| 摘要 |
PURPOSE:To accelerate effectively collapsion of molding sand from a casting by providing a zone for accelerating the collapsion of the molding sand between a heating furnace and a cooler and maintaining said zone at the high temp. atmosphere of the oxygen concn. higher than the oxygen concn. in the heating furnace. CONSTITUTION:A casting product P is conveyed successively from a preheating furnace 1 to a heating furnace 2, a device 3 for accelerating collapsion of molding sand and a cooler 4. The product is heat treated continuously by a burner 6 and a turbo fan 7 in the furnace 2 and the device 3. The atmosphere of the oxygen concn. higher than the oxygen concn. of the atmosphere in the furnace 2 is provided by a heat exchanger 12 to the device 3. More specifically, the heat exchanger 12 feeds fresh air contg. about 21% oxygen through an air feed duct 15 by a fan 14 into the device 3, sucks the air in the device 3 through a duct 13 and discharges the same from a duct 16 after heat exchange with the feed air. The oxidation decomposition of the binder for the molding sand is thus accelerated and the molding sand is easily dislodged from the product P. |
