Method for detecting the air tightness of a closed cavity

Abstract

The application discloses a kind of airtightness detection methods of closed cavity, the closed cavity of product to be measured is completely immersed in liquid in container, then container is placed in negative pressure environment and is kept for a period of time after pressure relief, inside and outside the closed cavity will form pressure difference, if there is small leak hole in closed cavity, external liquid will be driven by pressure difference and infiltrate into closed cavity from leak hole, and if the airtightness of closed cavity is good, external liquid will not enter closed cavity, therefore, subsequent can be observed whether there is liquid infiltration in the closed cavity of product to be measured to determine the airtightness of closed cavity.The method can use pressure difference to press external liquid into closed cavity, and does not need to use external tooling to detect pressure / negative pressure, which solves the problem that bubbles cannot be observed due to small leak hole in traditional method, and solves the problems of difficult sealing, easy air leakage, low detection accuracy and low efficiency caused by lack of special detection interface in traditional closed cavity.

Description

Technical Field

[0001] This invention relates to the field of airtightness testing technology, and more specifically to a method for testing the airtightness of a sealed cavity. Background Technology

[0002] Some products with enclosed cavities need to undergo airtightness testing after production, before leaving the factory, or before use. For example, the floats commonly used in ink cartridges to detect the level of ink can be made more accurate by setting up enclosed cavities to increase buoyancy. This requires ensuring the complete sealing of the float to prevent water or air leakage.

[0003] The conventional testing method involves immersing the product's sealed cavity in water and observing for air bubbles to determine if there is a leak. However, this method has limitations. When the leakage pores in the sealed cavity are small, it is often difficult to observe air bubbles, making this method inaccurate and less precise. Furthermore, the float cavity lacks a pre-installed dedicated testing interface. If external fixtures are used for pressure / negative pressure testing, secondary sealing issues can easily occur at the interface between the fixture and the float, introducing additional leakage risks. Moreover, the interface adaptation and fixture installation process is cumbersome and inefficient, making it unsuitable for testing the airtightness of floats. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for testing the airtightness of a closed cavity, so as to solve the problems of difficult sealing, easy leakage, low detection accuracy and low efficiency caused by the lack of a dedicated testing interface for traditional closed cavities.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: a method for detecting the airtightness of a sealed cavity, comprising the following steps: Provide a container filled with liquid, and completely immerse the closed cavity of the product to be tested in the liquid in the container, always keeping the closed cavity below the liquid level; Place the container and the product to be tested together in a negative pressure environment and maintain the pressure for a period of time before releasing the pressure. Remove the product to be tested and observe whether any liquid has seeped into the sealed cavity of the product.

[0006] Compared to existing technologies, the advantages of this invention are as follows: This method completely immerses the sealed cavity below the liquid surface in the container and places it in a negative pressure environment for pressure maintenance followed by depressurization. A pressure difference is created between the inside and outside of the sealed cavity. If there are tiny leaks in the sealed cavity, external liquid will seep into the sealed cavity under the pressure difference. Conversely, if the sealed cavity is airtight, external liquid will not be able to enter. Therefore, the airtightness of the sealed cavity can be determined by observing whether liquid has seeped into it. This method utilizes pressure difference to force external liquid into the sealed cavity without requiring external tooling for pressure / negative pressure testing. This solves the problem of not being able to observe bubbles due to small leaks in traditional methods, and also addresses the problems of difficult sealing, easy leakage, low detection accuracy, and low efficiency caused by the lack of a dedicated testing interface in traditional sealed cavities.

[0007] The above-mentioned method for testing the airtightness of a closed cavity, in the step of "taking out the product to be tested and observing whether there is liquid seepage into the closed cavity of the product to be tested", uses a measuring projector to observe the internal condition of the closed cavity to determine whether there is liquid seepage into the closed cavity, or uses a weighing measurement method to determine whether there is liquid seepage into the closed cavity based on the weight difference before and after.

[0008] The above-mentioned method for testing the airtightness of a closed cavity includes the following steps in the procedure of "removing the product to be tested and observing whether there is liquid seepage into the closed cavity of the product to be tested": Remove the product to be tested and remove the moisture from its surface; Place the product under test on the stage of the measuring projector, adjust the magnification of the measuring projector, focus on the closed cavity of the product under test, and observe whether there is liquid seepage into the closed cavity.

