For rail rolling by universal mill,a simplified three-dimensional theoretical model was built firstly.The kinematically admissible velocity field of the web,head,and base of rail was determined respectively;moreover,the corresponding strain rate field and the strength of shear strain rate were obtained.Then,the plastic deformation power of corresponding deformation zone,the power consumed on the velocity discontinuity surface,and the power generated by backward slip and forward slip were proposed.According to the upper-bound method,the rolling force of horizontal roll and two vertical rolls could be obtained.For verifying the theoretical model,the universal rolling experiments of 18 kg/m light rail was accomplished in Yanshan University Rolling Laboratory,and the experimental data of 60 kg/m heavy rail universal rolling were obtained from the Anshan Iron and Steel Group Corporation.Compared with the experimental data,the theoretical results of rolling force for 18 kg/m light rail and 60 kg/m heavy rail universal rolling were somewhat greater than experimental data,but in general did not exceed them by 15%.Thus,the simplified model was reliable and feasible for presetting and optimizing the parameters of rolling technology according to the upper-bound method.
