Fabrication method of large-size arc-shaped ultra-high vacuum cavity

Abstract

This invention provides a method for fabricating a large-size arc-shaped ultra-high vacuum cavity, belonging to the field of vacuum cavity processing. The method includes: removing hydrogen molecules from the raw materials of the ultra-high vacuum cavity using an ultra-high vacuum furnace; sequentially machining a vacuum base plate, a vacuum top cover plate, a vacuum inner arc side plate, and a vacuum outer arc side plate using a CNC machine tool; placing the vacuum base plate, vacuum top cover plate, vacuum inner arc side plate, and vacuum outer arc side plate sequentially on a welding fixture, fixing them using argon arc welding, and then performing external welding using laser welding to form the ultra-high vacuum cavity; using helium mass spectrometry to detect leaks in the welds of the ultra-high vacuum cavity; and using a laser tracker to measure the dimensions of the ultra-high vacuum cavity, thus completing the fabrication of the arc-shaped ultra-high vacuum cavity. The aim is to solve the problem of easy leakage in the fabrication of arc-shaped ultra-high vacuum cavities in existing technologies. The achieved technical effect is to avoid the occurrence of gas entrapment in the ultra-high vacuum cavity while reducing the probability of leakage.

Description

Technical Field

[0001] This invention relates to the field of vacuum cavity processing technology, and in particular to a method for manufacturing a large-size arc-shaped ultra-high vacuum cavity. Background Technology

[0002] The completion of the new generation of high-intensity heavy-ion accelerators provides strong support for research in cutting-edge fields such as nuclear physics and materials science, capable of providing pulsed heavy-ion beams up to 4.25 GeV / u. To ensure this performance, the high-intensity heavy-ion accelerator imposes stringent requirements on the design of each system, among which the high-precision ring spectrometer, as a key component, bears the heavy responsibility of ion beam control and experimentation.

[0003] The high-precision ring spectrometer consists of a variety of magnets and an electronic cooling system, a dual-time-of-flight spectrometer, and other large experimental terminals. To meet the ultra-high vacuum environment requirements of different experimental terminals, its ultra-high vacuum system is designed to achieve a vacuum level better than 1×10⁻⁶. -9 Pa. The high-precision ring spectrometer's electrode high-vacuum chamber is a large-sized arc-shaped structure with a thickness of over 7mm. It is usually made using a four-plate splicing and welding process. The conventional welding process uses argon arc welding to form two inner welds, which are then combined with two outer welds to complete the process.

[0004] However, traditional manufacturing methods have significant problems. On the one hand, due to the excessive thickness of the sheet metal, the outer weld seam is difficult to penetrate, resulting in gaps between the outer weld seam and the interior, causing gas entrapment. Gas molecules collide within these gaps, preventing the ultra-high vacuum system from achieving 1×10⁻⁶. -9 The design parameters of Pa affect the stability of the ion beam and the accuracy of experiments. On the other hand, the manufacturing process cannot effectively perform ultra-high vacuum leak detection on the two internal welds. If a leak occurs, subsequent repair welding is difficult to implement due to the complex structure and limited space, which increases maintenance costs and research time costs, and seriously restricts the overall performance of the high-current heavy ion accelerator. Summary of the Invention

[0005] This invention provides a method for manufacturing a large-size arc-shaped ultra-high vacuum cavity, which solves the defects of existing ultra-high vacuum cavity manufacturing technology, such as air entrapment and easy leakage. This method avoids air entrapment in the ultra-high vacuum cavity and effectively completes ultra-high vacuum leak detection of all welds in one go, thereby reducing the probability of leakage of the ultra-high vacuum cavity.

[0006] This invention provides a method for fabricating a large-size arc-shaped ultra-high vacuum cavity, comprising:

[0007] Hydrogen removal: Using an ultra-high vacuum furnace to remove hydrogen molecules from the raw materials in the ultra-high vacuum chamber;

[0008] Parts machining: The vacuum base plate, vacuum top cover plate, vacuum inner arc side plate and vacuum outer arc side plate are machined sequentially using CNC machine tools;

[0009] Laser welding: The vacuum base plate, vacuum top cover plate, vacuum inner arc side plate and vacuum outer arc side plate are placed on the welding fixture in sequence, fixed by argon arc welding, and then laser welding is used to perform external welding to form an ultra-high vacuum cavity.

[0010] Ultra-high vacuum leak detection: using helium mass spectrometry to detect leaks in the welds of ultra-high vacuum chambers;

[0011] Dimensional inspection: The dimensions of the ultra-high vacuum cavity were measured using a laser tracker, and the arc-shaped ultra-high vacuum cavity was completed.

