Electron beam welding positioning tooling and method for window inserts in fusion reactor diagnostics

Abstract

The application provides an electron beam welding positioning tool and method for a diagnostic window insert of a nuclear fusion reactor. The diagnostic window insert comprises a tube body including a first side plate, a second side plate and a circular arc transition section, and the positioning tool is used for positioning the tube body in an electron beam welding device. The positioning tool comprises a primary welding tool and a secondary welding tool. The primary welding tool comprises a base, a pressing block and a lateral positioning member. The base comprises a convex surface and a lateral arc surface. The pressing block is used for clamping the first side plate together with the convex surface. The lateral positioning member has a concave surface. The curvatures of the concave surface and the lateral arc surface are matched with the circular arc transition section. The concave surface and the lateral arc surface are used for clamping the circular arc transition section together. The pressing block and the lateral positioning member form a gap. The gap is used for exposing a joint between the circular arc transition section and the first side plate during primary welding. The secondary welding tool comprises a positioning assembly. The positioning assembly is used for fastening connection with inner surfaces of the plurality of side plates during secondary welding.

Description

Technical Field

[0001] This application relates to the field of precision welding technology, and more specifically, to an electron beam welding positioning fixture and method for window plugs in nuclear fusion reactor diagnostics. Background Technology

[0002] ITER (International Thermonuclear Experimental Reactor) is a large-scale magnetic confinement nuclear fusion experimental device. The diagnostic window module is a key component housing plasma diagnostic equipment and is used to perform diagnostic functions at ports in different locations within the ITER device, such as the upper, middle, or lower parts. The diagnostic window module located in the middle, also known as the central diagnostic window module, typically has a square tube structure with a rounded rectangular cross-section, formed by welding four side plates and rounded transition sections at the four corners. However, during the welding and positioning process between the curved surface and the side plates, the relative position of the curved surface and the side plates is difficult to fix precisely. This causes the other end of the rounded rectangular cross-section to easily deviate after welding, making it difficult to ensure the cross-sectional profile of the square tube is achieved. This, in turn, affects the assembly accuracy and sealing performance of the diagnostic window module and the vacuum chamber window. Summary of the Invention

[0003] This application provides an electron beam welding positioning fixture and method for window plugs in nuclear fusion reactor diagnostics, and is used to solve at least one of the above-mentioned technical problems.

[0004] In a first aspect, this application provides a positioning fixture for positioning the tube body of a window plug in a nuclear fusion reactor diagnostic process for electron beam welding. The tube body is surrounded by multiple side plates and an arc transition section. The side plates include a first side plate and a second side plate, and the arc transition section is connected between the first side plate and the second side plate. The positioning fixture is used to position the first side plate, the second side plate, and the arc transition section in an electron beam welding device.

[0005] The positioning fixture includes a primary welding fixture and a secondary welding fixture. The primary welding fixture includes a base, a pressure block, and a lateral positioning component. The base includes a boss surface and a side arc surface. The pressure block is used to clamp the first side plate together with the boss surface. The lateral positioning component has a concave arc surface. The curvature of the concave arc surface and the side arc surface both match the arc transition section. The concave arc surface and the side arc surface are used together to clamp the arc transition section. The pressure block and the lateral positioning component form a gap, which is used to expose the joint between the arc transition section and the first side plate during the primary welding. The secondary welding fixture includes a positioning assembly, which is used to fasten to the inner surfaces of multiple side plates during the secondary welding.

[0006] In this way, during the initial welding process, the boss surface and the pressure block work together to press the first side plate, and the side arc surface and the concave arc surface jointly clamp the arc transition section. This ensures that when welding the joint between the first side plate and the arc transition section for the first time, the first side plate and the arc transition section maintain a preset engagement angle. Then, during the secondary welding, the positioning components lock multiple side plates and arc transition sections from the inner surfaces of multiple side plates, improving the welding positioning accuracy of the tube body of the window plug in the nuclear fusion reactor diagnostics. At the same time, it is less likely to interfere with the electron beam irradiation towards the joint to be welded, thereby ensuring the assembly accuracy and reliable sealing of the diagnostic window plug.

[0007] In some embodiments, the boss surface is a plane with a square outline, and the side arc surfaces are located on both sides of the base along the two opposite sides of the boss surface.

[0008] In this way, each first side plate can be fixed to the initial welding fixture together with the two arc transition sections on both sides, reducing the number of additional assembly steps and improving welding efficiency.

[0009] In some embodiments, the lateral positioning member includes a first positioning plate and a second positioning plate. The first positioning plate is located on two opposite sides of the base along a first direction and is opposite to the side arc surface. A concave arc surface is formed on the first positioning plate. The second positioning plate is located on two opposite sides of the base along a second direction. The first direction and the second direction are two opposite directions of the side edges of the boss surface, respectively.

[0010] Thus, the first positioning plate and the second positioning plate fix the first side plate and the arc transition section from the first direction and the second direction, respectively, thereby improving the positioning accuracy and reliability of the first side plate and the arc transition section.

[0011] In some embodiments, the boss surface is formed with a receiving groove, which is located at the junction of the boss surface and the side arc surface and is opposite to the gap. The receiving groove extends along the joint between the arc transition section and the first side plate.

[0012] In this way, the receiving groove can receive molten droplets that fall during the welding process, and can also hold temporary backing strips, allowing the temporary backing strips to be welded to the inner side of the joint between the first side plate and the arc transition section, thereby ensuring perfect weld formation and providing support on the back of the weld, thus improving welding quality.

[0013] In some embodiments, the lateral positioning member is formed with an arc initiation groove and an arc termination groove communicating with the receiving groove, the arc initiation groove and the arc termination groove being located at opposite ends of the receiving groove along the length direction.

[0014] Thus, by setting arc initiation grooves and arc termination grooves at both ends of the receiving groove, the welding start and end ends, which are prone to defects due to unstable molten pools, are bombarded by electron beams instead of the first side plate and the arc transition section by the arc initiation grooves and the metal material filled in the grooves. This transfers the possible welding defects to the temporary backing strips or arc initiation and arc termination strips, thereby improving the welding quality.

