MXPA00005095A - Device and process for producing a steel strip - Google Patents

Abstract

Device for producing a thin steel strip, comprising at least one or more continuous-casting machines (1) for casting thin steel slabs, a furnace device (7) which is suitable for heating and/or homogenizing a slab, and at least one rolling device for reducing the thickness of a slab which is conveyed out of the furnace device (7), a welding machine being arranged between the continuous-casting machine (1) or continuous-casting machines (1) and the rolling device (10), for the purpose of joining slabs together.

Description

DEVICE AND PROCESS FOR THE PRODUCTION OF A STEEL STRIP DESCRIPTION OF THE INVENTION The invention relates to a device for producing a thin strip of steel, comprising at least one or more continuous casting machines for melting slabs or thin plates of steel, a furnace device which is suitable for heating and / or homogenizing a slab, and at least one laminating device for reducing the thickness of a slab that is transported out of the oven device. The invention also relates to a process for producing a steel strip, in which the liquid steel is poured into at least one continuous casting machine to form a slab or plate and, using the heat of the casting, is transported through of a furnace device and, in a laminating device, is rolled to form the strip with a desired final thickness. A device of this nature is described in the application WO-A-97/46332. By this reference, it is considered that the content of this application is incorporated in the present application. The application proposes, among other things, to use a device of this nature for an endless rolling process. In the application, it is understood that an endless rolling process means a rolling process in which the slabs or plates, after passing through a preliminary rolling device, the strips are coupled together, so that it can be carried out an endless rolling process in a finishing laminator. In the step, it has been proposed to couple the slabs together by providing the end of a slab with a shape that is such that it can be coupled to the front edge of a next slab which is also provided with a suitable, frequently complementary shape. The devices that are required to do this are highly complicated and require considerable amounts of space. In addition, the slabs or plates to be coupled together are exposed to the atmosphere for a considerable period of time, with the result that the slabs are cooled and an oxide layer is formed on the slabs. An endless rolling process, particularly when applied to thin slabs, for example, slabs with a thickness of 100 mm or less, preferably 80 mm or less, provides the possibility of achieving a very high level of homogeneity of temperature during rolling. This advantage is to a considerable degree denied by a complicated coupling method as described above. The object of the invention is to provide a device that makes it possible to couple together the thin melted slabs, which have been optionally reduced in a preliminary manner, quickly and easily. This objective is achieved by means of a device that is characterized in that a welding machine is arranged between the continuous emptying machine or the continuous emptying machines and the laminating device, for joining the slabs or plates together. With a welding machine, it is possible to quickly join together the end faces, which are straight or have some other simple shape, or two plates that are to be coupled one to the other. A welding machine does not require much space, so that the plates to be joined together are only exposed to the atmosphere for a short period of time and therefore also only emit heat into the environment for a short time. Consequently, the use of a welding machine also contributes to the reduction of the amount of oxide that forms on the surface of the plates to be welded together. In order to avoid temporary storages, for example, in the form of a roll box, a preferred embodiment of the device according to the invention is characterized in that the welding machine is movable along a length of welding in the direction of the standard passage of the plates, through the device to the rolling device. By allowing the welding machine to move along with the plates that are going to be welded together, the plate, whether it has been reduced in size or not, and the strip can run at the same speed throughout the length of the device, taking into account the reduction in thickness. An additional embodiment of the device according to the invention is characterized in that the welding machine is displaceable in the direction of standard passage of the plates through the device towards the rolling device at a speed between 4 and 20 m / min., Preferably at a speed between 10 and 17 m / min. In an endless rolling process, the speed at which the plate enters the laminating device is, depending on the final thickness of the strip to be achieved and on whether this final thickness is reached or not in the austenitic, ferritic field, or mixed ferritic-austere aus, in the range between 4 and 20 m / min., more preferably in the range between 10 and 17 m / min. For the process to operate efficiently, the speed at which the welding machine is displaced is preferably equal to the speed, if appropriate taking into account a reduction in thickness, at which the plate is introduced into the laminating device. An additional embodiment is characterized in that the welding machine is an induction welding machine. This prevents the need to introduce into the weld, a welding material with a chemical composition that differs from the chemical composition of the plates to be welded together. This is particularly important for grades of low alloy steel in particular grades of IF steel. In addition, the performance of an induction welding machine is easy to control.

