Study On Nonlinear Vertical Vibration Characteristics And Control Of Cold Rolling Mill With Dynamic Rolling Force

In modern steel rolling industry, along with the increasing demanding for the qualityof the rolling mill, there is raising technical requirement for high accuracy and highdynamic performance of rolling mill. However, the vibration of the mill have a strongimpact on the quality of product; restricts the rolling speed, causing damages to the millequipment, affects the production of the steel rolling and causes significant economiclosses to the company and country.This research takes the cold-rolling mill as the study object, in order to describe thedynamic changes of the rolling force during rolling process, the paper establishes a newdynamic rolling force model based on Bland-Ford-Hill model and in addition takes theimpact of the vibration and the elastic-plastic deformation into consideration. It provides afundamental establishment of the nonlinear vertical vibration model.Base on the dynamic rolling force model, the paper studies the relationship betweenthe rolling force and the displacement of the rolling vertical vibration. On the basis ofprinciple of dynamics, the paper establishes the Single-degree-of-freedom andTwo-degree-of-freedom nonlinear vertical vibration model. Hence, it provides aneffectiveness theoretical model of the research of the mechanism and characteristics of themill flutter.Based on the nonlinear vertical vibration model, by using harmonic balance methodand multi-scale method, the paper works out the amplitude-frequency characteristicequation. Furthermore, the characteristics and discipline of the amplitude-frequency underthe changes of nonlinear parameters and structural parameters is established. As a result,the paper gets the frequency region which causes a strong vibration. Moreover, the paperstudies the dynamic bifurcation characteristic of cooled rolling mill under differentextraneous force amplitude, thus find out the conditions in which periodic,period-doubling, and chaotic motion occurred. In conclusion, as the changes of extraneousforce amplitude, the rolling mill cause different movement. Thus, this finding provides aneffective theory reference for the research of inhibition of rolling mill vibration problem. Take the two-degree-of freedom vibration system as an example, by using the controlparameters of time-delay feedback, and using the multi-scale method to solve the primaryresonance and internal resonance amplitude-frequency characteristic equation of thesystem. In additional, the parameters of the actual mill were used to conduct a simulationresearch, in which certain pairs of time-delay parameters were used to control the masterof amplitude values. As a result, the stability of the system is improved with the jumpphenomena of the internal resonance region and vibration being effectively eliminated.