在選擇性雷射熔融 (SLM) 氣氛腔體中，如何提升彈射金屬粒子的移除率被視為改善製程品質的一大重要因素，而流場的發展與分析即是扮演解決此問題之關鍵角色，本篇論文基於先前對於AM250之研究，將工作平面擴大為500 mm × 500 mm，並設計一由上方吹氣下方抽氣之流場應用於工作腔體內，透過計算流體力學 (CFD) 與田口法之搭配，探討吹氣噴嘴外型、抽氣端厚度、抽氣裝置的距地高度以及噴嘴入口雷諾數在不同參數配比下對於流場發展以及金屬粉末移除率之影響，創造出一最佳化之流場設計，並藉由粒子圖相測速儀 (PIV) 分析所取得之實驗數據與模擬結果進行交叉驗證；此外，為了使模擬能夠更貼近實際製程，工作底板的加熱與金屬粒子的彈射行為也是本研究探討重點。而結果顯示了噴嘴所造成之軸轉換現象以及抽氣裝置之距地高度為改善金屬粒子移除率之重要參數。

Collecting and recycling the metal powders ejected from the working plane have been the primary objects for improving the manufacturing process of selective laser melting (SLM). The flow behaviors across the SLM working chamber are obviously significant and need to be further studied for solving these matters. In this study, we continue the studies presented previously to design a blow-to-suction device scaling-up from 250 mm × 250 mm to 500 mm × 500 mm. The air curtain inside the SLM working chamber, instead of a parallel flow, was designed as the one with a vertical downward blowing jet as well as two parallel suction devices. Computational fluid dynamics (CFD) and Taguchi method were investigated for simulating the flow field cross the working chamber, with the variations of the shape of push nozzle, the width of suction tunnel, the suction-to-plane distance and the Reynolds number of blowing flow. Particle image velocimetry (PIV) is used to provide the experimental information of the flow field and further verify the results from the simulation. The eject motion of the metal powders were also taken into consideration for carefully studying the interaction between the flow and the ejected particles. The results demonstrate that axis switching as well as the suction-to-plane distance are the important parameters for improving the particle removal efficiency inside the working chamber.

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