Plastic film cooling forming device

Abstract

The invention discloses a plastic film cooling forming device, and belongs to the field of plastic film production. The plastic film cooling forming device comprises an extrusion die head; the plastic film forms film bubbles between the extrusion die head and the propeller strut; the air injection part is used for injecting air into the film bubbles from the bottom; the exhaust part is used for exhausting air out of the film bubbles from the upper part; the exhaust part comprises an exhaust pipe which is located in the film bubble. An exhaust cavity channel and a cold water circulation cavity channel are formed in the exhaust pipe; the exhaust pipe is externally connected with cold water injection equipment, and the cold water injection equipment enables cold water to flow in the cold water circulation cavity from top to bottom. The exhaust pipe has the beneficial effects that cold water flows from top to bottom, the gradient with the temperature gradually increasing from top to bottom is formed on the outer wall of the exhaust pipe, and a better matched heat exchange relation is formed with air with the temperature gradually increasing from bottom to top in the film bubbles. Therefore, the temperature difference between different height positions of the film bubbles and the internal air is reduced, the cooling is more uniform, and the problems of film bubble instability or film quality caused by non-uniform cooling are reduced.

Description

Technical Field

[0001] This application relates to the field of plastic film production, and in particular to a plastic film cooling and forming apparatus. Background Technology

[0002] In the plastic blown film forming process, molten plastic is extruded through a ring die to form a tubular film bubble, which is then inflated by compressed air and solidified under cooling. Finally, it is flattened by a herringbone frame and wound up to form a plastic film. The cooling effect of the film bubble directly determines the film's production efficiency, thickness uniformity, transparency, and mechanical properties.

[0003] Traditional cooling systems primarily rely on an external air ring and internal air circulation. The external air ring blows cooling air onto the outer surface of the membrane bubble for heat exchange, while the internal system injects room temperature air into the bottom of the bubble. As the air rises, it carries away heat from the inner wall of the bubble and is exhausted from the top. However, this conventional internal cooling method has significant technical limitations: the initial temperature of the injected air is close to the ambient temperature, resulting in limited cooling capacity and making it difficult to meet the demands of high-speed, high-volume production or the production of thick films; more importantly, the temperature field distribution inside the bubble does not match the temperature change of the bubble wall, creating a "reverse gradient" that is detrimental to uniform cooling. Specifically, as the air flows from bottom to top, its temperature gradually increases after absorbing heat, resulting in a temperature distribution inside the bubble that is lower at the bottom and higher at the top. Simultaneously, the temperature of the bubble wall is highest immediately after extrusion from the die, and gradually decreases as it moves upward and exchanges heat with both external and internal air, resulting in a temperature distribution that is higher at the bottom and lower at the top. This inverted phenomenon, where the temperature difference between the internal air and the membrane bubble wall varies with height, results in significant differences in cooling intensity and rate at different heights of the membrane bubble: the lower part has a large temperature difference but the initial temperature of the cooling medium (air) is high, while the upper part has a small temperature difference but the air temperature is also high. This leads to an uneven overall cooling efficiency, which can easily cause problems such as film thickness fluctuations, uneven crystallinity, and decreased optical performance, thus limiting further improvements in production speed and product quality. Summary of the Invention

[0004] To address the issue of uneven overall cooling efficiency, which easily leads to problems such as film thickness fluctuations, uneven crystallinity, and decreased optical performance, thus limiting further improvements in production speed and product quality, this application provides a plastic film cooling and forming apparatus.

[0005] The plastic film cooling and forming apparatus provided in this application adopts the following technical solution:

[0006] A plastic film cooling and forming apparatus includes: an extrusion die for extruding molten plastic film from an extruder; the plastic film forming a bubble between the extrusion die and a herringbone frame; an air injection unit for injecting air into the bubble from below; and an air venting unit for discharging air from the bubble from above; the air venting unit includes an air vent pipe located in the middle of the bubble, with an air outlet at the top; the air vent pipe has an air venting chamber and a cold water circulation chamber inside, the cold water circulation chamber being located between the air venting chamber and the inner wall of the air vent pipe; and a cold water injection device connected to the outside of the air vent pipe, the cold water injection device communicating with the cold water circulation chamber, the cold water injection device causing cold water to flow from top to bottom in the cold water circulation chamber.

[0007] By adopting the above technical solution, cold water is used to cool the exhaust pipe through its internal structure, maintaining a low temperature on the outer wall of the exhaust pipe, which is lower than the temperature of the air inside the membrane bubble. This cooling of the air inside the membrane bubble further ensures that the air is kept at a lower temperature, improving the cooling efficiency and allowing the membrane bubble to be appropriately cooled even at relatively high conveying and production speeds, thereby further improving membrane bubble production efficiency and quality.

