新型主動式補償液靜壓軸承之靜動態特性分析

Characterization of the Static and Dynamic Performance of a Novel Pressure-sense-compensating Hydrostatic Bearing

李威志(Wei-Chih Lee)

指導教授 ： 宋震國

國立清華大學/工學院/動力機械工程學系/碩士(2012年)

摘要

本文設計、製作且測試一款新型主動式補償節流器/軸承模組，並將其應用於液靜壓線性平台系統。創新之處在於將主動式補償節流器與軸承塊(Pad)整合成一模組；其中，節流器係以一彈性元件的變形來感測油腔壓力的變化並作自動壓力補償，具有一體化的特色，故除了可以大幅提升軸承承載力、剛性及動態反應速度外，並有零件少、加工及組裝容易、成本低等優點。
在理論方面，首先建立毛細管節流液靜壓軸承與新型主動式補償液靜壓軸承的理論，推導出裝有不同節流器的單向墊與對向墊液靜壓軸承之承載力與剛性公式。接著，針對軸承系統具多個油腔的實際應用狀況，推導公式並進行數值模擬，探討具不同節流器之液靜壓軸承系統中，各油腔剛性與系統剛性之關係。結果證明系統剛性具各油腔剛性向量相加的性質，並以此理論建立新型主動式補償液靜壓軸承系統剛性設計之方法。
此外，本文亦針對液靜壓對向墊軸承系統，進行動態理論的推導，並進一步建立毛細管節流器與液靜壓對向墊軸承整合系統的動態理論。在實驗方面，本文針對承載力與剛性需求，同時設計製作毛細管節流器、創新型主動式補償節流器與液靜壓線性運動平台系統，以實驗證明理論推導與數值模擬的正確性。本文也透過設計液靜壓對向墊軸承的過程，探討設計參數與性能之關係。實驗結果發現，新型主動式補償液靜壓對向墊軸承會有節流器失效的現象，本文藉由量測對向墊軸承油腔壓力的暫態變化發現問題之所在，進而提出設計補償元件尺寸、增加補償元件阻尼比與剛性之改善方法。

關鍵字

液靜壓軸承 ； 自感測補償式節流器 ； 承載能力 ； 剛性 ； 阻尼 ； 動態特性

並列摘要

This thesis designed, fabricated, and tested a novel pressure self-sensing compensating restrictor and applied it to a linear stage equipped with hydrostatic bearings. The restrictor features an elastic element that deforms in response of the pressure variation of the oil chamber. It results in the change of the flow resistance of the restrictor, therefore, achieves the function of self-sensing compensation. Since the design integrates the restrictor with the bearing pad, it possesses the advantages of high load capacity, stiffness, and damping, in addition to fewer components, easy manufacturing and assembly, less cost.
This study started with construction of theoretical models of the hydrostatic bearings installed with capillary and the novel self-regulating restrictors, respectively. The equations governing the load capacity and stiffness of these two-types of bearings with single pad and opposed pads, respectively, were derived. Then, the stiffness equation of the bearing system with multiple pads (oil chambers) was developed. The simulation results confirm the vector additive characteristic of the stiffness of multiple-pad bearing system.
This study also performed dynamic analyses of opposed-pad hydrostatic bearings installed with either a capillary or a self-sensing compensating restrictor. Furthermore, this study designed and fabricated a hydrostatic bearing linear stage with the two-types of restrictors based on the desired load capacity and stiffness. The load capacity and stiffness of the single-pad and opposed-pad bearing systems were verified, first, with the numerical simulation. Then, the vector additive characteristic of the stiffness of multiple-pad bearing system was, then, confirmed. Experimental results revealed that the proposed restrictor became invalid at the beginning of pressurization stage due to the unequal gaps of the two opposed pads. This involves with the transient behavior of the elastic element of the restrictor. A restrictor with gap self-adjusting and high damping characteristics may be required in the future.

並列關鍵字

Hydrostatic bearing ； Self-sensing compensating restrictor ； Bearing stiffness ； Damping ； Load capacity

參考文獻

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