Device for changing negative pressure air tightness test pressure difference and air tightness detection method

Abstract

The invention discloses a device for changing negative pressure air tightness test pressure difference, which comprises a closed box, a clamping cylinder used for pressing a tested workpiece is arranged in the closed box, a negative pressure test machine is arranged outside the closed box, an exhaust pipe is connected to the negative pressure test machine, the other pipe orifice of the exhaust pipe is arranged in the inner cavity of the tested workpiece, and the other pipe orifice of the exhaust pipe is arranged in the inner cavity of the tested workpiece. The closed box is also provided with a pressurizing air inlet pipe for pressurizing the interior of the closed box; and a pipe orifice, positioned in the closed box, of the pressurizing air inlet pipe is positioned outside the tested workpiece. The invention also discloses an air tightness detection method, which comprises the following steps of: mounting a detected workpiece on the base, starting the clamping cylinder to press the detected workpiece, filling high-pressure gas into the closed box through the pressurizing gas pipe, extracting gas in a cavity of the detected workpiece by the negative pressure tester through the exhaust pipe, and carrying out air tightness detection on the detected workpiece. The closed box is additionally arranged outside a traditional negative pressure test, the environment of the negative pressure test is arranged in the closed box, and the negative pressure exceeding one atmospheric pressure is achieved by increasing the pressure in the closed box.

Description

Technical Field

[0001] The invention relates to a device for changing the pressure difference of a negative pressure airtightness test and an airtightness detection method. Background Art

[0002] In traditional negative pressure testing, under normal conditions, the theoretical maximum pressure difference can only be below 1 atmosphere, and negative pressure testing with a pressure difference of more than 1 atmosphere cannot be achieved. There is no theoretical research or related technical literature in this regard in the prior art. For example, the patent with publication number CN117870980A: An intelligent airtightness testing system and testing method and the patent with publication number CN209894407U: Metal pressure differential tube airtightness testing quick connector and airtightness testing device are both negative pressure tests under a pressure difference of one atmosphere. This situation limits the scope of airtightness testing, making it difficult for a testing device to meet the requirements of positive and negative pressure tests under multiple pressure differential conditions. In addition, the existing airtightness testing device needs to apply a lot of pressure to the workpiece to ensure that the sealing surface is leak-proof, so as long as a certain pressure difference can be formed, there are great limitations and requirements for the sealing test of thin-walled workpieces and special-shaped workpieces. Summary of the Invention

[0003] The present invention aims to overcome the shortcomings of the prior art by providing a device for varying the pressure differential during a negative pressure airtightness test. The negative pressure test pressure can be adjusted in real time as required, significantly expanding the range of airtightness testing. Based on the characteristics of negative pressure testing, increasing the pressure differential between the inside and outside of the workpiece being tested further facilitates sealing. Due to the uniformity of the ambient pressure, this device significantly improves the sealing performance of thin-walled and irregularly shaped workpieces.

[0004] To achieve the above-mentioned purpose, the technical solution of the present invention is to design a device for changing the pressure difference of a negative pressure air tightness test, comprising a closed box, a clamping cylinder for pressing the workpiece to be tested is provided inside the closed box, a negative pressure testing machine is provided outside the closed box, an exhaust pipe is connected to the negative pressure testing machine, another pipe opening of the exhaust pipe is provided in the inner cavity of the workpiece to be tested, and a pressurized air inlet pipe for pressurizing the interior of the closed box is further provided on the closed box, the pipe opening of the pressurized air inlet pipe located in the closed box is located outside the workpiece to be tested. A closed box is added to the outside of the traditional negative pressure test, and the environment of the negative pressure test is set in the closed box. By increasing the pressure in the closed box, it is equivalent to increasing the environmental pressure of the negative pressure test, thereby increasing the pressure difference between the inside and outside of the workpiece to be tested, thereby achieving a negative pressure exceeding 1 atmosphere.

[0005] A further technical solution is that a base is provided inside the closed box, and the workpiece to be measured is connected to the base through a seal; the base and the clamping cylinder are respectively fixedly connected to an inner wall of the closed box that is oppositely arranged; the air extraction pipe first passes through the closed box, then passes through the base and is connected to the inner cavity of the workpiece to be measured. After being set up like this, when the workpiece to be measured is pressed by the clamping cylinder, it is sealed with the surface of the base, and then the inner cavity of the workpiece to be measured can be evacuated by pumping air through the air extraction pipe, while the pressurized air inlet pipe can pressurize the outside of the workpiece to be measured inside the closed box, achieving the effect that the pressure difference between the inside and outside of the workpiece to be measured exceeds 1 atmospheric pressure.

