Processing method of battery aluminum foil blank

Abstract

The invention relates to a processing method of a battery aluminum foil blank, which comprises the following steps: casting and rolling a melt to obtain a cast and rolled coil, and controlling casting and rolling parameters during casting and rolling, the casting and rolling parameters comprising the melt temperature in a front box, the temperature and pressure of cooling water, the rolling force, the rolling speed and the coiling tension, so that the middle convexity of the obtained cast and rolled coil is 0.1-1.0%, and the thickness difference of two side parts is less than 0.05 mm; cold rolling is conducted on the cast-rolled coil to obtain a battery aluminum foil blank finished product, cold rolling comprises rolling from the first pass to the fifth pass, and during rolling, rolling parameters of all rolling passes in cold rolling are controlled, so that the thickness difference fluctuation of the obtained battery aluminum foil blank finished product is smaller than 0.8%; the rolling parameters comprise the machining rate, the rolling speed, the inlet tension, the outlet tension and the plate shape curve, so that the thickness precision of the battery aluminum foil blank is improved, the plate shape flatness of the battery aluminum foil blank is guaranteed, and the final plate shape flatness and the thickness precision of the battery aluminum foil are improved.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum foil processing, and in particular to a method for processing battery aluminum foil blanks. Background Art

[0002] Under the guidance of development policies such as clean energy and industrial clusters, aluminum-based new materials have become the core guarantee for my country's rail transit lightweight and new energy storage fields. The demand for new products such as power battery aluminum foil, aluminum-air battery, and clean energy aluminum alloy has surged. Among them, lithium batteries are the core components of new energy vehicles. With the development of new energy vehicles, the demand for lithium batteries has grown rapidly. Battery aluminum foil, as the positive current collector material of mainstream lithium battery products, has been widely used, thus triggering a sharp increase in market demand.

[0003] With the development trend of large-scale modularization and integration of power batteries, power battery aluminum foil shows a trend of widening, and the precision, plate quality and surface requirements of power battery aluminum foil are getting higher and higher.

[0004] At present, the final shape, thickness and other quality characteristics of battery aluminum foil products are not only affected by the equipment and technical processes of the foil rolling process, but also by the genetic influence of the shape and thickness of the aluminum foil blank. However, in the relevant technology, when processing aluminum foil blanks, due to the lack of effective processing method guidance, the aluminum foil blanks have problems such as poor thickness accuracy and poor shape, which affect the service life and stability of power batteries. Summary of the invention

[0005] Based on this, the present application provides a processing method suitable for wide-width battery aluminum foil blanks, which can improve the thickness accuracy and plate flatness of the battery aluminum foil blanks, thereby helping to improve the stability of the power battery and extend the service life of the power battery.

[0006] The present application embodiment provides a method for processing a battery aluminum foil blank, comprising:

[0007] The melt is cast-rolled to obtain a cast roll, and the casting and rolling parameters are controlled during the casting and rolling, wherein the casting and rolling parameters include the melt temperature in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension, so that the crown of the cast-rolled roll is 0.1-1.0%, and the thickness difference between the two sides is less than 0.05 mm;

[0008] The cast-rolled coil is cold rolled to obtain a finished battery aluminum foil billet, and the cold rolling includes a first rolling pass, a second rolling pass, a third rolling pass, a fourth rolling pass and a fifth rolling pass. During the rolling, the rolling parameters of all rolling passes in the cold rolling are controlled so that the thickness difference fluctuation of the obtained battery aluminum foil billet product is less than 0.8%; wherein the rolling parameters include processing rate, rolling speed, inlet tension, outlet tension and plate shape curve.

[0009] In one embodiment, the step of casting the melt to obtain a cast coil specifically includes:

[0010] preparing a melt;

[0011] Confirm that the lengths of the casting and rolling areas on both sides of the casting nozzle are equal and the accuracy of the casting rolls meets the requirements;

[0012] After the melt is subjected to initial casting and rolling, the temperature of the melt in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension are confirmed; the initial casting and rolling lasts for a preset time;

[0013] The melt is continuously cast and rolled to obtain a cast-rolled plate;

[0014] Coiling the cast-rolled plate to obtain a cast-rolled coil;

[0015] Cut and measure the thickness of the cast-rolled coil at different positions to determine the center crown of the cast-rolled coil and the thickness difference on both sides.

[0016] In one embodiment, in the step of continuously casting and rolling the melt to obtain a cast plate,

[0017] Monitor the cooling water temperature at the inlet and outlet sides every 30±10min to ensure that the cooling water temperature fluctuation at the inlet is less than 2°C and the cooling water temperature fluctuation at the outlet is less than 1°C. Detect the thickness of both sides of the cast plate every 30±10min to ensure that the thickness difference at both sides is ≤0.02mm and the difference between the thickness at both sides and the target plate thickness is ≤0.02mm.

