Polytetrafluoroethylene film circulating air uniform heating and stretching device

Abstract

The utility model discloses a kind of polytetrafluoroethylene film circulating air uniform heating stretching equipment, including equipment rack, stretching device, circulating air uniform heating system and control system, the equipment rack is sequentially provided with unwinding area, preheating zone, stretching zone and winding area, the circulating air uniform heating system includes the upper heating unit and lower heating unit of setting in stretching zone, heating element, circulating fan, air guide passage, multiple air outlets and return air port are all equipped in upper heating unit and lower heating unit, circulating fan is communicated with air guide passage, multiple air outlets and return air port are respectively arranged at different positions of air guide passage, form circulating air path.The utility model passes through the circulating air uniform heating system of symmetrical setting up, make hot air can simultaneously and uniformly act on the upper and lower surfaces of film, realized the temperature difference control in ±5 ℃ in film stretching process upper and lower, significantly improved the stretching uniformity and film thickness consistency.

Description

Technical Field

[0001] This utility model belongs to the field of thin film processing technology, specifically relating to a polytetrafluoroethylene (PTFE) thin film circulating air uniform heating and stretching device. Background Technology

[0002] Polytetrafluoroethylene (PTFE) film is widely used in aerospace, electronics, and chemical industries due to its excellent resistance to high and low temperatures, chemical corrosion, insulation, and low coefficient of friction. In the production of PTFE film, the stretching process is one of the key steps that determines the final performance and quality of the film.

[0003] Currently, the stretching process for polytetrafluoroethylene (PTFE) films mainly includes two methods: room temperature stretching and hot stretching. Hot stretching involves heating the film to a suitable temperature before stretching, which can give the film better physical and mechanical properties and dimensional stability. Existing hot stretching equipment typically uses bottom-space heating, that is, heating elements are placed at the bottom of the stretching zone to heat the film through thermal radiation and heat conduction. This heating method has the following technical drawbacks:

[0004] 1) The heat source is singular and fixed in location, resulting in a large temperature difference between the upper and lower surfaces of the film. There is a temperature difference of 10-15℃ between the upper and lower surfaces of the film, which affects the uniformity of stretching.

[0005] 2) The heat distribution is uneven, with a significant temperature gradient along the width of the film, and a large temperature difference between the edge region and the center region;

[0006] 3) It experiences large temperature fluctuations and is sensitive to changes in ambient temperature, making it difficult to control precisely;

[0007] 4) Low heating efficiency, low energy utilization, and long preheating time.

[0008] The aforementioned technical defects lead to uneven heating of the film during the stretching process, resulting in unsatisfactory stretching effects, such as uneven film thickness, inconsistent physical properties, and obvious edge effects, which seriously affect product quality and production efficiency.

[0009] Therefore, there is an urgent need for a polytetrafluoroethylene (PTFE) film stretching equipment that can achieve uniform heating of the upper and lower surfaces of the film, more uniform temperature distribution, and higher temperature control accuracy, so as to improve the stability of the stretching process and the consistency of film quality. Utility Model Content

[0010] The purpose of this invention is to address the aforementioned shortcomings in the existing technology by providing a polytetrafluoroethylene (PTFE) film circulating air uniform heating and stretching device. Through a circulating air uniform heating system symmetrically arranged at the top and bottom, uniform heating of the upper and lower surfaces of the film is achieved, making the temperature distribution of the film more uniform during the stretching process, thereby improving the stretching uniformity and film quality.

[0011] To achieve the above objectives, this utility model provides the following technical solution:

[0012] A polytetrafluoroethylene (PTFE) film circulating air uniform heating and stretching device includes a frame, a stretching device, and a control system. The frame is sequentially provided with an unwinding area, a preheating area, a stretching area, and a winding area. The stretching area includes a circulating air uniform heating system, which comprises an upper heating unit and a lower heating unit. The upper heating unit is located above the stretching device, and the lower heating unit is located below the stretching device. Both the upper and lower heating units are equipped with heating elements, a circulating fan, an air guide channel, multiple air outlets, and air return ports. The circulating fan is connected to the air guide channel, and the multiple air outlets and air return ports are respectively located at different positions in the air guide channel to form a circulating air path.

[0013] As a preferred embodiment of the present invention, the stretching device includes a front stretching roller group and a rear stretching roller group. The front stretching roller group is disposed at the front end of the stretching zone, and the rear stretching roller group is disposed at the rear end of the stretching zone. A stretching space is formed between the front stretching roller group and the rear stretching roller group. The upper heating unit and the lower heating unit are respectively disposed above and below the stretching space.

