A dual-beam laser welding method

Abstract

The present application relates to the technical field of metal material welding, and particularly relates to a double-beam laser welding method, which comprises the following steps: double-beam laser welding is carried out by using double laser heads; the upper laser head is inclined to the welding direction, and the inclination angle between the upper laser head and the vertical line of the surface of the welding plate is 3-6 degrees, and the laser defocusing amount is -2mm to -5mm; the lower laser head is inclined to the welding direction by 3-6 degrees, and the inclination angle of the lower laser head is greater than that of the upper laser head, and the laser defocusing amount is -2mm to +2mm; the distance between the focal points of the upper and lower laser heads in the horizontal direction is kept between 0.5mm and 1.0mm; the laser welding power is adjusted to carry out welding, the welding penetration of the upper laser head reaches 0.7t or above, and the welding penetration of the lower laser head reaches 0.3t-0.6t, and t is the plate thickness; the present application solves the problems of high reflection and porosity in the laser welding of aluminum or aluminum alloy, and effectively controls the molten pool solidification and laser high reflection in the welding process through the upper and lower double-beam welding.

Description

Technical Field

[0001] This invention relates to the field of metal welding technology, and in particular to a dual-beam laser welding method. Background Technology

[0002] Currently, in the field of aluminum or aluminum alloy welding, methods such as argon arc welding, gas shielded welding, and gas welding are commonly used. When using laser welding, due to the high reflectivity of aluminum or aluminum alloys, high laser reflection is highly likely to occur during the welding process, causing the laser to burn out. Simultaneously, during laser welding, the weld cools rapidly, and the solubility of dissolved gases in the molten pool decreases during cooling, preventing them from escaping and forming porosity defects in the weld, thus reducing the strength of the weld joint. Therefore, laser welding of aluminum or aluminum alloys is inherently risky and prone to joint defects. Experimental verification has shown that deflecting the laser head at a certain angle can effectively avoid high laser reflection. Furthermore, using a dual-laser-head scheme can effectively prevent weld defects. This invention fully utilizes this characteristic and, combined with laser waveform analysis, has developed a process method suitable for laser welding of aluminum or aluminum alloys.

[0003] The existing patent CN113182684A describes a dual-beam laser filler wire welding method and apparatus. This patent improves droplet transfer behavior, reduces droplet transfer cycle, droplet size, and droplet oscillation amplitude through a welding process of dual beams and filler wire distributed on the weld seam, thereby improving the flow mode of the molten pool and increasing the stability of the molten pool.

[0004] The existing patent CN118060718A describes a dual-beam welding process on opposite sides. This patent uses a laser heat conduction process to weld two metal parts without forming a keyhole during the welding process.

[0005] Both of the above patents employ a dual-laser beam welding process. Patent CN113182684A uses a single-sided dual-laser beam, which expands the molten pool area, improves the transfer behavior of the weld wire droplets, and increases the fluidity of the molten pool, thus forming a high-quality weld. However, this patent still cannot avoid the high reflectivity problem when welding aluminum or aluminum alloys. Patent CN118060718A belongs to the opposite-sided dual-laser beam welding, which uses laser heat conduction welding, not laser penetration welding, and has no welding keyhole. This patent solution cannot be used for welding aluminum or aluminum alloys. Summary of the Invention

[0006] This invention provides a dual-beam laser welding method that solves the problems of high reflection and porosity in laser welding of aluminum or aluminum alloys of the same or different materials. By using upper and lower dual-beam welding, the solidification of the molten pool and the high laser reflection in the welding process can be effectively controlled.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A dual-beam laser welding method includes the following steps: S1. The welding materials are two pieces of aluminum or aluminum alloy plates of the same or different materials; S2. Dual-beam laser welding using dual laser heads: The dual laser heads are positioned at the top and bottom of the sheet metal. The upper laser head is tilted towards the welding direction, with an angle of 3° to 6° between it and the perpendicular line to the surface of the welding plate, and a laser defocusing amount of -2mm to -5mm. The lower laser head is tilted towards the welding direction at 3° to 6°, and the tilting angle of the lower laser head is greater than that of the upper laser head, with a laser defocusing amount of -2mm to +2mm. The horizontal distance between the focal points of the two laser heads is maintained between 0.5mm and 1.0mm. S3. Adjust the laser welding power to perform welding. The upper laser head should achieve a welding penetration depth of 0.7t or more, and the lower laser head should achieve a welding penetration depth of 0.3t to 0.6t, where t is the plate thickness.

