Continuous casting and rolling installation and method

Abstract

The invention relates to a casting and rolling mill (10), a method for continuous strip production, and a method for batch strip production. A casting machine (20) for continuously casting a metal strand (2), a first separating device (30) arranged downstream of the casting machine (20) in the transport direction (R) for separating the metal strand (2), and a first rolling stand group (40) arranged downstream of the first separating device (30) in the transport direction (R) for rolling the metal strand (2) or slabs (4) separated therefrom are provided. The transport distance (T) between the first separating device (30) and the first rolling stand group (40) is 50 m or less.

Description

field of technology

[0001] The invention relates to a casting and rolling plant, a method for endless strip production and a method for batch strip production. State of the art

[0002] In so-called casting-rolling mills, the casting machine is coupled to one or more rolling trains, i.e., one or more groups of rolling stands, which allows the heat inherent in the freshly cast strand to be utilized for the rolling process. With such casting-rolling mills, it is particularly possible to roll very thin metal strips, so-called hot strips, in endless operation (so-called endless strip production, ESP), which cannot be produced by conventional cold rolling with multiple passes.

[0003] In continuous operation of a casting-rolling mill, the mass flow is constant along the entire length of the mill. Therefore, metal strips that must be cast very slowly to meet specified quality criteria and would consequently cool significantly between rolling steps cannot simply be produced as continuous strips. Accordingly, for example, strips that move through the mill with only a low mass flow may require additional heating energy in some cases. Furthermore, the continuous production of very thick strips is associated with difficulties due to the relatively slow speeds in the last stands, the cooling section, and the coiling area (for example, when coiling into coils or cooling the strip), which can only be resolved with considerable effort.Further difficulties can also arise when sampling the undeformed strand during ongoing plant operation, which is sometimes necessary for API grades, or when carrying out emergency strip guidance in the event of a malfunction.

[0004] To circumvent these difficulties, it is known to operate casting-rolling plants in so-called batch mode, in which a strand is continuously cast but cut into slabs of a predetermined length before the final product is completed, especially before the first rolling passes. These slabs can then be further processed more or less independently of the continuous casting process, and if necessary, even removed from the plant and reintroduced at a later time. In general, however, the production of hot strip in batch mode is disadvantageous, for example, with regard to the homogeneity of the material properties, production risk, achievable minimum thickness, and plant length. Summary of the invention

[0005] Against this background, it is an object of the present invention to create improved production conditions in a casting-rolling plant, in particular to provide an energy-efficient casting-rolling plant suitable for both endless strip production and batch strip production, as well as methods for the energy-efficient production of both endless strips and batch strips.

[0006] This object is achieved by a casting and rolling plant, a method for endless strip production and a method for batch production according to the independent claims.

[0007] Preferred embodiments are the subject of the dependent claims and the following description.

[0008] According to a first aspect of the invention, the casting-rolling plant is capable of both continuous strip production and batch strip production and comprises a casting machine for continuously casting a metal strand, a first separating device arranged downstream of the casting machine in the transport direction for separating the metal strand, and a first rolling stand group arranged downstream of the first separating device in the transport direction for rolling the metal strand or slabs separated therefrom. The transport distance between the first separating device and the first rolling stand group is 50 m or less, preferably 40 m or less.

[0009] Capability for both continuous strip production and batch strip production within the meaning of the invention preferably requires the casting-rolling plant to be capable of being operated or controlled in two different operating modes. One of these operating modes is continuous operation, in which a continuous strip is produced. This continuous strip is cut into a coil immediately before coiling. The other operating mode, in contrast, is batch operation, in which individual strips are produced from slabs cut at the beginning.

[0010] A transport path within the meaning of the invention is preferably a path along which a cast metal strand or a slab separated therefrom is transported, in particular conveyed. Such a transport path is expediently defined by one or more active and / or passive transport means, for example, transport rollers, rolls, conveyor belts, switches, and / or the like. The transport path can lead through one or more devices for processing or at least influencing the metal strand or slab, for example, through discharge devices, heating devices, descaling devices, and / or the like.

[0011] One aspect of the invention is based on the approach of minimizing or at least limiting the heat loss in a casting and rolling plant from a metal strand cast by means of a casting machine or from a slab separated therefrom, preferably as it passes through the entire plant, but in any case up to a first rolling stand group. For this purpose, a transport path between a first separating device for separating the metal strand and the first rolling stand group for rolling the metal strand or the slab separated therefrom is designed to be as short as possible. The plant is preferably designed such that this first transport path is only 50 m or less, preferably 40 m or less. The transport path is thus expediently dimensioned such that essentially one slab fits between the first separating device and the first rolling stand group, from which a hot strip up to 32 mm thick, which can be coiled into a coil, can be rolled.This makes it possible to retain almost all or at least a large part of the heat still contained in the metal strand after casting, or at least to significantly facilitate heat retention until the metal strand or slab is rolled for the first time by the first rolling stand group. At the same time, if necessary, for example, in the event of a disruption downstream of the first rolling stand group in the transport direction, the slab can be removed from the transport section as a whole. With such a short transport section, the casting-rolling mill is not significantly longer than a conventional casting-rolling mill configured exclusively for continuous operation. However, compared to conventional casting-rolling mills, which are essentially configured for batch operation, the casting-rolling mill according to the invention can be significantly shorter.Accordingly, compared to such conventional casting and rolling plants, strips in the range of 0.6 mm to 32 mm can be produced with significantly reduced energy consumption (less heating power required to reheat the slabs before the rolling process(es)) and, if necessary, also with lower CO2 emissions.

[0012] The casting machine is expediently designed to cast endlessly rolled strands relatively quickly, i.e. with a high specific mass flow of, for example, 3.5 to 6 t per minute and meter of width, but also slowly and relatively thickly, for example up to 230 mm, if specific quality requirements are placed on the end products. The casting machine can, for example, be designed to cast a metal strand at 3.5 m / min to 6 m / min for endless operation and at 1.5 m / min to 6 m / min for batch operation. The metal strand can be cast with a thickness of 90 mm to 230 mm, in particular 120 mm to 170 mm, and / or with a width of 800 mm to 2600 mm, in particular 900 mm to 2100 mm. For this purpose, casting segments of the casting machine can be adjustable or the narrow sides of a mold of the casting machine can be exchangeable.In addition, adjustable narrow sides can be used to change the casting width during plant operation.

