JP3253161B2 - Manufacturing method of prismatic sealed battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a sealed rectangular battery, and more particularly to a method of manufacturing a sealed rectangular battery having improved shapes of a drawing die and a curl die.

[0002]

2. Description of the Related Art A conventional rectangular sealed battery is manufactured by a method shown in FIG. First, a bottomed rectangular cylindrical outer can 5
A step (not shown) is formed by widening the upper opening of the “0”. Subsequently, an electrode body (not shown) in which a positive electrode and a negative electrode are laminated via a separator is accommodated in the outer can 50. Continued, explosion-proof function and sealing lid group 5 which also serves as terminal
1 is housed in a bottomed square tubular insulating gasket 52 having a rectangular hole at the bottom. The sealing lid group 51 includes a metal sealing plate 53 having a gas vent hole opened in the center, a safety valve (not shown) made of, for example, synthetic rubber, which is placed so as to cover the gas vent hole, A metal hat-shaped terminal plate 54 surrounding the safety valve by being welded to the sealing plate 53 and having a gas vent hole opened. In addition,
The sealing plate 53 has a shape in which two opposing longitudinal sides are curved outward. The insulating gasket 52 is placed on the step of the outer can 50. Next, using a drawing die (not shown) in which a hollow portion having a rectangular cylindrical shape is provided at the center and the inner peripheral surface at the lower end of the hollow portion is opened outward, a knuck which moves up and down the hollow portion is used. The drawing die is inserted into the upper opening of the outer can 50 while holding the upper opening of the outer can 50 out (not shown), and the upper opening of the outer can 50 is inserted into the outer can 50. The insulating gasket 52 is compressed inward by reducing the diameter to the size of the body. Subsequently, a curled mold (not shown) in which a hollow portion having a rectangular cylindrical shape is provided at the center portion and which has a rectangular recess formed at the bottom portion and communicating with the hollow portion and having a size larger than the hollow portion, The outer can 5 is formed by a knuckout (not shown) which moves up and down the hollow portion.
0, while pressing the sealing plate 53, the curl mold is brought into contact with the upper end of the upper opening of the outer can 50, and the upper end of the upper opening of the outer can 50 is bent inward. The plate 53 is compressed and fixed with the insulating gasket 52 to manufacture the battery.

In such a conventional method for manufacturing a prismatic battery, when the sealing plate 53 whose longitudinal sides opposed to each other are curved as described above is used, the sealing plate 5
3 and the bent portion 5 of the outer can 50
5 is narrowed, and the insulating gasket 52 interposed therebetween is over-compressed, which promotes compressive strain.

In addition, in the above-mentioned conventional method, the upper opening of the outer can 50 is reduced in diameter by using a drawing die in which the inner peripheral surface of the hollow portion has a flat surface, and The upper end of the upper opening of the outer can 50 is bent using a curl mold having a flat inner peripheral surface. As a result, the bent portion 55 of the outer can 50 cannot be formed following the outwardly curved side of the sealing plate 53 after the bending step as shown in FIG. , The curved side of the sealing plate 53 and the outer can 50 facing the curved side
The rising portion of the insulating gasket 52 interposed between the bent portion 55 and the bent portion 55 is excessively compressed. Therefore,
Since the sealing plate 53 is excessively compressed inward by the insulating gasket 52, there is a problem that the sealing plate 53 is warped and airtightness is reduced.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems, and has a rectangular shape capable of preventing the sealing plate from being deformed in the sealing step and improving the airtightness. An object of the present invention is to provide a method for manufacturing a sealed battery.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided a step of accommodating a power generating element in a bottomed rectangular cylindrical metal outer can having a step formed by expanding an upper opening. a step of two longitudinal sides which face each other for placing the rectangular metallic sealing plate having a curved shape outwardly, the bottomed rectangular cylindrical insulating the gasket having a rectangular hole in the bottom, the insulation A step of mounting a gasket on the step of the outer can, a drawing die in which a rectangular hollow portion is provided at the center, and a lower end inner peripheral surface of the hollow portion is opened outward; and Aperture
Knock-out that moves up and down the hollow part of the mold
Using, while holding down the upper opening of the outer can with the knockout, insert the drawing die into the upper opening of the outer can and insert the upper opening of the outer can to the body dimension of the outer can. A step of reducing the diameter and compressing the rising portion of the insulating gasket inward, and forming a rectangular hollow portion provided at the center and a rectangular shape having a greater length and width than the hollow portion formed at the lower end of the hollow portion. Curl mold with recess and front
Free from the hollow part of the curl mold to the square concave part
Using a knuckout that moves up and down, the curl mold is brought into contact with the upper end of the upper opening of the outer can by pressing the metal sealing plate of the outer can with the knuckout, and Compressing and fixing the sealing plate with the insulating gasket by bending the upper end of the upper opening inward, wherein the drawing die includes an inner peripheral surface of the hollow portion. The surface corresponding to the curved side of the sealing plate has an outwardly curved shape, and the curl mold corresponds to the curved side of the sealing plate on the inner peripheral surface of the rectangular recess. A method for manufacturing a rectangular sealed battery, characterized in that a surface to be bent has an outwardly curved shape.