[0012] In addition, the method for fabricating a large-size arc-shaped ultra-high vacuum cavity according to the present invention may also have the following additional technical features:

[0013] In some embodiments of the present invention, it further includes:

[0014] Before performing ultra-high vacuum leak detection, the ultra-high vacuum flange is welded to the end of the ultra-high vacuum chamber using argon arc welding.

[0015] In some embodiments of the present invention, it further includes:

[0016] Before performing ultra-high vacuum leak detection, the ultra-high vacuum cavity after laser welding is cleaned under ultra-high vacuum.

[0017] In some embodiments of the present invention, the ultra-high vacuum cavity after laser welding is subjected to ultra-high vacuum cleaning, including:

[0018] A rough wash is performed to remove visible dirt;

[0019] To remove oil, ultrasonically clean in a weakly acidic aqueous solution at 65℃ for 15 minutes.

[0020] Place in a 65℃ weakly alkaline solution and ultrasonically clean for 15 minutes to neutralize; rinse repeatedly with running deionized water.

[0021] High-purity nitrogen gas was used to dry the water stains.

[0022] In some embodiments of the present invention, the welding fixture includes:

[0023] The base plate positioning fixture has a waist-shaped groove and a limiting groove, and the limiting groove has a waist-shaped groove on both sides.

[0024] The pressure plate is assembled on the base plate positioning fixture via the mold assembly.

[0025] In some embodiments of the present invention, the mold assembly includes:

[0026] The upright is positioned between the pressure plate and the base plate positioning fixture.

[0027] The column has a screw at each end, one of which is connected to the pressure plate and the other is connected to the base plate positioning fixture.

[0028] In some embodiments of the present invention, the welding fixture further includes:

[0029] Positioning pins are inserted into the positioning fixture on the base plate during operation.

[0030] In some embodiments of the present invention, it further includes:

[0031] In the laser welding process, before using argon arc welding for spot welding and fixation, a laser tracker and vernier calipers are used to conduct a preliminary measurement of the dimensions of the ultra-high vacuum cavity spliced ​​on the welding fixture to confirm that the dimensions meet the requirements.

[0032] In some embodiments of the present invention, after fixing by argon arc welding, the method further includes:

[0033] The welding area is wiped with alcohol to remove surface oil and oxide layer, and then laser welding is used to perform external welding to form an ultra-high vacuum cavity.

[0034] In some embodiments of the present invention, forming an ultra-high vacuum cavity by using laser welding includes:

[0035] Configure the parameters of the laser welder;

[0036] Turn on the laser pointer, adjust the robot to align with the center of the welding position, perform a test weld using a stainless steel plate, and observe whether there are defects such as incomplete penetration, porosity, and hot cracks in the weld after the test weld.

[0037] Determine the final welding parameters;

[0038] A high-vacuum cavity is formed by external welding using a laser welder.

[0039] In summary, this application includes the following beneficial technical effects: This ultra-high vacuum cavity is formed by sequentially placing the vacuum base plate, vacuum top cover plate, vacuum inner arc side plate, and vacuum outer arc side plate on a welding fixture, fixing them with argon arc welding, and then performing external welding with laser welding. Combined with the hydrogen removal setting, this ensures that all external welds are fully penetrated, avoiding the occurrence of gas entrapment in the ultra-high vacuum cavity. At the same time, since all welds are externally welded, all welds can be effectively and simultaneously inspected for leaks in ultra-high vacuum, reducing the probability of leakage in the ultra-high vacuum cavity. Furthermore, even if a leak occurs later, only the external welds need to be repaired, with no restrictions on operating space, reducing maintenance costs and research time costs, and ensuring the overall performance of the high-intensity heavy ion accelerator. Attached Figure Description

[0040] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0041] Figure 1 A flowchart illustrating a method for fabricating a large-size arc-shaped ultra-high vacuum cavity according to some embodiments of the present invention is shown.

[0042] Figure 2 A perspective view of a welding fixture for a method of fabricating a large-size arc-shaped ultra-high vacuum cavity according to some embodiments of the present invention is shown schematically.

[0043] Figure 3 A perspective view of the base plate positioning fixture 1 of the method for fabricating a large-size arc-shaped ultra-high vacuum cavity according to some embodiments of the present invention is shown schematically.

[0044] Figure 4 A perspective view of a mold assembly 6 for a method of fabricating a large-size arc-shaped ultra-high vacuum cavity according to some embodiments of the present invention is shown schematically.

[0045] Figure 5 A partially enlarged view is shown schematically of an ultra-high vacuum cavity placed in part A of a welding fixture, according to a method for fabricating a large-size arc-shaped ultra-high vacuum cavity according to some embodiments of the present invention.

[0046] Figure 6 A perspective view of an ultra-high vacuum cavity fabricated by a method for fabricating a large-size arc-shaped ultra-high vacuum cavity according to some embodiments of the present invention is shown schematically.

