Abstract: The molding apparatus includes a table movable between an area where molding sand is fed and a mold-producing area for carrying a pattern plate on which a flask is mounted, a cylinder for vertically moving the table, a closing cover having an opening at the lower part thereof, the opening communicating with an upper opening of the flask. The closing cover has a stepped part such that the cross-sectional area of the lower part of the closing cover is smaller than that of the upper part thereof. At least one air-supply pipe communicates with the upper part of the closing cover and an air valve communicates with the air-supply pipe to introduce ambient air into the air-supply pipe. An opening is formed in an upper and side part of the closing cover for communicating with a vacuum source. A press plate is suspended in the closing cover for a vertical movement such that the press plate can be airtightly inserted into the small lower part of the closing cover.

Abstract: Molding sand (5) is fed into a space defined by a pattern plate (2) and a flask (3) mounted on the pattern plate (2), and the space is enclosed at the upper part of the flask (3) by a cover (6). The air in the enclosed space is evacuated to reduce the air pressure between the grains of the molding sand in the enclosed space to 1 Torr to 150 Torr, and then air is introduced into the enclosed space from the upper part of the space so that the pressure in the space can increase at the rate of 15 atm/s to compress the molding sand (5). The method eliminates the need for vent holes and enables the mold to be crack-free since the air flow is not reflected.

Abstract: A compressed air blowing apparatus for supplying compressed air to molding sand placed in a flask is arranged in such a manner that its compressed air reservoir tank is constituted by a surface-plate frame and a cover, the frame having a compressed-air outlet port which can be opened/closed by a sectioning device and a piston which can be vertically moved. The sectioning device is constituted by concentrically disposed large and small cylindrical members by a cover member secured to the large and small cylindrical members having air feed holes formed between the large cylindrical member and the small cylindrical member and by connecting duct for communicating the outside of the cylindrical member with the inside of the small cylindrical members.