Multi-spot laser welding device and method

Abstract

The invention discloses a multi-spot laser welding device and method, and relates to the technical field of laser processing, the device comprises a laser generator, an optical splitter, a variable collimation focusing device, a primary laser swing reflection cavity, a secondary laser swing reflection cavity and a secondary focusing device, the laser generator is connected with the input end of the optical splitter, and the output end of the optical splitter is connected with the variable collimation focusing device; a plurality of output ends of the optical splitter are respectively and sequentially connected with the variable collimation focusing device and the first-stage laser swing reflection cavities, the output ends of all the first-stage laser swing reflection cavities are connected with the input end of the same second-stage laser swing reflection cavity, and the output end of the second-stage laser swing reflection cavity is connected with the secondary focusing device. The method has the advantages that the welding seam strength is enhanced, and the welding efficiency can be greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of laser processing, and in particular to a multi-spot laser welding device. Background Art

[0002] Laser welding is an efficient and precise welding method that uses a high-energy-density laser beam as a heat source. Due to its advantages of high efficiency, low power consumption, and small welding deformation, it has been widely used in the new energy industry, especially the lithium battery manufacturing industry. Laser welding has become an important processing method for key processes such as battery cell assembly and module assembly.

[0003] In order to meet the requirements of high-quality and high-efficiency production, the welding of battery connectors requires the use of galvanometer swing laser welding technology. The galvanometer can make the laser perform swing scanning welding in a fixed area due to its reflection principle, and the galvanometer can make the laser beam swing in a small range, which greatly improves the production efficiency. For example, the patent document with publication number CN117961296A discloses a lithium battery pole ear laser welding method. The laser is converted into a moving light spot after passing through the galvanometer module. By controlling the rotation of the galvanometer module, the light spot moves along a spiral trajectory on the workpiece to be welded.

[0004] When the laser enters the molten pool in a swinging manner, the molten pool obtains a stirring effect, which can better form the weld and fusion zone, improve the welding forming quality, and help the molten pool to discharge the gas involved in the welding process. In the welding of battery connectors, the weld also needs to bear the flow demand. Laser swing can increase the volume of the molten pool, form a wider welding area, significantly reduce the contact resistance, and increase the flow capacity of the connector.

[0005] Existing galvanometer oscillating welding systems mostly use single spot or point or ring lasers. The laser beam is a single beam. When the beam is oscillating, the energy is relatively concentrated and the heating effect is discontinuous, which makes it difficult to meet the welding quality requirements. In addition, the shape of the molten pool formed is similar to the "tooth root" shape, which can easily cause explosion points or welding penetration, resulting in scrap. Summary of the invention

[0006] The technical problem to be solved by the present invention is how to avoid abnormal defects such as "tooth root" shaped molten pool, explosion point, spatter, weld penetration, high porosity, etc. generated during welding by a galvanometer oscillating welding system, so as to improve the welding quality.

[0007] The present invention solves the above technical problems through the following technical means: a multi-spot laser welding device, including a laser generator, a beam splitter, a variable collimation and focusing device, a primary laser oscillating reflection cavity, a secondary laser oscillating reflection cavity and a secondary focusing device, the laser generator is connected to the input end of the beam splitter, and the multiple output ends of the beam splitter are respectively connected to the variable collimation and focusing device and the primary laser oscillating reflection cavity in sequence, the output ends of all primary laser oscillating reflection cavities are connected to the input end of the same secondary laser oscillating reflection cavity, and the output end of the secondary laser oscillating reflection cavity is connected to the secondary focusing device.

[0008] The beam splitter changes the laser beam from one beam to multiple beams, and its energy distribution also changes from a single distribution to a multi-beam distribution, which can evenly heat the surface of the material and effectively solve the uneven energy distribution caused by single spot swing welding, and the excessive energy at a single point causing welding spatter and explosion points.

