Cold heading forming process of negative electrode post, negative electrode post, battery top cover and battery

Abstract

This invention relates to the field of battery technology, and discloses a cold heading process for a negative electrode post, a negative electrode post, a battery top cover, and a battery. The cold heading process for the negative electrode post specifically includes: blanking: cutting a copper-aluminum composite plate into blanks according to a preset size; screening: screening out blanks that meet the requirements; and heading: feeding the screened qualified blanks into a first cold heading mold for extrusion, thereby extruding a first groove on the top of the aluminum layer to increase the height of the aluminum layer. By cold heading the blanks to form the negative electrode post, welding and CNC machining processes are eliminated, improving production efficiency and saving costs. It also ensures a strong bond between the copper and aluminum layers, reducing the risk of breakage and improving the reliability of the negative electrode post.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a cold heading process for a negative electrode post, a negative electrode post, a battery top cover, and a battery. Background Technology

[0002] In a power battery, the terminal is the component that connects the inside and outside of the battery. One end of the terminal connects to the external circuitry of the power battery, and the other end connects to the internal cell, thus enabling the charging and discharging function. Since using aluminum for the external circuitry can reduce cost and weight, aluminum sheets are generally used to connect the external circuitry to the cell. However, the negative electrode current collector inside the cell is made of copper foil. Due to the different melting points of copper and aluminum, direct laser welding is difficult. Therefore, the negative electrode terminals of current power batteries all use copper-aluminum composite materials.

[0003] In the existing technology, friction welding is usually used to fix the upper aluminum block and the lower copper block together to form a blank, and then the copper-aluminum composite pole is formed by CNC machining. The disadvantages of this processing method are: (1) Copper and aluminum have different coefficients of linear expansion, and friction welding is prone to thermal stress, which is often difficult to eliminate and will produce large welding deformation; (2) During the welding process, as the welding stress and brittleness increase, cracks are easily generated on the welding surface, especially in the heat-affected zone, which is more likely to crack or even break, reducing the safety of the negative pole; (3) Friction welding has high process requirements and also requires cutting to ensure the size of the pole after forming, which is inefficient, requires a large amount of profile, and has a high cost.

[0004] Therefore, there is an urgent need to provide a cold heading process for the negative electrode post, the negative electrode post, the battery top cover, and the battery to solve the above problems. Summary of the Invention

[0005] The first objective of this invention is to provide a cold heading process for negative electrode posts, which eliminates the welding and CNC machining processes, improves production efficiency, reduces production costs, and has a low risk of breakage between the aluminum and copper layers, resulting in higher reliability.

[0006] The second objective of this invention is to provide a negative electrode post, which is manufactured by the above-mentioned cold heading process. This negative electrode post has high structural strength and improves safety.

[0007] The third objective of this invention is to provide a battery top cover that, by providing the aforementioned negative electrode post, can improve safety and reduce production costs.

[0008] A fourth objective of this invention is to provide a battery that, by providing the aforementioned battery top cover, can improve safety and reduce production costs.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0010] The cold heading process for the negative electrode post includes the following steps:

[0011] Blanking: Cut the copper-aluminum composite plate into blanks according to the preset dimensions;

[0012] Screening: Selecting blanks that meet the requirements;

[0013] Upsetting groove: The selected qualified blank is fed into the first cold upsetting mold for extrusion, so as to extrude the first groove on the top of the aluminum layer, thereby increasing the height of the aluminum layer;

[0014] As an optional solution, between the material feeding step and the screening step, the following is also included:

[0015] Shaping: The blank is placed in a shaping fixture for shaping.

[0016] As an optional solution, in the groove-building step, the bottom surface of the first groove is higher than the copper-aluminum joint surface, and the axial distance D between the bottom surface of the first groove and the copper-aluminum joint surface is greater than 0.5mm and less than 2.5mm.

[0017] As an optional approach, after the trenching step, the following steps are also included:

[0018] Chassis forming: The blank is fed into the second cold heading mold for extrusion to extrude the chassis at the bottom of the copper layer.

[0019] As an optional approach, the chassis forming process includes:

[0020] A second groove is extruded at the bottom of the copper layer, making the outer edge dimension of the copper layer larger than the outer edge dimension of the aluminum layer.

[0021] As an optional approach, the following steps are included after the chassis forming process:

[0022] Step forming: The pole obtained in the chassis forming step is fed into the third cold heading mold for extrusion to form a step structure on the chassis.

[0023] As an optional approach, after the step forming step, the following steps are also included:

[0024] Excess material punching: The excess material obtained from the step forming process is removed to obtain the finished product.

[0025] The negative electrode post is manufactured by the cold heading forming process described in any of the above-mentioned negative electrode posts.

[0026] The battery top cover includes the aforementioned negative terminal post.

