MXPA97000088A - Side side for a machine for the constant colada of a metal plate delg - Google Patents

Abstract

The present invention relates to a side face for a continuous casting machine of thin sheet that is constituted by a frame, in which two cylinders are mounted to rotate in opposite direction, by two side faces, located on each end of the cylinders, and elements for applying with contact pressure the lateral faces on the ends of the cylinders, which cooperate with the lateral faces to delimit a continuous casting mold in which a given amount of liquid metal is kept, comprising this side face a plate of non-metallic refractory material that comes into contact with the ends of the two cylinders, with a metal part that allows fixing the side face to the frame of the machine for continuous casting, characterized in that said metal part is constituted by a belt that surrounds the plate of refractory material only on its periphery

Description

SIDE SIDE FOR A MACHINE FOR THE CONTINUOUS PLASTER OF A THIN METAL SHEET The invention relates to a side face for a machine for the continuous casting of a sheet of thin metal, which is constituted by a frame, in which they mount two mobile walls, like two cylinders that rotate in opposite directions and two lateral faces placed in each one of the ends of the cylinders to delimit a mode of continuous casting in which a given quantity of liquid metal is stored. The classic continuous casting in thin slabs in a mold with fiwalls does not allow to obtain a thickness of less than approximately 50 mm. When it is desired to obtain products with a lower thickness, it is necessary to subject the slabs that exit continuously from the casting mold to rolling. For this reason, it has been trying for several years to develop continuous thin film casting processes, whose purpose was to directly obtain products whose thickness can be reduced up to 3 mm and less. Thus the compulsory hot rolling operation is avoided in the currently used processes. This results in a simplification of the production and a reduction in the amount of energy needed, which allows the sale price of the finished product to be lowered.

A machine for the continuous casting of a thin sheet of metal generally bears two mobile walls that face and delimit a mold with movable walls. The liquid steel coming from the distributor is introduced into this mold by means of a nozzle that has its proper geometry. A machine for the continuous casting of a thin metal sheet of this type is already known (from EP 0 546 206). This machine is constituted by two rollers with their horizontal and parallel axes that turn in the opposite direction. Two side faces are disposed at each end of these two rollers to determine the continuous casting mold into which the liquid steel is introduced from the distributor. The lateral faces are applied by a mechanical system that can be constituted by springs or by jacks acting against the end of the cylinders to achieve a tightness for the liquid steel. The side faces can be preheated before casting, depending on the mode of operation of the machine and the materials that constitute them. According to this document, the side faces are constituted by a base plate of refractory material, by an element of ceramic material that comes into contact with the face or rubbing surface of the end of the cylinders and which is embedded in the base plate. The assembly is mounted in a metal envelope that covers the back face of the base plate leaving only the ceramic element free. It is the bottom of this envelope that secures the. transmission of the pressure exerted by the mechanical system located behind the lateral face and allowing the watertight application, that is, impermeable of the lateral face against the cylinders, in order to avoid any leakage of liquid steel between these and the side walls. However, in a side face of that type, the presence of the metallic bottom of the envelope poses several problems. During the continuous casting, it causes the thermal flow that comes from the liquid metal and that passes through the plate of refractory material, a significant increase in the temperature of the bottom of the envelope. In the case where no device is provided for the cooling of the envelope, this increase in temperature gives rise to a deformation of the bottom, such as, for example, pumpage, that is, curvature. This deformation, among other things, is responsible for a defective transmission of the pressure exerted by the mechanical system on the back of the refractory plate. Because the bottom is deformed, pressure is not applied evenly on the refractory material plate, but it is concentrated in certain points of the same. For example, if the plate is pumped or curved, the bottom of the metal shell will only be applied to the plate of refractory material at the top of this pumped area. The concentration of the resulting restriction can go to the breaking of the plate of refractory material. The deformation of the envelope can also cause a change in the parallelism of the front face of the side face (refractory material) with its back face (metal bottom). Due to this modification of parallelism, the friction surface is no longer applied uniformly, ie with a constant pressure on the end of the cylinders. This phenomenon can lead to an infiltration of liquid steel between the cylinder and the rub surface of the side face. The installation of a system for cooling the metal casing and particularly the bottom of this casing makes it possible to limit the drawbacks described above, however, it causes a cooling of the surface of the refractory material of the side face that comes into contact with the liquid steel . This widens the coagulation phenomena, that is, the setting of the steel on this surface and may impair the good development of the casting. Also, during the manufacture of the side face, it is difficult to obtain a good parallelism between the front face (refractory material) and the back face (metal bottom). In effect, the base plate of refractory material is cemented inside the metal shell to keep it in place.

