Method for manufacturing terminal component for battery

Abstract

To suppress exposure of a high-ductility conductor layer on an inner wall surface of a bottomed hole part that is composed of a low-ductility conductor layer.SOLUTION: A method for manufacturing a terminal component includes the steps of: forming a first intermediate body 33 which has a shaft portion 33C that protrudes from a center part on a low-ductility conductor layer 31B side of an individual clad piece 31 obtained by laminating and joining a high-ductility conductor layer 31A and the low-ductility conductor layer 31B in a thickness direction; 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 including a flat tip part; and 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 including a flat tip part. A curvature radius R1 at an outer peripheral edge of the tip part of the first projection part of the punch 75 is made to be smaller than a curvature radius R2 of an outer peripheral edge of the tip part of the second projection part of the punch 85.SELECTED DRAWING: Figure 12

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes a lithium ion secondary battery (LIB) including a positive electrode made of an aluminum foil, a negative electrode made of a copper foil, a separator between the positive electrode and the negative electrode, and an electrolytic solution, wherein the positive electrode, the negative electrode, the separator, and the electrolytic solution are housed in a case. In the LIB, the positive electrode is connected to a positive electrode current collector in the case, and the positive electrode current collector is electrically connected to a positive electrode terminal penetrating the case. Further, the positive electrode terminal is connected to a bus bar outside the case. On the other hand, the negative electrode is connected to a negative electrode current collector in the case, and the negative electrode current collector is electrically connected to a negative electrode terminal penetrating the case. Further, the negative electrode terminal is connected to a bus bar outside the case.

[0003] In recent years, for weight reduction, a bus bar (Al bus bar) made of aluminum or an aluminum alloy is used. Therefore, in the LIB, a positive electrode terminal made of aluminum or an aluminum alloy is used for connecting a positive electrode current collector made of aluminum or an aluminum alloy and the Al bus bar. On the other hand, copper or a copper alloy is used for the negative electrode current collector. Therefore, Patent Document 1 describes that, in the negative electrode terminal, a portion in contact with the negative electrode current collector is made of copper or a copper alloy, and a portion in contact with 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 having a radial spread in the radial direction from the shaft portion, and a bottomed hole portion provided on one end side of the shaft portion, and is composed of a clad material in which a highly ductile conductor layer made of aluminum or an aluminum alloy and a low-ductile conductor layer made of copper or a copper alloy are joined. In Patent Document 1, the outer shape of the terminal component is formed by press-molding a two-layer clad piece composed of two types of metals. Specifically, the clad material is placed in a lower mold provided with a concave portion corresponding to the shaft portion so that the low-ductile conductor layer faces downward, and is forged and pressed by an upper mold from the side of the highly ductile conductor layer. Thereby, a shaft portion in which the central portion on the side of the low-ductile conductor layer protrudes is formed. Further, a bottomed hole portion is formed on one end side of the shaft portion, and a battery terminal is formed such that the remaining portion of the clad material becomes a flange portion.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The negative electrode terminal of Patent Document 1 is caulked, for example, by bending and spreading the end portion of the bottomed hole portion of the shaft portion in a direction orthogonal to the axial direction in a state where the shaft portion penetrates the case and the negative electrode current collector in the case from the outside to the inside of the battery case. As a result, the negative electrode terminal is electrically connected to the negative electrode current collector and fixes the negative electrode current collector to the case.

[0007] By the way, when forging and pressing a clad piece having a two-layer structure in which a high-ductility conductor layer and a low-ductility conductor layer are laminated and joined in the thickness direction, as a method of forming a bottomed hole in the shaft portion, there is a method of pressing a punch or the like against the tip of the shaft portion to plastically deform the shaft portion to form a bottomed hole. At this time, the high-ductility conductor layer existing inside the shaft portion may plastically flow due to strain so as to be pulled by the plastic flow of the low-ductility conductor layer forming the inner wall surface of the bottomed hole, and may be 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, if the battery terminal exposed from the inner wall surface of the bottomed hole is caulked to the negative electrode current collector, there is a risk that aluminum comes into contact with the electrolyte in the battery and pitting corrosion occurs. Therefore, a battery terminal in which aluminum is exposed from the inner wall surface of the bottomed hole needs to be treated as a defective product, and the yield rate decreases.