[0027] The battery includes a housing, a core pack, and a battery top cover, wherein the core pack is disposed within the housing, and the battery top cover is fastened to the opening end of the housing.

[0028] The beneficial effects of this invention are as follows:

[0029] This invention provides a cold heading process for negative electrode posts, comprising the following steps: blanking: punching a copper-aluminum composite plate into blanks according to a preset size; screening: screening out blanks that meet the requirements; and heading: sending the screened qualified blanks into a first cold heading mold for extrusion, thereby extruding a first groove on the top of the aluminum layer to increase the height of the aluminum layer. This invention uses cold heading to form negative electrode posts from blanks, eliminating welding and CNC machining processes, improving production efficiency, effectively reducing material waste, better controlling production costs, and ensuring a strong bond between the copper and aluminum layers with low breakage risk, thus improving the reliability of the negative electrode post.

[0030] The negative electrode post provided by the present invention is manufactured by the above-mentioned cold heading process. The negative electrode post has high reliability and improves safety.

[0031] The battery top cover provided by the present invention, by setting the above-mentioned negative electrode post, can improve safety and reduce production costs.

[0032] The battery provided by the present invention, by setting the above-mentioned battery top cover, can improve safety and reduce production costs. Attached Figure Description

[0033] To more clearly and understandably illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the negative electrode post forming process provided in an embodiment of the present invention;

[0035] Figure 2 This is a detailed flowchart of the cold heading process for the negative electrode post provided in this embodiment of the invention;

[0036] Figure 3 This is a schematic diagram of the negative electrode post provided in an embodiment of the present invention;

[0037] Figure 4 This is an axial cross-sectional view of the negative electrode post provided in an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of the battery top cover provided in an embodiment of the present invention;

[0039] Figure 6 This is an exploded view of the battery top cover provided in an embodiment of the present invention;

[0040] Figure 7 This is a top view of the battery top cover provided in an embodiment of the present invention;

[0041] Figure 8 yes Figure 7 Sectional view at point AA;

[0042] Figure 9 yes Figure 8 A magnified view of a section at point B in the middle;

[0043] Figure 10 This is a schematic diagram of the structure of the pressure block provided in an embodiment of the present invention;

[0044] Figure 11 This is a schematic diagram of the structure of the upper plastic part provided in an embodiment of the present invention.

[0045] In the picture:

[0046] 100. Copper-aluminum composite panel; 110. Aluminum layer; 120. Copper layer; 130. Copper-aluminum bonding surface;

[0047] 1. Cover plate assembly; 11. Upper plastic part; 111. Receiving groove; 112. Venting groove; 113. Protrusion; 12. Cover plate; 121. Explosion-proof valve hole; 13. Lower plastic part;

[0048] 2. Terminal post; 21. Negative terminal post; 211. Base plate; 2111. Second groove; 2112. Stepped structure; 2113. Boss; 212. Terminal post body; 2121. First groove; 22. Positive terminal post;

[0049] 3. Pressure block; 31. Mounting hole; 32. Welding groove;

[0050] 4. Sealing components;

[0051] 5. Connecting piece; 51. Stepped hole;

[0052] 6. Explosion-proof valve assembly; 61. Explosion-proof sheet; 62. Explosion-proof sheet film. Detailed Implementation

[0053] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0054] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0056] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, 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 limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0057] like Figure 1 and Figure 2 As shown, this embodiment provides a cold heading process for a negative electrode post, the specific steps of which include:

[0058] Step S1, Blanking: Cut the copper-aluminum composite plate 100 into blanks according to the preset size;

[0059] Step S2, Shaping: The blank is placed in a shaping fixture for shaping;

[0060] Step S3, Screening: Screen out the blanks that meet the requirements;

[0061] Step S4, Upsetting groove: The selected qualified blank is fed into the first cold upsetting mold for extrusion, so as to extrude the first groove 2121 on the top of the aluminum layer 110, thereby increasing the height of the aluminum layer 110.

[0062] Step S5, chassis forming: The blank is fed into the second cold heading mold for extrusion to extrude the chassis 211 at the bottom of the copper layer 120. During the chassis forming process, a second groove 2111 can also be extruded at the bottom of the copper layer 120, so that the outer edge dimension of the copper layer 120 is larger than the outer edge dimension of the aluminum layer 110;

[0063] Step S6, Step forming: The pole obtained in the chassis forming step is sent into the third cold heading mold for extrusion so that a step structure 2112 is formed on the chassis 211;

[0064] Step S7, Excess Material Cutting: The excess material obtained in the step forming step is removed to obtain the finished product.

