| 摘要 |
PURPOSE:To eliminate large casting flashes and to improve the quality of a casting by adjusting the suction pressure in an upper casting mold to the pressure smaller than the suction pressure in a lower casting mold and executing casting while preventing deformation of the mold mating surfaces at the peripheral edge of the cavity. CONSTITUTION:The open surfaces of flask bodies 1, 2 are coated with shielding sheets 12, 12. The upper casting mold M1 and the lower casting mold M2 which are hermetically sealed with internal heat insulating packing materials 11, 11 are formed. The upper and lower molds M1, M2 are mated and the cavity 13 is formed between both molds. A molten metal is thereafter poured into the cavity 13 by using the sprue 14 and vent hole 15 of the mold M1. The suction pressure in the mold M1 is acted smaller than the suction pressure in the mold M2 until the molten metal solidifies. More specifically, the downward pressure is always acted on the bottom surface of the mold M1 by adjusting the difference in the internal pressure between the upper and lower molds M1, M2, the own weight of the material 11 in the mold M1 and the pressure reducing power thereof, by which the mold mating surfaces P1, P2 of the molds M1, M2 are brought into tight contact with each other without space. The generation of a wedge-shaped space between the surfaces P1 and P2 is thus obviated and the generation of the flashes is prevented. |
