Welding method and battery module

Abstract

The application discloses a welding method and a battery module. The welding method is used for welding a workpiece and comprises the following steps: determining a to-be-welded area of the workpiece, the to-be-welded area having a head end and a tail end; locating a welding starting position in the to-be-welded area and ensuring that the distance between the welding starting position and the head end is greater than 0; starting a laser, forming a laser beam, and moving the laser beam from the welding starting position to the head end along the to-be-welded area to form a preheating section; moving the laser beam from the head end to the tail end along the to-be-welded area, and ensuring that the travel path of the laser beam at least partially coincides with the preheating section to form a reinforcing section; and stopping the laser. In this embodiment, the laser head is first moved from the welding starting position to the head end to perform a first welding and form a preheating section. After the laser beam reaches the head end, the laser beam is moved towards the tail end to improve the defect that the preheating section has a shallow penetration depth, thereby improving the quality of a weld and the welding strength.

Description

Technical Field

[0001] This application relates to the field of welding technology, and in particular to a welding method and a battery module. Background Technology

[0002] During the welding process, because the workpiece is at a low temperature before welding, the temperature of the workpiece at the beginning of the weld cannot rise rapidly, resulting in a shallow penetration at the starting point and weakening the strength of the weld. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a welding method that can improve the weld quality of the initial section of the weld and increase the strength of the weld.

[0004] This application also proposes a battery module formed by welding based on the above welding method.

[0005] A welding method according to a first aspect of this application is used to weld a workpiece having a region to be welded, the region to be welded having a head end and a tail end along its own extending direction, comprising the following steps:

[0006] Determine the area of ​​the workpiece to be welded, the area to be welded having a head end and a tail end;

[0007] The welding start position is located within the area to be welded, and the distance between the welding start position and the beginning end is greater than 0.

[0008] Turn on the laser to form a laser beam, and move the laser beam along the area to be welded from the welding start position to the first end to form a preheating section;

[0009] The laser beam is moved from the beginning end along the area to be welded to the end end, and the travel path of the laser beam at least partially overlaps with the preheating section to form a reinforcing section;

[0010] The laser is turned off.

[0011] The welding method according to the embodiments of this application has at least the following beneficial effects:

[0012] The welding start position is set within the area to be welded, with a distance greater than zero between it and the beginning of the weld. During welding, the laser beam is first moved from the welding start position to the beginning of the weld, forming a preheating section. Then, the laser beam is moved along the area to be welded from the beginning to the end, allowing for a second welding operation in the preheated section. This second welding improves upon the uneven weld penetration defects from the first welding, thereby improving the quality of the initial weld section and increasing weld strength. Furthermore, because the initial weld section is preheated, a rapid rise in workpiece temperature is avoided, reducing the formation of porosity during welding.

[0013] According to some embodiments of this application, the welding method further includes the following steps:

[0014] After the laser is turned on, the power of the laser is gradually increased to P1 while the laser beam moves;

[0015] After the laser beam moves to the first end, the power of the laser is adjusted to P2 so that the melting depth of the preheating section reaches the set value.

[0016] According to some embodiments of this application, the specific steps for ensuring that the welding start position is located within the area to be welded and that the distance between it and the start end is greater than 0 are as follows:

[0017] The welding start position is set at the tail end.

[0018] According to some embodiments of this application, the specific steps for moving the laser beam from the beginning end along the area to be welded to the end are as follows:

[0019] The power of the laser is maintained at P2, so that the laser beam moves from the beginning to the end with constant energy.

[0020] According to some embodiments of this application, the specific steps for ensuring that the welding start position is located within the area to be welded and that the distance between it and the start end is greater than 0 are as follows:

[0021] The welding start position is set between the first end and the last end.

[0022] According to some embodiments of this application, the specific steps for setting the welding start position between the first end and the last end are as follows:

[0023] The distance between the welding start position and the tail end is less than the distance between the welding start position and the head end.

[0024] According to some embodiments of this application, the specific steps for moving the laser beam from the beginning end along the area to be welded to the end are as follows:

[0025] After the laser beam moves to the welding start position, the power of the laser is increased to P3, and the laser beam moves from the welding start position to the tail end with constant energy.

[0026] According to some embodiments of this application, P2 is 2500W to 3000W, and P3 is 3500W to 4000W.

