JP2019133857A - Manufacturing method of external terminal for battery - Google Patents

Abstract

To provide a manufacturing method of an external terminal for a battery capable of improving the smoothness of a joint surface and ensuring stable conductivity when welding a bus bar.SOLUTION: In a manufacturing method of an external terminal for a battery including a head to which a bus bar is joined by welding, and a shaft to which a current collector is connected, a rod-shaped material 23 cut to a predetermined length is held with a receiving piece 41 such that one end protrudes, a head is molded by pressing one end of the rod-shaped material 23 with a punch 52 having a protrusion 52b at the center of the pressing surface 52c, the head surface is finished smoothly except the center, and the bus bar is joined to the smoothly-finished head surface.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a battery external terminal manufacturing method applicable to, for example, a lithium ion battery, a nickel metal hydride battery, and the like.

  In recent years, rechargeable secondary batteries such as lithium ion batteries and nickel metal hydride batteries have been adopted as power sources for automobiles. When used as a power source for automobiles, a battery with a large capacity is required. For example, as shown in Patent Document 1, a module in which a plurality of battery cells are modularized is mounted.

  The external terminal of the battery cell is formed of, for example, an aluminum-based metal material such as aluminum or an aluminum alloy, and includes a head and a shaft that is integrally formed with the head. The shaft portion is connected to a current collector plate housed inside the battery cell.

  In addition, as a method for manufacturing an external terminal for a battery, as shown in Patent Document 2, molding by cold heading is known.

Japanese Patent No. 6258858 Japanese Patent No. 612157

  However, when the battery external terminal is formed by cold heading (header processing), the head surface partially expands due to the influence of the springback. The battery cell is modularized by connecting the external terminals to each other with a conductive bus bar, but if the smoothness of the head surface of the external terminal, which is the joint surface with the bus bar, is low, There is a problem that the adhesiveness of the resin becomes low, and stable conductivity cannot be secured.

  In addition, processing oil is used in header processing, but if the header punch is pressed while the processing oil stays on the top surface of the head, the processing oil that has lost its escape at the boundary surface between the head surface and the header punch will be removed. There is also a problem that a dent is generated on the surface of the head when pressed.

  The present invention was created in view of the above problems, and provides a method of manufacturing an external terminal for a battery that can improve the smoothness of the joint surface and ensure stable conductivity when welding a bus bar. For the purpose.

  The above-described problem is a method of manufacturing an external terminal for a battery including a head portion to which a bus bar is joined by welding and a shaft portion to which a current collector plate is connected, and a metal piece cut into a predetermined length is connected to one end The head is formed by pressing one end of the metal piece with a punch having a protrusion at the center of the pressing surface, and the head surface is smooth except for the center. It can be solved by a method of manufacturing an external terminal for a battery that finishes and joins a bus bar to the smooth-finished head surface.

  In addition, it is preferable that the protrusion part of the said punch is formed so that an outer diameter may become small from the base end side to the front end side.

  In addition, it is preferable that the side surface of the protrusion of the punch is formed as an inclined surface.

  According to the manufacturing method of the battery external terminal of the present invention, the head is formed with the punch having the protrusion provided on the pressing surface, so that the expansion of the head surface due to the influence of the springback is suppressed. Therefore, the battery external terminal excellent in the smoothness of the head surface can be manufactured.

  Also, if the head is formed using a punch with a flat pressing surface, the expanding portion generated on the head surface due to the influence of the spring back has a mountain shape. Therefore, by using a punch formed so that the outer diameter decreases from the proximal end side to the distal end side, the ridge-shaped inflated portion can be offset almost without excess, so that the smoothness of the head surface is achieved. It will be better.

  In addition, when the head is formed with a punch having a protrusion on the pressing surface, a slight recess is formed on the surface of the head. Since the head is formed by header processing using processing oil, the processing oil stays in the recess, and the remaining processing oil is pushed out by the protrusion and overflows the head surface. For this reason, there is a problem in that a dent is generated on the head surface when the overflowing processing oil is pressed by the punch. Therefore, by making the side surface of the protrusion into an inclined surface, the side surface of the recess formed by such a protrusion functions to block the processing oil so that the processing oil does not overflow from the recess. Yes.