[0009] Each laser beam is reflected by a primary laser swing reflection cavity, so that its spot can swing in a small circle or other graphic motion, achieving an annular energy distribution effect, preheating the weld in the front section, continuous heating in the middle section to form a molten pool, and extending the cooling and solidification time of the molten pool in the back section. This welding process is generally called ring spot welding. This welding technology can effectively solve the splashing of metal materials and the solidification pores of the metal molten pool during welding, and can prevent the generation of cracks in the solidification stage.

[0010] The use of multiple light spots in a continuous swing can form a large-scale heating of the metal material and a relatively wide welding pool, so that the battery connectors can be welded, which can increase the effective welding area, improve the current capacity of the lithium-ion battery, and reduce the current resistance.

[0011] It can achieve that when multiple spots heat the molten metal at the same time, the welding molten pool will generate multiple laser keyholes at the same time. Multiple light beams move, so that the laser keyholes can continuously stir the molten pool, accelerate the discharge of pores in the molten pool, and the continuously stirred molten pool can refine the metal grains and prevent the generation of intergranular compounds. The strength of the weld is greatly improved after welding, and the pulling strength can reach 90% of the parent material.

[0012] The secondary laser swing reflection cavity is used to realize the simultaneous large-range movement of the overall multi-spot laser. The multi-spot laser beam moves according to the set welding trajectory path, which effectively increases the welding connection area. It can be used for more long or complex welding tasks, and can also weld multiple target welds at the same time, greatly improving the welding efficiency.

[0013] The secondary focusing device refocuses and compensates for the focal length deviation caused by laser displacement, so that the laser focus is always kept on the surface of the welding workpiece when the multi-spot laser beam moves, thereby achieving consistency and continuity of laser energy output.

[0014] The welding device can effectively solve abnormal defects such as "tooth root" shaped molten pool, explosion points, spatter, weld penetration, and high porosity during the welding process. It can also prevent the generation of cracks during the solidification stage, improve the overcurrent capacity of lithium-ion batteries, reduce the overcurrent resistance, enhance the weld strength, and greatly improve welding efficiency.

[0015] As an optimized technical solution, multiple first-level laser oscillating reflection cavities are evenly distributed around the same axis, the rotation trajectory of the laser beam in each first-level laser oscillating reflection cavity revolves around its axis, and the rotation direction of the laser beam in the first-level laser oscillating reflection cavity symmetrical on both sides of the axis is consistent.

[0016] It is beneficial to accurately control key indicators such as welding width, depth and porosity.

[0017] As an optimized technical solution, the output end of the laser generator is connected to the input end of the splitter through an optical fiber, the output end of the splitter is connected to the variable collimation and focusing device through an optical fiber or a closed external optical path, the output end of the variable collimation and focusing device is connected to the input end of the first-level laser oscillation reflection cavity through a closed external optical path, the output ends of all first-level laser oscillation reflection cavities are connected to the input end of the same second-level laser oscillation reflection cavity through a closed external optical path, and the output end of the second-level laser oscillation reflection cavity is directly connected to the secondary focusing device.

[0018] The laser beam transmission efficiency is high and the energy loss is low.

[0019] As an optimized technical solution, the first-level laser swing reflection cavity and the second-level laser swing reflection cavity are both provided with an X-axis reflection lens and a Y-axis reflection lens driven by a swing motor. The swing motor is controlled by a laser beam motion trajectory control system. The swing motor drives the X-axis reflection lens and the Y-axis reflection lens to deflect back and forth along the X-axis and Y-axis respectively, thereby controlling the deflection of the laser beam in the XY plane, causing the laser beam to perform continuous rotation motion according to a set trajectory, and to perform welding along a set weld trajectory.

[0020] The laser beam motion trajectory control system converts the set laser beam motion path into a signal voltage value, and controls the motion of the reflective lenses in all primary laser swing reflective cavities in a linked manner.

