Research On The Synthesis Rotation Error Modeling And Dynamic Charcteristic Of The Rotor System Supported By Roling-Sliding Bearing

Recently,the research on active hydrostatic journal bearing is always active,but most is to suppress the vibration of the spindle at the front bearing and improve the stiffness.In machine tool processing,the amplitude of the rotor at the front end of the spindle extension where the cutting tool are fixed will affect the machining accuracy more.If only the vibration of the rotor at the front bearing is reduced,the machining accuracy may not be improved.The strategy that comprehensively using the rotary error movement at the front and rear bearing to improve the rotary accuracy may be more effective,Therefore,it is necessary to study and analyze the motion and control of the whole rotor system.In this paper,a rotor system in which the front bearing is a hydrostatic journal bearing with control-cavities and the rear bearing is a rolling bearing is studied.As the target that rotary accuracy at the front end of the spindle extension where the cutting tool are fixed,the comprehensive rotary error modeling was established.To improve the controllability and stability of the active hydrostatic spindle,a smaller control cavitiy is nested in each oil cavity of the traditional hydrostatic bearing with four cavities,and the active single-side membrane restrictor is used to supply oil to it.The twice throttling inside the bearing is fully utilized to realize the coexistence of high stiffness,low damping and better controllability.Firstly,Based on the Reynolds lubrication equation and the flow continuity equation,the dynamic axis orbit model of the hydrostatic spindle was established by the finite difference method and the Euler iteration method.The control sensitivity,an important parameter of control characteristic,is proposed.The dynamic characteristics and control characteristics of the bearing under different bearing structures and oil supply pressures are theoretically studied by small disturbance method.The optimal range of bearing structural parameters is obtained.Then,aiming at the rotary error of the rotor at the front end of the spindle extension,based on the assumption of rigid spindle,according to the rotary error motion of the front and rear bearing rotors,the comprehensive rotary error model of the Rotor System supproted by roling-sliding Bearing is established by the spatial linear equation,and the influence of the amplitude and phase of the front and rear bearing rotor motion on the rotary error of the front end is analyzed;In order to match the amplitude and phase of the front and rear rotor motion and improve the front rotation accuracy,the dynamic response of the rotor system under different voltage signal inputs was calculated,including the rotating error motion,the change of the oil cavities pressure and the throttle clearance.According to the calculation,the active control is applied to the rotor motion at the front hydrostatic bearing by voltage input,and the calculation results show that the rotation error of the front end of the spindle is greatly reduced.Finally,through NI synchronous equipment and eddy current sensor,the rotor rotary error motion of each position of the rotor system supproted by roling-sliding bearing is measured,and the axis motion of the rotor system under different external excitation is studied.The experimental data are filtered and analyzed with MATLAB software,and the correctness of the comprehensive rotation error model of the rotor system supported by rolling-slidin bearring is verified.