Method for forming integrated explosion-proof valve on battery shell

Abstract

The invention discloses a method for forming an integrated anti-explosion valve on a battery shell. The method comprises the following steps: taking an aluminum alloy battery shell; sleeving and fixing the battery shell on a die core of a stamping station; forming an integrated explosion-proof valve in an explosion-proof valve area of the battery shell by adopting a punch through a punching process; and taking down the battery shell from the mold core. According to the invention, the battery shell made of an aluminum alloy material is directly stamped to form the integrated explosion-proof valve, so that the step of integrally thinning the explosion-proof valve area is omitted, and a compact organization structure is prevented from being formed in the explosion-proof valve area, so that the valve opening pressure control of the integrated explosion-proof valve is more accurate; and the process method is simple, mass production can be realized, and the production cost is relatively low.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of secondary batteries, and particularly relates to a method for forming an integrated explosion-proof valve in a battery shell. BACKGROUND

[0002] Secondary batteries are widely used in the field of new energy as the power source of electric vehicles and other equipment. At present, the shell of the secondary battery is mostly made of aluminum alloy or stainless steel material. A relief hole is generally arranged on the top cover of the battery, and an explosion-proof valve is welded at the relief hole to facilitate the release of internal pressure when the internal pressure of the battery is large, so as to prevent safety accidents such as explosion of the battery. However, this method of manufacturing the explosion-proof valve is relatively complicated, and has high requirements on the welding process, which increases the production cost; and is not conducive to the integrity of the battery shell.

[0003] At present, there is also a method of forming an explosion-proof notch as an integrated explosion-proof valve by laser etching or stamping. However, the laser etching method needs to be etched multiple times along the predetermined path, which is low in efficiency; and the stainless steel material is relatively hard, which is generally not suitable for stamping. The aluminum alloy material needs to be thinned as a whole in the explosion-proof valve area by extrusion or stamping first, and then stamped to form a notch after forming a relatively dense organizational structure; but the implementation of the above process is difficult and mass production is not easy to achieve. And the material accumulation is formed on both sides of the explosion-proof valve area in the first extrusion or stamping process, which affects the overall appearance of the battery shell, and the extrusion and stamping areas cause material accumulation, thereby accumulating a large stress, so that the burst pressure value of the explosion-proof valve is difficult to accurately control, and the burst pressure value of the explosion-proof valve fluctuates greatly under the same manufacturing process. SUMMARY

[0004] In view of the above deficiencies of the prior art, the technical problem to be solved by the present application is to provide a method for forming an integrated explosion-proof valve in a battery shell.

[0005] To solve the above technical problems, the present application provides the following technical solutions: A method for forming an integrated explosion-proof valve in a battery shell, comprising the following steps: S100, taking an aluminum alloy battery shell; S200, fixing the battery shell on the mold core of the stamping station; S300, forming an integrated explosion-proof valve in the explosion-proof valve area of the battery shell by stamping process using a punch; S400, taking the battery shell from the mold core.

[0006] Further, the integral explosion-proof valve comprises stamping notches forming a closed figure and a stretching area inside the closed figure; in the S300 step, the stamping forms the stamping notches while making the stretching area protrude outwardly from the outer surface of the battery shell or making the stretching area recess inwardly and protrude from the inner surface of the battery shell.

[0007] Further, the position of the stamping notches corresponding to the area of the explosion-proof valve on the punch is provided with a convex rib, the height of the convex rib is matched with the depth of the stamping notches; the enclosed area of the convex rib is provided with a first stretching part.

[0008] Further, the mold core comprises a strip-shaped part and a supporting part, the width of the strip-shaped part is matched with the width of the inner cavity of the battery shell; in the S200 step, the battery shell is sleeved and installed on the strip-shaped part, and the supporting part is used as a blocking part when the battery shell is installed; then, the battery shell is fixed on the strip-shaped part by a pressing plate; the pressing plate is provided with a through hole corresponding to the position of the strip-shaped part corresponding to the area of the explosion-proof valve; the strip-shaped part is provided with a matched second stretching part corresponding to the position of the first stretching part.

[0009] Further, the stretching area protrudes outwardly from the outer surface of the battery shell; the first stretching part comprises a first recess, and the second stretching part comprises a first convexity matched with the shape of the first recess.