[0027] According to some embodiments of this application, the sum of P1 and P2 is greater than P3.

[0028] The battery module according to a second aspect of this application includes a weld formed by welding based on the welding method described in the first aspect of the embodiment.

[0029] The battery module according to the embodiments of this application has at least the following beneficial effects:

[0030] The components in the battery module are welded using the welding method of the first aspect embodiment, which improves the defect of shallow penetration at the front of the weld and reduces weld porosity, thereby increasing the welding strength and improving the reliability of the battery module.

[0031] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0032] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0033] Figure 1 This is a flowchart of a welding method according to the first aspect of this application;

[0034] Figure 2 This is a flowchart of a welding method according to another embodiment of the first aspect of this application;

[0035] Figure 3 This is a flowchart of a welding method according to another embodiment of the first aspect of this application;

[0036] Figure 4 This is a flowchart of a welding method according to another embodiment of the first aspect of this application;

[0037] Figure 5 For workpiece based Figure 4 A schematic diagram of the welding trajectory for the Chinese welding method;

[0038] Figure 6 This is a schematic diagram of a workpiece structure formed by the welding method based on the first aspect embodiment;

[0039] Figure 7 for Figure 6 A cross-sectional schematic diagram;

[0040] Figure 8 A schematic diagram of the welding trajectory when the outline of the area to be welded is a polygonal line;

[0041] Figure 9 Another schematic diagram of the welding trajectory when the outline of the area to be welded is a polygonal line.

[0042] Figure 10 This is a schematic diagram of the welding trajectory when the outline of the area to be welded is a curve.

[0043] Figure 11 This is a schematic diagram of the structure of the battery module according to the second aspect of this application;

[0044] Figure 12 for Figure 11 Another perspective view of the battery module;

[0045] Workpiece 100;

[0046] Welding area 200, head end 210, tail end 220;

[0047] Welding start position 300;

[0048] 400mm weld seam;

[0049] 500 cells, 510 terminals;

[0050] Connecting piece 600. Detailed Implementation

[0051] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0052] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, 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.

[0053] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0054] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0055] In the description of this application, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] Figure 1 This is a flowchart of a welding method according to the first aspect of this application. Figure 5 For workpiece based Figure 4 A schematic diagram of the welding trajectory for the Chinese welding method. Figure 6 This is a schematic diagram of a workpiece structure formed by the welding method based on the first aspect embodiment. Figure 7 for Figure 6 A cross-sectional schematic diagram. Figure 8 This is a schematic diagram showing the outline of the area to be welded as a broken line. Figure 9 This is another schematic diagram of the welding trajectory when the outline of the area to be welded is a polygonal line. Figure 10 This is a schematic diagram showing the curved outline of the area to be welded. (Refer to...) Figure 1 , Figures 5 to 10 The welding method of the first aspect embodiment, used for welding workpiece 100, includes the following steps:

[0057] S100, Determine the area to be welded of the workpiece, which has a beginning and a end;

[0058] S200, so that the welding start position 300 is located within the area to be welded 200, and the distance between the welding start position 300 and the beginning end 210 is greater than 0;

[0059] S300, turn on the laser to form a laser beam, and move the laser beam welding starting position 300 along the area to be welded 200 to the beginning 210 to form a preheating section;

[0060] S400, the laser beam is moved from the beginning 210 along the area to be welded 200 to the end 220, and the travel path of the laser beam at least partially overlaps with the preheating section to form a strengthening section.

[0061] S500, turn off the laser.

