约束面投影成型室基底微观特征对透光性的影响

为了探明约束成型室基底微观孔隙特征对固化光源传播特性的影响规律,从而对光固化成型精度进行分析和预测,采用时域有限差分软件对成型室约束基底引入微孔特征条件下的透光性及在固化区光能量分布特性进行了数值模拟,并通过实验对模拟结果进行了验证.结果表明,约束基底引入微孔的形状、尺寸以及周期等微观几何特征影响基底的透光性及其透过基底在成型区的光强分布;相对于基底微孔形状,其尺寸和周期的影响更显著,减小微孔尺寸和周期有利于透光性以及光强在成型区分布的均匀性;微孔直径小于半波长、微孔边缘间距与微孔直径的比值小于1∶1时可以显著减小微孔的负面影响;微孔直径远大于半波长时,基底上的微孔将在成型零件表面形成不期望的附加特征,从而影响成型精度.研究结果可以为基底制备提供工艺改进的方向和理论依据.

Influence of Micro-feature parameters of Substrate on Light Transmittance in Constraint Surface Projection Stereolithography

To find out the influence rule of micro-pore geometric characteristics in the confined forming chamber on the propagation properties of the curing light source,and then analyze and predict the manufacturing accuracy in stereolithography process,numerical study was done using FDTD software to obtain the light transmittance of the substrate machined micro-pore array and the characteristics of light energy distribution in the curing zone.The simulation results were verified by experiments.The research results show that the shape,size and period of the micro-pore formed in the constrained substrate affect the light transmittance and the light intensity distribution in the forming area.Compared with the shape of the micro-pore on the substrate,the size and period of the micro-pore show a more significant effect,in which,reducing the size and period of the micro-pore facilitate the light transmittance and the light intensity uniformity improvement.If the diameter of micro-pore is less than half wavelength and the ratio of micro-pore edge spacing to micro-pore diameter is less than 1∶1,the negative effect of micro-pore can be reduced significantly.When the diameter of micro-pore is much larger than half wavelength,an undesirable additional feature on the surface of the fabricated part will be formed due to the micro-pore in constrained substrate and thus affecting the manufacturing accuracy.The results can provide direction and theoretical basis for the improvement of substrate preparation process.