EP1142660A1 - Grooved refractory part used for metallurgical casting, assembly of refractory parts and casting installation comprising such assembly - Google Patents

Abstract

The pouring tube (4) has a contact face (14) at the upper face of a collar (7). The contact face has a pair of additional grooves which are formed symmetrically, and communicate with an injection groove through either sides of its determinate section in a contact face (11) of an inner nozzle (9). Independent claims are also included for the following: (a) Refractory assembly; (b) Steel casting installation

Description

The present invention relates to a grooved refractory piece for the casting of a metal melted between an upper metallurgical container and a lower metallurgical container, a refractory assembly comprising such a part and a casting installation comprising such an assembly.

We know that the continuous casting of steel causes the filling of containers successive metallurgicals, in particular a pocket, a distributor and ingot molds, and that when passing from a higher metallurgical container to a metallurgical container lower, the metal should, as far as possible, be protected from contact with air ambient.

For this purpose, a jet protection tube or a submerged nozzle made of refractory material extends the pouring opening of the upper container (respectively the bag or the distributor), and plunges into the molten metal bath present in the lower container (respectively the distributor or the ingot mold), so that the molten metal passes from the pocket in the distributor or the distributor in the mold without ever being exposed to air ambient.

The pouring opening of the upper container has an internal material nozzle refractory, which opens under this container through a contact face intended to receive support a contact face of the jet protection tube or the submerged nozzle, to form a joint surface between these two parts.

Conventionally, a casting installation also includes means for regulation of the flow of molten metal. These means may consist of a distaff plunging into the metal bath of the upper container opposite the orifice casting and the degree of immersion in said metal bath determines the opening of said pouring orifice. Alternatively, a slide valve can also be used comprising a set of refractory plates each pierced with an orifice. Said plates are normally found between the internal nozzle and the jet protection tube or the submerged nozzle. The degree of alignment of the adjacent plate holes determines the flow of molten metal.

A continuous casting installation therefore includes many refractory parts assembled and having contact surfaces which can be flat at their interface or non-planar as for example indicated in document US 5,984,153.

However, we know that the section reductions occurring along the metal pouring channel melted induce significant depression which in turn could cause air intake. To avoid the penetration of air through the joint surface between two adjacent refractory pieces, an inert fluid is conventionally injected, plus particularly an inert gas such as argon, thanks to an injection groove which is formed in the contact surface of one of the parts and which delimits, with the contact face on the other room, a gas injection channel which almost completely circumscribes the orifice for casting molten metal.

This effectively reduces the risk of the metal coming into contact with the ambient air, when passing from the upper container to the lower container.

More recently, documents WO 98/17420 and WO 98/17421 have further shown that the injection channel could effectively perform the additional function of allowing injection of a sealing agent, such as for example graphite, to fill cracks that propagate from the pouring hole in the contact surface of a parts, or scratches, or scuffs, which are produced substantially in the direction displacement of one of the parts during its replacement. The sealing agent, which is transported by a carrier fluid, limits damage to the refractory around the cracks and / or scratches or scuffs and thus prevents the aspiration of air through them. The canal injection can be opened or closed. In the following description, the expressions injection channel or injection groove will be used interchangeably to designate a channel or groove intended for the injection of an inert gas alone or of a clogging in a carrier fluid.

The injection channel is therefore very useful. However, the Applicant has found that in in certain cases, this canal could be obstructed, that is to say blocked, itself.

In particular, this phenomenon has been observed in the case where the injection groove is formed in a surface of a refractory piece against which the surface of a another refractory piece intended to be replaced during casting operations. Through example, when the injection groove is formed in the lower surface of the nozzle against which the upper surface of a jet protection tube rests or of a submerged nozzle. Although the invention is obviously not limited to this particular case, for reasons of ease, it will be described in the rest of the description with reference to an injection groove formed in the lower face an internal nozzle against which the upper face of a submerged nozzle rests. The replacement of the submerged nozzle can be carried out, in known manner, by positioning of a new submerged nozzle next to the submerged nozzle at replace and then move the two nozzles simultaneously, the new one driving the old one to take its place under the internal nozzle.

