MXPA97006353A - Continuous or cue colada plant - Google Patents

Abstract

A rope casting plant for continuously casting a thin strip (1) of metal is equipped with a receptacle (4) for reception of cast iron having a pouring outlet (5) in front of which a surface can pass or circulate (8) casting to receive the laundry (3) in a thin layer that forms a rope (1), and has a support device (9) for the rope that receives the rope (1) from the surface (8) of wash. In order to make it possible to cast metal strips (1) without the risk of breaking, especially at high casting rates, the rope support device (9) has an essentially flat and substantially horizontal surface (22) supports the rope (1), into which pass channels (21) of passage or gas outlet that can be connected to a driving installation of the g

Description

"PLANT OE COLADA CONTINUES OR IN STRING" Description of the invention The invention relates to a rope casting plant for continuously casting a thin metal strip, in particular a steel strip with a thickness of less than 20 mm, preferably from 1 to 12 mm, with a a casting receiving container having a pouring mouth in front of which a casting surface can pass or circulate to receive the laundry in a thin layer forming a cord, as well as with a support device for the rope, the which receives the rope from the casting surface, and is further related to a method for the operation of a rope casting plant of this kind. A plant for the rope casting of a thin strip of metal of the type described at the outset is known, for example, from European patent EP-A-0 526 886. According to that state of the art, the metal casting or either it is placed on a rolling roller or on an endless track chain formed by links and, after the formation of a strip-shaped rope shell, it is transferred from the rolling roller or the track chain to a installation of rope support aligned approximately horizontally, which is configured as a conveyor belt REF: 25402 endless. Upon being transferred to the transportation device, the metal strip still has an upper side formed by casting, - it has only been solidified by its lower side, with which it was in contact with the rolling roller or with the endless band. The transport device is provided with a cooling, so that when leaving the transport device, the metal strip is already fully solidified. The transport device configured as an endless belt is formed by a net or grid, whereby between the intermediate spaces of the net or grid air is blown or sprayed water against the rope, in order to cool the rope intensively, that is, the underside of the metal strip. A fixed location intermediate support is provided between the surface for receiving the laundry and the transportation device, in order to bridge the space between the receiving surface of the laundry and the transportation device. An installation of this kind has the disadvantage that the transport device formed by an endless belt has many moving parts that have to be arranged directly adjacent to the casting zone of the metal strip. These parts are subjected to great efforts and therefore to a great wear during the rough operation of the foundry. Also disadvantageous is the fact that there is necessarily a relatively large intermediate space between the casting surface and the transportation device, which has to be bridged by an intermediate support. Therefore difficulties arise during the transportation of a metal strip in which only a very thin layer of the underside of the strip has solidified, and which in view of the high temperature is still very soft, since the underside solidified of the strip is seriously exposed to breakage due to the friction forces that occur between that lower side and the intermediate support. These friction forces are especially high if fire-proof graphite plates or plates of fire-proof material as usually provided are provided to create the intermediate support. According to the European patent EP-A-0 526 886, the transport device can also be formed by a table of fixed location, for which the metal strip is transported on the table by means of driven support rollers. However, in practice it is barely possible to make a support of the strip by means of rollers, since due to the reduced thickness and the reduced shape stability of the metal strip, the spokes of the rolls have to be extremely small so that they can be arranged as close as possible to one another. Regardless of the above, there are also intermediate spaces between the casting surface and the transport device and between the driven support rollers, due to the spokes of the rollers, spaces that as always would be necessary to bridge by means of intermediate supports, which at their they would once again promote the danger of the formation of breaks in the strip. A rope casting installation of the type described at the outset is also known from the European patent EP-A-0 568 211. There is directly next to the casting surface a scraper that receives the strip from the casting surface and the drive to a transportation table arranged below. Both the doctor blade and the transport table are of fixed location and are arranged aligned approximately horizontally. In this case, too, the hot and still very soft strip that emerges from the casting surface is highly exposed to breakage due to the friction forces that occur, so that adhesion of the strip can occur, especially the principle of the strip, on the scraper or on the transportation table. This can lead to damage to the strip and even to the stoppage of the casting operation. But a dent in the strip can also occur. The invention has the purpose of avoiding these disadvantages and difficulties, and the task of creating a rope casting plant of the type described at the beginning is proposed, as well as a procedure for the operation thereof, without the danger of break, allow to cast with high performance capacity metal strips whose shell of the rope is still very thin when being separated from the casting surface. In particular, casting with a high casting speed must be possible. In addition, the rope casting plant should allow a particularly good heat transfer between the partially solidified metal strip and the rope support device that follows the casting surface, so that even when casting at high casting speeds a rapid solidification is achieved through the strip. This task is solved according to the invention by equipping the rope support device with an essentially flat and substantially horizontal surface that supports the rope, a surface on which gas passage channels open, which are connected to an installation conductive gas.

