Empirically derived equations for predicting springback in bending

Abstract

(1) An empirical equation has been developed that predicts springback for a variety of die geometries on the basis of yield strength, thickness, and bend radius; and for some die conditions for bend angle, hold-down, plan view curvature, and punch-to-die clearance. Since an internally consistent rationalization of the predictive equation has also been developed, the predictive equation would appear to have some general validity. However, the extent of this validity cannot be established until it has been more thoroughly evaluated. (2) By using variation analysis of the predictive equation for springback, important insights have been established about the interrelationships between variation in springback; variation in yield strength; variation in thickness divided by the nominal thickness, (R/t); and nominal yield strength. This analysis indicates the importance of interactions between the causative variables on variations in springback.