[0008] An object of the present invention is to provide a method for manufacturing a battery terminal component having a shaft portion extending toward the low-ductility conductor layer side along the thickness direction of a clad plate, a flange portion extending from the shaft portion in a direction orthogonal to the thickness direction of the clad plate, and a bottomed hole portion provided on one end side of the shaft portion, the method being formed of a clad plate in which a high-ductility conductor layer and a low-ductility conductor layer having lower ductility than the high-ductility conductor layer are laminated and joined in the thickness direction, and suppressing the exposure of the high-ductility conductor constituting the high-ductility conductor layer from the inner wall surface of the bottomed hole portion.

Means for Solving the Problems

[0009] To solve the above problems, a first aspect of the present invention uses a clad plate in which a high-ductility conductor layer and a low-ductility conductor layer having lower ductility than the high-ductility conductor layer are laminated and joined in the thickness direction, and has a shaft portion extending along the thickness direction of the clad plate, a flange portion extending from the shaft portion in a direction orthogonal to the thickness direction, and a bottomed hole portion provided on one end side of the shaft portion, and is a manufacturing method for manufacturing a battery terminal component, a step (1) of punching the clad plate in the thickness direction to form a punched clad piece; a step (2) of forming a first intermediate body having the shaft portion protruding from the central portion on the low-ductility conductor layer side of the punched clad piece; Step (3) of forming a second intermediate body having an intermediate bottomed hole portion using a first mold having a first convex portion including a flat tip portion with the use of the first intermediate body Step (4) of forming a third intermediate body having a bottomed hole portion using a second mold having a second convex portion including a flat tip portion with the use of the second intermediate body, and step (3) is a step of pressing the first convex portion of the first mold against one end side of the shaft portion of the first intermediate body to plastically deform the first intermediate body, thereby forming an intermediate bottomed hole portion in which the shape of the first convex portion is transferred to one end side of the shaft portion, step (4) is a step of pressing the second convex portion of the second mold against the bottom surface of the intermediate bottomed hole portion of the second intermediate body to plastically deform the second intermediate body, thereby forming the bottomed hole portion in which the shape of the second convex portion is transferred from the intermediate bottomed hole portion, A method for manufacturing a terminal component, wherein a radius of curvature of an outer peripheral edge portion of a tip portion of the first convex portion is smaller than a radius of curvature of an outer peripheral edge portion of a tip portion of the second convex portion.

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

[0011] In step (4), it is preferable to plastically deform the second intermediate body such that the low-ductility conductor layer fills a gap between a corner portion formed by a bottom surface and an inner peripheral wall portion of the intermediate bottomed hole portion of the second intermediate body and an outer peripheral edge portion of a tip surface of the second convex portion of the second mold when the second convex portion of the second mold is pressed.

[0012] In step (4), it is preferable to form the flange portion extending in the orthogonal direction from the shaft portion by pressing the other end side of the shaft portion opposite to the one end side simultaneously with forming the intermediate bottomed hole portion into the bottomed hole portion.

[0013] Preferably, there is a step (5) of trimming an outermost peripheral portion of the flange portion to obtain the terminal component.

[0014] It is preferable to perform the above steps (1) to (5) by transfer press forming.

Advantages of the Invention

[0015] According to the present invention, since 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 and the inner peripheral wall portion of the intermediate bottomed hole portion onto which the shape of the first convex portion is transferred 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 portion, a gap is generated between the outer peripheral portion of the bottom surface of the intermediate bottomed hole portion and the outer peripheral edge of the tip of the second convex portion. From this state, when the second convex portion is further pressed against the bottom surface of the intermediate bottomed hole portion, an outward plastic flow occurs in the low-ductility conductor layer pressed by the outer peripheral edge of the tip of the second convex portion in the vicinity of the outer peripheral edge of the bottom surface of the intermediate bottomed hole portion, and the low-ductility conductor (for example, copper) constituting the low-ductility conductor layer plastically flows in a direction to fill the gap between the second convex portion and the intermediate bottomed hole portion. On the other hand, although a plastic flow also occurs in the high-ductility conductor layer in the direction toward the inner wall surface of the intermediate bottomed hole portion, since the low-ductility conductor (for example, copper) constituting the low-ductility conductor layer plastically flows toward the gap between the second convex portion and the intermediate bottomed hole portion first, it becomes difficult for the high-ductility conductor (for example, aluminum) constituting the high-ductility conductor layer to approach the inner wall surface of the intermediate bottomed hole portion. Therefore, when the bottomed hole portion is formed, it is possible to prevent the high-ductility conductor (for example, aluminum) constituting the high-ductility conductor layer from being exposed from the inner wall surface of the bottomed hole portion.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the battery terminal component according to the present invention will be described with reference to the drawings by giving configuration examples.

