Tab welding method and system

Abstract

The present application relates to a tab welding method and system, comprising: a process of directly laser welding to the top cover pole after the tabs are gathered by ultrasonic welding, measuring the current temperature of the workpiece welding surface in real time before welding each weld, using the laser welding energy equation and the tab melting heat equation to backstep the laser absorption rate of each weld, setting differentiated welding parameters for each weld according to the absorption rate ratio relationship of adjacent welds, preferably keeping the power unchanged and increasing the subsequent weld speed, and correcting based on the welding feedback data. The present application makes the fusion depth of each weld consistent, eliminates appearance defects such as burst points and splashes, and significantly improves the welding yield and process stability.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing technology, specifically to a method and system for electrode tab welding. Background Technology

[0002] In the assembly process of lithium-ion batteries, reliably connecting the tabs of the battery cell to the terminal posts of the top cover is one of the key steps. Currently, an efficient connection method is to first pre-weld multiple layers of tabs (especially copper tabs) together using ultrasonic welding to form a single unit, and then use laser welding to directly weld the gathered tabs to the terminal posts of the top cover (i.e., the "tab direct connection welding" process). Figure 1 As shown. This process simplifies the workflow and helps reduce battery internal resistance.

[0003] In actual production, it has been found that for the positive or negative electrode of a battery cell, multiple parallel laser solder marks (e.g., two) are typically welded sequentially onto the tab. However, due to the small spacing between adjacent solder marks, existing processes generally employ a sequential welding method of "welding the already welded marks first, then welding the marks to be welded." During this process, the heat generated by the already welded marks is rapidly conducted and accumulated through the highly thermally conductive copper tab and post, resulting in the initial temperature of the welding plane when welding the mark to be welded being much higher than that of the first mark. Taking copper as an example, its thermal conductivity is as high as approximately 400 W / (m·K), and its absorption rate of laser light increases significantly with increasing temperature.

[0004] This heat accumulation effect can lead to a series of quality problems: 1. Significant Differences in Welding Depth: Under the same laser welding parameters (such as power and speed), the copper material to be welded has a higher initial temperature and a higher laser absorption rate, resulting in a significantly greater penetration depth than the already welded weld. Existing experimental data shows that, under the same parameters, the difference in penetration depth between two welds can even exceed 0.5 mm.

[0005] 2. Inconsistent appearance quality: The weld not yet welded may absorb too much energy, leading to defects such as bursts and spatter; while the welded weld may have insufficient energy, resulting in shallow penetration. It is difficult to balance the process parameters between the two welds, directly affecting the welding yield and consistency.

[0006] Therefore, how to overcome the quality differences of continuous weld marks caused by heat accumulation and achieve stable and uniform welding results during the direct-connection laser welding process is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] In view of this, embodiments of the present invention provide a tab welding method and system to solve the technical problems in the existing tab direct-connection laser welding process, which are caused by the high thermal conductivity of the tab material, continuous welding heat accumulation leading to a large difference in the penetration depth between the desired weld and the already welded weld, a high rate of appearance defects, and difficulty in balancing process parameters.

[0008] This invention proposes a method for welding electrode tabs, comprising the following steps: During the process of sequentially performing multiple laser weldings on the electrode tabs that have been gathered by ultrasonic welding to form weld marks, the current temperature of the workpiece surface connected to the electrode tab is obtained before each weld mark is welded. For each weld mark to be welded starting from the second weld mark, the laser absorption rate of the current weld mark and the welded marks is calculated by reverse calculation using the laser welding energy equation and the thermophysical parameters of the tab material. Based on the laser absorption rates of the weld marks to be welded and the weld marks already welded, the relationship between the laser welding parameters is derived. Based on the relationship of the laser welding parameters, laser welding parameters are set for each weld mark to be welded, and welding is performed using the laser welding parameters.

[0009] Furthermore, the laser absorptivity of the current weld mark to be welded and the weld mark already welded are calculated using a backward calculation method based on the laser welding energy equation and the thermophysical parameters of the tab material. Specifically: Calculate the laser absorption rate of the current solder mark to be soldered and the solder mark already soldered according to the following formulas: According to the laser welding energy equation: And the equation for the heat of fusion based on the thermophysical parameters of the tab material: Combining the two equations, we obtain the laser absorption rate of the corresponding solder mark: in, For welding energy; The laser welding power corresponding to the solder mark; This corresponds to the laser welding time of the solder mark; This corresponds to the laser absorption rate of the solder mark; The specific heat capacity of the tab material; This refers to the quality of the molten metal corresponding to the solder mark; This is the difference between the melting point of the tab material and the current temperature of the corresponding soldering surface.

[0010] Furthermore, the mass of the molten metal is calculated using the planar area of ​​the solder mark, the laser penetration depth, and the density of the tab material: in, The mass of the molten metal; The area of ​​the solder mark; The total penetration depth of laser welding is denoted by , which is the sum of the electrode lug thickness and the penetration depth within the electrode post. The density of the tab material.

[0011] Furthermore, the welding time is calculated from the total length of the laser beam scanning path and the welding speed: in, For welding time; Total welding length; This refers to the laser welding speed.

[0012] Furthermore, the total penetration depth of the laser welded needle with weld marks is the penetration depth actually measured after welding; The total penetration depth of the laser welding of the weld mark to be welded is the penetration depth obtained according to a preset correspondence, which is the correspondence between laser welding power, welding speed, temperature and penetration depth.

[0013] Furthermore, the laser welding parameters include laser welding power and laser welding speed. The laser welding parameters are derived based on the laser absorptivity of the weld mark to be welded and the weld mark already welded, specifically as follows: in, The laser welding power of the weld mark. The laser welding power is the value of the desired solder mark. The laser welding speed of the welded solder mark. The laser welding speed for the desired solder mark. The laser absorption rate of the solder mark is the value of the welded area. The laser absorption rate of the solder mark to be soldered. , , The melting point of the tab material. The surface temperature of the workpiece before welding is indicated by the weld mark. The surface temperature of the workpiece before welding is required.

[0014] Furthermore, the laser welding power of the desired weld mark is consistent with the laser power of the already welded weld mark, and the laser welding parameters are set to the laser welding speed of the desired weld mark. Based on the relationship of the laser welding parameters, laser welding parameters are set for each desired weld mark, specifically as follows: in, The welding speed for the desired solder joint; The welding speed of the welded solder marks; The laser absorption rate of the solder mark; The laser absorption rate of the solder mark to be soldered; The difference between the melting point of the tab material and the surface temperature of the workpiece before welding the solder mark; The difference between the melting point of the tab material and the surface temperature of the workpiece before welding is called.

[0015] The present invention also proposes an electrode welding system, comprising: An ultrasonic welding device is used to weld multiple layers of electrode tabs together into one piece. A temperature measuring device is used to measure the current temperature of the workpiece welding surface in real time before each laser welding stamp and output the temperature data. A laser welding device is used to perform laser welding on each weld mark, and supports setting the laser welding power and laser welding speed individually for each weld mark; The control device is connected to the temperature measuring device and the laser welding device respectively. It is used to receive the welding surface temperature data of each weld mark, calculate the laser absorptivity of each weld mark by reverse calculation based on the laser welding energy equation and the thermophysical parameters of copper, and perform differential compensation for the laser welding parameters line by line based on the difference in the laser absorptivity between each weld mark.

[0016] The specific method by which the control device performs differentiated compensation for the laser welding parameters of each weld mark includes: for each weld mark to be welded starting from the weld mark to be welded, selecting at least one weld mark from the weld marks preceding the weld mark to be welded as a weld mark; obtaining the laser absorptivity of the weld mark to be welded and the laser absorptivity of the weld mark to be welded; calculating the welding power compensation value or welding speed compensation value of the weld mark to be welded relative to the weld mark to be welded according to the principle of energy conservation based on the ratio between the laser absorptivity of the weld mark to be welded and the laser absorptivity of the weld mark to be welded; and setting the laser welding power or laser welding speed of the weld mark to be welded based on the welding power compensation value or welding speed compensation value.

[0017] Furthermore, the aforementioned welded stamp is the preceding welded stamp immediately adjacent to the stamp to be welded; or, the welded stamp is one selected from the N preceding welded stamps immediately adjacent to the stamp to be welded, where N is an integer greater than or equal to 2.

[0018] The present invention also proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the tab welding method as described above.

[0019] The present invention also proposes an electronic device, comprising: processor; Memory for storing the executable instructions of the processor; The processor is configured to perform the tab welding method described above by executing the executable instructions.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention establishes a laser absorptivity backward model based on real-time feedback of welding surface temperature. It incorporates the actual difference in weld penetration and the thermophysical parameters of copper material into the calculation, quantitatively obtaining the ratio of laser absorptivity between successive welds. Based on this, it independently sets differentiated welding speeds or welding power for each weld. This approach changes the existing process where all welds use the same parameters, effectively compensating for the increased absorptivity caused by rapid heat conduction and significant heat accumulation between the copper tabs and posts. This results in multiple welds welded sequentially exhibiting consistent penetration, width, and appearance quality, significantly reducing welding effect differences caused by sequential welding and improving the uniformity and reliability of the tab-connected structure.

[0021] 2. This invention avoids the process risks that may arise from simply reducing power, such as difficulty in forming the initial molten pool and discontinuous welds, by maintaining the welding power constant and only increasing the welding speed of subsequent weld stamps. Simultaneously, it effectively suppresses the problem of excess energy caused by heat accumulation, reducing appearance defects such as bursts, spatter, and overheating. This solution not only improves the first-pass yield of direct-connect laser welding of electrode tabs but also enhances the tolerance and stability of the process window, providing reliable technical support for the large-scale production of high-power, multi-layer copper electrode tabs. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of an existing electrode tab direct connection welding structure; used to show the positional relationship of the top cover, electrode post, electrode tab, ultrasonic welding mark, and laser welding mark; Figure 2 This is a flowchart of a method for welding electrode tabs according to the present invention; Figure 3 This is a structural block diagram of a tab welding system according to the present invention; Figure 4 This is a flowchart of the laser absorption rate back-calculation and velocity compensation calculation of the present invention; Figure 5 This is a schematic diagram of the rectangular filling welding trajectory in this invention.

