Semi-solid extrusion aluminum battery shell thin wall forming method and forming system

Abstract

The invention relates to the technical field of aluminum extrusion battery shells, in particular to a semi-solid extrusion aluminum battery shell thin-wall forming method and a semi-solid extrusion aluminum battery shell thin-wall forming system. The forming system comprises an extrusion die used for extruding a first blank, one end of the extrusion die is provided with a pushing part, the pushing part is used for pushing an aluminum bar into the extrusion die, the end, away from the pushing part, of the extrusion die is provided with an ultrasonic detection part, the ultrasonic detection part is used for obtaining defect data of the extruded first blank and uploading the defect data to a controller, and a cavity is formed in the extrusion die; a heating assembly is arranged in the circumferential direction of the cavity and used for heating the cavity, the heating assembly comprises first heating modules arranged on the four faces of the outer wall of the cavity and second heating modules arranged at the four corners of the cavity, first temperature sensors are arranged at the first heating modules, and second temperature sensors are arranged at the second heating modules. According to the invention, the thin-wall aluminum battery shell with stable structure and high performance can be better produced, so that the weight of the new energy battery shell is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum extruded battery shells, and in particular to a semi-solid extruded aluminum battery shell thin-wall forming method and forming system. Background Art

[0002] In recent years, with the rapid development of renewable energy and electric vehicles, aluminum batteries have broad application prospects in electric vehicles and portable electronic devices due to their excellent conductivity, light weight and corrosion resistance.

[0003] The existing technology produces thin-walled aluminum battery shells by first heating the aluminum ingot to a semi-solid state and then cold-drawing and extruding it through a cavity mold. During the cold-drawing and extrusion process of the thin-walled aluminum battery shell, the thin-walled material is prone to yield under high pressure. When extruding aluminum battery shells below 0.5 mm, due to insufficient material fluidity in the edge area, defects such as cracks and holes frequently occur, affecting the integrity of the overall structure. In addition, for thin-walled components, the control of flatness is particularly important. If the flatness of the shell cannot meet the design standards, it is easy to cause problems of easy damage during subsequent assembly and use. Summary of the invention

[0004] The present invention provides a method for forming a thin-walled semi-solid extruded aluminum battery shell, which can overcome certain defects of the prior art to improve the structural integrity and flatness of the aluminum battery shell.

[0005] The semi-solid extruded aluminum battery shell thin-wall forming method according to the present invention comprises: The first forming stage includes: heating and melting the aluminum ingot to obtain aluminum liquid, and casting the aluminum liquid to obtain an aluminum rod; the second forming stage includes: performing at least one heating step, keeping the aluminum rod in a semi-solid state, cutting it and squeezing it into an extrusion mold for extrusion molding to obtain a first blank, and heating the extrusion mold during the extrusion process to keep the first blank in the extrusion mold in a semi-solid state; the third forming stage includes: placing the first blank in a shaping mold to perform a stretching and flattening step to obtain a second blank, performing a sawing step on the second blank, and naturally cooling the second blank after the sawing step, and cutting with a laser cutting machine in the sawing step; the first post-processing stage includes: performing an aging step on the second blank to obtain a third blank; the second post-processing stage includes: performing an oxidation step on the third blank to obtain a battery shell.

[0006] Preferably, the first forming stage comprises: heating the aluminum ingot to 700° C. to obtain aluminum liquid, pouring the aluminum liquid into a casting mold for casting, and using circulating water to cool the casting mold during the casting process to form the aluminum rod.

[0007] Preferably, the second forming stage comprises: heating the aluminum rod to 400° C. to make the aluminum rod enter a semi-solid state, cutting the aluminum rod and extruding it into an extrusion die for extrusion forming, and heating the cavity of the extrusion die during the extrusion process.

[0008] Preferably, the aging step includes placing the second blank in an aging furnace, heating it to 180° C. and maintaining it for 4 hours to eliminate stress concentration of the second blank.

