- 學位論文
導熱柱對熔融沉積式3D列印特性之數值研究
Influence of the thermal conducting fin on printing characteristic of the 3D printer with fused deposition modeling
摘要
3D列印為近年蓬勃發展之產業，除廣泛應用於工業製造外，在醫學領域亦備受重視。針對生物相容性材料之現有熔融沉積式3D列印機台，本論文採用Solidification Melting模型模擬此相變材料於料桶內之預熱融化過程，得知內部存在融化不均之現象，因而探求改善之方式。由初步結果研判受自然對流影響而造成融化不均，因此藉由加入導熱柱的方式，幫助內部融化速率較慢區域快速傳熱，並減少總融化時間。進一步探討系統及導熱柱參數之影響，包含加熱功率、導熱柱角度、導熱柱直徑、導熱柱數量以及導熱柱位置等。由模擬結果發現，加入導熱柱確實有助於減少總融化所需時間，歸因於其將料桶內部流場分化成上、下兩個較小的自然對流循環，避免長距離對流熱傳造成之溫度不均現象。最終透過大量模擬得到導熱柱之最佳設計參數以增加預熱融化效率，並藉由熱場、流場以及液體分率分布解釋原因。 藉由液體分率輪廓圖可以看出，當導熱柱位於較佳的擺放位置時，上、下兩處固體具有同時融化完畢的現象。而使用不同功率加熱並不會導致較佳的擺放位置偏移，隨著加熱功率增加，融化所需時間則減少，從時間節省比率來看，不同熱通量對此並不會造成太大影響。導熱柱在特定位置及角度下對於融化的影響具有較佳的效果，當高度往上偏移時，最佳導熱柱角度則會向下偏移。在所有的參數條件當中，導熱柱直徑為0.2D且高度為Y1時，在角度為20o的情況下具有最佳的時間節省率，其值為15%
並列摘要
3D printing is a booming industry in recent years. In addition to being widely used in industrial manufacturing, it has also been valued in the medical field. Aiming at the existing fused deposition modeling (FDM) 3D printer for the biocompatible material, this paper uses the Solidification Melting model to simulate the preheating and melting process of the phase change material in the barrel, and it is known that there is uneven melting inside so that explore ways to improve. According to the preliminary results, the uneven melting is caused by the influence of natural convection. Therefore, by adding the thermal conducting fin, it helps heat transfer in the slower internal melting area quickly and reduces the overall melting time. Further discuss the influence both the system and the parameters of the thermal conducting fin, including the heating power of system, as well as the angle, the diameter, the number, and the position of the thermal conducting fin. From the simulation results, it is found that the addition of the thermal conducting fin does help to reduce the time required for the overall melting, due to the fact that it divides the internal flow field of the barrel into two smaller natural convection cycles, avoiding temperature unevenness caused by long distance convective heat transfer. Finally, through many simulations, the best design parameters of the thermal conducting fin are obtained to increase the preheating and melting efficiency, and the reason is explained by the thermal field, flow field and liquid fraction distribution. It can be seen from the liquid fraction contour graph that when thermal conducting fin is in a better position, the upper and lower solids melt at the same time. Moreover, heating with different powers will not cause a better placement position shift. As the heating power increases, the time required for melting decreases. From the saving time ratio, different heat fluxes will not cause too much influences. The thermal conducting fin has a better effect on melting at a specific position and angle. When the height is shifted upward, the best thermal conducting fin angle will shift downward. Among all the parameter conditions, when the height is Y1 and the diameter of the thermal conducting fin is 0.2D, it has the best saving time rate when the angle is 20o, and its value is 15%.
參考文獻
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