Laser welding method and battery assembly method

Abstract

The application discloses a laser welding method and a battery assembling method, wherein the laser welding method comprises welding and cleaning and repairing a to-be-welded area, and the cleaning and repairing is to use a laser to scan the welded area after welding, so that particles and burrs in the welded area are fused. In view of the defects such as burst points and splashes that are prone to occur in the laser welding process, the application adds a cleaning and repairing step, that is, a low-power high-density high-speed laser is used to scan the welded area, so that the particles and burrs in the welded area are fused, and the particles and burrs existing on the surface are eliminated, so that the surface of the welded area is smoother and more delicate. After welding, the cleaning and repairing can fundamentally reduce the proportion of particle splashing and particle residue in the welded area without reducing the mechanical performance, the process flow is simple, and the quality of the battery is improved while the existing equipment is fully utilized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adapter plate and pole column welding, in particular to a laser welding method and a battery assembly method. BACKGROUND

[0002] Lithium battery is a power source for providing power source for power tools, which has the advantages of long service life, practical safety, large capacity, small size, light weight and is widely used in many fields. As a kind of new energy, lithium ion battery is widely used in our life, and aluminum shell battery becomes one of the most widely used battery models in lithium ion battery because of its safety advantage.

[0003] The existing aluminum shell battery needs to weld the connecting plate and the pole column during the manufacturing process. The current production process adopts laser welding to weld the adapter plate to the pole column of the top cover of the battery cell. After laser welding, the surface quality is poor, and there will be a protruding welding point and flying particles. The flying metal particles falling on the periphery and surface of the welding area are easy to fall into the inside of the battery cell, pierce the isolation film and cause the short circuit of the anode and cathode, which seriously threatens the safety and service life of the battery cell. Although the existing technology generally applies glue after welding to prevent flying objects from entering the inside of the shell and minimize the impact on the inside of the battery cell, there is still a risk of flying metal particles entering the inside of the battery cell.

[0004] Therefore, it is particularly necessary to fundamentally reduce the proportion of flying particles in order to reduce the cost of battery cell scrapping and the difficulty of manufacturing process. SUMMARY

[0005] The purpose of the present application is to provide a laser welding method and a battery assembly method.

[0006] The present application is implemented as follows:

[0007] In a first aspect, the present application provides a laser welding method, which comprises welding and cleaning and repairing the welding area. The cleaning and repairing is to melt the particles and burrs in the welded area by laser scanning the welded area after welding.

[0008] In an optional embodiment, the path of the cleaning and repairing step overlaps with the path of the welding step.

[0009] In an optional embodiment, the cleaning and repairing step satisfies at least one of the following ① or ②:

[0010] ① The cleaning and repairing is performed immediately after the welding step;

[0011] ② The cleaning and repairing is performed more than twice on the welded area after the welding step.

[0012] In an alternative embodiment, the power of the laser in the cleaning and repairing step is 1.3-1.7Kw, the scanning speed of the laser is 1300-1700mm / s, the defocusing amount is 1.7-2.3mm, and the protective gas flow rate is 7-9L / min.

[0013] In an alternative embodiment, the welding pattern in the cleaning and repairing step is double helix, the helix spacing is 0.085-0.115mm, the radius of one helix in the double helix is 0.5-0.7mm, and the radius of the other helix is 0.4-0.5mm.

[0014] In an alternative embodiment, the power of the laser in the cleaning and repairing step is 1.35Kw, the scanning speed of the laser is 1500mm / s, the defocusing amount is 2mm, the protective gas flow rate is 8L / min, the welding pattern is double helix, the helix spacing is 0.1mm, the radius of one helix in the double helix is 0.6mm, and the radius of the other helix is 0.48mm.

[0015] In an alternative embodiment, the welding power in the welding step is 1.7-2.0Kw, the welding speed is 1700-2000mm / s, the defocusing amount is 1.7-2.3mm, and the protective gas flow rate is 7-9L / min.

[0016] In an alternative embodiment, the welding pattern in the welding step is double helix, the helix spacing is 0.12-0.15mm, the radius of one helix in the double helix is 0.5-0.7mm, and the radius of the other helix is 0.4-0.5mm.

[0017] In an alternative embodiment, the welding power in the welding step is 1.8Kw, the welding speed is 1800mm / s, the defocusing amount is 2mm, the protective gas flow rate is 8L / min, the welding pattern is double helix, the helix spacing is 0.13mm, the radius of one helix in the double helix is 0.6mm, and the radius of the other helix is 0.48mm.