[0010] Further, the stretching area recesses inwardly and protrudes from the inner surface of the battery shell; the first stretching part comprises a second convexity, and the second stretching part comprises a second recess matched with the shape of the second convexity.

[0011] Further, the residual thickness of the battery shell at the stamping notches is 0.08mm-0.12mm.

[0012] Further, the stamping notches comprise a first horizontal notch, two second horizontal notches, two first connecting notches and two second connecting notches, the first horizontal notch is located at the middle of the area of the explosion-proof valve, the two second horizontal notches are symmetrically arranged on the two sides of the first horizontal notch, and the second horizontal notches are parallel to the first horizontal notch; the length of the second horizontal notch is greater than the length of the first horizontal notch, the first ends of the two second horizontal notches are connected with the first end of the first horizontal notch through a first connecting notch respectively, and the second ends of the two second horizontal notches are connected with the second end of the first horizontal notch through a second connecting notch respectively.

[0013] Further, the wall thickness of the battery shell is 0.3mm-0.8mm.

[0014] Further, in the S300 step, the pressure used in the stamping process is 70 tons-90 tons.

[0015] In this invention, the battery casing made of aluminum alloy is directly formed into an integrated explosion-proof valve through stamping, eliminating the need for overall thinning of the explosion-proof valve area and avoiding the formation of a dense microstructure in the explosion-proof valve area. Furthermore, while stamping creates the stamping marks, the stretching effect on the stretching area absorbs the aluminum alloy material diffusing outward from the stamping marks, preventing aluminum alloy material accumulation. This also reduces stress accumulation caused by stamping, resulting in more precise control of the opening pressure of the integrated explosion-proof valve. In addition, the process method of this embodiment is simple, easy to mass-produce, and has low production costs. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of an embodiment of the method for forming an integrated explosion-proof valve in a battery casing according to the present invention.

[0017] Figure 2 This is a schematic diagram showing how the battery casing is fitted and fixed onto the mold core.

[0018] Figure 3 This is a structural diagram of an integrated explosion-proof valve.

[0019] Figure 4 This is a bottom view of the punch.

[0020] Figure 5 This is a top view of the mold core.

[0021] Figure 6 When the first stretched part is the first concave part Figure 4 A schematic cross-sectional view along the AA direction.

[0022] Figure 7 When the second stretching part is the second convex hull Figure 5 A cross-sectional diagram along the BB direction.

[0023] Figure 8 This is a schematic diagram of the battery casing after stamping.

[0024] Figure 9 for Figure 8 Top view.

[0025] Figure 10 When the stretching area protrudes outward from the outer surface of the battery casing Figure 9 A schematic cross-sectional view along the CC direction.

[0026] Figure 11 When the first stretching part is the first convex hullFigure 4 A schematic cross-sectional view along the AA direction.

[0027] Figure 12 When the second stretched part is the second concave part Figure 5 A cross-sectional diagram along the BB direction.

[0028] Figure 13 When the stretched area is concave inward and convex outward from the inner surface of the battery casing Figure 9 A schematic cross-sectional view along the CC direction.

[0029] The diagrams in the instruction manual are labeled as follows: Battery casing - 100; Wide side - 110; Narrow side - 120; Integrated explosion-proof valve - 200; Stamping marks - 210; First horizontal marks - 211; Second horizontal marks - 212, 213; First connecting marks - 214, 215; Second connecting marks - 216, 217; Stretching area - 220, 221, 222; Mold core - 300; Strip section - 310; Support section - 320; Second stretching section - 330; Second convex bump - 331; Second recess - 332; Pressure plate - 400; Through hole - 410; Punch - 500; Protruding ridge - 510; First stretching section - 520; First recess - 521; First convex bump - 522. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0031] Example 1 Please see Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the method for forming an integrated explosion-proof valve in a battery casing according to the present invention. The method for forming an integrated explosion-proof valve in a battery casing according to this embodiment includes the following steps: S100. Take a battery casing 100 made of aluminum alloy. In this embodiment, the battery casing 100 is made of aluminum alloy, which can reduce the stress generated during stamping. Furthermore, aluminum alloy is easier to stretch, thus the stress generated during stamping can be better eliminated through the stretching action during the stamping process. In contrast, battery casings made of materials such as stainless steel are harder and not easy to stretch during the stamping process. Moreover, the stress generated during stamping is also greater, which can make it difficult to control the opening pressure of the explosion-proof valve.