[0013] The first separating device is preferably designed as a pendulum shear in order to be able to reliably separate the cast metal strand even at maximum dimensions, ie thicknesses of up to 230 mm and widths of up to 2600 mm.

[0014] The first rolling stand group expediently comprises at least one rolling stand, preferably three to four rolling stands, and is preferably configured to roll the cast metal strand or the slab separated therefrom to a thickness of between 6 mm and 80 mm, preferably between 8 mm and 75 mm. In particular, the first rolling stand group can roll the metal strand in continuous operation of the casting and rolling mill to an intermediate strip thickness of 6 mm to 30 mm, preferably 8 mm to 25 mm. In batch operation, however, the first rolling stand group can roll the slab to 20 mm to 80 mm, in particular 25 mm to 75 mm. In addition, an upsetting device can be provided, which is expediently arranged immediately in front of or on the first rolling stand of the first rolling stand group and can upset, ie narrow, the metal strand or the slab by 10 mm to 100 mm, preferably 20 mm to 50 mm, in the width direction on each side.

[0015] Optionally, a first descaling device, also referred to as a scale washer, can be provided between the first separating device and the first rolling stand group. With the first descaling device, scale can be removed with minimal heat extraction. The first descaling device is expediently arranged as close as possible to the first stand of the first rolling stand group, in particular directly in front of the first stand or an upsetting device arranged in front of or on it. For example, the first descaling device can be arranged less than 4 m from the first stand of the first rolling stand group.

[0016] Preferred embodiments of the invention and their further developments are described below. These embodiments can be combined with each other and with the aspects of the invention described below, unless expressly excluded.

[0017] In a preferred embodiment, the transport distance between the first separating device and the first rolling stand group is 30 m or less. Depending on the desired target thickness of the end product, i.e., particularly for a hot strip with a thickness of up to 32 mm, such a short transport distance may be sufficient to arrange a correspondingly long slab completely between the first separating device and the first rolling stand group and, if necessary, to remove it from the transport distance, for example, in the event of a malfunction downstream of the first rolling stand group. Heat losses between the first separating device and the first rolling stand group can thus be further reduced.

[0018] In a further preferred embodiment, the transport section between the first separating device and the first rolling stand group is free of tunnel furnaces and / or insulation sections. The transport section therefore comprises neither a tunnel furnace nor an insulation section, nor is it defined, even in sections, by a tunnel furnace or an insulation section. An insulation section is understood here to be a section provided with insulation to homogenize the temperatures between the center and surface of the strand. Such insulation sections are typically more than 50 m long.A short device which forms a section of the transport route and has an insulating effect in this section or even has insulating or insulating elements, but has a decidedly different function (for example, the removal of slabs from the transport route or the bridging of otherwise free distances between two devices) should not be understood as an insulating section.

[0019] In a further preferred embodiment, a discharge device for discharging slabs or strand pieces separated from the cast metal strand by means of the first separation device is provided between the first separation device and the first rolling stand group from the transport path. The discharge device expediently defines a discharge section within the transport path in which a slab or strand piece separated from the metal strand can be arranged and discharged from the transport path. Preferably, the discharge device, in particular the discharge section, defines the majority of the transport path, for example, more than half the transport path. By means of the discharge device, continuous casting can be maintained both in batch operation and in continuous operation if a disturbance occurs in the transport direction downstream of the first rolling stand group.The limitation of the discharge device essentially to a maximum slab length necessary for the desired coil size of the final product can take into account the reduction of heat loss in the area of ​​the transport route.

[0020] Heat loss during passage through the discharge device can be further reduced if a movable, particularly foldable, insulating cover is provided in the area of ​​the discharge device. The insulating cover, which can be manufactured in one piece or consist of several separate movable cover elements, can enclose the transport path at least in sections and at least partially. In particular, in order to be able to discharge a slab located in the area of ​​the discharge device from the transport path, the insulating cover can then be moved away. The insulating cover can, for example, be designed to be foldable and can be folded away when needed. Alternatively, a removable insulating cover is also conceivable.

[0021] In a further preferred embodiment, a first electrical heating device is provided between the first separating device and the first rolling stand group.

[0022] The electric heating device is expediently designed as an induction furnace and thus advantageously short, in any case significantly shorter than a tunnel furnace used in conventional casting-rolling plants. With the aid of the first heating device, the metal strand or the slab separated from it can be brought to a predetermined tapping temperature, expediently constant over the length of the slab, for subsequent rolling in the first rolling stand group, if necessary, for example during casting with low mass flows and correspondingly low transport speeds, such as during start-up or shut-down of the plant. The first heating device is expediently arranged between the discharge device and the first rolling stand group, in particular between the discharge device and the first descaling device.

[0023] A compact, yet powerful first heating device can be formed by a combination of several longitudinal field modules, transverse field modules, edge heaters, and radiant heating elements. A first heating device with at least one longitudinal field module, preferably three to six longitudinal field modules, and at least one edge heater, preferably one to two edge heaters, is preferred. Consequently, the first heating device preferably has a maximum of six longitudinal field modules and a maximum of two edge heaters. This makes it possible to create a heating section that accounts for only approximately 3 m to 6 m of the total transport section. Such a first heating device can therefore easily form a transport section of 50 m or less, possibly even 30 m or less, together with an unloading device of a typical slab length, i.e., approximately 16 m to 25 m, a first descaling device, and an upsetting device.

[0024] In a further preferred embodiment, a scarfing device, also known in English as a scarfing machine, is provided, which is arranged between the casting machine and the first separating device or between the first separating device and the first rolling stand group. By means of the scarfing device, the surface of the cast metal strand or of the slab separated therefrom can be liquefied and thus removed by a highly exothermic oxidation reaction in order to obtain surfaces of particularly high purity. By arranging the scarfing device upstream of the first separating device in the transport direction, continuous scarfing, i.e. continuous operation of the scarfing device, is possible.By arranging the scarfing device downstream of the first separating device in the transport direction, the scarfing can be carried out at a higher transport speed in batch operation due to the acceleration of the slab after separation from the metal strand, thus minimizing the thickness of the scarfed layer and thus output losses. This can also potentially save energy. The scarfing device is preferably arranged upstream of the first descaling device in the transport direction.

