JPH10321198A - Battery can and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery can in which lightening weight and increasing electric capacity are possible, and the internal pressure resistant strength and the axial load strength of a bottom portion are improved. SOLUTION: In this integral forming battery can, the thickness of a bottom portion 4 is 0.130 to 0.195 mm, the thickness of a side wall portion 2 is 0.070 to 0.195 mm, and an annular coining portion 6 is formed on the peripheral edge of the bottom portion 4. After a steel plate of 0.130 to 0.195 mm thick is drawn into a cup body, one time or more of re-drawing is conducted so as to form a flange portion. A side wall main portion 35a1 of uniform thickness is formed by ironing, a side wall upper portion 35a2 thicker than the side wall main portion 35a1 is formed just below a flange 35c, and thereafter the side wall upper portion 35a2 is removed by trimming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery can used as a container which also serves as a terminal for alkaline manganese dry batteries, rechargeable nickel-cadmium batteries, rechargeable lithium-ion batteries, rechargeable nickel-metal hydride batteries and the like, and a method of manufacturing the same. About.

[0002]

2. Description of the Related Art In recent years, portable telephones, portable audio equipment, portable computers and the like have been remarkably popularized, and dry batteries and rechargeable batteries serving as power sources for these devices are expected to be lightweight and have high electric capacity (long life). It is rare. In order to respond to these needs, a battery can used as a container also serving as a terminal of a dry battery or the like has a bottom thickness of 0.2 to 0.7 m.
m, an integrally molded battery can made of iron having a side thickness of 0.1 to 0.3 mm has been proposed (JP-A-60-180058).
No.). However, as for the size of dry batteries, etc., the outer dimensions are determined by the standard for each size such as AA, etc.
There is a problem that it is not enough to meet the needs for weight reduction and high electric capacity.

A conventional dry battery using a battery can is
The bottom portion expands outward due to an increase in internal pressure (for example, 20 kg / cm ² ) due to gas generation during overdischarge or the like, and the bottom portion is depressed inward due to a high axial load applied during caulking during sealing (see paragraph 0026). And the like, the flatness is lost. Further, the conventional battery can has a problem that when caulking for sealing when forming a dry battery or the like, a vertical wrinkle is generated in the caulked portion, or the caulked portion is loosened and leakage of the content liquid is likely to occur. Was. When a conventional battery can is used to form a dry battery or the like, a solid positive electrode mixture or the like having an outer diameter substantially equal to the inner diameter of the battery can is inserted. There is a problem that the positive electrode mixture and the like are easily damaged by being caught on the end of the electrode.

[0004]

SUMMARY OF THE INVENTION It is an object of the invention according to claim 1 to provide a battery can capable of reducing the weight and increasing the electric capacity. An object of the present invention according to claim 2 is to provide a battery can with improved internal pressure resistance and axial load strength at the bottom in addition to the object of the invention according to claim 1. The object of the invention according to claim 3 is, in addition to the object of the invention according to claim 1 and claim 2, a battery can in which a vertical wrinkle hardly occurs in a swaged portion and a swaged portion is hardly loosened during swaging. To provide. The object of the invention according to claim 4 is that of claim 1, claim 2, and claim 3
Another object of the present invention is to provide a battery can in which the positive electrode mixture or the like is not easily damaged when a positive electrode mixture or the like or a sealing body is inserted.

An object of the invention according to claim 5 is to provide a method for manufacturing a battery can that enables weight reduction and high electric capacity. The object of the invention according to claim 6 is, in addition to the object of the invention according to claim 5, a method of manufacturing a battery can in which the positive electrode mixture or the like is hardly damaged when a positive electrode mixture or a sealing body is inserted. Is to provide. An object of the invention according to claim 7 is, in addition to the object of the invention according to claim 6, to provide a method for manufacturing a battery can in which a caulked portion after being formed on a dry battery or the like is difficult to loosen. The object of the invention according to claim 8 is to provide a method of manufacturing a battery can with improved internal pressure resistance and axial load strength at the bottom in addition to the objects of claims 5, 6 and 7. To provide.

[0006]

According to a first aspect of the present invention, there is provided a battery can having a bottom portion and a cylindrical side wall formed integrally from a steel plate. Is 0.130 to 0.195 mm, and the thickness of the side wall is 0.070 to 0.195 mm.
Examples of the steel sheet include a bare low-carbon steel sheet and a surface-treated steel sheet having at least one surface treated. Integral molding refers to molding in which the bottom and side walls of the molded article are integrated, and refers to any one of drawing, re-drawing, ironing, or the like, or a suitable combination of these. A battery can formed by integral molding usually has a side wall, a bottom, and a curvature connecting the side wall and the bottom. The bottom portion may be flat, or may have a pip (a central projection serving as a terminal). The end surface of the side wall portion may be an annular plane perpendicular to the axial direction, or may be an annular slope extending inward and downward. The battery can refers to a can that serves as a container that contains a power generating element including a positive electrode, a negative electrode, and an electrolytic agent, and also serves as a terminal.

