An exhaust system for use in a thin film production process

Abstract

The utility model discloses an exhaust system for film production process, including extrusion device, filter, die head and vacuum generating device, the discharge end of extrusion device is connected with the feed end of filter, and the discharge end of filter is connected with die head, the filter includes the filter core and the shell, the shell is equipped with the feed port and the discharge port, the feed port with the discharge port opposite setting in both ends of the shell, the shell still is equipped with first exhaust port, and the first exhaust port is located in one end close to the discharge port, the vacuum generating device is connected with first exhaust port through first pipeline. Through the inner chamber communication of vacuum generating device and filter, effectively remove the residual gas in the melt, reduce the bubble defect, have the advantage that improve exhaust thoroughness, promote the film quality and production efficiency.

Description

Technical Field

[0001] This utility model relates to the field of thin film production technology, and in particular to an exhaust system applied to thin film production processes. Background Technology

[0002] In the production of biaxially oriented films, melt filtration is a crucial step in ensuring the purity of raw materials and the final film performance. In existing processes, after each filter replacement, melt filling and venting are required inside the filter. If this process is insufficient or venting is incomplete, residual gas will enter the downstream flow channel with the melt and eventually mix into the extrusion melt.

[0003] These trapped gases easily form bubble defects during the melt cooling and forming process, which not only seriously affect the appearance quality of the film but also significantly reduce its mechanical properties, such as tensile strength and elongation. In addition, bubbles trapped in the melt can also interfere with the stability of subsequent biaxial stretching processes, easily leading to production anomalies such as film breakage and material interruption, which adversely affect the continuity of the entire production line and the yield.

[0004] Currently, most common venting methods rely on melt self-flowing filling and mechanical venting, which have limited effectiveness in removing gas and cannot guarantee complete removal of air from the filter. Therefore, the industry urgently needs a method that can efficiently and thoroughly remove residual gas from the filter to improve melt filling quality, reduce bubble-related defects, and ensure the stability of the film production process and product consistency. Utility Model Content

[0005] In response to the problems raised in the background art, the purpose of this utility model is to propose an exhaust system for thin film production processes, which solves the problem that in the prior art, after replacing the filter, the air inside the filter is not completely removed, resulting in unstable film production quality.

[0006] To achieve this objective, the present invention adopts the following technical solution: An exhaust system for use in film production processes includes an extrusion unit, a filter, a die head, and a vacuum generator; The discharge end of the extrusion device is connected to the feed end of the filter, and the discharge end of the filter is connected to the die head; The filter includes a housing and a filter element. The housing has an inlet and an outlet, which are disposed opposite to each other at both ends of the housing. The housing also has a first exhaust port, which is located at the end near the outlet. The vacuum generating device is connected to the first exhaust port via a first pipe.

[0007] Preferably, the vacuum generating device is connected to the exhaust section of the extrusion device via a second pipe.

[0008] Preferably, it further includes a control device, a first vacuum sensor, a first control valve, a second vacuum sensor, and a second control valve, wherein the first vacuum sensor, the first control valve, the second vacuum sensor, the second control valve, and the vacuum generating device are electrically connected to the control device. The first vacuum sensor is disposed in the inner cavity of the filter and is used to obtain the first vacuum value in the filter; the first control valve is disposed in the first pipe and is used to control the opening and closing of the first pipe. The second vacuum sensor is disposed in the exhaust section of the extrusion device and is used to obtain the second vacuum value of the exhaust section of the extrusion device; the second control valve is disposed in the second pipe and is used to control the opening and closing of the second pipe.

[0009] Preferably, the device further includes a booster pump, which is disposed between the extrusion device and the filter via a material delivery pipeline.

[0010] Preferably, the filter is arranged vertically, and the outer shell includes a cylindrical body, an upper end cover, and a lower end cover, wherein the upper end cover and the lower end cover are respectively sealed and fixed to both ends of the cylindrical body; The feed inlet is located on the lower end cover, and the discharge outlet and the first exhaust outlet are located on the upper end cover.

[0011] Preferably, exhaust blocks are provided at the connection between the first pipe and the filter and at the connection between the second pipe and the extrusion device.