[0025] The scarfing device can also be designed to be movable or suspended so that it can be pulled out of the area between the casting machine and the first separating device or out of the transport path or can be introduced into this area or into the transport path as required.

[0026] In a further preferred embodiment, a second roll stand group arranged downstream of the first roll stand group in the transport direction and two reels arranged downstream of the second roll stand group in the transport direction are provided. A second separating device and a second electrical heating device are preferably arranged between the first roll stand group and the second roll stand group. A cooling section and a third separating device are preferably arranged between the second roll stand group and the two reels. The total transport distance between the first separating device and the front of the two reels in the transport direction is expediently at most 280 m, preferably at most 230 m. The casting and rolling mill can thus be designed to be significantly more compact than conventional casting and rolling mills, which can operate in both continuous and batch mode.

[0027] According to a second aspect of the invention, the method for continuous strip production is carried out using a casting and rolling plant comprising: i) a casting machine for continuously casting a metal strand; ii) a first separating device arranged downstream of the casting machine in the transport direction for separating the metal strand; iii) a first rolling stand group arranged downstream of the first separating device in the transport direction for rolling the metal strand or slabs separated therefrom, wherein the transport distance between the first separating device and the first rolling stand group is 50 m or less; iv) a second rolling stand group arranged downstream of the first rolling stand group in the transport direction; and v) at least two coilers arranged downstream of the second rolling stand group in the transport direction, wherein a third separating device is arranged between the second rolling stand group and the coilers.In the method, the metal strand is rolled into an intermediate strip by means of the first rolling stand group, and the intermediate strip is rolled into a hot strip, in particular to a target thickness, by means of the second rolling stand group. The hot strip is wound onto a coiler by means of one of the reels and, in particular upon reaching a predetermined coil size or a predetermined coil weight, is separated by means of the third separating device. The method for continuous strip production is therefore expediently carried out using a casting-rolling plant according to the first aspect of the invention, which is capable of both continuous strip production and batch strip production.

[0028] A second separating device, a second electric heating device or a cooling device, and / or a second descaling device are expediently arranged between the first rolling stand group and the second rolling stand group. A cooling section is preferably arranged between the second rolling stand group and the third separating device.

[0029] Due to the short transport distance of 50 m or less, the heat loss of the cast metal strand until rolling in the first rolling stand group is significantly reduced. Consequently, little or no (re)heating of the metal strand to a predetermined tapping temperature at the first rolling stand group is necessary. Accordingly, significant energy and, subsequently, cost savings can be achieved. Even if a first electrical heating device, e.g., consisting of several electrical heating elements, is provided between the first separating device and the first rolling stand group, energy can be saved: unlike tunnel kilns, such electrical heating elements consume no energy during idle operation. This allows the total energy required to produce steel strip to be reduced essentially to the deformation energy.At the same time, this makes it possible to reduce the space required for the entire plant, particularly compared to conventional casting and rolling plants suitable for batch operation with a tunnel furnace or an insulation section between the first separating device and the first rolling stand group.

[0030] In a preferred embodiment, in the event of an operational disruption in the region of the second rolling stand group or downstream thereof in the transport direction, i) the metal strand is simultaneously separated by means of the first separating device and the intermediate strip is simultaneously separated by means of the second separating device, and ii) strip pieces are subsequently separated from the intermediate strip by means of the second separating device and guided out of the casting and rolling mill immediately downstream of the second separating device in the transport direction at least until a slab separated from the cast metal strand by means of the first separating device can be guided out of the transport path by a removal device arranged between the first separating device and the first rolling stand group. The rolls of the first rolling stand group preferably remain engaged so that the maximum cutting thickness of the second separating device, for example a drum shear, is not exceeded.In this way, the area behind the first separating device can be cleared to continue removing slabs separated from the metal strand without having to stop the casting process. The removed slabs can, if necessary, be reintroduced into the transport line at a later time, reheated using the first heating device, and then further processed.

[0031] If the second cutting device is designed as a drum shear, it is preferred for simplicity if the strip pieces cut from the intermediate strip in the event of a malfunction have a length corresponding to the circumference of the cutting circle of the drum shear. The short strip pieces thus produced can be easily and at least partially automatically removed from the system before entering the second rolling stand group, into a second descaling device arranged in the transport direction between the second cutting device and the second rolling stand group, and / or into a second heating device arranged in the transport direction between the second cutting device and the second rolling stand group.

[0032] In a further preferred embodiment, the metal strand is rolled into the intermediate strip in the first rolling stand group without heating the metal strand in the area of ​​the transport path, i.e., between the first separating device and the first rolling stand group. During the rolling process in the first rolling stand group, only the heat still present in the metal strand from the casting process is utilized. This is possible in particular due to the short transport path of 50 m or less compared to conventional casting and rolling mills.

[0033] According to a third aspect of the invention, a method for batch strip production is carried out using a casting and rolling plant, comprising: i) a casting machine for continuously casting a metal strand; ii) a first separating device arranged downstream of the casting machine in the transport direction for separating the metal strand; iii) a first rolling stand group arranged downstream of the first separating device in the transport direction for rolling the metal strand or slabs separated therefrom, wherein the transport distance between the first separating device and the first rolling stand group is 50 m or less; iv) a second rolling stand group arranged downstream of the first rolling stand group in the transport direction; and v) at least two coilers arranged downstream of the second rolling stand group in the transport direction, wherein a third separating device is arranged between the second rolling stand group and the coilers.In the method, a slab is separated from the metal strand by means of the first separating device and accelerated to a pass-through speed for the first rolling stand group. The slab is then rolled in the first rolling stand group into an intermediate strip and in the second rolling stand group into a hot strip, in particular to a target thickness, which is wound up by means of one of the coilers. The method for batch strip production is therefore expediently carried out using a casting-rolling plant according to the first aspect of the invention, which is capable of both continuous strip production and batch strip production.

