Battery casing extrusion process

Abstract

This invention discloses an extrusion process for battery casings, used to manufacture a drawing blank A for a square unequal-wall battery casing. The square unequal-wall battery casing has a thick side, a thin side, and two oppositely distributed equal-walled sides. The wall thickness of the thick side is d1, the wall thickness of the thin side is d2, and the wall thickness of the equal-walled side is d3. The design deformation of the drawing blank A is X%, where X = 10-25. The wall thickness of the thick side of the blank is D1 = (100% + (X - Y)%) * d1 * (100% ± 1%); the wall thickness of the thin side is D2 = (100% + (X - Z)%) * d2 * (100% ± 1%); and the wall thickness of the equal-walled side is D3 = (100% + X%) * d3 * (100% ± 1%). Y = 0.5-5, Z = 0-3. By modifying the blank, the influence of unequal walls on the drawing process is eliminated, making the drawing deformation of the unequal-walled casing more coordinated.

Description

Technical Field

[0001] This invention relates to the field of battery casing manufacturing technology, and in particular to an extrusion process for battery casings. Background Technology

[0002] Aluminum alloy square power battery casings possess excellent corrosion resistance, superior thermal conductivity, and laser weldability. Made of 3003 stainless steel, they also exhibit certain strength and hardness. Therefore, they are widely used in the new energy vehicle sector.

[0003] Currently, there are several manufacturing processes for aluminum alloy square power battery casings: The first is to use 3003 alloy or a modified alloy, roll it into a thin sheet, and then cut and deep-draw it; the second is to use 3003 alloy or a modified alloy, extrude it into a sheet, and then cut and reverse-extrude it; the third is to use 3003 alloy or a modified alloy, and then cold-draw (draw) the hot-extruded billet. The first and second methods are limited in length due to the significantly increased friction and demolding difficulty with deep drawing or reverse extrusion, with a maximum length not exceeding 500mm. The third method has no length limit and is more efficient, making it more widely used.

[0004] However, the current extrusion + cold drawing method is generally used to produce battery casings with equal wall thickness. But for battery casings with unequal wall thickness, due to the different wall thicknesses, the wall thickness setting of the blank obtained by the extrusion process is unreasonable. During the drawing process, it is impossible to achieve coordinated deformation, which makes it impossible to carry out the subsequent cold drawing (drawing) process. Furthermore, the mechanical and structural properties of the finished product are difficult to meet the standards, resulting in a low pass rate. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an extrusion process for battery casings.

[0006] According to a first aspect of the present invention, an extrusion process for a battery casing is used to manufacture a drawing blank A for a square unequal-wall battery casing. The square unequal-wall battery casing has a thick side, a thin side, and two equal-walled sides. The thick side and the thin side are distributed opposite to each other, and the two equal-walled sides are distributed opposite to each other. The side of the drawing blank A corresponding to the thick side is the thick wall of the blank, the side of the drawing blank A corresponding to the thin side is the thin wall of the blank, and the side of the drawing blank A corresponding to the equal-walled sides is the equal-walled side of the blank. The wall thickness of the thick side is d1, the wall thickness of the thin side is d2, and the wall thickness of the equal-walled sides is d3. The extrusion process involves using an extrusion die to extrude an aluminum alloy rod to obtain a blank A; The design deformation of the drawn billet A is X%, where X = 10-25; The wall thickness D1 of the billet with thick walls is calculated as follows: (100% + (XY)%) * d1 * (100% ± 1%). The wall thickness D2 of the thin-walled billet is calculated as follows: (100% + (XZ)%) * d2 * (100% ± 1%). The wall thickness D3 of the billet with equal wall thickness is calculated as follows: D3 = (100% + X%) * d3 * (100% ± 1%). Y=0.5-5, Z=0-3.

[0007] The extrusion process for the battery casing according to embodiments of the present invention has at least the following beneficial effects: by correcting the deformation amount, the influence of unequal wall thickness on the drawing process is eliminated, making the drawing deformation of the unequal wall casing more coordinated.

[0008] According to some embodiments of the present invention, Y = d1 / d2, and when d1 / d2 > 5, Y is 5.

[0009] According to some embodiments of the present invention, Z = d1 / d3, and Z is 3 when d1 / d3 > 3.

[0010] According to some embodiments of the present invention, the drawn blank A in the F state satisfies the following conditions: tensile strength higher than 105 MPa, elongation after fracture greater than 30%, and average grain size less than or equal to 75 μm.