[0024] Reference numerals: ①-Top cover; ②-Electrical post; ③-Electrical tab; ④-Ultrasonic welding mark; ⑤-Electrical tab laser welding mark. Detailed Implementation

[0025] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0026] This invention provides a method and system for welding electrode tabs. This process is particularly suitable for scenarios where copper electrode tabs are brought together by ultrasonic welding and then directly welded to the top cover electrode post by laser. It can also be extended to multi-pass sequential laser welding processes for other high thermal conductivity metals (such as aluminum and silver alloys), as well as precision connection manufacturing fields that require consistency control of multiple weld seams under heat accumulation conditions.

[0027] In actual mass production, direct-connect laser welding of copper tabs has long faced severe challenges, including significant heat accumulation in subsequent welds due to the extremely high thermal conductivity of copper (approximately 400 W / (m·K)), nonlinear increase in laser absorptivity with increasing temperature, and penetration depth differences exceeding 0.5 mm under the same welding parameters. Traditional processes use the same laser power and welding speed for all welds, which cannot compensate for absorptivity drift caused by temperature field changes. While simply reducing the power of subsequent welds can decrease penetration depth, it is prone to defects such as weld beads and incomplete welds due to insufficient energy in the initial stage, which cannot form a stable molten pool. Existing offline trial-and-error optimization methods rely on a large number of experiments and lack quantitative criteria, making it impossible to respond online to batch fluctuations in the current temperature of the workpiece welding surface. Furthermore, conventional open-loop welding systems lack temperature feedback and parameter self-adjustment capabilities, resulting in one weld having a good appearance while adjacent welds exhibit defects such as bursts and spatter. The process window is narrow, and yield and consistency are severely restricted. The aforementioned shortcomings make it difficult for existing technologies to simultaneously meet the four core requirements of high-efficiency, multi-layer copper tab mass production: accuracy of heat accumulation compensation, stability of the molten pool, quantitative adjustment of parameters, and closed-loop adaptability. Consequently, both welding quality and production efficiency are difficult to improve further. The technical solution provided by the present invention will be described in detail below with reference to specific embodiments.

[0028] Example 1 This embodiment provides a method for welding electrode tabs, applied to the process of directly laser welding the electrode tabs to the top cover electrode post after ultrasonic welding. This embodiment uses copper electrode tabs as the implementation object. Due to the heat accumulation effect caused by the high thermal conductivity of copper, traditional welding with the same parameters makes it difficult to achieve consistent weld penetration depth in successive welds. This invention obtains the current temperature of the workpiece welding surface before each weld, and uses the laser welding energy equation and copper thermophysical parameters to deduce the laser absorptivity of each weld. Starting from the weld to be welded, it derives the welding parameter compensation amount based on the ratio of the absorptivity of previously welded welds (prioritizing the data from the previous adjacent weld), outputting differentiated welding power or speed for each weld, thus making the weld penetration depth more consistent. The core process of this method is as follows: Figure 2 As shown in the attached figures, the following is a detailed description.

[0029] In applications, copper tabs are thin, conductive structures in power battery cells that conduct current, consisting of numerous layers of thin copper foil. Ultrasonic welding involves applying high-frequency vibration and static pressure to the multi-layered copper foil before laser welding. This causes diffusion bonding at the interfaces of each layer under solid-state conditions, tightly pressing the dispersed copper foil layers into a rigid aggregate. This provides a smooth and structurally stable surface for subsequent laser welding. The weld marks left on the tabs by this process are called ultrasonic weld marks. Multiple laser weld marks refer to multiple independent laser fusion welds formed sequentially along the surface of the electrode on the same workpiece. In square aluminum-cased batteries, there are typically two weld marks for each of the positive and negative electrodes, requiring all four weld marks to be completed sequentially. Obtaining the current temperature of the workpiece welding surface before each weld stamp refers to the actual surface temperature of the electrode and post welding area collected by a temperature measuring device before the laser scanning of each weld stamp is started. The obtained temperature value objectively reflects the amount of heat accumulated in the copper material after the previous weld stamp is completed and conducted to the current welding area. It is an indispensable prerequisite input for subsequent calculation of laser absorption rate.

[0030] In applications, the laser absorption rate is a physical quantity that quantitatively describes the ability of a metal surface to absorb the energy of incident laser light. For copper materials, this value increases significantly with the increase in surface temperature. When the workpiece surface heats up due to the thermal accumulation of previous welding imprints, the laser absorption rate of subsequent welding imprints will be significantly higher than that of the already welded imprints at the initial room temperature. The backward deduction method is a calculation method that reversely calculates process parameters starting from known results. Since it is difficult to directly measure the energy exchange process in the instantaneous interaction between the laser and the copper molten pool under engineering conditions, the backward deduction idea is adopted. Taking the measured penetration depth data that can be conveniently obtained after welding and the known surface temperature and welding process parameters before welding as known quantities, the laser absorption rate corresponding to each welding imprint is reversely solved by establishing an energy conservation equation. The ratio relationship between the laser absorption rates of adjacent welding imprints refers to taking the ratio of the laser absorption rate values obtained by separately calculating each of the two adjacent welding imprints through the backward deduction method. This ratio directly quantifies the difference in the laser absorption ability of adjacent welding imprints caused by the thermal accumulation effect and is the core input basis for subsequent derivation of the welding parameter compensation amount.

[0031] In applications, setting different laser welding parameters for each welding imprint separately means that instead of uniformly using the same laser power and welding speed for all welding imprints on the same workpiece, the laser power value or welding speed value adapted to its absorption characteristics is specified for each welding imprint according to the laser absorption rate corresponding to each welding imprint, so that each welding imprint obtains an effective laser energy input that matches its absorption rate at the actual welding process, thereby compensating for the absorption rate difference caused by the thermal accumulation effect. The separate setting is achieved through the control software supporting the welding equipment. The operator or the control system separately creates an independent parameter configuration section for each welding imprint in the welding program. When the equipment runs, it automatically switches to the corresponding parameter group according to the welding imprint number to perform welding without stopping or manual intervention. The penetration depth tending to be consistent means that after the above-mentioned differential parameter compensation, the difference between the actual laser melting depths formed by each welding imprint in the terminal post is reduced to the allowable range required by the process, thereby eliminating defects such as appearance explosion points and uneven joint performance caused by excessive penetration depth deviation.

[0032] Specifically, in a production scenario involving direct welding of 40 layers of 4.5μm thick copper tabs, the weld mark size is 3mm × 20mm. Before welding the first weld mark (the one already welded), the temperature measuring device recorded the current temperature of the workpiece welding surface as approximately 25℃. Welding was completed using parameters of 1700W laser power and 200mm / s welding speed. The measured penetration depth within the electrode post was approximately 0.31mm (total penetration depth 0.49mm), and the appearance was normal. Due to the thermal conductivity of copper being approximately 400 W / (m·K), heat was rapidly conducted to adjacent areas after the first weld mark was completed. Before welding the second weld mark (the one to be welded), the temperature was measured again, and the current temperature of the workpiece welding surface had risen to approximately 160℃. If the same parameters were used, due to the increased laser absorption rate, the penetration depth within the electrode post would increase to approximately 0.67mm (total penetration depth 0.85mm), resulting in visible defects such as pinholes. The difference in penetration depth between the two weld marks was approximately 0.36mm. The laser absorption rate of the welded stamps was calculated by reverse calculation for each of the two solder marks. The laser absorption rate of the solder mark to be soldered is approximately 3.1%. Approximately 4.9%, based on the ratio of the two. And consider temperature difference correction (in , According to the speed setting formula in the brief, After setting the laser welding speed to approximately 360–365 mm / s for the desired weld mark, welding was performed. The measured penetration depth inside the electrode post decreased to approximately 0.36 mm (total penetration depth 0.54 mm), and the difference in penetration depth between the two weld marks was reduced from 0.36 mm to approximately 0.05 mm, significantly improving process consistency.

[0033] One method for obtaining the current temperature of the workpiece welding surface before each weld stamp can be achieved by using multi-channel infrared thermometers to collect non-contact, real-time data on the electrode tabs and posts. This allows for rapid temperature data acquisition without affecting the welding operation. Alternatively, thermocouple sensors can be pre-fixed near the posts, and the thermocouple readings can be read and input into the calculation program before each weld stamp is started. Another method for setting differentiated laser welding parameters for each weld stamp can be achieved by pre-entering power and speed parameter tables for each weld stamp into the welding software. During equipment operation, the corresponding parameter group is automatically called according to the weld stamp number. A third method can be used: the control device can calculate the compensation parameters for each weld stamp online in real time and dynamically write the results into the welding equipment control register before each weld stamp is started, achieving automatic closed-loop parameter compensation.

[0034] By acquiring the workpiece temperature in real time before each weld and quantitatively calculating the laser absorptivity using a reverse calculation method, the core problem of the inability to balance the heat accumulation effect between sequential welds caused by the high thermal conductivity of copper with unified parameters is fundamentally solved. Based on the energy conservation equation, both the absorptivity calculation and parameter compensation derivation are supported by clear physical equations. The calculation process is repeatable, and the results are deterministic, overcoming the inefficiency of relying on repeated trial and error to adjust parameters based on operational experience. The penetration depth of each weld tends to be consistent, eliminating defects such as surface defects, improving the welding yield, and reducing production losses. This has direct engineering application significance for the stable mass production of power batteries.

[0035] As an optional embodiment, the laser absorptivity of each weld mark is calculated using a reverse calculation method based on the laser welding energy equation and the thermophysical parameters of copper. Specifically, the laser welding energy equation and the copper melting heat equation are combined, and the measured melt depth and pre-weld surface temperature are used as known quantities to deduce the corresponding laser absorptivity for each weld mark. This combined solution method transforms the absorptivity, which is difficult to measure directly, into a physical quantity that can be calculated from geometric dimensions, material constants, and process parameters.

