Welding method and battery module

Abstract

The invention belongs to the technical field of battery module processing, and particularly relates to a welding method which comprises the steps that before welding, a protruding part on a partition plate is inserted into a mounting hole in an end plate, the mounting hole and the protruding part are of a rectangular structure, a long-strip-shaped annular gap is formed between the protruding part and the mounting hole, and the protruding part is inserted into the mounting hole in the end plate; the long-strip-shaped annular gap comprises a first long gap and a second long gap which are oppositely arranged. The first long seam and the second long seam extend along a first direction; during welding, firstly, the first long seam is welded in a laser welding mode, and a first welding seam is formed; then the second long seam is welded in a laser welding mode, a second welding seam is formed, and in the first direction, the welding end point of the second welding seam exceeds the end, close to the welding end point of the second welding seam, of the first welding seam; according to the welding method and the battery module, cracks at the tail end of the welding seam can be effectively reduced by optimizing the welding seam track and the welding sequence.

Description

Technical Field

[0001] The present application belongs to the technical field of battery module processing, and in particular, relates to a welding method and a battery module. Background Art

[0002] A battery module is a unit with a certain voltage and capacity formed by connecting multiple cells in series or in parallel. It is designed to provide higher voltage and energy storage capacity to meet the power requirements of specific applications. A battery module is usually composed of several cells, connectors, a battery management system (BMS), a shell, and other auxiliary structural parts (such as end plates, partitions, fasteners, etc.). Among them, the cell is the core part of the module and is responsible for storing electrical energy; the connector is used for electrical connection between cells; the BMS is responsible for monitoring and managing the charging and discharging process of the battery to ensure the safety and stable performance of the battery; the shell and other auxiliary structural parts provide physical support and isolation to protect the cell and BMS from the external environment. Battery modules are widely used in electric vehicles, hybrid vehicles, energy storage systems, and other applications that require large capacity and high voltage. In the field of electric vehicles, the battery module is one of the core components of the power battery system, providing continuous power support for the vehicle.

[0003] At present, in order to adapt to the development direction of lightweight and high endurance in the new energy vehicle industry, improving the space utilization of battery packs and reducing the number of product parts have become the key. This strategy not only helps to reduce the overall weight of the vehicle and improve energy efficiency, but also reduces production costs and simplifies the production process. Optimizing the design of the battery pack to achieve a more compact and efficient layout is an important path to promote the technological progress of new energy vehicles. To this end, battery modules are developing in the direction of high integration. With the demand for high integration of battery modules, multi-row modules have emerged. The multi-row module includes multiple battery cell groups, and partitions are arranged between adjacent battery cell groups to play an effective support and isolation role. At the same time, in order to ensure the firmness of the overall structure, the partition must also be closely connected with the end plate to form an integrated and stable structure to meet the application requirements of highly integrated battery modules. The common connection structure between the end plate and the partition is: the end plate is provided with a mounting hole, the partition is provided with a protrusion, the protrusion is inserted into the mounting hole on the end plate, and then the protrusion and the mounting hole are fixedly connected by welding. However, this design of slotting the end plate, inserting the middle partition and fixing it by welding faces the risk of weld cracks in actual applications. In order to avoid weld cracks in the weld, wire welding is usually used for connection. However, the welding speed of wire welding is slow, especially when manual wire filling is required. The welding efficiency is relatively low, and it is difficult to achieve fully automated production; in addition, the welding accuracy of wire welding may be affected by human operating factors, such as wire filling speed and angle, and it is difficult to achieve the high accuracy of laser welding. If laser welding is used, the following problems will arise: Since the slot size of the end plate is slightly larger than the thickness of the middle partition, there is a gap after assembly. During the welding process, the gap needs to be filled. Using conventional laser welding methods, welding cracks are likely to occur at the tail of the weld, which not only affects the strength of the structure, but may also reduce the overall performance and service life of the battery module.

