METHOD OF FORMING HOLE WITH ROUNDED EDGE AND DEVICE FOR FORMING HOLE WITH ROUNDED EDGE

摘要

A device for forming a hole with a rounded edge. The device has a punch (1) having a rounded shape (5) formed at the base of its foremost end (2) and also has a die (8) for supporting the peripheral edge of a punched hole (4) by a pressure receiving surface (9) normal to the axis of the punch, where the punched hole (4) is formed by being punched by the foremost end (2) of the punch (1). In one stroke of the punch (1), a workpiece (3) is punched by the foremost end (2) of the punch (1) to form the punched hole (4) and, at the same time, the rounded shape (5) of the foremost end (2) is transferred to that ridge (6) at the punched hole (4) that is on the aesthetically-designed surface (3a) side. A hole with a rounded edge can be efficiently formed, and because the peripheral edge of the punched hole (4) is supported by the pressure receiving surface (9), a uniform and highly accurate rounded shape (7) can be added to the ridge (6) of the punched hole (4).