MOLDING METHOD OF SAND MOLD USING FOAM SAND, MOLDING METAL MOLD AND SAND MOLD

摘要

PROBLEM TO BE SOLVED: To prevent molten metal from flowing into a sand mold from a fragile part or a hollow part of a blow-in port of the sand mold using foam sand which is exposed to a surface of a product part.SOLUTION: A cavity and a filling port of a metal mold are constituted so that a dimension a between cross points of two points when the dimension a between the cross points of the two points of a linear line passing through a cross section at a boundary part between the cavity and the filling port of the metal mold and a contour line of the cross section becomes maximum, and a wall thickness dimension d of a portion of a product part 22 formed of the cavity of the metal mold at which the blow-in port 24 protrudes satisfy a relationship of 2/3a1/3d, that is, ad/2. In a state that the blow-in port 24 is removed from the product part 22 of the sand mold 20, a hardened layer 22H having a necessary and sufficient thickness is secured at a portion of the product part 22 at which the blow-in port 24 is removed. Accordingly, it can be avoided that molten metal flows into a fragile part or a hollow part 22S of the product part 22 at casting.