Explosion-proof steel shell and manufacturing method thereof

Abstract

The present invention discloses an explosion-proof steel shell and a manufacturing method thereof, wherein the explosion-proof steel shell comprises a shell with at least one end open and a cover plate blocking the open end of the shell, explosion-proof notches are formed on the surface of the cover plate or the shell, and flange structures adapted to the inner wall of the shell are formed on the four edges of the cover plate. The present invention adopts the method of integrally stamping the explosion-proof valve with the cover plate or the shell, eliminating the need to assemble and weld the explosion-proof valve, reducing the process steps, simplifying the production process, improving the production efficiency and the yield rate, and greatly reducing the thickness of the cover plate, making the cover plate easier to stamp.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and in particular to an explosion-proof steel shell and a manufacturing method thereof. Background Art

[0002] The stainless steel shell is welded from stainless steel into a square shell with two ends open, and a stainless steel bottom cover is welded at one end to form the shell of the secondary battery. The battery inside the sealed shell may generate high-temperature and high-pressure gas during use, which may cause the shell to explode. In order to prevent the shell from exploding, it is necessary to release the pressure of the high-temperature and high-pressure gas generated inside the shell to prevent explosion. The conventional method is to stamp or CNC-process an explosion-proof countersunk hole for installing an explosion-proof valve on the bottom cover of the shell, and then weld the explosion-proof valve sheet on the explosion-proof countersunk hole. There are many processes. At the same time, in order to ensure the strength and squareness of the bottom cover, In order to weld the explosion-proof valve plate smoothly at the explosion-proof countersunk hole, the cover plate needs to be thicker, usually about 1.5mm. Since the hardness of stainless steel is as high as 150-180HV, the stamping and thinning process is difficult. The thicker the cover plate, the more difficult it is to stamp, which will greatly shorten the stamping life of the mold. Moreover, after actual stamping, arc transitions are formed at the junction of each step, and the corners cannot be cleared. It is easy to interfere with the subsequent installation of the explosion-proof valve plate, making it difficult to install the explosion-proof valve plate and the welding yield is low. The cost of CNC milling the steps of the explosion-proof countersunk hole is high, the production efficiency is slow, and it is not suitable for mass production. Summary of the invention

[0003] In view of this, an object of the present invention is to provide an explosion-proof steel shell to solve the problems of multiple processes, thick materials, difficult assembly and welding, and low welding yield in the prior art for manufacturing explosion-proof steel shells.

[0004] To achieve the above-mentioned purpose, an explosion-proof steel shell of the present invention comprises a shell with at least one end open and a cover plate that blocks the open end of the shell, explosion-proof notches are formed on the surface of the cover plate, and flange structures that are compatible with the inner wall of the shell are formed on the four edges of the cover plate.

[0005] In the above scheme, the explosion-proof structure can be directly formed on the surface of the cover plate or on the surface of the shell by stamping or milling. There is no need to process explosion-proof countersunk holes on the cover plate and then weld explosion-proof plates on the explosion-proof countersunk holes. Therefore, the process is simple. Since there is no need to weld explosion-proof plates, the thickness of the cover plate can be greatly reduced, making the cover plate easier to cut and stamp. When the pressure inside the shell increases to the set value, the cover plate or the shell will crack at the explosion-proof structure to release pressure, thereby achieving the purpose of effective explosion-proof. The flange structure has a certain elasticity and is adapted to the inner wall of the shell, which makes it convenient to assemble and weld the cover plate and the shell.

[0006] Furthermore, the explosion-proof structure includes an explosion-proof notch arranged on the surface of the cover plate or the shell, and the residual thickness of the explosion-proof notch gradually increases or decreases from one end of the explosion-proof notch to the other opposite end. The residual thickness of the thinner end of the explosion-proof notch is 0.07mm~0.09mm, and the residual thickness of the thicker end of the explosion-proof notch is 0.12mm~0.14mm.

[0007] The residual thickness of the explosion-proof notch changes gradually, so that each time a burst pressure relief occurs, the cracking starts from the position where the residual thickness of the explosion-proof notch is the smallest. When the residual thickness of the explosion-proof notch is equal, the position where the explosion-proof notch starts to crack each time a burst pressure relief occurs cannot be predicted. In comparison, the burst stability and controllability of this scheme are stronger.

[0008] Furthermore, the cover plate is integrally stamped from a stainless steel plate with a thickness of 0.15 mm to 0.35 mm, the shell is formed by bending and welding a stainless steel plate with a thickness of 0.15 mm to 0.25 mm, and the cover plate is sealed and welded to the shell.

[0009] Furthermore, the flange structure includes a downward flange formed along the four edges of the cover plate, the outer wall of the flange is adapted to the inner wall of the shell, the height of the flange is 0.5mm~0.7mm, and the upper surface of the cover plate is 0.2mm~0.4mm higher than the upper end surface of the shell to form a welding step between the upper end surface of the shell and the upper surface of the cover plate.