[0062] Specifically, the welding area 200 refers to the area on the workpiece that needs to be welded, i.e., the area where the weld will be located after welding is completed. Based on welding requirements, the welding area 200 of the workpiece 100 is determined. The welding area 200 has a beginning end 210 and a end end 220. The beginning end 210 of the welding area 200 is the position where the front end of the weld 400 is located after welding, and the end end 220 of the welding area 200 is the position where the rear end of the weld 400 is located after welding. The welding start position 300 is the starting position of the laser beam spot irradiating the workpiece 100 during welding. In conventional technology, the welding start position 300 is set at the end of the weld 400. However, because the workpiece 100 is at a low temperature in the early stages of welding, the workpiece 100 absorbs most of the energy, resulting in a shallow penetration depth in the front section of the weld 400 (the area from the welding start position 300 to the beginning end 210, i.e., the preheating section in this embodiment), leading to a shorter effective length of the weld 400 and reduced welding strength. Based on this, the welding method of this embodiment sets the welding starting position 300 within the area to be welded 200, and the distance from the first end 210 is greater than 0. First, the laser head is moved from the welding starting position 300 towards the first end 210. After the laser beam reaches the first end 210, it is moved towards the tail end 220, allowing the front section of the weld 400 to undergo secondary welding, forming a reinforced section. During the second welding process, the defect of shallow penetration in the front section of the weld 400 during the first welding can be improved, such as… Figure 6 and Figure 7 As shown, this improves the quality of the front section of weld 400, thereby increasing weld strength. Furthermore, a single weld can preheat the workpiece 100, reducing porosity during the welding process.

[0063] It should be noted that, depending on the actual welding situation, the outline of the area to be welded 200 can be a straight line (e.g., ...). Figure 5 As shown), broken line (as shown) Figure 8 (as shown) and smooth curves (such as) Figure 10 As shown in the figure, the outline of the preheating section can also be a straight line, a broken line, or a smooth curve.

[0064] For example, when the outline of the area to be welded 200 is a straight line, the welding start position 300 is set within the area to be welded 200 and offset from the position of the beginning end 210 (e.g., Figure 5 As shown, the laser beam moves in a straight line along the area to be welded 200 to the beginning 210, and then moves in the opposite direction to the end 220 to complete the welding of the workpiece 100.

[0065] When the area to be welded 200 is a broken line, that is, the area to be welded 200 includes several segments connected in sequence, the welding start position 300 is set within the area to be welded 200 and offset from the first end 210, and is located within the range of the foremost segment (e.g., Figure 9As shown), the laser beam moves in a straight line along the area to be welded 200 to the beginning 210, and then moves in a zigzag line along the area to be welded 200 to the end 220, completing the welding of the workpiece 100. When the welding starting position 300 is not within the foremost range (e.g., Figure 8 As shown, the laser beam moves along the welding area 200 in a zigzag pattern to the beginning 210, and then moves along the welding area 200 from the beginning 210 to the end 220, thus completing the welding of the workpiece 100.

[0066] When the area to be welded 200 is curved, the welding start position 300 is set within the area to be welded 200 and offset from the position of the beginning end 210 (e.g., Figure 10 The laser beam is moved in a curved path along the area to be welded 200 to the beginning 210, and then moved in a curved path along the area to be welded 200 from the beginning 210 to the end 220, thus completing the welding of the workpiece 100.

[0067] The outline of the area to be welded 200 can be a curve or a broken line in three-dimensional space. For example, if the workpiece is a metal pipe, the area to be welded 200 extends along the circumference of the pipe.

[0068] Reference Figure 2 , Figure 2 The flowchart of another embodiment of the welding method of the first aspect of this application is shown. In some embodiments, step S300 further includes the following step: after the laser is turned on, the power of the laser is gradually increased to P1 while the laser beam is moving.

[0069] Step S400 also includes the following steps: after the laser beam moves to the first end 210, the power of the laser is adjusted to P2 so that the melting depth of the preheating section reaches the set value.

[0070] Specifically, the workpiece 100 is preheated using power P1 for the first welding. As mentioned above, the weld quality of the first welding is low, and the penetration depth does not reach the set value (the required value for welding, set according to welding requirements). Therefore, after the first welding is completed, that is, after the laser beam moves to the beginning 210 of the area to be welded 200, the power of the laser is changed to P2. The magnitudes of P1 and P2 are not limited; that is, P2 can be less than, equal to, or greater than P1. The value of P2 is determined by the penetration depth formed by the first welding, so that the penetration depth of the weld 400 after the second welding reaches the set value.

[0071] In this process, the laser power is gradually increased, P1. For example, the welding starting position 300 is set within a distance of 1mm to 2mm from the beginning 210. When the laser beam moves to a distance of 0.5mm to 1mm from the welding starting position, the laser power is increased from 0 to P1. This avoids a sudden increase in laser power that would cause a rapid rise in the temperature of the workpiece 100, leading to defects such as porosity in the weld 400. Furthermore, the increase in laser power is synchronized with the movement of the laser head, increasing the welding speed. In addition, since the initial section of the weld 400 is welded twice, P1 and P2 can be set smaller compared to the single welding in conventional techniques. This reduces the energy of the laser beam during welding, thereby reducing the formation of porosity in the initial section of the weld 400.

