Static-dynamic Characteristics And The Control Method Research Of Ultra-precision Gas-magnetic Bearing Principal Axis System

Gas bearing and magnetic suspension bearing possess the highest rotary precision at present which has been widely used in the military, aerospace, computer and other fields. Aerostatic bearing has the advantages of minimal friction without leakage. However, it is not easy to control and process. Magnetic bearing has the advantages of no wear and good controllability. This paper first introduced the general situation of gas bearings and magnetic bearings, and introduced the classification and features of two kinds of bearings particularly.The respective advantages of aerostatic bearing and magnetic bearings can make up for each other’s shortcomings, so the combined use of aerostatic bearing and magnetic suspension bearing can improve the rotation accuracy of shafting. This paper designed a kind of spindle system of ultra-precision gas magnetic bearing, and designed the modality and parameters of the bearings of this system. The system consists of two aerostatic bearing and two active magnetic bearings as radial bearing and a thrust magnetic bearing as the axial bearing.This paper deduced the dynamic model of five degrees of freedom system and analyzed gyroscopic coupling effect when the spindle rotating with high speed by the researching the structure of the ultra-precision gas magnetic bearing spindle system. According to deriving the Reynolds equation and the designed parameters of the bearing, we studied the static characteristics of the aerostatic bearing and active magnetic bearings, and also analyzed the relationship between stiffness, eccentricity and bearing capacity of the aerostatic bearing under static conditions and the electromagnetic force change of active magnetic bearing by using Fern Analysis. We studied the dynamic characteristic of the front-end aerostatic bearing and analyzed the changing rule of the dynamic damping and stiffness by the method of combining rotating coordinate system and static grid.The calculation and analysis provides theoretical basis to improve the structure of gas magnetic bearing and improve its performance.We carried on the simulation analysis of the spindle control system by using MATLAB language, and designed PID controller of the spindle. We also carried on the simulation analysis of PID by using Simulink to, and the results of simulation analysis proved the feasibility and stability of using PID to control the spindle system.