臺灣博碩士論文加值系統

摘要
本文應用雷射破裂切削原理來進行氧化鋁材料的微量去除加工，提出一個新的材料去除加工技術-雷射破裂磨削技術。此法首先以聚焦CO2雷射劃割於陶瓷材料上，使其產生網格狀龜裂紋；再以離焦雷射使裂紋破裂連結，達到材料去除的目的。雷射劃割過程會在表面形成中央主裂紋、徑向裂紋及側向裂紋，並連結成為屑片元素；屑片元素即為材料去除的最小單元，其最小尺寸為0.1mm×0.1mm×0.02mm。此法能有效去除雷射加工時產生的熱變質層及裂紋缺陷，改善加工面品質，其表面粗糙度約可達Ra=1.14μm。本文首先針對微裂紋生成機制進行探討，以有限元素軟體分析其溫度場及應力場；並藉由電子顯微鏡的觀察驗證微裂紋成長形態；加工過程以聲射系統監測破裂聲波放射訊號。最後並尋找最佳的加工參數，以達到最佳的表面品質。
本文最後將以聲波放射系統探討雷射破裂切削技術的破裂擴展過程，包括了二維陶瓷薄板切割及三維陶瓷厚板銑削。為了達到良好的加工效率，破裂成長狀況的探討是這些技術重要關鍵。本文針對陶瓷基板雷射劃割之微裂紋缺陷；控制破裂雷射切割；雷射邊銑削之凹槽裂紋連結及破裂銑削元素裂紋連結等現象進行探討。藉由多個感測器接收破裂擴展所釋放的聲波，即時觀察出破裂發生次數、時間及位置，進而找出破裂擴展機制及原理。

ABSTRACT
A new laser machining technique developed from the concept of fracture machining was proposed to produce a micro-removal of ceramic material. A focused laser is scanned along a constant direction to generate micro-cracks on ceramic substrate, forming a fine crack network. A defocused laser is then scanned along the same path again. The laser heat generates tensile stresses that are concentrated at the tip of crack and induces the extension of the micro-cracks. Materials are removed due to the systematical linkage of the micro-cracks. The median cracks, radial cracks, and lateral cracks are formed on the material surface during the laser scribing process. The cracks will link together and form the chip-element, which is the fundamental unit of material removal. The minimum average length of the removed chip-element is about 0.1 mm and the thickness is about 0.02 mm. The surface quality is very good and the arithmetic average surface roughness is about 1.1 mm. The finite element software was used to analyze temperature and stress distribution. The SEM photographs of the machining surface and the acoustic emission data were obtained to analyze the micro-mechanism of the fracture machining process. The relationship between the surface quality and machining parameters was also discussed.
Finally, an acoustic emission system is applied to investigate the phenomena of cracks propagation and linkage during the fracture machining process. The AE sensor can detect a signal when crack is generated. The acoustic emission signal provides useful information about material removal mechanism. The AE signal parameters for investigations were peak amplitude and event counts. The crack formations of laser scribing and controlled fracture, and the crack linkage of laser milling were studied by using the acoustic emission technique.

摘要 I
ABSTRACT II
目錄 III
表錄 VI
圖錄 VII
第一章 緒論 1
1.1 雷射破裂切割技術 1
1.1.1控制破裂雷射切割 1
1.1.2 雷射破裂銑削 2
1.2 傳統雷射材料去除技術 3
1.2.1雷射燒熔式材料去除 4
1.2.2準分子雷射表面修整 5
1.3本文目的 7
第二章 雷射加工系統與聲射技術 13
2.1雷射加工系統 13
2.2電子顯微鏡 13
2.3聲射系統介紹 14
2.3.1聲射系統設備 14
2.3.2聲射量測系統技術介紹 15
2.3.3聲射系統於破壞量測上之應用 16
2.3.4聲射量測系統參數分析的選擇 17
第三章 雷射破裂磨削原理 27
3.1材料去除模式 27
3.2雷射劃割熱應力與裂紋成長 28
3.3 雷射劃割進給與屑片元素 30
3.4 熱破裂之雷射光點 30
3.5雷射劃割之有限元素分析 32
第四章 雷射破裂磨削實驗 50
4.1雷射破裂磨削實驗程序 50
4.2 網格裂紋與屑片元素之形成 50
4.3 雷射磨削加工條件 51
4.3.1雷射劃割 51
4.3.2雷射熱破裂 52
4.4 加工品質探討 53
4.4.1 表面粗糙度量測 53
4.4.2 雷射劃割裂紋顯微組織觀察 54
4.4.3 熱破裂顯微組織觀察 55
4.5聲射系統量測分析 56
4.5.1 雷射劃割聲波量測分析 56
4.5.2 雷射熱破裂聲波量測分析 57
第五章 雷射破裂切削之聲射量測實驗 84
5.1控制破裂雷射切割之聲射量測實驗 84
5.1.1 雷射劃割聲射訊號分析 85
5.1.2控制破裂切割聲射訊號分析 85
5.1.3控制破裂切割聲射訊號定位分析 87
5.2 邊銑削聲射系統量測實驗 88
5.2.1邊銑削熱破裂聲射訊號分析 88
5.2.2邊銑削聲射訊號定位分析 89
5.3中央銑削聲射系統量測實驗 90
5.3.1中央銑削熱破裂聲射訊號分析 90
5.3.2 中央銑削熱破裂聲射訊號位置之觀察 91
第六章 結論 113
6.1本文重要成果 113
6.2未來研究方向 114
參考文獻 116
簡歷 120

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