[0021] As an optimized technical solution, a preset swing path diagram, laser beam swing mode, and swing speed can be selected in the setting software of the laser beam motion trajectory control system.

[0022] The appropriate swing path diagram, laser beam swing mode and swing speed can be selected according to different welding requirements.

[0023] The present invention also discloses a multi-spot laser welding method, which uses the multi-spot laser welding device described in any of the above schemes, and comprises the following steps:

[0024] S1. The laser generator emits a laser beam, which is transmitted to the light-splitting interference cavity of the beam splitter, so that the laser beam is divided into multiple beams, and then transmitted to each variable collimation and focusing device respectively;

[0025] S2, a variable collimation focal length device collimates, expands and focuses each laser beam;

[0026] S3. The multiple laser beams that have been initially focused are transmitted to the primary laser swing reflection cavity respectively.

[0027] S4, the laser beam in the primary laser oscillation reflection cavity performs continuous rotational motion along a defined trajectory;

[0028] S5, the laser beam is transmitted to the secondary laser oscillating reflection cavity after passing through the primary laser oscillating reflection cavity, and the laser beam in the secondary laser oscillating reflection cavity moves along the set track of the weld;

[0029] S6. After the laser beam passes through the secondary laser swing reflection cavity, the secondary focusing device performs secondary focusing on the laser beam and compensates for the focal length differences at different positions;

[0030] S7. The laser beam after secondary focusing is projected onto the surface of the workpiece to be welded, and a molten pool is formed along the set track of the weld to complete the welding.

[0031] The beam splitter changes the laser beam from one beam to multiple beams, and its energy distribution also changes from a single distribution to a multi-beam distribution, thereby achieving a multi-spot energy distribution effect; by using a primary laser swing reflection cavity, the corresponding light spot is made to perform a circular reciprocating periodic motion to achieve a circular energy distribution effect; the light beam that realizes the multi-spot motion effect through the secondary laser swing reflection cavity moves according to the set welding trajectory path; the secondary focusing device re-focuses and compensates for the focal length deviation caused by the laser displacement, so that the laser focus is always located on the surface of the welding workpiece when the light beam that realizes the multi-spot motion effect moves, thereby achieving consistency and continuity of laser energy output; the welding method can effectively solve abnormal defects such as "tooth root" shaped molten pool, explosion point, spatter, weld penetration, and high porosity during welding, and can prevent the generation of cracks in the solidification stage, improve the overcurrent capacity of lithium-ion batteries, reduce the overcurrent resistance, enhance the weld strength, and greatly improve the welding efficiency.

[0032] As an optimized technical solution, the spectroscopic interference cavity distributes the laser energy evenly to each laser beam, and each laser beam output by the spectroscopic interference cavity has the same wavelength and direction.

[0033] Ensure the consistency and continuity of laser energy output.

[0034] As an optimized technical solution, the variable collimation focal length device makes the collimation distance and focal length of each laser beam consistent, and the spot size of each laser beam after focusing is consistent.

[0035] Ensure the consistency and continuity of laser energy output.

[0036] As an optimized technical solution, the angle at which the laser beam enters the primary laser swing reflection cavity is fixed.

[0037] Ensure the consistency and continuity of laser energy output.

[0038] As an optimized technical solution, all laser beams in the secondary laser oscillation reflection cavity move along a uniform trajectory, and all light spots output by the secondary laser oscillation reflection cavity have the same focal length.

[0039] Ensure the consistency and continuity of laser energy output. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic structural diagram of a multi-spot laser welding device according to a first embodiment of the present invention.

[0041] Figure 2 It is a schematic diagram of the light spot distribution type of the first embodiment of the present invention.

[0042] Figure 3 It is a schematic diagram of the laser swing direction and motion trajectory of the first embodiment of the present invention.

[0043] Figure 4 It is a schematic diagram of the internal swing principle of the laser swing reflection cavity in Example 1 of the present invention.

