Friction preheating device for copper alloy circular weld joint and using method

Abstract

The invention relates to a friction preheating device for a copper alloy circular weld joint and a using method, the friction preheating device comprises preheating welding equipment and a positioner, the preheating welding equipment is provided with a welding gun and a friction preheating part, the friction preheating part is located in front of the welding gun along a welding track, the positioner is used for supporting a to-be-welded part, and the welding gun is used for welding the to-be-welded part. And the to-be-welded part is driven to rotate. A friction preheating piece located in front of a welding gun is arranged on preheating welding equipment, a to-be-welded area is accurately preheated in a friction heat generation mode, it is ensured that the to-be-welded area is evenly heated to the designated temperature, and a good temperature condition is created for subsequent multi-pass and multi-layer surfacing of the welding gun; the defects of poor weld fusion, air holes, deformation and the like caused by high heat conductivity of the copper alloy can be reduced, and the welding quality and efficiency are improved. And the positioner drives the to-be-welded part to rotate, so that the preheating and welding processes can be continuously and stably carried out, and the device is particularly suitable for welding operation of large copper alloy components.

Description

Technical Field

[0001] This invention relates to the field of welding technology, specifically to a friction preheating device and its method of use for copper alloy circular welds. Background Technology

[0002] Traditional MIG (metal inert-gas welding) automated welding equipment often encounters problems such as poor weld fusion, porosity, and deformation when welding large copper alloy components due to the high thermal conductivity of the material. For large copper alloy components, without preheating, the welding heat is rapidly dissipated due to the material's extremely high thermal conductivity, causing a sharp increase in the temperature gradient between the weld zone and the base metal, leading to a series of defects such as insufficient penetration, lack of fusion, and substandard weld formation. To solve these problems, the common practice is to place the copper alloy component and welding equipment as a whole into a heating furnace for heating. This method suffers from high energy consumption and a poor working environment. Alternatively, preheating using a flame gun for localized baking results in uneven preheating temperature distribution and low preheating efficiency. Summary of the Invention

[0003] This invention addresses existing technical problems by providing a friction preheating device and its usage method for copper alloy circular welds.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a friction preheating device for a circular weld of copper alloy, comprising a preheating welding equipment and a positioner, wherein a welding torch and a friction preheating component are installed on the preheating welding equipment, the friction preheating component is located in front of the welding torch along the welding trajectory, and the positioner is used to support the workpiece to be welded and drive the workpiece to be welded to rotate.

[0005] Based on the above technical solution, the present invention can be further improved as follows: Furthermore, the friction preheating element is rotatably mounted on the welding equipment.

[0006] The beneficial effect of adopting the above-mentioned further solution is that, through the high-speed rotation of the friction preheating component and the intense friction between the friction preheating component and the workpiece surface, mechanical energy is efficiently converted into heat energy. This method has a concentrated heat source, a rapid heating rate, and the heat is directly applied to the area to be welded. The thermal efficiency is much higher than that of traditional conduction heating or radiation heating, and it can quickly raise the copper alloy workpiece to be welded to the required welding preheating temperature.

[0007] Furthermore, the friction preheating component includes a preheating shoulder at the lower end, which is in contact with the welding plane of the component to be welded.

[0008] The beneficial effect of adopting the above-mentioned further solution is that, as a key part of the friction preheating component that directly contacts the workpiece to be welded, its design directly affects the preheating effect and stability. The planar contact form can ensure the formation of a stable friction interface with the plane to be welded, ensuring the uniformity of heat generation and avoiding problems such as local overheating or insufficient preheating caused by poor contact.

[0009] Furthermore, the downward axial pressure of the friction preheating component is 40KN-55KN.

[0010] The beneficial effect of adopting the above-mentioned further solution is that this axial pressure range ensures sufficient positive pressure between the friction preheating component and the workpiece to generate stable frictional heat. Insufficient pressure will lead to slippage and insufficient heat generation; excessive pressure may damage the workpiece surface or increase the equipment load. This pressure range ensures both efficient heat generation and protection of the workpiece and equipment, guaranteeing the stability of the preheating process.

