DLP列印範圍延伸之探討

Abstract

本研究企圖以較低的設備成本與較短的印製時間透過數位光學處理(Digital Light Processing, DLP)技術印製出八隅體微米級結構，本系統採用光固化上照式成型系統，搭配三軸步進移動平台以擴大延伸列印面積，印製出高層數的大面積微結構，並且修改平台移動路徑將印製時間大幅縮短，欲探討延伸結構面積是否會影響機械性質，以及改變八隅體結構的比例，比較不同尺寸比例會對其機械性質造成影響。 而在印製過程中，藉由改變曝光時間、樹脂調配、切層厚度等列印參數印製出不同的結構，以及分析印製過程中所碰到的問題，尤其印製2x2結構時，平台會往X-Y平面移動，進而增加影響印製結果的因素，實驗結果發現在印製高層數的2x2結構會產生黏附現象(Stiction)，在中間接縫處結構因為表面張力不同而造成桿件扭曲變形。 印製完後測試八隅體結構之機械性質，發現延伸結構面積並不會影響抗壓強度；另一方面，改變單軸尺寸比例之結構會降低其機械性質的表現；最後，模擬結果與實驗結果定性相同，但定量不同，模擬結果之剛性大於實驗結果，原因為實際桿件成形方式與設計有所差異，導致實驗結果剛性較小。

This research attempts to print the octet-truss lattice microstructure by DLP technology with a lower equipment cost and a shorter printing time. This system employs top-down exposure stereo-lithography. By using a three-axis stepping motor platform to expand the printing area, this system can print microstructures in high levels. In addition, modifying the movement path can reduce the printing time effectively. The purpose of the research is to explore whether the extended structure will affect its mechanical properties, and comparing mechanical properties by changing the ratio of microstructures. In the printing process, this research produced different structures by changing some parameters such as exposure time, resin formulation, and layer thickness which will influence the results. These factors will be discussed separately in the research, especially when it comes to 2x2 structures, the platform moves in X-Y plane which increases the variables that affect the structures. The results of the 2x2 structure occurs stiction problem, which causes the octet-truss to be deformed by different surface tension. Testing mechanical properties will be the last step after printing structures. According to the compression testing, extending the area will not affect the compressive strength. On the other hand, changing the ratio of the octet-truss lattice microstructure can decrease its mechanical properties. Finally, the simulation result is qualitatively the same as the experimental result, but the quantitative is different. The simulation result of stiffness is better than the experiment result, because the forming of the actual truss between designing truss is different, which will decrease its stiffness.