[0036] The laser welding energy equation is: The equation for the heat of copper melting is: Combining the two equations, we obtain the formula for calculating the laser absorption rate of the solder mark: In application, the aforementioned laser energy equation is the fundamental physical expression describing the relationship between the total energy input by the laser beam to the workpiece and the actual energy absorbed by the material during laser welding. Welding energy Q represents the total energy input by the laser beam to the workpiece surface during the entire laser scanning process of the weld mark, measured in J. Laser welding power P is the actual output power of the laser, measured in W, and is a settable control parameter of the welding equipment; in this scheme, it is taken as 1700W. Welding time t is the time consumed for the laser beam to complete the entire weld mark scan, measured in seconds, and its value is determined by the designed weld mark length and welding speed. Laser absorptivity α is the proportion of incident laser energy actually absorbed by the copper material surface. This value is only on the order of a few percent for copper under solid-state conditions at room temperature, but it increases significantly with increasing surface temperature. It is this temperature-dependent characteristic that leads to differences in energy absorption between adjacent weld marks, resulting in inconsistent weld depth.

[0037] In application, the above-mentioned copper melting heat equation is a thermodynamic equation describing the heat absorbed during the process of heating a certain mass of copper material from its current surface temperature to its melting point. Specific heat capacity C is an inherent thermophysical property parameter of copper, representing the heat absorbed by a unit mass of copper material to increase its temperature by one °C. The specific heat capacity of copper is approximately 0.39 J / (g·°C), a known constant related to copper purity, which can be found in material handbooks. The molten metal mass m is the total mass of copper material actually melted under laser action within the solder area, in grams. This value is calculated using the solder area, total melt depth, and copper density, and is a key intermediate variable connecting the solder geometry parameters and the heat equation. The temperature difference ΔT is the difference between the melting point of copper and the current surface temperature of the workpiece before welding. The melting point of copper is approximately 1084 °C. When the current temperature of the workpiece welding surface increases due to the heat accumulation from the previous soldering, ΔT will decrease accordingly, indicating that the additional heat required to heat the copper to its melting point is reduced, which is equivalent to an increase in laser absorptivity under the same laser power.

[0038] In application, the laser welding energy equation and the metal melting heat equation are combined, meaning that the left side of both equations represents the welding energy Q, thus the right sides are equal. This establishes a direct quantitative relationship between power, time, absorptivity, specific heat capacity, mass, and temperature difference. The absorptivity α is treated as the only unknown and solved from this quantitative relationship to obtain the inverse calculation formula for the laser absorptivity. All variables on the right side of this formula are known quantities that can be directly measured or obtained through simple geometric calculations, including the material constant of copper, the geometric dimensions of the weld, the measured penetration depth, the pre-weld surface temperature, and welding process parameters. This achieves the goal of indirectly and quantitatively estimating the laser absorptivity of each weld through external observable measurements under engineering conditions where the instantaneous interaction between the laser and the molten copper pool cannot be directly measured.

[0039] Specifically, in the scenario of direct bonding of 40 layers of 4.5μm copper tabs, the complete calculation process is demonstrated using the already bonded solder joint as an example. The solder joint area S is 60mm². 2 If the laser power P is 1700W, the welding speed V is 200mm / s, and the weld mark size is 3mm×20mm, then the welding time t is 2s (e.g., Figure 5 As shown, the actual total scanning path length is 340mm, the theoretical time is 1.7s, and the actual measured time is extended to 2s due to acceleration and deceleration. The measured total melting depth h is 0.49mm, and the mass of molten metal m = 3 × 20 × 0.49 × (8.96 / 1000) ≈ 0.26g. The temperature difference is obtained by subtracting the surface temperature of 25℃ before welding from the melting point of copper (1084℃). Given a temperature of 1059℃ and a specific heat capacity of copper C of 0.39 J / (g·℃), substituting these values ​​into the calculation formula, the laser absorptivity of the welded area is approximately (0.39 × 0.26 × 1059) ÷ (1700 × 2) × 100 ≈ 3.1%. For the welded area to be welded, the surface temperature before welding is 160℃, and the total penetration depth is approximately 0.85 mm. Similarly, substituting the known values, the calculated laser absorptivity is approximately 4.9%. The difference between the two is nearly 1.6 times, fully verifying the feasibility and accuracy of the method of using simultaneous equations to deduce the laser absorptivity in this application scenario.

[0040] The laser welding power P can be determined by calibrating the actual output power of the weld head using a laser power meter and reading the value from the equipment parameter interface. Alternatively, a laser energy sensor can be used to monitor the actual output power online before welding and feed the monitoring value back to the control system in real time to improve the accuracy of the power data. The molten metal mass m can be obtained by metallographically cutting and grinding the weld section, measuring the actual melt depth under a microscope, and then substituting it into a geometric formula for calculation. Alternatively, a laser confocal microscope can be used to non-destructively characterize the three-dimensional morphology of the weld and extract the melt depth data for calculation, thus reducing the impact of cross-sectional sample preparation on measurement accuracy.

[0041] By establishing and simultaneously solving the laser welding energy equation and the metal melting heat equation, an indirect quantitative calculation method based on the principle of energy conservation is provided for laser absorptivity, which is difficult to measure directly in engineering. This solves the engineering problem of the difficulty in real-time sensing of the dynamic changes in laser absorptivity of copper materials with temperature. The parameters in both equations are inherent material constants, process parameters, or post-weld geometric measurements, eliminating the need for additional precision sensors and resulting in low computational costs. The resulting formula is concise and computationally efficient, suitable for real-time execution in welding control systems. This provides an accurate computational basis for subsequent weld stamp parameter compensation, theoretically ensuring the scientific validity and reliability of the parameter compensation scheme.

[0042] As an optional embodiment, the mass of the molten metal is obtained by multiplying the weld area, the total laser penetration depth, and the copper density, and the welding time is determined by dividing the designed weld length by the welding speed. Substituting the above relationships into the back-calculation formula for the absorption rate ensures that all input parameters are derived from directly measurable geometric data and material constants, reducing the difficulty of engineering implementation.

[0043] In applications, the molten metal mass *m* refers to the total mass of copper material that is heated above the melting point of copper and actually melts within the weld area during laser welding. It is calculated by multiplying the weld area *S*, the total weld penetration *h*, and the copper density *ρ*, i.e.: Wherein, the planar area S of the weld mark is the geometric area enclosed by the projected contour of the weld mark on the workpiece surface, and the unit is mm. 2The weld stamp dimensions can be directly read and calculated from the welding process design file. For example, when the weld stamp dimension is 3mm multiplied by 20mm, the area is 60mm². 2 The total penetration depth h in laser welding is the vertical distance from the top surface of the electrode tabs to the deepest point of the molten metal within the electrode column. It is equal to the sum of the total thickness of the copper electrode tabs and the actual penetration depth of the laser within the electrode column. In this scheme, the total thickness of the electrode tabs is 40 layers multiplied by 0.0045 mm, which equals 0.18 mm. Adding this to the penetration depth within the electrode column gives the total penetration depth, which can be obtained through metallographic section measurement. The density ρ of copper is an inherent physical property constant of copper, approximately 8.96 g / cm³. 3 Converted to g / mm 3 The value is approximately 8.96 × 10 -3 g / mm 3 When calculating, input 8.96 / 1000 as a known constant.

[0044] In this scheme, the total penetration depth h of laser welding consists of two parts: the total thickness of the copper tab stack and the actual penetration depth of the laser within the electrode column. The total thickness of the copper tab stack is determined by the number of tab layers and the thickness of a single tab layer, and is fixed during the process design phase, representing a known, fixed value for welded workpieces of the same specifications. The actual penetration depth of the laser within the electrode column, under the condition that the welding process parameters (including laser power, welding speed, defocusing amount, etc.) remain constant, mainly depends on the absorption characteristics of the copper material to the laser and the heat conduction conditions, and is essentially constant within the same process window.

[0045] In the electrode welding method provided by this invention, even for batch production scenarios with the same electrode tabs, the same electrode post structure, and the same welding process parameters, it is not necessary to rely on the initial calibration value as a fixed penetration depth parameter. The method of this invention supports the independent execution of a complete real-time adjustment process before each weld stamp is welded, specifically including: before the laser scanning of each weld stamp is started, the temperature measuring device acquires the current surface temperature of the welding area of ​​the weld stamp in real time; the control device calculates the laser absorptivity of the current weld stamp to be welded using a backward calculation method based on the real-time temperature and the measured penetration depth data of the welded stamps, according to the laser welding energy equation and the thermophysical parameters of the electrode tab material; based on the difference in laser absorptivity and temperature difference between the current weld stamp to be welded and the welded stamps, the laser welding parameters to be used for the current weld stamp are quantitatively derived according to the principle of energy conservation (preferably keeping the power constant and adjusting the welding speed); then the laser welding device performs the welding of the current weld stamp according to the differentiated parameters.

[0046] When adopting the above-mentioned real-time adjustment scheme, the welding parameters of each weld mark are independently calculated and set based on the actual thermal state of that weld mark before welding. This allows for the most accurate response to changes in the absorptivity of each weld mark caused by the previous heat accumulation, thus achieving optimal consistency in the penetration depth of each weld mark. Simultaneously, this scheme exhibits stronger adaptability to disturbances such as batch-to-batch fluctuations in tab surface condition, changes in ambient temperature, and differences in cooling conditions. It does not rely on the stability of the initial calibration values ​​across the entire batch, making it particularly suitable for high-end power battery manufacturing scenarios with extremely high requirements for welding consistency.

[0047] Of course, in actual mass production, if the tab specifications, electrode structure, and welding process parameters remain highly consistent, and the batch-to-batch consistency is good, the aforementioned simplified scheme based on the initial metallographic calibration can also be adopted to reduce the frequency of testing and improve production efficiency. Both implementation methods are within the scope of protection of this invention, and those skilled in the art can flexibly choose according to actual production cycle requirements and quality control needs.