[0014] As a preferred embodiment of this utility model, both the front stretching roller group and the rear stretching roller group include two parallel stretching rollers arranged one above the other, with a gap formed between the two stretching rollers for the film to pass through.

[0015] As a preferred embodiment of the present invention, the preheating zone includes multiple preheating rollers and a preheating cover, the preheating cover being disposed around the multiple preheating rollers, and the multiple preheating rollers being arranged sequentially along the film conveying direction.

[0016] As a preferred embodiment of this utility model, both the upper heating unit and the lower heating unit have arc-shaped inner surfaces that are adapted to the arc-shaped path during film stretching, and the air outlets are evenly distributed along the arc-shaped inner surfaces.

[0017] As a preferred embodiment of this utility model, both the upper heating unit and the lower heating unit are equipped with multiple temperature sensors. The signal output terminal of the temperature sensor is electrically connected to the signal input terminal of the control system, and the control output terminal of the control system is electrically connected to the control input terminals of the heating element and the circulating fan, respectively.

[0018] In a preferred embodiment of the present invention, the unwinding zone includes an unwinding device, which includes an unwinding shaft, a tension control mechanism, and a braking device; the winding zone includes a winding device, which includes a winding shaft, a servo motor, and a web guiding device.

[0019] As a preferred embodiment of this utility model, the air guide channel is provided with multiple adjustable air guide baffles for adjusting the wind speed distribution at the air outlet.

[0020] Compared with the prior art, this utility model has the following advantages:

[0021] 1) This utility model achieves simultaneous and uniform action of hot air on the upper and lower surfaces of the film through a circulating air uniform heating system that is symmetrically arranged at the top and bottom. This effectively overcomes the problem of large temperature difference between the upper and lower surfaces caused by single bottom heating in the prior art. According to the test, the temperature difference between the upper and lower surfaces of the film is controlled within ±5℃, which significantly improves the stretching uniformity.

[0022] 2) The circulating air uniform heating system of this utility model adopts a design with multiple air outlets evenly distributed, so that the hot air can be evenly distributed along the width of the film, effectively eliminating the temperature gradient between the edge and the center, and making the heating of each part of the film more uniform.

[0023] 3) This utility model is equipped with multiple temperature sensors and an intelligent control system, which can monitor the temperature distribution of the thin film in real time and accurately control the temperature by adjusting the power of the heating element and the speed of the fan, thereby improving the temperature control accuracy and reducing temperature fluctuations.

[0024] 4) This utility model adopts a circulating air heating method, which has high heat utilization rate, shortens preheating time, and improves energy utilization efficiency.

[0025] 5) Practical application has proven that the polytetrafluoroethylene film processed by this utility model equipment has been effectively improved in terms of thickness uniformity, physical properties, product qualification rate, and production efficiency, and has significant economic benefits and technological progress. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the polytetrafluoroethylene film circulating air uniform heating and stretching device of this utility model.

[0028] Figure 2 This is a schematic diagram of the structure of the circulating air uniform heating system in the stretching zone of this utility model;

[0029] Figure 3This is a cross-sectional view of the heating unit of this utility model, showing the circulating air path system. Note: Since the internal structures of the upper and lower heating units are exactly the same, Figure 3 Only the internal structure of one of them needs to be shown.

[0030] In the diagram: 1. Equipment frame; 2. Unwinding area; 3. Stretching device; 4. Preheating area; 5. Stretching area; 6. Upper heating unit; 7. Lower heating unit; 8. Rewinding area; 9. Unwinding device; 10. Control system; 11. Preheating roller; 12. Preheating cover; 13. Front stretching roller group; 14. Rear stretching roller group; 15. Rewinding device; 16. Heating element; 17. Circulating fan; 18. Air guide channel; 19. Air outlet; 20. Return air outlet; 21. Temperature sensor; 22. Air guide baffle. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] Please see Figure 1 As shown, the polytetrafluoroethylene (PTFE) film circulating air uniform heating and stretching equipment provided by this utility model includes a frame 1, on which an unwinding zone 2, a preheating zone 4, a stretching zone 5, and a winding zone 8 are sequentially arranged. The unwinding zone 2 includes an unwinding device 9, which comprises an unwinding shaft, a tension control mechanism, and a braking device, used to control the stable release and tension control of the PTFE film raw material. The preheating zone 4 includes multiple preheating rollers 11 and a preheating cover 12. The multiple preheating rollers 11 are arranged sequentially along the film conveying direction, and the preheating cover 12 is disposed around the multiple preheating rollers 11, used to preheat the film entering the stretching zone 5, so that the film temperature reaches the initial temperature required for stretching. The winding zone 8 includes a winding device 15, which comprises a winding shaft, a servo motor, and a web guiding device, used to wind up the stretched film and maintain appropriate tension.