[0034] Due to the short transport distance of 50 m or less, the heat loss of the slabs separated from the metal strand until rolling in the first rolling stand group is significantly reduced. Consequently, little or no (re)heating of the slabs to a specified tapping temperature is required at the first rolling stand group. At the same time, the space requirement for the entire plant is reduced, especially compared to conventional casting-rolling plants suitable for batch operation with a tunnel furnace or an insulating section between the first separating device and the first rolling stand group.

[0035] In a preferred embodiment, the slab is heated to a predetermined tapping temperature for the first rolling stand group by means of a first electrical heating device arranged between the first separating device and the first rolling stand group. This is achieved by reducing the electrical heating power used to heat the slab while the slab passes the first heating device. As a result, the head end of the slab is heated more than its foot end. This makes it possible to achieve a substantially constant tapping temperature over the entire length of the slab or to homogenize the slab temperature. Otherwise, the head end would cool more than the foot end by the time it reaches the first rolling stand group due to the slab accelerating to the tapping speed after being separated from the metal strand.

[0036] Preferably, the intermediate strip is then transported at a constant speed in the transport direction behind the first rolling stand group.

[0037] In a further preferred embodiment, the slab is rolled in the first rolling stand group without the slab being heated in the region of the transport section. For this purpose, the slab is expediently accelerated after being separated from the metal strand in such a way that its head end, when passed in the first rolling stand group, still has a temperature sufficient to reach a final rolling temperature for rolling in the second rolling stand group, e.g. the predetermined passing temperature for the first rolling stand group. Due to the acceleration after being separated from the metal strand, the foot end of the slab initially has a higher temperature than the head end. In order to maintain a substantially homogeneous temperature over the length of the slab, the rolling speed in the first rolling stand group is then preferably reduced while the slab passes the first rolling stand group and the intermediate strip rolled in the process passes the second rolling stand group.

[0038] If necessary, a combination of the two previously described embodiments can also be used. In this case, a temperature difference in the slab between the slab head and slab foot is at least partially reduced by heating using the first heating device. Subsequently, during rolling in the first rolling stand group, a substantially homogeneous temperature is established in the intermediate strip or the temperature difference is at least further reduced. In this case, too, the heating power of the first heating device is reduced while the slab passes through the first heating device, and the rolling speed is reduced while the slab is rolled in the first rolling stand group and the intermediate strip rolled in the second rolling stand group.

[0039] In a further preferred embodiment, a surface layer of the cast metal strand or of the slab separated therefrom is removed during a surface treatment by a scarfing device arranged upstream of the first rolling stand group in the direction of transport. The metal strand or slab is expediently preheated briefly for this purpose in the scarfing device. A reaction gas, for example oxygen, can then be blown onto the surface at high pressure, for example 5 bar or more, and the surface can be ignited. As a result, during this surface treatment, also referred to as scarfing, after the short ignition and preheating phase, a self-sustaining exothermic oxidation reaction with high-pressure oxygen can take place, during which a thin layer of the strand or slab surface is liquefied. This surface layer can be removed. This makes it possible to eliminate casting defects on the strand or slab surface.The slab surface can be eliminated and correspondingly high quality requirements for the final product can be met. The removal of such casting defects may be necessary, for example, to use the produced hot-rolled strip as starting material for automotive exterior applications.

[0040] Preferably, the surface treatment can remove a layer on both a top and bottom surface as well as on the side surfaces of the cast strand or the slab separated therefrom.

[0041] In contrast to the conventional production of strips with such high quality requirements, where such a surface treatment takes place offline, i.e. not directly on the cast strand or the slab separated from it and therefore at relatively low temperatures, the surface treatment in the present case takes place inline and consequently on the freshly cast strand that has not cooled down or at least hardly cooled down or on the slab separated from it that has not yet cooled down, i.e. for example at temperatures of more than 1000 C. The preheating time can thus be significantly reduced, for example to 10 s or less, in particular to 5 s or less.

[0042] During surface treatment, a layer of between 1 mm and 5 mm, preferably between 2 mm and 3 mm, is removed from the surface. This can be sufficient to achieve a final product quality that is sufficient for automotive outer skin applications with regard to casting defects on the strand or slab surface.

[0043] In order to prevent too much material from being removed by the scarfing device during surface treatment in batch operation of the casting and rolling mill during the (slow) casting of a thick metal strand, for example 180 mm or more, the surface treatment is preferably carried out in the transport area, in particular immediately upstream of the first heating device, at the rolling speed in the first rolling stand group. This means that the surface treatment is carried out on the slab after it has been separated from the metal strand and accelerated to the rolling speed (at the first rolling stand of the first rolling stand group). For example, the surface treatment can be carried out by the scarfing device after the slab has been accelerated to the cutting speed for the first rolling stand group.The slab then advantageously passes through the scarfing device at the initial speed, at least until the rolling speed in the first rolling stand group is reduced to equalize the temperature between the head and foot ends of the slab. The surface treatment can therefore take place at a comparatively high transport speed of the slab through the scarfing device, for example at a transport speed between 4 m / min and 6 m / min, preferably between 5 m / min and 5.8 m / min, which means less material is removed. Scarfing in batch operation of the casting and rolling plant, in particular to achieve particularly high-quality strips, such as those used in the automotive outer skin sector, is particularly synergistic because it can be carried out at a low casting speed, e.g. between 1 m / min and 2 m / min, in particular between 1.5 m / min and 1.8 m / min, and consequently a thick strand, e.g. with a thickness of 180 mm or more.Slow casting already allows for a purer end product, e.g., with fewer impurities and casting defects. For example, slow casting can avoid or at least reduce contamination from slag inclusions. Furthermore, bubbles containing impurities, such as non-metallic materials and / or gas, can rise to the meniscus—the liquid level or the steel / slag interface—while still in the mold without being trapped in the strand. This can be further enhanced by using a particularly long mold.

