Patent ID: 7698924

Claim:
A method for manufacturing a member having a chamfered through hole having a chamfered portion in peripheral corners located at each end of the through hole, in order to form the chamfered through hole, the method comprising: forming, in a plate-like portion, a prepared hole extending through the plate-like portion; forming a first chamfered portion by driving a first punch, which has a first tapered surface inclined corresponding to a desired chamfering shape, into the prepared hole from one side of the prepared hole, and thereby forming the first chamfered portion by the first tapered surface; forming a second chamfered portion by driving a second punch, which has a second tapered surface inclined corresponding to a desired chamfering shape and a generally columnar central pressing portion protruding from a center of the second tapered surface and having an annular corner at a tip thereof, into the prepared hole from another end of the prepared hole, and thereby forming the second chamfered portion by the second tapered surface and forming a central recess recessed axially inward from a center of the second chamfering portion by the central pressing portion; and punching out an unnecessary portion protruding radially inward of the prepared hole as a result of the forming the first chamfering portion and the forming the second chamfering portions using a finishing punch, having an outer diameter equal to or smaller than that of the corner of the central pressing portion, wherein the punching finishing step is performed by punching from the first chamfered portion toward the second chamfered portion using the finishing punch.