Single-stage nosing of thin-walled tubes into hollow spheres using a die

Abstract

In recent work, the present authors reported a thorough analysis of the mechanics of nosing thin-walled tubes into hollow spheres using a die and proposed enhancement of the formability limits of the process by means of preforming stages and preliminary tube-end preparation schemes. In an effort to improve the surface quality and dimensional accuracy and to extend further the formability of thin-walled hollow spheres, the present authors now report a new single-stage process based on the utilization of an innovative tool design consisting of two sharp-edge dies and a floating ring. The overall performance of the new proposed process is evaluated by means of numerical simulations based on the finite element method and experimentation on industrial aluminium alloy 6060 tubes under laboratory-controlled conditions.