[0044] The thick strand produced in this way can then be advantageous with regard to scarfing, since the ratio between the thickness of the removed surface layer and the thickness of the slab separated from the strand is significantly smaller than when scarfing thin strands or slabs. The relative material loss due to scarfing can thus be significantly reduced. In a further preferred embodiment, between the production of two strips in batch operation, a strand section is separated from the metal strand by means of the first separating device. The metal strand is therefore separated twice in quick succession. The strand section can then be removed from the transport section in the transport direction before the first rolling stand group, for example by means of the discharge device.Thus, sampling of the undeformed strand, as required for tube grades (API grades), for example, can be carried out by cutting it twice during batch operation of the plant without generating additional scrap. Short description of the drawings

[0045] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of an embodiment, which is explained in more detail in conjunction with the drawings. Fig. 1 shows an example of a casting and rolling plant; Fig. 2 shows an example of a process for endless strip production; and Fig. 3 shows an example of a process for batch strip production.

[0046] Where appropriate, the same reference numerals are used in the figures for the same or corresponding elements of the invention. Description of the embodiments

[0047] FIG 1 shows an example of a casting and rolling mill 10 which is suitable for both continuous operation and batch operation, i.e. for both continuous strip production and batch strip production. The casting and rolling mill 10 comprises a casting machine 20 for the continuous casting of a metal strand 2, a first separating device 30 arranged downstream of the casting machine 20 in the transport direction R for separating the metal strand 2, a first rolling stand group 40 comprising - purely as an example - four rolling stands 42 for rolling the metal strand 2 or slabs 4 separated therefrom, a second rolling stand group 50 comprising - purely as an example - five rolling stands 52 for re-rolling the intermediate product rolled in the first rolling stand group 40 and at least two coilers 60, 62 for coiling a final product. The metal strand 2 or the slabs 4 are / are wound up between the first separating device 30 and the first rolling stand group 40.The slabs 4 are transported along a transport path T, which in the present example is defined by a discharge device 70 for discharging the slabs 4, a first heating device 80 for heating the slabs 4, and a first descaling device 90 for descaling the metal strand 2 or the slabs 4 before the piercing in the first rolling stand group 40. Also arranged between the first and second rolling stand groups 40, 50 are a second separating device 100, a second heating device 110, a cooling device 120 for cooling the rolled intermediate product, and a second descaling device 130. A cooling path 140 with a rapid cooling unit 142 (also referred to as "power cooling") and a laminar cooling unit 144, as well as a third separating device 150, is arranged between the second rolling stand group 50 and the coilers 60, 62.In addition, a scarfing device 160 for scarfing the cast metal strand 2 is arranged in front of the first separating device 30 in the transport direction R.

[0048] The casting machine 20 has a mold (not shown) and casting segments (likewise not shown), which transfer the metal emerging from the mold, with at least initially a still liquid core, into a horizontal position in a casting arc 22. The casting segments are expediently designed to be adjustable so that the thickness of the cast metal strand 2 can be adjusted. In addition, the narrow sides of the mold can preferably be exchanged so that casting thicknesses between 90 mm and 230 mm, in particular between 120 mm and 170 mm, can be set. If necessary, the mold can also be equipped with adjustable narrow sides so that casting widths between 800 mm and 2600 mm, in particular between 900 mm and 2100 mm, can be set. The mold is expediently designed for casting mass flows of up to 6 t per minute and meter of width. This allows casting speeds of up to 6 m / min to be achieved.

[0049] In order to keep the casting-rolling plant 10 as compact as possible, i.e., to keep the total transport distance L of the casting-rolling plant 10 as short as possible, the length of the transport distance T is 50 m or less, preferably even only 30 m or less. Thus, the total transport length L from the first separating device 30 to the front reel 60 in the transport direction R, preferably even the total length of the plant from a casting ladle 24, also referred to as a tundish, or a corresponding ladle turret, or at least from the mold to the front reel 60, can be limited to 140 m to 280 m, in particular to only approximately 200 m to 230 m.Aside from reducing the footprint required to construct the casting-rolling mill 10, such a short transport distance T also has the advantage that heat originating from the casting process in the casting machine 20 and carried by the cast metal strand 2, in particular a hot core of the metal strand 2, can be carried to the first rolling stand group 40 without significant losses and used there in the rolling process. The production process with the casting-rolling mill 10 can thus be designed to be particularly efficient, in particular energy-saving and thus sustainable. With appropriate operation of the casting-rolling mill 10, for example, the production of a 2 mm thick hot strip with a total energy consumption of less than 100 kWh per ton of hot strip is possible.

[0050] Such a short transport path T can be realized, for example, by the discharge device 70 having essentially the maximum length of a thinly cast slab 4, as is necessary for the production of an end product that can still be wound into a coil of conventional size. Such maximum lengths are, for example, in the production of end products from slabs 4 with a maximum specific weight of 25 kg / mm ​​and a casting thickness of 120 mm, approximately 25 - 30 m. Accordingly, the discharge device 70 is preferably a maximum of 30 m, more preferably a maximum of 25 m, in particular a maximum of 20 m, long. The discharge device 70 thus preferably forms the majority, i.e., more than half, of the transport path T.

[0051] In addition, in order to shorten the transport path T, it is expedient if the first heating device 80 is designed as an electrical heating device, for example as an induction furnace. The first heating device 80 can therefore have a length of, for example, a maximum of 4 m and accordingly only make up a fraction of the transport path T. For example, the first heating device 80 can have at least one, preferably three to six longitudinal field modules and at least one, preferably one to two, edge heaters. In principle, however, other combinations of longitudinal field modules, transverse field modules, edge heaters and / or radiant heating elements are also conceivable. Expediently, the first heating device 80 can, by means of an appropriately predictive control, maintain a constant tapping temperature of the metal strand 2 orof the slabs 4 for the first rolling stand group 40 or at least a constant temperature at another location of the casting and rolling mill 10 in the transport direction R behind the first rolling stand group 40, for example a constant target or final rolling temperature, even with changing mass flows.

[0052] To further reduce heat loss on the transport path T, a hinged insulating cover 72 is provided in the area of ​​the discharge device 70. This allows a large portion of the transport path T to be covered when no slabs 4 need to be discharged from the transport path T.

