EP0906797B1 - Method and device for straightening a metal strip in a hot rolling mill - Google Patents

Abstract

The strip material is moved alternating over and under at least two stretch-levelling working rollers (7,8), between a cooling zone and a coiler. The working rollers are offset relative to each other, to deflect the strip on every roller. The rollers are of two types, being cylindrical or with a negative or positive roller crown. The rollers are self-propelled, and the stretch-levelling zone is water cooled.

Description

The invention relates to a method and a system for Forming of metal strip in a hot strip mill from a finishing train, a cooling section, a driver and a reel system, according to the preamble of claims 1, 2 and 13 (see e.g. U.S.-A-4,316,376). It is known to metal after the casting process in a hot strip mill to certain thicknesses, then to roll them after a coiling process of a cold strip rolling mill for rolling to the final dimension. Here are the cold strip mill fed metal strip ever higher requirements in terms of its mechanical and geometric properties, especially its flatness.

At the same time there is a tendency towards the desired final properties of the metal band, which are made up of the series Processes of hot and cold rolling mill result to be set in the hot rolling process or to produce a hot strip, the optimal conditions for the subsequent Bring cold rolling. At the same time, the Boundary conditions during hot rolling are more difficult. It is growing thinner and wider products to adapt to the end product wanted what a greater thickness reduction and a Use of larger rolling forces in the end stands of the hot wide strip mill requires. The consequence of this is that the Wear of the rolls with increasing decrease of the roll gap elevated. The thermal crown of the rollers also increases increased production on the rolling mill. These effects work adversely affect the flatness of the hot strip and thus also on the quality of the tape when cold.

A well-known means of producing flat hot strip is that Use of actuators. Stand with extremely thin tapes but currently hardly or no reliable hot strip flatness measurements to disposal.

It also occurs in a hot wide strip mill to the unevenness caused by the finishing train become, also to changes in flatness of the metal strip in the cooling section and through the driver rollers.

The belt leaves the finishing train with an uneven part Flatness or stress distribution over the Bandwidth. This can lead to the fact that despite the same boundary conditions (such as geometric dimensions, trains, Temperatures, material, etc.) for tapes in quick succession rolled, different flatnesses arise in the cold strip. The uneven flatness distribution of the hot strip then leads directly or indirectly through changed winding conditions on the reel (for example higher coilcrown) to different Flatness of the cold strip.

Furthermore, the deflection of the belt on the driver changes in the direction of the desired reel system due to the different Tension distribution across the width of the strip flatness. The main influencing factors are the ground ones Driver shape, the wear of the driver rollers, the contact pressure as well as the thermal crown of the driver rollers. Indeed can optimize the driver grinding as well as a Change of driver role material or driver role changing practice improve the boundary conditions.

When the tape is wound up into the coil, one is created uneven tension distribution over the bandwidth.

This generates different ones depending on the train level Belt extensions over the bandwidth and thus unpleasantness for the cold state. The main influencing factors are here the emerging coilcrown. The shape of the coil depends of the strip contour, the strip flatness during reeling, the material strength (temperature, material quality) and the Reel train from.

The disadvantage is that the changes in flatness on the Driver role as well as on the reel as well as by cooling of the coil cannot be influenced directly. hereby local flatness of the tape arises. There was also beating observed the immediate end of the band.

The object of this invention is a method and a system for setting the desired flatness and Tension conditions in hot strip to provide in To get cold state flat belt.

This object is achieved by the features of claims 1, 2 and 13 solved. Advantageous embodiments of the invention are shown in disclosed in the subclaims.

The core of the invention is the provision of a method and a system, wherein the strip material after exiting the cooling zone alternately above and below at least two successive stretching judge work rolls under Formation of a stretch judge zone is performed, the Stretching judge work rolls are arranged offset to each other are that the metal strip on each stretcher judge work roll is redirected. Alternatively, the function of two Stretching judge work roles by the two alone Driver roles are taken over. The stretching judge zone will then by turning the top or bottom drive roller in the area before or after the original driving roller position created.

In contrast to a known device for stretch bending straightening, as disclosed in DE 36 36 707 C2 proposed according to the invention, the stretching judge zone at the end of the hot rolling process. The stretching judge zone will by additional straightening rollers according to the Traction rollers or trained by means of the traction rollers themselves. In contrast, the aforementioned German patent discloses a stretch bending straightener with a downstream Rolling stand.

