JPH0377261A - Square-type battery - Google Patents

Abstract

PURPOSE:To form a proper press depth while preventing damage of a welded part by press-molding a part to be processed of an outer can in a prescribed position for improvement of battery properties. CONSTITUTION:An outer can 1 is made of a cold-rolled steel sheet and a battery cover 2 is welded in the open part of the can. To improve the properties of a battery, a concaved part with press depth X is formed by press-machining in the side of the outer can 1 in the layered direction. The press depth X is determined properly according to the thickness of the battery can, etc. The distance Y between the welded part and the end of press-machined part and the press depth X satisfy the following relations so as not to damage the welded part; Y>=AX+C, 10<A<15, A=14t+6.1 where C is a constant number and 0<C<0.18 and (t) represents thickness of the outer can.

Description

[Detailed Description of the Invention] The present invention provides an exterior can made of cold-rolled steel plate in which a battery power generating element is housed in the interior space, and an opening of the exterior can that is welded all around. The present invention relates to a prismatic battery comprising a battery lid and a battery lid, the outer can being pressed in the stacking direction of the battery power generation elements.

Conventional Production Engineering Team In the above-mentioned prismatic batteries, in order to improve battery performance (capacity, cycle characteristics) by applying a certain pressure to the battery power generation element, an outer can was used as shown in Japanese Patent Application Laid-Open No. 126566/1983. A manufacturing method is disclosed in which the battery power generating element is pressed in the stacking direction of the battery power generating element.

Here, when integrating the battery lid with the exterior can, since it is difficult to swage uniformly a prismatic battery compared to a cylindrical battery, the two are fixed by welding. After that, the above-mentioned press working was performed.

However, with the conventional structure described above, damage to the weld may occur during press processing due to the relationship between the distance from the weld to the press end closer to the weld and the press depth. I had an issue.

The present invention has been made in view of the current situation, and it is an object of the present invention to provide a prismatic battery that can prevent damage to welded parts and improve sealing performance.

In order to achieve the above object, the present invention includes an outer can made of cold-rolled steel plate in which a battery power generating element is housed in the inner space, and a battery lid welded all around the opening of the outer can. It consists of
In a square battery in which the outer can is pressed in the stacking direction of the battery power generation element, the distance Y from the welding part to the pressed end closer to the welding part is determined by the following relationship between the pressing depth X (!: It is characterized by setting the condition of the expression.

Y≧AX+C [However, io<A<15, A=1.4t+6.1(t:
Thickness of outer can) C: Constant] As mentioned above, when setting in relation to Y; f: Even when stretched, the tensile strength does not change much. Therefore, the mechanical influence of the press-formed part on the surrounding area is reduced, so that problems such as peeling at the welded part can be prevented from occurring.

Ura-Ichi-ichi-ichi [Preliminary Experiment I] The thickness t of the cold-rolled steel plate for deep drawing (hereinafter referred to as 5PCE) was varied (0.25 fl, 0.4 mm, 0.6
B)-ζ A tensile test was conducted to examine the relationship between tensile strength and elongation, and the results are shown in FIG.

As shown in FIG. 2, it is recognized that the relationship between tensile strength and elongation rate can be divided into three stages for any thickness of 5PCB. It can be seen that in the first and third stages, the tensile strength and elongation are approximately proportional, but in the second stage, the tensile strength does not change much and only the elongation rate changes.

Here, there is no problem in the first stage because the tensile strength is low, and there is no problem in the second stage because the tensile strength is not so large. On the other hand, in the third stage, the tensile strength becomes too large. Therefore, the distance Y from the weld to the press end closer to the weld as shown in FIG. 1 may be related to the press depth X so that the elongation of at least 5 PCBs during pressing is at the second stage.

Here, when the above relationship is applied to a square battery,
This will be explained using FIGS. 3('a) and (b).

In addition, in FIGS. 3(a) and 3(b), 1 is an exterior can, 2 is a battery lid, 3 is a welding part, and 4 is a press mold.

As shown in FIG. 3(a), the press die 4 is pressed against the surface of the outer can to deform the outer can 1 by an amount am inward toward the inside of the battery as shown in FIG. 3(,b). Then, the distance Y from the weld to the press end closer to the weld extends from bllm to a''+b2.Here, the elongation rate α is given by the following (1).
Define it as in Eq.

σSe ... (1) In addition, during the above pressing, the tensile strength is given by the composite angle Q of the pressurizing force P on the outer can of the press and the repulsive force R of the welded part 30, but the repulsion of the welded part In order to reduce the force R and make it a stable value, the outer can 1 is
It is necessary to set the distance Y so that the elongation becomes the second stage elongation.

However, since the pressing depth X required to improve battery performance varies depending on the thickness of the battery can, etc., the second stage of elongation is not necessarily reached. Therefore, in order to enter the second stage elongation range, it is necessary to make the following adjustments.

[Preliminary experiment■]

Figure 4 shows the press depth X changed (0.4.im,
0°2m, 0.1m) is a graph showing the relationship between the distance Y from the welded part to the press end closer to the welded part and the elongation rate α. Incidentally, the straight line in the figure is the point where the second stage in FIG. 2 shifts to the third stage. Specifically, the thickness of the outer can is t=Q.

In the case of 6fl, the elongation rate is approximately 100.2%, in the case of the outer can thickness t-0.4m, the elongation rate is approximately 100.4%, and in the case of the outer can thickness t = 0.25u, the elongation rate is approximately 100.6%
It is.

