An oven airlock door structure for a film production line

Abstract

The application discloses a kind of thin film production line with oven air seal door structure, including air seal door, air charge and discharge assembly and door buckle assembly, door handle is provided on the air seal door;The air seal door is connected with oven box by hinge, including the door body formed by the butt joint of door inner frame and door outer frame, heat insulation material is filled in the inner chamber of door body, and air seal strip is installed on the sealing end face of door body;The air charge and discharge assembly is configured bidirectional control structure, including first mechanical valve, second mechanical valve, telescopic transmission shaft, swing bar and tension spring;The door buckle assembly is used to realize sealing door closed accurate positioning, pre-tightening locking, prevent door body deviation and shake and cause sealing failure, including door buckle base, door buckle spring, positioning steel ball, door buckle pressing plate and door buckle spring piece.The thin film production line with oven air seal door structure of the application has less downtime, no local leakage during long-term operation, and strong equipment running stability.

Description

Technical Field

[0001] This invention relates to the field of plastic film production technology, and more specifically to an air-sealed door structure for an oven used in a film production line. Background Technology

[0002] In the industrial production of high-end special optical films such as TAC film (cellulose triacetate film), a large amount of corrosive organic solvent volatile gas will be continuously generated inside the oven. Such production scenarios have high requirements for the sealing performance, corrosion resistance, high temperature resistance and long-term stability of the oven door, and the equipment must achieve zero leakage. Currently, the industry mainly uses mechanical compression rubber strip sealing and labyrinth sealing combined with nitrogen curtain sealing for oven sealing. However, all of these methods have certain technical shortcomings. For example, relying on mechanical sealing to achieve a tight seal is prone to rapid swelling, aging, and failure under conditions of high temperature above 100°C and long-term corrosive volatile gases. Leakage occurs on average every 3 months. Moreover, this structure has poor sealing uniformity, and uneven pressure at a single point can cause local seal failure, requiring frequent shutdowns for manual pressure adjustment and maintenance. This results in long downtime and high maintenance frequency, seriously affecting the continuous and stable production of the production line. On the other hand, relying on airflow barrier to protect against corrosive gases has high overall energy consumption and high long-term operating costs. Furthermore, the gas barrier effect is limited, with an overall barrier rate of only 70-80%. There is still 20-30% of corrosive volatile gases leaking out without organization, which not only pollutes the production environment and corrodes surrounding equipment but also causes imbalances in temperature and airflow stability inside the oven, affecting the production precision and product quality of special optical films. It is impossible to achieve a truly zero-leakage seal.

[0003] Currently, airtight doors are also used in some areas in China, but the application fields and usage methods vary, such as:

[0004] The utility model patent with publication number CN202092834U discloses an automatic inflation and sealing mechanism, which is mainly used for the air tightness testing of the rear axle of automobiles. It achieves sealing by driving a conical inflation head with a rubber sleeve through a cylinder. The structure is designed for workpiece testing scenarios, but it lacks a structure that is resistant to high temperature and solvent corrosion. It cannot be adapted to the long-term high temperature and corrosion conditions of the oven, nor does it have the functions of closing and sealing the equipment door and opening and closing the door in both directions.

[0005] The utility model patent with publication number CN202381820U discloses an automatic inflation device for an inflation sealing valve, which mainly solves the problem of synchronizing the operation of the inflation sealing valve and the air cylinder. The structure focuses on the inflation control of a small valve body, and lacks an overall door sealing, heat insulation protection, and precise positioning structure, so it cannot be used in the scenario of sealing the door of a large oven.

[0006] Utility model patent CN203452598U discloses an integrated inflatable airtight door, which integrates the door body, door frame, and accessories into one unit. The door body has inflatable rubber strips embedded in grooves around its perimeter. The door frame is equipped with a wire-sealing device, which consists of a junction box, a conduit, and an airtight aviation socket. The accessories include a door closer, an electromagnetic lock, a door switch sensor, an emergency stop switch, a control panel, gas pipelines, and an emergency relief valve. This utility model employs a double-sided sealing structure to adapt to both positive and negative pressure spaces. Combined with the emergency relief valve and double-sided emergency stop switch, it features a dual safety structure, allowing for rapid pressure relief and door opening in emergency situations. It exhibits excellent airtightness and is suitable for low-leakage protection scenarios such as biosafety laboratories. However, it does not optimize the sealing structure for organic solvent corrosion and high-temperature aging conditions. Furthermore, its opening and closing control and positioning locking structure are relatively simple, failing to meet the requirements of high-frequency maintenance and long-term stable sealing in industrial ovens.

