Patent ID: 6508096
Filing Date: 2003-01-21
Classification: B21D

Abstract:
A draw stretch process for shaping a work piece initially comprising an elongated metal sheet having a pair of spaced opposite ends, said process comprising:placing said metal sheet in a metal forming position in a draw stretch forming machine between a bulldozer having a female forming surface and a die having a male forming surface, said sheet being positioned such that said ends thereof project laterally outwardly beyond said surfaces, said surfaces being complemental and configured to draw said metal sheet into a predetermined shape, said bulldozer being movable relatively toward the die from a draw initiating position where it is adjacent the metal sheet to a fully closed metal sheet shaping position, said draw initiating position and said fully closed position being spaced apart a predetermined distance; partially drawing the workpiece by moving said bulldozer toward said die with the workpiece therebetween a distance D1 from said draw initiating position to a working position located between said draw initiating position and said fully closed position; stretching the partially drawn work piece by pulling outwardly on said ends thereof after the bulldozer has reached said working position and continuing said stretching until any puckering or gathers in the workpiece are relieved; completing the drawing of the work piece by moving the bulldozer toward said die with the relieved work piece therebetween a distance D2 from said working position to said fully closed position to thereby give said work piece its final predetermined shape; and stretching the shaped work piece again by pulling outwardly on the ends thereof after the bulldozer has reached said fully closed position to thereby give the shaped work piece memory, to set its shape, and to work harden the same; wherein the ratio of D1:D2 ranges from about 1.5:1 to about 19:1.