Tool and method for carrying out protective welding on easily oxidized metal of welded heat exchanger

Abstract

The invention discloses a tool for conducting protective welding on easily-oxidized metal of a welding type heat exchanger, and belongs to the technical field of welding, the tool comprises a gas protection tool and an automatic pressing tool, the gas protection tool comprises a barrel, an upper cover, a lower cover and a rubber sleeve, a plurality of round holes are evenly distributed in the lower cover, the rubber sleeve is of a conical structure, and the upper cover and the lower cover are arranged in the barrel. The automatic pressing tool comprises a lifting crane, an upper pressing plate, a lower pressing plate and a guiding and positioning assembly, the lifting crane comprises a motor, a center mechanism and four screws, a gear transmission system is arranged in the center mechanism, and the guiding and positioning assembly comprises a guiding column, a plate diagonal hole positioning and pressing plate and a sliding rail mechanism. According to the tool for conducting protective welding on the easily-oxidized metal of the welding type heat exchanger, efficient and high-quality protective welding of the easily-oxidized metal is achieved through the collaborative design of the gas protection tool and the pressing automation tool in combination with precise gas parameter control and an intelligent welding strategy.

Description

Technical Field

[0001] This invention belongs to the field of welding technology, specifically relating to tooling and methods for protective welding of easily oxidized metals in welded heat exchangers. Background Technology

[0002] Welded heat exchangers (such as semi-welded plate heat exchangers) often use titanium plates as their heat exchange cores. Titanium plates have excellent corrosion resistance, long service life, and high pressure resistance, and are widely used in shipbuilding, chemical industry, and other fields. However, welding titanium and other easily oxidized metals presents many technical challenges: Titanium is chemically extremely reactive at temperatures above 600℃, readily reacting violently with oxygen, nitrogen, hydrogen, and other elements in the air to form hard and brittle compounds, leading to a decline in the material's mechanical properties; titanium has poor thermal conductivity, making it difficult to dissipate heat during welding, easily causing plate deformation and weld cracks; welding requires heating the plates to temperatures above 1600℃, causing rapid growth of titanium grains at instantaneous high temperatures, further affecting weld toughness and fatigue strength; in addition, for plates with special flow channels, it is difficult to simultaneously achieve flow channel bends and effective gas protection during welding. Existing tooling suffers from poor workpiece adaptability, inadequate fixation stability, and insufficient gas protection, leading to easy air intrusion during welding, easy oxidation and hydrogen embrittlement of the weld, affecting the heat exchanger's performance and lifespan.

[0003] Existing rare gas shielded welding fixtures have the following shortcomings: First, they are poorly adaptable to special flow channel plates, making it difficult to ensure continuous and effective gas coverage of the weld when bending. Second, the plates lack stability in fixing, failing to provide comprehensive and precise clamping and positioning, which leads to plate displacement during welding, affecting welding accuracy and gas shielding effectiveness. Third, the gas shielding effect is poor, as rare gases easily mix with air when introduced, and the lack of continuous protection during the weld cooling stage leads to weld oxidation and hydrogenation. Summary of the Invention

[0004] The purpose of this invention is to provide a tooling for protective welding of easily oxidized metals in welded heat exchangers, thereby solving the problems of easy oxidation, hydrogen embrittlement, difficulty in protecting the metals of special flow channels when welding easily oxidized metals in welded heat exchangers as mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a tooling for protective welding of easily oxidized metals in welded heat exchangers, including a gas protection tooling and an automated clamping tooling. The gas protection tooling includes a cylinder, an upper cover, a lower cover, and a rubber sleeve. The cylinder is a stainless steel round tube or seamless steel tube of a specific size, and its length is set to ensure that the laser welding gun head is in the optimal welding position. The upper cover is a round plate that matches the cylinder, and its upper part has a hole adapted to the size of the laser welding gun head for the laser welding gun head to extend into. The lower cover is a round plate of a specific thickness, on which round holes with a precision of 2mm are evenly distributed. The rubber sleeve is made of EPDM (ethylene propylene diene monomer rubber) material and has a conical structure, used to seal rare gases and as an intermediate transfer medium for special flow channel bends.

