渦輪分子真空泵浦轉子軸承系統振動與模態特性分析研究

Vibration Characteristics Analysis and Modal Testing of a Turbo Molecular Pump Rotor-Bearing System

黃裕盟(Yu-Meng Huang)

指導教授 ： 蔣小偉

國立清華大學/工學院/動力機械工程學系/碩士(2010年)

摘要

本論文為針對垂直立式之渦輪分子真空泵浦轉子軸承系統進行動態特性之研究，研究方法分為數值分析及實驗量測兩部分。數值分析為利用有限元素法分析軟體ANSYS和轉子動力學分析軟體DyRoBeS建立轉子系統二維及三維模型，利用不同邊界條件下之模態測試結果來修正及驗證轉子軸承系統之有限元素模型，再進一步計算轉子系統之坎貝圖(Campbell Diagram)以了解轉子軸承系統之動態特性，並與實驗結果作比對以確認分析之正確性。最終完成轉子臨界轉速相對於軸承剛性的關係圖，以提供廠商在分子泵浦轉子設計及軸承匹配上之參考依據。
實驗分為靜態敲擊測試和動態量測兩部分，靜態敲擊測試可以得到轉子軸承系統之自然頻率，動態量測可以得到系統之瀑布圖，由瀑布圖可以發現泵浦系統從0rpm上升至工作轉速52000rpm過程中會遇到之臨界轉速，以及確保泵浦系統工作轉速是否達到臨界轉速之10%以外的安全範圍。
最終以實驗量測與數值分析結果作為依據，建立一套本研究渦輪分子真空泵浦轉子軸承系統的分析模型，以提供未來泵浦振動原因分析及減振方案以提供廠商開發之參考及設計依據。

關鍵字

渦輪分子真空泵浦 ； 轉子軸承系統 ； 振動模態 ； 臨界轉速

並列摘要

This study is focused on the dynamic characteristics of a vertical turbo molecular pump rotor-bearing system. The research methods can be divided into two parts, which are numerical analysis and experimental measurements. In numerical analysis, we use the finite element analysis software ANSYS and DyRoBeS to construct a two-dimensional and three-dimensional model of the rotor-bearing system. In the analysis process, by constantly changing the pump system assembly methods we can correct and verify the rotor-bearing system finite element model under different boundary conditions. Next, we calculate the Campbell diagram to understand the dynamic characteristics of the rotor-bearing system, and to compare with the experimental results to verify the model. Finally, we found the relationship between the rotor critical speed and the bearing stiffness in order to provide the design of the molecular pump rotor and the bearing system.
Experimental measurements were divided into two parts: static percussion tests and dynamic measurements. Static test can provide the natural frequencies of the rotor-bearing system. Waterfall diagram of the dynamic test can measure the pump system’s critical speed from zero speed up to the working speed crossing, and to insure that the pump working speed is far from the critical speed of 10% in the safe range.
In summary, the results of the experimental measurements and numerical analysis can be the basis for the design of the turbo molecular vacuum pump rotor-bearing system analysis techniques in order to identify and prevent pump vibrations.

並列關鍵字

Turbo Molecular Pump ； Rotor-Bearing System ； Mode Shape ； Critical Speed

參考文獻

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5. Nelson, H. D., “A Finite Rotating Shaft Element Using Timoshenko Beam Theory,” ASME Journal of Mechanical Design, Vol. 102, pp. 793-803, Oct. 1980.

6. Rouch, K. E., and Kao, J. S., “Dynamic Reduction in Rotor Dynamics by the Finite Element Method,” ASME Journal of Mechanical Design,Vol.102, pp. 360-368, April 1980.