Backweld method for handheld laser welding

Abstract

The invention provides a backing welding method for handheld laser welding, and belongs to the technical field of welding, the method comprises the steps that a first to-be-welded plate and a second to-be-welded plate are obtained and fixed, the first to-be-welded plate and the second to-be-welded plate are parallel and opposite to each other, the first end part of the first to-be-welded plate is connected with the second end part of the second to-be-welded plate, and the second end part of the second to-be-welded plate is connected with the first to-be-welded plate; an included angle larger than 60 degrees and smaller than 90 degrees is formed between the first slope of the first to-be-welded plate and the second slope of the second to-be-welded plate, the handheld laser welding gun is arranged between the first slope and the second slope, and a welding wire is arranged at a laser nozzle of the handheld laser welding gun; and starting the handheld laser welding gun, moving the handheld laser welding gun in a direction parallel to the first edge when the laser beam passes through the first end part and the second end part, and synchronously filling a welding wire at the laser nozzle so as to form a welding bead of backing welding between the first slope and the second slope. The bottom of the plate is completely melted, and the beneficial effect of improving the welding quality is achieved.

Description

Technical Field

[0001] This application relates to the field of welding technology, and more specifically, to a method for root pass welding using a handheld laser welder. Background Technology

[0002] The root pass refers to the first weld applied when welding multiple layers of weld beads.

[0003] One current method for welding two plates using a root pass involves using an electric arc as a heat source to locally melt both plates and the welding rod on one side, forming a molten pool. After cooling and solidification, the two plates are firmly joined together as one weld.

[0004] However, in the above method, there may be some unmelted material on the other side of the plate, resulting in poor welding effect.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] This application provides a handheld laser welding method for the root pass, which solves the problem of poor welding results in related technologies. The technical solution is as follows: According to one aspect of this application, a method for forming a root pass weld in a handheld laser welding process is provided, the method comprising: Obtain a first plate to be welded and a second plate to be welded, wherein the thickness of the first plate to be welded and the second plate to be welded are both greater than or equal to 6 mm and less than or equal to 35 mm; The first plate to be welded and the second plate to be welded are fixed, the first plate to be welded and the second plate to be welded are parallel to each other and opposite to each other, the first edge of the first plate to be welded and the second plate to be welded opposite to each other has a first end and a first slope connected to the first end, the second edge of the second plate to be welded opposite to the first plate to be welded has a second end and a second slope connected to the second end, the first end and the second end are connected, the end of the first slope near the first end is connected to the end of the second slope near the second end, and there is an angle between the first slope and the second slope that is greater than 60 degrees and less than 90 degrees. A handheld laser welding gun is positioned between the first slope and the second slope, and a welding wire is placed at the laser nozzle of the handheld laser welding gun. The handheld laser welding gun is activated, and the laser nozzle emits a laser beam; As the laser beam passes through the first end and the second end, the handheld laser welding gun is moved in a direction parallel to the first edge, and the welding wire is simultaneously filled at the laser nozzle to form a root pass between the first slope and the second slope.

[0007] Optionally, moving the handheld laser welding gun along a direction parallel to the first edge and simultaneously filling the laser nozzle with the welding wire includes: The welding wire is filled into the laser nozzle by an automatic wire feeding system, and the handheld laser welding gun is moved in a direction parallel to the first edge by the welding wire.

[0008] Optionally, after the method involves filling the laser nozzle with welding wire via an automatic wire feeding system and using the welding wire to push the handheld laser welding gun to move in a direction parallel to the first edge, the method further includes: While controlling the handheld laser welding gun to move in a direction parallel to the first edge, it repeatedly swings laterally, the lateral direction being perpendicular to the first edge and parallel to the surface of the first plate to be welded.

[0009] Optionally, the frequency range of the repetitive oscillation is 100 Hz to 150 Hz, and the amplitude of the repetitive oscillation is 3 mm to 5 mm.

