面曝光固化快速成型曝光时间的参数优化研究

Optimization Study on Exposure Time for Mask Projection Stereolithography System

面曝光快速成型是光固化成型领域快速高速发展的一种工艺,曝光时间是成型工艺中的关键参数之一,对于成型质量有直接关系:若曝光时间过短,正在固化的树脂层硬度不够,在重力的的作用下会使其下落,进而影响下层树脂的固化,一层影响一层,最终使得逐层固化的树脂精度不高,导致制件变形较大;若曝光时间过长,正在固化的树脂硬度会比较高,但是其收缩也会比较明显,同时会在固化层和树脂槽之间会产生真空,真空力会使打印金属平台上升时所产生的拉力增大,容易造成固化层脱落遗留在树脂槽中,导致打印物件制造失败。通过比较不同曝光时间下样品的凝胶含量和双键转化率两大指标,确定样品随着曝光时间的增加固化程度也在不断增加;然后通过比较不同曝光时间下样品的拉伸储能模量,发现样品随着曝光时间的增加力学性能也随之增强。通过综合比较固化程度、成型力学性能、成型精度三大因素,确定整体成型最佳曝光时间。通过两个分层试验验证了前述最佳曝光时间的合理性。

The surface exposure prototype was a high-speed technology in the field of stereo lithography, and the exposure time was a key parameters in the processing process ： if the exposure time was too short, the deformation of parts would be high that the resin layer would fall into the next layer; on the contrary-, if the exposure time was too long, the object couldn＇t be manufactured that the vacuum force caused by the curing layer and the resin tank made the print the metal platform generated when an increase in tension increases. Firstly, by comparing the different exposure time samples of the gel content and the double bond conversion rate, it shown that the curing degree increased with the increasing of exposure time, and cured degree in 10-20 s could reach 90%; by comparingthe different samples of storage tensile modulus, it shown the mechanical properties increased with the increasinbgof exposure time. Through the comprehensive comparison of the degree of curing, molding mechanical properties, molding precision three factors, the best exposure time was of 15 s. Finally, the rationality of the above best exposure time was verified by two ACME-DLP layered experiments.