Lithium battery top cover sheet and forming process of explosion-proof valve mounting hole thereof

Abstract

The application provides a lithium battery top cover sheet and a forming process of an explosion-proof valve mounting hole thereof. The process increases the action of pre-punching in the process before the thickening forming process of the back convex bumping, the pre-punching is arranged in the middle of the bumping position, provides a material space for the bumping of the metal material belt when forming the concave part, prevents the material from flowing to both sides when forming, removes the excess material part formed by the excess material flowing into the pre-punching, forms a first side wall, provides a space for inserting the side wall of the protection type into the first side wall, separately applies pressure to the annular flange, avoids the conflict of the up-down forming force, the product has a large deformation at the same time, causes the poor flatness of the lithium battery top cover sheet, and the protection type prevents the material of the annular flange from flowing into the first side wall of the annular flange.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology for new energy vehicles, specifically to a lithium battery top cover sheet and its explosion-proof valve mounting hole forming process. Background Technology

[0002] With the increasing popularity of new energy lithium batteries, they have become an important direction for future energy competition, and green energy will also become a key development area in the future. In order to enhance the market competitiveness of lithium batteries, the requirements for product precision and dimensional consistency have become more stringent. Under the fierce market competition, the stability of equipment and the consistency of products have become even more important.

[0003] like Figure 9 The image shows a lithium battery top cover sheet, characterized by a raised bump on the back of the explosion-proof valve exceeding 2mm in thickness. Forming this bump often presents challenges due to material shortages. To address this issue, existing lithium battery top cover sheet and explosion-proof valve mounting hole forming processes can be found in CN114985594B. This process includes the following steps: Step S1: Continuously feed a metal strip in a step-by-step manner and punch out the lithium battery top cover sheet and terminal hole. Step S2: Stamp the punched area on the lithium battery top cover sheet to form a closed recess. Step S3: Stamp the annular side and the closed recess to form an annular sidewall, and apply pressure to the annular surface to cause it to sink, thus forming an annular sidewall at its edge, while simultaneously adjusting the height of the closed recess. Step S4: Stamp the upper annular surface of the annular side to form a continuous annular recess along the annular sidewall, with a raised ring formed at the inner edge of the annular recess. Simultaneously, stamp the lower end of the closed recess to form a recessed portion, and form an annular boss along the inner wall of the recessed portion. Step S5: Punch the middle of the closed recessed portion to form an explosion-proof valve mounting hole and an annular positioning groove, and chamfer the edge of the lithium battery top cover. Step S6: Punch the edges of the terminal hole, explosion-proof valve mounting hole, and liquid injection hole to form chamfers.

[0004] In the prior art, during step S2, when the back convex portion is thickened by pressing to form a closed concave portion, since the inside of the concave portion is closed while the sides are open, the material in the concave portion will preferentially move to the sides during the pressing and thickening process. This results in severe material overflow on both sides of the explosion-proof valve mounting hole, which may cause the edges to be crushed. Furthermore, it requires a large forming force, making material movement difficult. In step S3, the annular side portion and the closed concave portion are stamped to form an annular sidewall, and pressure is applied to the annular surface to make it sink and form an annular sidewall at its edge. At the same time, the height of the closed concave portion is adjusted. In this step, due to the conflict between the upper and lower forming forces and the large deformation of the product that occurs simultaneously in this step, the flatness of the lithium battery top cover sheet is poor. Summary of the Invention

[0005] The problem this invention aims to solve is to provide a forming process for a lithium battery top cover sheet and its explosion-proof valve mounting hole. The pre-punching, stretching, and back-forming process of this invention effectively solves the problem of insufficient material often encountered in the forming of convex bulges. At the same time, it avoids the problems of severe material overflow on both sides of the explosion-proof valve mounting hole, crushing of the edge, and large deformation of the product due to the conflict between the upper and lower forming forces, resulting in poor flatness of the lithium battery top cover sheet.

