Roller arrangement and optimisation method

Abstract

The invention relates to a roller arrangement (10, 10a, 10b) for the horizontal section (20) of a casting plant (30), in particular a thin slabbing plant, a horizontal section (20) with such a roller arrangement (10, 10a, 10b), a casting plant (30) with such a horizontal section (20) and a method (100) for optimising a roller arrangement (10, 10a, 10b). The roller arrangement (10, 10a, 10b) has a plurality of pairs of rollers (12, 12a) arranged one behind the other in a transport direction (T). Each pair of rollers (12, 12a) comprises two rollers (14, 14a) arranged opposite each other. According to the invention, the distance (d1, d2) between two identical pairs of rollers (12) varies within the roller arrangement (10, 10a, 10b).

Description

[0001] Description

[0002] Role arrangement and optimization procedures

[0003] field of technology

[0004] The invention relates to a roller arrangement for the horizontal section of a casting plant, in particular a thin slab plant, a horizontal section with such a roller arrangement, a casting plant with such a horizontal section and a method for optimizing a roller arrangement.

[0005] State of the art

[0006] Casting systems for casting metal strands typically have a mold into which liquid metal is continuously fed from an intermediate container, forming a liquid level in the mold. Adjacent to the mold is an arcuate section, which may also include a bending section, consisting of a plurality of rollers, which transfers the strand emerging vertically from the mold via a straightening section to a horizontal position. The arcuate section then flows into a horizontal section (including a straightening section), which again has a plurality of rollers. After passing through the horizontal section, the strand is sufficiently cooled and stable, allowing further processing. The arcuate and horizontal sections form what is known as the strand guide of the system.

[0007] A problem that occurs with such casting systems is fill level fluctuations in the mold, i.e., a constant, particularly periodic, rise and fall in the liquid level. These fill level fluctuations are caused by bulging of the not yet fully solidified strand as it passes through the curved section and the horizontal section. Between adjacent rollers, the thin strand shell surrounding the still-liquid core can bulge. The associated volume changes in the strand lead to an oscillating metal flow in the liquid core and thus ultimately to fill level fluctuations. This effect is self-reinforcing, i.e., the fill level fluctuations or the oscillating metal flow can lead to more severe bulging.

[0008] Fill level fluctuations can have a negative impact on strand quality, particularly the surface quality of the cast strand, and make stable casting operations difficult or even impossible. The bulging associated with fill level fluctuations can also lead to the formation of internal cracks in the strand and to center segregation. There is also a risk that the strand will not have a continuous thickness after solidification. This can generally be counteracted by reducing the casting speed, but this reduces plant productivity. Therefore, other approaches have been developed to prevent strand bulging or fill level fluctuations. For example, the cooling of the strand immediately below the mold or in the bend section can be intensified or improved, for example through optimized cooling patterns. The resulting thicker and therefore more stable strand shell counteracts bulging.However, this approach is only sufficiently effective at low speeds and strand thicknesses. It is therefore not suitable for thin slab casting at casting speeds of approximately 6 m / min, i.e., for casting slabs with a thickness of 120 mm or less.

[0009] Alternatively, fill level fluctuations can be at least partially compensated by regulating the metal flow into the mold. This typically involves periodically reducing or even stopping the outflow from the tundish. However, for technical reasons, this is only possible up to frequencies of approximately 0.6 Hz. This cannot counteract faster fluid oscillations in the core of the strand, which typically occur at casting speeds above approximately 2 m / min.

[0010] Another approach is to influence the metal flow from the mold by dynamically varying the gap in the bender section (bender gap oscillations). For example, the distance between opposing rollers in the bender section can be periodically changed. This can potentially also compensate for high-frequency fill level fluctuations; however, such gap variation systems are complex, maintenance-intensive, and expensive.

[0011] It is also known from DE 102021 207 301 A1 to provide interchangeable segments for replacing strand guide elements that differ in roller spacing or roller diameter from the strand guide elements to be replaced. According to US 2018 / 0133785 A1, it is also possible to divide the rollers of a transfer unit into a plurality of sections based on the average roller spacing. The average roller spacing in each section decreases compared to the previous section.

