Third-octave-mode chatter in rolling. Part 3: Stability of a multi-stand mill

Abstract

The stability of a tandem mill is analysed by considering interstand interactions. In this part of the paper the stability of the multistand multimodal chatter model, developed in Part 1 [1], is ascertained. The general model is represented in a simplified form, which highlights only phenomena caused by strip velocity, or equivalently, strip tension variations between stands. This mechanism constitutes one of the most critical sources of self-excitation in the operation of tandem mills and leads to the most detrimental effects associated with third-octave mode chatter. As before, the theoretical analysis of the stability conditions is followed by a simulation study that shows the major dynamic trends in the mill's behaviour.