[0007] In summary, existing oven sealing structures generally suffer from common technical problems such as poor resistance to high-temperature solvent corrosion, large leakage, high maintenance frequency, high downtime losses, high operating costs, and inability to achieve zero leakage. These problems severely restrict the high-quality, high-efficiency, and low-cost production of high-end special optical films. There is an urgent need to develop a special oven sealing door structure that is suitable for high-temperature and corrosive working conditions, with zero leakage and low maintenance. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a gas-filled sealing door structure for an oven in a thin film production line that minimizes downtime maintenance, prevents local leakage during long-term operation, and ensures strong equipment operational stability.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A gas-filled sealing door structure for an oven used in a thin-film production line includes a gas-filled sealing door, a gas filling and deflation assembly, and a door latch assembly. The gas-filled sealing door is connected to the oven body via a hinge, and a door handle is provided on the gas-filled sealing door. Unlike existing technologies, the following features are included:

[0011] The inflatable sealing door includes a door body, which is formed by assembling an inner door frame and an outer door frame together. A heat insulation pad is provided at the connection between the inner door frame and the outer door frame. The inner cavity of the door body is filled with heat insulation material, and an inflatable sealing strip is installed on the sealing end face of the door body.

[0012] The inflation / deflation assembly includes a first mechanical valve, a second mechanical valve, a telescopic drive shaft, a rocker arm, and a tension spring. The first and second mechanical valves are located within the inner cavity of the door body. The sliding end of the telescopic drive shaft is fitted with a compression spring and then fixedly connected to the valve core of the second mechanical valve. Its fixed end extends out of the inner door frame and is mounted on the inner door frame via a bushing. One end of the rocker arm is fixedly connected to the valve core of the first mechanical valve, and its other end is connected to a door handle located on the outer door frame via a tension spring. The gas inlet of the second mechanical valve is connected to a gas supply pipeline, and its gas outlet is connected to the gas inlet pipeline of the first mechanical valve. The gas outlet of the first mechanical valve is connected to the gas inlet pipeline of the inflation sealing strip.

[0013] The door latch assembly includes a door latch base, a door latch spring, a positioning steel ball, a door latch pressure plate, and a door latch spring sheet. The door latch pressure plate has a first through hole penetrating its thickness, and the door latch spring sheet has a second through hole penetrating its thickness. The diameter of the first through hole is larger than the diameter of the second through hole but smaller than the diameter of the positioning steel ball. The door latch base is fixed to the outer frame of the inflatable sealing door. The door latch spring and the positioning steel ball are assembled in the inner cavity of the door latch base. The door latch pressure plate confines the positioning steel ball within the inner cavity of the door latch base. The door latch spring sheet is fixed to the oven body at a position corresponding to the door latch base, and the center of the second through hole on the door latch spring sheet, the center of the first through hole on the door latch pressure plate, and the center of the positioning steel ball are all on the same vertical line.

[0014] Furthermore, there are two sets of door latch assemblies, which are respectively installed at the top and bottom of the inflatable sealing door.

[0015] Furthermore, an O-ring is provided between the fixed end of the telescopic drive shaft and the bushing.

[0016] Furthermore, a shut-off valve and a pressure regulating valve are also installed on the pipeline connecting the gas inlet of the second mechanical valve and the gas source.

[0017] Furthermore, the inflatable sealing strip is an inflatable sealing strip that is resistant to organic solvents and high temperatures, such as fluororubber, fluorosilicone rubber, perfluoroether rubber (FFKM), or solvent-modified silicone rubber.

[0018] Compared with the prior art, the present invention is characterized by:

[0019] 1. The sealing surface of the inflatable sealing door adopts a flexible and uniform expansion seal, replacing the traditional mechanical point-pressing seal. The sealing surface has no gaps or dead corners, and the sealing barrier rate is 100%, which completely solves the problem of unorganized leakage of exhaust gas, protects the workshop environment and surrounding equipment, and stabilizes the internal temperature field and flow field of the oven, avoiding color difference and thickness deviation of the film due to airflow and temperature fluctuations, significantly improving the quality and yield of optical films.

[0020] 2. Equipped with a dual mechanical valve independent pressure relief structure, it enables bidirectional operation of opening the oven door for routine external maintenance and opening the oven door inside in emergency situations. It is suitable for various maintenance scenarios, with fast opening and closing response and convenient operation, significantly improving equipment operation and maintenance efficiency.

