A production process for a diaphragm finishing unidirectional roller based on the winding process

Abstract

This invention relates to the field of battery manufacturing technology, and more particularly to a production process based on a unidirectional roller for the separator finishing in the winding process. The process includes: acquiring end-face and side-face images of a bare battery cell wound on a winding machine; determining whether the interlayer spacing uniformity of the bare battery cell meets the standard based on the interlayer gap uniformity index, and determining the preset pressure and rotation speed applied to the winding machine by the unidirectional roller based on the difference; determining whether the side flatness of the bare battery cell is qualified based on micro-undulation characterization parameters, and determining the preset number of rotations and the increase in preset pressure for the winding machine based on the relative difference; determining whether the winding stability of the bare battery cell meets the standard based on the batch gap fluctuation rate, and determining to increase the tension applied to the battery cell strip during the next batch winding process and increase the number of rotations based on the ratio; after winding, an adhesive applicator applies a termination tape to the qualified bare battery cell. This invention improves the winding efficiency of bare battery cells in the winding process.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, and in particular to a production process for a unidirectional roller for the diaphragm finishing process based on the winding process. Background Technology

[0002] In the lithium battery production process, the winding process involves winding the positive electrode sheet, negative electrode sheet, and separator in a specific order to form the basic shape of the cell. The winding machine winds the slit electrode sheet and separator into the core. In the winding process, a series of technical problems are prone to occur at the final stage of separator winding. If the interlayer spacing of the separator winding is uneven, it will cause an imbalance in the electric field distribution inside the battery, which will result in the battery capacity not being fully released and the charging and discharging efficiency being greatly reduced. In addition, once wrinkles are generated during the separator winding process, it will not only cause local changes in the thickness of the separator, affecting lithium ion transport, but may also cause separator damage due to stress concentration during subsequent battery use, resulting in a short circuit between the positive and negative electrodes and creating a serious safety hazard.

[0003] Chinese Patent Application Publication No. CN119725346A discloses an electrode composite device, a bare cell winding device, and a bare cell winding method, comprising: a first composite roller assembly, including a first composite roller and a second composite roller, the first composite roller and the second composite roller being arranged opposite each other, the first composite roller and the second composite roller being used to sequentially stack and composite a first separator, a first electrode, and a second separator together; and a side separator composite assembly, used to composite the portion of the first separator extending beyond the side of the first electrode with the portion of the second separator extending beyond the side of the first electrode.

[0004] However, the existing technology has the following problems: after the positive and negative electrode sheets and the separator are combined, the winding process is not carried out in depth to deal with the uneven interlayer spacing and surface unevenness of the separator in the final stage of the winding process. This results in a low quality pass rate of bare cells in the winding process, which in turn leads to low winding efficiency of bare cells in the winding process. Summary of the Invention

[0005] To address this, the present invention provides a production process for a unidirectional roller for the diaphragm finishing stage based on the winding process. This process overcomes the problem in the prior art where positive and negative electrode sheets and the diaphragm are combined and then wound. In this process, the uneven interlayer spacing and surface unevenness of the diaphragm finishing stage are not thoroughly addressed, resulting in a low quality pass rate of the bare cells during the winding process and consequently, low winding efficiency of the bare cells.

[0006] To achieve the above objectives, the present invention provides a production process for a diaphragm finishing unidirectional roller based on a winding process, comprising:

[0007] Acquire end-face and side-face images of bare battery cells wound on a winding machine;

[0008] Extract the bare cell layer spacing features of the end face image to determine whether the bare cell layer spacing uniformity meets the standard based on the obtained interlayer gap uniformity index, and determine the preset pressure applied by the unidirectional roller to the winding machine and the rotation speed of the winding machine based on the difference between the interlayer gap uniformity index and the preset interlayer gap uniformity index.

[0009] Microscopic undulation features of the side image are extracted to determine whether the flatness of the bare cell side is qualified based on the obtained microscopic undulation characterization parameters. The preset number of rotations of the winding machine and the increase of the preset pressure are determined according to the relative difference between the microscopic undulation characterization parameters and the preset microscopic undulation characterization parameters.

[0010] The layer gap data of several batches of qualified bare cells are obtained to determine whether the winding stability of the bare cells meets the standard based on the obtained batch gap fluctuation rate. The tension applied to the cell strip during the next batch winding process is increased according to the ratio of the preset batch gap fluctuation rate to the batch gap fluctuation rate. When the increased tension reaches the rated maximum tension, the preset number of rotations is increased.