[0012] Summary of the invention

[0013] Against this background, it is an object of the present invention to improve the avoidance or at least reduction of filling level fluctuations or bulges during continuous casting.

[0014] This object is achieved by a roller arrangement for a horizontal section of a casting plant, in particular a thin slab plant, a horizontal section with such a roller arrangement, a casting plant with such a horizontal section and a method for optimizing a roller arrangement according to the independent claims.

[0015] Preferred embodiments are the subject of the subclaims and the following description.

[0016] A roller arrangement for a horizontal section of a casting plant, in particular a thin-slab plant, according to a first aspect of the invention comprises a plurality of roller pairs arranged one behind the other in a transport direction, in particular horizontally. Each roller pair comprises two rollers arranged opposite one another, in particular vertically. According to the invention, at least two of these distances between immediately adjacent, similar roller pairs with the same diameter are different, and at least two of these distances between immediately adjacent, similar roller pairs with the same diameter are the same.

[0017] A distance between two pairs of rollers within the meaning of the invention is preferably the distance between the connecting lines, which preferably run parallel, through the rotational axis of the two rollers of each of these two pairs of rollers. The distance is therefore not a tangential distance between the outer surfaces of the rollers, but rather an axial distance.

[0018] Similar roller pairs within the meaning of the invention are roller pairs whose rollers have the same diameter.

[0019] It has been shown that the dynamics of bulging occurring during continuous casting, especially self-reinforcing effects, especially at high casting speeds of around 6 m / min, are largely determined by the roller spacing in the horizontal section of a casting plant. Extensive studies have shown that the majority of fill level fluctuations in the casting plant's mold are caused by evenly arranged rollers or roller pairs in the horizontal section.

[0020] One aspect of the invention is therefore based on the approach of distributing the rollers or roller pairs of a roller arrangement in the horizontal section of a casting plant not evenly, but unevenly one behind the other. A (horizontally) uneven distribution of the rollers or roller pairs in the horizontal section is expediently achieved by varying the (horizontal) distances between adjacent rollers of the roller pairs. It is advantageously provided that the distance between any two (adjacent) identical roller pairs changes at least once within the roller arrangement. For example, a first distance can be provided between two adjacent, identical roller pairs in one section within the roller arrangement and a second distance different from the first distance can be provided in another section. Furthermore, further, different distances can advantageously also be provided between further, adjacent roller pairs.

[0021] It has been found that such a variation in the distances between similar roller pairs within the roller arrangement enables reliable suppression of fill level fluctuations in the mold and the growth of bulges in the cast strand. Ultimately, this can result in improved strand quality, especially surface quality, and more stable casting operations. In particular, the occurrence of internal cracks and center segregation can be avoided or at least reduced.

[0022] A particularly advantageous feature of varying the distances between similar roller pairs within the roller arrangement is that it provides a passive measure for stabilizing the liquid level in the mold and for suppressing or at least reducing strand bulging. This measure is effective over a wide range of casting speeds, particularly at high casting speeds of around 6 m / min, such as those found in thin slab plants. Consequently, when using at least one roller arrangement according to the invention, there is little or no need to actively compensate for bulging or fill level fluctuations—with the associated effort and expense.

[0023] 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.

[0024] A particularly reliable prevention or at least reduction of bulging or the associated fill level fluctuations can be achieved by providing at least three different distances between each two adjacent roller pairs within the roller arrangement. For example, two or more adjacent roller pairs within the roller arrangement can be arranged at the first distance, two or more adjacent roller pairs within the roller arrangement at the second distance, and two or more adjacent roller pairs within the roller arrangement at a third distance different from the first and second distance. Such a large variation in the distances between adjacent roller pairs within the roller arrangement can effectively prevent or at least reduce regular, uniform bulging of the strand between adjacent rollers and the associated build-up of fill level fluctuations.

[0025] It can be particularly advantageous if the roller arrangement has a predetermined distribution of the spacing between adjacent roller pairs. The various spacings between adjacent roller pairs within the roller arrangement can, for example, be distributed such that the greatest spacing is provided in a central region of the roller arrangement. This enables, in particular, the arrangement of at least one drive roller pair consisting of two opposing rollers with a roller diameter that is larger than the roller diameter of rollers arranged outside the central region. The rollers of such a drive roller pair preferably have the same diameter.

