Graded pressure relief vacuumizing method and device for aluminum foil coated nano insulation board

Abstract

The invention relates to a graded pressure relief vacuumizing method and device for an aluminum foil-coated nano insulation board, and the method specifically comprises the steps: S1, placing an aluminum foil vacuum bag with a built-in nano insulation board in a vacuumizing device, and enabling a bag opening to be positioned at a heat sealing station of the vacuumizing device; s2, the aluminum foil vacuum bag is covered with a silica gel plate; s3, a vacuumizing device is started, and the interior of the aluminum foil vacuum bag is vacuumized; micro-amplitude vibration is applied to the area where the first air cavity and the second air cavity are located in the vacuumizing process; s4, after vacuumizing reaches the preset vacuum degree, a hot sealing strip is driven to conduct hot pressing sealing on the bag opening; and S5, after heat sealing is completed, the whole silica gel plate conducts pressure maintaining and cooling on the bag body. The method has the following advantages that warping, dislocation or wrinkling of the bag opening area is avoided, the exhaust smoothness, closing stability and heat sealing strength of the bag opening area are guaranteed, and the vacuum heat insulation packaging performance of the metal-based aluminum foil bag opening is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of vacuum packaging of new materials, specifically to a graded pressure release and vacuuming method and apparatus for aluminum foil-coated nano-insulation boards, which is particularly suitable for vacuum packaging devices and post-processing of new materials in high-end equipment manufacturing. Background Technology

[0002] Nanoporous thermal insulation panels are a new type of high-efficiency thermal insulation material made from fumed silica as the base material and with added functional components such as infrared shielding agents, through a special molding process. They have broad application prospects in emerging industries such as aerospace, industrial energy conservation, building insulation, and high-end equipment manufacturing. However, nanoporous thermal insulation panels have extremely strong hygroscopic properties; when exposed to ambient air, they rapidly absorb moisture, leading to a significant deterioration in their thermal insulation performance and severely impacting their long-term reliability in high-end applications. To solve this technical challenge, industrially, aluminum foil vacuum bags are commonly used for vacuum sealing. By removing the air from the bag and heat-sealing the opening, a stable vacuum isolation layer is formed, thereby ensuring the thermal insulation performance and service life of the nanoporous thermal insulation panel.

[0003] In existing aluminum foil vacuum bag wrapping processes, a silicone plate is typically placed on top of the bag to ensure its flatness during vacuuming, prevent foil wrinkles, and facilitate gas escape. The silicone plate's good elasticity and flexibility allow it to apply uniform pressure to the bag, ensuring a tight seal between the aluminum foil and the nano-insulation board surface, minimizing residual gas space. Simultaneously, the silicone plate acts as a buffer during vacuuming, preventing the nano-insulation board from cracking or the aluminum foil from being damaged due to excessive pressure. Furthermore, during heat sealing, the silicone plate helps to fix the bag body, ensuring proper alignment of the bag opening and improving heat sealing quality.

[0004] However, in practice, it has been found that the above method of directly placing the silicone sheet on top of the aluminum foil vacuum bag for vacuuming has the following technical defects:

[0005] 1. The silicone sheet is a single piece, applying uniform pressure to the bag body. During vacuuming, the bag opening area needs to maintain a certain degree of freedom to close naturally before heat sealing. However, the uniform pressure of the silicone sheet causes the bag opening area to be significantly constrained, making it difficult for the bag opening to achieve an ideal closure in the later stages of vacuuming. In practice, common problems include bag opening warping, misalignment, or wrinkling, which seriously affect the subsequent heat sealing quality, leading to poor heat seal and even air leakage.

[0006] Second, the nanoporous insulation board contains a large number of micro- and nano-scale pores, and gas molecules are physically adsorbed on the inner walls of these pores. Conventional vacuuming methods rely solely on negative pressure to expel free gas, which is insufficient to effectively desorb the gas molecules adsorbed on the inner walls of the pores. These residual gases will be slowly released during the use of the product after packaging, causing the vacuum level inside the bag to gradually decrease over time, thus shortening the product's effective lifespan.

[0007] Third, if the silicone plate still applies pressure to the bag opening area during heat sealing, the bag opening material will be heat sealed under pressure, which may cause stress concentration or uneven melting of the aluminum foil at the heat sealing line, affecting the sealing strength. If the silicone plate is removed in advance, the bag body may shift under vacuum, causing the bag opening to deviate from the heat sealing position, and the bag body cannot be kept under pressure and cooled. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a graded pressure release and vacuuming method and apparatus for aluminum foil-coated nano-insulation panels, effectively solving the above technical problems.

[0009] The objective of this invention is achieved through the following technical solution: a graded pressure release and vacuuming method for aluminum foil-coated nano-insulation panels, the specific steps of which include,

[0010] S1. Place the aluminum foil vacuum bag with built-in nano-insulation board inside the vacuum device, and position the bag opening at the heat sealing position of the vacuum device.

