Method and system for welding a battery housing

Abstract

This disclosure relates to a welding method and welding system for a battery casing. The casing includes a housing surrounding a battery cell and a cover plate for sealing the ends of the housing. The welding method is used to weld the cover plate to the housing. The welding method includes: obtaining a welding path and dividing the welding path into at least a first segment and a second segment connected sequentially; controlling a welding head to weld at a uniform speed in the first segment; and controlling the welding head to weld at a uniform acceleration starting from the end of the first segment in the second segment. When welding the battery casing and the cover plate, making the welding speed of the second segment a uniform acceleration greater than that of the first segment can reduce the laser energy input of the welding head to the latter segment, i.e., reduce the line energy. Even if the welding heat from the first segment accumulates in the latter segment, it will ensure good consistency of the penetration depth between the first and latter segments of the welding path, thereby resulting in a high welding yield and good welding quality for the battery casing.

Description

Technical Field

[0001] This disclosure relates to the field of battery manufacturing technology, and more specifically, to a welding method and welding system for a battery casing. Background Technology

[0002] Square batteries are evolving towards longer lengths and thinner profiles to achieve larger heat dissipation areas and better safety performance. Currently, these batteries are generally over 1000mm in length and less than 13.5mm in thickness, while the outer casing thickness is generally no more than 0.3mm; for example, aluminum casings are typically no more than 0.3mm thick, and steel casings are typically no more than 0.2mm thick. However, during the welding process, the heat input from the earlier welded sections is transferred to the later unwelded sections, resulting in inconsistent weld penetration. Furthermore, the thinness of the casing contributes to poor welding quality. Summary of the Invention

[0003] The purpose of this disclosure is to provide a welding method and welding system for battery casings, so as to at least partially solve the problems existing in the related art.

[0004] To achieve the above objectives, this disclosure provides a welding method for a battery casing, the casing including a housing for surrounding a battery cell and a cover plate for closing the ends of the housing, the welding method being used to weld the cover plate to the housing, the welding method including: obtaining a welding path and dividing the welding path into at least a first segment and a second segment connected in sequence; controlling a welding head to weld at a uniform speed in the first segment; and controlling the welding head to weld at a uniform speed starting from the end of the first segment in the second segment.

[0005] Optionally, the step of obtaining the welding path and dividing the welding path into at least a first segment and a second segment connected in sequence includes: setting the ratio of the distance of the first segment to the distance of the second segment to 1:3 to 3:1, and setting the ratio of the speed of the second segment to the speed of the first segment to 1.05 to 1.3.

[0006] Optionally, the welding method includes:

[0007] After the step of obtaining the welding path and dividing the welding path into at least a first segment and a second segment connected in sequence, a starting segment is set before the first segment and an ending segment is set after the second segment;

[0008] Before the step of controlling the welding head to weld at a constant speed in the first segment, the welding head is controlled to accelerate to a first speed in the initial segment, wherein the first speed is the welding speed of the welding head in the first segment; and

[0009] After the step of controlling the welding head to accelerate uniformly in the second segment from the end of the first segment, the welding head is controlled to decelerate to zero in the final segment.

[0010] Optionally, the welding method includes: obtaining the defocusing amount of the welding head in the starting segment and adjusting the defocusing amount of the welding head to a preset defocusing amount.

[0011] Optionally, the welding method includes:

[0012] The defocusing amount of the welding head is read in real time during the welding path and adjusted to the preset defocusing amount.

[0013] Optionally, the cover plate is square and includes four sides, with rounded corners between every two adjacent sides. The step of obtaining the welding path and dividing the welding path into at least a first segment and a second segment connected in sequence includes:

[0014] The starting point of the first segment is set at the tangent point between the rounded corner of one end of the side to be welded and the side to be welded, and the ending point of the second segment is set at the middle position of the rounded corner of the other end of the side to be welded.

[0015] Optionally, the welding method includes:

[0016] Before welding with the welding head, the offset between the position information of the welding path and the preset position information is obtained; and

[0017] The movement of the welding head is controlled based on the offset.

[0018] Optionally, before the step of obtaining the welding path and dividing the welding path into at least a first segment and a second segment connected sequentially, the welding method includes:

[0019] The clamping mechanism is controlled to clamp the housing; and

[0020] The control clamping mechanism clamps the cover plate.

[0021] Optionally, the cover plate includes four sides, and the welding method includes:

[0022] After the welding head has finished welding one of the side edges in the preset welding area, the welding head is controlled to return to its initial position; and

[0023] Control the battery casing to rotate so that the other unwelded side rotates into the welded area.

