| 摘要 |
PURPOSE:To make possible the use of a catalytic gas for curing having a low b.p. and to improve mass productivity by containing casting molds formed of molding sand kneaded with a prescribed binder into a hermetic vessel and maintaining the vessel under the specific pressure than introducing the specific catalytic gas for curing into the vessel to cure the molds. CONSTITUTION:The casting molds is formed of the molding sand formed of refractories kneaded with a phenolic resin and polyisocyanate binder. The molds A-D are contained into the hermetic vessel 1 and a vacuum pump 16 is run to maintain the inside of a hermetic chamber 5 under <=250Torr pressure. The prescribed amt. of the catalytic gas for curing consisting of gaseous amine or gaseous ammonia is then introduced into the chamber 5 from a receiver tank 7 to cure the sand (d). A valve 14 is opened and the pump 16 is operated to discharge the catalytic gas from the hermetic chamber inside. The amt. pressure is restored in the chamber 5 by opening a valve 20 and the molds A-D are taken out by rising a cap body 2. |
