On the Analysis of the Expansion and Reduction of Thin-Walled Tubes Using a Die

Abstract

The production of sound thin-walled tubular parts by expansion and reduction using a die is generally limited to components having geometrical features within a compact range. Basic design rules, relevant to process and die design are mainly derived from the accumulated experience of both manufacturers of tubular parts and suppliers of machine tools. However, gaps of knowledge can still be found in understanding the influence of process parameters on material flow and in providing an adequate description of the modes of deformation that are associated with the formability limits induced by ductile fracture, wrinkling, and buckling. The aim of the present paper is to extend the actual knowledge on the expansion and reduction of thin-walled tubes using a die by means of a comprehensive theoretical and experimental investigation. The theoretical investigation is supported by axisymmetric and three-dimensional numerical simulations based on the finite element flow formulation. The experimental work, performed on AA6060 aluminium alloy tubes, consisted of specially designed tests that were carried out under laboratory-controlled conditions with the intention of supporting and validating the overall investigation.