Method for manufacturing terminal component for batteries

Abstract

The present invention suppresses exposure of a high-ductility conductor layer on the inner wall surface of a bottomed hole part that is composed of a low-ductility conductor layer. Disclosed is a method for manufacturing a terminal component, the method including: a step for forming a first intermediate body 33 which has a shaft part 33C that protrudes from the center part on the low-ductility conductor layer 31B side of a cladding piece 31 which is formed by superposing and joining a high-ductility conductor layer 31A and a low-ductility conductor layer 31B in the thickness direction; a step for forming a second intermediate body 34 which has an intermediate bottomed hole part 34D, from the first intermediate body 33 by means of a punch 75 that has a first projection part which includes a flat tip part; and a step for forming a third intermediate body 35 which has a bottomed hole part 35D, from the second intermediate body 34 by means of a punch 85 that has a second projection part which includes a flat tip part. The curvature radius R1 at the outer peripheral edge of the tip part of the first projection part of the punch 75 is smaller than the curvature radius R2 of the outer peripheral edge of the tip part of the second projection part of the punch 85.

Description

Manufacturing method for battery terminal parts

[0001] The present invention relates to a method for manufacturing a battery terminal component, for example, a method for manufacturing a battery terminal component used in a secondary battery module such as a lithium ion secondary battery.

[0002] Patent Document 1 describes a lithium ion secondary battery (LIB) including a positive electrode made of aluminum foil, a negative electrode made of copper foil, a separator between the positive electrode and the negative electrode, and an electrolyte, with the positive electrode, negative electrode, separator, and electrolyte housed in a case. In the LIB, the positive electrode is connected to a positive electrode current collector inside the case, and the positive electrode current collector is electrically connected to a positive electrode terminal that penetrates the case. The positive electrode terminal is connected to a bus bar outside the case. Meanwhile, the negative electrode is connected to a negative electrode current collector inside the case, and the negative electrode current collector is electrically connected to a negative electrode terminal that penetrates the case. The negative electrode terminal is also connected to a bus bar outside the case.

[0003] In recent years, bus bars (Al bus bars) made of aluminum or aluminum alloys have been used to reduce weight. Therefore, in LIBs, a positive electrode terminal made of aluminum or an aluminum alloy is used to connect a positive electrode current collector made of aluminum or an aluminum alloy to the Al bus bar. Meanwhile, copper or a copper alloy is used for the negative electrode current collector. Therefore, Patent Document 1 describes that the portion of the negative electrode terminal that contacts the negative electrode current collector is made of copper or a copper alloy, and the portion that contacts the Al bus bar is made of aluminum or an aluminum alloy.

[0004] Specifically, the negative electrode terminal of Patent Document 1 has a shaft portion, a flange portion extending radially from the shaft portion, and a blind hole portion provided at one end of the shaft portion. The terminal is composed of a clad material in which a high-ductility conductor layer made of aluminum or an aluminum alloy and a low-ductility conductor layer made of copper or a copper alloy are bonded together. In Patent Document 1, the outer shape of the terminal component is formed by press-molding a two-layer clad piece made of two types of metal. Specifically, the clad material is placed in a lower mold having a recess corresponding to the shaft portion, with the low-ductility conductor layer facing downward, and is forged and pressed from the high-ductility conductor layer side by an upper mold. This forms a shaft portion with a protruding central portion on the low-ductility conductor layer side. Furthermore, a blind hole portion is formed at one end of the shaft portion, and the remaining portion of the clad material forms the flange portion, forming a battery terminal.

[0005] Japanese Patent No. 6581440

[0006] The negative electrode terminal of Patent Document 1 is crimped by, for example, bending and widening the end of the bottomed hole of the shaft in a direction perpendicular to the axial direction with the shaft penetrating the case and the negative electrode current collector inside the case from the outside to the inside of the battery case, thereby electrically connecting the negative electrode terminal to the negative electrode current collector and fixing the negative electrode current collector to the case.

[0007] When forging a two-layer clad piece, which is formed by laminating and bonding a high-ductility conductor layer and a low-ductility conductor layer in the thickness direction, a method for forming a bottomed hole in a shaft portion includes a method of plastically deforming the shaft portion by pressing a punch or the like against the tip of the shaft portion to form the bottomed hole. In this case, the high-ductility conductor layer present inside the shaft portion may undergo strain-induced plastic flow, as if pulled by the plastic flow of the low-ductility conductor layer forming the inner wall surface of the bottomed hole, and may become exposed from the inner wall surface of the bottomed hole. When the high-ductility conductor constituting the high-ductility conductor layer is, for example, aluminum, crimping a battery terminal exposed from the inner wall surface of the bottomed hole to a negative electrode current collector may result in the aluminum coming into contact with the electrolyte in the battery, causing pitting corrosion. Therefore, battery terminals with exposed aluminum from the inner wall surface of the bottomed hole must be treated as defective, resulting in a low yield rate.

[0008] The object of the present invention is to prevent the high ductility conductor constituting the high ductility conductor layer from being exposed from the inner wall surface of the bottomed hole in a manufacturing method for a battery terminal component having a clad plate formed by stacking and bonding a high ductility conductor layer and a low ductility conductor layer in the thickness direction of the clad plate, a shaft portion extending toward the low ductility conductor layer along the thickness direction of the clad plate, a flange portion extending from the shaft portion in a direction perpendicular to the thickness direction of the clad plate, and a bottomed hole portion provided on one end side of the shaft portion.

