Method and device for detecting turnover qualification of tab

Abstract

The invention discloses a tab folding qualification detection method and device. The tab folding qualification detection method comprises the following steps: after a tab is folded and a detected pole group sample is fixed, acquiring thickness data information of a tab characteristic position to obtain sample characteristic thickness data; and comparing the sample characteristic thickness data with a pre-obtained standard specification interval, and judging the folding qualification of the sample tab according to a comparison result. According to the invention, on the basis of the physical characteristic that the thickness of the folded tab changes after the winding of the pole group is completed, the tab thickness data of the fixed area after the tab is folded is collected in real time, and the characteristic thickness data is compared with the standard specification interval, so that the tab folding qualification is judged, a battery with a folding condition can be effectively prevented from entering a welding process, and the production efficiency is improved. The product quality is influenced.

Description

Technical Field

[0001] This invention relates to the field of power battery manufacturing technology, and in particular to a method and apparatus for detecting the pass / failability of electrode tabs. Background Technology

[0002] In power battery systems, electrodes and separators are stacked or wound to form a single-electrode assembly. The electrode assembly needs to be connected to the cover plate through tabs to complete current conduction. Influenced by the market's pursuit of fast-charging performance of battery cells, the demand for increasing the number of tabs in battery cells is constantly rising. The probability of tab folding is also gradually increasing. To ensure design effectiveness and product safety, the accuracy of tab folding detection has become a very important quality assurance indicator.

[0003] Currently, electrode folding detection solutions primarily rely on visual inspection. When using this approach for logical judgment, the required quantitative information is presented based on images. However, considering that electrode materials are mostly soft materials such as copper and aluminum, and have multi-layer stacking characteristics, the accuracy of image acquisition is severely affected by this, resulting in limited accuracy.

[0004] Patent document CN202510269227 discloses a tab detection system and method. The tab detection system includes: a transmission component for transferring a battery cell to a detection station; an image acquisition mechanism and a rotation mechanism, both disposed at the detection station; and a control terminal communicatively connected to the transmission component, the image acquisition mechanism, and the rotation mechanism. The rotation mechanism, under the control of the control terminal, rotates the battery cell at the detection station, allowing the battery cell to switch between a flat position and a suspended position. The image acquisition mechanism, under the control of the control terminal, acquires a side image of the tab of the battery cell in the flat position and a large-area image of the tab of the battery cell in the suspended position. The control terminal determines the tab detection result based on the side and large-area images of the tab. Its large-area image is affected by the stacking of electrode tabs, and can only capture the state of the top and bottom electrode tabs, and cannot detect the phenomenon of the entire electrode tab being folded; the side curve image cannot avoid the recognition interference caused by electrode tab misalignment, electrode tab deformation, and electrode tab gradient design, and there is a risk of batch detection failure.

[0005] Patent document CN202510294272 discloses a tab detection device and a tab detection method. The tab detection device includes a bracket, a support structure, and a vision inspection module. The bracket has a fixing structure for fixing the bare battery cell body in the direction of gravity, and the fixing structure is used to make the thickness direction of the battery cell body parallel to the direction of gravity. At least part of the support structure is fixed relative to the bracket and is used to support the bottom surface of the tab. Projected along the direction of gravity, at least part of the edge of the tab is set outside the edge of the support structure. The vision inspection module is fixed relative to the bracket and is used to detect the tab. The two tabs of the battery cell are supported respectively. Thus, when the tab detection device is used, the support structure can support the tab to a more horizontal position for easier detection. This helps to avoid inaccurate size detection and image defocusing caused by tab tilt, and helps to reduce detection deviation. The testing equipment and methods include adding a tab support device to provide external force for the tab to help shape it, so as to avoid problems such as inaccurate size detection and image defocus caused by tab tilt. The judgment indicators are tab color and tab area. However, it cannot avoid the interference caused by tab misalignment and tab gradient design, and the improvement effect is limited.

