適用於微型高速氣渦輪筒匣之像散式動平衡檢測系統之設計開發與研究

Research and Development of Dynamic Balancing System with Astigmatic Pick-up Head for Miniature High-speed Turbine Cartridge

楊思慧(Si-Hui Yang)

指導教授 ： 黃光裕

國立臺灣大學/工學院/機械工程學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.00425

摘要

本論文的目的開發微型高轉速之牙醫手機氣渦輪筒匣之動平衡機，以求降低轉子動不平衡來提升其在高速250~350 krpm運轉下的動平衡品質。氣渦輪筒匣雖然經過精密的製作與組裝，高速運轉還是透過作用在微小轉軸偏心的離心力引發動不平衡振動。動不平衡振動進而又會造成運轉偏擺、軸承磨損和噪音。為了量測動不平衡振動，兩組長度可調的彈簧鋼片平行導引被採用來支撐轉動筒匣，讓不平衡作用力得以轉換成彈簧鋼片的變形。長度可調功能使彈簧鋼片的自然頻率更接近被測轉子的轉速，使不平衡振動得以更有效激發彈簧鋼片的變形。彈簧鋼片的變形則透過像散式讀取頭量測，能感測非常小的高頻變形。轉子動不平衡的角度位置則以霍爾元件量測。透過影響係數平衡法，彈簧鋼片的變形量與對應的不平衡量角度位置則可以推算得轉子不平衡量。為了要去除微小不平衡量，固態脈衝雷射被用於在渦輪葉扇上製造精密的除料。20W的固態雷射以60 kHz的脈衝頻率，量測得除料率為1秒鐘可以去除約14ug。
動平衡實驗測試結果展示，動不平衡振動為14.6 nm至39.1 nm，相當於渦輪葉扇上38 μg至23 μg的動不平衡質量。經過一次雷射除料的動平衡處理後，動平衡量改善15.7%和33.9%，達到ISO G2.5的等級。

關鍵字

動平衡 ； 牙醫手機 ； 氣渦輪筒匣 ； 像散式讀取頭 ； 雷射除料

並列摘要

The aim of this thesis is to develop a dynamic balancing system for the miniature high-speed turbine cartridge. The capability of this system is to decrease dynamic unbalance of the rotor of turbine cartridge, and to improve the dynamic balance quality for the high-speed operation range from 250~350 krpm. Although the turbine cartridge is precisely manufactured and assembled, the dynamic unbalanced vibration still induced because of high-speed operation. The dynamic unbalanced vibration would cause rotational run out, bearing wear, and noise. For measuring the dynamic unbalanced vibration, two pairs of length-adjustable parallel spring guides are used to support the rotating cartridge in order to transform the unbalance forces into the spring deformations. The unbalance vibrations can effectively stimulate the spring deformations through the length-adjustable spring to modulate their natural frequencies close to the rotational speed of turbine cartridge. The spring deformations are measured by two astigmatic pickup heads, which have been verified to be able to detect very tiny high-frequent deformation without any contact loading. And the angular positions of the rotor unbalances are simultaneously detected by two perpendicular arranged hall sensors. By using the influence coefficient method, the rotor unbalances can be derived from the detected spring deformations and their corresponding angular position. For removing tiny unbalances, the pulsed solid-state laser is applied to create precision ablation mass on the turbine vane. The measured ablation rate is about 14 ug for 1-sec operation time by using the 20 W solid-state laser with the pulse frequency of 60 kHz.
　　The experimental balancing testing shows that the astigmatic pickup heads can detect very tiny unbalanced vibration in a range from 14.6 nm to 39.1 nm, which corresponds to the unbalance mass from 38 μg to 23 μg on the turbine vane. Through the dynamic balancing operation, the rotating quality of high-speed cartridge can be 15.7 % ~ 33.9% improved. The developed dynamic balancing system is experimentally verified that its balance quality can achieve the ISO G2.5-level.

並列關鍵字

Dynamic balancing ； Dental headpiece ； Turbine cartridge ； Astigmatic pick-up head ； Laser ablation

參考文獻

[3] 查宇杰，微小高速氣渦輪轉軸動平衡檢測機之設計開發與特性研究，國立台灣大學機械工程學研究所碩士，2008。

[13] 王識鈞，精密微型雙動力超高速氣渦輪之設計與開發，國立台灣大學機械工程學研究所博士，2012。

[4] 唐子健，微型高速氣渦輪筒匣性能檢測及動平衡之設計開發與研究探討，國立台灣大學機械工程學研究所碩士，2011。

[11] Hwu, E. T., Huang, K.Y., Hung, S.K., and Hwang, I.S., “Measurement of Cantilever Displacement Using a Compact Disk/Digital Versatile Disk Pickup Head”, Japanese Journal of Applied Physics, Vol. 45, No. 3B, pp.2368-2371, 2006.

[12] Hwu, E. T., Illers, H., Jusko, L., and Danzebrink, H.U.,“A hybrid scanning probe microscope (SPM) module based on a DVD optical head”, Meas. Sci. Technol, Vol.20,2009,084005.