A lithium battery pole piece ultrafast laser step-by-step die-cutting system and die-cutting method

Abstract

The present invention discloses a lithium battery pole piece ultrafast laser step-by-step die-cutting system and a die-cutting method thereof, including a material strip analysis module, a laser trajectory module, a galvanometer focusing module, a pole piece cutting module, a heat-affected zone module, and a path evaluation module, wherein the method is as follows: S1, establishing a pole piece material strip model to generate a preset laser scanning path; S2, simulating a galvanometer to control the laser beam to scan along the preset laser scanning path, and focusing the laser beam at the optimal focal position for preliminary cutting; S3, switching the laser power and cutting speed according to the pole piece properties, cutting the pole piece to a weak connection state, and recording the first heat-affected zone; S4, performing secondary cutting of the burrs along the preliminary cutting trajectory again, recording the secondary heat-affected zone, and evaluating the preset laser scanning path; S5, after repeating steps S2-S4 to obtain the pole piece optimal cutting path, completing the cutting of the pole piece. The present invention realizes precise cutting of the pole piece material strip, significantly improving the performance and safety of the battery.

Description

Technical Field

[0001] The present invention relates to the field of laser beam processing technology, in particular to the field of laser cutting technology, and specifically to a lithium battery pole piece ultrafast laser step-by-step die-cutting system and a die-cutting method thereof. Background Art

[0002] The pole piece is a metal conductor that leads the positive and negative current collectors from the lithium battery. Pole piece forming is the process of cutting out the conductors from the positive and negative current collectors. It is generally used as a pre-process for winding or lamination, and is one of the key processes in the manufacturing process of power batteries and some consumer electronic batteries.

[0003] Pole piece die-cutting is an important process in the lithium battery production process. The current laser die-cutting technology for negative pole pieces is relatively mature. However, due to the complex material composition and thickness of lithium battery pole pieces, the mainstream cutting method is still metal die-cutting. In the actual production of metal die-cutting knives, in order to ensure processing accuracy and quality, the maintenance cycle is short and the later maintenance cost is high.

[0004] During the electrode cutting process, the quality of the electrode cutting edge has an important impact on the battery performance and quality, including: (1) burrs and impurities, which will cause short circuits in the battery, causing self-discharge or even thermal runaway; (2) poor dimensional accuracy, unable to ensure that the negative electrode completely wraps the positive electrode, or the diaphragm completely separates the positive and negative electrode sheets, causing battery safety problems; (3) thermal damage to the material, coating shedding, etc., causing the material to lose activity and be unable to function; (4) uneven cutting edges, causing uneven charging and discharging of the electrode. Therefore, the electrode cutting process needs to avoid these problems and improve process quality.

[0005] The prior art uses ultrafast lasers to attempt laser die-cutting of lithium battery pole pieces. However, there is a problem of burning on the back of the pole piece during cutting. At the same time, during the laser cutting process, the high energy of the laser beam will cause local melting or vaporization of the material strip, thereby forming a heat-affected zone, causing deformation of the edge of the material strip, resulting in unstable pole piece cutting quality, which restricts the promotion of lithium battery pole piece laser die-cutting technology in actual battery production. Summary of the invention

[0006] The present invention overcomes the shortcomings of the prior art and provides a lithium battery pole piece ultrafast laser step-by-step die-cutting system and a die-cutting method thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a lithium battery pole piece ultrafast laser step-by-step die-cutting method, comprising the following steps:

[0008] S1. Preset trajectory generation: collect the size and shape of the material strip to establish a pole piece material strip model, preset the laser beam scanning trajectory, and generate a preset laser scanning path;

[0009] S2, laser beam focusing: simulate the galvanometer to control the laser beam to scan along the preset laser scanning path, and simulate the field mirror to focus the laser beam on the pole piece strip model to form the best focal position for preliminary cutting;

[0010] S3, preliminary cutting: switch different laser powers and cutting speeds according to the different pole piece properties of the incoming material, cut the pole piece to a weak connection state, and record the first heat affected area at the preliminary cutting track;

[0011] S4, secondary cutting: simulate the laser beam to perform secondary cutting on the burrs at the initial cutting position of the pole piece again along the initial cutting trajectory, record the secondary heat affected area generated during the secondary cutting, and evaluate the preset laser scanning path in combination with the initial heat affected area;

[0012] S5. After repeating steps S2-S4 to obtain the optimal cutting path of the electrode piece, the cutting of the electrode piece is completed.