[0011] S2. Cover the aluminum foil vacuum bag with a silicone plate. The silicone plate has a first air chamber, a second air chamber, and a third air chamber that are independently distributed and can be independently inflated along the direction of the bag opening. The third air chamber is located near the bag opening.

[0012] S3. Start the vacuuming device to evacuate the inside of the aluminum foil vacuum bag. During the vacuuming process, compressed air is injected into the first and second air chambers to apply a first clamping force to the aluminum foil vacuum bag. At the same time, compressed air is injected into the third air chamber to apply a second clamping force lower than the first clamping force to the aluminum foil vacuum bag, so that the aluminum foil vacuum bag in the direction of the bag opening is in a low-constraint state. At the same time, during the vacuuming process, a slight vibration is applied to the area where the first and second air chambers are located to promote the desorption of gas inside the aluminum foil vacuum bag and the nano-insulation board.

[0013] S4. When the vacuum reaches the preset vacuum level, the heat sealing strip is driven to heat-seal the bag opening. At the moment the heat sealing strip presses the bag opening, the pressure on the third air chamber is released, reducing the pressure on the bag body to zero, so that the bag opening area is completely freed from the constraint of the silicone plate.

[0014] S5. After heat sealing, compressed air is refilled into the third air chamber to restore its pressure to the same level as the first and second air chambers, so that the silicone plate can maintain pressure and cool the bag body as a whole.

[0015] A further improvement of the present invention is that: in step S3, the second pressing force of the third air chamber is 15%-20% of the first pressing force of the first air chamber; and in step S4, the moment when the heat sealing strip presses the bag opening is delayed by 0.2-0.5 seconds compared to the moment when the pressure of the third air chamber drops to zero, so as to ensure that the bag opening area can withstand the heat sealing pressure in a completely free state.

[0016] A further improvement of the present invention is that, in step S3, during the vacuuming process, a micro-vibration frequency of 30-80Hz and an amplitude of 0.05-0.15mm is applied to the area where the first and second air chambers of the silicone plate are located.

[0017] A graded pressure relief vacuum pumping device for aluminum foil-coated nano-insulation panels, comprising:

[0018] The vacuum chamber has a heat-sealing station inside, and the opening of the aluminum foil vacuum bag with built-in nano-insulation board is placed in the heat-sealing station. The vacuum chamber has a vacuum generator on the outside to evacuate the inside of the vacuum chamber.

[0019] The heat sealing assembly includes a heat sealing strip set on the heat sealing station and a heat sealing block placed inside the vacuum chamber. The heat sealing block is placed directly above the heat sealing strip and is lifted up and down by a drive cylinder.

[0020] The micro-vibration pressure plate assembly includes a rigid pressure plate connected to the drive end of the drive cylinder and a silicone plate placed on the lower end face of the rigid pressure plate. The silicone plate has a first air chamber, a second air chamber and a third air chamber independently distributed in sequence along the bag opening direction on the lower side of the interior of the silicone plate. The third air chamber is located close to the bag opening. The air chambers are physically isolated from each other by an elastic sealing partition. The upper end of the rigid pressure plate has a micro-vibration generator.

[0021] The pressure detection unit is a pressure sensor installed on a rigid pressure plate. The pressure sensor detects the clamping force between the micro-vibration pressure plate assembly and the aluminum foil vacuum bag in real time.

[0022] The partition pressure control unit is connected to the first, second, and third air chambers of the silicone plate, and independently controls the pressure of the compressed gas injected into each air chamber to adjust the pressure applied to the aluminum foil vacuum bag by each air chamber.

[0023] The control unit is electrically connected to the vacuum generator, heat sealing assembly, micro-vibration pressure plate assembly, pressure detection unit, and zoned pressure control unit.

[0024] A further improvement of the present invention is that the control unit executes the following control timing sequence.

[0025] (1) Rigid pressure plate pressing stage: The controller controls the second drive cylinder to drive the rigid pressure plate to descend. When the pressing force detected by the first pressure sensor reaches the preset contact pressure threshold, the pressing action of the second drive cylinder is stopped, so that the silicone plate and the surface of the aluminum foil vacuum bag remain in contact.

[0026] (2) Vacuuming stage: control the pressure of the first air chamber and the second air chamber to the first clamping force P1, control the pressure of the third air chamber to the second clamping force P2, where P2=0.15P1~0.2P1, and start the micro-amplitude vibration generator to apply micro-amplitude vibration to the first air chamber and the second air chamber during the vacuuming process;

[0027] (3) Heat sealing moment: Control the drive cylinder to descend, so that the heat sealing block presses the opening of the aluminum foil vacuum bag. At the moment of pressing, control the third air chamber to depressurize to zero, and the first air chamber and the second air chamber maintain pressure P1.

[0028] (4) Pressure holding and cooling stage: After heat sealing is completed, control the pressure of the third air chamber to return to P1, so that the silicone plate can hold pressure and cool the aluminum foil vacuum bag as a whole.