[0011] Furthermore, the rotational angular velocity of the friction preheating component is 20 rad / s-35 rad / s.

[0012] The beneficial effect of adopting the above-mentioned further solution is that the rotational angular velocity directly affects the power of frictional heat generation and the rate of temperature rise. This rotational speed range is matched with the aforementioned axial pressure, enabling the copper alloy weld area to be heated to the set temperature in a short time, while avoiding the problems of material overheating and burning due to excessive rotational speed or low heating efficiency due to excessively low rotational speed.

[0013] Furthermore, the radius of the preheating shoulder is 15mm-25mm.

[0014] The beneficial effect of adopting the above-mentioned further solution is that the size of the preheating shoulder radius determines the contact area between the preheating shoulder and the workpiece to be welded, thereby affecting the penetration depth and concentration of heat.

[0015] Furthermore, the friction preheating component forms a preheating area with a diameter of φ80mm-φ100mm on the workpiece to be welded.

[0016] The beneficial effect of adopting the above-mentioned further scheme is that the preheating zone diameter range is wide enough to effectively reduce the temperature gradient during welding, reduce welding stress and deformation, and prevent cold cracking; at the same time, it is not too wide, avoiding unnecessary energy waste, and achieving the best balance between preheating effect and energy efficiency.

[0017] Furthermore, the surface roughness Ra of the preheated shoulder is 10μm-12.5μm.

[0018] The beneficial effect of adopting the above-mentioned further solution is that this roughness range can provide a suitable coefficient of friction, which not only ensures the heat generation efficiency, but also avoids severe scratches on the workpiece surface due to excessive roughness, or insufficient friction and difficulty in heat generation due to excessive smoothness. This range helps to obtain a high-quality preheated surface.

[0019] Furthermore, the friction preheating element is retractably mounted on the preheating welding equipment.

[0020] The beneficial effect of adopting the above-mentioned further solution is that, during the preheating stage, the friction preheating component extends to contact the workpiece for heating; during the welding stage or when movement is required, the friction preheating component can be retracted to avoid interference with the welding torch or workpiece. The retractable design of the friction preheating component enables seamless switching between preheating and welding operations, improving the convenience and safety of operation.

[0021] Compared with existing technologies, the beneficial effects of the friction preheating device of this invention are as follows: By setting a friction preheating component in front of the welding torch on the preheating welding equipment, the area to be welded is precisely preheated by frictional heat generation, ensuring that the area to be welded is uniformly heated to the specified temperature. This creates favorable temperature conditions for subsequent multi-pass and multi-layer welding by the welding torch, helping to reduce defects such as poor weld fusion, porosity, and deformation caused by the high thermal conductivity of copper alloys, thus improving welding quality and efficiency. The targeted preheating of the area to be welded by the friction preheating component effectively solves the problem of high energy consumption caused by placing the welding equipment and the workpiece to be welded together in a heating furnace for overall heating in existing technologies, and also solves the problem of low preheating efficiency caused by using a flame torch for preheating in existing technologies. Simultaneously, the positioner drives the workpiece to be welded to rotate, enabling the preheating and welding processes to proceed continuously and stably, making it particularly suitable for welding large copper alloy components.

[0022] The present invention also provides a method for using the above-mentioned friction preheating device for copper alloy circular welds, comprising the following steps: Preheating: The workpiece to be welded is mounted on the positioner, which drives the workpiece to be welded to rotate. At the same time, the friction preheating component comes into contact with the area to be welded of the workpiece and preheats the area to be welded to a specified temperature through frictional heat generation. Welding: The welding torch performs multi-pass, multi-layer welding on the area to be welded of the workpiece.