[0032] In this embodiment, the battery casing 100 is a rectangular cylindrical structure, including two wide sides 110 and two narrow sides 120. The wall thickness d1 of the battery casing 100 is 0.3mm to 0.8mm; for example, it can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm or 0.8mm.

[0033] S200, please refer to Figure 2 The battery casing 100 is fitted and fixed onto the die core 300 at the stamping station. In this embodiment, the die core 300 includes a strip-shaped portion 310 and a support portion 320, wherein the width of the strip-shaped portion 310 (i.e., the width of the strip-shaped portion 310 in...) Figure 5 The dimension in the y-axis direction) and the inner cavity width of the battery housing 100 (i.e., the inner cavity of the battery housing 100 in the y-axis direction) Figure 8 and Figure 9 The dimensions (in the y-axis direction) are compatible. In this step, the battery housing 100 is inserted through one end of the strip portion 310 and fitted onto the strip portion 310. The support portion 320 connected to the first end of the strip portion 310 serves as a blocking part when installing the battery housing 100, and the pressure plate 400 is used to press and fix the battery housing 100 onto the strip portion 310. The pressure plate 400 is provided with a through hole 410 corresponding to the position of the explosion-proof valve area of ​​the strip portion 310, so that the punch 500 can pass through the through hole 410 to punch the battery housing 100 to form the explosion-proof valve.

[0034] S300: A punch 500 is used to form an integrated explosion-proof valve 200 in the explosion-proof valve area of ​​the battery casing 100 (i.e., the pre-determined area where an integrated explosion-proof valve 200 needs to be formed) through a stamping process. The pressure used in the stamping process is generally 70 to 90 tons, and in this embodiment, 80 tons is preferred. The integrated explosion-proof valve 200 may include a stamping notch 210 forming a closed pattern and a stretching region 220 located inside the closed pattern. The residual thickness d2 of the battery casing 100 at the stamping notch 210 is generally 0.08 mm to 0.12 mm. For example, the residual thickness d2 at the stamping notch 210 can be 0.08 mm, 0.09 mm, 0.10 mm, 0.11 mm, or 0.12 mm. At this time, the opening pressure corresponding to the integrated explosion-proof valve 200 is 0.9 MPa to 1.0 MPa. The remaining thickness d2 of the stamping mark 210 is defined as the remaining thickness of the battery casing 100 at the stamping mark 210; the specific value of d2 can be set as needed.

[0035] In this embodiment, while stamping to form the stamping mark 210, the stretching area 220 is also made to protrude outward from the outer surface of the battery casing 100. This allows the deformation of the stretching area 220 to absorb the aluminum alloy material that diffuses outward from the stamping mark 210. This avoids the accumulation of material on both sides of the stamping mark 210 after stamping, which would generate large stress and affect the opening pressure of the integrated explosion-proof valve 200, causing a large error in the opening pressure of the integrated explosion-proof valve 200.

[0036] Please see Figure 3 In this embodiment, the stamping notch 210 includes a first horizontal notch 211, two second horizontal notches (212, 213), two first connecting notches (214, 215), and two second connecting notches (216, 217). The first horizontal notch 211 is located in the middle of the explosion-proof valve area, and the two second horizontal notches (212, 213) are symmetrically arranged on both sides of the first horizontal notch 211, and the second horizontal notches (212, 213) are parallel to the first horizontal notch 211. The length of the second horizontal scribing marks (212, 213) is greater than the length of the first horizontal scribing mark 211. The first ends of the two second horizontal scribing marks (212, 213) are respectively connected to the first end of the first horizontal scribing mark 211 through a first connecting scribing mark (214, 215); the second ends of the two second horizontal scribing marks (212, 213) are respectively connected to the second end of the first horizontal scribing mark 211 through a second connecting scribing mark (216, 217), thereby forming two closed shapes.

