A method and system for improving battery side weld corners and applications

Abstract

The present application relates to the technical field of laser welding, and particularly relates to a method and system for improving battery side welding corners and application. The method comprises the following steps: obtaining structural parameters of a corner to be welded of a battery and process parameters of laser welding; when laser welding travels to a corner welding area of the battery, based on the structural parameters and the process parameters, calculating a height difference H of a corner surface to be welded corresponding to a current welding position and a side straight line surface to be welded in real time; and based on the height difference H calculated in real time, adjusting a height position of a laser welding gun head in real time, so that a relative height of a laser exit point and the surface to be welded is always kept constant during welding, and a welding defocusing amount is kept consistent. The present application can adjust the height position of the laser welding gun head in real time, so that the relative height of the laser exit point and the surface to be welded is always kept constant during welding, and the welding defocusing amount is kept consistent, to realize continuous welding with high quality and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of laser welding technology, and more specifically to a method, system, and application for improving the corner welding of battery sides. Background Technology

[0002] In current battery manufacturing processes, side welding primarily employs laser welding technology. Laser welding has become the mainstream process for battery packaging due to its advantages such as high energy density, small heat-affected zone, fast welding speed, and ease of automation integration. In actual production, battery side welding typically employs two methods: one where the battery is stationary and the laser welding head sequentially welds the four sides of the battery in straight lines; the other where the battery rotates while the laser welding head remains relatively fixed, achieving continuous welding around the battery's perimeter. Regardless of the method used, the welding of the battery corners (i.e., the R-corner area) remains a challenging and vulnerable point in the process.

[0003] In existing technologies, welding at battery corners typically relies on extending or repeating the welding of straight sections. Specifically, after the laser welding head completes a straight weld on one side, it moves to the corner area, changing the welding direction or rotating the battery to cover the corner area with laser light. Because the corner area has a rounded transition structure, there is a significant height difference between the surface to be welded (i.e., the seam between the cover and the casing) and the surface to be welded on the straight section of the side. This height difference is mainly determined by the geometry of the battery casing: the casing sidewall is a vertical plane, while the corner has a rounded transition. The height change formed by the intersection of the cover plane and the casing sidewall results in the welding surface in the corner area being lower than the welding surface of the straight section.

[0004] The height difference directly affects the defocusing amount during laser welding. Defocusing amount refers to the positional deviation of the laser focus relative to the surface to be welded, and it is one of the key parameters affecting weld quality. Excessive or insufficient defocusing amount can lead to inconsistent weld penetration and width, and even defects such as incomplete fusion, burn-through, and spatter. In existing processes, because the height of the welding head is fixed, it is impossible to adjust it in real time according to the height changes in corner areas, resulting in a difference in defocusing amount between corner areas and straight sections, thus affecting weld quality.

[0005] Furthermore, to ensure coverage of corner areas, existing technologies often employ repeated welding, meaning that after welding one side, the corner area is welded a second or multiple times. While this approach mitigates the impact of height differences to some extent, it introduces new problems: repeated welding can easily lead to excessive localized heat input, causing material overheating, coarse grains, expansion of the heat-affected zone, and even weld cracks or cover plate deformation. Simultaneously, the microstructure and mechanical properties of the repeatedly welded area differ from those of the straight weld section, resulting in discontinuous and uneven weld appearance, affecting product consistency and aesthetics. Moreover, repeated welding increases welding time, reduces production efficiency, and is detrimental to large-scale automated production.

[0006] In summary, existing battery side welding processes suffer from the following main problems in corner areas: First, the height difference caused by the geometric structure is not effectively compensated, and changes in defocusing affect welding quality; second, repeated welding not only fails to fundamentally solve the height difference problem but also introduces new problems such as uneven heat input, microstructure differences, and low efficiency. These problems severely restrict the improvement of battery sealing quality and manufacturing efficiency, becoming a key focus and challenge in optimizing battery manufacturing processes. Summary of the Invention

[0007] To overcome the problems of poor welding at battery corners in the existing technology, the present invention aims to provide a method, system, and application for improving battery side welding corners. This method can adjust the height of the laser welding torch in real time, ensuring that the relative height between the laser emission point and the surface to be welded remains constant during the welding process, maintaining consistent defocusing, and thus achieving high-quality, high-efficiency continuous welding.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a method for improving the side welding corner of a battery, comprising the following steps: Obtain the structural parameters of the corner of the battery to be welded and the process parameters of laser welding; When the laser welding reaches the corner welding area of ​​the battery, the height difference H between the corner welding surface and the side straight section welding surface corresponding to the current welding position is calculated in real time based on the structural parameters and process parameters. Based on the height difference H calculated in real time, the height position of the laser welding gun head is adjusted in real time to keep the relative height between the laser emission point and the surface to be welded constant during the welding process, thus maintaining a consistent amount of defocusing during welding.

