Numerical Simulation Of Differential Injection Molding Method

Based on the concept of differential and integral method applied in advancedmanufacture of polymer materials differential injection molding, differentialinjection processing is a new method used in the precision micro products. Byusing melt differential pump with function of precision measurement,pressurizing and pumping, the general injection molding machines canachieve the aim of processing micro precision products in high efficiency.Combining with the advantage of conventional injection molding, microinjection molding, hot runner and melt differential pump technology,differential injection molding method has not only a strong research value inthe subject technology theory, but also is of important engineering value in themanufacturing of miniature plastic products and precise plastic products.Taking the differential molding system as the research object and using thenumerical simulation method, the research is done on the differential pumpsystem, runner system and molding process respectively, the main researchcontents are as follows:1. The model of melt differential pump in differential injection molding machine is firstly built. And the Fluent fluid simulation software is used tosimulate the flow field of the melt in the differential molding system. Thecharacter of flow field and pressure distribution under high temperature isstudied under differential pump structure and process parameters. And theinfluence of differential pump structure and kinematical parameters on themelt pump out pressure is obtained. Also a kind of optimal differential pumpstructure and process parameters is put forward.2. Aiming at runner system in the differential molding machine, Moldex3D mold flow analysis software is used to simulate the speed and shear ratedistribution of the melt flowing in different runners. The influence ofconstruction on runner pressure required and shear stress, as well as shear rateis studied, which provided the basis for runner design characterized with lowinjection pressure and pressure loss, as well as in which the melt has goodliquidity and its temperature is uniform. The reasonable runner design wouldalso reduce the internal stress of product and the warpage in every direction.At the same time the hot runner technology can greatly reduce the flowresistance of the melt flow.And hot runner technology can also make a fillingbalance in the multimode cavity of product, which could improve the qualityconsistency of the product.3. Aiming at the differential injection molding process, an analysis ofspiral micro-product is studied based on the Moldex3D mold flow analysissoftware. Such key parameters as the melt and mold temperature, injection pressure and time, packing pressure and time are chosen and the fillingvolume and warpage in every direction are chosen as the evaluation index tostudy the influence of processing parameters on the filling rate of the product.The simulation results laid foundation for the molding process and moldstructure optimization in the application of differentialinjection processing.