Study And Application Of Numerical Method For Cooling Analysis In Injection Molding

More and more attention has been paid to cooling analysis CAE technology in the injection molding industry and its practical usage in this field is also in the rising. However, it still has some limitation due to two main factors. The first one is that the scale of model to be calculated can not be too large, the other is that the calculating speed is too slow sometimes.The static three-dimensional Boundary Element Method (BEM) for mold and transient one dimensional numerical solution for part are current widely used for the cooling analysis. In this method, two calculations are iterated until the desired result is acquired. In general, BEM forms full-matrix equations. As a result, it is very difficult to make the iteration converge when the scale of calculated problem is too large. In addition, the processing of this method is very time consuming and is hard to be optimized. Therefore, its efficiency is very low. These two problems strictly restrict the application of cooling analysis.The present research effectively solved the problems mentioned above. The cooling analysis model generated in this study dramatically improves the ability to deal with these problems. Some tasks, which would be difficult to calculate with the old BEM model because of the large scale, can be simply analyzed with the new model. Furthermore, there is a significant reduction in the computing time with rapid calculating method, about ten times faster than before. The six major works are as follow:1. Derived out the analytical solution for one-dimensional transient heat conducting equation of part under first type of unsymmetry boundary conditions. Then heat flux was expressed linearly with temperature on cavity surface. With the solution, BEM equation became the only equation which needs to be solved rather than the original coupling-iteration between two equations, which significantly enhanced the calculating efficiency. In addition, the outer surface of mold was considered as the surface of a finite sphere with the third boundary condition, contrasted to the old method that considered outer surface as a infinite heat-isolated sphere. Because the new model takes the heat transfer on mold surface into account, it is more accurate than the old one.2. A technique for optimizing the basic circle in pipe net analyses was proposed based on the knowledge of graphic theory. The minimum basic circle could be identified with this technique, which in turn enhanced the accuracy in the...