[0013] In a preferred embodiment of the present invention, in S2, the specific calculation steps of the optimal focus position are:

[0014] S21, according to Rayleigh length Where ω0 is the waist radius of the laser beam, and λ is the wavelength of the laser beam;

[0015] S22, working distance Wherein the working distance WD is the distance from the lens to the surface of the strip, f is the focal length of the focusing lens, ω0 is the waist radius of the laser beam, λ is the wavelength of the laser beam, and θ is the full angle of divergence of the laser beam;

[0016] S23, get the best focus position

[0017] In a preferred embodiment of the present invention, in S3, the specific steps of preliminary cutting are:

[0018] S31, using a galvanometer to control the laser beam to move along a preset laser scanning path, and using a focusing field lens to focus the laser beam to an optimal focus, and adjusting the laser power and cutting speed according to the properties of different material strips;

[0019] S32, start the laser emission unit, so that the laser beam cuts on the pole piece strip along a preset path, and cuts the strip to a weak connection state, that is, partially penetrated but not completely separated.

[0020] In a preferred embodiment of the present invention, in S3, the specific steps of recording the first heat affected area at the initial cutting trajectory are:

[0021] S33, using a thermal imager to perform thermal imaging scanning on the initially cut pole piece strip, and obtaining the heat accumulation area generated by the initial laser irradiation at the initial cutting track, that is, the first heat affected area, through the thermal imaging results;

[0022] S34, using a temperature sensor to monitor and record the temperature change curve corresponding to the laser irradiation point in real time to obtain temperature distribution data;

[0023] S35. Determine the area most seriously affected by heat according to the temperature change curve, that is, the first heat-affected area, and extract and record the shape data and position data of the first heat-affected area through an image recognition algorithm.

[0024] In a preferred embodiment of the present invention, in S4, the specific steps of performing secondary cutting on the burrs at the initial cutting of the pole piece are:

[0025] S41, identifying the burr position on the pole piece after preliminary cutting by a visual detection sensor, reducing the laser power and cutting speed of the laser beam according to the distribution of the burr, and simulating the laser beam to cut the pole piece again along the re-planned scanning path;

[0026] S42. After cutting, check the quality of the pole piece to ensure that the burrs have been completely removed and no new damage or increased thermal impact has been caused.

[0027] In a preferred embodiment of the present invention, in S4, the specific steps of evaluating the preset laser scanning path are:

[0028] S43, overlapping area assessment: compare the secondary heat affected area with the primary heat affected area to check whether there is an overlapping area. If there is an overlap, it means that the path setting is reasonable and the heat affected range is well controlled. If there is no overlap, repeat step S2 to optimize the laser scanning path to avoid an excessively large heat affected range.

[0029] S44, area assessment: Count the size of the secondary heat affected area to determine whether it is larger than the primary heat affected area; if it is larger, it means that the laser scanning path needs to be adjusted to reduce the secondary heat affected area; if it is smaller, it means that the laser scanning path meets the requirements;

[0030] S45, total heat impact assessment: superimpose the secondary heat affected area with the primary heat affected area to check whether the total heat affected range exceeds the allowable range; if it exceeds, the laser scanning path needs to be optimized to reduce the total heat impact; if it is within the allowable range, it indicates that the laser scanning path meets the requirements;

[0031] S46, Area Shape Assessment: Determine whether the shape of the secondary heat affected area is consistent with the first one. If not, adjust the focus or laser scanning path to optimize the shape of the heat affected area.

