EP4178735B1 - Method and computer program product for calculating a pass schedule for a stable rolling process - Google Patents

Description

The invention relates to a method and a corresponding computer program product for calculating a pass schedule for a stable rolling process when rolling metal strip in a rolling mill.

Technological background

When flat rolling rolled stock, especially metallic strips, it is known that small work roll diameters must be provided in order to achieve small final thicknesses (or for reasons of energy efficiency). However, small work roll diameters limit the possible geometry of the drive pin and thus the possible drive torque, which is comparably larger with increased material strength/increased forming resistance.

A disadvantage when using small work roll diameters is the horizontal deflection of the rolls due to the horizontal force acting with a large degree of slenderness (ratio of bearing center distance to roll diameter); please refer Figure 6 . The horizontal deflection not only leads to instability of the entire set of rollers, it can even go so far that the rollers buckle. In the case of very small work rolls, the deflection can not only have a horizontal component, but also a vertical component in the direction of the roll supporting it. The desired vertical bending of the work rolls to set a roll gap contour is not relevant in this consideration.

Various measures are known in the prior art to protect and protect thin rolls against horizontal deflection during a rolling process stabilize.

One of these measures is the so-called horizontal offset. The axial extent of a pair of work rolls is offset from the pair of rolls on which it is supported. An offset set of 0 (zero) leads to an unstable roll set and is generally avoided because when the roll gap changes, the rolls can "migrate" due to bearing play and belt defects and belt breaks can occur.

A fixed offset set is suitable for hot rolling mills where the strip tensions have little critical impact on the roll gap conditions and the stability of the roll set. In cold rolling mills, especially with a large product range and/or in reversing operation and/or in non-driven work rolls, a fixed offset set is not sufficient.

A further development of the fixed offset is the so-called (horizontal stabilization) HS offset, which is set by an HS shift (device). HS displacement means that the pair of work rolls, together with their chocks, is displaced in +/- strip running direction. Essentially this is a variable setting of an offset set. The amount and direction of the HS offset are set so that the force components occurring from the vertical setting force FA and offset (horizontal force), as well as the resulting tension difference from the inlet and outlet tension Ze, Za, compensate for each other as far as possible, preferably almost completely, in all rolling phases and the roller still rests stably on one side of the roller supporting it. The page to be set can vary depending on the parameters, e.g. B. rolling force, torque, roll diameter of both rolls, inlet and outlet side strip tensions, are either on the inlet side (-) or on the outlet side (+). The horizontal forces minimized by setting the HS offset result in only minimal horizontal deflection with an absolutely stable roller position.

mit

MA

Antriebsmoment

µ

Reibwert; und

r

Radius der Arbeitswalze,

saw

Versatz

wobei die detaillierten, bekannten Berechnungen je nach Art des Walzensatzes und dessen Antriebs variieren.The setting force FA and the tension on the inlet side Ze and on the outlet side Za of the rolling stand are the main forces that are responsible for the forming work to be done on the metal strip. The force component from the offset, ie the horizontal force of the work rolls Haw, is a resulting force that results from the vectorial addition of the other force components mentioned, whereby all force components must add up vectorially to 0, as in the Figure 7 shown. The horizontal force Haw and the offset have the following functional proportional relationship: $$\mathrm{Haw}=\mathrm{f}\left(\mathrm{FA},-\mathrm{saw},\mathrm{M.A},\mathrm{Ze}-\mathrm{Za},\mathrm{\mu },\mathrm{r}\right)$$

with

M.A

Drive torque

µ

coefficient of friction; and

r

radius of the work roll,

saw

offset

The detailed, known calculations vary depending on the type of roller set and its drive.

Because work rolls with a small diameter in particular react particularly critically to excessive horizontal forces, for example, as in Figure 6 shown tend to have an undesirable horizontal deflection, it is important that the horizontal forces do not become too large when using work rolls with a high degree of slenderness. It is therefore known and common in the prior art to calculate the target horizontal force on the work roll using a pass schedule computer on which a process model of the roll process runs. The stitch schedule calculator calculates the horizontal force taking into account a variety of input data.

A clear representation of the input data on the basis of which the pass schedule calculator calculates the setup data, ie the presetting for the rolling stand before the start of a rolling process, is given in Figure 8 shown. It can be seen that the input data is system data, data on technological limits, material data, data on rolling strategy, coil data, product data and/or optionally also production planning data.

The input data traditionally also includes a predetermined initial, manually determined offset of the work roll relative to another roll in the roll stand, which is stored in a database or table and against which the work roll is supported.

The target horizontal force calculated taking these input data into account is then checked in the prior art to see whether it meets a predetermined limit criterion when rolling under constant conditions. If so, the initial offset on which the calculation of the target horizontal force was based is set on the work roll and the rolling stock is rolled. Based on the set offset, it can then be assumed that the previously calculated target horizontal force, which meets the limit criterion, acts on the offset work roll. Compliance with the limit criterion is representative of a stable roll set and rolling process.

If the initially calculated target horizontal force does not meet the specified limit criterion, in the prior art the calculation of the target horizontal force is repeated with a changed offset of the work roll from a set of N available different offsets, but with otherwise unchanged input data until determined that the last calculated target horizontal force meets the limit criterion as best as possible for the first time, taking into account the last changed (optimal) offset.

This known method represents the closest prior art. Claim 1 was therefore delimited. The known method serves to determine an optimal offset for the work roll, in which the calculated target horizontal force lies within the limit criterion and therefore ensures stable rolling conditions.

