Abstract: Took the dynamic changes of vibration displacement of cold rolling mill roller in vertical direction into consideration, based on the Bland-Ford-Hill rolling force model, established a dynamic rolling force model. According to this formula of rolling force, through the rolling force and roll flattening radius conditions for decoupling calculation, the explicit calculation expression of rolling force is derived. On this basis, further considered the vibration influence of rolling mill’s mechanical structure, established the nonlinear vertical vibration equation of roll system contained dynamic rolling force, what’s more by using harmonic balance method, solved out the primary resonance amplitude-frequency characteristic equation of system. Last but not least, take the actual mill parameter for an example conducted a simulation research, analysed how dose the parameters which including equivalent nonlinear stiffness of a mill system, damping, extraneous force and so on affect primary resonance amplitude-frequency characteristic of rolling mill. And studied on the dynamic bifurcation characteristic of system when there is a change of external disturbance force, found that with the changes of the external disturbance force, the rolling mill will make periodic, period-doubling, chaotic motion and a series of complex movement, provided an effective theory reference for the research of inhibition of rolling mill vibration problem.

Key words: Cold rolling mill, Dynamic rolling force, Nonlinear, Vertical vibration