[0009] In order to solve the above problems, a first aspect of the present invention is a method for producing a terminal part for a battery, using a clad plate formed by stacking and bonding a high-ductility conductor layer and a low-ductility conductor layer having lower ductility than the high-ductility conductor layer in a thickness direction, the method having a shaft portion extending along the thickness direction of the clad plate, a flange portion extending from the shaft portion in a direction perpendicular to the thickness direction, and a bottomed hole portion provided on one end side of the shaft portion, the method comprising: a step (1) of punching the clad plate in the thickness direction to form a clad piece; a step (2) of forming a first intermediate body having the shaft portion protruding from a center portion on the low-ductility conductor layer side of the clad piece; a step (3) of using the first intermediate body to form a second intermediate body having an intermediate bottomed hole portion with a first molding die having a first convex portion including a flat tip portion; and a step (4) of using the second intermediate body to form a third intermediate body having the bottomed hole portion with a second molding die having a second convex portion including a flat tip portion. The process (3) is a process of pressing the first convex portion of the first molding die against one end side of the shaft portion of the first intermediate to plastically deform the first intermediate, thereby forming an intermediate bottomed hole portion to which the shape of the first convex portion has been transferred at one end side of the shaft portion; the process (4) is a process of pressing the second convex portion of the second molding die against the bottom surface of the intermediate bottomed hole portion of the second intermediate to plastically deform the second intermediate, thereby forming the bottomed hole portion to which the shape of the second convex portion has been transferred from the intermediate bottomed hole portion; and the method for manufacturing a terminal part is such that the radius of curvature of the outer peripheral edge portion of the tip portion of the first convex portion is smaller than the radius of curvature of the outer peripheral edge portion of the tip portion of the second convex portion.

[0010] It is preferable that the radius of curvature of the corner formed by the bottom surface of the bottomed hole portion of the third intermediate body and the inner wall portion is larger than the radius of curvature of the corner formed by the bottom surface of the intermediate bottomed hole portion of the second intermediate body and the inner wall portion.

[0011] In step (4), it is preferable to press the second convex portion of the second molding die against the second intermediate body to plastically deform the second intermediate body so that the low-ductility conductor layer fills the gap between the corner formed by the bottom surface and inner wall portion of the intermediate bottomed hole portion of the second intermediate body and the outer edge portion of the tip surface of the second convex portion of the second molding die.

[0012] In step (4), it is preferable that, at the same time as forming the intermediate bottomed hole portion in the bottomed hole portion, the other end side opposite to the one end side of the shaft portion is pressed to form the flange portion extending from the shaft portion in the perpendicular direction.

[0013] It is preferable to have a step (5) of trimming the outermost periphery of the flange to obtain the terminal component.

[0014] The steps (1) to (5) are preferably carried out by transfer press molding.

[0015] According to the present invention, because the radius of curvature of the outer peripheral edge of the tip of the first convex portion is smaller than the radius of curvature of the outer peripheral edge of the tip of the second convex portion, the radius of curvature of the corner formed by the bottom surface of the intermediate bottomed hole, to which the shape of the first convex portion is transferred, and the inner peripheral wall portion is smaller than the radius of curvature of the outer peripheral edge of the tip of the second convex portion. Therefore, when the second convex portion is pressed against the bottom surface of the intermediate bottomed hole, a gap is formed between the outer peripheral edge of the tip of the second convex portion and the bottom surface of the intermediate bottomed hole. When the second convex portion is further pressed against the bottom surface of the intermediate bottomed hole from this state, outward plastic flow occurs in the low-ductility conductor layer pressed by the outer peripheral edge of the tip of the second convex portion near the outer peripheral edge of the bottom surface of the intermediate bottomed hole, and the low-ductility conductor (e.g., copper) constituting the low-ductility conductor layer plastically flows in a direction that fills the gap between the second convex portion and the intermediate bottomed hole. On the other hand, although plastic flow also occurs in the high ductility conductor layer in a direction toward the inner wall surface of the intermediate bottomed hole, the low ductility conductor (e.g., copper) constituting the low ductility conductor layer first plastically flows toward the gap between the second convex portion and the intermediate bottomed hole, making it difficult for the high ductility conductor (e.g., aluminum) constituting the high ductility conductor layer to approach the inner wall surface of the intermediate bottomed hole. Therefore, when the bottomed hole is formed, it is possible to prevent the high ductility conductor (e.g., aluminum) constituting the high ductility conductor layer from being exposed from the inner wall surface of the bottomed hole.

