A laser welding apparatus

Abstract

The application discloses a kind of laser welding equipment, and its technical scheme main points are that the part to be welded is preheated using preheating laser beam of circular Gaussian spot, the part to be welded is welded using welding laser beam of circular Gaussian spot, the part to be welded is annealed using linear rectangular spot annealing laser beam, and energy uniformly distributed annealing laser beam is more conducive to controlling temperature gradient.In addition, the weld temperature of the application can be measured in real time, the power, spot center spacing of the preheating laser beam, welding laser beam and annealing laser beam are controllable in real time, the organization formed after laser melting is high in chemical uniformity, the grain structure is small, the weld quality is significantly improved, the residual stress after welding is effectively reduced, the mechanical properties of the alloy are greatly improved, and the service life of the welded part is improved.

Description

Technical Field

[0001] This invention relates to the field of laser welding, and more specifically, to a laser welding device. Background Technology

[0002] Gears are indispensable components of transmission machinery, and gearboxes, as the load-bearing structure of gears, are also essential components in the transmission systems of automobiles, construction machinery, and other machinery. Traditionally, gearboxes are cast parts, but casting is only suitable for manufacturing single products and not for producing gearboxes of multiple sizes and models. Furthermore, due to the numerous steps involved in the liquid metal forming process, gearboxes are prone to problems such as loose structure and coarse grains, which directly affect the mechanical properties and machinability of the transmission machinery. Therefore, to meet the requirements of high precision and high durability of gearboxes, laser welding is usually used for forming gearboxes.

[0003] Laser welding is one of the most mature technologies in laser processing. A high-energy-density laser, pumped by a laser, is directed onto the base material via a laser welding head. Heat accumulates and is conducted, causing the base material to rapidly melt and solidify, forming a weld and completing the welding process. The microscopic mechanism of laser welding involves extremely high laser energy density within the laser beam and its vicinity, causing the base material to vaporize and produce metal vapor. Simultaneously, the oscillation of the keyhole accelerates the fluidity of the molten pool. Compared to traditional welding techniques, laser welding offers advantages such as low heat input, high aspect ratio, small heat-affected zone, minimal deformation, and aesthetically pleasing welds. However, due to the rapid heating and cooling effects of the high-energy-density laser beam, laser welding is prone to generating significant thermal stress in the weld and is also susceptible to defects such as cracks and porosity.

[0004] The gearbox body is suitable for laser welding technology. The side plates, top plates, bottom plates, and center panels of the gearbox body are spliced ​​together and then fixed by laser welding. Compared with the traditional casting process, the processing method of splicing the side plates, top plates, bottom plates, and center panels and then fixing them by laser welding to form the gearbox body has significantly improved the forming quality. However, since the gearbox body itself requires high transmission accuracy and high durability, that is, the splicing welds need to have characteristics such as fine grains, low thermal stress, and no cracks. After laser welding, the gearbox body still has defects such as large residual stress, easy cracking, and insufficient grain size.

[0005] Currently, for welded metal castings such as gearbox housings that require high precision and durability, how to further improve their welding quality is a key research focus. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a laser welding device that uses a laser beam to preheat, weld, and anneal the parts to be welded, while simultaneously monitoring the weld temperature in real time to adjust the power and spot center spacing of the preheating laser beam, welding laser beam, and annealing laser beam. The resulting microstructure and chemical homogeneity after laser melting are very high, with fine grain structure, significantly improving the weld quality, effectively reducing post-weld residual stress, greatly improving the mechanical properties of the alloy, and extending the service life of the welded parts.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a laser welding device, comprising a preheating laser, a welding laser, an annealing laser, an infrared temperature measurement system, and a control system;

[0008] The preheating laser outputs a preheating laser beam to form a preheating spot on the part to be welded, the welding laser outputs a welding laser beam to form a welding spot on the part to be welded, and the annealing laser outputs an annealing laser beam to form an annealing spot on the part to be welded; the preheating spot, welding spot, and annealing spot are arranged linearly in sequence; the infrared temperature measurement system is used to detect the surface temperature of the weld after annealing spot irradiation in real time.

[0009] The control system adjusts the distance between the preheating spot, welding spot, and annealing spot, as well as the power of the preheating laser, welding laser, and annealing laser, in real time based on the signal fed back from the infrared temperature measurement system.