[0021] 3. The door latch assembly is equipped with a special positioning steel ball locking and door latch spring pre-tightening structure, which ensures that the door closes in a precise and uniform position every time, preventing the door from loosening or shifting, ensuring uniform sealing with each inflation, and preventing seal decay and local leakage during long-term operation, resulting in strong equipment operation stability.

[0022] 4. Adopting constant pressure pneumatic adaptive sealing, there is no need for monthly shutdowns for manual pressure adjustment and calibration. It eliminates problems such as uneven single-point compression and local seal failure, allowing the equipment to operate continuously and stably for a long time, significantly reducing downtime maintenance time and improving the continuous production efficiency and capacity of the production line.

[0023] 5. Furthermore, a special inflatable sealing strip resistant to organic solvents and high temperatures is used, combined with a multi-layer heat insulation structure for the door, which can withstand high temperatures of 100℃~250℃ and corrosive volatile gases for a long time, completely solving the problem of swelling and failure of traditional solid rubber strips after 3 months. The service life of the sealing components is effectively improved (more than 6 times) and the replacement cost of parts is greatly reduced. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of one embodiment of the gas-filled sealing door structure for the drying oven in the thin film production line described in this invention.

[0025] Figure 2 for Figure 1 A schematic diagram of the AA section of the embodiment shown.

[0026] Figure 3 for Figure 1 A schematic diagram of the inflation / deflation assembly in the embodiment shown.

[0027] Figure 4 for Figure 1 The diagram illustrates the inflation / deflation principle of the embodiment shown.

[0028] Figure 5 for Figure 1 A schematic diagram of the door latch assembly in the embodiment shown.

[0029] The numbers on the map are:

[0030] 1. Inflatable sealing door, 101 Inner door frame, 102 Inflatable sealing strip, 103 Outer door frame, 104 Heat insulation pad, 105 Heat insulation material; 2. Inflation and deflation assembly, 201 First mechanical valve, 202 Second mechanical valve, 203 Compression spring, 204 Telescopic drive shaft, 205 O-ring seal, 206 Bushing, 207 Rocker arm, 208 Tension spring, 209 Stop valve, 210 Pressure regulating and reducing valve; 3. Hinges; 4. Door handles; 5. Door latch assembly, 501 Door latch base, 502 Door latch spring, 503 Positioning steel ball, 504 Door latch pressure plate, 505 Door latch spring, 6. Oven body. Detailed Implementation

[0031] To better explain the technical solution of the present invention, the present invention will be described in further detail below with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0032] like Figure 1 and Figure 2 As shown, the air-filled sealing door structure for the film production line oven of the present invention includes an air-filled sealing door 1, an air-filling and deflation assembly 2, and a door latch assembly 5. The air-filled sealing door 1 includes a door body, which is formed by the butt joint assembly of an inner door frame 101 and an outer door frame 103. The inner cavity of the door body is filled with heat-insulating material 105 to achieve overall heat insulation. A heat-insulating pad 104 is set at the connection between the inner door frame 101 and the outer door frame 103 to block the high temperature of the oven from the inside to the outside, thus acting as a heat-breaking bridge. An air-filled sealing strip 102 is embedded in the sealing end face of the door body (around the inner door frame 101, i.e., the contact surface between the inner door frame 101 and the oven body 6). The air-filled sealing strip 102 expands uniformly after inflation and retracts uniformly after deflation. The use of the air-filled sealing strip 102 to replace the traditional mechanical compression sealing ensures uniform force on the sealing surface and eliminates defects such as local compression failure. For the material of the inflatable sealing strip 102, a special inflatable sealing material that is resistant to organic solvent corrosion and high temperature is preferred, such as fluororubber, fluorosilicone rubber, perfluoroether rubber (FFKM), or solvent-modified silicone rubber. The side of the inflatable sealing door 1 is hinged to the oven body 6 by three sets of hinges 3, and a door handle 4 is provided on the outer frame 103 of the inflatable sealing door 1 to realize the flexible opening and closing of the inflatable sealing door 1.