[0012] Preferably, the interior of the exhaust block has a tortuous labyrinthine channel.

[0013] Preferably, the vacuum generating device includes a cooling assembly, a vacuum pump, and a medium tank connected in sequence; The first pipe and the second pipe are connected to the cooling assembly via a main pipe.

[0014] Compared with the prior art, one of the above technical solutions has the following beneficial effects: By connecting the vacuum generator to the inner cavity of the filter, residual gas in the melt is effectively removed, reducing bubble defects. This has the advantages of improving the thoroughness of venting, enhancing film quality, and increasing production efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of one embodiment of the present utility model; Figure 2 This is a schematic diagram of the control logic of a control system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of one embodiment of the filter of this utility model.

[0016] The components include: extrusion device 1, filter 2, feed inlet 201, discharge outlet 202, first exhaust port 203, cylinder 211, upper end cover 212, lower end cover 213, filter element 22, die head 3, vacuum generator 4, first pipe 411, second pipe 412, cooling assembly 42, vacuum pump 43, medium tank 44, control device 5, first vacuum sensor 511, first control valve 512, second vacuum sensor 521, second control valve 522, and booster pump 6. Detailed Implementation

[0017] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0018] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0020] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0021] The following is in conjunction with the appendix Figures 1 to 3 The technical solution of this utility model will be further illustrated through specific implementation methods.

[0022] In existing technologies, the melt filtration stage plays a decisive role in the purity of raw materials and the performance of the biaxially oriented film. Traditional processes require melt filling and venting after replacing the filter, but current venting methods mainly rely on melt gravity flow and mechanical venting, resulting in insufficient gas removal efficiency. Residual gas, carried by the melt into the downstream flow channel, forms bubble defects during the cooling and forming stage, leading to a decline in film appearance quality and mechanical property degradation, while also increasing the risk of film breakage during the biaxial stretching process. The industry has long faced the technical bottleneck of incomplete gas removal from filters, necessitating improvements to venting methods to enhance production stability.

[0023] To address the aforementioned issues, researchers observed that traditional passive venting methods suffer from the limitation of not being able to cover areas where gas stagnation occurs. Based on fluid mechanics principles, they proposed introducing an active suction mechanism during the melt filling stage. By combining the connection between the extrusion unit and the filter, a closed-loop venting system was constructed, enabling melt flow and vacuum suction to work synergistically, thus overcoming the physical limitations of traditional processes.

[0024] Therefore, this utility model proposes an exhaust system for use in film production processes, including an extrusion device 1, a filter 2, a die head 3, and a vacuum generator 4; The discharge end of the extrusion device 1 is connected to the feed end of the filter 2, and the discharge end of the filter 2 is connected to the die head 3; The filter 2 includes a housing and a filter element 22. The housing is provided with an inlet 201 and an outlet 202. The inlet 201 and the outlet 202 are disposed opposite to each other at both ends of the housing. The housing is also provided with a first exhaust port 203, which is located at the end near the outlet 202. The vacuum generating device 4 is connected to the first exhaust port 203 via the first pipe 411.

[0025] The extrusion unit 1 is the unit that melts and plasticizes the raw material and outputs it. It can be implemented using a single-screw extruder or a twin-screw extruder, and its discharge end is sealed to downstream equipment via a flange. The filter 2 is a device for separating impurities from the melt. It includes a housing and a filter element 22. The inlet 201 and outlet 202 are positioned opposite each other at both ends of the housing, forming a smooth axial flow channel, reducing melt flow resistance and potential vortex zones. The first exhaust port 203 is located near the filter outlet 202. The vacuum generator 4, connected to this specific location, can create a strong negative pressure environment in this area, actively, accurately, and efficiently removing trapped air before the melt arrives. This avoids the risk of gas being trapped by the flowing melt and carried downstream in traditional methods, preventing the generation of bubble defects at the source.

[0026] Specifically, after the melt is output from the extrusion device 1, it enters the filter 2 to trap impurities. At this time, the vacuum generator 4 applies negative pressure to the inner cavity of the filter 2 through the first pipe 411. During the melt filling stage, residual gas inside the filter 2 is actively extracted to prevent gas from entering the flow channel of the die head 3 with the melt. All components are connected by a sealed system to maintain the continuity of melt delivery while achieving efficient gas separation.

