Semi-automatic helium mass spectrum leak detection system for vacuum cavity

Abstract

The utility model relates to a semi-automatic helium mass spectrometer leak detection system for a vacuum cavity. The semi-automatic helium mass spectrometer leak detection system comprises a leak detection device main body, an auxiliary leak detection part and a quick clamping device, wherein the leak detection device main body comprises a general test platform and a helium mass spectrometer leak detector; a bulge is arranged in the middle of the general test platform, a polyurethane gasket is arranged on the upper surface of the bulge for placing a to-be-detected workpiece, an L-shaped bracket is arranged on the outer side, a vertical section of the bracket is arranged close to the edge of the general test platform, and the bracket is higher than the to-be-detected workpiece after being mounted on the general test platform; the lower end of the quick-clamping device is detachably connected with the upper surface of the support, the head of the quick-clamping device is in threaded connection with a connecting rod, the tail of the quick-clamping device is provided with a pressing handle, the lower end of the connecting rod is provided with a detachably-connected cylindrical connecting block, and the lower surface of the connecting block is bonded with a pressure sensor which is electrically connected with a display unit; the auxiliary leak detection component comprises a helium spray gun and a plasma fan.

Description

Technical Field

[0001] The utility model relates to the technical field of helium leak detection, in particular to a semi-automatic helium mass spectrometry leak detection system for a vacuum chamber. Background Technique

[0002] In the fields of cryogenic superconductivity and accelerators, many devices and tests need to operate under ultra-high vacuum conditions (vacuum degree lower than 1x10 -8 Pa), and a specified vacuum degree needs to be achieved inside the vacuum chamber, which poses very high requirements for the leakage rate of the vacuum chamber. Generally, the leakage rate of the vacuum chamber used in the fields of cryogenic superconductivity and accelerators needs to be lower than 1x10 -11 Pa·m 3 / s. Traditional testing methods are difficult to test this index of the vacuum chamber, and helium mass spectrometry leak detection is required.

[0003] The helium mass spectrometry leak detection method utilizes the helium partial pressure measurement principle of a helium mass spectrometry leak detector to measure the helium leakage amount of the product to be detected. When there is a leak hole on the sealing surface of the product to be detected, the leak detection gas helium and other component gases will leak out from the leak hole. After the leaked gas enters the helium mass spectrometry leak detector, due to the selective recognition ability of the helium mass spectrometry leak detector, only the helium partial pressure signal value in the gas is given, thereby obtaining a leakage conclusion.

[0004] The helium mass spectrometry leak detection method can be divided into two types: the suction gun method and the helium spraying method.

[0005] (1) Suction gun method: The suction gun is connected to the helium mass spectrometry leak detector. After the product to be detected is evacuated and filled with helium at a pressure higher than atmospheric pressure, the suction nozzle of the suction gun is moved at a certain speed point by point along the suspicious leak gaps on the outer surface of the product to be detected for sucking. If there is a leak hole, the internal helium leaks through the leak hole and is sucked into the suction nozzle together with the surrounding air, and then enters the mass spectrometry chamber of the helium mass spectrometry leak detector, thereby generating an output indication of air leakage.

[0006] (2) Helium spraying method: Start the helium mass spectrometry leak detector and connect it to the product to be detected. The helium mass spectrometry leak detector evacuates the inside of the product to be detected. At this time, helium is sprayed on each position outside the product to be detected. When there is a leak at the sprayed position, helium will enter the vacuum sealing chamber of the product to be detected from the leak point, and then be sucked into the helium mass spectrometry leak detector and thus be detected.

[0007] The detection sensitivity of the suction gun method is relatively low, the uncertainty of the detection result is large, it is also greatly affected by the measurement environmental conditions, and it is inefficient to evacuate and refill helium for each product to be detected, and it is not suitable for batch operation; the detection sensitivity of the helium spraying method is high, it can detect the leak rate at any working pressure, and reflects the true leakage state of the product to be detected. Therefore, the most commonly used method for helium mass spectrometry leak detection of the vacuum chamber in the fields of cryogenic superconductivity and accelerators is the helium spraying method.