[0033] Please see Figure 1 and Figure 2As shown, the stretching zone 5 includes a stretching device 3 and a circulating air uniform heating system. The stretching device 3 includes a front stretching roller group 13 and a rear stretching roller group 14. The front stretching roller group 13 is located at the front end of the stretching zone 5, and the rear stretching roller group 14 is located at the rear end of the stretching zone 5, forming a stretching space between the front stretching roller group 13 and the rear stretching roller group 14. Both the front stretching roller group 13 and the rear stretching roller group 14 include two parallel stretching rollers arranged one above the other, forming a gap between the two stretching rollers for the film to pass through. The linear velocity of the rear stretching roller group 14 is greater than the linear velocity of the front stretching roller group 13, forming a stretching ratio, thereby achieving the stretching of the film.

[0034] The circulating air uniform heating system is the core component of this invention, comprising an upper heating unit 6 and a lower heating unit 7 symmetrically arranged. The upper heating unit 6 is positioned above the stretching device 3, and the lower heating unit 7 is positioned below the stretching device 3, corresponding to the upper and lower surfaces of the film within the stretching space, respectively.

[0035] Please see Figure 2 and Figure 3 As shown, the upper heating unit 6 and the lower heating unit 7 have the same structure, both including a heating element 16, a circulating fan 17, an air guide channel 18, multiple air outlets 19, and a return air inlet 20. The heating element 16 can be an electric heating tube or other heating device, used to heat the circulating air. The circulating fan 17 is connected to the air guide channel 18 and is used to drive the hot air to circulate within the air guide channel 18. Multiple air outlets 19 and return air inlets 20 are provided within the air guide channel 18. The air outlets 19 are evenly distributed on the side close to the film, and the return air inlets 20 are located on the side away from the film, forming a complete circulating air path where the air driven by the circulating fan 17 is heated by the heating element 16, blown out of the air outlets 19 through the air guide channel 18 to act on the film surface, and then returned through the return air inlets 20.

[0036] Both the upper heating unit 6 and the lower heating unit 7 have arc-shaped inner surfaces adapted to the arc-shaped path during film stretching. The air outlets 19 are evenly distributed along the arc-shaped inner surfaces to ensure that hot air can act evenly on the film surface throughout the stretching process. The air guide channel 18 is equipped with multiple adjustable air guide baffles 22, which can adjust the air velocity distribution at each air outlet 19 according to actual needs, further optimizing the hot air distribution.

[0037] To precisely control the temperature, multiple temperature sensors 21 are installed in both the upper heating unit 6 and the lower heating unit 7 to monitor the temperature at different locations on the film surface and in the space. The signal output terminals of the temperature sensors 21 are electrically connected to the signal input terminals of the control system 10, and the control output terminals of the control system 10 are electrically connected to the control input terminals of the heating element 16 and the circulating fan 17, respectively. The control system 10 has a built-in PLC controller and temperature control algorithm, which can automatically adjust the heating power of the heating element 16 and the rotation speed of the circulating fan 17 based on the feedback signals from the temperature sensors 21, thereby achieving precise temperature control within the stretching zone 5.

[0038] The working principle and process of this utility model are as follows:

[0039] First, the polytetrafluoroethylene (PTFE) film raw material is mounted on the unwinding device 9, and the film is released through the unwinding zone 2 while maintaining appropriate tension. After the film enters the preheating zone 4, it is conveyed by multiple preheating rollers 11 and preheated by the preheating hood 12, so that the film temperature gradually rises to the initial temperature required for stretching.

[0040] The preheated film enters the stretching zone 5 and passes through the front stretching roller group 13 into the stretching space. At this time, the circulating air uniform heating system starts working. The heating elements 16 in the upper heating unit 6 and the lower heating unit 7 heat the air, and the circulating fan 17 drives the hot air to be blown evenly onto the upper and lower surfaces of the film through the air guide channel 18 and multiple air outlets 19. After the hot air comes into contact with the film, it evenly transfers heat to the film, so that the temperature of the upper and lower surfaces of the film rises uniformly and is maintained within the ideal stretching temperature range.

[0041] Temperature sensor 21 monitors the film temperature and ambient temperature in real time and feeds the signal back to control system 10. Based on the temperature signal, control system 10 automatically adjusts the power of heating element 16 and the rotation speed of circulating fan 17 to ensure uniform and stable temperature distribution within the stretching zone 5 at the set value. Simultaneously, the airflow distribution at each air outlet 19 can be optimized by adjusting the angle of the air guide baffle 22, further improving temperature uniformity.