[0009] As a preferred embodiment of the present invention, the structural parameters include the radius of curvature R of the battery corner and the cumulative angle a of the laser welding gun head passing through the battery corner during welding; the process parameters include the welding speed V of laser welding and the total cumulative welding time S from entering the corner point to ending the corner.

[0010] As a preferred embodiment of the present invention, the height difference H is calculated using the following formula: H = R - cot(a) × V × S.

[0011] As a preferred embodiment of the present invention, the cumulative angle α is calculated using the following formula: a=arctan .

[0012] As a preferred embodiment of the present invention, the step of adjusting the height position of the laser welding gun head in real time based on the height difference H calculated in real time includes: The calculation is performed iteratively with a fixed micro-element period t. Each micro-element period t calculates a corresponding height difference H based on the current accumulated total welding time S. The difference ΔH between the H values ​​of two adjacent micro-element periods t is the real-time downward adjustment height of the laser welding gun head.

[0013] As a preferred embodiment of the present invention, the battery is placed horizontally, and the laser emission direction of the laser welding gun head is perpendicular to the horizontal placement direction.

[0014] As a preferred embodiment of the present invention, the laser welding process is a continuous welding process.

[0015] In a second aspect, the present invention provides a battery-side welding system for implementing the method, comprising: Laser welding gun head, used to emit laser to weld the sides and corners of batteries; The parameter acquisition module is used to acquire the structural parameters of the corner of the battery to be welded and the process parameters of laser welding. A position adjustment mechanism, connected to the laser welding gun head, is used to adjust the displacement distance of the laser welding gun head in the horizontal and vertical directions; The control system, electrically connected to the parameter acquisition module and the position adjustment mechanism, is used to calculate in real time the height difference H between the corner surface to be welded and the side straight section surface to be welded corresponding to the current welding position, and adjust the height position of the laser welding gun head in real time according to the height difference H calculated in real time, so that the relative height between the laser emission point and the surface to be welded remains constant during the welding process, and the welding defocusing amount remains consistent.

[0016] As a preferred embodiment of the present invention, the real-time adjustment is automatically calculated and executed by the control system according to a preset program, and the control system includes a programmable logic controller (PLC).

[0017] As a preferred embodiment of the present invention, the battery side welding system further includes a battery rotation mechanism, and the control system is used to synchronously control the continuous rotation of the battery and the continuous emission of the laser, so as to realize uninterrupted continuous operation of full-circumference battery sealing welding.

[0018] The third invention provides an application of the method for improving the side welding corner of the battery as described above in the quality control of battery manufacturing.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention overcomes the limitation of fixed welding head height in traditional battery side welding processes. By constructing a mathematical model based on kinematics and geometry (H=R-cot(a)×V×S), it achieves for the first time real-time quantitative calculation of the height difference H between the corner welding surface and the straight side welding surface. The control system performs high-frequency iterative calculations with a micro-element period t to accurately determine the required compensation amount ΔH in each tiny time interval, and drives the position adjustment mechanism to adjust the height of the laser welding gun head in real time. This dynamic compensation mechanism ensures that the relative height between the laser emission point and the welding surface remains constant throughout the entire welding process from the straight section to the corner area, thereby strictly locking the welding defocus amount to the optimal process parameter value. This fundamentally solves the problem of defocus amount deviation caused by height difference, ensuring the high consistency of weld penetration, weld width, and heat-affected zone throughout the entire circumference of the battery, and significantly improving the mechanical properties and sealing reliability of the welded joint.

[0020] 2. This invention abandons the inefficient traditional process that relies on straight-line extensions or repeated welding to cover corners. By continuously and dynamically adjusting the height in the corner area, uninterrupted laser welding is achieved. The battery can rotate at a uniform speed, while the laser welding gun head remains relatively stationary or moves in coordination with the horizontal direction, performing real-time compensation only in the height direction, truly achieving uninterrupted, continuous operation for full-circumference battery sealing. This new mode of one-time welding and full-process compensation directly eliminates the repeated welding time or idle travel time added by corner treatment in traditional processes. For mass-production battery manufacturing lines, it can significantly shorten the cycle time per station, improve equipment uptime, and reduce unit manufacturing costs.

