Tube sheet welding tool and welding method

Abstract

The present application relates to the technical field of electron beam welding, in particular to a tube sheet welding tool and a welding method, the welding tool comprises an inner support, a backing ring and a heat dissipation assembly, the inner support supports the pipe opening of the connecting pipe, so that the pipe opening of the connecting pipe is not prone to collapse during the welding process, the backing ring is supported on the side of the tube sheet away from the to-be-welded part to block and dissipate heat on the back side of the weld, so as to avoid melting through on the back side of the weld, and the control of the weld width and the penetration depth is realized, at the same time, the heat dissipation assembly is attached to the side of the backing ring away from the to-be-welded part to dissipate heat on the back side of the weld, so as to avoid the deformation of the tube sheet during the welding process, the cooperation of various structures ensures the welding quality and improves the fusion rate; the tube sheet welding method adopts the above welding tool and adopts the welding sequence of spot welding, pre-welding and formal welding, so as to avoid the collapse of the pipe opening of the connecting pipe during the welding process, and the weld width and the penetration depth are easy to control, and the welding quality and the fusion rate can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of electron beam welding technology, and in particular to a tube sheet welding fixture and welding method. Background Technology

[0002] Tube sheet welding is a common manufacturing process for equipment such as heat exchangers, condensers, and reactors. Electron beam welding has significant advantages in tube sheet welding due to its concentrated energy, small thermal deformation, and large weld depth-to-width ratio. In particular, electron beam welding can facilitate high-quality and high-precision connection between thin-walled tubes and tube sheets.

[0003] For example, a pressure vessel has multiple nickel-based thin-walled nozzles inside. The outer diameter D / inner diameter d of the thin-walled nozzles is ≤1.2, and the wall thickness is relatively thin. Currently, these thin-walled nozzles need to be welded to the tube sheet using electron beam welding to achieve a high fusion rate (≥95%) in order to control the resistivity of the thin-walled nozzles to the extreme and ensure the long-term stable operation of critical equipment. However, electron beam welding needs to be performed in a vacuum environment, with high welding heat. The welding process is very prone to defects such as nozzle mouth collapse and tube wall melt-through. At the same time, the welding heat input is large, and the weld width and penetration depth are not easy to control during continuous welding, which can easily cause back weld burn-through, resulting in welding defects and failure to meet the fusion rate requirements, thus affecting the preparation and use of critical equipment. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology in electron beam welding of thin-walled nozzles and tube sheets, such as easy collapse of the nozzle or melting through the tube wall, and difficulty in controlling the weld width and penetration depth, which affect the welding quality and fusion rate. This invention provides a tube sheet welding fixture and welding method.

[0005] In a first aspect, the present invention provides a tube sheet welding fixture for assisting in electron beam welding of a connecting tube and a tube sheet, wherein the connecting tube is inserted into the tube sheet such that the opening of the connecting tube is flush with the tube sheet to form a welding area, and the welding fixture includes:

[0006] An inner support member, which is used to be fitted into the opening of the connecting pipe; A bushing, which is used to fit onto the connector and abut against the side of the tube sheet away from the part to be welded; A heat dissipation assembly is used to abut against the side of the bushing away from the part to be welded.

[0007] This invention provides a tube sheet welding fixture. An internal support member supports the tube opening, rigidly maintaining its stable shape and preventing collapse during welding. A bushing, positioned on the side of the tube sheet away from the welding area, seals and dissipates heat from the weld back side, protecting the outer wall of the tube and preventing weld penetration. This also facilitates control over weld width and depth, resulting in aesthetically pleasing welds. Furthermore, a heat dissipation component, attached to the bushing on the side away from the welding area, rapidly dissipates heat during welding, preventing tube sheet deformation. The coordinated structure ensures welding quality and improves fusion rate.

[0008] Preferably, the inner support member is interference-fitted with the connecting pipe, the length of the inner support member is greater than the thickness of the tube sheet, and an axial mounting hole is provided inside the inner support member. The inner support member can be detachably connected to an extension member and removed through the mounting hole. The inner support member can support the connecting pipe opening to prevent collapse during welding, and after welding, it can be lengthened by the assembly extension member to allow for removal of the inner support member.