[0053] With a view to a short overall transport distance L, it is also expedient if the second heating device 110 is designed as an electric heating device. The second heating device 110 can in particular be designed as an induction furnace comprising, for example, at least two, preferably six, transverse field modules. However, the use of longitudinal field modules can also be advantageous, particularly with great strip thicknesses. The heating power installed in the form of the second heating device 110 at this position, i.e. between the first and second roll stand groups 40, 50, can be significantly lower than in pure ESP systems. This is due to the fact that at the start and / or end of casting and thus initially slow casting speeds, the first and secondlast strips can each be produced in a batch process, wherein the slabs 4 are accelerated to high entry speeds for the first rolling stand group 40 independently of the casting speed in the area of ​​the transport section T and can thus also continue to pass through the remaining part of the casting and rolling plant 10 at high speed (and correspondingly low heat loss).

[0054] The cooling device 120 can be used to specifically lower the final rolling temperature for rolling in the second rolling stand group 50 if necessary.

[0055] FIG 2 shows an example of a method 200 for endless belt production, for example with the FIG 1 The casting and rolling mill 10 shown is shown. In a method step S1, the metal strand 2 is cast from liquefied metal by means of the casting machine 20, in particular into a metal strand 2 with a thickness between 90 mm and 210 mm, preferably between 120 mm and 170 mm, and / or a width between 80 mm and 2600 mm, preferably between 900 mm and 2100 mm. The mass flow can be up to 6 t per minute and meter of width. Casting speeds of 3.5 m / min to 6 m / min are expediently achieved with the casting machine 20.

[0056] In an optional process step S2, the cast metal strand 2 is scarfed using the scarfing device 160 to achieve a particularly high surface cleanliness. Like the casting of the metal strand 2, the scarfing can be carried out essentially continuously.

[0057] In a further process step S3, the cast metal strand 2 is descaled by means of the first descaling device 90. Before entering the first rolling stand group 40, the descaled metal strand 2 can optionally be descaled by means of a FIG 1 The rolls can be upset by a compression device (not shown) located directly in front of the first roll stand group 40. The width reduction per side can be up to 100 mm, but at least up to 50 mm. For example, a width reduction of between 10 mm and 100 mm, preferably between 20 mm and 50 mm, can be achieved. Such upsetting can be particularly useful when changing the casting width.

[0058] In a further process step S4, the descaled and optionally also upset metal strand 2 is rolled into an intermediate strip by means of the first rolling stand group 40. The first rolling stand group 40 can roll the metal strand 2, for example, to an intermediate strip thickness of 6 mm to 30 mm, preferably 8 mm to 25 mm.

[0059] In an optional process step S5, the intermediate strip is heated by the second heating device 110 to set a predetermined final rolling temperature. Heating the intermediate strip may be particularly necessary when relatively thick endless strips, for example, with a thickness of 10 mm to 12.7 mm, are to be produced, since in this case the casting speed—and thus also the transport speed of the metal strand 2—is lower, for example, only 4 m / min.

[0060] In principle, the final rolling temperature can also be increased further or alternatively by opening one of the stands 42 in the first rolling stand group 40.

[0061] Alternatively, the intermediate strip is cooled in process step S5 using the cooling device 120 to set the specified final rolling temperature. Cooling the intermediate strip may be particularly necessary when producing relatively thin endless strips with a thickness of, for example, 0.6 mm to 2 mm, since in this case the casting speed is very high, for example, 6 m / min, and the intermediate strip temperature therefore drops correspondingly little until reaching the second roll stand group 50. In addition, intermediate cooling using the cooling device 120 can advantageously be carried out in batch operation during the production of thermomechanically rolled grades, such as API tube grades.

[0062] In a further process step S6, the intermediate strip is descaled by the second descaling device 130 and, in a process step S7, rolled into a hot strip by the second rolling stand group 50. The second rolling stand group 50 can, for example, roll the intermediate strip into a hot strip with a thickness of 0.6 mm to 12.7 mm, preferably 0.8 mm to 12.7 mm.

[0063] The hot strip is then cooled in a further process step S8 using the cooling section 140. The hot strip surface can also be cooled, for example, using the rapid cooling unit 142 in order to achieve the appropriate microstructure right down to the strip's interior, even with thick strips.

[0064] The cooled hot strip is then wound up by means of one of the coilers 60, 62 in a process step S9. When the resulting coil has reached, for example, a predetermined weight, the strip is cut by means of the third cutting device 150, for example, a flying shear, in a process step S10 and further wound up by means of another coiler 60, 62.

[0065] Should a malfunction occur during continuous operation of the casting-rolling mill 10, for example, in the area of ​​the second rolling stand group 50, the cooling section 140, or the coilers 60, 62, after process step S2, the metal strand 2 can be separated by the first separating device 30, and the intermediate strip can be simultaneously separated by the second separating device 100. The strand or strip section located between the first separating device 30 and the second separating device 100 at this time is then successively cut into short strip pieces by the second separating device 100. These strip pieces can be removed from the mill immediately downstream of the second separating device 100 or chopped into scrap bins. This frees up the first discharge device 70.By means of the first separating device 30, the subsequently produced metal strand 2 can be cut into slabs 4, which are then immediately discharged from the transport path T by means of the discharge device 70.

[0066] FIG 3 shows an example of a method 300 for batch production, for example with the FIG 1 The casting and rolling mill 10 shown is shown. In a method step Z1, the metal strand 2 is cast from liquefied metal by means of the casting machine 20, in particular into a metal strand 2 with a thickness between 90 mm and 230 mm, preferably between 120 mm and 170 mm, and / or a width between 80 mm and 2600 mm, preferably between 900 mm and 2100 mm. The mass flow can be up to 3.5 t / min per meter of width. Casting speeds of 1.5 m / min to 6 m / min are expediently achieved with the casting machine 20.

[0067] The specific weight of the slab can be up to 25 kg / mm, preferably up to 21 kg / mm.

[0068] In an optional process step Z2, the cast metal strand 2 is subjected to a surface treatment, also known as scarfing, by means of the scarfing device 160. During this treatment, a surface layer is removed from the metal strand (2). This allows for a particularly high level of surface purity. Like the casting of the metal strand 2, the scarfing can be carried out essentially continuously.

