An electrode assembly and a method of manufacturing the same

Abstract

This application relates to the field of battery cell manufacturing technology, specifically disclosing a racetrack-shaped weld seam welding method and a battery cell welding apparatus based on battery cells. The racetrack-shaped weld seam welding method includes: controlling a welding head to move along a first direction through a first welding segment to weld the first welding segment; controlling the welding head to move along the first direction into a first overtravel region; controlling the welding head to move along a second direction to leave the first overtravel region, the second direction being opposite to the first direction; controlling the battery cell to rotate, such that the welding head moving along the second direction passes through a second welding segment relative to the battery cell, and controlling the welding head to begin welding when the welding point of the welding head moves to the starting point of the second welding segment. In this solution, after the welding head completes the welding of the first welding segment, it completes a process of deceleration, reversal of motion, and re-acceleration in the first overtravel region, reducing the concentration of welding energy caused by low-speed start-up in the starting region of the second welding segment.

Description

Technical Field

[0001] This application relates to the field of battery cell manufacturing technology, and in particular to a method and apparatus for welding racetrack-shaped weld seams based on battery cells. Background Technology

[0002] During the battery cell manufacturing process, the cell casing and top cover typically require welding to form a sealed connection. For some cells, due to factors such as structural shape, the outer contour of the top cover or casing is not a simple straight line or circle, but rather forms a racetrack-shaped contour enclosed by two opposing straight edges and two opposing rounded edges. Accordingly, during welding, a racetrack-shaped weld needs to be formed along this racetrack-shaped side seam.

[0003] In existing racetrack-shaped battery cell top cover side seam welding processes, the entire weld seam is typically divided into straight lines and rounded corners, for example, including straight weld seams, rounded corner weld seams, straight weld seams, and rounded corner weld seams in sequence. Figure 1 As shown, the battery cell is in a horizontal position at the start of welding. Figure 1 As shown by the dashed outline in the image, the welding head first moves to the starting point of the straight weld ( Figure 1 (point d in the diagram), and after completing the focus calibration, initiate the translation axis movement so that the welding head moves along the straight direction to the end point of the straight weld (point d in the diagram). Figure 1 (Point b in the diagram) to complete the welding of the corresponding straight weld. After the straight weld is completed, the welding head enters the fillet weld welding process. At this time, the fixture needs to be activated to rotate the battery cell, so that the battery cell rotates from the horizontal turntable to the vertical position and then to the horizontal position (rotating 180°) in the direction of arrow a; correspondingly, as shown in the diagram... Figure 1 As shown, the welding head needs to follow the rotation of the battery cell, moving from the starting point of the fillet weld to the ending point, that is, from point b, through point c, and finally to point d. This process is then repeated to weld another straight weld and a fillet weld.

[0004] During the welding process, the requirements for motion control differ between the straight and rounded regions of the racetrack-shaped weld. When the welding head switches from a straight weld to a rounded weld, it needs to rise and fall vertically and move horizontally in the opposite direction to the original straight weld welding process. This horizontal reversal makes it difficult for the welding head to maintain a stable and uniform speed during the rounded weld welding process. This results in excessive energy input to the welding head in the transition section between the straight and rounded welds, leading to excessive weld point accumulation, uneven weld surface, and in severe cases, burn-through of the casing, thermal deformation, and other problems, affecting the welding quality and sealing reliability of the battery cell. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a method and apparatus for welding racetrack-shaped welds based on battery cells, in order to solve some or all of the above-mentioned problems.

[0006] To achieve the above-mentioned technical objectives, the first aspect of this application provides a method for welding a racetrack-shaped weld seam based on a battery cell, wherein the racetrack-shaped weld seam includes a plurality of adjacent first welding segments and second welding segments; The welding method includes: The welding head is controlled to move along a first direction past the first welding segment to weld the first welding segment; The welding head is controlled to move along the first direction into the first overtravel region, wherein when it is in the first overtravel region, the welding point of the welding head separates from the runway-shaped weld and the welding head stops welding; The welding head is controlled to move along a second direction to leave the first overtravel region, the second direction being opposite to the first direction; The cell is controlled to rotate so that the welding head, which moves along the second direction, passes through the second welding section relative to the cell, and the welding head begins welding when the welding point of the welding head moves to the starting point of the second welding section.

[0007] Further, before the controlled welding head moves along the first direction past the first welding segment, the following steps are included: The welding head is controlled to move along the first direction to leave the second overtravel area, and when the welding point of the welding head moves to the starting point of the first welding segment, the welding head is controlled to start welding, wherein when it is in the second overtravel area, the welding point of the welding head separates from the runway-shaped weld and the welding head stops welding. The control of the cell rotation, such that the welding head moving in the second direction passes the second welding segment relative to the cell, includes: The welding head is controlled to move along the second direction into the second overtravel region.

[0008] Furthermore, during the process of controlling the welding head to move along the second direction to leave the first overtravel area, the welding head accelerates, and when the welding point of the welding head moves to the starting point of the second welding segment, the welding head accelerates to a second preset speed.

[0009] Furthermore, the second preset speed is greater than the average movement speed of the second welding segment; The average speed is calculated based on the moving path and duration of the second welding segment.