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

[0019] The high-ductility conductor preferably has a standard electrode potential comparable to that of the bus bar of a lithium-ion battery. As the high-ductility conductor, the same material as that of the bus bar can be used. For example, aluminum or an aluminum alloy can be used. Examples of aluminum include A1050 and A1100 of the 1000 series defined in JIS-H4000:2022. Examples of aluminum alloys include Al-Mn-based alloys of the 3000 series and Al-Mg-based alloys of the 5000 series defined by the same JIS standard.

[0020] The low-ductility conductor is a conductor having lower ductility than the high-ductility conductor. Here, the "ductility" can be evaluated, for example, by the plastic elongation at the maximum test force defined in JISZ2241:2011. The standard electrode potential of the low-ductility conductor is preferably comparable to that of the negative electrode current collector of a lithium-ion battery. As the low-ductility conductor, the same material as that of the negative electrode current collector of a lithium-ion battery can be used. For example, copper or a copper alloy can be used. Examples of copper include C1020 and C1100 defined in JIS-H3100:2018. Examples of copper alloys include C1441, C1921, C1940, and C7250 defined by the same JIS standard.

[0021] FIG. 2 is a cross-sectional view showing a fixing portion of the terminal component 1 between the case 201 of the battery 200 and the negative electrode current collector 202. As shown in FIG. 2, the shaft portion 10 of the terminal component 1 penetrates the case 201 of the battery 200 and the negative electrode current collector 202 inside the case 201 from the outside (Z2 side) to the inside (Z1 side) of the case 201. Then, inside the case 201 (Z1 side), the terminal component 1 is caulked by bending and spreading the end portion of the bottomed hole portion 11 of the shaft portion 10 in the direction orthogonal to the axial direction (Z1 direction) (X1, X2 directions and Y1, Y2 directions). 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. Further, a packing 207 is provided between the flange portion 20 of the terminal component 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 suppress the leakage of the electrolytic solution inside the battery 200.

[0022] As shown in FIG. 2, in the state where the terminal component 1 is caulked, the surface 21 on the side opposite to the shaft portion 10 (Z2 side) of the flange portion 20 of the terminal component 1 is in contact with the bus bar 209 and is electrically connected. Note that the battery 200 is connected to other batteries (not shown) and external electronic devices 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, taking the method for manufacturing the terminal component 1 described above as an example.

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

[0025] Incidentally, the above step (2) has the following two steps. (2-1) Step of forming a convex portion that becomes a shaft portion from a clad piece (2-2) Step of forming a shaft portion by stretching the convex portion

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

[0027] The above steps (1) to (5) are preferably performed by transfer press forming. Hereinafter, each step will be described.

[0028] (1) Step of forming clad pieces from a clad plate FIG. 3 is a cross-sectional view for explaining a 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 laminating and joining a high-ductility conductor layer 30A and a low-ductility conductor layer 30B having 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 comparable to that of a bus bar of a battery. For the high-ductility conductor layer 30A, for example, aluminum or an aluminum alloy can be used. The low-ductility conductor layer 30B is a layer made of a conductor having lower ductility than the high-ductility conductor and having a standard electrode potential comparable to that of a negative electrode current collector of a battery. For the low-ductility conductor layer 30B, for example, copper or a copper alloy can be used.

[0029] To form the clad pieces 31 (see FIG. 4) from the clad plate 30, punching is performed using a press machine or the like. As shown in FIG. 3, the clad plate 30 is placed on the die 40 having a hole 41 of a predetermined shape (on the Z1 side), and a punch 42 having a predetermined shape is lowered from above (the Z1 side). Here, the predetermined shape is intended to be a shape corresponding to the shape of the clad piece 31. Thereby, the clad piece 31 can be produced from the clad plate 30. At this time, as shown in FIG. 3, a guide 43 for guiding the punch 42 may be provided. In FIG. 3, a configuration is shown in which punching is performed with the clad plate 30 arranged so that the highly ductile conductor layer 30A contacts the die 40, but a configuration in which punching is performed with the clad plate 30 arranged so that the low ductility conductor layer 30B contacts the die 40 may also be used.