The thickness of the bottom portion is 0.195 mm or less and the thickness of the side wall portion is 0.195 mm.
Therefore, it is lightweight and has a large internal volume. Therefore, a battery using this is lightweight and has a large electric capacity,
Long life. If the thickness of the bottom is smaller than 0.130 mm, the internal pressure resistance and the axial load strength of the bottom are reduced, and it is difficult to put the bottom into practical use. Therefore, the lower limit of the thickness of the bottom is set to 0.130 mm. Side wall thickness is 0.07
When the diameter is smaller than 0 mm, the side wall portion is easily broken at the time of manufacturing, and the productivity is reduced. Therefore, the lower limit is set to 0.070 mm.

According to a second aspect of the present invention, there is provided the battery can according to the first aspect, wherein an annular coining portion is formed on a peripheral portion of the bottom portion. The coining portion is slightly dented and strengthened by compression, and has high hardness and is hardly deformed. Since the coining portion is formed in an annular shape at the bottom peripheral edge serving as a base when the bottom portion swells or dents, swelling or dent due to the internal pressure or the axial load of the bottom portion hardly occurs.

According to the third aspect of the present invention, there is provided a micro Vickers hardness (MHv, load: 100 g) at an edge portion of a side wall portion.
r. The same applies hereinafter) in the range of 160 to 240. The edge portion is an opening end portion of a side wall portion which is bent inward after being filled with a power generation element or the like in a battery can and is closely engaged with a sealing body (gasket), that is, crimped. . Usually means a portion within 5 mm in the height direction from the end face. The hardness is 24
If it is higher than 0, a vertical wrinkle is generated in the caulked portion due to a compressive force in the circumferential direction at the time of caulking, and the sealing property is easily impaired.
When the hardness is lower than 160, the strength of the caulked portion is reduced, the caulked portion is loosened by the internal pressure, and the sealing property is easily impaired. In the invention according to claim 3, the hardness is 160 to 2
Since it is 40, the generation and loosening of the vertical wrinkles in the swaged portion hardly occur.

According to a fourth aspect of the present invention, the side wall portion has a cylindrical side wall main portion and an enlarged portion formed at an opening end and having an inner diameter larger than the side wall main portion. A battery can according to claim 3. The widening portion includes an edge portion serving as a caulking portion. Since the expanded portion having an inner diameter larger than the side wall main portion is formed at the opening end, it is easy to fill the power generation element and the like, it is difficult to damage, and the amount of compression in the circumferential direction when caulking becomes large, so the caulking force And the sealing property is improved.

According to a fifth aspect of the invention, there is provided a method for manufacturing a battery can, comprising: drawing a steel plate having a thickness of 0.130 to 0.195 mm into a cylindrical cup body; The flange portion is formed simultaneously with the diameter reduction, and then ironing is performed to form a sidewall main portion having a uniform thickness.At the same time, a sidewall upper portion thicker than the sidewall main portion is formed immediately below the flange portion, and then the sidewall upper portion is formed. It is characterized by being removed by trimming.

The number of times of redrawing in one or more times of redrawing is usually 5 times or less, preferably 2 times or more. In this specification, the redrawing processing includes processing for reducing the diameter of the side wall portion of the bottomed molded body. Therefore, in the case of simply redrawing, in addition to the ordinary redrawing performed using a die having a processing corner having a relatively large radius of curvature (hereinafter referred to as simple redrawing), Japanese Patent Laid-Open No. 1-25
No. 8822, radius of curvature R of a processing corner
The ratio R / t0 to the blank thickness t0 (that is, the thickness t0 of the bottom 31b of the cup body 31 in FIG. 8) is 1.0 to 2.0.
Using a die having an extremely small radius of curvature R of 9, the side wall is stretched and redrawn while reducing the thickness, so-called thinning redrawing, and thinning re-drawing as described in JP-A-7-275961. This shall include thinning redrawing-ironing, simple redrawing-ironing, and the like, in which drawing and ironing are performed simultaneously in the same process.

In the present specification, the ironing process is a process that finally includes a process of reducing the thickness of the side wall portion of the bottomed body and making it uniform in the height direction by using a ring die for ironing. Therefore, in the case of simply ironing, it includes simple redrawing-ironing, thinning redrawing-ironing, and the like, in addition to a single ironing only consisting of ironing (hereinafter referred to as simple ironing). The thickness of the bottom of the compact formed by redrawing or ironing is substantially equal to the thickness of the steel plate as the material. Since a steel plate having a thickness of 0.130 to 0.195 mm is used as a material (blank), the thickness of the bottom is 0.130 to 0.195.
mm battery cans can be manufactured. The thickness of the side wall may be greater than the thickness of the bottom by redrawing. However, since ironing is performed in the final step, the thickness of the side wall portion is set to 0.070 to 0.
It can be 195 mm. By leaving the flange portion, the punch can be easily extracted even if the side wall portion after ironing is thin.

According to a sixth aspect of the present invention, in the method for producing a battery can, a steel plate having a thickness of 0.130 to 0.195 mm is drawn into a cylindrical cup body, and then redrawn at least once. The flange portion is formed simultaneously with the diameter reduction, and then ironing is performed to form a sidewall main portion having a uniform thickness.At the same time, a sidewall upper portion thicker than the sidewall main portion is formed immediately below the flange portion, and then the sidewall upper portion is formed. Except for this, a simple redrawing process is performed with the clearance between the die and the punch equal to the thickness of the main part of the side wall to form a step part obliquely upward and outward below the upper part of the side wall, and then pass through the outer base of the step part. The step is trimmed in the axial direction to remove the step and the portion above the step.

