Analysis and Active Rejection of Chatter in Rolling Mills

This contribution is concerned with a vibration phenomenon in multistand rolling mills called (third octave) chatter. In order to analyse the dynamical system, which is nonlinear in nature, a mathemaitcal lumped parameter model of the plant is presented. This model comprises the mill stands, the strip as a coupling element of neighbouring mill stands and the hydraulic actuators. By means of the mathematical model of the coupled system the third octave chatter can be explained by an instability of the dynamic system. For the purpose of an active vibration rejection a nonlinear controller based on the PCH structure of the hydraulic system is designed.