[0009] Preferably, the oxidation step includes an alkaline etching step and an electric oxidation step. In the alkaline etching step, a sodium hydroxide solution is used to remove the thin oxide film on the surface of the third blank. Before performing the alkaline etching step, water is used for a rinse. After performing the alkaline etching step, water is used for a second rinse. Thereafter, the third blank is placed in a water pool and dilute sulfuric acid is added to neutralize the alkaline components on the surface of the third blank.

[0010] Preferably, the electrical oxidation step includes placing the third blank after alkaline etching as an anode in an electrolytic cell, placing 70% sulfuric acid in the electrolytic cell and reacting for 10 minutes to form an oxide film on the surface of the third blank, and the electrical oxidation step is performed 2-3 times.

[0011] The present invention also provides a semi-solid extruded aluminum battery shell thin-wall forming system, which includes: an extrusion die, the extrusion die is used to extrude a first blank, a propulsion part is provided at one end of the extrusion die, the propulsion part is used to push the aluminum rod into the extrusion die, an ultrasonic detection part is provided at the end of the extrusion die away from the propulsion part, the ultrasonic detection part is used to obtain defect data of the extruded first blank and upload it to a controller, the extrusion die has a cavity, a heating component is provided along the circumference of the cavity, the heating component is used to heat the cavity, the heating component includes a first heating module provided on the four sides of the outer wall of the cavity, and a second heating module provided at the four corners of the cavity, a first temperature sensor is provided at the first heating module, and a second temperature sensor is provided at the second heating module.

[0012] Preferably, the controller includes: a data acquisition module: used to collect the propulsion speed of the propulsion unit to extrude the aluminum rod, the temperature data of the first temperature sensor, and the temperature data of the second temperature sensor; a data calculation module: to build an adjustment model according to the propulsion speed of the propulsion unit to extrude the aluminum rod, the temperature data of the first temperature sensor, the temperature data of the second temperature sensor, and the defect data, and generate adjustment parameters; a control module: to send adjustment parameters to the propulsion unit, the first heating module, and the second heating module to adjust the propulsion speed, the heating power of the first heating module, and the heating power of the second heating module.

[0013] Preferably, constructing the adjustment model comprises the following steps: S1: Put the aluminum rod into the propulsion unit at the initial propulsion speed Pushing towards the extrusion die, the initial side wall temperature of the extrusion die cavity is , the initial corner temperature of the extrusion die cavity is , the initial heating power of the first heating module is , the initial heating power of the second heating module is ; S2: The ultrasonic testing unit tests the first blank every 10 seconds to obtain defect data D; S3: Calculate the adjustment parameter according to the defect data D, the expression is: (1) in: For the new advancement speed, is the current advancement speed, is the propulsion speed adjustment coefficient caused by defective data, is the defect data variation, is the new side wall temperature, is the current side wall temperature, is the target molding temperature of the side wall, is the side wall temperature adjustment coefficient, is the new corner temperature, is the current corner temperature, is the target molding temperature of the corners, is the corner temperature adjustment coefficient, is the power of the new first heating module, Heating power for the new second module, is the current power of the first heating module, is the current heating power of the second module, is the power adjustment coefficient of the first heating module according to the defect data, is the power adjustment coefficient of the second heating module according to the defect data.

[0014] As a preference, , , , and Obtained by the following steps: Construct a multiple regression model, the expression is: (2) in is the bias term, is the error term, obtained by the least squares method , , , and .

[0015] Beneficial effects: 1. The present invention adopts semi-solid extrusion technology to form aluminum in a semi-solid state, which greatly improves the forming efficiency and product quality. This process can effectively reduce the flow resistance of the material and improve the forming accuracy, thereby producing a battery shell with a thinner wall and better mechanical properties, thereby preferably reducing the shell weight of the new energy battery.

[0016] 2. The present invention can effectively eliminate stress concentration in the second blank by performing an aging step, thereby preferably improving the corrosion resistance and mechanical properties of the material and extending the service life of the battery casing.

[0017] 3. The present invention can obtain a uniform and dense oxide film on the surface through the alkaline etching step and the electrical oxidation step, which not only improves the corrosion resistance of the battery shell, but also enhances its insulation performance, thereby preferably improving the safety and stability of the battery.