[0006] A further technical solution is that the base is fixedly connected to the inner bottom wall of the closed box, and the clamping cylinder is fixedly connected to the inner top wall of the closed box; the pressurized air inlet pipe is arranged on the side wall of the closed box.

[0007] A further technical solution is that a through hole for the air extraction pipe to pass through is provided on the top wall of the closed box, and a channel for the air extraction pipe to pass through is provided on the base. Both channel openings of the channel are located on the upper surface of the base, and one is located inside the inner cavity of the workpiece to be measured and the other is located outside the workpiece to be measured. The through hole is sealed at the through hole through a seal (such as sealant). The shape of the channel can be an arc-shaped channel or a "凵"-shaped channel, etc.

[0008] Another technical solution is that the base is fixedly connected to the inner top wall of the closed box, and the clamping cylinder is fixedly connected to the inner bottom wall of the closed box; the pressurized air inlet pipe is arranged on the side wall of the closed box; or the base and the clamping cylinder are respectively fixedly connected to a pair of oppositely arranged inner side walls of the closed box, and the pressurized air inlet pipe is arranged on the top wall or the side wall of the closed box.

[0009] The technical solution of the present invention also includes: designing an airtightness detection method, using the device for changing the negative pressure airtightness test pressure difference, including the following detection steps: installing the workpiece to be measured on the base, starting the clamping cylinder to press the workpiece to be measured, filling high-pressure gas into the closed box through the pressurized air pipe, and the negative pressure tester extracts the gas inside the cavity of the workpiece to be measured through the air extraction pipe to perform airtightness detection on the workpiece to be measured. According to different usage requirements, different pressures (增压 or减压 (抽真空)) can be provided to the closed box, so that airtightness tests with different pressure differences can be obtained.

[0010] The advantages and beneficial effects of the present invention are as follows: Adding a closed box outside the traditional negative pressure test, setting the negative pressure test environment inside the closed box, and increasing the pressure to the closed box is equivalent to increasing the environmental pressure of the negative pressure test, so that the pressure difference between the inside and outside of the workpiece to be measured is increased, thereby achieving a negative pressure exceeding 1 atmospheric pressure.

[0011] According to different use requirements, different pressures can be provided to the sealed box (pressurization or decompression (vacuuming)), so that sealing tests with different pressure differences can be obtained.

[0012] This device does not need to apply a lot of pressure to the workpiece to ensure that the sealing surface is leak-proof. As long as a certain pressure difference can be formed, the sealing box can be pressurized to perform a sealing test, and as the pressure difference increases, it will become more and more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of a device for changing the pressure difference of a negative pressure air tightness test according to the present invention.

[0014] In the figure: 1. Negative pressure testing machine; 2. Exhaust pipe; 3. Enclosed box; 4. Pressurized air inlet pipe; 5. Clamping cylinder; 6. Workpiece to be tested; 7. Seal; 8. Base; 9. Inner cavity. DETAILED DESCRIPTION

[0015] The following embodiments are further described in conjunction with the accompanying drawings and examples. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0016] like Figure 1 As shown, the present invention is a device for changing the pressure differential of a negative pressure airtightness test, comprising a closed box 3, a clamping cylinder 5 for compressing a workpiece 6 to be tested, a negative pressure testing machine 1 to be installed outside the closed box 3, an exhaust pipe 2 to be connected to the negative pressure testing machine 1, the other end of which is located in the inner cavity 9 of the workpiece 6 to be tested, and a pressurized air inlet pipe 4 to be pressurized inside the closed box 3, the end of which is located inside the closed box 3 and is located outside the workpiece 6 to be tested. A base 8 is provided inside the closed box 3, and the workpiece 6 to be tested is connected to the base 8 via a seal 7; the base 8 and the clamping cylinder 5 are respectively fixedly connected to opposite inner walls of the closed box 3; the exhaust pipe 2 first passes through the closed box 3, then through the base 8, and is connected to the inner cavity 9 of the workpiece 6 to be tested. The base 8 is fixedly connected to the inner bottom wall of the closed box 3, and the clamping cylinder 5 is fixedly connected to the inner top wall of the closed box 3. The pressurized air inlet pipe 4 is installed on the side wall of the closed box 3. The top wall of the closed box 3 is provided with a through hole for the exhaust pipe 2 to pass through. The base 8 is provided with a channel for the exhaust pipe 2 to pass through. The two channel openings are both located on the upper surface of the base 8, one located in the inner cavity 9 of the workpiece 6 being measured, and the other located outside the workpiece 6 being measured.