[0072] Reference Figure 3 , Figure 3 In another embodiment of the welding method according to the first aspect of this application, in some embodiments, step S200, which involves placing the welding start position 300 within the area to be welded 200 and ensuring that the distance between the welding start position 300 and the first end 210 is greater than 0, specifically involves: S200', setting the welding start position 300 at the tail end 220. Specifically, since the welding start position 300 is located at the tail end 220, the section from the first end 210 to the tail end 220 is a reinforced section. Therefore, the entire weld 400 can be welded twice, thereby improving the quality of the weld 400 and increasing the welding strength.

[0073] Reference Figure 3 Based on the above embodiment, step S400, which moves the laser beam from the beginning 210 along the area to be welded 200 to the end 220, specifically involves: S400', maintaining the laser power at P2, and moving the laser beam from the beginning 210 to the end 220 with constant energy. Specifically, when the laser power is adjusted to P2, the laser beam performs secondary welding on the entire weld 400 with constant energy, improving the uniformity of the weld penetration and thus improving the welding quality.

[0074] Reference Figure 4 and Figure 5 , Figure 4 This is a flowchart of a welding method according to another embodiment of the first aspect of this application. Figure 5The diagram illustrates the welding trajectory of workpiece 100 based on the welding method of the first aspect embodiment. In some embodiments, step S200, which involves placing the welding start position 300 within the area to be welded 200 and ensuring that the distance between the welding start position 300 and the first end 210 is greater than 0, specifically involves setting the welding start position 300 between the first end 210 and the last end 220. Specifically, by setting the welding start position 300 between the first end 210 and the last end 220, secondary welding is not required for the entire area to be welded 200; only the front section of the weld 400 is subjected to secondary welding to form a reinforced section. This improves the shallow penetration depth of the front section of the weld 400 and simultaneously increases welding efficiency.

[0075] Based on the above embodiments, the specific steps of step S200, where the welding start position 300 is set between the first end 210 and the last end 220, are as follows:

[0076] The distance between the welding start position 300 and the tail end 220 is made smaller than the distance between the welding start position 300 and the head end 210. Specifically, setting the welding start position 300 closer to the tail end 220 increases the power P1 boost time, allowing the laser power to rise slowly to P1, thereby reducing the heat input to the workpiece 100 and reducing the porosity of the weld 400.

[0077] Since the front section of weld 400 is welded twice and the rear section of weld 400 (the area from the welding start position 300 to the tail end 220) is welded once, in order to make the penetration depth of the front section and the rear section of weld 400 more consistent, it is necessary to increase the melting degree of the laser beam on the rear section of weld 400 to further improve the quality of weld 400.

[0078] Based on this, refer to Figure 4 Based on the above embodiment, step S400, which moves the laser beam from the beginning 210 along the welding area 200 to the end 220, is as follows: S400”, after the laser beam moves to the welding start position 300, the power of the laser is increased to P3, and the laser moves from the welding start position 300 to the end 220 with constant energy at the P3 power.

[0079] Specifically, the laser power is increased to P3, increasing the laser beam energy and thus enhancing its melting ability on the workpiece 100. This ensures that the penetration depth of the later section of the weld 400 is more consistent with that of the earlier section. P2 can be incrementally increased to P3. For example, after the laser beam moves to the welding start position 300, the power is slowly increased, reaching P3 after the laser beam moves approximately 0.5mm and remaining stable. This avoids a rapid increase in laser beam energy that could cause a sharp rise in the temperature of the workpiece 100, thereby reducing porosity in the weld 400. Furthermore, reducing the laser head's moving speed can increase the degree of melting of the workpiece 100 by the laser beam, thereby improving the uniformity of the penetration depth throughout the weld 400.