The heat transfer from the plates that have been welded together to the atmosphere is further limited by one embodiment of the device according to the invention which is characterized in that the welding machine is provided with means for limiting heat transfer from the plates to the environment. It has been found that, by using plate thicknesses and rolling speeds that occur in practice, the process can be successfully operated, using even continuous, multiple strand casting machines, with a furnace device which is characterized in that the overall length of the oven device is between 250 and 330. The plates to be welded together are moved towards a desired position one with respect to the other using positioning means, after which the plates are welded together, by means of the welding machine, because the means of placement and the movable welding machine can not be completely accommodated in an oven and it is inevitable that during welding the plates to be welded together will be cooled in the area of the weld. In order to produce the desired temperature homogeneity of the plates, a further embodiment of the device according to the invention is characterized in that the oven device comprises a first zone and a second zone which, as seen in the direction of passage standard, they are placed one behind the other, and the welding machine is accommodated between the first and second zones. The furnace device preferably has means for transferring through the plates at an accelerated rate in order to be able to empty the furnace device rapidly, after an interruption to the process, whether planned or not, and before another interruption occurs. It has been found that a good welding, with little cooling of the plates, can be obtained in one embodiment of the device according to the invention which is characterized in that the first zone and the second zone are placed at a separated distance which, measured in a standard direction of passage is 4-25, preferably 5-17. In order to return the plates that have been cooled during welding to the correct temperature, a second zone is placed downstream of the welding machine, as seen in the standard passage direction, whose second zone, according to the invention , is characterized because it has a length between 25 and 100 m. It has been found that, depending on the speed at which the welding can be carried out in the weld length, sufficient temperature homogenization can be achieved with such a length. In the second zone, the welded plate achieves a temperature homogeneity that is desired for the subsequent rolling process. It has been found that a good level of homogeneity is achieved within the available time and length of the second zone in a device mode according to the invention which is characterized in that the second zone comprises a reheat section and a side heat section. to side. In order to minimize the cooling during the welding process in which the plates to be welded together are exposed to the environment, it is preferable that the means for limiting the transfer of heat from the plates to the device be accommodated in the device. environment, between the first zone and the second zone. The current continuous casting machines which are used in practice to melt or empty thin plates have a casting speed of about 6 m / min. for a plate thickness between 50 and 100 mm. For an endless rolling process, it is desirable that the speed at which the plate enters the rolling device falls in the range of between about 10 and about 20 m / min, preferably in the range between 12 and 16 m / min. . In order to build a bridge between the casting speed and the desired input speed, it is proposed to use a multi-billet casting machine or a plurality of casting machines next to one another. In this case, it is preferable that the device is provided with a second oven device for accommodating a plate. In this case, there is a dedicated furnace device available for each casting machine or for each billet, and there is no need to include complicated transverse or longitudinal conveying means for the plates in an oven. Currently, there are facilities in use in which the aforementioned difference in the speed between the casting speed and the speed of entry to the rolling device arises. This difference in speed can also arise in new installations or in facilities that are going to be newly built, for example in cases where, for whatever reason, a single casting machine or a double-billet casting machine is initially used. In the case of a new continuous dump machine that is subsequently installed or a second strand that is added, it is preferable for at least one oven device and the second oven device to be provided with conveyor means to transport a plate from the second oven device towards the oven device. In this case, the existing installation can be retained and a second baking device is placed in line with the new continuous emptying or emptying machine or the second billet. The conveyor means can be used to transport plates from the second furnace device to the furnace device, after which they can be coupled together in the welding machine. In relation to the limited space required, which is particularly important in a multi-billet casting machine, it is preferable that the conveyor means comprises a so-called parallel conveyor. An alternative is a tilting conveyor, in which a section of the plate coming from the second oven device is placed on the tilting conveyor, the rear side of which is then turned in the direction of the oven device. The front side of the tilting conveyor coming from the furnace device rotates towards the first mentioned tilting conveyor, after which the plate section of a tilting conveyor can be placed against the other tilting conveyor. The rocker conveyors then rotate back to their original positions. The advantages are simple connections to the media. One drawback is the increased amount of space that is required in comparison to a parallel conveyor. It has been found that rapid and successful homogenization of the temperature is achieved in a mode of the second oven device, which is characterized in that the second oven device is provided with a second heating section up and a second heating section side. to side, placed downstream of the second heating section upwards, as seen in the direction of standard passages of the plates. In order to achieve rapid and successful homogenization of the temperature in the furnace device as well, it is preferable that the furnace device be provided with a first heating section upwards and a first heating section from side to side, placed current down the first heating section upwards, on the inlet side of the oven device, as seen in the direction of the standard passage of the plates. In connection with achieving flexibility in the operation of the furnace device, inter alia in the case of or after a planned or sudden interruption, it is preferable that the furnace device be provided at the end, as seen in the address of standard passages, with an additional heating section from side to side which is accommodated downstream of the conveyor means, if present, and upstream of the welding machine. The invention is also exemplified by a process for producing a steel strip, in which the liquid steel is cast or melted in at least one continuous casting machine to form a plate and, using the melting heat, is transported through a furnace device and, in a laminating device, it is laminated to form the strip with a desired final thickness. This process is also described in the application PCT / NL97 / 00325. This application describes an endless process for producing a strip of steel that has been rolled in the austenitic, ferritic or mixed austenitic-ferritic range. The process described provides a large number of advantages. An advantage for the ability to carry out the process is that the individual plates can be coupled together. The object of the invention is to provide a process for coupling plates in such a way that the described process is carried out salefully. This object is achieved by a process for coupling the plates together, which is characterized in that the plates, which have already been optionally pre-reduced, are joined together by means of welding and the plates that have been welded together , they are laminated in an endless process in the rolling device. The coupling of the plates by means of welding provides the advantage that the plates can be quickly joined together without the formation of non-homogeneities in the chemical composition of the steel plate obtainable. In general, it will be necessary to carry out the welding on hot plates that are temporarily outside the oven device. Accordingly, the plates will inevitably cool, during welding, at the site of the weld to be formed. In order to prevent the non-homogeneities in the temperature that occur in the endless rolling process, an additional embodiment of the process of acujaxdo to the invention, is characterized in that the plates, after these have been welded together, are homogenized in temperature, at least at the site of the welded joint. In the case of an endless rolling process, it is desirable that the steel enters the rolling device at a relatively high speed. The current continuous casting machines are unable to achieve a casting speed corresponding to the desired speed of entry, if appropriate taking into account the reduction in thickness. Therefore, preference is given to a process according to the invention which is characterized in that the plates coming from two continuous casting machines are welded together. With the help of two or more continuous casting machines it is possible to achieve a flow of plate material which is large enough to be able to achieve the desired speed of entry into the rolling device. An alternative that takes less space and that is easier to perform in particular in the case of new installations, is characterized in that the plates coming from a machine for continuous emptying of multiple billet trajectories are welded together. In the case where a plurality of continuous dump machines or a multi-billet continuous dump machine is used, it is advantageous that a plurality of furnace devices be used simultaneously and that the plates coming from the furnace devices be coupled each other using the welding machine. In this case, a dedicated oven device is available for each billet. The billets coming from the kiln devices can be placed together, optionally in one of the ovens, and then coupled to each other by means of welding.

