Patent ID: 6386013
Filing Date: 2002-05-14
Classification: B21D

Abstract:
A method of forming a container lid with a thinned peripheral lip, comprising the steps of:first, performing a blanking step by shearing a blank from planar sheet stock of generally predetermined stock thickness, wherein the blank is composed of at least a central portion and a peripheral annular lip portion circumferentially bounding the central portion and lying generally in a plane; second, performing a clamping step by clamping the peripheral annular lip portion between first and second clamping elements, one against each face of the blank, wherein at least the first clamping element carries a thinning means for thinning the peripheral lip portion by relative movement between the thinning means and peripheral lip portion; third, performing a thinning step by oppositely relatively displacing the central portion of the blank and the peripheral lip portion, transversely to the plane of the peripheral lip, while applying through the clamping elements a predetermined clamping force of a magnitude allowing relative movement between the peripheral lip portion and the thinning means with resultant thinning of the lip portion to less than said generally predetermined stock thickness.