[0024] According to a second aspect of the present disclosure, a welding system is provided, capable of welding the battery casing using the welding method provided in the present disclosure, the welding system comprising:

[0025] Welding head, used to emit laser light;

[0026] A drive mechanism for driving the welding head to move; and

[0027] The control module is used to control the driving speed of the drive mechanism.

[0028] Optionally, the welding system includes a first mounting base for mounting the battery casing, a CCD camera mounted on the mounting base for acquiring position information of the welding path, and a control module electrically connected to the CCD camera.

[0029] Optionally, the welding system includes a ranging sensor fixed in position relative to the welding head for measuring the defocusing amount of the welding head, and the control module is electrically connected to the ranging sensor.

[0030] Optionally, the welding system includes a mounting platform for the battery casing to pass through and a clamping mechanism for clamping the casing to the mounting platform, the clamping mechanism comprising:

[0031] The clamping element is slidably mounted on the mounting platform and can be close to or away from the surface of the housing;

[0032] An elastic element, elastically compressed, abuts between the mounting platform and the clamping element, for pressing the clamping element against the surface of the housing; and

[0033] A first linear drive mechanism, mounted on the mounting platform and connected to the clamping member, is used to overcome the elastic force of the elastic member and drive the clamping member away from the surface of the housing.

[0034] Optionally, a square through hole is formed on the mounting platform for the housing to pass through. Two adjacent edges of the square through hole extend outward with baffles for fitting with two corresponding adjacent surfaces of the battery housing. The clamping mechanism includes a first clamping mechanism for clamping the housing against one of the baffles and a second clamping mechanism for clamping the housing against the other baffle.

[0035] Optionally, the welding system includes a clamping mechanism mounted on a first fixed base. The clamping mechanism includes a clamping member for pressing against the surface of the cover plate and a second linear drive mechanism for driving the clamping member closer to or away from the cover plate. The outer contour of the clamping member that contacts the cover plate is located within the outer contour of the cover plate.

[0036] Optionally, the welding system includes an installation platform for mounting the battery casing, the installation platform being rotatably mounted on the first fixed base, and the clamping mechanism including: a rotary drive mechanism, the clamping member being mounted on the output end of the rotary drive mechanism for being driven by the rotary drive mechanism to rotate synchronously with the installation platform, and the rotary drive mechanism being mounted on the output end of a second linear drive mechanism for being driven by the second linear drive mechanism to move the clamping member closer to or away from the cover plate.

[0037] Optionally, the welding system comprises two systems, used for welding the cover plates at both ends of the housing, respectively.

[0038] By employing the above technical solution, when welding the battery casing and cover plate, the welding path is divided into at least a first segment and a second segment. The welding speed of the second segment is a uniform acceleration greater than that of the first segment. By increasing the welding speed of the latter part of the welding path (the second segment), the laser energy input from the welding head to the latter segment can be reduced, i.e., the line energy is reduced. In this way, even if the welding heat from the first segment accumulates in the latter segment, the penetration depth of the first and latter segments of the welding path will be consistent, resulting in a high welding yield and good welding quality for the battery casing.

[0039] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0040] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0041] Figure 1 This is a flowchart of a welding method provided by an exemplary embodiment of the present disclosure.

[0042] Figure 2 This is a flowchart of a welding method provided by an exemplary embodiment of the present disclosure.

[0043] Figure 3 This is a flowchart of a welding method provided by an exemplary embodiment of the present disclosure.

[0044] Figure 4 This is a schematic diagram of a welding system provided in an exemplary embodiment of the present disclosure.

[0045] Figure 5 This is a schematic diagram from another angle of a welding system provided in an exemplary embodiment of this disclosure.

[0046] Figure 6 This is a schematic diagram of a welding system provided by an exemplary embodiment of the present disclosure, omitting the welding head.

[0047] Figure 7 yes Figure 6 An enlarged view of part A in the image.

[0048] Figure 8 This is a schematic diagram of a battery casing not being clamped according to an exemplary embodiment of this disclosure.

[0049] Figure 9 This is a schematic diagram of a battery casing being clamped according to an exemplary embodiment of this disclosure.

[0050] Figure 10 This is a schematic diagram of a cover plate provided in an exemplary embodiment of this disclosure.

[0051] Figure 11 This is a schematic diagram of two welding systems provided in an exemplary embodiment of this disclosure.

[0052] Figure 12 This is a schematic diagram showing the position of the welding head provided in an exemplary embodiment of this disclosure.

