Research on vibration characteristics of mill rolls based on nonlinear stiffness of the hydraulic cylinder

Abstract Considering the nonlinear stiffness constraint action from the hydraulic cylinder in the four-high rolling mill process, the vertical vibration dynamic model with two degrees of freedom is established. The nonlinear vertical vibration equation of roll system contained the nonlinear stiffness of the hydraulic cylinder is established on the basis of D'Alembert's principle, and the amplitude-frequency response of the vibration system is obtained by using average method. According to the actual parameters of rolling mill, the influence of the nonlinear stiffness of the hydraulic cylinder and external force on the amplitude-frequency response of the rolling mill is analyzed. Based on it, the behavior of mill vibration under the effect of different nonlinear stiffness is studies. The results show that the nonlinear stiffness of the hydraulic cylinder is larger and the rolling mill system is more unstable. The mill vibration behavior will gradually converge to stability when the nonlinear stiffness is weaker, and the mill vibration will be in a state of instability and divergent when the nonlinear stiffness is stronger. This conclusion provides a theoretical basis to suppress vibration of rolling mill.