Patent ID: 9433999
Filing Date: 2016-09-06
CPC Classification: B22C,B22D,C21D

Claim Text:
1. A manufacturing method of a core using an inorganic binder, comprising: an original sand supplying step in which original molding sand is supplied to a muller; a mulling step in which the original molding sand is mixed and mulled with a liquid inorganic binder including water glass and mulled sand is prepared by the muller; a sand transferring step in which the mulled sand is transferred from the muller to a mulled sand hopper; a sand supplying step in which the mulled sand is supplied from the mulled sand hopper to a blowing head positioned under the mulled sand hopper; a blowing step in which the mulled sand supplied into the blowing head is blown into a core mold; a gas exhausting step in which the inside of the core mold is exhausted and depressurized; a curing step in which after the core mold is preheated, the inside of the blown core is cured and calcined; and an extracting step in which the core mold is separated and the cured core is extracted, wherein the inorganic binder includes the water glass of 40 to 70 parts by weight, nano-silica of 5 to 35 parts by weight, a Li-based water resistant additive of 0.1 to 10 parts by weight, an organic silicon compound of 0.1 to 10 parts by weight, and an anti-sand burning additive of 1 to 10 parts by weight.