EP0850704B1 - Method for rolling a band - Google Patents

Abstract

The method concerns production of a rolled strip either in a rolling section with at least two roll stands with horizontally adjustable upper and lower working rolls (which act alone or are supported directly or via intermediate rolls on support rolls), or in a reversing stand with at least two passes. At least in one region of the strip the target nonplanarity profile is predetermined over the strip width and compared with the measured nonplanarity form. The resultant difference is calculated. The available mechanically or physically acting control elements are employed to minimise this difference as far as possible. Also claimed is the apparatus comprising at least two of the following control elements: (a) movable working rolls (10, 11) or their bending units (13); (b) means for pair-wise crossing of the working rolls and the support rolls (9); (c) zone cooling (15) of the working rolls; (d) thermal covers (18) for working rolls; (e) strip edge heaters (14); (f) strip edge coolers (16); and (g) strip edge lubricators (17).

Description

The invention relates to a method and an apparatus for Rolling a rolled strip in at least two roll stands belt conveyor with horizontally adjustable upper and lower work rolls that work alone (Duo scaffolding) or each of which can be directly or above supports an intermediate roller on a backup roller, or with a reversing stand on which at least two passes are rolled in which the roll of a state change is subjected to profile and flatness Actuate actuators on the rolled strip.

In practice, there are always higher demands on the Hot strip flatness as well as cold strip flatness. At the same time, the boundary conditions for hot rolling are also considered more difficult because of increasingly thinner and wider products be demanded, resulting in higher decreases and increased Rolling forces also in the rear stands. It takes the wear with a large decrease in (CSP systems), and the "Thermal Crown" increases with high road production, e.g. B. for continuous rolling or in an aluminum hot strip mill.

It follows that an elementary technical and there is an economic need for this through an optimal "Presetting" an improved band flatness even under to comply with more extreme boundary conditions, and accordingly there is a need to improve the flatness of a Rolling strip also within the street, depending on the Purpose of use and depending on the calculated Processes in the cooling of the hot strip on the Outfeed roller table and in the coil.

When hot rolling strip material are subject to within one Rolling program the thermal crowning and wear the work rolls and their elastic deformations relative big changes. Without correction by actuators changes with increasing rolling material throughput the roller contour. The effect is scaffolding too Scaffold or different from stitch to stitch. With that changes in addition to the belt contour, the specified one Hot strip flatness and subsequently also the cold strip flatness.

When rolling in one width, a number of strips with the same width or approximately the same width are rolled in succession within a rolling program. In addition to the value of the strip profile specified for a certain point (e.g. C ₄₀ or C ₂₅ ), the strip profile shape as a whole and, accordingly, the specified strip flatness also change for strip areas in the middle and in particular for areas of the strip near the edge. For example, the increasing drop in the thermal crowning of the rolls or the wear of the work rolls near the edge lead to undesirable profile anomalies. These are thickened areas in the edge area (beads), or on the contrary, the thickness in the edge area drops. Such profile anomalies considerably restrict the rollable length in a width. The roll length in one width is defined as the sum of all strip lengths that are rolled in a width or approximately the same width.

From DE 30 38 865 C1 it is known to change the thermal crown and the work roll wear by suitable actuators such as shifting and / or Bending members, e.g. B. "CVC" - (Continuously Variable Crown) shift or to compensate for suitable cooling.

According to EP 0 276 743 B1 it is known to control crowning and / or the edge drop of the belt the horizontal displacement of the work rolls as well as the bending forces acting on them on the upstream side Group of rolling stands of a tandem mill according to the rolling conditions including the width of the belts.

To control wear and thermal crowning of the work rolls with the aim of avoiding unwanted profile shapes and unplannedness, the work rolls are located in a group of roll stands located on the downstream side pushed back and forth at predetermined intervals. Here are the back frames after each band in opposite directions by a certain amount postponed; if the shift amount has reached a maximum value, the Reverse shift direction. This cyclical shifting causes wear equalized the work rolls to a larger area.