Prior to each replacement, the distributor's flow hole is closed, but it sometimes a certain amount of molten metal remains at the joint surface, at the interface between the pouring holes of the internal nozzle and the submerged nozzle.

This metal is entrained in the joint surface during the displacement of the nozzle, accumulates in the injection groove of the inert gas and causes its occlusion, which makes it ineffective both with regard to the admission of ambient air and with regard to the treatment of cracks and scratches or scuffs with a sealant carried by the fluid carrier.

The present invention aims to eliminate this drawback, in a simple and economic.

The present invention therefore relates to a refractory part delimiting a portion of a runner and comprising at least a first contact face capable of coming in support against a second contact face of another refractory piece defining a adjacent portion of the pouring channel and provided with an injection groove forming, with the first contact face, a fluid injection channel at least partially surrounding said channel, said part being designed to be moved along a trajectory predefined, along which the first contact face slides and remains in contact against the second contact face while the portion of the flow channel delimited by said part intercepts a determined part of the injection groove, characterized in that that the first contact face has an additional groove positioned so as to be in the casting position in the vicinity of the determined part of the groove and to communicate with this groove at least on either side of this part determined.

The additional groove formed in the contact face allows the injected fluid to go around the obstructed part of the injection groove.

In this way, even if the injection groove is obstructed, the injected fluid can circulate all around the pouring opening and form a barrier for ambient air.

An advantageous characteristic of the invention is that the additional groove is formed in the refractory piece which is regularly replaced, so that the injection channel is released again each time this part is replaced, contrary to the situation of the state of the art where the replacement of the refractory piece caused obstruction of the injection channel.

Preferably, the additional groove is blind so that the pressure in the channel injection is kept.

In a particular embodiment of the invention, the refractory piece constitutes a pouring tube, for example a submerged nozzle or a jet protection tube.

According to a particular characteristic, the additional groove is shaped to cover a mouth with a supply and / or discharge pipe (if there is one) a) of the fluid injection channel. This mouth is thus more likely to emerge in case of obstruction.

According to another particular characteristic, the first contact face comprises a second groove substantially parallel to the additional groove. This second groove may be located, relative to the additional groove, on the other side of the channel of casting. This second groove, hereinafter called scraper groove, has for function of scraping the contact face comprising the injection groove, in order to remove all dirt before positioning the new refractory piece likely to obstruct quality contact between the two contact faces.

Advantageously, the scraping groove is symmetrical with the additional groove by compared to the pouring channel. The two grooves are therefore interchangeable, this allows an introduction of the replacement part without having to take into account its sense of displacement. Each groove fills, depending on its position relative to the groove injection function, the additional groove function or the scraping groove function.

The present invention also relates to an assembly of refractory parts defining a runner, a first part of the assembly comprising at least a first contact face in abutment against a second contact face of a part adjacent refractory, a groove being provided in the second contact face for form, with the first contact face, a fluid injection channel surrounding at at least partially said channel, characterized in that the first part is a part refractory as described above.

According to a particular characteristic of this assembly, one or some of the parts refractories have a supply and, if necessary, a discharge duct fluid injection channel.

The present invention finally relates to a casting installation comprising a upper metallurgical vessel and a lower metallurgical vessel, connected by a runner defined in particular by an assembly of refractory parts as described above, the installation comprising a source of fluid connected to the supply duct of the fluid injection channel.

In a particular embodiment, the casting installation further comprises a means for injecting a sealing agent into the fluid.

• la figure 1 est une vue en coupe axiale d'une busette interne d'un répartiteur et d'une busette immergée,
• la figure 2 est une vue de dessous de la face de contact de la busette interne,
• la figure 3 est une vue de dessus de la face de contact de la busette immergée,
• la figure 4 représente les faces de contact de la busette interne et de la busette immergée superposées,
• la figure 5 est une vue analogue à la figure 1 montrant une valve à tiroir intercalée entre la busette interne et la busette immergée,
• la figure 6 est une vue de dessous de la plaque inférieure d'une valve à tiroir similaire à la vue de la figure 2.