The cement is baked in accordance with a thermal cycle that can exceed the level of 200 ° C. This cycle of baking causes a deformation in the metal casing that destroys the parallelism that existed before the baking of the cement. It is not easy to re-establish the parallelism between the front face and the back face by means of a new rectification, since it is necessary to make a lubrication during this rectification, which moistens the cement, so that it must be baked again. The present invention has precisely for its object a side face for a machine for the continuous casting of a thin sheet that remedies the drawbacks of the prior art, same that we exposed above. This side face must allow the transmission and distribution in equal form of the applied pressure exerted on its front face to avoid any risk of leakage of liquid steel. It must also allow the assurance of a good parallelism between its front face and its back face. These results are obtained, according to the present invention, by means of the system, according to which, the metal part that allows to fix the side face on the frame of the continuous casting machine is constituted by a belt that surrounds the plate of material refractory only in its periphery. This solution allows both a good geometric maintenance of the refractory material plate, a fixed fixation of the lateral face on the frame of the continuous casting machine, and a good parallelism between the two sides of the side wall, whatever be the temperature. This solution also makes it possible to produce a side face made entirely of refractory material at the level of the whole of the zones that are in contact with the liquid steel or with the cylinders, as well as with the pressure-applying device. The assembly of the metallic belt and the refractory plate can be carried out by foundations or by hot-sinking. In the case in which the assembly is secured by means of a foundation, preferably the metal belt and / or the refractory material plate has grooves or recesses that can be filled with cement to ensure a better maintenance of the refractory plate in the belt. The plate of refractory material is cemented by zone in the metal belt. The fixing cement, also in this case, may not be arranged in the entire contour of the piece of refractory material depending on the shape of the metal belt. For example, in the case where the inner shapes of the belt and the plate of refractory material are constituted by two circular arcs, concentric to the cylinder, the differences in expansion between the belt and the plate of refractory material impose the measure of not cement the entire contour of the plate, in order to avoid the cracking of the latter. Indeed, in this configuration, the presence of cement on both sides of the level of the axis of the cylinders causes a high level of congestion or clogging of the plate of refractory material at this level. The belt is made of metal (cicero, molten material or other), whose coefficient of thermal expansion is greater than that of the refractory material that constitutes the plate. Thus, at elevated temperature, the metal expands further. The belt then causes the placement in the traction state of the plate of refractory material, which can go to the breaking of the same. The cement used can be, for example, a silica-aluminous cement with silicate binder. Its function is to keep the plate of refractory material in the belt in a permanent or temporary condition. Preferably, the flat condition of the back face of refractory material is at least 0.5 mm. In other words, the surface of the back face must be completely contained between two parallel planes with a distance between them of 0.5 mm maximum. The plate of refractory material can be constituted in one piece. It can also be made from different parts, in particular a friction zone and a central zone only in contact with the liquid steel contained in the continuous casting mold. The central zone is preferably made of a ceramic material with an acilutinant in the form of carbon. According to an advantageous characteristic, at least a part of the friction zone is situated below the plane defined by the axes of rotation of each of the two cylinders. The invention also relates to the side faces that are found in a continuous sheet thin casting machine, constituted by a frame, on which are mounted two cylinders that rotate in the opposite direction, with two removable side faces, placed in each one of the ends of the two cylinders, and with elements to apply with a contact pressure the lateral faces on the ends of the cylinders. It is characterized in that the elements for applying a contact pressure of the lateral faces on the ends of the cylinders comprise a plate that is applied on the rear face of the refractory plate without coming into contact with the metallic belt of this plate of refractory material , the thickness of the plate being greater than the thickness of the belt. Thanks to this characteristic, the pressure exerted on the lateral