| 摘要 |
PURPOSE:To reduce the cost of molding by putting facing sand on a pattern plate in a molding flask, packing backing sand which does not contain a binder, etc. therein, evacuating the inside of the molding flask and rapping the mold. CONSTITUTION:The molding flask 5 is imposed on the pattern plate 3 enclosing the pattern 4 and a suction tube 6 is disposed therein. CO2 sand 20 is put thinly as the facing sand on the plate 3 and granular praticles (silica sand) 20 which do not contain the binder, etc. are tightly packed as the backing sand thereon. The top surface of the flask 5 is hermetically sealed with a film sheet 22 and a vacuum pump 17 is operated to evacuate the inside of the flask 5 and a suction box 1. Gaseous CO2 is then introduced into the flask 5 to cure thoroughly the sand 20 and further the gaseous CO2 introduced through the tube 6 is evacuated and sucked and thereafter the mold is rapped. The mold having the required hardness is thus obtd. without adding the binder and hardener to the sand and therefore the cost of molding is reduced. |