Since a steel plate having a thickness of 0.130 to 0.195 mm is used as a material (blank), the bottom portion has a thickness of 0.13 mm.
A battery can of 0 to 0.195 mm can be manufactured. The simple redrawing performed after the ironing is performed in a state where the clearance between the die and the punch is equal to the thickness of the main part of the side wall. Therefore, the thickness of the main portion of the side wall does not increase due to the simple redrawing as the final step. Therefore, similarly to the case of the invention of claim 5, the thickness of the side wall portion is 0.070 to 0.070.
A 0.195 mm battery can can be manufactured.
Since the trimming is performed in the axial direction through the outer surface base of the step portion, a battery can having an end surface formed of an annular slope can be manufactured.

According to a seventh aspect of the present invention, in the method for producing a battery can, a steel plate having a thickness of 0.130 to 0.195 mm is drawn into a cylindrical cup body, and then redrawn at least once. At the same time, the flange portion is formed at the same time as the diameter reduction, and then ironing is performed to form a sidewall main portion having a uniform thickness and an upper portion of the sidewall just below the flange portion which is thicker than the sidewall main portion. A simple redrawing process in which the clearance between the die and the punch is made the same as the thickness of the main part of the side wall is performed to form a first step part diagonally outward and upward, leaving a short cylindrical part below the upper part of the side wall. Simple redrawing of the portion and the first step portion to form a second step portion facing obliquely upward and outward between the portion corresponding to the first step portion and the upper portion of the side wall, and then forming the second step Axial trimming through the base of the outer surface of the part And removing the upper part.

According to a seventh aspect of the present invention, in addition to the sixth aspect of the present invention, the short cylindrical portion and the first step portion are simply redrawn to form a portion corresponding to the first step portion and an upper portion of the side wall. And a second step portion facing obliquely upward and outward is formed between the first and second portions, and then trimmed in the axial direction through the outer surface base of the second step portion. Since a steel plate having a thickness of 0.130 to 0.195 mm is used as a material (blank), the thickness of the bottom is 0.1 mm.
A battery can of 30 to 0.195 mm can be manufactured. In the final step, the short cylindrical portion and the first step portion are simply redrawn and the main portion of the side wall is not processed, so that the thickness of the main portion of the side wall does not change after ironing. Therefore, as in the case of the sixth aspect, the thickness of the side wall portion is 0.070 to 0.195 mm.
Can be manufactured. Since it is trimmed in the axial direction through the outer surface base of the second step portion, the portion corresponding to the short cylindrical portion and the first step portion, that is, the enlarged portion is formed at the opening end portion, and is formed of an annular slope. A battery can having an end face can be manufactured.

According to an eighth aspect of the present invention, in addition to the method for manufacturing a battery can according to the fifth, sixth or seventh aspect, the lower outer surface of the side wall is restrained immediately before or after the trimming. In this state, the periphery of the bottom is coined between the anvil and the punch. Therefore, it is possible to manufacture a battery can in which an annular coining portion is formed on the periphery of the bottom.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A battery can 1 shown in FIG. 1 shows one embodiment of a battery can of the present invention. The cylindrical side wall 2 connects to a flat bottom 4 via a curvature 3.
The thickness of the side wall portion 2 is uniform over the entire length, and is 0.07 to
This is a certain value in the range of 0.195 mm. Thickness t of bottom 4
Again, it is uniform and some value in the range of 0.130-0.195 mm. The thickness of the side wall 2 is equal to or less than the thickness of the bottom 3. The outer diameter of the side wall 2 is preferably 20 mm or less. The battery can 1 is preferably formed from a low carbon aluminum killed steel sheet manufactured from clean continuous cast steel substantially free of nonmetallic inclusions. A plating layer containing nickel alone, cobalt alone or nickel as shown in Table 1 is formed on the inner surface of the battery can 1 from the viewpoint of rust prevention and conductivity. Here, the numerals 1 and 2 indicate the plating type number (No.), and the “−” mark indicates “not present”.
For example, No. 1 shows that the plating layer is made of only nickel.

[0020]

[Table 1]

A plating layer containing nickel alone, tin alone or nickel as shown in Table 2 is formed on the outer surface of the battery can 1.

[0022]

[Table 2]

The plated layer may be formed by integrally forming the plated surface-treated steel sheet, or may be formed by plating after the integrated formation. The plating layer may be alloyed with a steel plate as a base. The plating layer preferably has a thickness of 0.5 to 7.0 μm. The end face 5 of the side wall 2 may be an annular plane perpendicular to the axial direction as shown by a solid line, or an annular slope inclined obliquely downward toward the inside as shown by a dotted line. In the case of the end face of the dotted line 5, the cross section is a convex arc, but the cross section may be a straight line, or the upper part may be a straight line, and the lower part may be a circular arc.