[0010] Furthermore, the flange structure includes an upwardly opening U-shaped flange formed along the four edges of the cover plate, the outer wall of the U-shaped flange is adapted to the inner wall of the shell, the height of the U-shaped flange is 0.6mm~1.0mm, and the upper end surface of the U-shaped flange is 0.15mm~0.4mm higher than the upper end surface of the shell to form a welding step between the upper end surface of the shell and the upper surface of the cover plate.

[0011] Furthermore, the flange structure includes an upwardly opening U-shaped flange formed along the four edges of the cover plate, the outer wall of the U-shaped flange is adapted to the inner wall of the shell, the height of the U-shaped flange is 0.6mm~1.0mm, and the upper end surface of the U-shaped flange is flush with the upper end surface of the shell.

[0012] Furthermore, the flange structure includes an upwardly opening U-shaped flange formed along the four edges of the cover plate, the outer wall of the U-shaped flange is adapted to the inner wall of the shell, the height of the U-shaped flange is 0.6mm~1.0mm, and the upper end surface of the U-shaped flange is provided with a lap edge extending in a horizontal direction, the lower surface of the lap edge is fitted with the upper end surface of the shell, and the outer peripheral surface of the lap edge is flush with the outer wall of the shell.

[0013] Furthermore, the projection of the trajectory of the explosion-proof notch on the surface of the cover plate is an elliptical, circular, square or other closed curve; or

[0014] The projection of the trajectory of the explosion-proof notch on the surface of the shell is an elliptical, circular, square or other closed curves.

[0015] Further, the explosion-proof structure is arranged on the upper surface or the lower surface of the cover plate; or

[0016] The explosion-proof structure is arranged on the outer wall or the inner wall of the shell.

[0017] Furthermore, the present invention also provides a method for manufacturing an explosion-proof steel shell, comprising the following steps:

[0018] S1. Making the shell:

[0019] S101, blanking, punching or cutting out the sheet size when the shell is unfolded. In this step, the sheet can be punched or cut out of a stainless steel sheet with a thickness of 0.15 mm to 0.25 mm, preferably a 0.2 mm stainless steel sheet;

[0020] S102, bending, bending the sheet obtained in step S101 according to the wide side size and narrow side size of the shell to form a cylindrical body with a joint seam;

[0021] S103, welding, continuously welding the joint seams of the cylinder in step S102 to form a cylinder with closed side walls;

[0022] S2. Making the cover plate:

[0023] S201, blanking, punching or cutting out the sheet material size when the cover plate is unfolded. In this step, the sheet material can be punched or cut out of a stainless steel sheet material with a thickness of 0.15 mm to 0.35 mm;

[0024] S202, punching out explosion-proof notches with residual thickness gradient characteristics on the surface of the sheet material in step S201. In this step, the explosion-proof notches may be punched on the upper surface of the sheet material or on the lower surface of the sheet material;

[0025] S203, punching out flange structures on the four edges of the sheet obtained in step S202;

[0026] S3, welding the shell and the cover plate: after the cover plate obtained in step S2 is assembled with the open end of the shell obtained in step S1, the cover plate and the shell are welded together to obtain an explosion-proof steel shell assembly.

[0027] The present invention adopts the method of integrally stamping the explosion-proof valve and the cover plate, eliminating the need to assemble and weld the explosion-proof valve, reducing process steps, simplifying the production process, and improving production efficiency and yield rate; the thickness of the cover plate is greatly reduced, making the cover plate easier to stamp; the residual thickness of the notch used for pressure relief is a gradual structure, which is beneficial to improving the stability and controllability of the burst; the edge of the cover plate of the present invention is provided with a flange structure, so that the edge of the cover plate has a certain elasticity, which is convenient for assembling and welding the cover plate and the shell, and makes the welding more firm. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is an exploded view of an explosion-proof steel shell of the present invention.

[0029] Figure 2 The figure is a top view of an explosion-proof steel shell of the present invention.

[0030] Figure 3 for Figure 2 Middle AA section view.

[0031] Figure 4 for Figure 3 Enlarged view of part A in the middle.

[0032] Figure 5 for Figure 3 Enlarged view of part B in the middle.

[0033] Figure 6 For Example 2 Figure 3 Enlarged view of part A in .

[0034] Figure 7 For Example 3 Figure 3 Enlarged view of part A in .

[0035] Figure 8 For Example 4 Figure 3 Enlarged view of part A in .

[0036] Fig. 9 It is a schematic diagram of the structure of the punch head used for engraving explosion-proof notches in the present invention.

[0037] Fig.10 The present invention is a flow chart of a method for manufacturing an explosion-proof steel shell.