In practice it has been shown that the calculation of the target horizontal force solely by iterating the offset with otherwise constant input data, in particular with constant trains on the inlet side and / or on the outlet side of the roll stand and with a constant setting force for the work roll is not always effective. This means that when the offset is varied or iterated alone, it is not always possible for the calculated target horizontal force to meet the aforementioned limit criterion. This leads to problems, especially when using work rolls with a high degree of slenderness, especially in conjunction with high strip tensions, because these react particularly critically to excessive horizontal forces, for example with the aforementioned undesirable horizontal deflection.

The invention is based on the object of developing a known method and a known computer program product for calculating a pass schedule for a stable rolling process when rolling, in particular, metallic rolling stock, in such a way that the stability of the roll set in the rolling stand and thus the stability of the rolling process, in particular when flat rolling thin metallic strips as rolling stock with high strength is further improved with the help of thin work rolls.

This task is achieved with regard to the method by the method claimed in claim 1.

The term “setting data” refers to initialization or presetting data; These data are (pre)set on the rolling stand before the rolling process begins. Some of these can be changed later during the rolling process.

The “target horizontal force” calculated according to the invention is a pure calculation variable that cannot be set directly on the rolling stand before the start of a rolling process. As I said, this is a resultant force that results from the vectorial addition of in particular the inlet pull, the outlet pull and the setting force of the work roll in the roll stand. However, the "target horizontal force" serves as a representative variable by which the stability of a rolling process, especially when using work rolls with a high degree of slenderness, can be predicted or determined, depending on whether it meets a predetermined limit criterion that represents the stability of the rolling process , fulfilled or not. However, the resulting horizontal forces can be determined during the rolling process directly via load cells on the bending blocks (additional design effort) or indirectly via load cells, pressure measurements in the stand or the deflection rollers and torque measurements on the drive spindles (soft sensors) for the drive and operating sides of the stand .

The degree of slenderness, which is defined by the ratio of the bearing center distance to the work roll diameter, is a parameter which, as described above, affects the stability of the rolling process. With a slimness score of 5 or more, the risk of instability increases significantly.

The determination according to the invention of the optimal tensions on the rolling stock on the inlet side and/or on the outlet side of the rolling stand offers the advantage that the target horizontal force can still be kept within the limit criterion even if this is not possible through iterative variation of the offset alone is.

Another advantage of considering the target horizontal force as a whole is the minimization of the bearing load on the entire roll set, which significantly increases the service life of the roll bearings.

According to a first exemplary embodiment of the invention, the calculation of the target horizontal force for different sections k of the metal strip to be rolled is carried out separately or individually, because the metal strip has different speeds in its different sections and experiences different strip tensions.

1. 1. die mindestens zwei berechneten Soll-Horizontalkräfte für die unterschiedlichen Abschnitte des Metallbandes das gleiche Vorzeichen haben müssen; und/oder
2. 2. die berechneten Soll-Horizontalkräfte jeweils vorgegebene werkstoffabhängige Belastungsgrenzen für die Arbeitswalze nicht überschreiten.

According to a second exemplary embodiment of the invention, a limit criterion for the horizontal stability of the rolling process, in particular for the work roll, is defined as a limit criterion, according to which

1. 1. the at least two calculated target horizontal forces for the different sections of the metal strip must have the same sign; and or
2. 2. the calculated target horizontal forces do not exceed the specified material-dependent load limits for the work roll.

According to a third exemplary embodiment, the calculated target horizontal force can still be kept within the limit criterion even if this cannot be achieved solely by varying the offset and the pulls on the inlet side and/or on the outlet side of the roll stand. For this purpose, this third exemplary embodiment provides that the adjusting force for the work roll is then also varied with the optimal offset and optimal trains held constant and also with input input data otherwise held constant until it is determined that the last calculated target value is Horizontal force meets the limit criterion.

According to a further exemplary embodiment, the input data for the pass schedule calculator is, in particular, data on technological limits. According to the invention, this includes in particular: material-dependent load limits for the horizontal stability of the roll set of the roll stand, limit values including the signs for the horizontal forces, limit values for the force and work requirement, limit values for the position of the flow divide, limit values for the advance and for the torques of the rolls of the roll stand. The said and claimed roll material-dependent load limits for the horizontal stability of the roll set and in particular the work rolls should be taken into account according to the invention, in particular when calculating the target horizontal force on the work roll, the target horizontal position of the work roll, the target tension of the rolling stock at the inlet and / or at the exit of the roll stand and when calculating the target decrease for at least one pass of the roll stand.

The claimed consideration of the material-dependent load limits when calculating the said target setting data offers the advantage that the stability of the roll set, which in addition to the work rolls also includes any intermediate and support rolls of the roll stand, and thus also the stability of the rolling process as a whole is improved. This means that unwanted movement of the strip to the right or left at the exit of the roll stand, strip cracks, roll-kissing and buckling or bending of the rolls are avoided or at least minimized. By taking the material-dependent load limits into account, it is also possible to roll thin rolling stock thicknesses desired by customers with very high strength values on conventional 4-Hi, 6-Hi roll stands, multi-roll stands or on roll stands with an odd number of rolls, even asymmetrically to the , without additional mechanical ones or having to provide fluidic assemblies to support the rolls on the roll stand.

