A deformation suppression device for thin-walled structure gas leakage test

Abstract

This invention provides a deformation suppression device for gas leak testing of thin-walled structures, comprising: an airbag-type fixture including a support frame and an airbag mounted on one side of the support frame, wherein the airbag and the support frame together define an airbag cavity, or the airbag alone defines an airbag cavity, and the airbag cavity is provided with an inflation / exhaust port; the inflation / exhaust port is used to connect to a test gas source, and when the inflation / exhaust port is inflated, the airbag undergoes elastic deformation under the action of air pressure, closely adhering to the outer surface of the thin wall of the workpiece under test and forming a covering layer to isolate the direct flow contact between ambient air and the outer surface of the thin wall. By controlling the air pressure in the airbag cavity to be consistent with the air pressure on the inner surface of the thin wall, deformation of the thin wall is suppressed. This invention effectively suppresses deformation of the thin wall during testing, avoids temperature fluctuations in the thin wall caused by the flow of ambient air, and improves the accuracy and repeatability of leak testing.

Description

Technical Field

[0001] This invention belongs to the field of sealing test technology and relates to a deformation suppression device for gas leakage testing of thin-walled structures. Background Technology

[0002] Leakage testing of power battery packs is a critical process in battery manufacturing, and the accuracy of the test results directly affects the safety, reliability, and lifespan of the battery. During testing, the battery pack is typically filled with gas at a certain pressure, and a leakage testing system is used to check whether the leakage rate meets design requirements. The top cover of a power battery pack is generally a large-area, thin-walled sheet metal part. When pressurized internally, this thin-walled cover is highly susceptible to elastic deformation or even permanent deformation. Elastic deformation during testing causes changes in internal volume, affecting pressure stability and leakage rate calculations, leading to inaccurate test results and serious quality risks. Permanent deformation alters the product's design dimensions and condition, impacting yield.

[0003] To control the deformation of thin-walled covers during leak tests, current production lines generally employ fixed frame structures. These frames only physically restrict the cover in localized areas, and the overall deformation suppression of the thin-walled cover needs improvement. Furthermore, in existing solutions, the thin-walled cover is directly exposed to ambient air. The flow of ambient air causes fluctuations in the temperature of the cover's outer surface, and these temperature changes alter gas density and pressure, thus requiring improvements in the accuracy and repeatability of leak tests. Summary of the Invention

[0004] This application provides a deformation suppression device for gas leakage testing of thin-walled structures to solve the problems existing in the prior art, effectively suppress the deformation of the thin wall during testing, avoid temperature fluctuations of the thin wall caused by the flow of ambient air, and improve the accuracy and repeatability of leakage testing.

[0005] The deformation suppression device for gas leakage testing of thin-walled structures provided in this application includes: an airbag-type fixture, including a support frame and an airbag installed on one side of the support frame. The airbag and the support frame together define an airbag cavity, or the airbag defines an airbag cavity independently. The airbag cavity is provided with an inflation / exhaust port. The inflation / exhaust port is used to connect to a test gas source. When the inflation / exhaust port is inflated, the airbag undergoes elastic deformation under air pressure, closely adhering to the outer surface of the thin wall of the workpiece under test and forming a covering layer to isolate the direct flow contact between ambient air and the outer surface of the thin wall. By controlling the air pressure in the airbag cavity to be consistent with the air pressure on the inner surface of the thin wall, deformation of the thin wall is suppressed.

[0006] Optionally, it also includes a support frame and a tooling moving mechanism mounted on the support frame; the support frame is fixedly installed, and the tooling moving mechanism is connected to the support frame to drive the airbag-type tooling to move between at least two positions, including an initial position for loading and unloading the workpiece under test, and a working position where the airbag contacts the thin wall of the workpiece under test during the leakage test; when the airbag-type tooling is in the initial position, the workpiece under test is moved to the test position by a moving trolley or a robot.

[0007] Optionally, the support frame includes a frame body and a rigid plate mounted on one side of the frame body, the airbag is located on one side of the rigid plate, and after inflation, it is fitted between the outer surface of the rigid plate and the thin wall.

[0008] Optionally, the airbag is mounted on the support frame via a quick-release mechanism, the quick-release mechanism including a pressure strip for securing the airbag after it is mounted on the support frame.

[0009] Optionally, the quick-release mechanism includes a ferromagnetic layer on the rigid plate, and the pressure strip can be adsorbed onto the ferromagnetic layer; or, the pressure strip is installed on the rigid plate by means of bolt connection or snap-fit.