[0011] After winding is completed, the gluing machine applies termination tape to the qualified bare battery cells.

[0012] Furthermore, the non-compliance of the bare cell interlayer spacing uniformity is determined based on the comparison result of the interlayer spacing uniformity index being greater than the preset interlayer spacing uniformity index.

[0013] Furthermore, the process of determining the interlayer gap uniformity index includes:

[0014] The interlayer boundaries of the end face image are extracted by grayscale and binarization to obtain the gap values ​​of each layer;

[0015] The average value of the gap between each layer of a number of qualified bare cells with winding in history is recorded as the reference gap value, and the deviation between the gap between each layer and the reference gap value is calculated.

[0016] The interlayer gap uniformity index is determined based on the deviation value, the reference interlayer gap value, the number of interlayer gaps, and the maximum deviation value.

[0017] Furthermore, under the condition that the uniformity of the bare cell layer spacing does not meet the standard, the process of determining the preset pressure of the unidirectional roller and the winding machine speed based on the difference between the interlayer gap uniformity index and the preset interlayer gap uniformity index includes:

[0018] Based on the comparison result where the difference is less than or equal to a preset difference, the unidirectional roller is determined to apply pressure to the winding machine with a first preset pressure, and the speed of the winding machine is reduced by a first preset speed adjustment coefficient;

[0019] Based on the comparison result where the difference is greater than a preset difference, the unidirectional roller is determined to apply pressure to the winding machine with a second preset pressure, and the speed of the winding machine is reduced with a second preset speed adjustment coefficient.

[0020] Furthermore, the non-compliance of the flatness of the bare cell side surface is determined based on the comparison results of the micro-undulation characterization parameter being greater than the preset micro-undulation characterization parameter.

[0021] Furthermore, the process of determining the micro-undulation characterization parameters includes:

[0022] Reconstructing the three-dimensional shape of the side image using a stereo vision algorithm;

[0023] Several regions are selected on the three-dimensional topography, the height data of the regions are extracted, and the average height deviation of the regions is calculated.

[0024] The average height deviation of the side of the qualified bare battery cell is recorded as the reference deviation;

[0025] The micro-undulation characterization parameter is determined based on the average height deviation and the reference deviation.

[0026] Furthermore, under the condition that the flatness of the bare cell side surface is unqualified, the process of determining the preset number of rotations of the winding machine and adjusting the preset pressure of the unidirectional roller based on the relative difference between the micro-undulation characterization parameter and the preset micro-undulation characterization parameter includes:

[0027] Based on the comparison result that the relative difference is less than or equal to the preset relative difference, the winding machine is determined to rotate at a first preset number of rotations, and the preset pressure of the unidirectional roller is increased by a first preset pressure adjustment coefficient.

[0028] Based on the comparison result that the relative difference is greater than the preset relative difference, the winding machine is determined to rotate at a second preset number of rotations, and the preset pressure of the unidirectional roller is increased by a second preset pressure adjustment coefficient.

[0029] Furthermore, the failure of bare cell winding stability to meet the standard is determined based on the comparison results of the batch gap fluctuation rate being greater than the preset batch gap fluctuation rate.

[0030] Furthermore, under the condition that the bare cell winding stability is not up to standard, based on the comparison result that the ratio of the preset batch gap fluctuation rate to the batch gap fluctuation rate is less than or equal to the preset ratio, the tension applied to the cell strip during the next batch winding process is increased by a first preset tension adjustment coefficient, and when the increased tension reaches the rated maximum tension, the preset number of rotations is increased by a first preset number of rotations adjustment coefficient.

