Die cutting system and method

Abstract

The invention discloses a die-cutting system and method, the system comprising: a sensor, a controller and a laser; the sensor is used for collecting the pole piece thickness data of the pole piece and sending the pole piece thickness data to the controller; the controller is used for determining the starting point of a thickness thinning zone according to the change of the pole piece thickness data, calculating the first distance from the starting point of the thickness thinning zone to the laser, calculating the die-cutting waiting time according to the first distance, and sending the die-cutting waiting time to the laser; the laser is used for die-cutting the pole piece after the die-cutting waiting time is interval to obtain a first pole ear; because the present application determines the starting point of the thickness thinning zone by the change of the pole piece thickness, and guides the laser to cut the first pole ear according to the starting point of the thickness thinning zone, the position of the thickness thinning zone can be accurately identified in the die-cutting process, and then the first pole ear can be accurately cut at the designed spacing before the thickness thinning zone in the die-cutting process, so that the thickness thinning zone is at the corner of the battery cell winding.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a die-cutting system and method. Background Art

[0002] The existing coating production process is to evenly coat a layer of slurry on the pole piece. After the coating is made into a battery cell through a series of operations such as rolling, die cutting, winding, and compaction, the coating may fall off at the corners, causing lithium deposition in the battery cell and causing safety accidents. Therefore, in order to overcome the above defects, the relevant technology proposes a new coating process, that is, using a double die head, the first die head evenly coats a layer, and the second die head coats another layer at a certain distance (coating gap length) on the basis of the first coating, which is the second coating.

[0003] In the winding stage, in order to make the thickness reduction area at the corner of the battery cell winding, it is necessary to accurately cut the first pole ear at the designed spacing before the thickness reduction area in the die-cutting process. Therefore, how to accurately cut the first pole ear at the designed spacing before the thickness reduction area in the die-cutting process is a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of the above problems, the present invention provides a die-cutting system and method, aiming to solve the problem of how to accurately cut the first pole ear at the designed spacing before the thickness thinning area in the die-cutting process.

[0005] In a first aspect, the present invention provides a die-cutting system, the die-cutting system comprising: a sensor, a controller and a laser; The sensor is used to collect the pole piece thickness data of the pole piece and send the pole piece thickness data to the controller; The controller is used to determine the starting point of the thickness thinning zone according to the change of the pole piece thickness data, calculate the first distance from the starting point of the thickness thinning zone to the laser, calculate the die-cutting waiting time according to the first distance, and send the die-cutting waiting time to the laser; The laser is used to die-cut the pole piece after the die-cutting waiting time to obtain the first pole ear.

[0006] In the technical solution of the embodiment of the present invention, the starting point of the thickness thinning zone is determined by measuring the change in the electrode thickness data, and the laser is guided to cut the first pole ear according to the starting point of the thickness thinning zone, so that the position of the thickness thinning zone can be accurately identified in the die-cutting process, and then the first pole ear can be accurately cut at the designed spacing before the thickness thinning zone in the die-cutting process, so that the thickness thinning zone is at the corner of the battery cell winding.

[0007] In some embodiments, the die-cutting system further includes: an encoder, an image collector, and an encoding roller corresponding to the encoder; the encoding roller is driven to rotate when the pole piece is conveyed, and the rotation of the encoding roller drives the encoder to trigger a pulse; The sensor is used to collect the pole piece thickness data of the pole piece in response to the pulse, and send the pole piece thickness data to the controller; The image collector is used to collect the image of the pole piece after die cutting in response to the pulse, and send the image of the pole piece after die cutting to the controller; The controller is used to perform defect detection on the die-cut pole piece according to the image of the die-cut pole piece.

[0008] In the technical solution of the embodiment of the present invention, a pulse is triggered when the pole piece is walking on the tape, and in response to the pulse, the pole piece thickness data of the pole piece and the image of the pole piece after die-cutting are collected, so as to achieve consistency between the pole piece walking and the pole piece detection, thereby improving the accuracy of the pole piece detection.

[0009] In some embodiments, the die-cutting waiting time is the number of die-cutting waiting pulses; The controller is further used to obtain the encoder accuracy of the encoder, and calculate the die-cutting waiting pulse number according to the pulse accuracy and the first distance; and send the die-cutting waiting pulse number to the laser; The laser is also used to die-cut the pole piece after the die-cutting waiting pulse number is spaced to obtain the first pole ear.

[0010] In the technical solution of the embodiment of the present invention, the number of die-cutting waiting pulses is calculated according to the encoder accuracy. After the number of die-cutting waiting pulses is calculated, the laser is controlled to die-cut the pole piece to obtain the first pole ear, thereby reducing the influence of the pole piece tape speed on the laser die-cutting of the first pole ear, thereby improving the accuracy of die-cutting of the first pole ear.

[0011] In some embodiments, the controller is further used to obtain a die-cutting error of the first pole tab according to the image of the pole piece after die-cutting; if the die-cutting error is not within a preset error range, an error correction instruction is generated according to the die-cutting error; The laser is also used to die-cut the pole piece according to the error correction instruction after the die-cutting waiting time to obtain the next first pole ear.

[0012] In the technical solution of the embodiment of the present invention, the die-cutting error of the first pole ear is obtained by using the image of the pole piece after die-cutting. If the die-cutting error is not within the preset error range, an error correction instruction is generated according to the die-cutting error to control the laser, thereby forming a complete closed-loop detection system, and then the process of laser die-cutting the first pole ear can be corrected in time, thereby improving the reliability of the die-cutting system.

[0013] In some embodiments, the controller is also used to obtain a second distance from the sensor to the laser, and to obtain a running distance of the pole piece when the sensor collects the pole piece thickness data; and to calculate a first distance from the starting point of the thickness thinning zone to the laser based on the second distance and the running distance.

[0014] In the technical solution of the embodiment of the present invention, when calculating the first distance, the second distance from the sensor to the laser and the pole piece walking distance when the sensor collects pole piece thickness data are also considered, thereby improving the accuracy of the first distance calculation and further improving the accuracy of the first pole ear die cutting.

[0015] In some embodiments, the sensor, the laser, the encoding roller and the image collector are sequentially arranged in the tape running direction of the pole piece, the data acquisition direction of the sensor is perpendicular to the tape running direction of the pole piece, the light outlet of the laser is perpendicular to the tape running direction of the pole piece, and the image acquisition direction of the image collector is perpendicular to the tape running direction of the pole piece.

[0016] In the technical solution of the embodiment of the present invention, the sensor, laser, encoding roller and image collector are arranged in sequence in the tape running direction of the pole piece, and the direction of data acquisition and laser die-cutting is set perpendicular to the tape running direction of the pole piece, thereby improving the accuracy of data acquisition and laser die-cutting.

[0017] In some embodiments, the sensor includes a first sensor and a second sensor, the first sensor and the second sensor are arranged on both sides of the pole piece in a facing manner, and the data collection direction of the first sensor and the second sensor is perpendicular to the pole piece.

[0018] In the technical solution of the embodiment of the present invention, a first sensor and a second sensor are respectively arranged on both sides of the pole piece, and the first sensor and the second sensor collect the pole piece thickness data of the pole piece in a counter-radiation form, thereby improving the accuracy of the pole piece thickness data.

[0019] In some embodiments, the image collector includes a first image collector, a second image collector, a third image collector, and a fourth image collector; The first image collector is used to detect the front defects of the electrode sheet after die-cutting; The second image collector is used to detect backlight defects of the die-cutting electrode sheet; The third image collector and the fourth image collector are used to detect the back surface defects of the electrode sheet after die-cutting.

[0020] In the technical solution of the embodiment of the present invention, multiple image collectors are arranged at multiple positions to detect the defects of the pole piece, thereby improving the comprehensiveness and accuracy of the pole piece defect detection.

[0021] In some embodiments, the first image collector includes a first camera and a first light source, and the first camera and the first light source are arranged on the same side of the pole piece; the second image collector includes a second camera and a second light source, and the second camera and the second light source are respectively arranged on both sides of the pole piece; the third image collector includes a third camera and a third light source, and the third camera and the third light source are arranged on the same side of the pole piece; the fourth image collector includes a fourth camera and a fourth light source, and the fourth camera and the fourth light source are arranged on the same side of the pole piece.

[0022] In the technical solution of the embodiment of the present invention, the first image collector, the third image collector and the fourth image collector use coaxial light, that is, the camera and the light source are arranged on the same side of the pole piece, perpendicular to the pole piece, and the second image collector uses backlighting, that is, the camera and the light source are respectively arranged on both sides of the pole piece, perpendicular to the pole piece, thereby improving the image acquisition effect of the image collector.

[0023] In some embodiments, the controller is also used to obtain the inflection point coordinates of the thickness thinning zone and the starting point coordinates of each pole piece strip, wherein the pole piece strip is a strip corresponding to a pole piece with a length of a battery cell; the length of the thickness thinning zone is calculated according to the inflection point coordinates of the thickness thinning zone, and the length of each pole piece strip is calculated according to the starting point coordinates of each pole piece strip.

[0024] In the technical solution of the embodiment of the present invention, the length of the thickness thinning zone is calculated according to the inflection point coordinates of the thickness thinning zone, and the length of each pole piece strip is calculated according to the starting point coordinates of each pole piece strip, so that the length of the thickness thinning zone and the length of each pole piece strip can be accurately calculated.

[0025] In some embodiments, the die-cutting system further includes: a calibration ruler, the calibration ruler being arranged on the encoding roller; the calibration ruler is driven to rotate by the rotation of the encoding roller, and the rotation of the encoding roller drives the encoder to trigger a calibration pulse; The image collector is further used to collect a calibration image of the calibration ruler in response to the calibration pulse, and send the calibration image to the controller; The controller is further used to obtain calibration scale parameters of the calibration scale, calculate the calibration accuracy according to the calibration image and the calibration scale parameters, wherein the calibration accuracy is used to represent the mapping relationship between pixel distance and actual distance; calculate the length of the thickness thinning area according to the calibration accuracy and the inflection point coordinates of the thickness thinning area, and calculate the length of each pole piece strip according to the calibration accuracy and the starting point coordinates of each pole piece strip.

[0026] In the technical solution of the embodiment of the present invention, the sensor is calibrated indirectly by calibrating the image collector, so that the target calibration accuracy can be determined, thereby improving the accuracy of subsequent calculations of the length of the thickness thinning area and the length of each pole piece strip.

[0027] In some embodiments, the sensor is a spectral confocal displacement sensor, which includes: a point light source, a dispersive confocal probe, a spectroscopic component, and a detector; The point light source is used to emit detection light to the pole piece, and the detection light forms detection light of different wavelengths after passing through the dispersive confocal probe, wherein when the detection light of different wavelengths is irradiated onto the pole piece, the return light of the pole piece is connected to the detector through the light splitting component, and the light splitting component is used to shield the light of unfocused wavelength in the return light; The detector is used to obtain the wavelength of the returning light, and search for the pole piece thickness data corresponding to the wavelength of the light in a preset wavelength relationship table, wherein the preset wavelength relationship table includes the correspondence between the wavelength of the light and the pole piece thickness data; and send the pole piece thickness data to the controller.

[0028] In the technical solution of the embodiment of the present invention, the sensor is set as a spectral confocal displacement sensor, so as to reduce the volume of the sensor, reduce the measurement blind area, and improve the anti-interference ability.

[0029] In a second aspect, the present invention provides a die-cutting method, comprising: Collecting the pole piece thickness data of the pole piece; Determine the starting point of the thickness thinning zone according to the change of the electrode thickness data, calculate the first distance from the starting point of the thickness thinning zone to the electrode die-cutting position, and calculate the die-cutting waiting time according to the first distance; After the die-cutting waiting time, the pole piece is die-cut at the pole piece die-cutting position to obtain a first pole ear.

[0030] In the technical solution of the embodiment of the present invention, the starting point of the thickness thinning zone is determined by measuring the change in the electrode thickness data, and the laser is guided to cut the first pole ear according to the starting point of the thickness thinning zone, so that the position of the thickness thinning zone can be accurately identified in the die-cutting process, and then the first pole ear can be accurately cut at the designed spacing before the thickness thinning zone in the die-cutting process, so that the thickness thinning zone is at the corner of the battery cell winding.

[0031] In some embodiments, before collecting the pole piece thickness data of the pole piece, the method further includes: When the pole piece is running, the pulse is triggered; The collecting of the pole piece thickness data of the pole piece comprises: In response to the pulse, collecting pole piece thickness data of the pole piece; After the die-cutting waiting time, the electrode piece is die-cut at the electrode piece die-cutting position to obtain the first electrode ear, and the method further includes: In response to the pulse, an image of the die-cut pole piece is collected, and defect detection is performed on the die-cut pole piece based on the image of the die-cut pole piece.

[0032] In the technical solution of the embodiment of the present invention, a pulse is triggered when the pole piece is walking on the tape, and in response to the pulse, the pole piece thickness data of the pole piece and the image of the pole piece after die-cutting are collected, so as to achieve consistency between the pole piece walking and the pole piece detection, thereby improving the accuracy of the pole piece detection.