When an endless rolling process is carried out, a large number of installation parts are coupled together by means of the steel plate or the steel strip. An interruption in one of the installation parts means that the entire device, or a large part of the device, has to be turned off. This interruption can be unplanned or planned, for example, in order to change laminators. In order to be able to cope with interruptions of any kind, an additional design of the process according to the invention is characterized in that the oven device is used as a buffer space for the temporary storage of the plates in the event of interruption to one of the parts of the installation for the processing of plates that have been welded together. The oven device can act as a buffer for interruptions to the parts that are located upstream and for interruptions to the parts that are located downstream. The larger the oven device, the greater the buffering capacity.

The invention will be explained in the following with reference to the drawings, which illustrate a non-limiting embodiment of the invention. In the drawings: Figure 1 shows a diagrammatic side view of a device in which the invention can be used; Figure 2 shows a graph illustrating the temperature profile in the steel as a function of the position in the device; Figure 3 shows a graph illustrating the thickness profile of the steel as a function of the position in the device; Figure 4 shows a more detailed embodiment of the furnace device with the welding machine; Figure 5 shows a more detailed embodiment of a device with a plurality of oven devices that are used simultaneously for a plurality of billets; Figure 6 shows the temperature profile and the temperature difference for various points on the plate and the oven as a function of time.