The stable boundary conditions made possible by the method according to the invention can advantageously be predetermined for the rolling process and by presetting the said (target) setting data Roll stand must be ensured before the rolling process begins. In this way, automatic threading and unthreading of the rolling stock into and out of the rolling stand can be ensured in a stable manner without additional devices. During the ongoing rolling process, the method according to the invention enables permanent monitoring of the said target setting data and, if necessary, their correction in order to ensure the stability of the rolling process even during ongoing operation. Through the method according to the invention, the product range of an existing rolling mill can be expanded regardless of the number of rolls and configuration, e.g. B. on rolling thinner final thicknesses. In addition, smaller work rolls can be used for these rolling stands in order to roll the said thinner final thicknesses and at the same time save energy.

According to a further exemplary embodiment, the method according to the invention is used not only in a single roll stand, but also in a rolling mill in which a plurality of roll stands are arranged one behind the other in the form of a rolling train. The said target setting data can not only be used for an individual rolling stand, but also for the said pass plan of a rolling train, i.e. H. preferably calculated and set according to the invention for all of their rolling stands, taking into account the material-dependent load limits.

According to a further exemplary embodiment of the invention, the actual horizontal force on the work roll is permanently monitored during the rolling process and regulated to a target horizontal force currently calculated by the pass schedule computer. The horizontal force is regulated by suitable variations of actuators that are available on the rolling stand, such as the horizontal offset of the work rolls, the tension of the rolling stock on the inlet side and/or on the outlet side of the rolling stand and/or that of the rolling stand on the rolling stock thickness reduction (adjusting force).

A further improvement in the stability of the rolling process can be achieved by also using production planning data, such as: B. Data relating to the optimization of the rolling program, data from production planning, factory planning and system utilization can be taken into account.

The measurement data obtained when monitoring the ongoing rolling process, such as the actual horizontal force, the actual horizontal position of the work rolls, the actual tension on the rolling stand at the inlet and/or outlet of the rolling stand and/or the actual actual thickness reduction of the rolling stock the roll stand are preferably compared with the associated current target setting data. Any deviations between target and actual values that may be detected in this way can be used for a preferably continuous adaptation of the process model.

Further advantages for embodiments of the method according to the invention are the subject of the dependent claims.

The above task is further solved by a computer program product. The advantages of this computer program product correspond to the advantages mentioned above with regard to the claimed method.

Figur 1

das Gesamtsystem des Stichplanrechners mit seinen Eingabedaten und Ausgabedaten, wobei die erfindungsgemäß relevanten Eingabedaten und Ausgabedaten unterstrichen sind;

Figur 2

ein Ablaufschema für das erfindungsgemäße Verfahren zum Berechnen der Soll-Horizontalkraft gemäß einem ersten Ausführungsbeispiel;

Figur 3

technologische Zusammenhänge und Unterschiede beim Einlaufen und Auslaufen eines zu walzenden Metallbandes in ein Walzgerüst (Stand der Technik);

Figur 4a, 4b

ein Ablaufschemata für das erfindungsgemäße Verfahren zur Berechnung der Soll-Horizontalkraft gemäß einem zweiten Ausführungsbeispiel der Erfindung;

Figur 5

ein Ablaufschema für das erfindungsgemäße Verfahren mit zusätzlicher Adaption des Prozessmodells;

Figur 6

das unerwünschte horizontale Durchbiegen von Arbeitswalzen mit hohem Schlankheitsgrad (Stand der Technik);

Figur 7

den Versatz der Arbeitswalze gegenüber einer sie stützenden Zwischen- oder Stützwalze im Walzgerüst sowie ein zugehöriges Kräfteparallelogramm (Stand der Technik); und

Figur 8

das Gesamtsystem des Stichplanrechners mit seinen Eingabedaten und Ausgabedaten gemäß dem Stand der Technik

veranschaulicht.A total of 8 figures are attached to the invention, where:

Figure 1

the overall system of the stitch schedule computer with its input data and output data, the input data and output data relevant to the invention being underlined;

Figure 2

a flowchart for the method according to the invention for calculating the target horizontal force according to a first exemplary embodiment;

Figure 3

technological connections and differences when entering and exiting a metal strip to be rolled into a rolling stand (state of the art);

Figures 4a, 4b

a flow chart for the method according to the invention for calculating the target horizontal force according to a second exemplary embodiment of the invention;

Figure 5

a flowchart for the method according to the invention with additional adaptation of the process model;

Figure 6

the undesirable horizontal bending of work rolls with a high degree of slenderness (prior art);

Figure 7

the offset of the work roll relative to an intermediate or backup roll supporting it in the roll stand and an associated force parallelogram (state of the art); and

Figure 8

the overall system of the stitch schedule computer with its input data and output data according to the state of the art

illustrated.

The invention is described below with reference to, in particular, Figures 1 - 5 described in detail in the form of exemplary embodiments. In all figures, the same technical elements are designated with the same reference numerals.

Figure 1 illustrates the process of the complex calculation of a pass schedule for at least one roll stand according to the method according to the invention. The core component for controlling a rolling process for rolling rolled stock With the help of at least one rolling stand there is a so-called pass schedule computer on which a process model of the rolling process runs. The process model depicts the complex forming process in the roll gap using known basic equations from forming technology and the condition of the roll set. In addition to the work rolls that span the roll gap of the rolling stock, the roll set can also include intermediate and/or support rolls of the roll stand. By running the process model on the pass schedule computer, advance calculations can be made for the next rolling stock to be rolled after the current rolling stock, recalculations regarding the current rolling stock or superimposed product optimizations can be carried out. In order to be able to calculate a stitch plan, the stitch plan calculator is supplied with input data that can be used in a suitable manner, e.g. B. must be stored in databases or in parameter files so that the pass schedule computer can access them. For example, the rolling stand or the multi-stand rolling mill must be described as input data using system data. In addition, there are technological limits for the rolling process that must be strictly adhered to. In addition, the forming behavior of the rolling stock to be rolled must be described mathematically using its material data.

