2008 Volume 2008 Issue 7-2 Pages 515-520
Plane externally pressurized thrust gas bearings for high speed spindles are considered. The behavior of the rotor-bearing system is studied both numerically and experimentally. A numerical model based on Reynolds equation is used to simulate the static and dynamic behavior of the system. Flow rate equation through inlet orifices is coupled with Reynolds equation. The flow rate is calculated by considering an experimentally determined discharge coefficient, that is function of holes diameter and local clearance. To increase stiffness are studied thrust bearings presenting a circumferential groove situated at the same radius of the supply holes. The influence of the groove on stiffness and stability is discussed. Simulations are made to evaluate the influence of supply holes diameter and of axial clearance on bearing characteristics.
Two thrust bearings are studied experimentally. They are composed by a symmetric couple of disks facing the rotor fl ange. The internal and external diameters of the disks are 52mm and 110mm and equipped with 8 holes of diameter 0.35mm on a circumference of diameter 65mm. A thrust bearing present a rectangular section circumferential groove, located at the same radius of the orifices, of width 0.7mm and thickness 10μm.
Comparisons between simulated and experimental stiffness are presented.