[0010] Optionally, moving the handheld laser welding gun along a direction parallel to the first edge includes: As the handheld laser welding gun moves in a direction parallel to the first edge, the laser beam continuously passes through the first end and the second end.

[0011] Optionally, the minimum distance between the first end of the first plate to be welded and the second end of the second plate to be welded ranges from 0 mm to 0.5 mm, and the thickness of the first end and the second end ranges from 2 mm to 3 mm.

[0012] Optionally, the angle between the first ramp and the thickness direction is in the range of 30 degrees to 40 degrees, the angle between the second ramp and the thickness direction is in the range of 30 degrees to 40 degrees, and the thickness direction is the direction perpendicular to the surface of the first plate to be welded.

[0013] Optionally, the angle between the first slope and the thickness direction is equal to the angle between the second slope and the thickness direction.

[0014] Optionally, the first slope has a first step structure, and the second slope has a second step structure. The step surface of the first step structure and the step surface of the second step structure are located in the same plane, and the weld bead is flush with the step surface of the first step structure and the step surface of the second step structure.

[0015] Optionally, the step surface of the first step structure satisfies: a=t (x / 90); Where a is the distance between the stepped surface and the back of the first plate to be welded in the thickness direction, t is the thickness of the first plate to be welded, x is the angle between the first slope and the second slope in degrees, and the back of the first plate to be welded is the side of the first plate to be welded that is away from the handheld laser welding gun.

[0016] The beneficial effects of the technical solutions provided in this application include at least the following: A method for forming a root pass weld using handheld laser welding is provided. A first and second weld plates with a thickness greater than or equal to 6 mm and less than or equal to 35 mm are obtained. The first and second weld plates are parallel to each other and arranged opposite each other, with the first end of the first weld plate connected to the second end of the second weld plate. An angle greater than 60 degrees and less than 90 degrees is formed between the first slope of the first weld plate and the second slope of the second weld plate, eliminating the need for pre-reserved gaps or requiring only minimal gaps during assembly. This reduces the risk of misalignment and deformation caused by improper gap control. A laser beam is emitted from the laser nozzle of a handheld laser welding gun located between the first and second slopes. As the laser beam passes through the first and second ends, the handheld laser welding gun is moved in a direction parallel to the first edges of the first and second weld plates, and welding wire is simultaneously filled at the laser nozzle, forming a root pass weld between the first and second slopes. This weld pass allows the laser to completely penetrate the first and second ends, ensuring complete melting of the bottom of the plate and achieving the beneficial effect of improving welding quality.

[0017] In addition, since this method directly melts through two relatively thick plates to be welded by hand-held laser welding gun, there is no need to leave a gap between the two plates during the welding process, which can reduce the assembly difficulty of the plates to be welded.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0020] Figure 1 This is a flowchart illustrating a method for forming a root pass in handheld laser welding, as shown in an embodiment of this application.

[0021] Figure 2 This is a flowchart illustrating another method for forming the root pass in handheld laser welding, as shown in an embodiment of this application.

[0022] Figure 3 This is a schematic diagram of the initial welding state structure of a handheld laser welder for the root pass, provided in an embodiment of this application.

[0023] The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0025] Figure 1 This is a flowchart illustrating a method for forming a root pass in handheld laser welding, as shown in an embodiment of this application. The method for forming a root pass in handheld laser welding may include the following steps: Step 101: Obtain the first and second plates to be welded. The thickness of both the first and second plates to be welded is greater than or equal to 6 mm and less than or equal to 35 mm.

[0026] Step 102: Fix the first plate to be welded and the second plate to be welded, with the first plate to be welded and the second plate to be welded being parallel to each other and opposite to each other.

[0027] The first edge of the first plate to be welded and the second plate to be welded opposite each other has a first end and a first slope connected to the first end. The second edge of the second plate to be welded opposite each other has a second end and a second slope connected to the second end. The first end and the second end are connected. The end of the first slope near the first end is connected to the end of the second slope near the second end. The first slope and the second slope have an included angle greater than 60 degrees and less than 90 degrees.

