AMENDED CLAIMS received by the International Bureau on 20 February 2006 (20.02.2006)+ statement We Claim:
1. An apparatus for casting a metal foam article from a foam of a molten metal, the apparatus comprising:
- a crucible for containing a molten metal;
- at least one mould, wherein the mould includes at least one mould cavity having the shape of said article and at least one opening for fluid communication between said crucible and said cavity;
- at least one gas injection nozzle, connected to a gas supply3 the gas injection nozzle being positioned below said mould cavity opening; and
- a flow generating means for causing said molten metal to flow from the crucible to the mould, whereby the molten metal level in said crucible is varied from a first level below the gas injection nozzle to a second level above the gas injection nozzle.
2. The apparatus of claim 1 wherein said flow generating means comprises a pressurizing means, a vacuum meansj a pump, a displacement means, gravity, or any combination thereof.
3. The apparatus of claim 2 wherein said crucible comprises a first chamber and a second chamber, wherein:
- said first and second chambers are in fluid communication with each other whereby molten metal flows between said chambers;
- said flow generating means is provided in the first chamber; and,
■ said mould and said gas injection nozzle are provided on the second chamber.
4. The apparatus of claim 3 wherein said first chamber is provided with a filling port for introducing molten metal into the first chamber,
5. The apparatus of claim 3 further including a molten metal reservoir in fluid communication with said first chamber.
6. The apparatus of claim 5 wherein said reservoir extends vertically higher than the height of the mould cavity.
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7. The apparatus of claim 6 wherein said reservoir includes a monitoring means for monitoring the level of molten metal contained therein.
8. The apparatus of claim 7 wherein said monitoring means is connected to a processor and wherein said processor controls the gas supply for said gas injection nozzle.
9. The apparatus of claim 3 wherein said second chamber includes a guide for guiding molten metal or metal foam into said mould cavity.
10. The apparatus of claim 2 wherein said pressurizing means includes a pressurized gas supply.
11. The apparatus of claim 3 wherein at least one of said chambers is provided with a mixer for stirring the molten metal.
12. The apparatus of claim 1 further including a riser tube provided in said crucible and extending through the molten metal contained in the crucible, the riser tube having an upper end opening into said mould cavity and a lower end proximal to the bottom of the crucible.
13. The apparatus of claim 12 wherein the bottom of said crucible is concavely shaped.
14. The apparatus of claim 12 wherein said pressurizing means includes a pressurized gas supply.
15. The apparatus of claim 3 wherein one or more of said crucible, first chamber, second chamber, and mould are releasably connected to each other.
16. A method of casting a metal foam article from a foam of a molten metal comprising: a) providing a crucible containing said molten metal; b) providing at least one mould having a mould cavity having the shape of said article, the mould cavity having an opening into said crucible for fluid communication therewith; c) providing at least one gas injection nozzle below said mould cavity opening; d) maintaining the level of the molten metal below said gas injection nozzle; e) raising the level of the molten metal above the gas injection nozzle;
21501411,1 25 f) injecting gas through said gas injection nozzle to generate a foam of said molten metal; g) directing said foam into said mould cavity;. h) filling said mould cavity with said foam and allowing said foam to cool; i) returning the level of said molten metal level to below the gas injection nozzle; j) removing said formed article from the mould cavity.
17, The method of claim 16 wherein said gas injection is ceased when said molten metal level is below the gas injection nozzle.
18 , The method of claim 16 wherein said step (e) includes filling said mould cavity with the molten metal.
19, The method of claim 16 wherein said step (e) comprises establishing a pressure within the crucible, said pressure being sufficient to cause the level of the molten metal to rise above the gas injection nozzle and flow into and fill said mould cavity.
20, An apparatus for casting a metal foam article from a foam of a molten metal, the apparatus comprising:
- a crucible for containing a molten metal;
- at least one mould, wherein the mould includes at least one mould cavity having the shape of said article and an opening for fluid communication between said crucible and said cavity;
- at least one gas injection nozzle, connected to a gas supply; and
- a flow generating means for causing said molten metal to flow from the crucible to the mould; wherein said crucible and mould are releasably connected together,
21 , The apparatus of claim 20 wherein said flow generating means comprises a pressurizing means, a vacuum means, a pump, a displacement means, gravity, or any combination thereof.
22, The apparatus of claim 21 wherein said crucible comprises a first chamber and a second chamber, wherein:
21501411,1 26 - said first and second chambers are in fluid communication with each other whereby molten metal flows between said chambers;
- said flow generating means is provided in the first chamber; and,
- said mould and said gas injection nozzle are provided on the second chamber.
23. The apparatus of claim 22 wherein said mould is releasably connected to said second chamber.
24. The apparatus of claim 23 wherein said first and second chambers are releasably connected together.
25. The apparatus of claim 24 wherein said mould is fluidly connected to said second chamber through a conduit.
26. The apparatus of claim 24 wherein said first and second chambers are fluidly connected through a conduit.
27. The apparatus of claim 20 wherein said mould includes multiple cavities.
28. The apparatus of claim 22 wherein said apparatus includes multiple gas injection nozzles.
29. The apparatus of claim 20 wherein said flow generating means maintains the level of molten meal between a first level below the gas injection nozzle and a second level above the gas injection nozzle.
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