[0018] In one of the embodiments, the melt temperature in the front box is 690±5℃; the cooling water pressure is 0.20~0.25MPa, the cooling water temperature on the inlet side is 25~35℃, the difference between the cooling water temperature on the outlet side and the cooling water temperature on the inlet side is 10-20℃, the rolling force is equal to the plate width (cm)×(6.0~8.0) tons / cm, the rolling speed is (810±10)mm / min, and the coiling tension is adjusted according to the center convexity (0.04±0.01)mm; the length of the casting zone is (62±1)mm.

[0019] In one embodiment, the casting roll accuracy includes the casting roll roundness, casting roll coaxiality, diameter difference of paired casting rolls, roll gap of paired casting rolls and casting roll convexity; wherein, the casting roll roundness is <0.06mm, the casting roll coaxiality is <0.08mm, the diameter difference of paired casting rolls is ≤0.5mm, the roll gap of paired casting rolls is (6.7±0.1)mm, and the roll convexity is 0.14mm.

[0020] In one embodiment, the step of cold rolling the cast-rolled coil to obtain a finished battery aluminum foil blank specifically includes:

[0021] The cast-rolled coil is subjected to the first rolling process, wherein the rolling parameters of the first rolling process are: a processing rate of 40% to 50%, a rolling speed of 300 to 350 m / min, and an inlet tension of 8 to 10 kg / mm 2 ,Export tension 10~12kg / mm 2 , the plate shape curve is +2;

[0022] The cast rolled coil after the first rolling is annealed, and then the second rolling is performed. The rolling parameters of the second rolling are: processing rate 50% to 55%, rolling speed 300 to 350 m / min, inlet tension 70% to 80% of the outlet tension of the first rolling, and outlet tension (15±2) kg / mm 2 , the plate shape curve is -2 to +2, at which time the online bending roll force is in the range of 0 to +20 and remains stable;

[0023] The cast-rolled coil that has been rolled in the second pass is rolled in the third pass, the fourth pass and the fifth pass in sequence; wherein the rolling parameters corresponding to the third pass, the fourth pass and the fifth pass are: a processing rate of 45-50%, a rolling speed of 600-1200 m / min, an inlet tension of 70-80% of the outlet tension of the previous pass, and an outlet tension of (15±2) kg / mm 2 , the plate shape curve is -2~+2.

[0024] In one of the embodiments, during the cold rolling of the cast coil, rolling oil is used for cooling, the temperature of the rolling oil is 35-40°C, the spraying amount of the rolling oil is 40±2%, the additive of the rolling oil is 5.5%-6.5%, and the acid value is 0.30±0.05 mgKOH / g.

[0025] In one of the embodiments, the bending roll force during the first rolling pass is between 0% and +30%; the bending roll force during the second to fourth rolling passes is between -10% and +30%, and the bending roll force during the second to fourth rolling passes gradually decreases; the bending roll force during the fifth rolling pass is between -10% and +5%.

[0026] In one embodiment, the rolling speeds of the first rolling pass and the second rolling pass are both (dividing value-50) m / min, wherein the dividing value refers to the critical value between the low speed gear and the high speed gear of the cold rolling mill.

[0027] In one embodiment, the processing rate of the third rolling pass to the fifth rolling pass gradually increases.

[0028] The processing method of the battery aluminum foil blank controls the melt temperature in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension during casting and rolling, so that the convexity of the cast-rolled coil is 0.1-1.0%, and the thickness difference between the two sides is less than 0.05 mm; controls the processing rate, rolling speed, inlet tension, outlet tension and plate shape curve of all rolling passes during cold rolling, so that the thickness difference fluctuation of the obtained battery aluminum foil blank product is less than 0.8%, thereby improving the thickness accuracy of the battery aluminum foil blank, ensuring the plate shape flatness of the battery aluminum foil blank, and then improving the final plate shape flatness and thickness accuracy of the battery aluminum foil, which is beneficial to improving the stability of the power battery and extending the service life of the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart of a method for processing battery aluminum foil blanks provided in an embodiment of the present application.

[0030] Figure 2 The thickness fluctuation curve of the battery aluminum foil blank prepared by the processing method of Example 1 is shown in FIG.

[0031] Figure 3 The thickness fluctuation curve of the battery aluminum foil blank prepared by the processing method of comparative example 1 is shown in FIG. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0033] In the description of the present application, it should be understood that if the 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. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0034] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0035] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0036] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0037] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0038] like Figure 1 As shown, the embodiment of the present application provides a method for processing a battery aluminum foil blank, comprising:

[0039] S1. Casting and rolling the melt to obtain a cast roll, and controlling the casting and rolling parameters during the casting and rolling, wherein the casting and rolling parameters include the melt temperature in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed, and the coiling tension, so that the crown of the cast roll obtained is 0.1-1.0%, and the thickness difference between the two sides is less than 0.05 mm;

[0040] S2. Cold rolling the cast-rolled coil to obtain a finished battery aluminum foil billet, wherein the cold rolling includes a first rolling pass, a second rolling pass, a third rolling pass, a fourth rolling pass and a fifth rolling pass, and the rolling parameters of all the cold rolling passes are controlled during rolling so that the thickness difference fluctuation of the obtained finished battery aluminum foil billet is less than 0.8%; wherein the rolling parameters include processing rate, rolling speed, inlet tension, outlet tension and plate shape curve.