[0004] In view of this, this application is filed. Summary of the invention

[0005] The purpose of this application is to provide a welding method and a battery module to address the above-mentioned technical problems, so as to achieve a stable connection between the partition and the end plate, reduce the risk of weld cracks during application, and improve the structural strength, overall performance and service life of the battery module.

[0006] In view of this, the present application provides a welding method, wherein a first welding member includes a protrusion, and a second welding member includes a mounting hole, and the protrusion matches the mounting hole. The welding method includes:

[0007] Before welding, the protrusion is inserted into the mounting hole, wherein the mounting hole and the protrusion are long strip structures; a long strip annular gap is formed between the protrusion and the mounting hole, and the long strip annular gap includes a first long gap and a second long gap that are arranged oppositely; and the first long gap and the second long gap extend along a first direction;

[0008] During welding, the first long seam is firstly welded by laser welding to form a first weld; then the second long seam is welded by laser welding to form a second weld, wherein, along the first direction, the welding end point of the second weld exceeds the end of the first weld close to the welding end point of the second weld.

[0009] Furthermore, the welding directions of the first long seam and the second long seam during laser welding are consistent, the welding starting point of the first weld is the first starting end, and the welding end point is the first end; the welding starting point of the second weld is the second starting end, and the welding end point is the second end;

[0010] Along the first direction, there is a first distance between the first starting end and the second starting end, and there is a second distance between the first end and the second end. The length of the first distance is recorded as N, and the length of the second distance is recorded as W. N is greater than or equal to zero, and W is greater than zero.

[0011] Furthermore, along the opposite direction of laser welding, the length that the first starting end exceeds the second starting end is the first distance; along the laser welding direction, the length that the second end exceeds the first end is the second distance, and the first distance is equal to the second distance.

[0012] Furthermore, the value range of W is: w≥3mm.

[0013] Furthermore, the height of the end plate is smaller than the height of the battery cell group, and the first direction extends in the vertical direction; when the first distance is smaller than the second distance, the distance between the second starting end and the middle height of the battery cell group is smaller than the distance between the second end and the middle height of the battery cell group.

[0014] Furthermore, the welding process parameters of the first welding are consistent with those of the second welding.

[0015] Furthermore, the welding process parameters of the laser welding are: welding power of 2000W to 5000W, welding speed of 60mm / s to 120mm / s, amplitude of 1mm to 4mm, and frequency of 100HZ to 220HZ.

[0016] Furthermore, the length of the protrusion is set so that after the protrusion is inserted into the mounting hole, the length of the protrusion protruding from the mounting hole is 0.3 mm to 10 mm.

[0017] Furthermore, the thickness of the partition is 1 mm to 4 mm, and during welding, the center distance between the laser tracks of the first weld and the second weld is equal to the thickness of the partition.

[0018] A battery module comprises a partition and an end plate, wherein the partition is a first welding part and the end plate is a second welding part, and the partition and the end plate are assembled and welded together by the above method.

[0019] The beneficial effects of this application are:

[0020] The welding method and battery module described in the present application weld the two seams between the partition and the end plate respectively. During the welding process, the first long seam is first welded by laser welding to form a first weld; then the second long seam is welded by laser welding to form a second weld. Since the welding end point of the second weld exceeds the end of the first weld close to the welding end point of the second weld, it is beneficial for the liquid molten material of the second weld to reflux and fill the cracks in the second weld caused by the stress release of the first weld, which can eliminate the influence of the stress release of the first weld on the welding of the second weld and avoid the formation of cracks in the second weld; and the second weld that is welded later is not easy to affect the first weld that is welded first, and is not easy to cause cracks in the first weld.

