Study On Time Delay Feedback Control And Vibration Performance Of Rolling Mill’s Main Drive Coupling System

The torsional vibration phenomena occurring in frequently rolling mill workingprocesses will reduce the steel products’ quality and yield efficiency, even destory therolling equipments, so the researches about the torsional vibration are very practicalsignificance. This study discuss the influence of multi-time delay feedback on thenonlinear dynamics behavior based on nonlinear torsional vibration system of rolling mill.In the context of electromechanical coupling, the control impact of the electromagneticstiffness and damping on bifurcation and chaos is investigated in this paper, whichcompletes mill vibration theory and control method in further research.Firstly, considering a kind stick-slip friction, the dynamics equation of couplingnonlinear torsional rotation system of rolling mill is established. The dynamical behaviorsof the system under multi-time delay feedback with two state variables are discussed.Characteristic roots and the stable regions of time delay are determined by Direct Method.The relation between two time delays ratio and time delay feedbacks gains with the stableregions of time delay is analyzed. The direction and stability of Hopf bifurcation aredecided by normal form theorem and center manifold argument. Finally, numericalsimulations can confirm the validity of the conclusions.Secondly, the dynamic equation of some nonlinear torsional vibration system ofrolling mill with two masses has been established, which contains a kind of nonlinearsick-slip friction. Chaotic motion and the control effect of multi-delay feedbacks of thenonlinear relative rotation system under external excitation are investigated. When thesystem is in chaos under external excitation, the multi-time delay is applied to control thechaotic motion. The chaotic critical conditions of parameters about Smale commutationare given in terms of Melnikov theory, while the influence of multi-delay feedbacks on thesystem movement station and chaotic critical conditions is studied. The control impacts ofmulti-time delay parameters on chaotic motion are studied by phase diagram, Poincaremap and power spectrum, separately.Thirdly, the nonlinear electromechanical coupling dynamics equations of rolling millmain drive system is established based on energy method. Choosing the electromagnetic stiffness and damping as bifurcation parameters, Hopf bifurcation points are solved withthe aid of multiple time scales under external excitation. Finally, the impact of theelectromagnetic stiffness and damping on chaotic motion are studied by bifurcationdiagram, Lyapunov and Poincare map, respectively.