By passing the tape through such a trained The stretching judge zone can be in the metal strip before it Reeling to the coil the desired flatness or tension properties can be set. With that it gets through the use of a higher quality, already planned hot strip possible, negative influences from the upstream processes largely eliminate and the quality of the tape in to improve cold condition.

In the simplest case, two stretcher judge work rolls are sufficient to form a stretch judge zone, wherein the metal strip is not rolled between the rollers, but bent and stretched between the successively arranged rolls becomes.

This has the consequence that flatness is compensated for as well more uniform voltage ratios can be set.

By post-treating the belt with straightening rollers the impurities from the finishing train, for example, parabolic and flatness higher Order as well as the unplannedness and tensions that in the cooling section arise, eliminated. Furthermore, disadvantageous Damage to the end of the belt in the form of local flatness and hitting the immediate end of the band through the Avoiding or using these stretcher leveler work rolls can be reduced.

Through the proposed stretcher judge work roles that it is located behind the driver and in front of the reel possible, in addition to the unevenness from the finishing train and cooling section itself the flatness changes on the driver to eliminate. Furthermore, reproducible flatness conditions can be set. To damage the belt surface to avoid, the rollers should be driven independently are or have a low moment of inertia.

On the other hand, it is also conceivable that it is already operational To produce hot strip, the desired thin final dimensions having. The stretching rollers according to the invention can already A sufficient degree of flatness has been set for hot strip be, so under certain circumstances entirely on the cold strip process can be dispensed with.

A stretching judge zone is advantageously divided by three Stretcher judge work rolls of a first type, which are arranged one behind the other. The stretch judge work rolls of the first type have a cylindrical shape.

Another advantageous embodiment of the invention is the use of a stretcher judge work roll of a second Type that advantageously with two stretcher leveler work rolls of the first type is combined. This is what happens If possible, metal strip first through the stretching judge zone, formed from the roles of the first type, then over the Role of the second type to be led. Through a special one Training the crown of this role of the second type can then existing flatness of the metal strip is compensated become. This can be uneven across the bandwidth Train distribution will be generated with the aim of To stretch the tape locally so that it is as cold as possible is plan.

It is of course just as conceivable here that the stretch straightener unit from just one stretcher judge work roll of the first Type in combination with two stretch leveler work rolls of the second type.

With this combination two can be arranged one behind the other Straightener work rolls of the second type and an upstream one Straightener work roll of the first type, the is preferably cylindrical. This will make the Flexibility of the stretching judge zone in response to different flatness of the tape, which is very different from the Production line and the cooling line - as described above is dependent - increased.

With the provision of a roll of the second type, the cross-warping becomes (cross bow) of the tape, often cold is observed, positively influenced.

It is also conceivable that the stretch judge zone out Stretching judge roll (s) of the second type with subordinate (s) Role (s) of the first type. Basically everyone is Combinations with more than two roles of one or the other Type conceivable.

For optimal setting of the position or contact pressure of this second stretcher judge work roll of the second type the measured values for strip contour, strip temperature distribution, the strip thickness and the tension level as well as the information the legalities derived from the offline cold flatness evaluation etc. can be used. It can be different Straightener work roll settings over the length of the tape.

By means of the proposed two-part training of the role of the second type it is possible to use different bandwidths or to react flexibly to band unevenness during the process, because of the strip edge-oriented displaceability the fixed or oscillating roller body the roller accordingly can be adjusted.

The lower drive roller can also advantageously perform the task the first stretch leveler work roll of the first type take.

The stretching judge zone can alternatively also by the upper and lower drive roller are formed. This will be achieves that when the reel has caught the tape head, the upper driver roller is swiveled sideways downwards and thus the belt is deflected on the drive rollers.

Also in the embodiment with driving rollers and straightening rollers usually do not touch this on the tape head Tape. Only after the build-up of tensile stresses Straightener rollers swung into the working position.

A belt zone cooling is advantageously in the stretching judge zone, in particular water cooling. This belt zone cooling can preferably take the form of a scale washer be trained. The tape is used on both sides High pressure pressurized with water which allows remove the tertiary scale at the same time. Behind this Cooling zone, i.e. in front of the reel device is a temperature measuring device intended.

It is also recommended that, in addition to the belt, the stretch straightener rollers be chilled to the thermal crown as well reduce wear. Known water cooling devices are conceivable here.

