| 摘要 |
An upsetting method capable of executing diameter expansion of a diameter expansion scheduled portion of a raw material unevenly in a peripheral direction is provided. A guide 20 having an insertion hole 21 for receiving and holding the diameter expansion scheduled portion 2 of the raw material 1 in a buckling preventing state is prepared. A diameter expansion preventing protruded portion 22 protruded in an axial direction of the guide 20 is integrally formed at a part of a tip end portion 20 a of the guide 20 . The diameter expansion scheduled portion 2 of the raw material 1 secured to the fixed die 10 is inserted and held in an insertion hole 21 of the guide 20 . Subsequently the diameter expansion scheduled portion 2 of the raw material 1 exposed between the tip end portion 20 a of the guide 20 and the fixed die 10 is expanded in diameter in a state in which diameter expansion of a contacting portion of the diameter expansion scheduled portion 2 in contact with the guide protruded portion 22 is restrained by moving the guide 20 in a direction opposite to a moving direction of the punch 30 while moving a punch 30 and pressurizing the diameter expansion scheduled portion 2 of the raw material 1 with the punch 30 in an axial direction.
|