[0009] The above-mentioned method for testing the airtightness of a closed cavity includes the following steps in the procedure of "removing the product to be tested and observing whether there is liquid seepage into the closed cavity of the product to be tested": Remove the product to be tested and remove the moisture from its surface; Weigh the product to be tested, W1, and calculate the weight difference before and after, ΔW = W1. If ΔW > A, the sealed cavity is judged to have a leakage defect; if ΔW ≤ A, the sealed cavity is judged to be qualified in terms of airtightness. Where W0 is the initial weight of the product under test, and A is the preset leakage judgment threshold.

[0010] The above-mentioned method for testing the airtightness of a closed cavity includes the following steps in the step "removing the product to be tested and removing moisture from the surface of the product to be tested": Remove the product to be tested and gently wipe the moisture off the outer surface of the product with a lint-free cloth; After wiping, place the product to be tested in a constant temperature oven and adjust the drying temperature and time to completely evaporate the residual moisture on the outer surface of the product to be tested. After drying, place the product to be tested in a desiccator to cool to room temperature.

[0011] The above-mentioned method for testing the airtightness of a closed cavity further includes the following steps before the step "providing a container filled with liquid, completely immersing the closed cavity of the product to be tested in the liquid in the container, and always keeping the closed cavity below the liquid level": Take the product to be tested, wipe its outer surface with anhydrous ethanol, then let it air dry naturally, and weigh it to obtain the initial weight W0 of the product to be tested.

[0012] In the above-mentioned method for testing the airtightness of a closed cavity, in the step "providing a container filled with liquid, completely immersing the closed cavity of the product to be tested in the liquid in the container, and always keeping the closed cavity below the liquid surface", after the product to be tested is completely immersed in the liquid in the container, it is shaken to remove air bubbles adhering to the surface of the product to be tested.

[0013] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0014] Figure 1 This is a flowchart of the airtightness testing method for a closed cavity according to the present invention; Figure 2 These are schematic diagrams of the floats described in Embodiments 1 and 2 of the present invention. Figure 3 This is a flowchart of the airtightness testing method according to Embodiment 1 and Embodiment 2 of the present invention.

[0015] The diagram shows the following symbols: 100 float, 110 enclosed cavity, 120 transparent membrane. Detailed Implementation

[0016] This invention provides a method for detecting the airtightness of a sealed cavity, comprising the following steps: Provide a container filled with liquid, and completely immerse the closed cavity of the product to be tested in the liquid in the container, always keeping the closed cavity below the liquid level; Place the container and the product to be tested together in a negative pressure environment and maintain the pressure for a period of time before releasing the pressure. Remove the product to be tested and observe whether any liquid has seeped into the sealed cavity of the product.

[0017] This method involves completely immersing the sealed cavity below the liquid level in the container and placing it under negative pressure. After pressure is maintained and then released, a pressure difference is created between the inside and outside of the sealed cavity. If there are tiny leaks in the sealed cavity, external liquid will seep into the cavity under the pressure difference. Conversely, if the sealed cavity is airtight, external liquid will not be able to enter. Therefore, the airtightness of the sealed cavity can be determined by observing whether liquid has seeped into it. This method utilizes pressure difference to force external liquid into the sealed cavity without requiring external tooling for pressure / negative pressure testing. It solves the problem of not being able to observe air bubbles due to small leaks in traditional methods, and also addresses the issues of difficult sealing, easy leakage, low detection accuracy, and low efficiency caused by the lack of a dedicated testing interface in traditional sealed cavities.

[0018] It should be noted that the product under test often has other structures besides the closed cavity. During testing, only the closed cavity needs to be immersed in the liquid. Therefore, the "complete immersion of the closed cavity of the product under test into the liquid in the container" mentioned in this invention does not mean that the entire product under test is completely immersed in the liquid in the container.