To control the flatness of a in a cold rolling mill with a rolling stand produced rolled strip is described in FR-A-2 640 894 a method in which the control of the shapes and conditions of the work roll surfaces during the rolling process with an actuator is made. To do this, use a flatness measuring device to display the Flatness of the rolled strip over its width and for generating an output signal the actuating device is put into operation so that it flatness controls the rolled strip. The output signal is a plurality analyzed by index values to set them as approximate sizes by which based on an approximate evaluation (means for fuzzy reasoning) by reasoning set a control output value for the actuator becomes. The work rolls can then either be controlled from the outside or heated or cooled on the inside and / or at least one of the intermediate rolls and / or the outer roller (s) moved, bent or changed in the apex.

From US-A-5,193,066 a method for controlling and controlling a Rolling process known in which in a cold rolling mill for the production of aluminum foils the rolled strip is rolled in one pass and then wound up. The rolling process is also regulated here with regard to the flatness of the strip, that a tape of the desired shape is obtained. To control the rolling parameters both current and saved data of the belt geometry used.

EP 0 618 020 A1 discloses a method for rolling a rolled strip in a generic roll stand with horizontally adjustable upper and lower Work rolls, with profilund Actuate flatness actuators on the rolled strip. The well-known rolling process allows it, despite being more flexible Rolling programs meet the requirements for profile accuracy and the flatness of the rolled strip to correspond approximately, if one Target contour of the profile of the rolled strip is specified successively reaching two groups of actuators act on the rolled strip, from which actuators the first Group above the critical thickness Rolling strip thicknesses are used and primarily the Contour of the rolled strip in its central area influence while actuators in a second group Rolling strip thicknesses below the critical thickness in Band edge area can be used.

However, the measures known in the prior art are sufficient not out to meet the increased requirements in particular with regard to flatness even under extreme conditions to be able to fulfill. These exist when generating Hot strip in particular, flexible rolling programs to be able to put together, in addition to larger thicknesses and Material changes before all breadth leaps in the direction narrow and wide are desired (mixed rolling). Moreover the number of tapes should be the same for economic reasons Width within a rolling program without impairment of profile accuracy and flatness can be increased.

The invention has for its object a method and to specify a device with which despite flexible Rolling programs meet the increased demands on the Hot strip flatness as well as the cold strip flatness and in Interact with it so that profile accuracy can be fulfilled, and with the help of the measures to be proposed Process through an optimal presetting an improvement the flatness also within the street as well as an improved Strip flatness is generated even under extreme conditions should be dependent on the intended use and the processes for cooling the hot strip on the Outfeed roller table and in the coil.

The method is also used in a Cold mill or a cold stand. Also be here Band contour changes in the immediate band edge area carried out and an "edge-drop" -free contour aimed at, with the unevenness as well as belt tension especially within the band edge.

These objects are achieved with the invention in a method for rolling a rolled strip in the preamble of claim 1 Specified genus by the characteristic features of the Claim 1 solved. It is no longer one Target flatness related to a reference point of the strip assumed, but rather a target non-flatness form specified the width of the tape, and on the other hand one in actually reached a certain band range Non-flatness form determined and with the given Non-flatness form compared, a difference is calculated from it and available mechanically or physically effective actuators used in such a way that the Difference is minimized as much as possible.

With the aid of the method according to the invention, a optimal presetting an improved band flatness even under created more extreme boundary conditions.

• Arbeitswalzenverschleiß
• Thermischer Crown (Zonenkühlung, Abdeckschalen)
• Walzkraft, z. B. infolge Walzenabplattung
• Spezial-Walzenschliff (Anti-Wulst-Walze, Tapered Roll)
• Online-Arbeitswalzen-Schleifvorrichtung
• Bandtemperaturänderungen an der Kante (positiv/negativ)
• Bandkantenschmierung

All actuators or parameters that influence the elastic behavior of the roller set can cause a parabolic-type belt extension across the width. Influencing factors that change the waviness or tape extensions, particularly in the edge area, are as follows:

• Work roll wear
• Thermal crown (zone cooling, cover shells)
• Rolling force, e.g. B. due to roll flattening
• Special roller grinding (anti-bead roller, tapered roll)
• Online work roll grinding machine
• Edge temperature changes (positive / negative)
• Strip edge lubrication

Depending on the requirements, actuators are included primarily parabolic or higher order effects activated in the area of the edges.

