Coupled Nonlinear Vibration Characteristic And Analysis Of Four-High Mill Based On Dynamic Rolling Force

The development of rolling technology has provided certain guarantee for people's high quality life,at the same time,it has brought unprecedented challenges to rolling technology and rolling mill production.Rolling mill vibration is ubiquitous in the daily production of major rolling mills.It not only reduces production efficiency and rolling accuracy,but also reduces the service life of rolling mill system parts,increases production costs,and seriously damages the interests of the state and enterprises.Taking hot strip mill as the research object,considering the effect of elastic deformation of roll on the length of horizontal contact arc,vertical vibration displacement,horizontal vibration displacement,torsional vibration angle of main drive direction and other process parameters on rolling force,a dynamic rolling force model is proposed.And torsion coefficient and friction system are considered respectively.The dynamic torque and friction force are established.On the basis of the above models,the vertical-torsional,vertical-horizontal two-degree-offreedom and vertical-torsional-horizontal three-degree-of-freedom coupled non-linear vibration models of four-high rolling mill are established respectively.The main resonance of the two-degree-of-freedom system is analyzed by multi-scale method,and the main resonance amplitude-frequency equation is derived,and the sag of the rolling mill system with variable parameters such as external disturbance force and non-linear parameters is studied.Amplitudefrequency characteristics of straight and torsional directions and their regularities.Finally,the numerical simulation of two-degree-of-freedom system and three-degree-offreedom system is carried out with the actual process parameters of a factory.It is found that the four-high rolling mill system presents periodic motion,multiple periodic motion and chaotic motion in the vertical,torsional and horizontal directions synchronously under the change of external disturbance,which provides a theoretical reference for further restraining the coupling vibration of rolling mill.