EP0825910A1

EP0825910A1 - Device and process for changing a continuous casting tube of a distributor in a steel-works

Info

Publication number: EP0825910A1
Application number: EP96913591A
Authority: EP
Inventors: Francois-No[L Richard
Original assignee: Vesuvius France SA
Current assignee: Vesuvius France SA
Priority date: 1995-05-05
Filing date: 1996-04-15
Publication date: 1998-03-04
Anticipated expiration: 2016-04-15
Also published as: SK283132B6; BR9608325A; CZ292318B6; ES2135896T3; DE69603081T2; KR100371614B1; JP3734272B2; CA2219951A1; PL323131A1; MX9708487A; AU705969B2; CN1188437A; AU5652696A; CN1072081C; ATE181689T1; RU2152846C2; DE69603081D1; FR2733705A1; PL180635B1; WO1996034713A1

Abstract

PCT No. PCT/FR96/00572 Sec. 371 Date Feb. 24, 1998 Sec. 102(e) Date Feb. 24, 1998 PCT Filed Apr. 15, 1996 PCT Pub. No. WO96/34713 PCT Pub. Date Nov. 7, 1996A tube changing device is comprised of a chassis (16) mounted of the distributor (2), refractory pieces (10, 18, 22) that delimit a casting gutter, these refractory pieces being comprised of at least one fixed place (18) and a tube having a plate (24) in its upper part, means for generating pressure for applying the plate (24) of the tube (22) against the fixed plate (18), a position for introducing a new tube (22a), a casting position and a position for evacuating the worn tube (22b), guidance means (18, 48) that permit the new tube (22a) to pass from the introduction position to the casting position and the worn tube (22) to pass from the casting position to the evacuation position, actuation means (34, 36) for moving the new tube from the introduction position to the casting position and the worn tube from the casting position to the evacuation position. The introduction position, casting position and evacuation position are arranged around a convex cylindrical surface (18) that constitutes the periphery of the fixed plate.

Description

DEVICE AND METHOD FOR CHANGING A CONTINUOUS CASTING TUBE OF A STEEL DISTRIBUTOR

The present invention relates to a device for changing a continuous casting tube comprising:

a chassis mounted under the distributor; refractory pieces which delimit a pouring channel for the passage of the steel from the distributor to a continuous casting mold having a large dimension and a small dimension, these refractory pieces comprising at least one fixed plate and a tube comprising a plate at its the top part ; pressurizing means for applying the plate of the tube against the fixed plate; a position for introducing a new tube, a pouring position and a position for discharging a used tube; guide means allowing the new tube to pass from the insertion position to the pouring position and the used tube to pass from the casting position to the discharge position; - actuating means for passing the new tube from the insertion position to the pouring position and the used tube from the casting position to the discharge position.

It generally applies to slab casting and more particularly to the casting of thin slabs.

In a continuous steel plant, the steel is poured from a ladle into a distributor, and from the distributor into one or more molds. To protect the steel from contact with air between the distributor and the mold, the steel is isolated from the atmosphere by means of a submerged refractory tube fixed to the bottom of the distributor and the lower end of which dips into the mold. . This tube wears out and clogs quickly, especially in its lower part. This limits the duration of the pour. To extend this period, devices have been devised which make it possible to replace a used tube with a new one. For economic reasons, it is preferable to change the tube without interrupting the pouring, that is to say without raising the distributor.

In these devices, called tube change devices, the tube is provided with a plate at its upper part, this plate can be attached or formed in one piece with the tube. This plate can slide, while maintaining a sealed junction, on the underside of a fixed plate of the distributor. In what follows the whole of the tube and the plate associated with it are simply called the tube. A new tube is introduced into the mold, next to the used tube. Means are used to push the new tube into the casting position while the used tube is pushed back to the other side of the mold.

To allow a tube change without raising the distributor, the lower end of the new tube must be immersed in the steel of the mold before the used tube is pushed towards its evacuation position. In the same way the used tube remains immersed in the steel when it is in the evacuation position.

An example of such a device is known from document EP 0 192 019.

These known devices have several drawbacks.

