Patent ID: 6766677
Filing Date: 2004-07-27
Classification: B21D

Abstract:
A rotary die curl assembly comprising: a punch assembly and a die assembly axially aligned and selectively engageable with each other;said punch assembly including a punch holder mounted on a punch center, said punch holder having an annular end that extends toward said annular die assembly, said end having an axially inward and radially inward extending tip; a curling punch received within said punch holder; and a punch core mounted within said curling punch including an axially extending periphery adjacent said curling punch defining a recess therebetween; wherein said curling punch extends axially outward of said punch holder and said punch core; said die assembly including a a die holder and a curling die received within said die holder, said curling die defining a bore; a lower pressure pad mounted within said bore and slideable relative to said curling die; and a die core located within said lower pressure pad, said die core having a raised edge located beneath the recess in said punch assembly; an upper spring holder located below said curling die, said lower pressure pad, and said die core supporting at least one of said curling die, lower pressure pad and die core; and a lower spring holder located below said upper spring holder and held in spaced relation by a spacing assembly defining a gap between said upper spring holder and said lower spring holder, whereby thermal expansion of either of the punch assembly or die assembly is compensated for by said spacing assembly and said gap.