[0021] 3. Due to the constant decoking amount and uniform heat input during welding, the weld seam in the corner area no longer suffers from overheating, collapse, spatter, or messy fish-scale patterns caused by repeated welding. It also avoids poor fusion due to insufficient heat input. The weld seam exhibits a natural and smooth geometric transition from the straight section to the corner, with a flat surface and fine texture, resulting in a significant leap in appearance quality. Metallographic analysis shows that the weld seam structure in the corner area is uniform and consistent with that in the straight section, without the formation of coarse grains or abnormal structures, thus eliminating the risk of stress concentration and fatigue failure caused by differences in microstructure. After applying this invention, the yield rate of battery sealing welding can be increased from approximately 92% in the prior art to over 99.5%, significantly reducing scrap losses caused by welding defects.

[0022] 4. In traditional processes, minute dimensional deviations in the battery casing and cover plate, as well as inconsistencies in assembly gaps, exacerbate height differences at corners, leading to fluctuations in welding quality. This invention employs a real-time calculation and feedback mechanism based on time (S) and speed (V), essentially providing proactive and intelligent control of the welding process. It does not rely on absolute mechanical alignment precision but rather automatically adapts to geometric changes in the corner area through algorithms, proactively compensating for height differences. This gives the production line a certain degree of tolerance for the consistency of incoming battery materials and the positioning accuracy of fixtures, reduces the difficulty of equipment debugging and maintenance, and improves the operational stability and process robustness of the entire production line. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the welded battery side and corner of the present invention.

[0024] Figure 2 This is a schematic diagram of the structural parameters at the corner of the battery in this invention.

[0025] In the diagram, 1-cover plate; 2-battery casing; 3-corner; 4-laser welding gun head. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the method and system for improving battery side welding corners proposed by this invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Any simple modifications, equivalent substitutions, or improvements made by those skilled in the art based on the embodiments of this invention without inventive effort fall within the protection scope of this invention.

[0027] Example 1 This embodiment provides a method for improving the side welding corner of a battery, particularly applicable to the side welding sealing process of a square power battery casing 2 and a cover plate 1, to solve the problem of poor welding quality caused by the height difference between the battery corner 3 (R corner) area and the straight side segment. Figure 1 As shown, the method mainly includes the following steps: Step S1: Obtain the structural parameters of the corner of the battery to be welded and the process parameters of laser welding.

[0028] The structural parameters are physical quantities describing the geometric characteristics of the battery corners, including at least the radius of curvature R of the battery corners. In the field of battery manufacturing, different battery models have different corner designs. The radius of curvature R is a constant and can be obtained in advance through design drawings or high-precision measuring equipment (such as image measuring instruments and laser profilometers). Furthermore, as... Figure 2 As shown, the structural parameters also include the cumulative angle 'a' of the battery corners that the laser welding gun head 4 needs to traverse during the welding process. The cumulative angle 'a' is calculated using the following formula: a=arctan .

[0029] Meanwhile, the acquired process parameters are key variables set when the laser welding machine performs welding operations, including at least the welding speed V and welding time S. Welding speed V is the moving speed of the laser welding torch relative to the battery workpiece, measured in mm / s. Welding time S refers to the total welding time accumulated from the laser welding torch entering the corner point to its exit from the corner. These parameters are preset by the host computer or control system before welding, or dynamically adjusted based on feedback during the welding process.

[0030] Step S2: When the laser welding reaches the corner welding area of ​​the battery, the height difference H between the corner surface to be welded and the side straight section surface to be welded is calculated in real time based on the structural parameters and process parameters.

[0031] like Figure 1 and Figure 2 As shown, because the battery casing has a rounded transition at the corner, and the cover plate plane intersects with the casing sidewall plane, the height of the surface to be welded at the corner (i.e., the surface at the joint between the cover plate and the casing) is slightly lower than the surface to be welded on the straight side section. This height difference H is the root cause of the change in defocusing amount and poor welding at the corner.