[0029] A further improvement of the present invention is that: the driving end of the second driving cylinder is connected to the rigid pressure plate by a flexible joint, and the rigid pressure plate is connected to the inner wall of the vacuum cavity by a guide post, the extension direction of the guide post being consistent with the extension and retraction direction of the second driving cylinder.

[0030] A further improvement of the present invention is that the partition pressure control unit includes an air source and air pressure regulating branches that are respectively connected to the first air chamber, the second air chamber, and the third air chamber of the silicone plate. Each air pressure regulating branch is connected in series with an electrical proportional valve between the air source and the corresponding air chamber and a pressure sensor 2 for detecting the pressure of the corresponding air chamber.

[0031] The control unit receives the actual pressure signals detected by each pressure sensor, compares each actual pressure value with the preset target pressure value, and controls the opening degree of each electro-proportional valve to achieve independent closed-loop regulation of the pressure of each air chamber.

[0032] A further improvement of the present invention is that the micro-amplitude vibration generator is an electromagnetic exciter. When the micro-amplitude vibration generator is started in the initial stage of vacuuming, a first frequency f1=50-80Hz is applied; in the middle stage of vacuuming, the frequency is automatically switched to a second frequency f2=30-50Hz according to the vacuum degree detection value; and in the later stage of vacuuming, when the vacuum degree reaches the preset value, the micro-amplitude vibration generator is turned off.

[0033] A further improvement of the present invention is that: the lower surface of the silicone plate is provided with a plurality of exhaust grooves, which are located close to the third air chamber.

[0034] A further improvement of the present invention is that a high-temperature resistant elastic pad is provided on the outer end face of the heat-sealing block, the thickness of the high-temperature resistant elastic pad is 1-3mm, and the hardness is Shore A 30-50 degrees.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1. This invention independently sets up a first air chamber, a second air chamber, and a third air chamber sequentially along the bag opening direction inside the silicone plate. During the vacuuming process, the pressure of each air chamber is independently adjusted by zoned pressure control, so that the first clamping force in the first and second air chambers is greater than the second clamping force in the third air chamber. This rapidly compresses the pore volume of the nano-insulation plate at the location of the first and second air chambers, while keeping the area of ​​the aluminum foil vacuum bag near the third air chamber in a low-constraint state. The establishment of this pressure gradient allows the gas molecules with higher pressure to flow naturally to the bag opening area with lower pressure, quickly guiding the gas flow. This maintains the initial positioning of the bag opening and provides the necessary degree of freedom for its natural closure in the later stage of vacuuming, effectively avoiding problems such as bag opening warping, misalignment, or wrinkling caused by excessive pressure in the bag opening area due to traditional whole silicone plates. The moment the heat-sealing strip presses the bag opening together, the third air chamber is rapidly depressurized to zero, and the bag opening area is completely freed from the constraint of the silicone plate. The bag opening material bears the heat-sealing pressure in a completely free state, which solves the defects of stress concentration and uneven melting caused by the pressure constraint on the bag opening area during heat sealing in the existing technology. It significantly improves the uniformity and sealing strength of the heat-sealing line, ensuring the long-term reliability of vacuum sealing.

[0037] 2. This invention applies micro-vibration to the areas containing the first and second gas chambers during the vacuuming process. This micro-vibration is transmitted to the silicone plate via a rigid pressure plate, and then acts on the aluminum foil vacuum bag and the internal nano-insulation plate. This causes minute, periodic deformation of the pore structure within the nano-insulation plate, disrupting the adsorption balance between gas molecules and the pore walls, effectively promoting the desorption and release of adsorbed gas. The third gas chamber, acting as a low-pressure, low-disturbance buffer zone, is designed to stably exhaust gas. Applying vibration to the third gas chamber could cause turbulent airflow at the bag opening, potentially even introducing residual gas into the bag opening area, reducing exhaust efficiency, and interfering with the natural closing process of the bag opening, thus affecting the subsequent heat-sealing quality. Therefore, this invention limits the vibration area to the main bag body area containing the first and second gas chambers. This fully utilizes the technical effect of vibration promoting gas desorption while ensuring smooth exhaust and closure stability at the bag opening, achieving synergistic optimization of staged pressure release and efficient desorption. Attached Figure Description

[0038] Figure 1This is a schematic diagram of the staged pressure relief and vacuum pumping device in this invention.

[0039] Figure 2 for Figure 1 A schematic diagram showing the positions of each atmospheric cavity on the silicone plate.

[0040] Figure 3 This diagram illustrates the gas flow within the aluminum foil vacuum plate compared to the conventional method and the method of this invention.

[0041] Figure 4 This is a SEM comparison diagram of the heat-sealed area of ​​the aluminum foil vacuum bag used to coat the nanoplate using the traditional method and the method of this invention.

