure of the active member 531, and the second extension portion 5322 is in an upward swing state.

[0064] When the lower ring 511 begins to move downward under the action of the pull-down actuator 512, the active member 531 moves downward in tandem. At this point, the passive member 532, in contact with the active member 531, begins a chain reaction. As the active member 531 gradually presses down on the first extension 5321, the pressure exerted on it causes the passive member 532 to rotate about its axis. At this point, the force acting on the first extension 5321 is directed downward.

[0065] At the same time, the second extension 5322 swings upward and applies an upward thrust to the lower end of the upper ring 521, driving the upper ring 521 to rise vertically, forming a synchronous motion in the opposite direction of the lower ring 511. This achieves coordinated tensioning of the upper and lower ends of the water jacket 3, thereby maintaining a stable support state of the water jacket 3 around the membrane bubble 1 and ensuring a uniform and continuous cooling process.

[0066] See also Figure 3 and Figure 5As shown, the pull-down drive 512 has a guide rod 5121 and a guide sleeve 5122. A guide rod 5121 is vertically provided around the lower ring sleeve 511, and each guide rod 5121 is sleeved with a guide sleeve 5122 provided on the water-cooled shell 2. When compressed gas enters the guide sleeve 5122 from top to bottom, the guide rod 5121 is in a compressed downward state inside the guide sleeve 5122.

[0067] The pull-down driver 512 pulls the water jacket 3 downward to ensure that the water jacket 3 is more stable after being fitted with the membrane bubble 1, and to limit the unstable shaking of the membrane bubble 1 in the water jacket 3, thereby ensuring that the water jacket 3 is completely fitted with the membrane bubble 1.

[0068] This is achieved by: when compressed gas is passed from top to bottom into the guide sleeve 5122, the gas pressure directly acts on the guide rods 5121, causing them to be compressed within the guide sleeve 5122 and move smoothly downward in the vertical direction. Each guide rod 5121 is fixedly connected to the lower ring 511. When the multiple guide rods 5121 around the lower ring 511 are simultaneously pushed by uniform pressure, they work together to ensure that the lower ring 511 maintains a smooth and consistent motion throughout the entire driving process.

[0069] The multi-point stamping method not only ensures the stable descent of the lower ring 511, but also prevents deflection or jamming caused by uneven force on one side. As compressed gas is continuously input, the guide rods 5121 gradually drive the lower ring 511 and the connected water jacket 3 downward, gradually stretching the water jacket 3 downward, thereby making the water jacket 3 more stable in close contact with the film bubble 1.

[0070] In addition, by adjusting the pressure of the input gas, the speed and force of pulling down the lower end of the water jacket 3 can be accurately controlled, thereby ensuring that the water jacket 3 always maintains appropriate tension during the entire cooling process to avoid damage due to sudden force. At the same time, it also ensures that the water cooling gap 31 between the water jacket 3 and the membrane bubble 1 is uniform and consistent, achieving an efficient and stable cooling effect.

[0071] The lower ring sleeve 511 is precisely controlled by arranging a pressure sensor in combination with a linear displacement sensor, which are not shown in the figure.

[0072] The pressure sensor is arranged between the guide rod 5121 and the guide sleeve 5122. When the guide rod 5121 moves relative to the guide sleeve 5122, the pressure sensor senses the pressure state of the guide rod 5121, thereby determining the pressure of the gas pushing the guide rod 5121 to move.

[0073] The linear displacement sensor is fixedly arranged on the water-cooling shell 2 and the pull wire therein is fixedly connected to the lower end of the guide rod 5121. As the guide rod 5121 moves downward, the pull wire is pulled out from the linear displacement sensor. The length of the pulled wire can be used to know the downward movement of the guide rod 5121, thereby knowing the downward movement distance of the water jacket 3.

[0074] During the film blowing process, under normal operating conditions, once bubble 1 has completed expansion, it enters a relatively stable molding phase, rather than undergoing a state of continuous, drastic change. Although bubble 1 may experience slight vibrations during cooling due to external airflow disturbances, its overall expanded size is stable and does not fluctuate frequently or significantly. Therefore, high-frequency, real-time dynamic adjustment of the tension of water jacket 3 is unnecessary.

[0075] During the initial molding phase of the bubble 1 or when the size is changed, the water jacket 3 undergoes a one-time tension adjustment and maintains its stable fit during the cooling process, rather than responding to each transient random change. Once the bubble 1 enters the stable cooling phase, the water jacket 3 is already in a properly tensioned state. Even if the bubble 1 vibrates slightly, the water jacket 3 maintains its stability through its stable tension adjustment. Furthermore, after cooling, the water jacket 3 returns to its original state, preventing long-term stress from affecting its service life and providing a foundation for subsequent adjustments to the new bubble 1.

