Stretching forming method of connecting piece

Abstract

The invention relates to the technical field of stamping and stretching, in particular to a stretching forming method of a connecting piece. The thickness of the connecting piece is T, and the volume of the product convex hull is V. The stretching forming method of the connecting piece comprises the following steps that S1, the connecting piece is stretched upwards so that a stretching convex hull can be formed on the connecting piece in a stretching mode, and the volume of the stretching convex hull ranges from 1.8 V to 2.5 V; s2, the stretching convex hull is extruded at least twice so that the outer diameter and the height of the stretching convex hull can be reduced, a compressed convex hull can be formed, and the size of the compressed convex hull ranges from 1.05 V to 1.15 V; and S3, the inclination angle of the side wall of the compression convex hull and the height of the thickness compression convex hull are shaped till the compression convex hull forms a product convex hull, the side wall of the product convex hull is T1, and T1 is larger than or equal to 0.8 T and smaller than T. And the thickness of the side wall of the product convex hull of the connecting sheet is more than 80% of the thickness of the connecting sheet, so that the resistance after the connecting sheet is electrically connected with the pole and the battery cell is less than 0.5 milliamperes.

Description

Technical Field

[0001] This invention relates to the field of stamping and stretching technology, and in particular to a stretching forming method for connecting pieces. Background Technology

[0002] In new energy batteries, connectors primarily serve as the electrical connection medium between the battery terminals and the battery cells. Connectors are generally made of relatively soft materials such as copper and aluminum sheets, and they need to be stamped and stretched using a stretching device to give them flat surfaces and convex features.

[0003] Currently, stamping and stretching processes typically involve upward or downward stretching, followed by one or two shaping steps before direct cutting. Existing stamping and stretching processes often result in a relatively small sidewall thickness for the convex package, making it difficult to meet the production requirement that the sidewall thickness of the convex package be greater than 80% of the thickness of the connecting piece before stretching. This leads to a situation where, after the connecting piece is electrically connected to the terminal and the cell, the resistance of the connecting piece is typically greater than 0.5 mA, reducing the battery's electrical performance. Summary of the Invention

[0004] The purpose of this invention is to provide a stretching forming method for a connecting piece, such that the sidewall thickness of the convex bulge formed by stamping and stretching the connecting piece is more than 80% of the thickness of the connecting piece, so that the resistance after the connecting piece is electrically connected to the electrode and the battery cell is less than 0.5 mA.

[0005] To achieve this objective, the technical solution adopted by the present invention is as follows:

[0006] A stretch forming method for a connecting piece, used to stretch and form a product protrusion on a connecting piece to be processed, wherein the thickness of the connecting piece is T and the volume of the product protrusion is V, and the stretch forming method for the connecting piece includes the following steps:

[0007] S1: The connecting piece is stretched upward to form a stretching bulge, the volume of which is 1.8V-2.5V;

[0008] S2: The stretching convex hull is compressed at least twice to reduce the outer diameter and height of the stretching convex hull and form a compression convex hull, the volume of which is 1.05V-1.15V;

[0009] S3: The inclination angle of the sidewall of the compression convex humb and the height of the compression convex humb are shaped until the compression convex humb forms the product convex humb, and the sidewall of the product convex humb is T1, then 0.8T≤T1<T.

[0010] As an optional method for stretching and forming the connecting piece, in step S1, the connecting piece is stretched by a stretching mechanism, the stretching mechanism including an upper forming die and a lower forming punch arranged opposite each other, the stretching convexity being sandwiched between the upper forming die and the lower forming punch; along the radial direction of the stretching convexity, the gap between the upper forming die and the lower forming punch is T+0.1mm.

[0011] As an alternative method for stretching and forming the connecting piece, the outer diameter of the stretching bulge is greater than twice the inner diameter of the product bulge.

[0012] As an alternative to the stretching and forming method for the connecting piece, in step S2, the stretching convex bulge is squeezed three times consecutively to gradually reduce the outer diameter and height of the compression convex bulge.

[0013] As an alternative method for stretching and forming the connecting piece, in step S2, the height difference of the compression bulge after two adjacent extrusions is 0.14T-0.3T.

[0014] As an optional method for stretching and forming the connecting piece, the volume of the compression bulge after the first extrusion is 1.5V-1.7V, the volume of the compression bulge after the second extrusion is 1.3V-1.5V, and the volume of the compression bulge after the third extrusion is 1.15V-1.25V.

