Study on processing mechanism to reinforce weld line strength by advanced methods for micro injection molding

微注射成型技术作为一种新型的制造技术，受到了国内外的广泛关注。熔接痕是普通注射成型和微注射成型过程中常见的缺陷，但对微注射成型不利。因此，深入了解熔接痕的形成机理，对提高注塑件的质量具有重要意义。目前，对于普通尺寸注塑成型中熔接痕现象的研究已经比较深入，但对于微注塑成型中熔接痕的研究还不够深入。本研究将熔接痕分为冷熔接痕和热熔接痕两种情况，建立了微尺度熔接痕形成过程的模拟方法，以预测微注塑成型中熔接痕的强度和位置。此外，还对影响微注射成型熔接线力学性能的因素进行了研究，如工艺参数、微通道截面形状和V形缺口等。并对焊缝发展过程中的微流体行为和V型缺口的形成进行了全面的探讨。此外，还对结晶性聚合物、无定形聚合物、短纤维树脂和金属颗粒填充聚合物等不同材料的熔接线性能进行了检验。同时也将发展其力学性能测试方法。

As a novel fabrication technology, micro injection molding is drawn much attention all over the worlds. Weld line is a usual but unfavorable flaw both in normal and in micro injection molding process. Therefore, it is important for improving the quality of injection molding parts that the weld line developing theory is understood completely. Nowadays, the weld line phenomena in normal size injection molding field has been studied maturely, but as for micro injection molding, the concentration is not enough adequate. In this project, the cold and the hot weld lines will be considered and the simulating method for micro scale weld lines forming process is intended to be built up for predicting the strength and position of the weld lines in micro injection molding. In addition the factors which influence the mechanical properties of weld lines in micro injection molding will be studied, like processing parameters, cross section shape of micro channels and V notch. The micro fluid behavior and the V notch formation during the weld line developing process will also be explored comprehensively. Furthermore, the weld line properties for different materials, like crystalline polymer, amorphous polymer, short fiber resin and metal particles filled polymer, are going to be checked up. As well as the mechanical property test methods will be developed.