Machine for punching hole in metal sheet - acts with matrix using annular punch with cutting edges which are inclined w.r.t. sheet surface

摘要

The machine uses an annular punch (2) to cut a circular hole in a metal sheet (5) or similar, the punch entering a matrix (3) opening (4) over which sheet (3) is mounted. The cutting edge (7) or edges of the punch are uniformly inclined at a relatively acute angle to the plane containing the sheet, the trailing (9) and leading (8) ends of successive cutting edges (7) being interposed by axial steps. The arrangement reduces the force necessary to effect a cut, and the cutting edge may be subdivided into two half circular similarly inclined lengths separated by equal axial steps.