[0018] In a second aspect, the application provides a battery assembling method, which comprises welding a tab to a pole of a top cover of a battery cell by using the laser welding method according to any one of the preceding embodiments.

[0019] The application has the following advantages:

[0020] In view of the defects such as burst point and splash prone to occur in the laser welding process, the cleaning and repairing step is added, that is, the low-power high-density high-speed laser is used to scan the welded area, so that the particles and burrs in the welded area are fused, and the particles and burrs existing on the surface are eliminated, so that the surface of the welded area is smoother and more delicate, and after welding, the cleaning and repairing is carried out, which can fundamentally reduce the proportion of particle splash and particle residue in the welded area without reducing the mechanical performance, the process flow is simple, and the quality of the battery is improved while the existing equipment is fully utilized. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0022] Figure 1 It is a welding effect diagram of the weld in Example 1.

[0023] Figure 2 It is a metallographic diagram of the weld in Example 1.

[0024] Figure 3 It is a welding effect diagram of the weld in Comparative Example 1.

[0025] Figure 4 It is a metallographic diagram of the weld in Comparative Example 1. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely. In the embodiments, the specific conditions not noted are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments not noted by the manufacturer are all conventional products that can be purchased in the market.

[0027] The embodiment of the present application provides a laser welding method, which comprises welding and cleaning and repairing a to-be-welded area, wherein the cleaning and repairing is to fuse particles and burrs in the welded area by using laser to scan the welded area after welding.

[0028] In view of the defects such as burst point and splash prone to occur in the laser welding process, the cleaning and repairing step is added, that is, a low-power high-density high-speed laser is used to scan the to-be-welded area, so that the particles and burrs in the welded area are fused, the particles and burrs existing on the surface are eliminated, and the surface of the welded area is made more smooth and delicate through high-speed secondary laser cladding, so that the proportion of particle splash and particle residue in the welded area can be fundamentally reduced without reducing the mechanical properties under the premise of simple process flow, and the quality of the battery is improved while the existing equipment is fully utilized.

[0029] In some embodiments of the present application, the path of the cleaning and repairing step overlaps with the path of the welding step. For example, the welding path is from point A to point B, and the path of the cleaning and repairing step is also between point A and point B. Specifically, the path of the cleaning and repairing step can be from point A to point B, or from point B to point A. Considering the efficiency and convenience of welding, the preferred path of the cleaning and repairing step is from point B to point A.

[0030] In some embodiments of the present application, the cleaning and repairing is performed immediately after the welding step, which can effectively utilize the residual heat of the welded area, reduce the energy consumption of the cleaning and repairing step, increase the depth of the molten pool to a certain extent, and facilitate the operation of the welding and cleaning and repairing steps.

[0031] In some embodiments of the present application, the welded area is cleaned and repaired twice or more times after the welding step.

[0032] Specifically, the cleaning and repairing can be performed twice, three times or even more times, and a person skilled in the art can determine the actual situation of the to-be-welded area. When the to-be-welded area has many particles and burrs, and the particles and burrs are not fused after one cleaning and repairing, the number of cleaning and repairing can be increased until the particles and burrs on the surface of the to-be-welded area are completely eliminated or the elimination ratio meets the requirements.

[0033] In some embodiments of the present application, the power of the laser in the cleaning and repairing step is 1.3-1.7Kw, the scanning speed of the laser is 1300-1700mm / s, the defocusing amount is 1.7-2.3mm, the protective gas flow rate is 7-9L / min, the welding pattern is double helical lines, the helical pitch is 0.085-0.115mm, the radius of one helical line in the double helical lines is 0.5-0.7mm, and the radius of the other helical line is 0.4-0.5mm.

[0034] In some preferred embodiments, the laser in the cleaning and repairing step has a power of 1.35Kw, the laser scanning speed is 1500mm / s, the defocusing amount is 2mm, the protective gas flow rate is 8L / min, the welding pattern is double helix, the helix spacing is 0.1mm, the radius of one helix in the double helix is 0.6mm, and the radius of the other helix is 0.48mm.

[0035] In some embodiments of the application, the welding power in the welding step is 1.7-2.0Kw, the welding speed is 1700-2000mm / s, the defocusing amount is 1.7-2.3mm, the protective gas flow rate is 7-9L / min, the welding pattern is double helix, the helix spacing is 0.12-0.15mm, the radius of one helix in the double helix is 0.5-0.7mm, and the radius of the other helix is 0.4-0.5mm.