[0069] Alternatively, it is also possible to carry out process step Z2 with a scarfing device 160 arranged behind the first separating device 30 only after a slab 4 has been separated from the metal strand 2. This allows scarfing to be performed at a higher transport speed, which reduces the thickness of the removed layer.

[0070] In a further process step Z3, a slab 4 is cut from the flame-treated metal strand 2 by means of the first separating device 30. The length of the slab 4 is, depending on the desired final product thickness and / or the desired specific weight of the final product, between 10 m and 30 m, preferably between 15 m and 25 m.

[0071] The slab 4 is accelerated immediately after being separated from the metal strand 2. In a further process step Z4, the slab 4 is heated by the first heating device 80. Since the slab head is cooler than the slab foot due to the acceleration after being separated from the metal strand 2, the heating power of the heating device 80 is preferably, in particular continuously, reduced as the slab 4 passes. This allows a constant starting temperature for the first pass in the first rolling stand group 40 over the entire length of the slab 4—and consequently also a constant final rolling temperature upon exiting the second rolling stand group 50.

[0072] Process step Z4 is optional. As an alternative to process step Z4, the slab 4 can also be accelerated so strongly after being separated from the metal strand 2 that the slab head reaches the first rolling stand group 40 before its temperature has fallen below the specified tapping temperature for the first rolling stand group 40. In this case, temperature homogeneity across the entire slab length can then be achieved in process step Z6 described below.

[0073] In a further process step Z5, the slab 4 is descaled by means of the first descaling device 90. Before entering the first rolling stand group 40, the descaled slab 4 can optionally be descaled by means of a FIG 1The strips can be upset by a not-shown upsetting device located directly in front of the first rolling stand group 40. The width reduction per side can be up to 100 mm, but at least up to 50 mm. For example, a width reduction of between 10 mm and 100 mm, preferably between 20 mm and 50 mm, can be achieved.

[0074] In a further process step Z6, the descaled and optionally upset slab 4 is rolled into an intermediate strip by means of the first rolling stand group 40. The first rolling stand group 40 can roll the slab 4, for example, to an intermediate thickness of 20 mm to 80 mm, preferably 25 mm to 75 mm.

[0075] If the temperature of the slab 4 has not yet been homogenized or has not been sufficiently homogenized in the optional process step Z4, the rolling speed in the first rolling stand group 40 can be reduced, in particular continuously, during rolling of the slab 4 into the intermediate strip. This mode of operation of the casting-rolling mill 10 is particularly energy-saving if no or at least only a low heating power is used to operate the first heating device 80.

[0076] In an optional process step Z7, the intermediate strip is scooped using the second separating device 100 to prevent undesirable deformations at the head and / or foot of the final product. Scooping using the second separating device 100 can therefore be particularly useful if the slab 4 was upset before the first rolling stand group 40.

[0077] In a further optional process step Z8, the intermediate strip is heated by the second heating device 110 to set a predetermined final rolling temperature. Heating the intermediate strip may be particularly necessary when producing relatively thick strips, for example, 20 mm to 32 mm thick, since in this case the casting speed—and thus also the transport speed of the slabs 2 and the intermediate strip—is lower, for example, only 1.2 m / min.

[0078] In principle, the final rolling temperature can also be increased by opening one of the stands 42 in the first rolling stand group 40.

[0079] Alternatively, in process step Z8, the intermediate strip is cooled by means of the cooling device 120 to adjust the specified final rolling temperature. Cooling the intermediate strip may be particularly necessary when relatively thin strips, for example, 1.2 mm to 5 mm thick, are to be produced, since in this case the casting speed is very high, for example, 6 m / min.

[0080] In a further process step Z9, the intermediate strip is descaled by the second descaling device 130 and, in a process step Z10, is hot-rolled by the second rolling stand group 50. The second rolling stand group 50 can roll the intermediate strip, for example, to a thickness of 1.2 mm to 32 mm, preferably 1.5 mm to 25.4 mm.

[0081] The strip is then cooled by means of the cooling section 140 in a further process step Z11.

[0082] Subsequently, in a further process step Z12, the cooled strip is wound up by means of one of the two coilers 60, 62. Once the entire strip produced from a slab 4 has been wound up, the following strip, ie, strip produced from a different slab 4, can be wound up by means of another coiler 60, 62.

[0083] Should a malfunction occur during batch operation of the casting and rolling plant 10, for example in the area of ​​the second rolling stand group 50, the cooling section 140 or the coilers 60, 62, the slab 4 can be removed from the transport section T by means of the first removal device 70 immediately after the process step Z3.

[0084] During batch operation of the casting-rolling mill 10, a sample can also be taken easily, for example, to ensure the quality of the final product. For this purpose, after the metal strand 2 has been separated in process step Z3, a strand section is again separated from the metal strand 2 using the first separating device 30. In this case, the first separating device 30 thus separates twice in quick succession. The short strand section thus produced can then be directly removed from the transport section T using the discharge device 70 and inspected.

[0085] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. List of reference symbols

[0086] 2Metal strand 4Slab 10Casting rolling mill 20Casting machine 22Casting bend 24Casting ladle 30First separating device 40First roll stand group 42Roll stand 50Second roll stand group 52Roll stand 60Reel 62Reel 70Execution device 72Insulating cover 80 first heating device 90 first descaling device 100 second separating device 110 second heating device 120 cooling device 130 second descaling device 140 cooling section 142 rapid cooling unit 144 laminar cooling unit 150 third separating device 160 scarfing device 200 Processes for endless strip production S1 Casting S2 Surface treatment (flaming) S3 First descaling S4 First rolling S5 Tempering S6 Second descaling S7 Second rolling S8 Cooling S9 Coiling S10 Cutting 300 Processes for batch strip production Z1 Casting Z2 Flaming Z3 Cutting Z4 Heating Z5 First descaling Z6 First rolling Z7 Cropping Z8 Tempering Z9 Second descaling Z10 Second rolling Z11 Cooling Z12 Coiling TTransport route RTransport direction LTotal transport route

Claims

1. Casting and rolling plant (10) which is capable of both endless strip production and batch strip production, with a casting machine (20) for continuously casting a metal strand (2), a first separating device (30) arranged downstream of the casting machine (20) in the transport direction (R) for separating the metal strand (2) and a first rolling stand group (40) arranged downstream of the first separating device (30) in the transport direction (R) for rolling the metal strand (2) or slabs (4) separated therefrom, wherein the transport distance (T) between the first separating device (30) and the first rolling stand group (40) is 50 m or less.

