臺灣博碩士論文加值系統

本文提出破裂切削(fracture machining)的雷射加工技術，利用破壞力學中裂紋擴展與缺陷連結的原理來去除材料。雷射加載在缺陷處造成應力集中，進而誘發缺陷連結，而雷射所造成的凹槽裂紋即是一種缺陷。此技術構想源之於陶瓷薄板控制破裂(controlled fracture)的雷射切割研究，本文將其應用範圍由二維的薄板切割推廣到三維厚板的銑削成形與貫穿切割。破裂切削技術有別於傳統燒熔方式，所需雷射功率低、材料去除率高、切削精度佳。本文以有限元素軟體ANSYS模擬雷射加工的溫度及應力場，以氧化鋁陶瓷厚板為實驗試片，雷射源包括CO2和Nd-YAG雷射兩種。首先建立起邊緣銑削的基本模式，成功地完成45°角的邊緣切割，並探討邊緣銑削條件之間的關係，包括雷射功率、雷射加載路徑、雷射移動速度、銑削進給量、材料去除率。依此基本模式，可達成三維成形之目的，如階梯、半階梯角、圓弧階梯等銑削。其次提出破裂切削元素的觀念，包括三角形與矩形去除元素，可應用於中央銑削。中央銑削不同於邊緣銑削，可在材料平面任意處加工，例如矩形凹穴及平行四邊形凹穴銑削。
最後探討兩種陶瓷厚板貫穿切割技術，其一為雙雷射同步加載，以聚焦的Nd-YAG雷射，及離焦8mm的CO2雷射同時加載在同一位置，可進行陶瓷厚板的貫穿切割，切割厚度可達10mm。其二為雷射劃割，以Nd-YAG雷射在厚板表面劃割一個深凹槽，再從背面以雷射掃描，產生熱應力使其貫穿破裂。利用此兩種方式進行直線或更複雜之曲線切割，品質均比傳統燒熔方式佳，且大幅降低對雷射功率的需求。

A new laser machining technique for ceramic material based on the concept of fracture machining is proposed in this paper. The material removal is due to the crack propagation and the linkage of defects. The original concept of fracture machining comes from the laser cutting technique with controlled fracture for the brittle thin plate. The conventional laser machining requires high laser power and will result in many cracks during the grooving process. But the required laser power of the required laser power of the present method is much smaller than the traditional method. The finite element software ANSYS is used to analyze the temperature and stress distribution during the laser machining process. The experimental specimens are Al2O3 ceramic, and the laser sources are CO2 laser and Nd：YAG laser. The technique of edge machining for ceramic thick plate is investigated. The relationships of process parameters such as material removal rate, surface roughness, laser scanned speed, laser power, and feed speed of laser is also discussed. The fundamental models of material removal of strip material and fracture machining element are proposed. They can be applied on the edge milling and center blind-cavity milling for arbitrary shape.
Finally, the two penetrated cutting methods for thick ceramic substrate are discussed. One is applying the CW focused Nd-YAG laser and the defocused CO2 laser at the same time to separate the ceramic substrate, in which the cutting depth can reach 10mm. The other is using Nd-YAG laser to scribe a groove-crack on a substrate, then applying the defocused CO2 laser at the back-side of the substrate to separate the material. Using this way to proceed more complicated curve cutting, the result of ceramic substrates are better than traditional method, not only on the rough status, but the crack faults, and so on, furthermore it decreases substantially the demands of laser power.

摘 要 I
ABSTRACT II
目 錄 III
表 錄 VI
圖 錄 VII
第一章 緒論 1
1.1 雷射破裂切削的技術原理 1
1.2 雷射破裂切削技術之特點及重要性 2
1.3 控制破裂切割與雷射劃割之前人成果 3
1.4 陶瓷雷射成形加工之前人成果 6
1.5 本文目的 9
第二章 雷射破裂銑削原理 14
2.1 實驗設備與材料 14
2.2 長條狀材料去除模式 15
2.2.1 材料去除步驟 15
2.2.2 材料去除率 16
2.2.3 去除過程中破裂超前量 16
2.3 平面狀材料去除模式─破裂切削元素 17
2.3.1 矩形元素去除 17
2.3.2 三角形元素去除 18
2.3.3 材料去除機制 18
2.3.4 去除單元大小與雷射功率 19
2.4 雷射劃割凹槽裂紋 19
2.4.1 凹槽裂紋深度 19
2.4.2 劃割條件與劃割深度 21
2.5 顯微組織觀察 22
2.5.1 Nd-YAG與CO2雷射劃割之顯微觀察 22
2.5.2 長條狀的材料去除模式顯微觀察 23
2.5.3 平面狀材料去除模式顯微觀察 25
2.6 破裂連結之有限元素分析 26
2.6.1 長條材料去除之有限元素分析 26
2.6.2 平面狀材料去除之有限元素分析 27
第三章 陶瓷厚板邊銑削實驗 74
3.1 邊銑削的程序與原理 74
3.2 斜面銑削 75
3.3 階梯銑削 76
3.4 半階梯角銑削 77
3.5 圓弧階梯銑削 77
3.6 材料去除率 78
3.7 銑削品質 79
3.7.1 顯微組織觀察 79
3.7.2 表面粗糙度量測 80
第四章 陶瓷厚板中央銑削實驗 92
4.1 中央銑削之程序與原理 92
4.2 矩形凹穴銑削 92
4.3 平行四邊形凹穴 93
4.4 材料去除率 95
4.5 中央銑削品質 95
4.5.1 顯微組織觀察 95
4.5.2 表面粗糙度 96
第五章 陶瓷厚板控制破裂雷射切割 106
5.1 厚板雷射切割原理 106
5.2 雷射加工條件 108
5.2.1 對稱直線切割 108
5.2.2 非對稱切割 111
5.3 顯微組織觀察與斷面品質 112
5.4 厚板切割之有限元素分析 114
5.4.1 寬度108mm陶瓷厚板破裂切割分析 114
5.4.2 寬度54mm陶瓷厚板破裂切割分析 115
第六章 陶瓷厚板雷射劃割 133
6.1 厚板雷射劃刻原理 133
6.2 雷射加工條件 134
6.3 有限元素分析 134
第七章 結論 141
7.1 本文重要成果 141
7-2 未來研究方向 143
參考文獻 145
簡 歷 149

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