An automatic spot welding method and system for new energy battery packaging

Abstract

The present application relates to the technical field of welding control, in particular to an automatic spot welding method and system for new energy battery packaging. The method analyzes the reference historical welding process in the pressing stage, determines the impedance peak value in the current spot welding process, analyzes the similar changes of the impedance peak value and the similar fluctuations of the spot welding current, and the similar situation of the existing welding spot, determines the reference index of the reference historical spot welding process; based on the reference degree of the reference historical spot welding stage, the flow duration after the impedance peak value and the welding current characteristic parameters are determined, and the subsequent current spot welding process is adjusted in real time. The present application monitors the multi-dimensional historical similarity of the impedance value in the flow stage, dynamically adjusts the subsequent flow parameters, reduces the abnormal conditions such as false welding, overwelding or welding spot resistance increase, and improves the spot welding quality stability and safety.

Description

Technical Field

[0001] This invention relates to the field of welding control technology, specifically to an automated spot welding method and system for new energy battery packaging. Background Technology

[0002] A complete new energy battery module typically consists of dozens of modules, and each sub-module is composed of multiple individual batteries connected in series and parallel. Currently, the series and parallel connection of individual new energy batteries is usually achieved by welding. Battery spot welding technology is one of the most widely used welding technologies in the parallel connection of new energy batteries. The welding quality not only affects the service life of the new energy battery pack, but also the safety of the new energy battery during charging and discharging.

[0003] Currently, resistance welding is widely used in the welding process of new energy battery modules. This involves applying pressure to metal tabs through electrodes while simultaneously passing a large current through the contact surface. The instantaneous heat generated by the contact resistance melts the metal locally, forming a weld. During the welding process, process parameters such as welding current, pressure, and electrode thickness are susceptible to slight fluctuations. If these are not adjusted promptly, abnormalities such as incomplete welds, over-welds, or increased weld resistance can easily occur. This can lead to insufficient weld strength, potentially resulting in increased battery internal resistance and decreased charge / discharge efficiency. Summary of the Invention

[0004] To address the technical problems in the prior art, the present invention aims to provide an automated spot welding method and system for new energy battery packaging, the specific technical solution of which is as follows:

[0005] This invention provides an automated spot welding method for packaging new energy batteries, the method comprising:

[0006] Obtain the final pressing force in the pressing stage of the current spot welding process, as well as the impedance value and current data in the current flow stage; based on the similarity of the final pressing force of the current spot welding process, select reference historical spot welding processes from historical spot welding processes;

[0007] After the impedance peak occurs in the current spot welding process, analyze the approximate changes in the previous impedance value and current data between the current spot welding process and the reference historical spot welding process, as well as the similarity of the distribution of existing weld points, to obtain reference indicators for each reference historical spot welding process.

[0008] Based on the spot welding time after the impedance peak and reference indicators of all historical spot welding processes, the duration reference of the current spot welding process is obtained.

[0009] The effectiveness of impedance value drop after impedance peak is analyzed for each reference historical spot welding process. Combined with reference indicators, the effective reference coefficient of each reference historical spot welding process is obtained. The distribution change characteristics of current data at each moment after impedance peak for all reference historical spot welding processes are adjusted by the effective reference coefficient to obtain the current characteristic reference degree at the moment of the current spot welding process.

[0010] Based on the duration reference and the current characteristic reference at any moment of the current spot welding process, adjustments are made to the current-carrying stage after the impedance peak of the current spot welding process.

[0011] Furthermore, the process of obtaining the reference historical spot welding process includes:

[0012] Obtain the final pressing force of each historical spot welding process in the pressing stage, calculate the difference between the final pressing force of each historical spot welding process and the current spot welding process, perform negative correlation mapping and normalization processing to obtain the pressing similarity;

[0013] Historical spot welding processes with a pressing similarity greater than a preset similarity threshold are used as reference historical spot welding processes.

[0014] Furthermore, current methods for obtaining the impedance peak value in the spot welding process include:

[0015] During the current flow stage of the current spot welding process, the impedance difference between each moment and the previous moment is taken as the impedance change value at each moment.

[0016] After a moment when the impedance change value is positive, when two consecutive moments when the impedance change value is not positive occur, the first moment when the impedance change value is not positive is taken as the peak moment, and the impedance value corresponding to the peak moment is the impedance peak value.