[0044] Figure 5 It is a schematic diagram of the light spot distribution type of the second embodiment of the present invention.

[0045] Figure 6 It is a schematic diagram of the light spot distribution type of the third embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0047] Embodiment 1

[0048] like Figure 1As shown, an embodiment of the present invention discloses a multi-spot laser welding device, including a laser generator 1, a beam splitter 2, a variable collimation and focusing device 3, a primary laser oscillating reflection cavity 4, a secondary laser oscillating reflection cavity 5 and a secondary focusing device 6.

[0049] The output end of the laser generator 1 is connected to the input end of the beam splitter 2 through an optical fiber of a certain length. The four output ends of the beam splitter 2 are respectively connected to the variable collimation and focusing device 3 and the first-level laser oscillation reflection cavity 4 in sequence, that is, the output end of the beam splitter 2 is connected to the variable collimation and focusing device 3 through an optical fiber or a closed external optical path, the output end of the variable collimation and focusing device 3 is connected to the input end of the first-level laser oscillation reflection cavity 4 through a closed external optical path, the output ends of all the first-level laser oscillation reflection cavities 4 are connected to the input end of the same second-level laser oscillation reflection cavity 5 through a closed external optical path, and the output end of the second-level laser oscillation reflection cavity 5 is directly connected to the secondary focusing device 6.

[0050] The laser generator 1 adopts a disk-type solid-state laser.

[0051] Four partially reflecting lenses arranged in parallel are arranged in the light-splitting interference cavity of the beam splitter 2, and the partially reflecting lenses are placed at 45° relative to the incident light path; among them, the No. 1 partially reflecting lens makes: 1 / 4 of the energy of the laser beam is reflected at an angle of 90°, and 3 / 4 of the energy passes through the lens; the No. 2 partially reflecting lens makes: 1 / 3 of the energy of the laser beam is reflected at an angle of 90°, and 2 / 3 of the energy passes through the lens; the No. 3 partially reflecting lens makes: 1 / 2 of the energy of the laser beam is reflected at an angle of 90°, and 1 / 2 of the energy passes through the lens; the No. 4 lens is a total reflection lens, which makes 100% of the energy of the laser beam reflected at an angle of 90°; the energy distribution form of the laser beam is Gaussian distribution.

[0052] The focal length of the variable collimating lens of the variable collimating and focusing device 3 is 165 mm, and the focal length of the focusing lens is 180 mm. After the laser is collimated, expanded, and focused, the focusing diameter of the laser beam is 0.15 mm.

[0053] like Figure 2 , Figure 3 As shown, four primary laser oscillating reflection cavities 4 are arranged around the beam splitter 2, and the four primary laser oscillating reflection cavities 4 are distributed at the four vertices A1, A2, B1, and B2 of the rhombus, wherein: point A1 is 3 mm away from point A2, and point B1 is 1.5 mm away from point B2; the laser beams in two primary laser oscillating reflection cavities 4 at diagonal positions perform circular motion in the same direction, the laser beams at points A1 and A2 perform clockwise circular motion at a speed of 220 mm / s; the laser beams at points B1 and B2 perform counterclockwise circular motion at a speed of 300 mm / s.

[0054] like Figure 4As shown, both the primary laser oscillating reflection cavity 4 and the secondary laser oscillating reflection cavity 5 are provided with an X-axis reflection lens and a Y-axis reflection lens driven by an oscillating motor. The oscillating motor is controlled by the laser beam motion trajectory control system. The X-axis reflection lens and the Y-axis reflection lens are driven by the oscillating motor to deflect back and forth along the X-axis and the Y-axis respectively, thereby controlling the deflection of the laser beam in the XY plane, so that the laser beam performs continuous rotation according to the set trajectory, and performs welding along the set trajectory of the weld. In order to make each light spot have an independent oscillating trajectory and speed, the number of the primary laser oscillating reflection cavity 4 is the same as the number of the light spots, that is, four; the area of ​​the reflection lens in the secondary laser oscillating reflection cavity 5 is ≥78.5mm 2 The movement range of the laser beam in the secondary laser swing reflection cavity 5 is 200mm to 600mm in the X direction and 200mm to 400mm in the Y direction.

