Design and Development of a Magnetostrictive Actuating Restrictor for Aerostatic Thrust Bearing and Performance Analyses
Date Issued
2006
Date
2006
Author(s)
Shiao, Yu-Chun
DOI
zh-TW
Abstract
With the progressing tendency of science and technology, the aerostatic bearings become more and more substantial because of their performance of low frictional operation and high rotating precision. In the aerostatic bearings, the restrictor is one of the key functions to improve the stiffness and the stability。The restrictor keeps the pressure of the air-film stable through the regulation of the flow rate, and the increasing stiffness brings about high rotating precision of the spindle. The aim of this thesis is to develop an active compensation restrictor for the aerostatic bearing system, and to study the influences of the design and operation parameters on the load-compensating capability. The slot-restricting principle is adopted for the active compensation restrictor device. Through the theoretical analyses and the finite-element analyses, the influence of slot gap on the supporting capacity is investigated. The regulating function of the restrictor gap is realized by the giant actuating effect of the magnetostrictive material Terfenol-D, which is applied to construct a magnetostrictive actuator together with permanent magnets, a coil and a magnetic circuit. For achieving an optimal actuating performance, the magnetic arrangement in the actuator is analyzed and verified by the finite element magnetic analyses. Through modifying the transferring function between restrictor device and magnetostrictive actuator, we develop two types of active compensation aerostatic bearing systems: the lever-driving system and the directly-driving system. In the lever-driving system, the magnetostrictive displacement is converted to the vertical displacement for regulating the restrictor gap by the lever. And in the directly-driving system, the magnetostrictive actuator integrated under the restrictor can regulate the restrictor gap directly. The system size, flow-restricting performance, dynamic compensation performance and compensating range of infinite-stiffness of the directly-driving system are superior to the lever-driving system. The directly-driving system is also experimentally proved to be able to effectively suppress the low frequency vibration.
Subjects
氣靜壓軸承
補償式節流裝置
磁變形材料
磁變形致動器
無限剛性
Aerostatic bearing
Compensation restrictor
Magnetostrictive material
Magnetostrictive actuator
Infinite stiffness
Type
thesis
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