Shell mold for casting a cylindrical product, apparatus for molding the shell mold, and casting method using the shell mold

摘要

A shell mold includes a plurality of sleeve forming portions. Of the sleeve forming portions, at least an endmost sleeve forming portion located adjacent to a subrunner portion has a modified shape for compensating for deformation of cast sleeves caused by solidification and contraction of molten metal. A shell molding apparatus includes an upper die and a lower die which constitute a die set for molding a shell mold. The lower die is composed of shell molding inserts, each having the shape of a halved cylinder, spiny insert receiving recesses formed in the shell molding inserts, and spiny inserts retractably provided in the spiny insert receiving recesses. In a casting method using a shell mold, many protrusions of a spiny insert are reversely copied to the inner surface of a halved shell mold at the undercut portion of the inner surface, thereby forming many depressions at the undercut portion. The halved shell mold is parted from the lower die. A plurality of bore forming cores are disposed in the halved shell mold. The halved shell mold and another halved shell mold are engaged with each other, thereby forming a shell mold for casting. Casting is performed using the thus formed shell mold.