2. Casting and rolling plant (10) according to claim 1, wherein the transport distance (T) between the first separating device (30) and the first rolling stand group (40) is 30 m or less.

3. Casting and rolling plant (10) according to claim 1 or 2, wherein the transport section (T) between the first separating device (30) and the first rolling stand group (40) is free of tunnel furnaces and insulation sections.

4. Casting and rolling plant (10) according to one of the preceding claims, comprising a discharge device (70) arranged between the first separating device (30) and the first rolling stand group (40) for discharging slabs (4) or strand pieces separated from the cast metal strand (2) by means of the first separating device (30) from the transport path (T).

5. Casting and rolling plant (10) according to one of the preceding claims, comprising a first electrical heating device (80) arranged between the first separating device (30) and the first rolling stand group (40), wherein the first heating device (80) has a maximum of six longitudinal field modules and a maximum of two edge heaters.

6. Casting and rolling plant (10) according to one of the preceding claims, comprising a scarfing device (160) arranged between the casting machine (20) and the first separating device (30) or between the first separating device (30) and the first rolling stand group (40).

7. Casting and rolling plant (10) according to one of the preceding claims, with a second roll stand group (50) arranged behind the first roll stand group (40) in the transport direction (R) and two reels (60, 62) arranged behind the second roll stand group (50) in the transport direction (R), wherein a second separating device (100) and a second electrical heating device (110) are arranged between the first roll stand group (40) and the second roll stand group (50), and a cooling section (140) and a third separating device (150) are arranged between the second roll stand group (50) and the two reels (60, 62), wherein the total transport distance (L) between the first separating device (30) and the front of the two reels (60, 62) in the transport direction (R) is at most 280 m, preferably at most 230 m.

8. A method (200) for endless strip production using a casting and rolling mill (10), comprising: - a casting machine (20) for continuously casting (S1) a metal strand (2); - a first separating device (30) arranged downstream of the casting machine (20) in the transport direction (R) for separating the metal strand (2); - a first rolling stand group (40) arranged downstream of the first separating device (30) in the transport direction (R) for rolling (S4) the metal strand (2) or slabs (4) separated therefrom, wherein the transport distance (T) between the first separating device (30) and the first rolling stand group (40) is 50 m or less; - a second rolling stand group (50) arranged downstream of the first rolling stand group (40) in the transport direction (R);and - two reels (60, 62) arranged behind the second rolling stand group (50) in the transport direction (R), a third separating device (150) being arranged between the second rolling stand group (50) and the two reels (60, 62), the metal strand (2) being rolled into an intermediate strip by means of the first rolling stand group (40) and the intermediate strip being rolled into a hot strip by means of the second rolling stand group (50) (S4, S7), and the hot strip being reeled up (S9) by means of one of the two reels (60, 62) and separated (S10) by means of the third separating device (150); 9. Method (200) according to claim 8, wherein in the event of an operational malfunction in the region of the second rolling stand group (50) or downstream in the transport direction (R) - the metal strand (2) is separated simultaneously by means of the first separating device (30) and the intermediate strip by means of the second separating device (100) and - strip pieces are then separated from the intermediate strip by means of the second separating device (100) and guided out of the casting and rolling mill (10) directly in the transport direction (R) downstream of the second separating device (100) at least until a slab (4) separated from the cast metal strand (2) by means of the first separating device (30) can be guided out of the transport path (T) by a guidance device (70) arranged between the first separating device (30) and the first rolling stand group (40).

10. Method (200) according to claim 8 or 9, wherein the metal strand (2) is rolled in the first rolling stand group (40) to form the intermediate strip without the metal strand (2) being heated in the region of the transport path (T).

11. Method (300) for batch strip production with a casting and rolling plant (10), which has: - a casting machine (20) for the continuous casting (Z1) of a metal strand (2), - a first separating device (30) arranged downstream of the casting machine (20) in the transport direction (R) for separating (Z3) the metal strand (2); - a first rolling stand group (40) arranged downstream of the first separating device (30) in the transport direction (R) for rolling (Z6) the metal strand (2) or slabs (4) separated therefrom, wherein the transport distance (T) between the first separating device (30) and the first rolling stand group (40) is 50 m or less; - a second rolling stand group (50) arranged downstream of the first rolling stand group (40) in the transport direction (R); and - at least two reels (60, 62) arranged behind the second rolling stand group (50) in the transport direction (R), a third separating device (150) being arranged between the second rolling stand group (50) and the reels (60, 62);wherein a slab (4) is separated (Z3) from the metal strand (2) by means of the first separating device (30) and accelerated to a penetration speed for the first rolling stand group (40), and the slab (4) is rolled (Z6, Z10) in the first rolling stand group (40) to an intermediate strip and in the second rolling stand group (50) to a hot strip, which is wound up (Z12) by means of one of the reels (60, 62); 12. The method (300) according to claim 11, wherein the slab (4) is heated (Z4) to a predetermined tapping temperature for the first roll stand group (40) by means of a first electrical heating device (80) arranged between the first separating device (30) and the first roll stand group (40), by reducing an electrical heating power used to heat the slab (4) while the slab (4) passes the first heating device (80).

13. The method (300) according to claim 11, wherein - the slab (4) is rolled (Z6) in the first rolling stand group (40) without the slab (4) being heated beforehand in the region of the transport path (T), and - a rolling speed in the first rolling stand group (40) is reduced while the slab (4) passes the first rolling stand group (40).

14. Method (300) according to one of claims 11 to 13, wherein a surface layer of the cast metal strand (2) or of the slab (4) separated therefrom is removed during a surface treatment (Z2) by a scarfing device (160) arranged in the transport direction (R) upstream of the first rolling stand group (40).

15. The method (300) according to claim 14, wherein the surface treatment (Z2) is carried out by the scarfing device (160) in the region of the transport path (T), in particular immediately before the first heating device, at the rolling speed in the first rolling stand group (40).

Images