[0010] The invention is further configured to include a beam splitting system and an annealing reflection system. The beam splitting system is used to split the beam output by the annealing laser into a first annealing laser beam and a second annealing laser beam. The first annealing laser beam is directly output to the part to be welded to form a first annealing spot, and the second annealing laser beam is reflected to the part to be welded through the reflection system to form a second annealing spot. The preheating spot, the welding spot, the first annealing spot, and the second annealing spot are arranged linearly in sequence.

[0011] The present invention is further configured such that: an energy adjustment device is provided in the beam splitting system, and the energy adjustment device allocates and adjusts the energy ratio of the first annealed laser beam and the second annealed laser beam.

[0012] The present invention is further configured such that the energy regulation device employs a polarizer element.

[0013] The present invention is further configured such that the energy ratio between the first annealing laser beam and the second annealing laser beam is 1:1 to 2:1.

[0014] The invention is further configured such that: the control system adjusts the distance between the preheating spot, the welding spot, the first annealing spot, and the second annealing spot, as well as the power of the preheating laser, the welding laser, and the annealing laser in real time based on the signal fed back by the infrared temperature measurement system.

[0015] The present invention is further configured to include a preheating reflection system, a welding reflection system, and an annealing reflection system, wherein the output beams of the preheating laser, the welding laser, and the annealing laser are reflected onto the part to be welded through the preheating reflection system, the welding reflection system, and the annealing reflection system, respectively.

[0016] The invention is further configured to include a first shaping system and a second shaping system; the output beam of the preheating laser and the output beam of the welding laser are respectively irradiated onto the part to be welded by the two first shaping systems, the first shaping system being used to shape the laser spot into a Gaussian circular spot; the output beam of the annealing laser is irradiated onto the part to be welded by the second shaping system, the second shaping system being used to shape the laser spot into a rectangular spot, the rectangular spot having two sides parallel to the straight line where the preheating spot and the welding spot are located.

[0017] The present invention is further configured such that the power of the preheating laser, the welding laser, and the annealing laser are all adjustable, with the preheating laser power being 600-800W, the welding laser power being 1700-2000W, and the annealing laser power being 500-700W.

[0018] The present invention is further configured such that the defocusing amount of the output beams of the preheating laser, welding laser, and annealing laser is 0-0.5mm, and the scanning speed of the preheating laser, welding laser, and annealing laser is 1000-1200mm / min.

[0019] The present invention is further configured to include a power adjustment module, wherein the beams output by the preheating laser, the welding laser, and the annealing laser pass through the three power adjustment modules respectively and form a light spot on the part to be welded.

[0020] The present invention is further configured such that: the power adjustment module includes a half-wave plate, a polarizing beam splitter prism and a beam absorber block; the fast axis direction of the half-wave plate is changed by rotation; after the beam passes through the half-wave plate, it is split into two beams by the polarizing beam splitter prism, one of which is the working beam, which forms a light spot on the part to be welded, and the other beam is absorbed by the beam absorber block.

[0021] The invention is further configured to include a collimating lens, wherein the working beam forms a light spot on the part to be welded after passing through the collimating lens.

[0022] The present invention is further configured to include a beam expander, wherein a beam expander is provided between the optical paths of the preheating laser, the welding laser, the annealing laser and their corresponding power adjustment modules.

[0023] In summary, compared with the prior art, the present invention has the following advantages: The present invention uses a preheating laser beam with a circular Gaussian spot to preheat the part to be welded, a welding laser beam with a circular Gaussian spot to weld the part, and a linear rectangular annealing laser beam to anneal the part. The annealing laser beam with uniform energy distribution is more conducive to controlling the temperature gradient. Furthermore, the weld temperature of the present invention can be measured in real time, and the power and center-to-center distance of the preheating laser beam, welding laser beam, and annealing laser beam can be controlled in real time. The resulting microstructure and chemical homogeneity after laser melting are very high, with fine grain structure, significantly improving weld quality, effectively reducing post-weld residual stress, greatly improving the mechanical properties of the alloy, and extending the service life of the welded parts. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of Example 1;

[0025] Figure 2 This is a schematic diagram of the shapes of each light spot in Example 1;

[0026] Figure 3 This is a schematic diagram of Example 2;

[0027] Figure 4 This is a schematic diagram of the shapes of each light spot in Example 2;

[0028] Figure 5 This is a schematic diagram of Example 3.