[0021] In summary, the welding method and battery module described in the present application can effectively reduce the occurrence of cracks at the end of the weld by optimizing the weld trajectory and welding sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a front view of the assembly structure of the partition and the end plate described in the present application;

[0023] Figure 2 It is a top view of the assembly structure of the partition and the end plate described in the present application;

[0024] Figure 3 It is a three-dimensional schematic diagram of the assembly structure of the partition and the end plate described in the present application;

[0025] Figure 4 It is a three-dimensional structural schematic diagram of the partition described in this application;

[0026] Figure 5 is a schematic diagram of the top view of the end plate described in the present application;

[0027] Figure 6 is a schematic diagram of the three-dimensional structure of the mounting hole in the end plate described in the present application;

[0028] Figure 7 It is a top view of the assembly structure of the mounting hole in the end plate and the raised portion in the partition plate described in the present application;

[0029] Figure 8 It is a front view of the assembly structure of the mounting hole in the end plate and the protrusion in the partition plate described in the present application;

[0030] Fig. 9 is a schematic diagram of the structure of the weld between the mounting hole in the end plate and the raised portion in the partition plate described in the present application;

[0031] The symbols in the figure are:

[0032] 1. End plate; 101. Mounting hole; 2. Partition plate; 201. Raised portion; 3. First weld; 301. First starting end; 302. First end; 4. Second weld; 401. Second starting end; 402. Second end. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0034] In the description of the present application, it should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. For ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0035] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0036] It should be noted that, in the description of the present application, the orientation or positional relationship indicated by terms such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise stated, these orientation words 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, and therefore cannot be understood as limiting the scope of protection of the present application; the orientation words "inside and outside" refer to the inside and outside relative to the contour of each component itself.

[0037] It should be noted that, in the present application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0038] like Figures 1 to 9As shown, a welding method, the first welding part includes a protrusion, the second welding part includes a mounting hole, the protrusion matches the mounting hole, the application takes the first welding part as a partition in a battery module and the second welding part as an end plate in a battery module as an example for illustrative description, but is not limited to this. For example, as long as it involves two welding parts that are matched to form a long strip structure, it can be applied. Specifically, the battery module includes a plurality of battery cell groups, and the partition 2 is arranged between adjacent battery cell groups. The partition 2 matches the mounting hole 101 on the end plate 1 through the protrusion 201 at the end. The welding method includes:

[0039] Before welding, the protrusion 201 on the partition 2 is inserted into the mounting hole 101 on the end plate 1, wherein the mounting hole 101 and the protrusion 201 are long strip structures; a long strip annular gap is formed between the protrusion and the mounting hole, and the long strip annular gap includes a first long gap and a second long gap that are oppositely arranged; and the first long gap and the second long gap extend along a first direction;

[0040] During welding, the first long seam is firstly welded by laser welding to form a first weld 3; then the second long seam is welded by laser welding to form a second weld 4, wherein, along the first direction, the welding end point of the second weld 4 exceeds the end of the first weld 3 close to the welding end point of the second weld 4.

[0041] As some examples of the present application, the mounting hole 101 and the protrusion 201 are rectangular strip structures, so that a rectangular long strip annular gap can be formed between the mounting hole 101 and the protrusion 201. In the long strip annular gap, a pair of gaps with a longer length are selected and recorded as the first long gap and the second long gap. In this case, the first direction is the extension direction of the first long gap and the second long gap.

[0042] In the welding process described in the present application, two welds of different lengths need to be welded separately, that is, the first weld 3 and the second weld 4 are formed by two weldings. Only one weld is welded each time. This method of welding in batches requires less filling of liquid molten material during the welding process, has a better filling effect, is more conducive to weld formation, and is less likely to cause welding cracks.

[0043] Preferably, the length of the first weld 3 is smaller than the second weld 4. During the welding process, the short weld is welded first, and then the long weld is welded; that is, during welding, the first weld 3 is formed by the first welding, and then the second weld 4 is formed by the second welding. This method of welding the short weld first and then the long weld during the welding process is mainly based on the control principle of welding stress and deformation, weakens the problem of mutual interference between the ends of the two welds, reduces the generation of welding cracks, and eliminates the influence of the stress release of the first weld on the welding of the second weld. The specific reasons are as follows:

[0044] (1) During welding, the cooling and solidification process of the weld will generate welding stress and deformation. If the long weld is welded first and then the adjacent short weld, the welding stress and deformation of the long weld may limit the free contraction of the short weld, causing the short weld to be subjected to additional tensile stress during the welding process, increasing the risk of welding cracks. However, if the short weld is welded first, the short weld is allowed to contract freely after welding, reducing the mutual interference with the subsequent long weld welding process.

