A laser welding method and welding apparatus

Abstract

The application provides a laser welding method and a welding device. The laser welding method adopts a welding device carrying a ring-shaped spot laser, and the emitted ring-shaped laser beam and central laser beam are welded along a preset welding track of a sealing nail. The power P1 of the emitting part of the ring-shaped spot laser corresponding to the central laser beam is set to 600-1400 W, and the power P2 of the emitting part of the ring-shaped spot laser corresponding to the ring-shaped laser beam is set to 800-1800 W. The welding device carrying the ring-shaped spot laser can adjust the beam mode of the ring-shaped laser beam and the central laser beam, can make the keyhole more stable during the welding process, and the inventor has found through experiments that when the power of the emitting part of the ring-shaped spot laser corresponding to the central laser beam is set to the range of 600-1400 W and the power of the emitting part of the ring-shaped spot laser corresponding to the ring-shaped laser beam is set in the range of 800-1800 W, the welding quality is good and the welding speed is obviously improved.

Description

Technical Field

[0001] This application belongs to the field of laser welding technology, and more specifically, relates to a laser welding method and welding equipment. Background Technology

[0002] With the continuous development of new energy technologies, the demand for lithium batteries is increasing, and therefore, the requirements for lithium battery production and quality are also becoming higher.

[0003] In the production of lithium batteries, one crucial step is to use laser welding to attach sealing pins to the electrolyte filling port of the battery casing to seal it. However, current laser welding techniques for sealing pins and battery casings suffer from defects such as porosity, cracks, and spatter, as well as slow welding speeds, resulting in low welding quality and low production yield.

[0004] Therefore, how to improve the welding quality and speed of the sealing nails and battery casing needs to be addressed. Summary of the Invention

[0005] This application provides a laser welding method that can improve the welding quality and speed of the sealing nail and the battery casing.

[0006] The laser welding method of this application uses a welding device equipped with a ring-shaped laser beam to weld the emitted ring laser beam and the central laser beam along the preset welding trajectory of the sealing nail. The power P1 of the emitting part of the ring-shaped laser beam corresponding to the central laser beam is set to 600-1400W, and the power P2 of the emitting part of the ring-shaped laser beam corresponding to the ring laser beam is set to 800-1800W.

[0007] Furthermore, the central laser beam is configured in pulse slow-descent mode, and the ring laser beam is configured in constant value continuous output mode.

[0008] Furthermore, each cycle of the pulse descent mode of the central laser beam sequentially includes an energy-raising stage, a welding stage, a first energy-lowering stage, and a second energy-lowering stage. The duration of each cycle of the pulse descent mode is set to T1, and the duration of the energy-raising stage is set to t. 11 The duration of the welding stage is set as t. 12 The duration of the first energy reduction stage is set to t. 13 The duration of the second energy reduction stage is set to t. 14 T1 = t 11 +t 12 +t 13 +t 14 0.2ms≤t 11 ≤0.5ms, 2ms≤t 12≤5ms, 0.1ms≤t 13 ≤1ms, 1ms≤t 14 ≤2.5ms; during the welding stage, the power of the emitting part of the ring spot laser corresponding to the central laser beam is set to 80% to 100% of P1; at the transition point between the first energy reduction stage and the second energy reduction stage, the power of the emitting part of the ring spot laser corresponding to the central laser beam is set to 40% to 60% of P1; the frequency of the pulse slow-descent mode is set to 20Hz to 100Hz, and the welding speed is set to 40mm / s to 60mm / s.

[0009] Furthermore, the central laser beam and the ring laser beam are respectively set to modulation mode, the central laser beam and the ring laser beam are frequency synchronized, the power P1 of the emitting part of the ring spot laser corresponding to the central laser beam is set to 800~1300W, and the power P2 of the emitting part of the ring spot laser corresponding to the ring laser beam is set to 1000~1800W.

[0010] Furthermore, the duration of each cycle of the modulation mode is set to T2, and each cycle of the modulation mode includes a peak phase and a trough phase. The peak phase corresponds to the phase in which the central laser beam and the ring laser beam are used for welding, and the trough phase corresponds to the phase in which the central laser beam and the ring laser beam stop welding. The duration of the peak phase is set to t. 21 The duration of the trough phase is set as t. 22 T2 = t 21 +t 22 30%≤t 21 / T2≤70%, the modulation frequency of the modulation mode is set to 0.1KHz~0.5KHz, and the welding speed is set to 60mm / s~100mm / s.

[0011] Furthermore, the central laser beam and the ring laser beam are respectively set to a constant value continuous output mode, the power P1 of the emitting part of the ring spot laser corresponding to the central laser beam is set to 600-800W, and the power P2 of the emitting part of the ring spot laser corresponding to the ring laser beam is set to 1000-1800W.

[0012] Furthermore, the welding speed is set to 60mm / s to 100mm / s.

[0013] Furthermore, the central laser beam and the ring laser beam are respectively set to pulse slow-descent mode, the central laser beam and the ring laser beam are set to the same frequency and synchronously, the power P1 of the emitting part of the ring spot laser corresponding to the central laser beam is set to 600~1400W, and the power P2 of the emitting part of the ring spot laser corresponding to the ring laser beam is set to 1000~1800W.

