Study Of Spatial Vibration Characteristic Of Plate Rolling Mills

The resonant and chatter vibrations of4/6-h cold and hot rolling mills worldwidehave not been solved yet so far. Technical parameters about natural vibrationcharacteristics of rolling mills have not been given in design theory of the mill. Thestability of the roll system is not concerned in traditional research about mill vibrations,namely that the mechanical model of the mill is all built on stable rolling mill. Meanwhile,the spatial vibration behaviors involving vertical, horizontal, axial, torsional, cross andswinging vibration are analyzed as coupled vibration behaviors of single vibration. Tocontrol or even eliminate mill vibration, the new research about mill vibration is from thethought of stability of roll system and spatial behaviors of the mill.First, the spatial transfer matrix method is selected for vibration analysis of the mill.The multilayer and multi-body spatial transfer matrix method is built according to thestructural characteristics of more rolls. The two2-h rolling mills with different stability ofroll system are taken as examples and the spatial vibration analysis is conducted usingmentioned method. Meanwhile, the field test experiment is done as well to validatenumerical results. Finally, the spatial vibration transfer matrix method is built.Secondly, considering the effect of damping, the spatial vibration models of the1580hot plate4-h mill, including mechanical model and FEM model, are built. For two rollingmills with different stability of roll system, the numerical analysis and simulation aboutspatial vibration characteristics are conducted using transfer matrix method and finiteelement method. The comparison between vibration characteristics of two mills is doneand the effect of clearance on natural frequency and mode shape is demonstrated. Thefield test experiment is done to validate numerical calculation and simulation. Meanwhile,the self-excited vibration mechanism for the1580mill is proposed form the recognition ofbeat and resonant vibration phenomenon, i.e., self-excited vibration caused by negativedamping occurring in forward and backward slip zone of roll gap is generated due tounequal work that the strip exerts on the roll under heavy reduction rate. Vibration controlmethods are proposed from technical parameter controlling and modification of mill structure.Finally, the spatial vibration models of two650cold plate4-h mills with differentstability of roll system are built and the numerical analysis about spatial vibrationcharacteristics is conducted using transfer matrix method. The field test experiment isdone simultaneously to validate numerical results and discuss excitation source whichcauses big inclined wave on strip surface, and the corresponding modified vibrationcontrol methods are proposed.In conclusion, the spatial vibration and its numerical analytical method, self-excitedvibration mechanism caused by negative damping occurring in forward and backward slipzone, and presentation of vibration control method have a great theoretical andengineering application value for the theoretical research of mill vibration and practicalproduction vibration controlling.