[0033] The inflation / deflation assembly 2 is installed in the middle of the door body. For example... Figure 3As shown, the inflation / deflation assembly 2 is equipped with a bidirectional control structure, including a first mechanical valve 201, a second mechanical valve 202, a telescopic drive shaft 204, a rocker arm 207, and a tension spring 208. The first and second mechanical valves 201 and 202 are fixedly installed inside the door cavity. The sliding end of the telescopic drive shaft 204, after being fitted with a compression spring 203, is fixedly connected to the valve core of the second mechanical valve 202. Its fixed end extends out of the inner door frame 101 and is installed on the inner door frame 101 via a bushing 206. An O-ring 205 is fitted between the fixed end of the telescopic drive shaft 204 and the bushing 206 to achieve dynamic sealing of the control air path and prevent micro-leakage. Pressing the fixed end of the telescopic drive shaft 204 activates the second mechanical valve 202, thereby releasing pressure; releasing it allows for automatic reset. This operation is performed inside the oven. One end of the swing arm 207 is fixed to the valve core of the first mechanical valve 201, and the other end is connected to the door handle 4 on the outer frame 103 via a tension spring 208. Pulling the door handle 4 on the outer frame 103 causes the tension spring 208 to act on the first mechanical valve 201, thereby releasing air and opening the door. Through the dual-valve independent control structure, pressure release and unlocking can be completed both inside and outside the oven, meeting the needs of equipment maintenance and preventing situations where workers accidentally close the oven door during maintenance and cannot open it again.

[0034] The air circuit system of the inflation / deflation assembly 2 is as follows Figure 4 As shown, a pressure-stabilizing gas supply circuit is formed by a gas source, a shut-off valve 209, and a pressure regulating and reducing valve 210 connected in series. The working pressure can be constantly adjusted to the pressure that matches the optimal expansion sealing amount of the inflatable sealing strip 102 (e.g., 0.6~0.8MPa, to meet the zero-leakage sealing function). The shut-off valve 209 and the pressure regulating and reducing valve 210 are connected in series to the air inlet of the gas source to open and close the gas path and achieve a constant inflation pressure, ensuring a stable and consistent expansion amount of the sealing strip. After passing through the shut-off valve 209 and the pressure regulating and reducing valve 210 in sequence, the supplied gas enters the second mechanical valve 202 through the gas inlet. The gas then enters the first mechanical valve 201 through the gas inlet via the pipeline from the gas outlet of the second mechanical valve 202, and is then fed into the inflation sealing strip 102 through the gas outlet of the first mechanical valve 201. The first mechanical valve 201 and the second mechanical valve 202 correspond to the external and internal pressure relief positions, respectively, to meet the bidirectional opening requirements of the oven body 6. Outside the oven, the pressure is released by pulling the door handle 4, which is then acted upon by the tension spring 208 on the first mechanical valve 201. Inside the oven, the pressure is released by pressing the fixed end of the telescopic transmission shaft 204, which acts upon the second mechanical valve 202.

[0035] The door latch assembly 5 is used to achieve precise positioning and pre-tightening locking when the sealed door is closed, preventing door misalignment and shaking that could lead to sealing failure. Two sets of door latch assemblies 5 are used, one at the top and one at the bottom of the inflatable sealed door 1. Figure 5 As shown, the door latch assembly 5 includes a door latch base 501, a door latch spring 502, a positioning steel ball 503, a door latch pressure plate 504, and a door latch spring piece 505. The door latch pressure plate 504 has a first through hole that penetrates its thickness, and the door latch spring piece 505 has a second through hole that penetrates its thickness. The diameter of the first through hole is larger than the diameter of the second through hole and smaller than the diameter of the positioning steel ball 503. The door latch base 501 is fixedly installed at the bottom or top of the outer frame 103 of the inflatable sealing door 1. The door latch spring 502 and the positioning steel ball 503 are assembled in the inner cavity of the door latch base 501. The door latch pressure plate 504 is located at the open end of the door latch base 501, which restricts the positioning steel ball 503 in the inner cavity of the door latch base 501. The door latch spring piece 505 is fixed on the oven body 6 at the corresponding position of the door latch base 501, and the center of the second through hole on the door latch spring piece 505, the center of the first through hole on the door latch pressure plate 504, and the center of the positioning steel ball 503 are on the same longitudinal vertical line. When the door is manually closed, the positioning steel ball 503 is engaged and positioned under the elastic force of the door latch spring 502, and falls into the designated locking position on the door latch spring 505 under the elastic force of the door latch spring 505, restricting the door from shaking or shifting, realizing the door's gapless locking and positioning, ensuring that the door's closing position is consistent each time, making the expansion gap of the inflatable sealing strip 102 uniform and the sealing pressure consistent, and completely avoiding local gap leakage.