[0065] refer to Figure 1 In step S1, the copper-aluminum composite plate 100 is punched into blanks according to a preset size using a stamping machine. The copper-aluminum composite plate 100 is a new type of material made by bonding copper and aluminum plates together through a specific process, with an aluminum plate on top and a copper plate on the bottom. The copper-aluminum composite plate 100 can be obtained through external purchase, making it readily available. One copper-aluminum composite plate 100 can be punched into several cylindrical blanks to obtain a semi-finished product (e.g., ...). Figure 1 As shown in Figure b), the upper end is an aluminum layer 110, and the lower end is a copper layer 120. Due to the different hardness of copper and aluminum materials, the diameters of the copper layer 120 and aluminum layer 110 in semi-finished product one will differ, with the diameter of the copper layer 120 being slightly larger than that of the aluminum layer 110. Therefore, in order to improve the consistency of the blank size, in step S2, semi-finished product one is shaped using a special shaping fixture to ensure the consistency of the blank size and to remove a small amount of copper material adhering to the surface of the aluminum layer 110. In step S3, the shaped blank is screened using a special screening disc to select blanks that meet the requirements, namely, the diameters of the copper layer 120 and aluminum layer 110 are consistent and the surface is flat. In step S4, the qualified semi-finished product one is fed into the first cold heading mold for extrusion using a special fixture to extrude the first groove 2121 on the top of the aluminum layer 110, resulting in semi-finished product two (as shown in Figure b). Figure 1 (As shown in c). By extruding the first groove 2121 on the top of the aluminum layer 110, the aluminum material originally located at the first groove 2121 can be moved to other positions, thereby increasing the height of the pole post to meet the design size requirements, while saving material usage. In step S5, the semi-finished product two is fed into the second cold heading mold for extrusion using a special fixture, causing the copper material to flow in all directions, so as to extrude the base plate 211 at the bottom of the copper layer 120, obtaining the semi-finished product three (as shown in c). Figure 1(As shown in d). In this step, while extruding the base plate 211, a second groove 2111 is extruded at the bottom of the copper layer 120, making the outer edge dimension of the copper layer 120 larger than the outer edge dimension of the aluminum layer 110, thus making the base plate 211 larger and fuller. The diameter of the base plate 211 is larger than the diameter at other locations, so that after the pole post 2 passes through the cover plate assembly 1, the base plate 211 can abut against the lower surface of the cover plate assembly 1 to form a limiting effect. In step S6, the semi-finished product three is fed into the third cold heading mold for extrusion using a special fixture, so that a stepped structure 2112 is formed on the base plate 211, resulting in the semi-finished product four (as shown in d). Figure 1 As shown in Figure e), the stepped structure 2112 on the chassis 211 is for positioning when it mates with the stepped hole 51 of the connecting piece 5. In step S7, excess material is removed from the semi-finished product 4 to remove the excess material generated by extrusion in steps S1 to S6, resulting in the finished product (as shown in Figure e). Figure 1 (as shown in f).

[0066] This embodiment uses cold heading to form the negative electrode post 21 from the blank, eliminating the welding and CNC machining processes, thus improving production efficiency, effectively reducing material waste, and better controlling production costs. Furthermore, this processing technology ensures a strong bond between the copper layer 120 and the aluminum layer 110, minimizing the risk of breakage and enhancing the reliability of the negative electrode post 21. Compared to the traditional negative electrode post 21 formed by friction welding, this embodiment involves fewer forming steps, simplifying the forming process, improving processing efficiency, and significantly reducing material and processing costs.

[0067] Preferably, in the blanking step, the copper layer 120 in the copper-aluminum composite plate 100 accounts for 30% to 50% of the overall material thickness. It is understood that the price of aluminum is much lower than that of copper. By appropriately reducing the amount of copper in the copper-aluminum composite plate 100, the processing cost of the negative electrode post 21 is reduced, and the weight of the negative electrode post 21 is also reduced to some extent. For example, the thickness of the copper layer 120 in the copper-aluminum composite plate 100 accounts for 30%, 35%, 40%, 45%, or 50% of the overall material thickness. By setting the thickness of the copper layer 120 within the above range, the amount of copper in the copper-aluminum composite plate 100 is appropriately reduced, thereby reducing the processing cost of the negative electrode post 21 and also reducing its weight.

[0068] Furthermore, such as Figure 3 and Figure 4As shown, the bottom surface of the first groove 2121 formed in the groove-building step is higher than the copper-aluminum bonding surface 130, and the axial distance D between the bottom surface of the first groove 2121 and the copper-aluminum bonding surface 130 is greater than 0.5 mm and less than 2.5 mm. By adopting this configuration, the first groove 2121 is formed only on the aluminum layer 110 without damaging the copper-aluminum bonding surface 130, ensuring that the copper layer 120 and the aluminum layer 110 are firmly bonded together, minimizing the risk of breakage, and thus ensuring the structural strength of the negative electrode post 21. For example, the axial distance D between the bottom surface of the first groove 2121 and the copper-aluminum bonding surface 130 can be 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.2 mm, or 2.4 mm. By setting the axial distance D within the above range, the structural strength of the negative electrode post 21 can be guaranteed, preventing it from breaking at the copper-aluminum bonding surface 130.

