| 摘要 |
PURPOSE:To cast a thin walled member having an intricate shape precisely by performing vacuum casting then pressure casting by using a water soluble casting mold which is produced from gypsum and hydrate of magnesium sulfate and removing the mold with water after the casting. CONSTITUTION:Hemihydrate gypsum and magnesium sulfate are mixed at about 3:2 ratio, and a powdery and granular refractory material and water are added thereto to prepare a slurry. The slurry is cast into a pattern and is solidified, whereby a molding is obtained. The molding is dried primarily at <=120 deg.C and is then dried secondarily at >=270 deg.C to remove crystal water. A water-soluble casting mold having high mechanical strength and having a dense layer consisting of the fine crystal particles of magnesium sulfate in the surface layer is thus obtained. Such mold 13 is installed in the case 2 of a precision casting device 1 and the inside is evacuated with a vacuum pump 10, whereafter molten metal M is charged into the cavity 15 and is cast under pressure by a compressed air source 8 successively. The mold 13 is dipped and dissolved in water upon solidification of the metal M whereby the casting which is a product is obtained. |