In Figure 1, the reference number 1 indicates a continuous casting machine for melting or emptying thin plates. In this introductory description, this term is understood to mean a continuous casting machine for melting or pouring thin steel plates with a thickness of less than 150 mm, preferably less than 100 mm, more preferably less than 80 mm. The continuous emptying machine may comprise one or more billets. It is also possible that a plurality of the continuous emptying machines be placed next to another. These modalities fall within the scope of the invention. The reference number 2 indicates a pouring cauldron from which the liquid steel to be emptied is fed to a funnel 3. Below the funnel 3, there is a pouring mold 4 into which the liquid steel is emptied and the less is partially solidified. The standard continuous dump machine has a casting speed of approximately 6 m / min. The solidified thin plate is introduced into a furnace device, for example in the form of a tunnel furnace 7 which has a total length of, for example, about 300 m. The design of the tunnel kiln will be described later. Using the cutting device 6, the plate can be head and tail, and a plate can be cut into sections that are operable in connection with the design of the oven device or the oven devices and the operation thereof. The speed at which the plate enters the furnace corresponds to the emptying speed and is therefore approximately 0.1 m / sec. Downstream of the furnace 7, there is an oxide removal device 9 for removing the oxide that has formed on the surface of the plate. The rolling device 10, which fulfills the function of the preliminary rolling device, comprises two quadruple height platforms. If desired, a cutting device 8 can be included for emergency situations. It can be seen from Figure 2, that the temperature of the steel plate, which is approximately 1450 ° C when leaving the funnel, falls on the rolling platform at a level of approximately 1150 ° C, and the plate, is homogenized in the oven device to that temperature. Intensive spraying with water in the oxide removal device 9 causes the plate temperature to drop from about 1150 ° C to about 1050 ° C. This applies to the lamination in the austenitic and ferritic fields, a and f respectively. In the two laminator platforms of the preliminary rolling device 10, the plate temperature falls, with each laminator increase, by others about 50 ° C, so that the plate, the thickness of which was originally approximately 70 mm and which is formed in two steps, with an intermediate thickness of 42 mm, in a steel strip with a thickness of approximately 16.8 mm, is at a temperature of about 950 ° C. The thickness profile as a location function is shown in Figure 3. The numbers indicate the thickness in millimeters. A cooling device 11, a group of reels 12, and if desired, an additional oven device (not shown) are accommodated downstream of the preliminary lamination device 10. During the production of an austenitically laminated strip, the strip exiting the rolling device 10 can be temporarily stored and homogenized in the reels 12, and if a further increase in temperature is required, it can be heated in the heating device ( not shown) which is placed downstream of the spool. It will be obvious to the person skilled in the art that the rolling device 11, the reels 12 and the oven device that are not shown can be in different positions with respect to each other, from those mentioned above. As a result of the reduction in thickness, the laminated strip enters the reels at a speed of approximately 0.6 m / sec. A second rust removal installation 13 is placed downstream of the cooling device 11, the reels 12 or the furnace device (not shown), for the purpose of once again removing an oxide film that may have formed on the surface of the laminated strip. If desired, another cutting device can be included at the head and tail of a strip. The strip is then introduced into a rolling mill which may be in the form of six four-level rolling mill platforms that are placed one behind the other. When an austenitic strip is produced, it is possible to achieve the desired final thickness of between, for example, 1.0 and 0.6 mm by using only five laminator platforms. The thickness that is achieved by each platform of the rolling mill is indicated, for a plate thickness of 70 mm, in the upper row of the figures in Figure 3. After leaving the rolling mill 14, the strip, which is then at a final temperature of about 900 ° C and has a thickness of 0.6 mm, is intensively cooled by means of a cooling device 15 and is wound on a winding or winding device 16. The speed at which it enters the device 'winding is approximately 13-25 m / sec. If the strip of ferritically rolled steel is to be produced, the strip of steel exiting the preliminary rolling device 10 is intensively cooled by means of the cooling device 11. This cooling device can also be incorporated between the rolling platforms of the device. of final lamination. It is also possible to employ natural cooling, optionally between the rolling platforms. Then, the strip encompasses the reels 12, and if desired, the oven device (not shown), and the oxide is then removed in the rust removal facility 13. The strip, which is now in the ferritic field, is then at a temperature of about 750 ° C. As stated above, an additional part of the material may still be austenitic but, depending on the carbon content and the desired final quality, this may be acceptable. In order to provide the ferritic strip with the desired final thickness of between, for example, 0.8 and 0.5 mm, the six platforms of the rolling mill 14 are used. As in the situation where an austenitic strip is being laminated, for lamination of a ferritic strip an essentially equal reduction in thickness is used for each platform of the mill, with the exception of the reduction carried out by the final platform of the mill. Everything is illustrated in the temperature profile according to Figure 2, and