2021 Volume 60 Issue 1 Pages 182-185
As vibration while rolling reduces productivity and strip quality, causes of vibration and measures for normalization have been investigated and reported so far. Most of those vibration related report cases of large sized mill for steel strip production, and cases of medium sized mill were rare. In this study, characteristics of vibration in medium sized cold strip rolling mill have been investigated. A specification of medium sized cold strip rolling mill and a kind of rolling condition for copper alloy strip were assumed, and the natural frequency of various kinds of vibration have been calculated theoretically based on those assumption. The vertical displacement natural frequency of a 4HI type mill and a 6HI type mill have been calculated based on mass–spring model. As cold strip rolling is conducted under front tension and rear tension, deflective strip vibration is easy to occur. The strip deflective natural frequency while rolling has been calculated. Also natural frequency of torsional system of the mill has been reported.
In general, sustained vibration of rotating system is mainly resulted from resonance or self–excited vibration. On both cases, vibration frequency is close to natural frequency, and vibration is easy to occur at lower natural frequency. Natural frequency of medium sized strip mill has lower natural frequency compared to that of large sized steel mill, so the former mill has stable tendency usually.
