Key Technology Research On The Hydrostatic Bearings And Hybrid Bearings Of Spindle System For High Precision Grinder

The efficient precision NC grinding machine is mainly used in the precision machining for aviation,military, optical elements, gem, mould and various kinds of hardware industry; it especially has a broad application prospect in the optical elements industry. The hybrid bearing is the core functional part of efficient precision numerical-controlling grinding machine. Compared with other bearings like roller bearing and hydrostatic bearing, it has smaller friction and loss, higher rotation accuracy and oil film stiffness, stronger bearing capacity, better damping shock absorption performance and longer life. In addition, in its static pressure cavity the hydrostatic bearing uses a throttle as the regulating element, which plays an important role in its performance. This paper mainly includes the following parts:Firstly, the theory of the sliding bearing and basic equations of design calculation are introduced. The basic equations are flow continuity equation, energy equation, momentum equation and Reynolds equation. Then the calculation equation of the sliding bearing performance is given, including the equations of temperature rise of the bearing oil film and the bearing capacity.Secondly, the oil film flow field numerical model of the hybrid bearing is set up on the basis of CFD and introduces division of bearing oil film and set of boundary conditions. According to the calculation method of CFD and 4+2 mathematical model of hybrid bearing are established, the influence that the working parameters and structure parameters of bearing have on its flow field characteristics is studied and the law of how various parameters influence bearing capacity of bearing oil film, oil film stiffness and temperature and flux is summarized. Then a set of comparatively optimal 4+2 mathematical model of hybrid bearing working parameters and structure parameters of hybrid bearing based on the calculation results are concluded. It provides important value for the design of 4+2 mathematical model of hybrid bearing.Thirdly, a design of new hydrostatic bearing throttling set—spiral pressure reducing valve is put forward in this paper. The throttling mechanism of spiral pressure reducing valve in the hydrostatic bearing and the working principle of spiral electric control valve are expounded. Also, a mathematical model based on the carrying capacity, oil film stiffness and flux of the hydrostatic bearing which employs the spiral pressure reducing valve is established. A numerical simulation through the MATLAB software programming is made. Then on this basis, the effect law that the Spindle eccentricity, bearing axial sealing edge length and the spiral pipe length of pressure reducing valve have on the bearing characteristics of the hydrostatic bearing is analyzed. Thus an important reference value for the design and structure parameter optimization of hydrostatic bearing which uses the spiral pressure reducing valve is provided.Lastly, the paper theoretically calculates the hydrostatic spindle static rigidity of the efficient precision grinding machine. At the same time the hydrostatic spindle static rigidity is tested and the results of theoretical calculation and experimental results is analyzed comparatively.Therefore, the correctness of the theoretical calculation is verified.