超音波輔助光學玻璃熱壓成形

Abstract

玻璃熱壓成形技術是玻璃光學元件重要的製程方式，用於量產非球面等複雜結構的光學元件，可大幅降低製造的成本。而超音波振動已經廣泛應用於輔助塑性加工，藉由摩擦力的改變、材料溫度升高等現象，使得材料成形性提高，提昇加工精度及降低成本。本研究嘗試結合超音波振動輔助應用於玻璃熱壓成形製程中，利用超音波振動對玻璃材料性質的改變，提升玻璃成形的效能與成品的品質，並延伸玻璃熱壓成形技術的應用。 研究中為了實現超音波輔助玻璃熱壓成形，首先針對實驗機台進行開發，以結合超音波與玻璃熱壓成形之技術。超音波振動裝置的輸出端設計為玻璃熱壓成形之上模具，再藉由修正超音波放大器之外形以補償共振頻率，使得超音波振動裝置可在玻璃熱壓成形的高溫環境下正常運作。接著利用建立之機台，對光學玻璃K-PSK100 (Sumita Co., Tg=398°C) 進行成形實驗，探討施加超音波振動對於光學玻璃熱壓成形的效應。於平面熱壓實驗中，玻璃材料受超音波振動後會發生應力降低之現象。而在成形V溝與Fresnel之複雜外型結構之實驗中，藉由超音波振動的輔助，可有效提升複雜結構的成形性。

Glass hot embossing technique is essential in mass producing glass optical elements. With the vigorous developments, the process was capable to produce aspheric or complex optical elements with low cost. Ultrasonic vibration-assisted forming is extensively adopted in plastic manufacturing processes. With the effects of changing the frictional condition and raising the material temperature, the material formability is increased, the forming accuracy is improved and the cost is reduced. Thus, this study is aimed to integrate the ultrasonic vibration-assisted forming and the glass hot embossing process. The effect of changing material properties caused by ultrasonic vibration was applied to improve the glass forming efficiency and the product quality, and stretch the applications of glass hot embossing technique. In order to realize the ultrasonic vibration-assisted glass hot embossing process, an experimental apparatus was firstly developed to integrate the techniques of the ultrasonic vibration and the glass hot embossing. The output end of the ultrasonic vibration device was designated as the upper mold of the glass hot embossing; and the resonant frequency was compensated by modifying the dimensions on the ultrasonic horn, so the ultrasonic vibration device could be operated at the high working temperature of glass hot embossing process. With the built apparatus, the optical glass K-PSK100 (Sumita Co., Tg = 398°C) was adopted in molding experiments to investigate the effects of ultrasonic vibration on the glass hot embossing process. In the flat hot embossing experiments, the loads were reduced as the ultrasonic vibration applied; in molding V-groove and Fresnel structures, the formability on these complex structures were significantly enhanced with the assistance of the ultrasonic vibration.