the thickness profile according to the lower row of Figure 3 for the ferritic lamination of the steel strip, as a function of the position. The temperature profile shows that the strip, when leaving, is at a temperature that is very high due to the recrystallization temperature. Therefore, in order to prevent the formation of rust, it may be desirable to use a cooling device 15, to cool the strip to the desired winding temperature, at which recrystallization may still take place. If the outlet temperature from the rolling mill 14 is too low, it is possible to bring the ferritically rolled strip to a desired winding temperature, by means of an oven device 18, which is placed downstream of the rolling mill. The cooling device 15 and the oven device 18 can be placed next to one another or one behind the other. It is also possible to replace one device with the other device depending on whether the ferritic or austenitic strip is being produced. As already mentioned, the lamination is carried out endlessly and in a semi-endless manner, when a ferxitic or austenitic strip is produced. This means that the strip coming out of the laminating device 14 and, if appropriate, the cooling device or the oven device 15 or 18 respectively, has a length greater than what is usual for the formation of a single spool or roll and that a section of the plate with the length of a complete furnace, or even a larger plate section, is continuously laminated in the final rolling device. A cutting device 17 is included in order to cut the strip to the desired length, corresponding to the standard winding dimensions. If desired, a so-called closed, additional winder can be accommodated immediately downstream of the rolling mill 14, in order to assist in controlling the movement of the strip and the temperature of the strip. The device is suitable for strips with a width of between 1000 and 1500 mm and a thickness of approximately 1.0 mm in the case of an extensively laminated strip and from approximately 0.5 to 0.6 mm in the case of a ferritically laminated strip. Figure 4 shows a more detailed embodiment of a furnace device with the welding machine forming part of the furnace device. The furnace device comprises a first zone, which comprises parts 7, 7 and 7.? 2 and a second zone, 7.4. A welding machine 7,3 is placed between the first zone and the second zone. The first zone is composed of a first section 7.1 of rising heat, and a first section 7.2 of heat from side to side. The length of the first ascending heat section 7.1 corresponds approximately to the length of a plate section. As soon as the plate section is fully accommodated in the first ascending heat section 7.1, the plate section is transported at high speed through the heat section 7.2 from side to side. A number of plate sections can be cushioned within the section 7. 2 heat from side to side, on the one hand in order to have sufficient time to heat them perfectly, and on the other hand as a buffer in the case of a part of the installation, downstream or upstream of the oven device, which is out of operation due to planned or unplanned interruption. A second zone 7,4 is placed downstream of the welding machine 7,3, in which the second zone plate sections that have been welded together are homogenized in order to stabilize the temperature drop that has occurred. during welding at the welding site. The total length of the furnace is 250-320 m. The length of the first section 7.1 of rising heat is about 35 to 70 m. The length of the first section 7.2 of heat from side to side is approximately 100-150 m. The required length for the welding machine 7. 3 is about 4-25 m, and the length of the second zone 7.4 is about 50-80 m. Figure 5 shows a more detailed sectional view of an array with a plurality of furnace devices that can be used simultaneously for a plurality of billets. The furnace device 7, 30 comprises a first section 7, 10, of rising heat, a first section 7, 11 of heat from side to side, and a parallel conveyor, 7, 12. An additional section 7,13 of side-to-side heat is placed downstream of the parallel conveyor 7,12. Downstream of 7,13 there is a welding machine 7,14 which is followed by a second zone 7,15 for the homogenization of the plates that have been welded together. The second furnace device 7,40 comprises a second ascending heat section 7,20, a second side heat section 7.21 and a parallel conveyor 7.22. With the help of the parallel conveyors 7, 12 and 7, 22, the plate sections can be transported from the furnace 7, 40 to the furnace 7, 30 and, with the help of the welding machine 7, 14, they can be coupled to the plates that have been supplied to the furnace 7.30 directly from a continuous dump machine. When a plate section is transported, the parallel conveyor 7,22 moves parallel to its longitudinal direction, towards the parallel conveyor 7,12, which temporarily moves out of its normal position. After the parallel conveyor 7,22 has taken the position of the parallel conveyor 7,12, the transported plate section is pushed through to the 7,13 additional side-to-side heat section, after which both parallel conveyors they return to their original position. Table 1 shows an overview of the possible configurations of ovens 7.30 and 7.40. In configuration 1, the furnace has a damper length of 208 m, which, in the case of an interruption involving a reduction in the casting speed of 0.25 and 50% compared to a casting speed of 6 m / min., provides a buffer capacity in minutes, of 20, 26 and 39 minutes, respectively. This damping time is available to eliminate interruptions to the device. With a shock absorber length of 180 m, as is achieved in configurations 2 and 3, the respective damping times are 14, 18 and 27 minutes, and in configuration 4, the damping times are respectively 8, 10 and 14 minutes . It is advantageous to place the parallel conveyor as far as possible towards the front, in order to be able to maintain the length of the oven devices 7.30 and 7.40, short.

