JPH01313848A - Angular sealed cell and manufacture of cell container thereof - Google Patents

Abstract

PURPOSE:To obtain a thin cell container with a high-precision shape, stable sealing performance and high volume efficiency by applying ironing to a step rising side wall formed with an expanded step by drawing. CONSTITUTION:An angular cell container 1 with an expanded step 2 is molded with a nickel-plated steel plate by drawing, an ironing punch 11 with a step 12 is inserted, it is inserted into an ironing die 13 formed with a guide section 13a with the same size as the width W1 (L1) of the expanded step, a taper section 13b, and a die section 13c with the same size as the width W2 (L2) of a side wall and extruded. A cell container 1 having a step rising side wall 3a with the preset thin thickness (t2) above the expanded step 2a is obtained. A sealing plate is mounted on the expanded step 2a, the edge of the step rising side wall 31 is folded inward and pressurized to form an edge folded/fastened section, then a cell is closely sealed. The cell container with excellent sealing performance and good volume efficiency is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rectangular sealed battery in which a metal battery container is loaded with a metal sealing plate via an insulating sealing packing and sealed tightly, and a method for manufacturing the container. It is something.

2. Description of the Related Art In recent years, as electronic devices have become more cordless, there has been a demand for small, high-capacity, high-density, and highly reliable sealed batteries. In particular, for batteries that are built into devices and used for long periods of time, such as sealed nickel-cadmium storage batteries or various lithium batteries, there is a strong demand for small prismatic batteries that are easy to store, and their implementation is progressing. In the case of small, prismatic sealed batteries such as those listed above, in order to withstand the internal gas pressure that occurs during overcharging, overdischarging, or use under incorrect conditions, without reducing volumetric efficiency, Metal battery containers are used, and laser seam welding has been a common method for sealing the batteries because it is easy to ensure airtightness. However, the laser welding method requires high precision in parts processing, requires expensive equipment, and is not very productive. Especially for prismatic batteries, the production cost is extremely high, so it is generally used for cylindrical batteries. The application of the ``crimping'' sealing method, in which the open end of the battery container is bent inward to seal it, is being considered in some cases.

The ones in Figures 7 and 8 are examples of prismatic alkaline batteries.
This was disclosed in Japanese Utility Model Application Publication No. 58-169859, and in each figure, the symbol "" indicates the external appearance, and the symbol "b" indicates the longitudinal section. In each case, a power generation element is housed in a rectangular metal battery container 31, and a sealing plate 32 made of synthetic resin is fixed to the center with a negative electrode terminal 33 that also serves as a negative electrode current collector. A bead (groove) 31a protruding inward is provided near the opening edge of the container 31, a sealing plate 32 is placed thereon, and the opening edge tip 31b is bent inward to seal the container. In the case of FIG. 8, after the sealing plate is pushed into the opening edge of the battery container 31, the battery container 31 is opened.
As shown in the figure, a point-like projection (projection) 31C that projects inward is provided at a predetermined position on the opening end of the sealing plate to fix the sealing plate.

The battery whose side cross section is shown in FIG. 9 is a cylindrical sealed alkaline storage battery disclosed in Japanese Utility Model Publication No. 41-9618.
An alkaline storage battery power generation element 44 is housed in a metal cylindrical battery container 41 which also serves as a cathode terminal, and a sealing lid 43 which also serves as a metal positive terminal is placed on the enlarged step 41a with an insulating sealing ring. 42 and the battery container 4
The opening edge 41c of the side wall 41b of the first stepped portion is pressurized and bent inward to seal the battery. The height is 8 to 10111 ff by applying the method of providing the battery container with an expanding step and placing the sealing lid as in the above example.

A relatively large rectangular button-type alkaline storage battery with 50 to 6 degrees WIII in both the vertical and horizontal directions and an arc of R8 to R12 at the corner has been studied.