Furthermore, the rolling stock to be rolled must be defined using product data. In addition, so-called coil data and the rolling strategy must each be specified as input data via strategy data. In addition, production planning data can also be used to take into account higher-level goals, such as: B. plant utilization or rolling program optimization can be taken into account. All of the terms mentioned for the input data are collective terms for various individual data that are included in Figure 1 are shown.

On the basis of this input data as well as on the basis of boundary conditions, the pass schedule computer then calculates so-called setup data, hereinafter referred to as target or initialization data, for the next step to be carried out Rolling process and sends it to the at least one rolling stand for presetting.

In contrast to Figure 8 , which shows the pass schedule calculation according to the prior art, include the data according to the invention for the technological limits Figure 1 both roll material-dependent load limits for the horizontal stability of the roll set as well as process technology limits, such as an impermissible change of sign of the horizontal force during different rolling phases of a pass schedule. A further difference to the prior art is that the horizontal stability HS position, ie the offset of the work roll to the other roll supporting it in the rolling stand, and/or the HS force, ie the horizontal force is determined during an ongoing rolling process. preferably measured and used in particular for an adaptation of the process model.

The most important difference compared to the prior art is that at least some of the setup data (in Figure 1 underlined in the "Setup data" block) are not just specified once for the entire rolling process, but are determined iteratively with a view to achieving the highest possible stability of the rolling process. I.e. The horizontal stability of the roll set, in particular the calculation of the horizontal forces on the work roll, is integrated into the pass schedule calculation.

The use of this data, which differs from the prior art, within the scope of the invention is described in more detail below.

Figure 2 shows schematically the sequence of the method according to the invention, as claimed in particular in claim 1. As part of the method according to the invention, in a first iteration in a first method step i), the input data for the pass schedule computer is provided, as previously with reference to Figure 1 described. Included according to the invention This input data also shows an initial offset of the work roll relative to another roll in the roll stand that supports the work roll. The initial offset can be determined either from a table or database, but it is preferred to determine it from Figure 7 known formula, whereby the belt tensions Ze and Za are set to zero. Before and/or during the rolling process, the method according to the invention then provides that in a second step ii) the target horizontal force on the work roll is calculated using the pass schedule computer. For this purpose, a process model of the rolling process runs on the pass schedule computer and the pass schedule calculator calculates the target horizontal force taking the input data into account.

1. 1. die mindestens zwei berechneten Horizontalkräfte für unterschiedliche Abschnitt des Metallbands das gleiche Vorzeichen haben müssen und/oder
2. 2. die berechneten Soll-Horizontalkräfte jeweils vorgegebene werkstoffabhängige Belastungsgrenzen für die Arbeitswalzen nicht überschreiten.

In a subsequent third method step iii), the target horizontal force previously determined by the pass schedule computer with the initial offset is checked to see whether it meets a predetermined limit criterion. This limit criterion represents the horizontal stability of the rolling process, especially that of the work rolls. According to the invention, this limit criterion is defined so that

1. 1. the at least two calculated horizontal forces for different sections of the metal strip must have the same sign and/or
2. 2. the calculated target horizontal forces do not exceed the specified material-dependent load limits for the work rolls.

In the event that the determined target horizontal force meets the limit criterion, the method according to the invention provides that the (optimal) offset saw _opt , which was the basis for the calculation of the target horizontal force, ie here the initial offset, is set on the roll stand and that the rolling stock or the metal strip is then rolled with the said initial optimal offset. Due to the optimal offset set, it can be assumed that rolling will then take place with the calculated target horizontal force that meets the limit criterion.

Otherwise, d. H. If the target horizontal force calculated with the initial offset does not meet the limit criterion, the method according to the invention provides for steps i), ii) and iii) in further maximum N iteration steps, each with a corrected/changed offset saw of the work roll from a set N available different offsets, but otherwise with unchanged input data, until it is finally determined in step iii) that the last calculated target horizontal force, taking into account the last changed or set optimal offset, meets the limit criterion.

verfügbaren unterschiedlichen Zügen auf der Einlaufseite und/oder mit einem jeweils veränderten Zug Za auf das Walzgut auf der Auslaufseite des Walzgerüstes aus einer Menge von $\mathrm{M}\in \mathbb{N}$

verfügbaren unterschiedlichen Zügen auf der Auslaufseite des Walzgerüstes und mit dem jeweils konstant gehaltenen optimalen Versatz saw_opt und mit auch ansonsten unveränderten Eingabedaten solange wiederholt werden, bis schließlich in Schritt iii) festgestellt wird, dass die zuletzt berechnete Soll-Horizontalkraft unter Berücksichtigung des zuletzt veränderten optimalen Zuges das Grenzkriterium erfüllt. Der besagte optimale Versatz ist derjenige Versatz, für den bei der zuvor durchgeführten Iteration des Versatzes die berechnete Soll-Horizontalkraft das Grenzkriterium am ehesten erfüllt.In the event that the calculated target horizontal force does not meet the limit criterion for any of the available N offsets, the method according to the invention provides that steps i), ii) and iii) in further maximum L and / or M iteration steps with one each changed tension Ze on the rolling stock on the inlet side of the rolling stand from a quantity of $\mathrm{L}\in \mathbb{N}$

available different trains on the inlet side and / or with a different train Za on the rolling stock on the outlet side of the rolling stand from a quantity of $\mathrm{M}\in \mathbb{N}$

Available different trains on the outlet side of the roll stand and with the optimal offset saw _opt , which is kept constant, and with otherwise unchanged input data are repeated until it is finally determined in step iii) that the last calculated target horizontal force takes into account the last changed optimal train meets the limit criterion. The optimal offset in question is the offset for which the calculated target horizontal force most closely meets the limit criterion in the previously carried out iteration of the offset.

