Double-gun synchronous magnetic control welding process for long and large aluminum alloy vehicle body components

Abstract

This invention relates to the field of aluminum alloy welding technology, specifically a dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components. The process includes setting a first GTAW welding torch on the front side of the workpiece and a second GTAW welding torch on the back side, with the tungsten electrode tips of the two torches offset along the weld direction. The first GTAW welding torch is equipped with a first magnetron coil, and the second GTAW welding torch is equipped with a second magnetron coil. The first and second alternating magnetic fields operate in opposite phases. This invention controls the phase relationship of the two alternating magnetic fields, causing the front and back magnetic fields to operate in opposite phases. This allows the two magnetic fields to act at staggered times, avoiding the superposition and enhancement effect of magnetic fields. When using the opposite-phase scheme, the front magnetic field promotes the front arc to swing to the left during the positive half-cycle, while the back magnetic field causes the back arc to swing to the corresponding side during the negative half-cycle. The two arcs are staggered in time, and their respective magnetic lines of force do not superimpose in the same direction, thus suppressing arc interference.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy welding technology, specifically to a dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components. Background Technology

[0002] Due to their special properties, aluminum alloys are now used in many industries, especially railway locomotives and chemical industry. Because aluminum alloy welding is very sensitive to the protection of weld seams and porosity, the requirements for argon gas protection are very high. When double-sided bevel butt welding of thick aluminum plates, the protection of the bevel is very important. Porosity is easily caused when single-sided welding is not properly protected.

[0003] Currently, various process solutions exist for welding butt joints of thick aluminum alloy plates. Among them, patent application CN202510109168.4 discloses a magnetically controlled arc welding system and method combining GTAW (Tungsten Inert Gas) and GMAW (Gas Metal Arc Welding). This system employs a narrow-gap welding scheme combining GTAW and GMAW, with the GTAW welding torch's central axis perpendicular to the surface of the narrow-gap beveled workpiece, and the GMAW welding torch mounted on one side of the GTAW torch. This technology applies a composite magnetic field from the front of the workpiece, achieving alternating oscillation of the two arcs at the same frequency, significantly improving welding efficiency and the fusion quality of the sidewalls of thick-walled materials, and avoiding incomplete fusion defects.

[0004] In addition, in the field of aluminum alloy body welding for rail vehicles, there have been reports of the application of "dual-gun welding robots". These robots use two welding robots to weld from both sides of the workpiece, and control the overall welding deformation and local welding deformation of large components through coordinated movement. Compared with single-gun welding robots, they have better deformation control capabilities.

[0005] However, the aforementioned prior art has the following technical problems: The problem of mutual interference between electric arcs: When two electric arcs are applied simultaneously from the narrow gap bevels on the front and back of the workpiece, respectively, electromagnetic interaction will occur between the two electric arcs. If no intervention is taken, the magnetic fields of the two electric arcs with the same frequency and phase will be superimposed and enhanced, forming a local high magnetic field region in the narrow gap, causing the electric arc to deflect, resulting in poor sidewall fusion or no fusion defects, which will increase the amount of weld corner deformation.

[0006] The contradiction between sidewall fusion and deposition efficiency in narrow-gap GTAW welding: The small-angle bevel of narrow-gap welding makes it difficult for arc heat to be effectively transferred to the sidewall, and poor sidewall fusion is the core bottleneck restricting its quality. Although GMAW can improve deposition efficiency, the arc heat input is large, and the softening effect on the heat-affected zone of aluminum alloy is more prominent; although pure GTAW can obtain high-quality welds, the deposition efficiency is low and it is not suitable for multi-layer, multi-pass filler welding of long components. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention aims to provide a dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components. This process utilizes the coordinated control of two magnetic fields: the front magnetic field focuses on stirring the molten pool and wetting the sidewalls, while the back magnetic field focuses on arc compression and interference suppression. The two magnetic fields work synchronously according to a preset phase difference and frequency relationship, thereby achieving active control over the coupling behavior of the two-sided arc.