It is necessary that the mold has a sufficient width so that three tubes can be placed there side by side: the position of the new tube, the position of the tube which is pouring, and the position which will take the used tube after exchange. In many cases the mold does not have a sufficient width and other more unfavorable methods must be used.

To carry out the tube change, a cylinder is generally used which pushes the new tube at its plate, which presses on the plate of the used tube. It is it is essential that this effort is transmitted through the plates of the new tube and the used tube. In other words it is essential that these plates come into contact with each other before the lower ends of the tubes touch. Indeed, in the opposite case, the forces exerted at the end of the tubes would cause their jamming in the slides of the tube change and their rupture. For the device to function correctly it is therefore necessary that the plates have a length greater than the size of the end of the tubes in the direction of the large dimension of the mold. This requirement is easy to meet in the case of a thick slab. Indeed, the tube then has an approximately circular compact section and the plate can easily have a length greater than the outside diameter of the tube. On the other hand, in the case of a thin slab casting, the mold is very narrow. In order to maintain a large passage section, the end of the tube must be very elongated in the direction of the large dimension of the mold. Consequently, the plates provided at the upper end of the tube must themselves be very elongated. This results, in addition to an additional cost, an increase in their size and increased difficulties for maneuvering the tube in the reduced volume between the bottom of the distributor and the mold.

In order to overcome this drawback, it has been imagined to introduce an intermediate plate between the plates of the tubes. Such an arrangement is described for example in the patent

WO95 / 03906. This intermediate plate effectively makes it possible to reduce the size of the plates but it requires additional manipulations, gives rise to a risk of forgetting the intermediate plate and poses alignment problems.

Finally, when the tube is put in place, its end must be introduced into the mold, then immersed in the steel. In the same way, when extracting the used tube, the lower end of the tube must be extracted from the steel, then from the mold.

In the existing art, these handling operations are generally carried out manually by an operator who carries and directs the tube by means of a clamp possibly associated with supports intended to facilitate the operations. In the case of thick slabs, these manual handling is relatively easy because there are several centimeters of play between the tube and the edges of the mold and because the steel skin solidified on the walls of the mold is thick and robust and does not fear possible impact with the tube, due to manual handling. In the case of thin slabs the handling problem becomes critical because the clearance between the tube and the mold walls is reduced to a few millimeters and the skin solidified in this type of thin slab is thin and fragile. Contact of the tube with this skin would induce a significant risk of breaking the skin, which would cause a breakthrough in the mold and stop the casting. The manipulations must therefore be extremely precise if one does not want to strike the tube.

Manual handling of the tube is therefore unrealistic and it would be necessary to use one or more very precise manipulators both for the introduction and for the withdrawal of the tube. Such a manipulator would not only be very expensive but also difficult to place in the working area which is reduced and must remain accessible to operators. The present invention specifically relates to a tube changing device which overcomes these drawbacks.

According to the main characteristic of the invention, the insertion position, the pouring position and the discharge position are arranged around a convex cylindrical surface having a horizontal axis perpendicular to the large dimension of the mold, this cylindrical surface constituting the periphery of the fixed plate.

The tube plate has a concave cylindrical shape which adapts to the convex cylindrical surface of the fixed plate so as to maintain a tight seal between these surfaces when the new tube passes from the insertion position to the casting position and the passage of the used tube from the pouring position to the discharge position by a rotational movement around the axis of the cylindrical surface.

The fixed plate is advantageously placed as low as possible below the mold so that the overall circle described by the tubes during their rotation is minimum. Thanks to this characteristic, the device can be used even when the width of the mold is less than three times the length of the end of a tube. In Indeed, since the introduction of the new tube and the evacuation of the used tube is effected by a rotational movement, it suffices that the circle described by the end of the tube does not strike the edge of the mold. Even in a narrow mold, you can change the tube without having to lift the distributor. Optionally when the width of the mold is reduced it is possible to slightly raise the distributor so that the circle of dimensions of the tube escapes the edges of the mold while keeping the tube submerged in the casting position.

