Study On Torsional Vibration Of Cold Mill Main Drive System Based On Effects Of Lubrication And Friction

Torsional vibration of mill main drive system has always been a technical problem that perplexes productive practice. It needs more efforts to study the mechanism of torsional vibration of the system, then we can take more reasonable measures to restrain vibration and ensure that the equipment works safely and efficiently. Researching on main drive system of cold rolling mill,this dissertation emphasizes the factor of lubrication and friction and establishes dynamic equation of the torsional rotation system. By analytic calculation and numerical simulation, dynamic characteristics of the torsional rotation system are analyzed and the effect law of lubrication and friction is gotten. The research provides theoretical direction for making reasonable regulations of lubrication and friction to restrain vibration.Firstly, the model of friction damping force is established by applying theory of lubrication and friction. Then the dynamic equation of nonlinear torsional rotation system of rolling mill is established by the application of the lumped mass method and the generalized dissipative system Lagrange principle.Secondly, the dynamic response of above dynamic equation is solved by KBM method. The response solution of the system is gotten under free vibration or periodic excitation. The structure and morphology of the solution are analyzed. The study provides theoretical direction for further research on torsional vibration of the system.Thirdly, based on the dynamic equation of the system, the characteristics of static and dynamic bifurcation are analyzed. Based on the method of multiple scales, the amplitude-frequency characteristic equation under main resonance is solved. The transition set and topological structure of bifurcation curves are received through the application of singularity theory. Based on Hurwitz determinant, the Hopf bifurcation points of autonomous system are obtained. The Hopf bifurcation diagrams under different lubrication parameters are gotten.Finally, based on the dynamic equation of the system, the chaotic motion of the autonomous system is investigated. The equilibrium points of the autonomous system are validated using Cardano formula. On this basis, the existence of homoclinic orbits is given with the undetermined coefficient method. The chaotic motion of the system is researched by means of Silnikov criterion. Numerical simulation investigates the chaotic motion of the system and the route to chaos through period-doubling bifurcations. Numerical calculation can confirm the validity of the analytical results.