FIGS. 2 and 3 show an annular, slightly recessed coining portion 6 formed on the bottom outer surface of the battery can 1 of the embodiment of FIG. In the case of FIG. 2, the outer peripheral line 6a of the coining part 6
Is connected to the lower end of the curvature portion 3 after the coining has been formed (the lower portion has been processed by coining and is slightly shorter than before the coining portion 6 is formed). This embodiment is preferable from the viewpoint of improving the strength of the bottom 4. However, the outer peripheral line 6a of the coining part 6 and the curvature part 3 may be slightly separated. That is, the distance between the outer peripheral line 6a and the curvature portion 3 is 0 to 5
It may be t (t is the thickness of the bottom). In the case of 0, the embodiment of FIG. 2 is included. It is preferable that the width w of the coining portion 6 is not less than 2t and not more than 15t. In particular, it is desirable that the distance is 0 (mm), that is, the outer peripheral line 6a is in contact with the curvature portion before the coining is formed or is in the vicinity of the bottom of the curvature portion before the coining is formed (in the case of FIG. 2). The depth d of the coining part 6 is usually about 10 to 30 μm, and the hardness increase by coining is usually about 5 to 20 μm.
%.

The dry battery 7 shown in FIG. 4 is an example of a dry battery manufactured by using the battery can 1 as a container also serving as a terminal. The bottom part 4 of the battery can 1 is a positive terminal, and 8 is a negative terminal. 9 is a sealing body (gasket), 10 is a positive electrode mixture, 11 is a negative electrode gel, and a separator 12 separates the positive electrode mixture 10 and the negative electrode gel 11. The positive electrode mixture 10 is usually formed of a hollow cylindrical pellet, the outer diameter of which is substantially equal to the inner diameter of the side wall 2.
It can be closely connected to the inner surface. Current collector 13 is negative electrode terminal 8
Connected to 14 is a plastic package,
It is usually a printed packaging film and is called a label.

The dry battery 7 is manufactured, for example, as follows. After inserting the positive electrode mixture 10 into the battery can 1, the separator 12 is inserted, and the negative electrode gel 11 is put into the separator 12. After forming the bead portion 2a at a position slightly higher than the upper surface of the positive electrode mixture 10 on the side wall portion 2 of the battery can 1, the current collector 1
The assembled negative electrode terminal 8 and the sealing body 9 are welded together, and the lower curvature part 9a of the large diameter part of the sealing body 9 is engaged with the bead part 2a. Next, as shown in FIG. 5, after inserting the battery can 1 into the recess 16a of the anvil 16 having the recess 16a into which the lower part of the battery can 1 can be inserted exactly,
A ring-shaped pressing surface 17a1 which is narrow at the top and extends vertically in the axial direction.
The caulking tool 17 having the concave portion 17a having the upper portion is lowered to press the rim 2b of the side wall portion 2 of the battery can 1 to be bent inward at a substantially right angle, and to be in close contact with the upper surface of the sealing body 9. Then, the caulked portion 18 is formed and sealed. In FIG. 5, the illustration of the power generating elements such as the positive electrode mixture 10 and the sealing body 9 is omitted. In order to prevent the generation and loosening of the vertical wrinkles in the caulking portion 18, the micro Vickers hardness of the rim portion 2 b is 16.
It is preferably from 0 to 240. The production of the battery can 1 having the edge portion 2b having such a hardness is performed by using a steel plate having a micro Vickers hardness of 80 to 140 before plating as a blank. During the caulking operation, an axial load F is applied to the side wall 2. It is considered that the axial load F acts on the bottom portion 4 via the curvature portion 3 so as to exert a radially inward force, but the bottom portion 4 is easily dented as shown by the dashed line 4. This tendency is more pronounced as the bottom 4 is thinner.

The battery can 21 shown in FIG. 6 shows one embodiment of the invention according to claim 4, wherein the side wall portion 22 comprises a cylindrical side wall main portion 22a and an expanded portion 22b.
The widening portion 22b includes an inverted truncated conical portion 22b2 connected to the side wall main portion 22a, and a short cylindrical portion 22b1 serving as an opening. The end surface 25 of the short cylindrical portion 22b1 is an annular slope extending obliquely downward inside. Therefore, the positive electrode mixture 1
When inserting the sealing member 9 and the sealing body 9 into the battery can 22, troubles such as catching hardly occur, and the above insertion is easy. Although the cross section of the annular slope is arc-shaped in FIG. 6, the cross-section may be entirely straight or the top may be straight and the bottom may be arc-shaped.
When a battery is formed, the inverted truncated conical portion 22b2 substantially becomes a bead portion (2a), and the short cylindrical portion 22b1 substantially becomes a portion covering the sealing body 9. When caulking, the short cylindrical part 22b1
Is reduced in diameter, and the entire length of the side wall portion 22 becomes substantially the same outer diameter. Therefore, the difference between the outer diameter of the short cylindrical portion 22b1 and the outer diameter of the side wall main portion 22a is preferably about 0.2 to 0.5 mm.

Next, one embodiment of a method for manufacturing the battery can 1 having the end face 5 having an annular flat surface will be described. Board thickness 0.1
30-0.195mm steel sheet blank (not shown)
Is subjected to shallow drawing to form a cylindrical side wall 3 as shown in FIG.
A shallow cup body 30 having 0a is formed. Next, the cup body 30 is simply redrawn to reduce the diameter of the cup body 3 in which the height of the side wall 31a is slightly smaller than the diameter of the bottom 31b.
1 (FIG. 8). Further, the cup body 31 is simply redrawn to form a cup body 32 having a height of a side wall 32a almost twice the diameter of a bottom 32b and a flange 32c as shown in FIG. Next, the cup body 32 is simply redrawn to form a reduced-diameter bottomed cylindrical body 33 having a side wall portion 33a, a bottom portion 33b, and a flange portion 33c as shown in FIG. Thereafter, the cup body 33 is subjected to simple redrawing, and as shown in FIG.
A reduced-diameter bottomed cylinder 34 having a bottom 34b and a flange 34c is formed.

