Analysis of the Mechanics for Drawing Polyvinyl Chloride Tubes over an Expanding Mandrel

Abstract

An analysis is presented of the mandrel drawing process in which a tubular polyvinyl chloride (PVC) billet is drawn over an expanding mandrel so as to achieve a tubular product having a high degree of molecular orientation in the hoop and axial directions and enhanced mechanical properties. The stress and deformation behaviour of material moving over the mandrel are determined from equilibrium considerations and modelling of the material using the Ogden representation. Experimental results from drawing tests carried out on a large-scale test facility are presented and the effects of mandrel semi-angle, mandrel exit diameter and processing temperature on drawing behaviour are evaluated. Good agreement is shown between the experimental results and theoretical predictions of final product thickness, die exit stress and drawing load.