[0008] With the continuous development of the cryogenic superconductivity and accelerator fields, the vacuum chamber is evolving towards a higher sealing level, posing higher requirements for the accuracy, efficiency, and reliability of testing. For the vacuum chambers in the cryogenic superconductivity and accelerator fields, there are many problems in the helium spraying method during the use of a helium mass spectrometer leak detector:

[0009] (1) During the helium mass spectrometry leak detection process, it is necessary to connect the interface of the vacuum chamber under test to the helium mass spectrometer leak detector. Usually, the connection method using a sealed copper gasket is adopted. However, since it requires a specific knife-edge flange as the connection medium, it will cause an increase in the cost of the vacuum chamber and waste of disposable sealed copper gaskets. Moreover, multiple bolts need to be fixed during the connection process, reducing the testing efficiency; to avoid waste of disposable copper gaskets, the industry also uses the method of silicone rubber and fluororubber contact sealing for helium mass spectrometry leak detection of vacuum chambers. However, due to the low sealing level of silicone rubber (1x10 -8 Pa·m 3 / s), and the high hardness of fluororubber, it is difficult to obtain accurate test results quickly; Sealing silicone grease / vacuum mud sealing: This connection method uses sealing silicone grease / vacuum mud to connect the test interface of the vacuum chamber to the helium mass spectrometer leak detector. Although the presence of sealing silicone grease / vacuum mud can obtain accurate test results, removing the sealing silicone grease / vacuum mud on the surface of the vacuum chamber after testing requires a large amount of time, which is not conducive to batch operation and efficiency improvement.

[0010] (2) The main purpose of the airtightness test of the vacuum chamber is to find the leak point and perform subsequent remedial operations on the leak point. However, due to the extremely fast diffusion rate of helium in the air, it is difficult to control the single gas output of the existing air gun, and it is very difficult to determine the leakage location of the vacuum chamber through the test results.

[0011] (3) The products of vacuum chambers are generally very precise, but most of the current helium mass spectrometry leak detection methods are manual operations, and it is very easy to damage the products due to human errors during the testing process. Summary of the Invention

[0012] To solve the technical problems existing in the above-mentioned background technology, the present invention provides a semi-automatic helium mass spectrometry leak detection system for vacuum chambers.

[0013] A semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, comprising a main body of the leak detection device, an auxiliary leak detection component and a quick-clamping device. The main body of the leak detection device includes a general test platform and a helium mass spectrometry leak detector. A protrusion is provided in the middle of the general test platform, and a gasket is provided on the upper surface of the protrusion for placing the workpiece to be leak-detected. An L-shaped bracket is provided on the outside. The vertical section of the bracket is close to the edge of the general test platform, and the height of the bracket is greater than the height of the workpiece to be leak-detected after it is installed on the general test platform. The lower end of the quick-clamping device is detachably connected to the upper surface of the bracket. The head of the quick-clamping device is threadedly connected to a connecting rod, and a pressing handle is provided at the tail. A detachable cylindrical connecting block is provided at the lower end of the connecting rod. A pressure sensor is adhesively bonded to the lower surface of the connecting block, and the pressure sensor is electrically connected to a display unit. The auxiliary leak detection component includes a helium spray gun and a plasma fan.

[0014] Preferably, a gasket is provided on the upper part of the boss for placing the workpiece to be leak-detected, and the gasket material is polyurethane.

[0015] When the system is in the working state, the axes of the connecting rod, the connecting block and the pressure sensor coincide.

[0016] The connecting rod is a cylindrical threaded rod, and the angle between the axis of the connecting rod and the axis of the general test platform is within 0-5°.

[0017] The axis of the connecting rod coincides with the axis of the general test platform.

[0018] Further, the pressure sensor is a cylindrical pressure sensor with an I-shaped cross-section.

[0019] The lower surface area of the pressure sensor is more than twice the upper surface area of the workpiece to be leak-detected. When the system is in the working state, for the case where the axis of the quick-clamping device does not align with the axis of the boss after it falls, a certain tolerance space is provided, so that the workpiece to be leak-detected must be under the pressure sensor and is evenly stressed.

[0020] An opening-downward groove is provided at the lower end of the connecting block, and a through hole is provided in the middle. Threads are provided inside the hole for detachable connection with the connecting rod.

[0021] The vertical cross-section of the groove is an isosceles trapezoid with the upper base smaller than the lower base, and the height of the groove is less than 1 / 3 of the height of the connecting block.