[0048] Based on the above principles, for batch welding operations using the same specifications of tabs, pole structures, and welding process parameters, it is only necessary to obtain the actual total penetration depth h0 of the welded marks through metallographic section measurement during the production start-up phase. In subsequent welding processes of the same specifications, this measured value h0 can be directly substituted into the calculation of the molten metal mass m as a fixed penetration depth parameter under the process conditions, without needing to repeat the metallographic section measurement for each weld mark. If the number of tab layers, pole structure, or key welding process parameters change, the initial calibration measurement must be performed again to obtain the total penetration depth value under the new process conditions.

[0049] In this embodiment, the total penetration depth h is the calibration value obtained through metallographic section measurement during the production start-up phase. Since this calibration value is measured under the same tab specifications, pole structure, and welding process parameters as actual production, its value comprehensively reflects the actual situation of material batches, surface conditions, and other factors under these process conditions. In subsequent batch production of the same specifications, the total penetration depth of laser welding is mainly determined by the welding process parameters (power, speed, defocusing amount, etc.). Under the condition that the process parameters remain unchanged, the total penetration depth is basically constant. If the number of tab layers, pole structure, or key welding process parameters change, the calibration measurement can be re-performed. This calibration process is simple and quick and does not affect batch production efficiency.

[0050] It should be noted that the total penetration depth of the welded stamps is not limited to actual measurement; it can also be obtained based on a pre-defined relationship between laser welding power, welding speed, temperature, and penetration depth. This relationship can be established through preliminary process experiments. Before formal production, multiple welding tests are conducted under different power, speed, and initial temperature conditions for the same tab specifications, electrode structure, and welding process parameter range. The actual penetration depth is measured, and a power-speed-temperature-penetration depth relationship data table or fitting curve is generated. In mass production, when the welding parameters and pre-welding temperature of the welded stamps are known, the corresponding total penetration depth can be obtained directly by looking up the table or calling the fitting function, without the need for destructive or online penetration depth measurement for each welded stamp. This method is particularly suitable for production scenarios where online real-time penetration depth measurement is not possible or measurement conditions are limited, reducing inspection steps and improving production efficiency. Furthermore, this pre-defined relationship can be periodically calibrated in conjunction with the first piece's measured penetration depth to ensure its accuracy. Whether the total melting depth is obtained by actual measurement or by pre-setting a corresponding relationship, the technical effect of the present invention can be achieved. Those skilled in the art can flexibly choose according to the on-site testing capabilities and production cycle requirements, and all of them fall within the protection scope of the present invention.

[0051] In applications, the welding time t is the time required for the laser beam to complete the actual scanning path of the entire weld mark, measured in seconds. The actual welding trajectory is not a single straight line, but rather... Figure 5 The diagram shows a rectangular filled reciprocating path. Taking a 3mm × 20mm solder mark as an example, the designed solder mark length... =20 mm, line spacing 0.2 mm, then the total welding length of a single weld (including transverse connections and longitudinal fillers, such as...) Figure 5 (As shown) is approximately: The welding speed is set to V=200 mm / s, and the theoretical welding time is... In actual production, due to factors such as laser start-stop response and acceleration / deceleration, the measured welding time varies. This invention directly uses the measured welding time in the absorption rate calculation. Since the total welding length of the two weld marks is the same, the time factors cancel each other out in the absorption rate ratio. Therefore, the compensation results obtained by using the measured time and the theoretical time are consistent and do not affect the final parameters.

[0052] It should be noted that the welding time t mentioned above is not limited to the actual measured value; a preset welding time can also be used, for example, based on the total length of the laser beam scanning path. The theoretical welding time calculated with the set welding speed V In practical engineering, due to factors such as laser start-stop response and acceleration / deceleration, the measured welding time may deviate from the theoretical calculation time. However, in calculating the laser absorption rate of each weld mark, this invention does not substantially affect the final parameter compensation result whether the measured welding time or the preset theoretical welding time is used. This is because the total welding length of all weld marks on the same workpiece... Similarly, when deriving parameter compensation relationships based on the ratio of absorption rates of adjacent solder marks, the time factors will cancel each other out in the ratio calculation. Therefore, those skilled in the art can flexibly choose to use either the actual measured welding time or the preset welding time according to the on-site measurement conditions, equipment data acquisition capabilities, and ease of calculation; both methods can achieve the technical effects of the present invention.

[0053] Specifically, in a scenario where the solder mark size is 3mm × 20mm and the copper tab has 40 layers, the area S is 60mm². 2 For the soldered weld marks, the measured total penetration depth h was 0.49 mm, and the copper density ρ was taken as 8.96 g / cm³. 3 =0.00896g / mm 3 molten metal mass m In the above calculation, the formula uses the designed weld area, which is independent of the total weld length. Welding time is based on measured values. Welding power The specific heat capacity of copper is C = 0.39 J / (g·℃). The temperature of the welded area before welding is 25℃. The temperature difference is... =1084-25=1059 ℃, substituting into the absorption rate formula: For the weld mark to be soldered, the pre-soldering temperature is raised to 160℃, and the measured total penetration depth h≈0.85mm, then... Temperature difference =1084-160=924 ℃, therefore: The above two sets of absorption rate values and The ratio is approximately 1.58, providing accurate input for subsequent parameter compensation.

[0054] The total penetration depth h can be measured by metallographically preparing the weld joint and then measuring the depth of the molten area in the vertical direction under an optical microscope. Alternatively, industrial CT scanning can be used to perform three-dimensional characterization of the weld cross-section and automatically extract the penetration depth value for non-destructive testing. The weld mark design length L can be determined by directly reading the weld mark size design value from the welding process design drawings. Alternatively, a visual inspection system can be used to perform dimensional calibration measurements on the actual weld mark image after welding to verify the consistency between the actual weld mark design length and the design value and confirm the accuracy of the calculation input.

[0055] The molten metal mass *m* is decomposed into the product of three independent measurable variables: the weld area, the total weld penetration depth, and the copper density. The welding time *t* is expressed as the ratio of the designed weld penetration length to the welding speed. This eliminates unknowns in the laser absorptivity calculation chain that require additional specialized measuring equipment. All parameters used are existing process data and conventional metallographic testing data from the welding production site, resulting in low engineering implementation costs. Precise calculation of the molten metal mass improves the accuracy of the laser absorptivity back-calculation results, allowing the derivation of subsequent welding parameter compensation quantities to be based on more accurate calculations, which is beneficial for improving the control precision of the final weld penetration depth consistency.

[0056] As an optional embodiment, at least one welded weld is selected from the preceding welded welds. To improve efficiency, the welding parameter compensation amount is directly derived based on the ratio of laser absorptivity between adjacent welds. Specifically, based on the principle that the laser welding energy required for two welds with the same penetration depth is equal, a parameter compensation formula for power and speed is derived: the ratio of the power of the welded weld to the power of the weld to be welded, multiplied by the ratio of the speed of the weld to the speed of the welded weld to the speed of the welded weld, equals the ratio of the absorptivity of the weld to the absorptivity of the welded weld. This formula provides a unified quantitative criterion for selecting either power adjustment or speed adjustment as the compensation path.

[0057] In applications, adjacent weld marks and weld seams to be welded refer to two laser weld seams that are close together in the welding sequence on the same workpiece. The weld mark is completed first, and the weld seam to be welded follows immediately. They are spatially adjacent and temporally continuous. Therefore, the heat remaining in the electrode post and tab after the weld mark is completed can be transferred to the adjacent area through the efficient heat conduction of copper before the weld seam to be welded begins, causing the temperature of the weld seam to rise. The laser welding power of the weld mark... and welding speed These are the process parameters set and used during the actual execution of the soldering process, including the laser absorption rate. These are physical property values ​​calculated using a reverse calculation method based on the pre-welding temperature and measured penetration depth of the welded area. The laser welding power of the weld to be welded... welding speed These are the target process parameters to be used when performing soldering, at least one of which differs from the already soldered solder to achieve parameter compensation, such as laser absorptivity. The corresponding physical property value is determined by the increase in surface temperature of the solder mark before soldering.

[0058] In applications, when two welds have the same penetration depth, the mass of molten metal is the same (denoted as m), but the initial temperatures of the two welds are different (the first weld has a different initial temperature). The second one is Therefore, equal masses of copper are heated from their respective initial temperatures to the melting point of copper. The heat required for (e.g., =1084℃) is as follows: in, Let be the specific heat capacity of copper. Assume the actual laser energy absorbed by the soldered area is . The solder mark to be soldered is Ignoring heat loss, we have , Therefore, when the penetration depth of two solder joints is the same, the ratio of the energy absorbed is equal to the ratio of the heat required: in, = - , = - Substitute = , = ( (For the total weld length, assuming two identical weld marks), the result is: That is, the parameter compensation relationship: in, The laser welding power of the welded stamp is expressed in W. The laser welding power of the desired solder mark is expressed in W. The laser welding speed of the welded marks is in mm / s. The laser welding speed of the desired solder mark is expressed in mm / s. The laser absorption rate of the solder mark; The laser absorption rate of the solder mark to be soldered; , The first point refers to the temperature rise required to heat the copper material from its initial temperature to its melting point before welding, expressed in °C.

[0059] This formula is derived from the principle of energy equality by simplifying and rearranging it by substituting the relationship between welding time and speed. Since welding time equals the total welding length divided by the welding speed, and the designed lengths of the two weld marks are the same, the ratio of the welding times of the two weld marks is equal to the inverse ratio of their welding speeds. Substituting this relationship into the energy equality equation, the weld mark design length term cancels out because it appears on both sides of the equation, ultimately yielding a parameter compensation relationship containing only the power ratio and speed ratio. This relationship shows that, while keeping the weld mark geometry constant, if the ratio of the laser absorptivity of the two weld marks is known, either the power or the welding speed parameter can be adjusted to make the ratio of the parameters satisfy this equation, thereby theoretically achieving consistency in the penetration depth of the two weld marks.

[0060] Specifically, the laser power of the solder mark... 1700W, welding speed The laser absorption rate is 200 mm / s. The laser absorption rate of the solder mark to be soldered is approximately 3.1%. Under the condition of approximately 4.9%, substituting into the parameter compensation formula, the absorption rate ratio is... / ≈1.58.

