Patent ID: 6522979
Filing Date: 2003-02-18
Classification: B21D

Abstract:
A method for selecting a suitable workpiece having a material composition and a thickness for forming an article, the method comprising the steps of:a) selecting a workpiece; b) obtaining a yield strain for the workpiece material; c) determining whether the article has at least one straight bend wherein each straight bend defines a respective straight bend axis; d) inputting a straight bend radius and a straight bend angle for each straight bend, and calculating a straight bend strain across each respective straight bend axis in response to a determination that the article has at least one straight bend; e) comparing the respective straight bend strains to the workpiece yield strain in response to calculating at least one straight bend strain; f) classifying the workpiece unsuitable, selecting an alternative workpiece, and returning to step (b) in response to at least one straight bend strain being at least equal to the workpiece yield strain; g) determining whether the article has at least one stretch flange defining a corner axis and a centerline axis; h) inputting a bend radius, a bend arc length, a flange width, a material thickness and a contour radius for each stretch flange, and calculating a stretch flange corner strain across the corner axis and a stretch flange bottom center strain across the centerline axis for each stretch flange in response to a determination that the article has at least one stretch flange; i) comparing the respective stretch flange corner strain and the stretch flange bottom center strain to the workpiece yield strain in response to calculating at least one stretch flange strain; j) classifying the workpiece unsuitable, selecting an alternative workpiece and returning to step (b) in response to either the stretch flange corner strain or the stretch flange bottom center strain being at least equal to the yield strain; and k) classifying the material suitable in response to each respective calculated strain being less than the material yield strain.