高速氣體靜壓軸承－主軸系統動態特性分析與實驗研究

Rot Dynamic Analysis and Experimental Study of the Aerostatic Bearing-Spindle System

陳明飛(Ming-Fei Chen) ； 李俊賢(Jun-Xian Li) ； 黃韋倫(Wei-Lun Huang) ； 蔡秉璁(Ping-Tsung Tsai)

《中華民國振動與噪音工程學會論文集》 2008 (2008/05) Pp. 265-273

摘要

高速氣體靜壓主軸已廣泛運用在精密機械設備上，例如晶圓切割機、PCB鑽孔機等。隨著主軸工作轉速的不斷提高，已經面臨超過二階或更高階臨界轉速的問題。由於主軸的結構型式、材料、軸承剛性等參數都會影響臨界轉速。因此，主軸系統的相關參數與臨界轉速的設計就變得非常重要。本文以PCB鑽孔機的氣體靜壓主軸做為研究載具。首先，利用有限差分法求解描述氣體軸承之氣膜壓力分佈的二維可壓縮雷諾方程式，並考慮主軸轉速對軸承性能的影響，得到軸承的承載力與剛性係數。其次，建立氣體靜壓軸承－主軸系統動力學模型，以有限元素法求解其自然頻率、振型。接著將計算結果與模態測試等實驗結果比對，確認有限元素程式與軸承剛性係數的正確性。然後再加上陀螺效應，計算繪出坎貝爾圖，得到軸承－主軸系統的臨界轉速。最後，進行氣體靜壓軸承－主軸系統的階次分析實驗，量測出臨界轉速並與計算所得臨界轉速比對。本文藉由理論分析與實驗量測方法，求取主軸系統之動態特性，可做為PCB鑽孔機主軸或精密磨床等高速主軸的開發參考。

關鍵字

氣體靜壓軸承－主軸系統 ； 有限差分法 ； 雷諾方程式 ； 軸承剛性 ； 有限元素法 ； 臨界轉速

並列摘要

High-speed aerostatic spindles have been widely used on precision machinery, such as Grinder machines and PCB drilling machines. With the ceaseless increase in spindle rotation speeds, there have emerged the second order or higher-order critical speed problems. Because the parameters such as the structural shape, material, and bearing stiffness all influence the critical speed, the related spindle parameters and the critical speed design become very important. The present paper employs the aerostatic spindle of the PCB drilling machine as the research vehicle. First of all, it uses the finite difference method to solve the two-dimension compressible Reynolds equation which describes the pressure distribution of the aerostatic bearing, and considers the influence of the spindle speed on bearing performance, hereby gets the bearing capacity and stiffness coefficients. Secondly, it establishes the dynamic model of the aerostatic bearing-spindle system, using the finite element method to obtain the natural frequency and mode shape. Then it compares the calculated results with the experimental results from the modal testing and others, to verify the correctness of the finite element method and the bearing stiffness coefficients. Next, it takes gyroscopic effects into account to calculate and draw the Campbell diagram, and obtains the critical speed of the bearing-spindle system. Finally, it conducts the order analysis experiment on the aerostatic bearing-spindle system, measures the critical speed and compares it with the calculated critical speed. The present paper, through theoretical analyses and experimental measurements, aims to obtain the dynamic characteristics of the bearing-spindle system, which can be used as a reference for developing the spindle of PCB drilling machines or the high-speed spindle of precision grinding machines, etc.

並列關鍵字

aerostatic bearing-spindle system ； finite difference method ； Reynolds equation ； bearing stiffness ； finite element method ； critical speed