Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 03, 2017 - September 06, 2017
Die-casting, which is able to cast mass production by high speed and pressure casting, cause characteristic defects by trapping air in molten metal. In this investigation, a runner shape that was not influenced by the injection speed and was able to decrease blow holes was obtained in die casting. Mold filling processes of the aluminium casting, using two types of runner shape, the basic model and the claw model, was simulated with the JSCAST. A metal flow and bubbles positions were solved numerically by a three-dimensional numerical model, based on the direct finite difference method and the Volume of Fluid method for treating the free surface. The simulation results indicated that to change runner shape was considerably effective against air volume. In the basic model under even flow condition, bubbles are densely packed in the upper and lower portions of the cavity. However, air bubbles increase toward the upper part of the cavity under two steps condition. On the other hand, in the claw model under both conditions, massive bubbles were found in the upper part of the cavity, and it was confirmed that fine bubbles are distributed over a wide range. It was also confirmed that the amount of bubbles decreased by about 38.5% depending on the difference in injection conditions of the basic model, however the amount of bubbles was reduced by about 73.1% depending on the difference in shape. In other words, we confirmed that the mold method can reduce about 56.3% than the velocity method.