[0031] Furthermore, under the condition that the winding stability of the bare cell does not meet the standard, based on the comparison result that the ratio of the preset batch gap fluctuation rate to the batch gap fluctuation rate is greater than the preset ratio, the tension applied to the cell strip during the next batch winding process is increased by the second preset tension adjustment coefficient, and when the increased tension reaches the rated maximum tension, the preset number of rotations is increased by the second preset number of rotations adjustment coefficient.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention acquires end-face and side-face images, determines whether the uniformity of the interlayer spacing of the bare cell meets the standard based on the interlayer gap uniformity index of the end-face image, determines the preset pressure applied by the unidirectional roller to the winding machine and the rotation speed of the winding machine based on the difference between the interlayer gap uniformity index and the preset interlayer gap uniformity index, and dynamically adjusts the pressure of the unidirectional roller and the rotation speed of the winding machine to optimize the winding process and make the interlayer spacing more uniform. Based on the micro-undulation characterization parameters of the side-face image, the present invention determines whether the flatness of the bare cell side surface is qualified, and determines the rotation speed of the winding machine based on the relative difference between the micro-undulation characterization parameters and the preset micro-undulation characterization parameters. The preset number of rotations and the increase of preset pressure improve the flatness of the bare cell side. The batch gap fluctuation rate is used to judge whether the winding stability of the bare cell meets the standard. If it does not meet the standard, the tension applied to the cell strip during the next batch winding process is increased. When the increased tension reaches the rated maximum tension, the preset number of rotations is increased, which improves the product quality consistency, improves the stability of the winding process, precisely controls the uniformity of the interlayer gap, reduces the fluctuation of battery internal resistance, and improves the consistency of energy density. The optimization of side flatness reduces the risk of cell surface wrinkles, reduces the quality fluctuation caused by material differences, reduces the risk of electrode breakage, and improves the winding efficiency of bare cells in the winding process.

[0033] Furthermore, this invention analyzes the interlayer spacing uniformity using images of the bare cell end face, dynamically adjusts the unidirectional roller pressure and winding machine speed, optimizes the cell strip tension, improves winding stability, reduces quality fluctuations, and enhances production line flexibility, thereby improving the winding efficiency of bare cells in the winding process.

[0034] Furthermore, the present invention uses the micro-undulation characterization parameters obtained from the side image to determine whether the flatness is qualified. If it is not qualified, the number of rotations of the winding machine and the preset pressure of the unidirectional roller are adjusted to avoid problems such as poor connection of the electrode tab and reduced sealing performance caused by excessive micro-undulation. The pressure and the number of rotations work together to improve the side undulation through mechanical compaction and simultaneously optimize the uniformity of the interlayer gap, reducing the risk of short circuit inside the cell.

[0035] Furthermore, this invention calculates the batch gap fluctuation rate by acquiring the interlayer gap data of different batches of bare cells, and compares it with the preset batch gap fluctuation rate to determine whether the winding stability meets the standard. If it does not meet the standard, the tension of the cell strip and the number of rotations of the winding machine are adjusted according to the ratio of the preset batch gap fluctuation rate to the batch gap fluctuation rate during the next batch winding. This improves the winding stability and consistency of bare cells, reduces rework and scrap caused by winding stability problems, and improves production efficiency. The winding stability improves the uniformity and stability of the internal structure of the cell, thereby enhancing the safety of the battery. Attached Figure Description

[0036] Figure 1 This is a flowchart of the production process of the diaphragm finishing unidirectional roller based on the winding process in an embodiment of the present invention;

[0037] Figure 2 This is a flowchart illustrating how to determine whether the uniformity of the bare cell layer spacing meets the standard in an embodiment of the present invention.

[0038] Figure 3 This is a flowchart illustrating the process of determining whether the flatness of the bare cell side surface is up to standard in an embodiment of the present invention.

[0039] Figure 4 This is a flowchart illustrating how to determine whether the winding stability of bare battery cells meets the standards in an embodiment of the present invention.

[0040] Figure 5 This is a schematic diagram of the production process of the diaphragm finishing unidirectional roller based on the winding process in an embodiment of the present invention;

[0041] In the diagram, 1 is the battery cell strip; 2 is the winding machine; 3 is the unidirectional roller; and 4 is the gluing machine. Detailed Implementation

[0042] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0043] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0044] It should be noted that the data in this embodiment are all derived from a comprehensive analysis and evaluation of historical test data and corresponding historical test results from the three months prior to this test. Those skilled in the art will understand that the determination of the above-mentioned parameters for any single item in this invention can be achieved by selecting the value with the highest percentage based on the data distribution as the preset standard parameter, using weighted summation to obtain the value as the preset standard parameter, substituting each historical data point into a specific formula and using the value obtained from that formula as the preset standard parameter, or other selection methods, as long as the invention can clearly define different specific situations in the single-item judgment process through the obtained values.

[0045] Please see Figure 1 As shown, it is a flowchart of the production process of the diaphragm finishing unidirectional roller based on the winding process in an embodiment of the present invention.

