| 摘要 |
PURPOSE:To cast a casting having good quality with a low degree of pressure reduction by bringing the lower sprues of a sand mold into contact with the molten metal surface, immersing a weight in the molten metal to rise the molten metal surface and acting the reduced pressure on the top of the casting mold thereby filling the molten metal into the casting mold. CONSTITUTION:The bottom ends of sprues 20, 20a in the lower part of a sand mold 1 consisting of a top mold 2 and a bottom mold 3 is brought into contact with the top surface of a molten metal 15. A weight 16 for lifting the molten metal surface is then lowered and is immersed into the molten metal 15 to rise the molten metal surface; at the same time, the inside of the pressure reducing chamber of a means 4 for holding the mold 1 is evacuated by a vacuum generator (not shown) connecting to a pipe 10 to suck up the metal 15 through sprues 20, 20a and to fill the metal 15 into a product cavity 21. The mold 1 is moved upward or the weight 16 is lifted above the molten metal surfaces to lower the molten so that the mold 1 is detached from the metal 15. |