[0041] It should be noted that the edge refers to the position 8 to 10 cm inward from the edge of the cast-rolled plate. The two sides refer to the position 8 to 10 cm inward from the edges of the two sides of the cast-rolled plate. By measuring the thickness of the two sides of the cast-rolled plate and calculating the thickness difference of the two sides of the cast-rolled plate, the thickness distribution of the cast-rolled plate can be determined.

[0042] The processing method of the battery aluminum foil blank provided in the embodiment of the present application controls the melt temperature in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension during casting and rolling, so that the convexity of the cast-rolled coil is 0.1-1.0%, and the thickness difference between the two sides is less than 0.05 mm; controls the processing rate, rolling speed, inlet tension, outlet tension and plate shape curve of all rolling passes during cold rolling, so that the thickness difference fluctuation of the obtained battery aluminum foil blank product is less than 0.8%, thereby improving the thickness accuracy of the battery aluminum foil blank, ensuring the plate shape flatness of the battery aluminum foil blank, and then improving the final plate shape flatness and thickness accuracy of the battery aluminum foil, which is beneficial to improving the stability of the power battery and extending the service life of the power battery.

[0043] In one embodiment, in step S1, the step of casting the melt to obtain a cast coil specifically includes:

[0044] Prepare the melt; obtain the melt through smelting, refining, degassing and deslagging, online grain refinement and filtering treatment.

[0045] Confirm that the lengths of the casting and rolling areas on both sides of the casting nozzle are equal and the accuracy of the casting rolls meets the requirements.

[0046] Specifically, the length of the casting and rolling zone on both sides of the casting nozzle refers to the direct distance from the front edge of the casting nozzle to the center line of the two casting rolls, which can help improve the consistency of the thickness of the casting and rolling zone on both sides of the casting nozzle. The casting roll accuracy includes the casting roll roundness, casting roll coaxiality, the diameter difference of the paired casting rolls, the roll gap of the paired casting rolls and the casting roll crown; the casting roll roundness is less than 0.06mm, the casting roll coaxiality is less than 0.08mm, the diameter difference of the paired casting rolls is ≤0.5mm, the roll gap of the paired casting rolls is (6.7±0.1)mm, and the roll crown is 0.14mm.

[0047] After the melt is initially cast and rolled, the temperature of the melt in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension are confirmed; the initial casting and rolling lasts for a preset time.

[0048] Specifically, the preset duration can be set according to the actual situation, for example, the preset duration is 5-10min. The melt temperature in the front box is 690±5℃; the cooling water pressure is 0.20~0.25MPa, the cooling water temperature on the inlet side is 25~35℃, the difference between the cooling water temperature on the outlet side and the cooling water temperature on the inlet side is 10-20℃, the rolling force is equal to the plate width (cm)×(6.0~8.0) tons / cm, the rolling speed is (810±10)mm / min, and the coiling tension is adjusted according to the center convexity (0.04±0.01)mm; the length of the casting zone is (62±1)mm. It can be understood that "the coiling tension is adjusted according to the center convexity (0.04±0.01)mm" means adjusting the coiling tension under the premise of ensuring that the center convexity of the cast-rolled plate is (0.04±0.01)mm.

[0049] The melt is continuously cast and rolled to obtain a cast-rolled plate;

[0050] Specifically, during the continuous casting and rolling process, the cooling water temperature at the inlet and outlet sides is monitored at intervals of 30±10 minutes to ensure that the cooling water temperature fluctuation at the inlet is less than 2°C, and the cooling water temperature fluctuation at the outlet is less than 1°C. The thickness of both sides of the cast plate is detected at intervals of 30±10 minutes to ensure that the thickness difference at both sides is ≤0.02mm, and the difference between the thickness at both sides and the target plate thickness is ≤0.02mm, which is beneficial to improve the thickness accuracy and flatness of the cast plate, and further to improve the thickness accuracy and flatness of the processed aluminum foil billet.

[0051] Coiling the cast-rolled plate to obtain a cast-rolled coil;

[0052] Cut and measure the thickness of the cast-rolled coil at different positions to determine the center crown of the cast-rolled coil and the thickness difference on both sides.

[0053] Specifically, the rolled plate can be cut at the exit side of the rolling mill, and the cutting length is not less than one circumference of the casting roll. By cutting the cast-rolled coil and then measuring the thickness of the cast-rolled coil at different positions, the accuracy of the determined convexity of the cast-rolled coil and the thickness difference of the two sides can be improved.