[0014] Furthermore, each cycle of the pulse descent mode sequentially includes an energy-raising stage, a welding stage, a first energy-reducing stage, and a second energy-reducing stage. The duration of each cycle of the pulse descent mode is set to T3, and the duration of the energy-raising stage is set to t. 31 The duration of the welding stage is set as t. 32 The duration of the first energy reduction stage is set to t. 33 The duration of the second energy reduction stage is set to t. 34 T3 = t 31 +t 32 +t 33 +t 34 0.2ms≤t 31 ≤0.5ms, 2ms≤t 32 ≤5ms, 0.1ms≤t 33 ≤1ms, 1ms≤t 34 The pulse descent mode frequency is set to 20Hz~100Hz, the welding speed is set to 10mm / s~60mm / s, and the central laser beam and the ring laser beam are synchronized with respect to the energy boosting stage, the welding stage, the first energy reduction stage, and the second energy reduction stage, respectively. In the welding stage, the power of the emitting part of the ring laser corresponding to the central laser beam is set to 80%~100% of P1, and the power of the emitting part of the ring laser corresponding to the ring laser beam is set to 80%~100% of P2. At the transition point between the first energy reduction stage and the second energy reduction stage, the power of the emitting part of the ring laser corresponding to the central laser beam is set to 40%~60% of P1, and the power of the emitting part of the ring laser corresponding to the ring laser beam is set to 40%~60% of P2.

[0015] Furthermore, the sealing nail is made of aluminum, the collimation focal length f1 of the welding head of the welding equipment is set to 100mm~150mm, the focusing focal length f2 of the welding head of the welding equipment is set to 200mm~300mm, and 1:2≤f1 / f2≤1:3.

[0016] Furthermore, 1:1.5≤P1:P2≤1:2.

[0017] This application also provides a welding apparatus capable of employing any of the laser welding methods described above.

[0018] The welding equipment of this application, which uses a ring-shaped laser beam, is used to weld sealing nails to the lithium battery casing. Specifically, the welding equipment is controlled to weld the emitted ring laser beam and the central laser beam along a preset welding trajectory of the sealing nail. This preset welding trajectory can be understood as the trajectory parameters that are pre-input into the control system of the welding equipment.

[0019] Among them, the welding equipment equipped with a ring-shaped laser beam has adjustable beam modes for both the ring laser beam and the central laser beam. This allows for more stable keyholes, faster welding speeds, more uniform welding, and better quality during the welding process. Furthermore, the inventors' experiments have shown that when the power of the emitting part of the ring-shaped laser beam corresponding to the central laser beam is set to the range of 600–1400W, and the power of the emitting part of the ring-shaped laser beam corresponding to the ring laser beam is set to the range of 800–1800W, the welding quality is significantly improved when used for welding sealing nails, and the welding speed is also increased. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the laser energy waveform in an embodiment of this application, wherein the central laser beam is set to pulse slow-down mode and the ring laser beam is set to constant value continuous output mode;

[0022] Figure 2 This is a schematic diagram of the welding of a sealing nail to a lithium battery casing in one embodiment where the central laser beam is set to pulse slow-descent mode and the ring laser beam is set to constant value continuous light output mode.

[0023] Figure 3 This is a schematic diagram of the welding of a sealing nail to a lithium battery casing in another embodiment where the central laser beam is set to pulse slow-descent mode and the ring laser beam is set to constant value continuous light output mode.

[0024] Figure 4 This is a schematic diagram of the welding of a sealing nail to a lithium battery casing in another embodiment where the central laser beam is set to pulse slow-descent mode and the ring laser beam is set to constant value continuous light output mode.

[0025] Figure 5 A schematic diagram of the laser energy waveforms of the central laser beam and the ring laser beam in a modulation mode according to an embodiment of this application;

[0026] Figure 6 This is a schematic diagram of the welding of a sealing pin to a lithium battery casing in one embodiment of a modulation mode using a central laser beam and a ring laser beam.

[0027] Figure 7 A schematic diagram illustrating the welding of a sealing pin to a lithium battery casing in another embodiment employing a modulation mode with a central laser beam and a ring laser beam;

[0028] Figure 8 A schematic diagram of the welding of a sealing pin to a lithium battery casing in another embodiment using a modulation mode with a central laser beam and a ring laser beam;

[0029] Figure 9 A schematic diagram of the laser energy waveforms of the central laser beam and the ring laser beam in an embodiment of this application, respectively set to a constant value continuous output mode;

[0030] Figure 10 This is a schematic diagram of the welding of a sealing nail to a lithium battery casing in one embodiment where the central laser beam and the ring laser beam are respectively set to a constant value continuous light output mode.

[0031] Figure 11 This is a schematic diagram of the welding of a sealing nail to a lithium battery casing in another embodiment where the central laser beam and the ring laser beam are respectively set to a constant value continuous light output mode;

[0032] Figure 12 This is a schematic diagram of the welding of a sealing nail to a lithium battery casing in another embodiment where the central laser beam and the ring laser beam are respectively set to a constant value continuous light output mode.

