CONSTRUCTION OF CORE FOR CASTING

PURPOSE:To provide construction of a core which enables inexpensive and intricate molding without spoiling the quality of casting, by packing the sand contg. no additives and admixtures densely in a free state into a thin filmlike shell body of a resin having the inside surface of the same shape as the shape of the core for casting. CONSTITUTION:An outside shell 1 of a core is molded to the inside shape of the outside shape of a designed core, and blank material sand 6 for molding sand is packed therein to form a core 8 for casting. The core is placed through a core print part 17 in the product part 15 of a master mold 16 of a bottom mold in a bottom mold flask 10, and a master mold 14 of a top mold in a top mold flask 9 is set thereon. Both molds are so mated that a vent hole 13 face a core print part 18. The molten metal 20 charged from a shank 19 into a sprue 11 formed to the mold 15 is charged through a gate 12 to the part 14, and the shell 1 of the core 8 is burned and gasified by the heat thereof. The gases are released through the core print 18 and the hole 13. Upon solidification of the metal 20, the flasks 9, 10 are opened, and the sand of the molds 15, 16 and the sand 6 of the core 8 are stripped downward. The sprue 11 and the gate 12 are cut away, and a product 22 is obtained.