It is a partially cutaway sectional view in front view of the battery external terminal manufactured by the battery external terminal manufacturing method of the present invention. It is a top view of the battery external terminal manufactured by the manufacturing method of the battery external terminal of this invention. It is a perspective view which shows the usage condition of the external terminal for batteries manufactured by the manufacturing method of the external terminal for batteries of this invention. It is process drawing which shows the cutting process in the manufacturing method of the external terminal for batteries of this invention. It is process drawing which shows the drawing process in the manufacturing method of the external terminal for batteries of this invention. It is process drawing which shows the preforming process in the manufacturing method of the external terminal for batteries of this invention. It is process drawing which shows the finishing process in the manufacturing method of the external terminal for batteries of this invention. It is process drawing which shows the discharge process in the manufacturing method of the external terminal for batteries of this invention. FIG. 8 is a partially cutaway cross-sectional view of the punch used in the finishing process shown in FIG. 7 when viewed from the front. FIG. 10 is a plan view of the punch shown in FIG. 9. It is a partially cutaway sectional view in front view of the battery external terminal manufactured by the method for manufacturing the battery external terminal according to another embodiment of the present invention. It is a top view of the battery external terminal manufactured by the manufacturing method of the battery external terminal which concerns on other embodiment of this invention. It is a partially cutaway sectional view of the punch used in the finishing process in the method for manufacturing the battery external terminal according to another embodiment of the present invention. It is a top view of the punch shown in FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In FIG. 1 and FIG. 2, 10 is the battery external terminal 10 manufactured by the manufacturing method of the battery external terminal which is this invention. The battery external terminal 10 is made of an aluminum-based metal material such as aluminum or an aluminum alloy, and includes a head portion 11 and a shaft portion 12 formed integrally with the head portion.

  As shown in FIG. 3, the battery external terminal 10 is used as a positive electrode terminal of a lithium ion battery 1 which is an example of a battery, and a shaft portion 12 of the battery external terminal 10 is provided inside the casing of the lithium ion battery 1. A current collecting plate (not shown) housed in is connected. In addition, by connecting the heads 11 of the battery external terminals 10 with the bus bar 2 by welding, a plurality of lithium ion batteries 1 are modularized.

  Here, the manufacturing method of the external terminal for batteries which is this invention is demonstrated based on FIG. As shown in FIGS. 4 to 8, the battery external terminal manufacturing method of the present invention includes a cutting step of cutting the wire 20 into a predetermined length, and a tip 23a of the rod-shaped material 23 cut by the cutting step. A drawing step for forming the shaft portion 12 by drawing, a pre-forming step for pre-forming the head portion 11 by pressing the other end portion 23b of the rod-shaped material 23, and another end portion 23b of the preformed rod-shaped material. Are pressed to forcibly form the head portion 11, and the battery external terminal 10 manufactured by forming the rod-shaped material 23 by the finishing step is discharged from the receiving piece.

  As shown in FIG. 4, in the cutting process, the wire 20 made of aluminum is inserted into the through hole 21 a of the cutting piece 21 and is extended until the tip of the wire 20 comes into contact with the stopper 22. In this step, the wire 20 protruding from the opening portion 21a is cut into a predetermined length to produce a rod-shaped material 23, which is an example of a metal piece. Further, the cutting of the wire 20 is performed by a cutter 24 that moves in a direction orthogonal to the axis of the wire 20 (direction indicated by arrow A).

  As shown in FIG. 5, the drawing step is a step of narrowing the tip 23 a of the rod-shaped material 23 cut by the cutting step to a small diameter using a drawing piece 31. The throttle piece 31 has a throttle hole 31a having a diameter smaller than the outer diameter of the rod-shaped material 23 and an insertion hole 31b communicating with the throttle hole 31a and having a diameter slightly larger than the outer diameter of the rod-shaped material 23 on the central axis. It is installed.

  Therefore, in the drawing process, first, the rod-shaped material 23 is inserted into the insertion hole 31 b of the drawing piece 31. Subsequently, the rod-shaped material 23 is pressed by the squeezing pin 32 in the direction in which the squeezing hole 31a is located (direction indicated by the arrow B). Then, the tip 23a of the rod-shaped material 23 flows into the throttle hole 31a by plastic deformation and is narrowed down to a small diameter. Finally, the rod-shaped material 23 is discharged from the diaphragm piece 31 by moving the knockout pin 33 inserted from the diaphragm hole 31a side of the diaphragm piece 31 in the direction in which the insertion hole 31b is located (direction indicated by arrow C).

  As shown in FIG. 6, the preforming step uses the receiving piece 41 and the preforming punch 42 to bring the other end 23 b of the rod-shaped material 23 formed by the drawing step closer to the completed shape of the head 11. It is a process. The receiving piece 41 communicates with the insertion hole 41a, which has an inner diameter where the tip end 23a of the rod-shaped material 23 can be inserted and the other end 23b cannot be inserted, and the rod-shaped material 23. It has a preforming hole 41b that can be accommodated with the other end 23b partially protruding.

  Further, the preforming punch 42 has a mortar-shaped preforming recess 42a on the end face. The preforming recess 41b of the preforming punch is pressed toward the other end 23b of the rod-shaped material 23 (in the direction indicated by the arrow D). Thereby, the other end 23b of the rod-shaped material 23 is deformed so as to swell along the inner peripheral surface of the preforming hole 41b, and the head 11 (the other end 23b) is preformed.

