EP0972581A2 - Rolling method for bar-shaped rolling stock, in particular steel bars and wire - Google Patents

Abstract

The actual rolling force and the resultant roll gap increase are determined. A roll gap correction is determined on the basis of this roll gap increase and a target roll gap in such a way that the actual roll gap approximates the target roll gap. The roll gap correction is implemented within a roll stand control interval.

Description

The present invention relates to a rolling process for rod-shaped rolling stock, in particular steel bars or wire, in one Roll stand with two relative to each other in one direction of attack adjustable work rolls, which together a rolling caliber with a Form the actual roll gap so that the rolling stock comes out of the roll stand an actual height and an actual width with a rolling speed runs out, the rolling stock being rolled with an actual rolling force.

Such rolling processes are known. For example, you work on the Basis of a so-called monitor regulation. There are deviations detected in the height and width of the rod-shaped rolling stock and on the basis of an electromechanical or hydromechanical position corrected. Such systems have the disadvantage that both Monitor control itself as well as the employment act very slowly. In addition, there is the time delay due to the measurement behind the last regulated scaffolding. As a result, there is a response time of about 3 seconds, so that only faults with a low Frequency can be adjusted. Short-term disturbances, e.g. through so-called Skidmarks are not fixable, which may result Tolerance violations leads. The same problem arises in the event of malfunctions that occur at the beginning or end of the rolling stock Temperature and thickness fluctuations are caused.

The object of the present invention is a rolling method for rod-shaped rolling stock, which is considerable works faster and with it also short-term disruptions can be adjusted.

• daß die Arbeitswalzen über eine Hydraulikzylindereinheit anstellbar sind,
• daß die Ist-Walzkraft erfaßt wird,
• daß anhand der Ist-Walzkraft eine walzkraftbedingte Walzspaltauffederung bestimmt wird,
• daß anhand der walzkraftbedingten Walzspaltauffederung und einem Soll-Walzspalt ein Walzenanstellungs-Korrekturwert derart bestimmt wird, daß der Ist-Walzspalt dem Soll-Walzspalt angenähert wird, und
• daß eine Walzenanstellung innerhalb einer Gerüstregelzeit um den Walzenanstellungs-Korrekturwert geändert wird.

The task is solved by

• that the work rolls can be adjusted via a hydraulic cylinder unit,
• that the actual rolling force is detected,
• that a roll gap-dependent suspension is determined on the basis of the actual rolling force,
• that a roll pitch correction value is determined on the basis of the roll-force-dependent roll gap suspension and a target roll gap such that the actual roll gap is approximated to the target roll gap, and
• that a roll pitch is changed within a stand control time by the roll pitch correction value.

Such methods have been used for rolling strips for years known. They are sophisticated. You care regardless of the Rolling force for an actual roll gap corresponding to the target roll gap. However, the methods were used for rolling rod-shaped rolling stock considered not applicable. The reason for this is that when rolling from the strip the width of the rolling stock is constant from the start. At Bar-shaped rolling stock, on the other hand, is also automatically rolled the width of the rolling stock changed. A simple transfer of the processes known for rolling strip would have been inadmissible Width tolerances result. In contrast, in the present invention the method is used to determine the difference between one superordinate control methods determined target roll gap and one To minimize the actual roll gap as quickly as possible. This will make the Application of the known thickness regulations for steel bars and Wire lines allowed.

When the rolling stock is in the rolling stand with a substantially constant Train arrives, there is an even greater latitude and Constant height of the rod-shaped rolling stock.

To keep the train constant, it is provided that the rolling stock in front the rolling stand is subjected to tension control. The train regulation can be designed in particular as a minimum draft control.

The train control can, for. B. can be realized in that the Rolled stock is subjected to loop control in front of the roll stand.

According to the invention it is provided that the difference between the actual roll gap and the target roll gap by the roll pitch correction value is partially compensated. Because thereby Cross-sectional fluctuations of the incoming rolling stock more evenly to the actual height and the actual width of the rolling stock being discharged distributed. The part is preferably dependent on the rolling force and / or frequency.

• die Arbeitswalzen des Walzgerüsts mit einer Betriebsdrehzahl rotieren,
• die Ist-Walzkraft gemäß dem Abtast-Theorem mindestens zweimal pro Umdrehung der Arbeitswalzen des Walzgerüsts erfaßt wird,
• der Walzenanstellungs-Korrekturwert dem Walzgerüst als Summe von Frequenzkomponenten zugeführt wird,
• die mit der Betriebsdrehzahl korrespondierende Frequenzkomponente dem Walzgerüst nach einer Filterzeit zugeführt wird und
• die Arbeitswalzen des Walzgerüsts während der Summe von Gerüstregelzeit und Filterzeit in etwa ein ungeradzahliges Vielfaches einer halben Umdrehung zurücklegen.