[0017] Furthermore, the method for obtaining the reference indicator includes:

[0018] Between each reference historical spot welding process and the current spot welding process, based on the similarity of the time value of reaching the resistance peak and the similarity of the current data fluctuation during the period of reaching the resistance peak, the approximate index of the spot welding parameters for each reference historical spot welding process is determined.

[0019] Between each reference historical spot welding process and the current spot welding process, the approximate index of the weld point distribution for each reference historical spot welding process is determined based on the similarity of the distribution of the number of existing weld point locations and the similarity of the distribution of distances from the current weld point.

[0020] By combining the approximate indicators of spot welding parameters and weld point distribution for each historical spot welding process, reference indicators for each historical spot welding process are obtained.

[0021] Furthermore, the method for obtaining the approximate index of the spot welding parameters includes:

[0022] For any spot welding process, the duration of the impedance peak value at the time corresponding to the initial time and the duration of the initial time are obtained as the peak duration of the spot welding process; the impedance value at the initial time and the impedance peak value are combined into a pair as the impedance characteristic group of the spot welding process; the current data are curve fitted on the time sequence from the initial time to the time corresponding to the impedance peak value to obtain the current fluctuation curve of the spot welding process.

[0023] Between each reference historical spot welding process and the current spot welding process, the difference between the peak durations is calculated and negative correlation mapping and normalization are performed to obtain the duration approximation of each reference historical spot welding process; the similarity between impedance characteristic groups is calculated to obtain the characteristic approximation of each reference historical spot welding process; the correlation between current fluctuation curves is calculated to obtain the current fluctuation approximation of each reference historical spot welding process.

[0024] The product of the approximation of the duration, the approximation of the characteristics, and the approximation of the current fluctuation of each reference historical spot welding process is used as the approximation index of the spot welding parameters for each reference historical spot welding process.

[0025] Furthermore, the method for obtaining the approximate index of the solder joint distribution includes:

[0026] For any spot welding process, calculate the average distance between all existing weld point positions and the current spot welding position, and use it as the positional distribution degree of the spot welding process; use the number of existing weld points in the spot welding process as the quantity distribution degree of the spot welding process.

[0027] Between the current spot welding process and each reference historical spot welding process, the difference in position distribution degree is calculated and negative correlation mapping and normalization are performed to obtain the approximate position index of each reference historical spot welding process; the difference in quantity distribution degree is calculated and negative correlation mapping and normalization are performed to obtain the approximate quantity index of each reference historical spot welding process.

[0028] The product of the approximate position index and the approximate quantity index of each reference historical spot welding process is used as the approximate index of the weld point distribution for each reference historical spot welding process.

[0029] Furthermore, the method for obtaining the duration reference degree includes:

[0030] The ratio between the reference index of each historical spot welding process and the reference index and value of all historical spot welding processes is used as the reference weight of each historical spot welding process.

[0031] Obtain the spot welding time after the impedance peak for each reference historical spot welding process; use the reference weight as the weight to calculate the average of the spot welding times of all reference historical spot welding processes to obtain the duration reference value of the current spot welding process.

[0032] Furthermore, the method for obtaining the effective reference coefficient includes:

[0033] The average slope of the impedance value after the impedance peak is obtained for each reference historical spot welding process, which is used as the drop rate of each reference historical spot welding process; the difference between the drop rate of each reference historical spot welding process and the expected drop rate is calculated and negatively correlated to obtain the drop effectiveness of each reference historical spot welding process.

[0034] The product of the decrease effectiveness of each reference historical spot welding process and the reference index is normalized and used as the effective reference coefficient for each reference historical spot welding process.

[0035] Furthermore, the method for obtaining the current characteristic reference degree includes:

[0036] The current data at each moment after the impedance peak of all historical spot welding processes are weighted and averaged using the effective reference coefficient as the weight to obtain the reference degree of the current data at each subsequent moment of the current spot welding process.

[0037] The decreasing reference level of the current process is obtained by weighting the slope of the current data at each moment after the impedance peak of all historical spot welding processes using the effective reference coefficient as the weight:

[0038] The current data reference degree and the descent reference degree at each moment are combined to serve as the current characteristic reference degree at each subsequent moment of the current spot welding process.

[0039] The present invention also provides an automated spot welding system for new energy battery packaging, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the automated spot welding method for new energy battery packaging described above.

