FR2659880A1 - Linking device between a metallurgical vessel containing a liquid metal and an ingot mould - Google Patents

Abstract

This device comprises an annular wall (8) integral with the base (1) of the vessel and surrounding the nozzle, and a chamber (9) with a double annular wall (9a, 9b) with a U-shaped cross-section which is open towards the top, extending the wall (7) of the ingot mould (3) and arranged opposite the said annular wall so that the latter penetrates therein, and the chamber (9) with a double wall contains a liquid (11) in which the wall (8) integral with the base (1) of the vessel is partially submerged. This system ensures a perfectly leak-tight and flexible link between the vessel 1 and the ingot mould 3, which makes it possible to dispense with the conventionally used covering powder.

Description

 The present invention relates to a connecting device between a metallurgical container containing a liquid metal, such as a continuous casting distributor, and an ingot mold supplied with liquid metal by at least one refractory casting nozzle linked to the distributor.

 To avoid contact of the cast metal with the atmosphere and in particular to avoid its oxidation, it is known to inert the flow zone of the metal, this inerting between distributor and ingot mold being commonly carried out, for large formats, by using a submerged nozzle and covering powder to protect the upper surface of the metal in the mold.

 It is also known that the flow of liquid metal in the nozzle causes a depression therein, especially at the surface of the bath of liquid metal in the ingot mold (meniscus), which causes a suction of atmospheric gas and in particular d oxygen in the liquid metal, through the refractory wall of the nozzle.

 To overcome this drawback, it is known, in particular for small formats, to have around the nozzle, a sleeve creating an insulating gas chamber. In fact, this insulation proved to be very insufficient for many nuances of cast metal. Furthermore, one may in certain cases wish to heat the surface of the liquid metal, for example by burners, which is made impossible by the presence of the covering powder. In order to be able to remove this powder, it has therefore also been proposed to tightly connect the bottom of the metallurgical container (distributor) to the upper end of the wall of the mold by an accordion bellows. But such a bellows did not no longer sufficiently waterproof, and has the further disadvantage of gradually wearing out due to the fatigue which it undergoes, caused by the oscillations of the mold, necessary to prevent the sticking of the liquid metal on its walls.

 The invention therefore aims to provide a connecting device between the casting container and the mold, which is perfectly sealed around the nozzle and the meniscus of liquid metal.

 According to the invention, the connecting device comprises an annular wall secured to the bottom of the container and surrounding the nozzle, and a double annular wall enclosure of U-shaped cross section open upwards, linked to the wall of the mold and arranged in view of said annular wall so that the latter penetrates therein, and the double-wall enclosure contains a liquid in which the wall integral with the bottom of the container is partially immersed.

 It will be understood that under these conditions the seal is total, no atmospheric gas being able to pass through the liquid enveloping the lower part of the wall secured to the bottom of the container.

 Other features and advantages of the invention will become apparent during the description which follows, given with reference to the appended drawing which illustrates an embodiment thereof by way of nonlimiting example.

 The single figure is a partial axial vertical sectional view of an embodiment of the connecting device according to the invention, between the bottom of a liquid metal pouring distributor and the wall of a continuous casting ingot mold.

 The drawing shows a bottom 1 of a distributor containing a liquid metal 2 such as steel, and an ingot mold 3 containing a bath of liquid metal 4.

The ingot mold 3, of rectangular or square section, is placed below the bottom i in which is arranged a casting opening 5 which opens into a tubular refractory nozzle 6 whose lower end is immersed in the bath 4.

 The liquid metal 2 therefore flows from the distributor i into the ingot mold 3 through the nozzle 6.

 The connecting device between the bottom 1 and the annular wall 7 of the ingot mold 3 comprises an annular wall 8 of shape corresponding to the horizontal section of the ingot mold, integral with the bottom 1 of the container and projecting under it by surrounding the nozzle 6, and an enclosure 9 with double annular walls 9a, 9b. The latter are connected to their base by a bottom 9c itself extended by an annular section 9d fixed on the upper end of the wall 7, by any suitable means such as welding.