Table 1 Configurations! - Length of the first or second furnaces of ascending heat section 7, 10 and 7.20 50 m 50 m 50 m 50 m - Length of the first or second heat section from side to side 7, 11 and 7.21 124 96 96 m 70 m - Length of 7, 12 and 7.22 42 m 42 m 42 m 42 m - Length of the rear heat section from side to side 7,13 42 m 42 m 42 m 42 m - Length of the welding section 7,14 52 m 80 m 52 m 106 m Total = 310 m 310 m 282 m 310 m - Buffer length (b + c + d) 208 m 180 m 180 154 m - Position of the parallel conveyor (a + b) 174 m 146 m 146 m 120 m - Oven length 7.40 (a + b + c) 216 m 188 m 188 m 162 m Figure 6 shows the temperature profile and temperature difference for various points on the plate as a function of time. The curves apply to a length of the first ascending heat section after emptying 60 m, a welding length of 10 m, a length of the second zone after welding of 45 m, and a total furnace length of 280 m. It can be observed from the profiles of the curves p (the lowest temperature of the plate) and q (the highest temperature of the plate) that a temperature homogenization takes place. The profile with which this takes place can be observed from the profile of the curve t. Curve u shows the temperature difference between the upper side and the lower side of the plate. The curves and r indicate, respectively, the temperature in the bottom and top of the oven device. The curve s shows the average temperature of the plate through the cross section. It can be clearly seen that in the period indicated by L, during which the welding takes place, the homogenization of the temperature occurs and is then leveled again in the second zone, which lies downstream of the welding machine, until it is an acceptable temperature difference of about 10 ° C between the coldest and hottest sections of the plate is reached before the plate is introduced into the laminating device.

