JPH06333541A - Rectangular battery can and its manufacture and device for forming rectangular vessel for rectangular battery - Google Patents

Abstract

PURPOSE:To make plate thickness with almost even dimensional accuracy, and to improve productivity, by providing a rectangular vessel formed by applying a tensile force reaching to a plastic deformation zone to a tube body in the direction orthogonal to the vessel axis, and a bottom plate connected airtight to the bottom of the rectangular vessel. CONSTITUTION:A rectangular battery can 11 consists of a rectangular vessel 12 an a bottom plate 13, and it is composed by welding connecting both members. Since the vessel 12 is formed by applying a tensile force reaching to the plastic deformation zone to a tube body in the direction orthogonal to the vessel axis, the parts corresponding to both ends of the long side side surface of the vessel 12 after formation are pulled to the center at the long side side surface, and the maaterial thickness can be made almost even by suppressing the variation of the material thickness to a minimum. As a result, the deformation in the charging time when the internal pressure is increase when it functions as a battery can be prevented, and the can strength is also increased. And by forming the vessel 12 and the bottom 13 separately, a consideration of the press hardening is unnecessary, so as to reduce the number of formation processes, as well as the process of annealing is made unnecessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prismatic battery can, and more particularly to a prismatic battery can for a lithium ion secondary battery, a method for producing the same and a device for molding a rectangular cylinder for the prismatic battery can.

[0002]

2. Description of the Related Art Generally, a rectangular battery can is manufactured by press drawing. In the conventional lithium-ion secondary battery can battery shown in FIG. 10, a plate-shaped metal plate requires about 10 steps by a combination of drawing and punching in several steps by a transfer press etc. Can be finished.

[0003]

However, since stainless steel having corrosion resistance and pressure resistance is used as the material for the battery can of the lithium-ion secondary battery, the following can be used in the manufacture of the rectangular battery can. There was such a problem.

The stainless steel used is a hard-to-work material that is hard to work harden, and in the conventional manufacturing method using a drawing process, work hardening is severe during the working process, so that it is necessary to anneal several times during the process. there were. Therefore, productivity was extremely poor.

In the rectangular battery can 11 obtained by the drawing process, the material thickness in the shaded area in FIG. 10 (a) is reduced to about 2/3 of the thickness of the original material. Therefore, the strength of the can becomes weak in the thin material portion. In addition, when it functions as a battery, deformation may occur during charging when the internal pressure increases.

The present invention has been made in view of the above circumstances, and a rectangular battery can having a substantially uniform material thickness and good dimensional accuracy, a manufacturing method with good productivity, and a rectangular tube for a rectangular battery can used therefor. A molding device is provided.

[0007]

The battery can according to the present invention comprises a rectangular tube formed by applying a tensile force that reaches a plastic deformation region in a direction orthogonal to the tube axis, and an airtight bottom part of the rectangular tube. And a bottom plate joined to.

Further, the method for manufacturing a battery can of the present invention comprises a step of forming a rectangular tube by applying a tensile force to the tube in a direction orthogonal to the axis of the tube to reach a plastic deformation region, and a step of forming the tube into a desired angle. Cutting the square tube so as to be equal to the height of the battery case, inserting a bottom plate into the bottom of the square tube, and rolling the bottom plate to fit the bottom of the square tube, And welding the square tube and the rolled bottom plate.

The square tube forming device for a rectangular battery can according to the present invention comprises a pair of cored bars and a wedge-shaped tool slidably inserted between the cored bars. The outer shape constitutes the desired inner dimension of the rectangular cylinder, and the wedge-shaped tool is slid to move the pair of cored bars in the direction orthogonal to the cylinder axis of the cylinder to form the desired rectangular cylinder. It is characterized by

[0010]

According to the present invention, since the rectangular tube is formed by applying a tensile force that reaches the plastic deformation region in a direction orthogonal to the cylinder axis, the long side surface of the rectangular tube after molding is formed. The parts corresponding to both ends are attracted to the central part of the long side surface, so that the change in material thickness can be suppressed to a minimum and the material thickness can be made substantially uniform. In addition, since the rectangular tube and the bottom plate of the prismatic battery can are formed separately, it is possible to prevent the material thickness of the corner portion of the bottom surface of the can from becoming thin, and there is no need for an annealing step due to work hardening.