[0053] Explanation of reference numerals in the attached figures

[0054] 11-Housing, 12-Cover plate, 121-Side, 122-Rounded corner, 200-Welding head, 201-Drive mechanism, 2011-Z-axis drive mechanism, 2012-X-axis drive mechanism, 2013-Y-axis drive mechanism, 2021-First fixed seat, 2022-Second fixed seat, 300-Clamping mechanism, 301-Clamping element, 3011-Adhesive piece, 302-Elastic element, 303-First linear drive mechanism, 310-First clamping mechanism, 320-Second clamping mechanism, 400-Pressure mechanism. 401-Clamping component, 402-Rotary drive mechanism, 403-Second linear drive mechanism, 500-CCD camera, 600-Distance sensor, 700-Mounting platform, 701-Square through hole, 702-Baffle, 703-Mounting protrusion, 101-Starting segment, 1011-Starting point, 102-First segment, 1021-Light emission point, 1022-End point of the first segment, 103-Second segment, 1031-Starting point of the second segment, 1032-Light receiving point, 104-Ending segment, 1041-Ending point. Detailed Implementation

[0055] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0056] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" are generally defined according to the usage habits of the welding system, as detailed in the relevant references. Figure 8 and Figure 9 In the drawing orientation, "inner" and "outer" refer to the inner and outer contours of the corresponding component itself. Terms such as "first" and "second" used in this disclosure are for distinguishing one element from another and do not have sequential or importance. Furthermore, when the following description relates to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0057] This disclosure provides a method for welding a battery casing, for example, a method for welding the casing of a square battery. This welding method can be implemented using the welding system provided in this disclosure. (Refer to...) Figure 7 The housing may include a housing 11 for surrounding the cell and a cover plate 12 for closing the ends of the housing 11. The welding method is used to weld the cover plate 12 to the housing 11, that is, to weld the edge of the cover plate 12 to the edges of the housing 11 around the cell.

[0058] Reference Figure 4 The welding system provided in this embodiment may include: a welding head 200, a drive mechanism 201, and a control module. The welding head 200 is used to emit a laser to perform laser welding on the weld seam; the drive mechanism 201 is used to drive the welding head 200 to move, as shown in the reference... Figure 4 and Figure 5 The drive mechanism 201 may include an X-axis drive mechanism 2012, a Y-axis drive mechanism 2013, and a Z-axis drive mechanism 2011 to drive the welding head 200 to move in the X, Y, and Z directions. All three drive mechanisms can be linear modules. The welding head 200 can be mounted on the Z-axis drive mechanism 2011, the Z-axis drive mechanism 2011 can be mounted on the X-axis drive mechanism 2012, and the X-axis drive mechanism 2012 can be mounted on the Y-axis drive mechanism 2013. The control module is used to control the drive speed of the drive mechanism 201, for example, controlling the drive speed of the drive mechanism 201 at different positions according to the requirements described below, so that the welding head 200 has a corresponding welding speed at different positions.

[0059] Reference Figure 1 The welding method provided in this disclosure includes:

[0060] In S3, the welding path is acquired and divided into at least a first segment 102 and a second segment 103 connected in sequence. The welding path is the weld between the shell 11 and the cover plate 12. The welding path can be pre-stored in the control system according to the size information of the cover plate 12, and the position information of the first segment 102 and the second segment 103 can be pre-stored by calculation. Alternatively, the welding path can be identified by a photographing device (such as a CCD camera) set on the welding system, and the control system can automatically divide the first segment 102 and the second segment 103 according to the photographic recognition information.

[0061] In S6, the welding head 200 is controlled to weld at a constant speed in the first segment 102. This can be achieved by controlling the movement of the drive mechanism 201 and its speed via the control module, thereby driving the welding head 200 to weld at a constant speed in the first segment 102.

[0062] In S7, the welding head 200 is controlled to accelerate uniformly from the end of the first segment 102 to the second segment 103. The control method can be as described above, which can be referred to here. Figure 12 The end point 1022 of the first segment 102 is the starting point 1031 of the second segment 103. It can be understood that the speed at the starting point 1031 of the second segment 103 is the uniform welding speed during the first segment 102.

[0063] The division of the welding path into at least the first segment 102 and the second segment 103 in this embodiment means that, according to the length of the welding path, it can also be divided into more segments, such as the first segment, the second segment, and the third segment. The speed of the second segment can be greater than that of the first segment, and the speed of the third segment can be greater than that of the second segment. Alternatively, the speed of the second segment can be greater than that of the first segment, and the third segment can be made to return to uniform motion, etc. The specific segmentation and the speed setting of each segment can be determined based on the weld metallographic analysis during the initial debugging.

