Torsional Vibration Research Of Main Driving System Of Rolling Mill With Impact Of Clearances And Strip Vibration

Iron and steel industry has been puzzled by rolling mill vibration for many years, which brings serious effect and damage, and the vibration phenomenon is extremely complicated. Torsional vibration is an importent factor of affecting product quality, and is one of main forms of roling mill vibration. Because of designing, installation and wearing, the influence of clearances on torsional vibration can not be ignored. In addition, strip vibration of plate mill is inevitable during rolling, and the influence of strip on torsional vibration has been also little concerned. The paper mainly discusses torsion vibration of main driving system with impact of clearances, strip and strip vibration research. The main contents are as follows:By using lumped mass method, a 5-degree of freedom scattering torsional vibration model of main driving system is established. Based on measured data, the model parameters and external loading form are determined. According to the actual location of clearances, a nonlinear torsional vibration dynamic model with clearances is established.Based on the torsional vibration dynamic model with clearances, the influence of clearances on torsional vibration system under slippage and biting impact conditions are investigated, respectively. By using Runge-Kutta method, the numerical results of torsional vibration dynamic responses with impact of clearances are obtained under the two different conditions. The influence of different simplified forms of clearances on the system dynamic response and the shaft section torque amplification factor, and the influence of the different clearance of the size and location on torque amplification factor are analyzed.According to the movement mechanism of strip and rollers, the strip and rollers coupled nonlinear vibration mechanical model is established. The strip during tandem rolling process is equivalent to axially moving Euler beam, and the rollers are equivalent to the inertial component on the fixed axis rotation, namely inertial boundary. Based on Hamilton’s principle, nonlinear vibration equations of axially moving Euler beam with inertial boundary condition are derived. Kantorovich averaging method is employed to discretize the motion equations and the inertial boundary, and the solutions are obtained by using modified iteration method. Depending on numerical calculation, the amplitude-frequency responses of Euler beam are determined. And the influences of axial velocity, tension, length between stands, and rotational inertia of roller on the vibration performance under inertial boundary condition are discussed.Coupled torsional vibration model of the drive systems and the strip between two stands is established. And the natural frequencies and main vibration modes are got by modal analysis, and then the harmonic response analysis is analyzed. By comparing of the two methods, the inherent relationship between strip and torsional vibration of driving system is further studied.In conclusion, an engineering control and optimization design of torsional vibration rely on deep understanding of complex motion characteristics of the system. The actual clearance position, clearance size and the effect of strip should be considered to establish an accurate model, and the simulation analysis results of drive system based on the model will accord with the practical engineering. Therefore, it has important reference value and theoretical foundation for design analysis and engineering analysis torsional vibration of rolling mill system.