Problems to be Solved by the Invention In such a conventional structure, the side shape is relatively wide or vertically long as shown in FIGS. When applied to a rectangular sealed battery where the internal pressure of the battery increases, the electrolyte or gas may easily leak from the sealed part of the battery, or the side wall of the battery container may expand and deform outward. There were many. That is, FIG.

In the battery shown in FIG. 8, the strength of the seal between the sealing plate 32 made of synthetic resin and the opening edge of the battery container 31 is low, so even if the gas pressure generated within the battery is relatively low, the sealing portion It was easy for gas or electrolyte to leak out.

In the case of a battery having the enlarged step shown in FIG.
yt), including the container side wall and the opening step.
2 to 0.41 steel plate has sufficient strength, workability,
The sealing process was easy, and no problems with accuracy were observed. However, when applied to a prismatic battery, since the side wall of the battery container is flat, a steel plate of the same thickness as a cylindrical battery has low strength, and the pressure inside the battery is low, e.g. 1~s KST.
/ d, the side surface of the container was expanded and deformed. In the case of an alkaline storage battery such as the above-mentioned sealed nickel-cadmium storage battery or a lithium battery that is used in a sealed manner, the expansion at an internal battery pressure of 6 to 10 to 9/d is practically 0.3 to 0.
2 or less, it must be restored without permanent deformation.

When this condition is applied to a square sealed battery, for example, in a battery case made of nickel-plated steel with one width of 26M, the other width of 13M, and height of 60MN, the steel plate thickness is 0 to satisfy the above deformation suppression condition. It must be between .7 and 0.9. However, under these conditions, if a rectangular battery container with an enlarged step as shown in Figure 9 is manufactured using a drawing molding method such as the trimming method that is normally used in production, it will have the shape shown in the top schematic diagram in Figure 12. Easy to cause problems with defects. That is, the molded rectangular battery container 1 tends to have uneven thickness near the corner part 7, and the corner part 76 has a relatively large arc, for example, R2 when molded.
, 5 to R3MM or more, R4-Ruff is required to press and bend the opening edge of the enlarged step, but it is difficult to obtain an accurate shape due to uneven thickness. The straight part of the opening edge above the enlarged opening step 72 is not straight as shown in the figure, but is G1 on the inside. G2 is biased, and the outer periphery tends to have a wavy shape with ridges at the corners, center, and in between, resulting in insufficient precision in shape. Furthermore, when the side wall thickness of the battery container becomes large, there is a problem in that the degree of expansion shown by ΔD in FIG. 9 must be made greater than the difference in plate thickness. This is to stop the pressure applied when the edge 41a of the side wall of the raised step shown at 41b in FIG. 9 is bent inward without deforming the step. As a result, the capacity density of the battery decreases, and the effect of having a square shape is diminished. Even with these considerations, it was difficult to press and bend the mouth edge of the enlarged step portion uniformly, and there were many problems such as insufficient drip resistance.

As an improvement measure for the above problem, Figure 1o is a side sectional view of the main part.
We investigated the application of a cylindrical battery shown in a partial side cross-sectional view of the single-mouth seal. The one in Figure 10 is Utility Model Publication No. 36-26438.
Seen in the alkaline battery disclosed in the publication, the battery container 5
A part of the inner wall of the opening edge of No. 1 is removed to form an acute protruding edge 51b.
A groove (step) 51 is provided, a disc-shaped sealing body 52 is placed on the crotch, and the lip 51c of the battery container is caulked inward to seal it. Cutting out the opening edge of a rectangular battery container as in this proposal requires machining using a milling machine or the like, resulting in low productivity and insufficient machining accuracy, making it difficult to apply to production. The one in Figure 11 is from 1977-
It was disclosed in Publication No. 164 (as a similar one,
(Japanese Utility Model Publication No. 57-75477), the purpose is to reduce the degree of expansion ΔD of the expansion step 41a described in FIG. An enlarged stepped portion (61a indicates the stepped portion after post-processing) is provided at the open end of the battery container 61, and a lid piece 63 is placed on this stepped portion via a hard annular gasket 62 made of polyamide or the like. Then, by applying compressive force 64 in the radial direction as shown by the arrows using a drawing die or the like, the rising side wall 61 of the stepped portion of the battery container 61 is removed.
b is reduced in diameter and sealed. However, in this method, when the gas pressure inside the battery increases, the lid piece 63 is lifted upward in the figure to exhaust the gas.

