STEPPED TRIMMING PUNCH Russian patent published in 1998 - IPC

FIELD: plastic metal working, namely blank trimming at forming operations. SUBSTANCE: punch has working end with 16 portions whose cutting edges are arranged along circle in vertical direction in such a way that cutting edges of first 5 portions are directed upwards, cutting edges of further 4 portions are directed downwards, cutting edges of next 4 portions are also directed upwards and cutting edges of last 3 portions are directed downwards. Cutting edges of linear portions of each of said opposite-direction groups of edges are placed at the same level relative to working end of punch. Cutting edges of linear portions of groups of cutting edges of the same direction are placed diametrically opposite. EFFECT: improved design. 4 dwg