The regular effort is minimized, if

• the work rolls of the roll stand rotate at an operating speed,
• the actual rolling force is recorded at least twice per revolution of the work rolls of the roll stand in accordance with the scanning theorem,
• the roll pitch correction value is fed to the roll stand as the sum of frequency components,
• the frequency component corresponding to the operating speed is fed to the roll stand after a filter time and
• cover the work rolls of the roll stand roughly an odd multiple of half a turn during the sum of the stand control time and filter time.

Rod-shaped rolling stock is rolled in multi-stand rolling mills. The invention therefore also relates in particular to a rolling process, in which a rod-shaped rolling stock, in particular bar steel or wire, first passes through a front and then a rear roll stand, with both the front and the rear roll stand with one the rolling process described above are operated and wherein the directions of adjustment of the work rolls of the roll stands vertically stand on each other.

• daß die Ist-Höhe und die Ist-Breite des Walzguts an einer Erfassungsstelle hinter dem hinteren Walzgerüst erfaßt werden und
• daß aus der Ist-Höhe und der Ist-Breite aus einem Walzplan die Soll-Walzspalte für die Walzgerüste derart bestimmt werden, daß die Differenz zwischen der Ist-Höhe und einer Soll-Höhe und die Differenz zwischen der Ist-Breite und einer Soll-Breite gegen Null gehen.

The rolling process can be improved

• that the actual height and the actual width of the rolling stock are recorded at a detection point behind the rear rolling stand and
• that the target roll gaps for the roll stands are determined from the actual height and the actual width from a rolling plan in such a way that the difference between the actual height and a target height and the difference between the actual width and a target Width go to zero.

The actual height and the actual width should preferably be at the same time be recorded.

The rolling process works even more precisely when the target roll gap are fed to the rolling stands with a delay, the waiting time by the quotient between one between the rear and the front rolling mill length and the rolling speed of the front roll stand is determined.

The control dynamics of the above rolling process is characterized by the between the front roll stand and the detection point for the actual height and the actual width of the rolling stock length is limited. The control dynamics can therefore be improved by the fact that for the rear roll stand determines an additional target roll gap in this way is that the ratio of the relative errors in height and the Width remains as constant as possible, with the relative error in the Height by the difference between the actual height and the target height, divided by the target height, and the relative error in width by the Difference between actual width and target width divided by the target width, given is.

When determining the target roll gaps for the roll stands the influence of the additional target roll gap, of course the actual height and the actual width of the rolling stock are taken into account.

As long as the rolling stock has not yet passed the registration point, the control loop for determining the target roll gap is not closed. Preferably, therefore, during the rolling of rolling stock from the actual height, the target height, the actual width and the target width Preliminary settings for the roll stands determined. With these preconceptions A subsequent rolling stock can then be rolled as control values until the tip of the subsequent rolling stock reaches the detection point runs through and thus closes the control loop. The roll stands can still use the pre-settings after closing the control loop be applied as input tax values.

The dynamics and the control accuracy of the roll stands is in given in full only if the roll settings of the Roll stands are within a specified range of employment move. It is therefore preferred to use the roller positions Roll stands for at least one upstream of the front roll stand Roll stand determined a target roll gap. This can ensure be that the roll positions of the two roll stands move within the cheapest employment range.

Figur 1

einen Teil einer mehrgerüstigen Drahtwalzstraße,

Figur 2

ein Vertikalgerüst,

Figur 3

ein Kraft-Walzspaltdiagramm und

Figur 4

ein Horizontalgerüst.

Further advantages and details emerge from the following description of an exemplary embodiment. In principle, the following show:

Figure 1

part of a multi-stand wire rolling mill,

Figure 2

a vertical scaffold,

Figure 3

a force roll gap diagram and

Figure 4

a horizontal scaffold.

A rolling mill for rod-shaped rolling stock, e.g. B. bar steel or wire, usually consists of a variety of roll stands. In Fig. 1 four of these roll stands are shown and provided with the reference numerals 1-4. A rod-shaped rolling stock 5, according to the exemplary embodiment material 5 for wire, made of steel passes in a transport direction z firstly through the rolling stand 4, then the rolling stand 3, then the rolling stand 2 and finally the rolling stand 1. Behind the rolling stand 1 there is a detection point 6 Thickness measuring device 7 arranged. Between the rolling stand 1 and the detection point 6 and the roll stand 2 are Walzgutlängen l _0, l ₁ of the rolling stock. 5

Roll stands 1 and 3 are vertical stands. With them are theirs two work rolls 8 arranged vertically. The work rolls 8 are can thus be adjusted relative to one another in an adjustment direction x. The The direction of attack x is horizontal. Roll stands 2 and 4 however, are horizontal scaffolds. With them are their two work rolls 8 adjustable in an adjustment direction y, which is vertical runs.

The directions of inclination x, y form together with the direction of transport z of the rolling stock 5 is a right-handed, right-angled coordinate system (x, y, z).