[0033] Figure 13 This is a schematic diagram of the laser energy waveforms of the central laser beam and the ring laser beam in an embodiment of this application, respectively set to pulse slow-down mode;

[0034] Figure 14 This is a schematic diagram of the welding of a sealing nail to a lithium battery casing in one embodiment where the central laser beam and the ring laser beam are respectively set to pulse slow-descent mode;

[0035] Figure 15 This is a schematic diagram of welding a sealing nail to a lithium battery casing in another embodiment where the central laser beam and the ring laser beam are respectively set to pulse slow-descent mode;

[0036] Figure 16 This is a schematic diagram of the welding of a sealing nail to a lithium battery casing, in another embodiment where the central laser beam and the ring laser beam are respectively set to pulse slow-descent mode.

[0037] The following are the labeling elements in the figure:

[0038] 10. Sealing nail; 20. Lithium battery casing. Detailed Implementation

[0039] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0040] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0041] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0043] The laser welding method provided in the embodiments of this application will now be described. The laser welding method provided in the embodiments of this application includes: using a welding device equipped with a ring-shaped laser beam to weld the emitted ring laser beam and the central laser beam along a preset welding trajectory of the sealing nail 10, wherein the power P1 of the emitting part of the ring-shaped laser beam corresponding to the central laser beam is set to 600-1400W, and the power P2 of the emitting part of the ring-shaped laser beam corresponding to the ring laser beam is set to 800-1800W.

[0044] The welding equipment in this application embodiment, equipped with a ring-shaped laser beam, is used to weld the sealing nail 10 to the lithium battery casing 20. Specifically, the welding equipment is controlled to weld the emitted ring laser beam and the central laser beam along a preset welding trajectory of the sealing nail 10. The preset welding trajectory can be understood as the trajectory parameters that are pre-input into the control system of the welding equipment.

[0045] Among them, the welding equipment equipped with a ring-shaped laser beam has adjustable beam modes for both the ring laser beam and the central laser beam. This enables more stable keyholes, faster welding speed, more uniform welding, and better quality during the welding process. The inventors' experiments have shown that when the power of the emitting part of the ring-shaped laser beam corresponding to the central laser beam is set to the range of 600-1400W and the power of the emitting part of the ring-shaped laser beam corresponding to the ring laser beam is set to the range of 800-1800W, the welding quality is significantly improved when used for welding the sealing nail 10, and the welding speed is also increased.

[0046] Example 1, such as Figures 1 to 4 As shown:

[0047] The central laser beam is set to a pulsed slow-decay mode, while the ring laser beam is set to a constant-value continuous output mode. During the welding of the sealing nail 10 using this method, the emitting part of the ring laser corresponding to the ring spot laser in the constant-value continuous output mode continuously inputs energy into the molten pool at a constant power, which can stabilize the molten pool to a large extent. Therefore, the keyhole generated by the central laser beam welding will not open or close with the switching on and off in the pulsed mode. After the welding process is completed, the power of the central laser beam is gradually reduced, making the temperature change of the molten pool smoother. This results in a good weld appearance and a defect-free weld.

[0048] Specifically, each cycle of the pulsed descent mode of the central laser beam sequentially includes an energy-raising stage, a welding stage, a first energy-lowering stage, and a second energy-lowering stage. The duration of each cycle of the pulsed descent mode is set to T1, and the duration of the energy-raising stage is set to t. 11 The duration of the welding stage is set to t. 12 The duration of the first energy reduction stage is set to t. 13 The duration of the second energy reduction stage is set to t. 14 T1 = t 11 +t 12 +t 13 +t 14 0.2ms≤t 11 ≤0.5ms, 2ms≤t 12 ≤5ms, 0.1ms≤t 13 ≤1ms, 1ms≤t 14 ≤2.5ms; During the welding stage, the power of the emitting part of the ring spot laser corresponding to the central laser beam is set to 80% to 100% of P1; At the transition point between the first and second energy reduction stages, the power of the emitting part of the ring spot laser corresponding to the central laser beam is set to 40% to 60% of P1; The frequency of the pulse slow-descent mode is set to 20Hz to 100Hz, and the welding speed is set to 40mm / s to 60mm / s.

[0049] In the welding method that uses a pulsed slow-down mode for the central laser beam and a constant-value continuous output mode for the ring laser beam, the ring laser beam can be understood as always being in a stable output state when the central laser beam is in the output state. Of course, the power of the ring laser beam also changes during the output and off phases, but the corresponding duration is very short and has a negligible impact on the welding process of the central laser beam.