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

[0031] First, as shown in FIG. 4, when arranging the clad piece 31 formed by punching the clad plate 30 in the thickness direction (Z2 direction) in the die 50 serving as the lower die, in the die 50, the clad piece 31 is arranged so that the highly ductile conductor layer 31A contacts the bottom surface 52 of the vertical hole portion 51 that opens upward (the Z1 side). At this time, the inner peripheral wall of the vertical hole portion 51 of the die 50 is arranged slightly outside the outer peripheral end surface (the side surface in the direction orthogonal to the Z1 and Z2 directions) of the clad piece 31. For this reason, 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 in a clearance fit state, so that the outer peripheral end surface (the side surface in the direction orthogonal to the Z1 and Z2 directions) and the lower surface (the surface on the Z2 side) of the highly ductile conductor layer 31A are constrained by the die 50. Note that the die 50 is an example of the lower die in the present invention.

[0032] Next, as shown in FIG. 5, when the punch 55A serving as the upper die is inserted into the vertical hole portion 51 of the die 50 and presses the upper surface (the surface on the Z1 side) of the low-ductility conductor layer 31B of the clad piece 31, in the punch 55A, a convex portion 32C (see FIG. 7) serving as the shaft portion 10 is formed at the center in the direction orthogonal to the thickness direction of the clad piece 31 (the X1, X2 directions and the Y1, Y2 directions). By means of the concave portion 56 for forming the convex portion that opens downward (Z2 side) and extends upward (Z1 side), the low-ductility conductor layer 31B of the clad piece 31 is pressed from the outer peripheral portion of the upper surface. As a result, while the plastic deformation of the outer peripheral side surface (the surface in the direction orthogonal to the Z1 and Z2 directions) of the clad piece 31 is restricted by the inner peripheral wall 53 of the vertical hole portion 51 of the die 50, the clad piece 31 is plastically deformed toward the concave portion 56 for forming the convex portion, and the convex portion 32C can be formed inside the concave portion 56 for forming the convex portion. Note that the punch 55A is an example of the upper die in the present invention.

[0033] The punch 55A has a concave portion 56 for forming a convex portion that opens downward (Z2 side) and extends upward (Z1 side) at the center in the direction orthogonal to its axial direction (the Z1, Z2 directions). Note that the axial direction of the punch 55A corresponds to the thickness direction of the clad plate 30 and the clad piece 31. Also, the direction orthogonal to the axial direction of the punch 55A corresponds to the direction orthogonal to the thickness direction of the clad plate 30 and the clad piece 31. The concave portion 56 for forming the convex portion in the punch 55A may be configured as a hole penetrating in the vertical direction (the Z1, Z2 directions), or may be configured as a non-penetrating concave portion.

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

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

[0036] It is preferable that the gradient of the inclined surface 57 of the concave portion 56 for forming the convex portion of the punch 55A with respect to the bottom surface 52 of the vertical hole portion 51 of the die 50 increases toward the inside (the center of the clad individual piece 31). That is, assuming a tangent plane to the inclined surface 57, the angle formed by the outer peripheral surface of the punch 55A and the tangent plane to the inclined surface 57 is less than 90 degrees, and it is preferable that the angle gradually decreases from the outer peripheral side of the punch 55A toward the inside (the center of the clad individual piece 31). Actually, in a cross-section along the axial direction (Z1, Z2 directions) of the punch 55A (the cross-section shown in FIG. 5), the angle formed by the line indicating the outer peripheral surface of the punch 55A and the line (tangent line) indicating the tangent plane of the inclined surface 57 is less than 90 degrees, and it is preferable that the angle gradually decreases from the outer peripheral side of the punch 55A toward the inside (the center of the clad individual piece 31). When the gradient of the inclined surface 57 increases toward the inside (the center of the clad individual piece 31), the stress acting on the clad individual piece 31 due to pressing decreases as it goes from the outer edge portion to the central portion of the clad individual piece 31. For this reason, the plastic flow of the clad individual piece 31 tends to be directed toward the center in the X direction (the center of the clad individual piece 31), and it becomes easier to plastically flow the low-ductility conductor layer 31B toward the concave portion 56 for forming the convex portion. When pressing the clad individual piece 31 with the punch 55A, a guide 59 for guiding the punch 55A in the vertical direction (Z1, Z2 directions) may be used.

