JPH06243846A - Manufacture of rectangular sealed battery - Google Patents

Abstract

PURPOSE:To prevent a deformation of a package can, and to increase the airtightness, so as to improve the reliability, by carrying out the calking by making the height of the corners in the upper opening smaller a specific height than the height at the center of a long side. CONSTITUTION:At the upper side of a step 2, a specific size of rising part 3 is formed, while the step 2 is formed by extending the upper opening of a package can 1 with a square tube form with bottom. In this case, when the height at the center of a long side is made h1, and the height of the corners is made h2, the rectangle is made h1>h2, and when the upper opening is contracted, the opening is made possible to bend to the inner side by making the height of the whole body of the upper opening equal and the widths of the sides equal. Consequently, when insulating gaskets are bent in a sealing process, the upper opening can be contracted evenly along the whole body and sufficiently, and the deformation of the package can is prevented as well as the airtightness is improved, so as to improve the reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a prismatic sealed battery, and more particularly to a method for manufacturing a prismatic sealed battery in which the shape of the upper opening of the outer can before the diameter reduction process is improved.

[0002]

2. Description of the Related Art An example of a conventional method for manufacturing a prismatic sealed battery will be described with reference to FIGS. First, as shown in FIG. 12, the stepped portion 51 is formed by expanding the upper opening of the outer can 50, which has a bottomed rectangular tube shape and each side of the upper opening has a uniform height. Subsequently, an electrode body (not shown) in which a positive electrode and a negative electrode are laminated via a separator is housed in the outer can 50. Continuing on, as shown in FIG. 13, an insulating gasket 52 in the shape of a square cylinder with a bottom having a rectangular hole at the bottom, in which a group of sealing lids having an explosion-proof function and terminals is stored in advance, is placed on the step 51 of the outer can 50. Place it. However, in FIG. 13, the sealing lid group is omitted. Then, the outer can 50
The upper opening of the outer can 50 is reduced in diameter to approximately the same size as the body of the outer can 50 to compress the insulating gasket 52 inward, and the upper end of the upper opening of the outer can 50 is bent inward. As shown in FIG. 14, the sealing lid group 53 is airtightly attached to the outer can 50 by compressing the insulating gasket 52 in the vertical direction and caulking to manufacture the battery. The sealing lid group 53 includes a sealing plate 54 having a gas vent hole at the center as shown in FIG. 14, and a safety valve (not shown) mounted so as to cover the gas vent hole and made of an elastic material. And a cap-shaped terminal plate 55 that surrounds the safety valve by being welded to the sealing plate 54 and has a gas vent hole, and functions as a return-type safety valve device.

In the battery manufactured by such a method, gas is generated in the outer can 50 due to overcharge, short circuit, etc., and the gas pressure is passed through the gas vent hole of the sealing plate 54 to the safety valve. When added, the safety valve is lifted because it is made of an elastic material, and a gap is created between the safety valve and the sealing plate 54. As a result, when the internal pressure of the battery rises, the gas escapes from the gap and the gas vent hole of the cap-type terminal plate 55 to the outside to prevent the battery from bursting.

However, when the diameter of the upper opening is reduced in the step of caulking and fixing in the above-mentioned conventional manufacturing method, the reduced diameter is shifted toward the four corners of the upper opening, and the four corners are provided. Is higher than the center of each side. Therefore, when the upper end of the upper opening is bent by the method described above, the width of the bent portion 56 becomes narrow at the center of each side and wide at the corner. In addition, since the degree of extension of the four corner portions during the diameter reduction step is greater on the long side than on the short side of the upper opening, the bent portion at the center of each of the long sides is larger. The width of 56 is further narrower than that of the central portion on each short side. As a result, when gas is generated in the outer can 50 due to the short circuit or the like, the central portion on the long side of the outer can bends outward, so that the gas pressure is lower than the operating pressure of the safety valve device. There is a problem that both the gas and the electrolytic solution in the outer can 50 leak out.

Further, if the curl is deepened to increase the pressure resistance of the corner portion where the width of the bent portion 56 is wide, the outer can 50 is locally pressed and the outer can 50 is deformed such as bending or distortion. There is a problem that it occurs.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art. The airtightness is improved, and when the upper end of the upper opening of the outer can is bent in the step of caulking and fixing, the above-mentioned problem is solved. An object of the present invention is to provide a method for manufacturing a prismatic sealed battery capable of preventing the outer can from being deformed.