[0029] In the diagram: 1. Preheating laser; 2. Welding laser; 3. Annealing laser; 4. Infrared temperature measurement system; 5. Control system; 61. Preheating reflection system; 62. Welding reflection system; 63. Annealing reflection system; 7. Beam splitting system; 8. First shaping system; 9. Second shaping system; 10. Part to be welded; 11. Preheating spot; 12. Welding spot; 13. Annealing spot; 131. First annealing spot; 132. Second annealing spot; 14. Beam expander; 15. Power adjustment module; 151. Half-wave plate; 152. Polarizing beam splitter prism; 153. Beam absorber; 16. Collimating lens; 17. Energy adjustment device. Detailed Implementation

[0030] The technical solution of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0031] Example 1

[0032] like Figure 1-2The diagram shown is a basic schematic of Embodiment 1 of the present invention. A laser welding device includes a preheating laser 1, a welding laser 2, an annealing laser 3, an infrared temperature measurement system 4, and a control system 5. The preheating laser 1 outputs a preheating laser beam to form a preheating spot 11 on the part 10 to be welded. The welding laser 2 outputs a welding laser beam to form a welding spot 12 on the part 10 to be welded. The annealing laser 3 outputs an annealing laser beam to form an annealing spot 13 on the part 10 to be welded. The preheating spot 11, welding spot 12, and annealing spot 13 are arranged linearly in sequence. The preheating laser beam preheats the upper and lower parts 10 to be welded before welding. The welding laser beam welds the upper and lower parts 10 to be welded. The annealing laser beam slowly cools the upper and lower parts 10 to be welded after welding. The infrared temperature measurement system 4 is used to detect the surface temperature of the weld after annealing in real time. In this embodiment, the infrared temperature measurement system 4 is an infrared temperature sensor.

[0033] The preheating laser 1, welding laser beam, annealing laser 3, and infrared temperature measurement system 4 all interact with the control system 5 in real time. Based on the signal fed back by the infrared temperature measurement system 4, the control system 5 adjusts the distance between the preheating spot 11, welding spot 12, and annealing spot 13, as well as the power of the preheating laser 1, welding laser 2, and annealing laser 3 in real time.

[0034] Specifically, based on the weld surface temperature obtained by the infrared temperature measurement system 4, if the weld surface temperature is higher than the preset temperature, the power of the preheating laser 1, the welding laser beam, and the annealing laser 3 is reduced; if the weld surface temperature is lower than the preset temperature, the power of the preheating laser 1, the welding laser beam, and the annealing laser 3 is increased.

[0035] In this embodiment, the power of the preheating laser 1 is 600-800W, the power of the welding laser 2 is 1700-2000W, and the power of the annealing laser 3 is 500-700W. The preheating laser beam preheats the upper and lower parts to be welded 10, which improves welding efficiency and also increases the workpiece temperature, thus improving the welding absorption rate. Because the high-energy-density laser beam rapidly heats and cools the weld during the welding stage, the weld is prone to significant thermal stress. Therefore, an annealing laser beam is used to continuously heat the weld, preventing rapid cooling. The welding stage requires the most instantaneous heat during the entire welding process; therefore, the welding laser beam has the highest power, at 1700-2000W.

[0036] Specifically, the defocusing amount of the output beams of the preheating laser 1, welding laser 2, and annealing laser 3 is 0-0.5mm; due to the addition of the preheating step, the scanning speed of the output beams of the preheating laser 1, welding laser 2, and annealing laser 3 can reach 1000-1200mm / min, which significantly improves the welding speed.

[0037] To adjust the center-to-center spacing of the laser spots, a preset temperature is required via control system 5. If the weld surface temperature is higher than the preset temperature, control system 5 extends the distance between preheating spot 11 and welding spot 12, or extends the distance between welding spot 12 and annealing spot 13. If the weld surface temperature is lower than the preset temperature, control system 5 shortens the distance between preheating spot 11 and welding spot 12, or shortens the distance between welding spot 12 and annealing spot 13. By adjusting the spot spacing, the preheating and annealing effects can be further optimized and improved based on laser power adjustment, while further reducing the possibility of overheating and burn-through.