[0064] Through the above technical solution, when welding the battery casing 11 and the cover plate 12, the welding path is divided into at least a first segment 102 and a second segment 103, and the welding speed of the second segment 103 is a uniform acceleration greater than that of the first segment 102. By increasing the welding speed of the latter part of the welding path (the second segment 103), the laser energy input of the welding head 200 to the latter part can be reduced, i.e., the line energy is reduced. In this way, even if the welding heat of the first segment (the first segment 102) accumulates in the latter part, the consistency of the penetration depth of the first and latter parts of the welding path will be guaranteed, thereby resulting in a high welding yield and good welding quality for the battery casing.

[0065] In this embodiment, step S3 may include: setting the ratio of the distance between the first segment 102 and the distance between the second segment 103 to 1:3 to 3:1, such as 1:1; and setting the ratio of the speed of the second segment 103 to the speed of the first segment 102 to 1.05 to 1.3, such as 1.2. In other words, the starting point 1031 of the second segment 103 can be set between one-quarter and three-quarters of the entire welding path, and the welding speed of the second segment 103 can be between 1.05 and 1.3 times the welding speed of the first segment 102. Setting the positional and speed relationships of the first segment 102 and the second segment 103 within this parameter range can achieve better weld penetration consistency, ensuring that the weld penetration is consistent from beginning to end. The preset values ​​for the first segment 102 and the second segment 103 can be determined based on the preliminary debugging. A long weld is divided into segments (usually 9 segments) and metallographically analyzed. The specific weld penetration depth is observed under a metallographic microscope. The segment with very small penetration depth fluctuation can be set as the first segment 102, and the segment with larger penetration depth can be set as the second segment 103. Battery products of different sizes can use this method to determine the data for the first segment 102 and the second segment 103 respectively, and can be pre-stored in the control system for welding of the corresponding products.

[0066] In this embodiment of the disclosure, reference is made to Figure 2 Welding methods may include:

[0067] After S3, in S4, a starting segment 101 is set before the first segment 102, and an ending segment 104 is set after the second segment 103. During the period between the starting segment 101 and the ending segment 104, only the movement of the welding head 200 is used, and no light is emitted. Here, "before" and "after" in the context of the first segment 102 and the second segment 103 are based on the movement path of the welding head 200, and not on the front and back defined by the physical part of the welding system.

[0068] Before S6 and after S4, in S5, the welding head 200 is accelerated to a first speed in the initial segment 101, where the first speed is the welding speed of the welding head 200 in the first segment 102; and

[0069] After S6, in S7, the control welding head 200 decelerates to zero in the final segment 104. (Refer to...) Figure 12Where S represents the position of the welding head 200 during its stroke, and V represents the velocity of the welding head 200 at the corresponding position. At the starting point 1011, the welding head 200 is stationary, i.e., its velocity is 0. The welding head 200 accelerates in the initial segment 101, reaching the first velocity at the starting point of the first segment (light emission point 1021). Then, the welding head 200 emits light at the starting point of the first segment (light emission point 1021) and welds uniformly in the first segment 102 at the first velocity. When the welding head 200... When the welding head 200 moves to the end of the first segment 1022 (i.e. the starting point of the second segment 1031), it begins to accelerate, making its welding speed in the second segment 103 greater than its speed in the first segment 102, so as to ensure the consistency of the penetration depth of the first segment 102 and the second segment 103. When the welding head 200 moves to the end of the second segment (i.e. the finishing point 1032), it begins to decelerate in the ending segment 104, and decelerates to 0 at the end point 1041 of the ending segment 104, returning to a stationary state.

[0070] In one embodiment, reference is made to... Figure 5 The welding system may include a ranging sensor 600 fixed in a position relative to the welding head 200, which can be used to measure the defocus amount of the welding head 200. The control module can be electrically connected to the ranging sensor 600 to control the drive mechanism 201 (such as the Z-axis drive mechanism 2011) to drive the welding head 200 to move based on the measured defocus amount information. In this embodiment, the welding method may include: acquiring the defocus amount of the welding head 200 at the starting segment 101 and adjusting the defocus amount of the welding head 200 to a preset defocus amount. For example, the defocus amount can be read at the starting point 1011, and then the defocus amount can be adjusted to the preset value while accelerating the welding head 200 at the starting segment 101, that is, adjusted to the value required for welding, thereby ensuring that the defocus amount during welding is accurate, meets the welding process requirements, and ensures the welding quality.