[0007]

According to the present invention, there is provided a step of accommodating a power generating element in a bottomed rectangular tubular metal outer can having a step formed by expanding an upper opening outward.
Placing a bottomed rectangular tubular insulating gasket having a rectangular hole at the bottom, in which a metal sealing plate is stored in advance, on the stepped portion of the outer can, and the upper opening of the outer can to the outer casing. Compressing the rising portion of the insulating gasket inward by reducing the diameter to approximately the same size as the body of the can, and bending the upper end of the upper opening of the outer can inward to insulate the sealing plate In the method for manufacturing a prismatic sealed battery, which comprises a step of compression-fixing with a gasket, a height of a central portion on the long side of the upper opening is h ₁ , and a height of a corner portion is h _2.
In the method of manufacturing a prismatic sealed battery, an outer can that satisfies the following formula h ₁ > h ₂ is used.

[0008]

According to the present invention, an outer can is used which satisfies h ₁ > h ₂ when the height of the central portion on the long side of the upper opening is h ₁ and the height of the corner is h _2. By
In the step of caulking and fixing, if the upper opening is reduced to a size substantially equal to the size of the body of the outer can, even if the four corners of the upper opening of the outer can are extended, the upper part will be drawn from the relation of the above formula. The height of the entire opening can be made equal or substantially equal. As a result, when the upper end of the upper opening of the outer can whose diameter has been reduced is bent inward, the upper end of the central portion on the long side of the upper opening can be bent to be equal to or more than the corner portion. The pressure resistance when the internal pressure of the battery rises can be improved.

Further, since the resistance of the corner portion of the upper opening can be reduced during curling, the upper end of the upper opening can be bent without applying an excessive force to the outer can. As a result, it is possible to prevent the outer can from being deformed such as bent or distorted.

[0010]

Embodiments of the present invention will be described below with reference to FIGS. Example 1

First, as shown in FIG. 1, for example, the height of the corner of the upper opening is 1.9 mm, the height of the central portion on the long side is 2.2 mm, and the width of the long side of the trunk (L ₁ ) is 13.8
mm (the width of the short side is 6.8 mm) and the wall thickness is 0.4 mm, the stepped portion 2 is formed by expanding the upper opening of the bottomed square tubular outer can 1, and the stepped portion is formed. A rising part 3 having a long side width (L ₂ ) of 14.2 mm (a short side width of 7.2 mm) was formed on the upper side of the part 2. The shape of the outer can 1 is shown in FIG. Next, an electrode body 7 in which a positive electrode plate 5 covered with a bag-shaped separator 4 containing nickel hydroxide as an active material and a negative electrode plate 6 containing a hydrogen storage alloy as an active material were laminated was placed in the outer can 1. Stowed. Subsequently, the alkaline electrolyte was contained in the outer can 1. Further, a sealing lid group 10 having an explosion-proof function and a terminal is placed on an insulating gasket 9 having a bottomed rectangular tube having a rectangular hole 8 at the bottom, and the insulating gasket 9 is placed on the rising portion of the outer can 1. 3 was placed on the step 2 below. The sealing lid group 10 is made of a metal sealing plate 12 having a gas vent hole 11 at the center, a safety valve 13 placed so as to cover the gas vent hole 11, and made of, for example, synthetic rubber, and the sealing plate. It is welded to 12 to surround the safety valve 13, has a gas vent hole 14 formed therein, and is composed of a metal cap-shaped terminal plate 15 and has a valve operating pressure of 10 k.
g / cm ² Is set to. The positive electrode lead 16 having one end connected to the positive electrode plate 5 has the other end connected to the sealing plate 1.
2 is connected to the lower surface. After that, the outer can 1 is placed on the lower die 17, a hollow portion 18 having a square tubular shape is provided in the center, and a first taper die 20 having a narrowing taper 19 at the lower end of the hollow portion 18 having the square tubular shape. Was placed above the outer can 1. The rectangular hollow portion 1 of the first drawing die 20.
8 is a knockout 2 having a step portion 21 formed on the lower peripheral edge thereof.
2 is inserted.