[0046] The present invention relates to a production process for a diaphragm finishing unidirectional roller based on a winding process, comprising:

[0047] Step S1: Obtain end face and side face images of the bare battery cell wound on the winding machine;

[0048] Step S2: Extract the bare cell layer spacing features of the end face image to determine whether the bare cell layer spacing uniformity meets the standard based on the obtained interlayer gap uniformity index, and determine the preset pressure applied by the unidirectional roller to the winding machine and the rotation speed of the winding machine based on the difference between the interlayer gap uniformity index and the preset interlayer gap uniformity index.

[0049] Step S3: Extract the micro-undulation features of the side image to determine whether the flatness of the bare cell side is qualified based on the obtained micro-undulation characterization parameters, and determine the preset number of rotations of the winding machine and the increase of the preset pressure based on the relative difference between the micro-undulation characterization parameters and the preset micro-undulation characterization parameters.

[0050] Step S4: Obtain the layer gap data of several batches of qualified bare cells to determine whether the winding stability of the bare cells meets the standard based on the obtained batch gap fluctuation rate. Determine the increase of the tension applied to the cell strip during the next batch winding process according to the ratio of the preset batch gap fluctuation rate to the batch gap fluctuation rate. When the increased tension reaches the rated maximum tension, increase the preset number of rotations.

[0051] Step S5: After winding is completed, the adhesive applicator applies termination tape to the qualified bare battery cells.

[0052] Specifically, this invention acquires end-face and side-face images. Based on the interlayer gap uniformity index of the end-face image, it determines whether the interlayer spacing uniformity of the bare cell meets the standard. Based on the difference between the interlayer gap uniformity index and a preset interlayer gap uniformity index, it determines the preset pressure applied by the unidirectional roller to the winding machine and the rotation speed of the winding machine. It dynamically adjusts the pressure of the unidirectional roller and the rotation speed of the winding machine to optimize the winding process and make the interlayer spacing more uniform. Based on the micro-undulation characterization parameters of the side-face image, it determines whether the flatness of the bare cell side is qualified. Based on the relative difference between the micro-undulation characterization parameters and the preset micro-undulation characterization parameters, it determines the preset number of rotations of the winding machine. Increasing the preset pressure improves the flatness of the bare cell side surface. The batch gap fluctuation rate is used to determine whether the bare cell winding stability meets the standard. If it does not meet the standard, the tension applied to the cell strip during the next batch winding process is increased. When the increased tension reaches the rated maximum tension, the preset number of rotations is increased, which improves the product quality consistency, improves the stability of the winding process, precisely controls the uniformity of the interlayer gap, reduces the fluctuation of battery internal resistance, and improves the consistency of energy density. The optimized side flatness reduces the risk of cell surface wrinkles, reduces the quality fluctuation caused by material differences, reduces the risk of electrode breakage, and improves the winding efficiency of bare cells in the winding process.

[0053] Specifically, in this embodiment of the invention, a positive electrode sheet, a negative electrode sheet, and a separator are combined to form a battery cell strip for winding a bare battery cell. The battery cell strip is then wound on a winding machine to form a bare battery cell. The tension of the battery cell strip is 0.1 to 0.3 N / mm², preferably 0.2 N / mm². The above process is a conventional process and will not be described in detail here.

[0054] Specifically, in this embodiment of the invention, the bare cell winding is deemed qualified if the uniformity of the spacing between the bare cell layers meets the standard and the flatness of the side surface is qualified.

[0055] Specifically, in this embodiment of the invention, after the winding is completed, the diaphragm is cut using a hot cutter or laser, retaining the length of the diaphragm end. After the bare battery cell is wound to a qualified standard, the adhesive machine applies a termination tape.

[0056] Specifically, in this embodiment of the invention, an industrial camera is provided in front of and on the side of the winding machine. The industrial camera is used to acquire end face images and side images of the bare battery cells wound on the winding machine.

[0057] Please see Figure 2 As shown, it is a flowchart for determining whether the uniformity of the bare cell layer spacing meets the standard in an embodiment of the present invention.

[0058] Specifically, in this embodiment of the invention, under the condition of obtaining the end face image of the bare cell, the interlayer spacing features of the bare cell in the end face image are extracted to obtain the interlayer spacing uniformity index. The comparison result of the obtained interlayer spacing uniformity index with the preset interlayer spacing uniformity index determines whether the interlayer spacing uniformity of the bare cell meets the standard.

