Prediction of the limiting redrawing ratio

Abstract

Abstract Redrawing process is used for reducing the lateral dimensions and increasing the depth of the cylinder cup, which was formed by deep drawing. To determine the optimum values of the process parameters, it is necessary to know the redrawability. In this paper, a new mathematical mode is established to predict the limiting redrawing ratio (LDR), which is based on Hill’s anisotropic criteria, tensile instability in the cup wall and sheet bending/unbending theory around the die arc radius. The maximum and minimum thickness ratio (tmax/tmin) of cup wall and friction effect were considered in the model. The calculation from the model is in good agreement with the results of finite element simulation, and also was confirmed by the experiments of commercially pure titanium (TA1) cup redrawing processing. The effects of various material properties, friction coefficient μ, radius of the die arc rd, half die cone anger α, half die opening ro, cup maximum thickness tmax, cup thickness ration tmax/tmin have been discussed to understand and control redrawing process for improving redrawablity.