[0010] Optionally, the inflation / exhaust port is connected to a first gas circuit, which includes a main circuit and an inflation circuit and an exhaust circuit connected in parallel. The main circuit is connected in series with the inflation circuit and the exhaust circuit connected in parallel. An inflation control valve is provided on the main circuit, a one-way valve is provided on the inflation circuit, and an adjustable pressure relief valve is provided on the exhaust circuit.

[0011] Optionally, the workpiece under test is connected to a second gas circuit, which is connected in parallel with the first gas circuit and both are connected to a leak testing system, the leak testing system including the test gas source.

[0012] Optionally, the support frame is provided with a vacuum adsorption auxiliary positioning mechanism, including: at least two vacuum suction cups arranged circumferentially along the support frame; a vacuum distribution pipeline connecting at least two of the vacuum suction cups to an external vacuum source; when the airbag-type fixture is in the working position, the adsorption surface of the vacuum suction cups adsorbs onto the non-thin-walled area of ​​the workpiece being measured or an external fixed base, for pre-fixing the airbag-type fixture in the target position before the airbag is inflated.

[0013] Optionally, an inflatable auxiliary airbag layer is provided between the support frame and the airbag. The auxiliary airbag layer is independent of the airbag cavity and has a separate auxiliary inflation and deflation port. After the airbag is inflated and adheres to the outer surface of the thin wall, the overall uniformity of the fit between the airbag and the thin wall is increased by controlling the inflation pressure of the auxiliary airbag layer to be greater than the pressure of the airbag cavity.

[0014] Optionally, the airbag is provided with a flow guiding structure on the side facing the outer surface of the thin wall, the flow guiding structure including multiple intersecting or parallel grooves; when the airbag gradually adheres to the outer surface of the thin wall, the air located between the airbag and the outer surface of the thin wall is discharged through the grooves; or, the inner wall or outer wall of the airbag is provided with a flexible electric heating film.

[0015] The above technical solution has the following beneficial effects: The deformation suppression device for gas leakage testing of thin-walled structures provided in this application has an air bladder cavity connected to a test gas source through an inflation and deflation port. The inflated air bladder covers an area greater than or equal to the outer surface area of ​​the thin wall and fits tightly against the entire outer surface of the thin wall, providing uniform support and preventing local buckling. The air pressure in the air bladder cavity is controlled to be the same as the air pressure on the inner surface of the thin wall, thus ensuring that the inner and outer surfaces of the thin-walled structure bear the same pressure. The net pressure of the thin wall is zero, preventing elastic or permanent deformation even if the thin wall itself has low stiffness. Furthermore, the air bladder acts as a covering layer, isolating the outer surface of the thin wall from the ambient airflow. The ambient airflow cannot directly scour the outer surface of the thin wall, thereby avoiding temperature fluctuations caused by convective heat transfer. This ensures that the internal gas density and pressure of the tested workpiece remain constant, improving the repeatability and accuracy of the leakage test. Attached Figure Description

[0016] The preferred embodiments of this application will now be described in detail with reference to the accompanying drawings to help understand the purpose and advantages of this application, wherein...

[0017] Figure 1 This is a schematic diagram of the structure of an airbag-type tooling in an optional embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the structure in an optional embodiment of this application, showing the tooling moving mechanism connected to the airbag-type tooling.

[0019] Figure 3 This is a schematic diagram of the structure of the airbag tooling in its initial position in an optional embodiment of this application.

[0020] Figure 4 This is a schematic diagram of the structure of the airbag tooling in the working position in an optional embodiment of this application.

[0021] Figure 5This is a schematic diagram of the structure of the airbag and the thin wall not being attached in an optional embodiment of this application. Figure 6 for Figure 5 A magnified view of part A in the image.

[0022] Figure 7 This is a schematic diagram of the structure when the airbag is attached to the thin wall in an optional embodiment of this application.

[0023] Figure 8 for Figure 7 A magnified view of part B in the image.

[0024] Figure 9 This is a pressure balance diagram of the airbag and the thin wall when they are in contact, according to an optional embodiment of this application.

[0025] Figure 10 This is a schematic diagram of the structure of the airbag and the workpiece under test when inflated, according to an optional embodiment of this application.

[0026] Figure 11 This is a schematic diagram of the structure of the airbag and the workpiece under test during exhaust in an optional embodiment of this application.