The method according to the invention provides that a target and flatness form of the strip is specified as a function of the intended use and of the processes during the cooling of the hot strip on the outfeed roller table and in the coil. It is not sufficient here to just have a target flatness or target unevenness value based on the z. B. C ₄₀ point to specify, but it is necessary to strive for a lengthening / shortening of the width or a flatness of higher order.

For example, instead of or in addition to the default a target flatness or non-flatness value a profile of Target stress distributions or target extensions over the Width specified and with the factually reached or calculated stress distributions or extensions be compared. The resulting differences will be then calculated and the actuators used in the manner that these differences are minimized as much as possible.

The procedure for determining the belt contour or Belt contour change and thus the belt tension distribution over the width or the band extension over the width shown in the flowchart of FIG. 12.

The process steps for generating a desired one Belt tension distribution or belt extension across the width FIG. 13 shows the flowchart.

Advantageously, in a hot mill to generate an in plan cold condition with the warm tape over the Band length different non-flatness forms specified.

For the intended generation of the different Hot strip unevenness becomes the work roll bending, PC stand angle, CVC shift or others Actuators changed over the length of the belt.

The procedure further provides that if there is insufficient Minimize the differences in the input conditions of the responsible scaffolding changed and the result is optimized. In addition to mechanically effective actuators physically effective actuators can also be used. These can be preset on the head, as well as over the tape length can be adjusted variably. They are for example strip edge cooling, strip edge heating, Rolling force distribution or band edge lubrication.

For a better overview of the processes taking place and the change of state of the tape, the description of the target values as well as the values actually achieved is carried out by dividing the bandwidth into a body area and an edge area. The non-flatness form can be described by a polynomial function y * = A ₂ x ² + A ₄ x ⁴ + A ₆ x ⁶ + A _n x ⁿ , where y * represents the coordinate for the tape lengthening, tape unevenness or tape tension, and x the bandwidth coordinate ,

See a further advantageous embodiment of the method before that around the target positive and negative limits (Tension, flatness, lengthening / shortening) defined and the actuators are used in such a way that the band tension distribution, flatness distribution, distribution of band lengthening / shortening within the limits.

To create a band extension / shortening parabolic or superordinate type across the bandwidth are preferably used actuators that the elastic Influence the behavior of the roller set, whereby this Actuators axial displacement means for the CVC work rolls or bending devices for these or both means at the same time include.

Furthermore, the invention provides that for Avoidance of corner waves on the warm band and in the Cold condition of the strip, a redistribution of the rolling force in the Is made that the rolling force at least in last stand reduced and the rolling force upstream located scaffolding is increased.

The processes during cooling of the are very advantageous Rolling strip on the outfeed roller table as well as in the coil Band extensions / shortenings taking place both in Body area as well as in the area of the band edges analyzed and the changes in length determined or calculated corresponding presetting of the actuators at least in last frame compensated.

And finally, with the method according to the invention preferably provided that mechanically acting actuators used and by non-mechanical, e.g. B. positive or negative thermal actuators are supported.

A device for performing the method according to the Invention is characterized by at least two or several of the actuators listed in the device claim in the area of the rolling mill.

These can be axially displaceable or CVC work rolls Work roll bending devices include. In addition, you can the work rolls can be designed to be interlocking. to These can be thermally influenced by the work rolls for example equipped with a thermal cover be, or optionally with zone cooling. The Work rolls can continue with special roll grinding or be equipped with an online grinder. For a case by case required thermal correction of the band edge areas furthermore provided that the device before, within or after the finishing train, e.g. B. in the area of Roller conveyor, a band edge heating, or even before, within or after the finishing train Has band edge cooling device. And finally can a belt edge lubrication device within the finishing train be provided.