[0050] The duration of one cycle of the emission state of the central laser beam is T1. Within one cycle, the central laser beam sequentially undergoes an energy-raising stage, a welding stage, a first energy-reducing stage, and a second energy-reducing stage at a frequency of 20Hz to 100Hz. During the energy-raising stage, the power of the emitting part of the ring-shaped laser corresponding to the central laser beam is at t... 11 The power is increased from zero to the required welding power over a period of time, that is, from zero to 80% to 100% of P1; during the welding stage, the emitting part of the ring spot laser corresponding to the central laser beam outputs a stable power of 80% to 100% of P1. 12 The duration is used to complete the welding process. In the first energy reduction stage, the power of the emitting part of the ring-shaped laser corresponding to the central laser beam gradually decreases from 80%–100% of P1 to 40%–60% of P1. In the second energy reduction stage, the power of the emitting part of the ring-shaped laser corresponding to the central laser beam further gradually decreases from 40%–60% of P1 to zero. Thus, the emitting part of the ring-shaped laser corresponding to the central laser beam completes one emission cycle. Under the above conditions, the welding speed can reach 40 mm / s–60 mm / s, enabling rapid welding. The inventors of this application discovered through experiments that, within the aforementioned laser power range, setting the duration parameter of each stage to 0.2 ms ≤ t... 11 ≤0.5ms, 2ms≤t 12 ≤5ms, 0.1ms≤t 13 ≤1ms, 1ms≤t 14 Within a range of ≤2.5ms, the weld quality is better and the welding speed is faster.

[0051] like Figure 1 The diagram shows the laser energy waveforms of the central laser beam and the ring laser beam in Example 1, where a represents the laser energy waveform of the central laser beam and b represents the laser energy waveform of the ring laser beam.

[0052] like Figure 2 As shown, the power P1 of the emitter of the ring-shaped laser corresponding to the central laser beam is set to 600W, and the power of the emitter of the ring-shaped laser corresponding to the central laser beam during the welding stage is set to 100% of P1. 11 Set to 0.2ms, t12 Set to 5ms, t 13 Set to 1ms, t 14 The welding diagram of the sealing nail 10 was obtained under the following parameters: 2.5ms pulse descent mode frequency set to 60Hz, power of the ring laser corresponding to the center laser beam at the transition point between the first and second energy reduction stages set to 40% of P1, welding speed set to 40mm / s, and power of the ring laser corresponding to the ring laser beam P2 set to 800W. As shown in the figure, the appearance is good. Through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding.

[0053] like Figure 3 As shown, the power P1 of the emitter of the ring-shaped laser corresponding to the central laser beam is set to 1400W, and the power of the emitter of the ring-shaped laser corresponding to the central laser beam during the welding stage is set to 80% of P1. 11 Set to 0.5ms, t 12 Set to 2ms, t 13 Set to 0.5ms, t 14 The welding diagram of the sealing nail 10 was obtained under the following parameters: 1ms pulse slow-descent mode frequency set to 100Hz, power of the emitter of the ring spot laser corresponding to the center laser beam at the transition point between the first and second energy reduction stages set to 60% of P1, welding speed set to 60mm / s, and power of the emitter of the ring spot laser corresponding to the ring laser beam set to 1800W. As shown in the figure, the appearance is good, and through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding.

[0054] like Figure 4 As shown, the power P1 of the emitter of the ring-shaped laser corresponding to the central laser beam is set to 1000W, and the power of the emitter of the ring-shaped laser corresponding to the central laser beam during the welding stage is set to 100% of P1. 11 Set to 0.2ms, t 12 Set to 4ms, t 13 Set to 0.5ms, t 14 The welding diagram of the sealing nail 10 was obtained under the following parameters: 2.5ms pulse descent mode frequency set to 80Hz, power of the ring laser corresponding to the center laser beam at the transition point between the first and second energy reduction stages set to 40% of P1, welding speed set to 50mm / s, and power of the ring laser corresponding to the ring laser beam P2 set to 1000W. As shown in the figure, the appearance is good. Through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding.

[0055] Example 2, as Figures 5 to 8 As shown:

[0056] The central laser beam and the ring laser beam are respectively modulated, and their frequencies are synchronized. The power P1 of the emitter of the ring spot laser corresponding to the central laser beam is set to 800-1300W, and the power P2 of the emitter of the ring spot laser corresponding to the ring laser beam is set to 1000-1800W.

[0057] The modulation period of the modulation mode is denoted as T2, where each period includes a peak phase and a trough phase, and the peak duration of the peak phase is denoted as t. 21 The duration of the trough during the trough phase is denoted as t. 22 Peak duration t 21 During this period, the laser continuously emits light at the set maximum power; similarly, the duration of the trough is t. 22 During the period, the laser continuously emits light at the set minimum power. During the peak duration t... 21 Inside, the central laser beam is used for welding; the duration of the low-frequency laser beam is t. 22 Inside, the central laser beam stops welding, thus the duration of the trough is t. 22 Inside, the ring-shaped laser beam can be in the off state. It should be noted that in the modulation mode of this embodiment, the central laser beam and the ring-shaped laser beam are synchronized, that is, they are synchronized on and off, and synchronized during peak and trough phases.

[0058] Where t 21 / t 22 Flexible and adjustable, the correlation is T2 = t 21 +t 22 In modulation mode, the heat input is lower, effectively reducing welding defects caused by excessive heat input. Furthermore, the inventors' experiments revealed that in adjustment mode, when the power of the emitter of the ring-shaped laser corresponding to the central laser beam is set to the range of 800–1300W and the power of the emitter of the ring-shaped laser corresponding to the ring laser beam is set to the range of 1000–1800W, the welding quality is significantly improved when used for welding the sealing nail 10, and the welding speed is also increased.