[0010] Furthermore, the starting end of the second welding segment at least partially overlaps with the ending end of the first welding segment, so that the starting welding area of ​​the second welding segment partially overlaps with the ending welding area of ​​the first welding segment, and / or, The starting end of the first welding segment and the ending end of the second welding segment at least partially overlap, so that the starting welding area of ​​the first welding segment and the ending welding area of ​​the second welding segment partially overlap.

[0011] Furthermore, the first welding segment includes interconnected straight line segments and arc segments; The straight segment covers the entire length of one straight weld of the racetrack-shaped weld; The arc segment covers a portion of the length of a rounded corner weld of the racetrack-shaped weld; The second weld segment covers a portion of the length of a fillet weld of the racetrack-shaped weld.

[0012] Furthermore, the first welding segment includes one straight segment and two circular arc segments; The two arc segments are respectively located at both ends of the straight line segment.

[0013] Further, before the controlled welding head moves along the first direction past the first welding segment, the following steps are included: Visual recognition is performed on the runway-shaped weld to obtain the weld width and determine the welding trajectory of the weld joint.

[0014] The second aspect of this application provides a battery cell welding apparatus for performing the battery cell-based racetrack-shaped weld welding method described in any of the preceding claims, and includes: a welding head, a clamp, and a rotary drive mechanism. The clamp is used to secure the battery cell; The rotary drive mechanism is connected to the clamp and is used to drive the clamp to rotate; The welding head is used to weld the racetrack-shaped weld on the battery cell.

[0015] Furthermore, it also includes: mobile mechanisms; The moving mechanism includes: an x-axis guide rail and a z-axis guide rail; The z-axis guide rail is slidably mounted on the x-axis guide rail along the x-axis direction; The welding head is slidably mounted on the z-axis guide rail along the z-axis direction.

[0016] As can be seen from the above technical solutions, this application provides a method and apparatus for welding racetrack-shaped welds based on battery cells; wherein, the method for welding racetrack-shaped welds based on battery cells includes a plurality of adjacent first welding segments and second welding segments; the welding method includes: controlling a welding head to move along a first direction through the first welding segment to weld the first welding segment; controlling the welding head to move along the first direction into a first overtravel region, wherein, when located in the first overtravel region, the welding point of the welding head separates from the racetrack-shaped weld and the welding head stops welding; controlling the welding head to move along a second direction to leave the first overtravel region, the second direction being opposite to the first direction; controlling the battery cell to rotate, such that the welding head moving along the second direction passes through the second welding segment relative to the battery cell, and when the welding point of the welding head moves to the starting point of the second welding segment, controlling the welding head to start welding.

[0017] In this solution, after the welding head completes the welding of the first welding segment, it enters the first overtravel zone and completes the deceleration, reversal, and re-acceleration process in the first overtravel zone. This reduces the welding energy concentration caused by low-speed start-up, reversal transition, or unstable cell rotation in the starting area of ​​the second welding segment. It can reduce the risk of weld point accumulation, burn-through, or uneven weld formation and improve the welding quality and sealing reliability of the racetrack-shaped weld. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the welding process of an existing welding apparatus provided in the embodiments of this application; Figure 2 A diagram showing the division between the first and second welding segments in a racetrack-shaped weld seam welding method based on a battery cell, provided in an embodiment of this application; Figure 3 A schematic diagram illustrating the welding of the first weld segment using a racetrack-shaped weld seam based on a battery cell, as provided in an embodiment of this application. Figure 4 A diagram showing the division between the first and second welding segments in a racetrack-shaped weld seam welding method based on a battery cell, provided in another embodiment of this application; Figure 5 A schematic diagram illustrating the welding of the first weld segment using a racetrack-shaped weld seam based on a battery cell, as provided in another embodiment of this application; Figure 6 A schematic diagram showing the preparation of welding the second welding segment for a racetrack-shaped weld seam welding method based on a battery cell, provided in another embodiment of this application; Figure 7 A schematic diagram showing the completion of the second weld segment in a racetrack-shaped weld seam welding method based on a battery cell, as provided in another embodiment of this application; In the diagram: 1. First welding segment; 1a. Straight segment; 1b. Circular arc segment; 2. Second welding segment; 3. First overtravel zone; 4. Second overtravel zone; 10. Welding head; 20. Battery cell; Arrow a: Direction of cell rotation; Point b: End point of straight weld; Point c: Midpoint of fillet weld; Point d: Start point of straight weld; Arrow e: First direction; Arrow f: Second direction; Point g: End point of fillet weld. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.

[0021] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of 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 the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a replaceable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0023] Please see Figures 2 to 5 The first aspect of this application provides a method for welding racetrack-shaped welds based on battery cells. The racetrack-shaped weld can be as follows: Figure 2As shown, it includes multiple adjacent first welding segments 1 and second welding segments 2, and the multiple first welding segments 1 and multiple second welding segments 2 are connected in sequence to form a closed weld. For example, there can be two first welding segments 1 and two second welding segments 2, and two straight welds and two rounded welds are connected end to end in sequence to form a closed runway-shaped trajectory.

[0024] In this embodiment, the runway-shaped weld itself has both straight welds and rounded fillet welds. For example... Figure 1 As shown, the area between point d and point b is a straight weld; the area between point b and point g is a fillet weld. A standard racetrack-shaped weld can have two straight welds and two fillet welds.