[0018] 4. In the present invention, the propulsion unit can extrude the aluminum rod into the extrusion die, thereby extruding the first blank, the ultrasonic detection unit can detect the extruded first blank to obtain defect data of the first blank, the temperature sensor can monitor the temperature in the cavity, and the heating coil can control the heating power, so that the temperature in the cavity can be adjusted as needed to improve the extrusion quality of the first blank.

[0019] 5. The present invention can adjust the advancement speed and cavity temperature in real time, so that the defect data D is kept in a lower range, thereby better improving the molding quality of the first blank. The system can be applied to aluminum alloy materials of various compositions, and can automatically adjust the advancement speed and cavity temperature according to the above formula without manual intervention, thereby better improving production efficiency.

[0020] 6. The present invention changes the temperature of the side walls and corners of the cavity by changing the heating power of the first heating module and the second heating module respectively. Therefore, the first heating module and the second heating module not only change the temperature of the edge of the cavity, but also can control the temperature of the side walls and corners of the cavity, thereby overcoming the disadvantages of conventional aluminum battery shell extrusion dies that the material fluidity in the edge area is insufficient, resulting in defects such as local cracks and holes. Furthermore, the advancement speed and the power of the first heating module and the second heating module are coupled through multiple parameters to perform real-time adjustment and optimization, so as to further reduce the defects of the first blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow chart of the thin-wall forming method of semi-solid extruded aluminum battery shell; Figure 2 It is a schematic diagram of the components of the semi-solid extruded aluminum battery shell thin-wall forming system; Figure 3 It is a schematic diagram of the controller module; Figure 4 It is a first cross-sectional schematic diagram of the internal structure of the extrusion die cavity; Figure 5 is a second cross-sectional schematic diagram of the internal structure of the extrusion die cavity; Figure 6 This is an axonometric diagram of the thin-wall forming system for semi-solid extruded aluminum battery shells. DETAILED DESCRIPTION

[0022] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the embodiments. It should be understood that the embodiments are only for explaining the present invention and are not intended to limit it.

[0023] Please refer to Figure 1 The present invention provides a semi-solid extruded aluminum battery shell thin-wall forming method, which can be used to produce a thin-walled aluminum battery shell, comprising the following steps: The first forming stage: the aluminum ingot is heated and melted to obtain aluminum liquid, and the aluminum liquid is cast to obtain an aluminum rod. The aluminum ingot can be made of aluminum alloy materials such as 6061 and 6063 according to the specific working state of the aluminum battery to ensure its mechanical properties and corrosion resistance. Specifically, a resistance furnace or a high-frequency furnace is used to heat the aluminum ingot to 700°C to obtain aluminum liquid, and the aluminum liquid is poured into a casting mold for casting. During the casting process, circulating water is used to cool the casting mold to form the aluminum rod.

[0024] The second forming stage: perform at least one heating step, heat the aluminum rod to 400°C, keep the aluminum rod in a semi-solid state, then cut and squeeze it into an extrusion mold for extrusion molding to obtain a first blank. During the extrusion process, the extrusion mold is heated to keep the first blank in the extrusion mold in a semi-solid state. The aluminum rod is heated to 400°C, kept in a semi-solid state, and then cut and extruded. The semi-solid aluminum rod shows better superiority in the forming process, has better fluidity and higher forming accuracy, can reduce defects such as pores and cracks during the forming process, and improves the final structural integrity and surface quality of the aluminum battery shell.

[0025] Therefore, through the above steps, a battery shell with a thickness of less than 0.4 mm can be preferably extruded, thereby preferably reducing the overall weight of the new energy battery, which is of great significance for the overall lightweighting of the new energy battery.

[0026] The third forming stage: placing the first blank into a shaping mold to perform a stretching and flattening step to obtain a second blank, performing a sawing step on the second blank, and naturally cooling the second blank after the sawing step. The sawing step is performed using a laser cutting machine.