[0033] In some embodiments, the die-cutting waiting time is the number of die-cutting waiting pulses; and the step of calculating the die-cutting waiting time according to the first distance includes: obtaining a pulse accuracy of the pulse; Calculate the number of die-cutting waiting pulses according to the pulse accuracy and the first distance; Correspondingly, after the die-cutting waiting time, die-cutting the pole piece at the pole piece die-cutting position to obtain the first pole ear includes: After the die-cutting waiting pulse number is exceeded, the pole piece is die-cut at the pole piece die-cutting position to obtain a first pole ear.

[0034] In the technical solution of the embodiment of the present invention, the number of waiting pulses for die-cutting is calculated according to the pulse accuracy, and after the number of waiting pulses for die-cutting is calculated, the pole piece is die-cut to obtain the first pole ear, thereby reducing the influence of the pole piece tape speed on the die-cutting of the first pole ear, and further improving the accuracy of die-cutting of the first pole ear.

[0035] In some embodiments, after the die-cutting waiting time, the electrode piece is die-cut at the electrode piece die-cutting position to obtain the first electrode ear, and further includes: Acquire a die-cutting error of the first pole tab according to the image of the pole piece after die-cutting; If the die-cutting error is not within the preset error range, generating an error correction instruction according to the die-cutting error; After the die-cutting waiting time, the pole piece is die-cut at the pole piece die-cutting position according to the error correction instruction to obtain the next first pole lug.

[0036] In the technical solution of the embodiment of the present invention, the die-cutting error of the first pole ear is obtained by using the image of the pole piece after die-cutting. If the die-cutting error is not within the preset error range, an error correction instruction is generated according to the die-cutting error to control the laser, thereby forming a complete closed-loop detection system, and then the process of laser die-cutting the first pole ear can be corrected in time, thereby improving the reliability of the die-cutting system.

[0037] In some embodiments, the step of calculating the first distance from the starting point of the thickness thinning zone to the pole piece die cutting position includes: Acquire a second distance between a collection position of the pole piece thickness data and a pole piece die-cutting position; Acquiring the walking distance of the pole piece when collecting the pole piece thickness data; The first distance from the starting point of the thickness thinning zone to the pole piece die-cutting position is calculated according to the second distance and the tape running distance.

[0038] In the technical solution of the embodiment of the present invention, when calculating the first distance, the second distance from the sensor to the laser and the pole piece walking distance when the sensor collects pole piece thickness data are also considered, thereby improving the accuracy of the first distance calculation and further improving the accuracy of the first pole ear die cutting.

[0039] In some embodiments, the step of performing defect detection on the die-cut electrode sheet according to the image of the die-cut electrode sheet comprises: Acquiring frequency characteristics of the image of the electrode sheet after die-cutting, and removing noise from the image of the electrode sheet after die-cutting according to the frequency characteristics to obtain a processed image; Acquire an edge texture image of the electrode sheet after die-cutting according to the image of the electrode sheet after die-cutting and the processed image; Defect detection is performed on the die-cutting rear electrode according to the edge texture image.

[0040] In the technical solution of the embodiment of the present invention, the frequency characteristics of the image of the pole piece after die-cutting are first obtained, and then the noise of the image of the pole piece after die-cutting is removed according to the frequency characteristics to obtain a processed image, and then the edge texture image of the pole piece after die-cutting is obtained according to the image of the pole piece after die-cutting and the processed image, and defect detection is performed on the pole piece after die-cutting according to the edge texture image, thereby improving the accuracy of gap coating tailing detection.

[0041] In some embodiments, determining the starting point of the thickness thinning area according to the change of the pole piece thickness data includes: Constructing an objective function according to the pole piece thickness data, wherein the objective function is used to represent the thickness change of the pole piece; Determining the inflection point of the thickness thinning zone according to the objective function; The starting point of the thickness thinning zone is determined according to the inflection point of the thickness thinning zone and the tape running direction of the pole piece.

[0042] In the technical solution of the embodiment of the present invention, an objective function is first constructed according to the pole piece thickness data, and then the inflection point of the thickness thinning zone is determined according to the objective function, and the starting point of the thickness thinning zone is determined according to the inflection point of the thickness thinning zone and the tape running direction of the pole piece, thereby improving the accuracy of the starting point of the thickness thinning zone.

[0043] In some embodiments, determining the inflection point of the thickness thinning area according to the objective function includes: Calculating the intersection point between a preset threshold and the objective function; The inflection point of the thickness reduction zone is determined according to the intersection point.

[0044] In the technical solution of the embodiment of the present invention, the inflection point of the thickness thinning area is determined by calculating the intersection point between the preset threshold and the derivative of the logic function and determining the inflection point of the thickness thinning area according to the intersection point, thereby being able to calculate the inflection point of the thickness thinning area.

[0045] In some embodiments, determining the inflection point of the thickness thinning area according to the objective function includes: Calculating the maximum or minimum value of the objective function; The inflection point of the thickness reduction zone is determined according to the maximum value or the minimum value.

[0046] In the technical solution of the embodiment of the present invention, the inflection point of the thickness thinning zone is determined based on the measurement scheme of the steepest descent / steepest ascent point, thereby improving the accuracy of the inflection point of the coating gap, and further improving the calculation accuracy of the length of the thickness thinning zone and the length of each pole piece strip.

[0047] In some embodiments, after determining the inflection point of the thickness thinning area according to the objective function, the method further includes: Obtaining the inflection point coordinates of the thickness thinning area and the starting point coordinates of each pole piece strip, wherein the pole piece strip is a strip corresponding to a pole piece of a battery cell length; The length of the thickness thinning zone is calculated according to the coordinates of the inflection point of the thickness thinning zone, and the length of each pole piece strip is calculated according to the coordinates of the starting point of each pole piece strip.

[0048] In the technical solution of the embodiment of the present invention, the length of the thickness thinning zone is calculated according to the inflection point coordinates of the thickness thinning zone, and the length of each pole piece strip is calculated according to the starting point coordinates of each pole piece strip, so that the length of the thickness thinning zone and the length of each pole piece strip can be accurately calculated.

[0049] In some embodiments, before calculating the length of the thickness thinning zone according to the inflection point coordinates of the thickness thinning zone and calculating the length of each pole piece strip according to the starting point coordinates of each pole piece strip, the method further includes: Acquiring a calibration image of the calibration ruler and obtaining calibration ruler parameters of the calibration ruler; Calculating a calibration accuracy according to the calibration image and the calibration ruler parameters, wherein the calibration accuracy is used to represent a mapping relationship between a pixel distance and an actual distance; Accordingly, the calculating of the length of the thickness thinning zone according to the inflection point coordinates of the thickness thinning zone, and the calculating of the length of each pole piece strip according to the starting point coordinates of each pole piece strip, comprises: The length of the thickness thinning zone is calculated according to the calibration accuracy and the coordinates of the inflection point of the thickness thinning zone, and the length of each pole piece strip is calculated according to the calibration accuracy and the coordinates of the starting point of each pole piece strip.

[0050] In the technical solution of the embodiment of the present invention, the sensor is calibrated indirectly by calibrating the image collector, so that the target calibration accuracy can be determined, thereby improving the accuracy of subsequent calculations of the length of the thickness thinning area and the length of each pole piece strip.

[0051] In some embodiments, the collecting the pole piece thickness data of the pole piece includes: emitting detection light of different wavelengths to the pole piece, wherein when the detection light of different wavelengths is irradiated onto the pole piece, the light of unfocused wavelength in the return light of the pole piece is blocked; Receive the return light of the pole piece, and obtain the wavelength of the return light, and search for the pole piece thickness data corresponding to the wavelength of the light in a preset wavelength relationship table, wherein the preset wavelength relationship table includes the correspondence between the wavelength of the light and the pole piece thickness data.

[0052] In the technical solution of the embodiment of the present invention, the pole piece thickness data is collected by using the wavelength of the light returning from the pole piece, thereby reducing the volume of the sensor, reducing the measurement blind area, and improving the anti-interference ability.

[0053] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the new coating process; Figure 2 Schematic diagram of gap coating; Figure 3 It is a schematic diagram of the pole piece after roller pressing and slitting; Figure 4 This is a schematic diagram of the pole piece after die-cutting and striping; Figure 5 Schematic diagram of a die-cutting system according to some embodiments of the present invention; Figure 6 A schematic diagram of the tape transport of a die-cutting system according to some embodiments of the present invention; Figure 7 Schematic diagram of a die-cutting system according to some embodiments of the present invention; Figure 8 A schematic diagram of the tape transport of a die-cutting system according to some embodiments of the present invention; Fig. 9 A schematic diagram of the tape transport of a die-cutting system according to some embodiments of the present invention; Fig.10 A schematic diagram of the thickness of the thinned area of ​​some embodiments of the present invention; Fig.11 Schematic diagram of a calibration ruler in some embodiments of the present invention; Fig.12 A schematic diagram of a calibration image according to some embodiments of the present invention; Fig.13 A schematic diagram of thickness measurement by a spectral confocal displacement sensor according to some embodiments of the present invention; Fig.14 A flow chart of a gap die cutting deviation correction method according to some embodiments of the present invention; Fig.15 A flow chart of a gap die cutting deviation correction method according to some embodiments of the present invention; Fig.16 A flow chart of a gap die cutting deviation correction method according to some embodiments of the present invention; Fig.17 Three views of the image collector of some embodiments of the present invention; Fig.18 A schematic diagram of finding the inflection point of the thickness thinning area in some embodiments of the present invention; Fig.19 Schematic diagram of calculating the inflection point of the thickness thinning area according to some embodiments of the present invention.

[0055] The reference numerals in the specific implementation manner are as follows: Thickness thinning area 10, film area 11, foil 12, first coating 13, second coating 14, pole ear area 20, first pole ear 40, sensor 50, laser 51, roller 60, encoder 61, encoding roller 62, image collector 63, first sensor 80, second sensor 81, first image collector 91, second image collector 92, third image collector 93, fourth image collector 94, first marking machine 95, second marking machine 96, calibration plate 100, first spectral confocal displacement sensor 101, second spectral confocal displacement sensor 102, camera 160 and lighting equipment 161. DETAILED DESCRIPTION

[0056] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0058] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0059] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0060] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0061] In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0062] In the description of the embodiments of the present invention, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention.

[0063] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0064] At present, from the perspective of market development, the application of batteries is becoming more and more extensive. Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of battery application areas, its market demand is also constantly expanding.

[0065] The existing coating production process is to evenly coat a layer of slurry on the electrode. After the coating is made into a battery cell through a series of operations such as rolling, die cutting, winding, and compaction, the coating may fall off at the corners, causing lithium deposition in the battery cell and causing safety accidents. Therefore, in order to overcome the above defects, the relevant technology proposes a new coating process. The new coating process is as follows: Figure 1 As shown, Figure 1 This is a side view of the pole piece in the new coating process. Figure 1In the process, positive electrode material is coated on both sides of the foil 12 to form a film area 11. When coating one side of the positive electrode material, a double die head is used. The first die head evenly coats a layer (i.e., the first coating layer 13). The second die head coats another layer (i.e., the second coating layer 14) at a certain distance (coating gap length) on the basis of the first coating layer, so that the corner of the manufactured battery cell is a thickness-reduced area 10. Gap coating is as follows Figure 2 As shown, Figure 2 This is a top view of the pole piece in the new coating process. Figure 2 In the figure, the pole piece after gap coating includes a thickness reduction area 10, a membrane area 11 and a pole ear area 20.

[0066] Before the gap-coated electrode sheet is wound into a battery cell, it needs to be rolled and die-cut. Rolling is to compact and cut the gap-coated electrode sheet. Figure 3 As shown, Figure 3 This is a top view of the electrode in the new coating process. Die cutting is to cut the electrode ears and strips after rolling. The electrode after die cutting and stripping is as follows Figure 4 As shown, Figure 4 This is a top view of the pole piece in the new coating process, such as Figure 4 As shown, in the winding stage, in order to make the thickness reduction area at the corner of the battery cell winding, it is necessary to accurately cut the first pole ear 40 at the designed spacing before the thickness reduction area 10 in the die-cutting process. Therefore, how to accurately cut the first pole ear at the designed spacing before the thickness reduction area in the die-cutting process is a technical problem to be solved urgently.

[0067] In order to solve the problem of how to accurately cut the first pole ear at the designed spacing before the thickness thinning zone in the die-cutting process, the starting point of the thickness thinning zone can be determined by measuring the change in the pole piece thickness data, and the laser can be guided to cut the first pole ear according to the starting point of the thickness thinning zone, so that the position of the thickness thinning zone can be accurately identified in the die-cutting process, and then the first pole ear can be accurately cut at the designed spacing before the thickness thinning zone in the die-cutting process, so that the thickness thinning zone is at the corner of the battery cell winding.