European Patent EP-A-0 629 459 discloses a method for manufacturing sheets or sheets of metal. According to this process molten metal is poured on a cooling roller through a nozzle, in which the liquid metal solidifies immediately. After a contact of the sheet or sheet with a peripheral part of the cooling roll, the sheet is separated from the cooling roller by the tangential blowing of air, and moves away from the cooling roller by transporting it on an endless conveyor belt. The metal sheet is adhered by suction to the endless conveyor belt by suctioning by air, for which the endless conveyor belt is permeable to the passage of air. The sheets have a thickness whose magnitude is 25 μm and an amorphous solidification occurs at the moment of the impact of the liquid metal. The sheet of solidified metal is brittle and tends to float, and due to its marginal weight it would rise immediately from the endless conveyor belt and the cooling roller, which is avoided by sucking it against the endless conveyor belt and holding it in tension with respect to to the cooling roller. In accordance with the invention, the gas drive installation is conveniently configured as a device to establish an overpressure in the gas to be conducted through the gas passage channels, such as inert gas or air. In this way, the formation of a gas cushion between the surface of the rope support device and the lower side of the metal strip is achieved, so that an absolutely safe process of initial pouring of the laundry is possible without the danger of the metal strip adhering or remaining lying, and therefore without the danger that transverse undulations of the strip could occur or a retention of the strip occurs. According to a preferred embodiment, the gas drive installation is configured as a device for establishing a negative pressure (vacuum) in the gas to be conducted through the gas passage channels. In this way it is possible to slightly suck the metal strip against the upper side of the rope support device during continuous operation, ie after the initial pouring of the laundry, so that a particularly good contact between the strip of the laundry is guaranteed. metal and the rope support device, and with it a particularly effective cooling. By means of this it is possible to strain with high casting rates, that is, at a high casting speed, or to cast a slightly thicker metal strips with reduced times until the solidification of the strand. The invention makes it possible to suffice with a very simple rope support device, and this is a rope support device configured as a plate arranged in a rigid manner, ie without moving parts. According to a preferred embodiment, the rope support device is formed by a material of good thermal conduction, in particular of copper or of a copper alloy, and is conveniently provided with an internal cooling, in particular with a internal cooling based on liquid. According to a preferred embodiment, the rope support device is constituted by two parts, and these are a scraper separator of the rope that is directed to the casting surface and which ends directly next to it, and a cooling table that immediately follows the doctor blade in the direction of stretching of the rope, being that both the scraper separator of the rope as well as the cooling table, are provided with passage channels for gas. In order to keep the gas consumption low, or to ensure that a small capacity gas installation is sufficientbK. , the rope support device will be suitably provided with lateral restraints that extend in the direction of stretching of the rope and encompass the longitudinal side edges of the rope. By this, a lateral leakage (loss) of the gas can be largely prevented by generating the gas cushion between the metal strip and the rope support device. Advantageously, the passage channels for the gas comprise, with their openings, which open to the surface of the rope support device a total section area of 0.01 to 20%, preferably from 0.1 to 5%, of the supporting surface. to the rope. Preferably, the openings of the gas passage channels that open onto the surface of the rope support device each have an area of the section from 1 to 50 mm2, preferably from 3 to 20 mm. A particularly advantageous generation of the mattress is ensured if the channels for the passage of the gas form with their mouths an acute angle with respect to the surface of the support device. It is advantageous if the mouths of the channels for the passage of the gas are directed such that a gas stream is formed which essentially moves in the direction of stretching of the rope. This gas stream is already formed at the mouths of the channels. Conveniently the sectional area of the openings forming the gas passage channels on the surface of the rope supporting device will be greater at the beginning of the rope supporting device than in the subsequent sections of the rope supporting device , which are in the direction of stretching of the rope, by means of which the critical initial pouring, that is to say, the start of the casting, during which the metal strip is particularly exposed, is facilitated. According to a preferred embodiment, the rope support device is provided with channels for a cooling agent arranged transversely to the direction of movement of the rope, and at least several of these cooling agent channels are in each case connected with a cooling agent feeder tube serving as a distribution branch, and with a cooling agent evacuation tube acting as a collector branch, which are disposed laterally of the rope support device. For this, it is advantageous for a coolant channel to be guided