Study On Hydraulic Forming Device And Molding Technology Of Micro - Pipe

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, however, the formability of the tube material becomes poor because of the micro size effects.This paper introduces the theory of crystal plasticity finite element method (CPFEM), and details the constitutive relation of crystal, which can be realized in ABAQUS by subroutine UMAT. A two-dimensional geometry model of the polycrystalline material is built by using Voronoi methods, and appreciate crystallographic orientation is given to each Voronoi grain based on crystallographic knowledge, then mesh unit is grouped according to the Voronoi polygon, which is controlled to be consistent with the geometry of the polycrystalline material requirements. Eventually CAE model of the polycrystalline is created in ABAQUS by INP file.A finite element simulation is implemented so as to research the phenomenon of the local thinning of microtube, which was inflated only by the internal pressure. A new process parameter, counter pressure, is introduced to this process in order to improve plastic deformation ability of micro-tube. Then the forming of the microtube is analyzed when this microtube was bulged by combined load of internal pressure and external pressure simultaneously. It is confirmed that the plastic formability of micro-tubes in hydroforming can be improved significantly by increasing the external pressure through a comparative analysis of two cases above.A mold of the microtube hydroforming is designed and a microtube hydraulic experimental platform is built so as to verify the reliability of the finite element simulation. And the experiment is controlled by using EX2N-70HN series touch screen PLC Combination Machine, so buckling phenomenon is studied in the forming process of microtube, and we analyze the impact of micro-tube wall thickness on forming process of microtube, which will lay a solid foundation for future study of bi hydroforming process of the microtube.