[0071] In one embodiment, reference is made to... Figure 5 The welding system may include a ranging sensor 600 fixed in position relative to the welding head 200, which can be used to measure the defocusing amount of the welding head 200. A control module may be electrically connected to the ranging sensor 600 to control the drive mechanism 201 (such as a Z-axis drive mechanism 2011) to drive the welding head 200 to move based on the measured defocusing amount information. In this embodiment, the welding method may include:

[0072] In the welding path (i.e., in the first segment 102 and the second segment 103), the defocus amount of the welding head 200 is read in real time and adjusted to the preset defocus amount. In this way, the defocus amount can be kept consistent throughout the welding process, thereby obtaining a high welding quality. In this embodiment of the present disclosure, the defocus amount of the welding head 200 can be adjusted to the preset value in the initial segment 101 by the Z-axis drive mechanism 2011. Then, during the welding of the first segment 102 and the second segment 103, the defocus amount is detected in real time and adjusted by the Z-axis drive mechanism 2011 to avoid inconsistencies in the defocus amount due to differences in the placement of the battery casing. For example, the edge of the cover plate 12 to be welded is usually placed horizontally along the X-axis, and the welding head 200 is welded by moving along the X-axis. Once the edge is tilted due to placement error, the defocus amount of the welding head 200 can be obtained in real time and compared with the preset defocus amount, and adjusted by the drive mechanism 201.

[0073] In one embodiment, reference is made to... Figure 4 The welding system may include a first fixing base 2021 for mounting the battery casing, i.e., the battery casing is fixed relative to the first fixing base 2021. The first fixing base 2021 may be configured to surround the welding head 200 on three sides to protect the welding process. A CCD camera 500 may be mounted on the first fixing base 2021 for acquiring the position information of the welding path. The control module is electrically connected to the CCD camera 500. The welding path captured by the CCD camera 500 can be fed back to the control module, and the control module can control the movement of the welding head 200. The CCD camera 500 may be mounted on the side of the first fixing base 2021 along the X direction, avoiding the welding space to avoid interference with the welding head 200, and enabling simultaneous imaging and welding to improve welding efficiency. In this embodiment, the welding method may include: acquiring the offset between the position information of the welding path and preset position information before welding with the welding head 200; and controlling the movement of the welding head 200 according to the offset. Since the positioning of the battery casing cannot be guaranteed to be completely consistent each time, the welding path (i.e., the area to be welded) of the battery casing can be obtained before welding. This path is then compared with pre-stored welding path information. The position of the welding head 200 is adjusted based on the offset between the actual welding path and position information and the preset welding path position information to compensate for this offset. This ensures good consistency of the welding trajectory between each battery casing, resulting in a high battery yield. Thin-shell welding requires higher precision in the welding trajectory. The repeatability positioning accuracy is generally less than 0.05mm. Repeatability positioning accuracy refers to the positional deviation of the welding light-emitting point and the 30th / 50th welding light-emitting point after continuously repeating the welding trajectory 30-50 times. This embodiment of the present disclosure obtains and compensates for this deviation value to accurately adjust the welding trajectory and ensure welding accuracy.

[0074] In this embodiment of the disclosure, the battery can be a square battery, as shown in the reference. Figure 10 The cover plate 12 can be constructed as a square and may include four sides 121. A rounded corner 122 is provided between every two adjacent sides 121. S3 may include: setting the starting point (light-emitting point 1021) of the first segment 102 at the tangent point between the rounded corner 122 at one end of the side 121 to be welded and the side 121 to be welded; and setting the ending point (i.e., light-receiving point 1032) of the second segment 103 at the middle position of the rounded corner 122 at the other end of the side 121 to be welded. Figure 10 For example, when welding the upper side 121, the welding head 200 emits light from the position where the upper left rounded corner 122 is tangent to the upper side 121. After welding along the side 121, the light is collected at the middle position of the upper right rounded corner 122. After collection, the laser heat is transferred to the lower half of the upper right rounded corner, so that the lower half of the rounded corner has a penetration depth and is welded. Correspondingly, since the upper right rounded corner has been welded during the welding of the upper side, when welding the right side 121, the light emission point of the welding head 200 is set at the position where the upper right rounded corner is tangent to the right side 121, and the light collection point can be set at the middle position of the lower right rounded corner. Similarly, when welding the lower side 121, the light-emitting point of the welding head 200 can be set at the position where the lower right rounded corner is tangent to the lower side 121, and the light-receiving point can be set at the middle position of the lower left rounded corner. When welding the left side 121, the light-emitting point of the welding head 200 can be set at the position where the lower left rounded corner is tangent to the left side 121, and the light-receiving point can be set at the middle position of the upper left rounded corner. Thus, the welding of the entire outer edge of the cover plate 12 can be completed, and by precisely controlling the positions of the light-emitting and light-receiving points, the weld depth at all points on the cover plate 12 can be made consistent, ensuring welding quality.

