Control Study On The Torsional Vibration Bifurcation Of The Main Drive System Of The Rolling Mill

With the development of modernization, it has put forward higher requirementon the quality of rolled steel products in various industrial fields, so rolling millshould be with high performance index---high accuracy and dynamic performance toreach the targets. The main rolling mill drive system, especially during the processof roll biting and producing shock, often accompanies with the twist vibrationphenomenon, for the performance of speed control system is hindered by the elasticconnection between the drive motor and roller and load disturbance. Twist vibrationnot only affects the surface quality of rolled piece but also greatly reduces the maindriving system of rolling mill, even influences the safety production of drive system,producing accidents such as broken roller broken shaft. Therefore, it urgently needsto be solved for the improvement of rolling mill drive system plays a critical role inthe vibration of steel rolling industry.The content of this paper is as follows:Firstly, based on broad Lagrange principle of dissipative system, this paperstudies the mechanism of the twist vibration produced by the main transmissionsystem, establishes the dynamics equations of main drive system include nonlinearstiffness, nonlinear damping and dual nonlinear, and lays a theoretical foundation fortwist vibration study.Secondly, apply Bifurcation theory to the mathematical model of relativerotation of main transmission system, and solve the approximately catalyticallysolution of the system with harmonic balance method in multiple time scalesanalysis. Get normal form of original system directly without the center manifold.According to utilize dynamic bifurcation theory to study the stability of periodicsolutions and almost periodic solution and present stable domain boundaryconditions, to provide theoretical foundation for smooth running of rolling mill.Thirdly, on the basis of the Lagrange-Maxwell Principle, the electromechanicalcoupling dynamic equations were established, including the oscillation instabilitycaused by nonlinear friction and the researches on the nonlinear friction at load end.Then the thesis researched the sufficient conditions and necessary conditions of theHopf bifurcation of the system, and designed the state-feedback control system, aswell as adopted multiscale and harmonic balance method to determine the parameterof the control system, transferring the Hopf bifurcation point and controlling thestability and the amplitude of the Limit Cycles.Finally, the twist vibration measurement system is designed, and the dynamic experiment is finished on the twist vibration analogue platform. The feasibility andeffectively of the related theory of the twist vibration produced by the maintransmission system is verified in this paper.