Research On Forming Theory Of Shafts In Warm Cross Wedge Rolling

Currently,Shafts forming technology in CWR(Cross Wedge Rolling)requires heating the billet above the full recrystallization temperature.In the entire forming process,the heating energy consumption accounts for more than 90% of the total energy consumption.Therefore,rolling with reduced temperature can realize the following benefits: energy saving and emission reduction,green manufacturing,bring economic benefits to enterprises,and meet the needs of an economical society.Because the forming process of cross wedge rolling shafts is complicated,the rolling temperature is directly related to the plasticity and microstructure evolution of the rolled parts.If the rolling temperature is directly reduced,it will cause various defects in rolled products,and even damage the mold and rolling mill equipment.In this paper,the research on forming theory of shafts in WCWR(Warm Cross Wedge Rolling)is carried out,the optimization of process parameters is proposed,the mechanism of rolling forming is analyzed,the forming quality of rolled products is guaranteed,and the green and energy saving type of CWR is promoted.In this paper,42 Cr Mo is used as the material of rolled products.Through the combination of numerical simulation and rolling experiments,the theory of rolling forming of shafts in WCWR is systematically studied.Through the comparison between the WCWR and HCWR(Hot Cross Wedge Rolling)in terms of force energy parameters,heating energy consumption,forming quality and temperature change,etc.Obtain the advantages and disadvantages of the two types of shafts forming processes,and clarify the types of defects that are prone to occur in the WCWR.In order to solve the surface defects of the rolled parts in the WCWR,the single factor test method was used to study the influence of the area reduction,forming angle,broadening angle and rolling temperature on the surface quality of the rolled products.The relationship between the area reduction and the selection of forming angle and widening angle is obtained.The orthogonal test is designed to obtain the optimal combination of forming process parameters.The variation of the process parameters on the quality and force-energy parameters of the WCWR is studied.The distribution of temperature field,stress field,strain field and stress-strain change in the core of rolled products during WCWR are studied,and the mechanism of shafts forming in WCWR is obtained.Finally,the rolling experiment and the metallographic experiment are carried out.The metallographic experiment shows the evolution of the microstructure at different positions of the shaft formed by the WCWR.The rolling experiment results are basically consistent with the simulation results,and the shape error is 1.12%.The rolling experiments verify the reliability of the finite element simulation and the accuracy of the theoretical analysis conclusions.The research results in this paper provide a reference for the selection of suitable process parameters for the WCWR,and provide theoretical guidance and experimental basis for improving the forming quality of the forming shafts by WCWR,it can also promote the transformation of cross wedge rolling process to green energy-saving manufacturing process,and further expand the application range of cross wedge rolling process.