[0009] Preferably, the heat dissipation assembly includes a pad and a heat exchange tube. The pad is engaged with the connecting pipe and rests against the side of the bushing away from the part to be welded. The heat exchange tube is wound around the connecting pipe and connected to a cooling medium delivery system. The heat exchange tube is in contact with the pad and / or the surface of the connecting pipe. By dispersing heat from the back of the part to be welded through the pad and then rapidly dissipating heat through the heat exchange tube, deformation of the tube sheet during welding can be effectively avoided, thus improving welding quality.

[0010] Preferably, the liner ring comprises a ceramic ring, the gasket comprises an oxygen-free copper plate, and the heat exchange tube comprises at least two flow channels, wherein the medium flows in the same or opposite directions in adjacent flow channels.

[0011] Preferably, a monitoring component is provided on the surface of the tube sheet, which is capable of monitoring the stress and / or strain state of the tube sheet during the welding process. The monitoring component can acquire the state of the tube sheet in real time during the welding process, which can be used to guide the real-time adjustment of welding parameters.

[0012] Preferably, the welding fixture further includes a limiting component, which clamps and cooperates with the tube sheet. The limiting component can limit and fix the tube sheet within the vacuum chamber, and a cooling system is installed outside the vacuum chamber. The limiting component stabilizes the relative positions of the connecting pipe, tube sheet, and welding fixture within the vacuum chamber, enabling electron beam welding within the vacuum chamber, while the cooling system outside the vacuum chamber assists in cooling the vacuum chamber.

[0013] In a second aspect, the present invention provides a tube sheet welding method, which employs a tube sheet welding fixture as described above to perform electron beam welding of a tube sheet and at least one connecting pipe, comprising: S1. Tooling assembly: Assemble the pipes, tube sheets and welding tooling to form the parts to be welded; S2, Spot welding: Spot welding is performed on the parts to be welded to initially fix the pipe and tube sheet; S3. Pre-welding: Welding parameters are obtained through pre-welding; S4. Formal Welding: Welding parameters obtained from S3 are used to complete the welding of the parts to be welded, forming a weld. S5. Tooling removal: Remove welding tooling and complete welding.

[0014] The tube sheet welding method of the present invention, by adopting the above-mentioned welding fixture and the welding sequence of spot welding, pre-welding and formal welding, can avoid the collapse of the tube end during the welding process, and is easy to control the weld width and penetration depth, thereby effectively improving the welding quality and fusion rate.

[0015] Preferably, the system includes multiple tubes arranged in an array. The pre-welding involves selecting a weldable portion located at or near the center of the tube sheet for welding, and obtaining welding parameters for use in welding the remaining weldable portions. Pre-welding a weldable portion related to the center of the tube sheet can better achieve stress dispersion, avoid tube sheet welding deformation, obtain more accurate and suitable welding parameters, and ensure the welding quality of all weldable portions.

[0016] Preferably, the system includes two tube sheets located at both ends of the nozzle. Several welding areas are formed on the opposite sides of the two tube sheets. After welding is completed on one side of the nozzle along its axial direction, welding is performed on the other side. The welding of the welding areas on the same tube sheet is staggered. This minimizes deformation of the tube sheet during welding.

[0017] Preferably, before removing the inner support, the weld side surface of the tube sheet is milled, and then the inner support is removed.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention provides a tube sheet welding fixture, which supports the tube opening through an internal support member, and can rigidly support the tube opening to maintain a stable shape, making it less likely to collapse during the welding process; 2. The present invention provides a tube sheet welding fixture, which is supported on the side of the tube sheet away from the part to be welded by a bushing ring. It can seal and dissipate heat on the back side of the weld, protect the outer wall of the tube, prevent melt-through on the back side of the weld, and facilitate the control of weld width and penetration depth, resulting in a beautiful weld. 3. This invention provides a tube sheet welding fixture, which uses a heat dissipation component to quickly dissipate heat during the welding process, thereby preventing the tube sheet from deforming during welding. The coordination of various structures ensures welding quality and improves fusion rate. 4. The present invention provides a tube sheet welding method. By using the above-mentioned welding fixture and adopting the welding sequence of spot welding, pre-welding and formal welding, the tube end collapse during the welding process can be avoided, and the weld width and penetration depth can be easily controlled, thereby effectively improving the welding quality and fusion rate. Attached Figure Description

[0019] Figure 1 This is a structural schematic diagram of a tube sheet welding fixture (before the installation of the limiting component) in Example 1.

