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  • 學位論文

超聲波輔助磨削加工之伺服控制系統開發研製

Development of A Servo Control System for Ultrasonically Assisted Machining

指導教授 : 丁鏞

摘要


本論文之目標為開發超聲波輔助磨削加工之致動系統,致動系統包括使用一組壓電振動元件作為致動器配合放大機構設計以提供適當之位移量輸出,及另一組壓電振動元件利用壓電正電壓效應作為感測器,即可即時偵測輸出位移作為追蹤共振頻率之依據,如此可保持穩定輸出的功能。研究內容主要包括設計製作縱向壓電致動元件(d33)作為振動源、以及設計指數函數之位移放大輸出機構、系統振動模態及波傳遞分析。經實驗驗證目前開發完成之致動系統對d33壓電致動元件輸入為300V的電壓之共振頻率約39kHz達到振動位移輸出約2.29μm,且可即時有效地量測振動位移,使壓電縱向換能器與壓電感測器,產生縱向振動與感測電壓,利用壓電陶瓷材料同時作為致動器與感測器,壓電致動器提供振動位移,而壓電感測器可方便與壓電致動器結合,而即時量測輸出之振動位移,供回授控制設計之用。由於考慮刀具旋轉造成致動器繞線問題,設計傳動環裝置,將致動器輸出的高頻振動位移傳導致加工刀具之輸出端面,經測試傳動至刀具輸出之振動位移輸出約0.23μm。所開發之伺服控制系統裝置於研磨工機具以10000rpm運轉進行玻璃磨削加工實驗,利用電子力顯微鏡(AFM)觀測可獲得平均粗糙度(Rave)為0.9353nm,明顯優於未使用超聲波加工的平均粗糙度(Rave)為13.82nm,可確認所研製之超聲波輔助磨削加工系統產生的高頻振動可以有效改善磨削玻璃的平均粗糙度。

並列摘要


The objective is to design of the vibration displacement device for ultrasonic machining process. A set of piezoelectric vibrators is used as actuator associated with an amplification mechanism to generate desired vibration displacement. Another set of piezoelectric vibrators is used as sensor to measure the vibration displacement simultaneously, which provides the feedback control purposed of adjustment of the driving frequency immediately. The main research topics include the design of longitudinal vibrator made by d33, the amplification mechanism design with exponential shape, the system vibration analysis as well as wave transmission analysis.   In experiment, the developed piezoelectric actuator integrated with amplification mechanism is able to provide vibration displacement of 2.29 micrometers under the driving frequency of about 39kHz and can immediately and effectively measure the vibration displacement, So that the piezoelectric longitudinal transducer and the piezoelectric sensor can produce longitudinal vibration and induced velocity. We use the piezoelectric ceramic materials as the actuator and the sensor at the same time, where the actuator provides vibration displacement, and the sensor can be easily combined with the actuator which can instantly measure the output of the vibration displacement for feedback control design purpose. Concerning the wire problem due to rotary operation, a transmission mechanism is implemented between the ultrasonic machining assisted device and the cutter. In practice, vibration displacement of 0.23μm is transmitted to the cutter. Implementation of the entire ultrasonic assisted servo system onto a grinding machine with an operation speed of 10000 rpm to grind glass, for example, can obtain roughness Rave of 0.9353nm measured by Atomic Force Microscopy (AFM), which is much better than the regular operation with roughness Rave of 13.82nm. As expected, the developed system is suitable for the subject of ultrasonically assisted machining purpose to improve the grinding efficiency.

參考文獻


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