[0011]

【Example】

(Embodiment 1) A rectangular battery can 11 according to the present invention comprises a rectangular tube 12 and a bottom plate 13 as shown in FIG. Note that the dimensions a, b, and c in FIG. 1 indicate the short side, long side, and height of the battery can, respectively. Hereinafter, the outer dimensions and the thickness of the battery can are excluded to represent the outer dimensions of the battery can. The inner dimension is used to represent the inner dimension.

A method for forming the rectangular battery can 11 and an apparatus for forming the rectangular tube 12 and the bottom plate 13 of the rectangular battery can will be described. As shown in FIG. 2, the forming device of the rectangular tube 12 of the rectangular battery can 11 includes a pair of cored bars 14 located on a base plate 24, and a wedge slidably inserted between the pair of cored bars 14. The tool 15 and the tool 15. The pair of cored bars 14 is movable in a direction orthogonal to the cylinder axis of the cylindrical body, and the wedge-shaped tool 15 is inserted between the pair of cored bars 14 to move the pair of cored bars 14 in the arrow direction B. When the wedge-shaped tool 15 is completely inserted between the pair of cored bars 14, the outer shape of the pair of cored bars 14 is changed to the desired rectangular tube 12 It is characterized in that it forms an inner shape of. The distance d between the cores 14 expanded by inserting the wedge-shaped tool 15 by the spring 16 is the same as that of the cored bar 1 obtained by removing the wedge-shaped tool 15.
4 moves in the direction of arrow B'and contracts. Here, the inclination angle of the core metal is limited by the length of the rectangular tube and the insertion length of the wedge-shaped tool, but it is preferable that the inclination angle be as small as possible.

As a molding device for the bottom plate 13 of the rectangular battery can 11, a punching die is used. An apparatus for molding the bottom plate 13 and fitting the square tube 12 and the bottom plate 13 in an airtight manner will be described with reference to FIG. As shown in FIG. 6, this device includes a punch 20 for punching the bottom plate 13, a punching die 21,
The mandrel 19 to be inserted into the inside of the rectangular tube 12, the mandrel holder 22 that fixes the mandrel 19 and is movable in the arrow direction C so that the bottom plate 13 and the rectangular tube 12 can be accurately positioned, and the rectangular tube 1
Slide 2 that can move in the direction D shown by the arrow to restrain the end of 2
3 and 3.

Next, a method of manufacturing the rectangular battery can 11 will be described. First, the rectangular tube 12 is molded by the above molding device. For the tubular body, stainless steel such as SUS304L
The pipe material 17 having a thickness of 3 mm and made of the above sample is used.
This pipe material 17 is set so as to surround the pair of cored bars 14 as shown in FIG. Note that FIG. 3B is a cross-sectional view taken along the line 3b-3b in FIG. Next, the wedge-shaped tool 15 is inserted between the pair of cored bars 14 while moving in the arrow direction A as shown in FIG. Move the wedge-shaped tool 15 gradually in the direction of arrow A.
The pair of cored bar 14 is moved in the arrow direction B by inserting the cored bar into the arrow B. Thus, as shown in FIG. 4 (b), the pipe material 17 is formed so that the pipe material 17 becomes equal to the desired length of the long side b of the rectangular battery can 11 after molding.
Mold 7. Here, the thickness e of the core metal 14 and the thickness e of the wedge-shaped tool are substantially equal to the length of the short side of the inner dimension of the desired rectangular battery can 11. Note that FIG. 4B is the same as FIG.
4b is a cross-sectional view taken along line 4b-4b of FIG. Next, this molded body is cut by a press die (not shown) so as to have a desired height c of the rectangular battery can 11 as shown in FIG. Here, although a cylindrical pipe material is used for the cylindrical body, the cylindrical body is not limited to a cylindrical shape and may have any shape that can be manufactured by the conventional technique, and may be, for example, a cylindrical body having an elliptical or oval cross section.