[0068] In some embodiments, a die-cutting system is proposed, which includes: a sensor, a controller and a laser; the sensor is used to collect pole piece thickness data of the pole piece, and send the pole piece thickness data to the controller; the controller is used to determine the starting point of the thickness thinning zone according to the change of the pole piece thickness data, calculate the first distance from the starting point of the thickness thinning zone to the laser, calculate the die-cutting waiting time according to the first distance, and send the die-cutting waiting time to the laser; the laser is used to die-cut the pole piece after the die-cutting waiting time to obtain the first pole ear.

[0069] In order to make the thickness reduction zone at the corner of the battery cell winding, it is necessary to accurately cut the first pole ear at the designed spacing before the thickness reduction zone in the die-cutting process. Therefore, it is necessary to accurately identify the position of the thickness reduction zone in the die-cutting process, and guide the laser to cut the first pole ear according to the position of the thickness reduction zone. In order to accurately identify the position of the thickness reduction zone in the die-cutting process, in this embodiment, the pole piece thickness data of the pole piece is collected by a sensor, and the starting point of the thickness reduction zone is determined according to the change of the pole piece thickness data. In order to accurately cut the first pole ear at the designed spacing before the thickness reduction zone, in this embodiment, the first distance from the starting point of the thickness reduction zone to the laser is first calculated, the die-cutting waiting time is calculated according to the first distance, and the laser is controlled. After the die-cutting waiting time, the pole piece is die-cut to obtain the first pole ear.

[0070] For ease of understanding, refer to Figure 5 This invention is provided for illustration, but is not intended to limit the present application. Figure 5 Schematic diagram of die-cutting system in some embodiments of the present invention, as an example, Figure 5 In the figure, it is assumed that the design spacing between the starting point of the thickness thinning area and the midpoint of the first pole ear is L, and the pole piece running direction is shown by the arrow in the figure. Figure 5 In the die-cutting system, a sensor 50, a controller and a laser 51 are included. When the pole piece is conveyed, the sensor 50 collects the pole piece thickness data of the pole piece by emitting a detection light, and sends the pole piece thickness data to the controller. The sensor 50 may be a point laser thickness gauge or a spectral confocal displacement sensor, which is not limited in this embodiment. After receiving the pole piece thickness data, the controller determines the starting point of the thickness thinning zone by analyzing the change of the pole piece thickness data (for example, the first drop point when the pole piece thickness data drops continuously can be determined as the starting point of the thickness thinning zone). After determining the starting point of the thickness thinning zone, the first distance L1 from the starting point of the thickness thinning zone to the laser 51 is obtained. After obtaining the first distance L1 from the starting point of the thickness thinning zone to the laser 51, the die-cutting waiting time T of the laser 51 can be calculated according to the pole piece's tape running speed V (assuming that the pole piece is tape-running at a uniform speed) and the designed spacing L between the starting point of the thickness thinning zone and the midpoint of the first pole ear. The specific calculation formula is T=(L1-L) / V. After obtaining the die-cutting waiting time T, the controller sends the die-cutting waiting time T to the laser 51. After the die-cutting waiting time, the laser 51 die-cuts the pole ear area 20 of the pole piece to obtain the first pole ear 40.

[0071] This embodiment determines the starting point of the thickness thinning zone by measuring the change in the electrode thickness data, and guides the laser to cut the first pole ear according to the starting point of the thickness thinning zone, so that the position of the thickness thinning zone can be accurately identified in the die-cutting process, and then the first pole ear can be accurately cut at the designed spacing before the thickness thinning zone in the die-cutting process, so that the thickness thinning zone is at the corner of the battery cell winding.

[0072] In some embodiments, the die-cutting system also includes: an encoder, an image collector, and an encoding roller corresponding to the encoder; the encoding roller is driven to rotate when the pole piece is walking, and the rotation of the encoding roller drives the encoder to trigger a pulse; the sensor is used to respond to the pulse, collect the pole piece thickness data of the pole piece, and send the pole piece thickness data to the controller; the image collector is used to respond to the pulse, collect the image of the pole piece after die-cutting, and send the image of the pole piece after die-cutting to the controller; the controller is used to perform defect detection on the pole piece after die-cutting according to the image of the pole piece after die-cutting.

[0073] In order to achieve consistency between the electrode tape and the electrode detection, in this embodiment, a pulse is triggered when the electrode tape is running, and in response to the pulse, the electrode thickness data of the electrode and the image of the electrode after die cutting are collected. Figure 6 This invention is provided for illustration, but is not intended to limit the present application. Figure 6 The following is a schematic diagram of the tape transport of the die-cutting system of some embodiments of the present invention, as an example: Figure 6 In the figure, it is assumed that the design spacing between the starting point of the thickness thinning area and the midpoint of the first pole ear is L, and the pole piece running direction is shown by the arrow in the figure. Figure 6In the die-cutting system, the die-cutting system includes a roller 60, a sensor 50, a controller, a laser 51, an encoder 61, an image collector 63 and an encoding roller 62 corresponding to the encoder 61. The roller 60 drives the pole piece to move, and the pole piece movement drives the encoding roller 62 to rotate. The rotation of the encoding roller 62 drives the encoder 61 to trigger a pulse. The sensor 50 responds to the pulse, collects the pole piece thickness data of the pole piece by emitting a detection light, and sends the pole piece thickness data to the controller. After receiving the pole piece thickness data, the controller determines the starting point of the thickness thinning zone by analyzing the change of the pole piece thickness data (for example, the first drop point when the pole piece thickness data drops continuously can be determined as the starting point of the thickness thinning zone). After determining the starting point of the thickness thinning zone, the first distance L1 from the starting point of the thickness thinning zone to the laser 51 is obtained. After obtaining the first distance L1 from the starting point of the thickness thinning zone to the laser 51, the die-cutting waiting time T of the laser 51 can be calculated according to the pole piece's tape running speed V (assuming that the pole piece is tape running at a uniform speed) and the design spacing between the starting point of the thickness thinning zone and the midpoint of the first pole ear as L. The specific calculation formula is T=(L1-L) / V. After obtaining the die-cutting waiting time T, the controller sends the die-cutting waiting time T to the laser 51. After the laser 51 has an interval of the die-cutting waiting time, it performs die-cutting on the pole piece to obtain the first pole ear. The image collector 63 collects the image of the pole piece after die-cutting in response to the pulse, and sends the image of the pole piece after die-cutting to the controller. The image collector 63 may be a camera, and the image collector 63 may be set at multiple locations to detect multiple defects, for example, to detect conventional defects such as metal leakage, tab excess material, straight edge excess material, etc. Of course, the image collector 63 may also be set near the laser 51 to detect whether the actual distance between the starting point of the thickness thinning area and the midpoint of the first tab is equal to the designed distance between the starting point of the thickness thinning area and the midpoint of the first tab. The specific setting method may be as follows: Figure 7 After receiving the image of the die-cut rear electrode sheet, the controller performs defect detection on the die-cut rear electrode sheet according to the image of the die-cut rear electrode sheet.

[0074] This embodiment triggers a pulse when the pole piece is being walked, and in response to the pulse, collects the pole piece thickness data of the pole piece and the image of the pole piece after die-cutting, thereby achieving consistency between the pole piece walking and the pole piece detection, and further improving the accuracy of the pole piece detection.

[0075] In some embodiments, the die-cutting waiting time is the number of die-cutting waiting pulses; the controller is also used to obtain the encoder accuracy of the encoder, and calculate the number of die-cutting waiting pulses based on the pulse accuracy and the first distance; the number of die-cutting waiting pulses is sent to the laser; the laser is also used to die-cut the pole piece after an interval of the number of die-cutting waiting pulses to obtain the first pole ear.

[0076] Considering that the pole piece is not moving at a uniform speed in some cases, if the laser is still controlled to die-cut the first pole ear according to the die-cutting waiting time, the position of the first pole ear may be inaccurate. Therefore, in this embodiment, the number of die-cutting waiting pulses is calculated according to the encoder accuracy, and after the number of die-cutting waiting pulses is spaced, the laser is controlled to die-cut the pole piece to obtain the first pole ear.

[0077] For ease of understanding, the following examples are given, but are not intended to limit the present application. As an example, assuming that the design distance between the starting point of the thickness reduction zone and the midpoint of the first tab is L, the main working steps of the gap die cutting detection system include: 1. Collect the pole piece thickness data of the pole piece.

[0078] 2. Determine the starting point of the thickness thinning area based on the change in the electrode thickness data.

[0079] 3. Calculate the first distance L1 from the starting point of the thickness thinning area to the laser.

[0080] 4. According to the first distance L1 from the starting point of the thickness thinning zone to the laser, the design spacing L between the starting point of the thickness thinning zone and the midpoint of the first pole ear, and the encoder accuracy P, the die-cutting waiting pulse number X=(L1-L) / P is calculated. The laser starts cutting the first pole ear after waiting for X pulses, where the encoder accuracy P represents the number of pulses generated per encoder rotation.

[0081] 5. The camera takes pictures of the pole piece after laser die-cutting. In addition to calculating the conventional pole piece defects and dimensions, it can also detect whether the actual distance between the starting point of the thickness thinning area and the midpoint of the first pole ear is equal to the designed distance between the starting point of the thickness thinning area and the midpoint of the first pole ear.

[0082] This embodiment calculates the die-cutting waiting pulse number according to the encoder accuracy, and controls the laser to die-cut the pole piece after the die-cutting waiting pulse number is exceeded to obtain the first pole ear, thereby reducing the influence of the pole piece tape speed on the laser die-cutting of the first pole ear, thereby improving the accuracy of the die-cutting of the first pole ear.

[0083] In some embodiments, the controller is also used to obtain the die-cutting error of the first pole ear based on the image of the pole piece after die-cutting; if the die-cutting error is not within a preset error range, an error correction instruction is generated based on the die-cutting error; the laser is also used to die-cut the pole piece according to the error correction instruction after the die-cutting waiting time to obtain the next first pole ear.

[0084] In order to make timely error corrections in the process of laser die-cutting the first pole ear, in this embodiment, the actual distance between the starting point of the thickness thinning area and the midpoint of the first pole ear is obtained through the image of the pole piece after die-cutting, and the design distance between the starting point of the thickness thinning area and the midpoint of the first pole ear is obtained. The laser is controlled according to whether the die-cutting error between the actual distance and the design distance is within a preset error range, thereby forming a complete closed-loop detection system.

[0085] For ease of understanding, the following examples are given, but are not intended to limit the present application. As an example, assuming that the design distance between the starting point of the thickness reduction zone and the midpoint of the first tab is L, the main working steps of the gap die cutting detection system include: 1. Collect the pole piece thickness data of the pole piece.

[0086] 2. Determine the starting point of the thickness thinning area based on the change in the electrode thickness data.

[0087] 3. Calculate the first distance L1 from the starting point of the thickness thinning area to the laser.

[0088] 4. According to the first distance L1 from the starting point of the thickness thinning zone to the laser, the design spacing L between the starting point of the thickness thinning zone and the midpoint of the first pole ear, and the encoder accuracy P, the die-cutting waiting pulse number X=(L1-L) / P is calculated. The laser starts cutting the first pole ear after waiting for X pulses, where the encoder accuracy P represents the number of pulses generated per encoder rotation.

[0089] 5. The camera takes pictures of the pole piece after laser die-cutting. In addition to calculating the conventional pole piece defects and dimensions, it can also detect whether the actual distance between the starting point of the thickness thinning area and the midpoint of the first pole ear is equal to the designed distance between the starting point of the thickness thinning area and the midpoint of the first pole ear.

[0090] 6. Obtain the designed spacing between the starting point of the thickness thinning zone and the midpoint of the first pole ear, and calculate the spacing error between the actual spacing and the designed spacing; if the spacing error is within the preset error range, return to step 1 and continue to die-cut the next first pole ear, wherein the preset error range may be an error range pre-set according to specification requirements, which is not limited in this embodiment.

[0091] 7. If the spacing error is not within the preset error range, closed-loop control is performed with the laser. Specifically, the controller generates an error correction instruction based on the spacing error and sends the error correction instruction to the laser; after the laser waits for X pulses, it die-cuts the pole piece according to the error correction instruction to obtain the next first pole ear.

[0092] This embodiment obtains the die-cutting error of the first pole ear through the image of the pole piece after die-cutting. If the die-cutting error is not within the preset error range, an error correction instruction is generated according to the die-cutting error to control the laser, thereby forming a complete closed-loop detection system, and then timely error correction can be performed on the process of laser die-cutting the first pole ear, thereby improving the reliability of the die-cutting system.

[0093] In some embodiments, the controller is also used to obtain a second distance from the sensor to the laser, and to obtain a running distance of the pole piece when the sensor collects the pole piece thickness data; and to calculate a first distance from the starting point of the thickness thinning zone to the laser based on the second distance and the running distance.

[0094] In order to improve the accuracy of the first distance, in this embodiment, when calculating the first distance, the second distance from the sensor to the laser and the tape travel distance of the pole piece when the sensor collects the pole piece thickness data are also considered.

