Prediction of Loads and Stresses in Closed-Die Forging

Abstract

Various empirical formulas for predicting the maximum load in practical forgings are reviewed. Assuming a constant friction shear stress at the material-tool interface, the slab method of analysis is applied to the general upsetting operation under inclined surfaces. The stress and load equations are derived for plane strain and axisymmetric deformation. A method for determining flow models in practical forgings is presented. This method gives better approximations of forging loads than the fictitious disk model. The theory presented in this work is applied to a lead forging at room temperature and to a 1043 steel forging at 1180 C. The agreement with predictions and experimental results are within useful engineering accuracy.