Further details, features and advantages result from the claims and the description below of some in the drawings of illustrated embodiments of the Invention.

Fig. 1

in schematischer Darstellung den erfindungsgemäßen Aufbau einer Anlage zur Durchführung des Verfahrens,

Fig. 2.1 - 2.5

Diagramme zur Ermittlung der Bandverlängerung über die Breite des Bandes,

Fig. 3.1 - 3.2

je ein Diagramm eines Walzprogramms nach Breite/Dicke des Walzgutes,

Fig. 4

die Form einer Anti-Wulst-Walze (gemäß EP 0 672 471 A1),

Fig. 5.1 - 5.6

Einfluss der Anti-Wulst-Walze beim Wegdrücken von Bandwulsten im Kantenbereich, betreffend die Gerüste 1 bis 6,

Fig. 6.1 - 6.4

Planheiten höherer Ordnung ohne Anwendung des Verfahrens nach der Erfindung,

Fig. 7.1 - 7.4

Einführung von Planheitslimits höherer Ordnung bzw. Vergabe einer negativen Ziel-Planheit höherer Ordnung im randnahen Bereich,

Fig. 8.1 - 8.6

Konturregelung durch Änderung der Schiebepositionen von CVC-, Anti-Wulst- und konventionellen Walzen,

Fig. 9

die Form einer Tapered-Walze,

Fig. 10.1 -10.4

Einfluss der Tapered-Walze mit und ohne Berücksichtigung von Planheitslimits höherer Ordnung,

Fig. 11.1 -11.6

Einfluss einer Walzkraftumverteilung auf die Bandplanheitsform bzw. Form der Bandverlängerung über der Bandbreite,

Fig. 12

Flussdiagramm zur Erzeugung einer gewünschten Bandverlängerung über die Breite,

Fig. 13

Flussdiagramm zur Entstehung von Kaltbandunplanheiten und deren Verminderung.

Show it:

Fig. 1

a schematic representation of the construction of a plant according to the invention for performing the method,

Fig. 2.1 - 2.5

Diagrams for determining the belt length across the width of the belt,

Fig. 3.1 - 3.2

a diagram of a rolling program according to the width / thickness of the rolling stock,

Fig. 4

the shape of an anti-bead roller (according to EP 0 672 471 A1),

Fig. 5.1 - 5.6

Influence of the anti-bead roller when pushing tape beads in the edge area, relating to the stands 1 to 6,

Fig. 6.1 - 6.4

Higher order flatnesses without using the method according to the invention,

Fig. 7.1 - 7.4

Introduction of higher-order flatness limits or allocation of a higher-order negative flatness target near the edge,

Fig. 8.1 - 8.6

Contour control by changing the sliding positions of CVC, anti-bead and conventional rollers,

Fig. 9

the shape of a tapered roller,

Fig. 10.1 -10.4

Influence of the tapered roller with and without taking into account higher order flatness limits,

Fig. 11.1 -11.6

Influence of a redistribution of rolling force on the strip flatness shape or the shape of the strip extension over the strip width,

Fig. 12

Flow chart for generating a desired band extension across the width,

Fig. 13

Flow chart for the occurrence of cold strip unevenness and its reduction.

In Figure 1 is the achievement of predetermined target non-flatness across the width of a rolled strip (3, 4) enabling rolling mill (6) - partly schematic and with only symbolic markings for the mechanical Actuators - including the elements that support them and in the form of "black boxes" for computers and measuring devices shown.

The plant consists of several rolling stands, one of which only the first and the last roll stand (7) or (8) are shown. However, it can also involve a rolling mill act on a reversing stand with which several passes are rolled become. Each roll stand (7, 8) has horizontally adjustable, upper and lower work rolls supported by backup rolls (9) (10, 11). The latter are axially displaceable, preferably with a CVC shift (12) and with Work roll bending devices (13) equipped; the Work rolls (10, 11), provided with ground or thermal wear contour, by means of CVC shift (12) and work roll bending (13) as mechanical Actuators either in the middle of the band or in Band edge area used.

