本研究是利用COMSOL Multiphysics軟體模擬三維暫態之氣體輔助雷射切割超薄玻璃，其研究目的是利用簡單模型了解氣體輔助切割與因熱應力產生粗糙裂紋(熱影響區深度)之間的關係。在研究中承接了實驗室團隊之研究成果，考慮材料反射率吸收係數以及切割過程之相變化，使溫度場更貼近真實情況。本文主要分析的有噴束輔助之噴束參數：噴嘴直徑、噴嘴與材料之距離、雷諾數，除此之外也探討不同切割參數：雷射光斑直徑、雷射能量(有無相變化)在使用噴束輔助之影響。
本研究選用Al2O3為待切割材料，模擬結果顯示，無論切割過程中是否有產生相變化，在噴嘴參數(噴嘴直徑、噴嘴與材料之距離、雷諾數)中固定其餘兩者，噴嘴直徑越小或噴嘴與材料之距離越小或雷諾數Re越大，熔化深度與熱影響區深度會越小，有較佳的切割結果。
在探討不同切割參數與有無噴束輔助切割之結果顯示，固定其餘參數，且都有產生相變化之切割情況下，選用光斑直徑較大的，切割面上的熱影響區與熔化的深度與表面寬度減少的值與比例皆較多；而在探討雷射能量時，選用雷射能量較大的切割參數，即有產生相變化之切割，在切割面的深度或是表面寬度上，能量較大減少的熱影響區的值比較多，因此選用光斑直徑較大者以及能量較大者之切割參數，其使用輔助氣體之效果更加明顯。
最後經由結果分析可得，使用噴束輔助可以增加其冷卻速率，進而增加切割效果；除此之外，噴束輔助也會減緩表面對於深度之間的溫度梯度，進而減少微裂紋的產生，改善了切割品質。

This study is to simulate the 3D transient gas-assisted laser cutting for ultrathin glass by COMSOL Multiphysics software. The research purpose is to use the simple model to understand the relation between gas-assisted cutting and the rough crack (heat affected zone depth) produced by the thermal stress. This study continues previous works of our lab team to consider the reflection and absorption coefficient of material and phase change of cutting process in order to obtain the real temperature distribution. The main jet-assisted parameters are nozzle diameter, the distance between nozzle and material, Reynolds number. In addition, the different cutting parameters, including laser spot diameter, laser energy are also investigated.
In this study, Al2O3 is chosen as the cutting material. The simulation result shows that the smaller diameter of the nozzle or the smaller distance between nozzle and material or the larger Reynolds number makes heat affected zone depth smaller, and has better cutting quality.
For the examination of jet-assisted cutting parameters, the results show that with larger spot diameter or laser power, the depth of the heat affected zone reduces more, so that the enhancement of jet-assisted becomes more obvious.
Finally, the simulation results also show that using jet-assisted cutting can increase cooling rate to improve the cutting. Besides, it also reduces the surface temperature gradient in depth and improves the cutting quality.

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