Next, the bottomed cylindrical body 34 is ironed by an ironing ring die 36 having an approach portion 36a, a land portion 36b and a relief portion 36c as shown in FIG. Forms a bottomed cylindrical body 35 having an increased side wall 35a and a flange 35c. The side wall portion 35a includes a side wall main portion 35a1 having a uniform thickness, and a side wall upper portion 35a2 having a larger thickness than the side wall main portion 35a1. The side wall upper part 35a2 has a wall thickness just below the flange part 35c and a side wall part 3 of the bottomed cylindrical body 34.
The outer surface connected to the short cylindrical portion 35a3, which is equal to the thickness of 4a and which has not been ironed, and the side wall main portion 35a1 are inclined downward and inward.
It has a tapered portion 35a4 equal to the inclination angle of 6a. Finally, as shown in FIG. 13, the vicinity of the upper end of the side wall main portion 35a1 is trimmed in the direction perpendicular to the axis by a rotary cutter (not shown), the upper portion 35a2 of the side wall is removed, and the end face 5 is flat and perpendicular to the axis. The battery can 1 is manufactured.

Next, an embodiment of a method of manufacturing the battery can 1 having the end face 5 having an annular slope will be described. The bottomed cylindrical body 34 shown in FIG.
A side wall portion 40a having a uniform thickness and a cylindrical side wall main portion 40a1 and a side wall upper portion 40a2 having a larger thickness than the side wall main portion 40a1 shown in FIG.
Is formed. Upper side wall 40a2
The short cylindrical portion 40a3 whose thickness directly below the flange portion 40c is equal to the thickness of the side wall portion 34a of the bottomed cylindrical body 34, and the tapered portion 40a4 whose outer surface connected to the side wall main portion 40a1 is inclined downward and inward. Has become. Next, the clearance between the die (not shown) and the punch (not shown) is changed to the side wall main portion 40a1 of the cylindrical cylindrical body 40.
A simple redrawing process is performed using a redrawing tool having a thickness equal to the thickness of the cylindrical member 41 to form a bottomed cylindrical body 41 having a side wall portion 41a, a bottom portion 41b, and a flange portion 41c shown in FIG. The side wall portion 41a includes a cylindrical side wall main portion 41a1, a side wall main portion 4
1a1, the upper wall portion 41a2 (which substantially corresponds to the upper wall portion 40a2) having a greater wall thickness, and the main wall portion 41.
It comprises a step portion 41a3 that faces obliquely upward and outward between a1 and the side wall upper portion 41a2. There is a curvature portion 41d between the main portion of the step portion 41a3 and the main portion 41a1 of the side wall.
d constitutes a part of the step portion 41a3.

At the time of the simple redrawing, the bottomed cylindrical body 4
The periphery of the bottom 40b of the zero forms the lower part of the side wall main part 41a1. The thickness of the bottom portion 40b of the bottomed cylindrical body 40 is larger than the thickness of the side wall main portion 40a1, but the thickness of the lower portion of the side wall main portion 41a1 is reduced because the redrawing process is performed using the above clearance tool. It becomes substantially equal to the thickness of the other part of the side wall main part 41a1. Next, the step portion 41a3 is trimmed in the vertical direction through the base 41a'3 of the outer surface of the step portion 41a3, that is, the upper end of the outer surface of the side wall main portion 41a1, in the trimming direction indicated by the dashed line 42, using a punch and a die type cutter. And the side wall upper portion 41a2 and the step portion 4
Most of 1a3 is removed. In this case, most of the end face 5 formed by trimming is occupied by the inner surface side of the curvature portion 41d. Accordingly, the battery can 1 having the end face 5 having the annular convex curved surface as shown in FIG. 16 is manufactured. When the radius of curvature on the inner surface side of the curvature portion 41d is extremely small, the cross section of the end face 5 is substantially straight. Curvature section 41d
If the inner surface has a slightly larger radius of curvature than in the above case, the cross section of the end face 5 has an arc shape in which the upper part is straight and the lower part is smoothly connected to this straight line.