It is advantageous not only in the band zone cooling Stretching judge zone, but also immediately before the To perform reel setup. Here is the Spraying technique using water or another liquid, which serves as a lubricant / release agent, cheap. A lubricant is recommended because of the sliding properties of the tape layers to each other during the cooling of the coil.

As a particularly preferred embodiment of the invention claimed integration of a stretch judge zone at the end a hot rolling process, i.e. still after going through the Finishing line, is proposed for setting a flat belt, that the employment of the stretching judge roles to Band and with each other by means of a first control loop in Dependency on the belt properties is currently regulated be measured. The level of tape tension can also be regulated which is different over the length of the tape.

For this it is possible, for example, that behind the stretching judge zone, seen in the belt conveying direction, a flatness measuring roller is arranged. This is a segmented tension measuring roller. The recorded by this measuring roller Values are used in the form of signals in a control loop Control of the stretching judge actuators and / or the finishing train actuators for further influencing flatness used. It is conceivable that the roles of the first and second type, which form the stretching judge zone, as segmented Tension measuring rollers are formed.

Finally, it is advantageously proposed that means a second control loop the settings of the Dependent cooling zone upstream cooling section depending are regulated by the belt properties. Preferably the control of the actuators of the stretching judge zone with the Control of the actuators of the cooling section with each other coupled by placing both control loops on a common one Use setpoint. Actual and setpoint of these two Control loops are the band properties. These are for example the temperature distribution over the bandwidth, the belt contour and / or the belt tension.

Known cooling patterns are used to control the cooling section resorted. For example, the setting is conceivable the cooling device such that a diminished Cooling effect occurs in the band edge area or that an additional Cooling effect of the band edge area arises or a parabolic change in temperature distribution over the bandwidth.

As is known, changes in the temperature distribution result over the bandwidth band unevenness due to different thermal shrinkage. In interaction with the downstream stretch straightener unit and the These cooling patterns are applied to a cooling behavior Compensation of the effects and thus an overall planer To get tape.

Finally, it is conceivable with another control loop also the mechanical actuators of the stretch leveler work rolls depending on the belt properties regulate.

To target the tension level in the stretching judge zone To be able to increase, it is also proposed to be a stretch judge against a roller arranged below this press or increase their immersion depth.

Alternatively, another driver can be installed in front of the Stretching judge zone, seen in the direction of strip travel become.

Figur 1

eine schematische Ansicht der erfindungsgemäßen Inline-Streckrichterrollen zwischen Treiber und Haspel einer Warmbandwalzanlage

Figur 2

eine schematische Ansicht des Endbereichs einer konventionellen Warmbandwalzanlage;

Figuren 3 und 4

schematische Ansichten von Ausführungsformen der Streckrichterzone, die durch Streckrichter-Arbeitsrollen des ersten Typs gebildet ist, wobei die Ausführung gemäß Figur 3 nicht unter den Schutzbereich den Ansprüche fällt.

Figuren 5 bis 7

schematische Ansichten von Ausführungsformen der Streckrichterzone, die aus Streckrichter-Arbeitsrollen des ersten und zweiten Typs gebildet ist, wobei die Ausführung gemäß Figur 5 nicht unter den Schutzbereich der Ansprüche fällt.

Figur 8

eine schematische Darstellung der Spannungsverhältnisse im Metallband bei Ausbildung der Rolle des zweiten Typs mit einem negativen Crown;

Figur 9

eine schematische Darstellung der Spannungsverhältnisse im Metallband bei zweigeteilter Ausbildung der Rolle des zweiten Typs;

Figur 10

einen Querschnitt der Rollenform nach Figur 9.

Figuren 11a,b

schematische Darstellungen mechanischer Stellglieder der Streckrichter-Arbeitsrolle;

Figur 12

Streckrichtermodell zur optimalen Einstellung der Streckrichter-Arbeitsrollen.

Figur 13

ein schematische Darstellung der Ausbildung der Streckrichterzone allein durch die Treibrollen;

Figur 14

eine schematische Darstellung der Ausbildung der Streckrichterzone mittels einer Rollgangsrolle und der unteren Treibrolle;

Figur 15

eine schematische Darstellung der Anordnung der Streckrichterrollen, welche kurz vor dem Ausfädeln des Bandendes aus dem letzten Walzgerüst gegeneinander gepreßt werden.