[0025] In the embodiments provided in this application, the welding process is completed by the welding head 10. The welding head 10 can be a laser welding head or other welding components capable of outputting welding energy to the weld seam of the battery cell 20. For ease of explanation, the following description uses the welding head 10 outputting laser energy as an example, but it should not be construed as this application being limited to laser welding. Accordingly, "start welding" in the following description can be understood as the welding head 10 starting to output welding energy to the welding point; "stop welding" can be understood as the welding head 10 stopping to output welding energy to the welding point.

[0026] The welding point of action described in this application refers to the location where the welding energy of the welding head 10 actually acts on the battery cell 20 or the racetrack-shaped weld. Taking laser welding as an example, the welding point of action can be the location of the laser spot irradiating the surface of the battery cell 20. Taking other welding methods as examples, the welding point of action can be the area where the welding energy is concentrated on the surface of the workpiece. Separation of the welding point of action from the racetrack-shaped weld means that the welding point of action is located outside the effective welding area of ​​the racetrack-shaped weld, or that the welding point of action no longer acts on the trajectory area where the weld needs to be formed.

[0027] Welding methods include: S1. Control the welding head 10 to move along a first direction past the first welding segment 1 to weld the first welding segment 1. Wherein, the first direction is as follows: Figure 3 As indicated by arrow e, it can be the negative direction of the x-axis. During the welding of the first welding segment 1 by welding head 10, the battery cell is in a horizontal position.

[0028] S2. Control the welding head 10 to move along the first direction into the first overtravel region 3, wherein when it is in the first overtravel region 3, the welding action point of the welding head 10 is separated from the runway-shaped weld and the welding head 10 stops welding. S3. Control the welding head 10 to move along a second direction to leave the first overtravel region 3, the second direction being opposite to the first direction. Wherein, the second direction is as follows: Figure 3 As shown by the arrow f in the figure, it can be the positive direction of the x-axis.

[0029] S4. Control the cell to rotate so that the welding head 10, which moves along the second direction, passes the second welding section 2 relative to the cell. When the welding action point of the welding head 10 moves to the starting point of the second welding section 2, control the welding head 10 to start welding. Then the welding head 10 continues to move along the second direction to complete the welding of the second welding section 2.

[0030] In some embodiments, the first welding segment 1 and the second welding segment 2 can be divided according to the geometry of the racetrack-shaped weld. Specifically, the first welding segment 1 is a straight weld in the racetrack-shaped weld, and the second welding segment 2 is a rounded fillet weld adjacent to the straight weld. That is, the start and end points of the first welding segment 1 can correspond to the geometric start and end points of the straight weld, respectively, and the start point of the second welding segment 2 can correspond to the start point of the rounded fillet weld adjacent to the straight weld. Specifically, the welding head 10 moves along a first direction through the first welding segment 1 to complete the welding of the straight weld. After the welding head 10 moves to the end point of the first welding segment 1, it continues to move along the first direction into the first overtravel region 3 and stops welding within the first overtravel region. Subsequently, the welding head 10 moves along a second direction opposite to the first direction to leave the first overtravel region 3, while controlling the cell 20 to rotate, so that the welding head 10 moving along the second direction passes through the second welding segment 2 relative to the cell 20. When the welding point of the welding head 10 moves to the starting point of the second welding segment 2, the welding head 10 is controlled to start welding to weld the fillet weld.

[0031] In the above embodiment, the welding head 10 does not stop moving at the end point of the first welding segment 1, but further enters the first overtravel region 3, where it decelerates and changes direction. This ensures that when the welding head 10 moves to the starting point of the second welding segment 2, it has a certain speed, which helps reduce weld point accumulation at the starting point of the fillet weld due to the welding head 10 starting from a stationary or low-speed state. This embodiment can improve the welding stability when switching from a straight weld to a fillet weld by setting the first overtravel region 3 without changing the geometric division of the first welding segment 1 and the second welding segment 2.

[0032] In one embodiment, such as Figure 2 and Figure 3 As shown, the first welding segment 1 includes a straight segment 1a and an arc segment 1b connected to each other; the straight segment 1a covers the entire length of a straight weld of the racetrack-shaped weld; the arc segment 1b covers part of the length of a rounded fillet weld of the racetrack-shaped weld; and the second welding segment 2 covers part of the length of a rounded fillet weld of the racetrack-shaped weld.

[0033] Specifically, the straight segment 1a can extend from the starting point of a straight weld to the ending point of the straight weld; the arc segment 1b connects to the downstream end of the straight segment 1a along the first direction and extends along the starting area of ​​the adjacent fillet weld. That is, the first welding segment 1 does not only cover the purely straight portion of the racetrack-shaped weld, but further extends beyond the geometric connection point between the straight weld and the fillet weld, and covers part of the starting area of ​​the adjacent fillet weld. Correspondingly, the second welding segment 2 can be configured to cover the remaining portion of the fillet weld not covered by the first welding segment 1, such as the top arc area or the middle area of ​​the fillet weld.