In Figure 2 This method according to the invention is shown, with the abbreviation “saw” for the offset of the work roll, the abbreviation “Ze” for the strip tension on the inlet side of the roll stand and the abbreviation “Za” for the strip tension on the outlet side of the roll stand.

According to the invention, the calculation of the target horizontal force is not carried out uniformly for an entire metal strip, but rather individually for different sections of the metal strip. This makes sense because the speed at which the metal strip to be rolled passes through the rolling stand and the accelerations and friction conditions exerted on the metal strip are different at an inlet section of the metal strip with which the metal strip is threaded into the rolling stand or its roll gap the speed, acceleration and friction conditions of the metal strip during rolling of the middle part (fillet) of the metal strip and during rolling of the outlet section when the metal strip is braked. In addition to the speed, acceleration and friction conditions, the band tensions exerted on the metal band are also different in sections of the metal band.

Figure 3 illustrates these technological connections, which are generally known in the prior art.

This problem is addressed by the present invention in that, as mentioned, the target horizontal force is calculated individually for the individual sections k ∈ N of the metal strip. In the case of the metal strip, a distinction is made in particular between an inlet section with k=1, a middle section (fillet) with k=4 and an outlet section with k=7. According to the invention, the target horizontal forces for at least two of these sections are in the form of the horizontal force Haw einl on the work roll when threading the rolling stock with its inlet section k = 1 into the rolling gap of the rolling stand, in the form of the horizontal force Haw fillet on the work roll when rolling the fillet Rolling stock k=4 and/or in the form of the horizontal force Haw ausl when unthreading the rolling stock with its outlet section k=7 from the rolling stand is individually calculated by following steps i), ii) and iii). Figure 2 to calculate each of the target horizontal forces in the individual sections of the metal strip must be run through individually.

Figure 4a ) illustrates a further exemplary embodiment of the method according to the invention in the case that the calculated target horizontal force neither with sole iterative change of the offset nor with sole iterative change of the strip tension Ze on the inlet side of the rolling stand nor with sole change of the strip tension Za on the outlet side of the Metal strip means that the calculated target horizontal force meets the limit criterion. In this case, the method according to the invention provides that initially those optimal trains from the set of L available different trains on the inlet side and / or from the set of M available different trains on the outlet side of the roll stand, with which the calculated target horizontal forces The limit criterion is best met when the optimal offset is kept constant and the input data is otherwise kept constant. With the optimal offset and the optimal trains selected in this way, the method steps i), ii) and iii) according to the invention are then repeated with iteratively changed adjusting forces FA h from a set of H available adjusting forces with h = 1 ... H as long as until it is determined in method step iii) that the last calculated target horizontal force meets the limit criterion. The optimal values determined in this way for the offset, for the strip tensions on the inlet side and the outlet side of the roll stand as well as for the setting force are then set on the roll stand before and during a rolling process. Because the calculation of the optimal values for the individual sections of the metal strip is carried out individually, the calculated optimal parameters are also individually readjusted during a rolling process, depending on which section of the metal strip is currently being rolled.

Unlike the optimal parameters iteratively determined according to the method according to the invention, the calculated target horizontal force cannot be directly Roll stand can be preset. Rather, it is a resulting quantity that is automatically adjusted and results when the parameters in question are set on the rolling stand. If the optimal values for the said parameters are set, one can be confident that the target horizontal force meets the limit criterion and that the process will therefore run stably.

If the metal strip to be rolled passes not only through a rolling stand, but through a rolling mill with a plurality of rolling stands that are arranged one behind the other in the rolling direction, the target horizontal force for the work rolls is determined individually in the individual stands as part of the pass schedule calculation and the assigned ones are determined Iteratively determined optimal parameters for a stitch sequence on the work rolls of the rolling stands are individually preset or adjusted.

Already above with reference to the Figures 1 and 8th It was mentioned that technological limits are also supplied as input to the pass schedule calculator. According to the invention, these are in particular material-dependent load limits for the horizontal stability of the roll neck of the roll stand, limit values, including sign information, for the horizontal forces and limit values for the force and work requirement, limit values for the position of the flow divider, and limit values for the advance and for torques of drives e.g. B. for the rolls of the rolling stand.

The calculation of the HS offset to be set, taking into account the permissible horizontal forces, can be carried out as follows, for example, see Figure 4b ):
For a planned rolling pass with an initial thickness of 2.0 to 0.793 mm with a strip width of 1162 mm and a work roll diameter of 330 mm, the pass plan-specific strip tensions Ze, Za are first determined. In addition, the resulting adjusting forces FA, but especially the horizontal forces Haw threading, Haw fillet, Haw threading out for the threading in and out Threading phase k=1, k=7, as well as the rolling phase k=4 of the strip fillets are calculated with a view to various possible adjustable offset positions. To set an optimal offset position, system-specific and forming parameters are taken into account.