[0026] Accordingly, according to the spacing distribution, in a front region of the roller arrangement with respect to the transport direction, the spacing between at least two roller pairs is expediently smaller than in the central region of the roller arrangement. For example, in the front region, three consecutive roller pairs can each be arranged at a first distance from one another. The last of these roller pairs, viewed in the transport direction, is then expediently arranged at a third, greater distance from another roller pair, in particular the driver roller pair consisting of rollers with a larger roller diameter.

[0027] Alternatively or additionally, according to the spacing distribution, the distance between at least two roller pairs is also smaller in a rear region of the roller arrangement with respect to the transport direction than in the central region of the roller arrangement. For example, in the rear region, three consecutive roller pairs can each be arranged at a second distance from each other. The first of these roller pairs, viewed in the transport direction, is then expediently arranged at a third, greater distance from the other roller pair, in particular the driver roller pair.

[0028] Irrespective of this, it can be provided that, according to the spacing distribution, the distance between at least two pairs of rollers in the front area is smaller than in the rear area, i.e., the at least two pairs of rollers in the front area are arranged closer together than in the rear area. For example, three consecutive pairs of rollers, each arranged at a first distance from one another, can be provided on the "input side" as seen in the transport direction. Three consecutive pairs of rollers, each arranged at a second distance from one another, can then be provided on the "output side." The second distance is expediently greater than the first distance.

[0029] An effective reduction in the bulging dynamics or the corresponding fill level fluctuations can be achieved, for example, by arranging at least two adjacent roller pairs in the front area at least 5 mm closer or further apart than at least two adjacent roller pairs in the rear area, i.e., for example, the first spacing is 5 mm smaller or larger than the second spacing. At the same time, it is expedient to arrange the at least two adjacent roller pairs in the front area at most 50 mm closer or further apart than at least two adjacent roller pairs in the rear area, i.e., for example, the first spacing is 50 mm smaller or larger than the second spacing.

[0030] Generally speaking, with regard to the suppression or at least reduction of oscillations of different wavelengths while providing stable support for the strand, it has proven advantageous for different distances between each two identical roller pairs to be stepped by at least 5 mm and / or at most 50 mm. In other words, the "jumps" between different distances provided between each two adjacent, preferably identical, roller pairs within the roller arrangement are at least 5 mm and / or at most 50 mm.

[0031] The horizontal section of a casting plant, in particular a thin-slab plant, according to a second aspect of the invention comprises a plurality of roller assemblies arranged one behind the other in a transport direction, in particular horizontally, wherein at least a first of the roller assemblies is designed according to the first aspect of the invention. By means of such a horizontal section, fill level fluctuations in the mold caused by the dynamics of the bulges between each two of the rollers can be passively avoided or at least reduced. As a result, improved strand quality and / or more stable casting conditions can be achieved with little effort.

[0032] In order to achieve an even more reliable prevention or at least reduction of fill level fluctuations in the mold, or to at least largely reduce the self-reinforcing effect during bulging of the strand, a second of the roller arrangements is preferably also designed according to the first aspect of the invention. Advantageously, the variation in the spacing in the at least one first roller arrangement differs from the variation in the at least one second roller arrangement.

[0033] A second roller arrangement configured in this way allows for a larger number of different spacings between each pair of identical rollers within the horizontal section. If the first and second roller arrangements are also essentially identical in construction, i.e., in particular, structurally interchangeable, the additional second roller arrangement can also be used to achieve a variation in the sequence of different spacings between the roller pairs. For this purpose, different arrangements or sequences of the first and second roller arrangements are conceivable, for example.

[0034] Of course, further roller arrangements with further, different variations of the spacing can also be advantageously provided.

