Patent ID: 7360387

Claim:
An upsetting method, comprising the steps of: preparing a plurality of guides each having an insertion hole penetrated in an axial direction for holding a bar-shaped raw material in a buckling preventing state; inserting and holding the raw material secured to a fixed die in each insertion hole of the plurality of guides in order; then expanding a first exposed portion of the raw material exposed between a first guide located at the foremost side of the plurality of guides and the fixed die by moving the plurality of guides in a direction opposite to a moving direction of a punch in a mutually adhering manner while pressurizing the raw material in the axial direction with the punch; and after completion of movement of the first guide, expanding a second exposed portion of the raw material exposed between a second guide and the first guide by relatively moving the second guide located behind the first guide among the plurality of guides in a direction opposite to a moving direction of the punch.