[0055] The setting software of the laser beam motion trajectory control system can select a preset swing path diagram and laser beam swing mode and swing speed. The laser beam motion trajectory control system converts the set laser beam motion path into a signal voltage value, and controls the movement of the reflective lenses in all the first-level laser swing reflection cavities 4 in a linked manner; the laser beam motion range is a circle with a diameter ≥5mm, the laser beam motion speed range in the first-level laser swing reflection cavity 4 is 0-300mm / s, and the laser beam motion speed range in the second-level laser swing reflection cavity 5 is 0-500mm / s.

[0056] The secondary focusing device 6 is a set of concave mirrors with a size of 650mm×650mm, which is used to compensate for the aberration caused by the movement position of the laser beam; the secondary focusing device 6 has the ability to keep the focal length of all laser beams within the range of 200mm~600mm in the X direction and 200mm~400mm in the Y direction consistent.

[0057] The embodiment of the present invention further discloses a multi-spot laser welding method, which uses the multi-spot laser welding device described in any of the above schemes, and includes the following steps:

[0058] S1, the laser beam emitted by the laser generator 1 is coupled into the optical fiber, and the laser beam is transmitted to the beam splitting interference cavity of the beam splitter 2 through the optical fiber, so that the laser beam is divided into four beams from one beam, and then transmitted to each variable collimation and focusing device 3 respectively. The beam splitting interference cavity distributes the laser energy evenly to each laser beam, and each laser beam output by the beam splitting interference cavity has the same wavelength and direction;

[0059] S2, the variable collimation focal length device 3 collimates, expands and focuses each laser beam, and the collimation distance and focal length of each laser beam by the variable collimation focal length device 3 are consistent, and the spot size of each laser beam after focusing is consistent;

[0060] S3. The four laser beams that have been initially focused are respectively transmitted to the primary laser oscillating reflection cavity 4. The angles at which the laser beams enter the primary laser oscillating reflection cavity 4 are fixed. The energy loss of the laser beams after passing through the primary laser oscillating reflection cavity 4 is ≤0.5%.

[0061] S4, laser beam motion trajectory control system controls the swing motor to drive the X-axis reflective lens and the Y-axis reflective lens to deflect back and forth along the X-axis and Y-axis respectively according to the set laser beam motion trajectory, thereby controlling the deflection of the laser beam in the XY plane, so that the laser beam in the primary laser swing reflection cavity 4 performs continuous rotation motion according to the defined trajectory;

[0062] S5, the laser beam is transmitted to the secondary laser swing reflection cavity 5 through the external optical path after passing through the primary laser swing reflection cavity 4, and the array position of the laser beam does not change after entering the secondary laser swing reflection cavity 5; the laser beam motion trajectory control system controls the swing motor to drive the X-axis reflection lens and the Y-axis reflection lens to deflect back and forth along the X-axis and Y-axis respectively according to the set laser beam motion trajectory, thereby controlling the deflection of the laser beam in the XY plane, so that the laser beam in the secondary laser swing reflection cavity 5 moves along the set trajectory of the weld; all laser beams in the secondary laser swing reflection cavity 5 move according to a unified trajectory, and all the spots output by the secondary laser swing reflection cavity 5 have the same focal length; taking a straight weld with a length of 100 mm as an example, the overall movement speed of the laser beam is 70 mm / s;

[0063] S6, after the laser beam passes through the secondary laser swing reflection cavity 5, the secondary focusing device 6 performs secondary focusing on the laser beam and compensates for the focal length difference at different positions;