[0019] Example 1 Embodiment 1 of the present invention provides a method for testing the airtightness of an ink cartridge float 100. The ink cartridge float 100 is a key structure used to detect the remaining ink level in the ink cartridge. The float 100 has a closed cavity 110 inside, which generates buoyancy to float in the ink. Therefore, its airtightness is particularly important. The following is the method for testing the airtightness of the float 100: Step S100: Take the float to be tested 100 and wipe the outer surface of the float 100 with anhydrous ethanol to remove oil, dust and residual moisture. Step S200: Provide a water tank filled with pure water. Completely immerse the pretreated float 100 in the pure water in the tank. A baffle or other structure can be set on the upper layer of the water tank to ensure that the float 100 is completely covered by pure water with no part exposed above the water surface. Alternatively, a fixing structure can be set at the bottom of the water tank and fixed to the other structures of the float 100 to avoid affecting the parts of the float 100 that need to be tested for air tightness. This also ensures that the float 100 remains below the liquid surface during subsequent testing steps. After immersing the float 100, gently shake the float 100 or the water tank to remove air bubbles attached to the surface of the float 100, so as to prevent residual air bubbles from affecting the subsequent negative pressure test results. Step S300: Place the water tank immersed in float 100 into the vacuum chamber, close the vacuum chamber door and start the vacuum device to pump the pressure inside the vacuum chamber to about -600 mmHg and maintain the pressure for 5 minutes. If there is a leakage hole on float 100, even if the leakage hole is small, the negative pressure parameter of -600 mmHg can effectively drive water into the micron-sized leakage hole. The 5-minute pressure holding time is sufficient to ensure that the water fully penetrates and avoids missed detection due to insufficient penetration. Step S400: After holding the pressure for 5 minutes, open the vacuum box pressure relief valve. After the pressure is released, remove the float 100 from the water and gently wipe the residual moisture on the outer surface of the float 100 with a lint-free cloth. Step S500: Place the float 100 on the stage of the measuring projector, adjust the magnification of the measuring projector to 3-8 times, focus on the internal space of the closed cavity 110 of the float 100, and observe whether the following characteristics are present inside the closed cavity 110: visible water droplets, water mist, or local condensation, or water stains on the wall of the closed cavity 110. If any of the above characteristics are present, the float 100 is determined to have a leakage defect. If there are no water droplets, water mist, or local condensation inside the closed cavity 110, and no water stains on the wall of the closed cavity 110, the float 100 is determined to be airtight. It can be understood that the detection method in this embodiment is for the float 100 of the ink cartridge, such as... Figure 2 As shown, the float 100 of the ink cartridge has a cavity, and a transparent membrane 120 is provided at the opening of the cavity. The transparent membrane 120 seals the cavity to form a closed cavity 110. Since the float 100 has a transparent membrane 120, a measuring projector can be used to allow light to penetrate the transparent membrane 120 of the float 100 for projection observation. It can be clearly seen whether there are water droplets, water mist or local condensation inside the closed cavity 110.

[0020] Example 2 Embodiment 2 of the present invention provides another method for testing the airtightness of the ink cartridge float 100. The difference between this method and Embodiment 1 is that, after depressurization, a weighing measurement method is used to determine the airtightness of the float 100. The following is the airtightness testing method for the float 100 in Embodiment 2: Step S100: Take the float to be tested 100, wipe the outer surface of the float 100 with anhydrous ethanol to remove oil, dust and residual moisture, and place the float 100 in a room temperature, ventilated and dust-free environment to air dry naturally to ensure that there are no attached substances or residual moisture on the outer surface of the float 100 to avoid interfering with the subsequent weighing test results. Then weigh the float 100 to obtain the initial weight W0 of the float 100. Step S200: Provide a water tank filled with pure water. Completely immerse the pretreated float 100 in the pure water in the tank. A baffle or other structure can be set on the upper layer of the water tank to ensure that the float 100 is completely covered by pure water with no part exposed above the water surface. Alternatively, a fixing structure can be set at the bottom of the water tank and fixed to the other structures of the float 100 to avoid affecting the parts of the float 100 that need to be tested for air tightness. This also ensures that the float 100 remains below the liquid surface during subsequent testing steps. After immersing the float 100, gently shake the float 100 or the water tank to remove air bubbles attached to the surface of the float 100, so as to prevent residual air bubbles from affecting the subsequent negative pressure test results. Step S300: Place the water tank immersed in float 100 into the vacuum chamber, close the vacuum chamber door and start the vacuum device to pump the pressure inside the vacuum chamber to about -600 mmHg and maintain the pressure for 5 minutes. If there is a leakage hole on float 100, even if the leakage hole is small, the negative pressure parameter of -600 mmHg can effectively drive water into the micron-sized leakage hole. The 5-minute pressure holding time is sufficient to ensure that the water fully penetrates and avoids missed detection due to insufficient penetration. Step S400: After holding the pressure for 5 minutes, open the vacuum box pressure relief valve. After the pressure is released, remove the float 100 from the water and gently wipe the residual moisture on the outer surface of the float 100 with a lint-free cloth. Step S500: Place the float 100 in a constant temperature oven, set the drying temperature to 60℃~80℃, and the drying time to 2 hours. Because the leakage hole is very small and the moisture on the outer surface of the float 100 is directly exposed, the evaporation rate of the moisture on the outer surface is much faster than that of the internal moisture. Setting an appropriate drying temperature and time ensures that the moisture on the outer surface of the float 100 is completely evaporated, while most of the moisture inside the sealed cavity 110 is retained. After drying, place the float 100 in a desiccator to cool to room temperature to avoid temperature changes affecting the accuracy of subsequent weight measurements. Step S600: Using an electronic analytical balance with an accuracy of 0.01g, weigh the dried float 100 (W1), and set the leakage judgment threshold A = 0.02mg. Calculate the weight difference before and after, ΔW = W1. If ΔW > A, the sealed cavity 110 is judged to have a leakage defect; if ΔW ≤ A, the sealed cavity 110 is judged to be qualified in terms of airtightness.