In order to better understand the invention, we will now describe an embodiment given by way of non-limiting example of the scope of the invention, with reference to the accompanying drawing in which:

• FIG. 1 is a view in axial section of an internal nozzle of a distributor and of a submerged nozzle,
• FIG. 2 is a bottom view of the contact face of the internal nozzle,
• FIG. 3 is a top view of the contact face of the submerged nozzle,
• FIG. 4 shows the contact faces of the superimposed internal nozzle and immersed nozzle,
• FIG. 5 is a view similar to FIG. 1 showing a slide valve interposed between the internal nozzle and the submerged nozzle,
• FIG. 6 is a view from below of the lower plate of a slide valve similar to the view of FIG. 2.

In Figure 1, there is shown the bottom wall 1 of a distributor, in a region surrounding one of its pouring orifices 2.

The distributor is provided with a tube changing device 3 which includes a mounting plate 5, integral with the rear wall of the distributor, a slide 6 for receive the flanges 7 of two immersed nozzles 4 which are thus kept at near the mounting plate 5, and a cylinder 8 to push the two nozzles immersed 4 in the slide 6.

The tapping hole 2 of the distributor has an internal nozzle 9 made of material refractory, which passes through the mounting plate 5 and rests on the underside of this last, by a contact face 11 surrounding the pouring orifice and forming a face of planar contact 11.

The slide 6 keeps the two immersed nozzles 4 in abutment against the contact face 11 of the internal nozzle, under a high pressure equivalent to a weight of several tonnes.

In FIG. 1, the immersed nozzle 4 on the right is the one that forms, with the internal nozzle 9, a portion of the runner 12 of the molten metal. The one on the left is a nozzle which has just been replaced by displacement in the slide 6 under the action of the jack 8. A stopper 10 can be applied against the upper mouth 13 of the nozzle internal to regulate the metal flow or stop the casting, in particular for allow replacement of the submerged nozzle.

In Figure 2, we see the contact face 11 of the internal nozzle.

The pouring opening has an elongated section in a direction 14 which is parallel slide 6, i.e. the direction in which the submerged nozzles are displaced when replacing the oldest of them.

Around the pouring orifice, the contact face has an injection groove 17 in shape of a portion of a circle on three quarters of a turn, extended by rectilinear portions whose ends 19 are close but do not communicate with each other. A end 19 joins the mouth 20 of a supply duct, or, where appropriate outlet, arranged in the internal nozzle 9. There is no need to attach too much of importance to the very shape of the groove 17. Preferably, its ends 19 must be close so that the area not circumscribed by the groove is reduced to minimum and relatively close to the periphery so that the mouth of the supply and, if necessary, fluid discharge conduits are accessible. The combination of straight and circular portions fulfills this function.

In FIG. 3, it can be seen that each immersed nozzle 4 delimits a portion 24 of section elongated transverse (in direction 14) of the pouring channel and that its flange 7 has a rectangular shape for its guidance in the slide 6 of the device 3 of change of submerged nozzle.

The contact face 14 of each submerged nozzle, constituted by the upper face (along the orientation of FIG. 1) of its flange 7, covers the injection groove 17 of the internal nozzle 9 when the submerged nozzle 4 is in the use position and thus forms a fluid and / or sealing agent injection channel, to combat admission ambient air in the runner and / or against flaring of refractory material constituting the internal nozzle around its cracks or scratches 25.

When replacing the submerged nozzle 4, the contact faces 14 of the two submerged nozzles slide in the direction 14 against the contact face 11 of the internal nozzle. The frictions are maximum in the regions 21, 22 delimited by the broken lines (in FIG. 2), which correspond to the places swept by the pouring orifices Error! Source of referral not found. immersed nozzles during their movement.