[0042] The film is stretched by the difference in linear velocity between the front stretching roller group 13 and the rear stretching roller group 14 while maintaining a uniform temperature. The stretched film then passes through the rear stretching roller group 14 into the winding area 8, where it is wound up by the winding device 15. During winding, a web guiding device ensures that the film edges are aligned to prevent deviation.

[0043] By employing the aforementioned circulating air uniform heating method, this invention achieves uniform heating of the upper and lower surfaces of the film, overcoming the temperature unevenness problem caused by single-sided bottom heating in existing technologies. Actual testing shows that the temperature difference between the upper and lower surfaces of the film is controlled within ±5℃ during heating, significantly lower than the 10-15℃ temperature difference of traditional equipment, and the temperature uniformity in the film width direction is improved by 40%.

[0044] In addition, this utility model has the following advantages: the circulating air heating method has high thermal efficiency and the preheating time is shortened by 30%; the multi-point temperature monitoring and intelligent control system significantly improves the temperature control accuracy, and the temperature difference between the upper and lower surfaces of the film is controlled within ±5℃; the film is heated evenly, has good stretching uniformity, and the thickness uniformity of the final product is improved by 25%, and the consistency of physical properties is improved by 30%; the product qualification rate is increased by 15%, and the production efficiency is increased by 20%.

[0045] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A polytetrafluoroethylene (PTFE) film circulating air uniform heating and stretching device, comprising a frame (1), a stretching device (3), and a control system (10), characterized in that, The equipment frame (1) is provided with an unwinding area (2), a preheating area (4), a stretching area (5) and a winding area (8) in sequence. The stretching area (5) includes a circulating air uniform heating system, which includes an upper heating unit (6) and a lower heating unit (7). The upper heating unit (6) is located above the stretching device (3), and the lower heating unit (7) is located below the stretching device (3). The upper heating unit (6) and the lower heating unit (7) are each provided with a heating element (16), a circulating fan (17), an air guide channel (18), multiple air outlets (19) and return air outlets (20). The circulating fan (17) is connected to the air guide channel (18). The multiple air outlets (19) and return air outlets (20) are respectively located at different positions in the air guide channel (18) to form a circulating air path.

2. The polytetrafluoroethylene film circulating air uniform heating and stretching equipment according to claim 1, characterized in that, The stretching device (3) includes a front stretching roller group (13) and a rear stretching roller group (14). The front stretching roller group (13) is located at the front end of the stretching zone (5), and the rear stretching roller group (14) is located at the rear end of the stretching zone (5). A stretching space is formed between the front stretching roller group (13) and the rear stretching roller group (14). The upper heating unit (6) and the lower heating unit (7) are respectively located above and below the stretching space.

3. The polytetrafluoroethylene film circulating air uniform heating and stretching equipment according to claim 2, characterized in that, Both the front stretching roller group (13) and the rear stretching roller group (14) include two parallel stretching rollers arranged vertically, with a gap between the two stretching rollers for the film to pass through.

4. The polytetrafluoroethylene film circulating air uniform heating and stretching equipment according to claim 1, characterized in that, The preheating zone (4) includes multiple preheating rollers (11) and a preheating cover (12). The preheating cover (12) is located around the multiple preheating rollers (11), and the multiple preheating rollers (11) are arranged sequentially along the film conveying direction.

5. The polytetrafluoroethylene film circulating air uniform heating and stretching equipment according to claim 1, characterized in that, Both the upper heating unit (6) and the lower heating unit (7) have arc-shaped inner surfaces that are adapted to the arc-shaped path during film stretching, and the air outlets (19) are evenly distributed along the arc-shaped inner surfaces.

6. The polytetrafluoroethylene film circulating air uniform heating and stretching equipment according to claim 1, characterized in that, Both the upper heating unit (6) and the lower heating unit (7) are equipped with multiple temperature sensors (21). The signal output terminal of the temperature sensor (21) is electrically connected to the signal input terminal of the control system (10). The control output terminal of the control system (10) is electrically connected to the control input terminal of the heating element (16) and the circulating fan (17), respectively.

7. The polytetrafluoroethylene film circulating air uniform heating and stretching equipment according to claim 1, characterized in that, The unwinding zone (2) includes an unwinding device (9), which includes an unwinding shaft, a tension control mechanism, and a braking device. The winding zone (8) includes a winding device (15), which includes a winding shaft, a servo motor, and a correction device.

8. The polytetrafluoroethylene film circulating air uniform heating and stretching equipment according to claim 1, characterized in that, The air guide channel (18) is equipped with multiple adjustable air guide baffles (22) to adjust the wind speed distribution at the air outlet (19).

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