[0016] 1 is a cross-sectional view of a terminal component 1 according to an embodiment of the battery terminal component of the present invention. FIG. 1 is a cross-sectional view showing a fixing portion between a case 201 and a negative electrode current collector 202 of a battery 200 by the terminal component 1. FIG. 2 is a cross-sectional view showing a step (A) of forming a clad piece 31 (see FIG. 4) from a clad plate 30. FIG. 3 is a cross-sectional view showing a state in which the clad piece 31 is placed on a die 50 serving as a lower mold. FIG. 4 is a cross-sectional view showing a step (B) of forming a convex portion that will become a shaft portion from the clad piece 31. FIG. 5 is a cross-sectional view showing a punch 55B of another form. FIG. 6 is a cross-sectional view showing an intermediate body 32 formed in step (B). FIG. 7 is a cross-sectional view showing a state in which the intermediate body 32 is placed on a die 60. FIG. 8 is a cross-sectional view showing a step (C) of extending the convex portion 32C to form a shaft portion 33C (see FIG. 10). FIG. 9 is a cross-sectional view showing a step (D) of forming an intermediate bottomed hole portion 34D (see FIG. 11) on one end side of the shaft portion 33C. FIG. 11 is a cross-sectional view showing a step (E) of forming a bottomed hole portion 35D (see FIG. 14) on one end side of the shaft portion 34C. 1 is an enlarged view of the outer peripheral edge of the tip of punch 85 and the outer peripheral edge of the bottom of intermediate bottomed hole portion 34D when punch 85 is inserted into intermediate bottomed hole portion 34D and the tip of punch 85 abuts against the bottom surface of intermediate bottomed hole portion 34D. FIG. 1 is a cross-sectional view showing the state in which punch 85 is further lowered and the bottom surface of intermediate bottomed hole portion 34D is pressed by the tip of punch 85. FIG. 2 is a cross-sectional view showing step (F) of forming a flange portion (original flange portion) by pressing the other end side of shaft portion 35D.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a battery terminal part according to the present invention will be described by way of configuration examples with reference to the drawings.

[0018] The battery terminal component according to the present invention is formed, for example, in the shape of a rivet. FIG. 1 is a cross-sectional view of a terminal component 1 according to an embodiment of the battery terminal component according to the present invention. As shown in FIG. 1, the terminal component 1 is formed in the shape of a rivet. The terminal component 1 has a shaft portion 10 extending in one direction (Z1 direction) and a flange portion 20 extending from one end of the shaft portion 10 in directions perpendicular to the shaft portion 10 (X1-X2 directions and Y1-Y2 directions perpendicular to X1-X2, Z1-Z2). One end of the shaft portion 10 is provided with a bottomed hole portion 11. The outer periphery of the shaft portion 10 is made of a low-ductility conductor. Furthermore, the flange portion 20 has a surface 21 on the opposite side (Z2 side) from the shaft portion 10 made of a high-ductility conductor, and a surface 22 on the shaft portion 10 side (Z1 side) made of a low-ductility conductor.

[0019] The highly ductile conductor preferably has a standard electrode potential similar to that of the bus bar of the lithium-ion battery. The highly ductile conductor can be made of the same material as the bus bar, such as aluminum or an aluminum alloy. Examples of aluminum include A1050 and A1100 in the A1000 series specified in JIS-H4000:2022. Examples of aluminum alloys include Al-Mn alloys in the A3000 series and Al-Mg alloys in the A5000 series, both of which are specified in the same JIS.

[0020] A low-ductility conductor is a conductor with lower ductility than a high-ductility conductor. Here, "ductility" can be evaluated, for example, by the plastic elongation at the maximum test force specified in JIS Z2241:2011. The standard electrode potential of a low-ductility conductor is preferably similar to that of the negative electrode current collector of a lithium-ion battery. The low-ductility conductor can be made of a material similar to that of the negative electrode current collector of a lithium-ion battery, such as copper or a copper alloy. Examples of copper include C1020 and C1100 specified in JIS-H3100:2018. Examples of copper alloys include C1441, C1921, C1940, and C7250, all of which are specified in the same JIS.

[0021] 2 is a cross-sectional view showing a portion where a terminal component 1 fixes a case 201 and a negative electrode current collector 202 of a battery 200. As shown in FIG. 2 , a shaft portion 10 of the terminal component 1 penetrates the case 201 and the negative electrode current collector 202 therein from the outside (Z2 side) of the case 201 of the battery 200 toward the inside (Z1 side) of the case 201. Inside the case 201 (Z1 side), the terminal component 1 is crimped by bending and widening the end of the bottomed hole portion 11 of the shaft portion 10 in directions (X1-X2 directions and Y1-Y2 directions) perpendicular to the axial direction (Z1 direction). In this state, the terminal component 1 is electrically connected to the negative electrode current collector 202 and fixes the negative electrode current collector 202 to the case 201. In addition, a packing 207 is provided between the flange 20 of the terminal part 1 and the case 201, and a packing 208 is provided between the case 201 and the negative electrode current collector 202. The packings 207 and 208 prevent the electrolyte from leaking from the battery 200.

[0022] 2, when the terminal component 1 is crimped, the surface 21 of the flange portion 20 of the terminal component 1 on the side opposite to the shaft portion 10 (Z2 side) is in contact with and electrically connected to the bus bar 209. The battery 200 is connected to other batteries and external electronic devices (not shown) via the bus bar 209.

[0023] Hereinafter, a method for manufacturing a battery terminal component according to an embodiment of the present invention will be described with reference to the drawings as appropriate, using the above-described method for manufacturing the terminal component 1 as an example.

[0024] A manufacturing method of a terminal component 1 according to an embodiment of the manufacturing method of a battery terminal component of the present invention includes the following steps (1) to (5): (1) forming a clad piece from a clad plate, (2) forming a first intermediate having a shaft portion from the clad piece, (3) forming a second intermediate having an intermediate bottomed hole portion from the first intermediate, (4) forming a third intermediate having a bottomed hole portion from the second intermediate, and (5) trimming the flange portion to obtain a terminal component.