[0027] Explanation of reference numerals in the attached figures: 1-Airbag-type fixture, 10-Support frame, 100-Frame body, 101-Rigid plate, 11-Airbag, 110-Inflation and exhaust port, 2-Workpiece under test, 20-Thin wall, 21-Moving trolley, 3-Support frame, 4-Fixed fixture moving mechanism, 40-Servo motor, 41-Lead screw, 42-Nut, 43-Linear guide rail, 5-Quick disassembly and assembly mechanism, 6-First gas circuit, 60-Main circuit, 600-Inflation control valve, 61-Inflation circuit, 610-One-way valve, 62-Exhaust circuit, 620-Adjustable pressure relief valve, 7-Second gas circuit, 8-Leakage test system, 80-Test gas source. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to embodiments and accompanying drawings. The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. These directional terms are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0029] The deformation suppression device for gas leakage testing of thin-walled structures provided in this application includes: an airbag-type fixture 1.

[0030] like Figure 1As shown, the airbag tooling 1 includes a support frame 10 and an airbag 11 installed on one side of the support frame 10. The airbag 11 and the support frame 10 together form an airbag cavity; or, the airbag 11 itself is an independent flexible sealed bag body, and its back is attached to the support frame 10. The internal space of the airbag 11 constitutes the airbag cavity.

[0031] The inflation / deflation port 110 is used to connect to the test air source 80. When the inflation / deflation port 110 is inflated, the airbag 11 undergoes elastic deformation under air pressure, closely adhering to the outer surface of the thin wall 20 of the workpiece 2 under test and forming a covering layer to isolate the direct flow contact between the ambient air and the outer surface of the thin wall 20. By controlling the air pressure in the airbag cavity to be consistent with the air pressure on the inner surface of the thin wall 20, the deformation of the thin wall 20 is suppressed.

[0032] Furthermore, the airbag 11, after inflation, has a coverage area greater than or equal to the outer surface area of ​​the thin wall 20 of the workpiece 2 being tested, thereby achieving full coverage deformation suppression and full outer surface airflow isolation for the thin wall 20. The airbag 11 is a flexible film made of an elastic material (such as silicone rubber, polyurethane, or neoprene rubber), with a thickness not exceeding 1 mm, and sufficient elongation to tightly adhere to the outer surface of the thin wall 20. The edges of the airbag 11 are fixed to the periphery of the support frame 10 by means of pressure strips, adhesives, or mechanical clamping.

[0033] The airbag 11 can either form a sealed airbag cavity together with the support frame 10, or it can be an independent sealed bag with one side of its surface attached to the support frame 10.

[0034] Optionally, the workpiece 2 under test is a power battery pack, the thin wall 20 is the metal cover of the power battery pack, and the shape of the airbag-type tooling 1 matches the outer surface of the thin wall 20 to achieve uniform fit.

[0035] like Figure 1 As shown, the support frame 10 can be a rigid frame made of metal or high-strength engineering plastic, with a profile adapted to the shape of the thin-walled 20. One side of the support frame 10 is an open surface for mounting the airbag 11, and the other side can be provided with reinforcing ribs or mounting interfaces.

[0036] Optionally, the inflation / deflation port 110 is located on the support frame 10 (the airbag 11 and the support frame 10 together form an airbag cavity) or on the airbag 11 (the airbag 11 forms an airbag cavity on its own), and is a metal or plastic nozzle with internal threads or quick-connect fittings, used to connect to an external test air source 80.

[0037] The deformation suppression device for gas leakage testing of thin-walled structures provided in this application embodiment has an air bladder cavity connected to a test gas source 80 via an inflation / deflation port 110. The inflated air bladder 11 has a coverage area greater than or equal to the outer surface area of ​​the thin-walled structure 20 and fits tightly against the entire outer surface of the thin-walled structure 20, providing uniform support to the thin-walled structure 20 and preventing local buckling. The air pressure in the air bladder cavity is controlled to be the same as the air pressure on the inner surface of the thin-walled structure 20, thereby ensuring that the inner and outer surfaces of the thin-walled structure 20 bear the same pressure. The net pressure of the thin-walled structure 20 is zero, so even if the thin-walled structure 20 itself has low stiffness, it will not undergo elastic deformation or permanent deformation. In addition, the air bladder 11 acts as a covering layer, isolating the outer surface of the thin-walled structure 20 from the ambient airflow. The ambient airflow cannot directly wash over the outer surface of the thin-walled structure 20, thereby avoiding temperature fluctuations caused by convective heat transfer. This keeps the internal gas density and pressure of the workpiece 2 under test constant, improving the repeatability and accuracy of the leakage test.