Next, one embodiment of a method of manufacturing the battery can 21 having the enlarged portion 22b will be described. The cup body 32 with the flange portion 32c shown in FIG. 9 was subjected to simple redrawing, and the height of the side wall portion 50a was almost three times the diameter of the bottom portion 50b as shown in FIG. A bottomed cylindrical body 50 is formed. The bottomed cylindrical body 50 is ironed to have a uniform wall thickness and a cylindrical side wall main portion 51a having a uniform cross-sectional shape similar to the bottomed cylindrical body 35 (FIG. 12) as shown in FIG.
1 and upper part 51a of the side wall which is thicker than main part 51a1 of the side wall.
A bottomed cylindrical body 51 having a side wall 51a made of two is formed. The upper side wall portion 51a2 has a short cylindrical portion 51a3 having a thickness just below the flange portion 51c equal to the thickness of the side wall portion 50a of the bottomed cylindrical body 50, and a taper whose outer surface connected to the main side wall portion 51a1 is inclined downward and inward. It is composed of a part 51a4.
Next, the sidewall main portion 51a1 of the cylindrical cylindrical body 51 is simply redrawn using a redrawing tool in which a clearance between a die (not shown) and a punch (not shown) is equal to the thickness of the sidewall main portion 51a1. The side wall 52a shown in FIG.
A bottomed cylindrical body 52 having a bottom 52b and a flange 52c is formed. The side wall portion 52a has a cylindrical main wall portion 52a1 and an upper wall portion 5 having a larger thickness than the main wall portion 52a1.
2a2 (corresponding to upper side wall 51a2), upper side wall 52a
A short cylindrical portion 52a3 hanging down from 2 and a side wall main portion 52a
Step portion 5 between diagonally upward and outside between 1 and short cylindrical portion 52a3
2a4.

Next, the short cylindrical portion 52 of the bottomed cylindrical body 52
a3 and the stepped portion 52a4 are redrawn while maintaining the diameters of the side wall main portion 52a1 and the side wall upper portion 52a2.
A cylindrical body 53 having a two-stepped portion as shown in FIG. That is, in FIG. 20, 53a1 is the main part of the side wall,
53a2 is an upper side wall portion, 53a3 is an upper step portion, 53a4 is a short cylindrical portion, 53a5 is a lower step portion having a relatively small angle α with the axis, and the lower step portion 53a5 is a side wall main portion 53.
Connect to a1. Next, the base 53 on the outer surface of the upper step 53a3
a′3, that is, in the vertical direction through the upper end of the outer surface of the short cylindrical portion 53a4, that is, in the trimming direction indicated by the dashed line 54, the upper step portion 53a3 is trimmed with a punch and die type cutter, and the upper side wall 53a2 and the upper step 53a2 are trimmed. Most of the portion 53a3 is removed. Thus, as shown in FIG.
A battery can 21 having an end face 25 having an annular curved surface having a convex arc cross section is manufactured.

Next, one embodiment of coining the bottom will be described. In FIG. 22, reference numeral 60 denotes an anvil;
1 is a ring body, 62 is a punch provided with an air vent hole 62a. The anvil 60 has an outer diameter equal to the outer diameter of the side wall portion 2 of the battery can 1, a width slightly larger than the width w of the coining portion 6, and includes an annular protrusion 60 a having a flat upper surface. The ring body 61 has an inner diameter slightly larger than the outer diameter of the annular projection 60a, and has a hole 61a into which the annular projection 60a and the side wall 2 can be inserted exactly. Punch 62
Is slightly smaller than the inner diameter of the side wall portion 2 and the punch 62
The clearance between the and the side wall 2 is small within a range where the punch 62 can be smoothly inserted into the battery can 1.

With the above tools, coining is performed as follows. Annular protrusion 60a of anvil 60
Extrapolate the ring body 61 to the anvil 6
In a state where the battery can 1 is placed on the ring 0, the side wall 2 of the battery can 1 is inserted into the ring body 61. Next, the punch 62 is inserted into the battery can 1, and the peripheral portion 4 a of the bottom 4 is
Press between 0a. Due to this pressing, a slightly concave coining portion 6 is formed as shown in FIG. The coining portion 6 is formed immediately before trimming or after trimming.

[0036]

【Example】

Experimental Example 1: A continuously cast aluminum killed low carbon steel sheet having a nickel plating (2.5 μm thickness) on both sides, a thickness of 0.190 mm, and a micro-Vickers hardness (MHv) of 110 before plating is shown in FIG. 13, drawing, redrawing, ironing, and trimming were performed in the order shown in FIG. The diameter of the blank was 45 mm, the drawing ratio when forming the cup 30 (FIG. 7) was 1.5, and the redrawing ratio when forming the cup 31 (FIG. 8) was 1.
25, the redraw ratio when forming the cup body 32 (FIG. 9) is 1.2.
5. The redraw ratio at the time of forming the bottomed cylindrical body 33 (FIG. 10) is 1.
24, the redraw ratio at the time of forming the bottomed cylinder 34 (FIG. 11) was 1.16, and the ironing rate at the time of forming the bottomed cylinder 35 (FIG. 12) was 50%. A water-soluble lubricant (G2700NT: trade name) manufactured by Nippon Kogyo Oil Co., Ltd. was used as a blank and applied to the bottomed cylindrical body 34 before ironing, followed by molding. Wash 40
This was performed by spraying hot water of 60 ° C. for 60 seconds. The height of the battery can 1 is 50.3 mm and the outer diameter of the side wall is 1.
3.8 mm, thickness of bottom 4 is 0.190 mm, side wall 2
Was 0.095 mm in thickness. On the flat bottom 4 of the battery can 1, using the tool shown in FIG. 22, the width w adjacent to the curvature portion 3 as shown in FIG.
A 7 μm coining portion 6 was formed by pressing with a 60-ton general-purpose press.

