Molten Metal Pressure Pour Furnace

Abstract

An apparatus and process are provided for discharging a dose of a molten metal from a pressure pour furnace. A heating chamber of the furnace is used to keep the molten metal at a selected temperature. A sealing port between the heating chamber and a pressure chamber allows selectively filling of the pressure chamber with molten metal from the heating chamber by inserting or removing a sealing means from the sealing port. The sealing means inserted in the sealing port also provides a means for preventing back flow of the molten metal to the heating chamber when the pressure chamber is pressurized. Differential pressure sensing of the pressure of the molten metal in the pressure chamber and the pressure of the pressurizing gas in the pressure chamber can optionally be used to achieve an accurate measured discharge from the pressure chamber as the level of molten metal decreases from repeated discharges of doses from the furnace. The sealing plate in which the sealing port is disposed and the sealing means selectively inserted or removed from the sealing port can be used as a metering valve between two molten metal containing components such as a launder and a pressure chamber of a pressure pour furnace.

1 . A method of discharging a dose of a molten metal from a pressure pour furnace, the method comprising the steps of:
 venting a pressure chamber of the furnace to atmospheric pressure;   opening a sealing port disposed in a wall between the pressure chamber and a heating chamber of the furnace by removing a sealing element from the sealing port to allow the flow of the molten metal from the heating chamber through the sealing port to the pressure chamber;   closing the sealing port by inserting the sealing element into the sealing port to prevent the flow of the molten metal from the heating chamber through the sealing port to the pressure chamber;   substantially sealing the pressure chamber from atmospheric pressure;   providing a dosing tube through a dosing tube opening in the pressure chamber, the dosing tube comprising a first and second contiguous sections, the first section disposed exterior to the pressure chamber and terminating in a dosing tube pour end, the second section disposed interior to the pressure chamber and terminating in a dosing tube supply end;   extending the dosing tube pour end away from the pressure chamber; and   injecting a gas into the volume above the surface of the molten metal in the pressure chamber to force an at least one dose of the molten metal through the dosing tube and out of the dosing tube pour end.   
   
   
       2 . The method of  claim 1  further comprising the step of injecting the gas above the surface of the molten metal in the pressure chamber to a ready level prior to the step of injecting the gas into the volume above the surface of the molten metal in the pressure chamber to force an at least one dose of molten metal through the dosing tube and out of the dosing tube pour end. 
   
   
       3 . The method of  claim 1  wherein the steps of opening or closing the sealing port further comprises raising or lowering a sealing tube having a first and second opposing ends, the sealing element attached to the first end of the sealing tube, and the second end of the sealing tube protruding through a sealing tube opening in the wall of the pressure chamber, the sealing tube opening pressure-sealed by a bellows having a first and second opposing ends, the first end of the bellows attached to the wall of the pressure chamber around the sealing tube opening and the send end of the bellows attached around the sealing tube external to the pressure chamber. 
   
   
       4 . The method of  claim 1  further comprising the steps of forming the sealing port from the combination of a cylindrically-shaped elbow passage and a conically-shaped passage, and orienting the elbow passage so that the molten metal flows through the elbow passage in a substantially horizontal path out of the heating chamber and a substantially vertical path into the conically-shaped passage in the pressure chamber when the sealing element is removed from the conically-shaped passage. 
   
   
       5 . The method of  claim 1  wherein the step of extending the dosing tube pour end away from the pressure chamber comprises the steps of extending a first partial section of the first section of the dosing tube from the remainder of the first section of the dosing tube, the first partial section of the first section of the dosing tube terminating in the dosing tube pour end, and providing a bellows sealing element around the first partial section and the remainder of the first section of the dosing tube. 
   
   
       6 . The method of  claim 1  wherein the step of extending the dosing tube pour end away from the pressure chamber comprises extending the first and second sections of the dosing tube, and providing a bellows sealing element around the first section and the dosing tube opening in the pressure chamber. 
   
   
       7 . A method of providing a dose of a molten metal, the method comprising the steps of:
 producing the molten metal by heating a metal charge in an at least one metal melting furnace;   supplying the molten metal to a heating chamber of an at least one molten metal pressure pour furnace by a launder;   venting a pressure chamber of the at least one molten metal pressure pour furnace to atmospheric pressure;   opening a sealing port disposed in a wall between the pressure chamber and the heating chamber of the at least one molten metal pressure pour furnace by removing a sealing element from the sealing port to allow the flow of the molten metal from the heating chamber through the sealing port to the pressure chamber;   closing the sealing port by inserting a sealing element into the sealing port to prevent the flow of the molten metal from the heating chamber through the sealing port to the pressure chamber;   substantially sealing the pressure chamber from atmospheric pressure;   providing a dosing tube through a dosing tube opening in the pressure chamber, the dosing tube comprising a first and second contiguous sections, the first section disposed exterior to the pressure chamber and terminating in a dosing tube pour end, the second section disposed interior to the pressure chamber and terminating in a dosing tube supply end;   extending the dosing tube pour end away from the pressure chamber; and   injecting a gas into the volume above the surface of the molten metal in the pressure chamber to force an at least one dose of the molten metal through the dosing tube and out of the dosing tube pour end.   
   