[0076] The specific adjustment process is: first start the compressed gas supply and gradually increase the gas pressure toward the guide sleeve 5122. For example, the cylinder drive method drives the guide rod 5121 to move in the guide sleeve 5122. At the same time, the pressure sensor monitors the input gas pressure value in real time to ensure that it is within the set range.

[0077] At the same time, a linear displacement sensor mounted on guide rod 5121 simultaneously monitors the downward travel of water jacket 3. When the displacement reaches the set target value, it indicates that water jacket 3 is in a stable tensioned state. At this point, the air pressure within guide sleeve 5122 automatically stabilizes to maintain the tension of water jacket 3. This dual feedback mechanism of pressure and displacement enables dynamic regulation of air pressure, improving the accuracy of determining the tension of water jacket 3 and ensuring its stability throughout the cooling process.

[0078] After the membrane bubble 1 expands and drives the water jacket 3 to deform freely, the membrane bubble 1 is now fitted in the water jacket 3. By stably controlling the tension state of the water jacket 3, the membrane bubble 1 therein remains stable, thereby improving the stable fitting state between the water jacket 3 and the membrane bubble 1, ensuring that a stable water flow path is formed between the two, and ensuring the cooling effect.

[0079] A method for blowing a plastic film to prevent uneven bubble wrinkles is applied to the above-mentioned device for blowing a plastic film to prevent uneven bubble wrinkles, comprising the following steps: S1, the plastic melt is extruded and inflated by the film blowing mechanism to form a film bubble 1, so that the film bubble 1 is continuously pulled downward and is in a stable expansion state; S2, cooling water enters from the water inlet 21 on the upper part of the water-cooling shell 2, flows along the spiral pattern 32 in the annular water-cooling gap 31 formed between the water jacket 3 and the membrane bubble 1, and performs circumferential uniform cooling; S3, through the coordinated work of the pull-down structure 51 and the pressure stabilizing structure 52, the water jacket 3 is kept in a tensioned state as a whole, the consistency of the water-cooling gap 31 is maintained, and the pressure-maintaining airbag 33 provides elastic support to the water jacket 3, further stabilizing the water jacket 3; S4. The film bubble 1 in the cooling process is continuously pulled downward, and the film is evenly rolled into a finished product, completing the entire film blowing process.

[0080] The present invention utilizes the synergistic effect of the pull-down structure 51 and the pressure-stabilizing structure 52 to simultaneously apply opposite forces to the upper and lower ends of the water jacket 3, maintaining uniform tension throughout the jacket and a consistent water-cooling gap 31. This effectively prevents uneven cooling caused by displacement, loosening, or deformation of the water jacket 3. This ensures that the spiral pattern 32 consistently adheres to the surface of the film bubble 1, preventing wrinkles and improving film forming quality.

[0081] At the same time, the spiral patterns 32 on the inner wall of the water jacket 3 can expand and contract synchronously with the deformation of the water jacket 3 to form a continuous and stable cooling water channel. The spiral water flow path prolongs the contact time between the cooling water and the membrane bubble 1, improves the heat exchange efficiency, prevents water flow short-circuiting or stagnation, and further enhances the cooling uniformity.

[0082] In addition, the pressure-maintaining airbag 33 provides elastic support to the water jacket 3 through gas expansion, absorbs external vibrations and dynamic stresses, and enhances its operational stability while preventing the water jacket 3 from shaking and deflecting, so that the cooling process can be carried out continuously, stably and efficiently, thereby comprehensively ensuring the consistency of film product quality and the reliability of the production process.

[0083] The above embodiments merely represent one or more embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of protection of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, and such modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the appended claims.

Claims

1. A plastic film blowing device for preventing uneven bubble wrinkles, comprising a film blowing mechanism and a water cooling mechanism disposed thereunder; characterized in that: The water cooling mechanism includes a water-cooling shell and a water jacket arranged on the shell for the film bubble to pass through. In the film blowing state, a water-cooling gap is formed between the film bubble and the water jacket for cooling water to flow from top to bottom. The inner wall of the water jacket has a drainage portion that fits with the outer surface of the film bubble to maintain uniform flow of cooling water; the upper end of the water jacket is fixedly connected to the water-cooling shell, and the lower end of the water jacket extends vertically downward. The water-cooling shell is respectively provided with a water inlet and a water outlet at positions corresponding to the upper and lower ends of the water jacket. The bottom of the water-cooling shell is provided with a rubber bottom that can fit tightly with the outer surface of the film bubble to prevent cooling water leakage. The rubber bottom support has a drainage channel connecting the water-cooling gap and the water outlet; the water-cooling shell is also provided with a stabilizing component for maintaining stable operation of the water jacket, and the stabilizing component includes a pull-down structure connected to the lower end of the water jacket and a pressure-stabilizing structure that acts synchronously on the upper half of the water jacket in cooperation with the pull-down structure, and a linkage structure is provided between the pull-down structure and the pressure-stabilizing structure; when the water jacket is tightened downward by the pull-down structure, the pressure-stabilizing structure is in a synchronous upward state under the action of the linkage structure, so that the water jacket forms an annular cooling area around the membrane bubble for uniform and stable flow of cooling water.