[0054] In this embodiment, by confirming that the lengths of the casting and rolling zones on both sides of the casting nozzle are equal and the accuracy of the casting rollers meets the requirements, the melt is initially cast and rolled, and then the temperature of the melt in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension are confirmed. The melt is then continuously cast and rolled to obtain a cast-rolled plate, which can help improve the thickness accuracy and flatness of the cast-rolled plate, and further help improve the thickness accuracy and flatness of the cast-rolled coil, so that the convexity of the obtained cast-rolled coil is 0.1-1.0%, and the thickness difference on both sides is less than 0.05mm.

[0055] In one embodiment, in step S2, the step of cold rolling the cast-rolled coil to obtain a finished battery aluminum foil blank specifically includes:

[0056] The first rolling of the cast rolled coil is carried out, and the rolling parameters of the first rolling are: processing rate 40% to 50%, rolling speed 300 to 350 m / min, inlet tension 8 to 10 kg / mm 2 ,Export tension 10~12kg / mm 2 , the plate shape curve is +2;

[0057] The cast rolled coil after the first rolling is annealed, and then the second rolling is performed. The rolling parameters of the second rolling are: processing rate 50% to 55%, rolling speed 300 to 350 m / min, inlet tension 70% to 80% of the outlet tension of the first rolling, and outlet tension (15±2) kg / mm 2 , the plate shape curve is -2~+2;

[0058] The cast-rolled coil that has been rolled in the second pass is rolled in the third pass, the fourth pass and the fifth pass in sequence; wherein the rolling parameters corresponding to the third pass, the fourth pass and the fifth pass are: a processing rate of 45-50%, a rolling speed of 600-1200 m / min, an inlet tension of 70-80% of the outlet tension of the previous pass, and an outlet tension of (15±2) kg / mm 2 , the plate shape curve is -2~+2.

[0059] In this embodiment, in the cold rolling process, by controlling the rolling parameters of each rolling pass, the stability of the cast-rolled coil shape during each rolling pass can be ensured, the thickness fluctuation of the cast-rolled coil can be reduced, and the thickness accuracy can be improved.

[0060] It is understandable that the flatness curve is a system code, which is represented by numbers such as "+4, +3, +2, +1, 0, -1, -2, -3, -4" on the rolling mill operating system. The operator only needs to enter the numbers to complete the setting of the flatness curve. The corresponding flatness curve is a fixed line segment with a certain curvature. The flatness curves of different rolling passes can be adjusted according to the flatness characteristics (convexity, wedge shape, etc.).

[0061] In one embodiment, during the cold rolling of the cast coil, rolling oil is used for cooling, the temperature of the rolling oil is 35-40°C, the spraying amount of the rolling oil is 40±2%, the additive of the rolling oil is 5.5%-6.5%, and the acid value is 0.30±0.05mgKOH / g.

[0062] It should be noted that the spraying amount of rolling oil of 40±2% means that the spraying amount of rolling oil is 40±2% of the total flow of the rolling spray system; for example, the design flow value of the spraying system of the rolling mill is 2300L / min, and the spraying amount of rolling oil of 40±2% corresponds to 874-966L / min.

[0063] In one of the embodiments, the bending roll force during the first rolling pass is between 0% and +30%; the bending roll force during the second to fourth rolling passes is between -10% and +30%, and the bending roll force during the second to fourth rolling passes gradually decreases; the bending roll force during the fifth rolling pass is between -10% and +5%.

[0064] It should be noted that in the design of aluminum alloy plate, strip and foil rolling mill system, the hydraulic system will apply a pressure to the rolling roll through the support roll to adjust the actual crown and actual deflection of the rolling roll during the rolling process, so as to achieve the purpose of improving the plate shape and reducing the lateral thickness difference. The bending roll force refers to the ratio between the pressure applied by the hydraulic system and the preset rolling force. The technicians and on-site operators use this ratio to judge the matching of the equipment and the process and the level of process stability. When the ratio is 0, it means that the plate shape does not need to be adjusted, and the system believes that the plate shape is flat at this time; when the system detects that the plate shape is poor, it will continuously apply pressure through the hydraulic system according to the online plate shape detection results (specifically, continuously apply pressure to the rolling roller through the support roller). The ratio of this pressure to the preset rolling force (that is, the bending roll force) will form a fluctuation range as the rolling time progresses, such as (0~20%, -10%~+20%, etc.). The size and stability of this ratio represent the degree of poor quality and stability of the plate shape. The greater the absolute value fluctuation of the ratio, the worse the plate shape; the more stable the absolute value, the more stable the plate shape characteristics.