[0015] In some embodiments, the base includes a flange that connects to a side arc surface and extends outward relative to the bottom edge of the side arc surface, and a lateral positioning member at least partially abuts against the flange.

[0016] In this way, the flange can support at least part of the lateral positioning component, enhance the positioning reliability of the concave arc surface and the lateral arc surface to the arc transition surface, and improve the stability of the initial welding fixture.

[0017] In some embodiments, the pressure block includes a pressure plate and a hollow portion connected to the pressure plate. The pressure plate is configured to fit tightly against the first side plate during initial welding, and the hollow portion forms a hollow area.

[0018] In this way, by tightly fitting the pressure plate to the first side plate, the positioning accuracy and reliability of the first side plate are ensured. At the same time, the hollowed-out part forms a hollowed-out area, which reduces the overall weight of the pressure block and facilitates molding.

[0019] In some embodiments, the positioning assembly includes a main frame, a locking member, and a connector. The connector is fixed to the inner surface of a plurality of side plates and has a positioning groove. The locking member is detachably fixed to the main frame and engages with the positioning groove to lock the main frame and side plates during secondary welding.

[0020] In this way, the locking component is detachably fixed to the main frame, and the locking component engages with the positioning slot, thereby conveniently assembling the positioning component on the inside of multiple side plates and achieving locking and positioning of the side plates from the inside.

[0021] In some embodiments, the secondary welding fixture includes a rotating assembly connected to a positioning assembly and used to rotate the tube so that the joints between the plurality of arc transition sections and the second side plate are sequentially oriented toward the electron beam emitting device of the electron beam welding equipment.

[0022] In this way, by rotating the component to assist the tube body in rotating, the joint to be welded can be switched more stably, thereby reducing deformation and displacement during the welding process of the second side plate and the arc transition section.

[0023] In some embodiments, the rotating assembly includes a first rolling element, a second rolling element, and a support element. The first rolling element is fixedly connected to the positioning assembly, the support element is fixedly disposed in the electron beam welding equipment, and the second rolling element is rotatably disposed on the support element and forms a rolling contact engagement with the first rolling element.

[0024] Thus, by fixing the first rolling element to the positioning component, fixing the positioning component to multiple side plates, and rotatably mounting the second rolling element on the support and forming a rolling contact with the first rolling element, the first rolling element, the positioning component as a whole, and multiple side plates and multiple arc transition sections rotate together relative to the support, thereby more conveniently realizing the adjustment of the orientation of the joint between the second side plate and the arc transition section.

[0025] Secondly, this application provides an electron beam welding positioning method for window components in nuclear fusion reactor diagnostics. The positioning method employs the positioning fixture described in any of the above embodiments and is used to position the first side plate, the second side plate, and the arc transition section in an electron beam welding device. The positioning method includes the following steps: Fix the arc transition section and the first side plate on the initial welding fixture; The welded arc transition section and the first side plate form a welded component; Fix the welding components and the second side plate on the secondary welding fixture; The joint between the welded arc transition section and the second side plate forms the tube body.

[0026] The electron beam welding positioning method provided in this application first positions and welds the first side plate and the arc transition section on the initial welding fixture to form a welded component, and then positions and welds the welded component to the second side plate on the secondary welding fixture. This allows the joints on both sides of the arc transition section to be completed in stages, reducing the problem of swaying or mutual pulling when welding the arc transition section to the flat side plate, which could lead to deformation of the tube body during welding. This improves welding stability and reliability, thereby ensuring the dimensional accuracy and sealing reliability of the tube body.

[0027] Additional aspects and advantages of this application will be set forth in the description which follows, in part from the description, or may be learned by practice of this application. Attached Figure Description

[0028] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein: Figure 1 This is a schematic diagram of the main structure of the tokamak device according to the embodiments of this application; Figure 2 This is a schematic diagram of the pipe body according to an embodiment of this application; Figure 3 This is a schematic diagram of the structure of the initial welding fixture according to the embodiments of this application; Figure 4 This is a cross-sectional schematic diagram of the initial welding fixture and welding component combination structure according to the embodiments of this application; Figure 5This is a schematic diagram of the separate structure of the welding component and the second side plate according to an embodiment of this application; Figure 6 This is a schematic diagram of the combined structure of the secondary welding fixture and the pipe body according to the embodiments of this application; Figure 7 yes Figure 6 An enlarged schematic diagram of part A; Figure 8 yes Figure 6 An enlarged schematic diagram of part B; Figure 9 This is a flowchart of the electron beam welding positioning method according to an embodiment of this application.

[0029] Explanation of key component symbols: 1000-Tokamak device, 1001-Vacuum chamber, 1002-Central port, 100-Tube body, 110-Side plate, 111-First side plate, 1111-First joint, 112-Second side plate, 1122-Second joint, 120-Circular transition section, 130-Welded component, 400-Temporary backing strip, 410-Arc-starting strip, 420-Arc-ending strip; 200-Initial welding fixture, 20-Base, 21-Boss surface, 211-Accommodation groove, 22-Side arc surface, 23-Flange, 30-Pressure block, 31-Pressure plate, 32-Hollowed part, 321-Hollowed section, 33-Gap, 40-Side positioning component, 41-First positioning plate, 411-Concave arc surface, 42-Second positioning plate, 421-Arc initiation groove, 422-Arc termination groove, X-First direction, Y-Second direction; 300-Secondary welding fixture, 50-Positioning component, 51-Main frame, 52-Locking component, 521-Fastening bolt, 522-Positioning block, 53-Connector, 531-Positioning groove, 5311-First section, 5312-Second section, 60-Rotating component, 61-First rolling component, 611-Turntable, 612-Connecting part, 62-Second rolling component, 63-Support component. Detailed Implementation

[0030] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0031] In the description of this application, it should be understood that the terms "center," "length," "width," "upper," "lower," "top," "bottom," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0032] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between the components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0035] Please see Figures 1-3 In one aspect, this application provides a positioning fixture for welding positioning of the tube body 100 of a window plug-in in nuclear fusion reactor diagnostics in an electron beam welding apparatus (not shown).