[0008] Furthermore, the thickness of the aluminum plate or aluminum alloy plate to be welded is 0.5mm to 3mm.

[0009] Furthermore, the laser welding employs variable power output, and the laser waveform includes sawtooth, rectangular, and oblique triangular shapes.

[0010] Furthermore, the power amplitude of the laser welding is controlled at 8% to 12% of the average laser power, and the frequency is 10Hz to 20Hz.

[0011] Furthermore, the maximum energy of the laser welding is 2kW to 10kW.

[0012] Furthermore, the laser welding speed is 0.03 m / s to 0.08 m / s.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1) This invention solves the problems of multiple weld pores, low joint strength, and high reflection during laser welding of aluminum or aluminum alloy homogeneous or heterogeneous materials by adopting a dual laser head configuration on the upper and lower parts of the sheet material, thus realizing laser welding of aluminum and aluminum alloy sheets. 2) By setting the tilt angle between the dual laser heads and the vertical line of the welding plate surface, the reflected laser beam refracted to the outside of the welding head during the welding process is increased, and the energy of the laser beam reflected into the laser head is reduced, effectively avoiding the high reflection problem when welding aluminum or aluminum alloy materials.

[0014] 3) The laser head of this invention is set with an inclined angle, which increases the residence time of the weld metal at high temperature, providing time for the pores generated in the weld to overflow the weld, effectively reducing the generation of weld pore defects. Attached Figure Description

[0015] Figure 1 This is a schematic diagram showing the position of the dual laser heads described in this invention.

[0016] In the diagram: 1. Welding plate; 2. Upper laser head; 3. Lower laser head. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: This invention discloses a dual-beam laser welding method, comprising the following steps: S1. Prepare two welding plates 1 for welding. The welding plates are aluminum plates and aluminum plates, aluminum plates and aluminum alloy plates, or aluminum alloy plates and aluminum alloy plates, with a plate thickness of 0.5mm to 3mm. S2. Using dual laser heads for dual-beam laser welding: Adjust the welding laser head, see... Figure 1 The upper laser head 2 is tilted in the welding direction, at an angle of [insert angle here]. The angle between the laser head and the perpendicular line to the surface of the welding plate is 3° to 6°, and the laser defocusing amount is -2mm to -5mm; the lower laser head is tilted in the welding direction in three directions, with the tilt angle being... The angle is 3° to 6°, and the tilt angle of the lower laser head 3 is greater than that of the upper laser head 2. The laser defocusing amount is -2mm to +2mm. The horizontal distance L0 between the focal points of the upper and lower laser heads is maintained between 0.5mm and 1.0mm. The tilt angle of the laser head in this invention is to avoid the reflection of the laser by the weld pool, which would cause the laser to burn out. When the tilt angle is less than 3°, the reflection control effect is not significant. When the tilt angle is greater than 6°, the actual thickness of the material to be welded increases, the laser power increases, and energy is wasted. Therefore, the deflection angle of the laser head is designed to be 3° to 6°. The defocusing amount of the upper and lower laser heads 3 is adjusted according to the actual welding effect. To increase the penetration depth, the laser head defocusing amount adopts negative defocusing. Therefore, the defocusing amount of the upper laser head 2 is -2mm to -5mm, and the defocusing amount of the lower laser head 3 is -2mm to +2mm. Welding effect is poor if it exceeds this range. To achieve good welding quality, the horizontal distance between the focal points of the upper and lower laser heads is maintained between 0.5mm and 1.0mm. This is to avoid interference caused by the small aperture formed by the laser, which would result in large fluctuations in the molten pool and poor weld formation. A distance of less than 0.5mm would lead to poor molten pool stability and poor weld formation, while a distance of more than 1.0mm would hinder the discharge of gas from the molten pool formed by the lower laser head 3, easily leading to porosity defects in the weld. The arrangement of the lower laser head 3 in front and the upper laser head 2 behind facilitates the discharge of porosity from the deep weld formed by the upper laser head 2, preventing the formation of porosity defects in the weld.