As described above, when reducing the diameter of the upper part of the battery container, the thickness of the side wall of the battery container is 0.4n or less according to the study results of the present inventors (0.25ffj +
) is the range that is easy to process. As mentioned above, in a square sealed battery, 0.41 due to pressure resistance problem! r51 or more, 0.
It is necessary to use a steel material with a thickness of about 5 to 1 times, and the force required to shrink the side wall is large, which may deform the battery or cause the battery to become impossible to remove from the mold if a pull-out mold is used. The improvement measures also had processing issues.

The present invention solves these problems, and uses a manufacturing method suitable for production to precisely shape the expanded step provided in the battery container and to reduce the thickness of the rising side wall of the step above the step. The object of the present invention is to provide a rectangular sealed battery that is thinned to an appropriate thickness, facilitates the process of sealing the battery, has excellent sealing performance, and has good volumetric efficiency, and a method for manufacturing the same.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides that the outer surface of the rising side wall of the step part of the enlarged step part formed at the opening end is thinned by ironing and is shaped into a predetermined shape. Using a metal rectangular battery container, a metal sealing plate is placed on the shaped stepped portion via an insulating sealing packing, and the edge of the side wall of the stepped portion is bent inward and fastened. Alternatively, the edge of the side wall of the raised stepped portion is bent inward and a force is applied to the stepped side wall in a perpendicular direction to reduce the width of the upper portion of the stepped portion to seal the battery.

In addition, the present invention involves inserting a punch with a predetermined battery internal shape into a metal rectangular battery container that has been molded with an enlarged step at the opening end using a drawing process, and then inserting it into a drawing die. Extrusion is performed, and the outer surface of the side wall of the raised step above the enlarged step is ironed, and the wall thickness of this side wall is reduced to 30 to 70% of the thickness before ironing, and is shaped into a predetermined shape. This is a manufacturing method to obtain a rectangular battery container suitable for the purpose.

Effect: According to such a method, manufacturing becomes easier and processing accuracy can be significantly improved compared to conventional manufacturing methods. Furthermore, by using a rectangular battery container in which the upper part of the enlarged step part is made thinner by ironing, a reliable caulking seal can be easily made and a battery with a high degree of sealing can be obtained. Since sealing by width reduction can still be easily and accurately performed, it is possible to reduce the degree of expansion of the sealing portion and obtain a battery with excellent volumetric efficiency.

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

Embodiment 1 FIG. 1A is a perspective view of the external appearance of the sealing part at the upper part of the battery according to the first embodiment of the present invention, and shows the rising side wall of the step above the enlarged step formed at the opening end by the process described later. A metal seal in which a terminal cap 9 is attached via an insulating seal packing 6 to the enlarged step part of a metal rectangular battery container 1 whose outer surface is ironed and made thin and shaped into a predetermined shape. A plate 7 is placed thereon, and the edge of the thinned step-up side wall 3a is bent inward and fastened to form a sealed opening.

Next, the process of manufacturing a metal rectangular battery container, which is the main subject of the present invention, will be described in detail. As a metal plate, there is a predetermined container side wall thickness that can withstand the internal pressure of the battery (Fig. 2).

