Apparatus for and a method of rapidly discharging a molten metal from its supply system of a pressurized holding furnace

Claim 1

A method of rapidly discharging a molten metal from the supply system associated with a pressurized holding furnace which supplies molten metal to the feeding section of a die cast machine, said pressurized furnace including (1) a pressure chamber having an inlet valve and a discharge valve for a pressure gas and (2) an open feeding chamber communicating with said pressure chamber at a level below the level of the molten metal in the pressure chamber, said pressure chamber being pressurizable to maintain a constant molten metal level in said feeding chamber, said supply system including a delivery pump operatively connected between a suction pipe and a delivery pipe, said delivery pipe extending upward from the level of said suction pipe and said delivery pump and being connected adjacent its upper end to the feeding section of said die cast machine which is above the level of molten metal in said feeding chamber. said method comprising the steps of: connecting the end of said suction pipe remote from said delivery pump to said feeding chamber at a level below the level at which said molten metal is maintained in said feeding chamber when said pressure chamber is pressurized, but above the level to which said molten metal falls in said feeding chamber when said pressure chamber is depressurized; pressurizing said pressure chamber so that when said delivery pump is not operating, the molten metal level in said supply system is above the level of said delivery pump but below the level of the feeding section of said die cast machine; operating said delivery pump while said pressure chamber is pressurized to cause the molten metal level in said supply system to rise to the level of the feeding section of said die cast machine; and opening said discharge valve to depressurize said pressure chamber so that the molten metal level in said feeding chamber falls below the level of said end of said suction pipe and the molten metal in said supply system flows back into said feeding chamber.

Claim 2

A method of rapidly discharging a molten metal from the supply system associated with a pressurized holding furnace which supplies molten metal to the feeding section of a die cast machine, said pressurized furnace including (1) a pressure chamber having an inlet valve and a discharge valve for a pressure gas and (2) an open feeding chamber communicating with said pressure chamber at a level below the level of the molten metal in the pressure chamber, said pressure chamber being pressurizable to maintain a constant molten metal level in said feeding chamber, said supply system including a delivery pump operatively connected between a suction pipe and a delivery pipe, said delivery pipe extending upward from the level of said suction pipe and said delivery pump and being connected adjacent its upper end to the feeding section of said die cast machine which is above the level of molten metal in said feeding chamber. said method comprising the steps of: connecting the end of said suction pipe remote from said delivery pump to said feeding chamber at a level below the level at which said molten metal is maintained in said feeding chamber when said pressure chamber is pressurized, but above the level to which said molten metal falls in said feeding chamber when said pressure chamber is depressurized; pressurizing said pressure chamber so that when said delivery pump is not operating, the molten metal level in said supply system is above the level of said delivery pump but below the level of the feeding section of said die cast machine; operating said delivery pump while said pressure chamber is pressurized to cause the molten metal level in said supply system to rise to the level of the feeding section of said die cast machine; and opening said discharge valve to depressurize said pressure chamber so that the molten metal level in said feeding chamber falls below the level of said end of said suction pipe and the molten metal in said supply system flows back into said feeding chamber.

Claim 3

An apparatus for rapidly discharging a molten metal from the supply system associated with a pressurized holding furnace which supplies molten metal to the feeding section of a die cast machine, said pressurized furnace including (1) a pressure chamber having an inlet valve and a discharge valve for a pressure gas and (2) an open feeding chamber communicating with said pressure chamber at a level below the level of the molten metal in the pressure chamber, said pressure chamber being pressurizable to maintain a constant molten metal level in said feeding chamber, said supply system including a delivery pump operatively connected between a suction pipe and a delivery pipe, said delivery pipe extending upward from the level of said suction pipe and said delivery pump and being connected adjacent its upper end to the feeding section of said die cast machine which is above the level of the molten metal in said feeding chamber, said apparatus comprising: means for connecting the end of said suction pipe remote from said delivery pump to said feeding chamber at a level below the level at which said molten metal is maintained in said feeding chamber when said pressure chamber is pressurized, but above the level to which said molten metal falls in said feeding chamber when said pressure chamber is depressurized so that when said pressure chamber is depressurized and the molten metal level in said feeding chamber consequently falls below the level of said end of said suction pipe, the molten metal in said supply system flows back into said feeding chamber.

Claim 4

An apparatus for rapidly discharging a molten metal from the supply system associated with a pressurized holding furnace which supplies molten metal to the feeding section of a die cast machine, said pressurized furnace including (1) a pressure chamber having an inlet valve and a discharge valve for a pressure gas and (2) an open feeding chamber communicating with said pressure chamber at a level below the level of the molten metal in the pressure chamber, said pressure chamber being pressurizable to maintain a constant molten metal level in said feeding chamber, said supply system including a delivery pump operatively connected between a suction pipe and a delivery pipe, said delivery pipe extending upward from the level of said suction pipe and said delivery pump and being connected adjacent its upper end to the feeding section of said die cast machine which is above the level of the molten metal in said feeding chamber, said apparatus comprising: means for connecting the end of said suction pipe remote from said delivery pump to said feeding chamber at a level below the level at which said molten metal is maintained in said feeding chamber when said pressure chamber is pressurized, but above the level to which said molten metal falls in said feeding chamber when said pressure chamber is depressurized so that when said pressure chamber is depressurized and the molten metal level in said feeding chamber consequently falls below the level of said end of said suction pipe, the molten metal in said supply system flows back into said feeding chamber.