[0011] According to some embodiments of the present invention, the temperature of the aluminum alloy rod is 470°C-510°C.

[0012] According to some embodiments of the present invention, the temperature of the extrusion die is 420°C-440°C.

[0013] According to some embodiments of the present invention, the extrusion speed is not less than 3 mm / s.

[0014] According to some embodiments of the present invention, the output speed of the drawn billet A is not less than 10 m / min.

[0015] According to some embodiments of the present invention, the drawn blank A is cooled, and the cooling rate is controlled so that the straightening amount of the drawn blank A is <0.1%.

[0016] According to some embodiments of the present invention, the extrusion die includes four diversion holes corresponding to the four sides of the drawn blank A, and at least one diversion bridge extending along the extrusion direction is provided in the diversion holes. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the wall thickness distribution of the blank A in an embodiment of the present invention; Figure 2 This is a cross-sectional schematic diagram of a square unequal-walled battery casing according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the extrusion die according to an embodiment of the present invention; Figure 4 This is a front structural diagram of an extrusion die according to an embodiment of the present invention.

[0018] Figure label: Diverting hole 101, diverting bridge 110, billet thick wall 801, billet thin wall 802, billet equal wall 803, thick edge 901, thin edge 902, equal wall edge 903. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0021] In the description of this invention, the use of "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0022] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0023] The extrusion process for a battery casing according to an embodiment of the present invention is used to manufacture a drawing blank A for a square battery casing with unequal wall thickness.

[0024] like Figure 1 , Figure 2As shown, the square unequal wall battery casing has a thick side 901, a thin side 902, and two equal wall sides 903. The thick side 901 and the thin side 902 are relatively distributed, and the two equal wall sides 903 are relatively distributed. The side of the drawn blank A corresponding to the thick side 901 is the blank thick wall 801, the side of the drawn blank A corresponding to the thin side 902 is the blank thin wall 802, and the side of the drawn blank A corresponding to the equal wall side 903 is the blank equal wall 803. The wall thickness of the thick side 901 is d1, the wall thickness of the thin side 902 is d2, and the wall thickness of the equal wall side 903 is d3.

[0025] The extrusion process involves using an extrusion die to extrude an aluminum alloy rod to obtain a blank A; The design deformation of the drawn billet A is X%, where X = 10-25; The wall thickness D1 of the billet thick-walled 801 is calculated as follows: (100% + (XY)%) * d1 * (100% ± 1%). The wall thickness D2 of the thin-walled 802 billet is calculated as follows: D2 = (100% + (XZ)%) * d2 * (100% ± 1%). The wall thickness D3 of the 803 billet with equal wall thickness is calculated as follows: D3 = (100% + X%) * d3 * (100% ± 1%). Y=0.5-5, Z=0-3.

[0026] Specifically, in this invention, the blank A is produced by extruding an aluminum alloy rod using an extrusion die. The blank A is used for drawing (pulling) by the drawing die. Since it is used to draw unequal-wall shells, uneven forces (pressure on the drawing die, friction, etc.) will occur during the drawing process of the blank A. The wall thickness of the blank A is related to the design deformation amount X%, but correction coefficients Y and Z need to be introduced to correct the wall thickness of the blank A in order to eliminate the influence of unequal walls on the drawing process and make the drawing deformation of the unequal-wall shell more coordinated.

[0027] The design deformation of the blank A is usually the deformation of the blank when the relative surfaces are equal in wall thickness, such as the deformation of the blank with equal wall thickness 803. The two equal wall sides 903 corresponding to the blank with equal wall thickness 803 have equal thickness, and the drawing force is easy to achieve balance. Therefore, the wall thickness D3 of the blank with equal wall thickness 803 is the wall thickness of the equal wall side 903, which is d3*(100%+X%), and then multiplied by (100%±1%) for correction (i.e., correction check value ±1%, used to correct the influence of external factors such as room temperature and humidity).

[0028] The thick wall 801 of the billet corresponds to the thick edge 901. Since the thick edge 901 and the thin edge 902 are relatively distributed, a correction coefficient Y needs to be introduced during the drawing process to correct the wall thickness of the drawn billet A, so that the wall thickness D1 of the thick wall 801 of the billet is (100% + (XY)%) * d1, and then multiplied by (100% ± 1%) for correction (i.e., correction check value ± 1%, used to correct the influence of external factors such as room temperature and humidity), so as to eliminate the influence of unequal wall thickness on the drawing process and make the drawing deformation of the unequal wall shell more coordinated.