[0006] The automated clamping fixture includes a lifting crane, an upper clamping plate, a lower clamping plate, and a guide positioning assembly. The lifting crane includes a motor, a central mechanism, and four screws. The guide positioning assembly includes guide columns, a plate diagonal hole positioning clamping plate, and a slide rail mechanism.

[0007] In a further embodiment, the central mechanism is equipped with a gear transmission system. The motor drives the gear transmission system to operate, thereby driving the four screws to lift and lower synchronously, realizing the lifting and lowering control of the upper pressure plate. The upper and lower pressure plates are both carbon steel heavy plates with plate flow channels. Easily oxidized metal plates are placed between the upper and lower pressure plates. The special flow channels of the plate pairs are precisely matched with the flow channels of the upper and lower pressure plates. The guide column ensures the verticality of the lifting and lowering of the upper pressure plate. The plate diagonal hole positioning pressure plate realizes the diagonal positioning of the plate pairs.

[0008] In a further embodiment, the slide rail mechanism includes a slide rail bracket reinforcing rib, a tooling platform support seat, a slide rail support seat, a telescopic adapter plate, a guide rail connecting plate, and a slide rail motor, thereby realizing the position adjustment and fixation of the lower clamping plate.

[0009] In a further embodiment, the rubber sleeve has a temperature resistance range of -40°C to 150°C, can withstand high temperatures of 180°C for short periods, maintains elasticity in low-temperature environments without hardening or becoming brittle, and possesses excellent weather resistance, aging resistance, elastic sealing, and electrical insulation.

[0010] In a further embodiment, the lifting crane adopts a four-axis linkage design to ensure the stability and pressure uniformity of the upper pressure plate lifting process. The clamping force of the upper pressure plate on the plate pair can be adjusted according to the plate material and thickness.

[0011] A method for protective welding of easily oxidized metals in welded heat exchangers using tooling includes the following steps:

[0012] S1: Plate pretreatment, cleaning of easily oxidized metal plates to remove surface oil, oxide scale and impurities, ensuring a clean welding surface;

[0013] S2: Tooling debugging and plate clamping. Adjust the slide rail mechanism of the automatic tooling to make the lower clamping plate in the preset welding position. Place the pre-treated easily oxidized metal plates on the lower clamping plate. Position the clamping plate diagonally through the diagonal holes of the plates to ensure that the special flow channels of the plates are aligned with the flow channels of the lower clamping plate. Start the lifting crane to drive the upper clamping plate to descend and clamp the plates together. The flow channels of the upper clamping plate and the flow channels of the plates are precisely matched.

[0014] S3: Gas protection fixture installation and gas pretreatment. Assemble the cylinder, upper cover, and lower cover of the gas protection fixture. Insert the laser welding torch into the cylinder through the hole in the upper cover, ensuring that the rubber sleeve fits tightly against the upper pressure plate. Introduce rare gas into the gas protection fixture and expel the air from the cylinder, rubber sleeve, and welding channel. The ventilation time is calculated based on the cylinder volume and initial oxygen content to ensure that the oxygen content in the welding area drops below 0.01%.

[0015] S4: Welding parameter settings. Based on the thickness and material of the easily oxidized metal plate, set the welding power, welding speed, and rare gas dynamic flow parameters. The total rare gas consumption includes the initial replacement volume and dynamic gas consumption. The initial replacement volume is calculated based on the cylinder volume, initial oxygen content, and allowable oxygen content. The dynamic gas consumption is determined based on the welding speed, weld length, and flow coefficient.

[0016] S5: Collaborative welding operation, start the laser welding gun and welding robot. The welding robot drives the laser welding gun to move along the preset welding path. During the welding process, rare gas is continuously introduced to maintain the gas protection atmosphere in the welding area. At the bend of the special flow channel, the conical rubber sleeve guides and protects to avoid interference between the laser welding gun and the flow channel, ensuring that the weld is located in the center of the flow channel.