[0047] Figure label:

[0048] 1. Base plate positioning fixture; 2. Vacuum base plate; 3. Vacuum top cover plate; 4. Vacuum inner arc side plate; 5. Vacuum outer arc side plate; 6. Mold assembly; 7. Pressure plate; 8. Nut; 9. Positioning pin; 10. Positioning hole; 11. Threaded hole; 12. Waist-shaped groove; 13. Column; 14. Screw; 15. Ultra-high vacuum flange; 16. Limiting groove. Detailed Implementation

[0049] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0050] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “” used herein may also indicate the inclusion of the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated, unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0051] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0052] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may also be rotated 90 degrees or in other orientations, and the spatial relative descriptors used in the text will be interpreted accordingly.

[0053] The vacuum chamber of the diode has a rectangular cross-section of 342 mm × 92 mm or greater, a wall thickness of 7 mm or more, a deflection angle of 18°, a deflection radius of 9500 mm or greater, and a total length of 3.6 m or more. Typically, this large-sized arc-shaped vacuum chamber is assembled from four plates. First, the base plate and the inner and outer arc-shaped side plates are joined together, and the two internal welds are completed using argon arc welding. Then, the top plate is placed on top, and the remaining two welds are completed from the outside. However, due to the excessive thickness of the plates, the outer welds are difficult to penetrate, resulting in gaps between the outer welds and the interior, causing gas entrapment. Gas molecules collide within these gaps, preventing the ultra-high vacuum system from achieving 1 × 10⁻⁶ vacuum. -9 The design parameters of Pa affect the stability of the ion beam and the accuracy of experiments. On the other hand, the manufacturing process cannot effectively perform ultra-high vacuum leak detection on the two internal welds. If a leak occurs, subsequent repair welding is difficult to implement due to the complex structure and limited space, which increases maintenance costs and research time costs, and seriously restricts the overall performance of the high-current heavy ion accelerator.

[0054] In addition, it should be noted that the definition of ultra-high vacuum refers to a gas pressure below 10... -7 A vacuum environment of Pa; large size refers to a horizontal or vertical dimension that is usually over 1 meter.

[0055] like Figures 1 to 6 As shown, according to an embodiment of the first aspect of the present invention, a method for fabricating a large-size arc-shaped ultra-high vacuum cavity is proposed, comprising:

[0056] Hydrogen removal: Using an ultra-high vacuum furnace to remove hydrogen molecules from the raw materials in the ultra-high vacuum chamber;

[0057] Parts machining: Vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4 and vacuum outer arc side plate 5 are machined sequentially using CNC machine tools;

[0058] Laser welding: Vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4 and vacuum outer arc side plate 5 are placed on the welding fixture in sequence, fixed by argon arc welding, and then laser welding is used to perform external welding to form an ultra-high vacuum cavity.

[0059] Ultra-high vacuum leak detection: using helium mass spectrometry to detect leaks in the welds of ultra-high vacuum chambers;

[0060] Dimensional inspection: The dimensions of the ultra-high vacuum cavity were measured using a laser tracker, and the arc-shaped ultra-high vacuum cavity was completed.

[0061] In the above embodiments, it should be noted that removing hydrogen molecules from the raw materials of the ultra-high vacuum chamber using an ultra-high vacuum furnace specifically includes placing the raw materials 316L and 316LN to be dehydrogenated into the ultra-high vacuum furnace after ultra-high vacuum cleaning, and then heating them in an ultra-high vacuum environment with a vacuum level better than 1×10⁻⁶. -3 Under the conditions of Pa, the hydrogen removal temperature is 900~950℃, and the hydrogen removal time is 1h / mm wall thickness. High-temperature hydrogen removal is carried out. During the cooling process, the temperature range of 900-600℃ must be avoided for less than 15 minutes to prevent the formation of carbide precipitation.

[0062] The ultra-high vacuum cleaning process includes: rough cleaning to remove visible dirt; ultrasonic cleaning for 15 minutes in a 65°C weakly acidic aqueous solution to remove oil; then ultrasonic cleaning for 15 minutes in a 65°C weakly alkaline solution to neutralize; repeated rinsing with flowing deionized water until no foam remains; and drying with high-purity nitrogen.

[0063] High-purity nitrogen refers to nitrogen gas with a purity between 99.99% and 99.9999%.

[0064] The process of machining the vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4, and vacuum outer arc side plate 5 sequentially using a CNC machine tool includes the following steps: First, import the drawings of the vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4, and vacuum outer arc side plate 5 into the CNC machine tool. Then, fix the 7mm thick 316L stainless steel plate after hydrogen removal onto the CNC machine tool. Select molybdenum wire as the electrode wire material, with a diameter of 0.1~0.3mm, a discharge power of 100~120A, a pulse width of 4~8μs, an impact voltage of 90~110V, and a wire feed rate of 0.5~5m / s.