[0036] There are various technological approaches to nuclear fusion reactors, such as magnetic confinement tokamaks, stellarators, and laser inertial confinement. Taking ITER (International Thermonuclear Experimental Reactor), an experimental nuclear fusion reactor based on the magnetic confinement tokamak approach, as an example, the main body of ITER is the tokamak device 1000. The tokamak device 1000 includes a vacuum chamber 1001, a magnet system, a blanket, a divertor, a cryostat, and other core components used to achieve and maintain the fusion reaction. The vacuum chamber 1001 is a giant container used to provide an ultra-high vacuum environment for the nuclear fusion reaction. The magnet system is used to generate a powerful magnetic field to confine, shape, and control the high-temperature plasma, thereby achieving and maintaining the nuclear fusion reaction. The vacuum chamber 1001 has multiple ports at different heights, including a central port 1002, an upper port, and a lower port. The central port 1002 is a diagnostic window that can be passed through the equatorial plane of the vacuum chamber 1001. The equatorial plane of vacuum chamber 1001 (e.g.) Figure 1 The plane shown by the dashed line can be defined as the horizontal midplane that passes through the circumferential center of symmetry of the tokamak device 1000 and is perpendicular to the polar axis (i.e., the circumferential axis of symmetry) of the device.

[0037] The diagnostic window insert can be sealed and fixed in the port or port insert of the vacuum chamber 1001 and is used for optical, infrared, or microwave diagnostics. The diagnostic window insert includes structural components for fixation and support, such as the tube 100, and also contains functional components for optical, infrared, or microwave diagnostics.

[0038] For the middle port 1002, the upper port, and the lower port, due to their different height positions on the vacuum chamber 1001, the corresponding structural shapes of the diagnostic window plug-ins also differ. For example, the upper and lower ports are usually tangentially arranged, and the cross-section of the installed plug-ins is usually trapezoidal. The middle port 1002 is radially arranged, and the diagnostic window plug-in installed on the middle port 1002 is also known as the diagnostic mid-window plug-in. The structural components of the diagnostic mid-window plug-in include a tube 100 with openings at both ends, and the cross-section of the tube 100 is rectangular. The positioning fixture and positioning method of this application embodiment are used to position the tube 100, which has a rounded rectangular cross-section, during the welding process.

[0039] The tube body 100 is formed by multiple side plates 110 and an arc transition section 120. The side plates 110 include a first side plate 111 and a second side plate 112. The arc transition section 120 connects the first side plate 111 and the second side plate 112. A positioning fixture is used to position the first side plate 111, the second side plate 112, and the arc transition section 120 in an electron beam welding device. The arc transition section 120 is a metal strip with a semi-circular cross-section. The first side plate 111 and the second side plate 112 are both flat plates. Furthermore, the multiple side plates 110 and the arc transition section 120 are made of the same austenitic stainless steel material.

[0040] In some embodiments, the multiple side plates 110 are of equal length. The first side plate 111 and the second side plate 112 are two side plates 110 connected to the two sides of the arc transition section 120 along its circumferential direction. Among the multiple side plates 110, the two first side plates 111 may be in opposite positions, and the two second side plates 112 are opposite each other along an orthogonal direction to the opposite directions of the two first side plates 111. Further, when the multiple side plates 110 and the arc transition section 120 are formed into a tube body 100 and assembled integrally with the diagnostic window insert to the central port 1002, the two first side plates 111 are opposite each other in a horizontal direction, and the two second side plates 112 are opposite each other in a direction perpendicular to the equatorial plane.

[0041] In one specific embodiment, the length of the tube body 100, that is, the length of the plurality of side plates 110, is 4272 mm; the height of the tube body 100, that is, the sum of the width of the first side plate 111 and the radius of the two arc transition sections 120, is 2161 mm; the width of the tube body 100, that is, the sum of the width of the second side plate 112 and the radius of the two arc transition sections 120, is 1694 mm.

[0042] Please see Figure 3 , Figure 4 and Figure 6The positioning fixture of this application includes a primary welding fixture 200 and a secondary welding fixture 300. The primary welding fixture 200 includes a base 20, a pressure block 30, and a lateral positioning member 40. The base 20 includes a boss surface 21 and a side arc surface 22. The pressure block 30 is used to clamp the first side plate 111 together with the boss surface 21. The lateral positioning member 40 has a concave arc surface 411. The curvature of the concave arc surface 411 and the side arc surface 22 are both matched with the arc transition section 120. The concave arc surface 411 and the side arc surface 22 are used together to clamp the arc transition section 120. The pressure block 30 and the lateral positioning member 40 form a gap 33. The gap 33 is used to expose the joint between the arc transition section 120 and the first side plate 111 during the primary welding. The secondary welding fixture 300 includes a positioning component 50. The positioning component 50 is used to fasten to the inner surface of the multiple side plates 110 during the secondary welding. For ease of distinction, in the following description, the joint between the arc transition section 120 and the first side plate 111 is named the first joint 1111, and the joint between the arc transition section 120 and the second side plate 112 is named the second joint 1122.

[0043] Thus, in the initial welding fixture 200, the boss surface 21 and the pressure block 30 cooperate to press the first side plate 111, and the side arc surface 22 and the concave arc surface 411 jointly clamp the arc transition section 120. This ensures that when the first joint 1111 is welded for the first time, the first side plate 111 and the arc transition section 120 maintain a preset engagement angle. Then, during the secondary welding, the positioning component 50 locks the multiple side plates 110 and the arc transition section 120 from the inner surface of the multiple side plates 110, thereby reducing the deformation and displacement of the second side plate 112 and the arc transition section 120 during the welding process. At the same time, it is less likely to interfere with the electron beam irradiation towards the joint to be welded, improving the welding positioning accuracy of the tube body 100 of the window plug in the nuclear fusion reactor diagnosis, thereby ensuring the assembly accuracy and reliable sealing of the diagnostic window plug.