[0065] In this embodiment, during the cold rolling process, the bending roll force of the first to fifth rolling passes is set and adjusted according to 0 to +30%, -10% to +30%, and -10% to +5%, respectively, and remains basically stable during steady-state rolling. On this premise, the plate shape curve and processing rate can be adjusted to achieve high stability of the entire rolling process, especially the stability of the plate shape, thereby improving the thickness accuracy and plate shape stability of the battery aluminum foil billet. In addition, the second to fourth passes are three consecutive rolling passes, and the same pair of rolling rolls are used for rolling. At this time, the center convexity of the rolling rolls is fixed, but the material temperature after each rolling pass will gradually rise, resulting in an increase in the corresponding thermal convexity. Even if the processing technology design for each pass is carried out using the equal rolling force method, the online plate shape from the second to the fourth pass will show a systematic loose trend in the middle. For this reason, the bending roll force during the second to the fourth pass is gradually reduced, so that the plate shape of the aluminum foil billet can be quickly stabilized.

[0066] In a specific example, the bending roll force during the second rolling pass is between 0% and +20% and remains stable; the bending roll force during the third rolling pass is between -10% and +20% and remains stable; the bending roll force during the fourth rolling pass is between -10% and +5%; and the bending roll force during the fifth rolling pass is between -10% and 0.

[0067] When the second rolling is performed after annealing, the yield strength of the cast-rolled plate is the lowest and the plate shape resistance is the smallest. Usually, with high processing rate rolling (processing rate is 50% to 55%), under the combined effect of low deformation resistance and high processing rate rolling, the cast-rolled plate has a poor plate shape when the bending roll force is +15% or even +10%. For this reason, in the embodiment, the bending roll force during the second rolling is set at 0 to +20% to improve the matching degree between the bending roll force and the poor plate shape, so that it is convenient to adjust the processing rate, rolling speed and other parameters in time to improve the poor plate shape and improve the plate shape flatness and stability of the battery aluminum foil blank. By making the bending roll force in the second rolling pass within the range of 0 to +20% and maintaining it continuously; making the bending roll force in the third rolling pass within the range of -10% to +20% and maintaining it continuously; making the bending roll force in the fourth rolling pass within the range of -10% to +5%; and making the bending roll force in the fifth rolling pass within the range of -10% to 0, the thickness accuracy and plate shape stability of the battery aluminum foil blank can be improved.

[0068] In one embodiment, the rolling speeds of the first rolling pass and the second rolling pass are both (dividing value-50) m / min, wherein the dividing value refers to the critical value between the low speed gear and the high speed gear of the cold rolling mill.

[0069] The rolling speed of the rolling mill is designed to be divided into two gears, namely, high gear and low gear. For example, the speed dividing value of the high and low gears of some 1850mm cold rolling mills is 350m / min. When the rolling speed is increased from 300m / min to 400m / min, it will cross the dividing value between the low gear and the high gear. At this time, in the rolling mill control, there will be a switch from single motor drive to dual motor drive, which will cause a disturbance in rolling stability. In this embodiment, the rolling speeds of the first and second rolling passes are both (dividing value-50)m / min, so that the rolling speeds of the first and second rolling passes can be avoided from crossing the dividing value between the high gear and the low gear, thereby ensuring the continuous stability of the production state of the rolling mill, and then improving the thickness accuracy and flatness of the obtained battery aluminum foil billet.

[0070] In one embodiment, the processing rate of the third rolling pass to the fifth rolling pass gradually increases.

[0071] Specifically, the processing rate of the third rolling pass may be 42%, the processing rate of the fourth rolling pass may be 47%, and the processing rate of the fifth rolling pass may be 50%.

[0072] By gradually increasing the processing rate from the third to the fifth rolling pass, gradually reducing the rolling force from the third to the fifth rolling pass, and gradually increasing the rolling speed from the third to the fifth rolling pass, the plate shape stability of the cast-rolled coil during each continuous rolling pass can be ensured, and the thickness accuracy and flatness of the obtained battery aluminum foil billet can be improved.

[0073] In specific implementation, the processing method of the battery aluminum foil blank of the embodiment of the present application includes:

[0074] (1) Confirm the casting rolls and their accuracy;

[0075] Specifically, the roundness of the casting roll is less than 0.06 mm, and the coaxiality of the casting roll is less than 0.08 mm; the diameter difference of the paired casting rolls is ≤ 0.5 mm, and the convexity of the casting roll is 0.14 mm.

[0076] (2) Measure the casting and rolling areas on both sides of the casting nozzle and ensure that the casting and rolling areas on both sides are consistent, where the length of the casting and rolling area is (62±1) mm.

[0077] (3) Casting and rolling the vertical plate to obtain a cast-rolled coil;

[0078] Specifically, after the melt is initially cast and rolled, the temperature of the melt in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension are confirmed; the melt is continuously cast and rolled to obtain a cast-rolled plate; the cast-rolled plate is coiled to obtain a cast-rolled coil, the thickness of the cast-rolled coil at different positions is cut and measured, and the convexity of the cast-rolled coil and the thickness difference on both sides are determined.