[0017] S6: Post-weld cooling protection. After welding is completed, continue to introduce rare gas until the weld temperature drops below 200℃. Stop the gas supply and wait for the tooling and plates to cool to room temperature. Then, start the lifting crane to raise the upper clamping plate and remove the welded plate pair.

[0018] The technical effects and advantages of this invention are as follows:

[0019] This tooling for protective welding of easily oxidized metals in welded heat exchangers effectively solves problems such as oxidation, hydrogen embrittlement, and cracking in the welding of easily oxidized metals through full-cycle gas protection and precise parameter control. The weld is silver-white in color, has a smooth appearance, and meets the mechanical properties (toughness, fatigue strength, etc.) and the requirements for use of welded heat exchangers in harsh environments.

[0020] The sliding rail mechanism and flow channel adaptation design of the automatic clamping tooling can be compatible with easily oxidized metal plates of different specifications and special flow channels. The conical rubber sleeve of the gas protection tooling achieves effective gas protection and anti-interference of the gun head when the special flow channel bends, thus broadening the application range of the tooling.

[0021] The tooling structure is simple and highly automated. The plate clamping, positioning and welding processes are all semi-automated or fully automated, which reduces the intensity of manual operation. The amount of rare gas used is precisely calculated and controlled to avoid waste and reduce production costs. The welding speed can be adjusted according to production needs, taking into account both welding quality and production efficiency.

[0022] All components of the tooling are made of heat-resistant, wear-resistant, and corrosion-resistant materials to ensure service life in long-term welding environments. The four-axis linkage lifting crane and guide positioning components ensure the stability of plate clamping and welding accuracy, reducing welding defects caused by tooling failure. This tooling for protective welding of easily oxidized metals in welded heat exchangers achieves efficient and high-quality protective welding of easily oxidized metals through the collaborative design of gas protection tooling and automatic clamping tooling, combined with precise gas parameter control and intelligent welding strategies. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the gas protection tooling of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of the lower cover of the present invention;

[0026] Figure 3 This is a front view of the automated clamping fixture of the present invention;

[0027] Figure 4 This is a top view of the automatic clamping fixture of the present invention.

[0028] In the diagram: 1. Cylinder body; 2. Upper cover; 3. Lower cover; 4. Rubber sleeve; 5. Upper clamping plate; 6. Lower clamping plate; 7. Slide rail bracket reinforcing rib; 8. Tooling platform support seat; 9. Plate diagonal hole positioning clamping plate; 10. Guide column; 11. Slide rail support seat; 12. Telescopic adapter plate; 13. Guide rail connecting plate; 14. Lifting crane; 15. Slide rail motor. Detailed Implementation

[0029] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0030] Unless otherwise defined, the directions mentioned herein, such as up, down, left, right, front, back, inside, and outside, are based on the directions shown in the figures of this invention, and are explained here together.

[0031] This invention provides, for example Figure 1-4 The tooling shown is for protective welding of easily oxidized metals in welded heat exchangers, including a gas protection tooling and an automated clamping tooling. The gas protection tooling includes a cylinder 1, an upper cover 2, a lower cover 3, and a rubber sleeve 4.