The tube plate can, without disadvantage, be appreciably smaller than the end of the tube. Indeed, the radius of the cylindrical surface is much less than the radius of the circle described by the end of the tube. It is therefore sufficient that the ratio of the length of the plate to the length of the end of the tube is in the same ratio as the radius of the cylindrical surface to the radius of the circle traversed by the end of the tube.

Finally and mainly, the new tube is entirely out of the steel, and even generally out of the mold, when it is in its insertion position and the used tube is entirely out of the steel, and even generally out of the mold. when in its evacuation position.

Thanks to this preferred characteristic, during the introduction of a new tube, and the evacuation of a used tube, the tube is guided by the tube changing device itself. This guidance is a rotation guidance given by the cylindrical surface of the fixed plate on which the concave surface of the tube plate slides. The device also provides lateral guidance of the tube in the mold. These two guides are very easily precise. This eliminates the very important handling problem and eliminates the need to use an expensive manipulator which is difficult to implement.

The invention also relates to a method for changing the distributor of a continuous steelworks distributor for replacing a used tube with a new tube, in which a new tube is placed in a tube changing device, then pushed into the pouring position, while, simultaneously, the used tube is pushed from the casting position to a discharge position.

The method is characterized in that the new tube is placed in the tube changing device in a position located outside the mold, that the new tube is brought to its casting position by a rotation around a horizontal axis perpendicular to the large dimension of the mold, which has the effect of causing the used tube to rotate around this same axis, bringing the used tube into a discharge position outside the mold in place, the center of rotation being located as low as possible.

In difficult circumstances, when the width of the mold is particularly reduced, the distributor is raised enough so that the circle which will be described by the end of the new tube during its rotation avoids the edge of the mold, without the tube which is in pouring ceases to be immersed in the liquid steel of the mold; the new tube is placed in the tube changing device; the used tube is brought to its casting position by a rotation which has the effect of causing the used tube to rotate around this same axis; the used tube is removed from the tube changing device; - the distributor is lowered to its normal casting position.

This process makes it possible to make a tube change in the case where the mold has a reduced width without having to interrupt the casting.

According to a preferred variant of the method of the invention, the new tube is placed in the tube changing device in a substantially horizontal position, the new tube is brought to its casting position by a rotation of substantially 90 ° around a horizontal axis, which has the effect of causing the user tube to rotate substantially 90 ° around this same axis. The used tube is extracted from the tube changing device in a substantially horizontal position. Preferably the actuating means comprise a rotor mounted rotating around the horizontal axis of the cylindrical surface, this rotor comprising a finger which pushes the new tube under the pressurizing means.

Preferably the finger moves back and forth to take up a new tube

Preferably the device comprises first retaining means which make it possible to keep the new tube in its insertion position and second retaining means which make it possible to maintain the used tube in its evacuation position.

Preferably the guide means and the retaining means are designed so as to allow the introduction of the new tube and the evacuation of the used tube in a direction perpendicular to the large dimension of the mold.

Preferably in that the means for pressurizing the plate transmit radial forces to the back of the plate.

Preferably in that the edges of the plates are produced so as to ensure contiguous contact so as to leave no gap between two successive plates during the passage of the seal opposite the pouring orifice.

Preferably in that the cylindrical plate comprises means for locking in rotation relative to the chassis.

Other characteristics and advantages of the present invention will become apparent on reading the following description of an exemplary embodiment given by way of illustration with reference to the appended figures.

In these figures: FIG. 1 is a view in longitudinal section of a device for changing the . tube according to the present invention; Figure 2 is a schematic view in longitudinal section which illustrates the position of the device during a tube change; Figure 3 is a cross-sectional view along line 3-3 of Figure 1.

The distributor designated by the general reference 2 has been shown only partially. It includes a steel bottom wall 4 covered with a refractory layer 6. It contains liquid steel 8. The bottom of the distributor 2 is crossed by an internal nozzle 10 and which allows the passage of liquid steel 8 The flow of steel passing through the internal nozzle 10 can be controlled by a stopper 12 or possibly by a drawer device interposed between the bottom of the distributor and the tube change (device not shown).

A fixing plate or base plate 14 is fixed under the bottom plate 4 of the distributor. The chassis 16 of the tube changing device according to the invention is fixed under the base plate 14. A fixed plate 18 is mounted in the chassis 16.