[0035] In order to be able to design the at least one first and the at least one second roller arrangement, and optionally also the further roller arrangements, so that they are structurally interchangeable, it is expedient if the at least one first and the at least one second roller arrangement have the same length in the transport direction, i.e. are of equal length. In particular, all of the roller arrangements can be structurally identical except for the distances between at least some of the roller pairs. For this purpose, all of the roller arrangements of the horizontal section can have the same frame. The length of the roller arrangement is expediently defined as the distance from the first roller to the last roller of the roller arrangement. The structural interchangeability of the roller arrangements, in particular the first and the second roller arrangement, allows great flexibility and variation in the design of the horizontal section.

[0036] A particularly effective prevention of fill level fluctuations or reduction of the dynamics of bulges in the horizontal section can be achieved by arranging several, i.e., at least two, first roller assemblies and several, i.e., at least two, second roller assemblies alternately. In other words, a sequence of first and second roller assemblies is provided in at least one section of the horizontal section, preferably in an alternating manner.

[0037] In principle, other arrangements or sequences of multiple first and second roller assemblies are also conceivable. For example, two second roller assemblies can always be provided between each first roller assemblies. In another variant, two second roller assemblies can always follow two first roller assemblies. Variants are also conceivable in which further roller assemblies designed according to the first aspect of the invention are arranged, for example, alternately or in a different manner with the first and second roller assemblies.

[0038] The casting plant, in particular a thin-slab plant, according to a third aspect of the invention has a horizontal section according to the second aspect of the invention. In such a casting plant, fill level fluctuations in the mold caused by the dynamics of the bulges between each two rollers in the horizontal section can be passively suppressed or at least mitigated. As a result, improved strand quality and / or more stable casting conditions can be achieved with minimal effort.

[0039] Fill level fluctuations in the mold that occur in a casting plant or the oscillations of the liquid metal that occur in the strand cast by the casting plant are caused not only by the spacing of the rollers in the horizontal section, but also, for example, by the rollers in the curved section. If, in addition to those according to the invention, conventional roller arrangements with evenly spaced roller pairs are also provided in the horizontal section, this can also amplify the fill level fluctuations or the bulging dynamics. In order to counteract this, it is expedient that the variation in the distance between any two similar roller pairs in a roller arrangement according to the first aspect of the invention is also predetermined with regard to these "external" contributions to the fill level fluctuations or the bulging dynamics, i.e. contributions made outside of the roller arrangements according to the invention.In other words, it is advantageous to adapt the roller arrangement according to the invention with regard to the entire casting plant or at least the entire horizontal section, in particular to predetermined casting conditions.

[0040] This can be achieved with the computer-implemented method for optimizing a roller arrangement for the horizontal section of a casting plant, in particular a thin slab plant, according to a fourth aspect of the invention.This method comprises: i) a simulation step in which fill level fluctuations in a mold of a casting plant are simulated on the basis of a plant model in which a horizontal section of the casting plant has a roller arrangement with a plurality of roller pairs arranged one behind the other in a transport direction, in particular horizontally, each consisting of two rollers opposite one another, in particular vertically; ii) an association step in which the simulated fill level fluctuations, in particular the intensity of these fill level fluctuations, are associated with distances between two identical roller pairs of the roller arrangement; and iii) the simulation step and the association step are repeated for at least one changed distance between at least two identical roller pairs of the roller arrangement, and iv) all simulated fill level fluctuations, in particular their intensity, are compared with one another.As a parameter that describes the strength of the fill level fluctuation, a standard deviation of the temporal progression of the fill level in a time window of defined length can be evaluated, for example. In this way, the optimal distribution of the spacing between the roller pairs of the roller arrangement, at which the fill level fluctuations are the smallest, can be determined. On the basis of the result of the comparison, a roller arrangement of a horizontal section of a casting plant is expediently optimized, i.e. the rollers of the roller arrangement of the horizontal section are spaced according to a simulation result, for example to avoid or at least reduce fill level fluctuations. In this way, for example, an existing roller arrangement can be replaced with an optimized roller arrangement or an optimized roller arrangement can be used directly when redesigning a horizontal section.

[0041] A plant model within the meaning of the present invention is preferably a thermomechanical dynamic model of the entire casting plant, in particular the mold, the curved section, and the horizontal section. Using this model, the bulging behavior of the cast strand can be comprehensively analyzed and an optimized roller arrangement can be determined.