[0038] In an optional embodiment, the device further includes a support frame 3 and a tooling moving mechanism 4 mounted on the support frame 3. The support frame 3 is fixedly arranged to support and position the tooling moving mechanism 4. The tooling moving mechanism 4 is connected to the support frame 10 to drive the airbag-type tooling 1 to move between at least two positions. The two positions include an initial position for loading and unloading the workpiece 2 under test, and a working position where the airbag 11 contacts the thin wall 20 of the workpiece 2 under test during the leakage test. When the airbag-type tooling 1 is in the initial position, it is away from the workpiece 2 under test, leaving sufficient space for the moving trolley 21 to enter and exit or for the robot arm to load and unload, thus moving the workpiece 2 under test to the test position. Figure 3 As shown; in the working position, the airbag fixture 1 descends (or advances) until the airbag 11 makes slight contact with the outer surface of the thin-walled 20. The moving trolley 21 is supported below the workpiece 2 being measured. At this time, the airbag 11 is not yet inflated or only in low-pressure pre-contact, as shown. Figures 4 to 6 As shown, by switching the airbag-type tooling 1 between the initial position and the working position, the switching between automated loading / unloading and testing is realized, thereby improving production efficiency.

[0039] Specifically, the tooling moving mechanism 4 includes a servo motor 40 (servo electric cylinder), a lead screw and nut pair, a linear guide rail 43, a slider, and a mounting base, such as... Figure 2 As shown, the output shaft of the servo motor 40 is rigidly connected to one end of the lead screw 41 via a coupling. The nut 42 is sleeved on the lead screw 41 and fixed to the support frame 10 of the airbag tooling 1 via a nut seat. The linear guide rail 43 is installed on the support frame 3 and extends along the axial direction of the lead screw 41. The slider is fixedly connected to the back of the support frame 10 and can slide along the linear guide rail to ensure that the nut 42 can only move linearly and cannot rotate with the lead screw 41.

[0040] Optionally, such as Figure 2As shown, there are two linear guide rails 43, which are respectively set on both sides of the lead screw 41, and there are two sliders, which are respectively slidably set on the linear guide rails 43.

[0041] Furthermore, after the nut 42 moves the airbag fixture 1 to the working position along the linear guide rail 43, the brake or lead screw built into the servo motor 40 self-locks (the self-locking condition must be met) to keep the airbag fixture 1 stationary in the working position to ensure the stability of the leak test.

[0042] In an optional embodiment, the support frame 10 includes a frame body 100 and a rigid plate 101 mounted on one side of the frame body 100. The airbag 11 is located on one side of the rigid plate 101 and, after inflation, is fitted between the rigid plate 101 and the outer surface of the thin wall 20. In this embodiment, the rigid plate 101 provides uniform back support, preventing uneven air pressure distribution caused by local deformation of the support frame 10 when the airbag 11 is inflated. The two side walls of the airbag 11 are respectively fixed to the rigid plate 101 and fitted to the workpiece 2 under test, so that the airbag 11 expands mainly towards the workpiece 2 under test during inflation, reducing energy loss.

[0043] Among them, such as Figure 1 As shown, the frame body 100 can be an outer frame made of square or rectangular steel pipes welded or bolted together, providing overall rigidity. The rigid plate 101 is a metal plate (such as an aluminum alloy plate or steel plate) with a thickness greater than or equal to 5mm, fixed to the back of the frame body 100 by screws or welding. The surface of the rigid plate 101 is flat, and its area is comparable to the area of ​​the airbag 11 when deployed. The airbag 11 can be a bag-shaped structure, with one side wall (back) fixed to the entire inner surface of the rigid plate 101 by adhesive or pressure strips; the other side wall (front) fits seamlessly with the outer surface of the thin wall 20 after inflation, such as... Figures 7 to 9 As shown, the air pressure inside the airbag cavity is consistent with the air pressure inside the workpiece 2 being tested, so as to avoid deformation of the thin wall 20. The rigid plate 101 provides support and force transmission for the airbag 11.