[0036] In some preferred embodiments, the welding power in the welding step is 1.8Kw, the welding speed is 1800mm / s, the defocusing amount is 2mm, the protective gas flow rate is 8L / min, the welding pattern is double helix, the helix spacing is 0.13mm, the radius of one helix in the double helix is 0.6mm, and the radius of the other helix is 0.48mm.

[0037] The embodiments of the application can effectively reduce the welding power and improve the welding speed under the premise of ensuring the mechanical properties by adding the cleaning and repairing step. In the cleaning and repairing step, a smaller helix spacing is used to fuse the particles and burrs, and a double helix is used as the welding pattern to increase the coverage area.

[0038] It should be noted that the laser welding method in the embodiments can be applied to other similar situations although it is obtained in the special background of welding the adapter piece and the pole.

[0039] Another embodiment of the application provides a battery assembly method, which comprises welding the adapter piece to the pole of the top cover of the battery cell by using the laser welding method in any one of the preceding embodiments.

[0040] The material of the adapter piece in the embodiments can be aluminum, copper or alloy, etc. The specific material of the adapter piece can be selected by the person skilled in the art according to the material of the pole and the tab, and generally the material of the adapter piece is the same as that of the tab and the pole. The laser welding method in the application is applicable to these materials and can meet the requirements of overcurrent, strength and low spatter of the battery.

[0041] The features and performances of the application are further described in detail below in combination with the embodiments.

[0042] Embodiment 1

[0043] The embodiment provides a laser welding method, comprising:

[0044] Preparation of the first component and the second component to be welded, the first component and the second component are both aluminum alloy materials, and a to-be-welded region is determined;

[0045] Adjusting equipment parameters, welding is performed, and the equipment parameters are as follows: a welding power is 1.8Kw, a welding speed is 1800mm / s, a defocusing amount is 2mm, a protective gas flow rate is 8L / min, a welding pattern is double helix lines, a helix interval is 0.13mm, a radius of helix A in the double helix lines is 0.6mm, and a radius of helix B is 0.48mm;

[0046] Adjusting equipment parameters, cleaning and repairing are performed, and the equipment parameters are as follows: a welding power is 1.5Kw, a welding speed is 1500mm / s, a defocusing amount is 2mm, a protective gas flow rate is 8L / min, a welding pattern is double helix lines, a helix interval is 0.1mm, a radius of helix A in the double helix lines is 0.6mm, and a radius of helix B is 0.48mm, and the appearance after cleaning and repairing and the metallographic test result are shown in Figure 1 and Figure 2 .

[0047] Embodiment 2

[0048] The embodiment provides a laser welding method, comprising:

[0049] Preparation of the first component and the second component to be welded, the first component and the second component are both aluminum alloy materials, and a to-be-welded region is determined;

[0050] Adjusting equipment parameters, welding is performed, and the equipment parameters are as follows: a welding power is 1.5Kw, a welding speed is 1500mm / s, a defocusing amount is 1.7mm, a protective gas flow rate is 7L / min, a welding pattern is double helix lines, a helix interval is 0.12mm, a radius of helix A in the double helix lines is 0.5mm, and a radius of helix B is 0.4mm;

[0051] Adjusting equipment parameters, cleaning and repairing are performed, and the equipment parameters are as follows: a welding power is 1.3Kw, a welding speed is 1300mm / s, a defocusing amount is 1.7mm, a protective gas flow rate is 7L / min, a welding pattern is double helix lines, a helix interval is 0.085mm, a radius of helix A in the double helix lines is 0.5mm, and a radius of helix B is 0.4mm.

[0052] Embodiment 3

[0053] The embodiment provides a laser welding method, comprising:

[0054] Preparation of the first component and the second component to be welded, the first component and the second component are both aluminum alloy materials, and a to-be-welded region is determined;

[0055] Adjusting the equipment parameters, welding is carried out, and the equipment parameters are as follows: the welding power is 2.0Kw, the welding speed is 2000mm / s, the defocusing amount is 2.3mm, the protective gas flow rate is 9L / min, the welding pattern is double helix, the helix interval is 0.15mm, the radius of helix A in the double helix is 0.7mm, and the radius of helix B is 0.5mm.

[0056] Adjusting the equipment parameters, welding is carried out, and the equipment parameters are as follows: the welding power is 2.0Kw, the welding speed is 2000mm / s, the defocusing amount is 2.3mm, the protective gas flow rate is 9L / min, the welding pattern is double helix, the helix interval is 0.15mm, the radius of helix A in the double helix is 0.7mm, and the radius of helix B is 0.5mm.

