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