[0061] If let equal That is, keeping the power constant and taking into account the effect of the initial temperature difference. =1059℃, =924℃, ratio / If ≈1.146, then the actual compensation speed should be: In actual production, the rounding setting is 360-365 mm / s.

[0062] If let equal That is, if the speed remains constant, then =1700÷1.58≈1075W.

[0063] Both schemes can be directly calculated using this parameter compensation formula, providing a clear quantitative basis for flexibly selecting parameter adjustment methods based on actual equipment conditions. Field test results show that after adopting the compensation scheme of increasing the speed to approximately 360 mm / s, the weld penetration depth of the desired weld is reduced to approximately 0.36 mm, which differs from the weld penetration depth of approximately 0.31 mm by about 0.05 mm. The compensation effect is roughly in line with the calculated expectations.

[0064] Among them, laser absorption rate and The calculation method can be achieved by using the aforementioned simultaneous equations and reverse calculation method. Known solder area, penetration depth, copper density, specific heat capacity, and surface temperature data can be substituted into the formula to obtain the result. Alternatively, the penetration depth temperature characteristic curve can be determined through welding tests with multiple parameters on the first sample, establishing an empirical data table of absorptivity changes with surface temperature. In production, the estimated absorptivity value can be obtained by referring to the table based on the measured temperature. Regarding the selection of power or speed in the parameter compensation formula, one approach is to keep the welding power constant while increasing the welding speed of the desired solder joint to avoid the risk of unstable molten pool in the initial stage due to excessively low power. Another approach is to keep the welding speed constant while decreasing the laser power of the desired solder joint, which is suitable when the power adjustment range is sufficient and does not affect stable arc initiation.

[0065] By establishing a parameter compensation formula centered on the ratio of the laser absorptivity of two weld marks, the previously difficult-to-quantify heat accumulation effect of adjacent weld marks is transformed into a simple two-parameter ratio constraint. This allows operators to directly determine the compensation parameters through a single calculation, eliminating the need for numerous repeated experiments. This formula simultaneously covers two compensation methods: power adjustment and speed adjustment, giving engineers the freedom to choose flexibly based on equipment characteristics and process windows. The formula has a clear physical meaning, containing only three types of parameters: power, speed, and absorptivity, making it suitable for programmatic implementation in welding control software. This lays the algorithmic foundation for automated, on-demand compensation of multiple weld mark parameters.

[0066] As an optional embodiment, parameter compensation is implemented by keeping the welding power constant and increasing the welding speed of the desired weld. Specifically, the laser welding power of the desired weld is set equal to the laser welding power of the already welded weld, and the welding speed of the desired weld is determined by multiplying the absorptivity ratio by the welding speed of the already welded weld. This scheme avoids the risk of instability in the initial molten pool that may result from excessively reducing the power, and it is simple to calculate and has high engineering reliability.

[0067] In application, setting the laser welding power of the desired weldment equal to the laser welding power of the already welded weldment means that when applying the parameter compensation formula, the constraint is to keep the laser power constant, concentrating all the degrees of freedom in parameter adjustment on the welding speed. The engineering rationale for this approach is that excessively reducing the laser power leads to a decrease in the stability of the molten pool at the weldment's initial position. When the laser power is too low, the copper material at the starting point may not be able to quickly form a stable molten pool, resulting in defects such as incomplete fusion or insufficient penetration in the initial section of the weldment, thus deteriorating the weldment quality. Therefore, under the premise of keeping the power constant, appropriately increasing the welding speed of the desired weldment to reduce the effective laser energy input per unit length compensates for the additional energy absorption caused by the increased absorptivity without compromising the minimum energy density conditions required for stable molten pool formation in the initial section of the weldment, making it a more robust engineering choice.

[0068] In application, the welding speed of the solder joint to be soldered It is determined by the parameter compensation relation in order to... equal The simplified speed compensation formula obtained under the given conditions shows that, when the power of the two lasers is kept the same, the ratio of the target welding speed of the desired weld to the welding speed of the already welded weld is exactly equal to the ratio of the absorptivity of the two lasers. That is, the desired weld with a higher absorptivity needs to be scanned at a higher speed to reduce the dwell time of the laser beam per mm of the designed weld length, thereby offsetting the additional energy absorption caused by the increased absorptivity. / This absorption rate ratio is the sole determinant of speed compensation. If the absorption rates of the two solder marks are the same, the target speeds are the same. As the difference in absorption rates increases, the speed compensation also increases accordingly. The calculation logic is intuitive and easy to verify.

[0069] Specifically, the welding speed of the welded stamps The laser absorption rate is 200 mm / s. The laser absorption rate of the solder mark to be soldered is approximately 3.1%. Under the measured condition of approximately 4.9%, substituting into the velocity compensation calculation formula yields... =1.58×1.146×200≈362mm / s, the actual welding speed was rounded down to approximately 360mm / s. Welding was performed on the desired weld at this speed, and the measured penetration depth was approximately 0.36mm, a significant decrease compared to the approximately 0.67mm penetration depth achieved with uniform parameters. This is approximately 0.05mm less than the approximately 0.31mm penetration depth of the previously welded weld, and the appearance of any popping spots was eliminated. With the laser power maintained at 1700W, the molten pool at the beginning of the weld was stable, and the entire weld had a uniform appearance. This verifies that, under the condition of maintaining constant power, simply increasing the welding speed can effectively compensate for the increased absorptivity caused by heat accumulation, achieving the process goal of making the penetration depth of the two welds more consistent.

[0070] Among them, the absorption rate ratio / The absorptivity can be obtained by immediately collecting the temperature of the area to be welded after the welded area is completed, then substituting the values ​​into a reverse formula to calculate the ratio of the two absorptivity. Alternatively, welding tests can be conducted on samples under different initial temperature conditions to establish a curve relating surface temperature to laser absorptivity. During production, the absorptivity ratio can be estimated by referring to the curve based on the measured temperature. The welding speed of the area to be welded... The setting and execution methods can be adopted by manually inputting the calculated speed value into the corresponding welding stamp parameter configuration section of the welding control software and then starting the welding program, or by using the control device to automatically complete the speed compensation calculation before each welding and write the result into the welding equipment parameter register to realize online automatic parameter updates.

[0071] Choosing a parameter compensation method that increases welding speed while maintaining constant power theoretically avoids the process risk of a stable weld pool not forming in the initial stage of the weld bead due to reduced laser power. Actual testing verified that the initial weld bead had a good appearance and uniform penetration throughout. The speed compensation calculation formula is simple and... / The ratio multiplied by You can get it directly With fewer calculation steps and no iteration required, it is suitable for real-time execution in welding control software with extremely low computational overhead. Field tests show that after compensation, the difference in weld penetration between the two welds was reduced from approximately 0.36 mm to approximately 0.05 mm, demonstrating a significant improvement and proving the effectiveness and engineering practical value of this speed compensation scheme in actual power battery manufacturing scenarios.

[0072] As an optional embodiment, the copper tab is a multi-layer copper foil laminated structure, which is ultrasonically welded together and then directly fixed to the top cover pole by laser welding. The laser welding direction is to penetrate vertically from the top surface of the tab and melt into the pole. The laser welding parameters for each weld mark are set individually by the welding software for that weld mark. The current temperature of the workpiece welding surface is obtained in real time by a multi-channel temperature measuring instrument before each weld mark is welded, which together constitutes the hardware and data basis for differentiated compensation.

[0073] In applications, the copper tabs are multi-layered copper foil stacked structures. This means that the conductive material constituting the tabs consists of a large number of thin copper foil layers neatly stacked together according to the designed number of layers. In this scheme, the tabs are composed of 40 layers of copper foil with a thickness of 4.5μm, and the total thickness of the tabs is approximately 0.18mm. The ultrasonic welding process brings them together into a single unit. This involves applying ultrasonic welding to the aforementioned multi-layered copper foil before laser welding. The high-frequency vibration of ultrasound generates frictional heat and plastic deformation between the layers of copper foil in the tab, causing the layers to diffuse and bond together at the interfaces to form a metallurgical connection. This compacts the dispersed multi-layered copper foil into a cohesive body with sufficient structural integrity, providing a flat and stable welding base for subsequent laser welding. The pressing marks left on the tabs by ultrasonic welding are called ultrasonic weld marks.

[0074] In applications, laser welding is performed by vertically penetrating from the top surface of the tab and melting into the electrode post. This means the laser beam is incident from top to bottom in a direction perpendicular to the tab plane. It first passes through the copper tab assembly, which has been pre-welded together by ultrasonic waves, melting all the copper tabs before continuing downwards into the top electrode post, forming a metallurgical connection across the tab-post interface. This welding direction ensures that the laser energy penetrates layer by layer along the thickness direction, forming a stable molten connection zone at the tab-post contact interface, achieving both electrical and mechanical connection between the tab and post. This method of welding directly from the top surface of the tab to the post is called direct tab welding, which, unlike the indirect connection method using adapter plates, has a shorter current path and lower contact resistance.

[0075] In application, the laser welding parameters for each weld mark are set individually by the welding software. This means that by using the multi-segment welding parameter configuration function provided by the control software of the laser welding equipment, an independent parameter segment is established for each weld mark in the welding program. Each parameter segment contains the laser power and welding speed settings corresponding to that weld mark. When the equipment executes the welding of each weld mark in sequence, it automatically calls the corresponding parameter segment according to the weld mark number to be welded. Automatic switching of welding parameters between adjacent weld marks can be achieved without manual intervention, so that differential parameter compensation can be seamlessly integrated into the production process without adding extra operation steps.

[0076] In application, the current temperature of the workpiece welding surface is obtained in real time by a multi-channel temperature measuring instrument before each weld stamp is welded. The multi-channel temperature measuring instrument refers to a temperature measuring device capable of simultaneously acquiring data from multiple temperature measurement channels, enabling synchronous temperature acquisition at multiple locations on the workpiece at the same time, avoiding time difference errors introduced by time-division measurement. Real-time measurement means that temperature acquisition is completed in a very short time before the laser scanning of each weld stamp begins, ensuring that the acquired temperature data reflects the true thermal state of the workpiece at the moment the weld stamp is about to begin, rather than the temperature value after a long period of thermal diffusion decay following the completion of previous weld stamps, thus guaranteeing the accuracy of the absorptivity calculation.