[0027] The first post-processing stage: performing an aging step on the second blank to obtain a third blank, wherein the aging step includes placing the second blank in an aging furnace, heating it to 180°C and maintaining it for 4 hours to eliminate stress concentration in the second blank. Therefore, the aging step can improve the toughness and fatigue resistance of the material, reduce the risk of deformation and fracture during subsequent processing or use, and thus improve the service life and safety of the battery casing.

[0028] In addition, the above-mentioned aging treatment can also promote the homogenization of the internal structure and grain refinement of the aluminum alloy, thereby improving the mechanical properties of the material, so that the aluminum battery shell can better cope with the various mechanical loads generated by the battery during operation.

[0029] Second post-processing stage: performing an oxidation step on the third blank to obtain a battery shell.

[0030] Among them, the oxidation step includes an alkaline etching step and an electric oxidation step. The alkaline etching step uses a sodium hydroxide solution to remove the thin oxide film on the surface of the third blank. Before performing the alkaline etching step, water is used for a rinse. After performing the alkaline etching step, water is used for a second rinse. Then, the third blank is placed in a water pool and dilute sulfuric acid is added to neutralize the alkaline components on the surface of the third blank. The electric oxidation step includes placing the alkaline-etched third blank as an anode in an electrolytic cell, placing 70% sulfuric acid in the electrolytic cell and reacting for 10 minutes to form an oxide film on the surface of the third blank. The electric oxidation step is performed 2-3 times.

[0031] The oxidation step uses a combination of alkaline etching and energized oxidation to form a well-defined battery shell surface treatment process. The alkaline etching step effectively removes the thin oxide film by using sodium hydroxide solution, ensuring the uniformity and consistency of subsequent surface treatment.

[0032] In addition, water rinsing before and after the alkaline etching step can effectively remove impurities and chemical residues on the surface, ensuring the efficiency and effectiveness of the subsequent treatment process. Dilute sulfuric acid is then added for neutralization to further eliminate residual alkaline components and prevent negative effects on the subsequent oxide film formation. This precise neutralization control provides ideal pre-treatment conditions for aluminum electrolytic oxidation and enhances the film layer bonding.

[0033] During the energized oxidation process, by using the third blank after alkaline etching as the anode and using conductive graphite or other metals such as platinum as the cathode for electrolytic oxidation and performing it 2-3 times, a more uniform and compact oxide film can be formed. This multiple oxidation treatment ensures the structural consistency and integrity of the oxide film, improves the corrosion resistance and wear resistance of the battery shell, makes it not only have insulating properties, but also improves the electrochemical stability of the aluminum alloy, improves the ability of the electrolyte inside the battery to isolate and protect the internal components of the battery, and better extends the battery life.

[0034] Therefore, the above-mentioned processing method can significantly improve the surface quality of the battery shell and reduce surface defects, thereby helping to enhance the overall performance of the battery shell. This is of great significance for ultra-thin battery shell materials below 0.4 mm. It can reduce the thickness of the battery shell without reducing the mechanical properties, electrical and chemical properties of the battery shell, thereby better reducing the overall weight of the new energy battery.

[0035] See Figure 2-5 The present invention also provides a semi-solid extruded aluminum battery shell thin-wall forming system, which includes an extrusion die, the extrusion die is used to extrude a first blank, a propulsion part is provided at one end of the extrusion die, the propulsion part is used to push the aluminum rod into the extrusion die, an ultrasonic detection part is provided at one end of the extrusion die away from the propulsion part, the ultrasonic detection part is used to obtain defect data of the extruded first blank and upload it to a controller, a cavity 23 is provided in the extrusion die, a heating component 24 is provided along the circumference of the cavity 23, the heating component is used to heat the cavity 23, the heating component 24 includes a first heating module 241 provided on four sides of the outer wall of the cavity, and a second heating module 242 provided at four corners of the cavity 23, a first temperature sensor 251 is provided at the first heating module, and a second temperature sensor 252 is provided at the second heating module.

