基于有限元的光固化快速成形中零件变形研究

以光固化快速成形过程中的零件变形为研究对象,详细分析了收缩力产生的根源及其作用原理,根据树脂固化时必然产生的收缩及层累加的特点,提出了收缩力、面分布载荷的概念;根据零件在成形过程中结构变化的特点,提出时变刚度的概念。基于此,建立了零件成形过程中的力学模型,利用有限元法分析了零件变形的趋势,揭示了成形过程中零件变形的本质问题。通过试验研究了零件的变形问题,试验结果证明了理论分析的正确性。由此提出了改进扫描工艺的分区域扫描策略,显著的减小了成形过程中零件的变形,提高了成形零件的精度。

ANALYSIS OF THE PART DEFORMATION IN STEREOLITHOGRAPGY BASED ON FEA

Taking the part deformation in SL process as the objective of study, the source of shrinkage force and its acting principle is analyzed in detail. Some new concepts as shrinkage force and surface-distributed loads are proposed according to the resin shrinkage while curing and the adhesive characteristics between adjacent layers. Furthermore, the time-varied stiffness is presented based on the change of part structure during layer incress. Based on the FEA method, the deformation trend of part is demonstrated. Hence the nature of part deformation in SL process is exposed. The experiment results show that they are consistent with the theoretical analysis. Therefore, a new hatching pattern called separate area scanning is proposed, which can improve the part accuracy by reducing the deformation.