From the viewpoint of sealing the battery with good airtightness,
In the drawing die, the width of the central portion of the curved portion of the hollow portion is larger than the width of the end portion of the curved portion by 0.5% or more, and also in the curl die, the width of the central portion of the curved portion of the concave portion is reduced. It is desirable that the width be 0.5% or more than the width of the end of the curved portion.

[0008]

According to the present invention, the upper opening of the outer can can be formed by using a drawing die in which the surface corresponding to the curved side of the sealing plate in the inner peripheral surface of the hollow portion has an outwardly curved shape. By using a curl mold having a shape in which the surface corresponding to the curved side of the sealing plate among the inner peripheral surfaces of the rectangular recesses has an outwardly curved shape, the curved side of the sealing plate is further reduced. The upper end of the upper opening of the outer can can be bent inward following the side. As a result, since the insulating gasket interposed between the bent portion of the outer can and the side of the sealing plate can be prevented from being locally compressed, the sealing plate is deformed. Can be prevented, the sealed battery can have a shape in which the long side surface of the outer can is curved outward, and as a result, due to a short circuit or overcharging, The gas pressure generated in the can causes the surface on the longitudinal direction of the upper opening of the outer can to be curved, but the strength can be improved.
Therefore, it is possible to maintain high airtightness when the internal pressure increases.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 First, a drawing die and a curl die used in the manufacturing method of the present invention will be described with reference to FIGS.

In FIGS. 1 and 2, an outer can described later is placed on a lower mold 1. A vertically movable first draw mold 4 in which a rectangular hollow part 2 is provided at the center and a lower end inner peripheral surface 3 of the hollow part 2 is opened outward is the lower die 1.
It is arranged above. A rectangular frame-shaped projection 5 on the lower periphery
Is moved up and down in the hollow portion 2. Further, as shown in FIG. 10, the hollow portion 2 has a shape in which a surface 7 corresponding to a curved side of a sealing plate described later among the inner peripheral surfaces thereof is curved outward, and The length (L ₁ ) of the long side is 16.62 mm, the width (L ₂ ) at the center of the curved portion is 5.87 mm, and the width (L ₃ ) at the end of the curved portion.
Is 5.72 mm.

In FIG. 3 and FIG.
A first curl mold 10 which is provided at the center and communicates with the hollow portion 8 at the bottom and has a rectangular recess 9 having a larger vertical and horizontal dimension than the hollow portion is formed. Are located in A knockout 12 having a rectangular frame-shaped protrusion 11 formed on a lower peripheral edge moves up and down the hollow portion 8 and the concave portion 9. As shown in FIG. 11, the concave portion 9 has a shape in which a surface 13 corresponding to a curved side of a sealing plate described later among the inner peripheral surfaces thereof is curved outward, and the length of the long side of the concave portion 9 is long. The length (L ₄ ) is 16.62 mm, the width (L ₅ ) at the center of the curved portion is 5.87 mm, and the width (L ₆ ) at the end of the curved portion is 5.72 mm.