[0020] Figure 2 This is a schematic diagram of the structure of the pad described in Example 1.

[0021] Figure 3 This is a schematic diagram of the structure of a tube sheet welding fixture (after the installation of the limiting component) in Example 1.

[0022] Figure 4 for Figure 3 A structural diagram from another perspective.

[0023] Figure 5 This is a top view of a tube sheet welding fixture according to Example 1.

[0024] Figure 6 This is a diagram showing the usage state of a tube sheet welding fixture in Example 1.

[0025] Figure 7 This is a front view of the tube sheet welding fixture in use according to Example 1.

[0026] Figure 8 for Figure 7 A magnified structural diagram of part A in the middle.

[0027] Figure 9 This is a bottom view of the tube sheet welding fixture in use according to Example 1.

[0028] Figure 10 This is a schematic flowchart of a tube sheet welding method according to Example 2.

[0029] Marked in the image: 1- Connector, 2- Tube sheet, 3- Welding area, 4- Inner support, 41- Assembly hole, 5- Liner ring, 6- Heat dissipation assembly, 61- Pad plate, 62- Heat exchange tube, 7- Monitoring assembly, 8- Limiting assembly. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0031] Unless otherwise specified, the terms "upper," "lower," "left," "right," "center," "inner," and "outer," etc., used in the description of specific embodiments of the present invention to indicate orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is usually placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, and for enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0032] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are arranged as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in "horizontal," "vertical," "suspended," "parallel," or "coaxial" directions, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0033] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0034] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0035] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to connection methods commonly used in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0036] Example 1 like Figures 1-9 As shown, a tube sheet welding fixture is used to assist in the electron beam welding of a tube 1 and a tube sheet 2. The tube 1 is inserted into the tube sheet 2, so that the opening of the tube 1 is flush with the tube sheet 2 to form a welding part 3. The welding fixture includes an inner support 4, a bushing 5, and a heat dissipation assembly 6.

[0037] The inner support 4 is used to be embedded in the opening of the connector 1 to provide rigid inner support for the opening of the connector 1, so as to prevent the opening of the connector 1 from collapsing during the welding process and to prevent the pipe wall of the connector 1 from being welded through during the welding process. It can overcome the problem that the pipe opening collapses and the pipe wall is easily welded through due to the large heat input of electron beam welding.

[0038] In an optional embodiment, the inner support 4 is interference-fitted with the connecting pipe 1. The length of the inner support 4 is greater than the thickness of the tube sheet 2. When in use, the end face of the inner support 4 is flush with the opening of the connecting pipe 1. The opening of the connecting pipe 1 is flush with the tube sheet 2 to form the welding part 3, so that the inner support 4 can provide overall support for the contact area between the connecting pipe 1 and the tube sheet 2, effectively preventing the pipe opening from collapsing during the welding process.

[0039] In an optional embodiment, the inner support 4 may be made of the same material as the connecting pipe 1.

[0040] In an optional embodiment, an assembly hole 41 is provided axially inside the inner support member 4. The inner support member 4 can be extended by detachably connecting an extension member through the assembly hole 41 to assist in the removal of the inner support member 4 from the pipe 1. The assembly hole 41 can be a threaded hole provided axially along the inner support member 4. The extension member can be a conventional structure such as a screw or bolt that is threadedly connected to the inner support member 4. The inner support member 4 can be extended by threading the extension member after welding.

[0041] The bushing 5 is used to fit onto the tube 1 and abut against the side of the tube sheet 2 away from the part 3 to be welded.

[0042] In an optional embodiment, the bushing 5 includes a ceramic ring, which can seal the back side of the part to be welded 3 and block the molten metal, so that the back of the weld is formed beautifully and does not damage the pipe wall.

[0043] The heat dissipation component 6 is attached to the side of the bushing 5 away from the part 3 to be welded, which can achieve rapid heat dissipation during the welding process and effectively ensure that the tube sheet 2 is not easily deformed.