Then, as shown in FIG. 2, the first drawing die 20 is lowered while the step portion 21 of the knuckout 22 and the upper end of the upper opening of the outer can 1 are brought into contact with each other to lower the outer can 1. The upper opening was reduced in diameter until it became equal to the width (L ₃ ) of the insulating gasket 9, and the step 2 of the upper opening was projected inward. Continuing, the first
After removing the first drawing die 20 from the outer can 1 by raising the drawing die 20 and pressing the step portion 21 of the knuckout 22 and the upper end of the upper opening of the outer can 1, FIG. As shown in FIG. 1, the first curl die 24 having the hollow portion 23 having a square tubular shape provided in the central portion was arranged above the outer can 1. In addition, a knuckout 26 having a step portion 25 formed at a lower peripheral edge thereof is inserted into the rectangular cylindrical hollow portion 23 of the first curl die 24.

Next, as shown in FIG. 4, the first curl die 24 is lowered to bring the first curl die 24 into contact with the upper end of the upper opening of the outer can 1 and the step of the knuckout 26. The portion 25 and the sealing plate 12 were brought into contact with each other, and the upper end of the upper opening of the outer can 1 and the rising portion 27 of the insulating gasket 9 were curled inward. Subsequently, as shown in FIG. 5, the first curl die 24 is lifted to remove the first curl die 24 from the outer can 1, and then a square tubular hollow portion 28 is provided in the central portion. A second drawing die 30 having a drawing taper 29 at the lower end of the hollow portion 28 having a rectangular tube shape is arranged above the outer can 1. In addition, a knuckout 32 having a step portion 31 formed at a lower peripheral edge is inserted into the square tubular hollow portion 28 of the second drawing die 30.

Next, as shown in FIG. 6, the second drawing die 30 is lowered while the step 31 of the knuckout 32 is in contact with the upper end of the upper opening of the outer can 1 to lower the upper part of the outer can 1. The diameter of the opening is reduced until it is approximately equal to the width (L ₁ ) of the body of the outer can 1, and the step 2 of the outer can 1 is reduced.
Was further projected inward to form a bent portion 33 having a width (L ₄ ). Subsequently, as shown in FIG. 7, after the second drawing die 30 is lifted to remove the second drawing die 30 from the outer can 1, a square tubular hollow part 34 is provided at the center. The 2-curl mold 35 was placed above the outer can 1. In addition,
A knuckout 37 having a step portion 36 formed at a lower peripheral edge thereof is inserted into the rectangular tubular hollow portion 34 of the second curl die 35.

Next, as shown in FIG. 8, the second curl die 35 is lowered to abut against the upper end of the upper opening of the outer can 1 and the step 36 of the knuckout 37.
The sealing plate 12 is brought into contact with the upper end of the upper opening of the outer can 1 and the rising portion 27 of the insulating gasket 9.
Was further curled inward to form a bent portion 38 on the peripheral edge of the sealing plate 12. Then, the second curl type 3
5 and the lower mold 17, the outer can 1 was removed as shown in FIGS. 9 and 11 to manufacture a prismatic nickel-hydrogen secondary battery.

The outer can 1 is drawn from a metal plate in order to prevent the nickel plating applied to the outer can 1 from peeling off when the upper end of the upper opening is bent. It is more desirable to manufacture by forming the above shape, followed by nickel plating and then heat treatment.

The above-described manufacturing method shown in FIG.
As shown in 0, when the height of the central portion on the long side of the upper opening is h ₁ and the height of the corner portion is h ₂ , h ₁ >
By using the outer can 1 that satisfies h ₂ , when the diameter of the upper opening is reduced, the meat comes close to the four corners. Since the height is low, the height of the entire upper opening is equal or substantially equal. As a result, as shown in FIG. 11, the upper end of the diameter-reduced upper opening can be bent inward with a uniform width. Therefore, since the bent portion 38 can uniformly and sufficiently compress the insulating gasket, the airtightness of the battery can be improved.

Further, since the width of the bent portion 38 is uniform, the upper end of the upper opening can be bent without applying an excessive force to the outer can 1 during the bending step. As a result, it was confirmed that the outer can 1 can be prevented from being deformed such as being bent or distorted, and that it has a pressure resistance equal to or higher than the valve operating pressure. In fact, the experiments described below confirmed that the battery manufactured by the manufacturing method of Example 1 had excellent characteristics.