[0045] (2) By welding the short weld first, the welding stress can be evenly released in a smaller range, avoiding the crack problem caused by stress concentration when welding long welds;

[0046] (3) Crystallization cracks are a common type of cracks in the welding process. They mainly occur during the crystallization process of the weld. Welding the short weld first and then the long weld can help reduce the shrinkage stress during the crystallization process at the end of the long weld and avoid the occurrence of welding cracks.

[0047] (4) Welding residual stress is one of the important factors leading to welding cracks. The order of welding short welds first and then long welds can gradually release and adjust the welding residual stress during the welding process, avoiding the crack problem caused by excessive residual stress;

[0048] (5) During the welding process, the welding stress of the weld will be transmitted along the weld direction. If the long weld is welded first, its welding stress may affect the short weld welded later, causing the short weld to be subjected to additional tensile stress or compressive stress during welding. Welding the short weld first avoids this situation, allowing the welding stress to be independently transmitted and released within the range of each weld.

[0049] (6) Through a reasonable welding sequence arrangement, the stress distribution during the welding process can be made more uniform and reasonable, thereby improving the overall quality of the welded joint, which not only helps to reduce the risk of welding cracks, but also helps to improve the mechanical properties and durability of the welded joint.

[0050] In summary, in the present application, the welding method of welding the short seam first and then the long seam has significant advantages in weakening the mutual interference of the weld ends, reducing the generation of welding cracks and eliminating the influence of welding stress release. It can weaken the mutual interference of the two weld ends and reduce the generation of welding cracks. At the same time, the different welding trajectories of the two welds can eliminate the influence of the welding stress release of the first weld on the welding of the second weld, and avoid the generation of welding cracks at the end of the weld.

[0051] As some examples of the present application, during the welding process, there are no requirements for the starting and ending ends of the first weld 3 and the second weld 4. For example, for the first weld 3 and the second weld 4 in the vertical direction, during welding, the first weld 3 and the second weld 4 can be formed by welding from top to bottom or from bottom to top.

[0052] In addition, there is no requirement for the relative welding direction of the first weld 3 and the second weld 4. For example, the welding directions of the first weld 3 and the second weld 4 can both be from top to bottom, or one of them can be from top to bottom and the other from bottom to top.

[0053] Preferably, the welding directions of the first long seam and the second long seam during laser welding are consistent, that is, the welding directions of the first weld 3 and the second weld 4 are consistent.

[0054] Furthermore, one end of the first weld 3 is recorded as a first starting end 301, and the other end is recorded as a first ending end 302. During welding, the first starting end 301 is used as a welding starting point and the first ending end 302 is used as a welding ending point to form the first weld 3.

[0055] Similarly, one end of the second weld 4 is recorded as a second starting end 401, and the other end is recorded as a second ending end 402. During welding, the second weld 4 is formed by welding with the second starting end 401 as the welding starting point and the second ending end 402 as the welding ending point.

[0056] Furthermore, along the first direction, there is a first distance between the first starting end 301 and the second starting end 401, and there is a second distance between the first end 302 and the second end 402. The length of the first distance is denoted as N, and the length of the second distance is denoted as W. N is greater than or equal to zero, and W is greater than zero.

[0057] Preferably, the value range of W is: w≥3mm.

[0058] More preferably, the value range of W is: 16mm>w≥3mm.