[0095] For ease of understanding, refer to Figure 6 and Figure 7 For illustration, but not limitation of the present application, as an example, it is assumed that the design spacing between the starting point of the thickness thinning zone and the midpoint of the first pole ear is L, and the pole piece tape running direction is shown by the arrow in the figure. The die-cutting system includes a roller 60, a sensor 50, a controller, a laser 51, an encoder 61, an image collector 63 and an encoding roller 62 corresponding to the encoder 61. The main working steps of the gap die-cutting detection system include: 1. The roller 60 drives the pole piece to move, and the pole piece moves the encoding roller 62 to rotate. The rotation of the encoding roller 62 drives the encoder 61 to trigger the pulse. After receiving the pulse trigger, the sensor 50 collects the pole piece thickness data at this time, and 5000 data are a group (can be pre-set).

[0096] 2. For the collected data, first preliminarily determine whether the data is an inflection point. The judgment logic is to compare the collected data with the preset data. The preset data is the thickness of the electrode in the thickness thinning area plus the thickness of the electrode in the non-thickness thinning area, divided by 2. If the collected data is less than the preset value, and the subsequent 500 points (settable) continue to be less than the value, then the point is a downward mutation point; similarly, if the collected data is greater than the preset value, and the subsequent 500 points (settable) continue to be greater than the value, then the point is an upward mutation point.

[0097] 3. According to the location of the mutation point found, smooth the 500 data before and after the mutation point, and then calculate the derivative to find the inflection point of the thickness thinning area.

[0098] 4. Assuming that the first inflection point of the thickness reduction zone (i.e., the starting point of the thickness reduction zone) is at the Mth point in the Nth array, after the N+1th data collection is completed, the first distance L1 from the starting point of the thickness reduction zone to the laser 51 is calculated by the following formula: L1=L2-(2*5000-M)*P*m / d In the formula, L1 represents the distance from the starting point of the thickness thinning zone to the laser 51, L2 represents the distance between the sensor 50 and the laser 51, (2*5000-M)*P*m / d represents the walking distance of the pole piece when the sensor collects the pole piece thickness data, (2*5000-M) represents the number of interval data points between the starting point of the thickness thinning zone and the end point of this data collection, P represents the accuracy of the encoder 61, m represents the frequency division of the sensor 50, and d represents the frequency division of the sensor 50.

[0099] 5. According to the first distance L1 from the starting point of the thickness thinning zone to the laser 51, the designed spacing L between the starting point of the thickness thinning zone and the midpoint of the first pole ear, and the accuracy P of the encoder 61, the die-cutting waiting pulse number X=(L1-L) / P is calculated. The laser 51 starts cutting the first pole ear after waiting for X pulses.

[0100] 6. The image collector 63 collects pictures of the gap electrode and the pole ear, and calculates the position from the first inflection point of the thickness thinning area to the pole ear based on the pictures, finds the outline of the pole ear based on the threshold, and then calculates the center position of the pole ear, and then calculates the position of the edge of the thickness thinning area based on the pictures, and then calculates the actual distance between the starting point of the thickness thinning area and the midpoint of the first pole ear.

[0101] 7. Obtain the designed spacing between the starting point of the thickness thinning zone and the midpoint of the first pole ear, calculate the spacing error between the actual spacing and the designed spacing, and if the spacing error is not within the preset error range, generate an error correction instruction based on the spacing error and the actual process requirements, and send the error correction instruction to the laser 51. The laser 51 then die-cuts the next first pole ear, and according to the error correction instruction, compensates for the distance of the pole ear cut by the laser 51.

[0102] When calculating the first distance, this embodiment also considers the second distance from the sensor to the laser and the pole piece walking distance when the sensor collects pole piece thickness data, thereby improving the accuracy of the first distance calculation and further improving the accuracy of the first pole ear die cutting.

[0103] In some embodiments, the sensor, the laser, the encoding roller and the image collector are sequentially arranged in the tape running direction of the pole piece, the data acquisition direction of the sensor is perpendicular to the tape running direction of the pole piece, the light outlet of the laser is perpendicular to the tape running direction of the pole piece, and the image acquisition direction of the image collector is perpendicular to the tape running direction of the pole piece.

[0104] In order to improve the accuracy of data collection and laser die-cutting, in this embodiment, the sensor, laser, encoding roller and image collector are sequentially arranged in the tape running direction of the pole piece, and the direction of data collection and laser die-cutting is set perpendicular to the tape running direction of the pole piece. Figure 6 This invention is provided for illustration, but is not intended to limit the present application. Figure 6 The following is a schematic diagram of the tape transport of the die-cutting system of some embodiments of the present invention, as an example: Figure 6 In the figure, the pole piece running direction is shown by the arrow in the figure, and the die-cutting system includes a roller 60, a sensor 50, a controller, a laser 51, an encoder 61, an image collector 63 and an encoding roller 62 corresponding to the encoder 61. The sensor 50, the laser 51, the encoding roller 62 and the image collector 63 are sequentially arranged in the running direction of the pole piece, wherein the sensor 50 is at the front to locate the thickness thinning area, and then the position of the thickness thinning area is transmitted to the controller, and the controller controls the laser 51 to cut the pole ear at a fixed position on the pole piece away from the thickness thinning area. The data acquisition direction of the sensor 50 is perpendicular to the running direction of the pole piece, the light outlet of the laser 51 is perpendicular to the running direction of the pole piece, and the image acquisition direction of the image collector 63 is perpendicular to the running direction of the pole piece. In a specific implementation, the shooting point of the image collector 63 can be located 3mm from the pole piece cutting point, and this embodiment does not limit this.

[0105] In this embodiment, the sensor, laser, encoding roller and image collector are arranged in sequence in the tape running direction of the pole piece, and the direction of data collection and laser die-cutting is arranged perpendicular to the tape running direction of the pole piece, thereby improving the accuracy of data collection and laser die-cutting.

[0106] In some embodiments, the sensor includes a first sensor and a second sensor, the first sensor and the second sensor are arranged on both sides of the pole piece in a facing manner, and the data collection direction of the first sensor and the second sensor is perpendicular to the pole piece.

[0107] In order to improve the accuracy of the pole piece thickness data, in this embodiment, a first sensor and a second sensor may be respectively provided on both sides of the pole piece, and the first sensor and the second sensor collect the pole piece thickness data of the pole piece in a counter-radiation manner.

[0108] For ease of understanding, refer to Figure 8 This invention is provided for illustration, but is not intended to limit the present application. Figure 8 The following is a schematic diagram of the tape transport of the die-cutting system of some embodiments of the present invention, as an example: Figure 8In the figure, the pole piece walking direction is shown by the arrow, and the die-cutting system includes a roller 60, a first sensor 80, a second sensor 81, a controller, a laser 51, an encoder 61, an image collector 63 and an encoding roller 62 corresponding to the encoder 61. The first sensor 80 and the second sensor 81 are arranged on both sides of the pole piece in a counter-projection form, and the data acquisition direction of the first sensor 80 and the second sensor 81 is perpendicular to the pole piece.

[0109] In this embodiment, a first sensor and a second sensor are respectively arranged on both sides of the pole piece. The first sensor and the second sensor collect the pole piece thickness data of the pole piece in a counter-radiation manner, thereby improving the accuracy of the pole piece thickness data.

[0110] In some embodiments, the image collector includes a first image collector, a second image collector, a third image collector and a fourth image collector; the first image collector is used to detect front defects of the die-cutting pole piece; the second image collector is used to detect backlight defects of the die-cutting pole piece; the third image collector and the fourth image collector are used to detect back defects of the die-cutting pole piece.

[0111] In order to improve the comprehensiveness and accuracy of pole piece defect detection, in this embodiment, multiple image collectors can be set at multiple positions to detect pole piece defects.

[0112] For ease of understanding, refer to Fig. 9 This invention is provided for illustration, but is not intended to limit the present application. Fig. 9 The following is a schematic diagram of the tape transport of the die-cutting system of some embodiments of the present invention, as an example: Fig. 9 In the figure, the pole piece tape running direction is shown by the arrow in the figure, and the die-cutting system includes a roller 60, a first sensor 80, a second sensor 81, a controller, a laser 51, an encoder 61, an encoding roller 62 corresponding to the encoder 61, a first image collector 91, a second image collector 92, a third image collector 93 and a fourth image collector 94, wherein the first image collector 91 can be used to detect defects on the front side of the pole piece, such as metal leakage, pole piece wrinkles, straight edge damage, and measure the size of the film area, etc. The second image collector 92 can be a backlight camera, which can detect pole piece damage, pole ear excess, straight edge excess, etc. through backlighting. The third image collector 93 and the fourth image collector 94 detect defects on the back side of the pole piece, and the detection items can be the same as those of the first image collector 91. Of course, in this embodiment, the die-cutting system may also include a first marking machine 95 and a second marking machine 96, and the first marking machine 95 and the second marking machine 96 are used to mark the pole piece. For example, if a gap tail is detected in the pole piece, it is necessary to mark the defect on the pole piece through the first marking machine 95 and / or the second marking machine 96.

[0113] In this embodiment, multiple image collectors are arranged at multiple positions to detect defects of the pole piece, thereby being able to improve the comprehensiveness and accuracy of the pole piece defect detection.

[0114] In some embodiments, the first image collector includes a first camera and a first light source, and the first camera and the first light source are arranged on the same side of the pole piece; the second image collector includes a second camera and a second light source, and the second camera and the second light source are respectively arranged on both sides of the pole piece; the third image collector includes a third camera and a third light source, and the third camera and the third light source are arranged on the same side of the pole piece; the fourth image collector includes a fourth camera and a fourth light source, and the fourth camera and the fourth light source are arranged on the same side of the pole piece.

[0115] In order to improve the image acquisition effect of the image collector, in this embodiment, the first image collector, the third image collector and the fourth image collector use coaxial light, that is, the camera and the light source are arranged on the same side of the pole piece, perpendicular to the pole piece, and the shooting point is located 3mm from the tangent point of the pole piece. The second image collector uses backlighting, that is, the camera and the light source are respectively arranged on both sides of the pole piece, perpendicular to the pole piece.

[0116] In some embodiments, the controller is also used to obtain the inflection point coordinates of the thickness thinning zone and the starting point coordinates of each pole piece strip, wherein the pole piece strip is a strip corresponding to a pole piece with a length of a battery cell; the length of the thickness thinning zone is calculated according to the inflection point coordinates of the thickness thinning zone, and the length of each pole piece strip is calculated according to the starting point coordinates of each pole piece strip.

[0117] In order to accurately calculate the length of the thickness thinning zone and the length of each pole piece strip, in this embodiment, the length of the thickness thinning zone is calculated according to the inflection point coordinates of the thickness thinning zone, and the length of each pole piece strip is calculated according to the starting point coordinates of each pole piece strip.

[0118] For ease of understanding, refer to Fig.10 This invention is provided for illustration, but is not intended to limit the present application. Fig.10 This is a schematic diagram of the thickness of the thickness thinning zone of some embodiments of the present invention. As an example, after obtaining the horizontal coordinates of the four points A, B, C, and D, the lengths of the three regions AB, BC, and CD can be directly calculated based on the horizontal coordinates of the four points A, B, C, and D, and then the length of the thickness thinning zone can be calculated based on the lengths of the three regions AB, BC, and CD; similarly, the length of each pole piece strip can be calculated based on the coordinates of the starting point of each pole piece strip.

[0119] This embodiment calculates the length of the thickness thinning zone according to the inflection point coordinates of the thickness thinning zone, and calculates the length of each pole piece strip according to the starting point coordinates of each pole piece strip, thereby accurately calculating the length of the thickness thinning zone and the length of each pole piece strip.

[0120] In some embodiments, the die-cutting system further includes: a calibration ruler, which is arranged on the encoding roller; the calibration ruler is driven to rotate by the rotation of the encoding roller, and the rotation of the encoding roller drives the encoder to trigger a calibration pulse; the image collector is also used to collect a calibration image of the calibration ruler in response to the calibration pulse, and send the calibration image to the controller; the controller is also used to obtain the calibration ruler parameters of the calibration ruler, calculate the calibration accuracy according to the calibration image and the calibration ruler parameters, wherein the calibration accuracy is used to represent the mapping relationship between pixel distance and actual distance; the length of the thickness thinning zone is calculated according to the calibration accuracy and the inflection point coordinates of the thickness thinning zone, and the length of each pole piece strip is calculated according to the calibration accuracy and the starting point coordinates of each pole piece strip.

[0121] In order to further improve the accuracy of the length of the thickness thinning zone and the length of each pole piece strip, in this embodiment, the target calibration accuracy can be determined first, and then the length of the coating gap zone can be calculated based on the target calibration accuracy and the inflection point coordinates of the coating gap zone, and the length of each pole piece strip can be calculated based on the target calibration accuracy and the starting point coordinates of each pole piece strip.