[0008] Because the air temperature inside the membrane bubble increases with height, and decreases with height, this leads to varying temperature differences between the membrane bubble and the air at different heights. This is detrimental to perfect cooling of the membrane bubble. However, the outer wall of the exhaust pipe is cold, and since the cold water flows from top to bottom, its temperature gradually increases from top to bottom. This allows for heat exchange between the warmer air at higher positions and the cooler outer wall of the exhaust pipe, providing more heat dissipation and lowering the temperature of the air at higher positions. Therefore, the cooling effect of the exhaust pipe's outer wall gradually increases from bottom to top, resulting in a greater reduction in the temperature of the warmer air at higher positions. This maintains the temperature difference variation between the membrane bubble and the gaps, reducing the degree of temperature difference variation and improving the cooling effect of the membrane bubble to some extent, thus improving the production quality of the membrane bubble.

[0009] Furthermore, a flow guiding structure is provided in the cold water circulation cavity; the flow guiding structure forms a spiral cavity in the cold water circulation cavity, and the flow guiding structure forms a water injection cavity in the exhaust cavity; the water injection cavity is connected to the spiral cavity; the spiral cavity is in direct or indirect contact with the inner wall of the exhaust pipe.

[0010] By adopting the above technical solution, water flows in the spiral cavity, which increases the flow distance of the water. This slows down the change in the water's position in terms of height, allowing the water to contact the exhaust pipe more and more evenly in the spiral cavity, thus avoiding the situation where excessively fast water circulation leads to a sharp increase in costs.

[0011] Furthermore, the top of the water injection chamber is connected to the top of the spiral channel, so that a water flow from top to bottom is formed in the spiral channel.

[0012] By adopting the above technical solution, the water in the water injection chamber enters the spiral channel at the top of the spiral channel, and the water flows from top to bottom, which helps to ensure that the temperature of the outer wall of the exhaust pipe gradually increases from top to bottom.

[0013] Furthermore, multiple heat sinks are provided on the inner wall of the exhaust pipe, and the heat sinks form multiple drainage chambers with multiple bends on the inner wall of the exhaust pipe.

[0014] By adopting the above technical solution, the arrangement of multiple heat sinks is used to increase the contact area between the inner wall of the exhaust pipe and the water, which is beneficial to improving the heat exchange efficiency between the exhaust pipe and the water.

[0015] Furthermore, an air injection structure is provided inside the exhaust pipe, the air injection structure having multiple air injection channels distributed along the height direction and an air storage chamber; the air injection channels and the air storage chamber are directly or indirectly connected to the heat exchange fins for heat exchange; multiple upward-sloping holes are opened on the wall of the exhaust pipe, the inclined holes communicating with the air storage chambers.

[0016] By adopting the above technical solution, the air injection structure allows air to enter the air storage chamber through the air injection channel. Both the air injection channel and the air storage chamber are in conjunction with heat exchange fins. Water in the spiral channel exchanges heat with the heat exchange fins, resulting in a low-temperature heat exchange. Simultaneously, the water also exchanges heat with the inner wall of the exhaust pipe, which is also at a low temperature. The air in the air injection channel is cooled by the action of the heat exchange fins and the inner wall of the exhaust pipe, and the air in the air storage chamber also cools down. Therefore, the cooler air is discharged outwards into the membrane bubble through the oblique holes. As the height inside the membrane bubble changes, the air temperature gradually increases. However, the cold air injected through the oblique holes mixes with the gradually warming air, causing the air to cool down. To a certain extent, this avoids the phenomenon of the air temperature inside the membrane bubble rising with increasing height. This allows the air temperature inside the membrane bubble to decrease with increasing height, thereby better reducing the degree of temperature difference variation at different locations within the membrane bubble and better ensuring the quality of the membrane bubble and the final production quality of the membrane.

[0017] Furthermore, a hydrophilic medium layer is provided on the inner wall of the inclined hole; the hydrophilic medium layer is attached to the inner wall of the inclined hole.

[0018] Furthermore, an enlarged hole is formed on the outer wall of the exhaust pipe, and the enlarged hole is connected to the oblique hole; the hydrophilic medium layer has a first bonding portion and a second bonding portion connected to the first bonding portion, the first bonding portion is bonded to the oblique hole, and the second bonding portion is bonded to a portion of the enlarged hole.

[0019] Furthermore, the gas injection structure includes an annular shell that forms the gas storage chamber; a gap exists between the annular shell and the outer side of the spiral plate.

[0020] Furthermore, the flow guiding structure includes: a spiral plate and a water injection pipe; the water injection pipe is fixed to the spiral plate, and the spiral plate is located on the outer wall of the water injection pipe; an airflow duct is provided inside the water injection pipe, and the water injection chamber is formed between the airflow duct and the water injection pipe; the airflow duct forms the exhaust channel; a driving component is provided at the water injection pipe, and the driving component is used to drive the water injection pipe to rotate so that the spiral plate rotates synchronously.