[0018] S3. Adjust the laser welding power to perform welding. The upper laser head 2 achieves a welding penetration depth of over 0.7t, and the lower laser head 3 achieves a penetration depth of 0.3t to 0.6t, where t is the plate thickness. The laser welding adopts variable power output, and the laser waveform includes sawtooth, rectangular, and oblique triangular shapes. The power amplitude value of the laser welding is controlled at 8% to 12% of the average laser power, and the frequency is 30Hz to 50Hz. The maximum energy of the laser welding is 10kW, and the laser welding speed is 0.03m / s to 0.16m / s.

[0019] The purpose of this invention to control weld penetration depth is to obtain better weld quality. The upper laser head 2 achieves a weld penetration depth of 0.7t or more (plate thickness) to accelerate the removal of gases within the weld, including pores formed by the lower laser head 3, thereby improving weld joint strength and the formability of the upper surface. When the upper surface penetration depth is less than 0.7t, the power of the smaller laser head needs to be increased to compensate for the weld penetration depth, which increases weld defects and reduces joint strength. The lower laser head 3 achieves a weld penetration depth of 0.3t to 0.6t (plate thickness) to control the weld formation on the lower surface. When the weld penetration depth is less than 0.3t, the penetration depth is too small, resulting in low efficiency and poor practicality of the lower surface laser head. When the weld penetration depth is greater than 0.6t, the lower surface penetration depth is too large, leading to poor weld formation and easy dripping of the molten pool. Therefore, controlling the penetration depth of the lower laser head 3 within the range of 0.3t to 0.6t (plate thickness) is beneficial for the formation of the lower surface and achieving higher weld quality. This invention uses a variable power laser. The variation in laser power causes fluctuations in the weld pool, which facilitates the removal of gases from the pool. Excessive laser power fluctuations result in poor weld stability, excessive welding spatter, and poor weld surface formation. Conversely, small laser power variations lead to poor stirring of the weld pool. Considering all factors, the laser power amplitude is controlled between 8% and 12% of the average laser power, and the laser power variation frequency is between 10Hz and 20Hz. Frequency that is too low or too high fails to create a stable stirring effect on the weld pool. Too low a frequency causes discontinuous welding defects in cold winds, while too high a frequency reduces the stirring effect. Therefore, a laser power variation frequency of 10Hz to 20Hz is optimal.

[0020] This invention discloses a dual-beam laser welding method, which integrates the tilt angle of the laser head, the weld penetration depth, the distance between the laser heads, and the front-to-back configuration of the laser heads to form a welding process for aluminum and aluminum alloy materials.

[0021] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0022] Example: A dual-beam laser welding method is described, and the welding process parameters are shown in Table 1. Table 1 The joint inspection results are shown in Table 2; Table 2

Claims

1. A dual-beam laser welding method, characterized in that, Includes the following steps: S1. The welding materials are two pieces of aluminum or aluminum alloy plates of the same or different materials; S2. Dual-beam laser welding using dual laser heads: The dual laser heads are positioned at the top and bottom of the sheet metal. The upper laser head is tilted towards the welding direction, with an angle of 3° to 6° between it and the perpendicular line to the surface of the welding plate, and a laser defocusing amount of -2mm to -5mm. The lower laser head is tilted towards the welding direction at 3° to 6°, and the tilting angle of the lower laser head is greater than that of the upper laser head, with a laser defocusing amount of -2mm to +2mm. The horizontal distance between the focal points of the two laser heads is maintained between 0.5mm and 1.0mm. S3. Adjust the laser welding power to perform welding. The upper laser head should achieve a welding penetration depth of 0.7t or more, and the lower laser head should achieve a welding penetration depth of 0.3t to 0.6t, where t is the plate thickness.

2. The dual-beam laser welding method according to claim 1, characterized in that, The thickness of the aluminum plate or aluminum alloy plate to be welded is 0.5mm to 3mm.

3. The dual-beam laser welding method according to claim 1, characterized in that, The laser welding employs variable power output, and the laser waveform includes sawtooth, rectangular, and oblique triangular shapes.

4. The dual-beam laser welding method according to claim 1, characterized in that, The power amplitude of the laser welding is controlled at 8% to 12% of the average laser power, and the frequency is 10Hz to 20Hz.

5. The dual-beam laser welding method according to claim 1, characterized in that, The maximum energy for laser welding is 2kW to 10kW.

6. The dual-beam laser welding method according to claim 1, characterized in that, The laser welding speed is 0.03 m / s to 0.08 m / s.

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