[0028] Step 103: Position the handheld laser welding gun between the first and second slopes, and place the welding wire at the laser nozzle of the handheld laser welding gun.

[0029] Step 104: Start the handheld laser welding gun, and the laser nozzle emits a laser beam.

[0030] Step 105: When the laser beam passes through the first end and the second end, move the handheld laser welding gun in a direction parallel to the first edge and simultaneously fill the laser nozzle with welding wire to form a root pass between the first slope and the second slope.

[0031] In summary, the handheld laser welding root pass method provided in this application involves obtaining a first and a second plate to be welded, both with a thickness greater than or equal to 6 mm and less than or equal to 35 mm. The first and second plates are parallel and opposite to each other, with the first end of the first plate connected to the second end of the second plate. An angle greater than 60 degrees and less than 90 degrees is formed between the first slope of the first plate and the second slope of the second plate, eliminating the need for pre-reserved gaps or requiring only minimal gaps during assembly. This reduces the risk of misalignment and deformation caused by improper gap control. A laser beam is emitted from the laser nozzle of the handheld laser welding gun located between the first and second slopes. As the laser beam passes through the first and second ends, the handheld laser welding gun moves along a direction parallel to the opposing first edges of the first and second plates, simultaneously filling the laser nozzle with welding wire. This forms a root pass between the first and second slopes, allowing the laser to completely penetrate the first and second ends, ensuring complete melting of the bottom of the plate and achieving the beneficial effect of improving welding quality.

[0032] In addition, since this method directly melts through two relatively thick plates to be welded by hand-held laser welding gun, there is no need to leave a gap between the two plates during the welding process, which can reduce the assembly difficulty of the plates to be welded.

[0033] The handheld laser welding root pass method provided in this application can be used to form a root pass weld bead between a first and a second plate to be welded. The root pass weld is the first layer (pass) of weld in a multi-layer, multi-pass welding process. It is the "foundation" and "backdrop" of the entire weld joint, directly affecting the quality of the weld. The root pass weld fuses the roots of the first and second plates to be welded together, achieving a preliminary structural connection. The root pass weld bead provides a good, defect-free base for subsequent filler weld passes. If the root pass weld is substandard, subsequent welding will be performed on defects, easily leading to the scrapping of the entire weld. Furthermore, the root pass weld is the most difficult step to control during the welding process due to limited operating space and the tendency for incomplete penetration (the roots of the first and second plates to be welded are not completely fused, forming a serious defect). The method provided in this application can solve at least some of these problems.

[0034] Figure 2 This is a flowchart illustrating another method for forming a root pass in handheld laser welding, as shown in an embodiment of this application. This method may include the following steps: Step 201: Obtain the first and second plates to be welded. The thickness of both the first and second plates to be welded is greater than or equal to 6 mm and less than or equal to 35 mm.

[0035] Thin plates less than 6 mm thick typically do not require such complex beveling for the root pass; while for ultra-thick plates thicker than 35 mm, the power of handheld laser welding may not be sufficient for a single-pass penetration. Therefore, for welding plates with a thickness greater than or equal to 6 mm and less than or equal to 35 mm, it is possible to ensure that subsequent laser power, beveling design, and other parameters can be effectively applied to plates within this thickness range, achieving single-sided welding with double-sided forming.

[0036] Step 202: Fix the first plate to be welded and the second plate to be welded, with the first plate to be welded and the second plate to be welded being parallel to each other and opposite to each other.

[0037] Figure 3 This is a schematic diagram of the initial welding state structure of a handheld laser welder for the root pass, as provided in an embodiment of this application. Figure 3As shown, the first edge of the first plate to be welded 11 and the second plate to be welded 12 opposite each other has a first end 111 and a first slope 112 connected to the first end 111. The second edge of the second plate to be welded 12 opposite to the first plate to be welded 11 has a second end 121 and a second slope 122 connected to the second end 121. The first end 111 is connected to the second end 121. The end of the first slope 112 near the first end 111 is connected to the end of the second slope 122 near the second end 121. The first slope 112 and the second slope 122 have an included angle greater than 60 degrees and less than 90 degrees.

