| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 98 === Aerostatic bearings are widely applied in high-precision guiding systems, high-speed spindles and semiconductor correlated systems because of their low friction, self-cooling and no pollution characteristics. Due to the air compressibility, aerostatic bearings always possess inherent weaknesses such as lower bearing capacity and strict operational bounds. In this Thesis, we have proposed a novel design concept of capped aerostatic bearing, which combines the radial and the axial bearings inside a cap-shaped air film to enhance its bearing capacity. Two opposite working cap-shaped aerostatic bearings are integrated with an air-turbine rotor to set up a high-speed rotor system. By using theoretical analyses and computational fluid dynamics simulation, the influences of the design parameters of the cap-shaped aerostatic bearing on its bearing capacity and stiffness are analyzed. And through the Taguchi method, an optimal combination of design parameters is built up. Through diverse experimental tests on the integrated system, it can be verified that the design concept of the cap-shaped bearing can increase the radial and axial bearing capacity and stiffness; moreover, low-friction bearing can also facilitate and enhance the rotation of the air-turbine rotor. According to the testing results, the cap-shaped aerostatic bearing has the radial bearing capacity of 27.5 N and the axial bearing capacity of 62 N, and the air-turbine rotor also reaches the maximum rotational speed of 52 krpm.
|
|---|
