JPS57206551A - Core holding structure in vacuum molding and vacuum casting - Google Patents

Abstract

PURPOSE:To allow easy escaping of the gases generated in a core and to prevent the generation of casting defects by forming walls that shut off core print and products on the outside circumference of the roots of the core print holding the core. CONSTITUTION:While the air in mated molds 2, 3 is sucked through air suction ports 13, 13, a mold is molded. After a core 5 is provided in the mold 3, the mold 2 is combined with said mold, and while the suction of the air is continued, molten metal is charged into a mold through a sprue and runners. Then, the molten metal is filled in product parts 4, but since the molds 2, 3 and the core 5 are put in tight contact with each other by walls 17, the molten metal cannot infiltrate spaces 8. Since the core print 6 is not enclosed by the molten metal, the combustion gases generated in the core 5 go out into the spaces 8 through the easy to pass core print 6 and enter many small holes provided beforehand to inside surface films 10, from which it can escape to the outside through the molding sand 12 then through the ports 13, 13. Therefore, the air is prevented from entering the inside of the product parts and remaining there.