Stability analysis of the rolling process and regenerative chatter on 2030 tandem mills

Chatter in the rolling stack of high-velocity tandem mills and temper mills is a widespread problem and affects the quality of the finished product and the productivity of the rolling mill. One factor that clearly plays an important role in causing mill vibration is the inherent gap between the roll chocks and mill housings. In order to control chatter in cold rolling operations, a much deeper understanding of the basic mechanics of the problem is required. Therefore, this paper proposes a rolled piece vibration model for comprehending instability of the strip due to the variation of the friction coefficient in the roll bite. Subsequently, owing to the time delay effect of the chatter marks between the immediate stands, a regenerative chatter model is developed and stability analysis of the regenerative chatter model due to negative damping is presented. Finally, for a more detailed understanding of the regenerative chatter phenomena, a simulator is developed and industrial investigations are carried out in practice. It follows from the numerical simulations and industrial investigations that regenerative chatter is a more serious vibration phenomenon than simple chatter.