Fast Optimization of Injection Velocity Profile Based on Graph Theory

Abstract

Injection velocity profile is an important process parameter that affects the quality of injection-molded parts. In this paper, a fast optimization method for injection velocity profile is proposed, which aims at a constant melt-front-velocity throughout the filling stage. According to the relationship between cavity geometry and the melt-front-velocity, the ideal injection velocity is proportional to the melt-front-area. Through studying the filling behavior of molten polymer and the characteristic of 3D surface mesh model, a modified Dijkstra's algorithm is employed to predict the melt-front-area at different filling steps. Based on the predicted melt-front-area, a least square method is adopted to find out the optimum injection velocity profile by minimizing the difference of injection velocity and the ideal injection velocity. Finally, a short shot experiment and a Moldflow simulation experiment have been conducted to verify the proposed optimization method, which demonstrate that the proposed method is correct and effective.