Research On Torsional Vibration Suppression Of Steel Rolling Mill System

The dynamic performance and more accuracy is mandatory in mill industry according to demand of steel rolling quality. The phenomenon of torsional vibration is ubiquitous in rolling mill system, while the mill is just rolling steel or is blocked which the load disturbance impact. The torsional vibration not only threats the mill's normal work, but also affects the quality of steel strip, and reduces the endurance life of its drive system. So how to reduce or eliminate the torsional vibration is a difficult question of research now.The torsional vibration is caused by mechanical system and electrical control system actually. As a result, the study of making the mechanical system and electrical control system as a integrated system is accord with the actual state. The reason of torsional vibration from mechanical system and electrical control system of its drive system was analyzed in theory, which causes the mill can not work well-balanced. The multi-mass model on steel mill system is established by principle of dynamics. The two-mass resonant system which has a motor and a load connected with a flexible shaft is proposed. And the effect of gap and friction is considered.The uncertainty is considered which is settled by elastic distortion of shaft stiffness and unknown perturbation. According to IMC principle, the internal model controller is obtained as considering both robust stability and robust performance constraints. The internal model controller parameters are derived to meet both robust stability and robust performance. The robust design of rolling mill system is obtained based on internal model structure. And the problem of rolling mill control system with parameters uncertainties and model structure uncertainties is solved. The robustness of this design is confirmed.Considering torsional vibration causing by rolling perturbation, model predictive control is applied to rolling mill system. The constraint condition is proposed to meet manipulated variable constraint. The optimization problem with linear inequalities can be solved by Quadratic Programming. The simulation results show that the design improves the dynamic performance and suppress torsional vibration causing by rolling perturbation. The model predictive control suppresses rolling perturbation.