[0122] In the specific implementation, the sensor can be calibrated indirectly by calibrating the image collector. For ease of understanding, refer to Fig.11 and Fig.12 This invention is provided for illustration, but is not intended to limit the present application. Fig.11 Schematic diagram of a calibration ruler in some embodiments of the present invention. Fig.12 This is a schematic diagram of a calibration image in some embodiments of the present invention. The calibration method in this embodiment requires the use of Fig.11 The film ruler shown in the figure is made of non-transparent soft film with a white background, and the pattern consists of 15mm black and white rectangles. The calibration method is to use an encoder to trigger an image collector (such as a camera) to collect pictures of the film ruler, and then use the collected pictures, such as Fig.11 As shown, the vertical resolution of the image is calculated, and then the pulse accuracy of the encoder is obtained, and then the target calibration accuracy of the sensor (such as the spectral confocal displacement sensor) in the tape direction is calculated. The specific steps are as follows: 1. The encoder triggers the image acquisition on the black and white interval calibration roller.

[0123] 2. The camera captures S complete black and white grids, and the algorithm measures the number of rows K occupied by the S black and white grids.

[0124] 3. The first calibration accuracy of the camera in the tape transport direction is P1=S*15 / K.

[0125] 4. The second calibration accuracy of the encoder in the tape running direction is P2 = P / camera frequency division coefficient.

[0126] 5. The target calibration accuracy of the spectral confocal position in the direction of the tape is P3=P2*point spectrum sub-frequency coefficient.

[0127] This embodiment calibrates the image collector and indirectly calibrates the sensor, thereby determining the target calibration accuracy and improving the accuracy of subsequent calculations of the length of the thickness thinning area and the length of each pole piece strip.

[0128] In some embodiments, the sensor is a spectral confocal displacement sensor, which includes: a point light source, a dispersive confocal probe, a spectroscopic component and a detector; the point light source is used to emit detection light to the pole piece, and the detection light forms detection light of different wavelengths after passing through the dispersive confocal probe, wherein when the detection light of different wavelengths is irradiated onto the pole piece, the return light of the pole piece is connected to the detector through the spectroscopic component, and the spectroscopic component is used to block the light of unfocused wavelength in the return light; the detector is used to obtain the wavelength of the return light, and search the pole piece thickness data corresponding to the wavelength of the light in a preset wavelength relationship table, wherein the preset wavelength relationship table includes the correspondence between the light wavelength and the pole piece thickness data; the pole piece thickness data is sent to the controller.

[0129] For ease of understanding, the following examples are given, but the present application is not limited. As an example, it is assumed that the instrument used for thickness measurement is a spectral confocal displacement sensor, and its measurement principle is: a white point light source forms a conical dispersion light source after passing through a dispersive confocal probe, and the dispersion angles of light of different wavelengths are different, and light of different wavelengths are confocal at different points. When the light source is irradiated onto objects of different heights, the light spot on the object passes through the coaxial optical path and then returns through a pinhole aperture and is connected to the spectrometer, while the light of the unfocused wavelength is blocked and attenuated by the aperture (i.e., the spectroscopic component) after returning, and the wavelength of the light received by the spectrometer (i.e., the detector) can reflect the height information of the object. When the distance to the target changes, the wavelength of the focused light will also change, resulting in different spectral distributions in the spectrometer. Compared with point laser thickness measurement, the spectral confocal displacement sensor is small in size, has a small measurement blind area, and has strong anti-interference ability.

[0130] For ease of understanding, refer to Fig.13 This invention is provided for illustration, but is not intended to limit the present application. Fig.13 This is a schematic diagram of thickness measurement using a spectral confocal displacement sensor according to some embodiments of the present invention. Fig.13 In the measurement steps: 1. Adjust the first spectral confocal displacement sensor 101 and the second spectral confocal displacement sensor 102 to be confocal.

[0131] 2. Calibration is performed using a calibration sheet 100 with a thickness of 0.5 mm, the purpose of which is to determine the distance H between the first spectral confocal displacement sensor 101 and the second spectral confocal displacement sensor 102 .

[0132] 3. Calculate the thickness of the object to be measured according to the following formula: h=HAB Wherein, H represents the distance between the first spectral confocal displacement sensor 101 and the second spectral confocal displacement sensor 102, A represents the distance from the upper sensor to the object to be measured, B represents the distance from the lower sensor to the object to be measured, and h represents the thickness of the object to be measured.

[0133] In this embodiment, the sensor is configured as a spectral confocal displacement sensor, thereby reducing the volume of the sensor, reducing the measurement blind area, and improving the anti-interference capability.

[0134] In some embodiments, Fig.14 As shown, a die cutting method is proposed, comprising: Step S10: collecting the pole piece thickness data of the pole piece.

[0135] Step S20: determining the starting point of the thickness thinning zone according to the change of the pole piece thickness data, calculating a first distance from the starting point of the thickness thinning zone to the pole piece die-cutting position, and calculating the die-cutting waiting time according to the first distance.

[0136] Step S30: after the die-cutting waiting time, die-cut the pole piece at the pole piece die-cutting position to obtain a first pole lug.

[0137] In this embodiment, the die-cutting method can be applied to a die-cutting system, and the die-cutting system includes a sensor, a controller, and a laser. In order to make the gap coating area at the corner of the battery cell winding, it is necessary to accurately cut the first pole ear at the designed spacing before the thickness thinning area in the die-cutting process. Therefore, it is necessary to accurately identify the position of the thickness thinning area in the die-cutting process, and guide the laser to cut the first pole ear according to the position of the thickness thinning area. In order to accurately identify the position of the thickness thinning area in the die-cutting process, in this embodiment, the pole piece thickness data of the pole piece is collected by a sensor, and the starting point of the thickness thinning area is determined according to the change of the pole piece thickness data. In order to accurately cut the first pole ear at the designed spacing before the thickness thinning area, in this embodiment, the first distance from the starting point of the thickness thinning area to the laser is first calculated, the die-cutting waiting time is calculated according to the first distance, and the laser is controlled. After the die-cutting waiting time, the pole piece is die-cut to obtain the first pole ear.

[0138] For ease of understanding, refer to Figure 5This invention is provided for illustration, but is not intended to limit the present application. Figure 5 Schematic diagram of die-cutting system in some embodiments of the present invention, as an example, Figure 5 In the figure, it is assumed that the design spacing between the starting point of the thickness thinning area and the midpoint of the first pole ear is L, and the pole piece running direction is shown by the arrow in the figure. Figure 5 In the die-cutting system, a sensor 50, a controller and a laser 51 are included. When the pole piece is conveyed, the sensor 50 collects the pole piece thickness data of the pole piece by emitting a detection light, and sends the pole piece thickness data to the controller. The sensor 50 may be a point laser thickness gauge or a spectral confocal displacement sensor, which is not limited in this embodiment. After receiving the pole piece thickness data, the controller determines the starting point of the thickness thinning zone by analyzing the change of the pole piece thickness data (for example, the first drop point when the pole piece thickness data drops continuously can be determined as the starting point of the thickness thinning zone). After determining the starting point of the thickness thinning zone, the first distance L1 from the starting point of the thickness thinning zone to the laser 51 is obtained. After obtaining the first distance L1 from the starting point of the thickness thinning zone to the laser 51, the die-cutting waiting time T of the laser 51 can be calculated according to the pole piece's tape running speed V (assuming that the pole piece is tape-running at a uniform speed) and the designed spacing L between the starting point of the thickness thinning zone and the midpoint of the first pole ear. The specific calculation formula is T=(L1-L) / V. After obtaining the die-cutting waiting time T, the controller sends the die-cutting waiting time T to the laser 51. After the die-cutting waiting time, the laser 51 die-cuts the pole ear area 20 of the pole piece to obtain the first pole ear 40.

[0139] This embodiment determines the starting point of the thickness thinning zone by measuring the change in the electrode thickness data, and guides the laser to cut the first pole ear according to the starting point of the thickness thinning zone, so that the position of the thickness thinning zone can be accurately identified in the die-cutting process, and then the first pole ear can be accurately cut at the designed spacing before the thickness thinning zone in the die-cutting process, so that the thickness thinning zone is at the corner of the battery cell winding.

[0140] In some embodiments, Fig.15 As shown, before step S10, the following steps are also included: Step S01: When the pole piece is moving, a pulse is triggered.

[0141] Accordingly, the step S10 includes: Step S10 ′: in response to the pulse, collecting the pole piece thickness data of the pole piece.

[0142] After step S30, the method further includes: Step S40: in response to the pulse, collecting an image of the die-cut pole piece, and performing defect detection on the die-cut pole piece according to the image of the die-cut pole piece.

[0143] In order to achieve consistency between the electrode tape and the electrode detection, in this embodiment, a pulse is triggered when the electrode tape is running, and in response to the pulse, the electrode thickness data of the electrode and the image of the electrode after die cutting are collected. Figure 6 This invention is provided for illustration, but is not intended to limit the present application. Figure 6 The following is a schematic diagram of the tape transport of the die-cutting system of some embodiments of the present invention, as an example: Figure 6 In the figure, it is assumed that the design spacing between the starting point of the thickness thinning area and the midpoint of the first pole ear is L, and the pole piece running direction is shown by the arrow in the figure. Figure 6 In the die-cutting system, the die-cutting system includes a roller 60, a sensor 50, a controller, a laser 51, an encoder 61, an image collector 63 and an encoding roller 62 corresponding to the encoder 61. The roller 60 drives the pole piece to move, and the pole piece movement drives the encoding roller 62 to rotate. The rotation of the encoding roller 62 drives the encoder 61 to trigger a pulse. The sensor 50 responds to the pulse, collects the pole piece thickness data of the pole piece by emitting a detection light, and sends the pole piece thickness data to the controller. After receiving the pole piece thickness data, the controller determines the starting point of the thickness thinning zone by analyzing the change of the pole piece thickness data (for example, the first drop point when the pole piece thickness data drops continuously can be determined as the starting point of the thickness thinning zone). After determining the starting point of the thickness thinning zone, the first distance L1 from the starting point of the thickness thinning zone to the laser 51 is obtained. After obtaining the first distance L1 from the starting point of the thickness thinning zone to the laser 51, the die-cutting waiting time T of the laser 51 can be calculated according to the pole piece's tape running speed V (assuming that the pole piece is tape running at a uniform speed) and the design spacing between the starting point of the thickness thinning zone and the midpoint of the first pole ear as L. The specific calculation formula is T=(L1-L) / V. After obtaining the die-cutting waiting time T, the controller sends the die-cutting waiting time T to the laser 51. After the laser 51 has an interval of the die-cutting waiting time, it performs die-cutting on the pole piece to obtain the first pole ear. The image collector 63 collects the image of the pole piece after die-cutting in response to the pulse, and sends the image of the pole piece after die-cutting to the controller. The image collector 63 may be a camera, and the image collector 63 may be set at multiple locations to detect multiple defects, for example, to detect conventional defects such as metal leakage, tab excess material, straight edge excess material, etc. Of course, the image collector 63 may also be set near the laser 51 to detect whether the actual distance between the starting point of the thickness thinning area and the midpoint of the first tab is equal to the designed distance between the starting point of the thickness thinning area and the midpoint of the first tab. The specific setting method may be as follows: Figure 7 After receiving the image of the die-cut rear electrode sheet, the controller performs defect detection on the die-cut rear electrode sheet according to the image of the die-cut rear electrode sheet.

[0144] This embodiment triggers a pulse when the pole piece is being walked, and in response to the pulse, collects the pole piece thickness data of the pole piece and the image of the pole piece after die-cutting, thereby achieving consistency between the pole piece walking and the pole piece detection, and further improving the accuracy of the pole piece detection.

[0145] In some embodiments, the die-cutting waiting time is the number of die-cutting waiting pulses; Fig.16 As shown, the step S20 includes: Step S201: determining the starting point of the thickness thinning zone according to the change of the pole piece thickness data, and calculating the first distance from the starting point of the thickness thinning zone to the pole piece die-cutting position.

[0146] Step S202: Acquire the pulse accuracy of the pulse.

[0147] Step S203: Calculate the number of die-cutting waiting pulses according to the pulse accuracy and the first distance.

[0148] Accordingly, the step S30 includes: Step S30': after the die-cutting waiting pulse number, die-cut the pole piece at the pole piece die-cutting position to obtain a first pole lug.

[0149] Considering that the pole piece is not moving at a uniform speed in some cases, if the laser is still controlled to die-cut the first pole ear according to the die-cutting waiting time, the position of the first pole ear may be inaccurate. Therefore, in this embodiment, the number of die-cutting waiting pulses is calculated according to the encoder accuracy, and after the number of die-cutting waiting pulses is spaced, the laser is controlled to die-cut the pole piece to obtain the first pole ear.

[0150] For ease of understanding, the following examples are given, but are not intended to limit the present application. As an example, assuming that the design distance between the starting point of the thickness reduction zone and the midpoint of the first tab is L, the main working steps of the gap die cutting detection system include: 1. Collect the pole piece thickness data of the pole piece.

[0151] 2. Determine the starting point of the thickness thinning area based on the change in the electrode thickness data.

[0152] 3. Calculate the first distance L1 from the starting point of the thickness thinning area to the laser.