[0037] In this embodiment, the second horizontal notch 212, the first connecting notch 214, and the second connecting notch 216, together with the first horizontal notch 211, form a first closed shape, within which a stretching region 221 is formed. The second horizontal notch 213, the first connecting notch 215, and the second connecting notch 217, together with the first horizontal notch 211, form a second closed shape, within which a stretching region 222 is formed. In this embodiment, the stamping notch 210, with the above structure, can form two valve-opening regions, thereby reducing the error in the valve-opening pressure of the integrated explosion-proof valve 200. Of course, the stamping notch 210 can also adopt other shapes.

[0038] Please see Figure 4 The punch 500 has a raised ridge 510 at the position corresponding to the stamping mark 210 in the explosion-proof valve area. The height of the raised ridge 510 is adapted to the depth of the stamping mark 210. A first stretching portion 520 is provided within the enclosed area of ​​the raised ridge 510. Please refer to [link / reference]. Figure 5 The strip portion 310 is provided with a matching second stretch portion 330 at the position corresponding to the first stretch portion 520.

[0039] Please seeFigure 6 and Figure 7 To ensure that the stretching regions 221 and 222 protrude outward from the outer surface of the battery casing 100 during the stamping process to form the stamping mark 210, in this embodiment, the first stretching portion 520 of the punch 500 includes two first recesses 521, and the second stretching portion 330 of the strip-shaped portion 310 includes two first protrusions 522 that are adapted to the shape of the first recesses 521. Thus, the cooperation of the two first recesses 521 and the two first protrusions 522 causes the stretching regions 221 and 222 to protrude outward from the outer surface of the battery casing 100 during the stamping process. The stretching action on the material of the stretching regions 221 and 222 absorbs the aluminum alloy material diffusing outward from the stamping mark 210, preventing material accumulation and deformation on both sides of the stamping mark 210, and also releasing the stress accumulated in the relevant area of ​​the stamping mark 210 during the stamping process.

[0040] S400, please refer to Figure 8 , Figure 9 and Figure 10 The battery casing 100 is removed from the mold core 300, resulting in a battery casing 100 with an integrated explosion-proof valve 200. Figure 10 As can be seen, after stamping, the stretching areas 221 and 222 protrude outward from the outer surface of the battery casing 100, and no aluminum alloy material accumulation deformation is formed on both sides of the first horizontal notch 211, the second horizontal notch 212, and the second horizontal notch 213; of course, no aluminum alloy material accumulation deformation is formed at the other stamping notches 210 either.

[0041] In this embodiment, the battery casing 100 made of aluminum alloy facilitates the stamping and stretching deformation of the integrated explosion-proof valve 200. Directly forming the integrated explosion-proof valve 200 through stamping eliminates the need for overall thinning of the explosion-proof valve area, avoiding the formation of a dense microstructure in that area. Furthermore, while forming the stamping notches 210, the stretching effect on the stretching area 220 absorbs the aluminum alloy material diffusing outwards from the stamping notches 210, preventing aluminum alloy material accumulation. This also reduces stress accumulation caused by stamping, resulting in more precise control of the opening pressure of the integrated explosion-proof valve 200. In addition, the process method of this embodiment is simple, can achieve mass production, and has low production costs, making it promising for broad applications.

[0042] Example 2 The difference in this embodiment is that the structure of the first stretching portion 520 of the punch 500 and the structure of the second stretching portion 330 of the strip portion 310 are different from those in Embodiment 1; thus, while forming the stamping mark 210 in step S300, the stretching region 220 is also made to be concave inward and protrude from the inner surface of the battery casing 100. That is, the protruding direction of the stretching regions 221 and 222 after stamping is different from that in Embodiment 1.

[0043] Please see Figure 11 and Figure 12 In this embodiment, the first stretching portion 520 of the punch 500 includes two second protrusions 321, and the second stretching portion 330 of the strip-shaped portion 310 includes two second recesses 322 that are adapted to the shape of the second protrusions 321. Thus, through the cooperation of the two second protrusions 321 and the two second recesses 322, the stretching regions 221 and 222 are recessed inward and protruded outward from the inner surface of the battery casing 100 during the stamping process. For the structure of the stretching regions 221 and 222 in the stamped battery casing 100, please refer to [reference needed]. Figure 13 The method described above can also absorb the aluminum alloy material diffused outward from the stamping mark 210 by stretching the material of the stretching region 221 and the stretching region 222, so that no material accumulation deformation will form on both sides of the stamping mark 210, and the stress accumulated in the stamping region can also be released.