[0080] Based on the above embodiments, P2 is 2500W to 3000W, and P3 is 3500W to 4000W. Specifically, in conventional technology, a laser power of 4000W is usually required to weld the connecting piece 600 and the pole piece 510. However, in this embodiment, since the front section of the weld 400 is preheated using the power of P1, a power of less than 4000W P2 can be used during the second welding of the front section, reducing the laser energy and thus reducing the generation of porosity during the welding of the front section of the weld 400. During the welding of the rear section of the weld 400, since the front section of the weld 400 has been welded twice, heat will be transferred to the rear section of the weld 400. Therefore, a power of less than 4000W P3 can be used during the welding of the rear section of the weld 400 to reduce energy input, thereby reducing the generation of porosity during the welding of the rear section of the weld 400 and improving the welding quality.

[0081] Based on the above implementation, the sum of P1 and P2 is greater than P3. Specifically, due to heat diffusion in the workpiece during welding, some of the heat generated during the first welding is lost during the second welding process using P2 after the first welding at power P1. Therefore, in order to make the penetration depth of the first and second weld sections more consistent, this embodiment ensures that the sum of the power P1 used for the first welding of the first weld section and the power P2 used for the second welding of the first weld section is greater than the power P3 used for welding the second weld section, i.e., P1 + P2 > P3.

[0082] In some embodiments, S500, the laser is turned off, specifically by gradually reducing the laser power to 0. Specifically, the laser power is gradually reduced to 0 to prevent the laser beam from suddenly disappearing and causing arc voids in the weld 400. Furthermore, this slows down the rate of temperature drop in the workpiece 100 after welding, preventing cracks in the workpiece 100 and improving welding quality.

[0083] In some embodiments, setting the laser power includes the following steps: automatically adjusting the laser power via a controller. Specifically, this embodiment eliminates the need for manual adjustment of the laser power; instead, a controller is used to adjust the laser power, resulting in higher efficiency and accuracy.

[0084] Reference Figure 11 and Figure 12 The battery module of the second aspect embodiment includes a weld 400 formed based on the welding method of the first aspect embodiment. Specifically, for example, the battery module includes a connecting piece 600 and a plurality of battery cells 500. Each battery cell 500 includes a terminal post 510. The connecting piece 600 is welded to the terminal post 510 of an adjacent battery cell 500 using the welding method of the first aspect embodiment, thereby forming the weld 400. The welding of the connecting piece 600 and the terminal post 510 of the battery cell 500 using the welding method of the first aspect embodiment improves the defect of shallow penetration of the first weld 400, reduces weld porosity, and increases welding strength, thereby improving the reliability of the connection between the connecting piece 600 and the terminal post 510.

[0085] Furthermore, since the battery module of this embodiment adopts the welding method of the first aspect embodiment, the battery module of this embodiment has all the beneficial effects brought by the welding method of the first aspect embodiment, which will not be repeated here.

[0086] It should be noted that the welding method of the first aspect embodiment is not limited to the welding of the connecting piece 600 and the pole post 510. For example, the welding of the middle side plate and the end plate, the welding of the end plate and the side plate, etc., can all adopt the welding method of the first aspect embodiment to improve the welding strength.

[0087] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A welding method, characterized in that, The process for welding workpieces includes the following steps: Determine the area of ​​the workpiece to be welded, the area to be welded having a head end and a tail end; The welding start position is located within the area to be welded, and is positioned between the beginning and the end of the weld, with the distance between the welding start position and the end of the weld being less than the distance between the welding start position and the beginning of the weld. And ensure that the distance between the welding start position and the first end is greater than 0; Turn on the laser to form a laser beam, and move the laser beam along the area to be welded from the welding start position to the first end to form a preheating section. While the laser beam is moving, gradually increase the power of the laser P1. The power of the laser is adjusted to P2, where P2 ≥ P1, so that the laser beam moves from the beginning to the end of the welding area, and the path of the laser beam at least partially overlaps with the preheating section to form a reinforced section, and the penetration depth of the preheating section reaches a set value; after the laser beam moves to the welding start position, the power of the laser is increased to P3, and the laser beam moves from the welding start position to the end of the welding area with constant energy, where P2 is 2500W to 3000W and P3 is 3500W to 4000W; The laser is turned off.

2. The welding method according to claim 1, characterized in that, The sum of P1 and P2 is greater than P3.

3. A battery module, characterized in that, This includes welds formed using the welding method according to any one of claims 1 or 2.

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