A rolling process for battery foils

Abstract

The application discloses a rolling process of a battery foil, characterized in that a blank is distributed and rolled according to a three-pass process, and one pass of rough rolling, one pass of medium rolling and one pass of fine rolling are respectively arranged; the reduction of the rough rolling and the medium rolling is 62% to 64%; the process has the advantages that the battery foil product is rolled in three passes, one rolling pass is reduced, the processing efficiency is improved, the processing cost is reduced, the production cost is lowered, and the production capacity is improved.

Description

Technical Field

[0001] This invention relates to the field of battery foil technology, and in particular to a rolling process for battery foil. Background Technology

[0002] With the rapid development of new energy electric vehicles, the demand for core components like lithium batteries is booming. As the cathode material for lithium batteries, aluminum foil requires higher performance and quality standards. The technical specifications for battery foil are stringent; customers have extremely high requirements for thickness, strength, shape, and cleanliness, making production difficult. Currently, the common process for producing battery foil involves four rolling passes. After long-term production exploration, this process is now mature, and the corresponding rolling oil, rolls, and rolling parameters are basically stable. However, the current four-pass production method results in low processing rates for each pass, especially the intermediate and finishing passes. The processing costs and production efficiency severely limit the profit margin and production capacity requirements of battery foil products. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0004] A rolling process for battery foil involves rolling a billet in three passes: one roughing pass, one intermediate rolling pass, and one finishing pass. Taking a billet with a thickness of 220 μm as an example, the rolling passes are allocated as follows: 220 μm → 80 μm → 30 μm → 13 μm. The reduction in both the roughing and intermediate rolling passes is 62%–64%. The most important aspect of achieving a three-pass process is increasing the reduction amount. Currently, the reduction amount in a four-pass process is between 50% and 60%. Taking a 220μm billet as an example, the reduction amounts are 220μm→100μm→40 / 42μm→20 / 21μm→12 / 13. In the process of increasing the reduction amount, in order to ensure that the aluminum foil produced by the three-pass process is of the same quality as that produced by the four-pass process, there are high requirements for the rolling motor, rolls, and rolling oil. If the oil film strength is insufficient, it will not provide lubrication during the rolling process, and the shape of the rolled sheet will deteriorate. Generally speaking, the smaller the reduction amount in each pass, the more stable the process parameters are. The large reduction amount used in this invention has already reached the upper limit of the rolling oil and roll parameters, and the process cannot be further simplified.

[0005] A further preferred technical solution is that the thickness of the blank ranges from 220μm to 240μm.

[0006] A further preferred technical solution is that the roughness of the support rollers in the three passes is selected to be between Ra: 0.6 and 0.7 μm, and the crown of the support rollers is 20‰-30‰.

[0007] A further preferred technical solution is that all three rolling passes employ flat roll rolling. Thermal crown refers to the degree of slight deformation of the rolls during rolling. During rolling, especially in processes involving reducing the number of passes, metal deformation generates a large amount of heat, causing slight thermal expansion of the rolls and resulting in thermal crown. If the thermal crown of the rolls is high in some areas and low in others, it will result in poor sheet shape; therefore, flat roll rolling is used.

[0008] A further preferred technical solution is that the surface roughness of the work rolls in each pass is:

[0009] The surface roughness of the roughing mill work rolls is selected to be between Ra: 0.21 and 0.23 μm;

[0010] The surface roughness of the intermediate rolling mill work rolls is selected between Ra: 0.09 and 0.10 μm;

[0011] The surface roughness Ra of the finishing mill work roll is between 0.07 and 0.08 μm.

[0012] The wider the material being produced, the more easily its edges deform. To ensure consistent plate shape, a further preferred technical solution is that when producing materials with a width ≤ 1200 mm, the convexity of the work roller is 30‰; when producing materials with a width > 1200 mm, the convexity of the work roller is 50‰. A higher convexity helps to tighten the edges, reducing edge shape defects.

[0013] A further preferred technical solution is that the rolling oil for the three passes uses 80# base oil with 10%–11% Goudain additive, wherein the Goudain additive contains 100% ester. The quality of lubrication depends on whether a continuous and durable oil film can be formed on the contact surfaces of relatively moving parts. The strength of the oil film is related to its high-temperature shear viscosity. Synthetic oils made from Group I to Group IV base oils typically contain various additives to improve their high-temperature shear viscosity. However, when the base oil and additives fail, the oil film becomes fragile and prone to breakage. Under these conditions, only ester-based synthetic oils can maintain superior lubrication, and the higher the ester content, the stronger the oil film.

