The discontinuity of material and the presence of a possible gap between a casting and its surrounding mold can play an important role in the solidification of the casting. Specifically, as the casting section size decreases, and total solidification time decreases, the effect of reduced heat flow created by the interface becomes more important. And the effect of a lowered heat transfer coefficient across any gap formed can become important even for thicker sectioned castings. This paper summarizes an investigation to determine interfacial heat transfer in sand castings. An experimental program was conducted to gather temperature data on industrial-sized plate castings. The temperature data obtained were used in an inverse heat conduction algorithm to determine the interfacial heat transfer coefficient history between the solidifying plate casting and the surrounding mold. Three section thicknesses were investigated (25.4mm, 12.7mm, and 6.35mm) and both resin bonded sand and green sand were considered. A special form of the inverse heat conduction problem was developed to handle the green sand case. Our results indicate that the interfacial heat transfer coefficients in resin sand attain a nearly constant value quickly for thicker sections, but can be increasing toward a constant value for a significant portion of the solidification time in thinner sections. Results for green sand indicate the magnitude of the heat transfer coefficient is similar to that in resin sand.
展开▼