[0042] Numbering on the map:

[0043] 1-Vacuum chamber, 2-Heat sealing station, 3-Vacuum generator, 4-Heat sealing strip, 5-Heat sealing block, 6-Drive cylinder one, 7-Micro-vibration pressure plate group, 8-Pressure sensor one, 9-Aluminum foil vacuum bag, 10-Bag opening, 11-Nano insulation board;

[0044] 71-Rigid pressure plate, 72-Silicone plate, 73-First air chamber, 74-Second air chamber, 75-Third air chamber, 76-Micro-vibration generator, 77-Drive cylinder two, 78-Flexible joint, 79-Guide column, 710-Exhaust groove. Detailed Implementation

[0045] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments and accompanying drawings. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0046] In the description of this invention, it should be understood that the terms indicating orientation or positional relationship, such as those based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the structure or unit referred to must have a specific orientation, and therefore should not be construed as a limitation of this invention.

[0047] In this invention, unless otherwise explicitly specified and limited, terms such as “connection,” “provided with,” and “have” should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can be described as a mechanical connection, a direct connection, or a connection through an intermediate medium. Those skilled in the art can understand the basic meaning of the above terms in this invention according to the specific circumstances.

[0048] A graded pressure relief vacuum method for aluminum foil-coated nano-insulation panels, comprising the following specific steps:

[0049] S1. Place the aluminum foil vacuum bag 9 with built-in nano heat insulation board inside the vacuum device, so that the bag opening 10 is positioned at the heat sealing station 2 of the vacuum device.

[0050] S2. Cover the aluminum foil vacuum bag 9 with the silicone plate 72. The silicone plate 72 is provided with a first air chamber 73, a second air chamber 74 and a third air chamber 75 that are independently distributed and can be independently inflated along the direction of the bag opening 10. The third air chamber 75 is located near the bag opening 10.

[0051] S3. Start the vacuuming device to evacuate the inside of the aluminum foil vacuum bag. During the vacuuming process, compressed air is injected into the first air chamber 73 and the second air chamber 74 to apply a first clamping force to the aluminum foil vacuum bag 9. At the same time, compressed air is injected into the third air chamber 75 to apply a second clamping force lower than the first clamping force to the aluminum foil vacuum bag 9, so that the aluminum foil vacuum bag 9 in the direction of the bag opening 10 is in a low-constraint state. At the same time, during the vacuuming process, a slight vibration is applied to the area where the first air chamber 73 and the second air chamber 74 are located to promote the desorption of gas inside the aluminum foil vacuum bag 9 and the nano-insulation plate 11.

[0052] S4. When the vacuum reaches the preset vacuum level, drive the heat sealing strip 4 to heat-seal the bag opening 10. At the instant the heat sealing strip 4 presses the bag opening 10, depressurize the third air chamber 75 to reduce the pressure on the bag body to zero, so that the bag opening 10 area is completely freed from the constraint of the silicone plate 72.

[0053] S5. After heat sealing, compressed air is refilled into the third air chamber 75 to restore its pressure to the same level as the first air chamber 73 and the second air chamber 74, so that the silicone plate 72 can maintain pressure and cool the bag body as a whole.

[0054] This invention features a first air chamber 73, a second air chamber 74, and a third air chamber 75 independently arranged sequentially along the bag opening direction inside the silicone plate. During the vacuuming process, the pressure of each air chamber is independently adjusted through zoned pressure control, ensuring that the first clamping force in the first air chamber 73 and the second air chamber 74 is greater than the second clamping force in the third air chamber 75. This rapidly compresses the pore volume of the nano-insulation plate 11 at the locations of the first air chamber 73 and the second air chamber 74, while simultaneously keeping the area of ​​the aluminum foil vacuum bag 9 near the third air chamber 75 in a low-constraint state. This pressure gradient allows the higher-pressure gas molecules to naturally flow towards the lower-pressure bag opening area, quickly guiding the gas flow. This maintains the initial positioning of the bag opening 10 and provides the necessary freedom for its natural closure in the later stages of vacuuming, effectively avoiding problems such as bag opening warping, misalignment, or wrinkling caused by excessive pressure in the bag opening 10 area due to the traditional solid silicone plate 72. The moment the heat-sealing strip 4 presses against the bag opening 10, the third air chamber 75 is rapidly depressurized to zero, and the area of ​​the bag opening 10 is completely freed from the constraint of the silicone plate 72. The bag opening material bears the heat-sealing pressure in a completely free state, which solves the defects of stress concentration and uneven melting caused by the pressure constraint on the bag opening area during heat sealing in the prior art. It significantly improves the uniformity and sealing strength of the heat-sealing line, and ensures the long-term reliability of vacuum sealing.