[0006] Patent document CN202510478092 discloses a visual inspection device for battery cell tabs, including a main frame. A first robotic arm, a visual inspection mechanism, a second robotic arm, and a third robotic arm are sequentially arranged along a fixture circulation conveyor line on the main frame. This device can automatically complete the detection of folding defects in battery cell tabs. Compared to manual inspection, the detection accuracy and efficiency are improved. Compared to existing inspection equipment on the market, it reduces manual handling, increases work efficiency, and avoids potential adverse effects on the battery cell during manual handling. Furthermore, the disclosed fixture circulation conveyor line includes a straightening mechanism and a first belt conveyor carrying several fixtures. Each fixture includes a support platform and limiting components on both sides. In use, the fixtures provide bottom support and left-right positioning for the battery cell, the straightening mechanism positions the battery cell front-back, and the first belt conveyor transports the positioned battery cell. The main focus of this inspection device is on the inspection process, with the final point of contact being the production line logistics device. The tab detection module uses a camera. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects in the existing technology and provide a method and apparatus for detecting the passability of electrode tab folding before welding after the tab is closed and pressed.

[0008] The first objective of this invention is to provide a method for detecting the conformity of tab folding, comprising the following steps:

[0009] After the electrode tabs are folded together and the sample of the electrode group is fixed, thickness data information of the characteristic positions of the electrode tabs is collected to obtain the characteristic thickness data of the sample.

[0010] The sample characteristic thickness data is compared with the pre-obtained standard specification range, and the passability of the sample tab folding is determined based on the comparison results.

[0011] Preferably, after obtaining the comparison result, the method further includes:

[0012] After mapping the sample characteristic thickness data to the tab feature position and folding state, a result feedback image is output; the result feedback image is used to distinguish the tab folding state representing the tab feature position through different colors.

[0013] Preferably, the standard specification range is obtained by collecting and analyzing thickness data of the characteristic positions of multiple electrode group samples with no electrode defects.

[0014] Preferably, the electrode tab feature positions are selected from multiple feature areas based on the width of the top bottom of the electrode tab after folding.

[0015] Preferably, the range of the feature region is determined by the product of the number of scans in a single test by the testing equipment and the minimum area measured in a single test.

[0016] Preferably, the standard specification range is determined by the following formula:

[0017]

[0018] in, This represents a calculation function based on a standard specification range of thickness. For the first Standard thickness of a single-layer electrode The deviation coefficient, For the first The tolerance of the single-layer electrode tab is as follows: This is the compensation value.

[0019] Preferably, the sample characteristic thickness data corresponds one-to-one with the electrode characteristic position, and is processed by the following conversion formula:

[0020]

[0021] in, This represents a transformation function based on the thickness data of the sampling points. As compensation value, , For the first The periodic eigenvalue coefficients of each sampling point For the amount of data, For the first Thickness data at each sampling point The trajectory of the thickness measuring equipment.

[0022] Preferably, a laser thickness measuring device is used to collect thickness data at the characteristic location of the electrode tab.

[0023] Preferably, the height of the tabs of the tested electrode group sample is arranged in an arithmetic sequence that increases from the outer ring inward.

[0024] A second objective of this invention is to provide a device for detecting the conformity of tab folding, used to implement the tab folding conformity detection method, comprising:

[0025] The data collection unit is used to collect thickness data information of the characteristic positions of the electrode tabs after the electrode tabs are folded and the electrode group sample is fixed, so as to obtain the characteristic thickness data of the sample.

[0026] The data processing and judgment unit is used to compare the sample characteristic thickness data with the pre-obtained standard specification range, and judge the qualification of the sample tab folding based on the comparison result.

[0027] Preferred options also include:

[0028] The result conversion feedback unit is used to map the sample characteristic thickness data to the electrode characteristic position one by one and output a result feedback image; the result feedback image is used to distinguish the electrode folding qualification of the electrode characteristic position by different colors.