[0153] 4. According to the first distance L1 from the starting point of the thickness thinning zone to the laser, the design spacing L between the starting point of the thickness thinning zone and the midpoint of the first pole ear, and the encoder accuracy P, the die-cutting waiting pulse number X=(L1-L) / P is calculated. The laser starts cutting the first pole ear after waiting for X pulses, where the encoder accuracy P represents the number of pulses generated per encoder rotation.

[0154] 5. The camera takes pictures of the pole piece after laser die-cutting. In addition to calculating the conventional pole piece defects and dimensions, it can also detect whether the actual distance between the starting point of the thickness thinning area and the midpoint of the first pole ear is equal to the designed distance between the starting point of the thickness thinning area and the midpoint of the first pole ear.

[0155] This embodiment calculates the number of waiting pulses for die-cutting according to the pulse accuracy, and after the number of waiting pulses for die-cutting is calculated, the pole piece is die-cut to obtain the first pole ear, thereby reducing the influence of the pole piece tape speed on the die-cutting of the first pole ear, and further improving the accuracy of die-cutting the first pole ear.

[0156] In some embodiments, after the die-cutting waiting time, the pole piece is die-cut at the pole piece die-cutting position to obtain the first pole ear, and it also includes: obtaining the die-cutting error of the first pole ear based on the image of the pole piece after die-cutting; if the die-cutting error is not within a preset error range, generating an error correction instruction based on the die-cutting error; after the die-cutting waiting time, the pole piece is die-cut at the pole piece die-cutting position according to the error correction instruction to obtain the next first pole ear.

[0157] In order to make timely error corrections in the process of laser die-cutting the first pole ear, in this embodiment, the actual distance between the starting point of the thickness thinning area and the midpoint of the first pole ear is obtained through the image of the pole piece after die-cutting, and the design distance between the starting point of the thickness thinning area and the midpoint of the first pole ear is obtained. The laser is controlled according to whether the die-cutting error between the actual distance and the design distance is within a preset error range, thereby forming a complete closed-loop detection system.

[0158] For ease of understanding, the following examples are given, but are not intended to limit the present application. As an example, assuming that the design distance between the starting point of the thickness reduction zone and the midpoint of the first tab is L, the main working steps of the gap die cutting detection system include: 1. Collect the pole piece thickness data of the pole piece.

[0159] 2. Determine the starting point of the thickness thinning area based on the change in the electrode thickness data.

[0160] 3. Calculate the first distance L1 from the starting point of the thickness thinning area to the laser.

[0161] 4. According to the first distance L1 from the starting point of the thickness thinning zone to the laser, the design spacing L between the starting point of the thickness thinning zone and the midpoint of the first pole ear, and the encoder accuracy P, the die-cutting waiting pulse number X=(L1-L) / P is calculated. The laser starts cutting the first pole ear after waiting for X pulses, where the encoder accuracy P represents the number of pulses generated per encoder rotation.

[0162] 5. The camera takes pictures of the pole piece after laser die-cutting. In addition to calculating the conventional pole piece defects and dimensions, it can also detect whether the actual distance between the starting point of the thickness thinning area and the midpoint of the first pole ear is equal to the designed distance between the starting point of the thickness thinning area and the midpoint of the first pole ear.

[0163] 6. Obtain the designed spacing between the starting point of the thickness thinning zone and the midpoint of the first pole ear, and calculate the spacing error between the actual spacing and the designed spacing; if the spacing error is within the preset error range, return to step 1 and continue to die-cut the next first pole ear, wherein the preset error range may be an error range pre-set according to specification requirements, which is not limited in this embodiment.

[0164] 7. If the spacing error is not within the preset error range, closed-loop control is performed with the laser. Specifically, the controller generates an error correction instruction based on the spacing error and sends the error correction instruction to the laser; after the laser waits for X pulses, it die-cuts the pole piece according to the error correction instruction to obtain the next first pole ear.

[0165] This embodiment obtains the die-cutting error of the first pole ear through the image of the pole piece after die-cutting. If the die-cutting error is not within the preset error range, an error correction instruction is generated according to the die-cutting error to control the laser, thereby forming a complete closed-loop detection system, and then timely error correction can be performed on the process of laser die-cutting the first pole ear, thereby improving the reliability of the die-cutting system.

[0166] In some embodiments, the calculation of the first distance from the starting point of the thickness thinning zone to the pole piece die-cutting position includes: obtaining the second distance between the collection position of the pole piece thickness data and the pole piece die-cutting position; obtaining the tape running distance of the pole piece when collecting the pole piece thickness data; and calculating the first distance from the starting point of the thickness thinning zone to the pole piece die-cutting position based on the second distance and the tape running distance.

[0167] In order to improve the accuracy of the first distance, in this embodiment, when calculating the first distance, the second distance from the sensor to the laser and the tape travel distance of the pole piece when the sensor collects the pole piece thickness data are also considered.

[0168] For ease of understanding, refer to Figure 6 and Figure 7 For illustration, but not limitation of the present application, as an example, it is assumed that the design spacing between the starting point of the thickness thinning zone and the midpoint of the first pole ear is L, and the pole piece tape running direction is shown by the arrow in the figure. The die-cutting system includes a roller 60, a sensor 50, a controller, a laser 51, an encoder 61, an image collector 63 and an encoding roller 62 corresponding to the encoder 61. The main working steps of the gap die-cutting detection system include: 1. The roller 60 drives the pole piece to move, and the pole piece moves the encoding roller 62 to rotate. The rotation of the encoding roller 62 drives the encoder 61 to trigger the pulse. After receiving the pulse trigger, the sensor 50 collects the pole piece thickness data at this time, and 5000 data are a group (can be pre-set).

[0169] 2. For the collected data, first preliminarily determine whether the data is an inflection point. The judgment logic is to compare the collected data with the preset data. The preset data is the thickness of the electrode in the thickness thinning area plus the thickness of the electrode in the non-thickness thinning area, divided by 2. If the collected data is less than the preset value, and the subsequent 500 points (settable) continue to be less than the value, then the point is a downward mutation point; similarly, if the collected data is greater than the preset value, and the subsequent 500 points (settable) continue to be greater than the value, then the point is an upward mutation point.

[0170] 3. According to the location of the mutation point found, smooth the 500 data before and after the mutation point, and then calculate the derivative to find the inflection point of the thickness thinning area.

[0171] 4. Assuming that the first inflection point of the thickness reduction zone (i.e., the starting point of the thickness reduction zone) is at the Mth point in the Nth array, after the N+1th data collection is completed, the first distance L1 from the starting point of the thickness reduction zone to the laser 51 is calculated by the following formula: L1=L2-(2*5000-M)*P*m / d In the formula, L1 represents the distance from the starting point of the thickness thinning zone to the laser 51, L2 represents the distance between the sensor 50 and the laser 51, (2*5000-M)*P*m / d represents the walking distance of the pole piece when the sensor collects the pole piece thickness data, (2*5000-M) represents the number of interval data points between the starting point of the thickness thinning zone and the end point of this data collection, P represents the accuracy of the encoder 61, m represents the frequency division of the sensor 50, and d represents the frequency division of the sensor 50.

[0172] 5. According to the first distance L1 from the starting point of the thickness thinning zone to the laser 51, the designed spacing L between the starting point of the thickness thinning zone and the midpoint of the first pole ear, and the accuracy P of the encoder 61, the die-cutting waiting pulse number X=(L1-L) / P is calculated. The laser 51 starts cutting the first pole ear after waiting for X pulses.

[0173] 6. The image collector 63 collects pictures of the gap electrode and the pole ear, and calculates the position from the first inflection point of the thickness thinning area to the pole ear based on the pictures, finds the outline of the pole ear based on the threshold, and then calculates the center position of the pole ear, and then calculates the position of the edge of the thickness thinning area based on the pictures, and then calculates the actual distance between the starting point of the thickness thinning area and the midpoint of the first pole ear.

[0174] 7. Obtain the designed spacing between the starting point of the thickness thinning zone and the midpoint of the first pole ear, calculate the spacing error between the actual spacing and the designed spacing, and if the spacing error is not within the preset error range, generate an error correction instruction based on the spacing error and the actual process requirements, and send the error correction instruction to the laser 51. The laser 51 then die-cuts the next first pole ear, and according to the error correction instruction, compensates for the distance of the pole ear cut by the laser 51.

[0175] When calculating the first distance, this embodiment also considers the second distance from the sensor to the laser and the pole piece walking distance when the sensor collects pole piece thickness data, thereby improving the accuracy of the first distance calculation and further improving the accuracy of the first pole ear die cutting.

[0176] In some embodiments, the defect detection of the die-cut pole sheet based on the image of the die-cut pole sheet includes: acquiring frequency characteristics of the image of the die-cut pole sheet, and removing noise from the image of the die-cut pole sheet based on the frequency characteristics to obtain a processed image; acquiring an edge texture image of the die-cut pole sheet based on the image of the die-cut pole sheet and the processed image; and defect detection of the die-cut pole sheet based on the edge texture image.

[0177] In this embodiment, the appearance of the gap electrode is also inspected. Since the traditional lighting scheme cannot effectively identify the tailing defect of the gap coating, a lighting scheme for the gap tailing defect is designed in this embodiment. Specifically, it can be as follows: Fig.17 As shown, Fig.17 The three-view diagram of the image collector of some embodiments of the present invention, the image collector may include a camera 160 and a lighting device 161, the camera 160 is set on one side of the pole piece, and the lighting device 161 is set on the other side of the pole piece, the position of the camera 160 corresponds to the position of the lighting device 161, wherein the camera 160 is set as follows: 1. Standing facing the incoming direction; 2. The camera field of view is 300mm; 3. The working distance is 245mm. The lighting device 161 is set as follows: the working distance is 40mm.

[0178] Considering that the tail is close to the background grayscale value, there is no effective method to detect it in the spatial domain (grayscale value). Therefore, in this embodiment, the frequency characteristics of the image of the die-cutting pole piece are first obtained, and then the image of the die-cutting pole piece is subjected to noise removal according to the frequency characteristics to obtain a processed image, and then the edge texture image of the die-cutting pole piece is obtained according to the image of the die-cutting pole piece and the processed image, and the defect detection of the die-cutting pole piece is performed according to the edge texture image.

[0179] For ease of understanding, the following examples are given, but are not intended to limit the present application. As an example, gap coating tailing detection includes: 1. Collect pictures: Collect images of the electrode after die-cutting.

[0180] 2. Convert the image from the spatial domain to the frequency domain: The spatial domain is the representation of an image on a two-dimensional plane, while the frequency domain is the representation of an image in terms of frequency. Converting an image from the spatial domain to the frequency domain means converting the image from a pixel representation in space to a spectrum representation in frequency through Fourier transform. In a specific implementation, a two-dimensional discrete Fourier transform (DFT) or a fast Fourier transform (FFT) can be used to achieve this conversion. The frequency domain representation helps analyze the frequency characteristics of an image, such as high-frequency noise and low-frequency texture. For example, in image processing software, an FFT algorithm can be used to convert a grayscale image from the spatial domain to the frequency domain to obtain its spectrum diagram.

[0181] 3. Create a low-pass (such as Gaussian) filter: The tail that needs to be detected appears as texture and contour in the spatial domain, and as a low-frequency feature in the frequency domain. Therefore, low-pass filtering is required. A low-pass filter is a filter that allows low-frequency signals to pass through while attenuating high-frequency signals. A Gaussian filter is a filter with a Gaussian function shape, whose frequency response is highest at the center frequency and gradually decreases as the frequency increases. In the specific implementation, when creating a Gaussian filter, it is necessary to set the parameters of the filter, such as the cutoff frequency, standard deviation, etc., and then generate a filter function with a Gaussian shape. Gaussian filters can effectively smooth images and remove high-frequency noise. For example, in image processing software, a Gaussian filter with a standard deviation of σ can be set and then applied to the image to smooth the noise.

[0182] 4. Multiply the frequency domain image by the filter: This step is to multiply the image in the frequency domain with the filter function point by point to change the frequency characteristics of the image. In the frequency domain, both the image and the filter are two-dimensional matrices, and point-by-point multiplication is the multiplication of corresponding elements. Through the product operation, certain frequency components in the image can be suppressed or enhanced. For example, multiplying a Gaussian filter with a frequency domain image can suppress high-frequency noise and retain low-frequency texture.

[0183] 5. Convert the frequency domain image to the spatial domain: This step is to convert the filtered frequency domain image back to the spatial domain to obtain the processed image. In the specific implementation, the two-dimensional discrete inverse Fourier transform (IDFT) or the inverse fast Fourier transform (IFFT) can be used to achieve this conversion. After converting back to the spatial domain, a smoothed image can be obtained. For example, in image processing software, the IFFT algorithm can be used to convert the frequency domain image back to the spatial domain to obtain the processed image.

[0184] 6. Perform differential operation on the transformed image and the original image: Difference operation refers to calculating the pixel difference between two images. The transformed image is subtracted from the original image point by point to obtain a difference image. The difference image can highlight the changes in the image, such as edges, textures, etc. For example, the difference operation between the smoothed image and the original image can produce a difference image that highlights the edges and textures.