[0027] This solution establishes an active venting mechanism through vacuum generator 4, eliminating the physical limitations of passive venting, effectively reducing the probability of bubble defects in the melt, and improving the surface smoothness and mechanical property consistency of the film. The vacuum suction shortens the venting time during the filter filling stage, reducing the risk of film breakage due to residual gas, and ensuring the continuous operational stability of the biaxial stretching process after the film is output from die head 3.

[0028] Furthermore, the vacuum generating device 4 is connected to the exhaust section of the extrusion device 1 via the second pipe 412.

[0029] The second pipe 412 connects the vacuum generator 4 and the exhaust section of the extrusion unit 1. It can be implemented using a high-temperature resistant metal pipe or a composite flexible hose, establishing an independent vacuum suction path. Specifically, during the process of the melt being transported from the extrusion unit 1 to the filter 2, the second pipe 412 creates a directional suction effect in the exhaust section of the extrusion unit 1. When the melt flows through the exhaust section of the extrusion unit 1, the air bubbles entrained within it are forcibly extracted under negative pressure and enter the processing system of the vacuum generator 4 through the second pipe 412. This suction effect forms a gas barrier at the source of the melt flow, effectively capturing the gas before it enters the filter 2. The second pipe 412 and the first pipe 411 act on the exhaust section of the extrusion unit 1 and the chamber of the filter 2, respectively, achieving coordinated exhaust through independent regional control.

[0030] Furthermore, it also includes a control device 5, a first vacuum sensor 511, a first control valve 512, a second vacuum sensor 521, and a second control valve 522, wherein the first vacuum sensor 511, the first control valve 512, the second vacuum sensor 521, the second control valve 522, and the vacuum generating device 4 are electrically connected to the control device 5. The first vacuum sensor 511 is disposed in the inner cavity of the filter 2 and is used to obtain the first vacuum value in the filter 2; the first control valve 512 is disposed in the first pipe 411 and is used to control the opening and closing of the first pipe 411. The second vacuum sensor 521 is disposed in the exhaust section of the extrusion device 1 and is used to obtain the second vacuum value of the exhaust section of the extrusion device 1; the second control valve 522 is disposed in the second pipe 412 and is used to control the opening and closing of the second pipe 412.

[0031] The control device 5 receives signals from the first vacuum sensor 511 and the second vacuum sensor 521 and outputs control commands to the first control valve 512 or the second control valve 522. Specifically, it can be implemented using an industrial PLC or an embedded controller, with logic judgment and command output achieved through a preset program. The first vacuum sensor 511 detects the negative pressure state inside the filter 2, and its detected data (the first vacuum value) is used to determine the exhaust state of the filter 2's inner cavity. The first control valve 512 is an actuator used to regulate the opening and closing of the first pipeline 411. Specifically, it can be implemented using a solenoid valve or a pneumatic ball valve, controlling the connection between the vacuum generator 4 and the filter 2 through opening and closing actions. The second vacuum sensor 521 uses the same measurement principle as the first vacuum sensor 511 and is installed in the exhaust section of the extrusion device 1 to monitor the residual gas in that area. The second control valve 522 has the same structural features as the first control valve 512 and independently controls the opening and closing state of the second pipeline 412.

[0032] Specifically, during the melt filling stage, the control device 5 simultaneously receives vacuum level data from both the inner cavity of the filter 2 and the exhaust section of the extrusion device 1. When the first vacuum sensor 511 detects that the inner cavity of the filter 2 has not reached the set threshold, the control device 5 keeps the first control valve 512 open, allowing the vacuum generator 4 to continuously extract gas. Once the target vacuum level is reached, the first control valve 512 closes to prevent over-extraction. Simultaneously, the second vacuum sensor 521 monitors the pressure status of the exhaust section of the extrusion device 1 in real time. If residual gas is detected in this area, the second control valve 522 opens, allowing the vacuum generator 4 to perform auxiliary exhaust in that area. The two detection and control systems interact and work collaboratively through the control device 5 to ensure that gas in the two key areas of the melt flow path is completely eliminated.