[0044] Specifically, electron beam welding equipment is a high-precision welding device that uses a high-speed electron beam to bombard the workpiece, converting the kinetic energy of the electron beam into heat energy to achieve material fusion and bonding. The electron beam emitting device is, for example, an electron gun. Electron beam welding has advantages such as high energy density, small heat-affected zone, and minimal welding deformation. When applied to the welding of the tube body 100 of the window insert in nuclear fusion reactor diagnostics, it can achieve extremely high-quality and high-precision welding, thereby ensuring the high reliability of the window insert during operation in the diagnostic process.

[0045] The base 20, pressure block 30, and lateral positioning member 40 can be separate structures before being assembled with the components of the tube body 100. By fixing at least two of the base 20, pressure block 30, and lateral positioning member 40 together, the first side plate 111 and the arc transition section 120 can maintain a fixed position and posture during the initial welding process, thereby reducing deformation and displacement.

[0046] The base 20 can be a relatively flat boss structure. The boss surface 21 is one end face of the base 20 along its own thickness direction, and the boss surface 21 is flat. The side arc surface 22 is connected to the boss surface 21, and the side arc surface 22 protrudes outward relative to the center of the base 20.

[0047] The lateral positioning component 40 includes a first positioning plate 41 opposite to the side arc surface 22. The first positioning part is strip-shaped and has a concave arc surface 411. The curvature of the concave arc surface 411 is the same as the curvature of the convex surface of the arc transition section 120 within a certain process error range, and the curvature of the side arc surface 22 is the same as the curvature of the concave surface of the arc transition section 120 within a certain process error range.

[0048] The edge of the pressure block 30 facing the first positioning plate 41 is spaced apart from the first positioning plate 41, and a gap 33 is formed between the edge of the pressure block 30 and the first positioning plate 41 along the first direction X. The first seam 1111 is exposed from the gap 33 and faces the electron beam emitting device.

[0049] In this application, the normal direction of the mounting surface of the primary welding fixture 200 and the secondary welding fixture 300 in the electronic welding equipment is defined as the vertical direction. Typically, the normal direction of the mounting surface of the primary welding fixture 200 and the secondary welding fixture 300 in the electronic welding equipment is parallel to the direction of gravity. The base 20 and the pressure block 30 can respectively press the first side plate 111 from the upper and lower sides. The electron beam emitting device is configured to emit an electron beam from top to bottom; the electron beam can be emitted vertically downwards or obliquely downwards.

[0050] The first side plate 111 and the arc transition section 120, after initial welding, are connected as a whole to form the welded component 130. The welded component 130 and the second side plate 112 can surround the outer periphery of the positioning component 50. The positioning component 50 pulls or presses each side plate 110 from the inside to reduce deformation and displacement during the welding process.

[0051] Please see Figure 3 and Figure 4 In some embodiments, the boss surface 21 is a plane with a square outline, and the side arc surface 22 is located on both sides of the base 20 along the opposite directions of the two sides of the boss surface 21.

[0052] In this way, each first side plate 111 can be fixed together with the two arc transition sections 120 on both sides on the initial welding fixture 200, reducing the number of additional assembly steps and improving welding efficiency.

[0053] Specifically, the first direction X can be the width direction of the boss surface 21, which also corresponds to the width direction of the first side plate 111 placed on the boss surface 21. The second direction Y can be orthogonal to the first direction X, and the second direction Y is the length direction of the boss surface 21, that is, the length direction of the first side plate 111 placed on the boss surface 21. The plane containing the first direction X and the second direction Y can be parallel to the mounting surface of the initial welding fixture 200 in the electronic welding equipment.

[0054] When the first side plate 111 is placed on the boss surface 21 and the pressure block 30 covers the first side plate 111, the projection range of the first side plate 111 on the boss surface 21 along the thickness direction falls within the contour range of the boss surface 21. The projection range of the pressure block 30 on the boss surface 21 along the thickness direction of the first side plate 111 can be located within the projection range of the first side plate 111 in the first direction X and exceed it in the second direction Y, and the projection range of the pressure block 30 also falls within the contour range of the boss surface 21.

[0055] Please see Figure 3 and Figure 4 In some embodiments, the lateral positioning member 40 includes a first positioning plate 41 and a second positioning plate 42. The first positioning plate 41 is located on both sides of the base 20 opposite to each other along the first direction X and is opposite to the side arc surface 22. The concave arc surface 411 is formed on the first positioning plate 41. The second positioning plate 42 is located on both sides of the base 20 opposite to each other along the second direction Y. The first direction X and the second direction Y are two opposite directions of the side edges of the boss surface 21, respectively.

[0056] Thus, the first positioning plate 41 and the second positioning plate 42 fix the first side plate 111 and the arc transition section 120 from the first direction X and the second direction Y of the first side plate 111, respectively, thereby improving the positioning accuracy and reliability of the first side plate 111 and the arc transition section 120.

[0057] As explained above, the first side is a square plate, and the boss surface 21 is square, with the first direction X and the second direction Y being orthogonal. The first side plate 111 and the second side plate 112 can surround the boss surface 21.

[0058] In some embodiments, the side of the base 20 facing the second positioning plate 42 can be a flat surface, and correspondingly, the second positioning plate 42 is generally straight. In other embodiments, the side plate 110 of the base 20 facing the second positioning plate 42 is an arc surface, curved surface or other complex shape that mates with the second positioning plate 42.

[0059] Please see Figure 3 and Figure 4In some embodiments, the base 20 includes a flange 23 connected to the side arc surface 22 and extending outward relative to the bottom edge of the side arc surface 22, and the lateral positioning member 40 at least partially abuts against the flange 23.

[0060] Thus, the flange 23 can support at least part of the lateral positioning element 40, enhance the positioning reliability of the concave arc surface 411 and the lateral arc surface 22 on the arc transition surface, and improve the stability of the initial welding fixture 200.