2. A plastic film blowing molding device for preventing uneven bubble wrinkles according to claim 1, characterized in that: The linkage structure has an active part arranged on the pull-down structure and a driven part cooperating with the pressure-stabilizing structure. The active part and the driven part respectively have a force-applying point and a force-receiving point that contact each other. When the pull-down structure moves downward, the driven part gradually applies an upward force to the pressure-stabilizing structure under the action of the active part, so that the upper and lower parts of the water jacket remain coordinated and tensioned.

3. A plastic film blowing molding device for preventing uneven bubble wrinkles according to claim 2, characterized in that: The pressure stabilizing structure has an upper ring sleeve coaxial with the water jacket. The inner side of the upper ring sleeve is provided with multiple pressure stabilizing rings along its axial direction that are tightly fitted with the outer surface of the water jacket. The outer side of the upper ring sleeve is provided with multiple balls, and the water-cooled shell is provided with vertical slide rails that cooperate with the corresponding balls.

4. A plastic film blowing device for preventing uneven bubble wrinkles according to claim 3, characterized in that: The pull-down structure has a lower ring sleeve that is coaxial with the water jacket. The lower end of the water jacket is fixedly connected to the lower ring sleeve. The lower ring sleeve is slidingly sleeved on the rubber base. The water jacket, the lower ring sleeve, the rubber base and the membrane bubble together form the water-cooling gap. The water-cooling shell is provided with a pull-down driver for driving the lower ring sleeve to move downward.

5. A plastic film blowing molding device for preventing uneven bubble wrinkles according to claim 4, characterized in that: An upper compression spring is provided between the upper ring sleeve and the water-cooled shell, and a lower compression spring is provided between the lower ring sleeve and the rubber base. When the upper ring sleeve and the lower ring sleeve move away from each other, the upper compression spring and the lower compression spring are in a synchronous compression state. At this time, the water body is in a deformed and stretched state. Conversely, the water jacket gradually returns to its initial state.

6. A plastic film blowing device for preventing uneven bubble wrinkles according to claim 1, characterized in that: The drainage part of the inner wall of the water jacket is specifically a spiral pattern that can expand and contract synchronously with the deformation of the water jacket. When the membrane bubble passes through the water jacket, the spiral pattern is in a tight fit with the outer surface of the membrane bubble, allowing the cooling water to flow from top to bottom along the spiral path.

7. A plastic film blowing device for preventing uneven bubble wrinkles according to claim 6, characterized in that: The water jacket is provided with a pressure-maintaining airbag to further maintain the stability of the water jacket. The water-cooling shell is provided with an air pipe connected to the pressure-maintaining airbag. When the pressure-maintaining airbag expands to contact the water jacket, the water jacket is in an elastically supported state, making the water jacket more stable.

8. A plastic film blowing device for preventing uneven bubble wrinkles according to claim 4, characterized in that: The driven member has a first extension portion in contact with the active member and a second extension portion in contact with the lower end of the upper ring sleeve. The driven member is rotatably arranged on the water-cooled shell. When the active member moves downward with the lower ring sleeve, the first extension portion is in a downward swing state under the pressure of the active member, and the second extension portion is in an upward swing state.

9. A plastic film blowing device for preventing uneven bubble wrinkles according to claim 8, characterized in that: The pull-down drive has a guide rod and a guide sleeve. A guide rod is vertically provided around the lower ring sleeve. Each guide rod is sleeved with a guide sleeve provided on the water-cooled shell. When compressed gas enters the guide sleeve from top to bottom, the guide rod is in a compressed downward state inside the guide sleeve.

10. A method for blowing a plastic film to prevent uneven bubble wrinkles, applied to a device for blowing a plastic film to prevent uneven bubble wrinkles according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. The plastic melt is extruded and inflated to form a film bubble through the film blowing mechanism, so that the film bubble is continuously pulled downward and is in a stable expansion state; S2, cooling water enters from the water inlet on the upper part of the water-cooling shell, flows along the spiral pattern in the annular water-cooling gap formed between the water jacket and the membrane bubble, and performs circumferential uniform cooling; S3. The pull-down structure and the pressure-stabilizing structure work together to keep the water jacket in a tensioned state, maintain the consistency of the water-cooling gap, and provide elastic support to the water jacket through the pressure-maintaining airbag, further stabilizing the water jacket. S4: The film bubble in the cooling process is continuously pulled downward, and the film is evenly rolled into a finished product, completing the entire film blowing process.

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