[0042] The simulation of fill level fluctuations advantageously includes determining a wavelength and / or frequency of strand bulging in the casting system. Preferably, the contribution of each roller pair in the horizontal section, and preferably also in the curved section, to the fill level fluctuations or bulging dynamics is also determined and taken into account when spacing the roller pairs.

[0043] The method according to the fourth aspect of the invention is preferably carried out by means of a computing device, for example a computer or a programmable logic controller (PLC), for example before a metal strand is cast for a new product, such as a metal strand with a changed thickness.

[0044] 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.

[0046] FIG 1 shows an example of a roller arrangement;

[0047] FIG 2 an example of a casting plant;

[0048] FIG 3 shows an example of an alternative configuration of the horizontal section of the casting plant from FIG 2; and

[0049] FIG 4 shows an example of a method for optimizing a roller arrangement.

[0050] Where appropriate, the same reference numerals are used in the figures for the same or corresponding elements of the invention.

[0051] Description of the embodiments

[0052] FIG 1 shows an example of a roller arrangement 10 for the horizontal section of a casting plant, in particular a thin slab plant, with a plurality of roller pairs 12 arranged one behind the other in a transport direction T. Each of these roller pairs 12 consists of two rollers 14 arranged opposite one another transversely to the transport direction T. Between the rollers 14 of each pair 12, a gap D is thus formed, in which a cast strand can be guided.

[0053] The roller pairs 12 are spaced apart from each other along the transport direction T at different distances di, d2, and da. The distances di, da, da are measured between the rotation axes R of adjacent rollers 14 in the transport direction T, each of two roller pairs 12. The rollers 14 are arranged by means of a carrier 16 within a length L, defined as the distance between the first and last roller pair 12 of the roller arrangement 10 in the transport direction T.

[0054] For reasons of clarity, only one of the roller pairs 12 is highlighted in FIG. 1 by a dotted oval and provided with a reference symbol. For the same reason, only two of the rotation axes R and only two of the rollers 14 are provided with a reference symbol.

[0055] In particular, in a front region V of the roller arrangement 10, as viewed in the transport direction T, adjacent roller pairs 12 are arranged at a first distance di from one another. These roller pairs 12 are designed identically to the roller pairs 12 in a rear region H of the roller arrangement 10, as viewed in the transport direction T. This means that the rollers 14 of these roller pairs 12 in the front and rear regions V, H are identical to one another, in particular have the same diameters. Adjacent roller pairs 12 in the rear region H are arranged at a second distance d2 from one another, which differs from the first distance di.

[0056] Generally speaking, the distance di, d2 varies between any two identical roller pairs 12 within the roller arrangement 10.

[0057] In a central region M of the roller arrangement 10, a roller pair 12a can be provided, the rollers 14a of which have a larger diameter than the rollers 14 in the front and rear regions V, H. Unlike the rollers 14 in the front and rear regions V, H, the rollers 14a in the central region M expediently serve as drive rollers, i.e., they can be actively rotated by means of a drive device (not shown). The roller pair 12a in the central region M is arranged at a third distance da from the adjacent roller pairs 12 in the front and rear regions V, H, which third distance can differ from the first and second distance di, d2.

[0058] Conveniently, the third distance da is greater than the first and second distances di, da. This simplifies the arrangement of the drive rollers 14a between the rollers 14 in the front and rear areas V, H.

[0059] The second distance da can be greater than the first distance di. However, it is also possible that the second distance da is smaller than the first distance di.

[0060] By distributing the spacing of the roller pairs 12 in this way, in particular by providing different spacings d1, d2 between similar roller pairs 12, the dynamics of bulges in the cast strand occurring between adjacent rollers 14 in the transport direction T can be positively influenced when a partially solidified cast strand is guided by the roller arrangement 10 in a horizontal area of ​​a casting plant. In particular, the build-up of bulges, as occurs with consistently regular spacing of similar roller pairs in conventional roller arrangements, can be prevented or at least reduced. This also results in a reduction in fill level fluctuations in a mold of the casting plant.It has been shown that these positive effects cannot be achieved - or at least not to this extent - solely by different distances between the roller pairs 12 in the front and rear areas V, H and the driver roller pair 12a in the central area M (ie when the first and second distances di, d2 are equal).