This fixed plate is presented as a cylinder of refractory material comprising at its upper part a socket 19 and which makes it possible to receive the lower end of the internal nozzle 10. The fixed plate is traversed by an orifice 20 which extends the channel of the nozzle internal 10. The center of the fixed plate 18 has been designated by the letter

O. A tube designated by the general reference 22 is mounted on the lower part of the fixed plate 18. The tube 22 comprises, at its upper part, a plate 24 of concave shape which is applied tightly to the plate fixed 18. Pressurizing means 36 are provided for applying the plate 24 of the tube 22 against the fixed plate 18.

The length of the lower end of the tube has been designated by the reference 26.

Below the tube changing device is the casting mold 28 which has a large dimension designated by the reference 30 and generally called width. The mold contains the liquid steel 8, still in the liquid state, and solidified only in contact with the walls of the mold which are cooled with water, to form a skin 32.

In FIG. 1, a second tube, designated by the reference 22a, has been placed on the cylindrical surface 18. The tube 22a is a new tube intended to replace the tube 22.

To this end, the invention provides actuation means for passing the new tube 22a from its insertion position shown in FIG. 1 to the casting position which is that of the tube 22 and for simultaneously passing the tube 22 from the casting position to the discharge position 22b. In the embodiment shown, the actuating means consist of a transverse bar 34 applied against the upper edge of the plate 24a of the new tube. The bar 34 is linked to the rotor 48 capable of turning on the same axis as the fixed plate. The actuating means also comprise a jack 36 mounted under the base plate 14 and which makes it possible to actuate the bar 34.

FIG. 2 shows the new tube 22a and the used tube 22 being changed. It can be seen that the lower end of the new tube 22a which was entirely outside the liquid steel 8 of the mold, and even entirely outside the mold 28 in its insertion position shown in FIG. 1, is not immersed in the steel only when the tube is placed in the casting position. In the introductory position

22a and in the discharge position 22b the tube is applied without being pressed against the cylindrical surface 18. The pressurization occurs gradually when it passes from the insertion position 22a to the casting position. Also the pressure is gradually released when the tube p-asses from the casting position to the discharge position 22b. The plate 24a of the new tube enters under rocker arms 36 having one end actuated by an elastic means such as for example springs and another end, visible in FIG. 2, adapted to the back of the plate 24, 24a of the tube. The end of the rocker arm 36 exerts a radial action on the plates 24, 24a, 24b of the tubes, in other words an action directed preferentially towards the center O of the fixed plate 18. It can thus be seen that the device for changing the tube of the invention, like a device of the prior art, provides three positions, namely a position for introducing a new tube, a pouring position and a position for discharging a used tube. However, unlike the prior art, when the tubes are arranged in this respective position they are not parallel to each other but arranged radially on the fixed plate 18. As can be seen in FIG. 2, the used tube 22 is already partially out of the mold when the new tube 22a enters it. For the operation of the device to be possible it is sufficient that the avoidance circle 38 described by the point of the tubes 22, 22a, 22b furthest from the center O of the fixed plate 18 does not meet the angle 40 of the mold. casting 28. In the case where the circle 38 would strike the angles 40 it would still be possible to slightly raise the distributor from a distance 42 (see FIG. 1) such that the tube 22 remains still immersed in the liquid steel 8 of the mold . By raising the distributor, the center O of the fixed plate 18 is raised, and consequently the position of the avoidance circle 38. FIG. 3 shows a cross-sectional view of the tube changing device of the invention. The cylindrical plate 18 is taken between two plates of refractory insulating material 44 which can be an integral part of the plate 18. The plates 44 possibly have a metal casing on their outer face, or even on both. A screw 46 or any other blocking means keeps the two plates 44 and the cylindrical plate 18 against the frame 16 in application. A rotor 48 is mounted rotating on cylindrical bearings 50 of the frame 16. The rotor 48 consists of two flaccid

