Abstract: The rolling mill is the complex mechano-electronic system controlled by computer. Improper design and some other factors may result in continuous self-excited vibration. The running faults of rolling mill influence badly product quality. Even production is interrupted. A method of self-excited vibration analysis based on multi-pa- rameter integrative testing and system identification is provided. The essential factors of the self-excited vibration phenomenon are analyzed by means of experiment and theory methods. The method of eliminating self-excited vibration is discussed too. In different operation conditions there are pure time lag in mathematic model of mill hydraulic AGC. When time lag exceeds a limit, self-excited vibration can occurs. The time lag may cause due to improper design of the mounted structures for roller gap displace trans-ducer. Through dynamics modification, the time lag of displace feedback signal is reduced to minimum in the engineering case. And self-excited vibration is eliminated.

Key words: Model structure, Self-excited vibration, Structure dynamics, System identification, Time lag