[0040] The present invention has the following beneficial effects:

[0041] This invention selects reference historical welding processes from historical spot welding processes by analyzing the similarity of the final pressing force in the pressing stage. Using historical data from similar processes in previous stages as a reference makes subsequent adjustments more reliable. After determining the impedance peak value in the current spot welding process, it further analyzes the similarity of impedance peak value changes and spot welding current fluctuations, reflecting the closeness between spot welding parameters in the initial spot welding process. Simultaneously, it analyzes the similarity of existing weld points, considering the current shunting effect caused by spot welding. Combined with the analysis of weld point consistency, it determines reference indicators for the historical spot welding process. By analyzing the similarity between various parameters of the historical spot welding stage and the current spot welding process, it determines the reference level of the historical spot welding stage, making adjustments based on the historical spot welding process more accurate. Then, based on the reference level of the historical spot welding stage, it determines the current carrying time after the impedance peak and the characteristic parameters of the welding current, and adjusts the spot welding time and welding current in real time for the subsequent stages of the current spot welding process, making automated adjustment more reliable. This invention monitors the impedance values ​​during the current flow stage using a multi-dimensional historical similarity method, dynamically adjusts subsequent flow parameters, reduces abnormal situations such as poor soldering, over-soldering, or increased solder joint resistance, and improves the stability and safety of spot welding quality. Attached Figure Description

[0042] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart of an automated spot welding method for packaging new energy batteries according to an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram illustrating the impedance change during a standard spot welding process, provided as an embodiment of the present invention.

[0045] Figure 3 A flowchart illustrating a method for obtaining reference indicators according to an embodiment of the present invention. Detailed Implementation

[0046] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an automated spot welding method and system for new energy battery packaging proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0048] The following description, in conjunction with the accompanying drawings, details the specific solution of the automated spot welding method and system for new energy battery packaging provided by this invention.

[0049] Please see Figure 1 The diagram illustrates an automated spot welding method for new energy battery packaging according to an embodiment of the present invention. The method includes the following steps:

[0050] S1: Obtain the final pressing force in the pressing stage of the current spot welding process, as well as the impedance value and current data in the current flow stage; based on the similarity of the final pressing force of the current spot welding process, select reference historical spot welding processes from historical spot welding processes.

[0051] In this embodiment of the invention, the welding process in automated spot welding control involves four steps: pressing, flow, pressure holding, and release. During the pressing stage, the fixture presses the electrode tab and the welding piece together to form an initial contact surface. The pressing force during welding is acquired by a load sensor. The pressing stage consists of two phases: pre-pressing and pressurization. In the pre-pressing stage, a first-stage light pressure is applied to ensure tight contact between the electrode tab and the electrode, forming a reference contact resistance, thereby eliminating surface micro-unevenness and reducing the initial contact resistance. Then, the pressure is increased to the process set value to complete the pressing. The pressing force at this point is recorded as the final pressing force. It should be noted that the pressing stage settings can be adjusted by the implementer according to the specific implementation scenario, which will not be elaborated here.

[0052] After pressing, the current flow process begins. Welding current is applied instantaneously to the contact surface, generating resistance heat that causes localized melting or plastic deformation of the metal, forming a weld nugget. The current during spot welding is controlled in real-time by a spot welding current controller. Since the thickness of the welding material is not uniform, spot welding based solely on initial parameters can lead to over-welding or incomplete welding in areas with thin or thick welding material. Therefore, real-time adjustment of the spot welding current is necessary.

[0053] In this embodiment of the invention, current and voltage data during the welding process are collected in real time using a high-precision current transformer and a voltage sensor, and the welding impedance value is derived based on the current and voltage data. The acquisition frequency can be 100kHz. The specific acquisition settings can be adjusted by the implementer according to the specific implementation scenario, and are not limited here.

[0054] Please see Figure 2 This diagram illustrates the impedance change during a standard spot welding process according to an embodiment of the present invention. At the beginning of current flow, although pre-pressurization has been completed during the pressing stage, there may still be minute gaps, surface oxide layers, or oil contaminants at the contact interface between the tab and the electrode. After current is applied, the continuous electrode pressure further flattens the micro-unevenness of the interface, increasing the actual contact area. Furthermore, the initial heat generated by the current quickly breaks down the oxide layer and evaporates the oil contaminants, reducing contact resistance. This leads to a rapid decrease in impedance, reflected in the impedance drop segment at the initial stage of current flow on the curve.

