Study On Key Technology Of Forming Shaft End By Closed Cross Wedge Rolling

With the increasing of demand of shaft parts in railway and automobile industry,the material utilization ratio and quality of production and the performance requirements are also getting higher and higher.At present,cross wedge rolling(CWR)has been widely used in the forming of shaft parts because of its high efficiency and energy saving,however,shaft end produce the concave heart during rolling process and need to set stub bar,and lead to the highest utilization rate of material 85% and difficult to improve,which is a bottleneck for CWR.Therefore,this paper proposes a new technique of closed rolling shaft to solve the defect of concave heart.This paper adopts an order of research from back to front,at first,the rolled parts is formed by open rolling,and the change of stress,strain,rolling-force,rolling-moment is analyzed during shaft end forming process,and illuminate the flow rule of metal and influence rule of technique parameters on mechanical parameters.At the same time,the main factors: shaft end length,step length,step angle,reduction of area,conduct an interaction test,and the primary and secondary of influence of technique parameters for quality of shaft end,and the theoretic relationship of shaft end length and technique parameters is obtained by regressing,at last,a corresponding rolling experiment is implemented,the results of experiment and simulation is almost the same.On this basis,the shaft end forming research by closed CWR is implemented,according to the forming mechanism of closed CWR shaft,a variable angle wedge block is designed to avoid the loose defect which is caused by end metal being squashing in the core.Besides,the stress and strain filed during closed CWR is analyzed,and the flow rule of metal is illuminated.For the axial-bulge defect which excite in shaft surface by closed CWR,this paper innovates a new guide,rectangle-guide is turn into running pulley guide to precise forming surface of rolled part,and effective solve axial-bulge.At last,for improving the quality of shaft end,the methods of “flat-end closed-open rolling” and “alien-end closed-open rolling” are proposed,and the forming mechanism of alien-end rolling is researched,and corresponding rolling experiment is carried out.The researches of this paper provide reliable theoretical basis for solve the concave heart of shaft end,and enrich the diversity of shaft parts,and improve the utilization of material,provide the theoretical guidance for actual production...