[0008] To achieve the above objectives, the present invention provides a dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components, including bevel preparation, pre-weld cleaning and preheating, dual-gun configuration and magnetron device installation, and dual-gun synchronous magnetron welding. Specifically, the following steps are included: S1. A double-sided narrow bevel is machined at the butt joint of the aluminum alloy workpieces to be welded. The double-sided narrow bevel includes a first bevel located on the front side of the workpiece and a second bevel located on the back side of the workpiece. The bevel angle is 2° to 8°, the blunt edge thickness is 2 to 6 mm, and the butt joint gap of a group of aluminum alloy workpieces is 0 to 1.5 mm. S2. Clean the double-sided narrow bevel of the aluminum alloy workpiece and a range of 30-50mm on both sides to remove oil and oxide film. Then, preheat the welding area with a neutral flame or a micro-carburizing flame at a preheating temperature of 80-180℃. S3. A first GTAW welding torch is set on the front side of the workpiece, and a second GTAW welding torch is set on the back side of the workpiece. The tungsten electrode tips of the two welding torches are staggered by a distance D along the weld direction, 0mm≤D≤8mm. The first GTAW welding torch is equipped with a first magnetron coil, and the second GTAW welding torch is equipped with a second magnetron coil. The first magnetron coil and the second magnetron coil are respectively arranged around the tungsten electrode of the corresponding welding torch to generate an alternating transverse magnetic field in their respective arc regions. S4. Start the first GTAW welding torch and the second GTAW welding torch, and introduce argon shielding gas. The first GTAW welding torch welds with the first welding current I1 and fills the molten pool with welding wire; the second GTAW welding torch welds with the second welding current I2 and does not fill the molten pool with welding wire; satisfy I2=(0.55~0.85)×I1; Simultaneously, a first excitation current is supplied to the first magnetron coil to generate a first alternating transverse magnetic field with a first frequency f1, and a second excitation current is supplied to the second magnetron coil to generate a second alternating transverse magnetic field with a second frequency f2; wherein f1 and f2 satisfy the following relationship: f1=f2 and the phase difference Δφ=90°~200°; during the welding process, the first GTAW welding torch and the second GTAW welding torch move synchronously along the weld direction at the same welding speed to achieve one-time penetration forming of both sides.

[0009] As a further improvement to this technical solution, in step S1, the double-sided narrow bevel is a U-shaped bevel, and the blunt edge thickness is 15% to 25% of the workpiece thickness.

[0010] As a further improvement to this technical solution, in step S3, the peak value of the magnetic induction intensity B of the alternating magnetic field generated by the first magnetic control coil and the second magnetic control coil in the arc region is 5 to 25 mT, and the excitation current frequency is 1 to 30 Hz.

[0011] As a further improvement to this technical solution, in step S4, the tungsten electrode diameter of the first GTAW welding torch is 2.4-4.0 mm, and the welding current I1 is 180-320 A; the tungsten electrode diameter of the second GTAW welding torch is 1.6-3.2 mm, and the welding current I2 is 100-250 A; the welding speed is 120-350 mm / min.

[0012] As a further improvement to this technical solution, in step S4, the phase difference Δφ = 180° ± 15°, that is, the first alternating magnetic field and the second alternating magnetic field work in opposite phase.

[0013] As a further improvement to this technical solution, or in step S4, f1 and f2 satisfy the following relationship: f1≠f2, and f2=f1×(0.4~0.8), so that the frequency of the back magnetic field is lower than the frequency of the front magnetic field.

[0014] As a further improvement to this technical solution, in step S4, the welding process adopts pulsed GTAW mode, with a pulse frequency of 2 to 10 Hz, a peak current duration of 40% to 60%, and a base current of 30% to 50% of the peak current; the pulse cycles of the first GTAW welding torch and the second GTAW welding torch are synchronized and in phase.

[0015] As a further improvement to this technical solution, in step S4, the protective gas is argon with a purity of ≥99.99%, the flow rate of the front protective gas is 15~25L / min, and the flow rate of the back protective gas is 10~18L / min; during the welding process, the relative humidity of the welding area is ≤80%, and the ambient temperature is ≥5℃.