[0069] Furthermore, in the upsetting step, the second cold heading die includes a cooperating concave die and a convex die. The concave die has a cavity, and the semi-finished product 2 is placed inside the cavity with the aluminum layer 110 facing the cavity. A push rod protrudes from the cavity and is used to abut against the bottom surface of the first groove 2121. Part of the copper material protrudes from the cavity. The convex die is used to press the bottom of the copper layer 120, so that the copper material flows to the surrounding area to form the base 211. Due to the difference in hardness between copper and aluminum, the push rod abutting against the bottom surface of the first groove 2121 can support the aluminum material and prevent the copper material from flowing into the aluminum material during the upsetting process, which would result in insufficient copper material volume and an undersized base 211.

[0070] Specifically, the height of the cavity is less than the height of the blank but greater than the height of the aluminum layer 110. This allows the sidewalls of the cavity to confine all the material of the aluminum layer 110 and part of the material of the copper layer 120. The remaining portion of the copper layer 120 protruding from the cavity forms the base 211, thus restricting the flow of aluminum material during molding. This also ensures that the base 211 is formed only on the copper layer 120 without damaging the copper-aluminum bonding surface 130, thereby guaranteeing the structural strength of the negative electrode post 21 and minimizing the risk of breakage. Preferably, the height of the cavity above the aluminum layer 110 is greater than 0.3 mm and less than 1.2 mm. For example, the height of the recess above the aluminum layer 110 is 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm or 1.1mm. By setting the height of the recess above the aluminum layer 110 within the above range, the flow of aluminum material during molding can be restricted, the structural strength of the negative electrode post 21 can be guaranteed, and it can be prevented from breaking at the copper-aluminum interface 130 without increasing the amount of copper material used excessively.

[0071] like Figure 3As shown, this embodiment also provides a negative electrode post 21, which is manufactured by the above-mentioned cold heading forming process of the negative electrode post. Specifically, the negative electrode post 21 is integrally formed from a copper-aluminum composite plate 100 by a cold heading process. The negative electrode post 21 includes a base plate 211 and a post body 212 that are coaxially arranged and whose outer edge dimensions decrease sequentially. The base plate 211 is formed in the base plate forming step of the above-mentioned cold heading forming process. A first groove 2121 is provided at the end of the post body 212 away from the base plate 1. The first groove 2121 is formed in the groove forming step of the above-mentioned cold heading forming process. The base plate 211 is made of copper material, and the post body 212 is made of aluminum material. The end face where the base plate 211 and the post body 212 are connected is the copper-aluminum bonding surface 130. By extruding a first groove 2121 into the top of the pole body 212, the material originally located in the first groove 2121 can be moved to other positions on the pole body 212, thereby increasing the height of the pole body 212 to meet the design size requirements and saving material usage. The shape of the first groove 2121 can be, but is not limited to, circular, square, elliptical, or other irregular shapes, and can be flexibly set according to requirements. No specific limitation is made here.

[0072] Preferably, such as Figure 4 As shown, the minimum distance W between the sidewall of the first groove 2121 and the outer sidewall of the electrode body 212 is greater than or equal to 1 mm. For example, the minimum distance W can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm or 7 mm. This minimum distance W is also the minimum wall thickness of the electrode body 212. By setting the minimum wall thickness of the electrode body 212 within the above range, the negative electrode 21 can ensure structural strength to meet welding strength requirements, thereby ensuring the structural strength of the battery top cover.

[0073] Furthermore, such as Figure 4 As shown, a boss 2113 is formed on the side of the chassis 211 near the pole body 212. The outer edge dimension of the boss 2113 is smaller than the outer edge dimension of the chassis 211 and is basically the same as the outer edge dimension of the bottommost end of the pole body 212. The boss 2113 is connected to the pole body 212, and the connection between the boss 2113 and the pole body 212 is the copper-aluminum bonding surface 130. The boss 2113 is formed in the chassis forming step of the cold heading forming process. That is to say, when forming the chassis 211, the aluminum material forming the pole body 212 and the copper material forming the boss 2113 can be just restricted by the cavity sidewall of the die. Therefore, the setting of the boss 2113 restricts the flow of aluminum material during forming, preventing insufficient aluminum material volume from causing the pole body 212 to be undersized. At the same time, it also ensures that the chassis 211 is formed only on the copper layer 120 without damaging the copper-aluminum bonding surface 130, thereby ensuring the structural strength of the negative pole 21 and reducing the risk of breakage.