[0038] The accompanying drawings in the specification are as follows:

[0039] Shell - 10;

[0040] Cover plate-20; explosion-proof notch-201; overlap-202; welding steps-203a, 203b; molten pool-204a, 204b, 204c, 204d; flange-205a; U-shaped flange-205b, 205c, 205d;

[0041] Punch head-30; protrusion-301. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in combination with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0044] Embodiment 1

[0045] This embodiment discloses an explosion-proof steel shell, such as Figure 1 , including a shell 10 with an opening at least at one end and a cover plate 20 for sealing the open end of the shell 10, an explosion-proof notch 201 is formed on the surface of the cover plate 20, and a flange structure adapted to the inner wall of the shell 10 is formed on the four edges of the cover plate 20. It can be understood that the explosion-proof notch 201 can also be set on the surface of the shell 10, that is, the explosion-proof notch 201 can be set on the outer wall of the shell 10, and can also be set on the inner wall of the shell 10. In this embodiment, only the explosion-proof notch 201 is set on the surface of the cover plate 20 for explanation.

[0046] The shell 10 in this embodiment is a cylindrical body with openings at both ends. The cover plate 20 is arranged on one end of the shell 10 to close the opening. In this arrangement, after the battery cell is installed in the shell 10, the other opening is closed to form a power battery or battery pack. It can be understood that the shell 10 can also be closed at one end and open at the other end. The cover plate 20 is arranged at the open end to close the opening. The shell 10 in this embodiment is made of stainless steel sheet with a thickness of 0.15mm to 0.25mm through cutting, bending and welding, preferably made of stainless steel sheet with a thickness of 0.2mm, combined with Figure 1 , Figure 2As shown, the shell 10 in this embodiment is a rectangular thin-walled cylindrical body with openings at both ends, including two oppositely arranged wide side walls and two oppositely arranged narrow side walls, and the cover plate 20 is a rectangular plate body that is adapted to the opening of the shell 10 of the rectangular cylindrical body. It can be understood that in other feasible embodiments, the shell 10 can also be set as a square or other shaped thin-walled cylindrical body. Correspondingly, the shape of the cover plate 20 is adapted to the shape of the open end of the shell 10. After the shell 10 is manufactured, the cover plate 20 is fixedly connected to the shell 10 by welding. After being fixedly connected to the shell 10, the cover plate 20 seals the open end of the shell 10. In this embodiment, the shell 10 is placed vertically and the cover plate 20 is arranged at the upper open end of the shell 10 for explanation.

[0047] The cover plate 20 is a rectangular plate. The position of the explosion-proof notch 201 on the surface of the cover plate 20 can be determined according to the assembly conditions inside the housing 10, and can be set at any desired position on the cover plate 20. In this embodiment, the explosion-proof notch 201 is set in the middle of the cover plate 20 for illustration. Figure 2-Figure 5 As shown, the explosion-proof notch 201 is formed by stamping, and the projection of the trajectory of the explosion-proof notch 201 on the surface of the cover plate 20 can be set to an elliptical, circular, square or other closed curves, such as Figure 1 , Figure 2 As shown, the trajectory of the explosion-proof notch 201 in this embodiment is set to be an elliptical curve set along the length direction of the cover plate 20, combined with Figure 3-Figure 5 As shown, the residual thickness of the explosion-proof notch 201 is 0.07 mm to 0.14 mm. Figure 5 As shown, the residual thickness of the explosion-proof notch 201 is defined as the remaining thickness H of the cover plate 20 after being punched and recessed at the explosion-proof notch 201. The explosion-proof notch 201 is only formed by the surface of the cover plate 20 being recessed into the body of the cover plate 20. The other opposite surface of the cover plate 20 remains flat, and no protruding features are generated at the place corresponding to the explosion-proof notch 201. It can be understood that when the explosion-proof notch 201 is set on the surface of the shell 10, the projection of the trajectory of the explosion-proof notch 201 on the surface of the shell 10 can also be set as an elliptical, circular, square or other closed curve. The residual thickness of the explosion-proof notch 201 is defined as the remaining side wall thickness of the shell 10 after being punched and recessed at the explosion-proof notch 201. The cross-section of the explosion-proof notch 201 can be in the shape of a U-shaped groove, a V-shaped groove or an inverted trapezoidal groove, such as Figure 4 , Figure 5As shown, in this embodiment, the explosion-proof notch 201 is preferably an inverted trapezoidal groove, thereby forming an explosion-proof valve for relieving pressure in the inner cavity of the shell 10 at the explosion-proof notch 201. Since the explosion-proof valve is formed by stamping in an integral manner with the cover plate 20, there is no need to separately assemble and weld an explosion-proof disk. Therefore, the cover plate 20 does not need to be relatively thick to consider the feasibility of assembly and welding with the explosion-proof disk. In general designs, this method of welding an explosion-proof disk usually requires the thickness of the cover plate 20 to be more than 1.5 mm in order to weld the separate explosion-proof disk to the cover plate 20 well. Furthermore, since there is no need to weld an explosion-proof disk on the cover plate 20, the cover plate 20 formed by stamping in this solution can be It is formed by stamping a thinner sheet or plate. It can be formed by stamping a stainless steel plate or sheet with a thickness of 0.15mm to 0.35mm. For example, it can be formed by stamping a stainless steel plate or sheet with a thickness of 0.15mm, 0.2mm, 0.25mm or 0.35mm. The cover plate 20 in this scheme is preferably made of 0.2mm stainless steel sheet or plate. Therefore, due to its thin thickness, the cover plate 20 forming the integrated explosion-proof valve is easier to stamp, the process is simple, the production efficiency is high, and the yield rate is higher. In this way, since the residual thickness at the explosion-proof notch 201 is smaller than the thickness at other positions of the cover plate 20, when the cover plate 20 is welded and fixed to the shell 10, when the pressure of the high-pressure gas generated in the shell 10 that is closed at both ends reaches a preset value, the explosion-proof notch 201 on the surface of the cover plate 20 will first crack to release the pressure, thereby preventing the gas pressure in the shell 10 from continuing to rise and causing a more severe accident of the shell 10 exploding as a whole, thereby achieving the purpose of pressure relief and explosion prevention. In this embodiment, the explosion-proof notch 201 is arranged on the upper surface of the cover plate 20. In order to prevent other corrosive liquids and impurities from entering the explosion-proof notch 201 and corroding the explosion-proof notch 201, it is necessary to stick a protective film on the upper surface of the cover plate 20 to protect the explosion-proof notch 201. In other feasible embodiments, the explosion-proof notch 201 can be arranged on the lower surface of the cover plate 20. The explosion-proof notch 201 arranged on the lower surface of the cover plate 20 can keep the upper surface of the cover plate 20 smooth and beautiful, and there is no need to stick a protective film to protect the explosion-proof notch 201.