[0032] The cylinder 1 is made of stainless steel round tube or seamless steel tube, with its length determined according to the optimal welding distance to ensure that the laser energy output from the laser welding gun head is precisely applied to the weld area. The upper cover 2 is a round plate matching the size of the cylinder 1, with a through hole in the center matching the diameter of the laser welding gun head. This ensures that the laser welding gun head can be easily inserted while reducing gas leakage. The lower cover 3 is a round plate of a specific thickness, with evenly distributed round holes of 2mm accuracy using precision machining. The number and distribution of the round holes are determined through gas flow simulation and experimental verification to ensure that the rare gas ejected from the round holes can evenly cover the welding area of ​​the easily oxidized metal plate, forming a stable gas protective film, while simultaneously controlling the gases generated during the welding process. The air and welding fumes are quickly discharged to avoid secondary pollution. The rubber sleeve 4 is made of EPDM (ethylene propylene diene monomer rubber), which has a wide temperature range (-40℃ to 150℃, short-term tolerance to 180℃), good elasticity, strong sealing, excellent weather resistance and aging resistance, and low cost. Compared with NBR (nitrile rubber) and SBR (styrene-butadiene rubber), it is more suitable for the scenario of this invention. The rubber sleeve 4 is designed with a conical structure, which can constrain the gas flow and improve the concentration of gas protection. On the other hand, at the bend of the special flow channel, it can serve as an intermediate transfer medium to avoid interference and collision between the laser welding gun head and the flow channel, while ensuring that the weld is always within the gas protection range.

[0033] The automated clamping fixture is used to stably clamp, position, and precisely fit the flow channel of easily oxidized metal plates, providing a stable foundation for welding operations. Its structure includes a lifting crane 14, an upper clamping plate 5, a lower clamping plate 6, and a guide and positioning assembly. The lifting crane 14 adopts a four-axis linkage design, consisting of a motor, a central mechanism, and four screws. The central mechanism has a built-in gear transmission system; the motor drives the gears, which in turn drive the four screws to lift synchronously, achieving smooth lifting of the upper clamping plate 5. The four-axis linkage design ensures even force distribution on the upper clamping plate 5, preventing plate... The plates deform due to uneven stress. The clamping force can be adjusted according to the material and thickness of the plates to meet the welding requirements of different specifications of plates. The upper clamping plate 5 and the lower clamping plate 6 are both made of carbon steel heavy plates. Their surfaces are processed with special flow channels that match the easily oxidized metal plates. After the plates are placed between the upper clamping plate 5 and the lower clamping plate 6, their flow channels are precisely matched with the flow channels of the clamping plates, ensuring that the weld is always located in the center of the flow channel during the welding process, thus improving the welding accuracy. The weight and structural design of the carbon steel heavy plates can effectively absorb the heat during the welding process and reduce plate deformation.

[0034] The guiding and positioning assembly includes guide posts 10, plate diagonal hole positioning clamping plates 9, and a slide rail mechanism. The guide posts 10 are installed at the four corners of the upper clamping plate 5 and the lower clamping plate 6 to ensure the verticality of the upper clamping plate 5 during the lifting process and avoid deviation. The plate diagonal hole positioning clamping plates 9 achieve precise positioning of the plate pairs by cooperating with the diagonal holes of the plates to prevent the plates from shifting during welding. The slide rail mechanism consists of slide rail bracket reinforcing ribs 7, tooling platform support base 8, slide rail support base 11, telescopic adapter plate 12, guide rail connecting plate 13, and slide rail motor 15. It can realize the horizontal position adjustment of the lower clamping plate 6, facilitate the clamping of plates and the adaptation to the welding path, and improve the versatility of the tooling.

[0035] Based on the above tooling, the welding method provided by the present invention includes the following steps:

[0036] S1: Plate pretreatment: A combination of mechanical grinding and chemical cleaning is used to remove oil, scale, dust and other impurities from the surface of easily oxidized metal plates to ensure that the welding surface is clean and free of contaminants, and to avoid impurities affecting the welding quality. The treated plates need to be welded within a short time to prevent re-oxidation.