The calculation shows that with a constant contact force (FA), constant tensions (Ze/Za) and different offset positions saw, the horizontal forces Haw change. However, the horizontal forces Haw in the different rolling phases k or the overall resulting horizontal force Fres must be decided. If the horizontal force Haw in the rolling phases k=1, k=4, k=7 or Fres exceeds the permissible limit values, specified by the 2nd limit criterion according to the invention, this can lead to damage to the roll or process instabilities (unflatness, undesirable hysteresis). and thus to loss of production. The permitted values are as in Fig. 4a ) shown, calculated.

If the offset position leads to a change in sign (1st limit criterion) between the sections of the metal strip, this can subsequently lead to an undefined, unstable rolling situation, which not only results in poor flatness values, but also in the rollers moving freely. which can lead to damage to the roller and its bearings, as well as the neighboring rollers. In addition, the setting of the work rolls or adjacent rolls is a serious problem with regard to the strip running. The strip is driven laterally out of the roll gap. Diagonal waves or even belt tears are the result. If the horizontal forces are too low, the tendency of the scaffolding to oscillate increases and quality tolerances cannot be maintained. If the horizontal forces are too large, the dynamics of the hydraulic adjustment control are negatively influenced by increased hysteresis.

In the calculation example according to Fig. 4b It becomes clear that for the two offset positions saw of -8 and -6 there are no sign changes in the associated calculated horizontal forces Haw in the 3 band sections k=1, k=4, k=7, but that for the offset position of saw= - 8 the associated horizontal force on the work roll Haw with Fbaw with a value of 84.3kN is minimally above the permissible limit value of the material-dependent load limit of 80kN, for example.

To determine the load and consider its limits, both the resulting horizontal force HAW/2 and the maximum bending force FaBW are taken into account and compared as the Fres - resulting total force with the permissible limit criterion.

Since all conditions are positively met at an offset saw of -6, the example follows Figure 4b an optimal offset of -6 mm is set for this rolling stitch.

If the calculation of the horizontal loads and the possible offset positions from the quantity N does not result in a permissible setting, it is necessary to automatically adjust the pass schedule, as described above with reference to Figures 2 and 4a described. The strip tensions, the stitch removal, the rolling forces or the setting forces and, to a limited extent, even the work roll diameters (e.g. rolls with a new or ground roll) can be adjusted. The resulting values from the pass schedule calculation are automatically compared with those from the calculation of the horizontal load until stable conditions arise.

Figure 5 shows a further aspect of the method according to the invention. This provides that, as already in Figure 1 shown, the ongoing rolling process is permanently monitored using a wide variety of measurement data, in particular the at least one actual horizontal force and/or the actual horizontal position (=offset). are preferably detected cyclically by at least one of the work rolls and that the actual horizontal force determined in this way is compared with a current target horizontal force and / or that the actual horizontal position is compared with the current target horizontal position of the work roll. This comparison consists in particular of forming a difference. Any deviations (delta) between the target and actual values that may be detected in this way are then checked according to the invention to see whether they lie within predetermined permissibility ranges. If permissible, the deviations are used for a preferably continuous adaptation of the process model running on the pass schedule computer. This makes the process self-learning. If the deviations (delta) between the target and actual values are not permissible, the tape tensions are adjusted during the current stitch so that the deviations determined are as permissible again as possible.

The measurement data can also be, for example: rolling forces exerted on the rolling stock by the at least one rolling stand, the thickness of the rolling stock, the temperature of the rolling stock, the rolling speed, the offset of the work rolls, the tensile load on the rolling stock, motor torques from the rolling stand assigned drives, e.g. B. to start or rotate the rollers and / or cooling data, which z. B. represent the cooling of the rolling stock.

At least one, preferably both, work rolls of the rolling stock of the rolling stand are driven.

The rolling stand can be designed as a reversing stand, in which case the rolling stock is rolled in reversing operation with the help of the rolling stand.