[0014] A further preferred technical solution is that the work roll is ground using an abrasive wheel, and the roughness of the abrasive wheel is selected to be Ra: 0.6~0.7μm. Generally, work rolls are reused, and their roughness and other parameters change after rolling, or the roll itself may develop defects, requiring grinding with an abrasive wheel. The roughness of the abrasive wheel differs from that of the roll. The roll is obtained after grinding with an abrasive wheel. If the roughness of the abrasive wheel is too small, it is prone to slippage, and the grinding speed slows down. If it is too large, the grinding speed is too fast, making it impossible to control the roughness and other indicators of the roll itself.

[0015] A further preferred technical solution is that the rolling oil temperature is controlled at 30-40℃ during roughing and intermediate rolling, and the rolling oil temperature is controlled at 40-45℃ during finishing rolling.

[0016] Because aluminum foil has a speed effect, the faster the rolling speed, the thinner the aluminum foil. However, the pressing amount in this application is large. In order to achieve the pressing thickness during production, the speed of the first pass of rough rolling is 650-700 m / min, the speed of the second pass of intermediate rolling is 800-850 m / min, and the speed of the third pass of finishing rolling is 600-650 m / min.

[0017] Compared with the prior art, the beneficial effects of the present invention are: the present invention is the first to use a three-pass battery foil preparation process. Due to the use of three-pass rolling, the reduction in each pass is large, which requires a large oil film strength. At the same time, the large reduction generates more heat and the thermal convexity of the roll itself is large. The present invention overcomes these problems, achieves a breakthrough in the production of battery foil products in three passes, and reduces the production cost of enterprises. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] In the following examples, the Gaoyin additive used was from Shijiazhuang Xintai Gaoyin additive, and the grinding wheel used was a Japanese Noritac brand 320# grinding wheel.

[0020] Example 1

[0021] A rolling process for battery foil involves rolling the billet in three passes: one roughing pass, one intermediate rolling pass, and one finishing pass. Taking a billet with a thickness of 220 μm as an example, to produce a material with a width of 1300 mm, the rolling passes are allocated as follows: 220 μm → 80 μm → 30 μm → 13 μm.

[0022] The rolling process uses flat rolls, and the roll parameters are as follows:

[0023] The surface roughness of the support rollers for all three passes was selected to be between Ra: 0.6 and 0.7 μm, and the crown of the support rollers was Cr: 0.030 mm (30‰).

[0024] Roughness Ra of roughing roll: 0.21~0.23μm, crown Cr of roll: 0.050mm (50‰);

[0025] The surface roughness Ra of the intermediate rolling mill work roll is 0.09~0.10μm, and the crown Cr of the work roll is 0.050mm (50‰).

[0026] The surface roughness of the finishing mill work roll is 0.07~0.08μm, and the crown of the work roll (Cr) is 0.050mm (50‰).

[0027] The rolling oil is made of 80# base oil with 10% to 11% of goudarine additive, wherein the goudarine additive has an ester content of 100%.

[0028] The roughness of the grinding wheel is selected to be Ra: 0.6~0.7μm;

[0029] During production, the first pass of the roughing mill is at a speed of 650–700 m / min and an oil temperature of 33℃. The strip shape is stable, with a 99% overlap between the actual and target strip shapes. There are no strip breaks in the entire coil, and the surface quality is good. The second pass of the intermediate mill is at a speed of 800–850 m / min and an oil temperature of 35℃. The strip shape is stable again, with a 99% overlap between the actual and target strip shapes. There are no strip breaks in the entire coil, and the surface quality is good. The third pass of the finishing mill is at a speed of 600–650 m / min and an oil temperature of 40℃. The strip shape is stable, with a 98% overlap between the actual and target strip shapes. There are no strip breaks in the entire coil, and the surface quality is good.

[0030] Example 2

[0031] A rolling process for battery foil involves rolling the billet in three passes: one roughing pass, one intermediate rolling pass, and one finishing pass. Taking a billet with a thickness of 240 μm as an example, to produce a material with a width of 1200 mm, the rolling passes are allocated as follows: 240 μm → 91 μm → 34 μm → 12 μm.

[0032] The rolling process uses flat rolls, and the roll parameters are as follows:

[0033] The surface roughness of the support rollers for all three passes was selected to be between Ra: 0.6 and 0.7 μm, and the crown of the support rollers was Cr: 0.025 mm (25‰).

[0034] Roughness Ra of roughing roll: 0.21~0.23μm, crown Cr of roll: 0.030mm (30‰);

[0035] The surface roughness Ra of the intermediate rolling mill work roll is 0.09~0.10μm, and the crown Cr of the work roll is 0.030mm (30‰).

[0036] The surface roughness of the finishing mill work roll is 0.07~0.08μm, and the crown of the work roll Cr is 0.030mm (30‰).

[0037] The rolling oil is made of 80# base oil with 10% to 11% of goudarine additive, wherein the goudarine additive has an ester content of 100%.

