ANALYTICAL AND EXPERIMENTAL-STUDY OF THE DIE DRAWING OF CIRCULAR RODSTHROUGH CONICAL DIES

An analysis is presented of the process of die drawing isotropic polym ers, in the form of circular rods, to produce highly oriented material s with enhanced mechanical properties. The stresses in a small element of material undergoing the drawing process have been analyzed using a force-equilibrium approach and the initial yield and flow stresses in the material have been predicted from the von-Mises yield criterion. The stress-strain-strain rate characteristics of the polymer used in t he analysis were deduced from uniaxial tensile test data obtained at t he same temperature at which the die drawing occurred. Experimental re sults are presented of the stress in polypropylene GSE-108 rods when d ie drawn at 90-degrees-C in a purpose-built die drawing facility. Nove l techniques were used to determine the stress and strain distribution s along the die. A comparison of the experimental results and the anal ytical predictions shows good agreement.