[0185] 7. Use the blob algorithm to filter the tail according to length, width, area size and aspect ratio Blob (Binary Large OBject) algorithm is an algorithm used in image processing and computer vision to detect and analyze connected regions in images. Smear usually refers to the long strips in the image that have a significant difference in brightness or color from the surrounding area. Using the Blob algorithm to detect connected regions in the image and filter them based on their length, width, area size, and aspect ratio, the smear in the image can be accurately detected. For example, in machine vision applications, the Blob algorithm can be used to detect scratches or linear defects in the image and filter and classify them based on their length, width, and other features.

[0186] 8. Use the minimum circumscribed rectangle to fit and output the length and width of the tail: Minimum bounding rectangle fitting refers to finding a minimum rectangular area that can completely contain a connected area (such as a tail) in the image. By calculating the bounding rectangle of the connected area and finding its minimum size, the minimum bounding rectangle can be obtained, and then the length and width of the rectangle are output as the size of the tail, so that the length and width of the tail can be accurately measured. For example, in image processing software, the minimum bounding rectangle fitting algorithm can be used to measure the length and width of scratches or linear defects in an image.

[0187] This embodiment first obtains the frequency characteristics of the image of the pole piece after die-cutting, and then removes noise from the image of the pole piece after die-cutting according to the frequency characteristics to obtain a processed image, and then obtains an edge texture image of the pole piece after die-cutting according to the image of the pole piece after die-cutting and the processed image, and performs defect detection on the pole piece after die-cutting according to the edge texture image, thereby improving the accuracy of gap coating tailing detection.

[0188] In some embodiments, determining the starting point of the thickness thinning zone according to the change of the pole piece thickness data includes: constructing an objective function according to the pole piece thickness data, wherein the objective function is used to represent the thickness change of the pole piece; determining the inflection point of the thickness thinning zone according to the objective function; and determining the starting point of the thickness thinning zone according to the inflection point of the thickness thinning zone and the tape running direction of the pole piece.

[0189] In order to improve the accuracy of the starting point of the thickness thinning zone, in this embodiment, the pole piece thickness data is first filtered and smoothed, and then the smoothed data is fitted with a logic function to obtain a fitted logic function (i.e., the target function), and then the fitted logic function is differentiated, and the inflection point of the thickness thinning zone is determined according to the derivative of the logic function, and then the starting point of the thickness thinning zone is determined according to the inflection point of the thickness thinning zone and the tape running direction of the pole piece.

[0190] This embodiment first constructs an objective function based on the electrode thickness data, then determines the inflection point of the thickness thinning zone based on the objective function, and determines the starting point of the thickness thinning zone based on the inflection point of the thickness thinning zone and the tape running direction of the electrode, thereby improving the accuracy of the starting point of the thickness thinning zone.

[0191] In some embodiments, determining the inflection point of the thickness thinning zone according to the objective function includes: calculating an intersection point between a preset threshold and the objective function; and determining the inflection point of the thickness thinning zone according to the intersection point.

[0192] In order to accurately calculate the inflection point of the thickness reduction zone, in this embodiment, the intersection point between the preset threshold and the derivative of the logic function can be calculated, and the inflection point of the thickness reduction zone can be determined according to the intersection point. Fig.10 and Fig.18 This invention is provided for illustration, but is not intended to limit the present application. Fig.10 Schematic diagram of thickness of the thinned area in some embodiments of the present invention, Fig.10 The medium thickness thinning area includes four inflection points: A, B, C, and D. Fig.18 Schematic diagram of finding the inflection point of the thickness thinning area in some embodiments of the present invention, Fig.18 In the process of finding the inflection point of the thickness thinning zone, the steps include: 1. After processing the data measured by the sensor, the pole piece thickness data can be obtained.

[0193] 2. First filter and smooth the pole piece thickness data.

[0194] 3. Then, the logistic function is fitted to the smoothed pole piece thickness data.

[0195] 4. Derivative the fitted logistic function.

[0196] 5. Find the intersection of the threshold line and the derivative of the logistic function, such as Fig.18 shown.

[0197] 6. The horizontal coordinate of the intersection is the horizontal coordinate of the inflection point, and the two inflection points C and D on the falling edge can be found. Similarly, the two inflection points A and B on the rising edge can be found.

[0198] Assume that the pole piece's tape running direction is as follows Fig.10As shown, the turning point D is in front of the turning point A in the running direction, and the turning point D is used as the starting point of the thickness thinning area. In the specific implementation, the coordinates of point A can be used as the reference, and N points on the left of point A can be averaged to be used as the thickness of the coating area of ​​the pole piece; the midpoint of points B and C can be used as the reference, and the average of N / 2 points on the left and right of the midpoint is the thickness of the thickness thinning area of ​​the pole piece.

[0199] In this embodiment, the intersection point between the preset threshold and the derivative of the logic function is calculated, and the inflection point of the thickness thinning area is determined according to the intersection point, so that the inflection point of the thickness thinning area can be calculated.

[0200] In some embodiments, determining the inflection point of the thickness thinning zone according to the objective function includes: calculating the maximum value or the minimum value of the objective function; and determining the inflection point of the thickness thinning zone according to the maximum value or the minimum value.

[0201] In an actual working environment, due to mechanical jitter, the measured thickness fluctuates, which affects the search for the gap coating inflection point. Therefore, in order to improve the accuracy of the coating gap inflection point, in this embodiment, a measurement scheme based on the steepest descent / steepest ascent point is used, which can stably find the inflection point in a jittery environment.

[0202] For ease of understanding, refer to Fig.10 and Fig.19 This invention is provided for illustration, but is not intended to limit the present application. Fig.10 Schematic diagram of thickness of the thinned area in some embodiments of the present invention, Fig.10 The medium thickness thinning area includes four inflection points: A, B, C, and D. Fig.19 Schematic diagram of finding the inflection point of the thickness thinning area in some embodiments of the present invention, Fig.19 In the process of finding the inflection point of the thickness thinning zone, the steps include: 1. After processing the data measured by the sensor, the pole piece thickness data can be obtained.

[0203] 2. First filter and smooth the pole piece thickness data.

[0204] 3. Then, the logistic function is fitted to the smoothed pole piece thickness data.

[0205] 4. Derivative the fitted logistic function.

[0206] 5. Find the maximum value of the derivative of the logistic function, such as Fig.19 shown.

[0207] 6. The horizontal coordinate of the maximum value of the derivative is the horizontal coordinate of the center point of the inflection point, such as Fig.19In the figure, the horizontal coordinate of the maximum value of the derivative is essentially the center point of the inflection points C and D. Based on the center point, the horizontal coordinates of the inflection points C and D can be obtained. Similarly, the horizontal coordinates of the two inflection points A and B can be obtained.

[0208] Assume that the pole piece's tape running direction is as follows Fig.10 As shown, the turning point D is in front of the turning point A in the direction of the tape travel, and the turning point D is taken as the starting point of the thickness thinning area.

[0209] This embodiment determines the inflection point of the thickness thinning zone based on the measurement scheme of the steepest descent / steepest ascent point, thereby improving the accuracy of the coating gap inflection point, and further improving the calculation accuracy of the length of the thickness thinning zone and the length of each pole piece strip.

[0210] In some embodiments, after determining the inflection point of the thickness thinning zone according to the objective function, it also includes: obtaining the inflection point coordinates of the thickness thinning zone and the starting point coordinates of each pole piece strip, wherein the pole piece strip is a strip corresponding to a pole piece with a length of a battery cell; calculating the length of the thickness thinning zone according to the inflection point coordinates of the thickness thinning zone, and calculating the length of each pole piece strip according to the starting point coordinates of each pole piece strip.

[0211] In order to accurately calculate the length of the thickness thinning zone and the length of each pole piece strip, in this embodiment, the length of the thickness thinning zone is calculated according to the inflection point coordinates of the thickness thinning zone, and the length of each pole piece strip is calculated according to the starting point coordinates of each pole piece strip.

[0212] For ease of understanding, refer to Fig.10 This invention is provided for illustration, but is not intended to limit the present application. Fig.10 This is a schematic diagram of the thickness of the thickness thinning zone of some embodiments of the present invention. As an example, after obtaining the horizontal coordinates of the four points A, B, C, and D, the lengths of the three regions AB, BC, and CD can be directly calculated based on the horizontal coordinates of the four points A, B, C, and D, and then the length of the thickness thinning zone can be calculated based on the lengths of the three regions AB, BC, and CD; similarly, the length of each pole piece strip can be calculated based on the coordinates of the starting point of each pole piece strip.

[0213] This embodiment calculates the length of the thickness thinning zone according to the inflection point coordinates of the thickness thinning zone, and calculates the length of each pole piece strip according to the starting point coordinates of each pole piece strip, thereby accurately calculating the length of the thickness thinning zone and the length of each pole piece strip.

[0214] In some embodiments, before calculating the length of the thickness thinning zone according to the inflection point coordinates of the thickness thinning zone, and calculating the length of each pole sheet strip according to the starting point coordinates of each pole sheet strip, it also includes: acquiring a calibration image of a calibration ruler, and obtaining the calibration ruler parameters of the calibration ruler; calculating the calibration accuracy according to the calibration image and the calibration ruler parameters, wherein the calibration accuracy is used to represent the mapping relationship between pixel distance and actual distance; accordingly, calculating the length of the thickness thinning zone according to the inflection point coordinates of the thickness thinning zone, and calculating the length of each pole sheet strip according to the starting point coordinates of each pole sheet strip, includes: calculating the length of the thickness thinning zone according to the calibration accuracy and the inflection point coordinates of the thickness thinning zone, and calculating the length of each pole sheet strip according to the calibration accuracy and the starting point coordinates of each pole sheet strip.

[0215] In order to further improve the accuracy of the length of the thickness thinning zone and the length of each pole piece strip, in this embodiment, the target calibration accuracy can be determined first, and then the length of the coating gap zone can be calculated based on the target calibration accuracy and the inflection point coordinates of the coating gap zone, and the length of each pole piece strip can be calculated based on the target calibration accuracy and the starting point coordinates of each pole piece strip.

[0216] In the specific implementation, the sensor can be calibrated indirectly by calibrating the image collector. For ease of understanding, refer to Fig.11 and Fig.12 This invention is provided for illustration, but is not intended to limit the present application. Fig.11 Schematic diagram of a calibration ruler in some embodiments of the present invention. Fig.12 This is a schematic diagram of a calibration image in some embodiments of the present invention. The calibration method in this embodiment requires the use of Fig.11 The film ruler shown in the figure is made of non-transparent soft film with a white background, and the pattern consists of 15mm black and white rectangles. The calibration method is to use an encoder to trigger an image collector (such as a camera) to collect pictures of the film ruler, and then use the collected pictures, such as Fig.11 As shown, the vertical resolution of the image is calculated, and then the pulse accuracy of the encoder is obtained, and then the target calibration accuracy of the sensor (such as the spectral confocal displacement sensor) in the tape direction is calculated. The specific steps are as follows: 1. The encoder triggers the image acquisition on the black and white interval calibration roller.

[0217] 2. The camera captures S complete black and white grids, and the algorithm measures the number of rows K occupied by the S black and white grids.

[0218] 3. The first calibration accuracy of the camera in the tape transport direction is P1=S*15 / K.

[0219] 4. The second calibration accuracy of the encoder in the tape running direction is P2 = P / camera frequency division coefficient.

[0220] 5. The target calibration accuracy of the spectral confocal position in the direction of the tape is P3=P2*point spectrum sub-frequency coefficient.

[0221] This embodiment calibrates the image collector and indirectly calibrates the sensor, thereby determining the target calibration accuracy and improving the accuracy of subsequent calculations of the length of the thickness thinning area and the length of each pole piece strip.

[0222] In some embodiments, the collecting of the pole piece thickness data of the pole piece includes: emitting detection light of different wavelengths to the pole piece, wherein when the detection light of different wavelengths is irradiated onto the pole piece, light of unfocused wavelengths in the return light of the pole piece is blocked; receiving the return light of the pole piece, and obtaining the wavelength of the return light, and searching for the pole piece thickness data corresponding to the wavelength of the light in a preset wavelength relationship table, wherein the preset wavelength relationship table includes the correspondence between the wavelength of light and the pole piece thickness data.

[0223] For ease of understanding, the following examples are given, but the present application is not limited. As an example, it is assumed that the instrument used for thickness measurement is a spectral confocal displacement sensor, and its measurement principle is: a white point light source forms a conical dispersion light source after passing through a dispersive confocal probe, and the dispersion angles of light of different wavelengths are different, and light of different wavelengths are confocal at different points. When the light source is irradiated onto objects of different heights, the light spot on the object passes through the coaxial optical path and then returns through a pinhole aperture and is connected to the spectrometer, while the light of the unfocused wavelength is blocked and attenuated by the aperture (i.e., the spectroscopic component) after returning, and the wavelength of the light received by the spectrometer (i.e., the detector) can reflect the height information of the object. When the distance to the target changes, the wavelength of the focused light will also change, resulting in different spectral distributions in the spectrometer. Compared with point laser thickness measurement, the spectral confocal displacement sensor is small in size, has a small measurement blind area, and has strong anti-interference ability.