[0038] The minimum distance h1 between the first end 111 of the first plate to be welded 11 and the second end 121 of the second plate to be welded 12 ranges from 0 mm to 0.5 mm. Controlling the assembly gap within this range greatly reduces the assembly precision requirements, simplifies the assembly process, reduces welding defects caused by uneven gaps, and improves production efficiency. The thickness h2 of the first end 111 and the second end 121 ranges from 2 mm to 3 mm. This thickness range provides a carrier for the "keyhole effect" of the laser, enabling it to form stably and penetrate. The keyhole effect, also known as the "deep penetration welding" mechanism, refers to the formation of a tiny hole filled with metal vapor that penetrates the entire molten pool when a high-energy-density laser beam irradiates the metal surface. The laser energy acts directly on the deep part of the material through this small hole. The welds formed by pinhole welding are deep and narrow. For the same plate thickness, pinhole welding requires a smaller weld cross-sectional area, less filler metal, and less welding deformation. Furthermore, the metal vapor pressure inside the pinhole helps to expel gases and impurities from the molten pool, thereby significantly reducing porosity and slag inclusions and improving the density and mechanical properties of the weld.

[0039] The angles between the first ramp 112 and the thickness direction, and / or the angles between the second ramp 122 and the thickness direction, are both within the range of 30 to 40 degrees. The thickness direction is perpendicular to the surface of the first plate to be welded 11. Within this angle range, it is possible to ensure that the laser beam can successfully irradiate the root while also providing suitable space for subsequent weld filling, achieving a balance between penetration depth and operability.

[0040] The angle between the first ramp 112 and the thickness direction is equal to the angle between the second ramp and the thickness direction. At this point, the bevels of the first and second plates to be welded 11 and 12 are perfectly mirror-symmetrical. Both plates can be prepared using the same processing technology and parameters, simplifying the production preparation process and reducing processing complexity. Furthermore, the symmetrical bevels allow the laser to be precisely positioned on the centerline of the joint, helping to form a heat-affected zone symmetrical about the weld centerline, thereby minimizing angular and wave deformations caused by uneven heating and cooling. The stress distribution of the post-weld structure is more balanced, improving the dimensional accuracy and shape stability of the product.

[0041] Furthermore, in another embodiment of this application ( Figure 3 (Not shown) The angles between the first and second ramps and the thickness direction can also be unequal. For example, the angle between the first and second ramps and the thickness direction is 40 degrees, while the angle is 30 degrees, thus forming a V-shaped bevel with a total angle of 70 degrees and an asymmetrical axis. This asymmetrical structure provides great layout flexibility. When the space on one side of the weld joint is obstructed by other components, preventing the welding torch from being centered in the ideal position, the bevel angle can be adjusted so that the steeper bevel side faces the direction of the confined space, while the gentler bevel side faces the direction of the open operating space. This allows the welding torch to be tilted at a certain angle for welding, solving the welding accessibility problem in narrow or special structures. When the materials of the first and second plates to be welded are different, this asymmetrical structure with unequal angles can also be used, with the side with the larger bevel angle facing the plate with better thermal conductivity or a slightly thicker thickness. In this way, a larger opening allows more laser energy and filler metal to act on that side, compensating for its faster heat loss and ensuring that the base materials on both sides reach the ideal melting state at the same time, thus achieving good fusion.