[0016] As a further improvement to this technical solution, the welding wire grade filled by the first GTAW welding gun is matched with the base material, the welding wire diameter is 1.2 to 2.0 mm, and the wire feeding speed is 800 to 2500 mm / min.

[0017] As a further improvement to this technical solution, the aluminum alloy workpiece to be welded is an aluminum alloy profile or plate for long components of an aluminum alloy car body of a rail vehicle. The base material grade is selected from one of 6005A-T6, 6082-T6, 6061-T6 or 7N01-T5, and the plate thickness is 10-30mm.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The dual-gun synchronous magnetron welding process for the long aluminum alloy vehicle body components, through the coordinated control of the phase difference or frequency difference of the two-sided magnetic field, enables the electric arcs on both sides to work in staggered time, effectively suppressing electromagnetic interference of the two-sided electric arcs, avoiding magnetic blow, and significantly improving the stability of the electric arc. Simultaneous welding on both sides results in symmetrical heat input and balanced shrinkage stress on both sides, significantly reducing welding angular deformation and bending deformation. It is particularly suitable for structural components such as long aluminum alloy vehicle body parts that have strict requirements for welding deformation. The alternating magnetic field on the front drives the arc to oscillate laterally, so that the arc heat evenly covers both sides of the narrow gap, fundamentally solving the technical bottleneck of poor sidewall fusion in narrow gap GTAW welding; the stirring effect of the magnetic field promotes the escape of dissolved gas in the molten pool and the breaking of oxide film, and the double-sided argon gas protection avoids oxidation on the back side, so that the porosity of the weld is significantly lower than that of conventional processes.

[0019] 2. The dual-gun synchronous magnetron welding process for the long aluminum alloy vehicle body components adjusts the welding current on the front side to be greater than that on the back side, satisfying a ratio of 0.55 to 0.85. The welding gun current on the back side is lower to avoid excessive melting of the base material on the back side, while the welding gun current on the front side is higher to undertake the main melting and filling functions, thereby achieving good fusion and effectively suppressing the amount of weld angular deformation. Attached Figure Description

[0020] The accompanying drawings described herein are for illustrative purposes only. The shapes and proportions of the components in the drawings are merely schematic and intended to aid in understanding the invention. They are not intended to specifically limit the shapes and proportions of the components of the invention.

[0021] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a bar chart comparing the tensile strength of welded materials produced by the process of this invention. Figure 3 A bar chart comparing the porosity of welds produced by the process of this invention. Figure 4 This is a bar chart comparing the angular deformation of welding processes according to the present invention. Detailed Implementation