[0059] When the interlayer gap uniformity index is less than or equal to the preset interlayer gap uniformity index, the uniformity of the bare cell interlayer spacing is determined to meet the standard.

[0060] When the interlayer gap uniformity index is greater than the preset interlayer gap uniformity index, it is determined that the uniformity of the bare cell interlayer spacing is substandard.

[0061] In this embodiment of the invention, the preset interlayer gap uniformity index ranges from [0.08, 0.15], preferably 0.12. However, the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0062] In this embodiment of the invention, the process of obtaining the interlayer gap uniformity index is as follows: the interlayer boundaries of the end face image are extracted by grayscale and binarization to obtain the gap value of each layer; the average value of the gap values ​​of several qualified bare cells with winding in the past is recorded as the reference gap value, and the deviation value between each layer gap and the reference gap value is calculated; the interlayer gap uniformity index is the sum of the absolute values ​​of several deviation values ​​divided by the reference gap value and divided by the number of layer gaps, plus the product of the maximum deviation value divided by the absolute value of the reference gap value and the weighting coefficient, wherein the weighting coefficient is 0.3.

[0063] Specifically, in this embodiment of the invention, when it is determined that the uniformity of the spacing between the bare battery cells does not meet the standard, the unidirectional roller presses the side of the winding machine with a preset pressure, and then the winding machine rotates.

[0064] Specifically, in this embodiment of the invention, the preset pressure of the unidirectional roller and the speed of the winding machine are determined based on the comparison result of the difference between the interlayer gap uniformity index and the preset interlayer gap uniformity index and the preset difference.

[0065] When the difference is less than or equal to the preset difference, it is determined that the unidirectional roller applies pressure to the winding machine with a first preset pressure, and the speed of the winding machine is reduced to the corresponding value with a first preset speed adjustment coefficient of 0.97.

[0066] When the difference is greater than the preset difference, it is determined that the unidirectional roller applies pressure to the winding machine with a second preset pressure, and the speed of the winding machine is reduced to the corresponding value with a second preset speed adjustment coefficient of 0.93.

[0067] The difference is the difference between the interlayer gap uniformity index and the preset interlayer gap uniformity index.

[0068] In this embodiment of the invention, the preset difference value range is [0.11, 0.23], preferably 0.18, but the above value is not limited to this, and those skilled in the art can also adjust the value according to actual needs.

[0069] In this embodiment of the invention, the first preset pressure range is 0.1 N / mm² to 0.2 N / mm², preferably 0.15 N / mm², and the second preset pressure range is 0.25 N / mm² to 0.35 N / mm², preferably 0.3 N / mm².

[0070] In this embodiment of the invention, the reduced speed is the product of the speed and the preset speed adjustment coefficient. The preset speed adjustment coefficient includes a first preset speed adjustment coefficient with a value of 0.97 and a second preset speed adjustment coefficient with a value of 0.93. In order to ensure that the adjusted speed meets the actual needs, the adjustment range should not be too large. Therefore, an adjustment coefficient is set to control the adjustment range.

[0071] Specifically, this invention analyzes the interlayer spacing uniformity by using images of the bare cell end face, dynamically adjusts the unidirectional roller pressure and winding machine speed, optimizes the cell strip tension, improves winding stability, reduces quality fluctuations, and enhances the flexibility of the production line, thereby improving the winding efficiency of bare cells in the winding process.

[0072] Please see Figure 3 As shown, it is a flowchart for determining whether the flatness of the bare cell side surface is qualified according to an embodiment of the present invention.

[0073] Specifically, in this embodiment of the invention, under the condition of obtaining a side image of the bare cell, the micro-undulation features of the side image are extracted to obtain a micro-undulation characterization parameter. The comparison result of the obtained micro-undulation characterization parameter with the preset micro-undulation characterization parameter determines whether the flatness of the side of the bare cell is qualified.

[0074] When the micro-undulation characterization parameter is less than or equal to the preset micro-undulation characterization parameter, the flatness of the bare cell side surface is determined to be qualified.

[0075] When the micro-undulation characterization parameter is greater than the preset micro-undulation characterization parameter, the flatness of the bare cell side surface is determined to be unqualified.

[0076] In this embodiment of the invention, the preset range of values ​​for the micro-undulation characterization parameter is [1.0, 1.2], preferably 1.1. However, the above values ​​are not limited to these values, and those skilled in the art can adjust the values ​​according to actual needs.