[0059] As some examples of this application, Fig. 9As shown, along the first direction, the first starting end 301 and the second starting end 401 are aligned. At this time, since the lengths of the first weld 3 and the second weld 4 are different, there is a certain distance between the first end 302 and the second end 402. The length of the distance is recorded as W, and W is equal to the length difference between the first weld 3 and the second weld 4.

[0060] It should be noted that the embodiment of the present application does not impose any specific restriction on the positional relationship between the first weld 3 and the second weld 4, as long as the welding end point of the second weld 4 exceeds the end of the first weld close to the welding end point of the second weld.

[0061] Exemplarily, the first starting end 301 is used as the welding starting point and the first end 302 is used as the welding end point to form the first weld 3, and the second starting end 401 is used as the welding starting point and the second end 402 is used as the welding end point to form the second weld 4, and the welding starting point is used as the first end in the laser welding direction and the welding end point is used as the second end in the welding direction. Compared with the second starting end 401, the first starting end 301 can be closer to or farther from the first end in the laser welding direction, or aligned with the second starting end 401 of the second weld 4; but compared with the second end 402, the first end 302 of the first weld 3 is farther from the second end in the laser welding direction. That is, with the second starting end 401 as the reference point, along the laser welding direction, the first starting end 301 can be before or after the reference point or be consistent with the reference point position, and with the second end 402 as the reference point, along the laser welding direction, the first end 302 does not reach the second end 402.

[0062] Preferably, taking the second end 402 of the second weld 4 as its welding end point as an example, along the laser welding direction, the first starting end 301 of the first weld 3 is before or aligned with the second starting end 401 of the second weld 4.

[0063] Preferably, along the opposite direction of laser welding, the length by which the first starting end 301 exceeds the second starting end 401 is the first distance N; along the direction of laser welding, the length by which the second end 402 exceeds the first end 302 is the second distance W, and the first distance N is equal to the second distance W.

[0064] For the sake of convenience of explanation, along the length direction of the protrusion 201 (i.e., the length direction of the mounting hole 101, such as the vertical direction), the end of the first weld 3 close to the first end (such as the lower end) of the protrusion 201 is the first starting end 301, and the end close to the second end (such as the upper end) of the protrusion 201 is the first terminal end 302; the end of the second weld 4 close to the first end (such as the lower end) of the protrusion 201 is the second starting end 401, and the end close to the second end (such as the upper end) of the protrusion 201 is the second terminal end 402.

[0065] In one embodiment of the present application, the distance between the first starting end 301 and the first end of the protrusion 201 is greater than the distance between the second starting end 401 and the first end of the protrusion 201, and the distance between the first end 302 and the second end of the protrusion 201 is greater than the distance between the second end and the second end of the protrusion 201, that is, both ends of the first weld 3 are shorter than the second weld 4.

[0066] Furthermore, the height of the end plate 1 is smaller than the height of the battery cell group, and the first direction extends along the vertical direction; when the first distance is smaller than the second distance, the distance between the second starting end 401 and the middle height of the battery cell group is smaller than the distance between the second end 402 and the middle height of the battery cell group.

[0067] Furthermore, the first starting end 301 and the second starting end 401 are located at one end of the end plate 1 close to the bottom of the battery cell, and the first terminal end 302 and the second terminal end 402 are located at one end of the end plate 1 away from the bottom of the battery cell. In this way, when the end plate 1 is installed, there is a certain distance from the bottom of the battery cell, and the battery cell usually expands from the middle. This arrangement can reduce the impact of the asymmetric weld.

[0068] In another embodiment of the present application, the distance between the first starting end 301 and the first end of the protrusion 201 is smaller than the distance between the second starting end 401 and the first end of the protrusion 201, the distance between the first end 302 and the second end of the protrusion 201 is larger than the distance between the second end and the second end of the protrusion 201, and the length of the first weld 3 is consistent with that of the second weld 4. At this time, the distance between the first starting end 301 and the middle height of the battery cell group is equal to the distance between the second end 402 and the middle height of the battery cell group.