[0055] The reason for depressurizing the third air chamber 75 at the moment when the heat seal strip 4 presses the bag opening 10 is that during the vacuuming stage, the silicone plate 72 not only presses the body of the aluminum foil vacuum bag 9, but also generates a horizontal tensile or taut force on the bag opening 10 area. If the pressure is not released at this time, the aluminum foil vacuum bag 9 at the sealing point will still bear the pressure and some tensile stress from the silicone plate 72 when the heat seal strip 4 is pressed, even in a state of high temperature softening. This can easily lead to internal stress concentration, resulting in a decrease in sealing strength. After depressurization, the heat seal strip can fuse the two layers of film of the aluminum foil vacuum bag by relying solely on its own heat and pressure without external mechanical tension interference. This results in a more uniform, dense, and high-strength seal.

[0056] Based on this embodiment, in step S3, the second pressing force of the third air chamber 75 is 15%-20% of the first pressing force of the first air chamber 73. In step S4, the moment when the heat sealing strip 4 presses the bag opening 10 is delayed by 0.2-0.5 seconds compared to the moment when the pressure of the third air chamber 75 drops to zero, ensuring that the area of ​​the bag opening 10 can withstand the heat sealing pressure in a completely free state.

[0057] In the vacuum heat sealing process, the nano-insulation board inside the aluminum foil vacuum bag 9 is a porous medium material. The gas not only exists in the gaps between the nano-insulation board particles, but is also adsorbed on the inner surface of the nanopores. The differentiated compression force design can form a directional exhaust channel inside the aluminum foil vacuum bag. If the bag opening is too tight, the residual gas cannot be discharged quickly. At the same time, the relative high pressure formed by the first gas chamber and the second gas chamber on the aluminum foil vacuum bag 9 further compresses the pore volume and discharges the free gas in the large pores.

[0058] Based on this embodiment, in step S3, during the vacuuming process, a micro-vibration frequency of 30-80Hz and an amplitude of 0.05-0.15mm is applied to the area where the first air chamber 73 and the second air chamber 74 of the silicone plate 72 are located.

[0059] This invention applies micro-vibration to the areas containing the first and second air chambers 73 and 74 during the vacuuming process. This micro-vibration is transmitted to the silicone plate 72 via the rigid pressure plate 71, and then acts on the aluminum foil vacuum bag 9 and the internal nano-insulation plate 11. This causes minute, periodic deformation of the pore structure inside the nano-insulation plate 11, disrupting the adsorption balance between gas molecules and the pore walls, effectively promoting the desorption and release of adsorbed gas. The third air chamber 75 serves as a low-pressure, low-disturbance buffer zone, its function being to stably exhaust gas. Applying vibration to the third air chamber 75 could cause turbulent airflow at the bag opening, or even stir in residual gas from outside into the bag opening 10 area, reducing exhaust efficiency and interfering with the natural closing process of the bag opening 10, affecting the subsequent heat-sealing quality. Therefore, this invention limits the vibration area to the main bag body area containing the first and second air chambers, fully utilizing the technical effect of vibration promoting gas desorption while ensuring smooth exhaust and closing stability at the bag opening area, achieving synergistic optimization of staged pressure release and efficient desorption.

[0060] A graded pressure relief vacuum device for aluminum foil-coated nano-insulation panels, referring to Figure 1 , Figure 2 ,include

[0061] Vacuum chamber 1, with heat sealing station 2 inside the vacuum chamber 1, the bag opening 10 of aluminum foil vacuum bag 9 with built-in nano heat insulation board 11 is placed on heat sealing station 2, and vacuum generator 3 is located outside the vacuum chamber 1 to evacuate the inside of the vacuum chamber 1.

[0062] The heat sealing assembly 4 includes a heat sealing strip 4 set on the heat sealing station 2 and a heat sealing block 5 placed inside the vacuum chamber 1. The heat sealing block 5 is placed directly above the heat sealing strip 4 and is lifted up and down by a drive cylinder 6.

[0063] The micro-vibration pressure plate assembly 7 includes a rigid pressure plate 71 connected to the driving end of the driving cylinder 77 and a silicone plate 72 placed on the lower end face of the rigid pressure plate 71. The silicone plate 72 has a first air chamber 73, a second air chamber 74 and a third air chamber 75 independently distributed in sequence along the direction of the bag opening 10 on the lower side of the inner side of the silicone plate 72. The third air chamber 75 is located close to the bag opening 10. The air chambers are physically isolated from each other by an elastic sealing partition. The upper end of the rigid pressure plate 71 has a micro-vibration generator 76.

[0064] The pressure detection unit is a pressure sensor 8 installed on the rigid pressure plate 71. The pressure sensor 8 detects the clamping force between the micro-vibration pressure plate group 7 and the aluminum foil vacuum bag 9 in real time.

[0065] The partition pressure control unit is connected to the first air chamber 73, the second air chamber 74 and the third air chamber 75 of the silicone plate, and independently controls the pressure of the compressed gas injected into each air chamber to adjust the pressure applied by each air chamber to the aluminum foil vacuum bag 9.

[0066] The control unit is electrically connected to the vacuum generator 3, the heat sealing group 4, the micro-vibration pressure plate group 7, the pressure detection unit, and the zone pressure control unit.