[0057] Example 4

[0058] The embodiment provides a laser welding method, comprising:

[0059] Preparation of a first component and a second component to be welded, the first component and the second component are both aluminum alloy, and a to-be-welded area is determined;

[0060] Adjusting the equipment parameters, welding is carried out, and the equipment parameters are as follows: the welding power is 2.0Kw, the welding speed is 2000mm / s, the defocusing amount is 2mm, the protective gas flow rate is 8L / min, the welding pattern is double helix, the helix interval is 0.15mm, the radius of helix A in the double helix is 0.6mm, and the radius of helix B is 0.48mm.

[0061] Adjusting the equipment parameters, welding is carried out, and the equipment parameters are as follows: the welding power is 2.0Kw, the welding speed is 2000mm / s, the defocusing amount is 2.3mm, the protective gas flow rate is 9L / min, the welding pattern is double helix, the helix interval is 0.15mm, the radius of helix A in the double helix is 0.7mm, and the radius of helix B is 0.5mm.

[0062] In Examples 1-4, the cleaning repair and welding steps are compared by high-speed camera shooting playback, no splashing after cleaning repair, and the roughness of the cleaning repair area is reduced, and the surface is obviously smoother and more delicate. In the repair process, the splashing residues and surface burr particles generated in the first welding are re-melted, and the effective depth and width of the molten pool can be increased.

[0063] Comparative Example 1

[0064] The embodiment provides a laser welding method, comprising:

[0065] Preparation of the first component and the second component to be welded, both of which are made of aluminum alloy, and determination of the welding area;

[0066] Adjusting the equipment parameters, the welding power is 1.92Kw, the welding speed is 800mm / s, the defocusing amount is 2mm, the protective gas flow rate is 8L / min, the welding pattern is double helix, the helix interval is 0.2mm, the radius of helix A in the double helix is 0.7mm, the radius of helix B is 0.7mm, welding is carried out, and the weld appearance and the metallographic test results are shown in Figure 3 and Figure 4 .

[0067] In the present comparative example, the visual welding area is relatively rough and not smooth.

[0068] The parameters used in each example and comparative example and the corresponding molten pool depth are shown in the following table

[0069]

[0070]

[0071] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A laser welding method of welding a lug to a pole, characterized by, The welding method comprises welding and cleaning repair to the welding area, and the cleaning repair is to melt the particles and burrs in the welded area by laser scanning the welded area after welding; In the welding step, the welding power is 1.7-2.0Kw, the welding speed is 1700-2000mm / s, the defocusing amount is 1.7-2.3mm, and the protective gas flow rate is 7-9L / min; in the welding step, the welding pattern is double helix, the helix spacing is 0.12-0.15mm, the radius of one helix in the double helix is 0.5-0.7mm, and the radius of the other helix is 0.4-0.5mm; In the cleaning repair step, the power of the laser is 1.3-1.7Kw, the laser scanning speed is 1300-1700mm / s, the defocusing amount is 1.7-2.3mm, and the protective gas flow rate is 7-9L / min; in the cleaning repair step, the welding pattern is double helix, the helix spacing is 0.085-0.115mm, the radius of one helix in the double helix is 0.5-0.7mm, and the radius of the other helix is 0.4-0.5mm; The cleaning repair step is performed immediately after the welding step, and the path of the cleaning repair step overlaps with the path of the welding step.

2. The laser welding method of welding a tab to a post of claim 1, wherein, After the welding step, the welded area is cleaned and repaired more than twice.

3. The laser welding method of welding a tab to a post of claim 1, wherein, In the cleaning repair step, the power of the laser is 1.35Kw, the laser scanning speed is 1500mm / s, the defocusing amount is 2mm, the protective gas flow rate is 8L / min, the welding pattern is double helix, the helix spacing is 0.1mm, the radius of one helix in the double helix is 0.6mm, and the radius of the other helix is 0.48mm.

4. The laser welding method of welding a tab to a post of claim 1, wherein, In the welding step, the welding power is 1.8Kw, the welding speed is 1800mm / s, the defocusing amount is 2mm, the protective gas flow rate is 8L / min, the welding pattern is double helix, the helix spacing is 0.13mm, the radius of one helix in the double helix is 0.6mm, and the radius of the other helix is 0.48mm.

5. A method of assembling a battery, characterized by The laser welding method is used to weld the adapter piece to the pole of the top cover of the battery cell.

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