[0069] In another embodiment of the present application, the distance between the first starting end 301 and the first end of the protrusion 201 is equal to the distance between the second starting end 401 and the first end of the protrusion 201, and the distance between the first end 302 and the second end of the protrusion 201 is greater than the distance between the second end and the second end of the protrusion 201. At this time, the distance between the second starting end 401 and the middle height of the battery cell group is greater than the distance between the second end 402 and the middle height of the battery cell group.

[0070] Furthermore, the length of the protrusion 201 is set so that after the protrusion 201 is inserted into the mounting hole 101, the protrusion 201 can protrude from the mounting hole 101 by a certain length, such as 0.3 to 10 mm. In this structure where the partition 2 slightly protrudes from the end plate 1, the material of the protruding part melted during welding can be used to fill the gap between the two, which is beneficial to reduce the probability of shrinkage cracks in the weld.

[0071] Preferably, the length of the protrusion 201 is set so that after the protrusion 201 is inserted into the mounting hole 101, the length of the protrusion 201 protruding from the mounting hole 101 is about 0.5 mm.

[0072] Furthermore, the thickness of the partition is 1 mm to 4 mm. During welding, the center distance between the laser tracks of the first weld 3 and the second weld 4 is approximately equal to the thickness of the partition 2 .

[0073] Furthermore, the welding process parameters of the first welding and the second welding are consistent, so that the two welding processes are relatively close, and there is no need to additionally adjust the parameters of the welding device, which is easy to operate.

[0074] Preferably, the thickness of the partition is 1 mm to 4 mm, and the process parameters of the laser welding are: welding power is 2000 to 5000 W, welding speed is 60 to 120 mm / s, amplitude is 1 to 4 mm, and frequency is 100 to 220 Hz.

[0075] More preferably, the thickness of the partition 2 is 2 mm, and the process parameters of laser welding are: welding power is 3200 W, welding speed is 80 mm / s, amplitude is 2 mm, and frequency is 150 Hz.

[0076] As some examples of the present application, the partition 2 and the end plate 1 are metal plates such as aluminum, copper-titanium, nickel, tin, chromium, niobium, gold, silver and their alloy plates, as well as metal plates such as stainless steel plates, carbon steel plates, and galvanized plates. In addition, the partition 2 and the end plate 1 can also be non-metallic plastic plates such as PP, PS, PC, ABS, polyamide, PMMA, polyoxymethylene, PET and PBT.

[0077] Preferably, the partition plate 2 and the end plate 1 are aluminum plates.

[0078] In addition, the present application also provides a battery module, which includes the above-mentioned partition 2 and end plate 1, and the partition 2 and the end plate 1 are assembled and welded together using the above-mentioned method.

[0079] In the welding method described in the present application, the two seams between the partition 2 and the end plate 1 are welded separately, and by controlling the width and length of the weld, it is beneficial to the reflux filling of the liquid molten material, reducing the reflux filling demand of the liquid molten material, and helping to improve the problem of insufficient liquid molten material at the end of the weld.

[0080] In addition, metal will cool down quickly after welding, and stress will inevitably exist inside the weld. If the two welds are the same length, when welding the second weld, the first weld will release stress after being heated, and this stress will tear the molten pool of the second weld. In the front and middle part of the weld, the impact of stress tearing can be eliminated by filling the liquid molten material, but at the end of the weld, there is not enough liquid aluminum to fill, and the impact of welding stress is like a crack. Therefore, in order to ensure that welding cracks will not occur inside the weld, the lengths of the two welds in this application are set to be different. Since there is a distance between the ends of the two welds, it can be ensured that each weld will not be affected by other welds when it is finished, which can effectively reduce the occurrence of cracks at the end of the weld.