[0037] S2: Tooling debugging and plate clamping: Start the slide rail motor 15, adjust the horizontal position of the lower clamping plate 6 to align it with the preset path of the welding robot, place the pre-processed plate pair on the lower clamping plate 6, insert the clamping plate 9 through the diagonal hole of the plate to achieve precise positioning of the plate pair, start the lifting crane 14, the motor drives the gear transmission system to run, drive the four screws to descend synchronously, and the upper clamping plate 5 descends smoothly to clamp and fix the plate pair, ensuring that the flow channel of the plate pair is completely matched with the flow channel of the upper and lower clamping plates 6 without deviation;

[0038] S3: Gas protection fixture installation and gas pretreatment: Assemble and fix cylinder 1, upper cover 2, and lower cover 3. Insert the laser welding gun tip into cylinder 1 through the through hole of upper cover 2, so that rubber sleeve 4 fits tightly against the surface of upper pressure plate 5 to ensure gas sealing effect. Introduce argon (rare gas) into the gas protection fixture to perform gas replacement and expel air from cylinder 1, rubber sleeve 4 and welding channel. The gas introduction time is calculated and determined based on the volume of cylinder 1, initial oxygen content (21%) and allowable oxygen content (0.01%) to ensure that the oxygen content in the welding area drops below 0.01% to avoid weld oxidation during welding.

[0039] S4: Welding parameter settings: Based on the thickness and material characteristics of the easily oxidized metal plates, and combined with experimental data, set the welding parameters: Welding power: For lap welding of titanium plates with a thickness of 0.7mm, the welding power is set to 650-660W. For other easily oxidized metal plates with a thickness of ≤3mm, adjust the power range according to the thermal conductivity and melting point of the material.

[0040] Welding speed: The welding speed can be adjusted in the range of 11-33 mm / min when lap welding titanium plates with a thickness of 0.7 mm, depending on the weld width requirements. The slower the speed, the wider the weld (3 mm weld at 11 mm / min and 2 mm weld at 33 mm / min).

[0041] Rare gas flow rate: Total gas consumption includes the initial replacement volume and dynamic gas consumption. For example: two titanium plates with a thickness of 0.7 mm are overlaid and welded at a welding power of 660W. The volume of cylinder 1 is v_cylinder. The initial oxygen content is 21%, diluted to the allowable oxygen content of 0.01%. The theoretical replacement volume of argon gas required is V_Ar. The welding speed is v = 22 mm / min. Taking K1 = 0.8, the weld length is 100 mm. The total volume of argon gas lost during welding is V_loss. The volume of the protected area, i.e., the volume of cylinder 1 in this tooling, is v = π × (0.3). 5)²×0.3≈0.11L, initial replacement volume VAr=0.11×21%(21% / 0.01%-1)≈23L, dynamic flow rate and total consumption: v=22mm / min, K1=0.8, gas flow rate Q=0.8×22×70=1232mm³ / min (converted to 1.2L / min), weld length is 100mm, welding time is t=4min, then dynamic gas consumption V=4×1.2=4.8L, total gas consumption is V=23+4.8=27.8L;

[0042] S5: Collaborative Welding Operation: Start the laser welding torch and welding robot. The welding robot moves along the preset path and monitors the weld position and gas protection status in real time through the vision recognition module. At the bend of the special flow channel, the conical rubber sleeve 4 moves synchronously with the laser welding torch and always fits the upper clamping plate 5 to avoid interference between the torch and the flow channel. At the same time, it ensures that rare gas continuously covers the weld. Argon gas is continuously introduced during the welding process to maintain the protective atmosphere of the welding area and to remove welding fumes and residual air in time. If the vision recognition module detects weld displacement or abnormal gas protection, it automatically adjusts the welding speed, gas flow rate or welding path to ensure welding quality.

[0043] S6: Post-weld cooling protection and inspection: After welding, continue to introduce argon gas until the weld temperature drops below 200℃, then stop the gas supply to prevent the weld from oxidizing and becoming embrittled by contact with air during cooling. After the tooling and plates have cooled to room temperature, start the lifting crane 14 to lift the upper clamping plate 5, remove the welded plates, and perform a visual inspection of the weld. The weld color should be silver-white, without oxidation discoloration, cracks, pores, or other defects. For plates with a thickness ≤3mm, the weld width should be controlled within the range of 2-3mm. Perform mechanical property testing on the weld to ensure that its toughness, fatigue strength, and other indicators meet the requirements for use in welded heat exchangers.

