DIFFERENT PRESSURE AND ANTIGRAVITY- CASTING FOR MOLTEN METAL WITH ALLOY ADDITIVE OF ESCAPING PROPERTY

摘要

PURPOSE: To provide differential pressure countergravity casting of a molten metal contg. a fugative alloyant, more particularly magnesium, which is liable to be subjected to the loss from the molten metal, more particularly nodular cast iron. CONSTITUTION: A mold 6 having a mold cavity 14 and a sprue 16 communicating therewith is immersed into a molten metal pool 3 on a lower side. While the mold is held immersed in the mold pool, the differential pressure sufficient for sucking the molten metal upward into the mold cavity described above through the sprue is applied via a vacuum source 23 or a vacuum chamber 22 between the mold cavity and the pool and treating material pellets 50 contg. the alloyant are arranged in the lower portion of the mold of the time. The treating materials replenish and maintain an effective concn. by coming into contact with the molten metal on the lower side, thereby compensating the loss of the alloyant from the molten metal with lapse of time. The mold is produced by forming a casting mold shaping body from a flexible mixture composed of a granular molding material and a hardenable binder, inserting an alloyant source partially the mold surface, preferably a rear surface 10a, while the mixture is soft, and curing the binder.