[0055] Once the contact state stabilizes, the heat continuously generated by the current causes the local temperature of the electrode metal to rise rapidly to its melting point, initiating a transition from solid to liquid state and forming a liquid weld nugget. The resistivity of liquid metal is much higher than that of solid metal; for example, the resistivity of liquid copper is about twice that of solid copper. Furthermore, the melting process may be accompanied by localized metal splashing and the generation of tiny bubbles, reducing the effective cross-sectional area of ​​the current path. At this point, the impedance value rises continuously from its lowest point until the weld nugget melts to its maximum, at which point the liquid metal constitutes the largest proportion, the current path is most obstructed, and the impedance reaches its peak.

[0056] After the peak value, the amount of melt in the weld nugget is sufficient to form a qualified weld joint. At this point, the current is still flowing, but the amount of metal melted no longer increases. Simultaneously, heat diffuses to the surrounding unmelted metal, causing the local temperature to slowly decrease. Some liquid weld nuggets begin to transform into solids, and the resistivity gradually decreases. In addition, bubbles inside the weld nugget gradually escape, spattering stops, the current path becomes more stable, and the effective cross-sectional area recovers. At this point, the impedance value slowly decreases from the peak value until the current-carrying stage ends, preparing for subsequent pressure holding and curing.

[0057] To more accurately and efficiently adjust the current spot welding process, historical data with similar conditions in the pressing stage are used for preliminary screening to obtain reference historical data for subsequent adjustment analysis, making the adjustment basis more reliable. In this embodiment of the invention, the final pressing force of each historical spot welding process in the pressing stage is obtained. The difference between the final pressing force of each historical spot welding process and the current spot welding process is calculated, negatively correlated, and normalized to obtain the pressing similarity. The smaller the difference, the more similar the initial process conditions in the pressing stage are, and the more suitable they are for reference. It should be noted that negative correlation mapping and normalization are techniques well known to those skilled in the art. Negative correlation mapping can be in the form of a negative exponential power with the natural constant as the base or inverse proportional value form. The choice of normalization can be linear normalization or standard normalization, etc., and the specific method is not limited here.

[0058] Finally, historical spot welding processes with a similarity to the preset similarity threshold are used as reference historical spot welding processes, and relatively similar historical spot welding processes are selected for reference analysis. In this embodiment of the invention, the preset similarity threshold is set to 0.7, and the specific value can be adjusted by the implementer and is not limited here.

[0059] S2: After the impedance peak occurs in the current spot welding process, analyze the approximate changes in the previous impedance value and current data between the current spot welding process and the reference historical spot welding process, as well as the similarity of the distribution of existing weld points, to obtain the reference index for each reference historical spot welding process.

[0060] Since the impedance peak can reflect the current welding state, the occurrence of the impedance peak is related to the spot welding current shunting and the thickness of the welding material. After the impedance peak occurs in the current spot welding process, the current working condition can be basically determined. At this time, through the approximate state analysis of the previous process, the reference reliability of each reference historical spot welding process can be further evaluated.

[0061] Therefore, it is necessary to first determine the impedance peak value during the current spot welding process. Once a peak value is detected, adjustments and analyses can be performed. In this embodiment of the invention, during the current-carrying phase of the current spot welding process, the impedance difference between each moment and the previous moment is taken as the impedance change value at each moment, reflecting the degree of impedance change. When the impedance change value is positive, it indicates that the impedance value has entered the boost phase, and will reach its peak value in a short time. Therefore, when two consecutive adjacent impedance change values ​​are not positive, it indicates a peak transition, and the impedance value drops. The first moment when the impedance change value is not positive is taken as the peak moment, and the impedance value corresponding to the peak moment is the impedance peak value.

[0062] After detecting the impedance peak during the current spot welding process, an analysis is performed on similar cases. The reliability of different historical reference data is comprehensively evaluated from two dimensions: the initial spot welding parameters and the current shunting effect caused by the existing weld point location. Preferably, in this embodiment of the invention, the method for obtaining the reference indicators for each historical spot welding process is described in [reference needed]. Figure 3 The diagram illustrates a flowchart of a method for obtaining a reference indicator according to an embodiment of the present invention, the method comprising the following steps:

[0063] S201: Between each reference historical spot welding process and the current spot welding process, based on the similarity of the time value of reaching the resistance peak and the similarity of the current data fluctuation during the period of reaching the resistance peak, determine the approximate index of the spot welding parameters for each reference historical spot welding process.