[0044] In one or more embodiments, the heat dissipation assembly 6 may include a pad 61, which is attached to the side of the bushing 5 away from the part 3 to be soldered, and the pad 61 is engaged with the connector 1.

[0045] In an optional embodiment, the backing plate 61 can be an oxygen-free copper plate. The backing plate 61 is installed on the side of the bushing 5 away from the part 3 to be welded. Combined with the bushing 5, it further protects the back side of the weld from being welded through and enables the tube sheet 2 to dissipate heat quickly, effectively ensuring that the tube sheet 2 is not easily deformed, and can also help the bushing 5 to stick to one side of the tube sheet 2.

[0046] In an optional embodiment, a snap-fit ​​can be provided on the pad 61 at the position corresponding to the connector 1. The snap-fit ​​can be a U-shaped groove that passes through the edge of the pad 61, so that the pad 61 can be snapped onto the connector 1. At the same time, the pads 61 can be used in pairs and snapped onto the connector 1 with the snaps facing each other, so as to facilitate removal after welding.

[0047] In an optional embodiment, the pad 61 can be provided in one or more layers. When multiple layers of pads 61 are used in combination, the snaps of adjacent layers of pads 61 can be kept perpendicular to each other to ensure the stability of the multi-layer pads 61 and to achieve better heat conduction and heat dissipation.

[0048] In an optional embodiment, the number of slots on the pad 61 can be set to one or more depending on the actual situation. When multiple slots are provided on the pad 61, each slot can hold at least one pipe 1.

[0049] In one or more embodiments, the heat dissipation assembly 6 may further include a heat exchange tube 62, which is coiled around the connecting pipe 1, connected to the cooling medium delivery system, and in contact with the pad 61 and / or the surface of the connecting pipe 1.

[0050] In an optional embodiment, the heat exchange tube 62 may include at least two flow channels, and the medium flow direction in adjacent flow channels may be the same or opposite. When there are multiple tubes 1, the heat exchange tube 62 may be coiled around the outside of each tube 1 along the surface of the pad 61 and passed between each tube 1 to realize the dissipation of welding heat during the welding process.

[0051] In this embodiment, two heat exchange tubes 62 are arranged side by side to form two flow channels. The two heat exchange tubes 62 are respectively connected to the cooling medium delivery system. The cooling medium can be coolant or water. The two heat exchange tubes 62 are wound between multiple pipes 1, and the medium flows in opposite directions in the two flow channels, which can form a dual-circulation liquid cooling circulation system. During the welding process, the welding heat is removed by bidirectional circulation of coolant.

[0052] In an optional embodiment, the cross-section of the heat exchange tube 62 can be rectangular to achieve surface contact between the heat exchange tube 62 and the connecting pipe 1 and the pad 61, thereby increasing the heat dissipation area of ​​the heat dissipation component 6 and improving the heat conduction and heat dissipation effect.

[0053] In one or more embodiments, a monitoring component 7 is provided on the surface of the tube sheet 2, which is capable of monitoring the stress and / or strain state of the tube sheet 2 during the welding process.

[0054] In an optional embodiment, the monitoring component 7 can be a stress and strain gauge attached to the tube sheet 2. The monitoring component 7 can be connected to a real-time online data monitoring system, which can acquire the status of the tube sheet 2 in real time during the welding process. Based on the real-time monitoring data, the welding parameters such as welding voltage and current can be dynamically adjusted to ensure that the tube sheet 2 does not deform during the welding process to the greatest extent. This can effectively solve the problem that the tube sheet 2 is prone to deformation due to the large heat input during electron beam welding, the local temperature exceeds the range of the molten pool, and large changes in thermal stress are easily generated.

[0055] In one or more embodiments, the welding fixture further includes a limiting component 8, which is clamped and cooperates with the tube sheet 2. The limiting component 8 can limit and fix the tube sheet 2 in the vacuum chamber, and a cooling system is installed against the outside of the vacuum chamber.