52 interconnected by the transverse bar 34 forming the thrust pin which actuates the new tube during its installation. In the configuration illustrated by the example each flange 52 is provided with a rod 54 which passes through a bean-shaped light 56 pierced in the frame 16. The two fingers 54 are connected to a drive fork 58 which is itself integral of the rod of the jack 36. The jack 36 is double acting. It makes it possible to pull and push the fork 58 and therefore to make a back and forth movement in rotation with the finger 34. During this movement the two axes 54 describe an arc of a circle of approximately 90 ° around the axis XX of the cylindrical part 18. This is the reason why the jack 36 is articulated with respect to the base plate about an axis 60 so as to allow its angular movement Note that the orifice 20 which passes through the cylindrical plate 18 can be cylindrical, as in the embodiment shown, but it can also have a section which widens. In this case the runner at the entrance to the tube 22 has a corresponding flared shape in order to maintain the continuity of the section of the runner.

On the other hand, means are provided for immobilizing in rotation the cylindrical plate 18 relative to the frame 16. In fact it is subjected to relatively large rotational forces exerted by the friction forces of the plates 24 of the tubes during their rotation.

FIG. 3 makes it possible to observe an exemplary embodiment of the means for pressurizing the plates 24, tubes such as 22. These means comprise rockers 36 articulated at their central part on spherical head screws 62 mounted in the frame 16 At their outer end the rocker arms 36 are pushed by springs 64. At their inner end, which may possibly have a concave shape which fits on the outer face of the plates 24, the rocker arms 36 exert a radial action directed towards the axis XX of the cylindrical plate 18. At least one pair of rocker arms is provided, and preferably several pairs in order to guarantee an application force distributed along the plates 24.

The puddles 52 of the rotor 48 advantageously have a diameter greater than that of the fixed plate 18 to serve as lateral guidance for the tube. One of the flanges 52 of the rotor 48 has two notches, namely respectively a notch for introducing the new tube and a notch for removing the used tube. These notches are intended to allow the introduction of the new tube and the extraction of the used tube from the face of the mold, that is to say in other words to allow it to be introduced into the insertion position and to extract it from the evacuation position by moving it in a direction perpendicular to the large dimension 30 of the mold (see FIG. 1). (parallel to the cylinder axis). Retention means are provided in order to keep the new tube 22a in its insertion position. These means consist of a curved sheet 66 disposed on one side of the frame. On the other side of the frame there is provided only a lug placed at the lower position of the tube to allow its introduction. Identical retaining means are provided in the evacuation zone in order to keep the used tube in the extraction position.

The operation of this device is as follows. When it is desired to carry out a tube change, the tube which is in the casting position being worn or obstructed, one begins by introducing a new tube 22a in the insertion position, represented on the left in FIG. 1. At this moment the actuating finger 34 is located at the upper part of the fixed plate 18, near the internal nozzle 10. The introduction of the new tube 22a can be made, as in the embodiment described, according to the front face of the mold, which allows easy handling of the tube. However, it is also possible, as an alternative embodiment, to introduce the new tube in another direction, for example radial with respect to the fixed plate. It is then necessary to provide retaining means adapted to this new direction. The new tube 22a being in place in the retaining means, the actuator 36 is actuated which exerts a tensile force on the fork 58, 54 from right to left, according to FIG. 1 so as to drive the rotor 48 in rotation counterclockwise. It should be noted that the fork 58 distributes the force of the jack on the two axes 54 so that the forces are symmetrical. The actuating finger 34 pushes the plate 24a of the new tube 22a. This plate 24a is advantageously made contiguous with the plate of the used tube 22 so that there is no gap between them allowing the passage of the liquid steel. It is possible to close the runner beforehand by means of the stopper 12. It is also possible, taking into account the absence of gap between the plates, to carry out a tube change without closing the runner.

When the used tube 22 arrives in the discharge position 22b, the new tube 22a has replaced it and the casting of the metal can continue normally. There is all the time necessary to remove the used tube 22b which is kept in the means of restraints that have been described previously. The jack 36 is then actuated in the other direction so as to return the finger 34 to its initial position. The cycle can then start again for a new tube change.