[0025] The above step (2) includes the following two steps: (2-1) a step of forming a convex portion that will become a shaft portion from the clad piece; and (2-2) a step of extending the convex portion to form a shaft portion.

[0026] Furthermore, the above step (4) may include the following step (4-2) in addition to the following step (4-1). Note that the steps (4-1) and (4-2) may be performed simultaneously. (4-1) A step of forming a bottomed hole on one end of the shaft portion. (4-2) A step of forming a flange by pressing the other end of the shaft portion.

[0027] The above steps (1) to (5) are preferably carried out by transfer press molding. Each step will be described below.

[0028] (1) Step of forming clad pieces from a clad plate FIG. 3 is a cross-sectional view illustrating step (A) of forming clad pieces 31 (see FIG. 4) from a clad plate 30. As shown in FIG. 3, the clad plate 30 is formed by stacking and bonding a high-ductility conductor layer 30A and a low-ductility conductor layer 30B, which has lower ductility than the high-ductility conductor layer 30A, in the thickness direction (Z1, Z2 directions). The high-ductility conductor layer 30A is a layer made of a conductor having a standard electrode potential similar to that of a battery bus bar. For example, aluminum or an aluminum alloy can be used for the high-ductility conductor layer 30A. The low-ductility conductor layer 30B is a layer made of a conductor having lower ductility than the high-ductility conductor and a standard electrode potential similar to that of a negative electrode current collector of a battery. For example, copper or a copper alloy can be used for the low-ductility conductor layer 30B.

[0029] To form the clad pieces 31 (see FIG. 4 ) from the clad plate 30, as shown in FIG. 3 , a press machine or the like is used to place the clad plate 30 above (Z1 side) a die 40 having a hole 41 of a predetermined shape, and a punch 42 having a predetermined shape is lowered from above (Z1 side) to perform a punching process. The predetermined shape here refers to a shape corresponding to the shape of the clad piece 31. This allows the clad piece 31 to be produced from the clad plate 30. In this case, as shown in FIG. 3 , a guide 43 for guiding the punch 42 may be provided. Note that FIG. 3 shows a configuration in which punching is performed with the clad plate 30 positioned so that the high ductility conductor layer 30A contacts the die 40, but punching may also be performed with the clad plate 30 positioned so that the low ductility conductor layer 30B contacts the die 40.

[0030] 4 and 5 are cross-sectional views for explaining the step (2-1) of forming the convex portion 32C (see FIG. 7) that will become the shank 33C (see FIG. 10) from the clad piece 31. FIG. 4 shows the step (2-1) of placing the clad piece 31 in the die 50. FIG. 5 shows the step (2-1) of forming the convex portion 32C that will become the shank 33C from the clad piece 31.

[0031] First, as shown in FIG. 4 , when a clad piece 31 formed by punching a clad plate 30 in the thickness direction (Z2 direction) is placed in a die 50 serving as a lower mold, the clad piece 31 is placed so that the high ductility conductor layer 31A contacts the bottom surface 52 of a vertical hole portion 51 that opens upward (toward the Z1 side) in the die 50. At this time, the inner peripheral wall of the vertical hole portion 51 of the die 50 is positioned slightly outward from the outer peripheral end surface (side surface perpendicular to the Z1 and Z2 directions) of the clad piece 31. Therefore, the inner peripheral wall 53 of the vertical hole portion 51 of the die 50 and the outer peripheral end surface of the clad piece 31 are close to each other and form a clearance fit, so that the outer peripheral end surface (side surface perpendicular to the Z1 and Z2 directions) and the lower surface (surface on the Z2 side) of the high ductility conductor layer 31A are constrained by the die 50. Note that the die 50 is an example of a lower mold in the present invention.

[0032] 5, when punch 55A serving as an upper mold is inserted into vertical hole 51 of die 50 to press the upper surface (surface on the Z1 side) of low ductility conductor layer 31B of clad piece 31, punch 55A presses low ductility conductor layer 31B of clad piece 31 from the outer periphery of the upper surface with convexity-forming recess 56 that opens downward (to the Z2 side) and extends upward (to the Z1 side) to form convexity 32C (see FIG. 7) that becomes shank 10 at the center in directions (X1-X2 directions and Y1-Y2 directions) perpendicular to the thickness direction of clad piece 31. As a result, plastic deformation of the outer periphery side surface (surface perpendicular to the Z1-Z2 directions) of clad piece 31 is constrained by inner circumferential wall 53 of vertical hole 51 of die 50, and clad piece 31 is plastically deformed toward convexity-forming recess 56, whereby convexity 32C can be formed inside convexity-forming recess 56. The punch 55A is an example of the upper die in the present invention.

[0033] Punch 55A has a convex-forming recess 56 that opens downward (toward the Z2 side) and extends upward (toward the Z1 side) at the center in directions (X1-X2 and Y1-Y2 directions) orthogonal to its axial direction (Z1-Z2 directions). The axial direction of punch 55A corresponds to the thickness direction of the clad plate 30 and the clad pieces 31. The direction orthogonal to the axial direction of punch 55A corresponds to the direction orthogonal to the thickness direction of the clad plate 30 and the clad pieces 31. In punch 55A, convex-forming recess 56 may be configured as a hole that penetrates in the up-down direction (Z1-Z2 directions), or as a non-penetrating recess.

