Patent ID: 8037731

Claim:
A forging method comprising: setting a workpiece inside a die, pressing the workpiece by a top part of the die in an axial direction toward a bottom part of the die, and making a material of an end face of the workpiece form a top end face of the workpiece into a shape having an eccentric ring-shaped recess and a projection, wherein, at the time of the pressing, a basic pressure is applied to the top end face of the workpiece at a location of the projection to be formed in the top end face of the workpiece by pressing the top part of the die in the axial direction toward the bottom part of the die, and, a first pressing and holding means applies a first pressure, independent from the basic pressure, to press and hold the top end face of the workpiece, surrounding the location of the projection to be formed in the top end face of the workpiece, to form the top end face of the workpiece into the eccentric ring-shaped recess and the projection, and press forming an eccentric ring-shaped recess and a projection in a bottom end face of the workpiece, by a stationary cylindrical bottom part of the die, wherein a second pressing and holding means applies a second pressure to a cylindrical outer circumference of the bottom part of the workpiece, and wherein a third pressing and holding means applies a third pressure to an inside of the cylindrical outer circumference of the bottom part of the workpiece.