[0034] In this embodiment, when the welding head 10 moves along the first direction through the first welding segment 1, it first passes through and welds the straight segment 1a, and then continues along the first direction to pass through and weld the arc segment 1b. Since the arc segment 1b is a part of the fillet weld near the straight weld, the arc segment 1b can be welded in advance during the movement of the welding head 10 along the first direction. After the welding head 10 completes the welding of the arc segment 1b, it continues along the first direction into the first overtravel region 3, and stops welding after entering the first overtravel region 3. Subsequently, the welding head 10 leaves the first overtravel region 3 along the second direction opposite to the first direction, while controlling the cell 20 to rotate, so that the welding head 10 passes through the second welding segment 2 relative to the cell 20; when the welding point of the welding head 10 moves to the starting point of the second welding segment 2, the welding head 10 is controlled to start welding, and then the welding head 10 continues to move along the second direction to complete the welding of the second welding segment 2.

[0035] In existing welding methods, there is a high risk of weld point accumulation in the area where the weld transitions from a straight weld to a fillet weld. In this embodiment, the starting area of ​​the fillet weld is pre-defined within the first welding segment 1, and welding is completed during the continuous movement of the welding head 10 along the first direction. This allows the welding head 10 to begin welding in the transition zone between the straight weld and the fillet weld when welding the second welding segment 2. Instead, it begins welding from the subsequent area of ​​the fillet weld after reversing and accelerating through the first overtravel zone 3. This further reduces weld point accumulation, burn-through, or uneven weld formation in the starting area of ​​the fillet weld and avoids weld point accumulation caused by acceleration and deceleration of the welding head 10 in the transition zone between the straight and fillet welds.

[0036] Specifically, during the transition from a straight weld to a rounded fillet weld, the weld trajectory gradually changes from a straight line to a circular arc. The relative position between the welding head 10 above the cell and the weld, the welding angle, the welding distance, and the projection position of the welding point on the weld all change. In other words, the transition zone between the straight weld and the rounded fillet weld is in a multi-axis motion adjustment state, which poses a high risk of insufficient matching with the preset welding energy parameters (frequency, pulse width, etc.). Therefore, using this transition zone as the acceleration starting point for welding will lead to a high risk of excessive welding energy input in a local area, resulting in weld point accumulation.

[0037] Based on this, in this embodiment, a portion of the rounded fillet weld near the straight fillet weld is designated as the first welding segment 1, and is completed by the welding head 10 as the arc segment 1b when welding the first welding segment 1 along the first direction. Thus, the starting point of the second welding segment 2 is no longer located at the geometric starting end of the rounded fillet weld, but rather at a position relatively far from the transition zone between the straight fillet weld and the rounded fillet weld. Furthermore, due to the pre-acceleration from the first overtravel region 3, rounded fillet welding can be performed only after the relative motion state between the welding head 10 and the battery cell 20 has become more stable. This further reduces the risks of weld point accumulation, weld offset, and uneven forming, thereby improving the welding quality of the rounded fillet weld.

[0038] In one embodiment, see Figures 4 to 7 In step S1 above, before controlling the welding head 10 to move along the first direction through the first welding segment 1, the following steps are included: S0. Control the welding head 10 to move along the first direction to leave the second overtravel region 4, and when the welding action point of the welding head 10 moves to the starting point of the first welding segment 1, control the welding head 10 to start welding. When located in the second overtravel region 4, the welding action point of the welding head 10 separates from the runway-shaped weld and the welding head 10 stops welding.

[0039] In step S4 above, the cell is controlled to rotate so that the welding head 10, moving in the second direction, passes the second welding segment 2 relative to the cell. Afterwards, the process includes: S5. Control the welding head 10 to move along the second direction into the second overtravel zone 4.

[0040] In this embodiment, the path along which the welding head 10 moves horizontally includes a welding area corresponding to the first welding segment 1 or the second welding segment 2, a first overtravel area 3, and a second overtravel area 4, with the first overtravel area 3 and the second overtravel area 4 located on both sides of the welding area. Furthermore, in this embodiment, the second overtravel area 4 serves as both the introduction overtravel area for entering the first welding segment 1 and the exit overtravel area after the second welding segment 2 is completed.

[0041] Specifically, such as Figure 5As shown, before welding begins, the battery cell 20 is fixed on the fixture and is in a horizontal position. At this time, the welding head 10 is located in the second overtravel zone 4, the welding head 10 is in a stopped welding state, and the welding point of the welding head 10 is separated from the racetrack-shaped weld, specifically... Figure 5 The x1 coordinate position is used to indicate the starting point of welding. When preparing to begin welding, the welding head 10 is controlled to move along the first direction to leave the second overtravel region 4, meaning the welding head 10 accelerates within the second overtravel region 4. When the welding point of the welding head 10 moves to the starting point of the first welding segment 1, welding begins. That is, the x2 coordinate position is the light-emitting point of the first welding segment 1.

[0042] Then, the welding head 10 continues to move along the first direction, and the welding point passes through the first welding segment 1, specifically, it moves to... Figure 5 The first welding segment 1 is welded at the x5 coordinate position. During this process, the battery cell 20 remains horizontal, and the welding head 10 mainly completes the welding of the first welding segment 1 by moving along the first direction. That is, the x5 coordinate position is the lead-out switching point of the first welding segment 1.

[0043] After the welding head 10 completes the welding of the first welding segment 1, the welding head 10 is controlled to continue moving along the first direction and enter the first overtravel region 3, specifically, it can move to... Figure 6 The x6 coordinate position is shown in the diagram. When the welding head 10 enters the first overtravel zone 3, the welding action point of the welding head 10 separates from the runway-shaped weld, and the welding head 10 stops welding. Thus, the welding head 10 can complete deceleration, stopping, and reversing actions in the first overtravel zone 3 without continuously inputting welding energy within the effective welding area of ​​the runway-shaped weld.