[0022] Under the guidance of this invention, any possible variations of this invention by those skilled in the art should be considered within its scope. The directional terms used herein are based on the orientations shown in the accompanying drawings and are for ease of description and simplification; therefore, they should not be construed as limiting the invention. Furthermore, in the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0023] Please see Figures 1-4As shown, the present invention provides a dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components, including bevel preparation, pre-weld cleaning and preheating, dual-gun configuration and magnetron device installation, and dual-gun synchronous magnetron welding. Specifically, the following steps are included: S1. For the butt joint of the aluminum alloy workpieces to be welded, a double-sided narrow bevel is machined. The double-sided narrow bevel includes a first bevel on the front side of the workpiece and a second bevel on the back side. The bevel angle is 2° to 8°, which reduces the filler volume by 50% to 70% compared to the conventional 30° to 60° bevel, while retaining sufficient arc operating space. The blunt edge thickness is 2 to 6 mm, leaving an appropriate blunt edge to avoid burn-through while ensuring complete penetration. The butt joint gap of a set of aluminum alloy workpieces is 0 to 1.5 mm. The double-sided narrow bevel is a U-shaped bevel, that is, the longitudinal section of the workpiece is hollowed out in a U-shape, leaving a central boss. The bosses of the two workpieces are butted together, and a welding area is formed at the bevel. The blunt edge thickness is 15% to 25% of the workpiece thickness. S2. Clean the double-sided narrow bevel of the aluminum alloy workpiece and a range of 30-50mm on both sides to remove oil and oxide film. Then, preheat the welding area with a neutral flame or a micro-carburizing flame at a preheating temperature of 80-180℃. S3. A first GTAW welding torch is set on the front side of the workpiece, and a second GTAW welding torch is set on the back side of the workpiece. The tungsten electrode tips of the two welding torches are staggered by a distance D along the weld direction, with 0mm ≤ D ≤ 8mm. The first GTAW welding torch is equipped with a first magnetron coil, and the second GTAW welding torch is equipped with a second magnetron coil. The first and second magnetron coils are respectively arranged around the tungsten electrode of the corresponding welding torch to generate an alternating transverse magnetic field in their respective arc regions. The peak value of the magnetic induction intensity B of the alternating magnetic field generated by the first and second magnetron coils in the arc region is 5-25mT, and the excitation current frequency is 1-30Hz. This intensity range is sufficient to effectively control the arc without causing arc instability. S4. Start the first and second GTAW welding torches, introduce argon shielding gas, and the first GTAW welding torch welds with the first welding current I1 and fills the molten pool with welding wire; the second GTAW welding torch welds with the second welding current I2 and does not fill the molten pool with welding wire; satisfy I2 = (0.55~0.85) × I1; the back welding torch does not fill the molten pool with welding wire, mainly providing supplementary heat to maintain the temperature of the molten pool and ensure root penetration, therefore the current is lower to avoid over-melting the back base material. The front welding torch fills the molten pool with welding wire and undertakes the main melting and filling functions, with a higher current; Simultaneously, a first excitation current is supplied to the first magnetron coil to generate a first alternating transverse magnetic field with a first frequency f1, and a second excitation current is supplied to the second magnetron coil to generate a second alternating transverse magnetic field with a second frequency f2; wherein f1 and f2 satisfy the following relationship: f1=f2 and the phase difference Δφ=90°~200°; during the welding process, the first GTAW welding torch and the second GTAW welding torch move synchronously along the weld direction at the same welding speed to achieve one-time penetration forming of both sides.

[0024] When two alternating electric arcs operate simultaneously from opposite sides of a workpiece, the electromagnetic fields generated by the two arc currents will couple with each other. Without intervention, the magnetic fields of the two arcs, with the same frequency and phase, will superimpose and enhance each other, forming a localized high magnetic field region within a narrow gap, causing arc deflection. This embodiment controls the phase relationship of the two alternating magnetic fields: the front magnetic field and the back magnetic field operate in opposite phases, allowing the two magnetic fields to act at staggered times, thus avoiding the superposition and enhancement effect of the magnetic fields and effectively suppressing electromagnetic interference between the two-sided arcs.

[0025] Specifically, when the anti-phase scheme is adopted, the front magnetic field promotes the front arc to swing to the left during the positive half-cycle, while the back magnetic field causes the back arc to swing to the corresponding side during the negative half-cycle. The two arcs are staggered in time, and their respective magnetic field lines will not superimpose in the same direction, thus the arc interference is suppressed.

[0026] Furthermore, the tungsten electrode diameter of the first GTAW welding torch is 2.4–4.0 mm, and the welding current I1 is 180–320 A; the tungsten electrode diameter of the second GTAW welding torch is 1.6–3.2 mm, and the welding current I2 is 100–250 A; the welding speed is 120–350 mm / min. The phase difference Δφ = 180° ± 15°, meaning the first and second alternating magnetic fields operate in opposite phases.

[0027] In addition, the welding process adopts pulsed GTAW mode with a pulse frequency of 2 to 10 Hz, a peak current duration of 40% to 60%, and a base current of 30% to 50% of the peak current; the pulse cycles of the first GTAW welding torch and the second GTAW welding torch are synchronized and in phase.