[0017] A method for air tightness detection adopts the device for changing the pressure difference of negative pressure air tightness test, including the following detection steps: the workpiece 6 to be tested is mounted on the base 8, the clamping cylinder 5 is started to press the workpiece 6 to be tested, high-pressure gas is filled into the closed box 3 through the pressurized air pipe, and the negative pressure testing machine 1 extracts the gas in the cavity of the workpiece 6 to be tested through the exhaust pipe 2 to perform air tightness detection on the workpiece 6 to be tested.

[0018] By adding a closed box to the traditional negative pressure test environment, the negative pressure test environment is set within the sealed box. By adjusting the pressure inside the sealed box, airtightness tests with different pressure differentials can be obtained, greatly expanding the range of airtightness testing. In theory, this device can meet all positive and negative pressure tests and can increase the maximum pressure differential by approximately 1 atmosphere compared to positive pressure testing under normal conditions.

[0019] The negative pressure airtightness test pressure can be adjusted in real time according to requirements, significantly expanding the test range. Due to the characteristics of negative pressure testing, increasing the pressure differential between the inside and outside of the workpiece being tested is more conducive to sealing. Due to the uniformity of the ambient pressure, this device significantly improves the sealing performance of thin-walled and special-shaped workpieces. This device does not require applying high pressure to the workpiece to ensure a leak-proof sealing surface. As long as a certain pressure differential is established and the sealing chamber is pressurized, the sealing test can be performed. As the pressure differential increases, the test becomes increasingly stable.

[0020] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A device for changing the pressure difference of a negative pressure airtightness test, characterized in that: It includes a closed box, which is equipped with a clamping cylinder for pressing the workpiece to be measured, a negative pressure testing machine is provided outside the closed box, the negative pressure testing machine is connected to an exhaust pipe, and the other pipe end of the exhaust pipe is provided in the inner cavity of the workpiece to be measured. The closed box is also provided with a pressurized air inlet pipe for pressurizing the interior of the closed box, and the pipe end of the pressurized air inlet pipe located in the closed box is located outside the workpiece to be measured.

2. The device for changing the pressure difference of a negative pressure airtightness test according to claim 1, characterized in that: A base is provided in the closed box, and the workpiece to be measured is connected to the base through a seal; the base and the clamping cylinder are respectively fixedly connected to an opposite inner wall of the closed box; the exhaust pipe first passes through the closed box, then passes through the base and is connected to the inner cavity of the workpiece to be measured.

3. The device for changing the pressure difference of a negative pressure airtightness test according to claim 2, characterized in that: The base is fixedly connected to the inner bottom wall of the closed box, and the clamping cylinder is fixedly connected to the inner top wall of the closed box; the pressurized air inlet pipe is arranged on the side wall of the closed box.

4. The device for changing the pressure difference of a negative pressure airtightness test according to claim 3, characterized in that: The top wall of the closed box is provided with a through hole for the exhaust pipe to pass through, and the base is provided with a channel for the exhaust pipe to pass through. The two channel openings are both located on the upper surface of the base, one is located in the inner cavity of the workpiece to be measured, and the other is located outside the workpiece to be measured.

5. The device for changing the pressure difference of a negative pressure airtightness test according to claim 2, characterized in that: The base is fixedly connected to the inner top wall of the closed box, and the clamping cylinder is fixedly connected to the inner bottom wall of the closed box; the pressurized air inlet pipe is arranged on the side wall of the closed box; Or the base and the clamping cylinder are respectively fixedly connected to a pair of oppositely arranged inner side walls of the closed box, and the pressurized air inlet pipe is arranged on the top wall or the side wall of the closed box.

6. An airtightness testing method, using the device for changing the pressure difference of a negative pressure airtightness test as claimed in claim 4 or 5, characterized in that: The test process includes the following steps: placing the workpiece to be tested on the base, starting the clamping cylinder to compress the workpiece to be tested, filling the closed box with high-pressure gas through the pressurized air pipe, and using the negative pressure testing machine to extract the gas in the cavity of the workpiece to be tested through the exhaust pipe to perform an airtight test on the workpiece to be tested.

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