[0061] Specifically, the flange 23 can be a long, strip-shaped plate. A first positioning plate 41 can be placed on the flange 23 and fixedly connected to it. The side arc surface 22 connects to the boss surface 21 and the flange 23 on both sides along its circumference. The plane containing the boss surface 21 can be tangent to or nearly tangent to the side arc surface 22. The tangent of the side arc surface 22 at its connection with the flange 23 forms an angle with the plane containing the flange 23. The plane containing the flange 23 can be parallel to or nearly parallel to the boss surface 21.

[0062] In some embodiments, the base 20 is a boss with flanges 23 on both sides in the first direction X, and the base 20 can be a block integrally cast.

[0063] Please see Figure 3 and Figure 4 In some embodiments, the boss surface 21 is formed with a receiving groove 211, which is located at the connection between the boss surface 21 and the side arc surface 22 and is opposite to the gap 33. The receiving groove 211 extends along the joint between the arc transition section 120 and the first side plate 111.

[0064] Thus, the receiving groove 211 can receive molten droplets that fall during the welding process, and can also accommodate the temporary backing strip 400, allowing the temporary backing strip 400 to be welded to the inner side of the joint between the first side plate 111 and the arc transition section 120, thereby ensuring perfect weld formation and providing support on the back of the weld, improving welding quality.

[0065] Specifically, the receiving groove 211 can extend along the side of the square boss surface 21 to form an elongated groove. Before the first side plate 111 is fixed to the boss surface 21, a temporary backing strip 400 can be placed in the receiving groove 211. The temporary backing strip 400 is a component used to provide support on the back of the weld and constrain the molten metal to prevent the molten metal from flowing or burning through. The temporary backing strip 400 is typically made of the same material as the components being welded (the first side plate 111 and the arc transition section 120 in this embodiment).

[0066] Optionally, the temporary backing strip 400 extends beyond both ends of the receiving groove 211 along its length. This allows the electron beam to begin and end welding from the temporary backing strip 400 beyond the ends of the first joint 1111, thus avoiding a relatively unstable welding process that could affect the welding quality at the first joint 1111.

[0067] Please see Figure 3 and Figure 4 In some embodiments, the lateral positioning member 40 is formed with an arc initiation groove 421 and an arc termination groove 422 communicating with the receiving groove 211. The arc initiation groove 421 and the arc termination groove 422 are respectively located at opposite ends of the receiving groove 211 along the length direction.

[0068] Thus, by setting arc-starting groove 421 and arc-ending groove 422 at both ends of the receiving groove 211, the welding start and end ends, which are prone to defects due to unstable molten pools, are bombarded by electron beams instead of the first side plate 111 and the arc transition section 120 by the arc-starting groove 421 and arc-ending groove 422 and the metal material filled in the grooves. This transfers the possible welding defects to the temporary backing strip 400 or the arc-starting strip 410 and arc-ending strip 420, thereby improving the welding quality.

[0069] Specifically, the arc-initiating groove 421 and the arc-terminating groove 422 are respectively formed on two second positioning plates 42 opposite each other along the second direction Y. One of the second positioning plates 42 forms two arc-initiating grooves 421 at intervals along the first direction X, and the other second positioning plate 42 forms two arc-terminating grooves 422 at intervals along the first direction X. In the first direction X, the arc-initiating groove 421 and the arc-terminating groove 422 are located near the contact point between the first positioning plate 41 and the second positioning plate 42.

[0070] As explained above, the receiving groove 211 extends along the side of the boss surface 21 and also along the length direction of the first joint 1111. It is easily understood that the receiving groove 211 extends along the second direction Y. In the second direction Y, the arc-initiating groove 421 is located at the starting end of the electron beam emission device emitting an electron beam towards the first joint 1111; the arc-extinguishing groove 422 is located at the ending end of the electron beam emission device emitting an electron beam towards the second joint 1122. The arc-initiating groove 421 and the arc-extinguishing groove 422 respectively accommodate the ends of the temporary backing strip 400 extending beyond the receiving groove 211.

[0071] Furthermore, combined Figures 3-5The arc-starting groove 421 also accommodates an arc-starting strip 410, and the arc-ending groove 422 also accommodates an arc-ending strip 420. The arc-starting strip 410 and the arc-ending strip 420 can be stacked above the two ends of the temporary backing strip 400, respectively. The arc-starting strip 410 and the arc-ending strip 420 can be flush with the first side plate 111 located on the boss surface 21 in the thickness direction of the first side plate 111, or they can be slightly lower or slightly higher than the upper surface of the first side plate 111. In this way, the arc-starting strip 410 and the arc-ending strip 420 are respectively at both ends of the first joint 1111, and each plays the role of arc-starting and arc-extinguishing during the welding process.

[0072] Please see Figure 3 and Figure 4 In some embodiments, the pressure block 30 includes a pressure plate 31 and a hollow portion 32 connected to the pressure plate 31. The pressure plate 31 is configured to fit tightly against the first side plate 111 during the initial welding, and the hollow portion 32 forms a hollow section 321.

[0073] In this way, by tightly fitting the first side plate 111 with the pressure plate 31, the positioning accuracy and reliability of the first side plate 111 are ensured. At the same time, the hollowed-out section 32 forms a hollowed-out area 321, which reduces the overall weight of the pressure block 30 and facilitates its molding.

[0074] Specifically, the pressure plate 31 and the hollowed-out portion 32 can be integrated as a single unit. For example, the entire pressure block 30, including the pressure plate 31 and the hollowed-out portion 32, is integrally cast. The pressure plate 31 is a flat plate whose size and shape match the first side plate 111. The hollowed-out section 321 can include multiple square holes arranged in an array. All the contoured holes are blind holes.

[0075] The edge of the pressure plate 31 along the second direction Y may extend beyond the edge of the boss surface 21 and be fixedly connected to the second positioning plate 42. Further, the pressure block 30 is bolted to the second positioning plate 42 via the portion of the pressure plate 31 covering the second positioning plate 42.