[0064] When referencing historical spot welding processes, the closer the time to reach the peak impedance and the closer the numerical state of the peak impedance, the more similar the spot welding conditions. Furthermore, considering the approximate parameters of the applied current fluctuations during this process, and combining the similarity between the welding material melting state and the current data parameters, the degree of approximation in the spot welding parameters is reflected.

[0065] In this embodiment of the invention, for any spot welding process, the duration of the time corresponding to the impedance peak and the initial time are obtained as the peak duration of the spot welding process. The impedance value corresponding to the initial time and the impedance peak value are combined into a binary tuple as the impedance characteristic group of the spot welding process, reflecting the initial impedance state and the peak state. On the time sequence from the initial time to the time corresponding to the impedance peak, the current data is curve fitted to obtain the current fluctuation curve of the spot welding process. It should be noted that curve fitting is a technique well known to those skilled in the art and will not be described in detail here.

[0066] Then, between each reference historical spot welding process and the current spot welding process, the difference between the peak duration is calculated and negative correlation mapping and normalization are performed to obtain the duration approximation of each reference historical spot welding process. The smaller the difference in peak duration, the closer the peak time is.

[0067] Further calculations are made to determine the similarity between impedance characteristic groups, obtaining the characteristic approximation degree of each reference historical spot welding process. In one embodiment of the present invention, the distance between two impedance characteristic groups can be calculated using Euclidean distance, followed by negative correlation mapping and normalization to obtain the characteristic approximation degree. The greater the characteristic approximation degree, the higher the numerical similarity between the initial impedance and the impedance peak. It should be noted that the calculation of the similarity between binary groups is a technique well-known to those skilled in the art, and Manhattan distance, etc., can also be used, without limitation.

[0068] Further calculations are made to determine the correlation between current fluctuation curves, obtaining the approximation of current fluctuations for each reference historical spot welding process. In this embodiment of the invention, the Pearson correlation coefficient is used to calculate the correlation between two current fluctuation curves to obtain the approximation of current fluctuations. The higher the correlation between the fluctuation curves, the more similar they are. It should be noted that the calculation of correlation between sequences is a technique well-known to those skilled in the art and is not limited herein.

[0069] Finally, the product of the approximation of the duration, the approximation of the characteristics, and the approximation of the current fluctuation of each reference historical spot welding process is used as the approximation index of the spot welding parameters for each reference historical spot welding process. The larger the approximation index of the spot welding parameters, the closer the corresponding reference historical spot welding parameters are to the current working condition, and the higher the reference value.

[0070] S202: Between each reference historical spot welding process and the current spot welding process, determine the approximate index of the weld point distribution for each reference historical spot welding process based on the similarity of the distribution of the number of existing weld point locations and the similarity of the distribution of distances from the current weld point.

[0071] Because spot welding creates weld joints, the welding current will form a conductive loop through these joints during subsequent spot welding processes, potentially diverting the welding current and further impacting welding efficiency. The more weld joints there are, the more severe the current diversion, and the closer the existing weld joints are to the current spot welding location, the greater the impact of the current diversion. Therefore, focusing on both the number and distance of existing weld joint locations allows for a more comprehensive assessment of the reliability of historical data.

[0072] In this embodiment of the invention, for any spot welding process, the average distance between all existing weld point locations and the current spot welding location is calculated as the positional distribution degree of the spot welding process, measuring the impact on the current spot welding location. The number of existing weld points in the spot welding process is used as the quantity distribution degree of the spot welding process.

[0073] Then, the difference in position distribution degree between the current spot welding process and each reference historical spot welding process is calculated and negative correlation mapping and normalization are performed to obtain the position approximation index of each reference historical spot welding process. The larger the position approximation index, the more similar the situation is under the influence of existing weld points.

[0074] Then, the difference in quantity distribution degree is calculated and negative correlation mapping and normalization are performed to obtain the quantity approximation index of each reference historical spot welding process. The larger the quantity approximation index, the more similar the influence on the quantity of weld points.

[0075] Finally, the product of the approximate position index and the approximate quantity index of each reference historical spot welding process is used as the approximate weld point distribution index of each reference historical spot welding process. The larger the approximate weld point distribution index, the higher the similarity between this reference historical spot welding process and the current one in terms of the influence of weld points, and the higher the referenceability of this reference historical spot welding process.

