| 摘要 |
PURPOSE:To prevent intrusion of gas at the time of casting and to produce a casting having no blowhole defects by providing a coating layer consisting of refractory material powder over the entire surface of a casting mold consisting of an air permeable material except the suction part thereof and acting pressure reduction only on the suction part. CONSTITUTION:The casting mold having the cavity part 3 is formed of a cope 1 and a drag 2 consisting of the material having air permeability such as shell mold for casting. Such casting mold is immersed into a molten metal 7 and a pressure reducing device 10 is lowered from above to reduce the pressure in the space part 11 through the suction port 12 by which the molten metal is sucked through a runner 4 into the cavity part 3 and is thus cast. A mold coating material consisting of the refractory material powder (low carbon of magnesia or zirconia system) is previously coated on the outside peripheral face 8 which is not immersed in the molten metal 7 and the rear surface 9 of the mold having irregular reuggedness to about 1mm thickness. Intrusion of the gas into the molten metal at the time of casting is thereby prevented and the defectless casting is obtd.
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