Further details and advantages of the invention emerge from the claims and the following description, in which exemplary embodiments of the invention illustrated in the drawings are explained in more detail. Show it:

Figure 1

is a schematic view of the inline stretch straightening rollers according to the invention between the driver and reel of a hot strip mill

Figure 2

a schematic view of the end region of a conventional hot strip mill;

Figures 3 and 4

schematic views of embodiments of the stretching judge zone, which is formed by stretching judge work rolls of the first type, the embodiment according to FIG. 3 not falling under the scope of the claims.

Figures 5 to 7

schematic views of embodiments of the stretch leveler zone, which is formed from stretch leveler work rolls of the first and second type, the embodiment according to FIG. 5 not falling within the scope of the claims.

Figure 8

a schematic representation of the tension in the metal strip when forming the role of the second type with a negative crown;

Figure 9

is a schematic representation of the tension in the metal strip with two-part design of the role of the second type;

Figure 10

a cross section of the roll shape of Figure 9.

Figures 11a, b

schematic representations of mechanical actuators of the stretching judge work roll;

Figure 12

Straightening judge model for optimal setting of the straining judge work rolls.

Figure 13

a schematic representation of the formation of the stretching judge zone solely by the drive rollers;

Figure 14

is a schematic representation of the formation of the stretching judge zone by means of a roller table roller and the lower drive roller;

Figure 15

is a schematic representation of the arrangement of the stretch straightening rollers, which are pressed against each other shortly before the end of the strip from the last roll stand.

After the rolling process in the hot strip mill, this runs Metal strip 1 via guide rollers via a driver 2, consisting from an upper 3 and lower 4 driver role to one Reel 5 to go there to a coil for further transport, mostly in a cold rolling mill to be rewound (figure 2).

Figure 1 shows here that according to the invention between the driver 2 and the reel 5, a stretch judge zone 6 is provided is here made up of two cylindrical ones arranged one behind the other Straightener work rolls 7 and a straightener work roll of the second type 8 is formed. Between the work rolls 7,8, which are driven independently, cooling systems 9a, here in the form of spray water nozzles, are provided, to increase the strip temperature across the width or thickness influence. Another cooling system 9b is just before Coil arranged. This is shown schematically in Figure 1 as one Spray nozzle 9b shown. By means of this cooling system 9b an additional lubricant is applied to the belt, to the sliding properties of the tape layers to each other while to improve the cooling of the coil.

The strip material runs alternately above and below the Straightening judge work rolls 7.8. The roles are in With respect to their axes of rotation so offset from each other that the metal strip 1 is deflected on each stretcher judge work roll becomes. By disrupting a straight band existing tensions in the band are influenced or new ones Tensions are generated that are beneficial to a flatness of the tape.

FIGS. 3 and 4 show embodiments of the stretch judge zone 6, which consist of either two or two three cylindrical stretch leveler work rolls 7 is composed. By means of the arrangement of the stretcher leveler work rolls 7 behind the driver 2 can even imprecision in the Drivers 2 are generated, eliminated before reeling become.

In Figure 5, the embodiment of Figure 3 is adopted with the additional arrangement of a stretcher judge work roll of the second type 8 behind the driver 2. FIG. 6 shows the embodiment of the stretching judge zone 6 of Figure 4, here also a stretching judge work role of second type 8 as the last station of the metal strip the reeling process is provided.

Figure 7 shows a similar constellation of roles as in Figure 6. In contrast to this, the lower drive roller 4 used as the first stretch roll.

The tension conditions when arranging a stretcher judge work roll of the second type 8 with a negative crown arise, Figure 8 represents. By those described above Rolling conditions as well as high loads and wear of the Rolls in the rolling mill create flatness in the metal strips and excessive tension at the band edges. Around to compensate for changes in flatness from warm to cold state, is a stretcher leveler work roll 8a with negative Crown provided. It is possible in the band edges to cause a change in length and in the so treated Tied a positive tension with a maximum in the middle and set minimum tensions at the edge.

With the help of the two-part stretch straightening roller 8b (Figure 9) the tension distribution of the band can be dependent of its width, d. H. its impertinence, to be influenced. As a result, a tape stretch becomes too higher order (non-parabolic) reached to be advantageous to act on the cold flatness.

Figure 10 shows a schematic representation of the two-part Roll 8b when laying a tape 1. The roll parts 9 can be moved back and forth to each other. You are either firmly mounted or arranged oscillating on the shaft 10.