[0044] All standard parts used in this invention can be purchased from the market, and irregularly shaped parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts, and equipment all adopt conventional models in the prior art. In addition, the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here. The control method of this invention is through a controller. The control circuit of the controller can be implemented by those skilled in the art through simple programming. It should be noted that the electrical components mentioned in this invention have been sorted according to the actual situation during manufacturing, so as not to cause the wire harness to become tangled or affect the operation. The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0045] In the description of this invention, it should be understood that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description, and is not intended to 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 invention.

[0046] Working principle:

[0047] The tooling for protective welding of easily oxidized metals in welded heat exchangers first involves adjusting the lower clamping plate 6 to the preset welding position via the slide rail mechanism of the automated tooling. The pre-treated easily oxidized metal plates are precisely positioned by the clamping plate 9 through the diagonal holes. The four-axis linkage lifting crane 14 drives the upper clamping plate 5 to descend smoothly. Utilizing the flow channel structure that precisely matches the plate pair and the adjustable clamping force, the plate pair is firmly clamped. At the same time, the carbon steel heavy plate absorbs the welding heat, and the guide column 10 ensures verticality, preventing the plates from shifting or deforming.

[0048] Subsequently, after the gas protection fixture is assembled, the rubber sleeve 4 tightly fits against the upper clamping plate 5 to form a sealed space. Rare gas is introduced to replace the air in the cylinder 1, rubber sleeve 4, and welding channel, reducing the oxygen content in the welding area to below 0.01%. The conical EPDM rubber sleeve 4 not only restricts gas flow to ensure concentrated protection but also avoids interference between the laser welding torch and the bends in the special flow channel. During welding, the welding power, speed, and rare gas dynamic flow parameters set according to the plate material and thickness take precise effect. The welding robot drives the laser welding torch along the preset path, and the continuously introduced rare gas maintains the protective atmosphere in the welding area. After welding, gas continues to be introduced until the weld temperature is below 200°C to prevent oxidation during the cooling stage. Finally, through the structural adaptation of each component and the full-cycle parameter control, problems such as oxidation, hydrogen embrittlement, and cracking in the welding of easily oxidized metals are avoided, achieving efficient and precise protective welding.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A tooling for protective welding of easily oxidized metals in welded heat exchangers, comprising a gas protection tooling and an automated clamping tooling, characterized in that: The gas protection fixture includes a cylinder (1), an upper cover (2), a lower cover (3), and a rubber sleeve (4). The cylinder (1) is a stainless steel round tube or seamless steel tube of a specific size, and its length is set to ensure that the laser welding gun head is in the optimal welding position. The upper cover (2) is a round plate that matches the cylinder (1), and its upper part has a hole that matches the size of the laser welding gun head for the laser welding gun head to extend into. The lower cover (3) is a round plate of a specific thickness, and its surface is evenly distributed with round holes of a precision of 2mm. The rubber sleeve (4) is made of EPDM (ethylene propylene diene monomer rubber) material and has a conical structure. It is used to seal rare gases and as an intermediate transfer medium for special flow channel bends. The automated clamping fixture includes a lifting crane (14), an upper clamping plate (5), a lower clamping plate (6), and a guide positioning assembly. The lifting crane (14) includes a motor, a central mechanism, and four screws. The guide positioning assembly includes a guide column (10), a plate diagonal hole positioning clamping plate (9), and a slide rail mechanism.

2. The tooling for protective welding of easily oxidized metals in welded heat exchangers according to claim 1, characterized in that: The central mechanism is equipped with a gear transmission system. The motor drives the gear transmission system to operate, thereby driving the four screws to lift and lower synchronously, realizing the lifting and lowering control of the upper pressure plate (5). The upper pressure plate (5) and the lower pressure plate (6) are both carbon steel heavy plates with plate flow channels. Easily oxidized metal plates are placed between the upper pressure plate (5) and the lower pressure plate (6). The special flow channels of the plate pairs are precisely matched with the flow channels of the upper pressure plate (5) and the lower pressure plate (6). The guide column (10) ensures the verticality of the lifting and lowering of the upper pressure plate (5). The plate diagonal hole positioning pressure plate (9) realizes the diagonal positioning of the plate pairs.