[0037] Note that the punch 55A shown in FIG. 5 has an inclined surface 57 whose gradient continuously increases toward the center of the clad individual piece 31, but a punch having another shape, for example, a punch having a shape like the punch 55B shown in FIG. 6, may be used.

[0038] FIG. 6 is a cross-sectional view showing another form of the punch 55B. As shown in FIG. 6, the punch 55B has a different shape from the punch 55A shown in FIG. 5. The punch 55B has a plurality of inclined surfaces 57A, 57B, 57C, 57D that are continuous from the outer peripheral portion at the lower end thereof toward the inside (the center of the clad piece 31). The inclined surfaces 57A to 57D are continuous in the order of the inclined surfaces 57A, 57B, 57C, 57D from the outer peripheral portion toward the inside (the center of the clad piece 31). It is preferable that the gradients of the inclined surfaces 57A to 57D of the concave portion 56 for forming the convex portion of the punch 55B with respect to the bottom surface 52 of the vertical hole portion 51 of the die 50 are such that the inclined surface 57A is the smallest, and the inclined surfaces 57B, 57C, 57D increase in this order.

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

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

[0041] When the thickness of the highly ductile conductor layer 32A is TH and the thickness of the low ductility conductor layer 32B is TL at the outer peripheral edge of the intermediate body 32, 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 concave portion 56 for forming the convex portion 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 concave portion 56 for forming the convex portion of the punch 55A until TL / (TH + TL) ≤ 0.1 is satisfied.

[0042] (2-2) Step of forming a shaft portion by extending a convex portion FIGS. 8 and 9 are cross-sectional views for explaining the step (C) of forming the shaft portion 33C (see FIG. 10) by extending the convex portion 32C. FIG. 8 shows a state where the intermediate body 32 is disposed in the die 60 in step (2-2). As shown in FIG. 8, within the vertical hole portion 61 of the die 60 that opens upward (Z1 side), the intermediate body 32 is disposed such that the highly ductile conductor layer 32A side thereof is in contact with the bottom surface 62 of the vertical hole portion 61. Further, the side surfaces of the intermediate body 32 in the direction orthogonal to the Z1 and Z2 directions are close to the inner peripheral wall 63 of the vertical hole portion 61 of the die 60. Thereby, the surface on the Z2 side of the highly ductile conductor layer 32A and the side surfaces in the direction orthogonal to the Z1 and Z2 directions are constrained by the bottom surface 62 and the inner peripheral wall 63 of the vertical hole portion 61 of the die 60.

[0043] Next, the convex portion 32C of the intermediate body 32 is extended to form the shaft portion 33C. FIG. 9 shows the step of pressing the outer peripheral portion of the low-ductility conductor layer 32B of the intermediate body 32 by the punch 65 to extend the convex portion 32C in the process (2-2). As shown in FIG. 9, from above (Z1 side) of the vertical hole portion 61 of the die 60, the outer peripheral portion of the low-ductility conductor layer 32B of the intermediate body 32 is pressed by the punch 65. The punch 65 has a recess 66 for forming a shaft portion that opens downward (Z2 side) and extends upward (Z1 side) inside thereof (at the center of the clad piece 31). Note that the recess 66 for forming a shaft portion may be formed of a hole that penetrates the punch 65 in the vertical direction (Z1 and Z2 directions), or may be formed of a non-penetrating hole. By pressing the outer peripheral portion of the low-ductility conductor layer 32B of the intermediate body 32 with the punch 65, while restraining the plastic deformation of the side surfaces of the clad piece 31 in the X1 and X2 directions by the inner peripheral wall 63 of the vertical hole portion 61 of the die 60, the convex portion 32C of the intermediate body 32 is plastically deformed toward the Z1 side inside the recess 66 for forming a shaft portion, and the shaft portion 33C (see FIG. 10) can be formed inside the recess 66 for forming a shaft portion. At this time, since the stress acting on the central portion of the intermediate body 32 due to pressing becomes smaller than that on the outer edge portion, the low-ductility conductor layer 32B easily plastically flows toward the center in the direction orthogonal to the thickness direction. Therefore, the generation of burrs in the low-ductility conductor layer 32B can be suppressed.