A nickel-plated steel plate with a thickness corresponding to z)K in Fig. 3,
Using a commonly used drawing process, the shape is sequentially formed into a cylindrical shape with a bottom or an elliptical shape, and then, as shown in the cross-sectional side view of one side of Fig. A square battery container 1 having a mouth part 2 is molded. The thickness of the side wall 3 of the raised stepped portion above the enlarged stepped portion 2 of the molded battery container 1 is the same as the side wall thickness of the lower portion of the stepped portion (t1 in the drawing). Next, as shown in the schematic cross-sectional side view of one side in FIG. W1. Guide part 1 with the same dimensions as (Ll)
3a, Tapered part 13b with a straight line or curve with an angle of 10 degrees or less, with dimensions that match the width W2 (L2) of the side wall of the stepped section after ironing shown in Fig. 3B. By inserting it into the ironing die 13 formed by the die part 130 and extruding it, the outer surface of the step riser side wall 3 above the enlarged step 2 is ironed, and the side wall of one main part in FIG. 3B is formed. As shown in the sectional view, a battery container 1 is obtained in which the thickness of the side wall 3& of the raised step above the enlarged step 2& is reduced to a predetermined value (thickness t2). By this method, the machining accuracy tolerance above the enlarged step is about 0.05, which is highly accurate. As mentioned earlier, the thickness t2 of the stepped side wall 3a differs slightly depending on the battery size (reference :W2.(I, 2)) is approximately 30W1K (equivalent to cylindrical D size) or less, it is preferable to use 0.2 to 0.4 wings. As mentioned above, in relation to the internal pressure of the battery, in a prismatic sealed battery, the thickness tl of the side wall of the battery container 1 is in the range of 0.4 to 1 mm when the width of the battery is about 3 mm or less as described above. Become. As a result of considering conditions such as workability in the sealing process, sealing strength for sealing the battery, and leakage resistance, the dimensions of the die part of the ironing die 13 are as follows:
The relationship between the thicknesses t'1 and t2 of 3a and 3a is 1:0.3~0.
7. That is, the thickness tl of the stepped side wall 3a after ironing is preferably selected from a range of 30-70% of the original wall thickness. Note that the height h of the side wall of the stepped section after ironing (Fig. 3 B) becomes flat in proportion to the ironing rate, so either calculate it in advance and adjust it during the first drawing process, or Then cut to a specified height. In the above example, a nickel-plated steel plate was used as the metal plate, but in a sealed alkaline storage battery system, a steel plate may be molded and then nickel-plated, or a nickel-clad steel plate may be used. For lithium battery systems, similar materials (as the negative electrode container) or stainless steel M17/reminium clad steel plates can be used. During the above-mentioned processing, if the stainless steel material or the like is particularly difficult to mold due to work hardening, annealing treatment is performed using a heat treatment furnace or the like.

FIG. 3C shows the appearance of the prismatic battery container power generation element 6 completed by the above steps. In this rectangular battery container, a sintered electrode plate impregnated with a nickel active material is used as the positive electrode, and a paste plate with a cadmium active material coated on the core material is used as the negative electrode.
After storing multiple sets of electrode plates with polypropylene nonwoven fabric separators interposed therebetween and injecting a predetermined amount of alkaline electrolyte, an insulator made of polyamide such as 66 nylon is molded as shown in the side cross-sectional view of the main part in Figure 4. A rectangular metal sealing plate 7 having an elastic valve body 8 made of synthetic rubber and a terminal cap 9 provided with an exhaust hole 9a fixed thereon so as to close the gas vent hole 7a is inserted into the expansion stage through the sealing packing 6. 2a, and as shown in the schematic side cross-sectional view of main parts in FIG. By placing the battery on the receiving mold 14 and applying force in the direction of the arrow to the caulking upper mold 16, the edge of the side wall 3a of the stepped portion is bent inward and pressurized to break the edge. Form the curved fastening part 4 and seal the battery to complete the process (Figure 6B).
. Note that 10 indicates a connection lead of one polarity.

Example 2 FIG. 1B is a sectional side view of a main part of one side of a rectangular sealed battery according to another embodiment of the present invention, and FIG. 6 is a side view of one side showing the sealing process of the battery. FIG.