[0074] Preferably, the height h of the boss 2113 is greater than 0.3 mm and less than 1.2 mm. The height h of the boss 2113 is the height of the cavity above the aluminum layer 110 during the chassis extrusion step. For example, the height h of the boss 2113 is 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, or 1.1 mm. By setting the height h of the boss 2113 within the above range, it is possible to avoid the inability to effectively restrict the flow of aluminum material during molding due to an excessively small height h, and to avoid increasing the amount of copper material used due to an excessively large height h.

[0075] Furthermore, in some embodiments, the copper-aluminum bonding surface 130 is recessed towards the chassis 211, and this recess is formed during the stamping of the first groove 2121. In other embodiments, the copper-aluminum bonding surface 130 may also be configured to be uneven. By configuring the copper-aluminum bonding surface 130 in the above form, the contact surface between the electrode body 212 and the chassis 211 is made to have a concave-convex fit, which improves the bonding strength between the electrode body 212 and the base 211, ensures that the copper layer and the aluminum layer are firmly bonded together, reduces the risk of breakage, and thus ensures the structural strength of the negative electrode 21.

[0076] Furthermore, such as Figure 4 As shown, a second groove 2111 is formed on the bottom of the chassis 211 facing away from the chassis. The second groove 2111 is formed simultaneously with the chassis 211 during the chassis forming step of the above-mentioned cold heading forming process. First, by extruding the second groove 2111 at the bottom of the chassis 211, the material originally located at the second groove 2111 can be moved to the sides of the chassis 211 during the extrusion process, thereby increasing the diameter of the chassis 211 and making the dimensions around the second groove 2111 fuller to meet the size requirements. Second, since the negative electrode post 21 is made of copper-aluminum composite plate 100 through a cold heading process, during the extrusion of the blank, due to the difference in hardness between copper and aluminum materials (copper is harder than aluminum), the copper material will squeeze the aluminum material, which easily forms a large wavy joint surface at the junction of the copper and aluminum materials, thus affecting the structural strength of the negative electrode post 21. By extruding a second groove 2111 at the bottom of the chassis 211, the copper-aluminum composite plate 100 provides flow space for the copper material during the isovolute deformation process, reducing the compression of the copper material on the aluminum material and making the interface between the copper and aluminum materials slightly smoother. This ensures the structural strength of the negative electrode post 21, making the root of the negative electrode post 21 less prone to breakage. The shape of the second groove 2111 can be, but is not limited to, circular, square, elliptical, or other irregular shapes; it can be flexibly set according to requirements and is not specifically limited here.

[0077] Preferably, such as Figure 4As shown, the axial cross-section of the second groove 2111 is arched, and the angle α between its circumferential sidewall and the horizontal plane is greater than or equal to 15° and less than or equal to 60°. For example, the angle α is 15°, 20°, 25°, 30°, or 40°. By setting the inclination angle of the circumferential sidewall of the second groove 2111 within the above range, the diameter of the chassis 211 can be larger, while providing better fluidity for the copper material in the copper-aluminum composite plate 100, making the root of the negative electrode post 21 less prone to breakage, thereby ensuring the structural strength of the negative electrode post 21.

[0078] like Figure 5 and Figure 6 As shown, this embodiment also provides a battery top cover, including a cover assembly 1, terminals 2, and pressure blocks 3. Terminals 2 are divided into a positive terminal 22 and the aforementioned negative terminal 21. The positive terminal 22 and negative terminal 21 are used to conduct current through external electrical components. The positive terminal 22 and negative terminal 21 have identical external structures, differing only in that the positive terminal 22 is integrally formed from an aluminum plate using a cold forging process, while the negative terminal 21 is integrally formed from a copper-aluminum composite plate 100 using a cold forging process. Therefore, they are collectively referred to as terminals 2 below. Correspondingly, two pressure blocks 3 are provided, with each terminal 2 corresponding to one pressure block 3. Mounting holes 31 are formed on the pressure blocks 3. After the terminal 2 passes through the cover assembly 1, it engages with the mounting holes 31. The terminal 2 and pressure blocks 3 are fixed by laser welding, and the pressure blocks 3 and terminal 2 are respectively pressed against both sides of the cover assembly 1.

[0079] like Figure 3 As shown, the pole post 2 includes a base 211 and a pole post body 212 that are coaxially arranged and whose outer edge dimensions decrease sequentially. Both the base 211 and the pole post body 212 are cylindrical structures, and the outer diameter of the base 211 is larger than the outer diameter of the pole post body 212. This allows the base 211 to abut against the lower surface of the cover plate assembly 1 after the pole post body 212 passes through the cover plate assembly 1, thereby forming a limiting effect.

