Research On Forming Mechanism And Shape Law Of Cross Wedge Rolling Based On Hexagonal Prism Billet

High speed rail is indispensable in the transportation system.The rail will be abandoned after a long time of using.In order to save resources and expand the product range of cross wedge rolling(CWR),the forming mechanism and shape law of hexagonal prism billet is studied in this paper.The rail head of the secondary reuse is rolled into a circular shaft,which not only bears the torque,but also the vertical force,lateral force,traction force and braking force.Therefore,the mechanical properties and forming quality of the products are highly required.In this paper,the rotating condition,deformation mechanism,quality and microstructure uniformity of hexagonal prism CWR were studied to research the forming mechanism and shape law and mechanical properties of products.In this paper,the numerical simulation analysis of CWR of hexagonal prism billet is carried out by using deform finite element software.The key technology of CWR of hexagonal prism billet is studied in combination with the macro rolling experiment and micro metallographic experiment.The four aspects of rotation condition,deformation mechanism and microstructure uniformity are studied in detail.In order to improve the formability,quality and microstructure uniformity of hexagonal prism billet,the finite element model(FEM)of CWR of hexagonal prism billet was established.The influence of forming angle,broadening angle and section shrinkage on the length of the concave was analyzed.The results were compared with CWR of round billet under the same parameters,and the concave of hexagonal prism billet is slightly larger than the length of the concave of the round billet,the influence trend of the technological parameters on the concave of the hexagonal prism billet and the round billet is basically the same.In this paper,the strain and stress fields in the deformation mechanism of hexagonal prism CWR are analyzed,and their distribution rules are obtained.In order to solve the problem of end concave,the end shape of hexagonal prism blank can be changed to reduce the length of concave.The temperature field,the average grain size and the dynamic recrystallization volume fraction of hexagonal prism billets during CWR are analyzed.The macro rolling experiment and micro metallographic experiment of hexagonal prism blank and round blank are carried out.The size of the error is obtained by comparing the experimental results with the finite element simulation.The feasibility of CWR of hexagonal prism billet is further verified by the experiment.The results of this paper provide theoretical guidance for the reasonable determination of technological parameters of hexagonal prism billet CWR,expand the range of CWR products,play an important role in reducing product cost and reasonable reuse of secondary waste products,have key engineering application value and scientific research significance for improving the quality of rolling products.