Patent ID: 8250897

Claim:
A method for producing a high strength workpiece material, comprising the steps of: placing a cylindrical mold having a vertically extending central space into a vertically extending central opening of a fixed mold in a vertically movable manner; placing a small diameter, long metal or alloy starting material into a central space of the cylindrical mold; vertically compressing both end faces of said small diameter, long starting material in said central space with a first press member and a support member, thereby causing one lengthwise end of said starting material to flow radially outward along an end face of said cylindrical mold to form an expanded part; bringing a second press member into contact with a lengthwise end face of said expanded part so as to press said expanded part against the end face of said cylindrical mold; and increasing a distance between said second press member and the end face of said cylindrical mold while decreasing a distance between said first press member and said support member, thereby continuously causing the radially outward flow from one end to another end of said small diameter, long starting material to gradually increase a thickness of said expanded part and finally produce a large diameter, short billet having an outer diameter surface abutting against a wall surface of the central opening of the fixed mold.