face and intended to ensure a tightness, that is, a tightness between the cylinders and the rubbing surface of this side face, is exerted by means of a piece that can be metallic and independent of the lateral face itself. Of course, this plate is subject to the flow of heat that passes through the plate of refractory material. Due to this, its temperature rises during the operation of the continuous casting machine. However, the elevation of this temperature of the metal plate is limited by the fact that a separate insulator (for example, a silica foam plate) can be introduced between the push plate and the side face itself, and that there is no thermal bridge between the metallic belt that holds the plate of refractory material and the thrust plate that applies the pressure to the back face of the plate of refractory material. Indeed, as previously mentioned, the thickness of the metal belt is less than that of the plate of refractory material, so that the surface of the belt is retracted or retracted with respect to the surface of the plate of refractory material. Furthermore, the invention relates to a device for the continuous casting between cylinders of thin metal products, which has two cooled cylinders that rotate in an opposite rotary direction, with two side sealing walls and supporting and pressure-applying elements of these walls. obturators against the edges of the cylinders, and characterized in that each sealing wall is constituted by a plate of hard refractory material surrounded by a metal belt, with which it is linked. Other features and advantages of the present invention will also appear on reading the following description, presented by way of illustration, of exemplary embodiments. In these drawings: Figure 1 is a highly schematic view, in perspective, of a casting machine of a thin sheet, between cylinders. Figure 2 is a perspective view of a first embodiment of the invention. Figure 3 is a sectional view of a detail of the plate of Figure 2. Figures 4 and 5 represent two other variants of embodiment. Figure 6 is a sectional view. Figure 7 is a sectional view of another embodiment variant. In Figure 1 a schematic perspective view of a thin film casting machine has been represented. It has two cylinders, two that rotate in the opposite direction, as illustrated schematically with the arrows 4, around the horizontal axes 6. Some plates 10 that are applied against the ends of the cylinders, they constitute a mold, in which the liquid steel is emptied. FIG. 2 shows a first embodiment of a side wall for a continuous thin film casting machine according to the invention. This side wall, identified by the general reference number 10, is constituted by two parts, namely a plate of refractory material 12 and a metal belt 14. As can be seen, the plate of refractory material has a shape, which it is adapted to that of the cylinders of the machine for continuous casting. It has two major sides basically in the form of an arc of a circle, whose center of curvature is situated on the central axis of the casting machine cylinders. The plate 12 has a smaller side in its lower part, and a larger side in its upper part. The plate 12 is maintained by a metal belt 14 which, in the illustrated embodiment, surrounds the plate 12 in its entire contour, and the belt can be mounted especially by means of clamping. The metal belt 14 carries fasteners such as screws, bolts, pins or other analogous auxiliaries that allow it to be fixed on the frame of the machine for continuous casting. Considering that these fastening elements are classic, they have not been represented in the figure. As can be seen, the plate of refractory material 12 has a thickness that is greater than that of the metal belt 14. In this way, the refractory material extends over both sides of the belt. A side face according to the invention has been developed, in which the metal belt was in the retracted position by 3 mm in relation to each of the front and rear faces of refractory material 12. In other terms, the thickness of the plate of refractory material was 6 mm higher than that of the metal belt. As can be seen in Figure 3, which represents a cross-sectional view of the metal belt 14 and a part of the plate of refractory material 12, the metal belt 14 carries a groove 14a, while the plate of refractory material carries a slot 12a. The grooves 12a and 14a are filled with a cement 16 which ensures the fixing of the plate 12 in the belt 14. A pushing plate 15 makes it possible to transmit an application force transmitted by application elements 17. It is noted that the thickness of the plate 12 is greater than that of the metal belt 14. In this way, there is no thermal bridge between the thrust plate 15 and the belt, nor between the belt and the edge of the cylinder 2. In the embodiment shown in the Figure 2, the plate of refractory material 12 is constituted by a single piece. Figure 4 shows a plate 12 consisting of two parts, namely an area 18 that carries the part of the plate that works