[0028] The shielding gas is argon with a purity of ≥99.99%. The flow rate of the shielding gas on the front side is 15-25 L / min, and the flow rate of the shielding gas on the back side is 10-18 L / min. During the welding process, the relative humidity of the welding area is ≤80%, and the ambient temperature is ≥5℃.

[0029] Alternatively, in step S4, f1 and f2 satisfy the following relationship: f1 ≠ f2, and f2 = f1 × (0.4 ~ 0.8), making the frequency of the back magnetic field lower than the frequency of the front magnetic field. When the frequency mismatch scheme is adopted, the two magnetic fields cannot form a stable coupling due to the frequency difference, which can also avoid interference.

[0030] It is worth noting that the welding wire used in the first GTAW welding torch is of a grade that matches the base material, with a wire diameter of 1.2–2.0 mm and a wire feed speed of 800–2500 mm / min. The aluminum alloy workpiece to be welded is an aluminum alloy profile or sheet used for long components of an aluminum alloy car body of a rail vehicle. The base material grade is selected from one of 6005A-T6, 6082-T6, 6061-T6, or 7N01-T5, and the plate thickness is 10–30 mm.

[0031] Example 1 6005A-T6 aluminum alloy 12mm thick plate double-sided I-groove welding (a) Base material and welding material Base material: 6005A-T6 aluminum alloy sheet, 300mm×150mm×12mm, two pieces joined together; Welding wire: ER5356 (φ1.6mm); (ii) Beveling type U-shaped bevel, bevel angle 0°, blunt edge 4mm, assembly gap 0mm; (III) Pre-welding preparation Before welding, clean the bevel and a 40mm area on both sides with acetone, and remove the surface oxide film with a stainless steel wire brush. Preheating temperature: 120℃ (neutral flame heating); Ambient conditions: temperature 22℃, relative humidity 55%; (iv) Equipment and parameter settings Front GTAW welding torch: AC, tungsten electrode diameter 3.2mm, welding current I1 = 240A, filler wire speed 1200mm / min; Backside GTAW welding torch: AC, tungsten electrode diameter 2.4mm, welding current I2=170A (I2 / I1=0.71), no filler wire; Welding torch spacing D = 2mm (welding torch slightly in front of the front), welding speed: 220mm / min; Protective gas: pure argon (99.99%), 20 L / min on the front and 15 L / min on the back; Magnetron parameters: front magnetron frequency f1 = 5Hz, rear magnetron frequency f2 = 5Hz, phase difference Δφ = 180° (out of phase), peak magnetic induction intensity B = 15mT; (v) Welding operations The welding guns on both sides simultaneously ignite the arc on the arc-starting plate. After stabilization, they enter the weld seam synchronously. The robot adds welding wire to the front side, but not to the back side. After welding, an inspection is carried out. (vi) Welding results Visual inspection revealed that the weld formation was good, with uniform fish-scale pattern on both the front and back weld surfaces, and no defects such as undercut, weld beads, or surface porosity. 100% radiographic testing (RT) met the ISO 10042 standard.

[0032] Example 2 6082-T6 aluminum alloy 20mm thick plate double U-shaped groove welding (a) Base material and welding material Base material: 6082-T6 aluminum alloy sheet, dimensions 500mm×200mm×20mm; Welding wire: ER5087 (φ1.6mm); (ii) Beveling type U-shaped bevel, bevel angle 6°, blunt edge 4mm, assembly gap 1.0mm; (III) Pre-welding preparation Remove oxide film by wiping with acetone and using a stainless steel wire brush. Preheat temperature: 150℃. Environmental conditions: Temperature 18℃, relative humidity 62%; (iv) Equipment and parameter settings Front GTAW welding torch: AC, tungsten electrode diameter 4.0mm, welding current I1 = 300A (pulse mode), pulse frequency 4Hz, peak duty cycle 50%, base current 120A (base value is 40% of peak value); filler wire speed 1800mm / min; Backside GTAW welding torch: AC, tungsten electrode diameter 3.2mm, welding current I2=210A (I2 / I1=0.70), no filler wire; Welding torch spacing D = 4mm, welding speed: 180mm / min; Protective gas: pure argon, 22 L / min on the front and 16 L / min on the back; Magnetization parameters: front magnetization frequency f1 = 8Hz, rear magnetization frequency f2 = 5Hz (f1 / f2 = 1.6, frequency shift mode), peak magnetic induction intensity B = 20mT (front) and 12mT (rear).

