Metal founding – Means to shape metallic material – Continuous or semicontinuous casting
Reexamination Certificate
2000-09-15
2003-04-29
Elve, M. Alexandra (Department: 1725)
Metal founding
Means to shape metallic material
Continuous or semicontinuous casting
Reexamination Certificate
active
06554055
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for the horizontal continuous casting of profiles, in particular of metal strips, comprising a receptacle for the molten metal, preferably a holding furnace, an ingot mould connectable to the receptacle via a ramming frame, where the forming casting gap of said ingot mould has a refractory lining that cannot be wetted by the molten metal, and comprising an oscillation drive for the ingot mould in casting direction.
For casting metal strips in a horizontal continuous casing process, the ingot mould defining the forming casting gap is connected to a receptacle for the molten metal via a ramming frame, which receptacle either consists of a holding furnace or can be charged with the molten metal via a holding furnace. With its usually ceramic ramming compound, the ramming frame provides a refractory lining in the transition area between the receptacle and the ingot mould, so that the metallic housing of the ingot mould can detachably be connected to the receptacle in a comparatively easy way. Since advantageous continuous casting conditions require a reciprocating oscillation of the ingot mould in casting direction with respect to the casting strand in the vicinity of the casting gap, it is necessary in these known horizontal continuous casting apparatuses to provide an oscillatory support of the ingot mould together with the receptacle and to connect the, same with an oscillation drive, which not only involves a considerable constructional effort, but also control problems, as in dependence on the respective casting program an excitation of oscillations with predetermined frequencies and amplitudes must be predetermined.
SUMMARY OF THE INVENTION
It is therefore the object underlying the invention to provide an apparatus for the horizontal continuous casting of profiles as described above such that an excitation of oscillations of the ingot mould with predeterminable frequencies and amplitudes can be ensured.
This object is solved by the invention in that the ingot mould is mounted on a sliding guide associated to the receptacle and extending in the casting direction, that the oscillation drive is supported on the one hand on the receptacle and on the other hand on the ingot mould, and that in the transition area between the receptacle and the ingot mould there is provided a web of refractory fibers, which has been prestressed with a minimum pressure corresponding to the hydraulic pressure of the molten metal and consists of refractory fibers that cannot be wetted by the molten metal, to provide a seal against the molten metal.
Due to the sliding guide for the ingot mould, which is associated to the receptable and extends in the casting direction, and the oscillation drive operating between the receptacle and the ingot mould, the mass to be moved in an oscillating way is substantially restricted to the small mass of the ingot mould as compared to the receptacle, which represents an advantageous condition for a precise oscillation control with frequencies and amplitudes that can be predetermined under program control. Such oscillatory support of the ingot mould with respect to the receptacle can, however, only be effected when between the oscillating ingot mould and the stationary receptacle, in which a seal can be provided, which can withstand all mechanical, metallurgical and thermal loads during an operating period adapted to the lifetime of the ingot mould. Such a seal will also include a fibrous web, which is prestressed with a minimum pressure corresponding to the hydraulic pressure of the molten metal, so that this fibrous web cannot be urged away from a sealing surface by the molten metal. This prestressing of the fibrous web thus ensures the close abutment of the web against the sealing surfaces, where the inherent elasticity of the web easily provides for the absorption of the oscillations of the ingot mould when a corresponding dimensioning of the fibrous web is ensured. The fibers of such web should be refractory and must not be wetted by the molten metal. These conditions are advantageously satisfied by carbon fibers, although other fibrous materials may also be used.
The fact that the web fibers cannot be wetted by the molten metal does, however, not exclude a penetration of the molten metal into the pores between the fibers of the web, just as prestressing the fibrous web cannot prevent a penetration of the molten metal. It is therefore recommended to apply a protective gas onto the fibrous web under a minimum pressure which corresponds to the hydraulic pressure of the molten metal, so that the protective gas filling the pores of the fibrous web effectively prevents the molten metal from penetrating into the fibrous web. The additional effort required for applying the protective gas onto the fibrous web can be kept small in view of the fact that it is common practice to also apply such protective gas onto the ramming compound of the ramming frame.
For the arrangement of the fibrous web as a seal against the molten metal, two advantageous solutions are provided. In accordance with the one solution, the ingot mould fixedly connected with the ramming frame can resiliently be braced against the receptacle by clamping the fibrous web between the ramming frame and an ingot mould connecting surface of the receptacle. In this case, the elastic properties of the fibrous web are particularly utilized, because the fibrous web is arranged substantially vertical with respect to the oscillating direction of the ingot mould. The resilient prestressing of the fibrous web is achieved by means of the resilient bracing of the ingot mould against the receptacle, where the oscillation drive must operate against this spring load.
According to the other possible solution, the ingot mould is movably supported with respect to the ramming frame fixedly connected with the receptacle, where in the fibrous web, which surrounds the lining of the casting gap associated to the ingot mould and engaging in the ramming frame, is pressurized by the ramming compound of the ramming frame and urged against the lining of the casting gap. The lining of the casting gap is thus oscillatingly reciprocated inside the fibrous web, which surrounds the same and is retained by the ramming frame, where between the lining and the fibrous web a sliding friction is produced. The prestressing of the fibrous web by means of the ramming compound of the ramming frame in connection with the inherent elasticity of the fibrous web again effects a safe abutment of the fibrous web against the sealing surface, which in this embodiment is formed by the lining of the casting gap.
It can thus be seen that by prestressing the fibrous web the oscillating ingot mould can easily be sealed against the receptacle by utilizing the inherent elasticity of the fibrous web, so that the advantage of an ingot mould oscillating with respect to a stationary receptacle can be utilized for the horizontal continuous casting process.
REFERENCES:
patent: 3857437 (1974-12-01), Watts
patent: 4640336 (1987-02-01), Arakawa et al.
patent: 4694886 (1987-09-01), Sakaguchi
patent: 4744406 (1988-05-01), Rostik
patent: 4802436 (1989-02-01), Wilson et al.
patent: 2 412 424 (1974-10-01), None
patent: 31 23 704 (1982-12-01), None
patent: 0 049 239 (1981-09-01), None
Collard & Roe P.C.
Elve M. Alexandra
Kerns Kevin P.
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