several times through the rope support device from the distribution branch, to finally end at the collector branch. In order to determine the position of the point at which the metal strip solidifies completely, or to influence the metallurgical / technological properties of the metal strip by modified cooling conditions, it is convenient to adjust the pressure between the bottom side of the string and the rope support device by means of corresponding suction and / or gas supply for regulation purposes. A method for starting a rope casting plant in which from a casting receiving container is continuously poured cast on a casting surface which flows under a pouring outlet of the casting recipient, and in which the casting solidifies in the casting surface under continuous formation of a rope, the rope, which is still still in a liquid state on its side away from the casting surface, continues to be transported from the casting surface to a rope support device in which it is supported and cooled, it is characterized by the fact that between the rope support device and the solidified lower side of the rope a gas cushion is generated, and this in particular only at the beginning of the rope. During the operation of the rope casting plant, from which a casting recipient is continually poured into cast iron on a casting surface which flows under a mouth of the casting recipient., and in which the laundry solidifies on the casting surface under the formation of a continuous cord, the cord, which is still still in a liquid state on its side away from the casting surface, continues to be transported from the surface of the casting. casting up to a rope support device where it is supported and cooled, a negative pressure (vacuum) and thus a particularly good adhesion of the side is conveniently generated between the rope support device and the solidified lower side of the rope. bottom of the rope on the surface of the rope support device. Between the solidified bottom side of the rope, which may be partially or completely solidified, and the rope support device, a gas cushion is advantageously generated in which an overpressure of 0.1 to 20 mbar prevails, preferably from 0.5 to 10 mbar. bar, with respect to the surrounding outside air pressure (atmosphere).

The negative pressure (vacuum) between the solidified bottom side of the rope and the rope support device will advantageously be up to 1000 mbar (vacuum), preferably between 5 and 100 mbar. In the following, the invention is explained in more detail on the basis of the drawing, in which a partially sectioned side view of a string casting plant according to the invention is shown in a schematic representation, and in figure 2 is shown in FIG. detail of figure 1 in enlarged scale. Figure 3 reproduces a cross section according to line III-III of figure 1, also in enlarged scale. Figure 4 shows, in analogous representation to that of figure 2, a modified embodiment. Figures 5 and 6 illustrate in diagrammatic representation once (figure 5) a partial view of a rope casting plant, and once (figure 6) a cut according to line VI-VI of figure 5. For casting a steel strip 1 with thickness 2 below 20 mm casting 3 is allowed to flow from a casting receiving container 4 through an opening 5 for casting of this container 4 on a casting roller 6. In the casting roller 6, which is provided with internal cooling, a very thin shell of rope 7 is initially formed, which is separated from the surface 8 of the casting roller 6 for transfer to a rope supporting device. which is generically indicated with the reference number 9. The rope support device 9 has a wedge-shaped squeegee 10 for separating the rope, a squeegee which with its pointed end 11 is directed directly against the casting surface 8. The squeegee for separating the rope connects to the casting surface in the region just next to the uppermost generator 13 of the casting surface, which is in the vertical plane 13 which traverses the turning axis 12 of the casting roller. Directly next to the scraper 10 for separating the rope is a cooling table 14 which complements the rope support device 9. Both the surface of the scraper blade 10 that separates the rope that receives the metal strip 1 with the solidified lower side, as well as the cooling table 14 that follows after the scraper separator of the rope are aligned approximately horizontally. The metal strip 1 arriving at the cooling table 14 still has a liquid surface 15, however, the solidified rope shell 7 of the metal strip 1 increases in thickness as it advances in its movement along the table 14 cooling, until finally at a point 16 of the cooling table 14 the strip 1 of metal solidified fully through. The scraper blade 10 of the rope and the cooling table 14 are made of a material of good thermal conduction, especially copper or a copper alloy, in order to ensure a good heat transfer between the metal strip 1 and the device 9 of rope support. Both the scraper blade 10 of the rope and also the cooling table 14 are provided with an internal cooling based on liquid, which is formed by channels 17 extending transversely to the longitudinal extension of the rope support device 9. The channels 17 are connected with pipes 18, 19 feeders and coolant evacuators, which are arranged parallel to the longitudinal extension of the rope support device 9, and to one side thereof. As can be seen in figures 5 and 6, in each case several channels 17 are connected in a conductive manner with a coolant supply pipe 18 and with a coolant evacuation pipe 19, in each case being driven a coolant channel 17 several times in the form of a meander through the