Anode can for battery and manufacturing method thereof
A cylindrical anode can has a sidewall extending along a central axis. The sidewall has an upper end portion having a relatively large thickness and a sidewall small portion having a thickness smaller than the upper end portion. The upper end portion is located at an end of the sidewall, and the sidewall small portion is a portion other than the upper end portion. In the sidewall, a distance (L 3 ) between an outer circumferential surface of the upper end portion and the central axis is equal to a distance (L 3 ) between an outer circumferential surface of the sidewall small portion and the central axis. A distance (L 1 ) between an inner circumferential surface of the upper end portion and the central axis is smaller than the distance (L 2 ) between an inner circumferential surface of the sidewall small portion and the central axis.
1. A method of manufacturing an anode can for a battery, the method comprising:
preparing a material member corresponding to a shape of an anode can for a battery to be produced;
forming a cylindrical body by deforming said material member so as to obtain a cylindrical body extending along a central axis and having a sidewall;
modifying a thickness by subjecting said sidewall to press working so as to form a large thickness portion located at an end portion of said sidewall and having a relatively large thickness and a small thickness portion being a portion other than said large thickness portion and having a thickness relatively smaller than that of said large thickness portion in said sidewall, the large thickness portion has an outer circumferential surface and an inner circumferential surface, the small thickness portion has an outer circumferential surface and an inner circumferential surface, a distance between the outer circumferential surface of the large thickness portion and the central axis is greater than a distance between the outer circumferential surface of the small thickness portion and the central axis, and a distance between the inner circumferential surface of the large thickness portion and the central axis is equal to a distance between the inner circumferential surface of the small thickness portion and the central axis; and
displacing the outer circumferential surface of the large thickness portion by arranging the cylindrical body having said large thickness portion and said small thickness portion formed in said step of modifying a thickness, between a die having a cylindrical opening and a cylindrical punch inserted in the cylindrical body, subjecting said sidewall to press working so that the distance between the outer circumferential surface of said large thickness portion and said central axis is equal to the distance between the outer circumferential surface of said small thickness portion and said central axis, and the distance between the inner circumferential surface of said large thickness portion and said central axis is smaller than the distance between the inner circumferential surface of said small thickness portion and said central axis,
wherein a diameter of the punch is set to such a value that the punch comes in contact with the inner circumferential surface of the worked large thickness portion but not in contact with the inner circumferential surface of the worked small thickness portion.
2. The method of manufacturing an anode can for a battery according to claim 1 , further comprising:
determining a thickness of said large thickness portion in said sidewall after modifying a thickness and before displacing the outer circumferential surface of the large thickness portion.
3. The method of manufacturing an anode can for a battery according to claim 1 , wherein said small thickness portion formed in said step of modifying a thickness has a thickness equal to that of a small thickness portion in a sidewall of an anode can for a battery to be produced.
4. The method of manufacturing an anode can for a battery according to claim 1 , wherein said step of press working includes:
inserting said punch into said opening together with said cylindrical body, a distance between an inner circumferential surface of said opening of said die and said central axis is equal to a distance between an outer circumferential surface of the anode can to be produced and said central axis, and a distance between an outer circumferential surface of said punch and said central axis is equal to a distance between the inner circumferential surface of said large thickness portion and said central axis.