[0044] As shown in FIG. 9, it is preferable that an inclined surface 67 inclined upward (Z1 side) toward the inside (the center of the clad piece 31) is provided on the inner peripheral edge portion of the recess 66 for forming a shaft portion of the punch 65. When the inclined surface 67 is provided, the low-ductility conductor layer 32B can be plastically flowed more smoothly upward (Z1 side) inside the recess 66 for forming a shaft portion along the inclined surface 67. Note that when pressing the intermediate body 32 with the punch 65, a guide 69 for guiding the punch 65 in the vertical direction (Z1 and Z2 directions) may be used.

[0045] (3) Step of forming an intermediate bottomed hole portion on one end side of the shaft portion FIG. 10 is a cross-sectional view for explaining step (3) of forming an intermediate bottomed hole portion 34D (see FIG. 11) on one end side of the shaft portion 33C. FIG. 10 shows a state where the intermediate body 33 (first intermediate body) formed in step (2-2) is disposed in the die 70 in step (3). As shown in FIG. 10, in the intermediate body 33 formed in the above step (2-2), the shaft portion 33C faces upward (Z1 side) in a vertical hole portion 71 that opens upward (Z1 side) of the die 70, and the high-ductility conductor layer 33A side is disposed in contact with the bottom surface 72 of the vertical hole portion 71. Further, the side surface of the intermediate body 33 in the direction orthogonal to the Z1 and Z2 directions is close to the inner peripheral wall 73 of the vertical hole portion 71 of the die 70. Thereby, the surface on the Z2 side of the high-ductility conductor layer 33A and the side surface in the direction orthogonal to the Z1 and Z2 directions are constrained by the bottom surface 72 and the inner peripheral wall 73 of the vertical hole portion 71 of the die 70.

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

[0047] (4-1) Step of forming a bottomed hole portion on one end side of the shaft portion FIG. 11 is a cross-sectional view for explaining the step (4-1) of forming a bottomed hole portion 34D at one end side (Z1 side) of a shaft portion 34C having the intermediate bottomed hole portion 34D of the intermediate body 34. As shown in FIG. 11, in step (4-1), the intermediate body 34 (second intermediate body) obtained in the above step (3) is placed in a vertical hole portion 81 that opens upward (Z1 side) above the die 80, with the intermediate bottomed hole portion 34D of the intermediate body 34 facing upward (Z1 side) and the high-ductility conductor layer 34A side in contact with the bottom surface 82 of the vertical hole portion 81 of the die 80. Also, the side surfaces of the intermediate body 34 in the direction orthogonal to the Z1 and Z2 directions are close to the inner peripheral wall 83 of the vertical hole portion 81 of the die 80. Thereby, the surface on the Z2 side of the high-ductility conductor layer 34A and the side surfaces in the direction orthogonal to the Z1 and Z2 directions are constrained by the bottom surface 82 and the 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 the tip is lowered from above (Z1 side) to below (Z2 side) the vertical hole portion 81 of the die 80, the tip portion of the punch 85 is inserted into the intermediate bottomed hole portion 34D, and the punch 85 is further lowered to press the intermediate body 34. Thereby, a bottomed hole portion 35D (see FIG. 14) having the shape of the tip portion of the punch 85 transferred thereto is formed. Here, if the radius of curvature of the outer peripheral edge portion of the tip portion (first convex portion) of the punch 85 is R2, the radius of curvature at the outer peripheral edge portion of the bottom surface of the bottomed hole portion 35D is the same as R2 or a slightly larger radius of curvature R2' (see FIG. 14).