[0029] The present invention relates to a method and apparatus for detecting the passability of tab folding. Based on the physical characteristic that the thickness of the tab changes after the electrode assembly is wound, the method collects tab thickness data in real time in the fixed area after the tab is folded, and compares the characteristic thickness data with standard specification ranges to determine the passability of tab folding. Furthermore, the characteristic thickness data is mapped one-to-one with characteristic positions, representing different tab folding states at different characteristic positions and displayed using different colors. This facilitates intuitive observation of the passability of tab folding positions and effectively prevents batteries with folding issues from entering the welding process, thus affecting product quality. Only batteries that pass the detection specified in this application are allowed to proceed to the ultrasonic welding process for the tabs, thereby ensuring post-welding quality.

[0030] The technology of the tab folding qualification detection method and device of the present invention can be integrated into different process steps such as winding, hot pressing, and ultrasonic welding, and has the advantages of low cost, small footprint, and simple operation. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the tabs folded up according to an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of the thickness measurement of the tab after folding in an embodiment of the present invention.

[0033] Figure 3 This is a flowchart illustrating the electrode tab folding conformity test of an embodiment of the invention.

[0034] Figure label:

[0035] 11. A electrode group, 12. Electrode tab, 13. B electrode group, 21. Electrode group thickness, 22. Electrode tab folding height, 3. Connecting piece, 4. Ultrasonic solder mark to be formed, 51. Test point 1, 52. Test point 2, 53. Test point 3, 61. Electrode tab exceeds solder mark size. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0037] In this embodiment of the application, the method for detecting the passability of the tab fold includes the following steps:

[0038] After the electrode tabs are folded together and the sample of the electrode group is fixed, thickness data information of the characteristic positions of the electrode tabs is collected to obtain the characteristic thickness data of the sample.

[0039] The sample characteristic thickness data is compared with the pre-obtained standard specification range, and the passability of the sample tab folding is determined based on the comparison results.

[0040] Preferably, in this application, after the tab 12 is retracted, the sample of the tested electrode assembly (such as...) Figure 1 After electrode groups A12 and B13 are fixed, thickness data is collected at the characteristic positions of their electrode tabs using a laser thickness gauge. Due to the characteristics of the sample at the test end, the single-layer thickness characteristic value is generally within 4µm. ~ For the 15µm range, the equipment testing accuracy should be higher than 0.5µm.

[0041] In this application, the electrode assembly sample being tested is die-cut using non-uniform height electrodes. The height of the electrodes is arranged in an increasing arithmetic sequence from the outer ring inwards. This increasing arithmetic sequence arrangement can be expressed by the following formula:

[0042] h i+1 -h i =((H / 2) 2 +L 2 ) 1 / 2 -L) / n,

[0043] Among them, hi and h i+1 Let H be the height of the i-th and (i+1)-th electrode lugs counting inwards from the outer ring, and H be the electrode group thickness 21, as shown. Figure 1As shown, L is the height at which the tabs are folded together during battery assembly (22), and n is the number of turns of the positive electrode sheet wound around the electrode assembly.

[0044] In this embodiment of the application, after the feature thickness data is collected, the data is summarized and compared with a predetermined standard specification range, and the data is classified according to the comparison results. The classification of the data refers to classifying the feature thickness data into categories such as within the range and outside the range according to the standard specification range.

[0045] In the comparison, if there is data in the specification value range that exceeds the standard specification range, it is NG (the proportion of test data within the specification value range is <100% of all data).

[0046] Furthermore, in this embodiment of the application, after obtaining the comparison result, the following steps are also included:

[0047] After mapping the sample thickness data to the tab feature positions and folding states, a result feedback graph is output. This graph uses different colors to distinguish the tab folding states at different tab feature positions. This allows for a visual representation of whether tab folding is present, indicating whether tabs at different positions are folded; for example, red indicates non-compliance, and green indicates compliance.

[0048] Specifically, the result feedback image is a color representation of the data at different locations after signal conversion. In some embodiments, the area of ​​test data within the specified value range is shown in green, indicating that the area has no folds and meets the requirements (folds can easily cause the tabs to intercalate, and detection can avoid this risk); the area above the specified value data band is shown in red, indicating that the area has folds and is in a stacked state; the area below the specified value data band is shown in yellow, indicating that the area has folds and is in a missing layer state. That is, if a non-green area appears in the result feedback image, it means that the tab has folded and needs to be isolated and dealt with.