   
       8 . The method of  claim 7  further comprising the steps of forming the sealing port from the combination of a cylindrically-shaped elbow passage and a conically-shaped passage and orienting the elbow passage so that the molten metal flows through the elbow passage in a substantially horizontal path out of the heating chamber and a substantially vertical path into the conically-shaped passage into the pressure chamber when the sealing element is removed from the conically-shaped passage. 
   
   
       9 . The method of  claim 7  further comprising the step of injecting the gas above the surface of the molten metal in the pressure chamber to a ready level prior to the step of injecting the gas into the volume above the surface of the molten metal in the pressure chamber to force an at least one dose of molten metal through the dosing tube and out of the dosing tube pour end. 
   
   
       10 . The method of  claim 7  wherein the steps of opening or closing the sealing port further comprises raising or lowering a sealing tube having a first and second opposing ends, the sealing element attached to the first end of the sealing tube, and the second end of the sealing tube protruding through a sealing tube opening in the wall of the pressure chamber, the sealing tube opening pressure-sealed with a bellows having first and second opposing ends, the first end of the bellows attached to the wall of the pressure chamber around the sealing tube opening and the second end of the bellows attached around the sealing tube exterior to the pressure chamber. 
   
   
       11 . The method of  claim 7  wherein the step of extending the dosing tube pour end away from the pressure chamber comprises the steps of extending a first partial section of the first section of the dosing tube from the remainder of the first section of the dosing tube, the first partial section of the first section of the dosing tube terminating in the dosing tube pour end, and providing a bellows sealing element around the first partial section and the remainder of the first section of the dosing tube. 
   
   
       12 . The method of  claim 7  wherein the step of extending the dosing tube pour end away from the pressure chamber comprises extending the first and second sections of the dosing tube, and providing a bellows sealing element around the first section and the dosing tube opening in the pressure chamber. 
   
   
       13 . A method of discharging a dose of molten metal from a pressure pour furnace, the method comprising the steps of:
 venting a pressure chamber of the furnace to atmospheric pressure;   opening a sealing port disposed in a wall between the pressure chamber and a heating chamber of the furnace by removing the end of a sealing tube from an opening in the sealing port to allow the flow of the molten metal from the heating chamber through the sealing port to the pressure chamber, the opening in the sealing port disposed in the pressure chamber;   energizing a sealing tube close actuator to initiate movement of the end of the sealing tube towards the opening in the sealing port;   seating the end of the sealing tube in the opening in the sealing port to terminate flow of the molten metal from the heating chamber to the pressure chamber;   substantially sealing the pressure chamber from atmospheric pressure;   providing a dosing tube through a dosing tube opening in the pressure chamber, the dosing tube comprising a first and second contiguous sections, the first section disposed exterior to the pressure chamber and terminating in a dosing tube pour end, the second section disposed interior to the pressure chamber and terminating in a dosing tube supply end;   injecting a pour gas into the volume above the surface of the molten metal in the pressure chamber to force the molten metal into the supply end of the dosing tube;   sensing when the level of molten metal in the dosing tube has reached a ready level to regulate the pressure of the gas to maintain the level of molten metal in the dosing tube at the ready level;   indexing the sprue of a mold adjacent to the dosing tube pour end;   extending the dosing tube pour end to the sprue of the indexed mold;   injecting the pour gas into the volume above the surface of the molten metal in the pressure chamber at a mold fill profile gas injection rate to force the molten metal out of the dosing tube pour end and into the sprue of the indexed mold to fill the interior volume of the mold;   adjusting the gas injection rate to return the level of molten metal in the dosing tube to the ready level; and   retracting the dosing tube pour end from the sprue of the indexed mold.   
   
   
       14 . The method of  claim 13  further comprising the steps of forming the sealing port from the combination of a cylindrically-shaped elbow passage and a conically-shaped passage, and orienting the elbow passage so that the molten metal flows through the elbow passage in a substantially horizontal path out of the heating chamber and a substantially vertical path into the conically-shaped passage into the pressure chamber when the sealing element is removed from the conically-shaped passage. 
   
   
       15 . The method of  claim 13  further comprising the step of sensing the back force loading on the sealing tube actuator to detect blockage in the opening of the sealing port as the end of the sealing tube moves toward the sealing port. 
   
   
       16 . The method of  claim 13  wherein the step of sensing when the level of molten metal in the dosing tube has reached a ready level further comprises the step of injecting a melt pressure sensing gas into a melt pressure sensing tube having an end immersed in the molten metal in the pressure chamber to sense a melt pressure sensing gas bubble release from the immersed end of the melt pressure sensing tube corresponding to the level of molten metal in the dosing tube having reached the ready level. 
   
   
       17 . The method of  claim 13  further comprising the step of passing a stream of pressurized air across the dosing tube pour end to dislodge molten metal after retracting the dosing tube pour end opening from the sprue in the mold. 
   
   
       18 . The method of  claim 13  wherein the step of extending the dosing tube pour end away from the pressure chamber comprises the steps of extending a first partial section of the first section of the dosing tube from the remainder of the first section of the dosing tube, the first partial section of the first section of the dosing tube terminating in the dosing tube pour end, and providing a bellows sealing element around the first partial section and the remainder of the first section of the dosing tube. 
   
   
       19 . The method of  claim 13  wherein the step of extending the dosing tube pour end away from the pressure chamber comprises extending the first and second sections of the dosing tube, and providing a bellows sealing element around the first section and the dosing tube opening in the pressure chamber.