[0023] The beneficial effects of the method of this invention are as follows: By organically combining friction preheating with the welding process, this method achieves precise and efficient preheating of the copper alloy area to be welded. During the preheating stage, the positioner drives the workpiece to be welded to rotate stably, ensuring that the friction preheating component can uniformly and continuously heat the area to be welded. Compared with traditional static preheating, this dynamic preheating method results in a more uniform heat distribution, avoiding localized overheating or insufficient preheating. The friction preheating component generates heat through friction with the area to be welded, quickly preheating the area to the specified temperature, providing a good temperature foundation for subsequent welding. The metal to be welded receives sufficient heat to achieve a good fusion state, avoiding insufficient penetration and incomplete fusion due to rapid heat loss. During the welding stage, the welding torch performs multi-pass, multi-layer welding on the fully preheated area. Due to the sufficient and uniform preheating, the weld fusion effect is better, reducing welding defects such as porosity and incomplete fusion, thus improving welding quality and efficiency. Meanwhile, this method is easy to operate, and the preheating and welding processes are closely integrated, which is conducive to realizing automated welding operations and reduces the difficulty and labor intensity of manual operation. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the friction preheating device of the present invention; Figure 2 This is a schematic diagram of the welding torch, friction preheating component, and workpiece to be welded according to the present invention; Figure 3 This is a schematic diagram of the friction preheating component of the present invention.

[0025] The reference numerals in the attached drawings are as follows: 10, preheating welding equipment; 11, welding torch; 12, friction preheating component; 121, preheating shoulder; 20. Positioner; 21. Fixture 1; 22. Fixture 2; 30. Part 1 to be welded; 40. Part 2 to be welded. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "vertical," "upper," "lower," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention 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 the invention.

[0028] like Figures 1 to 3 As shown, this invention discloses a friction preheating device for a circular weld of copper alloy, including a preheating welding device 10 and a positioner 20. The preheating welding device 10 is equipped with a welding torch 11 and a friction preheating component 12. The friction preheating component 12 is located in front of the welding torch 11 along the welding trajectory. The positioner 20 is used to support the workpiece to be welded and drive the workpiece to be welded to rotate. The workpiece to be welded is workpiece 30 and workpiece 40. The positioner 20 is provided with a clamp 21 and a clamp 22 to fix and clamp the workpiece 30 and workpiece 40 to ensure stability during rotation and welding. In this embodiment, the weld between workpiece 30 and workpiece 40 is annular.

[0029] The friction preheating component 12 is rotatably mounted on the welding equipment 10 around its own axis. The friction preheating component 12 includes a preheating shoulder 121 at the lower end, which contacts the welding plane. The lower end of the friction preheating component 12 is provided with a conical platform, and the preheating shoulder 121 is a plane provided at the lower end of the conical platform. The size of the lower end of the conical platform is small. Therefore, compared with the cylindrical structure, the conical platform structure can avoid interference between the friction preheating component 12 and the workpiece to be welded, ensure that the preheating shoulder 121 is in full contact with the surface to be welded, ensure that the heat can be concentrated on the part to be welded, and improve the preheating effect.

[0030] The friction preheating component 12 is retractably mounted on the preheating welding equipment 10. After preheating, it can be directly retracted to a preset position to avoid interfering with subsequent welding processes. For example, the friction preheating component 12 is mounted on a retractable hydraulic rod, thereby driving the friction preheating component 12 to retract and move.

[0031] This invention also discloses a method for using a friction preheating device for copper alloy circular welds, comprising the following steps: 1. Welding preheating The pre-processed large copper alloy parts to be welded, namely part 30 and part 40, are fixed on the positioner 20 using clamps 21 and 22, respectively. Clamps 21 and 22 are jaws. The preheating welding equipment 10 is then started, precisely aligning the friction preheating element 12 with the welding areas of parts 30 and 40. The friction preheating element 12 is controlled to move downwards, bringing the preheating shoulder 121 into contact with the welding plane. The positioner 20 is then started, driving the parts to be welded to rotate. Simultaneously, the friction preheating element 12 rotates around its own axis, contacting the welding area of ​​the workpiece and generating heat through friction. The welding area is preheated to the specified temperature. The duration of the preheating process is adjusted according to the size of the copper parts.

[0032] During operation, the axial pressure applied by the friction preheating component 12 is controlled at 40KN-55KN, the rotational angular velocity is controlled at 20rad / s-35rad / s, the radius of the preheating shoulder 121 is controlled at 15mm-25mm, and the surface roughness Ra of the preheating shoulder 121 is controlled at 10μm-12.5μm. For example, the surface roughness Ra can be 10.5μm, 11μm, 11.5μm or 12μm. The friction preheating component 12 forms a circular preheating area with a diameter of φ80mm-φ100mm on the workpiece to be welded, ensuring the preheating effect of the area to be welded.