In FIG. 5 and FIG.
4 is provided at a central portion, and a lower end inner peripheral surface 15 of the hollow portion 14 is opened outward.
6 is arranged above the lower mold 1. A knuckout 18 having a rectangular frame-shaped projection 17 formed on the lower periphery moves up and down the hollow portion 14. Further, the hollow portion 14
Of the inner peripheral surface, a surface corresponding to a curved side of a sealing plate described later has a shape curved outward, and the length of the long side of the hollow portion 14 is 16.62 mm. The width is 5.
87 mm, and the width of the end of the curved portion is 5.72 mm.

In FIG. 7 and FIG.
The second curl mold 21 is provided at the center and communicates with the hollow portion 19 at the bottom, and is formed with a rectangular concave portion 20 having a larger vertical and horizontal dimension than the hollow portion 19. It is located above. A knuckout 23 having a rectangular frame-shaped projection 22 formed on the lower periphery moves up and down the hollow portion 19 and the concave portion 20. Further, the concave portion 20 has a shape in which a surface corresponding to a curved side of a sealing plate described later among the inner peripheral surfaces thereof is curved outward, and the long side of the concave portion 20 has a length of 16.62 mm. The width of the central portion of the curved portion is 5.87 mm, and the width of the end portion of the curved portion is 5.72 m.
m. Next, the production method of the present invention will be described in detail.

As shown in FIG. 1, for example, the width (L ₇ ) of the long side of the body is 16.4 mm (the width of the short side is 5.5).
mm), the upper portion of the outer can 24 having a bottomed square cylindrical shape having a wall thickness of 0.4 mm is widened to form a stepped portion 2.
5 and the long side width (L ₈ ) is 16.8 mm above the step 25 (the short side width is 5.9 mm).
Is formed. Subsequently, an electrode body 30 in which a positive electrode plate 28 containing nickel hydroxide as an active material covered with a bag-shaped separator 27 and a negative electrode plate 29 containing a hydrogen storage alloy as an active material are laminated is placed in the outer can 24. Stowed. Subsequently, an alkaline electrolyte was accommodated in the outer can 24. Further, a rectangular hole 31 is opened at the bottom, and a sealing lid group 33 which also serves as an explosion-proof function and a terminal is placed on an insulating gasket 32 having a bottomed square cylindrical shape with a rising portion having a thickness of 0.5 mm. The gasket 32 was placed on the step 25 under the rising portion 26 of the outer can 24. The sealing lid group 33 is provided with a metal sealing plate 35 having a gas vent hole 34 opened in the center, and a safety valve 36 made of, for example, synthetic rubber so as to cover the gas vent hole 34.
And a metal cap-shaped terminal plate 38 surrounding the safety valve 36 by welding with the sealing plate 35 and having a gas vent hole 37 opened. The sealing plate 35
Has a shape in which longitudinal sides opposed to each other are curved outward as shown in FIG.
m, the width (L ₉ ) of the central portion of the curved portion is 4.25 mm, and the width (L ₁₀ ) of the end portion of the curved portion is 4.1 mm. Further, the length of the long side of the sealing plate 35 is desirably 40 times or less the thickness of the outer can 24 from the viewpoint of improving the airtightness of the battery, and is 15 mm in the present embodiment. A positive electrode lead 39 having one end connected to the positive electrode plate 28 is provided.
The other end is connected to the lower surface of the sealing plate 35. Thereafter, the outer can 24 is placed on the lower mold 1, and the first
The drawing die 4 was disposed above the outer can 24.

Next, as shown in FIG. 2 described above, the first drawing die 4 is lowered, and the first drawing die 4 is pressed while pressing the upper end of the upper opening of the outer can 24 with the projections 5 of the knockout 6. By inserting the mold 4 into the upper opening of the outer can 24, the diameter of the upper opening of the outer can 24 is reduced to such a degree that the insulating gasket 32 is lightly compressed, and the step of the upper opening is reduced. 25 protruded inward.
Subsequently, after the first drawing die 4 was lifted and removed from the outer can 24, the first curl die 10 was disposed above the outer can 24 as shown in FIG.

Next, as shown in FIG. 4 described above, the first curl mold 10 is lowered and the sealing plate 35 is pressed by the projections 11 of the nack-out 12 to form the first curl mold 10. Inner peripheral surface of recess 9 and outer can 2
The upper end of the upper opening of the outer can 24 is brought into contact with the upper end of the upper opening of the outer can 24 and the insulating gasket 32.
Was bent inward. Subsequently, as shown in FIG. 5 described above, the first curl mold 10 is raised to move the first curl mold 10 to the outer can 2.
After being removed from 4, the second drawing die 16 was placed above the outer can 24.

