Study on Vibration Asymmetry of Hot Rolling Mill with Structural Gap

Considering the asymmetry of the upper and lower structures of the hot rolling mill and the different gap of the horizontal bearing seats of the upper and lower work rolls, a horizontal–vertical coupling asymmetric nonlinear vibration model under the influence of dynamic rolling force is established. Based on the calculation and analysis of the natural characteristics of the model, the chaotic vibration theory is used to study the bifurcation behavior of the mill vibration system under the change of the upper and lower work roll bearing seat structural gaps and the change of the strip inlet thickness fluctuation amplitude. The results show that the asymmetric and symmetric structures of the mill have different effects on the natural characteristics and stability of the system, and the symmetric model has higher stability. The sensitivity of the upper and lower work roll structure gap to the system vibration is different. Simultaneously reducing the structural gap of upper and lower work rolls, or keeping the structural gap of upper work roll within the stable range of the side gap of lower work roll can improve the stability of the system. Structural gap changes and strip inlet thickness fluctuation amplitude changes can make the upper and lower work roll system into a non-synchronous chaotic state, and the existence of periodic bifurcation leading to chaotic motion and other phenomena significantly. The research results can provide reference for the theory of mill vibration suppression.