[0044] In an optional embodiment, the airbag 11 is mounted on the support frame 10 via a quick-release mechanism 5. The quick-release mechanism 5 includes a pressure strip, which is used to secure the airbag 11 after it is mounted on the support frame 10. The airbag 11 is a consumable part (due to long-term expansion, contraction, and friction). The quick-release structure can significantly shorten replacement time and reduce maintenance costs. The pressure strip is evenly pressed to ensure the positional stability of the airbag 11 relative to the support frame 10.

[0045] In an optional embodiment, the quick-release mechanism 5 includes a ferromagnetic layer located on the rigid plate 101, and the pressure strip can be adsorbed onto the ferromagnetic layer; alternatively, the pressure strip is installed on the rigid plate by bolt connection or snap-fit. Magnetic adsorption ensures that the airbag 11 embedded between the pressure strip and the support frame 10 is subjected to uniform force, resulting in stable and reliable operation. Furthermore, no screws or tools are required, making installation and disassembly extremely fast. Bolt connection or snap-fit ​​can also be used to secure the airbag to the rigid plate via the pressure strip.

[0046] In one optional embodiment, a layer of magnetic material (such as an iron-nickel alloy sheet) is electroplated, sprayed, or pasted onto the surface of the rigid plate 101 facing the airbag 11, or the rigid plate 101 itself is made of ferromagnetic steel; the pressure strip is made of permanent magnet material (such as neodymium iron boron magnet), or a bar magnet is embedded inside the pressure strip, the magnetic pole direction of which allows the pressure strip to be firmly attracted to the ferromagnetic layer. During installation, after placing the edge of the airbag 11 between the rigid plate 101 and the pressure strip, the magnetic pressure strip is directly attracted to the rigid plate 101, and the airbag 11 is pressed tightly by magnetic force.

[0047] In another optional embodiment, the pressure strip is a long strip of metal or hard plastic, the length of which matches the circumferential edge of the support frame 10, and the pressure strip has an L-shaped or T-shaped cross-section. The outer edge of the airbag 11 is pre-fitted with a thickened sealing lip. During installation, the edge of the airbag 11 is first placed on the circumferential plane of the support frame 10, the pressure strip is placed on top, the sealing lip is located on the outside of the pressure strip, and the screws are tightened to fix the pressure strip to the support frame 10, thereby positioning the edge of the airbag 11. It should be noted that the screws pass through the pressure strip and the area of ​​the support frame 10 where the airbag 11 is not installed, locking the pressure strip to the support frame 10. In an optional embodiment, the inflation / deflation port 110 is connected to a first gas circuit 6, which includes a main circuit 60 and an inflation circuit 61 and an deflation circuit 62 connected in parallel. The main circuit 60 is connected in series with the inflation circuit 61 and the deflation circuit 62. An inflation control valve 600 is provided on the main circuit 60, a one-way valve 610 is provided on the inflation circuit 61, and an adjustable pressure relief valve 620 is provided on the deflation circuit 62. This embodiment can precisely control the inflation pressure and rate, avoiding impact on the workpiece during inflation. Simultaneously, the one-way valve 610 ensures that even if the main circuit 60 loses pressure during inflation, the airbag cavity will not immediately deflate, maintaining a proper fit. The adjustable pressure relief valve 620 can automatically close after reducing the airbag cavity pressure to a set value (e.g., 0.02 MPa) during deflation, retaining a certain positive pressure, allowing the airbag 11 to inflate faster in the next test inflation, thus reducing the inflation time for the next test.

[0048] like Figures 10 to 11As shown, the main circuit 60 is the pipeline from the test gas source 80 to the branch point, with an inflation control valve 600 (electric proportional valve or on / off valve + pressure sensor) connected in series on it; the inflation circuit 61 is the pipeline from the branch point to the airbag cavity, with a one-way valve 610 (pointing towards the airbag cavity) installed on it to prevent backflow of gas in the airbag 11; the exhaust circuit 62 is the pipeline from the airbag cavity to the atmosphere (or recovery tank), connected in parallel with the inflation circuit 61, with an adjustable pressure relief valve 620 (such as a spring-loaded overflow valve or back pressure valve) installed on it. Gas from the test gas source 80 passes through the main circuit 60, reaches the branch point, and then inflates the airbag 11 through the inflation circuit 61, or during the exhaust process, the gas in the airbag 11 is discharged through the exhaust circuit 62.