[0015] As an alternative to the stretching and forming method for the connecting piece, in step S3, the compression bulge is shaped twice to adjust the inclination angle of the sidewall of the compression bulge and the height of the compression bulge.

[0016] As an alternative method for stretching and forming the connecting piece, the compression convex hull is formed into a shaped convex hull after the first shaping, and the volume of the shaped convex hull is 1.05V-1.15V.

[0017] As an alternative to the stretching forming method for the connecting piece, in step S2, the inner diameter of the stretching convex bulge remains unchanged; or, according to the extrusion sequence, the inner diameter of the stretching convex bulge after the previous extrusion is not less than the inner diameter of the stretching convex bulge after the next extrusion.

[0018] As an optional method for stretching and forming the connecting piece, the thickness T of the connecting piece is 0.6mm-1.5mm.

[0019] The beneficial effects of this invention are as follows:

[0020] The stretching and forming method for the connecting piece proposed in this invention includes steps S1, S2, and S3. In step S1, the connecting piece is stretched upward to form a stretching bulge, the volume of which is 1.8V-2.5V. In step S2, the stretching bulge is compressed at least twice to reduce its outer diameter and height, forming a compression bulge, the volume of which is 1.05V-1.15V. In step S3, the inclination angle of the sidewall and the height of the compression bulge are shaped until the compression bulge forms a product bulge, and the sidewall of the product bulge is T1, where 0.8T ≤ T1 < T. Step S1 involves stretching the connecting piece to form a stretched convex bump. Step S2 involves at least two compression shrinkages of the stretched convex bump to gradually reduce its outer diameter and height. Finally, Step S3 shapes the inclination angle of the sidewalls and the height of the compressed convex bump to prevent structural springback and improve the stability of the bump structure. Ultimately, the connecting piece is stretched to form a product convex bump, and the sidewalls of the bump are more than 80% of the connecting piece thickness. This ensures that the resistance after the connecting piece is electrically connected to the terminal and the battery cell is less than 0.5 mA, thus improving the electrical performance of the battery using the connecting piece. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the connecting piece with a convex hull provided in an embodiment of the present invention;

[0022] Figure 2 This is a flowchart of the main process of the stamping and stretching method provided in the embodiments of the present invention.

[0023] The component names and labels in the diagram are as follows:

[0024] 1. Connecting piece; 11. Flat part; 12. Convex hull. Detailed Implementation

[0025] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all of them.

[0026] 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.

[0027] 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.

[0028] In the description of this embodiment, the terms "upper," "lower," "right," and "left," 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.

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] Currently, stamping and stretching processes typically involve upward or downward stretching, followed by one or two shaping steps before direct cutting. Existing stamping and stretching processes often result in a relatively small sidewall thickness for the convex package, making it difficult to meet the production requirement that the sidewall thickness of the convex package be greater than 80% of the thickness of the connecting piece before stretching. This leads to a situation where, after the connecting piece is electrically connected to the terminal and the cell, the resistance of the connecting piece is typically greater than 0.5 mA, reducing the battery's electrical performance.

[0031] like Figure 1 and Figure 2As shown, this embodiment proposes a stretch forming method for a connecting piece, used to stretch and form a product protrusion on a connecting piece 1 to be processed. The thickness of the connecting piece 1 is T, and the volume of the product protrusion is V. The connecting piece 1 includes a flat portion 11 and a protrusion 12 integrally formed with the flat portion 11. The top wall and side wall of the protrusion 12 are connected by a rounded corner transition, and the side wall of the protrusion 12 is connected to the flat portion 11 by a rounded corner transition. The outer diameter of the protrusion 12 is defined as W, which includes the sum of the diameter of the rounded corner between the side wall of the protrusion 12 and the flat portion 11 and the diameter of the top wall of the protrusion 12. The inner diameter of the protrusion 12 is defined as N, which is the actual inner diameter of the protrusion 12 minus the difference in diameter between the rounded corner between the inner top wall and the inner side wall of the protrusion 12. The height of the protrusion 12 is defined as H, which is the distance between the bottom surface of the flat portion 11 and the top wall of the protrusion 12. It should be noted that the volume of the convex hull 12 (stretch convex hull, compression convex hull, shaping convex hull and product convex hull) is the material volume of the convex hull 12.