[0056] In an optional embodiment, the structure of the limiting component 8 can be adjusted according to the actual situation. In this embodiment, the limiting component 8 may include two limiting plates connected by a screw pull. The limiting plates can be connected to the fixed structure inside the vacuum chamber to realize the limiting and fixing of the welding fixture in the vacuum chamber. The limiting plates may be provided with limiting grooves that are adapted to the tube sheet 2 to stabilize the position of the tube sheet 2 under the action of the screw pull, thereby fixing the position of the pipe 1 to be welded and the tube sheet 2.

[0057] In an optional implementation, the cooling system may include an air duct and a flow guiding unit fitted to the outside of the vacuum chamber, which, together with the air duct box, air pipe and fan, form an air-cooled heat dissipation system, forming external convection outside the vacuum chamber to remove heat from the outer wall of the vacuum chamber, thereby achieving an auxiliary cooling effect.

[0058] This embodiment of a tube sheet welding fixture uses an inner support member 4 to support the nozzle 1, rigidly supporting the nozzle 1 to maintain a stable shape and preventing collapse during welding. A bushing 5 supports the tube sheet 2 on the side away from the welding area 3, sealing and dissipating heat on the back side of the weld, protecting the outer wall of the nozzle 1, preventing weld penetration on the back side, and facilitating control of weld width and penetration depth, resulting in a aesthetically pleasing weld. Simultaneously, a heat dissipation component 6 provides rapid heat dissipation during welding, preventing deformation of the tube sheet 2. This tube sheet welding fixture, through the coordinated structure, uses a ceramic ring to protect the back side of the weld, and a dual-circulation liquid cooling system and air cooling system to maximize the removal of welding heat, ensuring that excessive heat input does not cause deformation of the tube sheet 2 or weld penetration of the nozzle 1 wall, thus guaranteeing welding quality and improving fusion rate.

[0059] Example 2 like Figure 10 As shown, a tube sheet welding method, using a tube sheet welding fixture of Embodiment 1, performs electron beam welding of tube sheet 2 and at least one connecting pipe 1, including: S1. Tooling assembly: Assemble pipe 1, pipe sheet 2 and welding tooling to form the part to be welded 3.

[0060] S1 is used to assemble the connector 1, tube sheet 2 and welding fixture. The tube sheet 2 is provided with a tube hole that matches the connector 1. After the connector 1 is installed with the inner support 4, it is inserted into the tube hole on the tube sheet 2 to form the part to be welded 3. Specifically, it may include embedding the inner support 4 in the tube opening of the connector 1, fitting the bushing 5 and heat dissipation assembly 6 on the connector 1, inserting the connector 1 into the tube sheet 2 so that the tube opening of the connector 1 is flush with the tube sheet 2, and forming the part to be welded 3 on the outer side of the tube sheet 2 away from the connector 1.

[0061] S2, Spot welding: Spot weld at the part to be welded 3 to initially fix the pipe 1 and the pipe sheet 2.

[0062] S3. Pre-welding: Welding parameters are obtained through pre-welding.

[0063] S3 is used for pre-welding of the part to be welded or the structure under the same conditions to obtain accurate welding parameters and ensure welding quality.

[0064] In an optional embodiment, when multiple tubes 1 are arranged in an array, the welding part 3 located at or near the center of the tube sheet 2 can be selected for welding during pre-welding, and the welding parameters can be obtained for welding the remaining welding parts 3.

[0065] S4. Formal Welding: Using the welding parameters obtained from S3, complete the welding of part 3 to be welded to form a weld.

[0066] In an optional implementation, during the formal welding process, multiple parts to be welded on the same tube sheet 2 can be staggered to prevent deformation of the tube sheet 2 during welding.

[0067] In an optional embodiment, when both ends of the connector 1 need to be welded, several weldable parts 3 are formed on the two tube sheets 2 on the side surfaces that are far apart from each other. After the weldable parts 3 on one side of the connector 1 are welded, the weldable parts 3 on the other side are welded to achieve symmetrical welding of the two tube sheets 2 and prevent the tube sheets 2 from deforming during welding.

[0068] S5. Tooling removal: Remove welding tooling and complete welding.

[0069] In an optional implementation, corresponding to S5, after the welding of the part to be welded 3 is completed, the limiting component 8 and the heat dissipation component 6 can be removed first. Before the inner support 4 is removed, the weld side surface of the tube sheet 2 is milled to meet the requirements, so as to improve the accuracy of the weld side surface of the tube sheet 2 and facilitate the removal of the inner support 4, so as to ensure the welding quality to the greatest extent.

