Effect of the External Pressure on the Plastic Formability of Micro-Tubes in Hydroforming

摘要

Currently,micro tube-hydroforming has been developed due to its potential capability to mass-produce the micro tubular components made from metal,which are increasingly demanded by the increasing application of microsystems technology in electronics,telecommunications and medical industry.In this process,the formability of the tube material becomes poor because of the micro size effects.In this paper,a new process parameter,counter pressure,is introduced to this process in order to improve plastic deformation ability of micro-tube.This new process is called dual pressure hydroforming of micro tube.To assess the effect of the external pressure on the plastic formability of micro tubes,a crystal-plasticity finite element modeling technique has been used to simulate the micro tube expansion under internal pressure and dual pressure.In addition,GTN damage model is introduced and used in this research.It is confirmed from the present analysis that the plastic formability of micro-tubes in hydroforming can be improved significantly by increasing the external pressure.