[0079] The preset duration of the initial casting and rolling can be set according to the actual situation, for example, the preset duration is 5-10min. The melt temperature in the front box is 690±5℃; the cooling water pressure is 0.20~0.25MPa, the cooling water temperature on the inlet side is 25~35℃, the difference between the cooling water temperature on the outlet side and the cooling water temperature on the inlet side is 10-20℃, the rolling force is equal to the plate width (cm)×(6.0~8.0) tons / cm, the rolling speed is (810±10)mm / min, and the coiling tension is adjusted according to the center convexity (0.04±0.01)mm; the length of the casting zone is (62±1)mm. It can be understood that "the coiling tension is adjusted according to the center convexity (0.04±0.01)mm" means adjusting the coiling tension under the premise of ensuring that the center convexity of the cast-rolled plate is (0.04±0.01)mm.

[0080] During the continuous casting and rolling process, the cooling water temperature at the inlet and outlet sides is monitored at intervals of 30±10min to ensure that the cooling water temperature fluctuation at the inlet is less than 2°C and the cooling water temperature fluctuation at the outlet is less than 1°C. The thickness of both sides of the cast-rolled plate is detected at intervals of 30±10min to ensure that the thickness difference at both sides is ≤0.02mm, and the difference between the thickness at both sides and the target plate thickness is ≤0.02mm, which is beneficial to improve the thickness accuracy and flatness of the cast-rolled plate, and further to improve the thickness accuracy and flatness of the processed aluminum foil billet.

[0081] (4) Perform cold rolling process.

[0082] Specifically, the cast-rolled coil is sequentially subjected to a first rolling pass, annealing, a second rolling pass, a third rolling pass, a fourth rolling pass and a fifth rolling pass to obtain a finished battery aluminum foil blank.

[0083] The temperature of the rolling oil used in the rolling process is 35-40°C, the spraying amount of the rolling oil is 40±2%, the additive of the rolling oil is 5.5%-6.5%, and the acid value is 0.30±0.05mgKOH / g.

[0084] The rolling parameters of the first rolling are: processing rate 40% to 50%, rolling speed 300 to 350 m / min, entrance tension 8 to 10 kg / mm 2 ,Export tension 10~12kg / mm 2 , the plate shape curve is +2;

[0085] The rolling parameters of the second rolling are: processing rate 50% to 55%, rolling speed 300 to 350 m / min, inlet tension 70% to 80% of the outlet tension of the first rolling, outlet tension (15 ± 2) kg / mm 2 , the plate shape curve is -2~+2;

[0086] The rolling parameters corresponding to the third, fourth and fifth passes are: processing rate 45-50%, rolling speed 600-1200 m / min, inlet tension 70-80% of the outlet tension of the previous pass, outlet tension (15±2) kg / mm 2 , the plate shape curve is -2~+2.

[0087] Several specific experimental examples are given below to illustrate the improvement effect of the processing method of the battery aluminum foil blank of the embodiment of the present application compared with the prior art.

[0088] Take conventional 1235 battery aluminum foil and wide battery aluminum foil billet with a cast and rolled plate width of 1600mm as an example.

[0089] Embodiment 1

[0090] The processing methods of battery aluminum foil blanks include:

[0091] (1) Confirm the casting rolls and their accuracy;

[0092] Specifically, the roundness of the casting roll is less than 0.06 mm, and the coaxiality of the casting roll is less than 0.08 mm; the diameter difference of the paired casting rolls is ≤ 0.5 mm, and the convexity of the casting roll is 0.14 mm.

[0093] (2) Measure the casting and rolling areas on both sides of the casting nozzle and ensure that the casting and rolling areas on both sides are consistent, where the length of the casting and rolling area is (62±1) mm.

[0094] (3) Casting and rolling the vertical plate to obtain a cast-rolled coil;

[0095] Specifically, after the melt is initially cast and rolled, the temperature of the melt in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension are confirmed; the melt is continuously cast and rolled to obtain a cast-rolled plate; the cast-rolled plate is coiled to obtain a cast-rolled coil, the thickness of the cast-rolled coil at different positions is cut and measured, and the convexity of the cast-rolled coil and the thickness difference on both sides are determined.

[0096] The preset duration of the initial casting and rolling can be set according to the actual situation, for example, the preset duration is 5-10min. The melt temperature in the front box is 690±5℃; the cooling water pressure is 0.20~0.25MPa, the cooling water temperature on the inlet side is 25~35℃, the difference between the cooling water temperature on the outlet side and the cooling water temperature on the inlet side is 10-20℃, the rolling force is equal to the plate width (cm)×(6.0~8.0) tons / cm, the rolling speed is (810±10)mm / min, and the coiling tension is adjusted according to the center convexity (0.04±0.01)mm; the length of the casting zone is (62±1)mm. It can be understood that "the coiling tension is adjusted according to the center convexity (0.04±0.01)mm" means adjusting the coiling tension under the premise of ensuring that the center convexity of the cast-rolled plate is (0.04±0.01)mm.

