Punch unit for punching a hole in a soft metal sheet

摘要

A punch unit (1) is provided with: a punch (2), which is reciprocally driven in a punching operation; and, a die (3), which cooperates with the punch (2) in punching a hole in a soft metal sheet (i.e., workpiece not shown). In this punch unit (1): punch guides (12, 13a) and the die (3) are integrally formed into a punch block (11); and a radial clearance between the punch (2) and the die (3) is set at a value of from 4 to 15% of a thickness of the soft metal sheet to be punched; and, the punch unit (1) is further provided with a sheet hold-down means (5) the sheet hold-down means (5) functioning to hold down the soft metal sheet when the soft metal sheet is punched.