[0077] In this embodiment of the invention, the process of obtaining the micro-undulation characterization parameter is as follows: reconstructing the three-dimensional shape of the side image using a stereo vision algorithm; selecting several regions on the three-dimensional shape and extracting the height data of the regions; calculating the average height deviation of the several regions; recording the average height deviation of the side of the qualified wound bare cell as the reference deviation; the micro-undulation characterization parameter is the ratio of the average height deviation to the reference deviation, wherein the average height deviation is the sum of the differences between the height of several regions and the average height of several regions, divided by the number of regions.

[0078] Specifically, in this embodiment of the invention, under the condition that the flatness of the bare cell side is unqualified, the preset number of rotations of the winding machine and the preset pressure of the unidirectional roller are determined based on the comparison result of the relative difference between the micro-undulation characterization parameter and the preset micro-undulation characterization parameter and the preset relative difference.

[0079] When the relative difference is less than or equal to the preset relative difference, the winding machine is determined to rotate at the first preset number of rotations, and the preset pressure of the unidirectional roller is increased to the corresponding value by the first preset pressure adjustment coefficient of 1.06.

[0080] When the relative difference is greater than the preset relative difference, the winding machine is determined to rotate at the second preset number of rotations, and the preset pressure of the unidirectional roller is increased to the corresponding value by the second preset pressure adjustment coefficient 1.12.

[0081] The relative difference is the relative difference between the micro-undulation characterization parameter and the preset micro-undulation characterization parameter.

[0082] In this embodiment of the invention, the preset relative difference range is [0.35, 0.45], preferably 0.4, but the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0083] In this embodiment of the invention, the first preset number of rotations is 2 to 4 rotations, preferably 3 rotations, and the second preset number of rotations is 6 to 8 rotations, preferably 7 rotations.

[0084] In this embodiment of the invention, the increased preset pressure is the product of the preset pressure and the preset pressure adjustment coefficient. The preset pressure adjustment coefficient includes a first preset pressure adjustment coefficient with a value of 1.06 and a second preset pressure adjustment coefficient with a value of 1.12. The preset pressure includes the first preset pressure and the second preset pressure. In order to ensure that the adjusted preset pressure meets the actual needs, the adjustment range should not be too large. Therefore, an adjustment coefficient is set to control the adjustment range.

[0085] Specifically, this invention uses the micro-undulation characterization parameters obtained from the side image to determine whether the flatness is up to standard. If it is not up to standard, the number of rotations of the winding machine and the preset pressure of the unidirectional roller are adjusted to avoid problems such as poor electrode tab welding and reduced sealing performance caused by excessive micro-undulations. The pressure and the number of rotations work together to improve the side undulations through mechanical compaction and simultaneously optimize the uniformity of interlayer gaps, reducing the risk of short circuits inside the cell.

[0086] Please see Figure 4 As shown, it is a flowchart for determining whether the winding stability of bare battery cells meets the standard in an embodiment of the present invention.

[0087] Specifically, in this embodiment of the invention, the layer gap data of several batches of qualified bare cells are obtained to obtain the batch gap fluctuation rate, and the winding stability of the bare cells is determined based on the comparison result of the batch gap fluctuation rate and the preset batch gap fluctuation rate.

[0088] When the batch gap fluctuation rate is less than or equal to the preset batch gap fluctuation rate, the bare cell winding stability is determined to meet the standard.

[0089] When the batch gap fluctuation rate is greater than the preset batch gap fluctuation rate, it is determined that the bare cell winding stability does not meet the standard.

[0090] In this embodiment of the invention, the preset batch gap fluctuation rate is set to a range of [5%, 15%], preferably 10%, but the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0091] In this embodiment of the invention, the process of obtaining the batch gap volatility is as follows: calculate the standard deviation of the layer gap data for each batch; calculate the average of the standard deviations of all batches, denoted as the average batch standard deviation; calculate the standard deviation of the standard deviations of all batches, denoted as the volatility standard deviation, and the batch gap volatility is the ratio of the volatility standard deviation to the average batch standard deviation multiplied by 100%.

[0092] Specifically, in this embodiment of the invention, when it is determined that the winding stability of the bare battery cell is not up to standard, the tension applied to the battery cell strip during the next batch winding process is adjusted based on the comparison result of the ratio of the preset batch gap fluctuation rate to the preset ratio, and the number of rotations of the winding machine is adjusted when the adjusted tension reaches the rated maximum tension.