[0059] Specifically, 30%≤t 21 / T2≤70%, the modulation frequency of the modulation mode is set to 0.1KHz~0.5KHz, and the welding speed is set to 60mm / s~100mm / s. Further experiments by the inventors revealed that when t 21When the duration of / T2 is set to 30% to 70% and the frequency is set to 0.1KHz to 0.5KHz, it can better match the above power range to improve welding quality and welding speed. Under the above conditions, the welding speed can reach 60mm / s to 100mm / s, enabling rapid welding.

[0060] like Figure 5 The figure shows a schematic diagram of the laser energy waveforms of the central laser beam and the ring laser beam in a modulation mode in Example 2, where a represents the schematic diagram of the laser energy waveform of the central laser beam and b represents the schematic diagram of the laser energy waveform of the ring laser beam.

[0061] like Figure 6 As shown, the power P1 of the emitter of the ring laser corresponding to the central laser beam is set to 800W, the power P2 of the emitter of the ring laser corresponding to the ring laser beam is set to 1000W, and the t of the central laser beam and the ring laser beam are... 21 The welding diagram of the sealing nail 10 is obtained under the following parameters: T2 is set to 70%, the modulation frequency of the central laser beam and the ring laser beam is set to 0.1KHZ, and the welding speed is set to 60mm / s. As shown in the figure, the appearance is good. Through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding.

[0062] like Figure 7 As shown, the power P1 of the emitter of the ring laser corresponding to the central laser beam is set to 1000W, the power P2 of the emitter of the ring laser corresponding to the ring laser beam is set to 1300W, and the t of the central laser beam and the ring laser beam are... 21 The welding diagram of the sealing nail 10 is obtained under the following parameters: T2 is set to 50%, the modulation frequency of the central laser beam and the ring laser beam is set to 0.2kHz, and the welding speed is set to 80mm / s. As shown in the figure, the appearance is good. Through cross-section observation, the weld depth and weld width also meet the requirements of high-quality welding.

[0063] like Figure 8 As shown, the power P1 of the emitter of the ring laser corresponding to the central laser beam is set to 1300W, the power P2 of the emitter of the ring laser corresponding to the ring laser beam is set to 1800W, and the t of the central laser beam and the ring laser beam are... 21 The welding diagram of sealing nail 10 was obtained under the following conditions: T2 is set to 30%, the modulation frequency of the central laser beam and the ring laser beam is set to 0.5kHz, and the welding speed is set to 100mm / s. As shown in the figure, the appearance is good. Through cross-section observation, the weld depth and weld width also meet the requirements of high-quality welding.

[0064] Example 3, as Figures 9 to 12 As shown:

[0065] The central laser beam and the ring laser beam are set to constant value continuous output mode. The power P1 of the emitter of the ring spot laser corresponding to the central laser beam is set to 600-800W, and the power P2 of the emitter of the ring spot laser corresponding to the ring laser beam is set to 1000-1800W. The welding speed is set to 60mm / s-100mm / s.

[0066] In this embodiment, the central laser beam and the ring laser beam can be understood as always being in a stable and continuous output state. During the welding of the sealing nail 10 using this method, the keyhole remains open, resulting in a continuous and large laser energy input. By controlling the heat input, a weld with a good appearance and no defects can be obtained. Furthermore, the inventors of this application have found through experiments that when the power P1 of the emitting part of the ring laser corresponding to the central laser beam is set to 600-800W and the power P2 of the emitting part of the ring laser corresponding to the ring laser beam is set to 1000-1800W, a weld with a good appearance can be obtained, and the penetration depth and width also meet the welding requirements. Simultaneously, within this power range, the welding speed can reach 60mm / s to 100mm / s, achieving rapid welding.

[0067] like Figure 9 The diagram shows the laser energy waveforms of the central laser beam and the ring laser beam in Example 3, where a represents the laser energy waveform of the central laser beam and b represents the laser energy waveform of the ring laser beam. The initial energy boosting phases of the central and ring laser beams can be ignored.

[0068] like Figure 10 The figure shows the welding diagram of the sealing nail 10 under the following conditions: the power P1 of the emitter of the ring spot laser corresponding to the central laser beam is set to 800W, the power P2 of the emitter of the ring spot laser corresponding to the ring laser beam is set to 1800W, and the welding speed is set to 100mm / s. As shown in the figure, the appearance is good. Through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding. Moreover, the weld marks obtained by the welding mode of this embodiment are smoother and more aesthetically pleasing.

[0069] like Figure 11 The image shows a welding diagram of the sealing nail 10 obtained under the following conditions: the power P1 of the emitter of the ring spot laser corresponding to the central laser beam is set to 700W, the power P2 of the emitter of the ring spot laser corresponding to the ring laser beam is set to 1400W, and the welding speed is set to 100mm / s. As shown in the figure, the appearance is good. Through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding, and the weld marks are smooth and beautiful.