[0044] Subsequently, as Figures 6 to 7 As shown, the welding head 10 is controlled to move along the second direction to leave the first overtravel region 3, and the clamp is controlled to drive the battery cell 20 to rotate. Specifically, it can be... Figure 6 The clockwise rotation shown in the diagram causes the unwelded area downstream of the first welding segment 1 along the first direction to be rotated upwards for welding head 10 to weld. During the rotation, the battery cell 20 can gradually rotate from an initial horizontal state to a vertical state under the drive of the rotation drive mechanism, and then rotate from a vertical state to a horizontal state, completing a 180° rotation. During this process, the welding head 10 moves along the second direction and gradually approaches the starting point of the second welding segment 2, forming a compound relative motion between the welding head 10 and the battery cell 20. When the welding point of the welding head 10 moves to the starting point of the second welding segment 2, the welding head 10 is controlled to start welding. Under the combined action of the welding head 10 moving along the second direction and the rotation of the battery cell 20, the welding point of the welding head 10 moves along the second welding segment 2, thereby completing the welding of the second welding segment 2. During this process, the welding head 10 moves from... Figure 6The x6 coordinate position in the middle is moved to Figure 5 The x2 coordinate position is shown in the figure. Among them, the x7 coordinate position is the light-introducing point of the second welding segment 2, and the x8 coordinate position is the light-out point of the second welding segment 2.

[0045] After welding head 10 completes welding of the second welding segment 2, it continues to move along the second direction into the second overtravel region 4, that is, further moves to the x1 coordinate position. When welding head 10 enters the second overtravel region 4, the welding point of welding head 10 separates from the runway-shaped weld again, welding head 10 stops welding, and completes the reversal from the second direction to the first direction in the second overtravel region 4. Furthermore, as... Figure 7 The battery cell is then rotated back to a horizontal position, so that the second overtravel region 4 can serve both as a space for the welding head 10 to be pulled out after the second welding segment 2 is welded, and as an acceleration space before the first welding segment 1 begins to be welded. Then, steps S0 to S5 are repeated until all welding segments are welded, thus completing the welding of the racetrack-shaped weld.

[0046] In this embodiment, before entering the first welding segment 1, the welding head 10 can accelerate in the non-welding state within the second overtravel region 4; after completing the first welding segment 1, it can enter the first overtravel region 3 and complete the reversal in the non-welding state; then the welding head 10 approaches the second welding segment 2 again along the second direction, and cooperates with the battery cell 20 to rotate from a horizontal posture to a vertical posture, and then from a vertical posture to a horizontal posture, to complete the welding of the second welding segment 2. This avoids low-speed welding caused by the reversal at the starting welding positions of the first welding segment 1 and the second welding segment 2, thereby reducing the risk of weld point accumulation, burn-through, and uneven weld formation in the start and end areas of the rounded corner welding, and improving the continuity and sealing reliability of the racetrack-shaped weld.

[0047] In one embodiment, see Figures 4 to 7 The first welding segment 1 includes a straight segment 1a and two arc segments 1b; the two arc segments are respectively located at both ends of the straight segment. In this embodiment, the arc segments 1b of one first welding segment 1 and the arc segments 1b of the other first welding segment 1 correspond to the two ends of the fillet weld, and the second welding segment 2 corresponds to the middle part of the fillet weld.

[0048] In this embodiment, when welding the first welding segment 1 along the first direction, the welding head 10 first welds an arc segment 1b before entering the straight segment 1a, thus avoiding the starting welding point of the welding head 10 entering the first welding segment 1 being the transition zone between the straight weld and the fillet weld. Compared to the first welding segment 1 only including the straight segment 1a, or only setting the arc segment 1b at the downstream end of the straight segment 1a, this embodiment can simultaneously improve the welding connection quality at both ends of the straight segment 1a. On the one hand, the arc segment 1b located at the starting end of the straight segment 1a can reduce the problem of trajectory breakpoints or uneven weld points when switching from the previous fillet weld to the straight segment 1a; on the other hand, the arc segment 1b located at the ending end of the straight segment 1a can reduce the problem of low-speed welding and weld point accumulation when switching from the straight segment 1a to the next fillet weld, thereby achieving the effect of improving the overall weld point uniformity, trajectory continuity, and sealing reliability of the racetrack-shaped weld.

[0049] Furthermore, in this embodiment, the arc segment 1b at one end of the straight segment 1a can be equivalent to the forward extension of the straight weld, and the arc segment 1b at the other end of the straight segment 1a can be equivalent to the backward extension of the straight weld. This transforms the low-speed welding area, which is originally in the transition zone between the straight weld and the fillet weld and is easily affected by axial acceleration / deceleration or reversal, into a continuous welding area when the welding head 10 passes through the first welding segment 1 along the first direction. This improves the consistency of weld point spacing and the uniformity of weld formation in the connection area at both ends of the straight weld. At the same time, since the two arc segments 1b have already covered the area of ​​the adjacent fillet weld near the straight segment 1a, the subsequent second welding segment 2 can start welding from the area of ​​the fillet weld that is relatively far away from the straight weld. This allows the fillet welding stage to avoid the low-speed range where the motion axis acceleration / deceleration, reversal, or multi-axis coordination is still unstable at the fillet end, reducing the risk of weld point accumulation, burn-through, and thermal deformation caused by excessive energy input per unit length of weld.