[0032] In this embodiment, a mathematical model based on kinematics and geometry was constructed to accurately calculate the height difference H. Please refer to [the relevant documentation / reference]. Figure 2The radius of curvature of the battery corner is R. Within a certain time period, the laser welding torch moves at a speed V, and the distance traveled is D = V × S. The height difference between the corner surface to be welded and the straight section surface to be welded is H = R - cot(a) × D. Based on these two formulas, the program can be set so that when the speed is set to V, the distance traveled is obtained by simulating the change in time S, thereby calculating the height difference H = R - cot(a) × V × S between the corner surface to be welded and the straight section surface to be welded corresponding to the current welding position.

[0033] Step S3: Adjust the height position of the laser welding gun head in real time according to the height difference H calculated in real time.

[0034] Specifically, the control system (such as a programmable logic controller (PLC) converts the H value calculated in real time in step S2 into control commands for the servo driver, driving the Z-axis (height direction) servo motor connected to the laser welding gun head to move the gun head downwards. Specifically, iterative calculations are performed with a fixed micro-element period t. Each micro-element period t calculates a corresponding height difference H based on the current accumulated total welding time S. The difference ΔH between the H values ​​of two adjacent micro-element periods t is the downward adjustment height of the laser welding gun head. Through this closed-loop or semi-closed-loop real-time adjustment, it is ensured that the relative height between the laser emission point and the surface to be welded remains constant throughout the welding of the entire corner area, thereby stabilizing the welding defocusing amount at the optimal value (e.g., +4mm) and maintaining the consistency of the welding process. In this embodiment, the battery is placed flat, and the laser emission direction of the laser welding gun head is perpendicular to the flat placement direction, which is consistent with... Figure 1 The positional relationships shown are consistent. The entire welding process, including straight sections and corner sections, is continuous welding without the need to stop or slow down at corners, greatly improving welding efficiency.

[0035] Example 2 This embodiment provides a battery side welding system for implementing the method described in Embodiment 1. Please refer to... Figure 1 and Figure 2 The system includes: a laser welding torch head, a parameter acquisition module, a position adjustment mechanism, and a control system.

[0036] Laser welding torches emit high-energy-density laser beams to weld the straight sections and corner areas of a battery. The torch may contain optical components such as focusing lenses and collimating lenses to focus the laser beam transmitted from the fiber optic cable into a very small spot.

[0037] The parameter acquisition module is electrically connected to the control system and is used to acquire and store the structural parameters of the corner to be welded on the battery (such as the radius of curvature R and the cumulative corner angle a) and the laser welding process parameters (such as the welding speed V). These parameters can be manually entered by the operator through a human-machine interface (HMI) or automatically acquired by reading a preset recipe database.

[0038] The position adjustment mechanism is mechanically connected to the laser welding torch head and is typically a high-precision XYZ three-axis motion platform driven by a servo motor. It includes at least a drive unit for adjusting the torch head's displacement in the horizontal (X-axis, Y-axis) and vertical (Z-axis) directions. The displacement accuracy in the Z-axis direction needs to reach the micrometer level to meet the precise compensation requirements for the height difference H.

[0039] The control system is the core of the entire system, electrically connected to the parameter acquisition module and the servo drive of the position adjustment mechanism. It contains a programmable logic controller (PLC). The control system has pre-written and stored core control algorithm programs such as H=R-cot(a)×V×S. During the welding process, when the system determines that the laser welding torch has entered a corner area, the control system begins to execute this algorithm. It iteratively calculates at fixed periods (i.e., infinitesimal time t), calculating a corresponding compensation height H based on the current accumulated time S in each period, and then immediately sending a pulse command to the Z-axis servo drive to move the torch downwards by ΔH (the difference between the H values ​​of two adjacent infinitesimal periods). Through this high-frequency real-time calculation and adjustment, the amount of defocusing during welding is kept constant throughout the entire process.

[0040] As a further optimization of this embodiment, the battery side welding system also includes a battery rotation mechanism electrically connected to the control system. This rotation mechanism clamps the battery and rotates it around its central axis. The control system synchronously controls the continuous rotation of the battery and the continuous emission of the laser. For example, when performing full-circumference welding of a square battery, the battery can be set to rotate at a uniform speed of 360° while the laser welding torch remains horizontal. Real-time compensation along the Z-axis is used to track the defocusing fluctuations caused by changes in corner height, thereby achieving uninterrupted, high-efficiency continuous full-circumference battery sealing.