[0032] In a preferred embodiment of the present invention, in S1, the specific steps of collecting the size and shape of the material strip and establishing the pole piece material strip model are:

[0033] S11. Place the tape in a stable and interference-free environment to ensure that the tape does not move or deform during the scanning process;

[0034] S12, using a laser scanner to obtain size data and shape data of the material strip, the size data including the length, width, and thickness of the material strip, and the shape data including the specific contour of the edge of the material strip;

[0035] S13, input the collected size data and shape data into the STL model to create an accurate three-dimensional model of the pole piece strip.

[0036] The present invention also provides a lithium battery pole piece ultrafast laser step-by-step die-cutting system, comprising: a material strip analysis module, a laser trajectory module, a galvanometer focusing module, a pole piece cutting module, a heat-affected zone module, and a path evaluation module, characterized in that:

[0037] The strip analysis module includes: dimension measurement unit, shape scanning unit, attribute input unit and model building unit;

[0038] The laser trajectory module includes: an edge positioning unit, a focus position unit and a trajectory generation unit;

[0039] The galvanometer focusing module includes: a galvanometer parameter unit and a field lens parameter unit;

[0040] The pole piece cutting module includes: a laser power unit, a cutting speed unit, a laser emission unit and a burr recognition unit;

[0041] The heat-affected zone module includes: a zone edge recognition unit and a zone depth recording unit;

[0042] The path evaluation module includes: edge burr detection unit, heat affected area comparison unit, cutting surface smoothness detection unit and optimal path unit.

[0043] In a preferred embodiment of the present invention, the galvanometer parameter unit is used to set and control the motion parameters of the galvanometer to control the scanning direction and speed of the laser beam to ensure that the laser beam can scan according to a preset scanning trajectory;

[0044] The motion parameters of the galvanometer include: deflection angle, response time, maximum speed and bandwidth;

[0045] The field lens parameter unit is used to adjust the focusing parameters of the field lens so that the laser beam can be accurately focused on the target position on the material strip.

[0046] Focus parameters include: focal length and working distance.

[0047] In a preferred embodiment of the present invention, a waste material removal module is further included, including: a gas blowing and material removal unit, which is used to control the injection of high-pressure gas to blow away waste materials from the working area to ensure the continuity and work efficiency of the cutting process;

[0048] Waste collection unit: used to collect blown-away waste to prevent it from interfering with the production process.

[0049] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0050] (1) The present invention provides a lithium battery pole piece ultrafast laser step-by-step die-cutting system and die-cutting method thereof. By presetting the trajectory generation and laser beam focusing steps, the scanning path and focal position of the laser beam can be precisely controlled, thereby achieving accurate cutting of the pole piece strip. This method avoids the errors and burrs that may be generated by traditional mechanical cutting, improves the cutting accuracy and quality, and at the same time, this high-precision cutting is crucial for lithium battery pole pieces, which have extremely high requirements for size and shape, and can significantly improve the performance and safety of the battery.

[0051] (2) The present invention divides the cutting process into two processes: pre-cutting and edge trimming. A step-by-step cutting method is used to first cut the electrode piece to a weak connection state through preliminary cutting, and then a secondary cutting is performed to remove burrs, which can effectively improve the cutting efficiency and quality. During the preliminary cutting, the laser power and cutting speed can be switched according to the different electrode properties to ensure the accuracy and stability of the cutting. The secondary cutting focuses on removing burrs to further optimize the cutting effect.

[0052] (3) The present invention records the primary and secondary heat-affected zones and evaluates the preset laser scanning path in combination with these data. This method can ensure that each cut can meet the same quality standards, thereby improving product consistency. This can not only improve cutting efficiency, but also reduce the thermal impact of the laser on the pole piece, reducing thermal deformation and performance loss of the pole piece.

[0053] (4) This method achieves rapid cutting of lithium battery electrodes through preset laser scanning paths and automated laser beam focusing; the automated process reduces manual intervention, reduces operation time, and improves overall production efficiency; at the same time, through analog galvanometer control and field lens focusing technology, the laser beam can be accurately and quickly positioned to the optimal focal position, further improving the cutting speed.

