Investigation Into The System And Numerical Simulation Of Warm Micro-extrusion

With the rapid development of the micro-electro-mechanical-system(MEMS)and the microelectronic industry,the miniaturized micro-products have been the focus. However,the traditional micro-fabrication technologies have been unable to satisfy the demands of processing three-dimensional microparts as well as the volume production, and the extending the multiplicity of engineering materials.Micro-extrusion,one of the microforming methods,can be used to form the microparts with complex structures in mass production.Warm micro-extrusion process is proposed to solve the insufficiency of cold and hot micro-extrusion,and the corresponding system of warm micro-extrusion is designed.In addition,the ABAQUS software is used to simulate the warm micro-extrusion.The concerning investigations are as follows:Firstly,the system of warm micro-extrusion is studied and self-designed,including laser heating part,extrusion mould,temperature controller for die heating,loading part, feeding mechanism and three-dimension micro-moving platform etc.Noncontact laser-assisted heating method is used to heat the workpiece.The workpiece can be selectively heated through controlling laser power and the spot diameter,which has the advantages of good controllability and high efficiency.The operating principle of the system is also described.Secondly,in order to study the "size effect" related to flow stress,the micro-compression experiment is carried on.And relations between flow stress and deformation degree,strain rate as well as different lubrication conditions have been investigated.Then,the correction of flow stress in compression is discussed,and bulging method is carried on to the flow stress revision,the maximum of revised flow stress reduces about five percents compared with the original stress.Obtained true stress-strain curve can be used as the input data for the following finite element analysis.Lastly,ABAQUS/Explicit module is used to simulate the process of warm micro-extrusion for the aluminum alloy,and to explore the flow behavior of billet in extrusion cylinder and the influences of different processing parameters on forming rules.The parameters' effects on formability,such as forming temperature,extruding speed,different lubrication conditions,are analyzed mainly from equivalent strain distribution,stress distribution,extrusion force,temperature distribution and flowing rate.All the results provide the support to optimize the mould design.Crown in extruded parts is used as the standard to evaluate the formability in warm micro extrusion.