[0021] Furthermore, the spiral cavity is externally connected to a water injection tank; the water injection pipe is connected to the water injection tank via the connecting structure; the connecting structure includes: a transfer shell, a rotary joint, a water injection pump body, and a connecting pipe; the transfer shell is connected to the water injection pipe via the rotary joint, and the transfer shell is connected to the water injection tank body via the water injection pump and the connecting pipe in sequence; the airflow duct is inserted into the transfer shell and extends outward from the transfer shell.

[0022] In summary, this application includes at least one of the following beneficial technical effects:

[0023] By incorporating a cold water circulation chamber within the exhaust pipe, the outer wall of the exhaust pipe is kept at a low temperature, effectively cooling the air inside the membrane bubble and thus improving the overall cooling efficiency of the membrane bubble. This allows the membrane bubble to be adequately cooled at faster traction and production speeds, thereby increasing production efficiency.

[0024] By utilizing the downward flow of cold water, a temperature gradient is created on the outer wall of the exhaust pipe, which gradually increases from top to bottom. This creates a more suitable heat exchange relationship with the air inside the membrane bubble, which gradually increases in temperature from bottom to top. This helps to reduce the temperature difference between different height positions of the membrane bubble and the internal air, resulting in more uniform cooling and reducing membrane bubble instability or membrane quality problems caused by uneven cooling.

[0025] By injecting pre-cooled low-temperature air into the membrane bubble at different heights through the air injection structure, the tendency of the air temperature inside the membrane bubble to rise with height can be further suppressed, making the temperature distribution more uniform and conducive to producing membranes with more stable quality.

[0026] The cold water circulation also cools the hot air in the exhaust duct, preventing high-temperature exhaust gas from being directly discharged into the workshop and improving the working environment.

[0027] The hydrophilic medium layer design can effectively absorb water mist that may condense on the outer wall of the exhaust pipe, prevent water droplets from falling onto the membrane bubble and causing defects, and ensure long-term continuous and stable operation of the equipment. Attached Figure Description

[0028] Figure 1This is a schematic diagram of the overall structure of an embodiment of this application;

[0029] Figure 2 This is a structural schematic diagram as part of an embodiment, mainly showing an observation from another perspective. Figure 1 The structure;

[0030] Figure 3 This is a structural schematic diagram of a part of the embodiment, mainly showing the structure of the bubble stabilizer and some surrounding parts;

[0031] Figure 4 This is a structural schematic diagram of a part of the embodiment, mainly showing... Figure 1 The frontal planar structure;

[0032] Figure 5 This is a structural schematic diagram of a part of the embodiment, mainly showing... Figure 4 The structure of the membrane vesicle after partial cross-section;

[0033] Figure 6 This is a structural schematic diagram of a part of the embodiment, mainly showing... Figure 1 Local structure;

[0034] Figure 7 This is a structural schematic diagram of a part of the embodiment, mainly showing the structure of the exhaust component and some surrounding parts;

[0035] Figure 8 This is a structural diagram of a part of the embodiment, mainly showing the structure of the connecting structure and some surrounding parts;

[0036] Figure 9 This is a structural schematic diagram of a part of the embodiment, mainly showing the structure of the flow guiding structure and some surrounding parts;

[0037] Figure 10 This is a structural schematic diagram of a part of an embodiment, mainly showing the structure of the exhaust pipe;

[0038] Figure 11 yes Figure 10 Enlarged view of A in the middle;

[0039] Figure 12 yes Figure 10 Enlarged view of B in the middle;

[0040] Figure 13 This is a structural schematic diagram of a part of the embodiment, mainly showing the structure of the arc plate and the heat sink;

[0041] Figure 14 This is a structural schematic diagram as part of an embodiment, mainly showing a flow trajectory in the drainage chamber.

[0042] Figure label:

[0043] 1. Extrusion die head; 11. Support platform; 111. Air inlet;

[0044] 2. Injection component; 21. Injection structure; 211. Injection pipeline; 212. Annular shell; 213. Connecting hole;

[0045] 3. Exhaust component; 31. Exhaust pipe; 311. Exhaust port; 312. Angled hole; 313. Expanded hole; 314. Ring cover; 32. Heat sink; 33. Arc plate; 34. Hydrophilic medium layer; 341. First bonding part; 342. Second bonding part;

[0046] 4. A-frame;

[0047] 5. Guide rollers;

[0048] 6. Bubble stabilizer;

[0049] 7. Vesicles;

[0050] 8. Flow guiding structure; 81. Spiral plate; 811. Spiral cavity; 82. Water injection pipe; 821. Water injection chamber; 822. Cold water circulation cavity; 823. Drainage chamber; 824. Notch; 83. Airflow duct; 831. Exhaust cavity; 832. Ring cover; 84. Driving component; 85. Water injection tank;

[0051] 9. Connecting structure; 91. Transfer housing; 92. Rotary joint; 93. Water pump body; 94. Connecting pipe. Detailed Implementation

[0052] The following is in conjunction with the appendix Figure 1-14 This application will be described in further detail.

[0053] This application discloses a plastic film cooling and forming apparatus.