[0048] As an improvement of this embodiment, Figures 3 to 5 As shown, the residual thickness of the explosion-proof notch 201 gradually increases or decreases from one end of the cover plate 20 to the other end opposite thereto. Fig. 9 , Fig. 92 is a schematic diagram of a mold of a punch head 30 for punching an explosion-proof notch 201 on the surface of a cover plate 20. In the mold, a protruding height of a protruding portion 301 for punching and forming the explosion-proof notch 201 gradually decreases or increases from one end of the punch head 30 to the opposite end of the punch head 30. Therefore, a residual thickness of the explosion-proof notch 201 punched on the surface of the cover plate 20 by the punch head 30 gradually increases or decreases from one end of the cover plate 20 to the opposite end. In the present embodiment, the residual thickness of the explosion-proof notch 201 gradually increases or decreases along the length direction of the cover plate 20. It can be understood that in other feasible embodiments, the residual thickness of the explosion-proof notch 201 can also gradually increase or decrease along the width direction of the cover plate 20. It can be understood that the explosion-proof notch 201 can also be punched and engraved on the surface of the shell 10 by the punch head 30. In this embodiment, the residual thickness of the thinner end of the explosion-proof notch 201 can be set to 0.07mm-0.09mm, and the residual thickness of the thicker end of the explosion-proof notch 201 can be set to 0.12mm-0.14mm. Preferably, when the thickness of the cover plate 20 is 0.2mm, the residual thickness of the thinner end of the explosion-proof notch 201 is set to 0.08mm, and the residual thickness of the thicker end of the explosion-proof notch 201 is set to 0.13mm. It can be understood that when the thickness of the cover plate 20 is reduced, the residual thickness of the thicker end of the explosion-proof notch 201 is correspondingly The residual thickness of the thin end and the residual thickness of the thicker end can be appropriately reduced. When the thickness of the cover plate 20 increases, the residual thickness of the thinner end and the residual thickness of the thicker end of the explosion-proof notch 201 can be appropriately increased accordingly. Alternatively, the residual thickness of the thinner end and the residual thickness of the thicker end of the explosion-proof notch 201 can be determined according to the parameters of the battery cell in the shell 10 and the use environment. It can be understood that when the explosion-proof notch 201 is set on the surface of the shell 10, the reasonable depth of the thinner end and the thicker end of the explosion-proof notch 201 can also be determined according to the wall thickness of the shell 10. In this way, since the residual thickness of the explosion-proof notch 201 changes gradually, when high pressure is generated inside the shell 10, each time when bursting pressure relief occurs, the cracking starts from the position where the residual thickness of the explosion-proof notch 201 is the smallest, and then gradually extends to the end of the explosion-proof notch 201 where the residual thickness is thicker, and the bursting pressure relief is relatively stable. In the case where the residual thickness of the explosion-proof notch 201 is set to be equal and unchanged, when bursting pressure relief occurs in the shell 10, the place where the explosion-proof notch 201 starts to crack is unpredictable, or the entire explosion-proof notch 201 may burst synchronously, causing the cover plate 20 body to splash out of the shell 10. In comparison, the present solution has a variable setting of the residual thickness of the explosion-proof notch 201, which makes the bursting stability and controllability stronger.It can be understood that, when the residual thickness of the explosion-proof notch 201 is set to gradually change, the projection of the trajectory of the explosion-proof notch 201 on the cover surface can also be an unclosed curve. In this case, the residual thickness of the thicker end of the explosion-proof notch 201 is equal to the thickness of the cover 20. In this setting, when high pressure is generated inside the shell 10, each time a burst pressure relief occurs at the explosion-proof notch 201, the cracking starts from the position where the residual thickness of the explosion-proof notch 201 is the smallest, and then gradually moves to the residual thickness of the explosion-proof notch 201. The thicker end of the residual thickness of the explosion-proof notch 201 extends and cracks, and since the thickness of the thicker end of the residual thickness of the explosion-proof notch 201 is the same as the thickness of the cover plate 20, the thickness of the thicker end of the residual thickness of the explosion-proof notch 201 whose trajectory is an unclosed trajectory is thicker than that of the explosion-proof notch 201 whose trajectory is a closed curve. Therefore, the entire explosion-proof notch 201 will not be completely cracked when the shell 10 is exploded for pressure relief, which effectively prevents the cover plate 20 from splashing out of the cover plate 20 and damaging other components when the shell 10 is exploded for pressure relief.

