精密微型雙動力超高速氣渦輪之設計與開發

Design and Development of Precision Miniature Twin-bladed Ultra High-speed Air Turbine

王識鈞(Shih-Chun Wang)

指導教授 ： 黃光裕

國立臺灣大學/工學院/機械工程學研究所/博士(2012年)

https://doi.org/10.6342/NTU.2012.01870

摘要

本論文研發探討雙動力微型氣渦輪在超高轉速域的性能特徵。為了改善超精密與微加工技術的加工效率，高速主軸通常不可或缺地被廣泛應用於PCB鑽孔機、微加工機與牙科高速手機。因此，在超高速的應用裡，空氣驅動渦輪經過驗證比電動機更加適用，此外，渦輪葉扇與軸承是影響高速主軸的工作效率與品質的關鍵零組件。
　　通過詳細地研究與各種氣渦輪葉扇的性能分析，找出與效率和品質有影響的相關參數。並且根據最佳化設計的結果，本論文開發出一種新型渦輪葉扇，是由兩組平行偏移的渦輪葉扇所組成的雙動力氣渦輪葉扇（Twin-bladed impeller, 簡稱TB impeller），此設計能夠有效地將高壓氣體轉換成平順的旋轉動能。因此，在穩定的動力輸出和高平衡精度下能夠輕易地達到減少振動，噪音和磨損。
　　通過運用有限元素法，對雙動力氣渦輪葉扇進行轉速、扭力、振動與噪音進行參數與性能分析，並了解設計參數和運行參數的影響。而進氣口直徑、渦輪葉扇形狀及幾何參數是主要的設計參數；入口壓力和流量是主要的運行參數。透過氣渦輪葉扇，高壓氣體所轉換的能量將會以葉扇間流場與壓力分佈以及紊流能量損失方式所呈現的運轉動能。
　　此渦輪葉扇的設計可以結合生產技術並適用於一般自動生產過程，此外，通過特別佈局的分散氣流，可以使運轉的偏擺度最小化，並有效地實現沒有任何複雜的和昂貴的加工製作程序，因此可以大幅地抑制氣流噪音與提高軸承的運轉壽命。根據實驗驗證，在相同的供氣壓力下，雙動力氣渦輪葉扇在最高轉速、動能效率與扭力值分別高於10%、10%和15%的傳統葉扇。氣流噪音可以改善17%。本論文所開發出的雙動力氣渦輪葉扇可以有效地實現高運轉轉速、高扭力、低振動與低噪音的特性。由於在高轉速優越的高效率特點，也拓展了在高速加工領域應用的可能性。

關鍵字

高速 ； 筒匣 ； 微型主軸 ； 渦淪葉扇 ； 雙動力葉扇 ； 氣渦淪

並列摘要

Research and development of this thesis is to investigate the performance and characteristics of precision miniature twin-bladed air turbines in an ultra-high-speed region. In order to improve the machining efficiency of ultra-precision and micro fabrication technology, a high speed spindle is essential for the miniature tools which widely applied in systems such as PCB drilling machines, micro fabrication machines, and dental handpieces, etc. To realize the performance in high speed region, the air driven turbine is verified to be more feasible than an electromagnetic actuator. Furthermore, the operational efficiency and quality of the high speed spindle are significantly influenced by the turbine impeller and its bearings, respectively.
Through detailed configuration studies and performance analyses on diverse miniature turbine impellers, the efficiency-influential and quality-influential parameters have been derived. And based on optimization results, a novel type of twin-bladed impeller (TB-impeller) on air turbine, which consists of two parallel impellers with an angular offset, is developed. The offset twin impellers can efficiently and smoothly transform pneumatic energy into rotational energy. Therefore, steady driving force and less dynamic unbalance are easily achieved for reducing operational disturbances such as vibration, noise, and wear.
By applying a finite element analytical method, the operational performance and quality of the new developed twin bladed impeller such as rotational speed, torque, vibration, and noise were analyzed for comprehending influences of the design parameters and the operational parameters. While the inlet diameter, the blade shape and its geometric parameters are the dominant design parameters; the inlet pressure ,mass flow rate, and the outlet pressure are the main operational parameters. Through the turbine impellers, the pneumatic energy can be transformed into operational energy in form of the flow field and the pressure distribution as well as the energy loss in form of turbulence.
Also by integrating knowledge of production technology, a neat design of the turbine impellers suitable for automatic manufacturing processes is developed. And furthermore, through an elaborate layout of the flow guiding, a minimum rotational run-out can be effectively achieved without any complicate and costly machining processes. Consequently, it can significantly depress the stream noise and raise the operation lifetime of bearings. According to our experimental verification at the same inlet pressure, the free running speed, power efficiency, and torque of novel TB-impeller are 10 %, 10 %, and 15 % higher than traditional counterparts, respectively. And the stream noise can be reduced by 17 %. The developed miniature spindle with novel TB-impeller can efficiently realize high speed rotation with high free running speed, high torque, less vibration, and less noise. By its superior features, the developed twin-bladed impeller also broadens the application possibilities in high speed machining fields with high efficiency and fewer expenses.

並列關鍵字

High-speed ； Cartridge ； Miniature spindle ； Turbine impeller ； Twin-blade impeller ； Air turbine

參考文獻

[18] 柯彥旭，“牙醫手持鑽機性能檢測平台之設計與開發”，台灣大學碩士論文, 2007

[1] Dyson, J.E. and Darvell, B.W., 1993,“The development of the dental high speed air turbine handpiece---part 1. “, Aust Dent J, Vol. 38(1), pp. 49-58.

[2] Dyson, J.E. and Darvell, B.W., 1993,“The development of the dental high speed air turbine handpiece---part 1”, Aust Dent J, Vol. 38(2), pp. 131-144.

[3] Dyson, J.E. and Darvell, B. W., 1993,“Aspects of the design of modern dental air turbine handpiece.”, Aust Dent J, Vol.38(6), pp.131-143.

[5] Reynolds, O., 1886, “On the Theory of Lubrication and Its Application to Mr. Beauchamp Tower’s Experiments, Including an Experimental Determination of the Viscosity of Olive Oil”, Philosophical Trans. R. Soc. London, Vol. 177, pp.157-234.