[0097] During the continuous casting and rolling process, the cooling water temperature at the inlet and outlet sides is monitored at intervals of 30±10min to ensure that the cooling water temperature fluctuation at the inlet is less than 2°C and the cooling water temperature fluctuation at the outlet is less than 1°C. The thickness of both sides of the cast-rolled plate is detected at intervals of 30±10min to ensure that the thickness difference at both sides is ≤0.02mm, and the difference between the thickness at both sides and the target plate thickness is ≤0.02mm, which is beneficial to improve the thickness accuracy and flatness of the cast-rolled plate, and further to improve the thickness accuracy and flatness of the processed aluminum foil billet.

[0098] (4) performing a cold rolling process;

[0099] Specifically, the cast-rolled coil is sequentially subjected to a first rolling pass, annealing, a second rolling pass, a third rolling pass, a fourth rolling pass and a fifth rolling pass to obtain a finished battery aluminum foil blank.

[0100] The temperature of the rolling oil used in the rolling process is 35-40°C, the spraying amount of the rolling oil is 40±2%, the additive of the rolling oil is 5.5%-6.5%, and the acid value is 0.30±0.05mgKOH / g.

[0101] The rolling parameters of the first rolling are: processing rate 40% to 50%, rolling speed 300 to 350 m / min, entrance tension 8 to 10 kg / mm 2 ,Export tension 10~12kg / mm 2 , the plate shape curve is +2;

[0102] The rolling parameters of the second rolling are: processing rate 50% to 55%, rolling speed 300 to 350 m / min, inlet tension 70% to 80% of the outlet tension of the first rolling, outlet tension (15 ± 2) kg / mm 2 , the plate shape curve is -2~+2;

[0103] The rolling parameters corresponding to the third, fourth and fifth passes are: processing rate 45-50%, rolling speed 600-1200 m / min, inlet tension 70-80% of the outlet tension of the previous pass, outlet tension (15±2) kg / mm 2 , the plate shape curve is -2~+2.

[0104] Table 1 shows the specific process parameters of the cold rolling process in this embodiment.

[0105]

[0106] (5) Perform foil rolling process to obtain battery aluminum foil finished product.

[0107] Comparative Example 1

[0108] The processing methods of battery aluminum foil blanks include:

[0109] (1) Confirm the casting rolls and their accuracy;

[0110] Specifically, the roundness of the casting roll is 0.1 mm, and the coaxiality of the casting roll is 0.1 mm; the diameter difference between the paired casting rolls is 1 mm, and the convexity of the casting roll is 0.2-0.4 mm.

[0111] (2) Measure the casting and rolling areas on both sides of the casting nozzle and ensure that the casting and rolling areas on both sides are consistent. The length of the rolling area is 60 mm.

[0112] (3) Casting and rolling the vertical plate to obtain a cast-rolled coil;

[0113] Among them, the melt temperature in the front box is 685°C; the cooling water pressure is 0.10-0.2MPa, the rolling force is 800-900 tons, and the rolling speed is 820-850mm / min.

[0114] (4) performing a cold rolling process;

[0115] Specifically, the cast-rolled coil is sequentially subjected to a first rolling pass, annealing, a second rolling pass, a third rolling pass, a fourth rolling pass and a fifth rolling pass to obtain a finished battery aluminum foil blank.

[0116] The temperature of the rolling oil used in the rolling process is 30-35°C, the spraying amount of the rolling oil is 35%-37%, the additive of the rolling oil is 6.5%-8.0%, and the acid value is 0.35-0.4 mgKOH / g.

[0117] Table 2 shows the specific process parameters of the cold rolling process in this embodiment.

[0118]

[0119] (5) Perform foil rolling process to obtain battery aluminum foil finished product.

[0120] Obtain the thickness difference fluctuation curve of the battery aluminum foil blank obtained in Example 1 and Comparative Example 1. Figure 2-Figure 3 shown.

[0121] from Figure 2 The thickness fluctuation curve of the battery aluminum foil blank shown in the figure shows that the thickness fluctuation of the battery aluminum foil blank is less than 0.8%, which is significantly smaller than Figure 3 The thickness difference fluctuation value of the battery aluminum foil blank shown indicates that the processing method of the battery aluminum foil blank of the embodiment of the present application can improve the thickness accuracy of the battery aluminum foil blank and improve the plate flatness of the battery aluminum foil blank, thereby helping to improve the stability of the power battery and extend the service life of the power battery.

[0122] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0123] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A method for processing battery aluminum foil blanks, characterized in that: include: The melt is cast-rolled to obtain a cast roll, and the casting and rolling parameters are controlled during the casting and rolling, wherein the casting and rolling parameters include the melt temperature in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension, so that the crown of the cast-rolled roll is 0.1-1.0%, and the thickness difference between the two sides is less than 0.05 mm; The cast-rolled coil is cold rolled to obtain a finished battery aluminum foil billet, and the cold rolling includes a first rolling pass, a second rolling pass, a third rolling pass, a fourth rolling pass and a fifth rolling pass. During the rolling, the rolling parameters of all rolling passes in the cold rolling are controlled so that the thickness difference fluctuation of the obtained battery aluminum foil billet product is less than 0.8%; wherein the rolling parameters include processing rate, rolling speed, inlet tension, outlet tension and plate shape curve.