[0076] Please see Figure 6 and Figure 7 In some embodiments, the positioning assembly 50 includes a main frame 51, a locking member 52, and a connecting member 53. The connecting member 53 is fixed to the inner surface of a plurality of side plates 110, and the connecting member 53 forms a positioning groove 531. The locking member 52 is detachably fixedly connected to the main frame 51, and the locking member 52 engages with the positioning groove 531 to lock the main frame 51 and the side plates 110 during secondary welding.

[0077] Thus, the locking member 52 is detachably fixed to the main frame 51, and the locking member 52 engages with the positioning groove 531, thereby conveniently assembling the positioning component 50 on the inner side of the multiple side plates 110, and achieving locking and positioning of the side plates 110 from the inside.

[0078] Specifically, the main frame 51 can be a solid block or a hollow support structure formed by several interlocking and mutually supporting rods. The locking component 52 includes a fastening bolt 521 and a positioning block 522. The positioning block 522 is fixedly connected to the fastening bolt 521 and is located at one end of the fastening connection. During the locking process between the positioning assembly 50 and the side plate 110, the positioning block 522 can extend into the positioning groove 531 and engage with the groove wall of the positioning groove 531. The locking component 52 is detachably mounted on the main frame 51 via the fastening bolt 521.

[0079] The connector 53 can be welded to the side plate 110 facing the main frame 51 using a relatively easy-to-peel welding method. After the secondary welding is completed, the main frame 51 and the locking member 52 are separated from the connector 53, and then the connector 53 on the side plate 110 is removed. Multiple connectors 53 can be evenly arranged on each side plate 110. The distribution position and number of locking members 52 correspond to the connectors 53. Each connector 53 is fixedly connected to one or more locking members 52 through a positioning groove 531.

[0080] In some embodiments, the positioning groove 531 includes a narrower first segment 5311 and a wider second segment 5312. The second segment 5312 is relatively close to the connection surface between the connector 53 and the side plate 110, while the first segment 5311 is closer to the main frame 51 than the second segment 5312. A stepped surface is formed between the first segment 5311 and the second segment 5312, and the positioning block 522 abuts against the stepped surface. The stepped surface intersects the axial direction of the fastening bolt 521, for example, in an orthogonal relationship. The cross-section of the positioning groove 531 is approximately "T"-shaped or an inverted "T"-shaped.

[0081] In some embodiments, the secondary welding fixture 300 includes a rotating assembly 60 connected to the positioning assembly 50 and used to rotate the tube body 100 so that the joints between the plurality of arc transition sections 120 and the second side plate 112 are sequentially directed toward the electron beam emitting device of the electron beam welding equipment.

[0082] In this way, by rotating the component 60 to assist the tube body 100 in rotating, the joint to be welded can be switched more stably, thereby reducing the deformation and displacement during the welding process of the second side plate 112 and the arc transition section 120.

[0083] Specifically, the rotating assembly 60 may be located outside the area enclosed by the multiple side plates 110. After the second joint 1122 of the upward-facing second side plate 112 is welded, the rotating assembly 60 may be rotated as a whole, including the auxiliary welding component 130, the second side plate 112, and the positioning assembly 50, to orient the second joint 1122 to be welded upwards. The rotation of the welding component 130, the second side plate 112, and the positioning assembly 50 may be achieved by manual force or driving force provided by other driving components.

[0084] Please see Figure 6 and Figure 8 In some embodiments, the rotating assembly 60 includes a first rolling element 61, a second rolling element 62, and a support element 63. The first rolling element 61 is fixedly connected to the positioning assembly 50, the support element 63 is fixedly disposed in the electron beam welding equipment, and the second rolling element 62 is rotatably disposed on the support element 63 and forms a rolling contact engagement with the first rolling element 61.

[0085] Thus, the first rolling element 61 is fixedly connected to the positioning component 50, the positioning component 50 is fixedly connected to multiple side plates 110, and the second rolling element 62 is rotatably mounted on the support 63 and forms a rolling contact with the first rolling element 61. This assists the first rolling element 61, the positioning component 50 as a whole, and the multiple side plates 110 and multiple arc transition sections 120 to rotate together relative to the support 63, making it easier to adjust the orientation of the joint between the second side plate 112 and the arc transition section 120.

[0086] Specifically, the first rolling element 61 includes a turntable 611 and a connecting part 612. The turntable 611 is fixedly connected to the main frame 51 through the connecting part 612. There can be multiple connecting parts 612. Each connecting part 612 may include several tripod-like legs and connecting rods. One end of the connecting rod is connected to one end face of the turntable 611 along its own axial direction, and the other end of the connecting rod is connected to the leg. The leg is fixedly connected to the main frame 51.

[0087] The second rolling element 62 is, for example, a roller, which is rotatably mounted on the support 63 via a pivot (not visible in the diagram). The support 63 can be positioned below the turntable 611, with the roller located between the support 63 and the turntable 611, and the outer circumferential surface of the roller making rolling contact with the outer circumferential surface of the turntable 611. The axial direction of the roller's pivot can be parallel or nearly parallel to the axial direction of the turntable 611, and the diameter of the roller can be much smaller than the diameter of the turntable 611. The diameter of the turntable 611 can be specifically set with reference to the width or height of the main frame 51.

[0088] In some embodiments, the second rolling element 62 includes two rollers, which are symmetrically distributed relative to a reference line passing through the center of the turntable 611 and both roll in cooperation with the turntable 611. This improves the stability of the structure and the rotation process. Please see Figure 4 , Figure 6 and Figure 9 Secondly, this application provides an electron beam welding positioning method for window components in nuclear fusion reactor diagnostics. The positioning method employs the positioning fixture described in any of the above embodiments and is used to position the first side plate 111, the second side plate 112, and the arc transition section 120 within an electron beam welding device. The positioning method includes the following steps: Step S10: Fix the arc transition section 120 and the first side plate 111 on the initial welding fixture 200; Step S20: Weld the joint between the arc transition section 120 and the first side plate 111 to form the welded component 130; Step S30: Fix the welding component 130 and the second side plate 112 on the secondary welding fixture 300; Step S40: Weld the joint between the arc transition section 120 and the second side plate 112 to form the tube body 100.