[0032] The stretching and forming method for the connecting piece includes steps S1, S2, and S3. In step S1, the connecting piece 1 is stretched upward to form a stretching bulge, the volume of which is 1.8V-2.5V. In step S2, the stretching bulge is compressed at least twice to reduce its outer diameter and height, forming a compression bulge, the volume of which is 1.05V-1.15V. In step S3, the inclination angle of the sidewall and the height of the compression bulge are shaped until the compression bulge forms a product bulge, and the sidewall of the product bulge is T1, where 0.8T ≤ T1 < T.

[0033] Step S1 stretches the connecting piece 1 to form a stretched convex bulge. Step S2 compresses and shrinks the stretched convex bulge at least twice to gradually reduce its outer diameter and height. Finally, step S3 shapes the inclination angle of the sidewall and the height of the compressed convex bulge to prevent structural springback and improve the stability of the convex bulge structure. Ultimately, the connecting piece 1 is stretched to form a convex bulge, and the sidewall of the convex bulge is more than 80% of the thickness of the connecting piece 1. This ensures that the resistance after the connecting piece 1 is electrically connected to the terminal and the battery cell is less than 0.5 mA, thus improving the electrical performance of the battery using the connecting piece 1.

[0034] In step S1, the connecting piece 1 is stretched by a stretching mechanism, which includes an upper forming die and a lower forming punch arranged opposite each other, with a stretching protrusion sandwiched between the upper forming die and the lower forming punch. The gap between the upper forming die and the lower forming punch along the radial direction of the stretching protrusion is T+0.1mm. This arrangement ensures a suitable gap between the upper forming die and the lower forming punch when stretching the connecting piece 1 upwards, resulting in a moderate sidewall thickness for the stretching protrusion, facilitating subsequent extrusion and shaping. If the gap between the upper forming die and the lower forming punch along the radial direction of the stretching protrusion is less than T+0.1mm, the sidewall thickness of the stretching protrusion may become too thin, or even break; if the gap is greater than T+0.1mm, the sidewall thickness of the stretching protrusion may become too thick.

[0035] In this embodiment, the volume of the stretched convex bump is 1.8V-2.5V, meaning the volume of the stretched convex bump is 1.8 times-2.5 times the volume of the final product convex bump. Preferably, the volume of the stretched convex bump is twice the volume of the final product convex bump. In this embodiment, the outer diameter of the stretched convex bump is greater than twice the inner diameter of the product convex bump to maximize its outer diameter, facilitating subsequent continuous extrusion and shaping to gradually reduce its outer diameter.

[0036] In step S2, the stretching convex humb is subjected to three consecutive compressions, causing the outer diameter and height of the compression humb to decrease progressively. After the stretching humb undergoes the first compression, it forms a compression humb, which is then subjected to two more compressions, further compressing its outer diameter and height. Because the stretching humb undergoes three consecutive compressions, the forming efficiency of the humb 12 is ensured, while also maintaining a suitable range for the compression of its outer diameter and height dimensions in each compression.

[0037] Specifically, before each extrusion, the upper forming die and lower forming punch in the stretching mechanism must be replaced. This allows for the compression and shrinking of the outer diameter and height of the stretching protrusion through the use of upper and lower forming dies with different structures, thereby reducing the volume of the stretching protrusion. In step S2, the height difference of the compressed protrusion after two adjacent extrusions is 0.14T-0.3T. For example, in this embodiment, the thickness T of the connecting piece 1 is 1mm, so the height difference of each extruded compressed protrusion can be 0.14mm-0.3mm. By setting an appropriate height difference, excessive reduction in the height of the compressed protrusion can prevent deformation of its sidewalls, while excessive reduction can prevent an increase in the number of extrusions, thus reducing the forming efficiency of the protrusion 12.

[0038] In step S2, the volume of the compression bulge needs to be compressed to 1.05-1.15 times the volume of the product bulge after three compressions. Specifically, the volume of the compression bulge after the first compression is 1.5V-1.7V, the volume after the second compression is 1.3V-1.5V, and the volume after the third compression is 1.15V-1.25V. Through the above settings, the outer diameter and height of the compression bulge are compressed successively, thereby gradually reducing the volume of the compression bulge to facilitate subsequent shaping steps.