As described in detail with reference to FIGS. 2, 3, and 4 in Example 1, a battery container (Fig. B,C
), a rectangular metal sealing plate 7 containing the power generation element 6 and having terminal caps 9 etc. arranged and fixed thereon is placed on the enlarged step part 2a via the above-mentioned insulating sealing packing 6. After that, the edge of the side wall 3& of the stepped portion is bent inward by the caulking upper die 15 shown in FIG. The dimensional width of the mouth edge of the battery container after ironing shown in W2. The guide portion 16a is L2 (see FIG. 4).

Tapered part 16b with an inclination angle of about 10 degrees or less, battery container 1
Insert it into the reduced width die formed by the die part 16c, which is approximately the same as the dimensional width of the lower part of the battery, or 0.1 to 0.2-larger than the lower part of the battery. By pushing out the battery by applying a force of +0.1 to +0.3 with respect to the lower dimension of the battery container 1. , and the side wall of the insulating sealing packing 6 is compressed to seal the battery (at this time, the thickness tl of the side wall of the stepped portion does not change).

Next, in order to see the effects of the present invention, one width of the upper part of the completed battery was 25 mm, the other width was 13 mm, and the height of the battery container was 48 mm.
A rectangular sealed nickel-cadmium storage battery with a diameter of 2 mm was manufactured. A prismatic battery container was molded using a metal plate having a thickness of 0.7 mm and having a plating layer of 5 μm on each side on both sides. In both Example 2, the thickness t2 of the rising side wall 3a of the stepped portion was reduced to about 40 inches, which was 0.3 (goods). Also, the arc R of the upper corner of the opening step (see Figures 1A and 3C) is 13 m outside the container, based on the results of the sealing experiment.
It was set as m. As a result of manufacturing under these conditions, neither Example 1 nor Example 2 caused any process problems, and the internal pressure of the battery container was 8 to 1 oKy/cm (the operating pressure of the safety valve was BK5+/di). In this case, an expansion of 0.16 to 0.2 in thickness was observed on the wide side surface, but it returned to its original state when the internal pressure of the battery decreased, and no abnormality was observed in the sealed portion. Furthermore, reliability such as leakage resistance was also equivalent to C size and 5ubC size batteries of the same type. Note that the same effect can be obtained even if the sealing plate 7 and the backing 6 are formed by insert molding in the above.

On the other hand, for comparison, the same nickel-plated steel plate as that of the present invention was used, and as an application to the shape of the conventional cylindrical battery shown in Fig. 9, the drawing method shown in Fig. 2 was used. We added a process to modify the shape of the lip above the step. As a result, the stepped portion rising side wall 3 (thickness t 1 = 0.7 m
to) and the thickness of the widening step 2, the arc of the corner above the widening step described in the present invention (approximately the same is true for the lower part of the container) is R3 to R8 mm'? However, in Example 1, even with R7-R8 mm, the enlarged step portion 2 was deformed, resulting in poor sealing. In Example 2, R
If the width is 6 or more, width reduction is possible, but the pressure to extrude the battery is too high, deforming the upper part of the stain pond, and making it impossible to extrude from the width reduction die. Furthermore, the leakage resistance of the sealed battery was also insufficient compared to the conventional cylindrical battery and the two types of batteries of the present invention. Furthermore, when comparing the degree of opening ΔD, which indicates the degree of protrusion above the widening stepped portion described in the conventional example in FIG. .6 to 1.7 (g), while that of Example 1 of the present invention is approximately 0.9 m (for reference; in the case of a reduced width battery, the width of the present invention is ~o, 1 to 0.3 mm s Conventional example ~0.2~
0.4M).

As described above, by repeatedly processing the side wall of the stepped portion of a square battery container formed by the drawing process method, it is possible to make the wall thinner and achieve high precision. By applying this battery container with a well-arranged shape, the container edge can be easily and reliably bent and fastened (sealed by caulking) in the form of Example 1, and a battery with a stable and high degree of sealing can be obtained. In the form of Example 2, the width reduction process can be easily performed with high accuracy, and a battery with stable sealing performance and excellent volumetric efficiency can be obtained.