[0070] like Figure 12 The figure shows the welding diagram of the sealing nail 10 obtained under the following conditions: the power P1 of the emitter of the ring spot laser corresponding to the central laser beam is set to 600W, the power P2 of the emitter of the ring spot laser corresponding to the ring laser beam is set to 1000W, and the welding speed is set to 600mm / s. As shown in the figure, the appearance is good. Through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding, and the weld marks are smooth and beautiful.

[0071] Example 4, as Figures 13 to 16 As shown:

[0072] The central laser beam and the ring laser beam are set to pulse slow-descent mode, and the central laser beam and the ring laser beam are set to the same frequency and synchronously. The power P1 of the emitter of the ring spot laser corresponding to the central laser beam is set to 600~1400W, and the power P2 of the emitter of the ring spot laser corresponding to the ring laser beam is set to 1000~1800W.

[0073] In conventional pulsed welding, the keyhole opens and closes periodically with the periodic switching of the central laser beam, which is detrimental to the stability of the molten pool. However, the pulse descent mode of this embodiment allows for energy waveform settings to extend the laser's off-time, effectively slowing down the keyhole closure and providing preheating for the next pulse, thus improving molten pool stability and welding quality. The inventors' experiments have shown that setting the power P1 of the emitter of the ring-shaped laser corresponding to the central laser beam to 600–1400 W and the power P2 of the emitter of the ring-shaped laser corresponding to the ring-shaped laser beam to 1000–1800 W results in welds with good appearance and weld penetration and width that meet welding requirements.

[0074] Specifically, each cycle of the pulsed descent mode includes, in sequence, an energy-raising stage, a welding stage, a first energy-lowering stage, and a second energy-lowering stage. The duration of each cycle of the pulsed descent mode is set to T3, and the duration of the energy-raising stage is set to t. 31 The duration of the welding stage is set to t. 32 The duration of the first energy reduction stage is set to t. 33 The duration of the second energy reduction stage is set to t. 34 T3 = t 31 +t 32 +t 33 +t 34 0.2ms≤t 31 ≤0.5ms, 2ms≤t 32 ≤5ms, 0.1ms≤t 33 ≤1ms, 1ms≤t 34The pulse descent mode frequency is set to 20Hz~100Hz, and the welding speed is set to 10mm / s~60mm / s. The central laser beam and the ring laser beam are synchronized with each other during the energy boosting stage, welding stage, first energy reduction stage, and second energy reduction stage, respectively. During the welding stage, the power of the emitting part of the ring laser beam corresponding to the central laser beam is set to 80%~100% of P1, and the power of the emitting part of the ring laser beam corresponding to the ring laser beam is set to 80%~100% of P2. At the transition point between the first energy reduction stage and the second energy reduction stage, the power of the emitting part of the ring laser beam corresponding to the central laser beam is set to 40%~60% of P1, and the power of the emitting part of the ring laser beam corresponding to the ring laser beam is set to 40%~60% of P2.

[0075] In this embodiment, the duration of one cycle for the emission state of both the central laser beam and the ring laser beam is T3. Within one cycle, both the central laser beam and the ring laser beam synchronously and sequentially undergo the energy-raising stage, the welding stage, the first energy-reducing stage, and the second energy-reducing stage at the same frequency between 20Hz and 100Hz. During the energy-raising stage, the power of the emitting part of the ring laser corresponding to the central laser beam and the emitting part of the ring laser corresponding to the ring laser beam are within the range of T3. 11 Within a certain time period, the power is increased from zero to the power required for welding. That is, the emitting part of the ring spot laser corresponding to the central laser beam is increased from zero to 80% to 100% of P1, and the emitting part of the ring spot laser corresponding to the ring laser beam is increased from zero to 80% to 100% of P2.

[0076] During the welding stage, the emitting part of the ring-shaped laser corresponding to the central laser beam stably outputs t at 80% to 100% of the power of P1. 12 The emitter of the ring-spot laser corresponding to the ring laser beam outputs a stable power of t at 80% to 100% of P2. 12The duration is used to complete the welding process. In the first energy reduction stage, the power of the emitting part of the ring spot laser corresponding to the central laser beam gradually decreases from 80%–100% of the power of P1 to 40%–60% of the power of P1. At the same time, the power of the emitting part of the ring spot laser corresponding to the ring laser beam also gradually decreases from 80%–100% of the power of P2 to 40%–60% of the power of P2. In the second energy reduction stage, the power of the emitting part of the ring spot laser corresponding to the central laser beam is further gradually reduced from 40%–60% of the power of P1 to zero. At the same time, the power of the emitting part of the ring spot laser corresponding to the ring laser beam is further gradually reduced from 40%–60% of the power of P2 to zero. In this way, the emitting parts of the central laser beam and the ring spot laser corresponding to the ring laser beam complete one light emission cycle. Under the above conditions, the welding speed can reach 10 mm / s to 60 mm / s, enabling rapid welding.

[0077] The inventors of this application discovered through experiments that, within the aforementioned laser power range, setting the duration parameters of each stage to 0.2ms ≤ t 31 ≤0.5ms, 2ms≤t 32 ≤5ms, 0.1ms≤t 33 ≤1ms, 1ms≤t 34 Within a range of ≤2.5ms, the weld quality is better and the welding speed is faster.