[0065] Then, the vacuum inner arc side plate 4 and the vacuum outer arc side plate 5 are processed using a CNC bending machine or a CNC circular arc bending machine according to parameters such as deflection angle and radius.

[0066] After all parts have been processed, a laser tracker is used to accurately measure the length, width, radius, angle, and other dimensions of the vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4, and vacuum outer arc side plate 5.

[0067] Furthermore, the ultra-high vacuum flange 15 is machined using a CNC machining center according to national standards. The material of the ultra-high vacuum flange 15 is 316LN.

[0068] The process of placing the vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4, and vacuum outer arc side plate 5 sequentially on the welding fixture includes: first, fixing the vacuum base plate 2 on the welding fixture; then, splicing the vacuum inner arc side plate 4 and vacuum outer arc side plate 5 on both sides of the vacuum base plate 2; then, splicing the vacuum top cover plate 3 on the vacuum inner arc side plate 4 and vacuum outer arc side plate 5; and finally, using the welding fixture to fix and form the welding positions of the four outer weld seams.

[0069] The method of fixing by argon arc welding is to use an argon arc welding machine to spot weld and fix the welding positions of the four outer weld seams.

[0070] The method of forming an ultra-high vacuum cavity by using laser welding for external welding includes using a laser welder to fully weld the welding positions of the four external weld seams. After welding, all weld seams are ground and electrochemically polished. At the same time, areas with large deformations are mechanically corrected using a hydraulic straightening machine.

[0071] The use of a laser tracker to measure the dimensions of the ultra-high vacuum cavity specifically includes measuring the width, height, deflection angle, deflection radius, flatness, and perpendicularity of the flange face to the axis of the welded and leak-tested ultra-high vacuum cavity. Except for the angle requirement of ±0.1°, all other measurements should be within ±0.5mm.

[0072] The technical effects achieved by the above embodiments are as follows: This ultra-high vacuum cavity is formed by placing the vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4, and vacuum outer arc side plate 5 sequentially on a welding fixture, fixing them with argon arc welding, and then performing external welding with laser welding. Combined with the hydrogen removal setting, it can ensure that all external welds are fully penetrated, avoiding the phenomenon of gas entrapment in the ultra-high vacuum cavity. At the same time, since all are externally welded, all welds can be effectively inspected for leaks in ultra-high vacuum in one go, reducing the probability of leakage in the ultra-high vacuum cavity. In addition, even if a leak occurs later, only the external welds need to be repaired. The operating space is not restricted, reducing maintenance costs and research time costs, and ensuring the overall performance of the high-intensity heavy ion accelerator.

[0073] Optional, such as Figure 1 As shown, before performing ultra-high vacuum leak testing, the ultra-high vacuum flange 15 is welded to the end of the ultra-high vacuum chamber using argon arc welding.

[0074] In the above optional embodiments, it should be noted that an ultra-high vacuum flange 15 is welded to each end of the ultra-high vacuum cavity.

[0075] Leak detection of welds in ultra-high vacuum chambers using helium mass spectrometry includes checking for leaks at the location of the silver wire-sealed ultra-high vacuum flange 15 and all welds. If the leak rate is less than 1×10⁻⁶, the leak is considered to be within acceptable limits. -8 Pa·L·S -1 Then it is considered qualified.

[0076] The advantages of the above optional embodiments are as follows: using argon arc welding to weld the ultra-high vacuum flange 15 to the end of the ultra-high vacuum cavity can ensure reliable welding between the ultra-high vacuum flange 15 and the ultra-high vacuum cavity, and reduce welding costs. In this way, the combination of argon arc welding and laser welding is realized to maximize the sealing of the ultra-high vacuum cavity after welding, while ensuring the convenience of welding and controlling welding costs.

[0077] Optional, such as Figure 1 As shown, the ultra-high vacuum cavity after laser welding is cleaned under ultra-high vacuum before ultra-high vacuum leak detection.

[0078] In the above optional embodiments, it should be noted that after the ultra-high vacuum flange 15 is welded before ultra-high vacuum leak detection, the ultra-high vacuum chamber is cleaned under ultra-high vacuum.

[0079] After the dimensional inspection of the ultra-high vacuum chamber was completed, the chamber was validated. Equipped with a 400L sputtering ion pump and two titanium sublimation pumps, and held at 250℃ for 48 hours, the ultra-high vacuum chamber, constructed using 316L as the main body material and 316LN flanges processed by laser welding, achieved an ultimate ultra-high vacuum of 8 × 10⁻⁶. -10 Pa proves that this ultra-high vacuum chamber can avoid the occurrence of air entrapment, and at the same time can complete the ultra-high vacuum leak detection work in one go, avoiding a series of problems caused by subsequent leak repair.