[0077] Specifically, in the direct welding process of the square aluminum-cased battery cell pack, 40 layers of 4.5μm copper tabs are stacked and first sent to the ultrasonic welding station. The ultrasonic welding device applies ultrasonic vibration and pressure to the tabs, forming an ultrasonic weld mark on the tabs, tightly pressing and gathering the multiple layers of copper foil into a whole. The cell pack is then transferred to the laser welding station. Multiple temperature measuring instruments measure the initial surface temperature of approximately 25℃ in the welded area of ​​the positive electrode. The welding control software calls the welded parameter segment and performs laser welding at a laser power of 1700W and a welding speed of 200mm / s. The laser penetrates the tab from top to bottom and melts into the terminal post, forming a direct weld joint connecting the tab and the terminal post. Immediately after the welded area is completed, the temperature of the area to be welded is measured to be approximately 160℃. The control system calculates a compensation speed of approximately 360-365mm / s and writes it into the welded parameter segment. The equipment switches to this parameter segment to perform the welded area. The measured penetration depth is close to the first weld, with no bursts in the appearance, and good process consistency.

[0078] The process of ultrasonically welding and bringing together multi-layer copper tabs can be achieved by using an ultrasonic metal welding machine to spot weld the stacked copper foils at a fixed frequency and pressure parameters, forming a uniformly distributed ultrasonic weld mark within the tab width to ensure full bonding between the layers. Alternatively, ultrasonic wire welding can be used to continuously weld along the tab width, forming a continuous gathering weld seam that runs through the tab width, further improving the uniformity and integrity of the bonding between the tab layers. Real-time measurement of the workpiece welding surface temperature can be achieved using an infrared thermal imager to perform full-field temperature imaging of the weld mark area, automatically extracting the average temperature of the center area of ​​the weld mark before each weld mark is started. Alternatively, a contact thermocouple sensor fixed on the welding fixture can be used to measure the temperature at a fixed point near the electrode surface, using this as a representative value for the weld mark area temperature.

[0079] This process organically combines ultrasonic pre-welding of the multi-layered copper tab structure, direct laser welding from the top surface of the tab directly into the electrode post, and a differentiated parameter setting scheme based on real-time measurements from multiple temperature measuring instruments to form a complete direct tab welding process. Ultrasonic pre-welding eliminates the adverse effects of interlayer voids in the multi-layered copper foil on laser welding quality, ensuring workpiece stability during the laser welding stage. The welding software's ability to set parameters individually for each weld mark allows for direct implementation of heat accumulation compensation schemes through software configuration without changing the equipment hardware, resulting in extremely low engineering modification costs. The multiple temperature measuring instruments provide accurate and reliable pre-welding temperature data, ensuring the accuracy of absorptivity calculations and parameter compensation derivations, providing a reliable data foundation for consistently achieving consistent weld penetration across all weld marks.

[0080] Example 2 This embodiment provides a tab welding system for implementing the welding method described in Embodiment 1. Addressing the problem that traditional open-loop welding systems cannot compensate for absorbance drift caused by heat accumulation online, this invention integrates an ultrasonic welding device, a temperature measuring device, a laser welding device, and a control device. The following details... Figure 3 Each module is described in detail.

[0081] The ultrasonic welding device is a functional unit in the welding system responsible for pre-welding and agglomerating multi-layer copper tabs. Its working principle involves converting electrical energy into high-frequency mechanical vibration through an ultrasonic transducer. This vibrational energy is then applied to the welding interface of the laminated copper foil by the welding head. Under the combined action of static pressure, the contact interfaces between the layers of copper foil undergo plastic deformation and diffusion bonding, tightly agglomerating the dispersed, laminated multi-layer copper foil into a welded body with overall rigidity without the use of any welding auxiliary materials, leaving ultrasonic weld marks on the tabs. After the ultrasonic welding device completes the pre-welding of the tabs, the multi-layer copper tabs form a smooth surface and a well-bonded agglomerate, whose structural state meets the pre-welding preparation requirements for laser welding, providing a qualified workpiece condition for subsequent laser direct welding processes.

[0082] The temperature measuring device is a functional unit in the welding system responsible for acquiring the current temperature of the workpiece's welding surface in real time before each laser weld stroke and outputting the data to the control device. The temperature measuring device must have a response speed sufficient to complete temperature acquisition within the welding station cycle time, ensuring that the acquired temperature data accurately reflects the actual thermal state of the workpiece at the start of each weld stroke. A data communication connection is established between the temperature measuring device and the control device. After each temperature acquisition, the measurement result is transmitted to the control device in real time in digital signal form, serving as key input data for the control device to perform laser absorptivity calculations and derive welding parameter compensation amounts.

[0083] A laser welding device is a functional unit within a welding system responsible for sequentially performing laser welding on each weld mark according to the differentiated welding parameters output by the control device. The laser welding device must have the ability to independently set the laser welding power and speed for each weld mark on the same workpiece. This capability is achieved through the multi-segment parameter configuration function in its accompanying welding software. Each weld mark corresponds to an independent parameter segment, and the equipment executes the welding by sequentially calling the parameters of each segment. A parameter writing communication interface is established between the laser welding device and the control device. The differentiated parameters for each weld mark calculated by the control device can be written to the parameter register of the laser welding device through this interface, enabling real-time parameter updates and automatic switching.

[0084] The control unit, the core functional unit of the welding system, is responsible for data reception, parameter calculation, and command coordination. It is connected to both the temperature measurement device and the laser welding device. The control unit receives pre-weld surface temperature data for each weld mark from the temperature measurement device and, combined with the weld mark geometry, the thermophysical constants of copper, and the measured weld penetration depth, calculates the laser absorptivity for each weld mark using a backward deduction method, following the simultaneous solution of the laser welding energy equation and the copper fusion heat equation. After obtaining the laser absorptivity for each weld mark, the control unit further derives the differentiated laser welding parameters for each weld mark based on the ratio between the laser absorptivity of adjacent weld marks according to the parameter compensation formula. The calculation results are then output to the laser welding device to guide the actual welding execution of each weld mark, thereby ensuring that the weld penetration depth of each weld mark is consistent.

[0085] Specifically, in the complete workflow of the welding system, the ultrasonic welding device first pre-welds and gathers 40 layers of copper tabs to form a flat tab stack. Then, the core package enters the laser welding station. Before welding begins on the pre-welded positive electrode, a temperature measuring device measures the surface temperature of the area to approximately 25°C and transmits the data to the control device. Using this temperature as a known quantity, the control device calculates the laser absorption rate of the pre-welded area to be approximately 3.1% after welding is completed and the measured penetration depth is obtained. Simultaneously, before welding the desired area, it receives temperature data of approximately 160°C from the temperature measuring device, calculates the laser absorption rate of the desired area to be approximately 4.9%, and derives a speed compensation value of approximately 362 mm / s. This parameter is then written into the laser welding device. When executing the desired area, the laser welding device automatically switches to the compensated parameters to complete the welding. The penetration depths of the two welds become consistent, and the system forms a complete temperature sensing, compensation calculation, and parameter execution closed-loop control.

[0086] The data communication between the control device and the temperature measuring device can utilize wired serial ports or industrial Ethernet communication protocols to achieve real-time transmission of temperature data, ensuring a low-latency and highly reliable data link. Alternatively, a wireless sensor network can be used to transmit the data collected by the temperature measuring instrument to the control device in real time via a wireless channel, reducing on-site wiring and improving installation layout flexibility. The control device can output differentiated welding parameters to the laser welding device in several ways. First, the calculated parameters can be written into the parameter register of the corresponding weld mark before each weld mark is started via the device's communication interface. Second, the control device can directly generate a welding program file containing all the differentiated parameters for each weld mark, allowing the laser welding device to execute multiple welding segments according to the file, with each segment corresponding to the independent parameter configuration of one weld mark.

[0087] This welding system, through the coordinated operation of four functional units—an ultrasonic welding unit, a temperature measurement unit, a laser welding unit, and a control unit—transforms the multi-weld heat accumulation compensation method from a purely computational approach into a complete system solution that can be directly deployed on the production line. Ultrasonic welding and laser welding are sequentially connected within the same system framework, reducing inter-process transfer operations and improving production efficiency. The control unit centrally handles data processing and parameter calculation, reducing reliance on manual calculations and parameter adjustments by operators and minimizing human error. Real-time data input from the temperature measurement unit ensures the timeliness of the control unit's calculations, enabling parameter compensation to respond to actual changes in the workpiece's thermal state during each welding operation, rather than relying on fixed empirical parameters. This ensures consistent weld penetration depth across all welds in mass production.

[0088] As an optional embodiment, the temperature measuring device is a multi-channel temperature measuring instrument capable of simultaneously acquiring temperature data at multiple locations on the workpiece welding surface before each weld stamp is applied, and transmitting the acquired temperature data to the control device in real time. Multi-point synchronous measurement improves the comprehensiveness of thermal state characterization, and real-time transmission ensures the timeliness of parameter compensation.

[0089] In applications, multichannel temperature measuring instruments are a specific implementation of temperature measurement devices. Their key feature is the presence of multiple temperature measurement channels, enabling simultaneous temperature acquisition at multiple locations on the workpiece's welding surface. Synchronous acquisition means that temperature readings from multiple channels are performed concurrently rather than sequentially. This characteristic ensures that temperature data from multiple representative locations on the electrode surface or weldment area are obtained simultaneously within the brief pre-welding temperature measurement window, avoiding measurement errors introduced by time-sharing methods due to differences in the timing of readings from different locations. The simultaneous acquisition of multiple locations on the workpiece's welding surface by multichannel temperature measuring instruments allows the control device to obtain a comprehensive description of the workpiece's thermal state at the current moment, rather than relying solely on temperature information from a single point. This helps to more accurately characterize the actual preheating temperature distribution of the weldment area, improving the representativeness and accuracy of the temperature data used for absorptivity calculations.