[0078] like Figure 13 The diagram shows the laser energy waveforms of the central laser beam and the ring laser beam in Example 4, where a represents the laser energy waveform of the central laser beam and b represents the laser energy waveform of the ring laser beam.

[0079] like Figure 14 As shown, the power P1 of the emitter of the ring laser corresponding to the central laser beam is set to 600W, the power P2 of the emitter of the ring laser corresponding to the ring laser beam is set to 1800W, the power of the emitter of the ring laser corresponding to the central laser beam during the welding stage is set to 100% of P1, and the power of the emitter of the ring laser corresponding to the ring laser beam during the welding stage is set to 100% of P2. 31 Set to 0.5ms, t 32 Set to 5ms, t 33 Set to 1ms, t 34The welding diagram of the sealing nail 10 was obtained under the following parameters: 2.5ms pulse descent mode frequency set to 100Hz, power of the emitter of the ring laser corresponding to the center laser beam at the transition point between the first and second energy reduction stages set to 60% of P1, power of the emitter of the ring laser corresponding to the ring laser beam at the transition point between the first and second energy reduction stages set to 60% of P2, and welding speed set to 60mm / s. As shown in the figure, the appearance is good, and through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding.

[0080] like Figure 15 As shown, the power P1 of the emitter of the ring laser corresponding to the central laser beam is set to 800W, the power P2 of the emitter of the ring laser corresponding to the ring laser beam is set to 1400W, the power of the emitter of the ring laser corresponding to the central laser beam during the welding stage is set to 100% of P1, and the power of the emitter of the ring laser corresponding to the ring laser beam during the welding stage is set to 100% of P2. 31 Set to 0.5ms, t 32 Set to 4ms, t 33 Set to 0.5ms, t 34 The welding diagram of the sealing nail 10 was obtained under the following parameters: 2.5ms pulse descent mode frequency set to 100Hz, power of the emitter of the ring laser corresponding to the center laser beam at the transition point between the first and second energy reduction stages set to 60% of P1, power of the emitter of the ring laser corresponding to the ring laser beam at the transition point between the first and second energy reduction stages set to 60% of P2, and welding speed set to 60mm / s. As shown in the figure, the appearance is good, and through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding.

[0081] like Figure 16 As shown, the power P1 of the emitter of the ring laser corresponding to the central laser beam is set to 1000W, the power P2 of the emitter of the ring laser corresponding to the ring laser beam is set to 1800W, the power of the emitter of the ring laser corresponding to the central laser beam during the welding stage is set to 80% of P1, and the power of the emitter of the ring laser corresponding to the ring laser beam during the welding stage is set to 80% of P2. 31 Set to 0.2ms, t 32 Set to 2ms, t 33 Set to 0.5ms, t 34The welding diagram of the sealing nail 10 was obtained under the following parameters: 1ms pulse slow-descent mode frequency set to 100Hz, power of the ring spot laser corresponding to the center laser beam at the transition point between the first and second energy reduction stages set to 60% of P1, power of the ring spot laser corresponding to the ring laser beam at the transition point between the first and second energy reduction stages set to 60% of P2, and welding speed set to 60mm / s. As shown in the figure, the appearance is good, and through cross-section observation, the weld penetration and weld width also meet the requirements of high-quality welding.

[0082] Furthermore, in the above embodiments, the sealing nail 10 is made of aluminum, and the collimating focal length f1 of the welding head of the welding equipment is set to 100mm, and the focusing focal length f2 of the welding head of the welding equipment is set to 200mm. According to actual experiments, in the embodiments of this application, the collimating focal length f1 of the welding head is generally 100-150mm, and the focusing focal length f2 is generally 150-300mm. Among them, the collimating focal length f1 mainly uses three parameters: 100mm, 125mm, and 150mm, while the focusing focal length f2 mainly uses three parameters: 150mm, 250mm, and 300mm. After multiple tests and adjustments, when 1:2≤f1 / f2≤1:3, the welding quality and welding speed of the sealing nail 10 are improved more comprehensively. Of course, the above collimating focal length f1 and focusing focal length f2 can also be freely combined according to different welding needs.

[0083] According to the inventors’ multiple experiments, it was also found that when 1:1.5≤P1:P2≤1:2 in each of the above embodiments, it is also beneficial to improve the welding quality and welding speed of the sealing nail 10.

[0084] This application also provides a welding device capable of performing the laser welding method in any of the above embodiments.

[0085] Since the welding equipment of this application embodiment can perform the laser welding method in any of the above embodiments, the beneficial effects brought about by performing the laser welding method in any of the above embodiments will not be repeated here.