[0022] Further, the upper surface area of the groove is the same as the upper surface area of the pressure sensor. The trapezoidal cross-section groove can guide the bonding of the pressure sensor, facilitate the determination of the position of the pressure sensor, and the groove can better control the range of the adhesive material when bonding the pressure sensor, limiting the glue only inside the groove of the connecting block and preventing glue overflow.

[0023] Preferably, a plurality of small holes opening downward can also be designed on the upper surface of the groove, and glue is preset in the small holes.

[0024] The upper surface of the horizontal section of the bracket is flush with the upper surface of the protrusion on the general test platform.

[0025] The helium spray gun is divided into a spray gun body and a barometer, and the barometer is fixedly connected to the upper part of the spray gun body.

[0026] Beneficial effects of a semi-automatic helium mass spectrometry leak detection system for a vacuum chamber:

[0027] (1) A boss is designed on the general test platform to facilitate the placement of gaskets for better sealing of the workpiece to be leak-detected. This sealing method has low cost, reliable test results, high test accuracy, and no need for product surface cleaning after testing.

[0028] (2) A pressure sensor is used to control the downward pressure during the test, avoiding the potential risk of product damage caused by artificial unstable factors, and fixing the downward pressure during the test makes the test results more credible and comparable.

[0029] (3) Helium is sprayed through the helium spray gun, and at the same time, the outlet pressure is controlled by the barometer, which can better judge the leakage position of the vacuum chamber and facilitate subsequent remedial treatment.

[0030] (4) The quick-clamping device simplifies the connection and downward pressure processes during the test, reduces the risk of helium contamination of the instrument, improves the test efficiency and test accuracy, and thus reduces the test cost.

[0031] (5) After the test is completed, the test table is purged by the plasma fan to avoid residual helium gas entering the helium mass spectrometry leak detector and causing helium contamination of the instrument. Description of the Drawings

[0032] In the drawings:

[0033] Figure 1 is a schematic diagram of the overall structure of a semi-automatic helium mass spectrometry leak detection system for a vacuum chamber;

[0034] Figure 2 is a partial cross-sectional view of the connection block structure;

[0035] Figure 3 is a schematic diagram of the overall structure of the helium spray gun.

[0036] The components represented by the reference numerals in the drawings are:

[0037] 1. Quick-clamping device; 101. Connecting rod; 2. Bracket; 3. Connecting block; 301. Through hole; 302. Groove; 4. Pressure sensor; 5. General test platform; 6. Workpiece to be leak-detected; 7. Helium mass spectrometry leak detector; 8. Plasma fan; 9. Helium spray gun; 901. Spray gun body; 902. Barometer. Detailed Embodiments

[0038] The technical solution of the utility model is as follows:

[0039] See Figure 1 , a semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, including a leak detection device main body, an auxiliary leak detection component and a quick clamp device 1. The leak detection device main body includes a general test platform 5 and a helium mass spectrometry leak detector 7; a protrusion is provided in the middle of the general test platform 5, and a gasket 10 is provided on the upper surface of the protrusion for placing the workpiece 6 to be leak detected. An L-shaped bracket 2 is provided on the outside. The vertical section of the bracket 2 is close to the edge of the general test platform 5, and the height of the bracket 2 is greater than the height of the workpiece 6 to be leak detected after being installed on the general test platform 5; the lower end of the quick clamp device 1 is detachably connected to the upper surface of the bracket 2. The head of the quick clamp device 1 is threadedly connected to a connecting rod 101, and a pressing handle is provided at the tail. A detachable cylindrical connecting block 3 is provided at the lower end of the connecting rod 101, and a pressure sensor 4 is bonded to the lower surface of the connecting block 3. The pressure sensor 4 is electrically connected to a display unit; the auxiliary leak detection component includes a helium spray gun 9 and a plasma fan 8.

[0040] Preferably, the leak detection rate of the helium mass spectrometry leak detector 7 is 5×10 -13 Pa·m 3 / s or less. A gasket 10 is provided on the upper surface of the convex platform for placing the workpiece 6 to be leak detected. The material of the gasket 10 is polyurethane, which has good sealing performance compared with the traditional gasket 10 material, simple process, low cost, and is convenient to operate during use.

