選擇性雷射熔融之積層製造系統建置與應用於可調控式單線精微結構研究

Abstract

本論文中以粉床式積層製造平台為基礎，建構出選擇性雷射熔融系統，而後以調控精微結構為目地進行單線軌跡燒熔實驗。由於精微結構是以數層單線堆疊而成，因此實驗首先以功率24 W雷射進行單層單線的燒熔測試，並輔以底板預熱觀察燒熔軌跡之成型狀況，而後依據實驗結果找出最佳的成型參數區間。接著，為探討在不同積層高度時熱擴散速度對軌跡成型之影響，以重覆堆疊相同參數之單線軌跡的方式形成薄牆結構，透過電子顯微鏡觀察其表面與側向輪廓，可以得到在不同層次的條件下掃描速度對單線線寬之關係曲線，從曲線中可以發現線寬將會隨層次上升而增加。 根據上述實驗結果，我們能以最佳參數之成型軌跡為第一層結構，利用熱擴散速度隨積層高度增加而降低的特性，成功地製作出可調控式之精微結構。從中可明顯觀察到隨著積層高度增加，線寬較細的燒熔軌跡也能擁有穩定地成型結構，利用這些結果我們已能製作出具深寬比約5.5之薄牆結構，進而設計製作具多孔性之輕量化元件。

In this thesis, we construct a selective laser melting (SLM) system based on a powder bed fusion additive manufacturing and can be applied to controllable single line multi-layered metal microstructures. The single track microstructure is built up with multi-layered single track, therefore, we began with the first layer single track formed by laser power 24 watt and compared with the forming single track in different preheating temperature. The next step of experiments was going to investigate the influence of the heat transfer on forming different single track multi-layered microstructures. The contour of fabricated structure was measured by scanning electron microscope (SEM), we could get the relationship between the width of tracks and the scanning speed in the different height of structure. We found that the track width is increased as the height of the structure is increased. According to the experiment results, we could form the first layer with stable parameter and build up controllable structure by lower heat transfer effect in high layer. As higher structure, the thinner track would be form stably. As result, we could made a thin-wall structure with aspect ratio about 5.5. Finally, the lightweight design structure could be build up by controllable single track multi-layered microstructures.