[0036] According to the above scheme, the propulsion unit can extrude the aluminum rod into the extrusion die, thereby extruding the first blank, the ultrasonic detection unit can detect the extruded first blank and obtain the defect data of the first blank, the first temperature sensor 251 can monitor the temperature of the side wall of the cavity, and the second temperature sensor 252 can monitor the temperature of the corners of the cavity, wherein there are 4 second temperature sensors 251 and 4 second temperature sensors 252.

[0037] Furthermore, the first heating module and the second heating module 242 can control the heating power, so that the temperature in the cavity can be better adjusted as needed to improve the extrusion quality of the first blank. Specifically, the first heating module 241 is responsible for heating the side walls around the cavity to reduce defects in the plane around the first blank, and the second heating module is responsible for heating the four corners of the cavity to reduce defects at the four corners of the first blank, thereby preventing the first blank from causing defects such as cracking due to insufficient material fluidity at the corners.

[0038] It can be understood that the propulsion unit can adopt a propulsion structure that can control the propulsion speed, such as a cylinder or oil cylinder propulsion structure, a linear motor propulsion structure or a screw propulsion structure. The extrusion mold can be customized according to the size and thickness of the battery shell to be produced. The ultrasonic detection unit includes an ultrasonic detector, an ultrasonic generator and a signal processing unit. The ultrasonic detector is used to transmit and receive ultrasonic signals. Through the reflection and refraction principles of ultrasonic waves, the detector can identify the echo signals generated by defects, thereby judging the internal structural state of the material. The ultrasonic generator is used to generate ultrasonic signals of a certain frequency and transmit them to the aluminum billet to be detected. The signal processing unit can amplify and process the received echo signals to obtain defect data.

[0039] See Figure 6 In this embodiment, the propulsion unit includes a linear motor 1, which includes a bracket 11 that moves along the length direction. The bracket 11 includes a clamping mechanism 12, which is used to clamp the aluminum rod. An aluminum rod inlet 21 is provided at one end of the extrusion die 2, and the aluminum rod inlet 21 is used to insert the aluminum rod. The aluminum rod is heated to a semi-solid state by a heating coil 24 in the cavity 23, and is extruded according to the shape of a battery shell to obtain a first blank. A blank outlet 22 is provided at one end of the extrusion die 2 away from the aluminum rod inlet 21, and a conveying channel 3 is provided between the blank outlet 22 and the ultrasonic detection unit. The conveying channel 3 is used to convey the first blank extruded by the extrusion die to the ultrasonic detection unit. The ultrasonic detection unit includes an ultrasonic detector 4, which can detect and obtain defect data of the extruded first blank. The ultrasonic detection unit is provided with a discharge port 41 at one end away from the conveying channel 3.

[0040] Among them, the length of the conveying channel 3 is 80 cm. After the extruded first blank is cooled through the conveying channel 3, it is convenient for the ultrasonic detection unit to detect the first blank, so as to obtain more accurate defect data.

[0041] Please refer to Figure 2-3 In some embodiments, the controller includes: a data acquisition module: used to collect the propulsion speed of the propulsion unit to extrude the aluminum rod, the temperature data of the first temperature sensor, and the temperature data of the second temperature sensor; a data calculation module: to build an adjustment model according to the propulsion speed of the propulsion unit to extrude the aluminum rod, the temperature data of the first temperature sensor 251, the temperature data of the second temperature sensor 252, and the defect data, and generate adjustment parameters; a control module: to send adjustment parameters to the propulsion unit, the first heating module 241, and the second heating module 242 to adjust the propulsion speed, the heating power of the first heating module 241, and the heating power of the second heating module 242.