[0075] According to one embodiment of this disclosure, referring to Figure 4 and Figures 6 to 9The welding system may include a mounting platform 700 for the battery casing to pass through and a clamping mechanism 300 for clamping the casing 11 to the mounting platform 700. The clamping mechanism 300 includes a clamping member 301, an elastic member 302 and a first linear drive mechanism 303. The clamping member 301 is slidably mounted on the mounting platform 700, and can be close to or away from the surface of the housing 11. The clamping member 301 can be provided with a fitting piece 3011 at the position for fitting the housing 11 to fit tightly against the surface of the housing 11. The elastic member 302 (e.g., spring or elastic rubber) is elastically compressed and abuts between the mounting platform 700 and the clamping member 301 to press the clamping member 301 against the surface of the housing 11. For example, a mounting protrusion 703 can be provided on the mounting platform 700, and a corresponding protrusion can be provided on the clamping member 301. The elastic member 302 can abut between the mounting protrusion 703 and the protrusion of the clamping member 301. A first linear drive mechanism 303 (e.g., linear module or cylinder drive mechanism) is mounted on the mounting platform 700 and connected to the clamping member 301 to overcome the elastic force of the elastic member 302 and drive the clamping member 301 away from the surface of the housing 11. Before the battery casing is passed through the mounting platform 700, the clamping member 301 is first driven by the first linear drive mechanism 303 to compress the elastic member 302 and move it away from the casing 11 (see reference). Figures 6 to 8 After the battery casing passes through the mounting platform 700, the first linear drive mechanism 303 releases the clamping member 301 in the opposite direction, so that the clamping member 301 is pressed against the surface of the housing 11 under the elastic reset action of the elastic member 302 to press the housing 11. After the welding is completed, the first linear drive mechanism 303 can drive the clamping member 301 away from and release the housing 11 again to facilitate the removal and unloading of the battery.

[0076] Reference Figure 7 and Figure 8 The mounting platform 700 can have a square through hole 701 for the housing 11 to pass through. Clamping mechanisms can be provided on all four sides of the square through hole 701 to clamp the housing 11 on each of the four sides. In other embodiments, refer to... Figures 7 to 9 The two adjacent edges of the square through-hole 701 can each extend outward with a baffle 702 for fitting with two corresponding adjacent surfaces of the battery casing. The clamping mechanism 300 includes a first clamping mechanism 310 for clamping the casing 11 against one baffle 702 and a second clamping mechanism 320 for clamping the casing 11 against the other baffle 702. Figure 9For example, the first clamping mechanism 310 is used to clamp the housing 11 against the lower baffle 702, and the second clamping mechanism 320 is used to clamp the housing 11 against the left baffle 702. The baffle 702 can achieve the initial positioning of the battery casing passing through the square through hole 701, ensuring that the relative position of the battery casing and the mounting platform 700 is accurate and stable, resulting in good consistency of the welding trajectory for each welding and ensuring the yield of battery casing welding.

[0077] Reference Figure 7 The welding system may include a clamping mechanism 400 mounted on the first fixed base 2021. The clamping mechanism 400 includes a clamping member 401 for clamping against the surface of the cover plate 12 and a second linear drive mechanism 403 for driving the clamping member 401 closer to or further away from the cover plate 12. The second linear drive mechanism 403 may be a linear module or a cylinder drive mechanism. The surface of the clamping member 401 that contacts the cover plate 12 may be adapted to the structure at the cover plate 12. For example, when there are protruding electrodes or other structures at the cover plate 12, the clamping member 401 may be correspondingly provided with a recessed structure to accommodate the protruding portion. When the battery casing passes through the mounting platform 700 to mount the shaft, the second linear drive mechanism 403 drives the clamping member 401 to press against the surface of the cover plate 12, thereby positioning the cover plate 12 relative to the housing 11. When the outer shell is thin, thermal stress during the welding process can easily cause the outer shell to deform, which increases the gap between the cover plate 12 and the shell 11. By setting a clamping mechanism and a pressing mechanism, this problem can be effectively solved, eliminating thermal deformation during the welding process and ensuring welding quality and reliability.