To support these mechanical actuators (12, 13) is in front of and behind the first scaffolding of the finishing train Change in the edge heating of the rolled strip (3) or (4) a band edge heater (14) is arranged. For thermal Influencing the band shape via changes in the thermal Crowns of the work rolls (10, 11) have the rolling train (6), preferably in the area of the front or rear roll stands, a work roll zone cooling (15), e.g. B. in the form of corresponding zones on the work rolls (10, 11) directional spray nozzles, such as. B. behind the first Roll stand (7) shown. For the thermal influence of the Belt edges continue to wear belt edge cooling (16) with z. B. spray nozzles arranged in the side guides and Work roll cover trays (18) as for the last one Roll stand (8) shown as an example. The lubrication (17) of the Work rolls (10, 11) in the band edge area affect the Load distribution in the roll gap and thus also the Band contour. Behind the last rolling stand (8) are to permanent determination of the strip contour thickness, flatness and Temperature measuring devices (19, 20, 21) arranged.

Both the measuring devices (19 - 21) and (25, 26), as well Signaling devices of the mechanical actuators (12, 13) as well as the thermal and other influencing elements (14 - 18) are connected to a strip contour and flatness calculator (22) connected. The measured data determined, in particular for Profile and flatness or flatness of the tape (3, 4) can therefore immediately to correct the upstream Control systems or actuators are used with the Aim, the actual flatness shape of the rolled strip to compare with the values of the given target unevenness, to calculate a difference from it and the available standing mechanically or physically effective actuators in such a way that the differences are as possible be largely minimized, as is the teaching of the invention prescribes. For optimal starting conditions for the profile and To get a flatness calculation, the incoming belt contour with the profile measuring device (25), as well as the incoming flatness form with the flatness measuring device (26) detected. A pass schedule calculator (23) supplies the belt contour and Flatness calculator (22) with input data. A data return (24) is for the purpose of the desired rolling force redistribution set up.

The procedure for determining the belt contour or belt extension (delta L / L) _i (B) and thus the belt tension distribution σ _i (B) over the width (B) is shown in FIGS. 2.1 to 2.5. The process steps with which a predetermined target flatness or target band extension is generated across the width are shown in the flowchart in FIG. 12. In FIG. 2.1, the solid curve represents the incoming band contour y _a (B) and the dash-dotted curve shows the outgoing band contour y _from (B). Fig. 2.2 shows the difference between the incoming and outgoing band contour, Fig. 2.3 the band extension (B) with indication of the band edge area (a), the remaining curve indicating the so-called "band body area"; K is the running index over the bandwidth. The dashed curves show the shape of the positive and negative flatness limits across the bandwidth. 2.4 shows the division of the band extension and its limits into a parabolic component and in FIG. 2.5 into a component of a higher order.

Figure 3.1 shows a diagram of a rolling program according to the Width of the rolled strip. This includes one Width difference when rolling a total of approx. 185 coils between 1000 and 2000 mm in correspondingly graded Broad jumps. Figure 3.2 shows in addition to this within the same rolling program Rolled stock between 1,600 and 3,600 micrometers with the same Coilfolge. When rolling wide strips, for example after the Rolling program according to Fig. 3.1, 3.2 can with a short Sequence of beads. These are created with the help of Anti-bead rollers according to Figure 4 successfully pushed away.

The change in the band contour is seen by looking at the Figures 5.3 and 5.4 clearly. This contour change leads to Belt extensions, especially in the belt edge area, what for Scaffolds 3-6 of Figures 6.1 to 6.4 can be seen, with on the ordinate indicates the flatness of higher order and the number of coils on the abscissa. From Figures 5.4 and 6.2, especially in the area of coils 20 to 80, is the Band contour change clearly by using the anti-bead roller recognizable.