With respect to the battery can 1, the coining portion 6
And the hardness of the side edge portion 2b, 20 kgf / cm ²
Bulging height of the bottom 4 when an internal pressure of
The results of testing the depth of the recess of the bottom 4 when a kgf axial load was applied are shown in Table 3 as Experimental Example 1. The application of the internal pressure was performed by applying pressure with a hydraulic pump in a state where the opening of the battery can 1 was sealed. Experimental Example 2: Table 3 shows the results of a similar test performed on a battery can 1 similar to the battery can 1 of Experimental Example 1 except that no coining portion was formed. In Table 3, the corresponding portion refers to the coining corresponding portion at the bottom, and the numerical value in parentheses indicates the hardness of the coining corresponding portion.

[0038]

[Table 3]

Experimental Example 3: Steel plate having a thickness of 0.160 mm
In the same manner as in Experimental Example 1, except that the micro Vickers hardness was 112 and the ironing rate was 47%, the same test was performed.
As shown in Table 3. Experimental Example 4: Table 3 shows the results of a similar test performed on a battery can 1 similar to the battery can 1 of Experimental Example 3 except that no coining portion was formed.

Experimental Example 5: The thickness of the steel sheet was 0.2 for comparison.
50 mm, the micro Vickers hardness is 95, and no coining part is formed, and the diameter of the blank is 51 mm, the drawing ratio when forming the cup body 30 (FIG. 7) is 1.62, and the cup body 31 (FIG. 7). 8) Except that the redrawing ratio at the time of formation is 1.31 and the ironing rate at the time of forming the bottomed cylindrical body 35 (FIG. 12) is 28%, it is manufactured in the same manner as in Experimental Example 1, The result of the same test is shown in Experimental Example 5.
As shown in Table 3. Experimental Example 6: Further, for comparison, the thickness of the steel sheet was 0.210 m.
m, the micro Vickers hardness is 97 and no coining is formed, and the blank diameter is 60
mm, the drawing ratio when forming the cup body 30 (FIG. 7) is 1.9.
1. The redrawing ratio when forming the cup body 31 (FIG. 8) is 1.3.
1. The ironing rate at the time of forming the bottomed cylindrical body 35 (FIG. 12) is 0%.
Table 3 shows the results of a similar test made as in the case of Experimental Example 1 except for the following point. In addition, although the generation | occurrence | production state of the vertical wrinkle by the caulking for dry cell production was also tested, the vertical wrinkle did not generate | occur | produce in any of Experimental Examples 1-6.

[0041]

The battery can according to the first aspect of the present invention has an effect that the weight and the electric capacity can be reduced. The battery can according to the second aspect of the invention has the effect of improving the internal pressure resistance and the axial load strength of the bottom in addition to the effects of the first aspect of the invention. According to the battery can of the third aspect, in addition to the effects of the first and second aspects of the invention, it is possible to prevent the vertical creasing of the swaged portion and the loosening of the swaged portion during swaging. To play. The battery can of the invention according to claim 4 has the advantages of the invention according to claims 1, 2, and 3, and further has a positive electrode mixture when inserting a positive electrode mixture or a sealing body. And the like are hardly damaged.

The method for manufacturing a battery can according to the fifth aspect of the invention has an effect that a battery can that can be reduced in weight and has a high electric capacity can be manufactured. According to the method for manufacturing a battery can of the invention according to claim 6, in addition to the effect of the invention according to claim 5, a battery in which the positive electrode mixture or the like is unlikely to be damaged when a positive electrode mixture or a sealing body is inserted. This has the effect that cans can be manufactured. The method for manufacturing a battery can according to the invention according to claim 7 has an effect that, in addition to the effects of the invention according to claim 6, it is possible to manufacture a battery can whose caulking portion formed on a dry battery or the like is unlikely to be loosened. . According to the method for manufacturing a battery can of the invention according to claim 8, in addition to the effects of the invention according to claims 5, 6, and 7, the battery can has improved internal pressure resistance strength and axial load strength at the bottom. The effect is that cans can be manufactured.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing a first embodiment of a battery can of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG. 1;

FIG. 3 is an enlarged bottom view of the battery can of FIG. 1 when a coining portion is formed.

FIG. 4 is a longitudinal sectional view of an example of a dry battery using the battery can of FIG. 1;

FIG. 5 is a vertical sectional view of a main part for explanation showing a state where caulking of the dry battery shown in FIG. 4 is completed.

FIG. 6 is an explanatory longitudinal sectional view showing a second embodiment of the battery can of the present invention.

FIG. 7 is a longitudinal sectional view of the cup body formed in the first step in the first embodiment of the manufacturing method of the present invention.

FIG. 8 is a longitudinal sectional view of a cup formed in a second step in the first embodiment of the manufacturing method of the present invention.

FIG. 9 is a longitudinal sectional view of the cup body formed in the third step in the first embodiment of the manufacturing method of the present invention.

FIG. 10 is a longitudinal sectional view of a bottomed cylindrical body formed in a fourth step in the first embodiment of the manufacturing method of the present invention.

FIG. 11 is a longitudinal sectional view of a bottomed cylindrical body formed in a fifth step in the first embodiment of the manufacturing method of the present invention.

FIG. 12 is a longitudinal sectional view of a bottomed cylindrical body formed in a sixth step in the first embodiment of the manufacturing method of the present invention.

