Research On The Vertical Vibration Of Cold Strip Mill

Various forms of vertical vibration often happen during rolling, which seriously affect the steel quality and even cause accidents. Therefore, eliminating vibration of cold strip mill is the premise to realize high precision rolling. Based on the small cold rolling mill in the laboratory, we research on the vibration problems from three aspects to explore the technical parameters and structure parameters on the influence law of vertical vibration. So we can forecast the self-excited vibration more accurately and formulate rolling schedule more reasonably to avoid vibration. The main research work of this text as the following:First, a six degree freedom dynamic model of the rolling mill with vertical vibration system under damping condition has been built, and the equivalent mass and stiffness of model are calculated.Second, model analysis is carried out by matlab soft-ware, then the natural frequencies and models are obtained.Third, we explore influences of equivalent mass and stiffness on each natural frequency. We also explore the influence laws between structural parameters and each natural frequency. This work can give valid reference for the structural design of cold strip mill and further study of rolling stability conditions.Then,Considering the circumstance of forced vibration, the responses of vibration system under special working situations are discussed to research the dynamic properties. We finish drawing by matlab software. It is indicated that damping can reduce vibration intensity and the self-excited vibration is concerned with the natural frequencies.Finally, based on the theoretical analysis of the self-excited vibration reason in rolling mill, Calculating model of the critical rolling speed is established to explore influence of technological parameters and structure parameters on the critical rolling speed. Then the influence of working roll radius, damping, export thickness, entrance thickness, front tension stress, back tension stress, and distance between mill housing on critical rolling speed are obtained.These conclusions are all important for design of cold strip mill, formulation of rolling schedule and further study of self-excited vibration. Its also a great help to improving product quality and increasing production of steel strip. So, the research has important theoretical and practical significance.