[0042] Specifically, building a regulation model includes the following steps: S1: Put the aluminum rod into the propulsion unit at the initial propulsion speed Pushing towards the extrusion die, the initial side wall temperature of the extrusion die cavity is , the initial corner temperature of the extrusion die cavity is , the initial heating power of the first heating module is , the initial heating power of the second heating module is ; S2: The ultrasonic testing unit tests the first blank every 10 seconds to obtain defect data D; S3: Calculate the adjustment parameter according to the defect data D, the expression is: (1) in: For the new advancement speed, is the current advancement speed, is the propulsion speed adjustment coefficient caused by defective data, is the defect data variation, is the new side wall temperature, is the current side wall temperature, is the target molding temperature of the side wall, is the side wall temperature adjustment coefficient, is the new corner temperature, is the current corner temperature, is the target molding temperature of the corners, is the corner temperature adjustment coefficient, is the power of the new first heating module, Heating power for the new second module, is the current power of the first heating module, is the current heating power of the second module, is the power adjustment coefficient of the first heating module according to the defect data, is the power adjustment coefficient of the second heating module according to the defect data.

[0043] It can be understood that the defect data D is generated by the ultrasonic detection unit and is used to evaluate the defect conditions of the first blank, such as the number and depth of cracks. When used, it can be further defined according to the product process requirements. is the average value of the temperature data of the four first temperature sensors, the current corner temperature is the average value of the temperature data of the four second temperature sensors.

[0044] By introducing the defect data variation , can timely track the defects of the first blank in the production process, so as to facilitate subsequent dynamic adjustments, and automatically update the side wall target molding temperature and corner target molding temperature It can provide a better molding temperature reference in a short time, thereby avoiding large temperature fluctuations in the cavity, which leads to large differences in the production quality of the first blank and improves product consistency.

[0045] It is understood that the sidewall target molding temperature and corner target molding temperature They are the cavity side wall temperature and cavity corner temperature when the defect data is the smallest within 1 minute.

[0046] Therefore, based on the above multi-dimensional parameter adjustment for feedback control, the side wall forming temperature, corner forming temperature and advancement speed are controlled separately, which can optimize the advancement speed of the advancement part and the heating power of the first heating module 241 and the second heating module 242 in real time to reduce the defect data D and ensure the quality and stability of the first blank output.

[0047] Among them, the adjustment parameters , , , and Obtained by the following steps: Construct a multiple regression model, the expression is: (2) in is the bias term, is the error term, obtained by the least squares method , , , and ,The above calculation process is carried out in the data operation module, and real ,time calculation is performed by writing a computer program.

[0048] It is understandable that the bias term and error term The results are obtained by fitting the specific experimental data generated during the installation and debugging of the molding system, thereby reducing the error amount in the normal working state of the molding system and improving the accuracy of the feedback control of the molding system.

[0049] The above method can adjust the advancement speed and the temperature of the side wall, i.e., the corner, of the cavity in real time. By continuously processing the updated temperature data and defect data, the defect data D is kept within a lower range, thereby improving the forming quality of the first blank. Therefore, the system can be applied to aluminum alloy materials of various compositions. The advancement speed and cavity temperature can be adjusted automatically according to the above formula without manual intervention, thereby greatly improving production efficiency.

[0050] Specifically, by respectively adjusting the heating power of the first heating module and the second heating module, the forming quality of the first blank at the side walls and corners can be accurately controlled, thereby effectively reducing the number of defects in the first blank and improving the quality of the final aluminum battery shell.

[0051] Among them, changing the cavity temperature is achieved by changing the heating power of the first heating module and the second heating module. Therefore, the first heating module and the second heating module not only change the temperature of the edge of the cavity, but also can indirectly control the temperature inside the cavity. This embodiment couples multiple parameters to adjust and optimize the advancement speed and the power of the first heating module 241 and the second heating module 242 in real time to achieve the purpose of reducing the defects of the first blank.

[0052] Through the above steps, the semi-solid extruded aluminum battery shell thin-wall forming system forms a closed-loop control, and dynamically iterates various adjustment coefficients through a multivariate regression model, so that aluminum ingots of any batch or product number can be put into production without experiments, which shortens the production time and improves production efficiency. In addition, the system can automatically update data in real time to control the defect rate of the first blank at a low level, thereby improving the forming quality of the first blank.

[0053] Therefore, this system can continuously optimize the extrusion strategy according to the defects of the first blank, reduce the occurrence of defects in a targeted manner, and thus improve the comprehensive performance of the finished aluminum battery shell.