[0033] Furthermore, it also includes a booster pump 6, which is disposed between the extrusion device 1 and the filter 2 via a material conveying pipe.

[0034] The booster pump 6 is used to apply additional delivery pressure to the melt, thereby actively increasing the pressure to change the melt flow state and overcoming the problem of insufficient pressure when the melt flows under its own weight. The conveying pipe is a melt transmission channel connecting the extrusion unit 1 and the filter 2. Its position is set to ensure that the pressure output by the booster pump 6 directly acts on the transmission path from the discharge end of the extrusion unit 1 to the feed end of the filter 2, avoiding the impact of pressure decay on the filling effect of the melt before entering the filter.

[0035] The booster pump 6 is configured in the feed pipe downstream of the extrusion unit. After the melt is output from the extrusion unit 1, the booster pump 6 actively applies pressure to drive the melt flow. This pressure increase causes the melt to enter the inner cavity of the filter 2 at a higher flow rate, quickly filling the cavity space and squeezing the residual gas to migrate towards the vacuum generator.

[0036] Furthermore, the filter 2 is arranged vertically, and the outer shell includes a cylindrical body 211, an upper end cover 212 and a lower end cover 213, with the upper end cover 212 and the lower end cover 213 respectively sealed and fixed to both ends of the cylindrical body 211; The feed inlet 201 is located on the lower end cover 213, and the discharge outlet 202 and the first exhaust outlet 203 are located on the upper end cover 212.

[0037] The sealed connection between the upper end cover 212, the lower end cover 213, and the cylinder 211 forms a smooth and unobstructed axial flow channel. The filter 2 is arranged vertically so that its axial centerline is parallel to the direction of gravity, creating a bottom-up flow path for the melt through this vertical layout. By placing the inlet 201 on the lower end cover 213 and concentrating the outlet 202 and the first exhaust port 203 on the upper end cover 212, this structure perfectly utilizes the principles of gravity and buoyancy. The melt flows from bottom to top, and the air bubbles it contains rise naturally under the influence of buoyancy, eventually all accumulating at the top of the filter 2—in the inner cavity of the upper end cover 212. This design precisely limits the gas enrichment area to a minimum, controllable range, allowing the vacuum generator 4 to efficiently and directionally extract the enriched gas through the first exhaust port 203, greatly improving the exhaust speed and thoroughness.

[0038] Furthermore, exhaust blocks are provided at the connection between the first pipe 411 and the filter 2 and at the connection between the second pipe 412 and the extrusion device 1, respectively.

[0039] A vent block is a gas-guiding structure installed at the connection point between pipes and equipment. For gases, which have low density and extremely low viscosity, they can easily pass through the gas-guiding structure inside the vent block and be vacuumed away. However, for melts, which have extremely high viscosity, a tremendous amount of thrust is required to flow through the gas-guiding channels inside the vent block. The vacuum suction force is very small compared to the thrust of the melt pump, insufficient to overcome the flow resistance of the melt in the labyrinthine channels, causing the melt to stagnate at the channel entrance. Therefore, the vent block allows gas to pass through quickly while acting as a physical barrier to the melt, ensuring the unobstructed flow of the vacuum lines (first pipe 411 and second pipe 412).

[0040] Furthermore, the interior of the exhaust block is provided with a tortuous labyrinthine channel.

[0041] A labyrinthine channel refers to a continuous flow channel structure with multiple turns, specifically constructed using baffles arranged in a spiral, U-shape, or serrated pattern. This structure creates flow resistance by altering the direction of fluid movement, forcing the gas and melt to separate within the channel.

[0042] Specifically, when the melt carrying gas passes through the exhaust block, the gas flows along the labyrinthine channel under the influence of vacuum negative pressure. The continuous turns of the channel lengthen the gas flow path and simultaneously create local turbulent regions. Due to its higher viscosity, the melt stagnates at the turns, while the gas, due to its lower density, continues to migrate towards the vacuum end. The baffles installed within the channel form multiple levels of obstruction, preventing the melt from directly entering the vacuum pipe. The gas gradually separates from the melt during multiple changes in flow direction and is eventually extracted by the vacuum system.