in friction 11, and a central area 20. The friction zone 18 is elaborated from a refractory material having good frictional characteristics with a metal, especially a long duration and a good coefficient of friction, for example, a material that carries at least 15% boron nitride. The central zone is constituted by a part of the zone of the refractory plate that is in contact with the liquid metal. For this reason, it must present a very good resistance to corrosion, caused by steel. For example, it can be constituted by a ceramic material based on a carbon binder. In the exemplary embodiment shown in FIG. 4, the friction zone 18 is constituted by a single element. This element basically has a Y-shape. It leads to the friction zone 18, which is constituted by a concentric crown arc with a roller and a concentric crown arc with another roller. These two arms of the Y meet in their lower part to form a central zone. As can also be seen in Figure 4, a part of the friction zone is located below the level of the axis 22 of the two cylinders of the continuous casting machine, schematized with a mixed beam, that is, a trace of points and dashes (see Figure 1). The end of the rubbing zone located below the axis of the cylinders in the solidification zone of the sheet ends in a slack element 24, of at least 2 mm, which may be a chamfer or a rounded section so that the sheet, after solidifying does not come into rubbing with a heel of refractory material 26 located below the slack element 24. The edges of the friction zone 18 located on the side of each of the two cylinders carries a chamfer 28, or a rounded area of a size of at least 2 mm by 2 mm, in order to limit the level of mechanical stresses exerted at the level of these edges. In the absence of such a chamfer, a flaking or systematic flaking of the edges is noticeable., which in the long run may give rise to infiltrations of liquid metal. Considering that an airtight state is necessary between the friction zone 18 and the cylinders, it is necessary to create a flat situation of that plane which is constituted by the assembly of the friction zone 18, and which will be at least 0.5 mm. This imposes a parallelism between the plane of the friction zone 18 and the rear part of the refractory plate of at least 0.5 mm. However, following the machine for the continuous casting and the fixing device of the metal belt 14 on the frame of this machine, the plane of the rubbing surface 18 can also be parallel with respect to the plane of the application device of the Pressure. Likewise, for the same reasons for transmitting the stress of transmitting the pressure on the plate of refractory material 12, the flat state of the rear face of the latter must be at least 0.5 mm. FIGS. 5 and 6 show a variant embodiment of a side face for a continuous casting machine according to the invention. In this embodiment, the friction zone is constituted by four elements 30 in the form of crown arcs concentric to the cylinders, and of a block 32 which is joined to the sections of the crown 30. The block 32 carries, like the friction zone 18 in Figure 3, a part located below level 22 of the cylinder axis. It will also be noted that the crown arches 30 and the central area 20 are maintained in the metal belt 14 by three cemented zones 34. Indeed, the differences in expansion between the metal belt 14 and the refractory materials constituting the central area 20 and the elements 30 and 32, respectively, impose the measure of not cementing the entire contour of the plate 12, in order to avoid the cracking of the latter. The rest of the contour of the plate will be trimmed, for example, with fibers 36. Finally, an embodiment variant is shown in Figure 7, in which the plate 12 of refractory material comprises an independent rear plate 38, constituted by a non-metallic refractory material. This plate 38 serves as support for the other elements that have been described above, namely the crown arches 30, the central block 32 and the central area 20. All these elements can be located simply above the back plate 38, or they can also be fixed on this plate, for example, by means of a silica-alu cement or other cement.

Claims (18)

1. CLAIMS 1. A side face for a continuous sheet thin casting machine that is constituted by a frame, in which two cylinders are mounted to rotate in the opposite direction, by two lateral faces, located at each end of the frames. cylinders, and elements for applying with contact pressure the lateral faces on the ends of the cylinders, which cooperate with the lateral faces to delimit a continuous casting mold in which a given quantity of liquid metal is kept, this side face comprising a plate of non-metallic refractory material that comes into contact with the ends of the two cylinders, with a metal part that allows fixing the side face to the frame of the machine for continuous casting, characterized in that said metal part is constituted by a belt which surrounds the plate of refractory material only on its periphery.