[0054] In addition, the model allows dynamic adjustment of operating parameters according to real-time detection data, making the extrusion process more flexible and able to adapt to various production conditions and material properties. and the error term , which enables the model to adapt to and compensate for abnormal fluctuations in historical data and provide more accurate adjustments. Therefore, this method makes the control more stable and reduces production fluctuations caused by sudden defects.

[0055] And by optimizing the propulsion speed and heating power, the power consumption of the linear motor 1 and the heating group 24 can be reduced. In addition, this solution can reduce the scrap rate, thereby reducing the consumption of aluminum rods and has better economy.

[0056] The following are several groups of specific experimental data for producing aluminum battery shells with a battery shell thickness of ∈[0.2,0.4] mm using the semi-solid extrusion aluminum battery shell thin-wall forming system:

[0057] Tensile strength and compressive strength: Characterize the performance of the aluminum battery case during tension and compression, representing its strength.

[0058] Elongation: Indicates the extent to which the aluminum battery shell can stretch before it breaks, and is an important indicator for judging its toughness.

[0059] Corrosion resistance: After being immersed in the corrosive liquid for 24 hours, the depth of the aluminum battery shell where the thickness of the corrosion loss is the greatest. The smaller the value, the better the corrosion resistance.

[0060] Defect rate: It indicates the ratio of defective products to the total number of samples during the sample production process.

[0061] Among them, in the corrosion resistance test, the corrosive medium is 9.5% dilute sulfuric acid.

[0062] The above experimental data show that the tensile strength, compressive strength, elongation and corrosion resistance of battery shells with a thickness of less than 0.4 mm produced using the semi-solid extruded aluminum battery shell thin-wall forming system meet the use scenarios of new energy batteries, and the defect rate is within the normal range.

[0063] Therefore, this system can effectively improve the production quality of thin-walled aluminum battery shells, so that it can be better applied in the field of new energy batteries. By providing thin-walled aluminum battery shells with stable quality, the weight of new energy batteries can be reduced, thereby achieving lightweight new energy equipment.

[0064] It is easy to understand that those skilled in the art can combine, split, reorganize, etc. the embodiments of the present application to obtain other embodiments based on one or several embodiments provided in the present application, and these embodiments do not exceed the protection scope of the present application.

[0065] The present invention and its implementation methods are described schematically above, and the description is not restrictive. The embodiments shown in the embodiments are only part of the implementation methods of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by the embodiments and designs a structure and an implementation method similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for forming a thin-walled semi-solid extruded aluminum battery shell, characterized in that: include: The first forming stage includes: heating and melting the aluminum ingot to obtain aluminum liquid, and pouring the aluminum liquid to obtain an aluminum rod; The second forming stage includes: performing at least one heating step, keeping the aluminum rod in a semi-solid state, cutting it and extruding it into an extrusion die for extrusion forming to obtain a first blank, and heating the extrusion die during the extrusion process to keep the first blank in the extrusion die in a semi-solid state; The third forming stage includes: placing the first blank into a shaping mold to perform a stretching and flattening step to obtain a second blank, performing a sawing step on the second blank, naturally cooling the second blank after the sawing step, and performing cutting with a laser cutting machine in the sawing step; The first post-processing stage includes: performing an aging step on the second blank to obtain a third blank; The second post-processing stage includes: performing an oxidation step on the third blank to obtain a battery shell.

2. The method for forming a thin-walled semi-solid extruded aluminum battery shell according to claim 1, characterized in that: The first forming stage includes: The aluminum ingot is heated to 700°C to obtain aluminum liquid, which is then poured into a casting mold for casting. During the casting process, circulating water is used to cool the casting mold to form the aluminum rod.

3. The method for forming a thin-walled semi-solid extruded aluminum battery shell according to claim 1, characterized in that: The second forming stage includes: The aluminum rod is heated to 400° C. to make it enter a semi-solid state, and then the aluminum rod is cut and extruded into an extrusion die for extrusion molding. During the extrusion process, the cavity of the extrusion die is heated.