[0039] In step S3, the compression bulge is shaped twice to adjust the inclination angle of its sidewalls and the height of the compression bulge. Through these two shaping operations, the inclination angle of the sidewalls of the compression bulge is adjusted, and the height of the compression bulge is simultaneously compressed to form the product bulge. This improves the shaping effect of the compression bulge, ensures the structural stability of the product bulge formed on the connecting piece 1, and prevents deformation due to structural springback.

[0040] Specifically, before the first shaping, the upper forming die and lower forming punch within the stretching mechanism need to be replaced. This allows for adjustment of the inclination angle of the sidewalls of the compression punch and the height of the compression punch, thereby adjusting the volume of the stretched punch to match the product punch. During both shaping processes, the inner diameters of the compression punch, the shaping punch, and the product punch remain unchanged. The first shaping primarily adjusts the inclination angle of the compression punch's sidewalls to match that of the product punch, and also adjusts the height of the compression punch to match the height of the product punch. After the first shaping, the compression punch becomes the shaping punch, with a volume of 1.05V-1.15V. The second shaping primarily adjusts the inclination angle of the compression punch's sidewalls to prevent springback, ensuring that the shaping punch, after the second shaping, forms the product punch.

[0041] In step S2, the inner diameter of the stretching convex bulge remains unchanged. If the inner diameter remains constant, more material from the compression convex bulge will flow towards its sidewall during the extrusion process in step S2. In other embodiments, since the inner diameter of the compression convex bulge may change slightly during continuous extrusion, the inner diameter of the stretching convex bulge after each extrusion should not be smaller than the inner diameter of the stretching convex bulge after the next extrusion, according to the extrusion sequence. That is, the inner diameter of the bulge 12 in the preceding process cannot be smaller than the inner diameter of the bulge 12 in the subsequent process, to avoid defects such as pits on the sidewall of the bulge 12.

[0042] The thickness of the connecting piece 1 in this embodiment is 0.6mm-1.5mm. The thickness of the connecting piece 1 can be 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.46mm, or 1.5mm, etc., and the connecting piece 1 is generally made of relatively soft materials such as copper or aluminum. If the thickness of the connecting piece 1 is greater, the structural strength of the connecting piece 1 is greater, and the number of compression cycles can be appropriately reduced in step S2; if the thickness of the connecting piece 1 is smaller, the structural strength of the connecting piece 1 is smaller, and the number of compression cycles can be appropriately increased in step S2.

[0043] For ease of understanding, this embodiment uses a connecting piece 1 with a thickness of 1.35mm as an example to illustrate the processing procedure of the stamping and stretching method for the connecting piece 1:

[0044] In step S1, a connecting piece 1 with a thickness of T=1.35mm is placed between the upper forming die and the lower forming punch of the stretching mechanism to stretch the connecting piece 1 upward to form a drawstring protrusion 12. Along the radial direction of the stretching protrusion, the gap between the upper forming die and the lower forming punch is T+0.1mm. At this time, the outer diameter W of the stretching protrusion is 24.94mm, the inner diameter N is 11.95mm, the height H is 5.3mm, the sidewall T1 of the stretching protrusion is 1.2mm, the fillet radius between the top wall and the sidewall of the stretching protrusion is 3mm, and the fillet radius between the sidewall of the protrusion 12 and the flat part 11 is 3mm.

[0045] In step S2, the corresponding upper forming die and lower forming punch are replaced before the first extrusion to shrink the stretched punch into a compressed punch. At this time, the outer diameter W of the compressed punch is 19.61 mm, the inner diameter N is 11.22 mm, the height H is 5 mm, the side wall T1 of the compressed punch is 1.2 mm, the fillet radius between the top wall and the side wall of the compressed punch is 1 mm, and the fillet radius between the side wall of the compressed punch and the flat part 11 is 2 mm.

[0046] Before the second extrusion, replace the corresponding upper forming die and lower forming punch to continue extruding the compression punch. At this time, the outer diameter W of the compression punch is 17.63 mm, the inner diameter N is 11 mm, the height H is 4.8 mm, the side wall T1 of the compression punch is 1.2 mm, the fillet radius between the top wall and the side wall of the compression punch is 0.5 mm, and the fillet radius between the side wall of the compression punch and the flat part 11 is 1.3 mm.