[0067] Based on this embodiment, the control unit executes the following control timing sequence.

[0068] (1) Rigid pressure plate pressing stage: The controller controls the second drive cylinder to drive the rigid pressure plate 71 to descend. When the pressing force detected by the pressure sensor 8 reaches the preset contact pressure threshold, the pressing action of the second drive cylinder 77 is stopped, so that the silicone plate 72 and the surface of the aluminum foil vacuum bag 9 remain in contact.

[0069] (2) Vacuuming stage: control the pressure of the first air chamber 73 and the second air chamber 74 to the first clamping force P1, control the pressure of the third air chamber 75 to the second clamping force P2, where P2 = 0.15P1 ~ 0.2P1, and start the micro-amplitude vibration generator 76 to apply micro-amplitude vibration to the first air chamber 73 and the second air chamber 74 during the vacuuming process;

[0070] (3) Heat sealing moment: Control the drive cylinder 6 to descend, so that the heat sealing block 5 presses the bag mouth of the aluminum foil vacuum bag 9. At the moment of pressing, control the third air chamber 75 to depressurize to zero, and the first air chamber 73 and the second air chamber 74 maintain pressure P1.

[0071] (4) Pressure holding and cooling stage: After heat sealing is completed, control the pressure of the third air chamber 75 to return to P1, so that the silicone plate 72 can hold pressure and cool the aluminum foil vacuum bag 9 as a whole.

[0072] Figure 3 The gas flow paths during the vacuuming process were compared between the traditional method and the method of this invention.

[0073] In the traditional method, the upper end of the aluminum foil vacuum bag 9 is a silicone plate, which applies uniform pressure to the bag body. This pressure equalization method makes the stress state of the bag body and the bag opening area the same, and the flow resistance of gas in all directions inside the bag is not much different. Since the bag opening area is also subject to greater constraints, the gas is difficult to form a directional flow and is prone to stagnation or turbulence inside the bag, resulting in low exhaust efficiency. At the same time, the bag opening is difficult to close naturally in the later stage of vacuuming under high pressure constraints, and is prone to warping or misalignment.

[0074] In the method of this invention, the silicone plate 72 has independent first air chambers 73, second air chambers 74, and third air chambers 75, forming a pressure gradient along the bag opening 10. The first and second air chambers apply higher pressure (first clamping force) to the bag body, rapidly compressing the pore volume of the nano-insulation plate 11; the third air chamber 75 is close to the bag opening 10, applying lower pressure (second clamping force), keeping the bag opening area in a low-constraint state. This pressure gradient allows the gas inside the bag to flow naturally from the high-pressure area (bag body) to the low-pressure area (bag opening), forming a smooth exhaust path as shown in the figure. Simultaneously, vibration is only applied to the first and second air chamber areas, promoting gas desorption, while the bag opening area is unaffected by vibration, further ensuring the stability of the exhaust and the natural closure of the bag opening.

[0075] Based on this embodiment, the driving end of the second driving cylinder 77 is connected to the rigid pressure plate 71 by a flexible joint 78, and the rigid pressure plate 71 is connected to the inner wall of the vacuum chamber 1 by a guide post 79. The extension direction of the guide post 79 is consistent with the extension and retraction direction of the second driving cylinder 77.

[0076] When the micro-amplitude vibration generator 76 is working, it will generate high-frequency, low-amplitude vibrations. The flexible joint 78 prevents reverse impact from damaging the precision components inside the drive cylinder 77. On the other hand, under the precise constraint of the guide column 79, the rigid pressure plate 71 is restricted to a single axial degree of freedom. This allows the vibration energy to be converted into micro-amplitude oscillations along the guide direction, avoiding energy loss caused by lateral shaking. This ensures the precise alignment of the rigid pressure plate 71 and achieves efficient energy transfer, thereby providing stable and precise micro-amplitude vibration assistance for the nano-insulation plate 11 in the vacuum chamber 1.

[0077] Based on this embodiment, the partition pressure control unit includes an air source and air pressure regulating branches that are respectively connected to the first air chamber 73, the second air chamber 74, and the third air chamber 75 of the silicone plate 72. Each air pressure regulating branch is connected in series with an electrical proportional valve between the air source and the corresponding air chamber and a pressure sensor 2 that detects the pressure of the corresponding air chamber.

[0078] The control unit receives the actual pressure signals detected by each pressure sensor, compares each actual pressure value with the preset target pressure value, and controls the opening degree of each electro-proportional valve to achieve independent closed-loop regulation of the pressure of each air chamber.

[0079] Based on this embodiment, the micro-amplitude vibration generator is an electromagnetic exciter. When the micro-amplitude vibration generator is started at the initial stage of vacuuming, a first frequency f1=50-80Hz is applied; during the middle stage of vacuuming, it automatically switches to a second frequency f2=30-50Hz according to the vacuum degree detection value; and in the later stage of vacuuming, when the vacuum degree reaches the preset value, the micro-amplitude vibration generator is turned off.