[0049] In this application, the phrase "corresponding one-to-one between the sample characteristic thickness data and the tab characteristic position" means that the classified characteristic thickness data is corresponded one-to-one with the corresponding measurement position (characteristic position), and then a result feedback diagram with guiding significance for the defect position is output and a corresponding judgment result is given, such as the judgment result of whether it is qualified or not.

[0050] For example, the conversion formula for the one-to-one correspondence between the sample feature thickness data and the tab feature position is as follows:

[0051]

[0052] Where B0 is the compensation value, a i b iHere, c represents the periodic eigenvalue coefficient, where i is the number of data points i = 1, 2, 3, ..., i. i For sampling point measurement data, D is the perimeter of the equipment's running trajectory, that is, the perimeter of the equipment's scanning running trajectory when the thickness measuring equipment scans for thickness measurement.

[0053] In this embodiment, the feature location is determined by selecting a representative feature region (number I) based on the width T of the upper base of the tab, and then testing is performed. The number of data points measured is I=k. I (C) 1~ C i ), where k I The width of the feature region occupies the width T of the upper base of the tab, where I and i are natural numbers, and C is the ratio of the width of the feature region to the width T of the upper base of the tab. 1~ C i Points are selected on the feature region.

[0054] The range of the feature region is D, which can be set according to the number of scans E of the single measuring device * the minimum area d that can be tested in a single scan. The starting point for the thickness test of the feature position can be taken as the center of the position boundary of the ultrasonic weld mark 4 to be formed by the preset ultrasonic welding of the electrode tab as the starting point for the device test.

[0055] Specifically, based on the flat area of ​​a single sample i (the area of ​​the tab extending beyond the preset solder mark upper edge, such as...), Figure 2 (The area of ​​the electrode tabs shown exceeds the size of the solder mark). In some embodiments, three thickness test sampling points c1, c2, and c3 can be set, with the data volume of each sampling point related to the trajectory. When summarizing the data, preferably, the data is distinguished according to the hierarchy to ensure a strong correspondence between the final feedback information and the sample.

[0056] In this embodiment, the standard specification range is obtained by fixing multiple electrode group samples with defect-free (non-folded) tabs, and then collecting thickness data information at characteristic positions by laser thickness measurement technology with reference to a specific trajectory. If the sample size is >100 pieces, a standard is established and continuously iterated, and finally the standard specification range is obtained by fitting.

[0057] In this application, when fixing the defect-free sample electrode assembly, the sample electrode assembly is tightened and fixed according to the uniform state of the assembly process, so that the electrode tab gap is zero. This is to avoid the electrode tab state after testing affecting subsequent processes (such as cycle time and yield), and to ensure the accuracy, validity, and consistency of the test data. Then, for the fixed electrode tab, according to the set trajectory area at each characteristic position (such as... Figure 2 The red box shown represents the rectangular trajectory area of ​​different test points. Thickness tests are performed to obtain the required characteristic thickness data.

[0058] For example, the formula for calculating the standard specification range is as follows:

[0059] Where A is the standard thickness of a single-layer tab, K is the deviation coefficient, s is the incoming material tolerance, B is the compensation value, and n is the number of tab layers.

[0060] Example

[0061] Standard specification range determined:

[0062] Taking the negative electrode tab flipping test of a 63Ah monopolar group after hot pressing as an example, the tab height h 26 =18.4mm, h=0.31mm=h i+1 -h i The standard thickness of the single-layer electrode tab is A=5um, n=26, s=0.18, and the solder area is 6*16mm. After fixing with a fixture, the trapezoidal electrode tab is folded down to 2mm, and the top is flush with the solder tip, with a 1mm gap between the top and the top of the solder tip. Specifically, for each sample feature area (sampling point), I=3, i=20, and the perimeter D of the rectangular trajectory covered by each sampling area (feature area) is set to 6.28mm. 100 samples without folding are selected for testing.

[0063] After data fitting, K=2.5 and B=0.1 were obtained, and the standard interval was (127.8, 132.4).

