Radial flow simulation of drawing and extrusion of rigid/hardening materials

A combination of rigorous relations (drawn from continuum plasticity) with pragmatic engineering arguments, leads to new approximate formulae for the stress fields and velocity profiles in some basic steady forming processes. The latter include drawing and extrusion in two (plane strain) and three (axisymmetric) dimensions.The theory derived here accuonts for wall friction and, more important, is not restricted by any particular choice of the strain hardening function. The applicability of the present analysis is limited, though, to dies of sufficiently small angles, taper and wall friction.Confidence in our results is gained by comparing them with a few consistent approximations obtained from available exact solutions in theoretical plasticity.The simplicity and usefulness of the new formulae is demonstrated by specifying the results for rigid/power-hardening materials, and evaluating the drawing limits associated with the occurrence of necking and separation at the exit of the die.It is also shown that the present approximate solution can be used for rapid evaluation of the stress field in drawing of rigid/perfectly-plastic composite (bimetallic) sheets and tubes.