[0089] The electron beam welding positioning method provided in this application first positions and welds the first side plate 111 and the arc transition section 120 on the primary welding fixture 200 to form a welding component 130, and then positions and welds the welding component 130 to the second side plate 112 on the secondary welding fixture 300. This allows the joints on both sides of the arc transition section 120 to be completed in stages, reducing the problem of swaying or mutual pulling when the arc transition section 120 is welded to the flat side plate 110, which could lead to deformation of the tube body 100 during welding. This improves welding stability and reliability, thereby ensuring the dimensional accuracy and sealing reliability of the tube body 100.

[0090] It is easy to understand that the initial welding is the process of welding the first joint 1111, and the second welding is the process of welding the second joint 1122.

[0091] In step S10, the initial welding fixture 200 includes a separate base 20, a first positioning plate 41, a second positioning plate 42, and a pressure block 30. First, the first side plate 111 is placed on the boss surface 21 of the base 20, and the arc transition section 120 is placed on the side arc surface 22 of the base 20. The first side plate 111 and the arc transition section 120 are joined together by the first joint 1111, which is opposite to the receiving groove 211. A temporary backing strip 400 can be placed in the receiving groove 211 in advance. Then, the pressure block 30 is placed on the side of the first side plate 111 away from the boss surface 21, and the first positioning plate 41 is placed on the side arc surface 22 of the base 20. Positioning plate 41 is placed on arc transition section 120 and concave arc surface 411 is in contact with arc transition section 120; finally, second positioning plate 42 can be placed on both sides of base 20 along the second direction Y; first positioning plate 41 can be fixedly connected to flange 23 of base 20 to clamp arc transition section 120. At the same time, second positioning plate 42 can be fixedly connected to first positioning plate 41, pressure block 30 and base 20 respectively to limit the first side plate 111 and arc transition section 120 from the second direction Y, and enhance the positioning effect of pressure block 30 and boss surface 21 on the thickness direction of first side plate 111.

[0092] The base 20 and the first positioning plate 41, the second positioning plate 42 and the first positioning plate 41, the second positioning plate 42 and the pressure block 30, and the second positioning plate 42 and the base 20 can all be fixedly connected by at least one of the following methods: welding, screwing, riveting, etc.

[0093] In step S20, the first seam 1111 is exposed through the gap 33 between the pressure block 30 and the first positioning plate 41, and faces the electron beam emitting device. The electron beam emitting device emits an electron beam and sweeps along the first seam 1111, thereby achieving the welding of the first side plate 111 and the arc transition section 120. The first side plate 111 and the arc transition section 120, which are fixedly connected as a whole by the initial welding, constitute the welded component 130.

[0094] After step S20, that is, after the initial welding is completed, the welding component 130 can be removed from the initial welding fixture 200. That is, the fixedly connected base 20, first positioning plate 41, second positioning plate 42 and pressure block 30 need to be separated from each other.

[0095] After step S20, a temporary backing strip 400 may be connected to the inner side of the welding component 130 at the first joint 1111. The temporary backing strip 400 at the first joint 1111 can be removed before step S30, that is, before the welding component 130 is joined to the second side plate 112 and a secondary weld is performed. In other embodiments, the temporary backing strip 400 at the first joint 1111 can also be removed after step S40, that is, after the secondary weld is completed, together with the temporary backing strip 400 at the second joint 1122. The arc-starting plate and the arc-ending plate can be removed simultaneously with the temporary backing strips 400 to which they are attached.

[0096] In step S30, multiple connectors 53 can be fixed to the inner surfaces of the first side plate 111 and the second side plate 112. These connectors 53 can be arranged in rows along the length of the side plate 110 and spaced apart along the width of the side plate 110. Then, the second side plate 112 and the welding component 130 can be alternately arranged around the periphery of the main frame 51, and locking members 52 passing through the main frame 51 can be locked to the connectors 53, so that the edge of the second side plate 112 connects with the free edge of the arc transition section 120 on the welding component 130, and the second side plate 112 and the welding component 130 are spliced ​​into a tubular structure. At least one joint between the second side plate 112 and the welding component 130, i.e., the second joint 1122, faces the electron beam emitting device.

[0097] In step S40, the second joints 1122 on both sides of the second side plate 112 facing the electron beam emitting device can be welded first. Then, by rotating the first rolling element 61, the positioning component 50 and the tube body 100 to be welded can be rotated together relative to the electron beam welding equipment to rotate another second side plate 112 to an angle facing the electron beam emitting device. Then, the second joints 1122 between the other set of second side plates 112 and the arc transition section 120 can be welded. The rotation can be repeated multiple times until the joints between all the second side plates 112 and the welding components 130 are welded.

[0098] Please see Figure 2 , Figure 5 and Figure 6 In some embodiments, the side plate 110 includes two first side plates 111 and two second side plates 112, and the number of arc transition sections 120 is four. The positioning method further includes the following steps: Two first side plates 111 and four arc transition sections 120 are welded to form two welded components 130; Two welding components 130 and two second side plates 112 are fixed on the secondary welding fixture 300. One of the second side plates 112 and the arc transition section 120 face the electron beam emitting device of the electron beam welding equipment, and the other second side plate 112 faces away from the electron beam emitting device. Weld the joint between the second side plate 112 facing the electron beam emitting device and the arc transition section 120; Rotate the secondary welding fixture 300 and reverse the welding component 130 and the two second side plates 112; Weld the joint between the other second side plate 112 facing the electron beam emitting device and the arc transition section 120.

[0099] Thus, by first welding the two first side plates 111 to the four arc transition sections 120 to form two welded components 130, and then assembling and welding the two welded components 130 to the two separate second side plates 112, the number of welding steps can be reduced. Furthermore, by rotating the assembly 60 to invert the welded components 130 and the whole formed by the second side plates 112, the convenience and operational efficiency of the electron beam welding process can be improved. In addition, each side plate 110 can be welded to the arc transition sections 120 on both sides under a relatively uniform stress distribution, reducing mutual pulling and cumulative deformation.