[0054] A plastic film cooling and forming device includes: an extrusion die 1, an air injection component 2, and an air venting component 3. The plastic blown film machine includes the plastic film cooling and forming device, a herringbone frame 4, guide rollers 5, an extruder, and a bubble stabilizer 6. The extruder extrudes molten plastic through the extrusion die 1. After extrusion, the plastic solidifies in the air. The plastic is manually pulled out of the extrusion die 1 to form a plastic film, which is then fed upwards to the herringbone frame 4. After passing through the herringbone frame 4, the plastic film changes from a near-cylindrical shape to a sheet-like film, which is then guided outwards by the guide rollers 5 to obtain a qualified film. Air injection unit 2 injects external air into the cylindrical plastic film. The plastic film is cooled by the air injected by air injection unit 2 and forms a stable, crack-free bubble 7 between the extrusion die 1 and the herringbone frame 4. The bubble stabilizing frame 6 is located below the herringbone frame 4. Since air injection unit 2 injects air into the bubble 7, the bubble 7 will expand. The bubble stabilizing frame 6 prevents the bubble 7 from over-expanding and bursting, and also stably guides the bubble 7. The bubble 7 is a nearly cylindrical plastic film after expansion.

[0055] The air injection component 2 is used to inject smooth and nearly turbulent air into the membrane bubble 7 from below. The air venting component 3 is used to discharge air from the top of the membrane bubble 7. Both the air injection component 2 and the air venting component 3 are conventional technologies and will not be described in detail. The air venting component 3 includes an air vent pipe 31. The air vent pipe 31 is located in the middle of the membrane bubble 7, and an air vent 311 is provided at the top of the air vent pipe 31. The extrusion die 1 has a support platform 11 in the middle, and the air vent pipe 31 is set on the support platform 11. The air injection component 2 forms an air inlet 111 on the support platform 11, and the air injection component 2 allows air to enter the membrane bubble 7 from the air inlet 111. The air inlets 111 are distributed around the periphery of the air vent pipe 31. The top of the air vent pipe 31 is the outlet, so external air enters the membrane bubble 7 from the air inlet 111, then flows upward and is discharged outward along the air vent pipe 31.

[0056] The exhaust pipe 31 is internally equipped with an exhaust chamber 831 and a cold water circulation chamber 822, located between the exhaust chamber 831 and the inner wall of the exhaust pipe 31. A cold water injection device is connected to the outside of the exhaust pipe 31, and this device communicates with the cold water circulation chamber 822, allowing cold water to flow downwards within the chamber. The cold water circulation chamber 822 is an annular chamber, and both the exhaust chamber 831 and the inner wall of the exhaust pipe 31 are in contact with it. The cold water flowing in the circulation chamber 822 cools the exhaust pipe 31, resulting in a lower temperature. The cold water flowing in the circulation chamber 822 also cools the air discharged from the exhaust chamber 831, preventing excessively hot air from being discharged directly and affecting the workshop environment.

[0057] By adopting the above technical solution, and utilizing the internal design of the exhaust pipe 31, cold water cools the exhaust pipe 31, maintaining a low temperature on the outer wall of the exhaust pipe 31, which is lower than the temperature of the air inside the membrane bubble 7. Thus, the exhaust pipe 31 cools the air inside the membrane bubble 7, further ensuring that the air inside the membrane bubble 7 is at a lower temperature, improving the cooling efficiency of the membrane bubble 7. This allows the membrane bubble 7 to be appropriately cooled even at relatively fast conveying and production speeds, further improving the production efficiency and quality of the membrane bubble 7.

[0058] Because the air temperature inside the bubble 7 increases with height, and decreases with height, this leads to varying temperature differences between the bubble 7 and the air at different heights. This is detrimental to the perfect cooling of the bubble 7. Therefore, the outer wall temperature of the exhaust pipe 31 is low, and since the cold water flows from top to bottom, the temperature of the outer wall of the exhaust pipe 31 gradually increases from top to bottom. This allows for heat exchange between the warmer air at higher positions and the cooler outer wall of the exhaust pipe, providing more heat dissipation to lower the temperature of the air at higher positions. Thus, the cooling effect of the outer wall of the exhaust pipe 31 gradually increases from bottom to top, resulting in a greater reduction in the temperature of the warmer air at higher positions. This maintains the temperature difference variation between the bubble 7 at different heights and the gaps, reducing the degree of temperature difference variation and improving the cooling effect of the bubble 7 to a certain extent, thereby improving the production quality of the bubble 7.