[0080] The advantages of the above optional embodiments are as follows: by setting up ultra-high vacuum cleaning, debris and oil stains on the inner wall of the ultra-high vacuum chamber can be removed, reducing the pollution of the ultra-high vacuum chamber environment by debris and ensuring the ultra-high vacuum performance of the ultra-high vacuum chamber.

[0081] Optional, such as Figure 1 As shown, the ultra-high vacuum cavity after laser welding is cleaned under ultra-high vacuum conditions, including:

[0082] A rough wash is performed to remove visible dirt;

[0083] To remove oil, ultrasonically clean in a weakly acidic aqueous solution at 65℃ for 15 minutes.

[0084] Place in a 65℃ weakly alkaline solution and ultrasonically clean for 15 minutes to neutralize; rinse repeatedly with running deionized water.

[0085] High-purity nitrogen gas was used to dry the water stains.

[0086] In the above optional embodiments, it should be noted that high-purity nitrogen refers to nitrogen with a purity between 99.99% and 99.9999%.

[0087] The advantages of the above optional embodiments are as follows: Pre-cleaning quickly removes visible surface dirt, preventing large particles from affecting subsequent cleaning and the performance of the ultra-high vacuum chamber. Ultrasonic cleaning with a 65°C weakly acidic water-based solution utilizes the chemical reaction between acidic components and grease, along with the cavitation effect of high-frequency ultrasonic vibration, to efficiently remove oil stains, thoroughly cleaning the surface of the ultra-high vacuum chamber's inner wall and reducing the pollution of the ultra-high vacuum environment by residual oil. The weakly alkaline solution neutralization step effectively neutralizes residual acidic substances, preventing them from corroding the ultra-high vacuum chamber materials, while further removing residual impurities. Rinsing with flowing deionized water removes substances produced by the neutralization reaction and other residual impurities, reducing the amount of residual ions. Finally, high-purity nitrogen dries the water stains, preventing water vapor from forming and affecting the ultra-high vacuum level in the ultra-high vacuum environment. Through this series of cleaning processes, the impurity content inside the ultra-high vacuum chamber can be significantly reduced, the surface cleanliness of the ultra-high vacuum chamber can be improved, and the ultra-high vacuum performance of the ultra-high vacuum chamber can be effectively guaranteed.

[0088] Optional, such as Figures 2 to 6 As shown, the welding fixture includes a base plate positioning fixture 1, a mold assembly 6, and a pressure plate 7. The base plate positioning fixture 1 has a waist-shaped groove 12 and a limiting groove 16. The limiting groove 16 has waist-shaped grooves 12 on both sides. The pressure plate 7 is installed on the base plate positioning fixture 1 through the mold assembly 6.

[0089] In the above optional embodiments, it should be noted that each side of the limiting groove 16 of the vacuum base plate 2 is connected to a plurality of mold assemblies 6, and all the mold assemblies 6 are connected to the base plate positioning fixture 1 by bolts. The plurality of mold assemblies 6 on one side of the limiting groove 16 are arranged in a one-to-one correspondence with the plurality of mold assemblies 6 on the other side of the limiting groove 16. A pressure plate 7 is connected between each pair of corresponding mold assemblies 6, and each mold assembly 6 is elliptical in shape.

[0090] During operation, the vacuum base plate 2 is inserted into the limiting groove 16, and the two waist-shaped grooves 12 are located on both sides of the vacuum base plate 2. The vacuum inner arc side plate 4 and the vacuum outer arc side plate 5 are connected to the vacuum base plate 2 respectively. After the position is adjusted by the mold assembly 6, the vacuum top cover plate 3 is spliced ​​with the vacuum inner arc side plate 4 and the vacuum outer arc side plate 5. Then, the pressure plate 7 is pressed onto the vacuum top cover plate 3 and connected to the upper end of the mold assembly 6.

[0091] The machining method for the base plate positioning fixture 1 is as follows: first, the outer shape is machined by wire cutting, and then a large gantry milling machine is used for precision machining. The machining accuracy can be controlled within 0.2mm.

[0092] The advantages of the above optional embodiments are: the setting of the limiting groove 16 can effectively limit the vacuum base plate 2, and the setting of the waist-shaped groove 12 can leave a weld seam in the ultra-high vacuum cavity to facilitate subsequent spot welding.

[0093] Optional, such as Figures 2 to 6 As shown, the mold assembly 6 includes a column 13 and a screw 14. The column 13 is located between the pressure plate 7 and the base plate positioning fixture 1. A screw 14 is provided at each end of the column 13. One screw 14 is connected to the pressure plate 7, and the other screw 14 is connected to the base plate positioning fixture 1.

