Molten metal pressure pour furnace and metering vavle

• US 20040050525A1
• Filed: 03/05/2003
• Published: 03/18/2004
• Est. Priority Date: 09/13/2002
• Status: Active Grant

• Current Assignee: Hi-Tex Incorporated
• Original Assignee: Hi-Tex Incorporated
• Inventors: Kennedy, Gordon F., Mohler, Mark G.
• Granted Patent: US 7,279,128 B2
• Time in Patent Office: Days
• US Class Current: 164/306
• CPC Class Codes: B22D 18/04 Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould

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.

Claims

1. A pressure pour furnace for discharge of a dose of a molten metal, the pressure pour furnace comprising:

a receiving chamber for receiving the molten metal from a source of the molten metal;

a heating chamber having an at least partially open inlet connected to the receiving chamber, the heating chamber having a means for heating the molten metal to a suitable temperature;

a pressure chamber having an at least one sealing port to control a flow of the molten metal from the heating chamber to the pressure chamber;

a sealing means for insertion into, or removal from, each of the at least one sealing port to prevent the flow of the molten metal through the sealing port, or to allow the flow of the molten metal through the sealing port;

a dosing tube protruding through a dosing tube opening in a wall of the pressure chamber;

a means for providing a pressurized seal around the dosing tube opening;

a means for injecting a gas into the pressure chamber to force the molten metal in the pressure chamber out of the pressure chamber through the dosing tube; and

a means for venting the pressure chamber to atmospheric pressure.

2. The apparatus of claim 1 further comprising a means for extending and retracing the dosing tube out of and into the pressure chamber.

3. The apparatus of claim 1 wherein the means for providing a pressurized seal around the dosing tube opening comprises a bellows attached at a first end to the wall of the pressure chamber around the dosing tube opening and attached at a second end to the outside of the dosing tube.

4. The apparatus of claim 3 wherein the bellows comprises a first bellows section attached at a first end to the wall of the pressure chamber around the dosing tube opening and at a second end to a first connection around the outside of the dosing tube, and a section bellows section connected at a first end to the first connection around the outside of the dosing tube and at a second end to a second connection around the outside of the dosing tube, the second connection being near the external end of the dosing tube, wherein the first bellows section expands or contracts as the dosing tube is extended out of or retracted into the pressure chamber to maintain the pressurized seal and the second bellows section expands or contracts as the external end of the dosing tube moves away from the surface of a mold or moves towards the surface of a mold.

5. The apparatus of claim 1 wherein each one of the at least one sealing port is attached to a sealing plate, the sealing plate substantially forming the boundary wall between the pressure chamber and the heating chamber to block the flow of the molten metal from the heating chamber to the pressure chamber except through the at least one sealing port.

6. The apparatus of claim 5 wherein each of the at least one sealing port and the sealing plate are an integrally formed component.

7. The apparatus of claim 6 wherein the integrally formed component is cast from a high thermal conductivity ceramic.

8. The apparatus of claim 5 wherein the sealing means comprises a sealing element at a first end of a sealing tube, a second end of the sealing tube protruding through a sealing tube opening in a wall of the pressure chamber, and the pressure pour furnace further comprises a means for providing a pressurized seal around the sealing tube opening.

9. The apparatus of claim 8 further comprising a heating element in the sealing element to melt any molten metal frozen to the sealing tube.

10. The apparatus of claim 8 wherein the means for providing a pressurized seal around the sealing tube opening comprises a bellows attached at a first end to the wall of the pressure chamber around the sealing tube opening and attached at a second end to the outside of the sealing tube.

11. The apparatus of claim 5 wherein each of the at least one sealing port comprises a substantially conically-shaped opening having a generally vertically-oriented axial alignment, the substantially conically-shaped opening connected at its smaller diameter to a first end of a substantially cylindrically and elbow-shaped passage, a second end of the substantially cylindrically and elbow-shaped passage having a generally horizontally-oriented axial alignment, and the sealing means comprises a sealing element at a first end of a sealing tube, a second end of the sealing tube protruding through a sealing tube substantially pressure-sealed opening in a wall of the pressure chamber, the sealing means having a generally hemispherical shape for insertion into the substantially conically-shaped opening of each of the at least one sealing port.

12. The apparatus of claim 1 further comprising a means for sensing a ready level of the molten metal in the pressure chamber.

13. The apparatus of claim 12 wherein the means for sensing the ready level of the molten metal in the pressure chamber comprises a pair of separated conducting probes removably insertable into the end of the dosing tube protruding from the furnace, the ready level comprising the level of the molten metal in the dosing tube at which the molten metal completes an electrical circuit between the pair of separate conducting probes.