[0006] The technical solution adopted by the present invention to solve the above problems is as follows: a forming process for a lithium battery top cover sheet and its explosion-proof valve mounting hole, comprising the following steps:

[0007] Step S1: The metal strip is continuously conveyed in the blanking direction between the upper and lower dies of the continuous punching die, and during the conveying process, the lithium battery top cover, the first liquid injection hole, the pre-punched hole and at least one terminal hole on the lithium battery top cover are punched on the metal strip.

[0008] In step S2, during the continuous stepping conveying process, the metal strip is stamped into a recessed part at the outer edge of the pre-punched hole in the punching area of ​​the top cover plate. The recessed part includes an annular flange formed by the extrusion force during stamping and a residual material part at the bottom of the annular flange formed by the excess material of the annular flange flowing into the pre-punched hole. The height of the annular flange is H.

[0009] In step S3, during the continuous step-feeding process, the excess material in the metal strip is punched off to form the first sidewall.

[0010] In step S4, during the continuous step conveying process, the side wall of the protective mold is inserted into the first side wall, and the lower end face of the annular flange is stamped to make the height of the annular flange HX.

[0011] In step S5, during the continuous stepping conveying process, the upper half end face of the annular flange is stamped to form a first recessed portion. The first recessed portion includes an annular sidewall formed by the extrusion force during stamping and an annular surface located at the bottom of the annular sidewall.

[0012] In step S6, during the continuous stepping conveying process, the lower half end face of the annular flange is stamped to form an annular positioning groove. At the same time, under the extrusion force during stamping, the inner edge of the annular surface protrudes to form a convex ring, and the outer edge of the annular surface connects with the convex ring and the annular sidewall on both sides to form an annular recess.

[0013] In step S7, during the continuous step-by-step conveying process, the inner wall of the annular flange is punched away to form an explosion-proof valve mounting hole, and the lower half of the annular flange serves as the flange at the edge of the explosion-proof valve mounting hole.

[0014] Preferably, step S2 further includes the forming of the first electrode positioning groove: the first electrode positioning groove is continuously formed by punching the edge of the opening near the upper end face of the lithium battery top cover plate on the electrode hole.

[0015] Preferably, step S4 further includes the forming of the second injection hole and the second electrode positioning groove: during the continuous step conveying process, the edge of the first injection hole is punched and the second injection hole is formed, and the second electrode positioning groove, which is continuously provided, is punched and formed at the edge of the electrode hole near the lower end face of the lithium battery top cover.

[0016] Preferably, step S5 further includes a trimming and punching step for the second injection hole. During the continuous step-feeding process, the second injection hole is trimmed and punched using an injection hole punch.

[0017] Preferably, step S6 further includes a chamfering forming step, in which the metal strip is punched to form a beveled chamfer on the edge of the formed lithium battery top cover during the continuous step-feeding process.

[0018] Preferably, after step S7, there is a step S71, which is a chamfering forming step for the explosion-proof valve mounting hole. During the continuous step-feeding process, the lower edge of the formed explosion-proof valve mounting hole is punched and formed with a beveled chamfer.

[0019] Compared with the prior art, the advantages of the lithium battery top cover sheet and its explosion-proof valve mounting hole forming process designed in this invention are as follows:

[0020] Before the back convex bulge thickening process in step S2, a pre-punching action is added during step S1. This pre-punching hole is located in the middle of the overlay position, providing material flow space for the metal strip during overlay forming of the recessed portion in step S2, preventing material from flowing to both sides during forming. In step S3, the excess material formed by the excess material flowing into the pre-punching hole is removed to form the first sidewall, providing space for inserting the protective mold's sidewall into the first sidewall in step S4. This is achieved by separately applying pressure to the annular flange in step S4. The pressure is applied to avoid conflict between the upper and lower forming forces, which could lead to significant deformation of the product and poor flatness of the lithium battery top cover. The protective molding prevents material from flowing into the first sidewall of the annular flange. Under the pressure, the height of the annular flange is HX, forcing the material to extend only outwards from the first sidewall, increasing the thickness of the annular flange. This prepares for flange forming and meeting the required thickness and height. This is achieved by applying pressure to the annular flange separately in step S4 and separately in step S5. The upper half of the flange end face is stamped to form the first recess. In the prior art, the annular side and the closed recess are stamped in the same step, which is changed to stamping in two steps. This solves the problem of conflict between the upper and lower forming forces and large deformation of the product at the same time, resulting in poor flatness of the lithium battery top cover. In step S6, the lower half of the annular flange end face is stamped to form an annular positioning groove. The forming of the annular positioning groove is mainly used for positioning and fixing the explosion-proof valve protective film. At the same time, under the extrusion force during stamping, the inner edge of the annular surface protrudes to form a convex ring. The two sides of the outer edge of the annular surface are respectively connected to the convex ring and the annular sidewall to form an annular recess. The forming of the annular recess is mainly used for positioning the annular convex part on the explosion-proof valve to meet product requirements. In step S7, the inner wall of the annular flange is punched away to form the explosion-proof valve mounting hole. The lower half of the annular flange serves as the flange of the edge of the explosion-proof valve mounting hole, so that the inner wall of the explosion-proof valve mounting hole is perpendicular to the bottom surface of the annular recess and the bottom surface of the annular positioning groove to meet the forming requirements of the explosion-proof valve mounting hole.

[0021] Meanwhile, with pre-punching, the stretching process with pressing and extrusion is used to pull the middle material up and squeeze it to the annular side, which increases the thickness of the flange after forming to meet the requirements for the thickness and height of the flange. When pressing and thinning the flange, the material is designed to make the flange full and effectively solve the problem of insufficient material often encountered in the forming of the flange.

[0022] In addition, the inventors also experimented with stretching and flanging the outer ring of the pre-punched hole to form the back convex bulge of the explosion-proof valve. However, because the uneven cut surface at the tear edge left by the pre-punched hole is left on the convex bulge surface during the back-up forming process, a large amount of aluminum powder and aluminum wire are generated on the convex bulge surface after back-up forming. Compared with this solution, the uneven cut surface at the tear edge of the present invention is finely punched and chamfered in step S7 after multiple deformations, thus avoiding the problem of generating a large amount of aluminum powder and aluminum wire. Attached Figure Description

[0023] Figure 1 This is a top view of the entire invention;

[0024] Figure 2 This is a cross-sectional view of the metal strip of the present invention located at the sixth forming station;

[0025] Figure 3 This is a cross-sectional view of the metal strip of the present invention located at the forming station seven;

[0026] Figure 4 This is a cross-sectional view of the metal strip of the present invention located at the eighth forming station;

[0027] Figure 5 This is a cross-sectional view of the metal strip of the present invention located at the forming station nine;

[0028] Figure 6 This is a cross-sectional view of the metal strip of the present invention located at the forming station ten;

[0029] Figure 7 This is a cross-sectional view of the metal strip of the present invention located at the forming station eleven;

[0030] Figure 8 This is a cross-sectional view of the metal strip of the present invention located at the twelve forming stations;

[0031] Figure 9 This is a schematic diagram of the top cover of a lithium battery.

[0032] Illustrations: 100. Metal strip; 101. Forming station 1; 102. Forming station 2; 103. Forming station 3; 104. Forming station 4; 105. Forming station 5; 106. Forming station 6; 107. Forming station 7; 108. Forming station 8; 109. Forming station 9; 110. Forming station 10; 111. Forming station 11; 112. Forming station 12; 113. Blanking station; 1. Lithium battery top cover sheet; 2. Guide hole; 3. Pre-punching hole; 4. Injection hole 1; 5. Injection hole 2; 6. T-shaped cut edge hole; 7. Cut edge hole two; 8. Cut edge hole one; 9. Pole post hole; 10. Recessed part; 10.1. Annular flange; 10.2. Residual material part; 10.2.1. First side wall; 10.3. First recessed part; 10.3.1. Annular side wall; 10.3.2. Annular surface; 10.4. Protruding ring; 10.5. Annular recess; 10.6. Annular positioning groove; 10.7. Explosion-proof valve mounting hole; 10.8. Flange; 11. Pole post positioning groove one; 12. Pole post positioning groove two; 20. Protective shape. Detailed Implementation