[0070] Taking the tube sheet welding of a nozzle 1 inside a pressure vessel as an example, the process includes two tube sheets 2 and nine nozzles 1 arranged in three rows and three columns. Nine welding portions 3 are formed on the two tube sheets 2 on their opposite sides. The outer diameter D / inner diameter d of the nozzle 1 is ≤1.2, and the wall thickness is relatively thin. The depth-to-width ratio of each welding portion 3 is ≥10, and the welding width is ≤2mm. This process exhibits high penetration depth and low weld width. Conventional electron beam welding methods either result in insufficient penetration depth or, even if the penetration depth is sufficient, excessive heat input causes the nozzle 1 wall to collapse or melt through. Therefore, a tube sheet welding fixture from Example 1 and a tube sheet welding method from Example 2 are used, specifically including: a. An inner support 4 is embedded in the opening of each pipe 1, two ceramic rings are fitted on each pipe 1, and heat dissipation components 6 are set on both sides of the axial direction of the pipe 1. Then, the pipe 1 is assembled and inserted into one side of the tube plate 2 so that the opening of the pipe 1 is flush with the tube plate 2, forming nine arrayed welding parts 3 on a single tube plate 2. b. Spot weld the part to be welded 3 to initially fix each pipe 1 and tube sheet 2. The spot welding parameters can be voltage 80~90KV, beam current 3~6MA, welding speed 300mm / min, and welding height 130mm. c. On the side of tube sheet 2 away from the part to be welded 3, match and adjust the position of ceramic ring, oxygen-free copper plate and heat exchange tube 62, and limit the whole by the limiting component 8. Then perform pre-welding and check the stability of the voltage and current of the welding equipment. The pre-welding parameters can be voltage 80~90KV, beam current 8~12MA, welding speed 300mm / min and welding height 130mm. d. After the pre-welding is completed, the formal welding is carried out to complete the welding of the remaining parts 3 to be welded on the tube sheet 2. The formal welding parameters can be voltage 80~90KV, beam current 30~50MA, welding speed 300mm / min, and welding height 130mm. e. After the welding of one side of the tube sheet 2 is completed, the limiting component 8 is released, and the tube sheet 2 is flipped over to be welded on the other side.

[0071] In an optional embodiment, during pre-welding, the part 3 to be welded located at the center of the tube sheet 2 can be pre-welded to obtain welding parameters for welding the remaining parts 3 to be welded. The remaining parts are welded alternately. The alternate welding can be centered on the pre-welding position, and the upper, lower, left, and right parts 3 to be welded are welded sequentially using the adjusted welding parameters. Then, the corner parts 3 to be welded are welded sequentially in the diagonal direction. This ensures that there is at least one weld gap between the two welds welded successively. Combined with the dynamic adjustment of welding parameters during the welding process, it can effectively ensure that the tube sheet 2 does not deform due to uneven thermal stress, increase the weld fusion rate to more than 95%, and not cause damage to the tube sheet 2 and the connecting pipe 1. After welding, the inner support 4 can be lengthened and removed by the assembly extension, the ceramic ring can be removed by knocking and breaking, the heat exchange tube 62 can be removed by cutting and separating, and the pad 61 can be removed by moving.

[0072] In an optional embodiment, the heat dissipation component 6 can be reused during the welding process of the tube sheets 2 at both ends of the connecting pipe 1. That is, by adjusting the limiting state of the limiting component 8, the pad 61 and the heat exchange tube 62 can be disengaged from the corresponding side tube sheet 2, move along the axis of the connecting pipe 1 to fit against the other side tube sheet 2, and then be fixed by the limiting component 8.