[0041] Application examples This application example applies the method of Example 1 and the system of Example 2 to actual battery manufacturing quality control. On a production line for a square aluminum-cased power battery, the technical solution of this invention is used for sealing welding. First, the radius of curvature R of the battery corner is measured to be 5mm, the welding speed V is set to 150mm / s, and the micro-element time t is set to 2ms. During the welding process, when the laser head enters the first corner, the control system calculates according to the formula H=5-cot(a)×150×S. After welding, the weld is inspected for quality. The results show that the weld penetration and width in the corner area are basically consistent with those in the straight side area, the metallographic structure is uniform, and there are no defects such as over-melting, collapse, or insufficient welding. The weld appearance is smooth and the transition is natural. The yield rate has increased from the original 92% to over 99.5%, and the welding cycle time for a single battery has been shortened by 20%, fully verifying the effectiveness and superiority of this invention.

[0042] In summary, this invention creatively solves the long-standing problem of defocusing variations caused by geometric structures in battery side welding processes by real-time monitoring and compensation of the height difference in the welding area at battery corners. This achieves high-quality, high-efficiency continuous welding, which is of significant importance for advancing battery manufacturing technology. The above descriptions are merely preferred embodiments of this invention and are not intended to limit the invention. Those skilled in the art can make various improvements and modifications without departing from the spirit and principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

[0043] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving the side welding corner of a battery, characterized in that, Includes the following steps: Obtain the structural parameters of the corner of the battery to be welded and the process parameters of laser welding; When the laser welding reaches the corner welding area of ​​the battery, the height difference H between the corner welding surface and the side straight section welding surface corresponding to the current welding position is calculated in real time based on the structural parameters and process parameters. Based on the height difference H calculated in real time, the height position of the laser welding gun head is adjusted in real time to keep the relative height between the laser emission point and the surface to be welded constant during the welding process, thus maintaining a consistent amount of defocusing during welding.

2. The method for improving the battery side welding corner according to claim 1, characterized in that, The structural parameters include the radius of curvature R of the battery corner and the cumulative angle a that the laser welding gun head travels through the battery corner during welding; the process parameters include the laser welding speed V and the total cumulative welding time S from entering the corner point to ending the corner.

3. The method for improving the battery side welding corner according to claim 2, characterized in that, The height difference H is calculated using the following formula: H = R - cot(a) × V × S.

4. The method for improving the battery side welding corner according to claim 2 or 3, characterized in that, The cumulative angle α is calculated using the following formula: a=arctan 。 5. The method for improving the battery side welding corner according to claim 1, characterized in that, The step of adjusting the height position of the laser welding gun head in real time based on the height difference H calculated in real time includes: The calculation is performed iteratively with a fixed micro-element period t. Each micro-element period t calculates a corresponding height difference H based on the current accumulated total welding time S. The difference ΔH between the H values ​​of two adjacent micro-element periods t is the real-time downward adjustment height of the laser welding gun head.

6. The method for improving the battery side welding corner according to claim 1, characterized in that, The battery is placed horizontally, and the laser emission direction of the laser welding gun head is perpendicular to the horizontal placement direction.

7. A battery side welding system for implementing the method according to any one of claims 1-6, characterized in that, include: Laser welding gun head, used to emit laser to weld the sides and corners of batteries; The parameter acquisition module is used to acquire the structural parameters of the corner of the battery to be welded and the process parameters of laser welding. A position adjustment mechanism, connected to the laser welding gun head, is used to adjust the displacement distance of the laser welding gun head in the horizontal and vertical directions; The control system, electrically connected to the parameter acquisition module and the position adjustment mechanism, is used to calculate in real time the height difference H between the corner surface to be welded and the side straight section surface to be welded corresponding to the current welding position, and adjust the height position of the laser welding gun head in real time according to the height difference H calculated in real time, so that the relative height between the laser emission point and the surface to be welded remains constant during the welding process, and the welding defocusing amount remains consistent.

8. The battery side welding system according to claim 7, characterized in that, The real-time adjustment is automatically calculated and executed by the control system according to a preset program, and the control system includes a programmable logic controller (PLC).

9. The battery side welding system according to claim 7, characterized in that, The battery side welding system also includes a battery rotation mechanism. The control system is used to synchronously control the continuous rotation of the battery and the continuous emission of the laser, so as to realize uninterrupted continuous operation of full-circumference battery sealing.

10. The application of a method for improving battery side welding corners according to any one of claims 1-6 in battery manufacturing quality control.

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