基于收缩补偿的面曝光成型零件尺寸精度的改善

Improvement on Dimensional Accuracy of Parts Molded by Mask Projection Stereolithography based on Shrinkage Compensation

针对面曝光成型零件易收缩的问题,采用单因素实验研究了曝光时间、分层厚度、回合等待时间这3项工艺参数对圆柱形零件尺寸收缩率的影响,以获得合理的水平值,然后通过正交实验和极差分析法得到最佳工艺参数组合及该组合下的零件尺寸收缩率,在此基础上计算出收缩补偿因子,在零件分层之前对其尺寸进行收缩补偿,以获得高尺寸精度成型零件。结果表明,在同一工艺参数下Z向的收缩较XY平面方向更为严重;对Z向尺寸精度影响程度从大到小依次为分层厚度、回合等待时间、曝光时间;最佳工艺参数条件下XY平面方向的收缩补偿因子为1.001,Z向的收缩补偿因子为1.015 2。经过对复杂零件扩散器模型的收缩补偿,发现在最佳工艺参数下Z向尺寸收缩率由未收缩补偿前的1.59%降低至0.03%,显著提升了面曝光成型零件的尺寸精度。

Aiming at the easy shrinkage problem of parts molded by mask projection stereolithography,the effects of three process parameters such as exposure time,layer thickness and round waiting time on the dimensional shrinkage of cylindrical parts were studied by single factor experiment to obtain reasonable level values,then the optimum combination of process parameters and the dimensional shrinkage rates under the combination were obtained by orthogonal experiment and range analysis.On this basis,the shrinkage compensation factors of the parts were calculated,and the shrinkage compensation was made to the size of the parts before the parts are stratified so as to obtain the high precision molding parts.The results show that the Z-direction shrinkage is more serious than the XY plane direction under the same process parameters,the influence sequence of the process parameters for Z-direction dimensional accuracy is layer thickness,round waiting time and exposure time from large to small.Under optimal process parameters,the shrinkage compensation factor in XY plane direction is 1.001,and the shrinkage compensation factor in Z direction is 1.015 2.After shrinkage compensation for the complex part diffuser model,it is found that the Z-direction dimensional shrinkage rate under the optimal process parameters is reduced from 1.59%(before the shrinkage compensation)to 0.03%,which significantly improves the dimensional accuracy of the parts molded by mask projection stereolithography.