[0049] In this embodiment, a steel pressure plate can be provided under the cover plate 20 to strengthen the strength of the cover plate 20 so as to improve the deformation resistance of the cover plate 20. The steel pressure plate can be pasted on the lower surface of the cover plate 20. The length and width of the steel pressure plate are correspondingly smaller than the length and width of the cover plate 20. A through hole 2042 cooperating with the explosion-proof notch 201 is provided in the middle of the steel pressure plate, so that the pressure generated in the shell 10 can directly act on the explosion-proof notch 201 on the cover plate 20. With the strengthening effect of the steel pressure plate, while meeting the required use strength of the cover plate 20, the thickness of the cover plate 20 can be as thin as possible, and can be as thin as 0.15 mm. This makes the stamping of the cover plate 20 easier and the yield rate higher.

[0050] Combination Figure 3 , Figure 4As shown, in this embodiment, the flange structure includes a downward flange 205a formed along the four edges of the cover plate 20, and the outer wall of the flange 205a is adapted to the inner wall of the shell 10. When a steel pressure plate is attached to the lower surface of the cover plate 20, the height of the flange 205a is less than the thickness of the steel pressure plate and the cover plate 20 after superposition (the height of the flange 205a is defined as the distance from the upper surface of the cover plate 20 to the lower end surface of the flange 205a). In this way, the lower end of the flange 205a will not extend downward beyond the lower surface of the steel pressure plate under the cover plate 20, and will not interfere with components such as the battery cell installed in the shell 10. In this embodiment, the height of the flange is 0.5mm~0.7mm, preferably 0. .6mm, due to the setting of the flange 205a, the edge of the cover 20 has a certain elasticity. When the outer wall of the flange 205a is matched with the inner wall of the shell 10 to cover the cover 20 on the upper port of the shell 10, the cover 20 is more easily assembled on the upper port of the shell 10. In this embodiment, when the cover 20 is assembled on the upper port of the shell 10, the depth of the flange 205a into the shell is 0.25mm~0.45mm (the depth of the flange 205a into the shell is defined as the distance between the lower end surface of the flange 205a and the upper end surface of the shell 10). Preferably, the depth of the flange 205a into the shell is 0.3mm. Of course, the depth of the flange 205a into the shell can be reasonably adjusted according to the specifications of the product. In this embodiment, when the cover plate 20 is assembled to the upper port of the shell 10 to close the upper port of the shell 10, the upper surface of the cover plate 20 is 0.15mm to 0.4mm higher than the upper end surface of the shell 10, such as 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm or 0.4mm. Preferably, the upper surface of the cover plate 20 is 0.3mm higher than the upper end surface of the shell 10 so that the upper surface of the cover plate 20 and the upper end surface of the shell 10 form a welding step 203a that is conducive to welding the cover plate 20 and the shell 10 together. In this way, when laser welding is used to melt-weld the cover plate 20 and the shell 10 together at the welding step 203a, a molten pool 204a is formed at the welding step 203a to fill the welding step 203a. During welding, under the blowing state of protective gas, the molten pool 204a is full in shape and naturally forms a rounded corner state, and the welding effect is better.