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

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

[0051] From the state shown in FIG. 12 where there is a gap between the punch 85 and the intermediate bottomed hole portion 34D, the punch 85 is further lowered downward (toward the Z2 side), and the bottom surface of the intermediate bottomed hole portion 34D is pressed by the tip of the punch 85. As a result, as shown in FIG. 13, in the vicinity of the outer peripheral edge of the bottom surface of the intermediate bottomed hole portion 34D, plastic flow occurs in the outward direction (in the direction of arrow B in FIG. 13) in the low-ductility conductor layer 34B pressed by the outer peripheral edge of the tip of the punch 85, and the low-ductility conductor layer 34B plastically flows in a direction to fill the gap between the punch 85 and the intermediate bottomed hole portion 34D. On the other hand, although plastic flow also occurs in the high-ductility conductor layer 34A in the direction toward the inner wall surface of the intermediate bottomed hole portion 34D (in the direction of arrow A in FIG. 13), since the low-ductility conductor layer 34B plastically flows toward the gap between the punch 85 and the intermediate bottomed hole portion 34D first, it becomes difficult for the high-ductility conductor layer 34A to approach the inner wall surface of the intermediate bottomed hole portion 34D. Therefore, when forming the bottomed hole portion 35D (see FIG. 14), it is possible to suppress the exposure of the high-ductility conductor layer 34A from the inner wall surface of the bottomed hole portion 35D whose surface vicinity is composed of the low-ductility conductor layer 34B.

[0052] (4-2) Step of forming a flange portion by pressing the other end side of the shaft portion FIG. 14 is a cross-sectional view for explaining the process (4-2) of forming a flange portion by pressing the other end side (Z2 side) of the shaft portion 35C of the intermediate body 35 (third intermediate body). Note that the flange portion formed here is the original flange portion corresponding to the flange portion 20 shown in FIG. 1. As shown in FIG. 14, in the process (4-2), the intermediate body 35 (third intermediate body) obtained in the above process (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 such that the bottomed hole portion 35D of the intermediate body 35 faces upward (Z1 side) and the high ductility conductor layer 35A side is in contact with the upper surface 92 of the die 90.

[0053] Next, as shown in FIG. 14, the punch 95 is lowered from above (Z1 side) toward below (Z2 side). At this time, the punch 95 is lowered toward the inclined surface on the Z1 side on the outer peripheral side of the shaft portion 35C of the intermediate body 35 (the inclined surface on the outer peripheral side of the low ductility conductor layer 35B). By appropriately pressing the inclined surface on the Z1 side on the outer peripheral side of the shaft portion 35C of the intermediate body 35 with the die 90 and the punch 95, the inclined surface on the outer peripheral side is plastically deformed toward the Z2 side, and a flange portion (original flange portion) is formed.

[0054] (5) Process of trimming the outermost peripheral portion of the flange portion Next, the outermost peripheral portion of the flange portion (original flange portion) is trimmed as necessary for the intermediate body (not shown) in which the flange portion (original flange portion) is formed in the process (4-2). Thereby, the terminal component 1 having the shaft portion 10, the flange portion 20, and the bottomed hole portion 11 shown in FIG. 1 is completed. Note that if the above trimming is not performed, the flange portion (original flange portion) formed in the process (4-2) becomes the flange portion 20 shown in FIG. 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, Z2 directions) to form clad pieces 31. Next, in step (2), an intermediate body 32 (first intermediate body) having a shaft portion 32C protruding from the central portion on the side of the low-ductility conductor layer 31B of the clad piece 31 is formed. Next, in step (3), using the intermediate body 32 (first intermediate body), an intermediate body 33 (second intermediate body) having an intermediate bottomed hole portion 34D is formed by a first molding die (punch 75) having a first convex portion including a flat tip portion. Next, in step (4), using the intermediate body 33 (second intermediate body), an intermediate body 35 (third intermediate body) having a bottomed hole portion 35D is formed by a second molding die (punch 85) having a second convex portion including a flat tip portion.

[0056] As described above, in step (4), from a state where there is a gap between the punch 85 and the intermediate bottomed hole portion 34D (see FIG. 12), the punch 85 is lowered and the bottom surface of the intermediate bottomed hole portion 34D is pressed by the tip portion of the punch 85, so that an outward plastic flow (see FIG. 13) occurs in the low-ductility conductor layer 34B in the vicinity of the outer peripheral edge portion of the bottom surface of the intermediate bottomed hole portion 34D. As a result, it becomes difficult for the high-ductility conductor layer 34A to approach the inner wall surface of the intermediate bottomed hole portion 34D. Thereby, it is possible to form the terminal component 1 in which the high-ductility conductor layer 34A is less likely to be exposed from the inner wall surface of the bottomed hole portion 35D (see FIG. 14) configured by the low-ductility conductor layer 34B near the surface.