14. The apparatus of claim 12 wherein the means for sensing the ready level of the molten metal in the pressure chamber comprises a laser sensor disposed external to the pressure chamber, the laser sensor sensing the ready level of the molten metal in the dosing tube by time of return of a laser beam to the sensor from the surface of the molten metal in the dosing tube.

15. The apparatus of claim 12 wherein the means for sensing the ready level of the molten metal in the pressure chamber comprises a gas pressure sensing tube for sensing the pressure of the melt at a point at an end of the sensing tube in melt in the pressure chamber by adjusting the flow rate of a gas through the sensing tube so that approximately one bubble of gas per second rises through the melt from the end of the sensing tube when the melt in the pressure chamber is at the ready level.

16. The apparatus of claim 1 further comprising an immersion tube heater disposed in the pressure chamber to heat the molten metal in the pressure chamber.

17. The apparatus of claim 1 further comprising a means for drawing a vacuum above the surface of the melt in the pressure chamber when the at least one sealing port allows the flow of the molten metal through the sealing port to increase the time rate of refill of the pressure chamber.

18. The apparatus of claim 1 further comprising a means of pressurizing the molten metal in the heating chamber to increase the time rate of refill of the pressure chamber when the at least one sealing port allows the flow of the molten metal through the sealing port.

19. 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 an at least one sealing port disposed in a wall between the pressure chamber and a heating chamber of the furnace by removing a sealing element from the at least one sealing port to allow the flow of the molten metal from the heating chamber through the sealing port to the pressure chamber;

closing the at least one sealing port by inserting a sealing element into the at least one sealing port to prevent the flow of the molten metal from the heating chamber through the at least one sealing port to the pressure chamber;

substantially sealing the pressure chamber from atmospheric pressure; 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 out of a dosing tubing having one end protruding into the melt and an opposing end protruding through a dosing tube opening in a wall of the pressure chamber.

20. The method of claim 19 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 out of the dosing tubing.

21. The method of claim 19 wherein the step of opening or closing the at least one sealing port further comprises raising or lowering a sealing tube having the sealing element attached to one end, the opposing 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 attached at one end to the wall of the pressure chamber around the sealing tube opening and attached at a second end to the outside of the sealing tube.

22. The method of claim 19 further comprising the steps of extending the dosing tube to connect the end of the dosing tube external to the pressure chamber with a mold for filling, and retracting the dosing tube to withdraw the end of the dosing tube external to the pressure chamber after filling of the mold.

23. A system for providing doses of a molten metal, the system comprising:

an at least one metal melting furnace for the production of the molten metal by heating a metal charge;

an at least one molten metal pressure pour furnace comprising;

a receiving chamber for receiving the molten metal from a source of the molten metal;

a heating chamber having an at least partially open inlet connected to the receiving chamber, the heating chamber having a means for heating the molten metal to a suitable temperature;

a pressure chamber having an at least one sealing port to control a flow of the molten metal from the heating chamber to the pressure chamber;

a sealing means for insertion into, or removal from, each of the at least one sealing port to prevent the flow of the molten metal through the sealing port, or to allow the flow of the molten metal through the sealing port;

a dosing tube protruding through a dosing tube opening in a wall of the pressure chamber;

a means for providing a pressurized seal around the dosing tube opening;

a means for injecting a gas into the pressure chamber to force the molten metal in the pressure chamber out of the pressure chamber through the dosing tube; and

a means for venting the pressure chamber to atmospheric pressure; and

a launder for transferring the molten metal from the at least one metal melting furnace to the receiving chamber of the at least one molten metal pressure pour furnace.

24. The system of claim 23 further comprising an at least one metal treatment vessel, each of the at least one metal treatment vessel disposed in the launder between the at least one metal melting furnace and the at least one molten metal pressure pour furnace.

25. The system of claim 23 wherein at least one of the at least one molten metal pressure pour furnace further comprises a means for extending and retracing the dosing tube out of and into the pressure chamber.

26. The system of claim 23 wherein the means for providing a pressurized seal around the dosing tube opening comprises a bellows attached at a first end to the wall of the pressure chamber around the dosing tube opening and attached at the second end to the outside of the dosing tube.

27. The system of claim 23 wherein each one of the at least one sealing port is attached to a sealing plate, the sealing plate substantially forming the boundary wall between the pressure chamber and the heating chamber to block the flow of the molten metal from the heating chamber to the pressure chamber except through the at least one sealing port.

28. The system of claim 27 wherein the sealing means comprises a sealing element at a first end of a sealing tube, a second end of the sealing tube protruding through a sealing tube opening in a wall of the pressure chamber, and the at least one molten metal pressure pour furnace further comprises a means for providing a pressurized seal around the sealing tube opening.

29. The system of claim 28 wherein the means for providing a pressurized seal around the sealing tube opening comprises a bellows attached at a first end to the wall of the pressure chamber around the sealing tube opening and attached at a second end to the outside of the sealing tube.

