Vertical Vibration Characteristics Analysis Of Rolling Mill With Dynamic Rolling Force Considering Friction State Of Roll Gap

This paper take one 2800 cold rolling mill as the research object.On the basis of rolling theory,lubrication and friction theory,mechanic vibration theory,Four-DOF nonlinear mathematical model of vertical vibration of rolling mill with dynamic rolling force considering friction state of roll gap has been presented.The mathematical model is also simulated in MATLAB/SIMULINK,Further analysis research to vertical vibration characteristics of rolling mill is carried on through the field testing of 2800 rolling mill,and the validity and reliability of the simulation results and the model established in this thesis was verified.The main contents of this paper are as follows:(1).The impacts of rolling speed,rolling tension,rolling reduction and deformation zone length on vertical vibration of rolling mill are studied theoretically,especially the important relation between interface friction and rolling mill vibration,The effects of friction on vibration was expounded.In combination with field test,the relationships between rolling reduction,rolling speed,emulsion concentration and friction coefficient of roll gap are analyzed.(2).Under the vertical vibration of rolling mill,the dynamic rolling force model considering friction state of roll gap has been established,and the simulation analysis on the model was carried on.In order to establish a more precise rolling force model,the elastic deformation of rollers and rolled piece was taken into account in the model.On the basis of BRAND-FORD-HILL rolling force model,established the dynamic rolling force model considering the vertical vibration of rolling mill.The coupling relationship between the radius of roll flattening and rolling force has been decoupled,the functional relation between rolling force and rolls vibrating displacements was found by rational resolution.In order to facilitate further research on the vertical vibration of rolling mill under the dynamic rolling force,the functional relation between rolling force variation and rolls vibrating displacements has been obtained by Tailor expansion of the rolling force function.The dynamic rolling force model and the impacts of friction of roll gap on rolling force was also simulated in MATLAB.(3).Four-DOF nonlinear mathematical model of vertical vibration of rolling mill with dynamic rolling force considering friction state of roll gap has been presented.The mathematical model is also simulated in MATLAB/SIMULINK.On the basis of the dynamic rolling force model,Four-DOF nonlinear mathematical model of vertical vibration of rolling mill considering friction state of roll gap has been established;The natural vibration characteristics of the system under undamped free vibration was analyzed,and the theory of multiple scales method was used to solve nonlinear differential equations;the influence of many factors such as friction on vertical vibration of rolling mill is analyzed and simulated,and the dynamic simulation model of vertical vibration of rolling mill was established in MATLAB/SIMULINK,the dynamic responses of the top work roll and the top backup roll vibrating displacements are analyzed under different friction coefficient.(4).Further analysis research to vertical vibration characteristics of rolling mill is carried on through the field testing of 2800 rolling mill,and the validity and reliability of the simulation results and the model established in this thesis was verified.A series of conclusions has been obtained by testing.For example,the dominant vibration is self-excited vibration in the vertical mill system;the key vibration source is confirmed in the roll gap;results show that if rolling speed was improved,the stability of rolling mill will get worse;if the surface roughness of work roll was appropriately increased,the vibration amplitude will also reduce,etc.