[0029] The thin wall 802 of the billet corresponds to the thin edge 902. Since the thick edge 901 and the thin edge 902 are relatively distributed, a correction coefficient Z needs to be introduced during the drawing process to correct the wall thickness of the drawn billet A, so that the wall thickness D2 of the thin wall 802 of the billet is (100% + (XZ%)) * d2, and then multiplied by (100% ± 1%) for correction (i.e., correction check value ± 1%, used to correct the influence of external factors such as room temperature and humidity), so as to eliminate the influence of unequal wall thickness on the drawing process and make the drawing deformation of the unequal wall shell more coordinated.

[0030] In some embodiments of the present invention, the design deformation amount X of the billet is designed with reference to the equal wall edge. Therefore, in the present invention, the wall thickness D3 of the equal wall 803 of the billet is the wall thickness of the equal wall edge 903, which is d3*(100%+X%) multiplied by the correction check value. The wall thickness of the billet corresponding to the unequal wall edge needs to be corrected by introducing correction parameters.

[0031] In some embodiments of the present invention, Y = d1 / d2. When d1 / d2 > 5, Y is 5. When d1 / d2 is less than 0.5, Y is 0.5. By quantifying the correction parameter Y by the ratio of the wall thickness d1 of the thick side 901 to the wall thickness d2 of the thin side 902, the requirements for drawing the thick side 901 of the square unequal wall battery case can be met.

[0032] It is conceivable that in some embodiments of the present invention, the correction effect can be achieved when the correction parameter Y is 0.5, 1, 3, or 5, so that the thick edge 901 has a better drawing effect.

[0033] In some embodiments of the present invention, Z = d1 / d3. When d1 / d3 > 3, Z is 3. The parameter Z is quantified and corrected by the ratio of the wall thickness d1 of the thick side 901 to the wall thickness d3 of the equal side 903, which can meet the requirements for the drawing of the thick side 901 of the square unequal wall battery case.

[0034] It is conceivable that in some embodiments of the present invention, the correction effect can be achieved when the correction parameter Z is 0, 1, or 3, so that the thin edge 902 has a better drawing effect.

[0035] It is conceivable that, in some embodiments of the present invention, the drawn blank A in the F state meets the following requirements: tensile strength higher than 105 MPa, elongation after fracture greater than 30%, and average grain size less than or equal to 75 μm. Due to the small cross-sectional area, the specific drawing process of the unequal-walled square battery case requires a high degree of cold drawing hardening effect and has certain special mechanical property requirements for the F state material. The aluminum alloy drawn blank A with the above parameters can meet the drawing requirements of the unequal-walled square battery case.

[0036] It is conceivable that, in some embodiments of the present invention, the temperature of the aluminum alloy rod is 470℃-510℃, so that the aluminum alloy rod has a certain deformation capacity to meet the requirements of hot extrusion processing.

[0037] Specifically, temperatures of 470℃, 490℃, and 510℃ for aluminum alloy rods can all meet the extrusion requirements of the blanks for square unequal wall battery cases.

[0038] It is conceivable that, in some embodiments of the present invention, the temperature of the extrusion die is 420°C-440°C. Selecting this temperature is beneficial for controlling the coarse grain layer of this type of product, so that the product has good mechanical properties.

[0039] In some embodiments of the present invention, the extrusion speed is not less than 3 mm / s in the extrusion process to avoid a large temperature drop in the aluminum alloy material during the extrusion process, while ensuring production efficiency.

[0040] In some embodiments of the present invention, in the extrusion process, the output speed of the drawn billet A is not less than 10m / min, that is, the traction speed of the drawn billet A is not less than 10m / min, so as to avoid a large temperature drop in the aluminum alloy material during the extrusion process and at the same time ensure production efficiency.

[0041] In some embodiments of the present invention, the drawn blank A is cooled, and the cooling rate is controlled so that the straightening amount of the drawn blank A is <0.1%.

[0042] Specifically, the extruded blank A is cooled by a gentle breeze, with no limit on the cooling rate as long as it does not deform, and the straightening amount is limited to <0.1%.