[0042] In another embodiment of this application, a first step structure is provided on the first slope, and a second step structure is provided on the second slope. The step surfaces of the first and second step structures are located in the same plane, and the weld bead is flush with both the step surfaces of the first and second step structures. This step surface provides precise mechanical positioning for the weld bead. Regardless of how the welding speed is finely adjusted, the molten pool will stop collapsing at the step surface, thus ensuring a constant height for the entire weld bead, flush with the step surface. This avoids the problems of uncontrollable weld bead height and shape, and the tendency for concavity or collapse, that often occur when welding at slope bevels. By setting the first and second step structures, not only is the operational difficulty reduced, but quality fluctuations caused by human factors are also reduced, significantly improving welding quality.

[0043] The step surface of the first step structure satisfies: a=t (x / 90); Where 'a' is the distance in the thickness direction between the step surface and the back side of the first plate to be welded, 't' is the thickness of the first plate to be welded, and 'x' is the angle between the first and second slopes. The back side of the first plate to be welded is the side of the first plate to be welded that is away from the handheld laser welding gun. The larger the bevel angle 'x' or the larger the plate thickness 't', the larger the bevel volume, and the more root pass metal is required. Therefore, the step surface position 'a' needs to be lower to provide more space to accommodate this metal.

[0044] In one exemplary embodiment, the step surfaces of the first and second steps are parallel to each other. However, in a direction perpendicular to the step surface of the first step, the step surface of the second step is located on the side of the first step away from the first edge of the first step. That is, the step surface of the second step is higher than the step surface of the first step. This structure with step surfaces of different heights provides a reference point for the height of the weld bead, allowing the operator to confirm the height and thickness of the weld bead when forming the root pass weld. For example, if the thickness of the first and second plates to be welded is the same, then in the thickness direction of the first plate to be welded, the first distance between the step surface of the first step and the bottom surface of the first plate to be welded is equal to the second distance between the step surface of the second step and the top surface of the first plate to be welded, and the distance between the step surfaces of the first and second steps is equal to this first distance. This further facilitates the determination of the weld bead thickness and reduces the difficulty of welding.

[0045] Step 203: Position the handheld laser welding gun between the first and second slopes, and place the welding wire at the laser nozzle of the handheld laser welding gun.

[0046] like Figure 3 As shown, the handheld laser welding gun 13 is positioned between the first ramp 112 and the second ramp 122, and the welding wire 14 is fed to the front of the laser nozzle of the handheld laser welding gun 13 by an automatic wire feeding system. The handheld laser welding gun 13 can also be positioned above the bevels of the first ramp 112 and the second ramp 122, but this embodiment does not limit the position.

[0047] The rated output power P (watts) of the handheld laser welding gun and the thickness (t, millimeters) of the plate to be welded satisfy the following relationship: P ≥ 1000 + 100 t. This formula allows for the rapid calculation of the minimum laser power required for welding plates of different thicknesses. For example, when t is 6 mm: P ≥ 1000 + 100 6 = 1600W. When t is 25 mm: P ≥ 1000 + 100 25 = 3500 W. This means that welding a 25mm thick plate requires a handheld laser welding gun with a rated power of at least 3500W.

[0048] In one exemplary embodiment, the automatic wire feeding system is an electromechanical device capable of automatically, continuously, and stably feeding welding wire from a wire spool to the laser nozzle of a handheld laser welding torch. The automatic wire feeding system may include components such as a wire feeder, a wire feeding hose, and a wire spool. The wire feeder includes a motor-driven wire feeding wheel. The operator presses the welding wire into the groove (guide groove) of the wire feeding wheel by tightening a handle. As the motor rotates, friction drives the welding wire forward or backward. The wire feeder may include a knob or digital panel for precisely adjusting the wire feeding speed. The wire feeding speed is related to the laser power and welding efficiency and is a crucial factor in the welding parameters.

[0049] Step 204: Start the handheld laser welding gun, and the laser nozzle emits a laser beam.

[0050] In this embodiment, the power of the handheld laser welding gun is 1600 watts, the diameter of the welding wire is 1.2 mm to 1.6 mm, the wire feeding speed is 50 m / min to 60 m / min, and the gas flow rate is 15 L / min.