[0050] In one embodiment, during the process of controlling the welding head to move along the first direction to leave the second overtravel region, the welding head accelerates, and when the welding point of the welding head 10 moves to the starting point of the first welding segment 1, the welding head 10 is accelerated to a first preset speed, and then the welding head 10 passes through the first welding segment 1 at a constant speed to perform welding.

[0051] In one embodiment, during the process of controlling the welding head 10 to move along the second direction to leave the first overtravel region 3, the welding head 10 accelerates, and when the welding point of the welding head 10 moves to the starting point of the second welding segment 2, the welding head accelerates to the second preset speed.

[0052] In this embodiment, the welding head 10 does not start welding directly from a stationary or low-speed state at the starting point of the first welding segment 1 or the second welding segment 2, but has entered a preset motion state before reaching the corresponding welding segment, thereby reducing the low-speed welding and energy concentration phenomenon at the starting position.

[0053] In practical applications, the first preset speed and the second preset speed can be set according to the trajectory characteristics of the first welding segment 1 and the second welding segment 2, respectively. For example, when the first welding segment 1 mainly corresponds to straight-line welding, the first preset speed can be adapted to the stable speed of straight-line welding; when the second welding segment 2 corresponds to rounded-corner welding, the second preset speed can be adapted to the relative motion state between the welding head 10 and the battery cell 20. This allows different welding segments to have a relatively stable welding speed at the start of welding, improving the consistency of weld point spacing and reducing the risk of weld point accumulation, burn-through, or uneven weld formation.

[0054] In one embodiment, the second preset speed is greater than the average movement speed of the second welding segment 2; the average movement speed is calculated based on the movement path and movement duration of the second welding segment 2.

[0055] Specifically, in this embodiment, the second welding segment 2 can be used as the top arc segment of the fillet weld in the racetrack-shaped weld. Since the welding process of the second welding segment 2 requires the welding head 10 to move along the second direction and the battery cell 20 to rotate under the drive of the fixture, it is generally difficult to form the same stable uniform speed range as the straight welding segment. To avoid the welding head 10 starting welding in the low-speed start-up stage or the stage of insufficient speed, this embodiment calculates the average movement speed of the second welding segment 2 based on its movement path and movement duration, and uses this average movement speed as a reference speed to determine whether the welding head 10 has left the low-speed start-up range.

[0056] The movement path of the second welding segment 2 can be understood as the path length traversed by the second welding segment 2 during its required movement to complete the welding process. For example, it can be the trajectory length traversed by the starting point of the second welding segment 2 during the rotation of the battery cell. The movement duration can be the preset running time required for the welding head 10 and the battery cell 20 to complete the welding of the second welding segment 2.

[0057] It should be noted that the average movement speed is not the instantaneous speed of the second welding segment 2 at a certain moment, nor is it a requirement that the welding head 10 maintains this speed throughout the entire welding process of the second welding segment 2. Rather, it is a segment average speed calculated based on the overall movement path length and overall movement time of the second welding segment 2. Since the moving speed of the welding head 10 and the rotation speed of the battery cell 20 may be in an accelerating or decelerating state during the fillet welding stage, this segment average speed can be used as a reference benchmark for judging the low-speed range of the fillet welding stage.

[0058] After the welding point of the welding head 10 moves to the starting point of the second welding segment 2 and begins welding, the battery cell 20 continues to rotate, and the welding head 10 continues to move along the second direction. Since the displacement of the second welding segment 2 with the battery cell 20 is greater than the displacement of the welding head 10 along the second direction, the welding point can move from the starting point to the ending point relative to the battery cell 20 along the second welding segment 2, so that a stable relative welding trajectory is formed between the welding head 10 and the battery cell 20.

[0059] Meanwhile, as mentioned above, the welding head 10 can maintain a constant speed during the welding of the first welding segment 1; however, during the welding of the second welding segment 2, its speed cannot be maintained at a constant speed because it needs to match the rotation of the battery cell. Therefore, the welding stability of the second welding segment 2 is less than that of the first welding segment 1. In this embodiment, the first welding segment 1 is provided with two arc segments 1b that cover the end areas of the rounded fillet welds on both sides of the straight weld, which reduces the length of the second welding segment 2, thereby shortening the multi-axis collaborative welding time. The required lifting compensation, horizontal translation, and battery cell 20 rotation coordination amount of the welding head 10 during the welding of the second welding segment 2 are correspondingly reduced, thereby reducing the impact of multi-axis motion instability on the welding trajectory and energy input, reducing the risk of weld point accumulation, weld offset, and uneven forming, and improving the welding stability of the rounded fillet weld.

[0060] In one embodiment, the starting end of the second welding segment 2 at least partially overlaps with the ending end of the first welding segment 1, so that the starting welding area of ​​the second welding segment 2 partially overlaps with the ending welding area of ​​the first welding segment 1, and / or, the starting end of the first welding segment 1 at least partially overlaps with the ending end of the second welding segment 2, so that the starting welding area of ​​the first welding segment 1 partially overlaps with the ending welding area of ​​the second welding segment 2.