Drops of molten metal present at the interface between the pouring holes of the nozzle internal and submerged nozzle are carried away in region 22 located downstream of the pouring orifice, in the direction of movement of the submerged nozzles, and accumulate in the injection groove, which causes blockage of a specific part 23 (marked with a thickened line) of said injection groove, corresponding to its intersection with said region 22.

Two additional grooves 26, 27 are formed in the contact face 14 of each submerged nozzle 4, in corresponding locations, when said nozzle submerged is in the casting position, at the parts of the injection groove 17 belonging to regions 21, 22 delimited by the broken lines (in FIG. 2) of the face of contact of the internal nozzle, i.e. to the regions swept by the injection orifices immersed nozzles during their movement.

In the example shown, the two additional grooves 26, 27 are symmetrical by central symmetry around the center 28 of the contact face, which is substantially the center of the cross section of the pouring channel, because each submerged nozzle is usable in the two possible positions of engagement of its rectangular flange 7 in slide 6.

In reality, only the additional groove 26 covering the determined part 23 of the injection groove fulfills the function of clearing the injection channel.

In fact, when said determined part 23 of the injection groove 17 is obstructed, following the displacement of the two submerged nozzles, the fluid sent into the channel injection can bypass the obstructed part of the injection groove 17 by borrowing the additional groove 26 of the submerged nozzle, which communicates with said groove injection on either side of its obstructed part 23. The fluid can thus reach the rest of the injection channel to act as expected against the air intake and / or the treatment of cracks and scratches or scuffs.

Beyond its circular portion covering the determined part 23 of the groove injection, the additional groove 26 is extended by a straight portion which covers the straight portion of the injection groove.

The second additional groove 27, which does not cover the determined part 23 of the injection groove, nevertheless fulfills a function of scraping the contact face 11 of the internal nozzle when moving the two immersed nozzles.

The slide valve 30 of FIG. 5 is inserted between the internal nozzle 9 and the nozzle submerged 4 described previously.

This slide valve 30 is constituted by a fixed upper plate 31, a plate mobile intermediate 32 and a fixed bottom plate 33.

As has just been explained, the internal nozzle 9 may have a groove injection. In this case, the injection channel is formed with the upper face (relative in FIG. 4) of the fixed upper plate 31.

Other joint planes are formed between the fixed plates 31, 33 and mobile 32 of the valve with drawer. As is known, other injection channels can be provided in these joint planes to combat air intake.

Between the fixed bottom plate 33 and the submerged nozzle 4, there is a surface of joint which presents the same risks of degradation as that described with reference to Figures 1 to 4, because the replacements of the submerged nozzle 4 cause friction and risks of obstruction of an injection groove 34 formed in the face lower (compared to Figure 4) of the fixed bottom plate and completed by the face of contact of the submerged nozzle to form a fluid injection channel.

Due to this risk, the additional grooves 26, 27 of an identical submerged nozzle to that of Figure 3 perform the same functions with respect to the fixed bottom plate than with respect to the internal nozzle of FIG. 1.

Although the additional grooves have been described on submerged nozzles for a flat joint surface at the outlet of a distributor, it is understood that the invention applies to any flat or non-flat interface between two refractory parts delimiting between them a fluid injection channel.

1. paroi de fond du répartiteur

2. orifice de coulée

3. dispositif de changement de tube

4. busette immergée

5. plaque de montage

6. glissière

7. collerette du tube

8. vérin

9. busette interne

10. quenouille

11. face de contact de la busette interne

12. une portion du chenal de coulée

13. embouchure supérieure de la busette interne

14. face de contact du tube

16. direction X

18. rainure d'injection

19. extrémités de la rainure

20. embouchure d'un conduit d'alimentation, respectivement d'évacuation

21. région située en amont de l'orifice de coulée

22. région située en aval de l'orifice de coulée

23. partie déterminée de la rainure d'injection

24. portion de section transversale allongée suivant la direction X du chenal de coulée de la busette immergée