[0080] Based on this embodiment, the lower surface of the silicone plate 72 is provided with a plurality of exhaust grooves 710, and the exhaust grooves 710 are located near the third air chamber 75.

[0081] When the third air chamber 75 is evacuated, the exhaust groove 710 can provide a fast escape channel for the gas between the contact surface of the aluminum foil vacuum bag 9 and the silicone plate 72. Without these micro-grooves, the soft and dense silicone 72 is prone to forming a local sealed space when pressing the workpiece, and the residual gas cannot be discharged in time, which will lead to delayed adsorption or weak adsorption. The presence of the exhaust groove 710 shortens the gas flow path, allowing it to be sucked into the third air chamber 75 more smoothly, thereby achieving a fast and uniform vacuum channel.

[0082] Based on this embodiment, the outer end face of the heat-sealing block 5 is provided with a high-temperature resistant elastic pad, the thickness of which is 1-3mm and the hardness is Shore A 30-50 degrees.

[0083] Figure 4 The microstructure of the heat-sealed area of ​​the aluminum foil vacuum bag was compared between the traditional method and the method of the present invention.

[0084] In the traditional heat sealing method, the bag opening area is constantly constrained by the pressure of the silicone plate 72 during the vacuuming and heat sealing process. This causes the aluminum foil vacuum bag 9 to still bear external mechanical tension in the high-temperature molten state, forming an obvious stress concentration area. At the same time, the heat sealing under pressure causes uneven heating of the upper and lower aluminum foil layers, insufficient flow of molten material, and defects of uneven melting. These microstructural discontinuities directly lead to a decrease in the sealing strength of the heat seal line, which is prone to delamination or micro-leakage during subsequent use, affecting the long-term reliability of vacuum sealing.

[0085] At the heat-sealing point of the method of the present invention, the third air chamber 75 is depressurized at the instant the heat-sealing strip 4 presses against the bag opening 10, allowing the bag opening 10 area to completely escape the constraint of the silicone plate 72. The aluminum foil vacuum bag bears the heat-sealing pressure in a completely free state. This heat-sealing condition without external mechanical tension interference allows the upper and lower aluminum foil layers to fully fuse under the action of heat and pressure, and the molten material flows uniformly, forming a uniform and dense fused layer as shown in the figure. This dense microstructure ensures that the heat-sealing line has excellent sealing strength and long-term stability, effectively solving the problem of vacuum degree decay caused by heat-sealing defects in traditional methods.

[0086] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A graded pressure relief vacuum method for aluminum foil-coated nano-insulation panels, characterized in that: The specific steps include, S1. Place the aluminum foil vacuum bag with built-in nano-insulation board inside the vacuum device, and position the bag opening at the heat sealing position of the vacuum device. S2. Cover the aluminum foil vacuum bag with a silicone plate. The silicone plate has a first air chamber, a second air chamber, and a third air chamber that are independently distributed and can be independently inflated along the direction of the bag opening. The third air chamber is located near the bag opening. S3. Start the vacuuming device to evacuate the inside of the aluminum foil vacuum bag. During the vacuuming process, compressed air is injected into the first and second air chambers to apply a first clamping force to the aluminum foil vacuum bag. At the same time, compressed air is injected into the third air chamber to apply a second clamping force lower than the first clamping force to the aluminum foil vacuum bag, so that the aluminum foil vacuum bag in the direction of the bag opening is in a low-constraint state. At the same time, during the vacuuming process, a slight vibration is applied to the area where the first and second air chambers are located to promote the desorption of gas inside the aluminum foil vacuum bag and the nano-insulation board. S4. When the vacuum reaches the preset vacuum level, the heat sealing strip is driven to heat-seal the bag opening. At the moment the heat sealing strip presses the bag opening, the pressure on the third air chamber is released, reducing the pressure on the bag body to zero, so that the bag opening area is completely freed from the constraint of the silicone plate. S5. After heat sealing, compressed air is refilled into the third air chamber to restore its pressure to the same level as the first and second air chambers, so that the silicone plate can maintain pressure and cool the bag body as a whole.

2. The graded pressure relief and vacuuming method for aluminum foil-coated nano-insulation panels according to claim 1, characterized in that: In step S3, the second pressing force of the third air chamber is 15%-20% of the first pressing force of the first air chamber. In step S4, the moment when the heat sealing strip presses the bag opening is delayed by 0.2-0.5 seconds compared to the moment when the pressure of the third air chamber drops to zero, ensuring that the bag opening area can withstand the heat sealing pressure in a completely free state.

3. The graded pressure relief and vacuuming method for aluminum foil-coated nano-insulation panels according to claim 2, characterized in that: In step S3, during the vacuuming process, a micro-vibration with a frequency of 30-80Hz and an amplitude of 0.05-0.15mm is applied to the area where the first and second air chambers of the silicone plate are located.