[0081] Example 1

[0082] Taking an aluminum partition plate 2 with a thickness of 2 mm as an example, the raised portion 201 on the partition plate 2 is inserted into the mounting hole 101 on the aluminum end plate 1, and the raised portion 201 protrudes from the mounting hole 101 by 0.5 mm, forming a long annular gap between the raised portion 201 and the mounting hole 101, and a longer set of opposite sides in the long annular gap are welded by laser welding to form two welds of different lengths. Of the two welds of different lengths, the shorter weld is recorded as the first weld 3, and the longer weld is recorded as the second weld 4.

[0083] During welding, the first weld 3 is formed by the first welding, and then the second weld 4 is formed by the second welding. The center distance between the laser tracks of the first weld 3 and the second weld 4 is approximately equal to 2 mm. The starting points of the first weld 3 and the second weld 4 are arranged opposite to each other, and a position difference of 8 mm is formed between the end points.

[0084] The process parameters of laser welding of the first weld 3 and the second weld 4 are: welding power 3200 W, welding speed 80 mm / s, amplitude 2 mm, and frequency 150 Hz.

[0085] The embodiments of the present application are described above in conjunction with the accompanying drawings. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A welding method, wherein a first welding part comprises a protrusion, and a second welding part comprises a mounting hole, wherein the protrusion matches the mounting hole, It is characterized in that The welding method comprises: Before welding, the protrusion is inserted into the mounting hole, wherein the mounting hole and the protrusion are long strip structures; a long strip annular gap is formed between the protrusion and the mounting hole, and the long strip annular gap includes a first long gap and a second long gap that are arranged oppositely; and the first long gap and the second long gap extend along a first direction; During welding, the first long seam is firstly welded by laser welding to form a first weld; then the second long seam is welded by laser welding to form a second weld, wherein, along the first direction, the welding end point of the second weld exceeds the end of the first weld close to the welding end point of the second weld.

2. The welding method according to claim 1, It is characterized in that The welding directions of the first long seam and the second long seam are consistent when laser welding is performed, the welding starting point of the first weld is the first starting end, and the welding end point is the first end; the welding starting point of the second weld is the second starting end, and the welding end point is the second end; Along the first direction, there is a first distance between the first starting end and the second starting end, and there is a second distance between the first end and the second end. The length of the first distance is recorded as N, and the length of the second distance is recorded as W. N is greater than or equal to zero, and W is greater than zero.

3. The welding method according to claim 2, It is characterized in that Along the opposite direction of laser welding, the length that the first starting end exceeds the second starting end is the first distance; along the laser welding direction, the length that the second end exceeds the first end is the second distance, and the first distance is equal to the second distance.

4. The welding method according to claim 2, It is characterized in that The value range of W is: w≥3mm.

5. The welding method according to claim 2, It is characterized in that The height of the end plate is smaller than the height of the battery cell group, and the first direction extends in the vertical direction; when the first distance is smaller than the second distance, the distance between the second starting end and the middle height of the battery cell group is smaller than the distance between the second end and the middle height of the battery cell group.

6. The welding method according to any one of claims 1 to 5, It is characterized in that The welding process parameters of the first welding are consistent with those of the second welding.

7. The welding method according to any one of claims 1 to 5, It is characterized in that The welding process parameters of the laser welding are: welding power of 2000W to 5000W, welding speed of 60mm / s to 120mm / s, amplitude of 1mm to 4mm, and frequency of 100HZ to 220HZ.

8. The welding method according to any one of claims 1 to 5, It is characterized in that The length of the protrusion is set so that after the protrusion is inserted into the mounting hole, the length of the protrusion protruding from the mounting hole is 0.3 mm to 10 mm.

9. The welding method according to any one of claims 1 to 5, It is characterized in that The thickness of the partition is 1 mm to 4 mm. During welding, the center distance between the laser tracks of the first weld and the second weld is equal to the thickness of the partition.

10. A battery module, It is characterized in that It comprises a partition plate and an end plate, wherein the partition plate is a first welding part, and the end plate is a second welding part, and the partition plate and the end plate are assembled and welded together by the method described in any one of claims 1 to 9.

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