[0038] This embodiment also includes a preheating reflection system 1, a welding reflection system 2, and an annealing reflection system 3. The output beams of the preheating laser 1, welding laser 2, and annealing laser 3 are reflected onto the part 10 to be welded through the preheating reflection system 1, welding reflection system 2, and annealing reflection system 3, respectively, achieving a linear arrangement of three light spots. The positions of the three reflection systems can be changed by a displacement device, which is communicatively connected to the control system 5. The displacement device is not shown in the figure. The control system 5 adjusts the positions of the three reflection systems in real time through the displacement device based on the signal fed back by the infrared temperature measurement system 4. The moving direction of the three reflection systems is parallel to the straight line containing the preheating light spot 11, welding light spot 12, and annealing light spot 13.

[0039] In this embodiment, the preheating reflection system 61, the welding reflection system 62, and the annealing reflection system 63 are all total reflection mirrors. The preheating reflection system 61, the welding reflection system 62, and the annealing reflection system 63 are all communicatively connected to the control system 5 so that the control system 5 can adjust the reflection angle of each laser beam.

[0040] Specifically, the center-to-center distance between the preheating spot 11 and the welding spot 12 is 40-50mm, and the center-to-center distance between the welding spot 12 and the annealing spot 13 is 60-80mm.

[0041] This embodiment also includes a first shaping system 8 and a second shaping system 9. The preheating laser beam and the welding laser beam are shaped by the two first shaping systems 8 to form a Gaussian circular spot on the part 10 to be welded; the first annealing laser beam is shaped by the second shaping system 9 to form a rectangular spot on the part 10 to be welded. The preheating laser beam with a Gaussian circular spot is used to preheat the powder. The Gaussian laser beam has high heat concentration, which can improve the preheating efficiency. During the welding process, the Gaussian circular spot is used for welding. The Gaussian circular spot with a certain overlap rate of 70-80% significantly increases the flatness of the weld. After welding is completed, the rectangular spot is used for annealing. The linear laser beam with uniform energy distribution can perform uniform heat treatment on the weld surface, which is more conducive to controlling the temperature gradient, meeting the requirements of slow cooling, and avoiding the disadvantages of cracks and large residual stress caused by rapid cooling of the weld, thus effectively improving the welding quality.

[0042] Specifically, the first shaping system 8 is a focusing lens, and the second shaping system 9 is a cylindrical lens.

[0043] In this embodiment, both the first shaping system 8 and the second shaping system 9 are communicatively connected to the control system 5 to facilitate the adjustment of the shape and size of the Gaussian circular light spot and the rectangular light spot.

[0044] Specifically, the diameter of the Gaussian circular spot is 2-3 mm; the long side of the rectangular spot is 2-3 mm, and the short side is 500-800 μm. The short side of the rectangular spot is parallel to the straight line of the preheating spot 11, the welding spot 12, and the annealing spot 13, that is, the short side of the rectangular spot is parallel to the welding direction.

[0045] In summary, this embodiment employs a preheating laser beam with a circular Gaussian spot for preheating the part to be welded 10, a welding laser beam with a circular Gaussian spot for welding the part to be welded 10, and a linear rectangular spot annealing laser beam for annealing the part to be welded 10. The annealing laser beam with uniform energy distribution is more conducive to controlling the temperature gradient. In addition, the weld temperature in this embodiment can be measured in real time, and the power and center-to-center distance of the preheating laser beam, welding laser beam, and annealing laser beam can be controlled in real time. The microstructure and chemical homogeneity formed after laser melting are very high, and the grain structure is fine, which significantly improves the weld quality, effectively reduces post-weld residual stress, greatly improves the mechanical properties of the alloy, and extends the service life of the welded parts.

[0046] Example 2

[0047] like Figure 3-4As shown, this is a basic schematic diagram of Embodiment 2. Based on Embodiment 1, this embodiment uses a beam splitting system 7 to split the beam output from the annealing laser 3 into a first annealing laser beam and a second annealing laser beam. The first annealing laser beam passes through a second shaping system 9 and forms a rectangular first annealing spot 131 on the part to be welded 10. The second annealing laser beam is reflected by an annealing reflection system 63 and then passes through another second shaping system 9 to form a rectangular second annealing spot 132 on the part to be welded 10. The preheating spot 11, the welding spot 12, the first annealing spot 131, and the second annealing spot 132 are arranged linearly in sequence.

[0048] Specifically, the beam splitting system 7 is a multifunctional lens with a coating on its surface.

