Grinding process for negative electrode knife board of die-cutting knife

Abstract

The invention relates to the technical field of metal processing, in particular to a die-cutting knife negative electrode knife board grinding process which is characterized by comprising the following steps that S1, a grinding wheel is finely trimmed through a surface grinding machine, and it is guaranteed that the overall cutting position of the grinding wheel is flat and smooth; s2, the to-be-ground cutting board is fixed, and it is guaranteed that the parallelism of the to-be-ground cutting board, the left-right planeness of the cutting board, the left-right inclination straightness of a cutting edge and the up-down perpendicularity of the cutting board are all smaller than 2 micrometers; s3, a grinding wheel of the surface grinding machine is used for gently aligning the to-be-ground cutting board; s4, the cutting edge is accurately ground, after the reference position is aligned, a grinding machine grinding wheel is started to rotate for grinding, the cutting amount of each time is not higher than 0.2 micron until the perpendicularity of the small plane and the inner plane of the cutting edge of the cutting board is smaller than 2 microns and the straightness of the small plane of the cutting edge is smaller than 2 microns, and the cutting edge can be accurately ground by accurately controlling the flat position of the cutter before grinding and accurately controlling the cutting amount of the grinding wheel during grinding. Micron-sized small gaps of a negative electrode cutting board of the die-cutting knife can be reduced, the single service life of the knife can be more than 3 million times of punching, burrs of a battery pole piece can be controlled to be less than 8 microns, and the problem of powder falling is improved in detail.

Description

Technical Field

[0001] The invention relates to the technical field of metal processing, in particular to a grinding process for a negative electrode blade of a die cutting knife. Background Art

[0002] After the lithium-ion battery pole piece is coated with slurry, dried and rolled, it forms a three-layer composite structure of current collector and two-sided coating. Then according to the battery design structure and specifications, we need to cut the pole piece. Generally, for wound batteries, the pole piece is divided into strips according to the design width; for laminated batteries, the pole piece is cut into sheets accordingly, such as Figure 1 As shown. At present, the following three processes are mainly used for cutting lithium-ion battery pole pieces: (1) disc shear cutting, (2) die punching, and (3) laser cutting. During the pole piece cutting process, the quality of the pole piece 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 pole pieces, causing battery safety problems; (3) thermal damage to the material, coating shedding, etc., causing the material to lose activity and unable to function; (4) uneven cutting edges cause uneven charging and discharging of the pole piece. Therefore, the pole piece cutting process needs to avoid these problems and improve the process quality.

[0003] At present, most of the negative electrode cutters that are punched by molds are sharpened to about 19 degrees, and the tip of the knife is relatively sharp. The negative electrode cutters obtained by grinding in the prior art will have different degrees of micron-level small notches. In the process of punching ultra-thin electrode sheets, problems such as loss of points and burrs may occur, which will reduce the performance and quality of the battery and reduce the service life of the tool. Summary of the invention

[0004] The purpose of the present invention is to provide a process for grinding a negative electrode blade of a die cutting knife to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a die-cutting knife negative electrode blade grinding process, characterized in that it includes the following steps: S1. Fine-dress the grinding wheel on the surface grinder to ensure that the overall cutting position of the grinding wheel is flat and smooth; S2. Fix the blade to be ground to ensure that the parallelism of the blade to be ground, the left and right flatness of the blade, the straightness of the left and right tilt of the cutting edge, and the verticality of the blade are all less than 2um; S3. Use the grinding wheel of the surface grinder to gently grind the blade; S4. Finely grind the cutting edge. After aligning the reference position, turn on the grinding wheel of the grinder to rotate and grind. The amount of each cut should not exceed 0.2um, until the verticality of the small plane of the cutting edge and the inner plane of the blade is less than 2um, and the straightness of the small plane of the cutting edge is less than 2um.

[0006] Furthermore, the grinding wheel is a diamond grinding wheel.

[0007] Furthermore, the grinding wheel finishing thickness is 0.1-0.2 mm.

[0008] Furthermore, in S2, the blade to be ground is fixed by using precision flat-nose pliers.