First, except that an outer can having a uniform height on each side of the upper opening was used as the battery of Comparative Example 1,
A battery manufactured by the same manufacturing method as in Example 1 was prepared. However, the batteries of Example 1 and Comparative Example 1 were not provided with an explosion-proof function for the pressure resistance test described later.

10 batteries each of Example 1 and Comparative Example 1
Individually prepared, a booster was attached to the body of the outer can of each battery, and the gas pressure causing gas leakage from the sealing portion was measured with a pressure sensor. The results are shown in Table 1 below. Table 1 Gas pressure of sample gas leakage (kg / cm ² ) Example 1 12.5-15 Comparative Example 1 8.5-11

As is apparent from Table 1, the battery manufactured by the method of Example 1 has a high withstand voltage and can improve airtightness. On the other hand, since the battery manufactured by the method of Comparative Example 1 has a low withstand voltage, it can be inferred that gas leakage occurs from the sealing portion before the valve is actuated when the battery is actually provided with an explosion-proof function and used.

In the first embodiment, a manufacturing method using an outer can having a shape in which both ends of the long side and the short side of the upper opening are continuously reduced toward the corner is described. Although it has been described as applied, the present invention can also be applied to a manufacturing method using an outer can having a shape in which the step size of both ends on the long side of the upper opening is smaller than the central part.

[0023]

As described above in detail, according to the present invention, the airtightness can be improved and the deformation of the outer can can be reduced when the upper end of the upper opening of the outer can is bent in the step of caulking and fixing. It is possible to provide a highly reliable method for manufacturing a prismatic sealed battery.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a rectangular sealed battery of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of a square sealed battery of the present invention.

FIG. 3 is a cross-sectional view showing a manufacturing process of the prismatic sealed battery of the present invention.

FIG. 4 is a cross-sectional view showing the manufacturing process of the prismatic sealed battery of the present invention.

FIG. 5 is a cross-sectional view showing the manufacturing process of the prismatic sealed battery of the present invention.

FIG. 6 is a cross-sectional view showing a manufacturing process of the prismatic sealed battery of the present invention.

FIG. 7 is a cross-sectional view showing the manufacturing process of the prismatic sealed battery of the present invention.

FIG. 8 is a cross-sectional view showing the manufacturing process of the rectangular sealed battery of the present invention.

FIG. 9 is a cross-sectional view showing a rectangular sealed battery manufactured by the manufacturing method of the present invention.

FIG. 10 is a perspective view showing an outer can used in the method for manufacturing a rectangular sealed battery of the present invention.

FIG. 11 is a perspective view showing a rectangular sealed battery manufactured by the manufacturing method of the present invention.

FIG. 12 is a perspective view showing an outer can used in a method for manufacturing a rectangular sealed battery of a conventional example.

13 is a perspective view showing a state in which the diameter of the upper opening of the outer can of FIG. 12 is reduced.

FIG. 14 is a perspective view showing a rectangular sealed battery manufactured by a manufacturing method of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Exterior can, 2 ... Step part, 8 ... Rectangular hole, 9 ... Insulation gasket, 12 ... Sealing plate, 27 ... Standing part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Kitazume 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Inside Toshiba Battery Co., Ltd.

Claims (1)

[Claims] 1. A step of accommodating a power generation element in a bottomed rectangular tubular metal outer can having a step portion formed by expanding an upper opening outward, and a metal sealing plate is previously accommodated. The step of placing a bottomed rectangular tubular insulating gasket having a rectangular hole in the bottom on the stepped portion of the outer can, and the upper opening of the outer can having substantially the same size as the body of the outer can. And a step of compressing the rising portion of the insulating gasket inward, and a step of bending the upper end of the upper opening of the outer can inward and compressing and fixing the sealing plate with the insulating gasket. In the method for manufacturing a prismatic closed battery, the height of the central portion on the long side of the upper opening is h ₁ ,
A method for manufacturing a prismatic sealed battery, characterized in that an outer can that satisfies the following formula h ₁ > h ₂ is used, where the height of a corner portion is h ₂ .