3. The tooling for protective welding of easily oxidized metals in welded heat exchangers according to claim 1, characterized in that: The slide rail mechanism includes a slide rail bracket reinforcing rib (7), a tooling platform support seat (8), a slide rail support seat (11), a telescopic adapter plate (12), a guide rail connecting plate (13), and a slide rail motor (15), which realizes the position adjustment and fixation of the lower pressing plate (6).

4. The tooling for protective welding of easily oxidized metals in welded heat exchangers according to claim 1, characterized in that: The rubber sleeve (4) has a temperature range of -40℃ to 150℃, can withstand high temperatures of 180℃ for short periods, maintains elasticity in low-temperature environments, does not harden or become brittle, and has excellent weather resistance, aging resistance, elastic sealing and electrical insulation.

5. The tooling for protective welding of easily oxidized metals in welded heat exchangers according to claim 1, characterized in that: The lifting crane (14) adopts a four-axis linkage design to ensure the stability and pressure uniformity of the upper pressing plate (5) during the lifting process. The pressing force of the upper pressing plate (5) on the plate pair can be adjusted according to the plate material and thickness.

6. A method for protective welding of easily oxidized metals in a welded heat exchanger based on the tooling described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Plate pretreatment, cleaning of easily oxidized metal plates to remove surface oil, oxide scale and impurities, ensuring a clean welding surface; S2: Tooling debugging and plate clamping, adjust the slide rail mechanism of the automatic tooling to make the lower clamping plate (6) in the preset welding position, place the pre-treated easily oxidized metal plate pair on the lower clamping plate (6), and use the plate diagonal hole positioning clamping plate (9) for diagonal positioning to ensure that the special flow channel of the plate pair is aligned with the flow channel of the lower clamping plate (6), start the lifting crane (14), drive the upper clamping plate (5) to descend, and clamp and fix the plate pair, so that the flow channel of the upper clamping plate (5) is precisely matched with the flow channel of the plate pair; S3: Gas protection fixture installation and gas pretreatment. Assemble the cylinder (1), upper cover (2), and lower cover (3) of the gas protection fixture. Insert the laser welding gun head through the hole of the upper cover (2) into the cylinder (1) so that the rubber sleeve (4) fits tightly against the upper clamping plate (5). Introduce rare gas into the gas protection fixture and exhaust the air in the cylinder (1), rubber sleeve (4), and welding channel. The ventilation time is calculated based on the volume of the cylinder (1) and the initial oxygen content to ensure that the oxygen content in the welding area drops below 0.01%. S4: Welding parameter setting. Based on the thickness and material of the easily oxidized metal plate, set the welding power, welding speed, and rare gas dynamic flow parameters. The total rare gas consumption includes the initial replacement volume and dynamic gas consumption. The initial replacement volume is calculated based on the cylinder (1) volume, initial oxygen content, and allowable oxygen content. The dynamic gas consumption is determined based on the welding speed, weld length, and flow coefficient. S5: Collaborative welding operation, start the laser welding gun and welding robot, the welding robot drives the laser welding gun to move along the preset welding path, rare gas is continuously introduced during the welding process to maintain the gas protection atmosphere in the welding area, at the bend of the special flow channel, through the guiding and protective effect of the conical rubber sleeve (4), the interference between the laser welding gun and the flow channel is avoided, and the weld is located in the center of the flow channel. S6: Post-weld cooling protection. After welding, continue to introduce rare gas until the weld temperature drops below 200°C. Stop the gas supply and wait for the tooling and plates to cool to room temperature. Then start the lifting crane (14) to lift the upper clamping plate (5) and take out the welded plates.

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