[0049] In an optional embodiment, the workpiece 2 under test is connected to a second gas circuit 7, which is connected in parallel with the first gas circuit 6 and both are connected to a leak testing system 8, which includes the test gas source 80. In this embodiment, the airbag 11 and the workpiece 2 under test are simultaneously inflated by the same test gas source 80, ensuring that their pressures rise synchronously, ultimately achieving the goal of having the same air pressure in the airbag 11 and the workpiece 2 under test. The parallel structure avoids interference from the airbag 11 to the gas path of the workpiece 2 under test, resulting in more accurate test data. The first gas circuit 6 (supplying the airbag 11) and the second gas circuit 7 (supplying the workpiece 2 under test) share the same test gas source 80, but are controlled independently. The two circuits branch at the outlet of the test gas source 80, and then enter the airbag 11 and the workpiece 2 under test, respectively.

[0050] Optionally, a differential pressure sensor is installed between the inflation circuit 61 of the first gas circuit 6 and the second gas circuit 7. The high-pressure end of the differential pressure sensor is connected to the interior of the workpiece 2 being measured (through the pressure measuring port of the second gas circuit 7), and the low-pressure end is connected to the air bladder cavity (through the pressure measuring port of the first gas circuit 6). The electrical signal output terminal of the differential pressure sensor is connected to a controller (e.g., a PLC or a dedicated pressure controller), which is also electrically connected to the inflation control valve 600.

[0051] During the inflation phase: the leakage test system 8 simultaneously inflates the workpiece 2 and the airbag 11. The controller reads the pressure difference ΔP = P_workpiece - P_airbag from the differential pressure sensor in real time.

[0052] Pressure synchronization adjustment stage: If ΔP>0 (workpiece pressure is higher than airbag pressure), the controller outputs a signal to increase the opening of the inflation control valve 600, allowing more gas to enter the airbag chamber and increasing P_airbag; if ΔP<0, the controller reduces the opening of the inflation control valve 600 or briefly opens the adjustable pressure relief valve 620 to decrease P_airbag; if ΔP is within the allowable error range (e.g., ±50Pa), the controller maintains the current valve state.

[0053] Pressure Holding Phase: Once both sides reach the target test pressure, the leakage test system 8 closes the main inflation valve and enters the leakage detection cycle. During this period, the controller continues to monitor ΔP. If ΔP exceeds the threshold due to temperature changes or minor leaks, the controller fine-tunes the pressure in the air bladder chamber by controlling the opening of the inflation control valve 600 and the adjustable pressure relief valve, causing ΔP to return to zero and ensuring that the pressure inside and outside the thin-walled 20 remains equal.

[0054] If the differential pressure sensor detects that ΔP exceeds the safety limit (e.g., >5kPa), the controller will immediately issue an alarm and open the exhaust circuit 62 to prevent the thin-walled 20 from being damaged due to excessive pressure difference.

[0055] In an optional embodiment, the support frame 10 is provided with a vacuum adsorption auxiliary positioning mechanism, including: at least two vacuum suction cups arranged circumferentially along the support frame 10; a vacuum distribution pipeline connecting the at least two vacuum suction cups to an external vacuum source; when the airbag fixture 1 is in the working position, the adsorption surface of the vacuum suction cups adsorbs onto the non-thin-walled area 20 of the workpiece 2 under test or an external fixed base, which is used to pre-fix the entire airbag fixture 1 in the target position before the airbag 11 is inflated, ensuring that the relative position of the airbag and the thin-walled area 20 of the airbag 11 is completely consistent during each test, thereby improving the repeatability and accuracy of the leakage rate test data. Pre-fixation can resist the backlash force generated by the gas flow during the initial inflation of the airbag 11, prevent the support frame 10 from shifting, and the vacuum adsorption does not damage the surface of the workpiece 2 under test (the non-thin-walled area has high strength). Moreover, compared with mechanical clamping, the vacuum response is fast, the structure is simple, and it is easy to release automatically.

[0056] Optionally, the vacuum chucks are disc-shaped chucks made of silicone rubber or polyurethane, with at least two (usually one at each of the four corners), fixed to the edge of the support frame 10 or its extension arm by threads or clips. The suction surface of the chucks faces the frame (non-thin-walled area) of the workpiece 2 being tested or the positioning plate on the test bench. The vacuum distribution pipeline consists of nylon or PU tubing, multi-way connectors, a vacuum pressure valve, and a vacuum solenoid valve, connecting the chucks to a factory vacuum source or vacuum generator.

