METHOD AND APPARATUS FOR PROCESSING HOLE WITH ROUNDED EDGE

摘要

An apparatus for processing a hole with a rounded edge includes a punch 1 having a rounded shape 5 formed at a base portion of a cutting tip 2, and a die 8 supporting a peripheral edge of a pierced hole 4 formed through piercing by the cutting tip 2 of the punch 1 with a pressure receiving surface 9 perpendicular to a punch axis. By driving the punch 1 to make a single stroke motion, a hole is pierced in a workpiece 3 by the cutting tip 2 of the punch 1 to form the pierced hole 4 and the rounded shape 5 of the cutting tip 2 is transferred onto a ridge portion 6 on the side of a design surface 3a of the pierced hole 4. This permits efficient processing of holes with a rounded edge. In addition, by supporting the peripheral edge of the pierced hole 4 with the pressure receiving surface 9, a uniform and highly accurate rounded shape 7 can be formed on the ridge portion 6 of the pierced hole 4.