[0038] The roughness of the grinding wheel is selected to be Ra: 0.6~0.7μm;

[0039] During production, the first pass of the roughing mill is at a speed of 650–700 m / min and an oil temperature of 35℃. The strip shape is stable, with an actual strip shape matching the target strip shape by 98%. There are no strip breaks in the entire coil, and the surface quality is good. The second pass of the intermediate mill is at a speed of 800–850 m / min and an oil temperature of 38℃. The strip shape is stable, with an actual strip shape matching the target strip shape by 98%. There are no strip breaks in the entire coil, and the surface quality is good. The third pass of the finishing mill is at a speed of 600–650 m / min and an oil temperature of 43℃. The strip shape is stable, with an actual strip shape matching the target strip shape by 96%. There are no strip breaks in the entire coil, and the surface quality is good.

[0040] Example 3

[0041] A rolling process for battery foil involves rolling the billet in three passes: one roughing pass, one intermediate rolling pass, and one finishing pass. Taking a billet with a thickness of 230 μm as an example, to produce a material with a width of 1100 mm, the rolling passes are allocated as follows: 230 μm → 85 μm → 30 μm → 12 μm.

[0042] The rolling process uses flat rolls, and the roll parameters are as follows:

[0043] The surface roughness of the support rollers for all three passes was selected to be between Ra: 0.6 and 0.7 μm, and the crown of the support rollers was Cr: 0.020 mm (20‰).

[0044] Roughness Ra of roughing roll: 0.21~0.23μm, crown Cr of roll: 0.030mm (30‰);

[0045] The surface roughness Ra of the intermediate rolling mill work roll is 0.09~0.10μm, and the crown Cr of the work roll is 0.030mm (30‰).

[0046] The surface roughness of the finishing mill work roll is 0.07~0.08μm, and the crown of the work roll Cr is 0.030mm (30‰).

[0047] The rolling oil is made of 80# base oil with 10% to 11% of goudarine additive, wherein the goudarine additive has an ester content of 100%.

[0048] The roughness of the grinding wheel is selected to be Ra: 0.6~0.7μm;

[0049] During production, the roughing mill's first pass is at a speed of 650–700 m / min and an oil temperature of 36℃. The strip shape is stable, with a 97% overlap between the actual and target strip shapes. There are no strip breaks in the entire coil, and the surface quality is good. The intermediate rolling mill's second pass is at a speed of 800–850 m / min and an oil temperature of 38℃. The strip shape is stable, with a 98% overlap between the actual and target strip shapes. There are no strip breaks in the entire coil, and the surface quality is good. The finishing mill's third pass is at a speed of 600–650 m / min and an oil temperature of 45℃. The strip shape is stable, with a 96% overlap between the actual and target strip shapes. There are no strip breaks in the entire coil, and the surface quality is good.

[0050] This invention pioneers a three-pass battery foil manufacturing process. Due to the use of three-pass rolling, the reduction in each pass is large, requiring a high oil film strength. At the same time, the large reduction generates more heat, resulting in a large thermal convexity of the rolls themselves. This invention overcomes these problems, achieving a breakthrough in the production of battery foil products in three passes and reducing the production costs for enterprises.

[0051] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A rolling process of a battery foil, the battery foil being an aluminum foil, characterized in that, The billet with a thickness range of 220μm to 240μm is rolled in three passes: one pass for roughing, one pass for intermediate rolling, and one pass for finishing. The reduction in both roughing and intermediate rolling is 62% to 64%. The surface roughness of the work rolls in each pass is as follows: roughing roll surface roughness Ra is 0.21~0.23μm, intermediate roll surface roughness Ra is 0.09~0.10μm, and finishing roll surface roughness Ra is 0.07~0.08μm. The rolling speed of the first pass of roughing is 650-700 m / min, the rolling speed of the second pass of intermediate rolling is 800-850 m / min, and the rolling speed of the third pass of finishing rolling is 600-650 m / min. The rolling oil for all three passes is 80# base oil with 10%~11% of Goudaine additive, and the Goudaine additive has an ester content of 100%. The rolling oil temperature is controlled at 33~38℃ during roughing and intermediate rolling, and at 40~45℃ during finishing rolling. When producing materials with a width ≤ 1200 mm, the crown of the work roller is 30‰; when producing materials with a width > 1200 mm, the crown of the work roller is 50‰.

2. The rolling process for a battery foil as described in claim 1, characterized in that, The surface roughness Ra of the support rollers in the three passes is 0.6~0.7μm, and the crown of the support rollers is 20‰-30‰.

3. The rolling process for a battery foil as described in claim 1, characterized in that, All three rolling passes employ flat roll rolling.

4. The rolling process for battery foil as described in claim 1, characterized in that, The working roller is ground by a grinding wheel with a surface roughness Ra of 0.6~0.7μm.