Analysis of liquid metal filling process in gating system of semi closed sand casting

During sand casting, under the action of gravity, the liquid metal first enters the mold cavity through the sprue, enters the transverse sprue and inner sprue, and finally enters the mold cavity of the axle housing, which is the whole process of filling the axle housing. Figure (a) is a real-time screenshot of liquid metal just filling the sprue and entering the axle housing when sand casting is started; The filling ratio of the cavity is 25.3% and the solidification fraction is 0.0%. Figure (b) reflects the beginning of the flow of the liquid metal in the axle housing when the cavity is filled. The filling ratio of the cavity is 30.6% and the solidification fraction is 0.0%; Figure (c) is a screenshot of the middle stage of liquid metal filling. The cavity filling ratio is 64% and the solidification fraction is 4%; Figure (d) is a screenshot of the later stage of filling the cavity with liquid metal. The filling ratio of the cavity is 96.3% and the solidification fraction is 12.7%.

It can be seen from the velocity field shown in the figure that during the whole filling process of the mold cavity, the flow of the molten metal in the sprue in figures (a) and (b) is very stable as a whole, the melt fills the mold cavity quickly, and there is no cut-off and isolated metal solution. When the cross-sectional area of the transverse sprue is smaller than that of the direct sprue, it plays the role of blocking the sand when the molten iron passes through during the sand casting process, which will not make the molten steel wrap the molding sand, Thus, the axle housing will not produce shrinkage cavity, sand hole and other sand casting defects, so it is judged that the scheme is better.

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