4. A graded pressure relief vacuum device for implementing the aluminum foil-coated nano-insulation board according to any one of claims 1-3, characterized in that: include A vacuum chamber, wherein the vacuum chamber has a heat sealing station, the opening of an aluminum foil vacuum bag with a built-in nano-insulation board is placed on the heat sealing station, and the vacuum chamber has a vacuum generator on the outside to evacuate the inside of the vacuum chamber. The heat sealing assembly includes a heat sealing strip set on the heat sealing station and a heat sealing block placed inside the vacuum chamber. The heat sealing block is placed directly above the heat sealing strip and is lifted up and down by a drive cylinder. The micro-vibration pressure plate assembly includes a rigid pressure plate connected to the driving end of the driving cylinder and a silicone plate placed on the lower end face of the rigid pressure plate. The silicone plate has a first air chamber, a second air chamber and a third air chamber independently distributed sequentially along the bag opening direction on its lower inner side. The third air chamber is located close to the bag opening. The air chambers are physically isolated from each other by an elastic sealing partition. The upper end of the rigid pressure plate has a micro-vibration generator. The pressure detection unit is a pressure sensor installed on a rigid pressure plate. The pressure sensor detects the clamping force between the micro-vibration pressure plate assembly and the aluminum foil vacuum bag in real time. A partitioned pressure control unit is connected to the first, second, and third air chambers of the silicone plate, and independently controls the pressure of the compressed gas injected into each air chamber to adjust the pressure applied by each air chamber to the aluminum foil vacuum bag. The control unit is electrically connected to the vacuum generator, heat sealing assembly, micro-vibration pressure plate assembly, pressure detection unit, and zoned pressure control unit.

5. The graded pressure relief vacuum device for aluminum foil-coated nano-insulation panels according to claim 4, characterized in that: The control unit executes the following control timing sequence (1) Rigid pressure plate pressing stage: The controller controls the second drive cylinder to drive the rigid pressure plate to descend. When the pressing force detected by the first pressure sensor reaches the preset contact pressure threshold, the pressing action of the second drive cylinder is stopped, so that the silicone plate and the surface of the aluminum foil vacuum bag remain in contact. (2) Vacuuming stage: control the pressure of the first air chamber and the second air chamber to the first clamping force P1, control the pressure of the third air chamber to the second clamping force P2, where P2=0.15P1~0.2P1, and start the micro-amplitude vibration generator to apply micro-amplitude vibration to the first air chamber and the second air chamber during the vacuuming process; (3) Heat sealing moment: Control the drive cylinder to descend, so that the heat sealing block presses the opening of the aluminum foil vacuum bag. At the moment of pressing, control the third air chamber to depressurize to zero, and the first air chamber and the second air chamber maintain pressure P1. (4) Pressure holding and cooling stage: After heat sealing is completed, control the pressure of the third air chamber to return to P1, so that the silicone plate can hold pressure and cool the aluminum foil vacuum bag as a whole.

6. The graded pressure relief vacuum device for aluminum foil-coated nano-insulation panels according to claim 5, characterized in that: The driving end of the second driving cylinder is connected to the rigid pressure plate via a flexible joint. The rigid pressure plate is connected to the inner wall of the vacuum chamber via a guide post. The extension direction of the guide post is consistent with the extension and retraction direction of the second driving cylinder.

7. The graded pressure relief vacuum device for aluminum foil-coated nano-insulation panels according to claim 6, characterized in that: The partition pressure control unit includes an air source and air pressure regulating branches that are respectively connected to the first air chamber, the second air chamber, and the third air chamber of the silicone plate. Each air pressure regulating branch is connected in series with an electrical proportional valve between the air source and the corresponding air chamber and a pressure sensor 2 that detects the pressure of the corresponding air chamber. The control unit receives the actual pressure signals detected by each pressure sensor, compares each actual pressure value with the preset target pressure value, and controls the opening degree of each electro-proportional valve to achieve independent closed-loop regulation of the pressure of each air chamber.

8. The graded pressure relief vacuum device for aluminum foil-coated nano-insulation panels according to claim 7, characterized in that: The micro-amplitude vibration generator is an electromagnetic vibrator. When the micro-amplitude vibration generator is started at the initial stage of vacuuming, a first frequency f1=50-80Hz is applied; during the middle stage of vacuuming, it automatically switches to a second frequency f2=30-50Hz based on the vacuum level detection value; and in the later stage of vacuuming, when the vacuum level reaches the preset value, the micro-amplitude vibration generator is turned off.

9. The graded pressure relief vacuum device for aluminum foil-coated nano-insulation panels according to claim 8, characterized in that: The lower surface of the silicone plate is provided with multiple exhaust grooves, which are located near the third air chamber.

10. The graded pressure relief vacuum device for aluminum foil-coated nano-insulation panels according to claim 9, characterized in that: The outer end face of the heat-sealed block is provided with a high-temperature resistant elastic pad, the thickness of which is 1-3mm and the hardness is Shore A 30-50 degrees.

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