 The enclosure 9 therefore extends the wall 7 upwards and is arranged opposite the annular wall 8, (which can be made one-piece with the bottom 1), so that said wall 8 penetrates inside the enclosure. 9 between the two walls 9a and 9b. The enclosure 9 contains a liquid 11, for example water, in which the wall 8 is partially immersed.

 The wall 7 of the mold 3 is pierced with at least one orifice 12 into which opens a pipe 13 for injecting lubricant (oil) for the interface between the internal surface of the wall 7 and the liquid metal 4. The enclosure 9 and wall 8 can be made entirely of refractory material.

 It is understood that a perfectly sealed connection is thus produced between the bottom 1 of the container and the ingot mold 3, by virtue of the immersion of the lower part of the wall 8 in the liquid il of the enclosure 9. This liquid is maintained in circulation and at a relatively low temperature, by means known per se and not shown, in order to avoid the release of vapor. For the same purpose, it is also possible to provide the wall 8 with a flexible seal (not shown), located above the surface of the liquid 11, and which can slide on the internal surface of the walls 9a, 9b. Such a seal increases the efficiency of circulation and of maintaining the liquid therein at low temperature, to avoid the release of vapor.

 It will be noted that the walls 9a, 9b have between them sufficient spacing with respect to the thickness of the wall 8 to allow a certain freedom of movement in a horizontal direction. In addition, the lower end of this wall 8 is located sufficiently above the bottom 9c to allow a second degree of freedom of the wall 8 in a vertical direction.

 Under these conditions, the seal between the container 1 and the mold 3 remains complete during the oscillations of the mold. Another advantage of the device according to the invention lies in the fact that it makes it possible to remove the covering powder conventionally placed on the meniscus of the bath 4. In fact one of the functions of this powder is precisely to protect the bath 4 from liquid metal against the introduction of atmospheric oxygen. Another function of the covering powder consists in lubricating the interface between the bath 4 and the wall 7 to loosen the liquid metal from the wall. With the connection device according to the invention1, this lubrication is ensured by the introduction of oil into the lateral tube 13 which opens into the hole 12.

 Finally, the removal of the covering powder makes it possible to directly heat the meniscus, and moreover it allows a visualization of the meniscus1 for example by means of a suitable video camera, to control the pouring conditions and observe the meniscus near the walls1 and / or variations in the level of the metal in the mold.

 The invention is susceptible of various variants, among which the following will be cited: the wall 8 integral with the bottom 1 may be constituted at its upper part by a metallic core surrounded by refractory material 1 and at its lower part, immersed in the liquid 11, this wall may be entirely metallic.

 The lubricant can also be injected through porous elements, below the level of the meniscus, or else injected into the space circumscribed by the enclosure 9 and the annular wall 8 by a supply tube which then no longer passes through the ingot mold but the wall 8.

 In addition, the lower end of the nozzle can then also not be immersed insofar as it is agreed to dispense with guiding the jet of liquid metal into the bath.

 Finally the enclosure 9 can also1 instead of being located above the wall of the mold1 be placed laterally, at its periphery.

Claims (3)

 1. Connecting device between a metallurgical container such as a continuous casting distributor containing a liquid metal (2) and an ingot mold (3) supplied with liquid metal by at least one pouring nozzle (6) linked to said container1 characterized in that it comprises an annular wall (8) integral with the bottom (1) of the container and surrounding the nozzle, and an enclosure (9) with double annular wall (9at 9b) of U-shaped cross section open upwards linked to the wall (7) of the mold (3) and disposed opposite said annular wall so that the latter penetrates therein, and the double-walled enclosure (9) contains a liquid (41) in which the wall (8) is partially immersed ) secured to the bottom (1) of the container.  2. Device according to claim 1, characterized in that the wall (8) integral with the bottom (1) of the container consists at its upper part of a metal core surrounded by refractory, and at its lower part, immersed in the liquid (11), is entirely metallic.  3. Device according to one of claims 1 and 2, characterized in that the wall (8) integral with the container is provided with a flexible seal located above the liquid (11), and which can slide on the walls (9a, 9b ) of the enclosure (9).