[0224] For ease of understanding, refer to Fig.13 This invention is provided for illustration, but is not intended to limit the present application. Fig.13 This is a schematic diagram of thickness measurement using a spectral confocal displacement sensor according to some embodiments of the present invention. Fig.13 In the measurement steps: 1. Adjust the first spectral confocal displacement sensor 101 and the second spectral confocal displacement sensor 102 to be confocal.

[0225] 2. Calibration is performed using a calibration sheet 100 with a thickness of 0.5 mm, the purpose of which is to determine the distance H between the first spectral confocal displacement sensor 101 and the second spectral confocal displacement sensor 102 .

[0226] 3. Calculate the thickness of the object to be measured according to the following formula: h=HAB Wherein, H represents the distance between the first spectral confocal displacement sensor 101 and the second spectral confocal displacement sensor 102, A represents the distance from the upper sensor to the object to be measured, B represents the distance from the lower sensor to the object to be measured, and h represents the thickness of the object to be measured.

[0227] This embodiment collects the pole piece thickness data by the wavelength of the light returning from the pole piece, thereby reducing the volume of the sensor, reducing the measurement blind area, and improving the anti-interference ability.

[0228] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A die-cutting system, characterized in that: The die-cutting system includes: a sensor, a controller and a laser; The sensor is used to collect the pole piece thickness data of the pole piece and send the pole piece thickness data to the controller; The controller is used to determine the starting point of the thickness thinning zone according to the change of the pole piece thickness data, calculate the first distance from the starting point of the thickness thinning zone to the laser, calculate the die-cutting waiting time according to the first distance, and send the die-cutting waiting time to the laser; The laser is used to die-cut the pole piece after the die-cutting waiting time to obtain the first pole ear.

2. The die-cutting system according to claim 1, characterized in that: The die-cutting system further includes: an encoder, an image collector, and an encoding roller corresponding to the encoder; the encoding roller is driven to rotate when the pole piece is conveyed, and the rotation of the encoding roller drives the encoder to trigger a pulse; The sensor is used to collect the pole piece thickness data of the pole piece in response to the pulse, and send the pole piece thickness data to the controller; The image collector is used to collect the image of the pole piece after die cutting in response to the pulse, and send the image of the pole piece after die cutting to the controller; The controller is used to perform defect detection on the die-cut pole piece according to the image of the die-cut pole piece.

3. The die-cutting system according to claim 2, characterized in that: The die-cutting waiting time is the number of die-cutting waiting pulses; The controller is further used to obtain the encoder accuracy of the encoder, and calculate the die-cutting waiting pulse number according to the pulse accuracy and the first distance; and send the die-cutting waiting pulse number to the laser; The laser is also used to die-cut the pole piece after the die-cutting waiting pulse number is spaced to obtain the first pole ear.

4. The die-cutting system according to claim 2, characterized in that: The controller is further configured to obtain a die-cutting error of the first pole tab according to the image of the pole piece after die-cutting; if the die-cutting error is not within a preset error range, generate an error correction instruction according to the die-cutting error; The laser is also used to die-cut the pole piece according to the error correction instruction after the die-cutting waiting time to obtain the next first pole ear.

5. The die-cutting system according to claim 2, characterized in that: The controller is also used to obtain a second distance from the sensor to the laser, and to obtain a running distance of the pole piece when the sensor collects the pole piece thickness data; and to calculate a first distance from the starting point of the thickness thinning zone to the laser based on the second distance and the running distance.

6. The die-cutting system according to claim 2, characterized in that: The sensor, the laser, the encoding roller and the image collector are arranged in sequence in the tape running direction of the pole piece, the data acquisition direction of the sensor is perpendicular to the tape running direction of the pole piece, the light outlet of the laser is perpendicular to the tape running direction of the pole piece, and the image acquisition direction of the image collector is perpendicular to the tape running direction of the pole piece.

7. The die-cutting system according to claim 6, characterized in that: The sensor comprises a first sensor and a second sensor, wherein the first sensor and the second sensor are arranged on both sides of the pole piece in a facing manner, and data acquisition directions of the first sensor and the second sensor are perpendicular to the pole piece.

8. The die-cutting system according to claim 6, characterized in that: The image collector includes a first image collector, a second image collector, a third image collector and a fourth image collector; The first image collector is used to detect the front defects of the electrode sheet after die-cutting; The second image collector is used to detect backlight defects of the die-cutting electrode sheet; The third image collector and the fourth image collector are used to detect the back surface defects of the electrode sheet after die-cutting.

9. The die-cutting system according to claim 8, characterized in that: The first image collector includes a first camera and a first light source, and the first camera and the first light source are arranged on the same side of the pole piece; the second image collector includes a second camera and a second light source, and the second camera and the second light source are respectively arranged on both sides of the pole piece; the third image collector includes a third camera and a third light source, and the third camera and the third light source are arranged on the same side of the pole piece; the fourth image collector includes a fourth camera and a fourth light source, and the fourth camera and the fourth light source are arranged on the same side of the pole piece.

10. The die-cutting system according to any one of claims 2 to 9, characterized in that: The controller is also used to obtain the inflection point coordinates of the thickness thinning zone and the starting point coordinates of each pole piece strip, wherein the pole piece strip is a strip corresponding to a pole piece with a length of a battery cell; the length of the thickness thinning zone is calculated according to the inflection point coordinates of the thickness thinning zone, and the length of each pole piece strip is calculated according to the starting point coordinates of each pole piece strip.

11. The die-cutting system according to claim 10, characterized in that: The die-cutting system further comprises: a calibration ruler, which is arranged on the encoding roller; the calibration ruler is driven to rotate by the rotation of the encoding roller, and the rotation of the encoding roller drives the encoder to trigger the calibration pulse; The image collector is further used to collect a calibration image of the calibration ruler in response to the calibration pulse, and send the calibration image to the controller; The controller is further used to obtain calibration scale parameters of the calibration scale, calculate the calibration accuracy according to the calibration image and the calibration scale parameters, wherein the calibration accuracy is used to represent the mapping relationship between pixel distance and actual distance; calculate the length of the thickness thinning area according to the calibration accuracy and the inflection point coordinates of the thickness thinning area, and calculate the length of each pole piece strip according to the calibration accuracy and the starting point coordinates of each pole piece strip.

12. The die-cutting system according to any one of claims 1 to 9, characterized in that: The sensor is a spectral confocal displacement sensor, which includes: a point light source, a dispersive confocal probe, a spectroscopic component and a detector; The point light source is used to emit detection light to the pole piece, and the detection light forms detection light of different wavelengths after passing through the dispersive confocal probe, wherein when the detection light of different wavelengths is irradiated onto the pole piece, the return light of the pole piece is connected to the detector through the light splitting component, and the light splitting component is used to shield the light of unfocused wavelength in the return light; The detector is used to obtain the wavelength of the returning light, and search for the pole piece thickness data corresponding to the wavelength of the light in a preset wavelength relationship table, wherein the preset wavelength relationship table includes the correspondence between the wavelength of the light and the pole piece thickness data; and send the pole piece thickness data to the controller.

13. A die cutting method, characterized in that: include: Collecting the pole piece thickness data of the pole piece; Determine the starting point of the thickness thinning zone according to the change of the electrode thickness data, calculate the first distance from the starting point of the thickness thinning zone to the electrode die-cutting position, and calculate the die-cutting waiting time according to the first distance; After the die-cutting waiting time, the pole piece is die-cut at the pole piece die-cutting position to obtain a first pole ear.

14. The die-cutting method according to claim 13, characterized in that: Before collecting the pole piece thickness data of the pole piece, the method further includes: When the pole piece is running, the pulse is triggered; The collecting of the pole piece thickness data of the pole piece comprises: In response to the pulse, collecting pole piece thickness data of the pole piece; After the die-cutting waiting time, the electrode piece is die-cut at the electrode piece die-cutting position to obtain the first electrode ear, and the method further includes: In response to the pulse, an image of the die-cut pole piece is collected, and defect detection is performed on the die-cut pole piece based on the image of the die-cut pole piece.

15. The die-cutting method according to claim 14, characterized in that: The die-cutting waiting time is the number of die-cutting waiting pulses; and the die-cutting waiting time is calculated according to the first distance, including: Obtaining a pulse accuracy of the pulse; Calculate the number of die-cutting waiting pulses according to the pulse accuracy and the first distance; Correspondingly, after the die-cutting waiting time, die-cutting the pole piece at the pole piece die-cutting position to obtain the first pole ear includes: After the die-cutting waiting pulse number is exceeded, the pole piece is die-cut at the pole piece die-cutting position to obtain a first pole ear.

16. The die-cutting method according to claim 14, characterized in that: After the die-cutting waiting time, the electrode piece is die-cut at the electrode piece die-cutting position to obtain the first electrode ear, and the method further includes: Acquire a die-cutting error of the first pole tab according to the image of the pole piece after die-cutting; If the die-cutting error is not within the preset error range, generating an error correction instruction according to the die-cutting error; After the die-cutting waiting time, the pole piece is die-cut at the pole piece die-cutting position according to the error correction instruction to obtain the next first pole lug.

17. The die-cutting method according to claim 14, characterized in that: The calculation of the first distance from the starting point of the thickness thinning area to the pole piece die cutting position includes: Acquire a second distance between a collection position of the pole piece thickness data and a pole piece die-cutting position; Acquiring the walking distance of the pole piece when collecting the pole piece thickness data; The first distance from the starting point of the thickness thinning zone to the pole piece die-cutting position is calculated according to the second distance and the tape running distance.

18. The die-cutting method according to claim 14, characterized in that: The defect detection of the die-cutting electrode sheet according to the image of the die-cutting electrode sheet comprises: Acquiring frequency characteristics of the image of the electrode sheet after die-cutting, and removing noise from the image of the electrode sheet after die-cutting according to the frequency characteristics to obtain a processed image; Acquire an edge texture image of the electrode sheet after die-cutting according to the image of the electrode sheet after die-cutting and the processed image; Defect detection is performed on the die-cutting rear electrode according to the edge texture image.

19. The die cutting method according to any one of claims 13 to 18, characterized in that: Determining the starting point of the thickness thinning area according to the change of the pole piece thickness data includes: Constructing an objective function according to the pole piece thickness data, wherein the objective function is used to represent the thickness change of the pole piece; Determining the inflection point of the thickness thinning zone according to the objective function; The starting point of the thickness thinning zone is determined according to the inflection point of the thickness thinning zone and the tape running direction of the pole piece.

20. The die-cutting method according to claim 19, characterized in that: Determining the inflection point of the thickness thinning zone according to the objective function includes: Calculating the intersection point between a preset threshold and the objective function; The inflection point of the thickness reduction zone is determined according to the intersection point.

21. The die cutting method according to claim 19, characterized in that: Determining the inflection point of the thickness thinning zone according to the objective function includes: Calculating the maximum or minimum value of the objective function; The inflection point of the thickness reduction zone is determined according to the maximum value or the minimum value.

22. The die cutting method according to claim 19, characterized in that: After determining the inflection point of the thickness thinning area according to the objective function, the method further includes: Obtaining the inflection point coordinates of the thickness thinning area and the starting point coordinates of each pole piece strip, wherein the pole piece strip is a strip corresponding to a pole piece of a battery cell length; The length of the thickness thinning zone is calculated according to the coordinates of the inflection point of the thickness thinning zone, and the length of each pole piece strip is calculated according to the coordinates of the starting point of each pole piece strip.

23. The die cutting method according to claim 22, characterized in that: Before calculating the length of the thickness thinning zone according to the inflection point coordinates of the thickness thinning zone and calculating the length of each pole piece strip according to the starting point coordinates of each pole piece strip, the method further includes: Acquiring a calibration image of the calibration ruler and obtaining calibration ruler parameters of the calibration ruler; Calculating a calibration accuracy according to the calibration image and the calibration ruler parameters, wherein the calibration accuracy is used to represent a mapping relationship between a pixel distance and an actual distance; Accordingly, the calculating of the length of the thickness thinning zone according to the inflection point coordinates of the thickness thinning zone, and the calculating of the length of each pole piece strip according to the starting point coordinates of each pole piece strip, comprises: The length of the thickness thinning zone is calculated according to the calibration accuracy and the coordinates of the inflection point of the thickness thinning zone, and the length of each pole piece strip is calculated according to the calibration accuracy and the coordinates of the starting point of each pole piece strip.

24. The die cutting method according to any one of claims 13 to 18, characterized in that: The collecting of the pole piece thickness data of the pole piece comprises: emitting detection light of different wavelengths to the pole piece, wherein when the detection light of different wavelengths is irradiated onto the pole piece, the light of unfocused wavelength in the return light of the pole piece is blocked; Receive the return light of the pole piece, and obtain the wavelength of the return light, and search for the pole piece thickness data corresponding to the wavelength of the light in a preset wavelength relationship table, wherein the preset wavelength relationship table includes the correspondence between the wavelength of the light and the pole piece thickness data.

Images