[0093] When the ratio is less than or equal to the preset ratio, it is determined that the tension applied to the cell strip during the next batch of winding will be increased to the corresponding value by the first preset tension adjustment coefficient 1.15, and when the increased tension reaches the rated maximum tension, the preset number of rotations will be increased to the corresponding value by the first preset number of rotations adjustment coefficient 2.

[0094] When the ratio is greater than the preset ratio, it is determined that the tension applied to the cell strip during the next batch of winding will be increased to the corresponding value by the second preset tension adjustment coefficient 1.25, and when the increased tension reaches the rated maximum tension, the preset number of rotations will be increased to the corresponding value by the second preset number of rotations adjustment coefficient 4.

[0095] The ratio is the ratio of the preset batch gap volatility to the batch gap volatility.

[0096] In this embodiment of the invention, the preset ratio range is [0.16, 0.24], preferably 0.19, but the above value is not limited to this, and those skilled in the art can adjust the value according to actual needs.

[0097] In this embodiment of the invention, the increased tension is the product of the tension and the preset tension adjustment coefficient. The preset tension adjustment coefficient includes a first preset tension adjustment coefficient with a value of 1.15 and a second preset tension adjustment coefficient with a value of 1.25.

[0098] In this embodiment of the invention, the increased preset number of rotations is a preset number of rotations plus a preset number of rotations adjustment coefficient. The preset number of rotations adjustment coefficient includes a first preset number of rotations adjustment coefficient with a value of 2 and a second preset number of rotations adjustment coefficient with a value of 4. The preset number of rotations includes the first preset number of rotations and the second preset number of rotations. To ensure that the adjusted preset number of rotations meets the actual needs, the adjustment range should not be too large. Therefore, an adjustment coefficient is set to control the adjustment range.

[0099] Specifically, this invention calculates the batch gap fluctuation rate by acquiring the interlayer gap data of different batches of bare cells, and compares it with the preset batch gap fluctuation rate to determine whether the winding stability meets the standard. If it does not meet the standard, the tension of the cell strip and the number of rotations of the winding machine are adjusted according to the ratio of the preset batch gap fluctuation rate to the batch gap fluctuation rate. This improves the winding stability and consistency of bare cells, reduces rework and scrap caused by winding stability problems, and improves production efficiency. The winding stability improves the uniformity and stability of the internal structure of the cell, thereby enhancing the safety of the battery.

[0100] Please see Figure 5 The diagram shown is a schematic of the production process of the diaphragm finishing unidirectional roller based on the winding process in an embodiment of the present invention.

[0101] Battery cell strip 1, which is used to combine the positive electrode sheet, the negative electrode sheet and the separator;

[0102] Winding machine 2, which is used to wind the battery cell strip 1 into a bare battery cell;

[0103] The unidirectional roller 3 is used to apply a preset pressure to the side of the winding machine during the winding process of bare battery cells in order to improve the uniformity of interlayer gaps and the flatness of the side.

[0104] Adhesive applicator 4 is used to apply termination tape to the end of the separator after the bare battery cell has been wound to the required specifications.

[0105] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A production process for a diaphragm finishing unidirectional roller based on a winding process, characterized in that, include: Acquire end-face and side-face images of bare battery cells wound on a winding machine; Extract the bare cell layer spacing features of the end face image to determine whether the bare cell layer spacing uniformity meets the standard based on the obtained interlayer gap uniformity index, and determine the preset pressure applied by the unidirectional roller to the winding machine and the rotation speed of the winding machine based on the difference between the interlayer gap uniformity index and the preset interlayer gap uniformity index. Microscopic undulation features of the side image are extracted to determine whether the flatness of the bare cell side is qualified based on the obtained microscopic undulation characterization parameters. The preset number of rotations of the winding machine and the increase of the preset pressure are determined according to the relative difference between the microscopic undulation characterization parameters and the preset microscopic undulation characterization parameters. The layer gap data of several batches of qualified bare cells are obtained to determine whether the winding stability of the bare cells meets the standard based on the obtained batch gap fluctuation rate. The tension applied to the cell strip during the next batch winding process is increased according to the ratio of the preset batch gap fluctuation rate to the batch gap fluctuation rate. When the increased tension reaches the rated maximum tension, the preset number of rotations is increased. After winding is completed, the gluing machine applies termination tape to the qualified bare battery cells.