[0078] The outer contour of the clamping member 401 that contacts the cover plate 12 is located within the outer contour of the cover plate 12. Correspondingly, the outer contour of the clamping member 301 that contacts the housing 11 does not exceed the edge of the housing 11. This ensures that the clamping member 401 and the clamping member 301 will not block the weld and affect the welding effect.

[0079] In this embodiment, reference is made to Figure 3 The welding method in this embodiment may include: before S3,

[0080] In S1, the clamping mechanism 300 clamps the housing 11. For example, when the first clamping mechanism 310 and the second clamping mechanism 320 are provided, the second clamping mechanism 320 at the longer side of the cover plate 12 can clamp first, and then the first clamping mechanism 310 at the shorter side can be controlled to clamp, so that the longer side can be stably pre-positioned; and

[0081] In S2, the clamping mechanism 400 clamps the cover plate 12. After the battery casing is positioned by the clamping mechanism 300 and the clamping mechanism 400, the welding path is obtained and the welding process is carried out. This can avoid the casing from being deformed due to thermal stress, and ensure the welding quality and welding reliability.

[0082] The mounting platform 700 can be rotatably mounted on the first fixed base 2021, and is used to rotate the side 121 of the cover plate 12 to be welded to a preset welding area. That is, after welding is completed on one side edge of the cover plate 12, the unwelded side can be moved to the preset welding area by rotating the mounting platform 700. The preset welding area can be, for example, […]. Figure 9 The upper side of the cover plate 12 shown is positioned on a horizontal plane. The clamping mechanism 400 may include a rotary drive mechanism 402. The clamping member 401 can be mounted on the output end of the rotary drive mechanism 402, and is driven by the rotary drive mechanism 402 to rotate synchronously with the mounting platform 700. This ensures that the clamping member 401 can rotate synchronously with the battery casing, guaranteeing that the clamping member 401 can still clamp the cover plate 12 after rotation, and preventing deformation of the cover plate 12 and housing 11 that would affect the welding quality. A second linear drive mechanism 403 can be mounted on the first fixed base 2021. The rotary drive mechanism 402 can be mounted on the output end of the second linear drive mechanism 403, and is driven by the second linear drive mechanism 300 to move the clamping member 401 closer to or away from the cover plate 12. The rotary drive mechanism 402 can be a servo motor.

[0083] As described above, the cover plate 12 may include four sides 121, and the welding method of this embodiment may include:

[0084] After the welding head 200 finishes welding one side 121 in the preset welding area, it is controlled to return to its initial position, for example, to a position away from the battery casing in the XYZ direction, such as returning to the starting point 1011, to avoid interference with the clamping mechanism 300 on the mounting platform 700 and other components such as the battery casing. Figure 12 In the diagram, H represents the Z-axis height of the welding head 200. At the starting point 1011, the height of the welding head is relatively high to avoid interference. After the starting segment 101, the height of the welding head 200 (i.e., the defocusing amount) remains consistent.

[0085] And control the battery casing to rotate so that the other unwelded side 121 rotates to the welding area, so that the next welding action can be performed by repeating the above welding process. During welding, one short side of the cover plate 12 can be welded first, then one long side, and then another short side and another long side. Welding the short side first can initially position the welding trajectory and ensure the accuracy of the trajectory of subsequent welding.

[0086] Reference Figure 11The welding system can be two, used to weld at the cover plates 12 at both ends of the housing 11 respectively, thereby improving the welding effect. The first fixing seat 2021 of each welding system can be slidably mounted on the second fixing seat 2022, so as to adjust the distance between the two welding systems by sliding to facilitate welding of battery housings of various lengths.

[0087] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0088] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0089] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for welding a battery casing, the casing comprising a housing for surrounding a battery cell and a cover plate for closing the ends of the housing, the welding method being used to weld the cover plate to the housing, characterized in that, The welding method includes: Obtain the welding path and divide the welding path into at least a first segment and a second segment connected sequentially; Control the welding head to weld at a uniform speed in the first segment; and The welding head is controlled to accelerate welding uniformly from the end of the first segment to the second segment; The step of obtaining the welding path and dividing the welding path into at least a first segment and a second segment connected in sequence includes: setting the ratio of the distance of the first segment to the distance of the second segment to 1:3 to 3:1, and setting the ratio of the speed of the second segment to the speed of the first segment to 1.05 to 1.3; The welding method includes: After the step of obtaining the welding path and dividing the welding path into at least a first segment and a second segment connected in sequence, a starting segment is set before the first segment and an ending segment is set after the second segment; Before the step of controlling the welding head to weld at a constant speed in the first segment, the welding head is controlled to accelerate to a first speed in the initial segment, wherein the first speed is the welding speed of the welding head in the first segment; and After the step of controlling the welding head to accelerate uniformly in the second segment from the end of the first segment, the welding head is controlled to decelerate to zero in the final segment.

