MEMBER HAVING CHAMFERED THROUGH HOLE, AND METHOD OF MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a method of manufacturing a member having a chamfered part by which a burr-like unnecessary part on the inner peripheral side can be removed by a press working after forming the chamfered part on both ends. SOLUTION: This method includes: a prepared hole punching step for forming a prepared hole is formed on a planar part 70 when forming the chamfered through hole having a chamfered part on both ends; a first chamfering step for forming the first chamfered part 11 by striking a first punch; a second chamfering step for forming a second chamfered part 12 by striking a second punch on which an approximately columnar central pressurizing part having a second tapered surface and an annular corner part protruding from the middle and on the tip is provided and also the central recessed part 14 where is recessed inward in the axial direction is formed; and a punching and finishing step for punching and removing an unnecessary part 75 protruding inward in the radial direction by punching it with a finishing punch. The punching and finishing step is performed toward the second chamfering part 12 from the first chamfering part 11 by using a finishing punch 25 the outside diameter of which is the same as the corner part in the central pressurizing part or smaller than it. COPYRIGHT: (C)2009,JPO&INPIT