Patent ID: 6223931
Filing Date: 2001-05-01
Classification: B21D

Abstract:
Strengthened can end having a central panel portion, comprising(a) a circular portion punched out of a planar sheet, said circular portion having an axis and an edge portion, said circular portion being shaped between form tools, thereby forming a circumferential groove in the edge portion, said circumferential groove having an inner wall leading through a radius of curvature into the central panel portion,(b) an annular fringe region in the central panel portion, said annular fringe region being positioned radially inside the radius of curvature and having a sheet thickness reduction constantly decreasing from a point of lowest residual thickness in radially outward direction towards the radius of curvature and having a step portion at a radially inner end of the sheet thickness reduction for strengthening the annular fringe region, reducing bulging of the central panel portion and improving orientation of the inner wall of the circumferential groove in the edge portion of the can end.