• die Erfindung lässt sich gleichermaßen für Einzelgerüste und Tandemwalzstraßen, sowie Einweg und Reversierbetrieb einsetzen. Sie eignet sich sowohl für 4 Hi und 6Hi als auch j-Hi (j=2 bis 6) Walzgerüste.
• Für die Einstellung der Versatzposition saw wird ein bekanntes HS-Verschiebesystem eingesetzt. Dieses befindet sich konstruktiv in dem Bereich der Walzeneinbaustücke und ist an den Walzenständern befestigt. Es ist also keinerlei zusätzliche mechanische Ausrüstung entlang des Walzenballens vorzusehen. Dieser Bereich bleibt frei für eine wirksame Walzenkühlung/-Schmierung, Induktoren, Bürsten und Bandleitelemente.
• Eine Ausreizung des zulässigen und möglichen Antriebsmoments einer kleinen Arbeitswalze kann durch den Einsatz von High Torque HT-Spindeln mit Momenten- oder Temperaturüberwachung erfolgen.
• Ein Arbeitswalzen-Twin-Drive reduziert die mögliche Momenten-Verwerfung zwischen den beiden Arbeitswalzen und kann somit ebenfalls als weitere Maßnahme zur Reduktion der resultierenden Horizontalkraft oder zur weiteren Reduzierung der Walzendurchmesser eingesetzt werden.
• Die automatische Stichplan-Berechnung/Generierung mit der integrierten Berechnung der Horizontalkräfte ist mit verschiedenen Leveln der Automation verbunden.
• Die Basisautomation (Level 0, Level 1) stellt sicher, dass die berechneten Sollwerte zwingend eingestellt werden. Sind die Sollwerte nicht eingestellt (Vergleich von Sollwert und Ist-Messwert), so wird eine Einlaufsperre ausgesprochen.
• Die Stichplanberechnung und die integrierte Berechnung der Horizontalkräfte sind Bestandteil eines physikalischen Prozessmodells (Level 2) oder einer Untermenge (Teilmodelle Level 2).
• Die Modelle und/oder die Stichplanberechnung mit der verbundenen Berechnung der Horizontalkräfte können einen überlagerten Optimierungsalgorithmus aufweisen. Die Optimierung kann selbstlernend oder über Adaption erfolgen und ggf. vorliegende Messwerte berücksichtigen.
• Eine Verbindung mit einem Produktionsplanungswerkzeug (Level 2 ½ oder Level 3) kann vorgesehen sein. So können technisch nicht stabil herstellbare Stichfolgen durch einen anderen Produktionsweg doch hergestellt werden, ohne dass es an der Walzanlage selbst zu Problemen kommt. Alternativ kann durch eine Verknüpfung mit einem Produktionsplanungstool des herzustellenden Produkts angepasst werden, um an der Anlage einen Stillstand zu vermeiden.
• Ein Verbund mit einer automatschen Wartungsplanung (Level 2 ½ oder Level 3) kann vorgesehen sein, um eine Feinjustierung mit eingesetzten Arbeitswalzendurchmessern zu erreichen.
• Die vorausberechneten resultierenden Horizontalkräfte werden mit gemessenen Horizontalkräften verglichen. Für die Messung können Kraftmesseinrichtungen (z.B. Piezoelemente, Druckmessungen, Dehnungsmessstreifen oder Kraftmessdosen) im Bereich der Biegeeinrichtungen vorgesehen sein. Die Messung kann alternativ indirekt über digitale Softsensoren über beteiligte messbare Parameter zurück gerechnet werden.
• Ein Abgleich von Berechnungs- und Messwerten der Horizontalkräfte kann durch Lernalgorithmen als Bestandteil der Prozessmodelle oder eines Teilmodelles erzielt werden, so dass eine Adaption (Langzeit-/Kurzzeitadaption) der modellbasierten Berechnungen erfolgen kann.

Additional measures improving the invention:

• The invention can be used equally for individual stands and tandem rolling mills, as well as for one-way and reversing operations. It is suitable for 4 Hi and 6Hi as well as j-Hi (j=2 to 6) rolling stands.
• A well-known HS displacement system is used to adjust the offset position saw. This is structurally located in the area of the roller chocks and is attached to the roller stands. There is therefore no need to provide any additional mechanical equipment along the roll barrel. This area remains free for effective roller cooling/lubrication, inductors, brushes and strip guide elements.
• The permissible and possible drive torque of a small work roll can be maximized by using High Torque HT spindles with torque or temperature monitoring.
• A work roll twin drive reduces the possible torque distortion between the two work rolls and can therefore also be used as a further measure to reduce the resulting horizontal force or to further reduce the roll diameter.
• The automatic stitch schedule calculation/generation with the integrated calculation of the horizontal forces is connected to different levels of automation.
• The basic automation (Level 0, Level 1) ensures that the calculated setpoints are set compulsorily. If the setpoints are not set (comparison of setpoint and actual measured value), an inlet lock is issued.
• The pass schedule calculation and the integrated calculation of the horizontal forces are part of a physical process model (Level 2) or a subset (Submodels Level 2).
• The models and/or the pass schedule calculation with the associated calculation of the horizontal forces can have a superimposed optimization algorithm. The optimization can be self-learning or via adaptation and, if necessary, take existing measured values into account.
• A connection with a production planning tool (Level 2 ½ or Level 3) can be provided. This means that stitch sequences that cannot be produced in a technically stable manner can still be produced using a different production route without causing problems on the rolling mill itself. Alternatively, the product to be manufactured can be adjusted by linking it to a production planning tool in order to avoid downtime in the system.
• A network with automatic maintenance planning (Level 2 ½ or Level 3) can be provided in order to achieve fine adjustment with the work roll diameters used.
• The predicted resulting horizontal forces are compared with measured horizontal forces. For the measurement, force measuring devices (e.g. piezo elements, pressure measurements, strain gauges or load cells) can be provided in the area of the bending devices. Alternatively, the measurement can be calculated back indirectly via digital soft sensors via the measurable parameters involved.
• A comparison of calculation and measured values of the horizontal forces can be achieved using learning algorithms as part of the process models or a partial model, so that an adaptation (long-term/short-term adaptation) of the model-based calculations can take place.