[0061] The aforementioned positive effects can also be achieved by a different spacing distribution of the roller pairs 12 than that described above. For example, according to another, equally advantageous spacing distribution, the first spacing di can be greater than the second spacing d2. Alternatively or additionally, further (different) spacings can also be provided between further similarly designed roller pairs 12.

[0062] FIG 2 shows an example of a casting plant 30, in particular a thin slab plant, for casting a strand 40. The casting plant 30 comprises a mold 32 which can be continuously filled with liquid metal 42 from an intermediate container 34, so that a liquid level 44 forms in the mold 32. The strand 40 emerging from the mold 32 and still having a liquid core can be transferred from the vertical to the horizontal by means of a plurality of support rollers 36a arranged along an arc. The support rollers 36a form an arc section 36 of the casting plant 30. Adjoining the arc section 36 is a horizontal section 20 which is formed from a plurality of roller arrangements 10a, 10b arranged one behind the other in a transport direction T and indicated by dashed rectangles.Each of these roller arrangements 10a, 10b has a plurality of roller pairs 12 arranged in a row in the transport direction T, wherein each roller pair 12 is formed from two rollers 14 arranged opposite one another.

[0063] For reasons of clarity, only one of the roller pairs 12 is highlighted by a dotted oval and provided with a reference symbol. For the same reason, only one of the support rollers 36a and two of the rollers 14 are provided with a reference symbol.

[0064] The spacing between adjacent, similar roller pairs 12 varies within the respective roller arrangement 10a, 10b. This means that at least two adjacent roller pairs 12 are arranged at a first distance from each other, and at least two further adjacent, similar roller pairs 12 are arranged at a second distance different from the first distance (see FIG. 1). The structure of the first roller arrangements 10a with regard to the spacing of adjacent, similar roller pairs 12 expediently differs from the structure of the second roller arrangements 10b.For example, there may be a smaller difference between the distances at which similar roller pairs 12 are arranged in a front section of the first roller assemblies 10a, on the one hand, and in a rear section of the first roller assemblies 10a, on the other hand, than between the distances at which similar roller pairs 12 are arranged in a front section of the second roller assemblies 10b, on the one hand, and in a rear section of the second roller assemblies 10b, on the other hand. Alternatively or additionally, the distance distribution may also differ between the first and second roller assemblies 10a, 10b, ie, for example, whether the distance between adjacent, similar roller pairs 12 within the respective roller assembly 10a, 10b increases or decreases.

[0065] The roller assemblies 10a, 10b expediently have the same length L and are thus structurally interchangeable. In particular, all roller assemblies 10a, 10b can be mounted in the horizontal section 20 using similar frames (see FIG. 1), between which the rollers 14 are rotatably mounted, for example. This allows a multitude of possible configurations of the horizontal section 20 to be realized with little effort and flexibility, as described below by way of example in connection with FIG. 3.

[0066] Conveniently, the frames are also designed to be similar to frames of conventional roller assemblies (not shown), which have a constant spacing between similar roller pairs 12. This allows existing casting systems to be retrofitted with roller assemblies 10a, 10b, which have varying spacings between similar roller pairs 12, with little effort and at low cost.

[0067] In principle, the casting system 30 can also have, in addition to the two first and two second roller assemblies 10a, 10b shown, further first and second roller assemblies 10a, 10b, which are expediently arranged alternately in the transport direction T. Alternatively or additionally, one or more conventional roller assemblies with a constant distance between similar roller pairs 12 can be provided in front of and / or behind the four roller assemblies 10a, 10b shown.

[0068] FIG. 3 shows an example of an alternative configuration of the horizontal section 20 of the casting system from FIG. 2. Here, the two second roller assemblies 10b are arranged between the two first roller assemblies 10a. This pattern can be continued in the transport direction T if further second and / or first roller assemblies 10b, 10a are provided. In a further alternative (not shown), it can also be provided that two first roller assemblies 10a and two second roller assemblies 10b are provided alternately.