Claims

1. Tube changing device for a continuous steelworks distributor comprising: - a frame (16) mounted on the distributor (2), refractory pieces (10, 18, 22) which define a flow channel for the passage of the steel from the distributor (2) to a continuous casting mold (28) having a large dimension (30) and a small dimension (31), these refractory parts comprising at least one fixed plate (18) and one tube ( 22) comprising a plate (24) at its upper part, pressurizing means (36) for applying the plate (24) of the tube (22) against the fixed plate (18), a position for introducing a new tube (22a), a pouring position and a position for discharging a used tube (22b), guide means (18, 48) allowing the new tube (22a) to pass from the insertion position to the casting position and the used tube (22) to move from the casting position to the discharge position, actuating means (34, 36) for passing the tube n euf from the insertion position to the pouring position and the used tube from the casting position to the discharge position, characterized in that: the insertion position, the casting position and the discharge position are arranged around a convex cylindrical surface (18) having a horizontal axis (XX) perpendicular to the large dimension (30) of the mold (28), this cylindrical surface constituting the periphery of the fixed plate, the plate (24) of the tube (22) has a concave cylindrical shape which adapts to the convex cylindrical surface (18) so as to maintain a tight seal between these surfaces when the new tube passes from the insertion position to the pouring position and from the passage of the used tube from the pouring position to the discharge position by a rotational movement around the axis (XX) of the cylindrical surface (18).

2. Device according to claim 1 characterized in that the new tube (22a) is entirely out of the steel (8) of the mold (28), when it is in its insertion position and in that the used tube (22b) is entirely out of steel

(8) of the mold (28) when it is in its evacuation position.

3. Device according to any one of claims 1 and 2 characterized in that the actuating means comprise a rotor (48), mounted rotating around the horizontal axis (XX) of the cylindrical surface (18), this rotor (48) comprising a finger (34) which pushes the new tube (22a) under the pressurizing means (36).

4. Device according to claim 3 characterized in that the finger (34) performs a back-and-forth movement to resume a new tube (22a).

5. Device according to any one of claims 1 to 4 characterized in that it comprises first retaining means which allow to maintain the new tube (22a) in its insertion position and second retaining means which allow hold the used tube (22b) in its evacuation position.

6. Device according to claim 5 characterized in that the guide means and the retaining means are designed so as to allow the introduction of the new tube (22a) and the discharge of the used tube (22b) in a direction perpendicular to the large dimension (30) of the mold.

7. Device according to any one of claims 1 to 6 characterized in that the means for pressurizing the plate (24) transmit radial forces to the back of the plate.

8. Device according to any one of claims 1 to 7 characterized in that the edges of the plates are produced so as to ensure contiguous contact so as to leave no gap between two successive plates during the passage of the seal opposite the pouring orifice.

9. Device according to any one of claims 1 to 8 characterized in that the cylindrical plate comprises means for locking in rotation relative to the chassis (16).

10. Method for changing the distributor of a continuous steelworks distributor for replacing a used tube with a new tube, in which a new tube is put in place in a tube changing device, then pushed into the position of casting, while simultaneously the used tube is pushed from the casting position to a discharge position, characterized in that: the new tube is placed in the tube changing device in a position where the tube has not no contact with mold steel

(28), the new tube is brought to its casting position by a rotation about a horizontal axis (XX) perpendicular to the large dimension of the mold, which has the effect of causing the used tube to rotate around it. same axis and to bring it into a position where the tube has no contact with the mold steel and from which it can be extracted from the tube change,

11. Method according to claim 10 characterized in that the distributor (2) is raised enough so that the circle (38) which will be described by the end of the new tube (22a) and the used tube (22b) avoids the edge (40) of the mold, but without the pouring tube (22) ceasing to be immersed in the liquid steel (8) of the mold (28).

12. Method according to one of claims 10 or 11 characterized in that one puts the new tube (22a) in the tube changing device in a substantially horizontal position, that brings the new tube to his position of poured by a rotation substantially 90 ° around a horizontal axis (XX) which has the effect of causing the used tube to rotate substantially 90 ° around this same axis; and in that the used tube is extracted from the tube changing device in a substantially horizontal position.

13. Plate-tube assembly for a device according to any one of claims 1 to 9.