| 摘要 |
PURPOSE:To decrease the loss of a refrigerant by evacuating and sucking the inside of a casting mold through the fine holes of a pattern and spraying liquid nitrogen to the surface of the upper layer of molding sand. CONSTITUTION:The many fine holes are bored to the pattern 1 and the molding sand 4 is put through the holes 2 into a molding flask 3. The inside of the flask 3 is then evacuated and sucked through an evacuating and sucking pipe 5. While the atm. air is sucked through the pipe 5, the refrigerant such as liquid nitrogen is sprayed to the upper layer of the molding sand 4. More specifically, the refrigerant is uniformly sprayed through a perforated plate 7 from a refrigerant introducing pipe 6. The freezing speed is increased by the evacuation and suction and therefore the consumption of the refrigerant such as liquid nitrogen is remarkably reduced. The use of low-temp. gaseous flow is also possible in place of spraying the liquid nitrogen. The loss of the refrigerant is considerably decreased in this case as well. |