[0054] (5) By evaluating the secondary heat-affected zone, the present invention can more accurately understand the distribution of thermal effects on the pole piece after multiple laser processing, which helps to optimize laser parameters such as power, speed and focal length to reduce the heat-affected zone and avoid overheating or uneven heating of the material, thereby improving the cutting quality; at the same time, by accurately evaluating the secondary heat-affected zone, the thermal stress of the material can be better managed and deformation caused by thermal expansion or contraction can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0056] Figure 1 is a system structure diagram of a preferred embodiment of the present invention;

[0057] Figure 2 is a flow chart of a preferred embodiment of the present invention;

[0058] Figure 3 Schematic diagram of laser die cutting of lithium battery pole pieces according to a preferred embodiment of the present invention;

[0059] Figure 4 This is a cutting cross-sectional effect diagram of the fillet area of ​​the pole piece of the first embodiment of the present invention;

[0060] Figure 5 This is a front view of the cutting effect of the fillet area of ​​the pole piece of the first embodiment of the present invention;

[0061] Figure 6 This is a reverse side effect diagram of the cutting of the fillet area of ​​the pole piece of the first embodiment of the present invention;

[0062] Figure 7 This is a cross-sectional effect diagram of a straight line region of a pole piece according to a second embodiment of the present invention;

[0063] Figure 8 This is a front view of the cutting effect of the straight line area of ​​the pole piece of the second embodiment of the present invention;

[0064] Fig. 9 This is a reverse side effect diagram of the cutting of the straight line area of ​​the pole piece of the second embodiment of the present invention.

[0065] In the figure: 1. Waste area. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0068] like Figure 1 As shown, a lithium battery pole piece ultrafast laser step-by-step die-cutting system includes: a material strip analysis module, a laser trajectory module, a galvanometer focusing module, a pole piece cutting module, a heat-affected zone module, and a path evaluation module, characterized in that:

[0069] The strip analysis module includes:

[0070] Dimension measurement unit, used to measure the length and width of the strip to ensure the accuracy of the laser cutting path;

[0071] The shape scanning unit is used to scan the profile of the strip and obtain its specific shape information in order to establish an accurate pole piece strip model;

[0072] The property input unit is used to input the physical property information of the electrode, including the electrode thickness and the electrode composition; the electrode composition is a metal foil material, and the metal foil material includes a copper foil electrode and an aluminum foil electrode;

[0073] The model building unit is used to build a pole piece strip model according to the collected size, shape and attribute information.

[0074] The laser track module includes:

[0075] Edge positioning unit, used to determine the position of the edge of the material strip so that the laser beam can start cutting accurately;

[0076] Focus position unit, used to calculate the best focus position of the laser beam on the material strip to ensure cutting accuracy;

[0077] The trajectory generating unit is used to generate the scanning trajectory of the laser beam according to the focus position and edge positioning information, that is, the preset laser scanning path.

[0078] The galvanometer focusing module includes:

[0079] The galvanometer parameter unit is used to set and control the motion parameters of the galvanometer to control the scanning direction and speed of the laser beam to ensure that the laser beam can scan according to the preset scanning trajectory;

[0080] The motion parameters of the galvanometer include:

[0081] Deflection angle: It is the angle range within which the galvanometer can deflect the laser beam, which determines the size of the laser processing area and has a value range of ±5° to ±45°.

[0082] Response time: It is the time required for the galvanometer to respond to the control signal and reach the specified deflection angle, and the value range is 10μs-1ms.

[0083] Maximum speed: The maximum deflection speed that the galvanometer can achieve, ranging from 10° / s to 160° / s.

[0084] Bandwidth: The signal frequency range that the galvanometer can process, which affects the dynamic response and has a value range of 1-5kHz.

[0085] The field lens parameter unit is used to adjust the focusing parameters of the field lens so that the laser beam can be accurately focused on the target position on the material strip.

[0086] Focus parameters include:

[0087] Focal length: The focal length of the field lens determines the spot size and position of the laser beam after focusing, and the value range is 10mm-1000mm.

[0088] Working distance: The distance from the field lens to the focusing point, i.e. the pole piece, ranges from 10mm to 500mm.