[0033] Before detailing any embodiment of the invention, it should be understood that the invention, in its application, is not limited to the details of the construction and arrangement of the components set forth in the following description or illustrated in the following figures. The invention can have other embodiments and can be practiced or carried out in various ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting. The use of “comprising” or “having” and variations thereof is intended to cover the items set forth below and their equivalents, as well as any additional items. Unless otherwise specified or limited, the terms “installation,” “connection,” “support,” and “linkage,” and variations thereof are used broadly and cover both direct and indirect installation, connection, support, and linking. Moreover, “connection” and “linkage” are not limited to physical or mechanical connections or links.

[0034] Furthermore, firstly, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention. Secondly, the term "a" should be understood as "at least one" or "one or more," that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple. The term "a" should not be construed as a limitation on the quantity.

[0035] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments, and any variations or modifications may be made to the implementation of the present invention without departing from the stated principles.

[0036] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0037] The lithium battery top cover sheet and its explosion-proof valve mounting hole forming process described in the embodiment uses a continuous punching die for continuous stamping and forming. The continuous punching die includes, in sequence, a forming station 101 for forming the guide hole 2, a forming station 102 for forming the pre-punched hole 3 and the injection hole 4, a forming station 103 for forming the T-shaped cutting edge hole 6, a forming station 104 for forming the cutting edge hole 7, a forming station 105 for forming the cutting edge hole 8 and the electrode post hole 9, a forming station 106 for forming the recessed part 10 and the electrode post positioning groove 11, a forming station 107 for forming the first sidewall 10.2.1, and a forming station 108 for forming the injection hole 5 and the electrode post 6. The station includes a column positioning groove 12 and a forming station 108 for stamping the lower end face of the annular flange 10.1; a forming station 109 for trimming and forming the injection hole 5 and forming the annular sidewall 10.3.1 and annular surface 10.3.2; a forming station 110 for punching and forming the chamfered edge of the lithium battery top cover 1 and forming the annular positioning groove 10.6, the convex ring 10.4 and the annular recess 10.5; a forming station 111 for forming the explosion-proof valve mounting hole 10.7 and the flange 10.8; a forming station 112 for punching and forming the chamfered edge of the lower end edge of the formed explosion-proof valve mounting hole 10.7; and a blanking station 113.

[0038] The metal strip 100 is punched at the thirteen forming stations to form the lithium battery top cover 1 and its explosion-proof valve mounting hole 10.7. At the same time, a flange 10.8 that meets the thickness and height requirements is formed on the edge of the explosion-proof valve mounting hole 10.7. The specific forming steps are as follows:

[0039] In step S1, the metal strip 100 is continuously conveyed in the blanking direction between the upper and lower dies of the continuous blanking die. During the conveying process, it passes through stations one to five to punch and form the lithium battery top cover 1, the liquid injection hole 4, and the pre-punched hole 3 and at least one terminal hole 9 on the lithium battery top cover 1. The pre-punched hole 3 provides material flow space for the metal strip 100 when the recess 10 is formed later, and prevents the material from flowing to both sides during forming. The metal strip 100 is an aluminum strip.

[0040] In step S2, during the continuous step-by-step conveying process, the metal strip 100 passes through the forming station 106, where a recessed portion 10 is formed at the outer edge of the pre-punched hole 3 in the punching area of ​​the lithium battery top cover plate 1. The recessed portion 10 includes an annular flange 10.1 formed by the downward indentation of aluminum material under the extrusion pressure during punching, and a surplus material portion 10.2 formed at the bottom of the annular flange 10.1 by the excess aluminum material of the annular flange 10.1 flowing into the pre-punched hole 3. The height of the annular flange 10.1 is H. This step also includes the forming of the electrode positioning groove 11: the electrode positioning groove 11 is continuously punched and formed on the edge of the electrode hole 9 near the upper end face of the lithium battery top cover plate 1.