[0076] S203: By combining the approximate indicators of spot welding parameters and the approximate indicators of weld point distribution for each reference historical spot welding process, a reference indicator for each reference historical spot welding process is obtained.

[0077] Finally, the reference index for referencing historical spot welding processes is quantified by combining two aspects. In this embodiment of the invention, the product of the approximate index of spot welding parameters and the approximate index of weld point distribution is used as the reference index for each historical spot welding process. The larger the reference index, the higher the reference reliability of the corresponding historical spot welding process.

[0078] S3: Based on the spot welding time and reference indicators after the impedance peak of all reference historical spot welding processes, obtain the duration reference degree of the current spot welding process; analyze the effectiveness of the impedance value drop after the impedance peak of each reference historical spot welding process, and obtain the effective reference coefficient of each reference historical spot welding process by combining the reference indicators; adjust the distribution change characteristics of the current data at each moment after the impedance peak of all reference historical spot welding processes by the effective reference coefficient to obtain the current characteristic reference degree of the current spot welding process.

[0079] After analyzing the reference level of the historical spot welding process, the duration of current application and current application characteristics following the impedance peak in the historical spot welding process can be combined to provide an adjustment basis for the current spot welding process.

[0080] First, based on the duration of impedance peaks following historical spot welding processes, a reference duration is provided for the current spot welding process. In this embodiment of the invention, the method for obtaining the duration reference includes:

[0081] The ratio of the reference index of each historical spot welding process to the sum of the reference indexes of all historical spot welding processes is used as the reference weight for each historical spot welding process, quantifying the proportion of each historical spot welding process in the overall analysis. The spot welding duration after the impedance peak is obtained for each historical spot welding process. The reference weight is used as the weight to calculate the weighted average of the spot welding durations of all historical spot welding processes, obtaining the duration reference value of the current spot welding process. By combining the weighted average and all historical reference data, the optimal current application duration for the current spot welding process is obtained.

[0082] Furthermore, based on the reference historical spot welding process, the decrease in resistance value after the impedance peak is analyzed to determine the degree of resistance drop in this spot welding case. Both excessive and insufficient resistance drop can lead to abnormal weld joint conditions. For example, if the drop is too fast, it indicates that the heating efficiency during the spot welding process is too high, which may result in spatter, cold welds, and other issues.

[0083] Therefore, adjusting the reference index based on the impedance value fluctuation and decrease makes subsequent adjustments to the current spot welding process based on the current change characteristics of historical spot welding processes more accurate and reliable. In this embodiment of the invention, the method for obtaining the effective reference coefficient based on the impedance value decrease includes:

[0084] The average slope of the impedance value after the impedance peak is obtained for each reference historical spot welding process, and this slope is used as the drop rate of each reference historical spot welding process, reflecting the rate of impedance value drop. The difference between the drop rate and the expected drop rate of each reference historical spot welding process is calculated and negatively correlated to obtain the drop effectiveness of each reference historical spot welding process. The smaller the difference between the drop rate and the expected drop rate, the lower the possible abnormal deviation and the more reliable the reference. In this embodiment of the invention, the expected drop rate can be set to 5, and the specific value can be adjusted by the implementer and is not limited here.

[0085] Then, the product of the descent effectiveness and the reference index of each reference historical spot welding process is normalized and used as the effective reference coefficient for each reference historical spot welding process. By adjusting the descent effectiveness, the reference historical spot welding process is made more accurate in subsequent current characteristic analysis.

[0086] Based on the current data from historical spot welding processes, and combined with effective reference coefficients, reference current data characteristics are provided for the current spot welding process. In this embodiment of the invention, the method for obtaining the current characteristic reference degree includes:

[0087] By using the effective reference coefficient as the weight, the current data of all reference historical spot welding processes at each moment after the impedance peak are weighted and averaged to obtain the reference degree of the current data at each subsequent moment of the current spot welding process, which characterizes the reference value distribution state of the current data at each moment of the subsequent impedance peak.

[0088] By using the effective reference coefficient as the weight, the slope of the current data at each moment after the impedance peak of all reference historical spot welding processes is weighted and averaged to obtain the decreasing reference degree of the current spot welding process, which characterizes the reference reduction rate of the current data at each subsequent moment.

[0089] Finally, the reference degree of current data and the reference degree of descent at each moment are combined as the reference degree of current characteristics at each subsequent moment of the current spot welding process, providing a reference basis for adjusting the current data of the current spot welding process.