[0009] Furthermore, in S2, a micrometer is used to measure parallelism, flatness and straightness.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: the negative electrode blade grinding process of the die-cutting knife can reduce the micron-level small notches on the negative electrode blade of the die-cutting knife by accurately controlling the flat position of the tool before grinding and the cutting amount of the grinding wheel during grinding. The single service life of the tool can be greater than 3 million times, the burrs of the battery electrode can be controlled to less than 8μm, and the powder loss problem is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a flow chart of the present invention; Figure 2 It is a schematic diagram of the processing state structure of the present invention; Figure 3 This is a schematic diagram of the blade structure of the present invention; Figure 4 This is a schematic diagram of the microstructure of the punched longitudinal cross section of the negative electrode sheet of the battery of the present invention; Figure 5 It is a schematic diagram of the microstructure of the punched transverse cross section of the negative electrode sheet of the battery of the present invention. DETAILED DESCRIPTION

[0012] 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.

[0013] See also Figure 1-5 , an embodiment of the present invention provides: a die-cutting knife negative electrode blade grinding process, comprising the following steps: S1. The surface grinder fine-dresses the grinding wheel to ensure that the overall cutting position of the grinding wheel is flat and smooth. The grinding wheel is a diamond grinding wheel, and the grinding wheel fine-dressing thickness is 0.1-0.2mm; S2. Use precision flat-nose pliers to fix the blade to be ground, and use a micrometer to measure parallelism, flatness and straightness to ensure that the parallelism of the blade to be ground, the left and right flatness of the blade, the straightness of the left and right tilt of the cutting edge, and the verticality of the blade are all less than 2um; S3. Use the grinding wheel of the surface grinder to gently grind the blade; S4. Fine grinding of the cutting edge. After aligning the reference position, turn on the grinding wheel of the grinding machine to rotate and grind. The amount of each cut should not exceed 0.2um. Refer to the attached Figure 3 , until the perpendicularity between the small plane of the blade edge and the inner plane is less than 2um, and the straightness of the small plane of the blade edge is less than 2um.

[0014] The tool ground by the die-cutting negative electrode blade grinding process is used to punch out the negative electrode sheet of the battery. The finished product effect is as follows: As can be seen from the table above, the negative electrode blade grinding process of the die-cutting knife can reduce the micron-level small gaps on the negative electrode blade of the die-cutting knife, and the single service life of the tool can be greater than 3 million times. Figure 4 This is a schematic diagram of the longitudinal cross-section microstructure of the battery negative electrode punching, with a burr size of 4.766μm. Figure 5 This is a schematic diagram of the microstructure of the transverse cross-section of the punched battery negative electrode. The burr size is 5.24μm. The burr of the battery electrode can be controlled to less than 8μm, and the powder loss problem is significantly improved.

[0015] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. The grinding process of the negative electrode blade of the die cutting knife is characterized in that: The following steps are involved: S1. Fine-dress the grinding wheel on the surface grinder to ensure that the overall cutting position of the grinding wheel is flat and smooth; S2. Fix the blade to be ground to ensure that the parallelism of the blade to be ground, the left and right flatness of the blade, the straightness of the left and right tilt of the cutting edge, and the verticality of the blade are all less than 2um; S3. Use the grinding wheel of the surface grinder to gently grind the blade; S4. Finely grind the cutting edge. After aligning the reference position, turn on the grinding wheel of the grinder to rotate and grind. The amount of each cut should not exceed 0.2um, until the verticality of the small plane of the cutting edge and the inner plane of the blade is less than 2um, and the straightness of the small plane of the cutting edge is less than 2um.

2. The die-cutting knife negative electrode blade grinding process according to claim 1, characterized in that: The grinding wheel is a diamond grinding wheel.

3. The die-cutting knife negative electrode blade grinding process according to claim 1, characterized in that: The grinding wheel finishing thickness is 0.1-0.2 mm.

4. The die-cutting knife negative electrode blade grinding process according to claim 1, characterized in that: In the S2, the blade to be ground is fixed by using precision flat-nose pliers.

5. The die-cutting knife negative electrode blade grinding process according to claim 1, characterized in that: In the S2, a micrometer is used to measure parallelism, flatness and straightness.

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