Study On Dynamic Evolution Of Filling Flow Pattern Of Aluminum Alloy Die Casting

With the development of die-casting products towards thin-wall and complicated direction,the fine control of mold filling process is very important.Therefore,it is necessary to understand the flow characteristics of liquid metal in the cavity and the influence of die-casting parameters on mold-filling flow?At present,numerical simulation and water analogy are the main methods to study the flow law of liquid metal in mold filling process of die casting,but there are some differences between numerical simulation and water analogy as compared with the actual mold filling process.In this paper,the dynamic real-time characterization of mold filling process of die casting was used to observe and studied the influence of different fast injection velocity,different ingate thickness and cavity structure on mold filling process.At the same time,the numerical simulation under the same experimental conditions was compared and analyzed,and the main conclusions are drawn as follows:(1)After the liquid metal enters the mold cavity from the inate,with the increase of the filling speed,the flow of the liquid metal is not continuous,and the morphology of the flow front gradually changes from smooth circle to brokenup.Due to the wall attachment effect of the jet,the liquid metal adheres to the glass window side is filled forward,and the countersunk protruding platform and the sudden change structure of the cross section have little effect on the flow pattern at the initial stage of the filling.The existence of the through hole protruding platform changes the filling flow pattern,forces the flow to produce separated flow,and promotes the formation of voids in the process of liquid metal flow.(2)When the liquid metal is filled with the fast injection velocity of 1.5m/s,the flow front breakups earlier than that of 1.0m/s filling,and the splashing degree of the flow front is more serious in the same position.(3)The thickness of the ingate affects the flow characteristics of the molten metal.The larger the thickness of the ingate is,the less likely the liquid metal flow front is to breakup,and at the same filling distance,the degree of fragmentation and splashing at the flow front is low.At the same time,the larger the thickness of the ingate,the flow front is not easy to expand,easy to produce liquid metal accumulation.(4)When the filling velocity and the thickness of the ingate change,the numerical simulation of the filling flow trend and the location of the cavity are consistent with the actual filling process,but the fragmenting and spattering of flow front is different from the actual flow.