[0064] In subsequent testing, if the sample data at the measured sampling point is not within the range, the sample is judged as NG. The location image feedback will show the folding point as red or yellow, corresponding to the tab folding angle. Folding (the tab surface is not flat) has a negative impact and is a defective product, while no folding is a good product.

[0065] The following combination Figure 3 As shown, the tab folding test of this application is described as follows:

[0066] Example 1 of electrode folding detection

[0067] Step 1: Randomly select a hot-pressed electrode assembly sample, and press and fix the electrode assembly and electrode tab position without damaging the electrode tab to ensure that the gap between the electrode tab layers is zero.

[0068] Step 2: Perform thickness testing at the three designated test points (Test Point 1, Test Point 2, and Test Point 3) following a rectangular trajectory.

[0069] Step 3: The collected thickness data is summarized and processed. The maximum value of the measured data is 132.2 and the minimum value is 127.9, both of which are within the standard specification range (127.8, 132.4). The summarized data shows that the proportion of data within the standard specification range is 100%, and the sample is qualified.

[0070] Step 4: After classifying the data, match it one-to-one with the measurement location, output a green feedback image that matches the test trajectory location, and give an OK result.

[0071] Step 5: Remove the test sample and visually inspect it manually according to the location indicators. The actual folding condition of the sample is found to be defect-free, consistent with the output result. This indicates that the judgment was correct.

[0072] Example 2 of electrode folding detection

[0073] Step 1: Randomly select a hot-pressed electrode assembly sample, and press and fix the electrode assembly and electrode tab position without damaging the electrode tab to ensure that the gap between the electrode tab layers is zero.

[0074] Step 2: Perform thickness testing at the three designated test points (e.g., test point 1, test point 51, test point 52, and test point 53) following a circular trajectory.

[0075] Step 3: The collected thickness data is summarized and processed. The maximum value of the measured data is 134.4 and the minimum value is 125.9, both of which exceed the standard specification range (127.8, 132.4). The summarized data shows that the proportion of data within the standard specification range is 70% < 100%, so the sample is unqualified.

[0076] Step 4: Match the categorized data with the measurement locations one by one. Data at test point 1 is located below the standard specification range and is shown in yellow; data at test point 2 is concentrated above the standard specification range and is shown in red; data at test point 3 is concentrated within the standard specification range and is shown in green. Based on the data results, output the flip diagram corresponding to the different colors of the test trajectory locations (e.g., a fully red scan trajectory as shown in step 2 indicates that there are different degrees of flipping at the three feature locations), and give the data failure result.

[0077] Step 5: Remove the test sample and visually inspect it manually according to the location indicators. It was found that the sample actually folded at a trapezoidal angle. Test point 1 was missing a layer, test point 2 had multiple layers, and test point 3 had a normal number of layers. The fold occurred at point 1 and then folded to point 2, consistent with the output results. This indicates the judgment was correct.

[0078] The sample information for Example 1 and Example 2 is summarized in Table 1:

[0079] Table 1

[0080] project Example 1 Example 2 standard (127.8,132.4) (127.8,132.4) Measured maximum value 132.2 134.4 Measured minimum value 127.9 125.9 Percentage of acceptable thickness data 100% 70% Display position and color All green #1 Yellow + #2 Red + #3 Green Is it accurate? precise precise

[0081] Further embodiments of this application provide an electrode tab folding conformity testing device for implementing the electrode tab folding conformity testing method, comprising:

[0082] The data collection unit is used to collect thickness data information of the characteristic positions of the electrode tabs after the electrode tabs are folded and the electrode group sample is fixed, so as to obtain the characteristic thickness data of the sample.

[0083] The data processing and judgment unit is used to compare the sample characteristic thickness data with the pre-obtained standard specification range, and judge the qualification of the sample tab folding based on the comparison result.

[0084] Further embodiments of this application include:

[0085] The result conversion feedback unit is used to map the sample characteristic thickness data to the electrode characteristic position one by one and output a result feedback image; the result feedback image is used to distinguish the electrode folding qualification of the electrode characteristic position by different colors.

