WO2004052576A1

WO2004052576A1 - Metallic frame for a pouring nozzle, assembly of a metallic frame with a pouring nozzle and device for the insertion and/or removal of a pouring nozzle

Info

Publication number: WO2004052576A1
Application number: PCT/BE2003/000212
Authority: WO
Inventors: Mariano Collura; Vincent Boisdequin
Original assignee: Vesuvius Group SA
Current assignee: Vesuvius Group SA
Priority date: 2002-12-10
Filing date: 2003-12-08
Publication date: 2004-06-24
Anticipated expiration: 2005-06-10
Also published as: AU2003289763A1; AR042353A1

Abstract

The present invention relates to a metallic frame used to girdle a pouring nozzle used in a device for the insertion and/or removal of a pouring nozzle of a molten metal casting installation. The invention also concerns an assembly of such a metallic frame with a pouring nozzle. According to another of its aspects, the invention concerns a device for the insertion and/or removal of a pouring nozzle of a molten metal casting installation which is particularly adapted for using the metallic frame of the invention. The metallic frame is provided with coupling means to pulling means of the device for the insertion and/or removal of the nozzle and with coupling means (11) to a manipulator. Thus, the time required to insert a new nozzle is reduced so as to reduce or even eliminate the risk of the molten metal freezing in the casting channel, particularly in case of non natural opening of a ladle.

Description

Metallic frame for a pouring nozzle, assembly of a metallic frame with a pouring nozzle and device for the insertion and/or removal of a pouring nozzle.

[0001] The present invention relates to a metallic frame used to girdle a pouring nozzle used in a device for the insertion and/or removal of a pouring nozzle of a molten metal casting installation. The invention also concerns an assembly of such a metallic frame with a pouring nozzle. According to another of its aspects, the invention concerns a device for the insertion and/or removal of a pouring nozzle of a molten metal casting installation which is particularly adapted for using the metallic frame of the invention.

[0002] The casting of a molten metal is generally carried out in an installation comprising several refractory elements forming a casting channel between two successive metallurgic containers. These elements fulfill different functions which are the transfer of the molten metal, the shrouding of the molten metal against the cooling and the chemical attacks of the surrounding atmosphere and, optionally, the casting flow control of the molten metal. Thus, in the ingot mold continuous casting, the molten metal contained in a casting ladle is discharged through a discharge orifice arranged in the bottom wall of the ladle and extended by a nozzle extending through the bottom wall. Under the bottom wall, there is generally a molten metal stream flow control device constituted from refractory plates provided each with a pouring orifice which can be aligned or shifted one with respect to the other by relative displacement of the plates so as to modify the cross-sectional flow area defined by the superposition of the pouring orifices. The melt exits from the flow-control device into a nozzle, having generally a small length and called collector nozzle. In certain cases, a pouring nozzle intended for shrouding the stream discharged from the collector nozzle during its way to a tundish is provided. Conventionally, this pouring nozzle is fitted on the downstream end of the collector nozzle. From the USP 5,695,674, a casting installation wherein the collector nozzle and the shrouding nozzle form an assembly introduced into the casting position by sliding into guide-rails is however also known. The International patent application WO-A1 -9920420 discloses such a shrouding nozzle. [0003] The metal poured through the shrouding nozzle into the tundish is then directed towards one or more pouring orifices arranged in the bottom wall of the tundish. This orifice is prolonged by a nozzle which can run directly into the ingot mold. In this case, the flow control of the melt poured from the tundish is performed with a stopper system which can close the pouring orifice arranged in the bottom wall. In a variant, the nozzle can be formed of several adjacent elements, in particular, an inner nozzle ending upstreamly with the pouring orifice arranged in the bottom wall of the tundish and downstreamly with an end formed as a planar surface and a subentry nozzle ending upstreamly with a planar surface matching the planar surface of the inner nozzle. Such an installation allows the replacement with an appropriate device (such as described for example in the patent EP-A1- 192,019) of the subentry nozzle without having to interrupt the casting. In this case also, the flow- control of the melt poured from the tundish is performed with a stopper system which can close the pouring orifice arranged in the bottom wall. Another variant wherein a flow control device with plates working according to the same principle as the flow-control device above described in the context of the casting ladle is inserted between the inner nozzle and the subentry nozzle is also known. The patent EP-B1-441 ,927 discloses such a kind of installation. [0004] The possibility to insert and/or to exchange a nozzle during the casting without having to interrupt it has been mentioned here above. The pouring nozzle intended to lead the melt from a metallurgical container towards another one are indeed wear parts which are strongly mechanically, chemically and thermally stressed to an extent that their service life can limit the casting time. In this context, it may occur, at the level of the ladle as much as of the tundish, that the molten metal can not or not any longer freely flow through the inner nozzle. In the case of a ladle, such an event can occur at the opening. In particular, when, under the combined effect of the heat and pressure, the casting sand used to prevent the molten metal from entering the casting channel before the casting, has formed a sintered cupola which is too thick to break out at the opening of the ladle. In the case of a tundish, it is possible that during the casting, the pouring orifice or the inner nozzle become clogged by inclusional deposits (for example an alumina deposit in the case of the casting of an aluminium killed steel). [0005] In both cases, it is then necessary to completely close the casting channel, to remove the pouring nozzle so as to access the inner nozzle (possibly through the plates of the flow control device and, if need be, through a collector nozzle) and to reopen the casting channel. Thereby, it is possible to torch with an oxygen lance introduced into the inner nozzle (possibly through the plates of the flow control device and, if need be, through a collector nozzle) so as to destroy the plug clogging the casting channel. As soon as the plug has been destroyed, the molten metal can again flow through the inner nozzle. It will however exit on the free air at the downstream end thereof, downgrading thereby the cast metal which oxidize when contacting air and sucking air into the molten metal, which, in turn can cause numerous problems as well as a risk of projection and splashing of molten metal which are not without consequences for the manpower and the casting installation.