Next, a method of forming the bottom plate 13 will be described. As shown in FIG. 6, by using a drawing die, from a plate material 18 made of stainless steel, for example, SUS304L, to a rectangle having a short side a and a long side b of an inner dimension of a desired rectangular battery can. The bottom plate 13 is punched into a slightly smaller rectangular shape. At the same time as this punching, the punch stroke
The bottom plate 13 is fitted inside the bottom of the square tube 12 into which the core bar 19 is inserted, and the bottom plate 13 is struck and rolled by the core bar 19 and the punch 20 to change the material thickness of the bottom plate 13 and Fit tighter inside the ends of the. At this time, in order to prevent the bulging of the end portion of the rectangular tube 12, the pair of slides 23 restrain the outside of the end portion of the rectangular tube 12. In this way, the square tube 12
Since the bottom plate 13 and the bottom plate 13 are pressure-bonded and do not come off easily,
Good work efficiency during laser welding in the next process.

Next, as shown in FIG. 7, the square tube 12 and the bottom plate 13 are welded by moving the laser L as shown by an arrow to obtain the battery can 11. Here, suppressing springback,
In order to obtain a rectangular cylinder with the desired dimensional accuracy, a tensile force that reaches the plastic deformation region is necessary. Therefore, the outer peripheral dimension of the pipe material, that is, the dimension before molding, is such that the dimension after molding, that is, the outer circumferential dimension of the desired battery can is preferably 3 to 15% larger than the dimension before molding, more preferably 6 to 8%. It is desirable to set to. Above this value, the phenomenon of material thickness reduction and surface roughening rapidly progresses from the center of the long side surface of the desired prismatic battery, leading to breakage. On the other hand, if it is less than this value, springback occurs and the shape and dimensional accuracy deteriorate. This value varies depending on the material used. Further, the height of the pipe material is set to be larger than the target height of the battery can.

As described above, since the pipe material 17 is formed by applying the tensile force reaching the plastic deformation region in the direction orthogonal to the cylinder axis, as shown in FIG. 5, the desired length of the rectangular battery can 11 is increased. Pipe material 1 at both ends of the side
7 can be drawn to the center of the long side surface of the desired battery can, the change in material thickness can be suppressed to a minimum, and a rectangular battery can 11 having a substantially uniform material thickness can be obtained. As a result, when functioning as a battery, the internal pressure can be prevented from being deformed at the time of charging and the can strength can be increased. Further, since the rectangular tube 12 and the bottom plate 13 are separately molded, it is not necessary to consider work hardening. As a result, the step of annealing is unnecessary and the number of forming steps is reduced, so that the productivity is improved.

(Embodiment 2) As shown in FIG. 8, the apparatus for forming the rectangular tube 12 of the prismatic battery can according to the present embodiment is the same as the apparatus for forming the rectangular tube according to the first embodiment, except that the wedge-shaped tool 15 is provided with a pair of cores. By inserting it between the metal bars 14,
Is provided with a slide cam 25 in which a force acts on the arrow B'in the direction opposite to the opening direction, and at the end of forming the pipe blank 17,
It is characterized in that a step of sandwiching both sides of the short side surface of the rectangular battery can after molding with the core metal 14 and the slide cam 25 is added.

The operation of this device will be described. When the wedge-shaped tool 15 is inserted in the direction of arrow A, the cam 26 moves in the direction of arrow A in conjunction with the wedge-shaped tool 15, and the cam 26 applies a force to the slide cam 25 in the direction of arrow B ′. At the end of forming the pipe material 17, both sides of the short side surface of the formed rectangular battery can are sandwiched by the core metal 14 and the slide cam 25.

By the way, although the performance of the battery was not affected, the cylindrical portion 12 molded by the method of Example 1 was as follows. That is, the tubular portion 1 molded by the method of Example 1
As shown in FIG. 9B, the short side surface 11a at both ends of the rectangular tube 12 is substantially flat, and the short side surface 11a at the center of the rectangular tube 12 is shown in FIG. 9C. Has a slightly rounded shape, and the outer circumference of the central portion is larger than the outer circumference of both ends by the rounded shape. Incidentally, FIG. 9A shows a rectangular tube 12 made by the molding method of Example 1, and FIG.
9B is a cross-sectional view taken along line 9b-9b in FIG. 9A, and FIG. 9C is a cross-sectional view taken along line 9c-9c in FIG. 9A.

In the apparatus of the second embodiment, the pipe material 17
At the end of molding, the short side surface 2 of the rectangular battery can after molding
Since the surface is sandwiched between the core metal 14 and the slide cam 25, the rectangular tube 12
The side surface 11a on the short side of the central portion of the is substantially flat, and a battery can with higher dimensional accuracy can be obtained.