2. 2. The side face according to claim 1, characterized in that the belt and / or the plate of refractory material has grooves or anchoring elements that can be filled with cement to ensure a better support of the refractory plate in the belt.
3. 3. The side face according to any of claims 1 and 2, characterized in that the plate of refractory material is cemented by zones, in the metal belt.
4. 4. The side face according to any of claims 1 to 3, characterized in that the flat state of the rear face of the plate of refractory material is at least equal to 0.
5. 5 mm. The side face according to any of claims 1 to 4, characterized in that the plate of refractory material carries a friction zone and a central zone located in condition in contact with the liquid metal contained in the mold for continuous casting.
6. 6. The side face according to claim 5, characterized in that the central area is made of a ceramic material with carbon binder.
7. The side face according to any of claims 5 and 6, characterized in that a part of the friction zone is located below the plane defined by the axes of rotation of each of the two cylinders.
8. The side face, according to claim 7, characterized in that the part of the friction zone located below the plane defined by the axes of rotation of each of the two cylinders ends in an area out of phase with the plane of friction that has a depth of at least 2 mm, this area being constituted phase-shifted, for example, by a chamfer or a rounded part.
9. The side face according to any of claims 5 and B, characterized in that the friction zone is constituted at least in part by elements forming crown arcs concentric to the cylinders.
10. The side face according to any of claims 7 and 9, characterized in that the parallelism between the plane of the surface of the part that works by rubbing the friction zone and the rear face of the refractory plate is at least 0.5 mm .
11. The side face according to any of claims 5 and 10, characterized in that the flat state of the friction zone is at least 0.5 mm.
12. 12. The side face according to any of claims 1 and 11, characterized in that the plane of the upper surface of the metal belt is retracted at least by a distance of 3 mm with respect to the plane of the friction surface.
13. 13. The side face according to any of claims 5 and 12, characterized in that the edge of the friction zone (18) located opposite the end of the cylinders ends in a zone of clearance of at least 2 mm depth, which may be This disconnection piece is constituted by a chamfer or a rounded part.
14. 14. The side face according to any of claims 5 and 13, characterized in that the friction zone is made of a material consisting of at least 15% boron nitride (BN).
15. 15. The side face according to any of claims 5 and 14, characterized in that the friction zone is composed of several joining elements.
16. 16. The side face according to any of claims 1 and 15, characterized in that the plate of refractory material comprises an independent back plate, constituted by a non-metallic refractory material that serves as support for the other constituent elements of the plate.
17. 17. Lateral side for a continuous thin film casting machine, consisting of a frame, in which two cylinders that rotate in the opposite direction are mounted and two removable side faces placed on each end of two cylinders, as well as elements to apply with a contact pressure the lateral faces on the ends of the cylinders, in which the two cylinders cooperate with the lateral faces to delimit a continuous casting mold in which a given quantity of liquid metal is kept, characterized in that the elements to apply a contact pressure of the lateral faces on the external of the cylinders comprise a plate that is applied on the rear face of the plate of refractory material without contact with the metal belt of this plate of refractory material, in which the thickness of the plate is greater than the thickness of the belt.
18. 18. The device for the continuous casting between cylinders of thin metal products, carrying two cooled cylinders that rotate in the opposite direction, with two side sealing walls and support elements and applying by pressing these sealing walls against the edges of the cylinders, characterized in that each wall is constituted by a plate of hard refractory material surrounded by a metal belt to which it is connected. EXTRACT OF THE INVENTION A lateral face for a continuous casting machine of thin metal sheet, constituted by a frame, in which two cylinders are mounted that rotate in the opposite direction, with two lateral faces placed on each of the ends of the machine. the cylinders and elements to apply contact compression the lateral faces on the ends of the cylinders. The cylinders cooperate with the side faces to delimit a mold for continuous casting in which a given quantity of liquid metal is stored. The side face comprises a plate of non-metallic refractory material that comes into contact with the ends of the two cylinders, a metallic part that allows to fix the lateral face to the frame of the continuous casting machine, while the metallic part is constituted by a belt that surrounds the plate of refractory material only on its periphery.