[0034] As described above, by pressing the low-ductility conductor layer 31B of the clad piece 31 with the punch 55A while constraining the plastic deformation of the outer peripheral side surface (surface perpendicular to the Z1 and Z2 directions) of the clad piece 31 with the inner peripheral wall 53 of the vertical hole portion 51 of the die 50, the clad piece 31 can be plastically deformed toward the convex-forming recess 56 of the punch 55A. In the thickness direction (Z1 and Z2 directions) of the clad piece 31, the stress acting on the central portion of the clad piece 31 due to the pressing of the convex-forming recess 56 of the punch 55A is smaller than the stress acting on the outer edge portion of the clad piece 31. Therefore, the low-ductility conductor layer 31B is more likely to plastically flow toward the central portion of the clad piece 31, and the generation of burrs due to distorted plastic flow of the low-ductility conductor layer 31B on the upper surface (Z1 side) of the outer edge portion of the clad piece 31 can be suppressed.

[0035] 5, the inner peripheral edge of the convex-forming recess 56 of the punch 55A is preferably provided with an inclined surface 57 that is inclined upward (toward the Z1 side) toward the inside (the center of the clad piece 31). By providing the inclined surface 57 on the inner peripheral edge of the convex-forming recess 56 of the punch 55A, the low-ductility conductor layer 31B can be plastically flowed upward (toward the Z1 side) along the inclined surface 57 inside the convex-forming recess 56.

[0036] The gradient of the inclined surface 57 of the convex-forming recess 56 of the punch 55A relative to the bottom surface 52 of the vertical hole 51 of the die 50 preferably increases toward the inside (the center of the clad piece 31). That is, assuming a tangent surface to the inclined surface 57, the angle between the outer peripheral surface of the punch 55A and the tangent surface to the inclined surface 57 is preferably less than 90 degrees and gradually decreases from the outer peripheral side of the punch 55A toward the inside (the center of the clad piece 31). In practice, in a cross section (cross section shown in FIG. 5 ) taken along the axial direction (Z1, Z2 directions) of the punch 55A, the angle between the line indicating the outer peripheral surface of the punch 55A and the line (tangent) indicating the tangent surface to the inclined surface 57 is preferably less than 90 degrees and gradually decreases from the outer peripheral side of the punch 55A toward the inside (the center of the clad piece 31). When the gradient of the inclined surface 57 increases toward the inside (the center of the clad piece 31), the stress acting on the clad piece 31 due to pressing decreases from the outer edge portion toward the center portion of the clad piece 31. This makes it easier for the plastic flow of the clad piece 31 to move toward the center in the X direction (the center of the clad piece 31), making it easier to cause the low-ductility conductor layer 31B to plastically flow toward the convex-forming recess 56. When pressing the clad piece 31 with the punch 55A, a guide 59 may be used to guide the punch 55A in the up and down directions (Z1 and Z2 directions).

[0037] Although the punch 55A shown in Figure 5 has an inclined surface 57 whose slope increases continuously toward the center of the clad piece 31, punches of other shapes, such as punch 55B shown in Figure 6, may also be used.

[0038] FIG. 6 is a cross-sectional view showing another embodiment of a punch 55B. As shown in FIG. 6, the punch 55B has a shape different from that of the punch 55A shown in FIG. 5. The punch 55B has multiple inclined surfaces 57A, 57B, 57C, and 57D that continue from the outer periphery of its lower end toward the inside (the center of the clad piece 31). The inclined surfaces 57A to 57D continue in this order from the outer periphery toward the inside (the center of the clad piece 31). It is preferable that the gradient of the inclined surfaces 57A to 57D of the convex-forming recess 56 of the punch 55B relative to the bottom surface 52 of the vertical hole 51 of the die 50 be smallest for the inclined surface 57A, and increase in the order of the inclined surface 57B, the inclined surface 57C, and the inclined surface 57D.

[0039] Note that inclined surfaces 57A, 57B, 57C, and 57D may each be flat or curved. For example, inclined surfaces 57A, 57B, 57C, and 57D may each be conical. In this case, when the taper angles of inclined surfaces 57A, 57B, 57C, and 57D are θ1, θ2, θ3, and θ4, respectively, it is preferable that θ1 > θ2 > θ3 > θ4.

[0040] 7 is a cross-sectional view showing the intermediate body 32 formed in step (2-1) using the die 50 and punch 55A shown in FIG. 5. The intermediate body 32 can also be formed using the die 50 shown in FIG. 5 and the punch 55B shown in FIG. 7. As shown in FIG. 7, the intermediate body 32 has a high ductility conductor layer 32A and a low ductility conductor layer 32B, and a convex portion 32C is provided in the center of the low ductility conductor layer 32B side. The position of the convex portion 32C on the low ductility conductor layer 32B side corresponds to the center of the clad piece 31 on the low ductility conductor layer 32B side.

[0041] When the thickness of the high ductility conductor layer 32A at the outer peripheral edge of the intermediate body 32 is TH and the thickness of the low ductility conductor layer 32B at the outer peripheral edge of the intermediate body 32 is TL, it is preferable to satisfy TL / (TH+TL)≦0.2, and it is more preferable to satisfy TL / (TH+TL)≦0.1. That is, in step (B), it is preferable to extend the convex portion 32C into the convex-forming recess portion 56 of the punch 55A until TL / (TH+TL)≦0.2 is satisfied, and it is more preferable to extend the convex portion 32C into the convex-forming recess portion 56 of the punch 55A until TL / (TH+TL)≦0.1 is satisfied.