[0089] The pole piece cutting module includes:

[0090] Laser power unit, used to adjust the laser power according to different material properties to achieve the best cutting effect;

[0091] Cutting speed unit, used to adjust cutting speed to suit different material properties and laser power;

[0092] A laser emitting unit, used to emit a laser beam and perform the actual cutting operation;

[0093] The burr recognition unit is used to identify the burrs after cutting and provide a basis for secondary cutting.

[0094] Among them, for copper foil pole pieces, the thickness is 100-200μm, the corresponding laser power is 50-100W, and the cutting speed is 5-15μm / s; for aluminum foil pole pieces, the thickness is 40-80μm, the corresponding laser power is 150-250W, and the cutting speed is 10-30μm / s.

[0095] The Heat Affected Zone module includes:

[0096] The area edge recognition unit is used to identify the edge of the heat-affected area generated during the laser cutting process through an edge recognition algorithm; the edge recognition algorithm includes

[0097] Area depth recording unit, used to record the depth information of the heat affected area in order to evaluate the cutting quality. The path evaluation module includes:

[0098] Edge burr detection unit, used to detect burrs on the edge of the material strip after cutting;

[0099] Heat affected zone comparison unit, used to compare the primary and secondary heat affected zones to evaluate thermal damage during cutting;

[0100] A cutting surface smoothness detection unit, used to detect the smoothness of the cutting surface and evaluate the cutting quality;

[0101] The optimal path unit is used to evaluate and optimize the preset laser scanning path according to the above detection and comparison results to obtain the optimal cutting path of the pole piece.

[0102] Also included is a waste removal module, including:

[0103] Air blowing and material removal unit, used to control the jet of high-pressure gas to blow away the waste from the working area, ensuring the continuity and work efficiency of the cutting process;

[0104] Waste collection unit: used to collect blown-away waste to prevent it from interfering with the production process.

[0105] The waste removal module also includes a roller removal unit and a manual removal unit.

[0106] like Figure 2 As shown, a lithium battery pole piece ultrafast laser step-by-step die-cutting method comprises the following steps:

[0107] S1. Preset trajectory generation: collect the size and shape of the material strip to establish a pole piece material strip model, preset the laser beam scanning trajectory, and generate a preset laser scanning path;

[0108] S2, laser beam focusing: simulate the galvanometer to control the laser beam to scan along the preset laser scanning path, and simulate the field mirror to focus the laser beam on the pole piece strip model to form the best focal position for preliminary cutting;

[0109] S3, preliminary cutting: switch different laser powers and cutting speeds according to the different pole piece properties of the incoming material, cut the pole piece to a weak connection state, and record the first heat affected area at the preliminary cutting track;

[0110] S4, secondary cutting: simulate the laser beam to perform secondary cutting on the burrs at the initial cutting position of the pole piece again along the initial cutting trajectory, record the secondary heat affected area generated during the secondary cutting, and evaluate the preset laser scanning path in combination with the initial heat affected area;

[0111] S5. After repeating steps S2-S4 to obtain the optimal cutting path of the electrode piece, the cutting of the electrode piece is completed.

[0112] In S1, the specific steps of collecting the size and shape of the strip to establish the pole piece strip model are:

[0113] S11. Place the tape in a stable and interference-free environment to ensure that the tape does not move or deform during the scanning process;

[0114] S12, using a laser scanner to obtain size data and shape data of the material strip, the size data including the length, width, and thickness of the material strip, and the shape data including the specific contour of the edge of the material strip;

[0115] S13, input the collected size data and shape data into the STL model to create an accurate three-dimensional model of the pole piece strip.

[0116] In S1, the specific steps of generating a preset laser scanning path are:

[0117] S13, inputting the motion parameters of the galvanometer and the focusing parameters of the field lens into the model to establish the galvanometer and the field lens, and simulating the interaction between the laser beam and the material strip;

[0118] S14, establishing the starting point and the end point of the laser beam, and setting a number of connection points between the two points, connecting the starting point, the connection point and the end point in sequence to obtain a preset laser scanning path.