[0044] In this embodiment, the step of thinning the entire explosion-proof valve area is also omitted, which reduces stress accumulation caused by stamping and makes the opening pressure control of the integrated explosion-proof valve 200 more precise. Furthermore, the process method in this embodiment is basically the same as in Embodiment 1, enabling mass production at a lower cost.

[0045] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. A method for forming an integrated explosion-proof valve in a battery casing, characterized in that, Includes the following steps: S100, Take an aluminum alloy battery casing; S200. The battery casing is fitted and fixed onto the die core of the stamping station; S300: An integrated explosion-proof valve is formed in the explosion-proof valve area of ​​the battery casing by a punching process. S400, Remove the battery casing from the mold core.

2. The method for forming an integrated explosion-proof valve in a battery casing as described in claim 1, characterized in that: The integrated explosion-proof valve includes a stamping mark forming a closed pattern and a stretching area located inside the closed pattern; in step S300, while stamping to form the stamping mark, the stretching area is also made to protrude outward from the outer surface of the battery casing, or the stretching area is made to be recessed inward and protrude outward from the inner surface of the battery casing.

3. The method for forming an integrated explosion-proof valve in a battery casing as described in claim 2, characterized in that: The punch head is provided with a raised ridge at the position where the stamping mark is formed in the explosion-proof valve area, and the height of the raised ridge is adapted to the depth of the stamping mark; a first stretching part is provided in the enclosed area of ​​the raised ridge.

4. The method for forming an integrated explosion-proof valve in a battery casing as described in claim 3, characterized in that: The mold core includes a strip-shaped portion and a support portion. The width of the strip-shaped portion is adapted to the inner cavity width of the battery housing. In step S200, the battery housing is sleeved onto the strip-shaped portion, and the support portion serves as a blocking portion when installing the battery housing. Then, a pressure plate is used to press and fix the battery housing onto the strip-shaped portion. The pressure plate is provided with a through hole corresponding to the position of the explosion-proof valve area of ​​the strip-shaped portion. A matching second tension portion is provided at the position of the first tension portion of the strip-shaped portion.

5. The method for forming an integrated explosion-proof valve in a battery casing as described in claim 4, characterized in that: The stretching region protrudes outward from the outer surface of the battery casing; the first stretching portion includes a first recess, and the second stretching portion includes a first convex bulge adapted to the shape of the first recess.

6. The method for forming an integrated explosion-proof valve in a battery casing as described in claim 4, characterized in that: The stretching region is recessed inward and protrudes from the inner surface of the battery casing; the first stretching portion includes a second convex bulge, and the second stretching portion includes a second recess that matches the shape of the second convex bulge.

7. The method for forming an integrated explosion-proof valve in a battery casing as described in claim 2, characterized in that: The residual thickness of the battery casing at the stamping marks is 0.08mm to 0.12mm.

8. The method for forming an integrated explosion-proof valve in a battery casing as described in any one of claims 2 to 7, characterized in that: The stamping marks include a first horizontal mark, two second horizontal marks, two first connecting marks, and two second connecting marks. The first horizontal mark is located in the middle of the explosion-proof valve area. The two second horizontal marks are symmetrically arranged on both sides of the first horizontal mark and are parallel to the first horizontal mark. The length of the second horizontal mark is greater than the length of the first horizontal mark. The first ends of the two second horizontal marks are respectively connected to the first ends of the first horizontal mark through a first connecting mark, and the second ends of the two second horizontal marks are respectively connected to the second ends of the first horizontal mark through a second connecting mark.

9. The method for forming an integrated explosion-proof valve in a battery casing as described in claim 1, characterized in that: The wall thickness of the battery casing is 0.3mm to 0.8mm.

10. The method for forming an integrated explosion-proof valve in a battery casing as described in claim 1, characterized in that: In step S300, the stamping process uses a pressure of 70 to 90 tons.

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