[0086] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A laser welding method applied to the welding of sealing studs in lithium-ion batteries, characterized in that, include: A welding device equipped with a ring spot laser is used to weld the emitted ring laser beam and the central laser beam along the preset welding trajectory of the sealing nail. The power P1 of the emitting part of the ring spot laser corresponding to the central laser beam is set to 600~1400W, and the power P2 of the emitting part of the ring spot laser corresponding to the ring laser beam is set to 800~1800W. The central laser beam is set to pulse slow-descent mode, and the ring laser beam is set to constant value continuous output mode. Each cycle of the pulse descent mode of the central laser beam sequentially includes an energy-raising stage, a welding stage, a first energy-reducing stage, and a second energy-reducing stage. The duration of each cycle of the pulse descent mode is set to T1, the duration of the energy-raising stage is set to t11, the duration of the welding stage is set to t12, the duration of the first energy-reducing stage is set to t13, and the duration of the second energy-reducing stage is set to t14. T1 = t11 + t12 + t13 + t14, 0.2ms ≤ t11 ≤ 0.5ms, 2ms ≤ t12 ≤ 5ms, 0.1ms ≤ t13 ≤ 1ms, and 1ms ≤ t14 ≤ 2.5ms. During the welding stage, the power of the emitting part of the ring-shaped laser corresponding to the central laser beam is set to 80%~100% of P1; At the transition point between the first energy reduction stage and the second energy reduction stage, the power of the emitting part of the ring spot laser corresponding to the central laser beam is set to 40%~60% of P1; The frequency of the pulse slow-descent mode is set to 20Hz~100Hz, and the welding speed is set to 40mm / s~60mm / s.

2. A laser welding method applied to the welding of sealing studs in lithium-ion batteries, characterized in that, include: Welding equipment equipped with a ring-shaped laser beam is used to weld the emitted ring laser beam and the central laser beam along the preset welding trajectory of the sealing nail; The central laser beam is set to pulse slow-descent mode, and the ring laser beam is set to constant value continuous output mode. The central laser beam and the ring laser beam are respectively set to modulation mode, the central laser beam and the ring laser beam are frequency synchronized, the power P1 of the emitting part of the ring spot laser corresponding to the central laser beam is set to 800~1300W, and the power P2 of the emitting part of the ring spot laser corresponding to the ring laser beam is set to 1000~1800W. The duration of each cycle of the modulation mode is set to T2. Each cycle of the modulation mode includes a peak phase and a trough phase. The peak phase corresponds to the phase in which the central laser beam and the ring laser beam are used for welding, and the trough phase corresponds to the phase in which the central laser beam and the ring laser beam stop welding. The duration of the peak phase is set to t21, the duration of the trough phase is set to t22, T2=t21+t22, 30%≤t21 / T2≤70%, the modulation frequency of the modulation mode is set to 0.1KHz~0.5KHz, and the welding speed is set to 60mm / s~100mm / s.

3. A laser welding method applied to the welding of sealing studs in lithium-ion batteries, characterized in that, include: Welding equipment equipped with a ring-shaped laser beam is used to weld the emitted ring laser beam and the central laser beam along the preset welding trajectory of the sealing nail; The central laser beam and the ring laser beam are respectively set to pulse slow-down mode. The central laser beam and the ring laser beam are set to the same frequency and synchronously. The power P1 of the emitting part of the ring spot laser corresponding to the central laser beam is set to 600~1400W, and the power P2 of the emitting part of the ring spot laser corresponding to the ring laser beam is set to 1000~1800W. Each cycle of the pulse slow-descent mode sequentially includes an energy-boosting phase, a welding phase, a first energy-degrading phase, and a second energy-degrading phase. The duration of each cycle of the pulse slow-descent mode is set to T3, the duration of the energy-boosting phase is set to t31, the duration of the welding phase is set to t32, the duration of the first energy-degrading phase is set to t33, and the duration of the second energy-degrading phase is set to t34. T3 = t31 + t32 + t33 + t34, 0.2ms ≤ t31 ≤ 0.5ms, 2ms ≤ t32 ≤ 5ms, 0.1ms ≤ t33 ≤ 1ms, and 1ms ≤ t34 ≤ 2.5ms. The frequency of the pulse slow-descent mode is set to 20Hz~100Hz, and the welding speed is set to 10mm / s~60mm / s. The central laser beam and the ring laser beam are synchronized with respect to the energy-boosting phase, the welding phase, the first energy-degrading phase, and the second energy-degrading phase, respectively. During the welding stage, the power of the emitting part of the ring spot laser corresponding to the central laser beam is set to 80%~100% of P1, and the power of the emitting part of the ring spot laser corresponding to the ring laser beam is set to 80%~100% of P2; At the transition point between the first energy reduction stage and the second energy reduction stage, the power of the emitting part of the ring spot laser corresponding to the central laser beam is set to 40%~60% of P1, and the power of the emitting part of the ring spot laser corresponding to the ring laser beam is set to 40%~60% of P2.

4. The laser welding method according to any one of claims 1-3, characterized in that, The sealing nail is made of aluminum. The collimation focal length f1 of the welding head of the welding equipment is set to 100mm~150mm, and the focusing focal length f2 of the welding head of the welding equipment is set to 200mm~300mm, with 1:2≤f1 / f2≤1:

3.

5. The laser welding method according to any one of claims 1-3, characterized in that, 1:1.5≤P1:P2≤1:

2.

6. A welding device, characterized in that, The welding equipment is capable of using the laser welding method as described in any one of claims 1-5.

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