Metal founding – Means to shape metallic material – Continuous or semicontinuous casting
Patent
1999-01-25
2000-10-24
Batten, Jr., J. Reed
Metal founding
Means to shape metallic material
Continuous or semicontinuous casting
164459, B22D 11041
Patent
active
061351970
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to the vertical hot-top continuous casting of metals, particularly steel.
DESCRIPTION OF THE PRIOR ART
It is known that vertical hot-top continuous casting is essentially distinguished from conventional vertical continuous casting by the fact that sitting on top of the mold body, made of copper or a copper alloy, vigorously cooled by the circulation of water and defining a passage for the metal to be cast which undergoes peripheral solidification on contact with its wall, is a feed head made of a thermally insulating refractory intended to contain, in the liquid state, a volume of cast metal delivered by the tundish placed above it (BF 2,000,365).
Thus, by virtue of a "two-material" mold of this type, it is possible for the free surface (meniscus) of the cast metal, which then lies within the feed head, to be distanced from the point where the cast metal on contact with the cold wall necessarily starts to solidify, namely the upper edge of the copper component.
Thus, the aim is to produce, by continuous casting, semifinished products of a higher quality and with high extraction rates, which are even higher than in conventional continuous casting. This is because any hydrodynamic turbulence caused by the influx of molten metal into the mold is confined within the refractory feed head so that, below it, solidification can commence and continue in a calm environment in which the cast steel progresses towards the output end of the mold without any significant velocity gradients in the section ("plug"-type flow).
It has been envisaged to design the refractory feed head itself in two superposed separate parts. An upper part--the bush--made of a refractory which is thermally very insulating, and therefore generally made of a fibrous refractory which has quite a low density in order to prevent any spurious solidification on the internal wall of the bush by the cast metal cooling when coming into contact with it, and a lower part, of smaller size and internally aligned with the mold body--the annulus--made of a compact refractory, and therefore having good mechanical strength so as to withstand the mechanical erosion caused by the proximity of the tip of incipient solidification on the upper edge of the copper body in contact with the end of the feed head. An example of a compact refractory which may be suitable for this purpose is SiAlON (or Sialon.RTM.).
Other materials may also be suitable, but they all have the drawback of being expensive to use since, although very strong, they end up by being worn away, which means that the used annulus has to be replaced by a new annulus after a relatively short period of time.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a solution which allows the working life of a refractory annulus of this type to be very substantially extended so as to make the running costs associated with renewing this annulus in a hot-top continuous casting machine reasonable.
For this purpose, the subject of the invention is a two-material mold for the vertical hot-top continuous casting of metals, such as steel, comprising a metal body (made of copper or copper alloy), which is vigorously cooled and defines a passage for the metal to be cast which, on contact with its internal wall, undergoes peripheral solidification, and a feed head made of a thermally insulating refractory which sits on the cooled metal body and is intended to contain, in the liquid state, the molten metal poured from a tundish placed above it, which mold is distinguished by the fact that the feed head is formed by two superposed separate refractory parts--an upper bush made of a refractory having good thermal insulation properties and a lower annulus made of a refractory material having good mechanical strength properties and internally aligned with the mold body--and that the annulus is crimped into a reinforcing means whose height is less than that of the annulus.
When casting long products, which will be the sole case considered below, thi
REFERENCES:
patent: 3381741 (1968-05-01), Gardner
Jolivet Jean-Marc
Perrin Eric
Salaris Cosimo
Spiquel Jacques
Ascometal
Batten, Jr. J. Reed
Cole Thomas W.
Societe Anonyme Des Forges et Acieries de Dilling
Sogepass
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