[0057] During operation, when the tooling moving mechanism 4 delivers the airbag tooling 1 to the working position, the vacuum solenoid valve opens, the suction cup draws a vacuum, and the vacuum suction force firmly pulls the support frame 10 toward the workpiece 2 being measured, so that the thin film of the airbag 11 and the outer surface of the thin wall 20 maintain the set initial gap (or slight contact). Then, the controller outputs a signal to close the brake of the servo motor 40 of the tooling moving mechanism 4 and opens the first gas circuit 6 to inflate the airbag 11.

[0058] In an optional embodiment, an inflatable auxiliary airbag layer is provided between the support frame 10 and the airbag 11. The auxiliary airbag layer is independent of the airbag cavity and has a separate auxiliary inflation / deflation port. After the airbag 11 is inflated and adheres to the outer surface of the thin wall 20, the inflation pressure of the auxiliary airbag layer is controlled to be greater than the pressure of the airbag cavity to increase the overall uniformity of the fit between the airbag 11 and the thin wall 20. This embodiment solves the problem of incomplete fit of the single-layer airbag 11 when there are depressions or curved surfaces on the surface of the workpiece 2 being tested. The back pressure of the auxiliary airbag layer causes the main airbag 11 to undergo secondary deformation, tightly filling the tiny gaps, significantly improving the overall uniformity of the fit, and avoiding test errors caused by local suspension.

[0059] Optionally, the auxiliary airbag layer is another independent flexible airbag located between the rigid plate 101 of the support frame 10 and the airbag 11. The periphery of the auxiliary airbag layer is fixed to the support frame 10, and it is separated from the airbag 11 by a thin diaphragm, or the back of the airbag 11 can directly serve as the front of the auxiliary airbag layer. A separate auxiliary inflation / deflation port can pass through the support frame 10 or the rigid plate 101 and connect to an independent test air source 80 pipeline and pressure control valve.

[0060] The following steps can be used to implement this application: the airbag cavity is first inflated to pressure P1 (equal to the internal pressure of the workpiece 2 being tested), and the airbag 11 is attached to the outer surface of the thin wall 20; the auxiliary airbag layer is inflated to pressure P2 through the auxiliary inflation and deflation port, and P2>P1; the auxiliary airbag layer expands, and pushes the airbag 11 evenly from the back to press it further against the outer surface of the thin wall 20, filling the microscopic uneven areas.

[0061] In an optional embodiment, the airbag 11 has a flow-guiding structure on the side facing the outer surface of the thin-walled 20. The flow-guiding structure includes multiple intersecting or parallel grooves. As the airbag 11 gradually adheres to the outer surface of the thin-walled 20, the air between the airbag 11 and the outer surface of the thin-walled 20 is discharged through the grooves. This embodiment allows the airbag 11 to adhere to the outer surface of the thin-walled 20, and the air in the middle area is quickly discharged, avoiding the formation of closed air pockets that prevent this area from contacting the workpiece 2 being tested.

[0062] Optionally, the grooves can be formed on the surface of the thin film of the airbag 11 facing the workpiece 2 by molding, laser engraving, or chemical etching. The grooves have a depth of 0.05mm to 0.5mm and a width of 0.1mm to 1.0mm. The grooves can be in the form of a grid (intersecting each other) or parallel stripes. All grooves are interconnected and extend to the edge of the airbag 11. When the airbag 11 gradually adheres to the workpiece 2 from the center outwards, the air trapped between the airbag 11 and the workpiece 2 is squeezed into the grooves and flows along the grooves to the edge of the airbag 11 and is discharged. This allows the airbag 11 to completely adhere to the surface of the workpiece 2 without forming bubbles or bulges.

[0063] In an optional embodiment, a flexible electric heating film is embedded inside or on the back of the airbag 11. This flexible electric heating film is a carbon fiber heating film with a polyimide substrate and a power density of 0.5 W / cm² to 1.5 W / cm². The flexible electric heating film is connected to a power source via a temperature controller. Before the leak test begins, the temperature controller preheats the surface temperature of the airbag 11 to the same temperature as the test gas inside the workpiece 2 (e.g., 25 ± 0.5 °C), with a preheating time not exceeding 30 seconds. After preheating, the airbag 11 will not absorb heat from the surface of the thin wall 20 due to its lower temperature when it is in contact with the thin wall 20, thus avoiding pressure changes caused by localized temperature drops in the thin wall 20 and further improving the accuracy of the leak test.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A deformation suppression device for testing gas leakage in thin-walled structures, characterized in that, include: An airbag-type tooling includes a support frame and an airbag installed on one side of the support frame. The airbag and the support frame together define an airbag cavity, or the airbag alone defines an airbag cavity. The airbag cavity is provided with an inflation / deflation port. The inflation / deflation port is used to connect to the test air source. When the inflation / deflation port is inflated, the airbag undergoes elastic deformation under air pressure, closely adhering to the outer surface of the thin wall of the workpiece under test and forming a covering layer to isolate the direct flow contact between the ambient air and the outer surface of the thin wall. By controlling the air pressure in the airbag cavity to be consistent with the air pressure on the inner surface of the thin wall, deformation of the thin wall is suppressed.

