LOW-PRESSURE CASTING METHOD AND HOLDING FURNACE DEVICE FOR LOW-PRESSURE CASTING

摘要

PROBLEM TO BE SOLVED: To greatly shorten a casting cycle time by reducing the pressure in a molten metal holding furnace at every ending of casting and refluxing the molten metal remaining in a stalk at a lowered temp. to the molten metal in this holding furnace. ;SOLUTION: The structure capable of reducing the pressure in the molten metal holding furnace 11 is obtd. by branching air piping 19 from a compressed air source 16 disposed at a ceiling cap 13 of the molten metal holding furnace 11 and disposing a suction pipe 21 communicating a vacuum source 20. More specifically, the suction pipe 21 branched downstream of a stop valve 17 of the air piping 19 is provided, successively from an air piping 19 side, with a discharge valve 25, a reducing stop valve 22, a pressure regulating tank 23 and a vacuum stop valve 24 which are connected to the vacuum source 20. Operation is executed by closing the stop valve 17 together with the end of casting, discharging the compressed air in the furnace from the discharge valve 25 and taking out castings from the metal molds 5, 7. The operation is carried out by the procedures of reducing the pressure in the holding furnace 11 by closing the discharge valve 25 and opening the reducing stop valve 22 during this time, lowering the molten metal in the stalk pipe 14 down to the bottom end thereof to include this molten metal into the molten metal in the holding furnace 11 and raising the temp. thereof to the required temp.;COPYRIGHT: (C)1999,JPO