Patent ID: 10130989

Abstract:
An opening is provided in a foam pattern, and a coating agent is applied to the opening. The coating agent applied to the opening is taken as a beam having a sectional secondary moment I (mm4), a vertical plate thickness h (mm), and a length L (mm). It is assumed that a volume of a cavity part in the foam pattern is V (mm3), a bulk density of the casting sand filling the cavity part is ρs (kg/mm3), a gravitational acceleration is g (mm/sec2), a density of the melt is ρm (kg/mm3), an angle of the opening with respect to a vertical direction is θ, and a transverse strength of the coating agent at the highest temperature during pouring of the melt is σb (MPa). A sectional shape of the opening, the angle θ of the opening, and the transverse strength σb of the coating agent are selected to satisfy the expression: σbI>V(ρm−ρs)g{(hL/2)sin θ−cos θ}.