2. The welding method according to claim 1, characterized in that, The welding method includes: obtaining the defocusing amount of the welding head in the starting segment and adjusting the defocusing amount of the welding head to a preset defocusing amount.

3. The welding method according to claim 1, characterized in that, The cover plate is square in shape and includes four sides, with rounded corners between every two adjacent sides. The step of obtaining the welding path and dividing the welding path into at least a first segment and a second segment connected in sequence includes: The starting point of the first segment is set at the tangent point between the rounded corner of one end of the side to be welded and the side to be welded, and the ending point of the second segment is set at the middle position of the rounded corner of the other end of the side to be welded.

4. The welding method according to claim 1, characterized in that, The welding method includes: Before welding with the welding head, the offset between the position information of the welding path and the preset position information is obtained; and The movement of the welding head is controlled based on the offset.

5. The welding method according to any one of claims 1-4, characterized in that, Before the step of obtaining the welding path and dividing the welding path into at least a first segment and a second segment connected sequentially, the welding method includes: The clamping mechanism is controlled to clamp the housing; and The control clamping mechanism clamps the cover plate.

6. The welding method according to claim 1, characterized in that, The cover plate includes four sides, and the welding method includes: After the welding head has finished welding one of the side edges in the preset welding area, the welding head is controlled to return to its initial position; and Control the battery casing to rotate so that the other unwelded side rotates into the welded area.

7. A welding system, characterized in that, The battery casing can be welded using the welding method of any one of claims 1-6, and the welding system comprises: Welding head, used to emit laser light; A drive mechanism for driving the welding head to move; and The control module is used to control the driving speed of the drive mechanism.

8. The welding system according to claim 7, characterized in that, The welding system includes a first mounting base for mounting the battery casing, a CCD camera mounted on the first mounting base for acquiring the position information of the welding path, and a control module electrically connected to the CCD camera.

9. The welding system according to claim 7, characterized in that, The welding system includes a distance sensor fixed at a position relative to the welding head, used to measure the defocusing amount of the welding head, and the control module is electrically connected to the distance sensor.

10. The welding system according to claim 7, characterized in that, The welding system includes a mounting platform for the battery casing to pass through and a clamping mechanism for clamping the casing to the mounting platform, the clamping mechanism comprising: The clamping element is slidably mounted on the mounting platform and can be close to or away from the surface of the housing; An elastic element, elastically compressed, abuts between the mounting platform and the clamping element, for pressing the clamping element against the surface of the housing; and A first linear drive mechanism, mounted on the mounting platform and connected to the clamping member, is used to overcome the elastic force of the elastic member and drive the clamping member away from the surface of the housing.

11. The welding system according to claim 10, characterized in that, The mounting platform has a square through hole for the housing to pass through. Two adjacent edges of the square through hole extend outward with baffles for fitting with two corresponding adjacent surfaces of the battery housing. The clamping mechanism includes a first clamping mechanism for clamping the housing against one of the baffles and a second clamping mechanism for clamping the housing against the other baffle.

12. The welding system according to claim 7, characterized in that, The welding system includes a clamping mechanism mounted on a first fixed base. The clamping mechanism includes a clamping member for pressing against the surface of the cover plate and a second linear drive mechanism for driving the clamping member closer to or away from the cover plate. The outer contour of the clamping member that contacts the cover plate is located within the outer contour of the cover plate.

13. The welding system according to claim 12, characterized in that, The welding system includes an installation platform for mounting the battery casing, the installation platform being rotatably mounted on the first fixed base, the clamping mechanism including a rotary drive mechanism, the clamping member being mounted on the output end of the rotary drive mechanism and being driven by the rotary drive mechanism to rotate synchronously with the installation platform, the rotary drive mechanism being mounted on the output end of a second linear drive mechanism and being driven by the second linear drive mechanism to move the clamping member closer to or away from the cover plate.

14. The welding system according to claim 7, characterized in that, The welding system consists of two parts, used for welding the cover plates at both ends of the housing.

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