  Furthermore, the bottom surface of the preforming recess 42a of the preforming punch 42 has a protrusion 42b at the center. For this reason, a recess 23c is formed in the center portion of the surface of the head 11 (the other end 23b) of the preformed rod-shaped material 23.

  As shown in FIG. 7, the finishing step is a finished product shown in FIGS. 1 and 2 by pressing the head 11 (the other end 23 b) of the preformed rod-shaped material 23 with the punch 52. This is a step of forming the battery external terminal 10 into a head shape. As shown in FIGS. 9 and 10, the punch 52 has a semispherical protrusion 52 b at its center portion on the end surface. With the punch 52 configured in this manner, the head 11 (the other end 23b) of the preformed rod-shaped material 23 held by the receiving piece 41 is pressed. Then, the head 11 is completed by plastically deforming the head 11 (the other end 23b) of the rod-shaped material 23 so as to fill the preformed recess 41b. Of course, since it formed with the punch 52 which has the protrusion 52b, the recessed part 23e is formed in the center part of the head surface of the rod-shaped raw material 23. FIG.

  As shown in FIG. 8, in the discharging step, the rod-shaped material 23 formed on the battery external terminal 10 positions the knockout pin 43 inserted from the insertion hole 41 a side of the receiving piece 41 in the preforming hole portion 41 b. By moving in the direction (direction indicated by arrow E), the sheet is discharged from the receiving piece 41.

  Here, in the finishing step, the reason why the protrusion 52b is provided in the central portion of the pressing surface (end surface) 52c of the punch 52 is as follows when the pressing surface has no protrusion and is flat. There is a problem that the surface of the head of the battery external terminal has a low smoothness. On the other hand, on the surface of the head portion 11 of the battery external terminal 10 formed using the punch 52 as in the present invention, the peripheral portion 23d of the recess 23e has high smoothness, and the bus bar 2 is provided here. This is suitable for laser welding or spot welding.

  Hereinafter, as another embodiment of the present invention, a method of manufacturing the battery external terminal 110 shown in FIGS. 11 and 12 using the punch 152 shown in FIGS. 13 and 14 instead of the punch 52 will be described. In the other embodiment, since the portions other than the configuration of the punch 152 used in the finishing process are the same as those in the method for manufacturing the battery external terminal described above, only the differences will be described. The punch 152 has a frustoconical protrusion 152b at the center of the pressing surface 152c, and the side surface of the protrusion 152b is formed into an inclined surface 152d.

  As shown in FIGS. 11 and 12, the battery external terminal 110 formed using the punch 152 has a recess 123e formed on the surface of the head 111 and a peripheral portion 123d having high smoothness. Become. Further, the inner peripheral surface of the recess 123e formed by the inclined surface 152d of the protrusion 152b of the punch 152 is also formed into the inclined surface 123f.

Here, the reason why the inclined surface 123f is formed in the recess 123e is that the rod-shaped material 23 is formed using processing oil in the finishing process. For this reason, when the punch 152 is pressed in a state in which the processing oil stays on the surface of the head portion 111 of the battery external terminal 110, the processing oil that has lost its escape at the boundary surface between the surface of the head 111 and the punch 152, There is also a problem that a dent is generated on the surface of the head 111 by being pressed by the pressing surface 152 c of the punch 152. On the other hand, in the battery external terminal 10 formed using the punch 152 as in the present invention, the inner peripheral surface of the recess 123e formed in the head 11 is formed in the inclined surface 123f. The processing oil staying in 123e is blocked by the inclined surface 123f. For this reason, since the processing oil does not overflow to the peripheral portion 123d, the smoothness of the peripheral portion 123d is not impaired. Although some dents are made on the inner peripheral surface and the bottom surface of the recess 123e by the processing oil, there is no problem because this portion does not affect the welding of the bus bar 2.

DESCRIPTION OF SYMBOLS 1 Lithium ion battery 2 Bus bar 10,110 Battery external terminal 11,111 Head 12,112 Shaft part 23 Bar-shaped material (metal piece)
23d, 123d Peripheral portions 23e, 123e Recess 123f Inclined surface 41 Receiving piece 52, 152 Punch 52b, 152b Protrusion 52c, 152c Press surface 152d Inclined surface

Claims (3)

A method of manufacturing an external terminal for a battery comprising a head portion to which a bus bar is joined by welding and a shaft portion to which a current collector plate is connected,
While holding a metal piece cut to a predetermined length with a receiving piece so that one end protrudes, and pressing the one end of the metal piece with a punch having a protrusion at the center of the pressing surface, the head is formed A method for producing an external terminal for a battery, characterized in that the surface of the head is smoothed except for the central portion, and a bus bar is joined to the smoothed surface of the head.   2. The method of manufacturing a battery external terminal according to claim 1, wherein the protrusion of the punch is formed so that an outer diameter decreases from a base end side to a tip end side. The method of manufacturing an external terminal for a battery according to claim 2, wherein a side surface of the projecting portion of the punch is formed as an inclined surface.

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