30. The system of claim 27 wherein each of the at least one sealing port comprises a substantially conically-shaped opening having a generally vertically-oriented axial alignment, the substantially conically-shaped opening connected at its smaller diameter to a first end of a substantially cylindrically and elbow-shaped passage, a second end of the substantially cylindrically and elbow-shaped passage having a generally horizontally-oriented axial alignment, and the sealing means comprises a sealing element at a first end of a sealing tube, a second end of the sealing tube protruding through a sealing tube substantially pressure-sealed opening in a wall of the pressure chamber, the sealing means having a generally hemispherical shape for insertion into the substantially conically-shaped opening of each of the at least one sealing port.

31. A method of providing doses 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 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 an at least one sealing port disposed in a wall between the pressure chamber and a heating chamber of the at least one molten metal pressure pour furnace by removing a sealing element from the at least one sealing port to allow the flow of the molten metal from the heating chamber through the sealing port to the pressure chamber;

closing the at least one sealing port by inserting a sealing element into the at least one sealing port to prevent the flow of the molten metal from the heating chamber through the at least one sealing port to the pressure chamber;

substantially sealing the pressure chamber from atmospheric pressure; 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 out of a dosing tubing having one end protruding into the melt and an opposing end protruding through a dosing tube opening in a wall of the pressure chamber.

32. The method of claim 31 wherein the step of opening or closing the at least one sealing port further comprises raising or lowering a sealing tube having the sealing element attached to one end, the opposing end of the sealing tube protruding through a sealing tube opening in a wall of the pressure chamber, the sealing tube opening pressure-sealed with a bellows attached at one end to the wall of the pressure chamber around the sealing tube opening and attached at a second end to the outside of the sealing tube.

33. The method of claim 31 further comprising the steps of extending the dosing tube to connect the end of the dosing tube external to the pressure chamber with a mold for filling, and retracting the dosing tube to withdraw the end of the dosing tube external to the pressure chamber from the mold after filing of the mold.

34. A metering valve for controlling a flow of a molten metal between a first molten metal containing component and a second molten metal containing component, the metering valve comprising:

a sealing plate substantially forming the boundary wall between the first molten metal containing component and the second molten metal containing component to block the flow of the molten metal between the first and the second molten metal containing components;

a sealing port disposed in the sealing plate to allow the flow of the molten metal between the first and the second molten metal containing components through the sealing port; and

a sealing means comprising a sealing element at a first end of a sealing tube, the sealing means inserted in the sealing port to prevent the flow of the molten metal between the first and the second molten metal containing components.

35. The metering valve of claim 34 wherein the sealing port comprises a substantially conically-shaped opening having a generally vertically-oriented axial alignment, the substantially conically-shaped opening connected at its smaller diameter to a first end of a substantially cylindrically and elbow-shaped passage, a second end of the substantially cylindrically and elbow-shaped passage having a generally horizontally-oriented axial alignment, and the sealing element having a generally hemispherical shape for insertion into the substantially conically-shaped opening of the sealing port.

36. A method of controlling a flow of a molten metal between a first molten metal containing component and a second molten metal containing component, the method comprising the steps of:

providing a sealing plate between the first molten metal containing component and the second molten metal component to block the flow of the molten metal between the first and the second molten metal containing components;

providing a sealing port in the sealing plate to allow the flow of the molten metal between the first and the second molten metal containing components; and

selectively sealing the sealing port with a sealing means at a first end of a sealing tube to prevent the flow of the molten metal between the first and the second molten metal containing components.

37. The method of claim 36 wherein the step of providing a sealing port further comprises providing a substantially conically-shaped opening in the sealing port, the conically-shaped opening having a generally vertically-oriented axial alignment, the substantially conically-shaped opening connected at its smaller diameter to a first end of a substantially cylindrically and elbow-shaped passage, a second end of the substantially cylindrically and elbow-shaped passage having a generally horizontally-oriented axial alignment, and the sealing element having a generally hemispherical shape for insertion into the substantially conically-shaped opening of the sealing port.

38. A metering valve for controlling a flow of a molten metal from a supply of a molten metal to a pressure chamber of a molten metal pressure pour furnace, the metering valve comprising:

a sealing plate substantially forming the boundary wall between the supply of the molten metal and the pressure chamber to block the flow of the molten metal from the supply of the molten metal to the pressure chamber;

a sealing port disposed in the sealing plate to allow the flow of the molten metal from the supply of the molten metal to the pressure chamber through the sealing port, the sealing port connected to the interior of the pressure chamber; and

a sealing means comprising a sealing element at a first end of a sealing tube, the sealing means inserted in the sealing port to prevent flow of the molten metal from the supply of the molten metal to the pressure chamber.

