Frequency analysis of chatter vibrations in tandem rolling mills

Chatter in high speed tandem mills affects the quality of the product and the production rate of the rolling mill. It may also cause damage to mill components and strip rupture. To monitor chatter generation within the rolling mill, it is highly recommended to use online chatter detecting systems. This paper presents a set of guidelines to optimal control and prevention of chatter in rolling mills. Investigation is based on experimental results of the third octave chatter in a two-stand tandem rolling mill. Online vibration monitoring system that was used has provided different acceleration signals from various components of the rolling stand. Acceleration signals have been analyzed by a vibration analysis toolbox. Frequency analysis and signal processing techniques were used for examining the vibration data. From frequency spectrum analysis it is found that the prominent frequency in the vibration spectrum of the upper backup roll is the most significant one. It is demonstrated that the upper backup roll and top housing are more sensitive to chatter than the work rolls and they are suitable locations for installing the permanent acceleration sensors for chatter warning system.