Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
1999-06-16
2001-08-07
Turner, Archene (Department: 1775)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C428S610000, C428S647000, C428S679000, C428S680000, C429S163000
Reexamination Certificate
active
06270922
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a surface treated steel sheet for battery container, a battery container and a battery using same.
PRIOR ART
For manufacturing a battery container in which strong alkaline solution is packed, like a primary battery such as alkali-manganese batteries and a secondary battery such as nickel cadium batteries and nickel-hydrogen battery of which extensive demand is expected, a method of barrel plating, after press forming cold-rolled steel strip into a battery container, the so-called post-plating, or a method of press forming nickel-plating steel strip into a battery container, the so-called pre-plating, have been adopted. From these points of view, the inventors of the present application previously proposed a surface treated steel sheet having low internal resistance which is excellent for a battery container (WO 95/11527).
Further recently, a DI (drawing and ironing) forming method is increasingly used as a method of thinning wall to increase the capacity of the battery replacing the multi step deep drawing method (Published Japanese Patent Hei 7-99686). This DI forming method and DTR (drawing thin and redraw) forming method is capable of increasing the battery capacity because the container side wall being thinner than the bottom thickness allows more positive electrode and negative electrode active materials to be contained. Moreover, the thick bottom has an advantage to improve the pressure resistance of the battery. Incidentally, although the DI forming method and the DTR forming method are effective for increasing the battery capacity as mentioned above, there is a disadvantage in the continuous forming method because the deformation resistance of the material in these methods is greater than that in the conventional multi step deep-drawing forming method. Concretely, when the powdering quality (powdery dropout of the plating layer) in the cupping process of the DI forming method and the DTR forming method is inferior, the powder adheres to the die and the punch during the ironing process causing a defect in the container side wall. Although a similar phenomenon happens in the deep-drawing forming, the above-mentioned defect is more remarkable in the DI forming method and the DTR forming method because the container wall has small surface roughness and has more lustrous appearance. Thus, powdering quality is more critical in the DI forming method and the DTR forming method. Also, because the contact pressure of the material with the tool is greater in the DI forming method and the DTR forming method than that in the drawing method, favorable lubrication is required for tool duration. Therefore, materials which have a favorable powdering quality are required.
For the surface to be the outside of a battery container, as-plated steel sheet by the gloss nickel plating has conventionally been adopted. However, said gloss nickel-plating has inferior powdering quality during the press-forming. In addition, since gloss plating involves organic additives containing sulfur (for example, sulfonic acid having═C—SO
2
-group) to make electrolytically deposited crystal grains fine, sulfur is absorbed in the plating layer during electroplating, which causes the em-brittlement with sulfur promoted by the temperature rise of the material in the ironing and the stretching process of the DI forming and the DTR forming resulting in a deteriorated powdering quality.
The present invention is based on such findings and it is aimed to provide a battery container having a surface treated layer with low internal resistance at the inner surface of it and high quality and yet excellent continuous formability at the outer surface of it. And it is further aimed at a surface treated steel sheet which is suitable for producing the said battery container. Another objective of the present invention is to improve the removability of container (strippability) after the DI forming and the DTR forming. This is taken into consideration since the difficult of stripping the container from the punch (strippability) in the final pressing process is critical in the container manufacturing in addition to the above-mentioned powdering quality. At stripping, where the container is pulled out from the punch by hitching fingernails on the edge of the container, there has been a problem that an inferior stripping would cause breaking or tearing at the open end portion of the container, which deteriorated the productivity.
DISCLOSURE OF THE INVENTION
In a battery container described in claim
1
, an iron-nickel-tin diffusion layer is formed on the inner surface and an iron-nickel-cobalt diffusion layer is formed on the outer surface.
In a battery container described in claim
2
, a nickel-tin diffusion layer is formed as the uppermost layer and a nickel layer is formed under said nickel-tin diffusion layer on the inner surface, and a nickel-cobalt diffusion layer is formed as the uppermost layer and a nickel layer is formed under said nickel-cobalt diffusion layer on the outer surface.
In a battery container described in claim
3
, a nickel-tin diffusion layer is formed as the uppermost layer, a nickel layer is formed as the intermediate layer and an iron-nickel diffusion layer is formed as the lowermost layer on the inner surface, and a nickel-cobalt diffusion layer is formed as the uppermost layer, a nickel layer is formed as the intermediate layer and an iron-nickel diffusion layer is formed as the lowermost layer on the outer surface.
In a battery container described in claim
4
, a nickel-tin diffusion layer is formed as the uppermost layer and an iron-nickel diffusion layer is formed under said nickel-tin diffusion layer on the inner surface, a nickel-cobalt diffusion layer is formed as the uppermost layer and an iron-nickel diffusion layer is formed under said nickel-cobalt diffusion layer on the outer surface.
In a battery container described in claim
5
, a nickel-tin diffusion layer is formed as the uppermost surface, an iron-nickel-tin diffusion layer is formed as the intermediate layer and an iron-nickel diffusion layer is formed as the lowermost layer on the inner surface, and a nickel-cobalt diffusion layer is formed as the uppermost layer, an iron-nickel-cobalt diffusion layer is formed as the intermediate layer and an iron-nickel diffusion layer is formed as the lowermost layer on the outer surface.
A battery container described in claim
6
is one according to any of claim
1
to
5
which is manufactured using drawing, DI forming or DTR forming.
In a surface treated steel sheet for a battery container described in claim
7
, an iron-nickel-tin diffusion layer is formed on the one side of said steel sheet, that is to be the inner surface of the battery container, and an iron-nickel-cobalt diffusion layer is formed on the other side of said steel sheet, that is to be the outer surface of the battery container.
In a surface treated steel sheet for a battery container described in claim
8
, a nickel-tin diffusion layer is formed as the uppermost layer, a nickel layer is formed under said a nickel-tin diffusion layer on the one side of said steel sheet, that is to be the inner surface of the battery container, and a nickel-cobalt diffusion layer is formed and nickel layer is formed under said nickel-cobalt diffusion layer on the other side of said steel sheet, that is to be the outer surface of the battery container.
In a surface treated steel sheet for a battery container described in claim
9
, a nickel-tin diffusion layer is formed as the uppermost layer, a nickel layer is formed as the intermediate layer and an iron-nickel diffusion layer is formed as the lowermost layer on the one side of said steel sheet, that is to be the inner surface of the battery container, and nickel-cobalt diffusion layer is formed as the uppermost surface, a nickel layer is formed as the intermediate layer and an iron-nickel diffusion layer is formed as the lowermost layer on other side of said steel sheet, that is to be the outer surface of the battery container.
In a
Ohmura Hideo
Ohmura Hitoshi
Tomomori Tatsuo
Browdy and Neimark
Toyo Kohan Co. Ltd.
Turner Archene
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