[0049] In this embodiment, the defocusing amount of the first annealing laser beam and the second annealing laser beam is 0-0.5mm, and the scanning speed is 1000-1200mm / min.

[0050] In this embodiment, the beam splitting system 7, the preheating reflection system 61, the welding reflection system 62, and the annealing reflection system 63 are all repositioned by displacement devices to adjust the center distance between the four light spots. The displacement devices are not shown in the figure. The control system 5 adjusts the positions of the three reflection systems and the beam splitting system 7 in real time through the displacement devices based on the signal fed back by the infrared temperature measurement system 4, thereby changing the distance between the preheating light spot 11, the welding light spot 12, the first annealing light spot 131, and the second annealing light spot 132.

[0051] The center-to-center distance between the preheating spot 11 and the welding spot 12 is 40-50mm, the distance between the welding spot 12 and the first annealing spot 131 is 80-100mm, and the center-to-center distance between the first annealing spot 131 and the second annealing spot 132 is 40-50mm.

[0052] The beam splitting system 7 is equipped with an energy adjustment device, which distributes and adjusts the energy ratio of the first annealing laser beam and the second annealing laser beam. The energy ratio between the first annealing laser beam and the second annealing laser beam is 1:1 to 2:1. In this embodiment, two front-to-back distributed first annealing laser beams and second annealing laser beams with adjustable energy ratios are further provided. Both the first annealing spot 131 and the second annealing spot 132 are linear rectangular spots. Based on the requirement of uniform heat treatment of the weld surface, after the first annealing laser beam heats and slowly cools the weld layer, the second annealing laser beam performs a second slow cooling, further effectively reducing residual stress. The beam splitting system 7 is communicatively connected to the control system, which adjusts the output angle and energy ratio of the first and second annealing laser beams in real time.

[0053] Specifically, in this embodiment, the energy adjustment device is a polarizer element.

[0054] The beam output from the annealing laser 3 is adjusted in energy ratio by a polarizer element and then split into a first annealing laser beam pointing vertically downward and a second annealing laser beam input to the annealing reflection system 63 by a beam splitting lens in the beam splitting system 7.

[0055] Example 3

[0056] like Figure 5 As shown, the difference between this embodiment and embodiment 2 is that this embodiment also includes a power adjustment module 15 and a collimating lens 16.

[0057] The beams output from the preheating laser, welding laser, and annealing laser pass through three power adjustment modules 15 and then enter three collimating lenses 16. The preheating laser beam, after being collimated by the collimating lens 16, illuminates the preheating reflection system, and the welding laser beam, after being collimated by the collimating lens 16, illuminates the welding reflection system.

[0058] The power adjustment module 15 includes a half-wave plate 151, a polarizing beam splitter 152, and a beam absorber 153. The fast axis direction of the half-wave plate 151 is changed by rotation. After the beam passes through the half-wave plate 151, it is split into two beams by the polarizing beam splitter 152. One of the beams is the working beam and enters the collimating lens 16. In order to prevent the polarized light that is not used from damaging the eyes and equipment, the beam absorber 153 is used to collect it.

[0059] Specifically, the half-wave plate 151 is placed on a high-precision rotary table. The rotation of the rotary table is controlled by a controller to adjust the fast axis direction of the half-wave plate 151, thereby flexibly adjusting the polarization direction of the laser passing through the half-wave plate 151. This, in turn, flexibly adjusts the energy ratio between the laser passing through the polarizing beam splitter 152 and the laser reflected by it, thus achieving flexible control of the average power used for laser processing.