Effects of the Invention As described above, according to the present invention, by applying ironing to the side wall of the stepped portion of a rectangular battery container formed by drawing to form an enlarged stepped portion, a thin seal can be formed. Since it can be applied easily and reliably, a battery with a stable and high degree of sealing can be obtained. Further, since the width reduction process can be easily performed with high precision, a rectangular sealed battery with stable sealing performance and high volumetric efficiency can be obtained.

[Brief explanation of the drawing]

Figures 1, 2, 3, 4, 6, and 6 show embodiments of the present invention, and Figure 1A shows a prismatic sealed battery of the present invention using a caulking method. An upper perspective view, B is a side cross-sectional view of the main parts of the rectangular sealed battery of the present invention with a reduced width sealing method, and FIGS. 2 and 3 A are side cross-sectional views showing processing steps including ironing of the rectangular battery container of the present invention. 3B and 3C are views showing the side cross section and external shape of the obtained prismatic battery container, FIG. 4 is a view showing the assembly process of the battery of the present invention, and FIGS. Fig. 6 is a side sectional view showing the sealing process of the present invention using the reduced width sealing method, and Figs. 7 and 8 show a conventional prismatic battery. Fig. 9 is a side sectional view of a conventional cylindrical battery with an enlarged step, Fig. 10 is a side sectional view of main parts of another conventional cylindrical battery, Fig. 11 1 is a sectional side view of a main part of a cylindrical battery to which the conventional sealing method by diameter reduction is applied, and FIG. 12 is a schematic top view of a prismatic battery container having a conventional enlarged step. DESCRIPTION OF SYMBOLS 1... Square battery container, 2... Enlarged stepped part during drawing process, 2a... Expanded stepped part after ironing process, 2b...・Expanded stepped part after width reduction, 3...
・Rising side wall of the stepped part during drawing process, 3a... Standing side wall of the stepped part after ironing process, 3b... Side wall of the rising step part after narrowing, 4...・・Brim bend fastening part, 4'
...... Mouth rim bent portion, 5... Power generation element, 6
...Insulating sealing packing, 7...Sealing plate, 8...Elastic valve body, 9...Terminal cap, 11...Stringing punch , 12...
・Step part of ironing punch, 13... Ironing die, 13a... Guide part, 13b... Part of putty, 13C... Taper part , 14...
... Receiving mold, 16 ... Upper caulking mold, 16 ...
・・Width reduction die, 1ea・・・Guide part, 18b
・・・・・・Taper part, 16c90. ...Die part, 17...Extrusion rod, R...Corner outer surface arc of the rising side wall of the step, x3a...The mouth edge before narrowing is bent. battery. Name of agent: Patent attorney Toshio Nakao and one other person L.
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Claims (3)

[Claims] (1) The power generating element is housed in a metal square battery container in which the outer surface of the rising side wall of the step part formed by enlarging the opening end is made thin by ironing and is shaped into a predetermined shape. , a metal sealing plate was placed on the shaped stepped portion via an insulating sealing packing, and the thinned stepped portion rising side wall edge was bent inward and tightened to form a sealed opening. Features a square sealed battery. (2) The power generation element is housed in a square metal battery container in which the outer surface of the rising side wall of the step part formed by enlarging the opening end is made thin by ironing and is shaped into a predetermined shape. , A metal sealing plate is placed on the shaped step through an insulating sealing packing, and the thinned step-up rising side wall edge is bent inward and the edge is bent in a direction perpendicular to the step side wall. A prismatic sealed battery characterized by applying force to reduce the width of the upper part of the step to create a sealed opening. (3) An ironing punch is inserted into a rectangular battery container formed by drawing a metal plate into a shape with an enlarged step at the opening end, and the ironing punch is inserted to create the specified internal shape of the container including the enlarged step. By inserting it into a die and extruding it, the outer wall of the rising side wall of the stepped portion of the battery container is ironed, reducing the side wall thickness to 30 to 70% of the original thickness and shaping it into a predetermined shape and size. A method for manufacturing a square battery container.