To provide a coining method by which the fatigue property of the whole sheared hole is improved by imparting sufficient and uniform compressive residual stress to both ends of the sheared hole and the whole inner peripheral surface of the sheared hole in the coining of one time.
An object of coining having the sheared hole is placed on a first die and the object of coining is pressed against the first die by a second die which is opposed to the first die. While inserting a center core which is projected from the distal end of a conning punch which is opposed to the second die and makes a set with the first punch into the sheared hole from one end of the sheared hole until arriving at the second die, the other end and the inner peripheral surface of the sheared hole are deformed plastically by the second die and the center core and also burrs which exist in the peripheral part of the one end of the sheared hole are crushed by the coining punch.
| JPS54104092A | 1979-08-15 | |||
| JP2006181633A | 2006-07-13 | |||
| JPS63123536A | 1988-05-27 | |||
| JP2009248162A | 2009-10-29 | |||
| JPS6182937A | 1986-04-26 | |||
| JPH01177035U | 1989-12-18 |
Takashi Ishida
Tetsuji Koga
Hiroshi Kamematsu
Nakamura Asayuki
Nagasaka Tomoyasu
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