[0036] When the equipment is in normal production operation, the shut-off valve 209 is in the normally open state. The air supply (compressed air) passes through the shut-off valve 209 and is then pressure-regulated by the pressure-reducing valve 210 before continuously inflating the air-filled sealing strip 102. The air-filled sealing strip 102 expands evenly and fits against the sealing end face of the oven. Then, it is locked in place with the door latch assembly 5, achieving a full-circumference gapless zero-leakage seal, effectively isolating the high-temperature and corrosive organic solvent evaporation gas inside the oven from leakage. During external maintenance, the air circuit can be quickly depressurized by pulling the door handle 4 on the outer frame 103, which acts on the first mechanical valve 201. After depressurization, the air-filled sealing strip 102 retracts, releasing the sealing contact, and the door can be easily opened through the door handle 4. After maintenance, the door is closed, and the air circuit automatically stabilizes and refills, restoring the zero-leakage seal. No manual mechanical tightening or pressure adjustment is required throughout the process. In an emergency where staff are trapped inside the oven, the door can be opened by pressing the fixed end of the telescopic drive shaft 204, which acts on the second mechanical valve 202.

[0037] The applicant conducted high-temperature corrosion tests on the structure described in this application. The results showed that the inflatable sealing door structure of this invention can withstand high temperature of 220℃ and organic solvent corrosion for a long time. The service life of the inflatable sealing strip 102 can reach more than 24 months. No need to stop the machine to adjust the pressure throughout the process. Zero leakage of exhaust gas is achieved. The temperature field fluctuation inside the oven is small. It effectively solves defects such as color difference, spots and uneven thickness of optical thin films, and greatly improves the product yield.

Claims

1. A gas-filled sealing door structure for a film production line oven, comprising a gas-filled sealing door (1), a gas filling and defilling assembly (2), and a door latch assembly (5), wherein the gas-filled sealing door (1) is connected to the oven body (6) via a hinge (3), and a door handle (4) is provided on the gas-filled sealing door (1); characterized in that, The inflatable sealing door (1) includes a door body, which is formed by the butt joint assembly of an inner door frame (101) and an outer door frame (103). A heat insulation pad (104) is provided at the connection between the inner door frame (101) and the outer door frame (103). The inner cavity of the door body is filled with heat insulation material (105), and an inflatable sealing strip (102) is installed on the sealing end face of the door body. The inflation / deflation assembly (2) includes a first mechanical valve (201), a second mechanical valve (202), a telescopic drive shaft (204), a rocker arm (207), and a tension spring (208). The first mechanical valve (201) and the second mechanical valve (202) are located in the inner cavity of the door body. The sliding end of the telescopic drive shaft (204) is fitted with a compression spring (203) and then fixedly connected to the valve core of the second mechanical valve (202). Its fixed end extends out of the inner frame (101) and is installed on the door through a bushing (206). On the inner frame (101); one end of the swing rod (207) is fixed to the valve core of the first mechanical valve (201), and the other end is connected to the door handle (4) set on the outer frame (103) through the tension spring (208); the gas inlet of the second mechanical valve (202) is connected to the gas supply pipeline, and its gas outlet is connected to the gas inlet pipeline of the first mechanical valve (201), and the gas outlet of the first mechanical valve (201) is connected to the gas inlet pipeline of the inflatable sealing strip (102); The door latch assembly (5) includes a door latch base (501), a door latch spring (502), a positioning steel ball (503), a door latch pressure plate (504), and a door latch spring (505). The door latch pressure plate (504) has a first through hole penetrating its thickness, and the door latch spring (505) has a second through hole penetrating its thickness. The diameter of the first through hole is larger than the diameter of the second through hole and smaller than the diameter of the positioning steel ball (503). The door latch base (501) is fixed to the outer frame of the inflatable sealing door (1). On (103), the door latch spring (502) and the positioning steel ball (503) are assembled in the inner cavity of the door latch base (501), and the door latch pressure plate (504) restricts the positioning steel ball (503) in the inner cavity of the door latch base (501); the door latch spring (505) is fixed on the oven body (6) at the corresponding position of the door latch base (501), and the center of the second through hole on the door latch spring (505), the center of the first through hole on the door latch pressure plate (504) and the center of the positioning steel ball (503) are on the same longitudinal vertical line.

2. The air-sealed door structure for an oven used in a thin film production line according to claim 1, characterized in that, The number of door latch assemblies (5) is two sets, which are respectively set at the top and bottom of the inflatable sealing door (1).

3. The air-filled sealing door structure for an oven used in a thin film production line according to claim 1 or 2, characterized in that, The gas inlet of the second mechanical valve (202) is also equipped with a shut-off valve (209) and a pressure regulating valve (210) on the pipeline connecting the gas inlet to the gas source.

4. The air-filled sealing door structure for an oven used in a thin film production line according to claim 1 or 2, characterized in that, An O-ring (205) is provided between the fixed end of the telescopic drive shaft (204) and the bushing (206).

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