2. The processing method of battery aluminum foil blank according to claim 1, characterized in that: The step of casting the melt to obtain a cast coil specifically comprises: preparing a melt; Confirm that the lengths of the casting and rolling areas on both sides of the casting nozzle are equal and the accuracy of the casting rolls meets the requirements; After the melt is subjected to initial casting and rolling, the temperature of the melt in the front box, the temperature and pressure of the cooling water, the rolling force, the rolling speed and the coiling tension are confirmed; the initial casting and rolling lasts for a preset time; The melt is continuously cast and rolled to obtain a cast-rolled plate; Coiling the cast-rolled plate to obtain a cast-rolled coil; Cut and measure the thickness of the cast-rolled coil at different positions to determine the center crown of the cast-rolled coil and the thickness difference on both sides.

3. The processing method of battery aluminum foil blank according to claim 2, characterized in that: In the step of continuously casting and rolling the melt to obtain a cast plate, Monitor the cooling water temperature at the inlet and outlet sides every 30±10min to ensure that the cooling water temperature fluctuation at the inlet is less than 2°C and the cooling water temperature fluctuation at the outlet is less than 1°C. Detect the thickness of both sides of the cast plate every 30±10min to ensure that the thickness difference at both sides is ≤0.02mm and the difference between the thickness at both sides and the target plate thickness is ≤0.02mm.

4. The processing method of battery aluminum foil blank according to claim 2, characterized in that: The melt temperature in the front box is 690±5℃; the cooling water pressure is 0.20~0.25MPa, the cooling water temperature on the inlet side is 25~35℃, the difference between the cooling water temperature on the outlet side and the cooling water temperature on the inlet side is 10-20℃, the rolling force is equal to the plate width (cm)×(6.0~8.0) tons / cm, the rolling speed is (810±10)mm / min, and the coiling tension is adjusted according to the center convexity (0.04±0.01)mm; the length of the casting zone is (62±1)mm.

5. The processing method of battery aluminum foil blank according to claim 2, characterized in that: The casting roll accuracy includes the casting roll roundness, casting roll coaxiality, diameter difference of paired casting rolls, roll gap of paired casting rolls and casting roll convexity; among them, the casting roll roundness is <0.06mm, the casting roll coaxiality is <0.08mm, the diameter difference of paired casting rolls is ≤0.5mm, the roll gap of paired casting rolls is (6.7±0.1)mm, and the roll convexity is 0.14mm.

6. The processing method of battery aluminum foil blank according to claim 1, characterized in that: The step of cold rolling the cast-rolled coil to obtain a finished battery aluminum foil blank specifically comprises: The cast-rolled coil is subjected to the first rolling process, wherein the rolling parameters of the first rolling process are: a processing rate of 40% to 50%, a rolling speed of 300 to 350 m / min, and an inlet tension of 8 to 10 kg / mm 2 ,Export tension 10~12kg / mm 2 , the plate shape curve is +2; The cast rolled coil after the first rolling is annealed, and then the second rolling is performed. The rolling parameters of the second rolling are: processing rate 50% to 55%, rolling speed 300 to 350 m / min, inlet tension 70% to 80% of the outlet tension of the first rolling, and outlet tension (15±2) kg / mm 2 , the plate shape curve is -2~+2; The cast-rolled coil that has been rolled in the second pass is rolled in the third pass, the fourth pass and the fifth pass in sequence; wherein the rolling parameters corresponding to the third pass, the fourth pass and the fifth pass are: a processing rate of 45-50%, a rolling speed of 600-1200 m / min, an inlet tension of 70-80% of the outlet tension of the previous pass, and an outlet tension of (15±2) kg / mm 2 , the plate shape curve is -2~+2.

7. The method for processing battery aluminum foil blank according to claim 6, characterized in that: During the cold rolling of the cast coil, rolling oil is used for cooling. The temperature of the rolling oil is 35-40°C, the spraying amount of the rolling oil is 40±2%, the additive of the rolling oil is 5.5%-6.5%, and the acid value is 0.30±0.05 mgKOH / g.

8. The method for processing battery aluminum foil blank according to claim 6, characterized in that: The bending roll force during the first rolling pass is between 0% and +30%; the bending roll force during the second to fourth rolling passes is between -10% and +30%, and the bending roll force during the second to fourth rolling passes gradually decreases; the bending roll force during the fifth rolling pass is between -10% and +5%.

9. The method for processing battery aluminum foil blank according to claim 6, characterized in that: The rolling speeds of the first rolling pass and the second rolling pass are both (dividing value-50) m / min, wherein the dividing value refers to the critical value between the low speed gear and the high speed gear of the cold rolling mill.

10. The method for processing battery aluminum foil blank according to claim 6, characterized in that: The processing rates from the third rolling pass to the fifth rolling pass gradually increase.

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