Patent ID: 7673489

Claim:
A forging method for enlarging scheduled diameter-enlarging portions which are located at axial end portions of a bar-shaped raw material, the forging method comprising the steps of: holding an axial intermediate portion of the raw material with a holding die in a state in which the axial intermediate portion is prevented from being enlarged in diameter, and the axial end portions of the raw material are disposed in respective forming dented portions provided at axial end portions of the holding die; providing a guide in each dented portion of the holding die such that the scheduled diameter-enlarging portions are provided in insertion passages formed in the respective guides and the guides are axially movable within the dented portions; and simultaneously pressing the respective scheduled diameter-enlarging portions with punches in an axial direction of the raw material to fill the material of the scheduled diameter-enlarging portions in the forming dented portions while moving each guide in a direction opposite to a moving direction of each punch, thereby enlarging each scheduled diameter-enlarging portion in diameter, wherein each insertion passage is configured to hold the schedule diameter-enlarging portion inserted therein so as to prevent buckling of the scheduled diameter-enlarging portion when the schedule diameter-enlarging portion is pressed in the axial direction.