4. The method for forming a thin-walled semi-solid extruded aluminum battery shell according to claim 1, characterized in that: The aging step includes placing the second blank into an aging furnace, heating it to 180° C. and maintaining it for 4 hours to eliminate stress concentration of the second blank.

5. The method for forming a thin-walled semi-solid extruded aluminum battery shell according to claim 1, characterized in that: The oxidation step includes an alkaline etching step and an electric oxidation step. In the alkaline etching step, a sodium hydroxide solution is used to remove a thin oxide film on the surface of the third blank. Before the alkaline etching step, water is used to perform a rinse. After the alkaline etching step, water is used to perform a second rinse. After that, the third blank is placed in a water pool and dilute sulfuric acid is added to neutralize the alkaline components on the surface of the third blank.

6. The method for forming a thin-walled semi-solid extruded aluminum battery shell according to claim 5, characterized in that: The electrical oxidation step includes placing the third blank after alkaline etching as an anode in an electrolytic cell, placing 70% sulfuric acid in the electrolytic cell and reacting for 10 minutes to form an oxide film on the surface of the third blank, and the electrical oxidation step is performed 2-3 times.

7. A semi-solid extruded aluminum battery shell thin-wall forming system, characterized in that: include: An extrusion die is provided, wherein the extrusion die is used for extruding a first blank. A propulsion portion is provided at one end of the extrusion die, and the propulsion portion is used for pushing the aluminum rod into the extrusion die. An ultrasonic detection portion is provided at one end of the extrusion die away from the propulsion portion, and the ultrasonic detection portion is used for obtaining defect data of the extruded first blank and uploading it to a controller. A cavity is provided in the extrusion die, and a heating component is provided along the circumference of the cavity. The heating component is used for heating the cavity. The heating component includes a first heating module provided on four sides of the outer wall of the cavity, and a second heating module provided at four corners of the cavity. A first temperature sensor is provided at the first heating module, and a second temperature sensor is provided at the second heating module.

8. The semi-solid extruded aluminum battery shell thin-wall forming system according to claim 7, characterized in that: The controller includes: Data acquisition module: used to collect the advancing speed of the extruded aluminum rod of the advancing part, the temperature data of the first temperature sensor and the temperature data of the second temperature sensor; Data calculation module: constructs an adjustment model according to the advancing speed of the extruded aluminum bar of the advancing part, the temperature data of the first temperature sensor, the temperature data of the second temperature sensor and the defect data, and generates adjustment parameters; Control module: used to send adjustment parameters to the propulsion unit, the first heating module and the second heating module to adjust the propulsion speed, the heating power of the first heating module and the heating power of the second heating module.

9. The semi-solid extruded aluminum battery shell thin-wall forming system according to claim 8, characterized in that: The construction of the mediation model includes the following steps: S1: Put the aluminum rod into the propulsion unit at the initial propulsion speed Pushing towards the extrusion die, the initial side wall temperature of the extrusion die cavity is , the initial corner temperature of the extrusion die cavity is , the initial heating power of the first heating module is , the initial heating power of the second heating module is ; S2: The ultrasonic testing unit tests the first blank every 10 seconds to obtain defect data D; S3: Calculate the adjustment parameter according to the defect data D, the expression is: （1） in: For the new advancement speed, is the current advancement speed, is the propulsion speed adjustment coefficient caused by defective data, is the defect data variation, is the new side wall temperature, is the current side wall temperature, is the target molding temperature of the side wall, is the side wall temperature adjustment coefficient, is the new corner temperature, is the current corner temperature, is the target molding temperature of the corners, is the corner temperature adjustment coefficient, is the power of the new first heating module, Heating power for the new second module, is the current power of the first heating module, is the current heating power of the second module, is the power adjustment coefficient of the first heating module according to the defect data, is the power adjustment coefficient of the second heating module according to the defect data.

10. The semi-solid extruded aluminum battery shell thin-wall forming system according to claim 9, characterized in that: , , , and Obtained by the following steps: Construct a multiple regression model, the expression is: （2） in is the bias term, is the error term, obtained by the least squares method , , , and .

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