[0051] Embodiment 2

[0052] Combination Figure 3 , Figure 6As shown, in the present embodiment, the flange structure includes a U-shaped flange 205b with an opening upward formed along the four edges of the cover plate 20, the outer wall of the U-shaped flange 205b is adapted to the inner wall of the shell 10, and when the lower surface of the cover plate 20 is attached to the steel pressure plate, the lower end surface of the U-shaped flange 205b is located in the space above the plane where the lower surface of the steel pressure plate is located, or the lower end surface of the U-shaped flange 205b is flush with the lower surface of the steel pressure plate. In this way, the lower end of the U-shaped flange 205b will not exceed downwardly the lower surface of the steel pressure plate under the cover plate 20, and will not interfere with components such as the battery cells installed in the shell 10. The upper end surface of the U-shaped flange 205b is flush with the upper end surface of the cover plate 20 or is located in the space below the plane where the upper end surface of the cover plate 20 is located. Preferably, the upper end surface of the U-shaped flange 205b is located in the space below the plane where the upper end surface of the cover plate 20 is located. The setting of b makes the edge of the cover plate 20 have a certain elasticity. When the outer wall of the U-shaped flange 205b is matched with the inner wall of the shell 10 to cover the cover plate 20 on the upper port of the shell 10, the cover plate 20 is more easily assembled on the upper port of the shell 10. In this embodiment, the height of the U-shaped flange 205b is 0.6mm-1.0mm (the height of the U-shaped flange 205b is defined as the distance from the upper surface of the cover plate 20 to the lower end surface of the U-shaped flange 205b). Preferably, it is 0.8mm. When the cover plate 20 is assembled on the upper port of the shell 10, the depth of the U-shaped flange 205b entering the shell is 0.25mm~0.45mm (the depth of the U-shaped flange 205b entering the shell is defined as the distance between the lower end surface of the U-shaped flange 205b and the upper end surface of the shell 10). Preferably, the depth of the U-shaped flange 205b entering the shell is 0.3mm. Of course, the depth of the U-shaped flange 205b entering the shell can be reasonably adjusted according to the specifications of the product. In this embodiment, when the cover plate 20 is assembled to the upper port of the shell 10 to close the upper port of the shell 10, the upper end surface of the U-shaped flange 205b is 0.15mm~0.4mm higher than the upper end surface of the shell 10, such as 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm or 0.4mm. Preferably, the upper end surface of the U-shaped flange 205b is 0.2mm higher than the upper end surface of the shell 10 so that the upper surface of the cover plate 20 and the upper end surface of the shell 10 form a welding step 203b that is conducive to welding the cover plate 20 and the shell 10 together. In this way, when laser welding is used at the welding step 230b to melt-weld the cover plate 20 and the shell 10 together, a molten pool 204b is formed at the welding step 203b to fill the welding step 203b. During welding, under the blowing state of protective gas, the molten pool 204b has a full shape and naturally forms a rounded state, and the welding effect is better.

[0053] Embodiment 3

[0054] Combination Figure 3 , Figure 7 As shown, in this embodiment, the flange structure includes a U-shaped flange 205c with an opening upward formed along the four edges of the cover plate 20, and the outer wall of the U-shaped flange 205c is adapted to the inner wall of the shell 10. When a steel pressure plate is attached to the lower surface of the cover plate 20, the lower end surface of the U-shaped flange 205c is located in a space above the plane where the lower surface of the steel pressure plate is located, or the lower end surface of the U-shaped flange 205c is flush with the lower surface of the steel pressure plate, so that the lower end of the U-shaped flange 205c will not extend downward beyond the steel pressure plate below the cover plate 20. The lower surface of the pressure plate will not interfere with components such as the battery cells installed in the shell 10. The upper end surface of the U-shaped flange 205c is flush with the upper end surface of the cover plate 20 or is located in the space below the plane where the upper end surface of the cover plate 20 is located. Preferably, the upper end surface of the U-shaped flange 205c is located in the space below the plane where the upper end surface of the cover plate 20 is located. The height of the U-shaped flange is 0.6mm~1.0mm (the height of the U-shaped flange 205c is defined as the distance from the upper surface of the cover plate 20 to the lower end surface of the U-shaped flange 205c), preferably 0.8mm. Due to the setting of the U-shaped flange 205c, the edge of the cover 20 has a certain elasticity. When the outer wall of the U-shaped flange 205c is matched with the inner wall of the shell 10 to cover the cover 20 on the upper port of the shell 10, the cover 20 is more easily assembled on the upper port of the shell 10. In this embodiment, when the cover 20 is assembled on the upper port of the shell 10, the depth of the U-shaped flange 205c entering the shell is 0.4mm~0.6mm (the depth of the U-shaped flange 205c entering the shell is defined as the distance between the lower end surface of the U-shaped flange 205c and the upper end surface of the shell 10). Preferably, the depth of the U-shaped flange 205c entering the shell is 0.5mm. Of course, the depth of the U-shaped flange 205c entering the shell can be reasonably adjusted according to the specifications of the product. In this embodiment, when the cover plate 20 is assembled to the upper port of the shell 10 to close the upper port of the shell 10, the upper end surface of the U-shaped flange 205c is flush with the upper end surface of the shell 10. When laser welding is used, welding is performed at the gap between the shell 10 and the U-shaped flange 205c, and a molten pool 204c is formed at the gap between the upper end surface of the shell 10 and the upper end surface of the U-shaped flange 205c.

