Nosing of thin-walled hollow spheres using a die: Experimental and theoretical investigation

Alves, L.M.; Vilaça, P.; Martins, P.A.F.

Key information

Authors:

Alves, L.M. (Luís Manuel Mendonça Alves); Vilaça, P. (Pedro Miguel dos Santos Vilaça da Silva); Martins, P.A.F. (Paulo António Firme Martins)

Published in

2006

Abstract

In contrast to end forming of tubes, there is no published work that addresses the manufacturing of thin-walled hollow spheres by nosing using a die. Important characteristics of the process such as the development of plastic instability modes (local buckling), thickening of the tube-wall and occurrence of wrinkling needs to be properly studied. This paper presents a numerical and experimental investigation of the nosing of thin-walled hollow spheres using a die with the purpose of examining the process mechanics, obtaining a better understanding of the modes of deformation and establishing the formability limits in terms of the major process parameters. The paper also presents a new concept of nosing thin-walled hollow spheres that makes use of preforming stages and tube end preparation schemes in order to successfully extend the formability limits of the process. Theoretical investigation and process development are supported by numerical predictions based on the finite element flow formulation and the overall methodology is assessed by means of experimental tests on industrial AA6060 Aluminium alloy tubes (natural aged) under laboratory-controlled conditions.