[0119] In S2, the laser beam is emitted by a simulated ultrafast laser, which is either a picosecond laser or a femtosecond laser.

[0120] In S2, the specific calculation steps of the optimal focus position are:

[0121] S21, according to Rayleigh length Where ω0 is the waist radius of the laser beam, and λ is the wavelength of the laser beam;

[0122] S22, working distance Wherein the working distance WD is the distance from the lens to the surface of the strip, f is the focal length of the focusing lens, ω0 is the waist radius of the laser beam, λ is the wavelength of the laser beam, and θ is the full angle of divergence of the laser beam;

[0123] S23, get the best focus position

[0124] In S3, the specific steps of preliminary cutting are:

[0125] S31, using a galvanometer to control the laser beam to move along a preset laser scanning path, and using a focusing field lens to focus the laser beam to an optimal focus, and adjusting the laser power and cutting speed according to the properties of different material strips;

[0126] S32, start the laser emission unit, so that the laser beam cuts on the pole piece strip along a preset path, and cuts the strip to a weak connection state, that is, partially penetrated but not completely separated.

[0127] For example, a pole piece strip made of aluminum alloy is processed, and its surface is smooth and hard. In step S31, the laser beam is first controlled by the galvanometer to move along the preset laser scanning path. The galvanometer will accurately adjust the scanning angle and speed of the laser beam according to the preset path data to ensure that the laser beam can move along the predetermined trajectory.

[0128] At the same time, the focusing field lens is used to focus the laser beam to the best focus. The function of the focusing field lens is to converge the laser beam to a very small point to improve the energy density and cutting efficiency of the laser. By adjusting the focal length and position of the focusing field lens, it can be ensured that the laser beam forms a small and high-intensity spot on the surface of the material strip, thereby achieving accurate cutting of the material strip.

[0129] Since aluminum alloy has high hardness and reflectivity, it is necessary to adjust the laser power and cutting speed according to the properties of this material. Generally speaking, for materials with higher hardness, it is necessary to increase the laser power to improve the cutting effect; at the same time, in order to avoid overheating or ablation, it is necessary to reduce the cutting speed to ensure the stability and safety of the cutting process.

[0130] In step S32, the laser emitting unit is started, so that the laser beam starts to cut the pole piece strip along a preset path. At this time, the laser beam forms a continuous cutting line on the surface of the strip with the adjusted power and speed.

[0131] During the cutting process, it is necessary to pay close attention to the interaction between the laser beam and the tape, as well as the real-time feedback of the cutting effect. By constantly adjusting the laser parameters and scanning path, it is ensured that the laser beam can partially penetrate the tape, but not completely separate it. This weak connection state means that the tape still maintains a certain connection strength after cutting, but can be easily separated through subsequent process steps.

[0132] For example, in actual operation, it was observed that the laser beam formed a series of tiny perforations or notches on the cutting line, which did not completely disconnect the strip, but formed a hinge-like connection structure. This connection structure not only ensures the stability of the strip during the cutting process, but also facilitates the subsequent separation operation.

[0133] In S3, the specific steps of recording the first heat affected area at the initial cutting trajectory are:

[0134] S33, using a thermal imager to perform thermal imaging scanning on the initially cut pole piece strip, and obtaining the heat accumulation area generated by the initial laser irradiation at the initial cutting track, that is, the first heat affected area, through the thermal imaging results;

[0135] S34, using a temperature sensor to monitor and record the temperature change curve corresponding to the laser irradiation point in real time to obtain temperature distribution data;

[0136] S35. Determine the area most seriously affected by heat according to the temperature change curve, that is, the first heat-affected area, and extract and record the shape data and position data of the first heat-affected area through an image recognition algorithm.

[0137] In S3, the criteria for determining a weak connection state are:

[0138] The resistance of the cut area is measured to determine whether the material is still electrically connected; specifically, the resistance of a weakly connected electrode will be higher than that of a fully connected electrode, but lower than that of a fully cut electrode.

