超音波及雷射輔助切削技術應用於石英玻璃銑削之研究

Application of Ultrasonic and Laser Assisted Machining Techniques for Quartz glass Milling

陳家澤(Jia-Ze Chen)

指導教授 ： 林盛勇

國立虎尾科技大學/工程學院/機械與電腦輔助工程系碩士班在職專班/碩士(2016年)

摘要

近年來，石英玻璃等難切削硬脆材在光源、電子、光通訊、雷射、航太等產業之應用日益廣泛，尤其在光電系統及半導體等領域的運用上特別活躍。隨著需求量不斷增加，對於石英玻璃各種加工品質的要求也日益嚴苛。目前從事石英玻璃加工的業者大多以雕銑、研磨或拋光等方式為之，加工製程較為繁雜且成本也較高，所以尋求縮短製程及有效節省成本等方面的突破，乃當前加工技術之重要課題。石英玻璃具有高脆性、高硬度、低延展性及低導熱性等性質導致切削性差，在加工過程中刀具易產生快速磨損，加工表面易產生裂紋、破裂及邊緣崩角等缺陷。因此，改善石英玻璃切削性能、加工效率及刀具壽命的提升為長期以來相關業者最關心的課題。
本文建構一四階段石英玻璃銑削實驗，包含無輔助、各單項輔助及多項混合輔助系統以驗證輔助效果之差異及優劣。首先，第一階段進行無輔助銑削以監測切削性能之變化及加工參數之調整。接著，第二至第四階段分別導入單軸超音波輔助、雙軸超音波系統單軸振盪混合雷射輔助系統及雙軸超音波雙軸振盪與雷射系統的混合輔助銑削。同時觀測表面粗糙度、邊緣形貌及刀具磨耗於各加工參數之變化趨勢，期提高脆性材料的可切削性，進而取得更好的表面粗糙度、表面形貌與刀具磨耗。再來，於雷射輔助銑削實驗前，先行測試雷射預熱於工件表面之碎裂時間，據以設定雷射-刀具距離。最後，將雙軸超音波輔助銑削系統架設於工具機工作台上，並經不斷反覆的測試、調校與修飾以確保雙軸振盪作動確實，同時結合雷射輔助系統以建構一混合式輔助切削加工系統。本文實驗採用耐磨耗且導熱係數較高的nACo®極細微粒碳化鎢鍍層刀具，透過加工製程參數（切削速度、徑向銑削深度、進給速度）全因子組合的調變規劃，針對石英玻璃進行上述四階段之銑削加工。於實驗過程中，使用動力計監測銑削力的變化，以工具顯微鏡觀測加工完成表面形貌與側邊緣形貌，並以表面粗度儀進行表面粗糙度之量測。結果顯示，雙軸超音波雙軸振盪與雷射系統的混合輔助銑削，不僅優於上述各單項輔助及多項混合輔助系統，且明顯地大幅度改善刀具磨耗與表面粗糙度。

關鍵字

石英玻璃 ； 雙軸向超音波輔助 ； 雷射輔助 ； 切削性能

並列摘要

Hardened and brittle material such as quartz glass has gradually become the important materials for light source, electronic, optical communication, laser and aerospace technology industry applications in recent years. In which electro-optical system and semiconductor applications are particularly active. As its demand is increased constantly, various requests on machining qualities of quartz glass are also more stringent. At present, the main machining ways on quartz glass are almost with engraving milling, grinding lapping or polishing and these machining processes are too complicated and too much wasted. Therefore, seeking a breakthrough for shortening the process and saving the cost effectively is an important issue for the machining workers. Because quartz glass have the properties of high hardness, large brittleness, less malleability, low thermal conductivity and hence low machinability, it causes the cutting-tool wear quickly during the machining process. Also, the crack and damage, and edge-indentation are easily generated on the machined surface and around outer edge, respectively. In order to solve the above problems, this project applies the diamond cutting tool to conduct quartz glass machining through a combination of an ultrasonically assisted machining and laser assisted machining under the conditions of high cutting speed, low depth of cut and suitable feed rate. It is expected to handle the material removal process corresponding to different ductile-brittle transition modes properly for quartz glass machining and enhance the processing efficiency, improvement of surface quality and reduction of production cost consequently.
The four stage experiments including without assistance, single and hybrid assisted machining systems on quartz glass milling were constructed in this study in order to verify the assisted effect on cutting performance and to compare the difference, merit and drawback among them. First of all, the milling experiment without assistance was performed to investigate the variations of cutting performance and the results were used for the suitable process parameter planning in the next stage experiments. Next, uniaxial ultrasonically assisted system, combination of laser assisted system and a biaxial ultrasonically assisted system with only one-axis oscillation (x or y direction), and combination of laser assisted system and a biaxial ultrasonically assisted system with simultaneous two-axis oscillations (x and y directions) were subsequently introduced at the second to the fourth stage experiments, respectively. At each stage experiment, the effects of process parameters on the variations of surface roughness, side-edge surface morphology and cutting-tool wear are investigated. It is expected that the machinability of this high brittle material can be promoted resulting in good cutting performance and better cutting-tool wear. Before the use of laser assistance, the laser preheating time related to the workpiece surface fragmentation should be tested in advance for a proper spacing distance setting between laser-spot and cutting-tool. Finally, a biaxial ultrasonically assisted machining system is designed, fabricated and mounted on a machine-tool work-table. At the meantime, a long-term oscillation test including calibration and detailed adjustment is conducted repeatedly until the whole normal manipulation of the system is assured. Thus, a hybrid assisted machining system can be established through the integration of this biaxial ultrasonically assisted system and a laser assisted system. Under these assistances, milling experiments of quartz glass by cutting-tool of extra-fine particle tungsten carbide with coating were conducted. And the full factorial experiments of process parameter combinations such as feed rate, cutting velocity and radial depth of cut were also planned. During the experiments, dynamometer is used to monitor the variation of cutting force. Tool wear, edge-indentation and side-edge surface morphology of the quartz glass will be measured by tool-microscope off-line. Surface roughness measurement through a probe contact type instrument is also performed. The results show that the milling experiment with both laser assisted system and an ultrasonically assisted system with simultaneous two-axis oscillations has the better results than those experiments without, with single assisted and the other hybrid assisted combinations. Because the use of this complete hybrid assisted system, the cutting performance of tool wear and surface roughness are improved significantly.

並列關鍵字

quartz glass ； dual-axis ultrasonically assisted ； laser-assisted ； cutting performance

參考文獻

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