[0021] The detection methods in Embodiments 1 and 2 do not require a dedicated detection interface for the closed cavity 110 of the float 100, nor do they require additional sealing fixtures to dock with the float 100. The float 100 can be directly immersed in water for negative pressure detection, thus avoiding the risk of secondary air leakage caused by poor sealing at the fixture interface. It also eliminates the steps of fixture adaptation, installation and disassembly, greatly simplifying the detection process and significantly improving detection efficiency.

[0022] It should be noted that in the description of this invention, any descriptions of orientation, such as up, down, front, back, left, right, etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the purpose of facilitating the description of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and should not be construed as a limitation of this invention.

[0023] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the stated number, while "above," "below," "within," etc. are understood to include the stated number. If "first" or "second" is mentioned, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0025] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for detecting the airtightness of a sealed cavity, characterized in that, Includes the following steps: Provide a container filled with liquid, and completely immerse the closed cavity of the product to be tested in the liquid in the container, always keeping the closed cavity below the liquid level; Place the container and the product to be tested together in a negative pressure environment and maintain the pressure for a period of time before releasing the pressure. Remove the product to be tested and observe whether any liquid has seeped into the sealed cavity of the product.

2. The method for detecting the airtightness of a closed cavity according to claim 1, characterized in that, In the step "Remove the product to be tested and observe whether there is liquid seepage into the closed cavity of the product to be tested", a measuring projector is used to observe the internal condition of the closed cavity to determine whether there is liquid seepage into the closed cavity, or a weighing measurement method is used to determine whether there is liquid seepage into the closed cavity based on the weight difference before and after.

3. The method for detecting the airtightness of a closed cavity according to claim 2, characterized in that, The step "Remove the product to be tested and observe whether there is any liquid seepage into the sealed cavity of the product to be tested" includes the following steps: Remove the product to be tested and remove the moisture from its surface; Place the product under test on the stage of the measuring projector, adjust the magnification of the measuring projector, focus on the closed cavity of the product under test, and observe whether there is liquid seepage into the closed cavity.

4. The method for detecting the airtightness of a closed cavity according to claim 2, characterized in that, The step "Remove the product to be tested and observe whether there is any liquid seepage into the sealed cavity of the product to be tested" includes the following steps: Remove the product to be tested and remove the moisture from its surface; Weigh the product to be tested, W1, and calculate the weight difference before and after, ΔW = W1. If ΔW > A, the sealed cavity is judged to have a leakage defect; if ΔW ≤ A, the airtightness of the sealed cavity is judged to be qualified. Where W0 is the initial weight of the product under test, and A is the preset leakage judgment threshold.

5. The method for detecting the airtightness of a closed cavity according to claim 4, characterized in that, The step "Remove the product to be tested and remove moisture from its surface" includes the following steps: Remove the product to be tested and gently wipe the moisture off the outer surface of the product with a lint-free cloth; After wiping, place the product to be tested in a constant temperature oven and adjust the drying temperature and time to ensure that the residual moisture on the outer surface of the product to be tested is completely evaporated. After drying, place the product to be tested in a desiccator to cool to room temperature.

6. The method for detecting the airtightness of a closed cavity according to claim 4, characterized in that, Before the step "provide a container filled with liquid, completely immerse the closed cavity of the product to be tested in the liquid in the container, and always keep the closed cavity below the liquid level", the following steps are also included: Take the product to be tested, wipe its outer surface with anhydrous ethanol, then let it air dry naturally, and weigh it to obtain the initial weight W0 of the product to be tested.

7. The method for detecting the airtightness of a closed cavity according to any one of claims 1-6, characterized in that, In the step "Provide a container filled with liquid, completely immerse the closed cavity of the product to be tested in the liquid in the container, and always keep the closed cavity below the liquid surface", after the product to be tested is completely immersed in the liquid in the container, shake to remove air bubbles attached to the surface of the product to be tested.

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