[0059] In a specific embodiment, a flow guiding structure 8 is provided in the cold water circulation cavity 822. The flow guiding structure 8 forms a spiral cavity 811 in the cold water circulation cavity 822 and a water injection cavity in the exhaust cavity 831, the water injection cavity communicating with the spiral cavity 811. The spiral cavity 811 is in direct or indirect contact with the inner wall of the exhaust pipe 31. More specifically, the flow guiding structure 8 includes a spiral plate 81 and a water injection pipe 82. The water injection pipe 82 is fixed to the spiral plate 81, the spiral plate 81 is located on the outer wall of the water injection pipe 82, and an airflow duct 83 is provided inside the water injection pipe 82, forming the water injection chamber 821 between the airflow duct 83 and the water injection pipe 82. The exhaust cavity 831 is located inside the airflow duct 83. The space formed by the spiral plate 81 and the water injection pipe 82 is the spiral cavity 811. In one embodiment, the spiral plate 81 is in direct contact with the inner wall of the exhaust pipe 31. In this case, the spiral cavity 811 is formed by the water injection pipe 82, the spiral plate 81, and the inner wall of the exhaust pipe 31. A cold water injection device injects cold water into the water injection cavity between the water injection pipe 82 and the airflow duct 83. The cold water then enters the spiral cavity 811 from the water injection cavity and gradually flows under the guidance of the spiral plate 81. The cold water contacts the inner wall of the exhaust pipe 31, keeping the exhaust pipe 31 at a relatively low temperature. Additionally, the cold water injected from the water injection chamber 821 also contacts the airflow duct 83, cooling the exhaust air.

[0060] Cold water cools the airflow duct 83 to prevent the exhaust air from becoming too hot and affecting the workshop environment. The cold water flows through the spiral cavity 811, which, while maintaining cooling of the exhaust pipe 31, slows down the flow rate of the cold water, reduces the amount of cold water used, and lowers production costs.

[0061] Specifically, the top of the water injection chamber 821 is connected to the top of the spiral channel 811, so that a water flow from top to bottom is formed in the spiral channel 811. Water in the water injection chamber 821 enters the spiral channel 811 from the top, and the downward flow of water helps to ensure that the temperature of the outer wall of the exhaust pipe 31 gradually increases from top to bottom. More specifically, multiple notches 824 are opened at the top of the water injection pipe 82, and a ring cap 832314 is provided at the top of the airflow duct 83, which is fastened to the top of the exhaust pipe 31.

[0062] In other embodiments, the spiral plate 81 is in indirect contact with the inner wall of the exhaust pipe 31. In this case, multiple heat sinks 32 are provided on the inner wall of the exhaust pipe 31, meaning that the spiral plate 81 and the heat sinks 32 are in close contact to achieve indirect contact between the spiral plate 81 and the inner wall of the exhaust pipe 31. The heat sinks 32 form multiple, repeatedly curved drainage chambers 823 on the inner wall of the exhaust pipe 31. The multiple heat sinks 32 consist of vertical heat sinks 32 and horizontal heat sinks 32. The horizontal heat sinks 32 are located between any two adjacent vertical heat sinks 32. Thus, when cold water flows between any two vertical heat sinks 32, encountering the horizontal heat sinks 32 causes the cold water to change its flow direction, thus slowing the flow. Simultaneously, the arrangement of the heat sinks 32 increases the contact area between the cold water and the inner wall of the exhaust pipe 31, improving the cooling efficiency of the outer wall of the exhaust pipe 31. The repeatedly curved drainage chambers 823 ensure that the flow speed of cold water in the area where the heat sinks 32 are located is the same as the flow speed of cold water in the spiral plate 81.

[0063] Specifically, an air injection structure 21 is provided inside the exhaust pipe 31. The air injection structure 21 has multiple air injection channels distributed along the height direction and an air storage chamber. The air injection channels and the air storage chamber are directly or indirectly connected to the heat sink 32 for heat exchange. Multiple upward-sloping holes 312 are formed on the wall of the exhaust pipe 31, and the holes 312 communicate with the air storage chamber, which is an annular chamber. The multiple holes 312 are circumferentially distributed on the exhaust pipe 31. More specifically, the air injection structure 21 includes an annular shell 212, which forms the air storage chamber. The air injection structure 21 also includes an air injection pipe 211, which sequentially passes through multiple annular shells 212, forming an air injection channel. A connecting hole 213 is formed on the air injection pipe 211, located inside the annular shell 212, and the air injection pipe 211 communicates with the multiple annular shells 212. A gap exists between the annular shell 212 and the outer side of the spiral plate 81, preventing direct contact between the spiral plate 81 and the annular shell 212 during rotation. The air injection structure 21 allows air to enter the air storage chamber through the air injection channel. Both the air injection channel and the air storage chamber are in heat exchange cooperation with the heat sink 32. The water in the spiral channel 811 exchanges heat with the heat sink 32, resulting in a low temperature. Simultaneously, the water exchanges heat with the inner wall of the exhaust pipe 31, which is also at a low temperature. The air in the air injection channel is cooled by the heat sink 32 and the inner wall of the exhaust pipe 31, and the air in the air storage chamber also cools down. This causes the cooler air to be discharged outwards into the membrane bubble 7 through the oblique hole 312. As the internal height of the membrane bubble 7 changes, the air temperature gradually increases. However, the cold air injected through the oblique hole 312 mixes with the gradually warming air, cooling the air and, to a certain extent, preventing the air temperature inside the membrane bubble 7 from rising with increasing height. This allows the air temperature inside the membrane bubble 7 to decrease as the height increases, thereby better reducing the degree of temperature difference variation at different locations inside the membrane bubble 7 and better ensuring the quality of the membrane bubble 7 and the final production quality of the membrane.