25. fissures, rayures et éraflures de la busette interne

26. rainure additionnelle recouvrant la partie déterminée de la rainure d'injection

27. deuxième rainure additionnelle

28. centre de la face de contact de la busette immergée

30. valve à tiroir

31. plaque supérieure fixe

32. plaque intermédiaire mobile

33. plaque inférieure fixe

34. rainure d'injection formée dans la face inférieure (par rapport à la figure 5) de la plaque inférieure fixe

With reference to FIG. 6, reference will be made mutatis mutandis to the description of FIG. 2, the reference 34 designating an injection groove formed in the lower face (relative to FIG. 5) of the fixed lower plate.

1. bottom wall of the distributor

2. pouring orifice

3. tube changing device

4. submerged nozzle

5. mounting plate

6. slide

7. tube flange

8. cylinder

9. internal nozzle

10. distaff

11. contact face of the internal nozzle

12. a portion of the pour channel

13. upper mouth of the internal nozzle

14. tube contact face

16. direction X

18. injection groove

19. ends of the groove

20. mouth of a supply or discharge pipe

21. region upstream of the pouring orifice

22. region downstream of the pouring orifice

23. specified part of the injection groove

24. portion of cross section elongated in direction X of the pouring channel of the submerged nozzle

25. cracks, scratches and scrapes on the internal nozzle

26. additional groove covering the determined part of the injection groove

27. second additional groove

28. center of contact face of submerged nozzle

30. slide valve

31. fixed top plate

32. movable intermediate plate

33. fixed bottom plate

34. injection groove formed in the lower face (with respect to FIG. 5) of the fixed lower plate

Claims (11)

Refractory piece (4) delimiting a portion (12) of a pouring channel and comprising at least a first contact face (14) capable of coming to bear against a second contact face (11) of another refractory piece ( 9) delimiting an adjacent portion of the pouring channel and provided with an injection groove (17) forming, with the first contact face (14), a fluid injection channel at least partially surrounding said channel, said part (4) being designed to be moved along a predefined path, along which the first contact face (14) slides and remains in abutment against the second contact face (11) while the portion (12) of the runner delimited by said part intercepts a determined part (23) of the injection groove, characterized in that the first contact face (14) has an additional groove (26, 27) positioned so as to be in the vicinity of the part determined (23) d e the groove and to communicate with this groove at least on either side of this determined part. Refractory piece according to claim 1, characterized in that said piece constitutes a pouring tube, for example a submerged nozzle (4). Refractory piece according to either of Claims 1 and 2, characterized in that the additional groove (26) is blind. Refractory piece according to any one of claims 1 to 3, characterized in that the additional groove (26) is shaped to cover a mouth (20) with a supply duct and / or discharge from the injection channel of fluid. Refractory piece according to any one of claims 1 to 4, characterized in that the first contact face (14) has a second groove (27) substantially parallel to the additional groove. Refractory piece according to claim 5, characterized in that the second groove (27) is located, with respect to the additional groove, on the other side of the pouring channel (12). Refractory piece according to claim 6, characterized in that the second groove (27) is symmetrical with the additional groove with respect to the runner (12). Assembly of refractory parts delimiting a pouring channel, a first part (4) of the assembly comprising at least a first contact face (14) bearing against a second contact face (11) of an adjacent refractory part (9 ), an injection groove (17) being provided in the second contact face (11) to form, with the first contact face (14), a fluid injection channel at least partially surrounding said channel, characterized in that the first part (4) is a refractory part according to any one of claims 1 to 7. Assembly according to claim 8, characterized in that one or some of the refractory parts comprise a supply duct and, optionally, discharge from the fluid injection channel. Casting installation comprising an upper metallurgical vessel and a lower metallurgical vessel, connected by a defined runner (12) in particular by an assembly of refractory parts according to any one of claims 8 and 9, the installation comprising a source of fluid connected to the supply line for the fluid injection channel. Casting installation according to claim 10, characterized in that said installation further comprises means for injecting a sealing agent into the fluid.

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