Continuous casting mold for the vertical casting of metals

Details Continuous casting mold for the vertical casting of metals Continuous casting mold for the vertical casting of metals

1999-01-22

2000-04-18

Batten, Jr., J. Reed

Metal founding

Means providing inert or reducing atmosphere

In continuous casting apparatus

164416, 164418, B22D 11041, B22D 11053, B22D 11059

Patent

active

060503246

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to the continuous casting of metals, especially of steel. It relates more specifically to the so-called technique of "vertical hot-top continuous casting".


PRIOR ART

The first articles on this technique seem already to have been published toward the end of the sixties, a good example of which is document FR-A-2,000,365. Since then, it has become distinguished from conventional vertical continuous casting, very widely practiced at the present time throughout the world, essentially by the fact that sitting on top of the "active" component of the mold, namely the vigorously cooled tubular metal component in which the desired solidification of the cast metal starts and grows, is a thermally insulating feed head intended to contain, in the liquid state, the molten metal delivered by a tundish located above it.
This "active" component is conventionally a tube made from a single piece (for casting billets or blooms) or made from plates joined together (for casting slabs or large blooms). It is made of copper, or a copper alloy, and vigorously cooled by intense circulation of water against its external wall so as to be able to extract a sufficient heat flux to ensure that the molten metal solidifies on contact with its internal wall.
These two contiguous components define a continuous sizing passage for the cast metal which enters it in the molten state via the top and leaves it via the bottom in the form of a solid shell deriving from the peripheral solidification of the cast metal on contact with the cold wall of the mold body and which contains a still-liquid core. Solidification then continues to its conclusion in the lower part of the casting machine by means of spray units.
The basic advantage sought in vertical hot-top continuous casting resides in the fact that it is thus possible for the free surface (the "meniscus") of the metal poured into the mold, which free surface then lies within the refractory feed head, to be distanced from the point where the cast metal on first coming into contact with the cold wall of the mold body necessarily starts to solidify, i.e. in the region of the edge of the upper end of the copper component.
Thus, the intention is to cast semi-finished products of superior metallurgical quality continuously at high extraction rates, which are even higher than in conventional continuous casting, since the solidification process is then initiated in a hydrodynamically calm environment, any turbulence, especially that caused by the influx of molten metal, remaining confined within the buffer volume provided by the refractory feed head.
Moreover, this technique has no significant drawbacks with respect to conventional continuous casting, from which it may be seen as a development, and therefore involves no major technological step. It is possible, without any particular difficulty, to convert a conventional continuous casting machine into a hot-top continuous casting machine since in particular the tundish, although placed at a short distance above it, does not remain rigidly connected to the mold. However, although the first publications on the hot-top continuous casting of steel are contemporaneous with the introduction on an industrial scale of vertical continuous casting, which has undergone the extraordinary amount of development which is known about (more than 80% of steel production world-wide is currently produced by continuous casting), at the present time vertical hot-top continuous casting still remains in the research stage of the process of applying the technology on an industrial scale.
Trials performed by the Applicants have exposed a major problem which may explain this lack of acceptance from an industrial standpoint, namely the instability over time of the geometry at the "cooled copper component/refractory feed head" interface. This is because this geometry suffers because of deformation of the upper end of the cooled component.
In conventional vertical continuous casting, such deformation is caused by adventitio

REFERENCES:
patent: 3381741 (1968-05-01), Gardner
patent: 3612151 (1971-10-01), Harrington et al.
patent: 5325910 (1994-07-01), Schneider et al.

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