[0055] Embodiment 4

[0056] Combination Figure 3 , Figure 8As shown, in the present embodiment, the flange structure includes an upwardly opening U-shaped flange 205d formed along the four edges of the cover plate 20, the outer wall of the U-shaped flange 205d is adapted to the inner wall of the shell 10, and when a steel pressure plate is attached to the lower surface of the cover plate 20, the lower end surface of the U-shaped flange 205d is located in the space above the plane where the lower surface of the steel pressure plate is located, or the lower end surface of the U-shaped flange 205d is flush with the lower surface of the steel pressure plate. In this way, the lower end of the U-shaped flange 205d will not extend downward beyond the lower surface of the steel pressure plate under the cover plate 20, and will not interfere with components such as the battery core installed in the shell 10, and the upper end surface of the U-shaped flange 205d is flush with the upper end surface of the cover plate 20 or is located above the cover plate The space below the plane where the upper end surface of 20 is located, preferably, the upper end surface of the U-shaped flange 205d is located in the space below the plane where the upper end surface of the cover plate 20 is located, the height of the U-shaped flange 205d is 0.6mm~1.0mm (the height of the U-shaped flange 205d is defined as the distance from the upper surface of the cover plate 20 to the lower end surface of the U-shaped flange 205d), preferably 0.8mm, the upper end surface of the U-shaped flange 205d extends in the horizontal direction to form a lap 202. In this embodiment, when the cover plate 20 is assembled to the upper port of the shell 10 to close the upper port of the shell 10, the lower surface of the lap 202 is in contact with the upper end surface of the shell 10, and the outer peripheral surface of the lap 202 is flush with the outer wall of the shell 10. When laser welding is adopted, welding is performed at the gap between the shell 10 and the overlap 202 , and a molten pool 204 d is formed at the gap between the upper end outer wall of the shell 10 and the outer peripheral surface of the overlap 202 .

[0057] The present application also provides a method for manufacturing an explosion-proof steel shell, which can be used to manufacture the above-mentioned explosion-proof steel shell. Fig.10 As shown, the preparation method mainly includes the following steps:

[0058] S1. Manufacturing the housing 10:

[0059] S101, cutting, punching or cutting out the sheet size when the shell 10 is unfolded. In this step, the sheet can be punched or cut from a stainless steel sheet with a thickness of 0.15mm to 0.25mm, preferably a 0.2mm stainless steel sheet. When the explosion-proof notch 201 is set on the side wall of the shell 10, in this step, the punched or cut stainless steel sheet can be punched to form an explosion-proof notch 201 with a residual thickness gradient. When punching the explosion-proof notch 201, the explosion-proof notch 201 can be engraved on one side surface of the stainless steel sheet, or on the other side surface of the stainless steel sheet.

[0060] S102, bending, bending the sheet obtained in step S101 according to the wide side size and the narrow side size of the shell 10 to form a cylindrical body with a joint seam;

[0061] S103, welding, continuously welding the joint seams of the cylinder in step S102 to form a cylinder with closed side walls;

[0062] S2, making cover plate 20:

[0063] S201, blanking, punching or cutting out the sheet size when the cover plate 20 is unfolded. In this step, the sheet can be punched or cut out of a stainless steel sheet with a thickness of 0.15 mm to 0.35 mm, preferably a 0.2 mm stainless steel sheet;

[0064] S202, when the explosion-proof notch 201 is set on the surface of the cover plate 20, the explosion-proof notch 201 with the residual thickness gradient feature is punched out on the surface of the sheet in step S201. In this step, the explosion-proof notch 201 may be punched on the upper surface of the sheet or on the lower surface of the sheet;

[0065] S203, punching out flange structures on the four edges of the sheet obtained in step S202, the flange structures can be as follows Figure 4 , Figure 6 , Figure 7 , Figure 8 The structure shown in;

[0066] S3, welding the shell 10 and the cover plate 20. After assembling the cover plate 20 obtained in step S2 and the open end of the shell 10 obtained in step S1, weld the cover plate 20 and the shell 10 together to obtain an explosion-proof thin steel shell. In this step, it is also possible to weld the cover plate 20 in step S2 to only one open end of the shell 10 as needed, and then weld the electrode plate to the other open end to obtain an explosion-proof thin steel shell.

