Patent ID: 7555927

Claim:
A method of manufacturing a bottle-shaped can including a body having a large diameter, a shoulder that is continuously connected to an upper end of the body in an axial direction of the body and is tapered upward, a neck that is continuously connected to an upper end of the shoulder in the axial direction and extends upward, and a cap that is engaged with a male screw formed on the neck, comprising: performing a necking process on an opening portion of a cylindrical workpiece with a bottom and the body several times to form the body, the shoulder, and a portion for forming the neck that is continuously connected to the upper end of the shoulder in the axial direction and extends upward; forming a first convex in at least one of a connection portion between the shoulder and the portion for forming the neck and a connection portion between the shoulder and the body such that the first convex protrudes outward in a radial direction from the entire circumference of the connection portion; pressing a line linking the upper end to a lower end of the shoulder in a direction in which the shoulder is inclined to an inside of the bottle-shaped can to form, in a circumferential direction of the shoulder, a plurality of grooves extending in an inclined direction; pressing a lower end of the line with a mold surface having a triangular shape, with one vertex of the triangular mold surface disposed at the lower end of the line; and pressing a point on the line where the first convex is disposed to be recessed inward in the radial direction.