[0086] In this application, the data collection unit uses a laser thickness gauge to measure the thickness of the tabs after they are folded and fixed, obtaining sample characteristic data. Simultaneously, it summarizes and generalizes the raw data, and based on previous data accumulation, obtains and defines a risk-controllable data fluctuation range to arrive at a standard specification range. The data processing and judgment unit compares the sample characteristic thickness data obtained by the data collection unit with the pre-obtained standard specification range, and judges the passability of the tab folding based on the comparison result.

[0087] In this embodiment, the result conversion feedback unit is used to perform fitting and conversion processing on the analyzed classification data, mapping it to different states of tab folding, establishing a correspondence between thickness measurement data, folding state, and folding position, and providing graphical results of tab folding detection based on objective data. This can avoid the influence of subjective factors brought about by the visual solution, improve accuracy, and reduce manufacturing costs.

[0088] For the specific technical solution or content of the tab folding conformity testing device of this application, please refer to the description of the tab folding conformity testing method.

[0089] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0090] Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the invention.

[0091] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for testing the conformity of tab folding, characterized in that, Including the following steps: After the electrode tabs are folded together and the sample of the electrode group is fixed, thickness data information of the characteristic positions of the electrode tabs is collected to obtain the characteristic thickness data of the sample. The sample characteristic thickness data is compared with the pre-obtained standard specification range, and the passability of the sample tab folding is determined based on the comparison results.

2. The method for detecting the conformity of tab folding according to claim 1, characterized in that, After obtaining the comparison result, the method further includes: After mapping the sample characteristic thickness data to the tab feature position and folding state one by one, a result feedback image is output; the result feedback image is used to distinguish the tab folding state that represents the tab feature position through color.

3. The method for detecting the conformity of tab folding according to claim 1, characterized in that, The standard specification range is obtained by collecting and analyzing thickness data at the characteristic locations of multiple electrode group samples with defect-free electrodes.

4. The method for detecting the conformity of tab folding according to claim 1, characterized in that, The electrode tab feature positions are selected from multiple feature areas based on the width of the top bottom of the electrode tab after folding.

5. The method for detecting the conformity of tab folding according to claim 4, characterized in that, The range of the feature region is determined by the product of the number of scans performed by the testing equipment in a single test and the minimum area measured in a single test.

6. The method for detecting the conformity of tab folding according to claim 1, characterized in that, The standard specification range is determined by the following formula: ； in, This represents a calculation function based on a standard specification range for thickness. For the first Standard thickness of a single-layer electrode The deviation coefficient, For the first The tolerance for single-layer tabs is as follows: This is the compensation value.

7. The method for detecting the conformity of tab folding according to claim 2, characterized in that, The sample characteristic thickness data corresponds one-to-one with the electrode characteristic position, and is processed by the following conversion formula: ； in, This represents a transformation function based on the thickness data of the sampling points. As compensation value, , For the first The periodic eigenvalue coefficients of each sampling point For the amount of data, For the first Thickness data at each sampling point This refers to the perimeter of the thickness measuring device's operating trajectory.

8. The method for detecting the conformity of tab folding according to claim 1, characterized in that, Thickness data was collected at the characteristic locations of the electrode tabs using a laser thickness gauge.

9. The method for detecting the conformity of tab folding according to claim 1, characterized in that, The height of the tabs on the tested electrode group samples are arranged in an arithmetic progression increasing from the outer ring inwards.

10. A device for detecting the conformity of tab folding, used to implement the tab folding conformity detection method according to any one of claims 1-9, characterized in that, include: The data collection unit is used to collect thickness data information of the characteristic positions of the electrode tabs after the electrode tabs are folded and the electrode group sample is fixed, so as to obtain the characteristic thickness data of the sample. The data processing and judgment unit is used to compare the sample characteristic thickness data with the pre-obtained standard specification range, and judge the qualification of the sample tab folding based on the comparison result. Preferred options also include: The result conversion feedback unit is used to map the sample feature thickness data to the electrode feature position one by one and output the result feedback diagram. The result feedback diagram is used to distinguish the passability of electrode folding by different colors, which characterizes the electrode characteristic position.

Images