Finite Element Analysis And Mold Design On Micro Deep Drawing Of The Rectangular Box

With the development of micro-mechanical and micro-electromechanical systems,the demand of micro-parts increases gradually.The micro-deep drawing technology is concerned because of its advantages of high efficiency,low cost and mass production.However,as a plastic deformation method at micro scale,the forming theory and production experience of micro-deep drawing are still not mature enough,which restrict the application of micro-deep drawing technology.Micro-deep drawing process can form all kinds of cavity and various factors affected its complex forming process.However,most of the existing researches focus on cylindrical parts but few researches on rectangular boxes.In this paper,the micro-deep drawing of the micro square box-shaped pieces was investigated with the method of numerical simulation and the influence factors were concluded.According to the research results,a micro deep drawing mold suitable for forming box-shaped pieces was designed.Aiming at the phenomenon of scale effect in microform,the existing constitutive theory about scale effect was arranged and analyzed.Based on the modified surface layer model,the constitutive relationship of the material with the face-centered or bulk-centered cubic lattice was deduced.Then finite element numerical simulation of the micro-deep drawing process of cylindrical parts was carried out according to the constitutive relationship.The experimental results were compared with the simulation results in order to verify the validity of the proposed model.The modified surface layer model was applied to the micro-deep drawing simulation of box-shaped parts.The parameters about workpieces,mold and forming process were selected as variables in the analysis.The contrast analysis results through finite element analysis were as follows:The round shape and the straight edge forming process of box-shaped parts influenced each other.This phenomenon was similar to the traditional drawing process.The grain size of sheet metal material affected the micro drawing force and the thickness of workpieces.The die clearance,punch radius and the processing quality of mould parts had impact on the micro drawing force.But the effect of punching speed on micro drawing force was little.The study of the forming law of box-shaped parts was important for the mechanism of micro-deep drawing,process design and mold design.Based on finite element analysis results and combined with the micro-deep drawing characteristics,i.e.small size and special shape of box-shaped pieces,the sizes of punch and die and other parameters were optimized.On this basis,a set of micro-deep drawing mold was designed.In order to avoid the influence of manual feeding process and unloading process to workblanks and workpieces,an automatic feeding mechanism and a flexible unloader were designed.It was proved that the mold had reasonable structure and moved without interference through motion simulation.The mold structure could provide reference for the design of micro molds with the same type.