[0041] In step S3, during the continuous step conveying process, the metal strip 100 passes through the forming station 7 107, where the excess material 10.2 is punched off to form the first side wall 10.2.1. The inner wall of the first side wall 10.2.1 is used to attach the protective type 20.

[0042] In step S4, during the continuous step-by-step conveying process, the metal strip 100 passes through the forming station 8 108, where the sidewall of the protective mold 20 is inserted into the first sidewall 10.2.1, and the lower end face of the annular flange 10.1 is stamped. The protective mold 20 is used to fit inside the first sidewall 10.2.1. When stamping the lower end face of the annular flange 10.1, it prevents the material of the annular flange 10.1 from flowing into the first sidewall 10.2.1 on the annular flange 10.1. Under the action of the stamping force, the height of the annular flange 10.1 is HX, and the material is forced to... The material can only extend outward from the first sidewall 10.2.1, which increases the thickness of the annular flange 10.1, and prepares for the forming of the flange 10.8 and to meet the thickness and height requirements of the flange 10.8. This step also includes the forming of the injection hole 2 5 and the electrode positioning groove 2 12. During the continuous step conveying process, the metal strip 100 punches and forms the injection hole 2 5 at the edge of the injection hole 1 4, and punches and forms the electrode positioning groove 2 12 with continuous arrangement at the edge of the electrode hole 9 near the lower end face of the lithium battery top cover plate 1.

[0043] In step S5, during the continuous step-feeding process, the metal strip 100 passes through the forming station 9 109 to punch the upper surface of the annular flange 10.1 to form a first recess 10.3. The first recess 10.3 includes an annular sidewall 10.3.1 formed by the downward concavity under the extrusion force during punching and an annular surface 10.3.2 located at the bottom of the annular sidewall 10.3.1. This step also includes a trimming and punching step for the injection hole 2 5. During the continuous step-feeding process, the metal strip 100 uses an injection hole punch to trim and punch the injection hole 2 5.

[0044] In step S6, during the continuous step-by-step conveying process, the metal strip 100 passes through the forming station 110, where the lower end face of the annular flange 10.1 is stamped to form an annular positioning groove 10.6. The forming of the annular positioning groove 10.6 is mainly used for positioning and fixing the protective film of the explosion-proof valve. At the same time, under the extrusion pressure during stamping, the inner edge of the annular surface 10.3.2 protrudes to form a convex ring 10.4. The outer edges of the annular surface 10.3.2 are respectively connected to the convex ring 10.4 and the annular sidewall 10.3.1 to form an annular recess 10.5. The forming of the annular recess 10.5 is mainly used for positioning the annular protrusion on the explosion-proof valve, and the depth of the annular recess 10.5 formed by stamping meets the product requirements.

[0045] Step S6 also includes punching and forming a chamfered edge on the edge of the formed lithium battery top cover 1;

[0046] In step S7, during the continuous step-feeding process, the metal strip 100 passes through forming station 111, where the inner wall of the annular flange 10.1 is punched away to form the explosion-proof valve mounting hole 10.7. The lower half of the annular flange 10.1 serves as the flange 10.8 at the edge of the explosion-proof valve mounting hole 10.7. The inner wall of the explosion-proof valve mounting hole 10.7 is perpendicular to the bottom surface of the annular recess 10.5 and the bottom surface of the annular positioning groove 10.6, respectively, to meet the forming requirements of the explosion-proof valve mounting hole 10.7. During the continuous step-feeding process, the metal strip 100...

[0047] In step S71, the lower edge of the explosion-proof valve mounting hole 10.7 is punched and chamfered at the forming station 112. Finally, it passes through the blanking station 113 and is blanked.

[0048] The above description only illustrates the preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All modifications made within the scope of the independent claims of this invention are also within the scope of protection of this invention.