[0094] In the above optional embodiments, it should be noted that each mold assembly 6 includes a column 13 and two screws 14. The column 13 has an elliptical cross-sectional shape and is connected to the base plate positioning fixture 1 and the corresponding pressure plate 7 by the two screws 14 respectively.

[0095] The beneficial effects of the above optional embodiments are as follows: by using the elliptical arrangement of the columns 13, multiple columns 13 can be used together to firmly clamp the vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4, and vacuum outer arc side plate 5, ensuring the installation accuracy of the vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4, and vacuum outer arc side plate 5.

[0096] Optional, such as Figures 2 to 6 As shown, the welding fixture also includes a positioning pin 9, which is inserted into the base plate positioning fixture 1 during operation.

[0097] In the above optional embodiments, it should be noted that, specifically, the base plate positioning fixture 1 is also provided with a positioning hole 10 and a threaded hole 11, the positioning pin is inserted into the positioning hole 10, and the screw 14 is screwed into the threaded hole 11.

[0098] Both the vacuum inner arc side plate 4 and the vacuum outer arc side plate 5 are machined with a step 7mm deep and 1.5mm wide to accommodate the vacuum base plate 2 and the vacuum top cover plate 3.

[0099] The vacuum base plate 2, vacuum top cover plate 3, vacuum inner arc side plate 4, and vacuum outer arc side plate 5 are sequentially placed on the welding fixture. The vacuum base plate 2 is then fitted onto the positioning pin 9 and placed on the limiting groove 16 of the base plate positioning fixture 1, positioned between the two waist-shaped grooves 12. The vacuum inner arc side plate 4 and vacuum outer arc side plate 5 are then connected to the vacuum base plate 2 respectively. The vacuum top cover plate 3 is then spliced ​​with the vacuum inner arc side plate 4 and vacuum outer arc side plate 5. Finally, the elliptical assembly of multiple molds 6 is adjusted. The column 13, with the synergistic action of multiple columns 13 and multiple screws 14, adjusts the accuracy of the vacuum inner arc side plate 4 and the vacuum outer arc side plate 5. Then, the pressure plate 7 is installed on the screws 14 on the corresponding column 13 and fixed with washers and nuts 8 so that the vacuum top cover plate 3 and the vacuum inner arc side plate 4, as well as the vacuum top cover plate 3 and the vacuum outer arc side plate 5, are tightly fitted, so that the vacuum base plate 2, the vacuum top cover plate 3, the vacuum inner arc side plate 4 and the vacuum outer arc side plate 5 are placed on the welding fixture in sequence.

[0100] Before laser welding, the welding fixtures are processed.

[0101] The advantages of the above optional embodiments are: the positioning pin 9 can ensure the stability and firmness of the ultra-high vacuum cavity placed on the base plate positioning fixture 1.

[0102] Optional, such as Figure 1 As shown, in the laser welding process, before using argon arc welding for spot welding and fixation, a laser tracker and vernier calipers are used to initially measure the dimensions of the ultra-high vacuum cavity spliced ​​on the welding fixture to confirm that the dimensions meet the requirements.

[0103] In the above optional embodiments, it should be noted that a laser tracker and vernier calipers are used to perform a preliminary measurement of the dimensions of the ultra-high vacuum cavity spliced ​​on the welding fixture to confirm that the dimensions meet the requirements, including whether the angular accuracy of each component reaches ±0.1° and the cross-sectional dimension accuracy reaches ±0.5mm.

[0104] The advantages of the above-mentioned optional embodiments are as follows: Preliminary dimensional measurements using a laser tracker and vernier calipers before laser welding allow for precise control of the specifications of each part of the ultra-high vacuum chamber. This enables timely detection of splicing errors, avoiding rework due to dimensional discrepancies and improving welding efficiency. Furthermore, it ensures that the dimensions of the ultra-high vacuum chamber meet the requirements of a high-precision ring spectrometer, guaranteeing subsequent welding quality and achieving the required ultra-high vacuum performance standards, and reducing the risk of performance defects caused by dimensional issues.

[0105] Optional, such as Figure 1 As shown, after spot welding with argon arc welding, the process also includes wiping the welding position with alcohol to remove surface oil and oxide layer, and then using laser welding to perform external welding to form an ultra-high vacuum cavity.

[0106] In the above optional embodiments, it should be noted that the method of wiping the welded area with alcohol can be achieved by using a cotton swab or non-woven cloth dipped in alcohol to fully moisten the surface of the weld joint; wiping in a circular motion to dissolve grease and rosin residue. Stubborn stains can be gently brushed with a soft brush, or wiped repeatedly 2-3 times.

[0107] The advantages of the above optional embodiments are as follows: by wiping the welding position with alcohol to remove surface oil and oxide layer, the surface oil and oxide layer can be effectively removed, ensuring the smoothness and flatness of the laser welding surface and the extremely high vacuum degree, thus avoiding the occurrence of gas entrapment during the laser welding process.