[0069] FIG 4 shows an example of a computer-implemented method 100 for optimizing a roller arrangement for the horizontal section of a casting plant, in particular a thin slab plant.

[0070] In a simulation step S1, fill level fluctuations in a mold of a casting plant are simulated based on a plant model of the casting plant. The plant model, in particular a thermomechanical dynamic model of the casting plant, expediently describes (among other things) a horizontal section of the casting plant comprising a roller arrangement with a plurality of roller pairs arranged one behind the other in a transport direction, each pair comprising two rollers arranged opposite one another. To simulate the fill level fluctuations, a wavelength and / or frequency of strand bulges occurring in the cast strand and the resonance of these bulges can be determined, for example by a thermomechanical simulation for the solidification of the strand. Possible input parameters of the plant model include: the initial position of the liquid level in the mold, i.e.the filling level of the mold; the casting speed; the chemical composition of the liquid metal fed into the mold; the material properties of the mold; the roller geometry, in particular the positions of the support rollers in the curved section and / or the rollers in the horizontal section; the dimensions of the strand (thickness and width) and the cooling of the strand.

[0071] In an association step S2, the simulated fill level fluctuations are associated with the distances between two identical roller pairs in the roller arrangement. For each roller pair in the horizontal section, its respective contribution to the fill level fluctuations can be determined. This is conveniently done using an elasticity model of the strand based on beam theory.

[0072] The simulation step S1 and the association step S2 are repeated in a further method step S3, preferably for at least one changed distance between at least two similar roller pairs of the roller arrangement in the horizontal section. This allows a comparison of all simulated fill level fluctuations in a further method step S4. Based on this comparison, the configuration of the roller arrangement can be expediently determined in which the fill level fluctuations are the smallest (for example, the standard deviation of the fluctuations is the smallest).

[0073] In this way, new casting plants can be planned with an optimized roller arrangement or a horizontal section having one or more optimized roller arrangements. The roller arrangement(s) optimized using the method 100 described can suppress or reduce strand bulges or the corresponding fill level fluctuations so effectively that, in a casting plant planned in this way, further measures to suppress or at least reduce strand bulges or the corresponding fill level fluctuations are not necessary, or at least only to a reduced extent. If necessary, the optimized roller arrangements can also be used in existing casting plants in order to create more stable casting conditions there as well and to be able to cast higher-quality strands.

[0074] 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.

[0075] List of reference symbols

[0076] 10, 10a, 10b roller arrangement

[0077] 12 pairs of rollers

[0078] 12a Driver roller pair

[0079] 14 rolls

[0080] 14a Driver roller

[0081] 16 frames

[0082] 20 horizontal section

[0083] 30 casting plant

[0084] 32 mold

[0085] 34 intermediate containers

[0086] 36 arch section

[0087] 36a support roller

[0088] 40 strands

[0089] 42 liquid metal

[0090] 44 Liquid level

[0091] 100 procedures

[0092] S1 Simulation of fill level fluctuations

[0093] S2 Association of filling level fluctuations with distances between two similar pairs of rollers

[0094] S3 Repeat the simulation step and the association step

[0095] S4 Comparing the simulated fill level fluctuations

[0096] T Transport direction

[0097] L length

[0098] D gap di first distance d2second distance d3third distance

[0099] M mid-range

[0100] V front area

[0101] H rear area

[0102] R rotation axis

Claims

Claims 1. Roller arrangement (10, 10a, 10b) for a horizontal section (20) of a casting plant (30), in particular a thin slab plant, formed from a plurality of roller arrangements (10, 10a, 10b) arranged one behind the other in a transport direction (T), with a plurality of roller pairs (12, 12a) arranged one behind the other in the transport direction (T), each consisting of two rollers (14, 14a) arranged opposite one another, wherein immediately adjacent roller pairs are spaced apart by a distance (di, da, da) in the transport direction, characterized in that at least two of these distances (di, da) between immediately adjacent identical roller pairs are different and at least two of these distances (di, da) between immediately adjacent identical roller pairs are the same.

2. Roller arrangement (10, 10a, 10b) according to claim 1, wherein at least one first pair of rollers, preferably a driver pair of rollers, is designed such that it differs from the similar pairs of rollers, wherein the rollers of the first pair of rollers have a different, preferably a larger diameter than the rollers of the similar pairs of rollers.