[0043] like Figure 3 , Figure 4 As shown, in some embodiments of the present invention, the extrusion die includes four diversion holes 101 corresponding to the four sides of the drawn blank A. At least one diversion bridge 110 extending along the extrusion direction is provided in the diversion hole 101. By configuring the diversion bridge 110, the material flow can be guided, reducing turbulence, pressure imbalance and other situations, and improving extrusion stability and the quality of the extruded product.

[0044] Specifically, when the aluminum alloy rod is extruded through the flow divider bridge 110, the flow divider bridge 110 extending along the extrusion direction can guide the material, reduce the occurrence of the material flow direction deviating from the extrusion direction, balance the extrusion pressure, and make the material distribution uniform, so that incomplete welding, substandard thickness and other problems are less likely to occur, thus improving the product qualification rate.

[0045] In some embodiments of the present invention, the diversion bridge 110 has a flat structure to achieve a better flow guiding effect.

[0046] Specifically, the aluminum alloy conveying direction is from front to back, and the diversion bridge 110 has a teardrop-shaped structure that is wider at the front and narrower at the back.

[0047] In some embodiments of the present invention, each diversion hole 101 is provided with a diversion bridge 110. The diversion bridge 110 is disposed in the middle of the diversion hole 101 and extends along the extrusion direction. By diverting and guiding the flow in the middle through a single diversion bridge 110, the material flow can be guided better, and the impact on the material flow rate and pressure can be reduced.

[0048] Specifically, in practical applications, the cross-sectional area and flow rate of the diversion orifice 101 need to be set according to the shape of the extrusion, and should not be too large or too small. Adding a single diversion bridge 110 can reduce the impact on the original diversion orifice.

[0049] Of course, in the specific implementation process, if the diversion hole 101 is large, two or more diversion bridges 110 can be configured as needed, which will not be described in detail here.

[0050] Of course, the present invention is not limited to the above-described embodiments. Those skilled in the art can make equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. An extrusion process for a battery casing, characterized in that, A blank A is used to manufacture a square unequal wall battery case. The square unequal wall battery case has a thick side (901), a thin side (902) and two equal wall sides (903). The thick side (901) and the thin side (902) are distributed opposite to each other, and the two equal wall sides (903) are distributed opposite to each other. The side of the blank A corresponding to the thick side (901) is the blank thick wall (801), the side of the blank A corresponding to the thin side (902) is the blank thin wall (802), and the side of the blank A corresponding to the equal wall side (903) is the blank equal wall (803). The wall thickness of the thick side (901) is d1, the wall thickness of the thin side (902) is d2, and the wall thickness of the equal wall side (903) is d3. The extrusion process involves using an extrusion die to extrude an aluminum alloy rod to obtain a blank A; The design deformation of the drawn billet A is X%, where X = 10-25; The wall thickness D1 of the billet thick wall (801) is (100% + (XY)%) * d1 * (100% ± 1%). The wall thickness D2 of the thin-walled billet (802) is calculated as (100% + (XZ)%) * d2 * (100% ± 1%). The wall thickness D3 of the billet with equal wall thickness (803) is (100% + X%) * d3 * (100% ± 1%). Y=0.5-5, Z=0-3; Y = d1 / d2, and when d1 / d2 > 5, Y is 5; Z = d1 / d3, and Z is 3 when d1 / d3 > 3; The drawn billet A in the F state meets the following requirements: tensile strength higher than 105 MPa, elongation after fracture greater than 30%, and average grain size less than or equal to 75 μm.

2. The extrusion process for the battery casing according to claim 1, characterized in that, The temperature of the aluminum alloy rod is 470℃-510℃.

3. The extrusion process for the battery casing according to claim 1, characterized in that, The temperature of the extrusion die is 420℃-440℃.

4. The extrusion process for the battery casing according to claim 1, characterized in that, The extrusion speed shall not be less than 3 mm / s.

5. The extrusion process for the battery casing according to claim 1, characterized in that, The output speed of the blank A drawing is not less than 10m / min.

6. The extrusion process for the battery casing according to claim 1, characterized in that, The drawn billet A is cooled, and the cooling rate is controlled so that the straightening amount of the drawn billet A is less than 0.1%.

7. The extrusion process for the battery casing according to claim 1, characterized in that, The extrusion die includes four diversion holes (101) corresponding to the four sides of the blank A, and at least one diversion bridge (110) extending along the extrusion direction is provided in each diversion hole (101).

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