[0042] (2-2) Step of Forming a Shank by Extending the Convex Portion Figures 8 and 9 are cross-sectional views illustrating step (C) of extending the convex portion 32C to form a shaft portion 33C (see Figure 10). Figure 8 shows the state in which the intermediate body 32 is placed in the die 60 in step (2-2). As shown in Figure 8, in a vertical hole portion 61 of the die 60 that opens toward the upper side (Z1 side) of the die 60, the intermediate body 32 is placed so that its high ductility conductor layer 32A side is in contact with a bottom surface 62 of the vertical hole portion 61. In addition, a side surface of the intermediate body 32 in a direction perpendicular to the Z1 and Z2 directions is close to an inner peripheral wall 63 of the vertical hole portion 61 of the die 60. As a result, the Z2-side surface of the high ductility conductor layer 32A and the side surface perpendicular to the Z1 and Z2 directions are constrained by the bottom surface 62 and inner peripheral wall 63 of the vertical hole portion 61 of the die 60.

[0043] Next, the protrusion 32C of the intermediate body 32 is stretched to form the shank 33C. FIG. 9 shows the step (2-2) in which the outer periphery of the low ductility conductor layer 32B of the intermediate body 32 is pressed with a punch 65 to stretch the protrusion 32C. As shown in FIG. 9 , the punch 65 presses the outer periphery of the low ductility conductor layer 32B of the intermediate body 32 from above (the Z1 side) the vertical hole 61 of the die 60. The punch 65 has a shank-forming recess 66 on its inner side (at the center of the clad piece 31) that opens downward (to the Z2 side) and extends upward (to the Z1 side). The shank-forming recess 66 may be configured as a hole that penetrates the punch 65 in the vertical direction (the Z1-Z2 direction), or may be configured as a non-through hole. By pressing the outer periphery of the low-ductility conductor layer 32B of the intermediate body 32 with the punch 65, the plastic deformation of the side surfaces of the clad piece 31 in the X1 and X2 directions is constrained by the inner peripheral wall 63 of the vertical hole 61 of the die 60, while the convex portion 32C of the intermediate body 32 is plastically deformed toward the Z1 side inside the shank-forming recess 66, thereby forming the shank 33C (see FIG. 10 ) inside the shank-forming recess 66. At this time, the stress acting on the central portion of the intermediate body 32 due to the pressing is smaller than that acting on the outer edge portion, so the low-ductility conductor layer 32B is more likely to plastically flow toward the center in the direction perpendicular to the thickness direction. This makes it possible to suppress the generation of burrs in the low-ductility conductor layer 32B.

[0044] 9 , the inner peripheral edge of the shank-forming recess 66 of the punch 65 is preferably provided with an inclined surface 67 that is inclined upward (toward the Z1 side) toward the inside (the center of the clad piece 31). The provision of the inclined surface 67 allows the low-ductility conductor layer 32B to more smoothly plastically flow upward (toward the Z1 side) within the shank-forming recess 66 along the inclined surface 67. Note that when pressing the intermediate body 32 with the punch 65, a guide 69 may be used to guide the punch 65 in the up-down direction (Z1 and Z2 directions).

[0045] (3) Step of Forming an Intermediate Bottomed Hole on One End of the Shank Figure 10 is a cross-sectional view illustrating step (3) of forming an intermediate bottomed hole 34D (see Figure 11) on one end of the shaft 33C. Figure 10 shows the state in step (3) in which the intermediate 33 (first intermediate) formed in step (2-2) is placed in a die 70. As shown in Figure 10, the intermediate 33 formed in step (2-2) is placed in a vertical hole 71 that opens upward (to the Z1 side) of the die 70, with the shaft 33C facing upward (to the Z1 side) and the high ductility conductor layer 33A side in contact with the bottom surface 72 of the vertical hole 71. Furthermore, the side surface of the intermediate 33 perpendicular to the Z1 and Z2 directions is close to the inner peripheral wall 73 of the vertical hole 71 of the die 70. As a result, the Z2 side surface and the side surface perpendicular to the Z1 and Z2 directions of the highly ductile conductor layer 33A are constrained by the bottom surface 72 and inner peripheral wall 73 of the vertical hole portion 71 of the die 70.

[0046] Next, as shown in Figure 10, punch 75 (first molding die) having a substantially flat tip portion (first convex portion) at its tip is lowered from above (Z1 side) to below (Z2 side) vertical hole portion 71 of die 70, and the tip portion of punch 75 presses against the tip portion of shank 33C. As a result, intermediate bottomed hole 34D (see Figure 11), to which the shape of the tip portion of punch 75 has been transferred, is formed at the tip portion of shank 33C. Here, if the radius of curvature of the outer peripheral edge of the tip portion (first convex portion) of punch 75 is R1, the radius of curvature of the outer peripheral edge of the bottom of intermediate bottomed hole 34D will be the same as R1 or a radius of curvature R1' (see Figure 11) that is slightly larger than R1.