3. Roller arrangement (10, 10a, 10b) according to one of the preceding claims, comprising a predetermined distribution of the distances (di, da, da) between adjacent roller pairs (12, 12a), wherein the greatest distance (da) is provided in a central region (M) of the roller arrangement (10, 10a, 10b) according to the distribution.

4. Roller arrangement (10, 10a, 10b) according to one of the preceding claims, comprising a predetermined distribution of the distances (di, da, da) between adjacent roller pairs (12, 12a), wherein according to the distribution in a front region (V) of the roller arrangement (10, 10a, 10b) with respect to the transport direction (T) the distance (di) between at least two roller pairs (12) is smaller than in a central region (M) of the roller arrangement (10, 10a, 10b).

5. Roller arrangement (10, 10a, 10b) according to one of the preceding claims, comprising a predetermined distribution of the distances (di, da, da) between adjacent roller pairs (12, 12a), wherein according to the distribution in a rear region (H) of the roller arrangement (10, 10a, 10b) with respect to the transport direction (T) the distance (da) between at least two roller pairs (12) is smaller than in a central region (M) of the roller arrangement (10, 10a, 10b).

6. Roller arrangement (10, 10a, 10b) according to one of the preceding claims, wherein at least two identical roller pairs (12) are arranged in a front roller arrangement with respect to the transport direction (T). Area (V) of the roller arrangement (10, 10a, 10b) are arranged more closely than in a rear area (H) of the roller arrangement (10, 10a, 10b) with respect to the transport direction (T).

7. Roller arrangement (10, 10a, 10b) according to one of the preceding claims, wherein different distances (di, d2) between two identical roller pairs (12) are 5 mm to 50 mm increments.

8. Horizontal section (20) of a casting plant (30), in particular a thin slab plant, with a plurality of roller arrangements (10, 10a, 10b) arranged one behind the other in a transport direction (T), wherein at least a first of the roller arrangements (10a) is designed according to one of claims 1 to 7.

9. Horizontal section (20) according to claim 8, wherein at least a second of the roller assemblies (10b) is designed according to one of claims 1 to 7 and the variation of at least one distance (d1, d2) in the at least one first roller assembly (10a) differs from the variation of at least one distance (d1, d2) in the at least one second roller assembly (10b).

10. Horizontal section (20) according to claim 9, wherein the at least one first and the at least one second roller arrangement (10a, 10b) have the same length (L) in the transport direction (T).

11. Horizontal section (20) according to claim 9 or 10, wherein a plurality of first roller assemblies (10a) and a plurality of second roller assemblies (10b) are arranged alternately.

12. Casting plant (30), in particular thin slab plant, with a horizontal section (20) according to one of claims 8 to 11.

13. Computer-implemented method (100) for optimizing a roller arrangement (10, 10a, 10b) for the horizontal section (20) of a casting plant (30), in particular a thin slab plant, formed from a plurality of roller arrangements (10, 10a, 10b) arranged one behind the other in a transport direction (T), comprising: - in a simulation step (S1), simulating fill level fluctuations in a mold (32) of a casting plant (30) on the basis of a plant model in which a horizontal section (20) of the casting plant (30) has a roller arrangement (10, 10a, 10b) with a plurality of roller pairs (12, 12a) arranged one behind the other in a transport direction (T), each consisting of two rollers (14, 14a) arranged opposite one another; - in an association step (S2), associating the simulated filling level fluctuations with distances (di, d2) between two identical roller pairs (12) of the roller arrangement (10, 10a, 10b); - repeating (S3) the simulation step (S1) and the association step (S2) for at least one changed distance (di, d2) between at least two similar roller pairs (12) of the roller arrangement (10, 10a, 10b); and - Compare (S4) all simulated fill level fluctuations.

14. A computer-implemented method according to claim 13, comprising: Selecting a simulated level fluctuation with the associated distances (di, d2), wherein the simulated level fluctuation has the smallest standard deviation, wherein the standard deviation is determined for a time window of defined length.

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