Model-data joint identification of rolling mill parameters and multi-frequency external disturbance excitation

• Develop a dynamic rolling force model under the influence of variable friction . • Develop a vertical-horizontal coupled model for roll system with tilted spring. • Model parameters are efficiently identified based on experimental data. • Rolling conditions have a significant effect on the model parameters. • Resonance of roll will be more intense under multi-frequency excitation. Complex nonlinear factors exist in the rolling interface of the mill, resulting in a rich nonlinear dynamic behavior of the roll system. Accurate dynamic model and parameters are the prerequisite for correctly analyzing the vibration characteristics of the roll system. In this paper, the influence of roll vibration on the friction state of rolling deformation zone is considered, and the dynamic rolling force model under the influence of variable friction factors is established. The vertical-horizontal coupling nonlinear dynamic model of the roll system under the action of dynamic rolling force is further established for the electric press-down mill, in which the tilting of the press-down stud caused by vibration is taken into account. The roll vibration acceleration signals are collected through experiments, and the equivalent stiffness, equivalent damping, dynamic change of rolling force and external disturbance force in the model are identified by extended Kalman filtering algorithm. The identification results are verified by the experimental data of dynamic rolling force. Based on the identification results, the 6th order sinusoidal approximation functions of the external disturbance forces are established. The effects of parameters on the amplitude-frequency characteristics of 2nd super-harmonic resonance, 1/2 sub-harmonic resonance, and the combined resonance of the roll under multi-frequency excitation are analyzed. The findings of this study can provide theoretical guidance for mill parameters design and rolling process selection to improve the stability of the mill.