[0033] 2. Welding Once the area to be welded reaches the set temperature, the friction preheating component 12 is controlled to contract, separating it from the surface of the component to be welded. The welding torch 11 begins operation. During welding, the positioner 20 drives the large copper alloy component to rotate at a uniform speed, achieving continuous welding of the circumferential weld. The rotation speed of the positioner 20 is determined according to the performance of the base material and process requirements. The welding torch 11 performs multi-pass, multi-layer cladding welding on the area to be welded. After each layer is completed, flux is evenly sprinkled on the surface of the weld layer, and welding continues until the area to be welded is completed according to the preset path. Welding is performed directly after preheating, which minimizes heat loss and ensures that the molten pool is in a stable temperature field during welding. The multi-pass, multi-layer cladding welding method, combined with the use of flux, further optimizes the metallurgical properties of the weld metal. The gas generated by the decomposition of flux at high temperatures effectively protects the molten pool, preventing the intrusion of gases such as oxygen and nitrogen in the air to form pores. At the same time, the flux also plays a role in deoxidation and desulfurization, improving the purity and mechanical properties of the weld. Applying flux after each weld layer provides insulation and heat preservation for subsequent weld layers, helps control the cooling rate of the weld area, reduces the generation of welding stress, and thus reduces the risk of weld cracking.

[0034] 3. Post-weld treatment After the welding process is completed, the welded area is leveled and polished to complete the welding operation of the entire copper alloy circular weld.

[0035] Example 1 1. Welding Preheating: The parts to be welded are fixed on the positioner 20 using a fixture. The preheating welding equipment 10 is started, ensuring that the friction preheating component 12 is precisely aligned with the area to be welded, and the preheating shoulder 121 contacts the welding plane. The positioner 20 is started to drive the parts to be welded to rotate, while the friction preheating component 12 rotates around its own axis to preheat the area to be welded. The axial force of the friction preheating component 12 is 30KN, the rotational angular velocity is 30rad / s, and the radius of the preheating shoulder 121 is 20mm. By controlling the size of the preheating shoulder 121, a circular preheating zone with a diameter of φ80mm is formed on the parts to be welded. The total thickness of the parts to be welded is 80mm, the preheating time is 60s, and the final average temperature of the preheating zone reaches 300℃. The temperature of the preheating zone can be measured by a temperature sensor such as an infrared temperature sensor. The total weight of the parts to be welded (part 1 30 and part 2 40) is 1600Kg, and the energy utilization efficiency is 63.5%.

[0036] The efficiency calculation method for preheating welding equipment 10 is as follows: Heating efficiency (energy utilization efficiency) η = (effective heat consumed by the preheating zone Q1 / total energy output by the friction preheating component 12 Q2) × 100%; Given fixed parameters: the density ρ of the copper alloy is 8.96 × 10⁻⁶. -6 The specific heat capacity of copper alloy is 0.385 kJ / (kg·℃). Preheating area: A circular area with a diameter of φ80mm, i.e., radius r=40mm; The total thickness of the welded part is h=80mm (the thickness of the preheating zone is the same as the thickness of the workpiece). Initial temperature T0: room temperature 25℃; Final preheating temperature T: 300℃ Preheating time: 60 seconds; (1) Temperature rise in the preheating zone: T1 = T - T0; T0 - initial temperature of the preheating zone, °C; T - final temperature of the preheating zone, °C; (2) Calculate the mass of the preheated zone according to the following formula: ① Calculate the area of ​​the preheating zone: A = π × r²; Where A is the area of ​​the preheating zone, in mm 2 ;r - radius of the preheating zone, mm; Substituting the data above: A = 3.14 × 40² = 5024 mm² ② Calculate the volume of the preheating zone: V = A × h; where, V - volume of the preheating zone, mm 3 h - Thickness in the preheating zone, mm; Substituting the data above: V = 5024 × 80 = 401920 mm³ ③ Calculate the mass of the preheating zone: m1 = ρ × V; m1 - mass of the preheating zone, kg; ρ - density of the copper alloy; m1 = 8.96 × 10 -6 ×401920≈3.60kg (3) Heat the preheating zone to the final temperature. The effective heat of the preheating zone is Q1, Q1=m1×c×T1=m1×c×(T-T0), c-specific heat capacity; Q1-heat consumed by the preheating zone, KJ; Q1 = 3.60 × 0.385 × 275 ≈ 381.2 KJ (4) The output energy of the friction preheating component 12 is Q2, Q2=2 / 3×μ×F×R×ω×t; μ-friction coefficient; F-axial force, N; t-preheating time, s; R-shoulder radius, m; ω-angular velocity, rad / s; Known parameters: roughness is 10-12 μm, friction coefficient μ is 0.4-0.7. In this embodiment, μ=0.5, F=50000N, R=0.02m, ω=30rad / s, t=60s.