[0139] In S4, the specific steps of performing secondary cutting on the burrs at the initial cutting of the pole piece are as follows:

[0140] S41, identifying the burr position on the pole piece after preliminary cutting by a visual detection sensor, reducing the laser power and cutting speed of the laser beam according to the distribution of the burr, and simulating the laser beam to cut the pole piece again along the re-planned scanning path;

[0141] S42. After cutting, check the quality of the pole piece to ensure that the burrs have been completely removed and no new damage or increased thermal impact has been caused.

[0142] In S4, the specific steps of evaluating the preset laser scanning path are:

[0143] S43, overlapping area assessment: compare the secondary heat affected area with the primary heat affected area to check whether there is an overlapping area. If there is an overlap, it means that the path setting is reasonable and the heat affected range is well controlled. If there is no overlap, repeat step S2 to optimize the laser scanning path to avoid an excessively large heat affected range.

[0144] S44, area assessment: Count the size of the secondary heat affected area to determine whether it is larger than the primary heat affected area; if it is larger, it means that the laser scanning path needs to be adjusted to reduce the secondary heat affected area; if it is smaller, it means that the laser scanning path meets the requirements;

[0145] S45, total heat impact assessment: superimpose the secondary heat affected area with the primary heat affected area to check whether the total heat affected range exceeds the allowable range; if it exceeds, the laser scanning path needs to be optimized to reduce the total heat impact; if it is within the allowable range, it indicates that the laser scanning path meets the requirements;

[0146] S46, Area Shape Assessment: Determine whether the shape of the secondary heat affected area is consistent with the first one. If not, adjust the focus or laser scanning path to optimize the shape of the heat affected area.

[0147] In S45, the allowable range of thermal impact on the pole piece area is 20-30mm 2 .

[0148] In S5, it also includes the removal of waste areas of the material strip by air blowing, rollers or manual removal, such as Figure 3 shown.

[0149] Embodiment 1

[0150] Use the method provided in this application to cut the fillet area of ​​the pole piece. Figure 4 This is the cutting cross-section effect diagram of the fillet area of ​​the pole piece. Figure 5 This is the front effect diagram of the cutting of the fillet area of ​​the pole piece. Figure 6 This is the reverse side effect of cutting the fillet area of ​​the pole piece.

[0151] Embodiment 2

[0152] Use the method provided in this application to cut the straight line area of ​​the pole piece. Figure 7 This is the cutting cross-section effect diagram of the straight line area of ​​the pole piece. Figure 8 This is the front effect diagram of the cutting of the straight line area of ​​the pole piece. Fig. 9 This is the reverse effect diagram of cutting the straight line area of ​​the pole piece.

[0153] In summary, the ultrafast laser step-by-step die-cutting method for lithium battery pole pieces provided in the present application divides the cutting process into two processes, pre-cutting and edge trimming, based on the small heat-affected zone and low tendency of molten beads generated in ultrafast laser processing, thereby effectively avoiding the problem of pole piece burns generated during the processing. The cutting surface quality of the straight line area and the rounded corner area of ​​the pole piece is stable, flat and smooth, the interface is clear, the edge burrs are effectively controlled, the heat impact is small, and the quality problem of laser die-cutting processing of lithium battery pole pieces is solved.