Claims

1. A process for forming a lithium battery top cover sheet and its explosion-proof valve mounting hole, characterized in that, The steps include the following: Step S1, the metal strip (100) is continuously conveyed in the blanking direction between the upper and lower dies of the continuous punching die, and during the conveying process, the lithium battery top cover (1), the liquid injection hole (4), the pre-punched hole (3) and at least one terminal hole (9) on the lithium battery top cover (1) are punched on the metal strip (100). In step S2, during the continuous step-by-step conveying process, the metal strip (100) is stamped into a recessed part (10) at the outer edge of the pre-punched hole (3) in the punching area of ​​the top cover plate. The recessed part (10) includes an annular flange (10.1) formed by the extrusion force during stamping and a residual material part (10.2) at the bottom of the annular flange (10.1) formed by the excess material of the annular flange (10.1) flowing into the pre-punched hole (3). The height of the annular flange (10.1) is H. In step S3, during the continuous step conveying process, the excess material (10.2) of the metal strip (100) is punched out to form the first sidewall (10.2.1); In step S4, during the continuous step conveying process, the side wall of the protective mold (20) is inserted into the first side wall (10.2.1), and the lower end face of the annular flange (10.1) is punched so that the height of the annular flange (10.1) is HX. In step S5, during the continuous step conveying process, the upper half end face of the annular flange (10.1) of the metal strip (100) is stamped to form a first recess (10.3). The first recess (10.3) includes an annular sidewall (10.3.1) formed by the extrusion force during stamping and an annular surface (10.3.2) located at the bottom of the annular sidewall (10.3.1). In step S6, during the continuous step conveying process, the lower end face of the annular flange (10.1) of the metal strip (100) is stamped to form an annular positioning groove (10.6). At the same time, under the extrusion pressure during stamping, the inner edge of the annular surface (10.3.2) protrudes to form a convex ring (10.4), and the outer edges of the annular surface (10.3.2) are respectively connected to the convex ring (10.4) and the annular sidewall (10.3.1) to form an annular recess (10.5). In step S7, during the continuous step conveying process, the inner wall of the annular flange (10.1) of the metal strip (100) is punched away to form the explosion-proof valve mounting hole (10.7), and the lower half of the annular flange (10.1) serves as the flange (10.8) at the edge of the explosion-proof valve mounting hole (10.7).

2. The forming process for the lithium battery top cover sheet and its explosion-proof valve mounting hole according to claim 1, characterized in that, Step S2 also includes the forming of the electrode positioning groove 1 (11): the electrode positioning groove 1 (11) is continuously formed by punching the edge of the hole (9) near the upper end face of the lithium battery top cover (1).

3. The forming process for the lithium battery top cover sheet and its explosion-proof valve mounting hole according to claim 2, characterized in that, Step S4 also includes the forming of injection hole 2 (5) and electrode positioning groove 2 (12): During the continuous step conveying process, the metal strip (100) punches and forms injection hole 2 (5) on the edge of injection hole 1 (4), and punches and forms electrode positioning groove 2 (12) continuously arranged on the edge of electrode hole (9) near the lower end face of lithium battery top cover (1).

4. The forming process for the lithium battery top cover sheet and its explosion-proof valve mounting hole according to claim 3, characterized in that, Step S5 also includes a trimming and punching process for the second injection hole (5). During the continuous step-by-step conveying process, the metal strip (100) is trimmed and punched using the injection hole punch.

5. The forming process for the lithium battery top cover sheet and its explosion-proof valve mounting hole according to any one of claims 1-4, characterized in that, Step S6 also includes a chamfering forming step, in which the metal strip (100) punches and forms a chamfered edge on the edge of the formed lithium battery top cover sheet (1) during the continuous step conveying process.

6. The forming process for the lithium battery top cover sheet and its explosion-proof valve mounting hole according to claim 5, characterized in that, After step S7, there is also step S71, which is a chamfering forming step for the explosion-proof valve mounting hole (10.7). During the continuous step conveying process, the metal strip (100) punches and forms a beveled chamfer on the lower edge of the formed explosion-proof valve mounting hole (10.7).

Images