2. The production process of the diaphragm finishing unidirectional roller based on the winding process according to claim 1, characterized in that, The non-compliance of the bare cell interlayer spacing uniformity is determined based on the comparison result of the interlayer spacing uniformity index being greater than the preset interlayer spacing uniformity index.

3. The production process of the diaphragm finishing unidirectional roller based on the winding process according to claim 2, characterized in that, The process of determining the interlayer gap uniformity index includes: The interlayer boundaries of the end face image are extracted by grayscale and binarization to obtain the gap values ​​of each layer; The average value of the gap between each layer of a number of qualified bare cells with winding in history is recorded as the reference gap value, and the deviation between the gap between each layer and the reference gap value is calculated. The interlayer gap uniformity index is determined based on the deviation value, the reference interlayer gap value, the number of interlayer gaps, and the maximum deviation value.

4. The production process of the diaphragm finishing unidirectional roller based on the winding process according to claim 3, characterized in that, Under the condition that the uniformity of the bare cell layer spacing does not meet the standard, the process of determining the preset pressure of the unidirectional roller and the winding machine speed based on the difference between the interlayer gap uniformity index and the preset interlayer gap uniformity index includes: Based on the comparison result where the difference is less than or equal to a preset difference, the unidirectional roller is determined to apply pressure to the winding machine with a first preset pressure, and the speed of the winding machine is reduced by a first preset speed adjustment coefficient; Based on the comparison result where the difference is greater than a preset difference, the unidirectional roller is determined to apply pressure to the winding machine with a second preset pressure, and the speed of the winding machine is reduced with a second preset speed adjustment coefficient.

5. The production process of the diaphragm finishing unidirectional roller based on the winding process according to claim 4, characterized in that, The non-compliance of the flatness of the bare cell side surface was determined based on the comparison results of the micro-undulation characterization parameter being greater than the preset micro-undulation characterization parameter.

6. The production process of the diaphragm finishing unidirectional roller based on the winding process according to claim 5, characterized in that, The process of determining the parameters characterizing the micro-abnormalities includes: Reconstructing the three-dimensional shape of the side image using a stereo vision algorithm; Several regions are selected on the three-dimensional topography, the height data of the regions are extracted, and the average height deviation of the regions is calculated. The average height deviation of the side of the qualified bare battery cell is recorded as the reference deviation; The micro-undulation characterization parameter is determined based on the average height deviation and the reference deviation.

7. The production process of the diaphragm finishing unidirectional roller based on the winding process according to claim 6, characterized in that, Under the condition that the flatness of the bare cell side surface is unqualified, the process of determining the preset number of rotations of the winding machine and adjusting the preset pressure of the unidirectional roller based on the relative difference between the micro-undulation characterization parameter and the preset micro-undulation characterization parameter includes: Based on the comparison result that the relative difference is less than or equal to the preset relative difference, the winding machine is determined to rotate at a first preset number of rotations, and the preset pressure of the unidirectional roller is increased by a first preset pressure adjustment coefficient. Based on the comparison result that the relative difference is greater than the preset relative difference, the winding machine is determined to rotate at a second preset number of rotations, and the preset pressure of the unidirectional roller is increased by a second preset pressure adjustment coefficient.

8. The production process of the diaphragm finishing unidirectional roller based on the winding process according to claim 7, characterized in that, The failure of bare cell winding stability to meet the standard is determined based on the comparison results of the batch gap fluctuation rate being greater than the preset batch gap fluctuation rate.

9. The production process of the diaphragm finishing unidirectional roller based on the winding process according to claim 8, characterized in that, Under the condition that the bare cell winding stability is not up to standard, based on the comparison result that the ratio of the preset batch gap fluctuation rate to the batch gap fluctuation rate is less than or equal to the preset ratio, the tension applied to the cell strip during the next batch winding process is increased by the first preset tension adjustment coefficient, and when the increased tension reaches the rated maximum tension, the preset number of rotations is increased by the first preset number of rotations adjustment coefficient.

10. The production process of the diaphragm finishing unidirectional roller based on the winding process according to claim 9, characterized in that, If the bare cell winding stability is found to be substandard, the tension applied to the cell strip during the next batch winding process is increased by a second preset tension adjustment coefficient based on the comparison result that the ratio of the preset batch gap fluctuation rate to the batch gap fluctuation rate is greater than the preset ratio. When the increased tension reaches the rated maximum tension, the preset number of rotations is increased by a second preset number of rotations adjustment coefficient.

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