[0006] It is thus important to be able to reinsert a casting nozzle (possibly, the nozzle previously used can be recycled). For this purpose, it is necessary to interrupt again the casting for the time needed to insert a casting nozzle. Another problem could then arise if the insertion of the new casting nozzle takes too long. The molten metal retained at the level of the flow control device could indeed freeze in the casting channel where it cools down quickly. If so is the case, it is then necessary to repeat the whole process from the torching. It is possible to reduce this freezing risk by allowing enough molten metal to flow through the casting channel after the plug has been removed by torching. Thereby, the walls of the casting channel can accumulate enough heat and the freezing is delayed accordingly. It will however be easily understood that from the point of view of the quality of the cast metal, this solution is not desirable and even occasion often a downgrade of the cast metal.

[0007] In the case where the nozzle is inserted by fitting (thus in the case of a shrouding nozzle for a casting ladle), the new nozzle insertion operation after the plug removal operation takes from 10 to 15 seconds. This represents the acceptable limit beyond which the freezing risk is too high. Documents US-A1 -4892235, FR-A1 -2694711 , JP-A-7-164117 and JP-A-9-108825 show such nozzle.

[0008] In the case where the nozzle is inserted by sliding the planar surface forming its upper end against a matching planar surface forming the lower end of the upstream element of the installation (for example, in the case of a casting ladle shrouding nozzle forming a unit with the collector nozzle), the operation is clearly more complex and can take more time since it is then necessary to transfer the new tube from a manipulator where it was previously waiting, to the rail-guides, then to correctly align the new nozzle in the actuating device before submitting it to the action of a device intended to push it towards the casting position. [0009] In the context of the casting ladle, this problem is even more critical since the nozzle is cumbersome and uneasy to manipulate. In this case, it is also necessary to spend some type to couple (at least temporarily) the manipulator to the actuating device of the nozzle (or, more generally, to the ladle) to permit a pushing device to insert the nozzle on the guide-rails without stepping back. In this case, the new nozzle insertion after the plug removal operation can take from 30 seconds to more than one minute. This time is largely superior to the upper limit above discussed and has, so far, presented an insuperable obstacle preventing the use on a ladle of such a tube forming a unit with the collector nozzle. It would however be desirable to use such a nozzle that would permit, among other, to start the pouring of the ladle with the discharge opening of the nozzle immersed in the molten metal bath. Reference is made about this to the International patent application WO-A1 -9920420 which describes the advantages associated with this nozzle.