[0064] S7. The laser beam after secondary focusing is projected onto the surface of the workpiece 7 to be welded. The movement path of the laser beam is the superposition state of the swing path of the primary laser swing reflection cavity 4 and the swing path of the secondary laser swing reflection cavity 5. The projection distance is 200mm~800mm. The laser beam forms a molten pool along the set trajectory of the weld to complete the welding. Taking the distance of 472mm between the workpiece 7 to be welded and the laser head as an example, at this time, the spot diameter of the laser beam projected on the workpiece 7 to be welded is 0.735mm, the diameter of the halo formed by the light beams at points A1 and A2 is 3.4mm, the diameter of the halo formed by points B1 and B2 is 1.2mm, the molten pool depth is 4mm, and the molten pool width is 5mm.

[0065] When the workpiece 7 to be welded is an aluminum alloy, the recommended number of beams is two to five, which can also be increased or decreased according to the welding base material, material, thickness and welding requirements. The laser beam rotation trajectory must revolve around the same axis and the rotation direction must remain consistent.

[0066] This embodiment achieves a multi-spot energy distribution effect by (1) changing the light beam from one beam to four beams, and changing its energy distribution from a single distribution to a four-point distribution; (2) using a primary laser swing reflection cavity 4 to make the corresponding A1, A2, B1, and B2 light beams perform a circular reciprocating periodic motion to achieve a ring-shaped energy distribution effect, wherein the A1 and A2 light beams form an outer light ring; and the B1 and B2 light beams form an inner light ring; (3) using a secondary laser swing reflection cavity 5 to achieve the effect of simultaneous movement of the above four light spots within an elliptical range; and (4) by refocusing and compensating for the focal length deviation caused by laser displacement, it is possible to keep the laser focus always on the surface of the welding workpiece when moving within an elliptical range, thereby ensuring the consistency and continuity of laser energy output.

[0067] In this embodiment, a slag spatter collection device was used during the welding process, and a total of 328 slag particles were collected. When the weld surface was observed under a 10x microscope, 82 metal slag particles were adhered around the weld. Compared with ordinary laser welding, the welding process was more stable, the welding molten pool was more stable, and the amount of slag and spatter was significantly reduced.

[0068] The samples after welding in this embodiment were tested, and the welding pull-out forces of 10 groups of samples were tested as follows:

[0069]

[0070] The samples after welding in this embodiment were tested, the welds were longitudinally cut, ground, polished, and immersed in metallographic etching liquid to test the stability of the welding penetration. The depth of the welding pool of 10 groups of samples was tested respectively, and the values ​​were taken at every 1mm distance. The statistical range and data PPK value are as follows:

[0071]

[0072] The samples after welding in this embodiment were tested, and the welds were CT scanned to test the pores in the welding pool. Ten groups of samples were tested respectively, and the porosity in the molten pool (the proportion of pore volume in the molten pool volume) was as follows:

[0073]

[0074] The samples after welding in this embodiment were tested, and the welds were CT scanned to detect whether there were cracks inside the molten pool. No cracks were found in the 10 groups of samples tested.

[0075] Embodiment 2

[0076] The difference between this embodiment and the first embodiment is that:

[0077] The three output ends of the beam splitter 2 are connected to three primary laser swing reflection cavities 4. Three parallel arranged partial reflection lenses are arranged in the beam splitter interference cavity of the beam splitter 2.

[0078] like Figure 5 As shown, three primary laser swing reflection cavities 4 are distributed at three vertices of an equilateral triangle.

[0079] In step S1, the laser beam is divided into three beams.

[0080] In step S3, the three laser beams that have been initially focused are respectively introduced into the primary laser oscillation reflection cavity 4.

[0081] Embodiment 3

[0082] The difference between this embodiment and the first embodiment is that:

[0083] The three output ends of the beam splitter 2 are connected to three primary laser swing reflection cavities 4. Three parallel arranged partial reflection lenses are arranged in the beam splitter interference cavity of the beam splitter 2.