[0090] S4: Based on the duration reference degree and the current characteristic reference degree at the moment of the current spot welding process, adjust the current flow stage after the impedance peak of the current spot welding process.

[0091] After obtaining the duration reference and current characteristic reference of the current spot welding process, the subsequent current data and current duration in the current spot welding process can be adjusted by the spot welding current regulator. That is, the actual current rate is reduced and the current data is smoothed according to the current characteristic reference, and the current application duration is maintained at the duration reference. In this embodiment of the invention, the smoothing filtering method is a well-known technique and will not be described in detail here. This completes the current flow stage. After the current flow is completed, the electrode pressure is maintained to allow the weld nugget to cool and solidify under pressure. After the pressure holding is completed, the electrode force is quickly released, the workpiece is separated, and the welding cycle is completed. This cycle is repeated until the new energy battery packaging is completed.

[0092] In summary, this invention selects reference historical welding processes from historical spot welding processes by analyzing the similarity of the final pressing force in the pressing stage. Using historical data from similar processes in previous stages as a reference makes subsequent adjustments more reliable. After determining the impedance peak value in the current spot welding process, it further analyzes the similarity of impedance peak value changes and spot welding current fluctuations, reflecting the closeness between spot welding parameters in the initial spot welding process. Simultaneously, it analyzes the similarity of existing weld points, considering the current shunting effect caused by spot welding. Combined with the analysis of weld point consistency, it determines reference indicators for the historical spot welding process. By analyzing the similarity between various parameters of the historical spot welding stage and the current spot welding process, it determines the reference level of the historical spot welding stage, making adjustments based on the historical spot welding process more accurate. Then, based on the reference level of the historical spot welding stage, it determines the current carrying time after the impedance peak value and the characteristic parameters of the welding current, and adjusts the spot welding time and welding current in real time for the subsequent stages of the current spot welding process, making automated adjustment more reliable. This invention monitors the impedance values ​​during the current flow stage using a multi-dimensional historical similarity method, dynamically adjusts subsequent flow parameters, reduces abnormal situations such as poor soldering, over-soldering, or increased solder joint resistance, and improves the stability and safety of spot welding quality.

[0093] The present invention also provides an automated spot welding system for new energy battery packaging, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the automated spot welding method for new energy battery packaging described above.

[0094] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0095] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. An automated spot welding method for packaging new energy batteries, characterized in that, The method includes: Obtain the final pressing force in the pressing stage of the current spot welding process, as well as the impedance value and current data in the current flow stage; based on the similarity of the final pressing force of the current spot welding process, select reference historical spot welding processes from historical spot welding processes; After the impedance peak occurs in the current spot welding process, analyze the approximate changes in the previous impedance value and current data between the current spot welding process and the reference historical spot welding process, as well as the similarity of the distribution of existing weld points, to obtain reference indicators for each reference historical spot welding process. Based on the spot welding time after the impedance peak and reference indicators of all historical spot welding processes, the duration reference of the current spot welding process is obtained. The effectiveness of impedance value drop after impedance peak is analyzed for each reference historical spot welding process. Combined with reference indicators, the effective reference coefficient of each reference historical spot welding process is obtained. The distribution change characteristics of current data at each moment after impedance peak of all reference historical spot welding processes are adjusted by the effective reference coefficient to obtain the current characteristic reference degree at the current spot welding process moment. Based on the duration reference and the current characteristic reference at any moment of the current spot welding process, adjustments are made to the current-carrying stage after the impedance peak of the current spot welding process. The method for obtaining the effective reference coefficient includes: The average slope of the impedance value after the impedance peak is obtained for each reference historical spot welding process, which is used as the drop rate of each reference historical spot welding process; the difference between the drop rate of each reference historical spot welding process and the expected drop rate is calculated and negatively correlated to obtain the drop effectiveness of each reference historical spot welding process. The product of the decrease effectiveness of each reference historical spot welding process and the reference index is normalized and used as the effective reference coefficient for each reference historical spot welding process.

2. The automated spot welding method for new energy battery packaging according to claim 1, characterized in that, The process of obtaining the reference historical spot welding process includes: Obtain the final pressing force of each historical spot welding process in the pressing stage, calculate the difference between the final pressing force of each historical spot welding process and the current spot welding process, perform negative correlation mapping and normalization processing to obtain the pressing similarity; Historical spot welding processes with a pressing similarity greater than a preset similarity threshold are used as reference historical spot welding processes.