FIG. 13 is a longitudinal sectional view showing a state immediately after a battery can is formed in the first embodiment of the manufacturing method of the present invention.

FIG. 14 is a longitudinal sectional view of a bottomed cylindrical body formed in a fourth step in the second embodiment of the manufacturing method of the present invention.

FIG. 15 is a longitudinal sectional view of a bottomed cylindrical body formed in a fifth step in the second embodiment of the manufacturing method of the present invention.

FIG. 16 is a longitudinal sectional view showing a state immediately after a battery can is formed in a second embodiment of the manufacturing method of the present invention.

FIG. 17 is a longitudinal sectional view of a bottomed cylindrical body formed in a fourth step in the third embodiment of the manufacturing method of the present invention.

FIG. 18 is a longitudinal sectional view of a bottomed cylindrical body formed in a fifth step in the third embodiment of the manufacturing method of the present invention.

FIG. 19 is a longitudinal sectional view of a bottomed cylindrical body formed in a sixth step in the third embodiment of the manufacturing method of the present invention.

FIG. 20 is a longitudinal sectional view of a bottomed cylindrical body formed in a seventh step in the third embodiment of the manufacturing method of the present invention.

FIG. 21 is a longitudinal sectional view showing a state immediately after a battery can is formed in a third embodiment of the manufacturing method of the present invention.

FIG. 22 is a longitudinal sectional view showing a state in which a coining portion is formed on the bottom of the battery can of the present invention.

FIG. 23 is an enlarged view of a portion B in FIG. 22;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Battery can 2 Side wall 2b Edge 4 Bottom 4a Perimeter 6 Coining part 21 Battery can 22 Side wall 22a Side wall main part 22b Expanding part 35a1 Side wall main part 35a2 Upper side wall 40c Flange part 40a1 Side wall main part 40a2 Side wall Upper part 41a3 Step part 41a'3 Outer surface base part 42 Trimming direction 50c Flange part 51a1 Side wall main part 51a2 Side wall upper part 52a3 Short cylindrical part 52a4 (First step part) Step part 53a3 (Second step part) Upper step part 53a5 ( (Step corresponding to the first step) Lower step 54 Trimming direction 60 Anvil 61 Ring body (member for restraining the lower outer surface of the side wall) 62 Punch

Claims (8)

[Claims] 1. A battery can having a bottom portion and a cylindrical side wall formed by integral molding from a steel plate, wherein the bottom has a thickness of 0.130 to 0.195 mm and the side wall has a thickness of 0.130 to 0.195 mm. A battery can having a thickness of 0.070 to 0.195 mm. 2. The battery can according to claim 1, wherein an annular coining portion is formed on a peripheral portion of the bottom portion. 3. The battery can according to claim 1, wherein the edge of the side wall has a micro Vickers hardness of 160 to 240. 4. The battery according to claim 1, wherein the side wall portion has a cylindrical side wall main portion, and an enlarged portion formed at an opening end and having an inner diameter larger than the side wall main portion. For cans. 5. After drawing a steel plate having a thickness of 0.130 to 0.195 mm into a cylindrical cup body, performing redrawing at least once to form a flange portion at the same time as diameter reduction,
Next, ironing is performed to form a main portion of the sidewall having a uniform thickness, at the same time forming an upper portion of the side wall thicker than the main portion of the side wall immediately below the flange portion, and thereafter removing the upper portion of the side wall by trimming. Manufacturing method. 6. A steel plate having a thickness of 0.130 to 0.195 mm is drawn into a cylindrical cup body, and then redrawn at least once to form a flange portion at the same time as diameter reduction.
Next, ironing is performed to form a sidewall main portion having a uniform thickness, and at the same time, a sidewall upper portion thicker than the sidewall main portion is formed immediately below the flange portion, and then, except for the sidewall upper portion, the clearance between the die and the punch is changed to the sidewall main portion. A simple re-drawing process with the same thickness as that of the step is performed to form a stepped portion diagonally outward and upward below the upper portion of the side wall, and then trimmed in the axial direction through the outer surface base of the stepped portion to form a stepped portion and an upper portion thereof. A method for producing a battery can, comprising: 7. After drawing a steel plate having a thickness of 0.130 to 0.195 mm into a cylindrical cup body, performing a redrawing process at least once to form a flange portion at the same time as the diameter reduction,
Next, ironing is performed to form a main portion of the sidewall having a uniform thickness and an upper portion of the sidewall that is thicker than the main portion of the sidewall immediately below the flange portion. Thereafter, except for the upper portion of the sidewall, the clearance between the die and the punch is adjusted to the thickness of the main portion of the sidewall. The same simple redrawing is performed to leave a short cylindrical portion below the upper part of the side wall to form a first stepped portion facing obliquely upward and outward, and the short cylindrical portion and the first stepped portion are simply redrawn. Forming a second stepped portion facing obliquely upward and outward between the portion corresponding to the first stepped portion and the upper portion of the side wall, and then trimming in the axial direction through the outer surface base of the second stepped portion. 2. A method for manufacturing a battery can, comprising: removing a step portion and a portion above the step portion. 8. The method according to claim 5, wherein in the step immediately before or after the trimming, the bottom peripheral edge is coined between the anvil and the punch while the lower outer surface of the side wall is restrained.
A method for producing a battery can according to claim 6.