[0084] like Figure 6 As shown, three primary laser swing reflection cavities 4 are evenly spaced and distributed on a straight line with a spacing of 0.5 mm.

[0085] The laser beams in each primary laser swing reflection cavity 4 perform circular motion in the same direction, which is counterclockwise circular motion in this embodiment, and the angular velocity is 150 rad / s.

[0086] This embodiment can also obtain welding with excellent performance similar to that of the first embodiment, but the difference is that a deeper molten pool can be obtained compared with the first embodiment, and the laser penetration performance is improved.

[0087] In order to accurately control key indicators such as welding melt width, melting depth and porosity, the present invention has multiple first-level laser oscillating reflection cavities 4 evenly distributed around the same axis, that is, the above-mentioned "matrix distribution", "triangular distribution" and "straight line distribution"; the laser beam rotation trajectory in each first-level laser oscillating reflection cavity 4 is carried out around its axis, and the laser beam rotation direction in the first-level laser oscillating reflection cavity 4 symmetrical on both sides of the axis is consistent; when the material to be welded is aluminum alloy, the recommended number of beams is 2-5, which can also be increased or decreased according to the welding parent material, material, thickness and welding requirements.

[0088] Comparative Example

[0089] In this comparative example, the TRUMPF disc-type solid-state laser TruDisk is used as the laser source. After the light beam is emitted, it is immediately coupled into the optical fiber. The laser beam is introduced into the TRUMPF PFO-33 galvanometer laser system through a certain length of optical fiber. The spot swing parameters are set: swing type circle, radius: 1.5mm, swing frequency 120Hz, and the basic welding parameters are set: power: appropriate value, speed: 87mm / s, defocus: +2mm.

[0090] The difference between this comparative example and the first embodiment is that there is only one light beam, and the light beam is reflected by an ordinary galvanometer to achieve a small-range swing motion and a large-range motion.

[0091] In this comparative example, a slag spatter collection device was used during the welding process, and a total of 2,944 slag particles were collected. When the weld surface was observed under a 10x microscope, 907 metal slag particles were adhered to the weld. Compared with Example 1, the welding pool had boiling phenomenon, the amount of slag and spatter increased significantly, and the welding process showed multiple unstable situations.

[0092] The samples after welding in this comparative example were tested, and the welding pull-out forces of 10 groups of samples were tested as follows:

[0093]

[0094] It can be seen that the tensile strength of the weld in Example 1 is significantly better than that in the comparative example.

[0095] The samples after welding in this comparative example were tested. The weld seams were longitudinally cut, ground, and polished. They were immersed in metallographic etching liquid and the stability of the welding penetration was tested. The depth of the welding pool of 10 groups of samples was tested separately. The values ​​were taken at intervals of 1 mm. The statistical range and standard deviation are as follows:

[0096]

[0097] It can be seen that the weld penetration consistency of Example 1 is significantly better than that of the comparative example.

[0098] The samples after welding in this comparative example were tested, and the welds were CT scanned to test the pores in the welding molten pool. Ten groups of samples were tested respectively, and the porosity in the molten pool (the proportion of pore volume in the molten pool volume) was as follows:

[0099]

[0100] It can be seen that the weld porosity of Example 1 is significantly better than that of the comparative example.

[0101] The samples after welding in this comparative example were tested, and the welds were CT scanned to detect whether there were cracks inside the molten pool. After testing 10 groups of samples, it was found that one group of welds had welding solidification cracks with a length of 72 μm and a width of 0.8 μm.

[0102] It can be seen that the crack suppression performance of the welding process in Example 1 is better than that in the comparative example.

[0103] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, it should be understood by those skilled in the art that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-spot laser welding device, characterized in that: The invention comprises a laser generator, a beam splitter, a variable collimation and focusing device, a primary laser oscillating reflection cavity, a secondary laser oscillating reflection cavity and a secondary focusing device, wherein the laser generator is connected to the input end of the beam splitter, and the multiple output ends of the beam splitter are respectively connected to the variable collimation and focusing device and the primary laser oscillating reflection cavity in sequence, the output ends of all the primary laser oscillating reflection cavities are connected to the input end of the same secondary laser oscillating reflection cavity, and the output end of the secondary laser oscillating reflection cavity is connected to the secondary focusing device.