[0073] This embodiment of a tube sheet welding method employs the aforementioned welding fixture. The inner support member 4 supports the tube 1, preventing collapse of the tube 1 opening during welding. A bushing 5 seals the back side of the weld, and a heat dissipation component 6 rapidly dissipates heat. A welding sequence of spot welding, pre-welding, and final welding is used to progressively increase the welding heat input. Welding parameters such as voltage, current, welding speed, and welding height are calculated and precisely controlled, facilitating control of weld width and penetration depth. This effectively improves welding quality and fusion rate, enhancing the welding quality of the tube 1 and tube sheet 2. It ensures the fusion rate of the thin tube 1 and tube sheet 2 meets requirements, overcomes the problem of easy burn-through on the back side of the tube sheet 2 weld, and achieves a higher fusion rate for welds with high penetration depth and low weld width. This improves work efficiency and enhances the reliability and safety of the device.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tube sheet welding method, characterized in that, An electron beam welding fixture is used to assist in the welding of a tube sheet (1) and a tube sheet (2). The tube sheet (1) is inserted into the tube sheet (2) so that the opening of the tube sheet (1) is flush with the tube sheet (2) to form a welding part (3). The outer diameter D / inner diameter d of the tube sheet (1) is ≤1.2, the depth-to-width ratio of the welding part (3) is ≥10, and the welding width is ≤2mm. The welding fixture includes: The inner support member (4) is used to be installed in the pipe opening of the pipe (1). The end face of the inner support member (4) is flush with the pipe opening of the pipe (1) to provide overall support for the contact area between the pipe (1) and the tube sheet (2). A bushing (5) is used to fit onto the connecting pipe (1) and abut against the side of the tube sheet (2) away from the part to be welded (3); A heat dissipation assembly (6) is used to abut against the side of the bushing (5) away from the part to be welded (3). The heat dissipation assembly (6) includes a pad (61) and a heat exchange tube (62). The pad (61) is engaged with the connecting pipe (1) and abuts against the side of the bushing (5) away from the part to be welded (3). The heat exchange tube (62) is coiled around the connecting pipe (1) and is connected to a cooling medium delivery system. The heat exchange tube (62) is in contact with the pad (61) and / or the surface of the connecting pipe (1). The welding steps include: S1. Tooling assembly: Assemble the pipe (1), pipe sheet (2) and welding tooling to form the part to be welded (3); S2, Spot welding: Spot weld at the part to be welded (3) to initially fix the pipe (1) and the tube sheet (2); S3. Pre-welding: Welding parameters are obtained through pre-welding; S4, Formal Welding: Using S3 to obtain welding parameters to complete the welding of the part to be welded (3), forming a weld, the welding sequence of spot welding, pre-welding and formal welding, gradually increasing the welding input heat; S5. Tooling removal: Remove welding tooling and complete welding; The pre-welding includes multiple pipes (1) arranged in an array, and the pre-welding includes selecting the welding part (3) located at or near the center of the tube sheet (2) for welding, and obtaining welding parameters for welding the remaining welding parts (3); It includes two tube sheets (2) located at both ends of the connector (1). The two tube sheets (2) form several weldable parts (3) on the side surfaces that are far apart from each other. After the weldable parts (3) on one side of the connector (1) are welded, the weldable parts (3) on the other side are welded. The weldable parts (3) on the same tube sheet (2) are welded alternately.

2. The tube sheet welding method according to claim 1, characterized in that, The inner support member (4) is interference-fitted with the connecting pipe (1). The length of the inner support member (4) is greater than the thickness of the tube sheet (2). The inner support member (4) has an axially arranged assembly hole (41). The inner support member (4) can be detachably connected to the extension member and taken out through the assembly hole (41).

3. The tube sheet welding method according to claim 1, characterized in that, The liner (5) includes a ceramic ring, the pad (61) includes an oxygen-free copper plate, and the heat exchange tube (62) includes at least two flow channels, with the medium flowing in the adjacent flow channels in the same or opposite directions.

4. The tube sheet welding method according to claim 1, characterized in that, The surface of the tube sheet (2) is provided with a monitoring component (7), which is capable of monitoring the stress and / or strain state during the welding process of the tube sheet (2).

5. The tube sheet welding method according to claim 1, characterized in that, The welding fixture also includes a limiting component (8), which is clamped and cooperates with the tube sheet (2). The limiting component (8) can be limited and fixed in the vacuum chamber, and a cooling system is installed outside the vacuum chamber.

6. The tube sheet welding method according to claim 1, characterized in that, Before removing the inner support (4), the weld side surface of the tube sheet (2) is milled, and then the inner support (4) is removed.

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