[0010] One of the object of the present invention is thus the reduction of the time necessary for the insertion of the new nozzle so as to reduce or even eliminate the freezing risk of the molten metal in the casting channel, in particular in the case of a ladle. [0011] According to the invention, this problem is solved thanks to device for the insertion and/or removal of a pouring nozzle of a molten metal casting installation, the nozzle, comprising a first upstream end able to form a joint with a matching surface of an adjacent element of the casting installation, device wherein the nozzle is brought by linear displacement from an insertion position towards a casting position where the surface of the nozzle first end is pushed against the matching surface of the adjacent element of the casting installation, by pulling the nozzle. [0012] Since the nozzle is thereby coupled to the pulling means of the device, operation taking a very short time, it is no longer necessary to couple a pushing device or even to align the nozzle. [0013] Nevertheless, it is necessary to provide the tube with coupling means to these pulling means. Therefore, according to the present invention, the nozzle is girdled, at the level of the first end by a metallic frame provided with coupling means for pulling means of the device for the insertion and/or removal of the pouring nozzle. Moreover, according to the invention, the metallic frame is provided with coupling means for a manipulator, located on the frame on the side opposite to the firing direction in the device for the insertion and/or removal so as to permit a quick insertion of a new nozzle into the device for the insertion and/or removal. [0014] Contrarily to the devices of the art wherein the coupling means for the manipulator are also used for the coupling to the nozzle actuation means (see for example JP-Kokai-09-108865 and JP- Kokai-07-164117) and which requires thus a very large lateral hindrance, the frame according to the invention permits the insertion of the nozzle in a few seconds without requiring an excessive hindrance.

[0015] Advantageously, the metal frame is provided with chamfers inducing thus metallic frame to self-align horizontally and vertically in the pulling device during the transfer of the nozzle towards the casting position. It is also advantageous that this frame be provided with two opposite sides parallel to themselves and to the firing direction of then nozzle to also works as guiding surface in the device for the insertion and/or removal of a pouring nozzle.

[0016] The coupling means to the puling means of the device for the insertion and/or removal of a pouring nozzle which are provided on the metallic frame can be located all around the periphery of said frame as far as they permit the pulling thereof. Preferably, the coupling means for the pulling means of the device for the insertion and/or removal of the casting nozzle are located on each side of the frame, perpendicularly to the firing direction in of the device for the insertion and/or removal to permit the operation of the pulling means which cannot end up in front and under the discharge opening of the inner nozzle.

[0017] The coupling means can be variously constituted. Preferably, means constituted from grooves adapted to receive each a lug drive of a pulling device of the device for the insertion and/or removal of the casting nozzle. This embodiment presents the advantage of only using metallic element having a high mechanical strength. Thereby, it is even possible to have a kind of cam or slope permitting the guiding of said lugs towards the groove intended to receive them. [0018] By appropriately selecting the dimensions of the metallic frame so as to form a structure rigid enough, it is possible to distribute evenly around the first end of the nozzle the stress generated by pushing the nozzle first end surface against the matching surface of the adjacent element of the installation. Preferably, the metallic frame is so conformed. [0019] In this case, the frame can be provided with an indentation intended to receive a nozzle whose the first end is circular and provided of a shoulder matching the indentation. Incidentally, the invention relates also to such a casting nozzle having a first circular end and provided with a shoulder matching the indentation of the metallic frame as well as to an assembly of such a nozzle with a metallic frame according to the invention. The tube can be surrounded at is upper end with a metallic envelope, generally embossed and/or welded so as to distribute the stress to which it is submitted. It is however possible to have a nozzle having a bare end. [0020] According to a preferred variant of the invention, there can be a blocking device for the nozzle in the metallic frame so as to be able to manipulate it according to different orientations without the risk for the nozzle to fall down.

[0021] According to a particularly advantageous embodiment, the metallic frame is adapted to be recycled. For example, it can open in two parts pivoting around an axis. Thereby, when the nozzle is worn, it is possible to extract it from the metallic frame which can then be recycled. Moreover, in case the nozzle is of the type having an outer diameter of the lower end larger than the outer diameter at the level of the upper end (such as disclosed in the International patent application WO- A1 -9920420), it is impossible to introduce such a tube directly into a metallic frame and this embodiment is therefore particularly advantageous. [0022] In order to permit a better understanding of the invention, it will now be described with references to the figures illustrating particular embodiments of the invention without however limiting it whatsoever. On these figures, a cross-section of an assembly of a casting nozzle girdled with a frame according to the invention is depicted on figure 1. Figures 2, 3 and 4 show various embodiments of the metallic frame. [0023] Figure 1 shows the refractory nozzle 2 girdled into the metallic frame 1 at the level of its upper upstream end 3. It is preferable that the surface of the nozzle intended to be pushed against the downstream surface of the adjacent refractory element of the installation protrudes beyond the frame so as to avoid any interference with the downstream surface of the adjacent refractory element. The coupling means to the pulling means of the device for the insertion and/or removal of the pouring nozzle are constituted of two grooves 5 located on each side of the frame, perpendicularly to the firing direction in of the device for the insertion and/or removal. In this case, the pulling means can be constituted of two lugs drive entering into the grooves. On both sides, there can be a slope permitting the guiding of the lugs towards the grooves. [0024] The metallic frame is provided with an indentation 9 intended to receive a nozzle 2 whose the first end is circular and provided with a shoulder 10 matching the indentation 9. This characteristic combined with the appropriate selection of the metallic frame dimension so as to provide a sufficiently rigid structure permits to distribute evenly around the first end of the nozzle the stress generated by pushing the surface of the first end against the matching surface of the adjacent element of the installation. [0025] Finally, an example of the coupling means 11 of the metallic frame to a manipulator whose the end is conformed to engage rigidly into the indentation of the coupling means 11. [0026] Figures 2 and 3 show coupling means 6 and 7 for the pulling means of the device for the insertion and/or removal of the casting nozzle which are located in the firing direction of said device. These coupling means can be constituted for example by two rods 6 provided with a hole (in this case, the pulling means can be constituted by another rod also provided with a hole which is introduced between the two rods of the metallic frame, the assembly being unified by a key) or by a T-shaped pin 7 (in this case, the pulling means can be constituted by a couple of hooks). Alternatively, the figure 4 shows another embodiment according to which the actuating means are constituted by two lugs 8 located each on an opposite side of the frame, perpendicularly to the firing direction in of the device for the insertion and/or removal. In this case, the pulling means are constituted by two grooves where said lugs can enter.