[0061] By ensuring that the starting end of the second welding segment 2 at least partially overlaps with the ending end of the first welding segment 1, the starting welding area of ​​the second welding segment 2 can fall into or cover the already welded area of ​​the first welding segment 1 when the welding head 10 switches from the first welding segment 1 to the second welding segment 2. Therefore, even if there is a slight positional deviation in the welding head 10 during reversal, acceleration, rotation with the battery cell 20, or restarting welding, the risk of unwelded areas forming between the first welding segment 1 and the second welding segment 2 can be reduced, thereby lowering the risk of weld breaks, incomplete welds, or poor sealing.

[0062] Meanwhile, by ensuring that the starting end of the first welding segment 1 and the ending end of the second welding segment 2 at least partially overlap, the continuity of the racetrack-shaped weld seam during the closed-loop welding process can be further guaranteed. In other words, the adjacent first welding segment 1 and second welding segment 2 are transitioned through an overlapping welding area of ​​a certain length or range, thereby improving the fault tolerance of the segmented welding trajectory, ensuring the weld seam is continuous without breaks, and improving the airtightness and overall welding reliability of the racetrack-shaped weld seam of the battery cell 20.

[0063] It should be noted that the aforementioned repeated welding area is artificially set up, unlike the weld point accumulation area generated in the transition section in existing welding methods. Its risk is controllable and the repeated welding path is short, so the risk of weld burn-through is low.

[0064] In one embodiment, before controlling the welding head to move along a first direction through a first welding segment, the method includes: visually identifying the runway-shaped weld to obtain the weld width of the runway-shaped weld and determine the welding trajectory of the welding head.

[0065] The process of visually recognizing the racetrack-shaped weld can be performed using a 3D profilometer. Visual recognition can determine the alignment accuracy between the welding head 10 and the racetrack-shaped weld based on the actual assembly state of the battery cell 20, shell size deviations, top cover position deviations, and weld width variations. Simultaneously, it can improve the accuracy of the position settings for the first welding segment 1, the second welding segment 2, the first overtravel area 3, and the second overtravel area 4, enabling the welding head 10 to more accurately start or stop welding on the first welding segment 1 and the second welding segment 2. This reduces problems such as weld misalignment, missed welds, insufficient weld overlap, or welding points deviating from the weld center due to weld offset, trajectory errors, or workpiece size fluctuations, thereby improving the welding consistency, forming quality, and sealing reliability of the racetrack-shaped weld.

[0066] The second aspect of this application provides a battery cell welding apparatus for performing the battery cell-based racetrack-shaped weld welding method of any of the above claims, and includes: a welding head 10, a clamp, and a rotary drive mechanism; the clamp is used to fix the battery cell 20; the rotary drive mechanism is connected to the clamp and is used to drive the clamp to rotate; the welding head 10 is disposed on one side or above the battery cell 20 and is used to weld the racetrack-shaped weld on the battery cell 20.

[0067] The fixture can hold the casing, top cover, or other positioning parts of the battery cell 20, exposing the racetrack-shaped weld of the battery cell 20 within the welding range of the welding head 10. The rotary drive mechanism can be an R-axis rotary mechanism, which can drive the fixture to rotate around a preset rotation axis. During the welding process, when the welding head 10 welds the straight area in the racetrack-shaped weld, the battery cell 20 can remain relatively stationary or maintain a predetermined posture; when the welding head 10 welds the rounded corner area in the racetrack-shaped weld, the rotary drive mechanism drives the fixture to rotate the battery cell 20, creating relative motion between the welding head 10 and the battery cell 20, thereby allowing the welding point of the welding head 10 to move along the rounded corner area of ​​the racetrack-shaped weld.

[0068] Furthermore, it also includes: a moving mechanism; the moving mechanism includes: an x-axis guide rail and a z-axis guide rail; the z-axis guide rail is slidably disposed on the x-axis guide rail along the x-axis direction; the welding head 10 is slidably disposed on the z-axis guide rail along the z-axis direction.

[0069] Specifically, the x-axis guide rail drives the z-axis guide rail and the welding head 10 mounted on the z-axis guide rail to reciprocate along the x-axis direction. The first and second directions can be two opposite directions along the x-axis. Thus, the welding head 10 can move along the first direction through the first welding segment 1, and can also move along the second direction away from the first overtravel region 3 and towards the second welding segment 2. The z-axis guide rail drives the welding head 10 to move up and down along the z-axis direction to adjust the distance between the welding head 10 and the battery cell 20, ensuring that the welding point of the welding head 10 is maintained in a suitable welding position.

[0070] In a specific welding process, the fixture first fixes the battery cell 20, and the welding head 10 moves along the first direction via the x-axis guide rail, passing through the first welding segment 1 to complete the welding of the first welding segment 1. Subsequently, the welding head 10 continues to move along the first direction into the first overtravel region 3, where welding stops. Afterwards, the x-axis guide rail drives the welding head 10 to move along the second direction to leave the first overtravel region 3, while the rotary drive mechanism drives the fixture to rotate the battery cell 20, causing the welding head 10 to pass through the second welding segment 2 relative to the battery cell 20. When the welding point of the welding head 10 moves to the starting point of the second welding segment 2, the welding head 10 begins welding, and the welding of the second welding segment 2 is completed with the cooperation of the x-axis guide rail, the z-axis guide rail, and the rotary drive mechanism.