rope support device 9. Additionallyboth the rope separating blade 10 and also the cooling table 14 are provided with gas channels 20 which also extend transversely to their longitudinal directions, and from which gas-flow channels 21 exit into the surface 22 of gas. the cooling table 14 and the scraper 10 separating the rope. It is not necessary that the coolant channels and / or the gas channels extend transversely to the longitudinal extension of the rope support device 9, they can also extend along or at any desired angle with respect to the longitudinal direction . The gas channels can be connected to a gas driving installation through gas pipes 23 arranged in the longitudinal direction of the rope support device 9, which installation is configured so as to put the gas inside the channels 20 of the gas. gas under pressure as well as under vacuum (negative pressure). By this it is possible to blow at will through the gas passage channels 21, such as inert gas or air, between the underside of the metal strip 1 and the surface 22 of the cooling table 14 or of the doctor blade 10. Separator of the rope. In this way friction between the metal strip 1 and the rope support device 9 is reduced to such an extent that the metal strip 1 is prevented from adhering or remaining lying on the surface of the doctor blade 10 or the cooling table 14. This in particular is of great importance during the initial pouring of the laundry, when the principle of the strip 1 of metal which is still very soft is pushed on the cooling table 14 above the scraper 10 separating the rope. Accordingly, the creation of the gas cushion is carried out particularly during the phase of the initial pouring of the laundry, that is, at the start of the laundry. By doing this, the forces acting on the support device 9 can be reduced or even compensated due to the weight of the metal strip 1. Conveniently the gas channels are arranged in an irregular manner and not in regular rows, in order to avoid marks, scratches or inhomogeneities, etc., in the metal strip 1. In the region of the edge of the metal strip, ie, along the longitudinal edges of the rope support device 9, flanges 24 or similar structures are preferably provided in order to achieve an intercepting effect, so that the gas consumption can be kept reduced by generating the gas cushion between the metal strip 1 and the rope support device 9. By creating a negative pressure (vacuum) by sucking gas (air) through the gas passage channels 21, a very good contact between the underside of the strip and the surface 22 of the gas is achieved. cooling table or scraper 10 separator of the rope, contact that after the initial pouring of the laundry - when the metal strip 1 already has a greater hardness or solidity - is no longer harmful, so that an effect is possible of cooling particularly good by the intensive thermal transfer that occurs because of good contact between the metal strip 1 and the cooling table 14 or the scraper 10 separating the cord. Because of this it is possible to strain at high casting rates. The invention makes it possible to take into consideration modifications of the casting rates (modifications of the thickness of the strip 2 and / or modifications of the casting speed) and continue to cast without problem. According to the embodiment shown in FIG. 3, the gas passage channels 21 are arranged in an inclined manner, and this in such a way that an air current is formed which moves in the direction of stretching of the rope ( direction of casting) 25 by placing the gas outlet channels 21 under vacuum (negative pressure). The invention is not limited to the embodiment shown in the drawing, but it can be modified, in different ways. For example it is conceivable to use some other device, for example a casting band or the like in place of the casting roller 6. A strictly horizontal alignment of the rope support device 9 is not required.; you just have to make sure that you can form a strip with the desired thickness. It is conceivable that some of the gas outlet or passage channels are connected to a separate gas drive installation, so that gas with different intensities can be fed or sucked along the longitudinal extension of the gas support device 9. rope. It is also conceivable to put some of the gas outlet or passage channels under gas overpressure, while simultaneously other gas passage channels are subjected to negative pressure (vacuum).

Claims (20)

1. CLAIMS OF THE PATENT 1. String casting plant for continuously casting a thin strip of metal, especially a strip of steel with a thickness of less than 20 mm, preferably between 1 and 12 mm, with a container for receiving of cast iron having a pouring mouth in front of which a casting surface can pass or circulate to receive the laundry in a thin layer forming a cord, as well as with a support device for the cord, which receives the cord of the casting surface, which is characterized in that the rope supporting device has an essentially flat and substantially horizontal surface supporting the rope into which gas passage or outlet channels that can be connected to a pipeline open. gas booster installation.
2. 2. Rope casting plant according to claim 1, characterized in that the gas driving installation is configured as a device to establish an overpressure in the gas, such as inert gas or air, which must be conducted to through the gas passage channels.
3. 3. Rope casting plant according to claim 1 or 2, characterized in that the gas drive installation is configured as a device to establish a negative pressure (vacuum) in the gas to be conducted to through the gas passage channels.