[0060] This embodiment also includes a beam expander 14. A beam expander 14 is provided between the optical paths of the preheating laser, the welding laser, the annealing laser, and their corresponding power adjustment modules 15. The beam expander 14 is used to change the diameter and divergence angle of the laser beam, and it can transform the beams output by the preheating laser, the welding laser, and the annealing laser into collimated beams of a specific diameter.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser welding device, characterized in that: It includes a preheating laser (1), a welding laser (2), an annealing laser (3), an infrared temperature measurement system (4), a control system (5), and a beam splitting system (7); The preheating laser (1) outputs a preheating laser beam to form a Gaussian circular preheating spot (11) on the part to be welded (10), the welding laser (2) outputs a welding laser beam to form a Gaussian circular welding spot (12) on the part to be welded (10), and the annealing laser (3) outputs an annealing laser beam to form a rectangular annealing spot (13) on the part to be welded (10); the preheating spot (11), the welding spot (12), and the annealing spot (13) are arranged linearly in sequence; the infrared temperature measurement system (4) is used to detect the surface temperature of the weld after the annealing spot (13) is irradiated in real time; The control system (5) adjusts the distance between the preheating spot (11), welding spot (12), and annealing spot (13) and the power of the preheating laser (1), welding laser (2), and annealing laser (3) in real time based on the signal fed back by the infrared temperature measurement system (4). The beam splitting system (7) is used to split the beam output by the annealing laser (3) into a first annealing laser beam and a second annealing laser beam. The first annealing laser beam is directly output to the part to be welded (10) to form a first annealing spot (131). The second annealing laser beam is reflected to the part to be welded (10) through the reflection system to form a second annealing spot (132). The preheating spot (11), the welding spot (12), the first annealing spot (131), and the second annealing spot (132) are arranged linearly in sequence. The beam splitting system (7) is equipped with an energy adjustment device, and the energy ratio between the first annealed laser beam and the second annealed laser beam is 1:1-2:1; The power of the preheating laser (1), welding laser (2), and annealing laser (3) can all be adjusted. The power of the preheating laser (1) is 600-800W, the power of the welding laser (2) is 1700-2000W, and the power of the annealing laser (3) is 500-700W. The defocusing amount of the output beams of the preheating laser (1), welding laser (2), and annealing laser (3) is 0-0.5mm, and the scanning speed of the preheating laser (1), welding laser (2), and annealing laser (3) is 1000-1200mm / min.

2. The laser welding equipment according to claim 1, characterized in that: The energy regulation device distributes and adjusts the energy ratio of the first annealing laser beam and the second annealing laser beam.

3. The laser welding equipment according to claim 2, characterized in that: The energy regulation device employs a polarizer element.

4. A laser welding device according to claim 1 or 2, characterized in that: The control system (5) adjusts the distance between the preheating spot (11), welding spot (12), first annealing spot (131), and second annealing spot (132) and the power of the preheating laser (1), welding laser (2), and annealing laser (3) in real time based on the signal fed back by the infrared temperature measurement system (4).

5. The laser welding equipment according to claim 1, characterized in that: It also includes a preheating reflection system (61), a welding reflection system (62) and an annealing reflection system (63), the output beams of the preheating laser (1), the welding laser (2) and the annealing laser (3) are reflected onto the part to be welded (10) through the preheating reflection system (61), the welding reflection system (62) and the annealing reflection system (63) respectively.

6. A laser welding device according to any one of claims 1-2 and 5, characterized in that: It also includes a first shaping system (8) and a second shaping system (9); the output beam of the preheating laser (1) and the output beam of the welding laser (2) are respectively irradiated on the part to be welded (10) through the two first shaping systems (8), and the first shaping system (8) is used to shape the laser spot into a Gaussian circular spot; the output beam of the annealing laser (3) is irradiated on the part to be welded (10) through the second shaping system (9), and the second shaping system (9) is used to shape the laser spot into a rectangular spot, the rectangular spot having two sides parallel to the straight line where the preheating spot (11) and the welding spot (12) are located.

7. The laser welding equipment according to claim 1, characterized in that: It also includes a power adjustment module (15). The beams output by the preheating laser (1), welding laser (2), and annealing laser (3) pass through the three power adjustment modules (15) respectively and form light spots on the part to be welded (10).

8. A laser welding device according to claim 7, characterized in that: The power adjustment module (15) includes a half-wave plate (151), a polarizing beam splitter (152), and a beam absorber (153). The fast axis direction of the half-wave plate (151) is changed by rotation. After the beam passes through the half-wave plate (151), it is split into two beams by the polarizing beam splitter (152). One beam is the working beam, which forms a spot on the part to be welded (10). The other beam is absorbed by the beam absorber (153).

9. A laser welding device according to claim 8, characterized in that: It also includes a collimating lens (16), through which the working beam passes and forms a spot on the part (10) to be welded.

10. A laser welding device according to claim 7, characterized in that: It also includes a beam expander (14), and a beam expander (14) is provided between the optical paths of the preheating laser (1), the welding laser (2), the annealing laser (3) and its corresponding power adjustment module (15).

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