[0033] Comparative Example 1 (without magnetic control) Conditions: The base material and other parameters are the same as in Example 1, but magnetic control is not applied (f1 = f2 = 0, that is, the excitation power supply of the magnetic control coil is turned off).

[0034] Comparative Example 2 (In-phase magnetron comparison, Δφ=0°) Conditions: Except that the phase difference is set to 0° (in phase), the rest are the same as in Example 1.

[0035] Comparative Example 3 (Single-sided GTAW welding comparison) Conditions: Conventional single-sided GTAW multi-layer multi-pass welding (without back welding gun) is used. The base material and plate thickness are the same as in Example 1. V-groove (60°), one root pass + two fill and cover passes, no magnetron, welding current 220A (root pass) and 240A (fill and cover), welding speed 200mm / min.

[0036] Summary table of examples and comparative data

[0037] Data Analysis and Conclusions Analysis of magnetic control effect A comparison of Example 1 and Comparative Example 1 shows that after applying anti-phase double-sided magnetron sputtering, the weld porosity decreased from 4.5% to 1.8% (a decrease of 60%), the tensile strength increased from 178 MPa to 192 MPa (an increase of 7.9%), and the sidewall fusion improved from having localized incomplete fusion to complete fusion. This indicates that double-sided synchronous magnetron sputtering has significant effects on promoting the escape of molten pool gas, refining grain structure, and improving arc spreadability.

[0038] Phase relationship influence The comparison between Example 1 and Comparative Example 2 shows that, under the same magnetic induction intensity and frequency conditions, the anti-phase scheme (Δφ = 180°) can further reduce porosity by 44% and increase tensile strength by 4.3% compared to the in-phase scheme (Δφ = 0°). This verifies the principle analysis of this invention regarding "the phase difference of two-sided magnetic fields can suppress arc interference"—when working in the same phase, the superposition of the two magnetic fields may actually exacerbate arc deflection; working in opposite phase or at different frequencies can achieve "decoupling".

[0039] Advantages of double-sided welding A comparison of Example 1 and Comparative Example 3 shows that the increased weld angular deformation is related to whether double-sided welding is used and the current control. The welding torch currents on the front and back sides meet a ratio of 0.55 to 0.85. The back welding torch does not use filler wire and mainly provides supplementary heat to maintain the molten pool temperature and ensure root penetration; therefore, the current is lower to avoid over-melting the back base material. The front welding torch uses filler wire and undertakes the main melting and filling functions; therefore, the current is higher. Compared with traditional single-sided multi-layer multi-pass welding, double-sided synchronous magnetron welding not only saves about 58% of filler metal but also increases welding efficiency by about 54%. The welding deformation is significantly reduced from 3.5° to 0.8°, indicating that single-sided multi-pass welding is prone to over-melting the back base material, demonstrating the significant advantage of double-sided high and low welding currents in deformation control.