[0041] As a further preference, the general test platform 5 and the helium mass spectrometry leak detector 7 are detachably connected through a KF25 interface.

[0042] When the system is in a working state, the axes of the connecting rod 101, the connecting block 3, and the pressure sensor 4 coincide.

[0043] The connecting rod 101 is a cylindrical threaded rod, and the angle between the axis of the connecting rod 101 and the axis of the general test platform 5 is 0-5°.

[0044] The axis of the connecting rod 101 coincides with the axis of the general test platform 5.

[0045] Further, the pressure sensor 4 is a cylindrical pressure sensor 4 with an I-shaped cross-section, and the pressure range is 0-50 kg.

[0046] The lower surface area of the pressure sensor 4 is more than twice the upper surface area of the workpiece 6 to be leak detected. When the system is in a working state, for the case where the axis of the quick clamp device 1 does not align with the axis of the convex platform after falling, a certain tolerance space is provided, so that the workpiece 6 to be leak detected must be under the pressure sensor 4 and is uniformly stressed.

[0047] An opening downward groove 302 is opened at the lower end of the connecting block 3, and a through hole 301 is opened in the middle, as Figure 2, a thread is provided inside the hole for detachable connection with the connecting rod 101.

[0048] The vertical cross-section of the groove 302 is an isosceles trapezoid with the upper base smaller than the lower base, and the height of the groove 302 is less than 1 / 3 of the height of the connecting block 3.

[0049] Furthermore, the upper surface area of the groove 302 is the same as the upper surface area of the pressure sensor 4. The trapezoidal cross-section groove 302 can guide the bonding of the pressure sensor 4, facilitating the determination of the position of the pressure sensor 4. And when bonding the pressure sensor 4, the groove 302 can better control the range of the bonding glue material, limiting the glue only inside the groove 302 of the connecting block 3 without glue overflow.

[0050] Preferably, multiple small holes with openings downward can also be designed on the upper surface of the groove 302, and glue is preset in the small holes.

[0051] The upper surface of the horizontal section of the bracket 2 is flush with the upper surface of the protrusion of the universal test platform 5. When the size of the workpiece 6 to be leak-tested is relatively large, the bracket 2 can bear weight on the upper surface, ensuring the stability of the quick-clamping device 1 and further enhancing the stability of the entire system.

[0052] The helium spray gun 9 is divided into a spray gun body 901 and a barometer 902. Refer to Figure 3 , and the barometer 902 is fixedly connected to the upper part of the spray gun body 901.

[0053] Usage scenario: The workpiece 6 to be leak-tested in this embodiment is an N-type feedthrough product with a vacuum chamber diameter of 25 mm. The position to be detected is the weld, and the airtightness requirement is 1×10 -11 Pa·m 3 / s.

[0054] First, connect the kf25 interface of the universal test platform 5 with the kf25 interface of the helium mass spectrometer leak detector 7. Secondly, place the polyurethane gasket on the universal test platform 5, and then place the workpiece 6 to be leak-tested on the polyurethane gasket. The inner holes of the above structures need to be interconnected to form a closed cavity; bond the quick-clamping device 1 and the pressure sensor 4, and then place the pressure sensor 4 on the workpiece 6 to be leak-tested, and set the pressure value of the pressure sensor 4 to 25 kg.

[0055] Press the pressing handle at the tail of the quick-clamping device 1 downward. After the value displayed on the display unit electrically connected to the pressure sensor 4 reaches the preset value of 25 kg, manually start the helium mass spectrometer leak detector 7 to start pumping air. When the value reaches the preset standard value of 1×10 -11 Pa·m 3After it stabilizes at / s, set the outlet pressure of the helium spray gun 9 to 0.03 MPa through the barometer 902 of the helium spray gun 9, and slowly spray a circle around the weld of the workpiece 6 to be leak-tested. Judge whether there is leakage at this weld from the numbers displayed on the helium mass spectrometer leak detector 7;

[0056] If during the process of the helium spray gun 9 spraying along the weld, when reaching a certain place, the numbers displayed on the helium mass spectrometer leak detector 7 fluctuate up and down, it indicates that there is a leakage point here and subsequent remedial treatment is required;

[0057] After the test is completed, turn on the plasma fan 8 and blow air on the surface and around the workpiece 6 to be leak-tested for 10 - 20 seconds to disperse the helium in the air, so as to prevent the residual helium from being pumped into the helium mass spectrometer leak detector 7, thereby causing helium pollution; finally, manually turn off the helium mass spectrometer leak detector 7. After the helium mass spectrometer leak detector 7 stops pumping air, apply pressure upward on the pressing handle at the tail of the quick-clamping device 1 to release the clamping state of the workpiece 6 to be leak-tested, and complete the helium mass spectrometry leak detection work.