To better the properties of the stretch leveler work rolls To be able to influence, it is proposed to use the roles mechanical actuators. Opportunities for this are for example roller bending, adjustable support roller (s) or an inflatable roll. This is the deflection the stretcher judge work rolls and thus the effect on the line variably influenced under load. Figure 11 a shows schematically the storage of a stretcher judge work roll, being on the Bearing pin 11 influenced by roller bending 12 can be.

Figure 11b illustrates the influence of one or two employable Support rollers 13 and their arrangement to the stretching judge work roll 7th

For optimal adjustment of the position of the straightening judge work rolls and the starting pressure as well as the setting the mechanical actuators to influence the roll deflection a variety of influencing factors must be taken into account become. These influencing variables go as a manipulated variable within of control loops. Figure 12 gives an overview about the influencing factors.

The band contour, the band temperature distribution, the strip thickness and width, the strip tension distribution as well as their level, the drive roller stiffness and their strength and shape (thermal crown, cut, Wear) and the strip material properties in Dependence on forming speed and temperature.

On the one hand there are elastic, thermal and the wear behavior of the stretch judge work rolls. In the stretch judge model will also provide data on the Flatness change when cooling the coils and information recorded from measured cold flatness evaluations.

In the embodiment with a tension measuring roller for measuring the Flatness according to claim 14 is also the correcting variable measured warm flatness behind the stretching judge zone with in the stretch judge model.

After receiving these parameters it is possible to get an optimal one Position (immersion depth) and an optimal contact pressure the stretch judge work rolls of the first and to determine and adjust the second type. Can continue from the calculation the amount of cooling water over the range for strip zone cooling. In addition, one Activation of the mechanical actuators for influencing the stretch roll deflection possible.

Examples of mechanical actuators are roller bending, adjustable support rollers or inflatable rollers. As influenceable Control value is also provided the belt tension level, that can vary across the length of the tape. in this connection it is provided that the actuators of the stretching judge rollers and thus the tension level varies over the length of the belt is adjustable. That means it will be for the individual Actuators have different setpoints.

The recorded values can also be used as a control variable the cooling device downstream of the finishing train used, for example, the temperature distribution over the bandwidth already through adapted cooling equalize. Different cooling patterns can be set here, as for example from the patents DE 32 30 866 or EP 0 449 003 B1 are known. background is taking into account that the band cools faster at the edge than in the middle. Reduced cooling of the edges - this is achieved, for example, by inactivating the edge spray nozzles a chilled beam - compensates for this different heating processes across the range and creates a tape with a more even temperature distribution.

Figure 13 shows a second alternative of a device for Execution of the proposed method, the stretch judge zone just by the top 3 and bottom 4 drive roller is formed. After the reel has gripped the ribbon head (Figure 13 a), the upper drive roller 3 is down, laterally pivoted along the lower drive roller 4 (FIG 13 b, c). The drive rollers 3, 4 have the in this position Function of two stretch judge work rolls. In this embodiment the stretching judge zone is behind the (Original) position of the driving rollers. You can choose between: a gap 14 between the lower 4 and the upper Drive roller 3 can be set in the shut down state (Figure 13 c).

Finally, an embodiment is possible in which the Straightener zone 6 by a roller 15 of the roller table as well the lower drive roller 4 of the driver 2 is formed (Figure 14). The roller 16 is used to generate the bending effect the passline panned.

FIG. 15 schematically shows an advantageous arrangement of the Straightener rolls just before threading out the end of the belt the finishing train. Here, the straightening roller 7, here exemplary of the first type, against one arranged below Roller 17 pressed to maintain the necessary retraction. If no roller 17 is provided, a greater immersion depth or a larger amount of bending for the Straightener roll chosen to complete the bending stretch straightening process when unthreading the tape end.

The proposed method and device can be general used in the manufacture of metals. In particular machining of steel and aluminum is planned.