[0100] It is easy to understand that for a tube 100 with a rounded rectangular cross-section, the arc transition sections 120 are located at the four corners of the tube 100, and there are a total of 8 joints between the four arc transition sections 120 and the four side plates 110 that need to be welded.

[0101] First, two side plates 110 positioned opposite each other on the tube body 100 are selected as the first side plates 111 and subjected to preliminary welding. After preliminary welding, the first side plates 111 are fixedly connected to an arc transition section 120 on each side along their width direction, forming a shape as shown in the figure. Figure 5 The welding component 130 is shown. The two side plates 110, which are the first side plates 111, can be opposite each other circumferentially in the vacuum chamber 1001 when the tube body 100 is assembled into the vacuum chamber 1001, or they can be opposite each other along the polar axis.

[0102] Subsequently, the two formed welded components 130 are fixedly connected to the positioning assembly 50 along with two other side plates 110 (second side plates 112), forming a tubular shape for secondary welding. During the secondary welding process, the positioning assembly 50 and the tubular welded components 130 and second side plates 112 can be rotated relative to each other by the first rolling element 61 on the second rolling element 62, assisting in the rotation of the positioning assembly 50 and the tubular welded components 130 and second side plates 112. Rotation refers to rotating the tubular welded components 130 and second side plates 112 180°, so that the second joint 1122, which was facing upwards in the initial stage of secondary welding, turns downwards, and the second joint 1122, which was facing downwards in the initial stage of secondary welding, turns upwards. Before and after rotation, electron beams are emitted from the two sets of second joints 1122 respectively to complete the welding of the welded components 130 and the second side plates 112.

[0103] In the description of this specification, references to terms such as "some embodiments," "examples," or "some examples" indicate that a specific feature, structure, material, or characteristic described in connection with the described embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0104] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An electron beam welding positioning fixture for window inserts in nuclear fusion reactor diagnostics, characterized in that, The plug-in includes a tube body surrounded by multiple side plates and an arc transition section. The side plates include a first side plate and a second side plate. The arc transition section is connected between the first side plate and the second side plate. The positioning fixture is used to position the first side plate, the second side plate and the arc transition section in an electron beam welding device. The positioning fixture includes: The initial welding fixture includes a base, a pressure block, and a lateral positioning component. The base includes a boss surface and a side arc surface. The pressure block is used to clamp the first side plate together with the boss surface. The lateral positioning component has a concave arc surface. The curvature of the concave arc surface and the side arc surface are both matched with the arc transition section. The concave arc surface and the side arc surface are used together to clamp the arc transition section. The pressure block and the lateral positioning component form a gap. The gap is used to expose the joint between the arc transition section and the first side plate during the initial welding. The secondary welding fixture includes a positioning component for fastening to the inner surfaces of the plurality of side plates during secondary welding.

2. The positioning fixture according to claim 1, characterized in that, The boss surface is a plane with a square outline, and the side arc surfaces are located on both sides of the base along the two opposite directions of the boss surface.

3. The positioning fixture according to claim 2, characterized in that, The lateral positioning component includes a first positioning plate and a second positioning plate. The first positioning plate is located on two opposite sides of the base along a first direction and is opposite to the side arc surface. The concave arc surface is formed on the first positioning plate. The second positioning plate is located on two opposite sides of the base along a second direction. The first direction and the second direction are two opposite directions of the side edges of the boss surface.

4. The positioning fixture according to claim 1, characterized in that, The boss surface is formed with a receiving groove, which is located at the connection between the boss surface and the side arc surface and is opposite to the gap. The receiving groove extends along the joint between the arc transition section and the first side plate.

5. The positioning fixture according to claim 4, characterized in that, The lateral positioning member has an arc-initiating groove and an arc-reducing groove that communicate with the receiving groove, and the arc-initiating groove and the arc-reducing groove are respectively located at opposite ends of the receiving groove along the length direction.

6. The positioning fixture according to claim 1, characterized in that, The base includes a flange that is connected to the side arc surface and extends outward relative to the bottom edge of the side arc surface, and the lateral positioning member at least partially abuts against the flange.

7. The positioning fixture according to claim 1, characterized in that, The pressure block includes a pressure plate and a hollowed-out portion connected to the pressure plate. The pressure plate is configured to fit tightly against the first side plate during the initial welding, and the hollowed-out portion forms a hollowed-out area.

8. The positioning fixture according to claim 1, characterized in that, The positioning assembly includes a main frame, a locking member, and a connecting member. The connecting member is fixed to the inner surface of the plurality of side plates and has a positioning groove. The locking member is detachably fixed to the main frame and engages with the positioning groove to lock the main frame and the side plates during the secondary welding.

9. The positioning fixture according to claim 1, characterized in that, The secondary welding fixture includes a rotating assembly connected to the positioning assembly and used to rotate the tube body so that the joints between the plurality of arc transition sections and the second side plate are sequentially oriented toward the electron beam emitting device of the electron beam welding equipment.

10. The positioning fixture according to claim 9, characterized in that, The rotating assembly includes a first rolling element, a second rolling element, and a support element. The first rolling element is fixedly connected to the positioning assembly, the support element is fixedly disposed in the electron beam welding equipment, and the second rolling element is rotatably disposed on the support element and forms a rolling contact engagement with the first rolling element.

11. A method for electron beam welding and positioning of a window insert in nuclear fusion reactor diagnostics, the insert comprising a tube body surrounded by multiple side plates and an arc transition section, the side plates comprising a first side plate and a second side plate, the arc transition section being connected between the first side plate and the second side plate, characterized in that, The positioning method is implemented using the positioning fixture described in any one of claims 1-10, and is used to position the first side plate, the second side plate, and the arc transition section in an electron beam welding equipment; the positioning method includes: The arc transition section and the first side plate are fixed on the initial welding fixture; Weld the joint between the arc transition section and the first side plate to form a welded component; The welding component and the second side plate are fixed on the secondary welding fixture; The joint between the arc transition section and the second side plate is welded to form the tube body.

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