[0108] Optional, such as Figure 1 As shown, the process of forming an ultra-high vacuum cavity using laser welding for external welding includes:

[0109] Configure the parameters of the laser welder;

[0110] Turn on the laser pointer, adjust the robot to align with the center of the welding position, and perform a test weld using a stainless steel plate. Observe whether there are defects such as incomplete penetration, porosity, and hot cracks in the weld after the test weld.

[0111] Determine the final welding parameters;

[0112] A high-vacuum cavity is formed by external welding using a laser welder.

[0113] In the above optional embodiments, it should be noted that using laser welding to perform external welding to form an ultra-high vacuum cavity specifically includes:

[0114] Set the parameters of the laser welder as follows: laser power 6~8KW, welding speed 0.8~2m / min, defocusing distance +2~+5mm, shielding gas argon, flow rate 15~30L / min.

[0115] Turn on the laser pointer, adjust the robot to align with the center of the welding position, and perform a test weld using a stainless steel plate. Observe whether there are defects such as incomplete penetration, porosity, and hot cracks in the weld after the test weld. Specifically, turn on the laser pointer, adjust the robot to align with the center of the weld corresponding to the welding position, with an error of less than 0.1mm, and perform a test weld using 7mm thick 316L stainless steel. Observe whether there are defects such as incomplete penetration, porosity, and hot cracks in the weld. When the weld surface is smooth without depressions, there is no undercut on both sides, and the weld is fully penetrated, determine the final welding parameters.

[0116] Then, wipe the welding position with alcohol to remove oil and oxide layer from the two weld seams of the vacuum cover plate 3. Import the 3D model of the ultra-high vacuum cavity, which is fixed by argon arc welding after being installed on the welding fixture, into the CNC machine tool control system. Along the arc weld seam generation path, avoid the position of the pressure plate 7. Set the clamping point of the fixture 5mm on both sides of each pressure plate 7 and the distance from the surface of the vacuum inner arc side plate 4 and the vacuum outer arc side plate 5 on the corresponding side of the ultra-high vacuum cavity is 15mm. After setting, the formal welding is carried out. Before welding, the shielding gas should be turned on and the welding area should be purged 5s in advance. Start the laser and start welding after the power is stable.

[0117] For areas where pressure plate 7 was not welded in the first attempt, the position of pressure plate 7 was adjusted. After grinding and cleaning the weld seams on both sides, the 3D model of the ultra-high vacuum cavity, which was fixed by argon arc welding after being installed on the welding fixture, was imported into the CNC machine tool control system. Along the arc weld seam generation path, the position of pressure plate 7 was avoided. Clamping points were set at 5mm positions on both sides of each pressure plate 7, and the distance from the corresponding vacuum inner arc side plate 4 and the corresponding vacuum outer arc side plate 5 of the ultra-high vacuum cavity was 15mm. After setting, the formal welding was carried out. Before welding, the shielding gas should be turned on, the welding area should be purged 5 seconds in advance, the laser should be started, and welding should begin after the power stabilized. The welding of the two weld seams at the position of vacuum cover plate 3 was completed.

[0118] Then, after taking out and flipping the entire ultra-high vacuum chamber, the vacuum top cover plate 3 is placed on the positioning pin 9 and then placed on the limiting groove 16 of the bottom plate positioning fixture 1, located between the two waist-shaped grooves 12. The two weld seams of the top cover plate are wiped with alcohol to remove surface oil and oxide layer. The 3D model of the ultra-high vacuum chamber, which is fixed by argon arc welding after being installed on the welding fixture, is imported into the CNC machine tool control system. Along the arc weld seam generation path, the position of the pressure plate 7 is avoided. Clamping points are set at 5mm positions on both sides of each pressure plate 7, and the distance from the corresponding vacuum inner arc side plate 4 and the corresponding vacuum outer arc side plate 5 of the ultra-high vacuum chamber is 15mm. After setting, the formal welding is carried out. Before welding, the shielding gas should be turned on, the welding area should be purged 5 seconds in advance, the laser should be started, and welding should begin after the power stabilizes.

[0119] For areas where pressure plate 7 was not welded in the first attempt, the position of pressure plate 7 was adjusted. After grinding and cleaning the weld seams on both sides, the 3D model of the ultra-high vacuum cavity, which was fixed by argon arc welding after being installed on the welding fixture, was imported into the CNC machine tool control system. Along the arc weld seam generation path, the position of pressure plate 7 was avoided. Clamping points were set at 5mm positions on both sides of each pressure plate 7, and the distance from the corresponding vacuum inner arc side plate 4 and the corresponding vacuum outer arc side plate 5 of the ultra-high vacuum cavity was 15mm. After setting, the formal welding was carried out. Before welding, the shielding gas should be turned on, the welding area should be purged 5 seconds in advance, the laser should be started, and welding should begin after the power stabilized. The welding of the two weld seams at the vacuum base plate 2 position was completed.