Furthermore, the wear of the work rolls and the thermal crown of the work rolls to undesirable Lead band extensions or band shortenings. Therefore must set limits for the limitation of the band extension or Flatness limits - also of higher order - are introduced. The introduction of such flatness limits goes z. B. from the Figures 7.1 to 7.4 for the framework F3 to F6 (dash-dotted lines). The set Sliding positions of the stands F1 to F6 from CVC, anti-bulge conventional rollers for the purpose of strip contour and Figures 8.1 to 8.6 show band flatness optimization. For the outlet scaffold of Figure 7.4 were negative Higher-order target unevenness for the strip edge specified. As shown in diagram 7.4 in particular thereby higher order waves, e.g. B. corner waves on the Belt edge, in both warm and cold belt condition successfully fought.

Another actuator for the application of contour control is shown in Figure 9. It is in the form of a Tapered roller recognizable, with the abscissa the axial length, and the ordinate shows the diameter difference.

The effect of the tapered roller on the belt contour and the Flatness form or form of the band extension are from the Figures 10.1 to 10.4 recognizable. In the example of Fig. 10.1 the desired belt contour could be created, it is however impermissibly short band fibers in the edge area the consequence according to Fig. 10.2. The danger of tearing the tape due to excessive tensile stress on the edge is very large. To avoid this problem, flatness limits were increased Order introduced.

According to Figure 10.3, the desired band contour is not so flat because the flatness shape created according to Fig. 10.4 was kept within the permissible limits. at Optimization of the sliding position for the purpose of Higher order flatness improvement is e.g. B. the bend used to ensure body flatness.

To make the target flatness of higher order expedient Flatness boundary lines. These serve the expected the strip edges when cooling the strip / coil counteract or a safe belt transport in the Ensure road.

There are corner waves in the street. In many cases this is due to excessive rolling force, for example according to FIGS. 11.1 to 11.3 on the framework F6.

The rolling force level is often not from stand to stand falling, but remains constant or even increases according to FIG. 11.1 something at F6. This leads especially to thin ones Tapes to long tape edges, as shown in Figure 11.3.

The target flatness shape (Delta L / L) _target as well as the flatness limits ((Delta L / L) _lim are also shown in Figure 11. If this process takes place in a hot mill, where the strip edges are naturally somewhat colder, the situation worsens During the cooling process of the hot strip in the coil, a redistribution of the rolling force, for example by reducing the rolling force at F6 and increasing at F4 / F5 according to FIGS. 11.4 to 11.6, improves the situation.

A related change in body unplannedness can be caused by the actuators work roll bending or CVC rolls be balanced. By analyzing the processes at Cooling process of the hot strip on the outfeed roller table and in the The target strip extensions for the hot strip can be coiled determine across the width in order to then close the cold strip flatness improve. The procedure for this is in the flow chart shown in FIG. 13.

The integration of the rolling force redistribution in the The overall iteration scheme is shown in FIG. 12.

Claims (18)