[0080] Specifically, such as Figure 6 As shown, the cover plate assembly 1 includes an upper plastic part 11, a cover plate 12, and a lower plastic part 13 stacked from top to bottom. The pressure block 3 is located on the side of the upper plastic part 11 away from the cover plate 12. The upper plastic part 11, the cover plate 12, and the lower plastic part 13 are all provided with through holes for the electrode post 2 to pass through. In this embodiment, the cover plate 12 is a smooth aluminum sheet. The electrode post 2 passes through the through holes of the lower plastic part 13, the cover plate 12, and the upper plastic part 11 from bottom to top and is connected to the mounting hole 31 of the pressure block 3. The electrode post 2 and the pressure block 3 are fixed by laser welding. The pressure block 3 is pressed against the upper surface of the upper plastic part 11, and the electrode post 2 is pressed against the lower surface of the lower plastic part 13.

[0081] It should be noted that, as Figures 7 to 9As shown, the cover plate 12 serves as the main support for the battery top cover, supporting other components. Figure 9 As shown, the upper plastic part 11 is embedded in the assembly gap between the pressure block 3 and the cover plate 12, serving as insulation and separating the pressure block 3 from the cover plate 12. This reduces the probability of external short circuits in the power battery and improves its safety performance. The lower plastic part 13 is located between the cover plate 12 and the base 211 of the terminal post 2, separating the cover plate 12 from the base 211 of the terminal post 2. This also serves as insulation and reduces the probability of external short circuits in the battery.

[0082] Further, refer to Figure 9 The battery top cover also includes a sealing element 4, which is fitted onto the terminal post 2 to seal the terminal post 2 against the cover plate 12. The sealing element 4 has an annular stepped structure, with its smaller outer diameter portion embedded in the assembly gap between the cover plate 12 and the terminal post 2, and the larger outer diameter portion abutting against the lower surface of the cover plate 12. This provides both sealing and insulation between the cover plate 12 and the terminal post 2. The sealing element 4 has a certain degree of elasticity and is interference-fitted into the assembly gap between the cover plate 12 and the terminal post 2, which helps improve the overall sealing performance, preventing air from entering the battery and electrolyte leakage. The sealing element 4 is made of an acid- and alkali-resistant, high-temperature-resistant elastic material, such as fluororubber, which is resistant to electrolyte corrosion.

[0083] refer to Figure 6 The assembly process of the battery top cover is as follows: First, the sealing element 4 is fitted onto the upper part of the terminal post 2. Then, the lower plastic part 13 is placed below the cover plate 12. The terminal post 2 with the sealing element 4 fitted on it passes through the lower plastic part 13 and the cover plate 12 in sequence, so that the base plate 211 at the bottom of the terminal post 2 abuts against the lower surface of the lower plastic part 13. Then, the upper plastic part 11 is placed above the cover plate 12 and fitted onto the terminal post 2. Then, the pressure block 3 is placed above the upper plastic part 11 and fitted onto the terminal post 2. Then, pressure is applied to the top of the terminal post 2 through the fixture, so that the material at the top of the terminal post 2 flows to all sides, thereby making the components fit tightly together. Then, the pressure block 3 is connected and fixed to the terminal post 2 through laser welding process, so that the components are fixed into a whole and the connection is stable. Compared with the riveted top cover, the welding process is simple, the cost is low, the assembly efficiency of the battery top cover is improved, and the connection strength of the battery top cover can be guaranteed.

[0084] It is understandable that when welding the pressure block 3 and the terminal post 2, welding will be carried out on the top of the pressure block 3 along the joint between the terminal post 2 and the pressure block 3. Therefore, during welding, the aluminum material on the top of the terminal post 2 will be extruded to form a welding residue. The welding residue protruding from the upper surface of the pressure block 3 will affect the aesthetics of the outer tube of the battery top cover.

[0085] To solve the above problems, such as Figure 9 and Figure 10 As shown, a welding groove 32 is formed on the surface of the pressure block 3. The welding groove 32 is connected to the periphery of the mounting hole 31 and is used to accommodate the welding residue generated during the welding of the electrode post 2 and the pressure block 3. Specifically, the upper surface of the pressure block 3 is higher than the upper surface of the electrode post 2. The welding groove 32 is circular and is located above the mounting hole 31 and coaxially arranged with the mounting hole 31. The radial dimension of the welding groove 32 is larger than the radial dimension of the mounting hole 31, thus forming a step on the top of the pressure block 3. The welding groove 32 is used to accommodate the welding residue extruded during welding, preventing the welding residue from protruding from the upper surface of the pressure block 3, thereby ensuring the flatness and aesthetics of the battery top cover. In other embodiments, the shape of the welding groove 32 can also be square, elliptical, or other irregular shapes, as long as the outer edge dimension of the welding groove 32 is larger than the outer edge dimension of the mounting hole 31. No specific limitation is made here.