Next, as shown in FIG. 6 described above, the first drawing die 16 is lowered, and the first drawing die 16 is pressed while pressing the upper end of the upper opening of the outer can 24 with the projecting portion 17 of the knockout 18. By inserting the mold 16 into the upper opening of the outer can 24, the upper opening of the outer can 24 is reduced in diameter until it becomes equal to the width (L ₇ ) of the body of the outer can 24. The step portions 25 of 24 were further projected inward to form bent portions 40 having a width (L ₁₂ ) of 15.4 mm. Subsequently, as shown in FIG. 7 described above, the second drawing die 16 is removed from the outer can 24 by raising the second drawing die 16, and then the second curl die 21 is removed from the outer can. 24 above.

Next, as shown in FIG. 8 described above, the first curl mold 21 is lowered and the sealing plate 35 is pressed by the projections 22 of the nack-out 23 to form the first curl mold 21. By contacting the inner peripheral surface of the recess 20 with the upper end of the upper opening of the outer can 24, the upper end of the upper opening of the outer can 24 and the insulating gasket 3
The rising portion of No. 2 was further bent inward to form a bent portion 41 following the outwardly curved side of the sealing plate 35 at the periphery of the sealing plate 35. After this, the second
As shown in FIG. 9, the outer can 24 was removed from the curl mold 21 and the lower mold 1 to manufacture a prismatic nickel-metal hydride secondary battery.

In the battery shown in FIG. 9 described above, gas is generated in the outer casing 24 due to overcharging, short-circuit, or the like, and the gas pressure passes through the gas vent hole 34 of the sealing plate 35. When the safety valve 36 is added to the safety valve 36, the safety valve 36 is made of an elastic material, so that the safety valve 36 is lifted and a gap is formed between the safety valve 36 and the sealing plate 35. As a result, the gas flows into the gap and the gas vent hole 37 of the hat-shaped terminal plate 38.
To the outside to prevent the battery from being ruptured. The explosion-proof mechanism is of a return type.

In such a manufacturing method, FIG.
As shown in FIGS. 0, 11 and 13, the outer peripheral surface is formed by using a drawing die 4 in which the surface 7 corresponding to the curved side of the sealing plate 35 of the inner peripheral surface of the hollow portion 2 has an outwardly curved shape. A curl mold 10 is used in which the upper opening of the can 24 is reduced in diameter, and the surface 13 corresponding to the curved side of the sealing plate 35 of the inner peripheral surface of the rectangular recess 9 is curved outward. This allows the upper end of the upper opening of the outer can 24 to be bent inward following the curved side of the sealing plate 35. As a result, it is possible to prevent the insulating gasket 32 interposed between the bent portion 41 of the outer can 24 and the side of the sealing plate 35 from being locally compressed. It is possible to prevent the plate 35 from being deformed. Therefore, it is possible to improve the airtightness of the battery.

Further, the upper end of the upper opening of the outer can 24 is bent inward following the curved side of the sealing plate 35, so that a short circuit or overcharging causes the inner can 24 to be bent. The outer can 24
The surface on the longitudinal direction side of the upper opening can be suppressed from being curved. Therefore, it is possible to maintain high airtightness when the internal pressure increases. The second drawing die 16 and the second curling die 21 have the same effects as those of the first drawing die 4 and the first curling die 10. In fact, the experiment described below confirmed that the battery manufactured in Example 1 had excellent characteristics.

First, as the battery of Comparative Example 1, a drawing die having a hollow inner surface formed with a flat surface and a curling die having a concave inner surface formed with a flat surface were used. Other than
A battery manufactured by the same manufacturing method as in Example 1 was prepared. However, since the insulating gasket was excessively compressed during the sealing step, the sealing plate was warped and deformed.
The batteries of Example 1 and Comparative Example 1 were not provided with an explosion-proof function for a pressure resistance test described later.