Claims (23)

1. Method of reshaping metal strip in a hot strip rolling plant, wherein the rolling strip after running through a finishing train and a cooling path is fed by way of a driver, which consists of an upper and a lower driver roller, to a coiling device, wherein the strip material (1) in a region between the end of the cooling path and the coiling device is led in alternation above and below at least two stretch-levelling working rollers (7, 8), which are arranged one after the other, with formation of a stretch-levelling zone (6) and wherein the stretch-levelling working rollers (7, 8) are so arranged offset relative to one another that the metal strip is deflected at each stretch-levelling working roller (7, 8), characterised in that the strip is subjected to a stretching process between driver (2) and coiling device (5) by means of the arrangement of stretch-levelling working rollers (7, 8) behind the driver (2).
2. Plant for reshaping metal strip, consisting of a rolling train with downstream cooling path, driver and coiling device for carrying out the method according to claim 1, characterised in that two stretch-levelling working rollers of a common type are provided in the region between the driver (2) and the coiling device (5).
3. Plant according to claim 2, characterised in that in each instance two stretch-levelling working rollers of one type are used in combination with a stretch-levelling roller of another type.
4. Plant according to claim 2, characterised in that in each instance two stretch-levelling working rollers of one type are used in common with an additional stretch-levelling working roller of the same type.
5. Plant according to one of claims 2 to 4, characterised in that the stretch-levelling working rollers (7) of a first type are cylindrical.
6. Plant according to one of claims 2 to 4, characterised in that the stretch-levelling working roller of a second type (8) has a negative or positive roller crown (8a).
7. Plant according to claim 6, characterised in that the stretch-levelling working roller of the second type (8b) is composed of two stretching roller bodies (9) which are separated from one another and fixedly mounted or are mounted on a shaft (10) to be oscillating, the stretch roller bodies each being displaceable oriented with respect to the strip edge.
8. Plant according to claims 2 to 7, characterised in that the lower roller of the driver (3) is used as a stretch-levelling roller of the first type (7).
9. Plant according to one of claims 2 to 8, characterised in that the stretch-levelling working rollers (7, 8) are independently drivable.
10. Plant according to one of claims 2 to 9, characterised in that the stretch-levelling working rollers (7, 8) of the first and second type are provided with mechanical setting elements such as roller bending means, adjustable backing rollers and inflatable rollers.
11. Plant according to one of claims 2 to 10, characterised in that a strip zone cooling (9a), particularly a water cooling, is provided in the stretch-levelling zone (6).
12. Plant according to one of claims 2 to 10, characterised in that a device (9b) is provided for application of a lubricant to the strip.
13. Plant for reshaping metal strip, consisting of a rolling train with downstream cooling path, driver and cooling device for carrying out the method according to claim 1, characterised in that the upper and lower rollers of the driver (3, 4) take over the function of stretch-levelling working rollers by pivotation of the upper drive roller laterally downwardly.
14. Plant according to one of the preceding claims, characterised in that a planarity measuring roller is arranged after the stretch-levelling zone (6) as seen in strip running direction.
15. Plant according to one of the preceding claims, characterised in that one stretch-levelling roller (7, 8) is constructed as a segmented tension measuring roller.
16. Plant according to one of the preceding claims, characterised in that at least one driver device, which consists of two rollers, for increase in tension stress is provided in front of the stretch-levelling zone as seen in strip running direction.
17. Method according to claim 1, characterised in that the adjustment of the stretch-levelling rollers relative to one another and to the strip is regulated in dependence on the strip characteristics and/or on the characteristics of the drive rollers or stretch-levelling working rollers by means of a first regulating circuit.
18. Method according to claim 1, characterised in that the settings of the cooling path are regulated in dependence on the strip characteristics and/or on the characteristics of the drive rollers or stretch-levelling working rollers by means of a second regulating circuit.
19. Method according to claim 1, characterised in that the mechanical setting elements of the stretch-levelling working rollers are regulated in dependence on the strip characteristics by means of a third regulating circuit.
20. Method according to claim 1, characterised in that the level of strip tension is regulated in dependence on the strip characteristics and/or on the characteristics of the drive rollers or stretch-levelling working rollers by means of a fourth regulating circuit.
21. Method according to claims 17 to 20, characterised in that the first and/or the second and/or the third and/or the fourth regulating circuits are coupled together and refer back to common target values.
22. Method according to one of claims 17 to 20, characterised in that the strip contour, the strip temperature, the strip thickness and width, the strip tension stress distribution and/or the planarity characteristics of the strip after running through the stretch-levelling zone come into play as strip characteristics.
23. Method according to one of claims 17 to 20, characterised in that the drive roller stiffness, force and shape and/or the thermal and/or wear properties of the stretch-levelling rollers come into play as characteristics of the drive rollers or stretch-levelling working rollers.

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