Nonlinear torsional vibration dynamics of rolling mill´s drive system under spindle angle parametric excitation

Considering the effect caused by the spindle angle and friction force of roll gap on the main drive system of rolling mill, the nonlinear torsional vibration dynamical equation of rolling mill´s drive system is established, which contains parametrical stiffness and nonlinear friction damping. The amplitude-frequency characteristic equation and bifurcation response equation are obtained by solving the dynamical equation using the multi-scale method. The example analysis was carried out on the 1780 rolling mill of Chengde Steel Group. It is shown that the increase of motor´s disturbance torque will aggravate the vibration of rolling mill´s drive system; the motor´s disturbance will enlarge when the angle is too large or too small. Then the reasonable control range of spindle angle is determined. It is best to keep spindle angle between degree of 2 and 5.