[0051] Step 205: When the laser beam passes through the first end and the second end, fill the laser nozzle with welding wire through the automatic wire feeding system, and push the handheld laser welding gun to move in a direction parallel to the first edge by the welding wire.

[0052] As the handheld laser welding torch moves parallel to the first edge, the laser beam continuously passes through the first and second ends. This ensures the laser beam continuously penetrates both ends, forming a small hole. Simultaneously, the automatic wire feeding system precisely fills the molten pool with welding wire, and utilizes the thrust generated during wire feeding to assist the operator in moving the welding torch at a uniform speed along the weld direction, achieving complete root penetration and synchronous filling of the weld metal. Furthermore, the pushing action of the welding wire allows the welding torch to move at a uniform speed, resulting in a uniform and consistent weld.

[0053] Step 206: While controlling the handheld laser welding gun to move in a direction parallel to the first edge, it repeatedly swings laterally. The lateral direction is perpendicular to the first edge and parallel to the surface of the first plate to be welded, so as to form a root pass between the first slope and the second slope.

[0054] The handheld laser welding torch is controlled to perform lateral, repetitive oscillations at at least one of a oscillation frequency of 100 Hz to 150 Hz and an oscillation amplitude of 3 mm to 5 mm. High-frequency oscillation agitates the molten pool, resulting in a more even distribution of heat on both sides of the bevel, preventing undercut or incomplete fusion caused by excessive heat concentration. The oscillation motion also widens the weld bead, allowing for better fusion with the bevel walls and forming a smooth, full weld shape. The agitation effect of the oscillation also helps gases and impurities in the molten pool to rise and escape, significantly reducing porosity and slag inclusions in the weld, and improving the weld's density and mechanical properties.

[0055] The root pass welding method for handheld laser welding provided in this application embodiment uses handheld laser welding to form the root pass weld. Handheld laser welding has the characteristics of flexible and convenient operation, high welding heat, concentrated density, and strong penetration ability.

[0056] In summary, the handheld laser welding root pass method provided in this application involves obtaining a first and a second plate to be welded, both with a thickness greater than or equal to 6 mm and less than or equal to 35 mm. The first and second plates are parallel and opposite to each other, with the first end of the first plate connected to the second end of the second plate. An angle greater than 60 degrees and less than 90 degrees is formed between the first slope of the first plate and the second slope of the second plate, eliminating the need for pre-reserved gaps or requiring only minimal gaps during assembly. This reduces the risk of misalignment and deformation caused by improper gap control. A laser beam is emitted from the laser nozzle of the handheld laser welding gun located between the first and second slopes. As the laser beam passes through the first and second ends, the handheld laser welding gun moves along a direction parallel to the opposing first edges of the first and second plates, simultaneously filling the laser nozzle with welding wire. This forms a root pass between the first and second slopes, allowing the laser to completely penetrate the first and second ends, ensuring complete melting of the bottom of the plate and achieving the beneficial effect of improving welding quality.

[0057] In addition, since this method directly melts through two relatively thick plates to be welded by hand-held laser welding gun, there is no need to leave a gap between the two plates during the welding process, which can reduce the assembly difficulty of the plates to be welded.

[0058] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0059] In this application, the term "at least one of A and B" merely describes the relationship between related objects, indicating that three relationships can exist. For example, "at least one of A and B" can represent: A existing alone, A and B existing simultaneously, and B existing alone. Similarly, "at least one of A, B, and C" indicates that seven relationships can exist, representing: A existing alone, B existing alone, C existing alone, A and B existing simultaneously, A and C existing simultaneously, C and B existing simultaneously, and A, B, and C existing simultaneously. Likewise, "at least one of A, B, C, and D" indicates that fifteen relationships can exist, representing: A existing alone, B existing alone, C existing alone, D existing alone, A and B existing simultaneously, A and C existing simultaneously, A and D existing simultaneously, C and B existing simultaneously, D and B existing simultaneously, C and D existing simultaneously, A, B, and C existing simultaneously, A, B, and D existing simultaneously, A, C, and D existing simultaneously, and A, B, C, and D existing simultaneously.

