Study On The Folding Defects Control For Extrusion Forging The Part With Branch

The branch-type forgings are indispensable parts in engineering field,widely used in aerospace,weapons and equipment,automobile industry and petrochemical engineering,etc,trade.In order to adapt to its complicated and changeable working conditions and strict requirements of mechanical properties,mainly adopting extrusion forming.But it is easy to produce defects in extrusion forming,and folding is one of the most sensitive defects.Therefore,it is urgent to control effectively the folding defects of such forgings.In this dissertation,the folding defects of branch-type forgings in the process of extrusion forming was conducted as the research object,and explore the influence of technological parameters on the folding degree.Firstly,the three dimensional thermal coupling model was established by using DEFORM-3D software,by studying the distribution characteristics of stress,damage fields and streamline of the mesh,it explored the flow laws of deformation metal and the formation process of folding defects during forming process.The evolution process and influence of folding defects on microstructure and properties were predicted by using the theory of cellular automata.Secondly,numerical simulations were adopted to study the influences of forming parameters on the metal flow laws,folding degree and streamline of the mesh,such as punch velocity,punch size parameter and motion form,the distance of die arc end and the annular plane of punch and cross-section shape of branch.Again,a prediction model of maximum folding length is established to get the primary and secondary relationship between the main technological parameters influence on the folding degree by using the response surface method.At last,the reliability and accuracy of the FEM numerical model and the maximum folding length model had been verified through experimental research on the folding defects of branch-type forgings extrusion process.Based on the systematically studying of folding defects and metal streamline of the branch-type forgings extrusion forming process,this paper has an important economic and academic value to obtain high quality and defect-free forgings...