Claims (20)

3.1 .CLAIMS

1. A device for producing a thin steel strip, comprising at least one or more continuous casting machines for emptying steel plates with a thickness of less than 120 mm, a baking device that is suitable for heating and / or homogenizing a plate, and at least one laminating device for reducing the thickness of a plate that is conveyed out of the oven device, characterized in that a welding machine is accommodated between the continuous dump machine or the continuous dump machines and the laminating device, for melting of narrow end faces of the plates and then joining the successive plates together, the welding machine is movable along a length of welding in the standard passage direction of the plates, through the device towards the rolling device, and the furnace device comprises a first zone and a second zone, which, observed in the standard passage direction, are placed one after the other, and the welding machine is accommodated between the first and second zones.

2. Device according to claim 1, characterized in that the welding machine is movable in the standard passage direction of the plates through the device, towards the laminating device at a speed between 4 and 20 m / min., Preferably at a speed between 10 and 17 m / min.

3. Device according to claim 1 or 2, characterized in that the welding machine is an induction welding machine.

4. Device according to any of the preceding claims, characterized in that the welding machine is provided with means for limiting the transfer of heat from the plates to the environment.

5. Device according to any of the preceding claims, characterized in that the total length of the oven device is between 250 and 330 m.

6. Device according to claim 5, characterized in that the first zone and the second zone are placed at a distance which, measured in the direction of the standard passage, is from 4 to 25 m, preferably from 5 to 17 m.

7. Device according to claim 5 6 6, characterized in that the second zone has a length between 25 and 100 m.

8. Device according to any of claims 5-7, characterized in that the second zone comprises a rising reheating section and a side-by-side heating section.

9. Device according to any of claims 5-8, characterized in that the means for limiting the transfer of heat from the plates to the environment are arranged between the first zone and the second zone.

10. Device according to any of the preceding claims, characterized in that the device is provided with a second oven device for accommodating a plate.

11. Device according to claim 10, characterized in that at least one of the first oven device and the second oven device is provided with conveying means for transporting a plate from the second oven device to the first oven device.

12. Device according to claim 11, characterized in that the conveyor means comprise a so-called parallel conveyor.

13. Device according to any of claims 10-12, characterized in that the second furnace device is provided with a second ascending heat section and a second heat section from side to side, placed downstream of the second ascending heat section, as seen in the standard passage direction of the plates.

14. Device according to any of the preceding claims, characterized in that the furnace device is provided with a first ascending heat section and a first heat section from side to side, placed downstream of the first ascending heat section, on the side input of the oven device, as seen in the standard passage direction of the plates.

15. Device according to any of the preceding claims, characterized in that the oven device is provided at the end, as seen in the standard passage direction, with an additional section of heat from side to side, which is accommodated downstream of the half conveyor, if present, and upstream of the welding machine.

16. Process for the production of a strip of steel, in which the liquid steel is emptied into at least one continuous dump machine to form a plate with a thickness of less than 120 mm and, using the heat of emptying, is transported through a furnace device and, in the laminating device, is laminated to form the strip with a desired thickness, characterized in the process because the successive plates, which have already been optionally pre-reduced, are joined together, by merging mutually facing the narrow end faces by means of welding, and the plates that have been welded together are laminated in an endless process in the laminating device, the welding site is moved together with the plates, and the plates, after these they have been welded together, they are homogenized in temperature at least in the place of the solder joint.

17. Process according to claim 16, characterized in that the plates coming from two continuous casting machines are welded together.

18. Process according to any of claims 16 or 17, characterized in that the plates coming from a machine for continuous emptying of multiple billet paths are welded together.

19. Process according to any of claims 16-18, characterized in that a plurality of oven devices used simultaneously and the plates coming from the oven devices are coupled together using the welding machine.

20. Process according to any of claims 16-19, characterized in that the oven device is used as a buffer space for the temporary storage of the plates in the case of the interruption to one of the parts of the installation for the processing of plates that have been welded together