[0043] Furthermore, the vacuum generating device 4 includes a cooling assembly 42, a vacuum pump 43, and a medium tank 44 connected in sequence; The first pipe 411 and the second pipe 412 are connected to the cooling assembly 42 via a main pipe.

[0044] During vacuuming, condensable volatiles such as moisture and low-molecular-weight polymers in the melt will enter the pipeline as vapor. If they directly enter the vacuum pump 43, they will condense inside the pump, mixing and emulsifying with the medium (which can be water or oil) within the pump 43, leading to pump oil performance failure, pump body corrosion, and damage. By placing the cooling component 42 (such as a condenser or cold trap) before the vacuum pump 43 as a core pretreatment unit, it rapidly cools the high-temperature gas using refrigeration or cooling water, causing most of the condensable vapors to condense into liquid and be captured before entering the vacuum pump. This ensures that the gas entering the vacuum pump 43 is dry, clean, and at room temperature, greatly extending the service life and maintenance cycle of the vacuum pump.

[0045] Furthermore, the indiscriminate discharge of captured volatile condensate would cause pollution and waste; the direct emission of oil mist generated by the vacuum pump would pollute the environment. By setting up a media tank 44 as an integrated collection and treatment unit to collect and filter the oil-gas mixture discharged from the vacuum pump 43, the gas is discharged externally, and the media (water or oil) flows back to the media tank. This not only achieves centralized management and recycling of waste liquid and waste oil, avoiding environmental pollution, but also protects the workshop working environment and meets the requirements of clean production.

[0046] The technical principles of this utility model have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of this utility model and should not be construed as limiting the scope of protection of this utility model in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of this utility model without any inventive effort, and these embodiments will all fall within the scope of protection of this utility model.

Claims

1. An exhaust system for use in thin film manufacturing processes, characterized in that: Includes extrusion equipment, filters, dies, and vacuum generators; The discharge end of the extrusion device is connected to the feed end of the filter, and the discharge end of the filter is connected to the die head; The filter includes a housing and a filter element. The housing has an inlet and an outlet, which are disposed opposite to each other at both ends of the housing. The housing also has a first exhaust port, which is located at the end near the outlet. The vacuum generating device is connected to the first exhaust port via a first pipe.

2. The exhaust system for thin film production process according to claim 1, characterized in that: The vacuum generating device is connected to the exhaust section of the extrusion device via a second pipe.

3. The exhaust system for thin film production process according to claim 2, characterized in that: It also includes a control device, a first vacuum sensor, a first control valve, a second vacuum sensor, and a second control valve, wherein the first vacuum sensor, the first control valve, the second vacuum sensor, the second control valve, and the vacuum generating device are electrically connected to the control device. The first vacuum sensor is disposed in the inner cavity of the filter and is used to obtain the first vacuum value in the filter; the first control valve is disposed in the first pipe and is used to control the opening and closing of the first pipe. The second vacuum sensor is disposed in the exhaust section of the extrusion device and is used to obtain the second vacuum value of the exhaust section of the extrusion device; the second control valve is disposed in the second pipe and is used to control the opening and closing of the second pipe.

4. The exhaust system for thin film production process according to claim 3, characterized in that: It also includes a booster pump, which is installed between the extrusion device and the filter via a material delivery pipeline.

5. The exhaust system for thin film production process according to claim 4, characterized in that: The filter is arranged vertically, and the outer shell includes a cylindrical body, an upper end cover, and a lower end cover, with the upper end cover and the lower end cover respectively sealed and fixed to both ends of the cylindrical body; The feed inlet is located on the lower end cover, and the discharge outlet and the first exhaust outlet are located on the upper end cover.

6. The exhaust system for thin film production process according to claim 5, characterized in that: Exhaust blocks are provided at the connection between the first pipe and the filter and at the connection between the second pipe and the extrusion device, respectively.

7. The exhaust system for thin film production process according to claim 6, characterized in that: The interior of the exhaust block has a tortuous labyrinthine channel.

8. An exhaust system for use in thin film production processes according to any one of claims 2-7, characterized in that: The vacuum generating device includes a cooling assembly, a vacuum pump, and a medium tank connected in sequence. The first pipe and the second pipe are connected to the cooling assembly via a main pipe.

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