[0037] The energy is calculated as Q2: Q2 = 2 / 3 × μ × F × R × ω × t = 2 / 3 × 0.5 × 50000 × 0.02 × 30 × 60 = 600 kJ; The energy utilization efficiency is then η1, where η1 = Q1 / Q2 × 100% = 63.5%. 2. Welding: After the preheating area reaches 300°C, the friction preheating component 12 is retracted upwards. The positioner 20 drives the large copper alloy components, namely the first part to be welded 30 and the second part to be welded 40, to rotate at a uniform speed. The welding torch 11 performs multi-pass, multi-layer surfacing welding on the area to be welded between the first part to be welded 30 and the second part to be welded 40. Flux is applied after each layer of welding is completed until the welding is completed.

[0038] 3. Post-weld treatment: Level and polish the welded area.

[0039] Example 2 1. Welding preheating: Fix the parts to be welded on the positioner 20 using a fixture, start the preheating welding equipment 10, so that the friction preheating part 12 is precisely aligned with the area to be welded, and the preheating shoulder 121 contacts the welding plane.

[0040] The positioner 20 is started to drive the workpiece to be welded to rotate. At the same time, the friction preheating component 12 rotates around its own axis to preheat the area to be welded. The axial force of the friction preheating component 12 is 50KN, the rotational angular velocity is 30rad / s, the radius of the preheating shoulder 121 is 20mm, forming a circular preheating zone with a diameter of φ80mm. The total thickness of the workpiece to be welded is 80mm, the preheating time is 120s, and the set temperature of the preheating zone is 575℃ when the average temperature of the preheating zone reaches 575℃. The total weight of the workpiece to be welded 30 and the workpiece to be welded 40 is 1600Kg, and the energy utilization efficiency is 63.5%. The calculation method is described in Example 1.

[0041] 2. Welding: After the preheated area reaches 575°C, the friction preheating part 12 is retracted upwards. When the friction part 12 separates from the part to be welded, the positioner 20 drives the large copper alloy component to rotate at a uniform speed. The welding torch 11 performs multi-pass, multi-layer welding on the area to be welded. Flux is applied after each layer of welding is completed until the welding is completed.

[0042] 3. Post-weld treatment: Level and polish the welded area.

[0043] Comparative Example 1 The pre-processed parts 30 and 40 to be welded were fixed on the positioner 20. An acetylene flame was used for heating, precisely aiming the flame at the area to be welded. The preheating zone formed by the flame was a circular area with a diameter of φ80mm. The total weight of the parts to be welded was 1600Kg. The preheating zone was heated to 300℃, and the flame needed to be continuously heated for 420s. During this process, the total energy output was 3592KJ, with an energy utilization efficiency of only 10.6%. Subsequent welding and post-weld processing steps were the same as in Example 1.

[0044] The heat generated by burning acetylene is calculated using the following formula: Q3 = n × |Δc H°|; Where Q3 is the heat released by the combustion of acetylene, in kJ; n is the amount of acetylene, in mol. |ΔcH°| represents the heat released by the complete combustion of 1 mol of acetylene, |ΔcH°| = 1299 kJ; Because: n= m - mass of acetylene, g; M - molar mass of acetylene, 26.04 g / mol; The mass of acetylene consumed is m = 72g; Therefore, Q3 = n × |Δc H° | = ×∣ΔcH°∣= ×1299=3592kJ.