[0064] In a more specific embodiment, multiple arc-shaped plates 33 are also provided on the inner wall of the exhaust pipe 31, and multiple heat sinks 32 are divided into multiple groups of heat sinks 32. Each group of heat sinks 32 is set on an arc-shaped plate 33, and the arc-shaped plate 33 is detachably connected to the inner wall of the exhaust pipe 31, thereby facilitating the placement of the heat sinks 32 on the inner wall of the exhaust pipe 31. The air injection pipe 211 is fixed to the heat sinks 32, and at least one air injection pipe 211 is provided. When only one air injection pipe 211 is provided, it is fixed to one group of heat sinks 32. When multiple air injection pipes 211 are provided, each air injection pipe 211 is fixed to a separate group of heat sinks 32. The annular shell 212 is fixed to the multiple groups of arc-shaped plates 33. After welding the annular shell 212 to the arc-shaped plates 33, the overall structure of the multiple arc-shaped plates 33, multiple heat sinks 32, multiple air injection pipes 211, and multiple annular shells 212 is then placed into the exhaust pipe 31.

[0065] A hydrophilic medium layer 34 is disposed on the inner wall of the inclined hole 312; the hydrophilic medium layer 34 is attached to the inner wall of the inclined hole 312. The hydrophilic medium layer 34 can be a sponge pad, and the hydrophilic medium layer 34 is annular. Because the outer wall temperature of the exhaust pipe 31 is relatively low, under certain special production conditions, the outer wall of the exhaust pipe 31 will be at an even lower temperature to cool the air in the membrane bubble 7. At this time, the air in the membrane bubble 7 comes into contact with the outer wall of the exhaust pipe 31. Since the air entering the membrane bubble 7 is difficult to be absolutely dry, the outer wall of the exhaust pipe 31 will be damp during actual use. After long-term operation, water mist will condense on the outer wall of the exhaust pipe 31. The water mist flows into the inclined hole 312 on the outer wall of the exhaust pipe 31 and comes into contact with the hydrophilic medium layer 34 in the inclined hole 312. It is absorbed by the hydrophilic medium layer 34, which avoids the situation where water mist condenses on the outer wall of the exhaust pipe 31 and drips onto the membrane bubble 7 after long-term use. This is beneficial to ensure the long-term operation of the equipment and the long-term stable production of membranes and the long-term stable preparation of membranes.

[0066] More specifically, an enlarged hole 313 is formed on the outer wall of the exhaust pipe 31, and the enlarged hole 313 is connected to the oblique hole 312; the hydrophilic medium layer 34 has a first bonding portion 341 and a second bonding portion 342 connected to the first bonding portion 341. The first bonding portion 341 is bonded to the oblique hole 312, and the second bonding portion 342 is bonded to a portion of the enlarged hole 313. The enlarged hole 313 makes it easier for the condensed water mist to be absorbed by the hydrophilic medium layer 34. Both the first bonding portion 341 and the second bonding portion 342 can be a sponge pad or other absorbent material.

[0067] In some embodiments, the water injection pipe 82 is directly connected to a cold water injection device, which can be a pump body and a cold water storage structure. The water injection pipe 82 is connected to the pump body via a pipeline. The air injection device 2 also injects air into the air injection pipeline 211. The air injection pipeline 211 is directly connected to the air injection device 2. The airflow duct 83 discharges the air outward. The airflow duct 83 crosses the water injection pipe 82 so that the airflow duct 83 is disconnected from the water injection pipe 82 and connected to the external environment.

[0068] In other embodiments, a driving member 84 is provided at the water injection pipe 82. The driving member 84 is used to drive the water injection pipe 82 to rotate, so that the spiral plate 81 rotates synchronously. The rotation of the spiral plate 81 can further control the flow speed of cold water in the spiral cavity 811, and better increase or decrease the flow of cold water according to the actual cooling situation.

[0069] Specifically, the spiral cavity 811 is externally connected to a water tank 85. The water injection pipe 82 is connected to the water tank 85 via the connecting structure 9. The connecting structure 9 includes: a transfer housing 91, a rotary joint 92, a water injection pump body 93, and a connecting pipe 94. The transfer housing 91 is connected to the water injection pipe 82 via the rotary joint 92. The transfer housing 91 is connected to the water tank 85 via the water injection pump and the connecting pipe 94. The water injection pump draws water out of the transfer housing 91 through the connecting pipe 94 and sends it into the transfer housing 91 via the rotary joint 92, then from the transfer housing 91 through the rotary joint 92 into the water injection pipe 82. The airflow duct 83 is inserted into the transfer housing 91 and extends outward from the transfer housing 91. The driving component 84 uses a motor and a transmission structure, which is either gear transmission or belt transmission. The motor drives the water injection pipe 82 to rotate through the transmission structure.