39. The metering valve of claim 38 wherein the sealing port comprises a substantially conically-shaped opening having a generally vertically-oriented axial alignment, the substantially conically-shaped opening connected at its smaller diameter to a first end of a substantially cylindrically and elbow-shaped passage, a second end of the substantially cylindrically and elbow-shaped passage having a generally horizontally-oriented axial alignment, and the sealing elemnt having a generally hemispherical shape for insertion into the substantially conically-shaped opening of the sealing port.

40. A method of controlling a flow of a molten metal from a supply of a molten metal to a pressure chamber of a molten metal pressure pour furnace, the method comprising the steps of:

providing a sealing plate between the supply of the molten metal and the pressure chamber;

providing a sealing port in the sealing plate, the outlet sealing port connected to the interior of the pressure chamber to allow the flow of the molten metal from the supply of the molten metal to the pressure chamber; and

selectively sealing the sealing port with a sealing means at a first end of a sealing tube to prevent the flow of the molten metal from the supply of the molten metal to the pressure chamber.

41. The method of claim 40 wherein the step of providing the sealing port further comprises providing a substantially conically-shaped opening in the sealing port, the conically-shaped opening having a generally vertically-oriented axial alignment, the substantially conically-shaped opening connected at its smaller diameter to a first end of a substantially cylindrically and elbow-shaped passage, a second end of the substantially cylindrically and elbow-shaped passage having a generally horizontally-oriented axial alignment, and the sealing element having a generally hemispherical shape for insertion into the substantially conically-shaped opening of the sealing port.

42. A metering valve for controlling a flow of a molten metal from a supply of molten metal to the pressure chamber of a molten metal pressure pour furnace, the metering valve comprising:

a double metering valve chamber;

an inlet sealing port disposed in a wall of the double metering valve chamber to allow the flow of the molten metal from the supply of the molten metal into the double metering valve chamber;

an inlet sealing means comprising an inlet sealing element at a first end of an inlet sealing tube, the inlet sealing means inserted in the inlet sealing port to prevent the flow of the molten metal from the supply of molten metal into the double metering valve chamber;

an outlet sealing port disposed in the wall of the double metering valve chamber to allow the flow of the molten metal from the double metering valve chamber into the pressure chamber, the outlet sealing port connected to the interior of the pressure chamber; and

an outlet sealing means comprising an outlet sealing element at a first end of an outlet sealing tube, the outlet sealing means inserted in the outlet sealing port to prevent flow of the molten metal from the double metering valve chamber to the pressure chamber.

43. The metering valve of claim 42 wherein the inlet sealing port and outlet sealing port each comprise a substantially conically-shaped opening having a generally vertically-oriented axial alignment, the substantially conically-shaped opening connected at its smaller diameter to a first end of a substantially cylindrically and elbow-shaped passage, a second end of the substantially cylindrically and elbow-shaped passage having a generally horizontally-oriented axial alignment, and the sealing element having a generally hemispherical shape for insertion into the substantially conically-shaped opening of the sealing port.

44. The metering valve of claim 42 further comprising a gas inlet in a wall of the double metering valve chamber to pressurize the double metering valve chamber to the same pressure as the pressure chamber.

45. A method of controlling a flow of a molten metal from a supply of molten metal to the pressure chamber of a molten metal pressure pour furnace, the method comprising the steps of:

providing a double metering valve chamber;

providing an inlet sealing port in a wall of the double metering valve chamber to allow the flow of the molten metal from the supply of molten metal into the double metering valve chamber;

selectively sealing the inlet sealing port with an inlet sealing means comprising an inlet sealing element at a first end of an inlet sealing tube to prevent the flow of the molten metal from the supply of molten metal into the double metering valve chamber;

providing an outlet sealing port in the wall of the double metering valve chamber, the outlet sealing port connected to the interior of the pressure chamber to allow the flow of the molten metal from the double metering valve chamber into the pressure chamber; and

selectively sealing the outlet sealing port with an outlet sealing means comprising an outlet sealing element at a first end of an outlet sealing tube to prevent flow of the molten metal from the double metering valve chamber to the pressure chamber.

46. The method of claim 45 wherein the steps of providing the inlet sealing port and the outlet sealing port further comprise providing for each of the inlet sealing port and the outlet sealing port a substantially conically-shaped opening in the inlet and outlet sealing ports, the substantially conically-shaped opening having a generally vertically-oriented axial alignment, the substantially conically-shaped opening connected at its smaller diameter to a first end of a substantially cylindrically and elbow-shaped passage, a second end of the substantially cylindrically and elbow-shaped passage having a generally horizontally-oriented axial alignment, and the inlet and outlet sealing elements having a generally hemispherical shape for insertion into the substantially conically-shaped opening of the inlet and outlet sealing ports, respectively.

47. The method of claim 45 further comprising the step of injecting a gas at a pressure that is the same as the gas pressure in the pressure chamber.