[0120] After welding is completed, all welds are ground and electrochemically polished, while areas with significant deformation are mechanically straightened using a hydraulic straightening machine.

[0121] Furthermore, according to the machining drawings, the excess portion of the ultra-high vacuum cavity at the location of the locating pin 9 is removed, and the two machined ultra-high vacuum flanges 15 are welded to both ends of the ultra-high vacuum cavity using argon arc welding, thus completing the welding.

[0122] The advantages of the above-mentioned optional embodiments are as follows: the laser welding process can be optimized in advance through parameter setting, trial welding, and parameter determination. Trial welding can detect weld defects and avoid problems such as incomplete penetration and porosity caused by direct welding, thus ensuring the quality of external welding; welding after determining the final parameters can improve the welding accuracy and sealing of the ultra-high vacuum cavity, meet the stringent requirements of high-precision ring spectrometers for ultra-high vacuum cavities, and ensure the ultra-high vacuum performance and operational stability of the equipment.

[0123] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for manufacturing a large-sized arc-shaped pole high vacuum chamber, characterized in that, Comprise: Removing hydrogen: using an ultra-high vacuum furnace to remove hydrogen molecules in the raw material of the ultra-high vacuum chamber; Part processing: using a numerical control machine tool to sequentially process the vacuum bottom plate (2), the vacuum upper cover plate (3), the vacuum inner arc side plate (4) and the vacuum outer arc side plate (5); Laser welding: placing the vacuum bottom plate (2), the vacuum upper cover plate (3), the vacuum inner arc side plate (4) and the vacuum outer arc side plate (5) on the welding tool in turn, using argon arc welding spot welding to fix, and then using laser welding to perform outer welding to form an ultra-high vacuum chamber; Ultra-high vacuum leak detection: using helium mass spectrometry leak detection method to detect the weld of the ultra-high vacuum chamber; Size detection: using a laser tracker to measure the size of the ultra-high vacuum chamber, and the arc-shaped ultra-high vacuum chamber is completed, further comprising: Before the ultra-high vacuum leak detection, welding the ultra-high vacuum flange (15) to the end of the ultra-high vacuum chamber by argon arc welding, further comprising: Before the ultra-high vacuum leak detection, performing ultra-high vacuum cleaning on the ultra-high vacuum chamber after laser welding, the ultra-high vacuum cleaning on the ultra-high vacuum chamber after laser welding comprising: Rough cleaning to remove visible dirt; Ultrasonic cleaning in a 65℃ weak acid water-based solution for 15 minutes to remove oil; Placing in a 65℃ weak alkaline solution, ultrasonic cleaning for 15 minutes to neutralize; repeatedly flushing with flowing deionized water; Blowing dry water stains with high-purity nitrogen.

2. The method of claim 1, wherein, The welding tool comprises: A bottom plate positioning tool (1) provided with a waist-shaped groove (12) and a limiting groove (16), and the limiting groove (16) is provided with the waist-shaped groove (12) on both sides; A pressing plate (7) installed on the bottom plate positioning tool (1) through a mold assembly (6).

3. The method of claim 2, wherein the method further comprises: The mold assembly (6) comprises: A vertical column (13) arranged between the pressing plate (7) and the bottom plate positioning tool (1); A screw rod arranged at both ends of the vertical column (13), one of the screw rods (14) is connected with the pressing plate (7), and the other screw rod (14) is connected with the bottom plate positioning tool (1).

4. The method of claim 3, wherein the method further comprises: The welding tool further comprises: A positioning pin (9) inserted in the bottom plate positioning tool (1) during work.

5. The method of claim 1, wherein, Further comprising: In the laser welding step, before the argon arc welding spot welding, the size of the ultra-high vacuum chamber spliced on the welding tool is initially measured by a laser tracker and a vernier caliper, and the size is confirmed to meet the requirements.

6. The method of claim 1, wherein, After the argon arc welding spot welding, further comprising: Cleaning the welding position with alcohol to remove surface oil stains and oxide layers, and then using laser welding to perform outer welding to form an ultra-high vacuum chamber.

7. The method of claim 1, wherein, The laser welding to form an ultra-high vacuum chamber comprises: Parameter setting of a laser welder; Turning on the laser indicator light, adjusting the center of the robot to align the welding position, using a stainless steel plate to perform trial welding, and observing whether there are defects such as incomplete penetration, pores and hot cracks in the welded seam after trial welding; Determining the final welding parameters; Using the laser welder to perform outer welding to form an ultra-high vacuum chamber.

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