[0070] In other embodiments, the drainage cavity and spiral cavity 811 can directly discharge water to the external ground, or a liquid receiving device can be installed on the ground to achieve water recycling. The area where the drainage cavity and spiral cavity 811 are located refers to the space between the water injection pipe 82 and the exhaust pipe 31. Alternatively, a sealing plug can be installed in the space between the water injection pipe 82 and the exhaust pipe 31, or the special shape of the water injection pipe 82 and the exhaust pipe 31 can be used to seal the lower part of the space between the water injection pipe 82 and the exhaust pipe 31, and then a pipe can be installed on the side of the exhaust pipe 31 to communicate with the space between the water injection pipe 82 and the exhaust pipe 31. This pipe is connected to an external pump body to achieve water discharge.

[0071] The workflow for this application is as follows:

[0072] After being heated, plasticized, and melted in the extruder, the plastic raw material is continuously and stably conveyed to the extrusion die 1. The molten plastic is extruded outward through the annular slit of the extrusion die 1, forming a tubular molten prototype.

[0073] The operator pulls the initially extruded tubular melt upwards from the die outlet. The melt initially solidifies in the air, forming the initial tubular plastic film (i.e., the initial segment of film bubble 7). The traction force causes film bubble 7 to continue moving upwards.

[0074] The air injection unit 2 injects treated, stable, and nearly turbulent-free cooling air into the interior of the bubble 7 from the bottom (specifically through the air inlet 111 on the support platform 11 in the middle of the extrusion die 1). The injected air serves two purposes: firstly, it supports and inflates the bubble 7 to achieve the predetermined diameter; secondly, as a cooling medium, it exchanges heat with the inner wall of the bubble 7, carrying away heat and providing internal cooling. The injection pressure must be kept stable to ensure the stability of the shape and size of the bubble 7.

[0075] The injected air causes the membrane bubble 7 to expand. To prevent the membrane bubble 7 from over-expanding or swaying, a bubble stabilizing frame 6 is installed on the outside of the membrane bubble 7 and below the A-frame 4. The bubble stabilizing frame 6 constrains and stabilizes the expanding membrane bubble 7, ensuring that the membrane bubble 7 moves upward in a stable cylindrical shape.

[0076] The continuously rising cylindrical film bubble 7 reaches the position of the A-frame 4. The A-frame 4 gradually folds and flattens the cylindrical film bubble 7, transforming it into a sheet film body with two layers stacked together. Subsequently, the sheet film body is further flattened and guided by the guide roller 5 and conveyed to the subsequent winding or processing station, finally obtaining a qualified plastic film product.

[0077] Internal air circulation and enhanced cooling:

[0078] After heat exchange is completed inside the membrane bubble 7, the air that has increased in temperature is drawn in through the exhaust port 311 at the top of the exhaust pipe 31 located on the central axis of the membrane bubble 7. The exhaust pipe 31 is fixed on the support platform 11 in the middle of the extrusion die 1.

[0079] The cold water injection device pumps cold water into the cold water circulation chamber 822 inside the exhaust pipe 31. The cold water flows from top to bottom within this chamber (specifically through a spiral chamber 811 or a flow channel equipped with heat sinks 32). The flowing cold water undergoes efficient heat exchange with the wall of the exhaust pipe 31, thereby reducing the temperature of the entire exhaust pipe 31 wall.

[0080] The cooler outer wall of the exhaust pipe 31 is directly exposed to the rising air inside the membrane bubble 7, becoming a powerful "cold source" that provides additional, active cooling to the air inside the membrane bubble 7. This significantly enhances the overall cooling capacity of the internal cooling system.

[0081] Because the cold water flows from top to bottom, the temperature of the outer wall of the exhaust pipe 31 exhibits a gradient distribution that gradually increases from top to bottom. This is a better match with the complex temperature field inside the membrane bubble 7, where the air temperature gradually decreases from top to bottom, while the membrane bubble 7 wall temperature gradually increases from top to bottom. The low-temperature zone at the top of the exhaust pipe 31 can more effectively cool the warmer internal air at the top of the membrane bubble 7, while the relatively higher pipe wall temperature at the bottom avoids over-cooling of the lower region of the membrane bubble 7. This helps to balance the temperature difference between different height positions of the membrane bubble 7 and the internal air, achieving more uniform cooling.

[0082] In a further embodiment, the air supplied by the air injection component 2 can be pre-cooled through the air injection structure 21 integrated in the exhaust pipe 31 (such as an air injection channel or an air storage chamber that exchanges heat with the heat sink 32). The pre-cooled low-temperature air is injected obliquely upwards into the membrane bubble 7 through the inclined holes 312 on the wall of the exhaust pipe 31, which further optimizes the cooling effect inside the membrane bubble 7, especially in the middle and lower regions, and can actively regulate the internal temperature distribution.

