Abstract: A molding chamber (7) accommodating pattern plates (24, 25) is supplied by a steam of air with sand mixture delivered in a direction parallel to the pattern plates (24, 25). After a time delay relative to the start of the sand delivery operation, and sand mixture is preliminarily compacted by delivering a stream of compressed air directly into the molding chamber in a direction parallel to the pattern plates, the delivery of compressed air being continued within a period of time equal to 5 to 30 percent of the duration of the sand mixture delivery operation. As a result of the delivery of compressed air, the delivery of the sand mixture is retarded and even interrupted. The stream of compressed air diverts the sand mixture in the molding chamber towards the pattern plates, thus providing a better filling of narrow deep hollows on pattern surfaces and preliminary compaction of the sand mixture. The sand delivery operation is completed after the end of the preliminary compaction.

Abstract: The apparatus includes a housing 1 accommodating inner and outer tubes 2 and 4, respectively, arranged concentrically relative to each other. Lower ends of the tubes 2 and 4 are connected by a flange 15 to a disk-type feeder 14 the flange and feeder having holes 13 and 21 through which the interior of a heating chamber 9 confined between the outer wall of the outer tube 4 and inner wall of the housing 1 communicates with interior 17 of the inner tube 2 and with the interior of the drying chamber 6 confined between the outer wall of the inner tube 2 and inner wall of the outer tube 4. Communicating with the drying chamber 6 are a charging hopper 7 and a discharging means 8 occupying the bottom part of the apparatus. Disposed in the wall of the housing 1 between the flange 15 and worm 5 of the outer tube 4 is a furnace 11 having a burner 12 and communicating with the interior of the heating chamber 9. In addition, the heating chamber 9 communicates with an exhaust pipe 10 of a suction means.