[0047] (4-1) Step of forming a bottomed hole portion on one end side of the shaft portion Figure 11 is a cross-sectional view for explaining step (4-1) of forming a bottomed hole portion 34D on one end side (Z1 side) of the shaft portion 34C having the intermediate bottomed hole portion 34D of the intermediate body 34. As shown in Figure 11, in step (4-1), the intermediate body 34 (second intermediate body) obtained in step (3) is placed in a vertical hole portion 81 that opens upward (Z1 side) of the die 80 so that the intermediate bottomed hole portion 34D of the intermediate body 34 faces upward (Z1 side) and the high ductility conductor layer 34A side is in contact with the bottom surface 82 of the vertical hole portion 81 of the die 80. In addition, the side surface of the intermediate body 34 in the direction perpendicular to the Z1 and Z2 directions is close to the inner peripheral wall 83 of the vertical hole portion 81 of the die 80. As a result, the Z2 side surface and the side surface perpendicular to the Z1 and Z2 directions of the highly ductile conductor layer 34A are constrained by the bottom surface 82 and inner peripheral wall 83 of the vertical hole portion 81 of the die 80.

[0048] Next, as shown in FIG. 11 , a punch 85 (second molding die) having a substantially flat tip portion (second convex portion) at its tip is lowered from above (Z1 side) to below (Z2 side) the vertical hole portion 81 of the die 80, inserting the tip portion of the punch 85 into the intermediate bottomed hole portion 34D, and then the punch 85 is further lowered to press the intermediate body 34. This forms a bottomed hole portion 35D (see FIG. 14 ) to which the shape of the tip portion of the punch 85 is transferred. Here, if the radius of curvature of the outer peripheral edge of the tip portion (first convex portion) of the punch 85 is R2, the radius of curvature of the outer peripheral edge of the bottom of the bottomed hole portion 35D is a radius of curvature R2′ (see FIG. 14 ) that is the same as or slightly larger than R2.

[0049] 12, it is preferable that the radius of curvature R1' of the outer peripheral edge of the bottom surface of intermediate bottomed hole 34D is smaller (R1'<R2) than the radius of curvature R2 of the outer peripheral edge of the tip of punch 85. Therefore, it is preferable that the radius of curvature R1 of the outer peripheral edge of the tip (first convex portion) of punch 75 shown in FIG. 10 used in step (3) is smaller (R1<R2) than the radius of curvature R2 of the outer peripheral edge of the tip (second convex portion) of punch 85 shown in FIG. 11 used in step (4-1).

[0050] 12 is an enlarged view of the outer peripheral edge of the tip of punch 85 and the outer peripheral edge of the bottom of intermediate bottomed hole portion 34D when punch 85 is inserted into intermediate bottomed hole portion 34D and the tip face of punch 85 abuts against the bottom face of intermediate bottomed hole portion 34D. When the tip of punch 85 abuts against the bottom face of intermediate bottomed hole portion 34D, if R1'<R2, a gap will form between punch 85 and intermediate bottomed hole portion 34D, as shown in FIG.

[0051] 12 , where there is a gap between punch 85 and intermediate bottomed hole portion 34D, punch 85 is further lowered downward (toward Z2), and the bottom surface of intermediate bottomed hole portion 34D is pressed by the tip of punch 85. As a result, as shown in Fig. 13 , outward plastic flow (in the direction of arrow B in Fig. 13 ) occurs in low ductility conductor layer 34B pressed by the outer peripheral edge of the tip of punch 85 near the outer peripheral edge of the bottom surface of intermediate bottomed hole portion 34D, and low ductility conductor layer 34B plastically flows in a direction to fill the gap between punch 85 and intermediate bottomed hole portion 34D. Meanwhile, although plastic flow also occurs in the high ductility conductor layer 34A in a direction toward the inner wall surface of the intermediate bottomed hole portion 34D (the direction of arrow A in FIG. 13 ), the low ductility conductor layer 34B plastically flows first toward the gap between the punch 85 and the intermediate bottomed hole portion 34D, making it difficult for the high ductility conductor layer 34A to approach the inner wall surface of the intermediate bottomed hole portion 34D. Therefore, when the bottomed hole portion 35D (see FIG. 14 ) is formed, it is possible to prevent the high ductility conductor layer 34A from being exposed from the inner wall surface of the bottomed hole portion 35D, the surface of which is constituted by the low ductility conductor layer 34B.

[0052] (4-2) Step of Forming a Flange by Pressing the Other End Side of the Shank FIG. 14 is a cross-sectional view illustrating step (4-2) of forming a flange by pressing the other end side (Z2 side) of the shaft portion 35C of the intermediate body 35 (third intermediate body). The flange formed here is the original flange shape corresponding to the flange portion 20 shown in FIG. 1. As shown in FIG. 14, in step (4-2), the intermediate body 35 (third intermediate body) obtained in step (4-1) is placed on the upper surface 92 of the die 90. Specifically, the intermediate body 35 is placed on the upper surface 92 of the die 90 so that the bottomed hole portion 35D of the intermediate body 35 faces upward (Z1 side) and the high ductility conductor layer 35A side contacts the upper surface 92 of the die 90.

[0053] 14, the punch 95 is lowered from above (Z1 side) to below (Z2 side). At this time, the punch 95 is lowered toward the inclined surface on the Z1 side (the inclined surface on the outer periphery of the low-ductility conductor layer 35B) that is outer than the shank 35C of the intermediate body 35. By appropriately pressing the inclined surface on the Z1 side that is outer than the shank 35C of the intermediate body 35 with the die 90 and punch 95, the inclined surface on the outer periphery is plastically deformed toward the Z2 side, and a flange portion (original flange portion shape) is formed.