[0086] Furthermore, such as Figure 6 As shown, the battery top cover also includes a connecting piece 5. The connecting piece 5 is located on the side of the lower plastic part 13 opposite to the cover plate 12. The connecting piece 5 has a bent structure. One end of the connecting piece 5 is used to fix it to the bottom of the terminal post 2, and the other end is used to connect it to the electrode tab of the battery cell, thereby realizing the conduction of current. It should be noted that since there are two terminals 2, correspondingly, there are two upper plastic parts 11, two sealing parts 4, and two connecting pieces 5, so as to cooperate with the corresponding terminals 2 respectively.

[0087] Specifically, in combination Figure 4 and Figure 9 The chassis 211 has a stepped structure 2112 at its edge, which is formed in step S6 of the cold heading process. A stepped hole 51 is formed on the connecting piece 5, and the stepped structure 2112 mates with the stepped hole 51. Specifically, the stepped structure 2112 gives the chassis 211 two different outer diameters, and a stepped surface is formed on the stepped structure 2112. The stepped hole 51 also includes two holes of different diameters. When the chassis 211 mates with the connecting piece 5, the smaller outer diameter portion of the chassis 211 passes through the smaller diameter hole in the stepped hole 51, and the larger outer diameter portion of the chassis 211 mates with the larger diameter hole in the stepped hole 51. The stepped surface of the chassis 211 mates with the stepped surface of the stepped hole 51. This arrangement improves the positioning effect between the chassis 211 and the connecting piece 5, and restricts mutual movement between the chassis 211 and the connecting piece 5 after assembly, facilitating subsequent assembly and welding processes. Meanwhile, the larger outer diameter portion of the chassis 211 can shield the gap between the smaller outer diameter portion of the chassis 211 and the wall of the stepped hole 51, preventing the heat generated during welding from being conducted to the vicinity of the cover plate assembly 1 through the gap.

[0088] Furthermore, such as Figure 4 and Figure 6 As shown, the axis of the pole post 2 is perpendicular to the lower plastic part 13, and the outer wall of the pole post 2 is inclined relative to the axis of the pole post 2. The inclination direction and inclination angle of the hole wall of the mounting hole 31 are the same as those of the outer wall of the pole post 2, and the outer wall of the pole post 2 fits snugly against the hole wall of the mounting hole 31. Here, the outer wall of the pole post 2 specifically refers to the outer wall of the pole post body 212, excluding the outer wall of the chassis 211. In this embodiment, as... Figure 4 As shown, the outer wall of the electrode post body 212 is inclined from bottom to top towards the interior of the electrode post body 212. In other embodiments, the outer wall of the electrode post body 212 can also be inclined from bottom to top towards the direction away from the electrode post body 212. The wall of the mounting hole 31 can be set with the same inclination direction and inclination angle. That is to say, the outer wall of the electrode post body 212 is a slope, and the wall of the mounting hole 31 is also a slope, so that the electrode post body 212 and the mounting hole 31 are engaged by the slope. On the one hand, the slope prevents the laser from directly burning the lower plastic part 13 during laser welding. On the other hand, the slope can form an interlock at the joint surface between the electrode post body 212 and the pressure block 3, thereby improving the structural strength of the battery cover 12.

[0089] Preferably, such as Figure 4 As shown, the angle θ between the outer wall of the electrode post body 212 and its axis is greater than 0° and less than or equal to 3°. For example, the angle θ is 1°, 2°, or 3°. The angle between the wall of the mounting hole 31 and its axis is also greater than 0° and less than or equal to 3°; for example, the angle is 1°, 2°, or 3°. By setting the inclination angle of the outer wall of the electrode post body 212 and the inclination angle of the wall of the mounting hole 31 within the above ranges, not only can direct laser radiation during laser welding prevent burns to the lower plastic part 13, but an interlock can also be formed at the joint surface between the electrode post body 212 and the pressure block 3, thereby improving the structural strength of the battery cover 12.

[0090] Furthermore, such as Figure 11 As shown, an exhaust groove 112 is provided on the side of the upper plastic part 11 that abuts against the pressure block 3, and the exhaust groove 112 communicates with the mounting hole 31. After the bottom surface of the pressure block 3 is attached to the surface of the upper plastic part 11, there is a certain gap between the exhaust groove 112 and the pressure block 3. The exhaust groove 112 can discharge the heat gas generated during the welding process, preventing the pole post 2 or the pressure block 3 from deforming due to the inability of heat gas to be discharged during the welding process. The exhaust groove 112 is shaped as an annular groove plus four straight grooves connected to the annular groove. In other embodiments, the exhaust groove 112 can also be other shapes, which can be flexibly set according to the requirements, and no specific limitation is made here.