As is clear from Fig. 4, the elongation rate α is affected by the press depth X and the distance Y from the weld to the press end closer to the weld. Even if the depth X changes, the elongation of the outer can can be made to be the second stage elongation. Specifically, the values may be set as shown in Table 1 below.

Table 1 [Consideration I] In order to secure the elongation rate α at the second stage, we investigated the relationship between the press depth It is shown in FIG. The plot points in Figure 6 are obtained by examining the intersection of the straight line of the thickness of the outer can (0.4 m in this discussion) and the press depth curve in Figure 4, and plotting this. C9 in Figure 4
~C3 point corresponds to C+""C3 point in FIG.

A regression analysis of the plot points of the X value and Y value in Figure 6 shows that Y = 10.96X + 0.03 is the boundary between the second and third stages, so Y210°96 If it is within this range, it is recognized that it will enter the second stage of elongation.

[Consideration■]

When the thickness of the outer can is 0.25 m, the range in which the elongation rate α falls into the second stage was investigated in the same manner as in Consideration I above, and the results are shown in FIG. In addition, d in Figure 4
, ~d5 points and points 41 to 41 in FIG. 6 correspond.

As a result, since Y=10X is the boundary between the second stage and the third stage, it is recognized that the elongation is in the second stage if Y≧lOX.

[Consideration■]

When the thickness of the outer can is 0.6 mm, the range in which the elongation rate α falls into the second stage was investigated in the same manner as in Analysis I above, and the results are shown in FIG. In addition, e in Figure 4
The l''-C3 point corresponds to points 01 to 03 in FIG.

As a result, since Y=14.82X+0.175 is the boundary between the second stage and the third stage, Y≧14°82X+0.
If it is within the range of 175, it can be seen that it is in the second stage of growth.

[Conclusion]

From the results of Consideration I to Consideration II above, in the formula Y≧AX+C, 10<A<15, O<C<O.

It is recognized that it is acceptable as long as it is within the range of 8.

Also, the relationship between the above A and the thickness t of the outer can is A in Fig. 6.
, from regression analysis of plot points with at, A=14t+6
．． It is expressed by the formula 1.

[Example] As shown in FIGS. 5(a) to 5(C), the prismatic battery of the present invention has an outer can 1 made of 5PCB with a thickness of 0.4 fi. A battery power generating element is housed in which positive electrode plates and negative electrode plates are alternately stacked with separators in between. A battery lid 2 is welded to the opening of the exterior can, and the exterior can is pressed into a concave shape in the stacking direction of the battery power generating elements. The external dimensions of this square battery are height 64 fl x width 16 fl x thickness 5.6 fl.
It is.

In this case, the relationship between tensile strength and elongation is as shown in FIG. 2 (t=0.4111).

From this graph, it is desirable that the elongation rate α is between 0.1 and 0.4%. In particular, if the elongation rate α is set to be slightly smaller than the maximum value, the elongation of the outer can will be at the second stage even if the pressure during pressing changes, which will ensure that damage at the welded part is not caused. It can be prevented. Therefore, in this embodiment, the elongation rate α is set to 0.3%.

On the other hand, a pressing depth of 0.2 fi on each of the front and back surfaces is necessary for performance improvement.

4゜Taking these things into consideration, looking at Figure 4 above, the distance Y from the weld to the press end closer to the weld is approximately 3t.
It is recognized that it is necessary to maintain a distance of at least m.

From the above, in the prismatic battery of this example, Fig. 5 (a
) to (c), the values (w) of A, B, C, and D are A=
59, B=12, X=0.2, and Y=3. If pressing is performed under these conditions, it is possible to reliably prevent the welded portion from being damaged before and after pressing.

As explained above, according to the present invention, even when the outer can is pressed in order to improve battery performance, 1. Since damage to the welded part due to press working can be minimized, the yield of batteries can be dramatically improved.

[Brief explanation of drawings]

FIGS. 1(a) to 1(C) are diagrams showing the press working part of a square battery, in which FIG. 1(a) is a front view, FIG. 1(b) is a side view,
Figure (C) is a plan view, Figure 2 is a graph showing the relationship between elongation rate and tensile strength when using 5PCB, and Figure 3 (
Figures a) and (b) are diagrams showing the deformation and force applied during pressing of the outer can, in which Figure (a) is an explanatory diagram before pressing, Figure (b) is an explanatory diagram after pressing, Figure 4 is a graph showing the relationship between the distance from the weld to the press end closer to the weld and the elongation rate when the press length/brace depth is changed, and Figure 5 (a)
) to (C) are diagrams showing the press dimensions in this example, where (a) is a front view, (b) is a side view, and (
C) is a plan view, and Figure 6 is a graph showing the range of the press depth and the distance from the weld to the press end closer to the weld to set the outer can to the second stage of elongation. . 1... Exterior can, 2... Battery cover, 3... Welded part, 4
...Press type.

Claims (1)

[Claims] (1) Consisting of an outer can made of cold-rolled steel plate with a battery power generating element housed in its interior space, and a battery lid welded all around the opening of the outer can, the battery power generating element is stacked in the stacking direction. A rectangular battery whose outer can is pressed, characterized in that the distance Y from the welded part to the pressed end closer to the welded part is set to the condition of the following formula in relation to the pressing depth X. Square battery. Y≧AX+C [However, 10<A<15, A=14t+6.1 (t: thickness of outer can) C: constant]