[0054] (5) Step of Trimming the Outermost Periphery of the Flange Next, as necessary, the outermost periphery of the flange (original flange form) is trimmed from the intermediate (not shown) on which the flange (original flange form) was formed in step (4-2). This completes the terminal component 1 having the shank 10, flange 20, and bottomed hole 11 shown in Figure 1. If the trimming is not performed, the flange (original flange form) formed in step (4-2) becomes the flange 20 shown in Figure 1.

[0055] As described above, in the manufacturing method of the terminal component 1 according to the embodiment of the manufacturing method of the battery terminal component of the present invention, in step (1), the clad plate 30 is punched in the thickness direction (Z1 and Z2 directions) to form the clad piece 31. Next, in step (2), an intermediate 32 (first intermediate) is formed, which has a shaft portion 32C protruding from the center of the clad piece 31 on the side of the low-ductility conductor layer 31B. Next, in step (3), the intermediate 32 (first intermediate) is used to form the intermediate 33 (second intermediate) having the intermediate bottomed hole 34D with a first molding die (punch 75) having a first convex portion including a flat tip. Next, in step (4), the intermediate 33 (second intermediate) is used to form the intermediate 35 (third intermediate) having the intermediate bottomed hole 35D with a second molding die (punch 85) having a second convex portion including a flat tip.

[0056] As described above, in step (4), when there is a gap between punch 85 and intermediate bottomed hole portion 34D (see FIG. 12), punch 85 is lowered to press the bottom surface of intermediate bottomed hole portion 34D with the tip of punch 85, causing outward plastic flow (see FIG. 13) in low ductility conductor layer 34B near the outer peripheral edge of the bottom surface of intermediate bottomed hole portion 34D, making it difficult for high ductility conductor layer 34A to approach the inner wall surface of intermediate bottomed hole portion 34D. This makes it possible to form terminal component 1 in which high ductility conductor layer 34A is unlikely to be exposed from the inner wall surface of bottomed hole portion 35D (see FIG. 14), the surface of which is formed of low ductility conductor layer 34B.

[0057] The manufacturing method of the terminal component 1 according to the embodiment of the manufacturing method of the battery terminal component of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the gist of the above embodiment. For example, the step (4) of forming a third intermediate body having a bottomed hole portion from the second intermediate body and the step (5) of trimming the flange portion to obtain the terminal component may be performed simultaneously.

[0058] The battery terminal component according to the present invention can be used by connecting it to an electrode of a lithium-ion secondary battery, for example. This application claims priority to Japanese Patent Application No. 2023-208591, filed December 11, 2023.

Claims

1. A method for manufacturing a terminal part for a battery, using a clad plate formed by stacking and bonding a high ductility conductor layer and a low ductility conductor layer having lower ductility than the high ductility conductor layer in the thickness direction, the terminal part having a shaft portion extending along the thickness direction of the clad plate, a flange portion extending from the shaft portion in a direction perpendicular to the thickness direction, and a bottomed hole portion provided on one end side of the shaft portion, the method comprising the steps of: (1) punching the clad plate in the thickness direction to form a clad piece; (2) forming a first intermediate body having the shaft portion protruding from the center of the clad piece on the low ductility conductor layer side; (3) using the first intermediate body to form a second intermediate body having an intermediate bottomed hole portion with a first molding die having a first convex portion including a flat tip portion; and (4) using the second intermediate body to form a third intermediate body having a bottomed hole portion with a second molding die having a second convex portion including a flat tip portion. The process (3) is a process of pressing the first convex portion of the first molding mold against one end side of the shaft portion of the first intermediate to plastically deform the first intermediate to form the intermediate bottomed hole portion to which the shape of the first convex portion is transferred to one end side of the shaft portion; the process (4) is a process of pressing the second convex portion of the second molding mold against a bottom surface of the intermediate bottomed hole portion of the second intermediate to plastically deform the second intermediate to form the bottomed hole portion to which the shape of the second convex portion is transferred from the intermediate bottomed hole portion; and a method for manufacturing a terminal part, wherein the radius of curvature of the outer circumferential edge of the tip portion of the first convex portion is smaller than the radius of curvature of the outer circumferential edge of the tip portion of the second convex portion.

2. A method for manufacturing a terminal part as described in claim 1, wherein the radius of curvature of the corner formed by the bottom surface and inner wall portion of the bottomed hole portion of the third intermediate body is larger than the radius of curvature of the corner formed by the bottom surface and inner wall portion of the intermediate bottomed hole portion of the second intermediate body.

3. A method for manufacturing a terminal part as described in claim 1 or 2, wherein in step (4), the second convex portion of the second molding die is pressed against the second convex portion to plastically deform the second intermediate body so that the low ductility conductor layer fills the gap between the corner formed by the bottom surface and inner wall portion of the intermediate bottomed hole portion of the second intermediate body and the outer periphery of the tip of the second convex portion of the second molding die.

4. A method for manufacturing a terminal part as claimed in any one of claims 1 to 3, wherein in step (4), the intermediate bottomed hole portion is formed in the bottomed hole portion, and at the same time, the other end side opposite to the one end side of the shaft portion is pressed to form the flange portion extending from the shaft portion in the perpendicular direction.

5. The method for manufacturing a terminal component according to claim 4, further comprising a step (5) of trimming the outermost periphery of the flange to obtain the terminal component.

6. The method for manufacturing a terminal component according to claim 5, wherein steps (1) to (5) are carried out by transfer press molding.

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