2. The deformation suppression device for gas leakage testing of thin-walled structures according to claim 1, characterized in that, It also includes a support frame and a tooling moving mechanism mounted on the support frame; The support frame is fixedly installed, and the tooling moving mechanism is connected to the support frame to drive the airbag tooling to move between at least two positions. The two positions include the initial position for loading and unloading the workpiece under test, and the working position where the airbag contacts the thin wall of the workpiece under test during the leakage test. When the airbag fixture is in its initial position, the workpiece to be tested is moved to the test position by a trolley or a robotic arm.

3. The deformation suppression device for gas leakage testing of thin-walled structures according to claim 1, characterized in that, The support frame includes a frame body and a rigid plate installed on one side of the frame body. The airbag is located on one side of the rigid plate and is fitted between the outer surface of the rigid plate and the thin wall after inflation.

4. The deformation suppression device for gas leakage testing of thin-walled structures according to claim 2, characterized in that, The airbag is installed on the support frame via a quick-release mechanism, which includes a pressure strip for securing the airbag after it is installed on the support frame.

5. The deformation suppression device for gas leakage testing of thin-walled structures according to claim 4, characterized in that, The quick assembly / disassembly mechanism includes a ferromagnetic layer located on the rigid plate, and the pressure strip can be adsorbed onto the ferromagnetic layer; Alternatively, the pressure strip can be installed on the rigid plate by means of bolt connection or snap-fit.

6. The deformation suppression device for gas leakage testing of thin-walled structures according to claim 1, characterized in that, The inflation / exhaust port is connected to a first gas circuit, which includes a main circuit and an inflation circuit and an exhaust circuit connected in parallel. The main circuit is connected in series with the inflation circuit and the exhaust circuit connected in parallel. The main circuit is equipped with an inflation control valve, the inflation circuit is equipped with a one-way valve, and the exhaust circuit is equipped with an adjustable pressure relief valve.

7. The deformation suppression device for gas leakage testing of thin-walled structures according to claim 6, characterized in that, The workpiece under test is connected to a second gas circuit, which is connected in parallel with the first gas circuit and both are connected to a leak testing system, which includes the test gas source.

8. The deformation suppression device for gas leakage testing of thin-walled structures according to claim 1, characterized in that, The support frame is equipped with a vacuum adsorption-assisted positioning mechanism, including: At least two vacuum suction cups are arranged circumferentially along the support frame; A vacuum distribution pipeline connects at least two of the vacuum chucks to an external vacuum source; When the airbag-type fixture is in the working position, the suction surface of the vacuum suction cup is adsorbed onto the non-thin-walled area of ​​the workpiece being tested or the external fixed base, which is used to pre-fix the airbag-type fixture in the target position before the airbag is inflated.

9. The deformation suppression device for gas leakage testing of thin-walled structures according to claim 1, characterized in that, An inflatable auxiliary airbag layer is provided between the support frame and the airbag. The auxiliary airbag layer is independent of the airbag cavity and has a separate auxiliary inflation / deflation port. After the airbag is inflated and adheres to the outer surface of the thin wall, the inflation pressure of the auxiliary airbag layer is controlled to be greater than the pressure of the airbag cavity to increase the overall uniformity of the fit between the airbag and the thin wall.

10. The deformation suppression device for gas leakage testing of thin-walled structures according to claim 1, characterized in that, The airbag has a flow guiding structure on the side facing the outer surface of the thin wall, and the flow guiding structure includes multiple grooves that intersect or are distributed in parallel. As the airbag gradually adheres to the outer surface of the thin wall, the air located between the airbag and the outer surface of the thin wall is discharged through the groove; Alternatively, the inner or outer wall of the airbag may be provided with a flexible electrically heated film.

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