Claims (13)

1. Method for calculating a pass schedule for a stable rolling process in the rolling of at least one section of a metal strip in a roll stand, comprising the following steps:

   i) provision of input data for a pass schedule computer, wherein the input data also includes a predetermined initial offset of the work roll relative to another roll, which supports it, in the roll stand; and
   before and/or during the rolling process;

   ii) calculation of the target horizontal force on the work roll with the help of the pass schedule computer, on which a process model of the rolling runs, taking into account the input data; and

   iii) checking whether the target horizontal force determined by the pass schedule computer fulfils a predetermined boundary criterion;

   if yes: setting the offset, on which the calculation of the target horizontal force was based, at the work roll and rolling the rolling material with the resulting target horizontal force; or if no: repeating steps i), ii) and iii) with a respective changed offset (saw) of the work roll from a set of N available different offsets and with otherwise unchanged input data until it is established in step iii) that the last calculated target horizontal force fulfils the boundary criterion taking into account the last changed offset;

   characterised in that

   if the iterative repetition of the steps i), ii) and iii) each with a change of the offset alone does not lead in step iii) to the target horizontal force satisfying the boundary criterion then the method in step iii) in the case of the option "if no" provides the following first modification:

   selection of that optimal offset from the set of N offsets by which the calculated target horizontal force best fulfils the boundary criterion, and

   repeating the steps i), ii) and iii) each with a changed tension on the rolling material on the inlet side of the roll stand from a set of L available different tensions and/or each with a changed tension on the rolling material on the outlet side of the roll stand from a set of M available different tensions and in each instance with the optimal offset kept constant and also with otherwise unchanged input data until it is established in step iii) that the last calculated target horizontal force fulfils the boundary criterion taking into account the last changed tension.
2. Method according to claim 1,
   characterised in that

   the metal strip to be rolled has a plurality k of sections, in particular an entry section wherein k = 1, a middle section as fillet wherein k = 2 and an exit section wherein k = 3; and

   the target horizontal forces for at least one of these sections are individually calculated in the form of the horizontal force (Haw entry) on the work roll during introduction of the rolling material by its entry section into the rolling gap of the roll stand, in the form of the horizontal force (Haw fillet) on the work roll during rolling of the fillet of the rolling material, and/or in the form of the horizontal force (Haw exit) during departure of the rolling material by its exit section from the roll stand in that the steps i), ii) and iii) for calculation of each of the target horizontal forces in the individual sections of the metal strip are run through individually.
3. Method according to claim 1 or 2,
   characterised in that
   a boundary criterion for the horizontal stability of the rolling process, particularly for the work roll, is defined as boundary criterion, according to which

   1. the at least two calculated target horizontal forces for the different sections of the metal strip have to have the same sign; and/or

   2. the calculated target horizontal forces do not exceed respective predetermined material-dependent load limits for the work roll.
4. Method according to any one of the preceding claims,
   characterised in that
   if the iterative repetition of the steps i), ii) and iii) with the undertaken change in tension and with optimal offset kept constant does not lead in step iii) to the at least one calculated target horizontal force fulfilling the boundary criterion then the method in the case of the option "if no" provides the following second modification:

   selection of those optimal tensions from the set of L available different tensions on the entry side and/or from the set of M available different tensions on the exit side by which the calculated target horizontal forces best fulfil the boundary criterion with optimal offset kept constant and with input data otherwise kept constant;

   repetition of the steps i), ii) and iii) with a respective iteratively changed adjusting force (FA) for the work roll with respective optimal offset kept constant and respective optimal tensions kept constant and also input data otherwise kept constant until it is established in step iii) that the last calculated target horizontal force fulfils the boundary criterion.
5. Method according to any one of the preceding claims,
   characterised in that

   in the rolling mill several roll stands are arranged in succession in rolling direction;

   the at least one target horizontal force for a plurality of work rolls in the roll stands arranged in succession is individually determined; and

   the associated iteratively determined optimal parameters for a pass sequence at the work rolls of the roll stands are preset or set.
6. Method according to any one of the preceding claims,
   characterised in that
   the input data comprise plant data, data with respect to technological limits, material data, data with respect to rolling strategy, coil data, product data and/or optionally also production planning data.
7. Method according to claim 6,
   characterised in that
   the data with respect to technological limits comprise at least limit values for individual ones of the following parameters:
   material-dependent load limits for the horizontal stability of the roll set of the roll stand, limit values, inclusive of sign, for the horizontal forces, limit values for the force requirement and work requirement, limit values for the position of the neutral point, limit values for the lead and for the torques of drives, for example for the rolls of the roll stand.
8. Method according to any one of claims 3 to 7,
   characterised in that

   measurement data, particularly the at least one actual horizontal force and/or the actual horizontal position of at least one of the work rolls, are detected, preferably cyclically, while the rolling process is running; and

   the actual horizontal force is compared with the respective current target horizontal force and/or the actual horizontal position is compared with the respective current target horizontal position of the work roll.
9. Method according to claim 8,
   characterised in that

   in this way possibly recognised differences between the target and actual values are checked as to whether they lie within predetermined permissible ranges; and

   if permissibility is given:

   the differences are used for a preferably continuous adaptation of the process model running on the pass schedule computer.
10. Method according to claim 8 or 9,
    characterised in that
    the measurement data are in addition, for example:
    rolling forces exerted on the rolling material by the at least one roll stand, the thickness of the rolling material, the temperature of the rolling material, the rolling speed, the offset of the work rolls, the tensile stress on the rolling material, motor torques of drives associated with the roll stand, for example for adjusting or rotating the rolls, and/or cooling data, which represent, for example, cooling of the rolling material.
11. Method according to any one of the preceding claims,
    characterised in that
    the at least one roll, preferably two rolls, of the roll stand is or are driven.
12. Method according to any one of the preceding claims,
    characterised in that

    the roll stand is configured as a reversing stand; and

    the rolling material is rolled with the help of the roll stand in reversing operation.
13. Computer program product which can be loaded directly into the internal memory of a digital computer, here in particular the memory of a pass schedule computer of a roll stand or a rolling train, and comprises software code sections by which the steps according to any one of the preceding method claims are executed when the product runs on the computer.

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