[0057] As described above, 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. However, the present invention is not limited to the above embodiment, and various modifications are possible without changing the gist of the above embodiment. For example, step (4) of forming a third intermediate body having a bottomed hole portion from the second intermediate body and step (5) of trimming the flange portion to obtain a terminal component may be performed simultaneously.

Industrial Applicability

[0058] The battery terminal component according to the present invention can be used, for example, by connecting it to an electrode of a lithium-ion secondary battery.

Description of Symbols

[0059] 1: Terminal component 10: Shaft portion 11: Bottomed hole portion 20: Flange portion 30: Clad plate 30A, 31A, 32A, 33A, 34A, 35A: High-ductility conductor layer 30B, 31B, 32B, 33B, 34B, 35B: Low-ductility conductor layer 31: Clad piece 32, 33, 34, 35: Intermediate body 32C: Protrusion 33C, 34C, 35C: Shaft portion 34D: Intermediate bottomed hole portion 35D: Bottomed hole portion 40, 50, 60, 70, 80, 90: Die 41: Hole 42, 55A, 55B, 65, 75, 85, 95: Punch 43, 59, 69: Guide 51, 61, 71, 81: Vertical hole portion 52, 62, 72, 82: Bottom surface 53, 63, 73, 83: Inner peripheral wall 56: Concave portion for forming protrusion 57, 57A, 57B, 57C, 57D, 67: Inclined surface 66: Concave portion for forming shaft portion 92: Upper surface 200: Battery 201: Case 202: Negative electrode current collector 207, 208: Packing 209: Bus bar

Claims

1. Using a clad plate in which a highly ductile conductor layer and a low ductility conductor layer having lower ductility than the highly ductile conductor layer are laminated and joined in the thickness direction, an axial portion extending along the thickness direction of the clad plate, a flange portion extending from the axial portion in a direction orthogonal to the thickness direction, and a bottomed hole portion provided on one end side of the axial portion, a manufacturing method for manufacturing a battery terminal component, comprising: Step (1) of punching the clad plate in the thickness direction to form clad pieces; Step (2) of forming a first intermediate body having the axial portion protruding from the central portion on the low ductility conductor layer side of the clad piece; 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; Step (4) of 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, and Step (3) is a step of pressing the first convex portion of the first molding die against one end side of the axial portion of the first intermediate body to plastically deform the first intermediate body, and forming the intermediate bottomed hole portion in which the shape of the first convex portion is transferred to one end side of the axial portion; Step (4) is a step 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 body to plastically deform the second intermediate body, and forming the bottomed hole portion in which the shape of the second convex portion is transferred from the intermediate bottomed hole portion, and A method for manufacturing a terminal component, wherein the radius of curvature of the outer peripheral edge portion of the tip of the first convex portion is smaller than the radius of curvature of the outer peripheral edge portion of the tip of the second convex portion.

2. The method for manufacturing a terminal component according to claim 1, wherein the radius of curvature of the corner formed by the bottom surface and the inner peripheral 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 the inner peripheral wall portion of the intermediate bottomed hole portion of the second intermediate body.

3. In the step (4), the second intermediate body is plastically deformed such that the low-ductility conductor layer fills a gap between a corner formed by a bottom surface and an inner peripheral wall of the intermediate bottomed hole portion of the second intermediate body and an outer peripheral edge portion of a tip end portion of the second convex portion of the second mold by pressing the second convex portion of the second mold. The method for manufacturing a terminal component according to claim 2.

4. In the step (4), simultaneously with forming the bottomed hole portion in the intermediate bottomed hole portion, a flange portion extending in the orthogonal direction from the shaft portion is formed by pressing the other end side of the shaft portion opposite to the one end side. The method for manufacturing a terminal component according to any one of claims 1 to 3.

5. The method for manufacturing a terminal component according to claim 4, further comprising a step (5) of obtaining the terminal component by trimming an outermost peripheral portion of the flange portion.

6. The method for manufacturing a terminal component according to claim 5, wherein the steps (1) to (5) are performed by transfer press forming.

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