[0060] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for forming a root pass weld in handheld laser welding, characterized in that, The method includes: Obtain a first plate to be welded and a second plate to be welded, wherein the thickness of the first plate to be welded and the second plate to be welded are both greater than or equal to 6 mm and less than or equal to 35 mm; The first plate to be welded and the second plate to be welded are fixed, the first plate to be welded and the second plate to be welded are parallel to each other and opposite to each other, the first edge of the first plate to be welded and the second plate to be welded opposite to each other has a first end and a first slope connected to the first end, the second edge of the second plate to be welded opposite to the first plate to be welded has a second end and a second slope connected to the second end, the first end and the second end are connected, the end of the first slope near the first end is connected to the end of the second slope near the second end, and there is an angle between the first slope and the second slope that is greater than 60 degrees and less than 90 degrees. A handheld laser welding gun is positioned between the first slope and the second slope, and a welding wire is placed at the laser nozzle of the handheld laser welding gun. The handheld laser welding gun is activated, and the laser nozzle emits a laser beam; As the laser beam passes through the first end and the second end, the handheld laser welding gun is moved in a direction parallel to the first edge, and the welding wire is simultaneously filled at the laser nozzle to form a root pass between the first slope and the second slope.

2. The method according to claim 1, characterized in that, Moving the handheld laser welding gun along a direction parallel to the first edge and simultaneously filling the laser nozzle with the welding wire includes: The welding wire is filled into the laser nozzle by an automatic wire feeding system, and the handheld laser welding gun is moved in a direction parallel to the first edge by the welding wire.

3. The method according to claim 2, characterized in that, After the method involves filling the laser nozzle with welding wire via an automatic wire feeding system and using the welding wire to push the handheld laser welding gun to move in a direction parallel to the first edge, the method further includes: While controlling the handheld laser welding gun to move in a direction parallel to the first edge, it repeatedly swings laterally, the lateral direction being perpendicular to the first edge and parallel to the surface of the first plate to be welded.

4. The method according to claim 3, characterized in that, The frequency range of the repetitive oscillation is 100 Hz to 150 Hz, and the amplitude of the repetitive oscillation is 3 mm to 5 mm.

5. The method according to claim 1, characterized in that, Moving the handheld laser welding gun along a direction parallel to the first edge includes: As the handheld laser welding gun moves in a direction parallel to the first edge, the laser beam continuously passes through the first end and the second end.

6. The method according to claim 1, characterized in that, The minimum distance between the first end of the first plate to be welded and the second end of the second plate to be welded ranges from 0 mm to 0.5 mm, and the thickness of the first end and the second end ranges from 2 mm to 3 mm.

7. The method according to claim 1, characterized in that, The angle between the first ramp and the thickness direction is in the range of 30 degrees to 40 degrees, and the angle between the second ramp and the thickness direction is in the range of 30 degrees to 40 degrees. The thickness direction is the direction perpendicular to the surface of the first plate to be welded.

8. The method according to claim 7, characterized in that, The angle between the first slope and the thickness direction is equal to the angle between the second slope and the thickness direction.

9. The method according to claim 7, characterized in that, The first slope has a first step structure, and the second slope has a second step structure. The step surface of the first step structure and the step surface of the second step structure are located in the same plane, and the weld bead is flush with the step surface of the first step structure and the step surface of the second step structure.

10. The method according to claim 9, characterized in that, The step surface of the first step structure satisfies: a=t (x / 90); Where a is the distance between the stepped surface and the back of the first plate to be welded in the thickness direction, t is the thickness of the first plate to be welded, x is the angle between the first slope and the second slope in degrees, and the back of the first plate to be welded is the side of the first plate to be welded that is away from the handheld laser welding gun.

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