[0083] When the hot air discharged from the membrane bubble 7 flows through the exhaust chamber 831 in the center of the exhaust pipe 31, it will be indirectly cooled by the cold water in the surrounding cold water circulation chamber 822, thereby reducing the temperature of the discharged air and improving the working environment of the workshop.

[0084] The outer wall of the exhaust pipe 31 may condense water mist due to cooling, which may cause it to fall below the air dew point. The hydrophilic medium layer 34 set in the intake oblique hole 312 can effectively absorb this moisture, prevent water droplets from forming and dripping onto the membrane bubble 7, thus preventing defects and ensuring the stability of long-term operation.

[0085] By driving the internal spiral plate 81 to rotate through the drive component 84, the flow state of cold water in the spiral cavity 811 can be adjusted, thereby flexibly controlling the cooling intensity and adapting to different production process requirements.

[0086] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A plastic film cooling and forming apparatus, comprising: An extrusion die is used to extrude molten plastic film from an extruder. The plastic film forms a bubble between the extrusion die and the herringbone frame; An air injection device is used to inject air from below into the membrane bubble; An exhaust component for discharging air from above the membrane bubble; Its features are: The exhaust component includes an exhaust pipe located in the middle of the membrane bubble, and an exhaust port is provided at the top of the exhaust pipe; The exhaust pipe is provided with an exhaust chamber and a cold water circulation chamber, and the cold water circulation chamber is located between the exhaust chamber and the inner wall of the exhaust pipe. The exhaust pipe is connected to a cold water injection device, which is connected to the cold water circulation chamber. The cold water injection device causes cold water to flow from top to bottom in the cold water circulation chamber.

2. The plastic film cooling and forming apparatus according to claim 1, characterized in that: A flow guiding structure is provided in the cold water circulation cavity; the flow guiding structure forms a spiral cavity in the cold water circulation cavity, and the flow guiding structure forms a water injection cavity in the exhaust cavity; the water injection cavity is connected to the spiral cavity; The spiral cavity is in direct or indirect contact with the inner wall of the exhaust pipe.

3. The plastic film cooling and forming apparatus according to claim 2, characterized in that: The top of the water injection chamber is connected to the top of the spiral channel, so that a water flow from top to bottom is formed in the spiral channel.

4. The plastic film cooling and forming apparatus according to claim 2, characterized in that: Multiple heat sinks are provided on the inner wall of the exhaust pipe, and the heat sinks form multiple drainage chambers with multiple bends on the inner wall of the exhaust pipe.

5. The plastic film cooling and forming apparatus according to claim 4, characterized in that: An air injection structure is provided inside the exhaust pipe. The air injection structure has multiple air injection channels distributed along the height direction and an air storage chamber. The air injection channels and the air storage chamber are directly or indirectly connected to the heat sink for heat exchange. The exhaust pipe has multiple upward-sloping holes on its wall, and these holes are connected to the gas storage chamber.

6. The plastic film cooling and forming apparatus according to claim 5, characterized in that: A hydrophilic medium layer is provided on the inner wall of the inclined hole; the hydrophilic medium layer is attached to the inner wall of the inclined hole.

7. The plastic film cooling and forming apparatus according to claim 6, characterized in that: An enlarged hole is formed on the outer wall of the exhaust pipe, and the enlarged hole is connected to the inclined hole; The hydrophilic medium layer has a first bonding portion and a second bonding portion connected to the first bonding portion. The first bonding portion is bonded to the oblique hole, and the second bonding portion is bonded to a portion of the enlarged hole.

8. The plastic film cooling and forming apparatus according to claim 5, characterized in that: The gas injection structure includes an annular shell that forms the gas storage chamber; there is a gap between the annular shell and the outer side of the spiral plate.

9. The plastic film cooling and forming apparatus according to any one of claims 2-8, characterized in that: The flow guiding structure includes: a spiral plate and a water injection pipe; the water injection pipe is fixed to the spiral plate, and the spiral plate is located on the outer wall of the water injection pipe; An airflow conduit is provided inside the water injection pipe, and the water injection chamber is formed between the airflow conduit and the water injection pipe; The airflow duct forms the exhaust cavity; A driving component is provided at the water injection pipe, which is used to drive the water injection pipe to rotate so that the spiral plate rotates synchronously.

10. The plastic film cooling and forming apparatus according to claim 9, characterized in that: The spiral cavity is externally connected to a water tank; The water injection pipe is connected to the water injection tank via the aforementioned connection structure; The connection structure includes: a transfer housing, a rotary joint, a water injection pump body, and a connecting pipe; The transfer housing is connected to the water injection pipe via the rotary joint, and the transfer housing is connected to the water injection tank via the water injection pump and the connecting pipe in sequence; The airflow duct is inserted into the transfer housing and extends outward from the transfer housing.

Images