[0091] Preferably, such as Figure 11As shown, the upper plastic part 11 has a receiving groove 111 on the side near the pressure block 3. The pressure block 3 is placed in the receiving groove 111, thus limiting its position. The aforementioned venting groove 112 is located at the bottom of the receiving groove 111. After the pressure block 3 is placed in the receiving groove 111, the bottom surface of the pressure block 3 is in contact with the bottom surface of the receiving groove 111. Multiple protrusions 113 are formed on the side wall of the receiving groove 111, spaced apart circumferentially. The protrusions 113 are very thin and abut against the pressure block 3. When the pressure block 3 is placed in the receiving groove 111, the protrusions 113 can position the pressure block 3. The surface of the protrusions 113 can be set as an inclined surface, allowing the pressure block 3 to enter the receiving groove 111 along the surface of the protrusions 113, making operation more convenient. The specific number of protrusions 113 is not specifically limited here and can be flexibly set according to actual needs.

[0092] Furthermore, such as Figure 5 and Figure 6 As shown, the battery top cover also includes an explosion-proof valve assembly 6, which includes an explosion-proof sheet 61 and an explosion-proof sheet film 62. The explosion-proof sheet 61 is assembled into the explosion-proof valve hole 121 of the cover plate 12 by welding. The explosion-proof sheet 61 can automatically and quickly release the pressure of the battery when the internal pressure rises, preventing the power battery from exploding and causing a safety accident. The explosion-proof sheet film 62 protects the explosion-proof sheet 61 and prevents external dust, water or other impurities from entering the explosion-proof sheet 61.

[0093] This embodiment also provides a battery, specifically a square battery, which includes a casing, a core pack, and the aforementioned battery top cover. The core pack is disposed within the casing, and the battery top cover is fastened to the open end of the casing. The casing serves to support the core pack, providing effective restraint and protection. The casing can be made of a conductive metal material, such as aluminum or aluminum alloy, and the battery top cover can be sealed to the casing by welding. By using the aforementioned battery top cover, the cost of the battery can be reduced, and the battery safety can be improved.

[0094] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A cold-upset forming process for a negative pole stud, characterized by, The specific steps include: Blanking: Cut the copper-aluminum composite plate (100) into blanks according to the preset size; Screening: Selecting blanks that meet the requirements; Upsetting groove: The selected qualified blank is fed into the first cold upsetting mold for extrusion, so as to extrude the first groove (2121) on the top of the aluminum layer (110) to increase the height of the aluminum layer (110); Chassis forming: The blank after the upsetting groove is fed into the second cold upsetting mold for extrusion, so that the copper material flows to all sides, so as to extrude the chassis (211) at the bottom of the copper layer (120). The second cold heading die includes a concave die and a convex die. The concave die has a cavity in which the blank after being grouted is placed, with the aluminum layer (110) facing the cavity. A push rod is protruding from the cavity and is used to abut against the bottom surface of the first groove (2121). Part of the copper layer (120) protrudes from the cavity. The convex die is used to press the bottom of the copper layer (120). The height of the cavity is less than the height of the blank and greater than the height of the aluminum layer (110).

2. The cold-upsetting forming process of a negative pole post according to claim 1, characterized in that, Between the material feeding step and the screening step, the following is also included: Shaping: The blank is placed in a shaping fixture for shaping.

3. The cold-upsetting forming process of the negative pole post according to claim 1, characterized in that, In the groove-building step, the bottom surface of the first groove (2121) is higher than the copper-aluminum bonding surface (130), and the axial distance D between the bottom surface of the first groove (2121) and the copper-aluminum bonding surface (130) is greater than 0.5mm and less than 2.5mm.

4. The cold-upsetting forming process of the negative pole post according to claim 1, characterized in that, The chassis forming process includes: A second groove (2111) is extruded at the bottom of the copper layer (120) so that the outer edge dimension of the copper layer (120) is larger than the outer edge dimension of the aluminum layer (110).

5. The cold-upsetting forming process of a negative pole post according to claim 1, characterized in that, Following the chassis forming process, the following steps are also included: Step forming: The pole obtained in the chassis forming step is sent into the third cold heading mold for extrusion so that a step structure (2112) is formed on the chassis (211).

6. The cold-upsetting forming process of a negative pole post according to claim 5, characterized in that, Following the step forming process, the following steps are also included: Excess material punching: The excess material obtained from the step forming process is removed to obtain the finished product.

7. A negative pole post, characterized by It is manufactured by cold heading forming process of negative electrode post as described in any one of claims 1-6.

8. A battery top cover characterized by, Includes the negative electrode post as described in claim 7.

9. A battery characterized by It includes a housing, a core pack, and a battery top cover as described in claim 8, wherein the core pack is disposed within the housing, and the battery top cover is fastened to the open end of the housing.

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