[0047] Before the third extrusion, replace the corresponding upper forming die and lower forming punch to continue extruding the compression punch. At this time, the outer diameter W of the compression punch is 16.23 mm, the inner diameter N is 11 mm, the height H is 4.6 mm, the side wall T1 of the compression punch is 1.2 mm, the fillet radius between the top wall and the side wall of the compression punch is 0.5 mm, and the fillet radius between the side wall of the compression punch and the flat part 11 is 0.7 mm.

[0048] In step S3, before the first shaping, the corresponding upper forming die and lower forming punch are replaced to adjust the inclination angle of the sidewall of the compression punch and the height of the compression punch to form the shaped punch. At this time, the outer diameter W of the shaped punch is 15.68 mm, the inner diameter N is 10.86 mm, the height H is 4.4 mm, the sidewall T1 of the shaped punch is 1.2 mm, the fillet radius between the top wall and the sidewall of the shaped punch is 0.5 mm, and the fillet radius between the sidewall of the punch 12 and the flat part 11 is 0.5 mm.

[0049] After the first shaping is completed, a second shaping is performed on the shaping convex hull to determine the tilt angle of its sidewalls. At this point, the outer diameter W of the shaping convex hull is 15.68 mm, the inner diameter N is 10.86 mm, the height H is 4.4 mm, the sidewall T1 of the shaping convex hull is 1.2 mm, the fillet radius between the top wall and the sidewall of the shaping convex hull is 0.5 mm, and the fillet radius between the sidewall of the shaping convex hull and the flat part 11 is 0.5 mm.

[0050] The above embodiments merely illustrate the basic principles and characteristics of the present invention. The present invention is not limited to the above embodiments. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method of stretch forming a tab for stretch forming a product bulge on a tab (1) to be processed, the tab (1) having a thickness T and the product bulge having a volume V, characterized in that, The stretch forming method of the connecting sheet comprises the following steps: S1: upwardly stretching the connecting sheet (1) to stretch form a stretch protrusion on the connecting sheet (1), the volume of the stretch protrusion being 1.8V-2.5V; S2: extruding the stretch protrusion at least twice to reduce the outer diameter and height of the stretch protrusion and form a compression protrusion, the volume of the compression protrusion being 1.05V-1.15V; S3: shaping the inclination angle of the side wall of the compression protrusion and the height of the compression protrusion until the compression protrusion forms the product protrusion, and the side wall of the product protrusion is T1, then 0.8T≤T1 2. The stretch forming method of a connecting piece according to claim 1, characterized by, In step S1, the connecting sheet (1) is stretched by a stretching mechanism, the stretching mechanism comprising an upper forming concave die and a lower forming convex die oppositely arranged, the stretch protrusion being arranged between the upper forming concave die and the lower forming convex die; along the radial direction of the stretch protrusion, the gap between the upper forming concave die and the lower forming convex die is T+0.1mm.

3. The stretch forming method of a web according to claim 1, wherein The outer diameter of the stretch protrusion is greater than 2 times the inner diameter of the product protrusion.

4. The stretch forming method of a web according to claim 1, wherein In step S2, the stretch protrusion is extruded continuously for three times to gradually reduce the outer diameter and height of the compression protrusion.

5. The stretch forming method of a web according to claim 4, wherein In step S2, the height difference of the compression protrusion after two adjacent extrusions is 0.14T-0.3T.

6. The stretch forming method of a web according to claim 4, wherein The volume of the compression protrusion after the first extrusion is 1.5V-1.7V, the volume of the compression protrusion after the second extrusion is 1.3V-1.5V, and the volume of the compression protrusion after the third extrusion is 1.15V-1.25V.

7. The stretch forming method of a web according to claim 1, wherein In step S3, the compression protrusion is shaped twice to adjust the inclination angle of the side wall of the compression protrusion and the height of the compression protrusion.

8. The stretch forming method of a web according to claim 7, wherein The compression protrusion forms a shaped protrusion after the first shaping, and the volume of the shaped protrusion is 1.05V-1.15V.

9. The stretch forming method of a web according to any one of claims 1 to 8, characterized by, In step S2, the inner diameter of the stretch protrusion remains unchanged; or, according to the extrusion sequence, the inner diameter of the stretch protrusion after the last extrusion is not less than the inner diameter of the stretch protrusion after the next extrusion.

10. The stretch forming method of a web according to any one of claims 1 to 8, characterized by, The thickness T of the connecting sheet (1) is 0.6mm-1.5mm.

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