[0154] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A lithium battery pole piece ultrafast laser step-by-step die-cutting method, characterized in that: The following steps are involved: S1. Preset trajectory generation: collect the size and shape of the material strip to establish a pole piece material strip model, preset the laser beam scanning trajectory, and generate a preset laser scanning path; S2. Laser beam focusing: simulate the galvanometer to control the laser beam to scan along the preset laser scanning path, and simulate the field mirror to focus the laser beam on the pole piece strip model to form the best focal position for preliminary cutting; the specific calculation steps of the best focal position are: S21, according to Rayleigh length , where ω0 is the waist radius of the laser beam and λ is the wavelength of the laser beam; S22, working distance , where the working distance WD is the distance from the lens to the surface of the strip, f is the focal length of the focusing lens, ω0 is the waist radius of the laser beam, λ is the wavelength of the laser beam, and θ is the full angle of divergence of the laser beam; S23, get the best focus position ; S3, preliminary cutting: switch different laser powers and cutting speeds according to the different pole piece properties of the incoming material, cut the pole piece to a weak connection state, and record the first heat affected area at the preliminary cutting track; S4, secondary cutting: simulate the laser beam to perform secondary cutting on the burrs at the initial cutting position of the pole piece again along the initial cutting trajectory, record the secondary heat affected area generated during the secondary cutting, and evaluate the preset laser scanning path in combination with the initial heat affected area; the specific steps for evaluating the preset laser scanning path are: S43, overlapping area evaluation: compare the secondary heat affected area with the initial heat affected area to check whether there is an overlapping area. If there is an overlap, it means that the path setting is reasonable and the heat affected range is well controlled; if there is no overlap, repeat step S2 to optimize the laser scanning path to avoid excessive heat affected range; S44, area assessment: Count the size of the secondary heat affected area to determine whether it is larger than the primary heat affected area; if it is larger, it means that the laser scanning path needs to be adjusted to reduce the secondary heat affected area; if it is smaller, it means that the laser scanning path meets the requirements; S45, total heat impact assessment: superimpose the secondary heat affected area with the primary heat affected area to check whether the total heat affected range exceeds the allowable range; if it exceeds, the laser scanning path needs to be optimized to reduce the total heat impact; if it is within the allowable range, it indicates that the laser scanning path meets the requirements; S46, area shape assessment: determine whether the shape of the secondary heat-affected area is consistent with the first one. If not, adjust the focus or laser scanning path to optimize the shape of the heat-affected area; S5. After repeating steps S2-S4 to obtain the optimal cutting path of the electrode piece, the cutting of the electrode piece is completed.

2. The method for ultrafast laser step-by-step die-cutting of lithium battery pole pieces according to claim 1, characterized in that: In S3, the specific steps of preliminary cutting are: S31, using a galvanometer to control the laser beam to move along a preset laser scanning path, and using a focusing field lens to focus the laser beam to an optimal focus, and adjusting the laser power and cutting speed according to the properties of different material strips; S32, start the laser emission unit, so that the laser beam cuts on the pole piece strip along a preset path, and cuts the strip to a weak connection state, that is, partially penetrated but not completely separated.

3. The method for ultrafast laser step-by-step die-cutting of lithium battery pole pieces according to claim 1, characterized in that: In S3, the specific steps of recording the first heat-affected area at the initial cutting trajectory are: S33, using a thermal imager to perform thermal imaging scanning on the initially cut pole piece strip, and obtaining the heat accumulation area generated by the initial laser irradiation at the initial cutting track, that is, the first heat affected area, through the thermal imaging results; S34, using a temperature sensor to monitor and record the temperature change curve corresponding to the laser irradiation point in real time to obtain temperature distribution data; S35. Determine the area most seriously affected by heat according to the temperature change curve, that is, the first heat-affected area, and extract and record the shape data and position data of the first heat-affected area through an image recognition algorithm.

4. The method for ultrafast laser step-by-step die-cutting of lithium battery pole pieces according to claim 1, characterized in that: In S4, the specific steps of performing secondary cutting on the burrs at the initial cutting of the electrode piece are: S41, identifying the burr position on the pole piece after preliminary cutting by a visual detection sensor, reducing the laser power and cutting speed of the laser beam according to the distribution of the burr, and simulating the laser beam to cut the pole piece again along the re-planned scanning path; S42. After cutting, check the quality of the pole piece to ensure that the burrs have been completely removed and no new damage or increased thermal impact has been caused.

5. The method for ultrafast laser step-by-step die-cutting of lithium battery pole pieces according to claim 1, characterized in that: In S1, the specific steps of collecting the size and shape of the material strip to establish the pole piece material strip model are: S11. Place the tape in a stable and interference-free environment to ensure that the tape does not move or deform during the scanning process; S12, using a laser scanner to obtain size data and shape data of the material strip, the size data including the length, width, and thickness of the material strip, and the shape data including the specific contour of the edge of the material strip; S13, input the collected size data and shape data into the STL model to create an accurate three-dimensional model of the pole piece strip.

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