The batteries of Example 1 and Comparative Example 1 were 10
Each battery was prepared, a booster was attached to the body of the outer can of each battery, and the gas pressure at which gas leaked from the sealed portion was measured with a pressure sensor. The results are shown in Table 1 below. Table 1 Sample Gas pressure at which gas leakage occurred (kg / cm ² ) Example 1 11-13 Comparative Example 12-11

As is clear from Table 1, the battery manufactured by the method of Example 1 has a pressure resistance of 11 to 13 kg / cm ^2. It is clear that the airtightness can be improved. In contrast, the batteries manufactured by the method of Comparative Example 1 had a withstand voltage of 2 to 11
kg / cm ² And it was recognized that the sealing plate was warped.

Further, after the bending step shown in FIG. 9 described above, the radius of curvature (R ₁ ) of the curved surface formed by the rising portion 26 and the bent portion 41 of the outer can 24 determines the thickness of the outer can 24 by t. 1.5t ≦ R ₁ ≦ 3
It is desirable that the width t of the bent portion 41 be larger than the thickness of the outer can 24.

[0026]

As described above in detail, according to the present invention, there is provided a method for manufacturing a prismatic sealed battery capable of preventing a sealing plate from being deformed in a sealing step and improving airtightness. can do.

[Brief description of the drawings]

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

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

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

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

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

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

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

FIG. 10 is a sectional view of the drawing die of FIG. 1 along the line AA.

FIG. 11 is a cross-sectional view of the curl mold of FIG. 3 along the line BB.

FIG. 12 is a top view of a group of sealing lids serving also as an explosion-proof function and a terminal in FIG. 1;

FIG. 13 is a top view of the prismatic sealed battery in FIG. 9;

FIG. 14 is a top view of a prismatic sealed battery manufactured by a conventional manufacturing method.

[Explanation of symbols]

2 ... hollow part, 3 ... opened inner peripheral surface, 4 ... first drawing die, 6 ... knuck out, 8 ... hollow part, 9 ... recess, 10 ...
1st curl mold, 12 ... knuck out, 14 ... hollow part,
15 ... The inner peripheral surface that has been widened, 16 ... Second drawing die, 18 ...
Knuck out, 19 ... hollow part, 20 ... concave part, 21 ... second
Curl mold, 23: Knuck out, 24: Outer can, 25
... stepped part, 31 ... rectangular hole, 32 ... insulating gasket, 35
… A sealing plate.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideaki Kitazume 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Co., Ltd. (56) References Japanese Utility Model 2-22562 (JP, U) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) H01M 2/02

Claims (1)

(57) [Claims] 1. A step of accommodating a power generating element in a bottomed rectangular cylindrical metal outer can having a step formed by expanding an upper opening, and two longitudinal sides facing each other. There the rectangular metallic sealing plate having a curved shape outwardly, a step of placing the bottomed rectangular cylindrical insulating the gasket having a rectangular hole in the bottom, the step portion of the insulating gasket the outer can The step of placing on the upper part, a hollow cylindrical hollow portion is provided at the center portion, and the lower end inner peripheral surface of the hollow portion is expanded to the outside, the drawing die and the hollow portion of the drawing die freely
Using a knuckout that moves up and down, inserting the drawing die into the upper opening of the outer can while pressing the upper opening of the outer can with the knuckout, and closing the upper opening of the outer can A step of compressing the rising portion of the insulating gasket inward by reducing the diameter to the size of the body of the outer can, and a square tubular hollow portion provided at the center and the hollow portion
A curl mold having a rectangular concave portion having a larger vertical and horizontal dimension than the hollow portion formed at a lower end of the curl mold and the hollow of the curl mold
Knuck out that can move up and down freely from the part to the square recess
And holding the curl mold against the upper end of the upper opening of the outer can while holding down the metal sealing plate of the outer can with the nack-out, and using the upper end of the upper opening of the outer can. And compressing and fixing the sealing plate with the insulating gasket by bending inward.The method according to claim 1, wherein the drawing die includes an inner peripheral surface of the hollow portion of the sealing plate. The surface corresponding to the curved side has an outwardly curved shape, and the curl mold has an outer peripheral surface corresponding to the curved side of the sealing plate on the inner peripheral surface of the rectangular recess. A method for producing a prismatic sealed battery, characterized by having a curved shape.