2. The multi-spot laser welding device according to claim 1, characterized in that: Multiple primary laser oscillating reflection cavities are evenly distributed around the same axis, the laser beam rotation trajectory in each primary laser oscillating reflection cavity is around its axis, and the laser beam rotation direction in the primary laser oscillating reflection cavity symmetrical on both sides of the axis is consistent.

3. The multi-spot laser welding device according to claim 1, characterized in that: The output end of the laser generator is connected to the input end of the beam splitter through an optical fiber, the output end of the beam splitter is connected to the variable collimation and focusing device through an optical fiber or a closed external optical path, the output end of the variable collimation and focusing device is connected to the input end of the first-level laser oscillation reflection cavity through a closed external optical path, the output ends of all first-level laser oscillation reflection cavities are connected to the input end of the same second-level laser oscillation reflection cavity through a closed external optical path, and the output end of the second-level laser oscillation reflection cavity is directly connected to the secondary focusing device.

4. The multi-spot laser welding device according to claim 1, characterized in that: The first-level laser swing reflection cavity and the second-level laser swing reflection cavity are both provided with an X-axis reflection lens and a Y-axis reflection lens driven by a swing motor. The swing motor is controlled by a laser beam motion trajectory control system. The swing motor drives the X-axis reflection lens and the Y-axis reflection lens to deflect back and forth along the X-axis and the Y-axis respectively, thereby controlling the deflection of the laser beam in the XY plane, so that the laser beam performs continuous rotation motion according to the set trajectory, and performs welding along the set trajectory of the weld.

5. The multi-spot laser welding device according to claim 4, characterized in that: The setting software of the laser beam motion trajectory control system can select a preset swing path diagram and a laser beam swing mode and a swing speed.

6. A multi-spot laser welding method, using the multi-spot laser welding device according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. The laser generator emits a laser beam, which is transmitted to the light-splitting interference cavity of the beam splitter, so that the laser beam is divided into multiple beams, and then transmitted to each variable collimation and focusing device respectively; S2, a variable collimation focal length device collimates, expands and focuses each laser beam; S3. The multiple laser beams that have been initially focused are transmitted to the primary laser swing reflection cavity respectively. S4, the laser beam in the primary laser oscillation reflection cavity performs continuous rotational motion along a defined trajectory; S5, the laser beam is transmitted to the secondary laser oscillating reflection cavity after passing through the primary laser oscillating reflection cavity, and the laser beam in the secondary laser oscillating reflection cavity moves along the set track of the weld; S6. After the laser beam passes through the secondary laser swing reflection cavity, the secondary focusing device performs secondary focusing on the laser beam and compensates for the focal length differences at different positions; S7. The laser beam after secondary focusing is projected onto the surface of the workpiece to be welded, and a molten pool is formed along the set track of the weld to complete the welding.

7. The multi-spot laser welding method according to claim 6, characterized in that: The beam splitting interference cavity distributes the laser energy evenly to each laser beam, and each laser beam output by the beam splitting interference cavity has the same wavelength and direction.

8. The multi-spot laser welding method according to claim 6, characterized in that: The collimation distance and focal length of each laser beam are consistent with the variable collimation focal length device, and the spot size of each laser beam after focusing is consistent.

9. The multi-spot laser welding method according to claim 6, characterized in that: The angle at which the laser beam enters the primary laser swing reflection cavity is fixed.

10. The multi-spot laser welding method according to claim 6, characterized in that: All laser beams in the secondary laser swing reflection cavity move along a uniform trajectory, and all light spots output by the secondary laser swing reflection cavity have the same focal length.

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