[0027] Eventually, a metallic frame openable in two parts 12, 12' by pivoting around an axis 13 is shown on figure 2. Thereby, the nozzle 2 can be easily extracted after use and the frame can be recycled.

Claims

1. Metallic frame (1 ) for girdling a pouring nozzle (2) of a device for the insertion and/or removal of a pouring nozzle of a molten metal casting installation, the nozzle, comprising a first upstream end (3) whose the planar surface is provided with a molten metal inlet orifice (4) is able to form a joint with a matching surface of an adjacent element of the casting installation also planar and provided with an orifice, device wherein the nozzle (2) is brought by linear displacement from an insertion position towards a casting position where the surface of the nozzle first end (3) is pushed against the matching surface of the adjacent element of the casting installation, the metallic frame (1) girdling the tube (2) at the level of the first end (3) and being provided with coupling means (5,6,7,8) to pulling means of the device for the insertion and/or removal of the nozzle, characterized in that the frame (1) is provided with coupling means (11) to a manipulator, located on the frame (1 ) on the side opposite to the firing direction in the device for the insertion and/or removal.

2. Frame according to claim 1 , characterized in that the coupling means (5,8) of the frame (1 ) to the pulling means of the device for the insertion and/or removal of the casting nozzle are located on each side of the frame, perpendicularly to the firing direction in the device for the insertion and/or removal.

3. Frame according to claim 2, characterized in that the coupling means of the metallic frame comprises at least two grooves (5) adapted to receive each a lug drive of a pulling device of the device for the insertion and/or removal of the casting nozzle.

4. Frame according to claim 1 , characterized in that the frame is shaped so as to distribute evenly around the first end of the nozzle the stress generated by pushing the first end of the nozzle against the matching surface of the adjacent element of the installation.

5. Frame according to claim 4, characterized in that the frame (1 ) is provided with an indentation (9) intended to receive a nozzle (2) whose the first end is circular and provided of a shoulder (10) matching the indentation (9).

6. Frame according to claim 1 , characterized in that the frame is provided with opening means allowing the insertion and/or removal of the nozzle from the frame.

7. Frame according to claim 6, characterized in that the frame (1) can open in two parts (12,12') pivoting around an axis (13).

8. Assembly of a metallic frame according to any one of the claims 1 to 7 with a casting nozzle.

9. Assembly of a metallic frame (1 ) according to claim 5 with a casting nozzle (2) whose the first upstream end (3) is planar and circular and provided with a shoulder (10) matching the indentation (9) of the metallic frame.

10. Device for the insertion and/or removal of a pouring nozzle of a molten metal casting installation, the nozzle (2) comprising a first upstream end (3) whose the planar surface, provided with a molten metal inlet orifice (4) is able to form a joint with a matching surface, also planar and provided with an orifice, of an adjacent element of the casting installation, device wherein the nozzle is brought by linear displacement from an insertion position towards a casting position where the surface of the nozzle first end is pushed against the matching surface of the adjacent element of the installation, the tube (2) being girdled at the level of the first end (3) by a metallic frame (1) according to any one of the claims 1 to 7, characterized in that the device comprises pulling means for the frame (1).