4. The rope casting plant according to one or more of claims 1 to 3, characterized in that the rope supporting device is configured as a rigidly arranged plate.
5. 5. Rope casting plant according to one or more of claims 1 to 4, characterized in that the rope support device is made of a material that is a good thermal conductor, especially copper or a copper alloy.
6. String casting plant according to one or more of claims 1 to 5, characterized in that the rope supporting device is provided with internal cooling, in particular internal liquid cooling.
7. String casting plant according to one or more of Claims 1 to 6, characterized in that the rope supporting device has a scraper separating the rope directed towards the casting surface and it ends directly against it, and a cooling table next to the doctor blade in the direction of stretching of the rope, being that both the separator blade of the rope and also the cooling table are provided with gas passage or outlet channels.
8. 8. Rope casting plant according to one or more of claims 1 to 7, characterized in that the rope support device is provided with lateral constraints that cover the longitudinal edges of the rope and Extension in the direction of stretching of the rope 9.
9. Rope casting plant according to one or more of claims 1 to 8, characterized in that the exit or passage channels for the gas cover with their openings which discharge into the surface of the rope support device in total an area of the section from 0.01 to 20%, preferably from 0.1 to 5%, of the surface of the support device supporting the rope 10.
10. Casting plant in a rope according to one or more of claims 1 to 9, characterized in that the outlet or passage channels for the gas have in each case in their openings opening into the surface of the device of rope support, an area of the section from 1 to 50 mm2, preferably from 3 to 2O mm2.
11. String casting plant according to one or more of claims 1 to 10, characterized in that the mouths of the outlet or passage channels for the gas form an acute angle with the surface of the device support.
12. 12. Rope casting plant according to claim 11, characterized in that the mouths of the outlet or passage channels for the gas are directed in such a manner that a gas stream is formed which substantially moves in the direction of stretching of the cord.
13. String casting plant according to one or several of claims 1 to 12, characterized in that the sectional area of the openings forming the channels for passage of the gas on the surface of the device The rope support is larger at the beginning of the rope support device than in the subsequent sections of the rope support device, which are in the direction of stretching the rope. 1 .
14. Casting plant according to one or more of claims 1 to 13, characterized in that the rope support device is provided with coolant channels arranged transversely to the direction of movement of the rope , and at least several of these cooling agent channels are in each case connected with a cooling agent feeder tube acting as a distribution branch and with a cooling agent evacuation tube acting as a collector branch, which are disposed laterally of the Rope support device.
15. String casting plant according to claim 14, characterized in that a cooling agent channel is conducted several times through the rope support device from the distribution branch, to finally open out in the collector branch.
16. 16. Process for the operation of a rope casting plant according to one or more of claims 1 to 15, characterized in that the pressure between the lower side of the rope and the supporting device of the rope rope is adjusted by corresponding suction and / or gas supply for regulation purposes.
17. 17. Method according to claim 16, for the start-up of a rope-casting plant, in which casting is continuously poured from a cast-iron receiving container onto a casting surface passing or circulating under a pouring outlet of the casting plant. casting recipient, and in which the laundry solidifies on the casting surface under continuous formation of a string, the string, which is still still in a liquid state on its side away from the casting surface, is continued transporting from the casting surface to a supporting device for the rope in which it is supported and cooled, characterized in that a mattress is generated between the rope support device and the solidified lower side of the rope of gas, and this in particular only at the beginning of the rope.
18. 18. Method according to claim 16, for the operation of a rope casting plant, in which casting is continuously poured from a casting recipient onto a casting surface passing or circulating under a pouring outlet of the casting plant. casting recipient, and in which the laundry solidifies on the casting surface under continuous formation of a string, the string, which is still still in a liquid state on its side away from the casting surface, is continued conveying from the casting surface to a supporting device for the rope on which it is supported and cooled, characterized by the fact that a pressure is generated between the rope support device and the solidified lower side of the rope negative (vacuum), and with it a particularly good narrow fit of the bottom side of the rope on the surface of the carrier support device erda
19. 19. Method according to one or more of claims 16 to 18, characterized in that a mattress of the solidified lower side of the partially or completely solidified rope and the rope support device is generated. gas in which there is an overpressure of 0.1 to 20 mbar, preferably from 0.5 to 10 mbar, with respect to the pressure of the outside air surrounding the plant. Method according to one or more of claims 16 to 19, characterized in that a negative pressure (vacuum) of up to the solidified lower side of the rope and the rope support device is generated. 1000 mbar, preferably between 5 and 100 mbar.