US Patent 7555927 Bottle-shaped can manufacturing method and bottle-shaped can

In a bottle-shaped can manufacturing method and a bottle-shaped can, a necking process is performed on an opening portion of a cylindrical workpiece with a bottom several times to form a body, a shoulder, and a portion for forming a neck that is continuously connected to an upper end of the shoulder in the axial direction of the bottle-shaped can and extends upward, and a first convex is formed 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. Then, the shoulder is pressed to the inside of the body while the first convex is recessed inward in the radial direction, thereby forming grooves in the shoulder.