3. The automated spot welding method for new energy battery packaging according to claim 1, characterized in that, The current methods for obtaining the impedance peak value in the spot welding process include: During the current flow stage of the current spot welding process, the impedance difference between each moment and the previous moment is taken as the impedance change value at each moment. After a moment when the impedance change value is positive, when two consecutive moments when the impedance change value is not positive occur, the first moment when the impedance change value is not positive is taken as the peak moment, and the impedance value corresponding to the peak moment is the impedance peak value.

4. The automated spot welding method for new energy battery packaging according to claim 1, characterized in that, The methods for obtaining the reference indicators include: Between each reference historical spot welding process and the current spot welding process, based on the similarity of the time value of reaching the resistance peak and the similarity of the current data fluctuation during the period of reaching the resistance peak, the approximate index of the spot welding parameters for each reference historical spot welding process is determined. Between each reference historical spot welding process and the current spot welding process, the approximate index of the weld point distribution for each reference historical spot welding process is determined based on the similarity of the distribution of the number of existing weld point locations and the similarity of the distribution of distances from the current weld point. By combining the approximate indicators of spot welding parameters and weld point distribution for each historical spot welding process, reference indicators for each historical spot welding process are obtained.

5. The automated spot welding method for new energy battery packaging according to claim 4, characterized in that, The method for obtaining the approximate index of the spot welding parameters includes: For any spot welding process, the duration of the impedance peak value at the time corresponding to the initial time and the duration of the initial time are obtained as the peak duration of the spot welding process; the impedance value at the initial time and the impedance peak value are combined into a pair as the impedance characteristic group of the spot welding process; the current data are curve fitted on the time sequence from the initial time to the time corresponding to the impedance peak value to obtain the current fluctuation curve of the spot welding process. Between each reference historical spot welding process and the current spot welding process, the difference between the peak durations is calculated and negative correlation mapping and normalization are performed to obtain the duration approximation of each reference historical spot welding process; the similarity between impedance characteristic groups is calculated to obtain the characteristic approximation of each reference historical spot welding process; the correlation between current fluctuation curves is calculated to obtain the current fluctuation approximation of each reference historical spot welding process. The product of the approximation of the duration, the approximation of the characteristics, and the approximation of the current fluctuation of each reference historical spot welding process is used as the approximation index of the spot welding parameters for each reference historical spot welding process.

6. The automated spot welding method for new energy battery packaging according to claim 4, characterized in that, The method for obtaining the approximate index of the solder joint distribution includes: For any spot welding process, calculate the average distance between all existing weld point positions and the current spot welding position, and use it as the positional distribution degree of the spot welding process; use the number of existing weld points in the spot welding process as the quantity distribution degree of the spot welding process. Between the current spot welding process and each reference historical spot welding process, the difference in position distribution degree is calculated and negative correlation mapping and normalization are performed to obtain the approximate position index of each reference historical spot welding process; the difference in quantity distribution degree is calculated and negative correlation mapping and normalization are performed to obtain the approximate quantity index of each reference historical spot welding process. The product of the approximate position index and the approximate quantity index of each reference historical spot welding process is used as the approximate index of the weld point distribution for each reference historical spot welding process.

7. The automated spot welding method for new energy battery packaging according to claim 1, characterized in that, The method for obtaining the duration reference degree includes: The ratio between the reference index of each historical spot welding process and the reference index and value of all historical spot welding processes is used as the reference weight of each historical spot welding process. Obtain the spot welding time after the impedance peak for each reference historical spot welding process; use the reference weight as the weight to calculate the average of the spot welding times of all reference historical spot welding processes to obtain the duration reference value of the current spot welding process.

8. The automated spot welding method for new energy battery packaging according to claim 1, characterized in that, The method for obtaining the current characteristic reference degree includes: The current data at each moment after the impedance peak of all historical spot welding processes are weighted and averaged using the effective reference coefficient as the weight to obtain the reference degree of the current data at each subsequent moment of the current spot welding process. The decreasing reference level of the current process is obtained by weighting the slope of the current data at each moment after the impedance peak of all historical spot welding processes using the effective reference coefficient as the weight: The current data reference degree and the descent reference degree at each moment are combined to serve as the current characteristic reference degree at each subsequent moment of the current spot welding process.

9. An automated spot welding system for new energy battery packaging, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the automated spot welding method for packaging new energy batteries as described in any one of claims 1 to 8.

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