METHOD FOR CASTING ALUMINUM ALLOY-MADE IMPELLER

• Main Authors: HONMA HIDEAKI, FURUKAWA HIROFUMI
• Format: Patent
• Language: English
• Published: 03.03.1998
• Edition: 6
• Subjects: CASTING; CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES; FOUNDRY MOULDING; PERFORMING OPERATIONS; POWDER METALLURGY; TRANSPORTING

PROBLEM TO BE SOLVED: To obtain an impeller without developing cast defect caused by misrun, etc., by inserting a heated ceramic-made vessel at the center part of the casting of the impeller and pouring molten Al alloy having different compositions from the inner part of the vessel and from the outer part of the vessel. SOLUTION: At the position of the center upper part of the impeller 20 in a mold assembled with metallic molds 5, 6 and a core 7, the heated ceramic- made vessel 8 and a stopper 9 are arranged. The molten Al alloy 2 applying degassing treatment in a ladle 1 is poured from a pouring hole 11 and reached to a prescribed molten metal surface level 23. Together with this, the molten Al alloy 4 applying the degassing treatment in a ladle 3 and having higher strength and higher ductility than these of the molten Al alloy 2 in the ladle 1, is poured to a prescribed molten metal surface level 24 in the vessel 8. The stopper 9 in the vessel is pulled up and a nozzle 10 is opened and the molten metal pressures in the outer part and the inner part of the vessel 8 are balanced. Successively, the vessel 8 is gradually risen and the molten Al alloy in the vessel 8 is shifted into the casting (the impeller product) through the nozzle 10 with the static pressure difference between the molten metals.