[0040] It should be noted that the above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A twin-gun simultaneous magnetic control welding process for long aluminum alloy car body components, characterized in that: This includes bevel preparation, pre-weld cleaning and preheating, dual-gun configuration and magnetron installation, and dual-gun synchronous magnetron welding. Specifically, the following steps are included: S1. A double-sided narrow bevel is machined at the butt joint of the aluminum alloy workpieces to be welded. The double-sided narrow bevel includes a first bevel located on the front side of the workpiece and a second bevel located on the back side of the workpiece. The bevel angle is 2° to 8°, the blunt edge thickness is 2 to 6 mm, and the butt joint gap of a group of aluminum alloy workpieces is 0 to 1.5 mm. S2. Clean the double-sided narrow bevel of the aluminum alloy workpiece and a range of 30-50mm on both sides to remove oil and oxide film. Then, preheat the welding area with a neutral flame or a micro-carburizing flame at a preheating temperature of 80-180℃. S3. A first GTAW welding torch is set on the front side of the workpiece, and a second GTAW welding torch is set on the back side of the workpiece. The tungsten electrode tips of the two welding torches are staggered by a distance D along the weld direction, 0mm≤D≤8mm. The first GTAW welding torch is equipped with a first magnetron coil, and the second GTAW welding torch is equipped with a second magnetron coil. The first magnetron coil and the second magnetron coil are respectively arranged around the tungsten electrode of the corresponding welding torch to generate an alternating transverse magnetic field in their respective arc regions. S4. Start the first GTAW welding torch and the second GTAW welding torch, and introduce argon shielding gas. The first GTAW welding torch welds with the first welding current I1 and fills the molten pool with welding wire; the second GTAW welding torch welds with the second welding current I2 and does not fill the molten pool with welding wire; satisfy I2=(0.55~0.85)×I1; Simultaneously, a first excitation current is supplied to the first magnetron coil to generate a first alternating transverse magnetic field with a first frequency f1, and a second excitation current is supplied to the second magnetron coil to generate a second alternating transverse magnetic field with a second frequency f2; wherein f1 and f2 satisfy the following relationship: f1=f2 and the phase difference Δφ=90°~200°; during the welding process, the first GTAW welding torch and the second GTAW welding torch move synchronously along the weld direction at the same welding speed to achieve one-time penetration forming of both sides.

2. The dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components according to claim 1, characterized in that, In step S1, the double-sided narrow bevel is a U-shaped bevel, and the blunt edge thickness is 15% to 25% of the workpiece thickness.

3. The dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components according to claim 2, characterized in that, In step S3, the peak value of the magnetic induction intensity B of the alternating magnetic field generated by the first and second magnetic control coils in the arc region is 5 to 25 mT, and the excitation current frequency is 1 to 30 Hz.

4. The dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components according to claim 3, characterized in that, In step S4, the tungsten electrode diameter of the first GTAW welding torch is 2.4–4.0 mm, and the welding current I1 is 180–320 A; the tungsten electrode diameter of the second GTAW welding torch is 1.6–3.2 mm, and the welding current I2 is 100–250 A; the welding speed is 120–350 mm / min.

5. The dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components according to claim 4, characterized in that, In step S4, the phase difference Δφ = 180° ± 15°, that is, the first alternating magnetic field and the second alternating magnetic field operate in opposite phase.

6. The dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components according to claim 5, characterized in that, Alternatively, in step S4, f1 and f2 satisfy the following relationship: f1≠f2, and f2=f1×(0.4~0.8).

7. The dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components according to claim 6, characterized in that, In step S4, the welding process adopts pulsed GTAW mode with a pulse frequency of 2 to 10 Hz, a peak current duration of 40% to 60%, and a base current of 30% to 50% of the peak current; the pulse cycles of the first GTAW welding torch and the second GTAW welding torch are synchronized and in phase.

8. The dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components according to claim 7, characterized in that, In step S4, the protective gas is argon with a purity of ≥99.99%, the flow rate of the front protective gas is 15-25 L / min, and the flow rate of the back protective gas is 10-18 L / min; during the welding process, the relative humidity of the welding area is ≤80%, and the ambient temperature is ≥5℃.

9. The dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components according to claim 8, characterized in that, The welding wire used in the first GTAW welding torch is of a grade that matches the base material, with a wire diameter of 1.2 to 2.0 mm and a wire feed speed of 800 to 2500 mm / min.

10. The dual-gun synchronous magnetron welding process for long aluminum alloy vehicle body components according to claim 9, characterized in that, The aluminum alloy workpiece to be welded is an aluminum alloy profile or sheet for long components of an aluminum alloy car body of a rail vehicle. The base material grade is selected from one of 6005A-T6, 6082-T6, 6061-T6 or 7N01-T5, and the sheet thickness is 10-30mm.

Images