[0045] Because the size of the preheating zone and the final heating temperature in this comparative example are the same as in Example 1, the heat required for the preheating zone is also the same as in Example 1, which is Q1; Then, in this comparative example, the energy utilization efficiency η2 is given by η2 = Q1 / Q3 × 100% = ×100%=10.6%; The test data are shown in Table 1: Table 1. Experimental data of Examples 1-2 and Comparative Example 1

[0046] Comparative data from Examples 1, 2, and 1 show that the present invention achieves preheating of copper alloy circular welds through frictional heating, with energy utilization efficiency far exceeding that of traditional flame heating methods. Furthermore, the preheating time is significantly shortened, enabling rapid heating of the area to be welded to the specified temperature, effectively improving the efficiency of welding operations. Simultaneously, by precisely controlling various parameters of the frictional preheating component, flexible adjustment of the preheating temperature can be achieved to meet the preheating requirements of different welding processes.

[0047] The friction preheating device and method for copper alloy circular welds of the present invention, taking advantage of the high thermal conductivity of copper alloys, innovatively adopts friction preheating to achieve precise, efficient, and controllable preheating of the area to be welded before welding. This effectively solves the problems of uneven temperature, high energy consumption, and poor preheating effect of traditional preheating methods, and avoids various welding defects caused by rapid heat loss during copper alloy welding, thus improving the welding quality of copper alloy circular welds. The device has a compact structure, and the layout of the friction preheating component and welding torch is adapted to the welding trajectory of the circular weld. The retractable friction preheating component achieves seamless connection between preheating and welding. Combined with the rotation drive of the positioner, it meets the needs of continuous automated welding of large copper alloy circular welds, providing a new technical path for reliable welding of large copper alloy components.

[0048] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A friction preheating device for a circular weld seam of copper alloy, characterized in that, The equipment includes a preheating welding device (10) and a positioner (20). The preheating welding device (10) is equipped with a welding torch (11) and a friction preheating component (12). The friction preheating component (12) is located in front of the welding torch (11) along the welding trajectory. The positioner (20) is used to support the workpiece to be welded and drive the workpiece to be welded to rotate.

2. The friction preheating device for copper alloy circular welds according to claim 1, characterized in that, The friction preheating element (12) is rotatably mounted on the welding equipment (10).

3. The friction preheating device for copper alloy circular welds according to claim 2, characterized in that, The friction preheating component (12) includes a preheating shoulder (121) located at the lower end, which is in contact with the welding plane of the component to be welded.

4. The friction preheating device for copper alloy circular welds according to claim 1 or 3, characterized in that, The downward axial pressure of the friction preheating component (12) is 40KN-55KN.

5. The friction preheating device for copper alloy circular welds according to claim 4, characterized in that, The rotational angular velocity of the friction preheating component (12) is 20-35 rad / s.

6. The friction preheating device for copper alloy circular welds according to claim 3, characterized in that, The radius of the preheating shoulder (121) is 15mm-25mm.

7. The friction preheating device for copper alloy circular welds according to claim 6, characterized in that, The friction preheating component (12) forms a preheating area with a diameter of φ80mm-φ100mm on the workpiece to be welded.

8. The friction preheating device for copper alloy circular welds according to claim 3, characterized in that, The surface roughness Ra of the preheated shoulder (121) is 10μm-12.5μm.

9. The friction preheating device for copper alloy circular welds according to claim 2 or 3, characterized in that, The friction preheating component (12) is retractably mounted on the preheating welding equipment (10).

10. The method of using the friction preheating device for copper alloy circular welds according to any one of claims 1-9, characterized in that, Includes the following steps: Preheating: The workpiece to be welded is mounted on the positioner (20), the positioner (20) drives the workpiece to be welded to rotate, and at the same time the friction preheating component (12) contacts the area to be welded of the workpiece to be welded, and the area to be welded is preheated to the specified temperature by frictional heat generation; Welding: The welding torch (11) performs multi-pass, multi-layer welding on the area to be welded of the workpiece.

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