1. Method of hot-rolling a rolled strip (3, 4) in a hot rolling train (6) with at least two roll stands (7, 8) with horizontally adjustable upper and lower working rolls (10, 11), which act alone or of which each is supported at a backing roll (9) directly or by way of an intermediate roll, or in a reversing stand at which at least two passes are rolled, in which or at which the rolled strip (3, 4) is subjected to a change in state, characterised in that for attainment of an optimal presetting at least at a strip region on the one hand a target non-planarity shape, which is determined in dependence on the purpose of use as well as on the proceedings in the cooling down of the hot strip (3, 4) on the outlet roller path and in the coil, is preset over the body region and edge region of the strip and on the other hand a non-planarity shape actually achieved there is ascertained and compared with the preset non-planarity shape, a difference is calculated therefrom and available mechanically or physically effective setting elements (12, 13, 14, 15, 16, 17, 18) are used in such a manner that the difference is minimised as far as possible, wherein the envisaged hot strip non-planarity shape leads to the desired cold strip planarity after cooling down of the strip (3, 4).
2. Method according to claim 1, characterised in that in addition to presetting a target non-planarity shape a profile of the target stress distributions or the target elongations of the strip (3, 4) over the width are preset and compared with the actually achieved stress distributions or elongations, the thereby resulting differences are calculated and the setting elements (12, 13, 14, 15, 16, 17, 18) are used in the manner that the differences are minimised.
3. Method according to claim 1, characterised in that for producing a strip (3, 4) which is planar in the cold state, different non-planarity shapes are predetermined for the hot strip (3, 4) over the strip length.
4. Method according to one or more of claims 1 to 3, characterised in that in the case of insufficient minimisation of the difference, the starting conditions, i.e. the characteristics of the entering strip (3, 4) such as strip profile, planarity shape or strip temperature distribution, of the relevant stand are changed and the result optimised.
5. Method according to claim 1, characterised in that for producing different strip non-planarity shapes at least the working roll bending (13), the PC stand setting angle and the CVC displacement (12) are set to be constant or variable over the strip length.
6. Method according to one or more of claims 1 to 5, characterised in that the description of the target values, non-planarity shapes and the mathematical evaluation by division of the strip width into a body region and into an edge region is undertaken.
7. Method according to one of claims 1 and 6, characterised in that the non-planarity shape is described by a polynomial function y* = A₂x² + A₄x⁴ + A₆x⁶ + A_nxⁿ, wherein y* represents the co-ordinates for the strip elongation, strip non-planarity or strip stress and x represents the strip width co-ordinates.
8. Method according to one or more of claims 1 to 7, characterised in that the non-planarity shape is alternatively described as a point sequence (x, y).
9. Method according to one or more of claims 1 and 6, characterised in that the target value for the non-planarity shape is described by a polynomial function according to claim 7 or as a point sequence (x-y) according to claim 8.
10. Method according to one or more of claims 1 to 9, characterised in that positive and negative limits (for example, the strip stress, planarity, strip elongation / strip shortening) are defined around the target values and the setting elements (12, 13, 14, 15, 16, 17, 18) are used in such a manner that the strip stress distribution, planarity distribution, distribution of strip elongation / shortening lie within the limits or an exceeding of the limits is minimised.
11. Method according to one or more of claims 1 to 10, characterised in that the limits for the permissible non-planarity shape are described by a polynomial function according to claim 7 or as a point sequence (x, y) according to claim 8.
12. Method according to one or more of claims 1 to 11, characterised in that the target non-planarity shapes as well as the planarity limits can be inferred by way of the width of a strip (3, 4) for the different stands or passes of different shapes and levels.
13. Method according to one or more of claims 1 to 12, characterised in that for producing a strip elongation / shortening of parabolic or superordinate form over the strip width, setting elements (12, 13) are used which influence the elastic behaviour of the roll set, wherein these setting elements comprise axial displacing means (12) for the working rolls (10, 11) or bending devices (13) for these or both of these means at the same time.
14. Method according to one or more of claims 1 to 13, characterised in that for the avoidance of distortion waves at the hot strip (3, 4) as well as in the cold state of the strip (3, 4) a distribution of the rolling force is undertaken in the sense that the rolling force is reduced at least in the last stand (8) and the rolling force of stands disposed upstream is increased.
15. Method according to one or more of claims 1 to 14, characterised in that the proceedings in the cooling down of the rolled strip (3, 4) on the outlet roller path as well as in the coil and the strip elongation / shortenings thereby taking place are analysed not only in the body region, but also in the region of the strip edges and the length changes in that case ascertained or calculated are compensated for by appropriate presetting of the setting elements (12, 13, 14, 15, 16, 17, 18) at least in the last stand (8).
16. Method according to one or more of claims 1 to 15, characterised in that mechanically acting setting elements (12, 13) are used and are assisted by nonmechanical, for example positive or negative, thermal setting elements (14, 15, 16, 17, 18).
17. Method according to one or more of claims 1 to 16, characterised in that the measured non-planarity shape is compared with the target planarity shape and the difference is utilised for adaptation purposes.
18. Method according to one or more of claims 1 to 17, characterised in that the difference between the calculated or measured non-planarity shape and the target planarity shape is analysed and is divided into parabolic components as well as into components of higher order, and that setting elements (12, 13, 14, 15, 16, 17, 18) are thereafter used in correspondence with their effect.

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