[0090] In application, real-time transmission of collected temperature data to the control device means that after each temperature acquisition, the multi-channel temperature measuring instrument automatically sends the acquisition results to the control device via a data communication link for calculation without manual intervention. Real-time transmission implies an extremely short time delay between the completion of temperature acquisition and the receipt of data by the control device, without affecting the normal cycle of the welding process. The control device can complete parameter calculations and write the results to the welding equipment before the laser welding device starts welding. The entire data flow is fully automated during the welding preparation stage. After the temperature data is transmitted to the control device, the built-in parameter calculation module of the control device performs subsequent absorption rate back-calculation and parameter compensation amount derivation, driving the laser welding device to execute corresponding differentiated parameter welding.

[0091] Specifically, in the actual direct-connection welding process of the electrode tabs, a multi-channel temperature measuring instrument is fixedly installed at an appropriate position in the laser welding station, with each temperature measuring channel probe aligned with multiple temperature measuring points on the electrode surface. Before the welding control program starts the laser scanning of each weld mark, the program issues a temperature measurement command. Each channel of the multi-channel temperature measuring instrument synchronously completes a temperature acquisition and transmits the temperature readings of each channel to the control device as digital signals within a millisecond delay. Taking two weld marks on the positive electrode as an example, the average temperature of each channel before the welded marks are completed is approximately 25°C. After being transmitted to the control device, it waits for the completed weld marks and obtains the penetration depth data before performing an absorption rate calculation. During the time interval between the completion of the completed weld marks and the start of the weld mark to be welded, the multi-channel temperature measuring instrument again synchronously acquires and reads temperature data of approximately 160°C and transmits it to the control device. The control device immediately completes the absorption rate calculation and speed compensation derivation of the weld mark to be welded, writes the calculation results into the laser welding device, and then starts the welding of the weld mark to be welded. The entire process is completed automatically without manual intervention.

[0092] Among the various techniques for simultaneously acquiring temperature data from multiple locations using multi-channel temperature measuring instruments, a multi-channel infrared radiation thermometer can be employed. This instrument uses multiple temperature probes fixedly pointed at different locations within the soldering area. Each channel is triggered synchronously, reading the temperature values ​​of all channels within a single acquisition cycle. Alternatively, an infrared thermal imager combined with image processing software can be used to extract the average temperature of multiple preset regions of interest from the thermal image, achieving multi-point synchronous temperature measurement. For real-time temperature data transmission, RS-232 or RS-485 serial communication can be used to directly connect the temperature measuring instrument and the control device, transmitting temperature data in real-time at a fixed baud rate. Alternatively, an industrial Ethernet communication protocol can be used to push the temperature measuring instrument's data to the control device via a network, supporting longer transmission distances and higher data transmission rates.

[0093] Multi-channel temperature measuring instruments possess multi-channel synchronous acquisition capabilities, providing a more comprehensive description of the thermal state distribution of the weldment area compared to single-point, single-measurement methods. This reduces the representativeness of temperature data caused by deviations in single-point measurement locations. Real-time transmission eliminates the manual transfer between temperature data acquisition and welding parameter calculation, enabling the entire thermal compensation process to be completed fully automatically within the production cycle time, without affecting welding efficiency. As an independent external sensor device, the multi-channel temperature measuring instrument requires no modification to the laser welding equipment itself. It can be integrated into existing welding systems by connecting to the control device via a data communication interface, resulting in low engineering integration costs and strong adaptability to existing production line modifications.

[0094] As an optional embodiment, the control device has a built-in parameter calculation module, the calculation process of which is as follows: Figure 4As shown, this parameter calculation module performs the following calculations: it calculates the laser absorptivity of each weld mark based on the welding surface temperature and corresponding laser penetration depth; it calculates the welding speed or welding power compensation between adjacent weld marks based on the ratio of their laser absorptivity; and it outputs differentiated welding parameters corresponding to each weld mark to the laser welding device. This module integrates sensing, calculation, and decision-making, automating the compensation process.

[0095] In application, the first core calculation task performed by the parameter calculation module is to calculate the laser absorptivity of each weld mark by inversely using the laser welding energy equation and the copper molten heat equation, based on the welding surface temperature and corresponding laser penetration depth of each weld mark. This calculation takes the pre-weld surface temperature of each weld mark transmitted in real-time by the temperature measurement device as input, and the measured penetration depth data obtained from the penetration depth detection of each weld mark as input. Combined with the weld mark geometry, known material constants such as copper density and specific heat capacity, the laser absorptivity value for each weld mark is calculated sequentially according to the laser absorptivity calculation formula. The absorptivity calculation for each weld mark is independent, based on its own pre-weld temperature and penetration depth data, fully reflecting the differences in workpiece thermal state caused by different welding sequences, and serving as the prerequisite for subsequent parameter compensation calculations.

[0096] In application, calculating the welding speed or welding power compensation between adjacent welds based on the ratio of their laser absorptivity is the second core calculation task performed by the parameter calculation module. After obtaining the laser absorptivity of each of the two adjacent welds, the parameter calculation module calculates their ratio. Divide by Then, according to the parameter compensation formula and the selected compensation method, the specific target value of the parameter that needs to be adjusted is derived. When using the fixed power adjustment speed compensation method, the compensation result is the target welding speed of the desired weldment, which is equal to the absorptivity ratio multiplied by the welding speed of the already welded weldment. When using the fixed speed adjustment power compensation method, the compensation result is the target laser power of the desired weldment, which is equal to the laser power of the already welded weldment divided by the absorptivity ratio. The parameter calculation module automatically selects the corresponding calculation path and executes it according to the preset compensation method.

[0097] In application, outputting differentiated welding parameters corresponding to each weld mark to the laser welding device is the third core calculation task performed by the parameter calculation module, and it is also a key step in converting the calculation results into actual execution instructions for the welding equipment. After completing the parameter compensation calculation for each weld mark, the parameter calculation module outputs the target laser power and target welding speed corresponding to each weld mark to the laser welding device in the form of digital control signals. This can be achieved by directly writing to the parameter register of the welding equipment, updating the parameter segment of the corresponding weld mark in the welding program, or triggering the parameter switching command of the equipment. After the parameters are output, the laser welding device executes the welding of the corresponding weld mark according to the new differentiated parameters, completing a complete control closed loop from thermal state perception, absorptivity calculation, parameter derivation to welding execution.

[0098] Specifically, during the operation of the parameter calculation module built into the control device, for the positive electrode solder mark, the module receives the pre-soldering surface temperature of 25℃ and the measured total weld depth of 0.49mm after soldering, and substitutes them into the calculation formula to obtain the laser absorption rate. Approximately 3.1%, and stored in the cache. For the desired solder mark, the module receives a pre-soldering surface temperature of 160℃, and after the first reference soldering of the desired solder mark, obtains a total penetration depth of approximately 0.85mm, from which the laser absorption rate is calculated. The absorptivity is approximately 4.9%. The module then calculates the absorptivity ratio to be approximately 1.58. According to the fixed power speed adjustment scheme, the target speed of the weld bead to be welded is calculated to be approximately 362 mm / s and output to the laser welding device. After updating the corresponding parameter segment, the laser welding device executes the weld bead to be welded, realizing automatic and accurate compensation of welding parameters. This verifies the complete execution link of the three calculation tasks of the parameter calculation module.

[0099] The parameter calculation module can acquire the penetration depth data required for laser absorptivity calculation by integrating an online penetration depth sensor at the welding station. This sensor automatically measures the penetration depth after each weld stroke and transmits the data back to the control device. Alternatively, it can perform metallographic sectioning on the first sample to establish a mapping between power / speed and penetration depth. During mass production, penetration depth data can be estimated using a lookup table for the parameter calculation module. The parameter calculation module can output differentiated parameters to the laser welding device by writing the calculated parameters into the currently active parameter segment of the welding equipment in real time via a communication interface before each weld stroke begins. Alternatively, it can pre-write the compensation parameters for all weld strokes offline before mass production begins, allowing the equipment to directly perform welding stroke by stroke according to the pre-written differentiated parameters during mass production.

[0100] The control device incorporates a parameter calculation module that integrates three tasks—laser absorptivity calculation, compensation amount derivation, and parameter output—into a single software module for unified execution. This avoids the error risks introduced by multiple systems or manual intervention. The calculations performed by the parameter calculation module are based on the energy conservation equation and simple algebraic operations, resulting in low computational load and fast execution speed. All calculations can be completed within the interval between adjacent welding operations, and parameters are written before welding begins, without causing cycle time delays. The parameter calculation module accepts real-time temperature input from a temperature measurement device, enabling the compensation parameter calculation to track changes in the actual thermal state of the workpiece during each welding operation. It provides accurate compensation parameters for different batches of products and under different environmental conditions, ensuring the robustness and consistency of the solution in mass production.

[0101] As an optional embodiment, the laser welding device is equipped with welding software that allows for independent setting of welding power and speed for multiple weld marks on the same workpiece. This enables parameter compensation for differences in laser absorptivity caused by copper heat accumulation between adjacent weld marks. After completing the welding of each weld mark, the laser welding device feeds back the actual welding parameters and penetration depth data to the control device for subsequent weld mark absorptivity calculations and parameter corrections, forming a closed-loop self-optimizing control.

[0102] In applications, the welding software equipped with laser welding equipment supports independently setting the welding power and speed for multiple weld marks on the same workpiece. This means that the welding software provides multi-segment welding parameter configuration functions at the program design level, allowing operators or control systems to specify laser power and welding speed values ​​individually for each weld mark in a complete welding program. Each weld mark forms an independent parameter configuration segment, and the parameters between segments do not affect each other. When the equipment executes multiple weld marks sequentially, it automatically reads and applies the corresponding parameters segment by segment according to the weld mark number. This function enables the differential parameter compensation scheme to be implemented through pure software configuration without any hardware modification to the welding equipment. Parameter compensation can be achieved simply by writing the differential parameters obtained from the compensation calculation into the corresponding parameter segment of the welding software according to the weld mark sequence. The modification cost is extremely low, making it suitable for direct promotion and application on existing production equipment.