Although each of the above embodiments has been described with respect to a rectangular battery can, this manufacturing method can be applied to a cylindrical battery and to a battery can other than a lithium battery. In particular, it is possible to easily provide a battery can having an extremely high shape, a battery can having a shape that is difficult to press-draw, such as a battery can having a large difference between the long side and the short side. Further, it can be applied as a substitute for the drawing process in a material which is hard to work and harden.

[0023]

EFFECTS OF THE INVENTION Since the rectangular battery can of the present invention has a substantially uniform material thickness, it is possible to prevent deformation during charging, which increases the internal pressure when functioning as a battery, and has a strong can strength. Further, according to the method for manufacturing a rectangular battery can of the present invention, since the rectangular tube and the bottom plate are separately molded, it is not necessary to consider work hardening. As a result, the step of annealing is unnecessary and the number of forming steps is reduced, so that the productivity is improved.

[Brief description of drawings]

FIG. 1A is a perspective view of a rectangular battery can according to the present invention. (B) A longitudinal cross-sectional view taken along line 1b-1b in FIG.

FIG. 2 is a schematic cross-sectional view of a device for forming a rectangular tube of a rectangular battery can according to the present invention.

FIG. 3 (a) is a schematic view showing a forming process before forming a rectangular tube of a rectangular battery can. 3B is a cross-sectional view taken along line 3b-3b in FIG.

FIG. 4 (a) is a schematic view showing a square tube forming step in the process of forming a square tube of a square battery can. 4B is a cross-sectional view taken along the line 4b-4b in FIG.

FIG. 5 is a perspective view showing the process of forming a prismatic battery can next to FIG.

FIG. 6 is a process for forming a bottom plate of a rectangular battery can and a forming apparatus;
Schematic which shows the process of crimping a square cylinder and a bottom plate, and a shaping | molding apparatus.

FIG. 7 is a perspective view showing a process of laser welding a rectangular tube and a bottom plate of a rectangular battery can.

FIG. 8 is a vertical cross-sectional view showing another embodiment of the apparatus for forming the rectangular tube of the rectangular battery can of the present invention.

9 (a) is a view showing a square tube of a square battery can molded by the molding device shown in FIG. (B) A cross-sectional view taken along the line 9b-9b in FIG. 9 (a). (C) A cross-sectional view taken along line 9c-9c in FIG. 9 (a).

FIG. 10 (a) is a perspective view of a battery can obtained by a conventional drawing process. 8B is a vertical cross-sectional view taken along the line 10b-10b in FIG. FIG.

[Explanation of symbols]

 11 ... Square battery can 12 ... Square tube 13 ... Bottom plate 14 ... Core metal 15 ... Wedge-shaped tool 17 ... Pipe material 20 ... Punch

Claims (4)

[Claims] 1. A square tube formed by applying a tensile force that reaches a plastic deformation region in a direction orthogonal to a cylinder axis, and a bottom plate airtightly joined to the bottom of the square tube. Characteristic square battery can. 2. A step of forming a rectangular tube by applying a tensile force that reaches a plastic deformation region in a direction orthogonal to the axis of the tube to form a rectangular tube, and the step of making the molded piece equal to a desired height of a rectangular battery can. A step of cutting the square tube, a step of inserting a bottom plate into the bottom portion of the square tube, a step of rolling the bottom plate to fit the bottom portion of the square tube, and the square tube and the rolled bottom plate. A method for manufacturing a prismatic battery can, comprising the step of welding and joining. 3. A pair of cored bars and a wedge-shaped tool slidably inserted between the cored bars, wherein the pair of cored bar outer shapes form a desired inner dimension of a rectangular cylinder, A device for forming a rectangular tube for a rectangular battery can, characterized in that the wedge-shaped tool is slid to move the pair of cores in a direction orthogonal to the axis of the tube to form a desired rectangular tube. . 4. An apparatus for forming a rectangular tube for a prismatic battery can according to claim 3, wherein the wedge-shaped tool is inserted between the pair of cored bars so that the direction opposite to the opening direction of the pair of cored bars is obtained. A prismatic battery characterized in that a slide cam for exerting a force is provided on the core body, and at the end of molding of the cylindrical body, both sides of the short side surface of the prismatic battery can after molding are sandwiched by the core metal and the slide cam. Machine for forming square cylinders for cans.