[0058] Beneficial effects of a semi-automatic helium mass spectrometry leak detection system for a vacuum chamber:

[0059] (1) Design a boss on the general test platform 5 to facilitate placing the gasket 10 for better sealing of the workpiece 6 to be leak-tested. This sealing method has low cost, reliable test results, high test accuracy, and no need for product surface cleaning after testing.

[0060] (2) Use the pressure sensor 4 to control the downward pressure during the test process, avoiding the potential risk of product damage caused by artificial unstable factors, and fixing the downward pressure during the test makes the test results more credible and comparable.

[0061] (3) Spray helium through the helium spray gun 9, and at the same time control the outlet pressure through the barometer 902, which can better judge the leakage position of the vacuum chamber and facilitate subsequent remedial treatment.

[0062] (4) Simplify the connection and downward pressure processes during the test through the quick-clamping device 1, reduce the risk of helium pollution of the instrument, improve the test efficiency and test accuracy, and thus reduce the test cost.

[0063] (5) After the test is completed, blow the test table through the plasma fan to avoid residual helium entering the helium mass spectrometer leak detector 7 and causing helium pollution of the instrument.

Claims

1. A semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, comprising a main body of the leak detection device, an auxiliary leak detection component, and a quick clamp device (1). The main body of the leak detection device includes a general test platform (5) and a helium mass spectrometry leak detector (7); It is characterized in that a protrusion is provided in the middle of the general test platform (5), and a gasket (10) is provided on the upper surface of the protrusion for placing the workpiece to be leak-detected (6). An L-shaped bracket (2) is provided on the outside. The vertical section of the bracket (2) is arranged close to the edge of the general test platform (5), and the height of the bracket (2) is greater than the height of the workpiece to be leak-detected (6) after being installed on the general test platform (5); the lower end of the quick clamp device (1) is detachably connected to the upper surface of the bracket (2). The head of the quick clamp device (1) is threadedly connected to a connecting rod (101), and a pressing handle is provided at the tail. A detachable cylindrical connecting block (3) is provided at the lower end of the connecting rod (101), and a pressure sensor (4) is adhesively bonded to the lower surface of the connecting block (3). The pressure sensor is electrically connected to a display unit; the auxiliary leak detection component includes a helium spray gun (9) and a plasma fan (8).

2. The semi-automatic helium mass spectrometry leak detection system for a vacuum chamber according to claim 1, wherein, The area of the lower surface of the pressure sensor (4) is more than twice the area of the upper surface of the workpiece to be leak-detected (6).

3. A semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, characterized in that, An opening-downward groove (302) is provided at the lower end of the connecting block (3), and a through hole (301) is provided in the middle.

4. A semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, characterized in that, Internal threads are provided in the through hole (301) for detachably connecting with the connecting rod (101).

5. A semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, characterized in that, The vertical section of the groove (302) is an isosceles trapezoid with the upper base smaller than the lower base, and the height of the groove (302) is less than 1 / 3 of the height of the connecting block (3).

6. The semi-automatic helium mass spectrometry leak detection system for a vacuum chamber according to claim 1, wherein The upper surface of the horizontal section of the bracket (2) is flush with the upper surface of the protrusion of the general test platform (5).

7. A semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, characterized in that, When the system is in the working state, the axes of the connecting rod (101), the connecting block (3), and the pressure sensor (4) coincide.

8. A semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, characterized in that, The material of the gasket (10) is polyurethane.

9. A semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, characterized in that, When the system is in the working state, the axis of the connecting rod (101) coincides with the axis of the general test platform (5).

10. A semi-automatic helium mass spectrometry leak detection system for a vacuum chamber, characterized in that, The helium spray gun (9) is divided into a spray gun main body (901) and a barometer (902), and the barometer (902) is fixedly connected to the upper part of the spray gun main body (901).

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