Research On The Vibration Mechanism Of Rolling Mill Main Drive System Bosed On Electromagnetic Coupling And Control Method

Modern iron and steel industry are advancing towards high speed, energy conservation and diversified. As an integral part of the steel industry, rolling mill is related to the long-term development of the modern iron and steel industry. Therefore,the research on the vibration mechanism of rolling mill is not only related to the improvement of industrial efficiency, but also has a very important for the development of scientific research technology.First, the main drive system of the rolling mill is composed of a power motor and a roller, which is composed of a rolling wheel, a connecting shaft and a speed reducer,modern mill generally uses AC motor as power source. When the motor and rolling mill is rigid connection, through the combination of AC motor rotor internal complex magneto electric and rotor air friction resistance, the electromechanical coupling model of one-mass rolling mill main drive system is established. A first order approximate solution of the electromechanical coupling system in resonance case is investigated by a multiple-scales method. At the same time, the influence of the frequency of the rotor induced current frequency on the nonlinear parametric resonance of the main drive system is analyzed by using the phase plane method and Poincare method, and the parameter values for the system to generate the bifurcation state.Secondly, when the motor and rolling mill are elastic connection, by combining the magnetic flux linkage equation with the mechanical system, the mathematical model of the mechanical and electrical coupling system of the main drive system of the rolling mill are established. This model gets rid of previous model's complicated integral part and inertia hinder. The influence of the magnetic flux coefficient, the time constant of the stator and the rotor time constant on amplitude and adjust time of main drive system are analyzed by numerical method. And considering asynchronous motor nonlinear factors of air friction, further researches the influence of the leakage coefficient, the time constant of the stator, the time constant of the rotor and the friction coefficient of the stator on the amplitude and the time of the load speed of the main drive system of the rolling mill.Third, according to the characteristics of the mechanical and electrical coupling system of the rolling mill, the model of the electric coupling system of the main transmission system of the rolling mill in the internal friction resistance of the AC motor are established by using the magnetic flux linkage equation and the mechanical system of the rolling mill. The bifurcation of the system under nonlinear friction damping is analyzed by the second method of Lyapunov and Routh-Hurwitz stability criterion. It is pointed out that necessary and sufficient condition for the system when the Hopf bifurcation occurs in the system, and analysis of the influence of subcritical bifurcation and voltage grid frequency on vibration of main drives system of rolling mill.Last, when the motor and rolling mill are rigid connection, according to the theory of auto disturbance rejection control, the anti disturbance control system is established,and compared with the traditional PID control system. Research results show that, the auto disturbance rejection control technology can quickly and smoothly control the mechanical and electrical coupling system of the rolling mill. It can not only improve the system's following performance, but also has a very high precision. It also has strong robustness and provides an effective control method for the rolling mill system.