APPLICATION OF THE UPPER-BOUND PRINCIPLE FOR SOLVING THE ROLL FORCE IN HEAVY RAIL ROLLING BY UNIVERSAL MILL
应用上限原理求解重轨万能轧制过程轧制力

For heavy rail rolling by universal mill, a simplified 3-dimention theoretical model is built firstly. The kinematically admissible velocity fields of the web, head and base of rail are determined, respectively, and the corresponding strain rate fields and the intensity of shear strain rate are also obtained. Then the plastic deformation power, the friction powers and the powers consumed on the velocity discontinuity surface are obtained. According to the upper-bound principle, the roll force of horizontal roll and two vertical rolls can be obtained. Moreover, the roll force can also be calculated by the formula of slab rolling under the same deformation condition. The roll force from the formula of slab rolling differs greatly from the field data, and the roll force from upper-bound method is somewhat greater than the field data but in general the difference is less than 13 percent. So, it is more reliable to preset and optimize the parameters of rolling technology according to the upper-bound method.