[0103] In application, after completing the welding of each weld mark, the laser welding device feeds back the actual welding parameters and penetration depth data to the control device. This means that after the laser scanning of each weld mark is completed, the laser welding device not only performs the welding action but also transmits the actual power and speed parameters used in this welding, as well as the penetration depth value obtained through online detection or offline measurement, back to the control device via a data communication interface. The control device uses this feedback data for two purposes: first, it substitutes the actual welding parameters and penetration depth data as known quantities for calculating the laser absorptivity of the weld mark into the reverse calculation formula, ensuring that the data used for absorptivity calculation is completely consistent with the actual welding execution state; second, it accumulates the feedback data as a process record for reference in subsequent weld mark absorptivity calculations and parameter corrections, enabling the system to have the ability to continuously self-correct and optimize based on actual welding results.

[0104] Specifically, after the laser welding device completes the positive electrode welding, the welding software records the actual output laser power of 1700W and welding speed of 200mm / s, and triggers the penetration depth detection process to obtain the measured total penetration depth of approximately 0.49mm. These parameters and penetration depth data are then transmitted back to the control device via the communication interface. The control device combines this feedback data with the pre-welding temperature of 25℃ from the temperature measurement device and substitutes it into the laser absorptivity calculation formula. The calculated laser absorptivity of the welded electrode is approximately 3.1%, which is then stored in the system cache. After the welded electrode is completed at a compensated speed of approximately 360mm / s, the actual parameters and penetration depth data are fed back again. The control device uses this to calculate the actual absorptivity of the welded electrode and compares it with the predicted value. If a deviation exists, the compensation parameters are corrected in subsequent batches, enabling the system to have a gradual self-correcting capability. As production data accumulates, the compensation accuracy is continuously improved.

[0105] The welding software can be configured to independently set welding parameters for multiple weld stamps. This can be achieved by having the operator manually input and save the corresponding power and speed parameters for each weld stamp through the graphical interface of the welding software, or by having the control device batch-write the calculated differentiated parameters into the multi-segment parameter configuration area of ​​the welding software via a communication interface, enabling automatic batch updates of parameters without manual intervention. The laser welding device can transmit actual welding parameters and penetration depth data back to the control device via the welding equipment's own status monitoring interface, recording real-time welding process parameters and periodically pushing them to the control device in log form. Alternatively, an external welding process monitoring system can collect actual data on laser power and motion axis speed and send it to the control device through an independent communication channel, improving the independence and reliability of data acquisition.

[0106] The welding software's ability to independently set parameters for each weld stamp provides the system with the flexibility to configure optimal parameters for each weld stamp as needed. This ensures the fundamental capability for differentiated parameter compensation across multiple weld stamps without replacing welding equipment, offering advantages such as low engineering modification costs and ease of implementation. After each weld stamp is completed, the actual parameters and penetration depth data are fed back to the control device, establishing a data link between the welding result and subsequent parameter calculations. This enables the parameter compensation scheme to have continuous self-correction capabilities, and the compensation accuracy can be gradually improved as production data accumulates. The feedback data also forms a complete process data record, providing data support for the traceability of the welding process. This helps to quickly locate the cause when welding quality abnormalities occur, improving the quality management level of the production process.

[0107] Example 3 This invention also provides a computer-readable storage medium storing a computer program thereon. The computer-readable storage medium can be a non-transitory storage medium such as a read-only memory (ROM), random access memory (RAM), USB flash drive, portable hard drive, magnetic disk, or optical disk, or it can be in the form of flash memory, solid-state drive, or embedded storage chip. When the computer program is executed by a processor, it can implement all or part of the steps of the tab welding method described in Embodiment 1.

[0108] In practical applications, this computer-readable storage medium can be pre-installed in the control device of the electrode welding system, or it can be distributed independently for loading and execution by terminal devices with data processing capabilities. When the computer program in the storage medium is invoked, it performs the following operations in sequence: acquiring the surface temperature data of each weld before welding; calculating the laser absorptivity of each weld using a reverse calculation method based on the laser welding energy equation and the thermophysical parameters of the electrode; and performing differential compensation on the laser welding parameters of subsequent welds based on the differences in the laser absorptivity between each weld, so that the penetration depth of each weld tends to be consistent.

[0109] Example 4 The present invention also provides an electronic device. The electronic device includes a processor and a memory, wherein the memory is used to store executable instructions of the processor. The processor is configured to perform a tab welding method as described in Embodiment 1 by executing the executable instructions.

[0110] In this embodiment, the electronic device can be the control device of the electrode welding system itself, or it can be an industrial computer, industrial control computer, embedded controller, PLC (programmable logic controller), or host computer, independent of the welding system. This electronic device is connected to the temperature measuring device and the laser welding device via wired or wireless means. It receives the surface temperature data of each weld mark before welding from the temperature measuring device, calls the computer program stored in the memory to execute each step of the electrode welding method, and outputs the calculated differentiated welding parameters to the laser welding device to control it to perform differentiated laser welding on each weld mark.

[0111] The electronic device also includes a communication interface for data interaction with the temperature measuring device, the laser welding device, and external systems; it may also include a display device for real-time display of the laser absorption rate, welding parameter compensation value, and penetration consistency evaluation results of each weld mark.

[0112] For details of the steps involved in the specific implementation of the above storage medium and electronic device, please refer to the corresponding descriptions in the foregoing method embodiments, which will not be repeated here.

[0113] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for welding electrode tabs, characterized in that, Includes the following steps: During the process of sequentially performing multiple laser weldings on the electrode tabs that have been gathered by ultrasonic welding to form weld marks, the current temperature of the workpiece surface connected to the electrode tab is obtained before each weld mark is welded. For each weld mark to be welded starting from the second weld mark, the laser absorption rate of the current weld mark and the welded marks is calculated by reverse calculation using the laser welding energy equation and the thermophysical parameters of the tab material. Based on the laser absorption rates of the weld marks to be welded and the weld marks already welded, the relationship between the laser welding parameters is derived. Based on the relationship of the laser welding parameters, laser welding parameters are set for each weld mark to be welded, and welding is performed using the laser welding parameters.

2. The electrode tab welding method according to claim 1, characterized in that, The laser absorptivity of the weldment to be welded and the welded weldment is calculated using a backward calculation method, based on the laser welding energy equation and the thermophysical parameters of the electrode material. Calculate the laser absorption rate of the current solder mark to be soldered and the solder mark already soldered according to the following formulas: According to the laser welding energy equation: And the equation for the heat of fusion based on the thermophysical parameters of the tab material: Combining the two equations, we obtain the laser absorption rate of the corresponding solder mark: in, For welding energy; The laser welding power corresponding to the solder mark; This corresponds to the laser welding time of the solder mark; This corresponds to the laser absorption rate of the solder mark; The specific heat capacity of the tab material; This refers to the quality of the molten metal corresponding to the solder mark; This is the difference between the melting point of the tab material and the current temperature of the corresponding soldering surface.

3. The electrode tab welding method according to claim 2, characterized in that, The mass of the molten metal is calculated using the planar area of ​​the corresponding solder mark, the laser penetration depth, and the density of the electrode material. in, The mass of the molten metal; The area of ​​the solder mark; The total penetration depth of laser welding is denoted by , which is the sum of the electrode lug thickness and the penetration depth within the electrode post. The density of the tab material.

4. The electrode tab welding method according to claim 2, characterized in that, The welding time is calculated from the total length of the laser beam scanning path and the welding speed: in, For welding time; Total welding length; This refers to the laser welding speed.

5. The electrode tab welding method according to claim 3, characterized in that, The total penetration depth of laser welding with weld marks is the penetration depth actually measured after welding; The total penetration depth of the laser welding of the weld mark to be welded is the penetration depth obtained according to a preset correspondence, which is the correspondence between laser welding power, welding speed, temperature and penetration depth.

6. The electrode tab welding method according to claim 1, characterized in that, The laser welding parameters include laser welding power and laser welding speed. The laser welding parameters are derived based on the laser absorptivity of the weld mark to be welded and the weld mark already welded, specifically as follows: in, The laser welding power of the weld mark. The laser welding power is the value of the desired solder mark. The laser welding speed of the welded solder mark. The laser welding speed for the desired solder mark. The laser absorption rate of the solder mark is the value of the welded area. The laser absorption rate of the solder mark to be soldered. , , The melting point of the tab material. The surface temperature of the workpiece before welding is indicated by the weld mark. The surface temperature of the workpiece before welding is required.

7. The electrode tab welding method according to claim 6, characterized in that, The laser welding power of the weld mark to be welded is consistent with the laser power of the weld mark already welded. The laser welding parameters are set to the laser welding speed of the weld mark to be welded. Based on the relationship of the laser welding parameters, laser welding parameters are set for each weld mark to be welded, specifically: in, The welding speed for the desired solder joint; The welding speed of the welded solder marks; The laser absorption rate of the solder mark; The laser absorption rate of the solder mark to be soldered; The difference between the melting point of the tab material and the surface temperature of the workpiece before welding the solder mark; The difference between the melting point of the tab material and the surface temperature of the workpiece before welding is called.

8. A tab welding system, characterized in that, include: An ultrasonic welding device is used to weld multiple layers of electrode tabs together into one piece. A temperature measuring device is used to measure the current temperature of the workpiece welding surface in real time before each laser welding stamp and output the temperature data. A laser welding device is used to perform laser welding on each weld mark, and supports setting the laser welding power and laser welding speed individually for each weld mark; The control device is connected to the temperature measuring device and the laser welding device respectively. It is used to receive the welding surface temperature data of each weld mark, calculate the laser absorptivity of each weld mark by reverse calculation based on the laser welding energy equation and the thermophysical parameters of copper, and perform differential compensation for the laser welding parameters line by line based on the difference in the laser absorptivity between each weld mark.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the tab welding method as described in any one of claims 1 to 7.

10. An electronic device, characterized in that, include: processor; Memory for storing the executable instructions of the processor; The processor is configured to perform the tab welding method as described in any one of claims 1 to 7 by executing the executable instructions.

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