[0067] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An explosion-proof steel shell, comprising a shell with at least one end open and a cover plate blocking the open end of the shell, characterized in that: An explosion-proof structure is integrally formed on the surface of the cover plate or the shell, and a flange structure is formed on the four edges of the cover plate, and the outer wall of the flange structure is matched with the inner wall of the shell.

2. The explosion-proof steel shell according to claim 1, characterized in that: The explosion-proof structure includes an explosion-proof notch arranged on the surface of the cover plate or the shell, and the residual thickness of the explosion-proof notch gradually increases or decreases from one end of the explosion-proof notch to the other opposite end. The residual thickness of the thinner end of the explosion-proof notch is 0.07mm~0.09mm, and the residual thickness of the thicker end of the explosion-proof notch is 0.12mm~0.14mm.

3. The explosion-proof steel shell according to claim 2, characterized in that: The cover plate is formed by integrally stamping a stainless steel plate with a thickness of 0.15 mm to 0.35 mm, the shell is made of a stainless steel plate with a thickness of 0.15 mm to 0.25 mm, and the cover plate is sealed and welded to the shell.

4. The explosion-proof steel shell according to claim 1, characterized in that: The flange structure includes downward flanges formed along the four edges of the cover plate, the outer wall of the flange is adapted to the inner wall of the shell, the height of the flange is 0.5mm~0.7mm, the upper surface of the cover plate is 0.2mm~0.4mm higher than the upper end surface of the shell to form a welding step between the upper end surface of the shell and the upper surface of the cover plate.

5. The explosion-proof steel shell according to claim 1, characterized in that: The flange structure includes an upwardly opening U-shaped flange formed along the four edges of the cover plate, the outer wall of the U-shaped flange is adapted to the inner wall of the shell, the height of the U-shaped flange is 0.6mm~1.0mm, and the upper end surface of the U-shaped flange is 0.15mm~0.4mm higher than the upper end surface of the shell to form a welding step between the upper end surface of the shell and the upper surface of the cover plate.

6. The explosion-proof steel shell according to claim 1, characterized in that: The flange structure includes an upwardly opening U-shaped flange formed along the four edges of the cover plate, the outer wall of the U-shaped flange is adapted to the inner wall of the shell, the height of the U-shaped flange is 0.6mm~1.0mm, and the upper end surface of the U-shaped flange is flush with the upper end surface of the shell.

7. The explosion-proof steel shell according to claim 1, characterized in that: The flange structure includes an upwardly opening U-shaped flange formed along the four edges of the cover plate, the outer wall of the U-shaped flange is adapted to the inner wall of the shell, the height of the U-shaped flange is 0.6mm~1.0mm, and the upper end surface of the U-shaped flange is provided with a lap edge extending in a horizontal direction, the lower surface of the lap edge is in contact with the upper end surface of the shell, and the outer peripheral surface of the lap edge is flush with the outer wall of the shell.

8. The explosion-proof steel shell according to claim 2, characterized in that: The projection of the trajectory of the explosion-proof notch on the surface of the cover plate or the surface of the shell is an elliptical, circular, square or other closed curve or an unclosed curve.

9. The explosion-proof steel shell according to any one of claims 1 to 8, characterized in that: The explosion-proof structure is arranged on the upper surface or the lower surface of the cover plate, or The explosion-proof structure is arranged on the outer wall or the inner wall of the shell.

10. A method for manufacturing an explosion-proof steel shell, characterized in that: The following steps are involved: S1. Making the shell: S101, blanking, punching or cutting out the sheet size when the shell is unfolded. In this step, the sheet can be punched or cut out of a stainless steel sheet with a thickness of 0.15 mm to 0.25 mm, preferably a 0.2 mm stainless steel sheet; S102, bending, bending the sheet obtained in step S101 according to the wide side size and narrow side size of the shell to form a cylindrical body with a joint seam; S103, welding, continuously welding the joint seams of the cylinder in step S102 to form a cylinder with closed side walls; S2. Making the cover plate: S201, blanking, punching or cutting out the sheet material size when the cover plate is unfolded. In this step, the sheet material can be punched or cut out of a stainless steel sheet material with a thickness of 0.15 mm to 0.35 mm; S202, punching out explosion-proof notches with residual thickness gradient characteristics on the surface of the sheet material in step S201. In this step, the explosion-proof notches may be punched on the upper surface of the sheet material or on the lower surface of the sheet material; S203, punching out flange structures on the four edges of the sheet obtained in step S202; S3, welding the shell and the cover plate: after the cover plate obtained in step S2 is assembled with the open end of the shell obtained in step S1, the cover plate and the shell are welded together to obtain an explosion-proof steel shell.

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