[0071] During the welding of the second welding segment 2, the x-axis guide rail can drive the welding head 10 to move along the second direction, the rotary drive mechanism can drive the battery cell 20 to rotate, and the z-axis guide rail can compensate for the height of the welding head 10 according to the change in weld height or welding distance after the battery cell 20 rotates. Therefore, the welding point of the welding head 10 can move stably along the second welding segment 2, reducing weld offset, weld point accumulation, or welding instability caused by the rotation of the battery cell 20, the reversal of the welding head 10, or changes in welding distance.

[0072] With the above structure, the battery cell welding device can use the x-axis guide rail to realize the reciprocating movement of the welding head 10 in the first and second directions, use the z-axis guide rail to adjust the welding distance between the welding head 10 and the battery cell 20, and use the rotary drive mechanism to drive the battery cell 20 to rotate, thereby realizing continuous or segmented welding of the straight and rounded corner areas in the racetrack-shaped weld. This structure can cooperate with the first overtravel area 3 and the second overtravel area 4 to enable the welding head 10 to accelerate, decelerate, change direction, or adjust its position in a non-welding state, reducing the situation where the welding head 10 starts or changes direction at low speed within the effective welding area of ​​the racetrack-shaped weld, thereby improving the welding quality and sealing reliability of the racetrack-shaped weld of the battery cell 20.

[0073] The above are merely preferred embodiments of this application and are not intended to limit the present invention. Although this application has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for welding racetrack-shaped seams based on battery cells, characterized in that, The runway-shaped weld seam includes multiple adjacent first and second weld sections; The welding method includes: The welding head is controlled to move along a first direction past the first welding segment to weld the first welding segment; The welding head is controlled to move along the first direction into the first overtravel region, wherein when it is in the first overtravel region, the welding point of the welding head separates from the runway-shaped weld and the welding head stops welding; The welding head is controlled to move along a second direction to leave the first overtravel region, the second direction being opposite to the first direction; The cell is controlled to rotate so that the welding head, which moves along the second direction, passes through the second welding section relative to the cell, and the welding head begins welding when the welding point of the welding head moves to the starting point of the second welding section.

2. The method for welding racetrack-shaped seams based on battery cells according to claim 1, characterized in that, Before the controlled welding head moves along the first direction past the first welding segment, the following steps are included: The welding head is controlled to move along the first direction to leave the second overtravel area, and when the welding point of the welding head moves to the starting point of the first welding segment, the welding head is controlled to start welding, wherein when it is in the second overtravel area, the welding point of the welding head separates from the runway-shaped weld and the welding head stops welding. The control of the cell rotation, such that the welding head moving in the second direction passes the second welding segment relative to the cell, includes: The welding head is controlled to move along the second direction into the second overtravel region.

3. The method for welding racetrack-shaped seams based on battery cells according to claim 2, characterized in that, During the process of controlling the welding head to move along the second direction to leave the first overtravel area, the welding head accelerates, and when the welding point of the welding head moves to the starting point of the second welding segment, the welding head accelerates to a second preset speed.

4. The method for welding racetrack-shaped seams based on battery cells according to claim 3, characterized in that, The second preset speed is greater than the average movement speed of the second welding segment; The average speed is calculated based on the moving path and duration of the second welding segment.

5. The method for welding racetrack-shaped seams based on battery cells according to claim 1, characterized in that, The starting end of the second welding segment at least partially overlaps with the ending end of the first welding segment, such that the starting welding area of ​​the second welding segment partially overlaps with the ending welding area of ​​the first welding segment, and / or, The starting end of the first welding segment and the ending end of the second welding segment at least partially overlap, so that the starting welding area of ​​the first welding segment and the ending welding area of ​​the second welding segment partially overlap.

6. The method for welding racetrack-shaped seams based on battery cells according to any one of claims 1 to 5, characterized in that, The first welding segment includes interconnected straight line segments and arc segments; The straight segment covers the entire length of a straight weld in the racetrack-shaped weld; The arc segment covers a portion of the length of a rounded fillet weld of the racetrack-shaped weld; The second weld segment covers a portion of the length of a fillet weld of the racetrack-shaped weld.

7. The method for welding racetrack-shaped seams based on battery cells according to claim 6, characterized in that, The first welding segment includes one straight segment and two circular arc segments; The two arc segments are respectively located at both ends of the straight line segment.

8. The method for welding racetrack-shaped seams based on battery cells according to claim 1, characterized in that, Before the controlled welding head moves along the first direction past the first welding segment, the following steps are included: Visual recognition is performed on the runway-shaped weld to obtain the weld width and determine the welding trajectory of the weld joint.

9. A battery cell welding device, characterized in that, For performing the cell-based racetrack-shaped weld welding method as described in any one of claims 1 to 8, and comprising: a welding head (10), a fixture, and a rotary drive mechanism; The clamp is used to fix the battery cell (20); The rotary drive mechanism is connected to the clamp and is used to drive the clamp to rotate; The welding head (10) is used to weld the racetrack-shaped weld on the battery cell (20).

10. The cell welding apparatus according to claim 9, characterized in that, Also includes: Mobile mechanism; The moving mechanism includes: an x-axis guide rail and a z-axis guide rail; The z-axis guide rail is slidably mounted on the x-axis guide rail along the x-axis direction; The welding head (10) is slidably mounted on the z-axis guide rail along the z-axis direction.

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