Metal founding – Process – Shaping liquid metal against a forming surface
Reexamination Certificate
1999-11-08
2001-04-10
Pyon, Harold (Department: 1722)
Metal founding
Process
Shaping liquid metal against a forming surface
C164S479000, C164S481000, C164S488000, C164S452000, C164S154800, C222S590000
Reexamination Certificate
active
06213193
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a caster including a gas delivery means to resist backflowing and freezing of molten metal to the tip of a nozzle and an associated method.
Casters for casting molten metal, such as molten aluminum, into metal products are known. Molten metal is typically introduced into the caster from a trough that is fed from a furnace. Typically, a nozzle introduces the molten metal into the mold of the caster. In a twin belt caster, the mold is formed by a pair of opposed movable belts and a pair of opposed side dams. A metal product, such as a slab, is formed in the mold by solidifying the molten metal. An example of a twin belt caster is described in U.S. Pat. No. 4,964,456.
A recurring problem with casters utilizing a nozzle is that molten metal can freeze at the nozzle tip. This freezing of molten metal at the nozzle tip causes undesirable surface qualities in the cast slab. In addition, freezing of molten metal at the nozzle tip can cause nozzle damage.
Also, despite the known devices to seal the belt to the nozzle (see, e.g., U.S. Pat. No. 4,785,873) a space can form between the nozzle and the belt, and molten metal can enter this space, and thereafter freeze to the nozzle tip.
What is needed, therefore, is a caster that includes means for resisting freezing and backflowing of molten metal to the nozzle tip. By resisting this freezing and backflowing of molten metal to the nozzle tip, a higher quality cast metal product can be produced in the caster.
SUMMARY OF THE INVENTION
The invention has met or exceeded the above-mentioned needs as well as others. The caster of the invention comprises means for defining a mold to receive molten metal therein and a nozzle for delivering the molten metal into the mold. The nozzle includes a tip. The caster further includes means for delivering a gas to a space defined by the mold defining means and the nozzle. In this way, freezing and backflowing of the molten metal near the tip is resisted.
The method of the invention includes providing a caster substantially as described above and solidifying the molten metal into a metal product in the mold of the caster. The method further comprises introducing a gas into the space defined by the nozzle and the mold defining means while the molten metal is solidifying in the mold. Once again, the introduction of the gas into the space resists freezing and backflowing of the molten metal to the tip of the nozzle.
REFERENCES:
patent: 3552478 (1971-01-01), Lauener
patent: 5967220 (1999-10-01), Lauener
Brownlee David W.
Buckwalter Charles Q.
Larex AG
Lin I.-H.
Pyon Harold
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