| 摘要 |
PURPOSE:To mold a casting mold having sufficiently high sand packing density by constituting the rear part in the recess of a pattern of a half split pattern board into plural hollow chambers and controlling the opening and closing of an air release valve in the midway of blowing of molding sand. CONSTITUTION:When molding sand is blown in while an air release valve 11 is held closed, compressed air flows in the direction of a vent hole 6 provided in the lower position of a pattern recess 2; therefore, the molding sand moves accordingly and the sand in the lower part of the recess 2 is packed thoroughly. When the valve 11 is opened and an air release valve 12 is closed thereafter, the flow of the compressed air is changed and the molding sand in the upper position of the recess 2 is moved accordingly, whereby the packing density thereof is increased. |