The rolling stock 5 runs into the roll stand 4 at a rolling speed v ₄ , it having a dimension x ₄ in the x direction and y ₄ in the y direction before rolling in the roll stand 4.

The rolling stock 5 is rolled in the roll stand 4, the work rolls 8 of the roll stand ₄ rotating at an operating speed n ₄ . After rolling, the rolling stock 5 runs out of the roll stand 4 at a rolling speed v ₃ . At this point in time, the rolling stock 5 has dimensions x ₃ and y ₃ in the x direction and y direction, respectively. With these values, it enters the mill stand 3.

In an analogous manner, the rolling stock between the roll stands 3 and 2 has a rolling speed v ₂ and dimensions x ₂ , y ₂ in the x direction and y direction. Likewise, the rolling stock 5 between the roll stands 2 and 1 has a rolling speed v ₁ and dimensions x ₁ , y ₁ . The rolling stock then runs out of the roll stand 1 at a rolling speed v ₀ and dimensions x ₀ , y ₀ .

As already mentioned, the roll stands 2 and 4 are horizontal stands. For them, the dimension y ₁ , y _{3 of} the rolling stock 5 running out in the y direction thus corresponds to the actual height. The dimension x ₁ , x _{3 of} the rolling stock 5 running out corresponds to the actual width. This is the reverse for roll stands 1 and 3. Here the dimension x ₀ , x ₂ corresponds to the actual height behind the respective mill stand 1 or 3, the dimension y ₀ , y ₂ corresponds to the actual width.

The two work rolls 8 of the roll stands 1-4 each form a roll caliber with an actual roll gap s ₁ to s ₄ . The actual roll gaps s ₁ to s ₄ can be set by a corresponding adjustment a ₁ to a _{4 of} the respective roll stand 1-4 to a corresponding target roll gap s ₁ * -s ₄ *. The work rolls 8 of the roll stands 1 and 2 can be adjusted relative to one another via hydraulic cylinder units 12. The roll stands 3 and 4 can also be adjusted via hydraulic cylinder units. As an alternative, it is also possible for the rolling stands 3 and 4 to be started using an electric or hydraulic motor with a downstream transmission.

When the beginning of the rolling stock 5 runs into the rolling stands 1-4, no actual values of the rolling stock 5 can yet be recorded in the detection point 6. The roll stands 1-4 are therefore first operated in controlled operation with target roll gaps s ₁ * -s ₄ *. As soon as the beginning of the rolling stock 5 passes through the detection point 6, the actual height is simultaneously measured via the thickness measuring device 7 H 0 = x 0 and the actual width b 0 = y 0 of the rolling stock 5 detected. The values h _0, b ₀ are reported to a rolling plan computer 9, which uses them to determine the desired roll gaps s ₁ *, s ₂ * for the roll stands 1 and 2 on the basis of a rolling plan. The calculation of the target values s ₁ *, s ₂ * naturally takes into account the coupling of changes in length, height and width in the roll stands 1 and 2. The target values s ₁ *, s ₂ * are determined in such a way that the difference between the actual values -Height h ₀ and a target height h ₀ * and the difference between the actual width b ₀ and a target width b ₀ * approach zero.

The rolling stock length l ₁ is located between the roll stands 1 and 2. A point of the rolling stock 5 that is rolled by the roll stand 2 at any point in time therefore requires a running time t = l 1 : v 1 to get to the mill stand 1. So that the determined target roll gaps s ₁ * and s ₂ * are applied to the same location of the rolling stock 5, the target roll gaps s ₁ *, s ₂ * must be fed to the roll stands 1, 2 with a delay, which is identical to is the running time t. The target roll gap s ₂ * is thus supplied to the roll stand 2 by the running time t sooner than the target roll gap s ₁ * to the roll stand 1.

The rolling stock 5 is rolled in the roll stands 1-4 with actual rolling forces F ₁ to F ₄ . Due to the actual rolling forces F ₁ to F _4, the actual roll gaps s ₁ - s _{4 of} the roll stands 1-4 spring open. The actual roll gaps s ₁ to s ₄ thus result from the sum of a position a ₄ to a _{1 of} the respective roll stand 1-4 and the respective stand suspension C ₁ F ₁ to C ₄ F ₄ . C ₁ to C ₄ are the spring constants of the roll stands 1-4.

In order to keep the actual roll gap s _{1 of} the roll stand 1 at its desired roll gap s ₁ *, the actual rolling force F _{1 is} detected according to FIG. 2 and fed to a frequency filter 10. The frequency filter 10 filters the rolling force F ₁ and forwards the filtered value to a stand regulator 11. The frame controller 11 determines in accordance with FIG. 3 on the basis of the filtered actual roll force F ₁ a rolling force caused Walzspaltauffederung .DELTA.S _1. Based on these rolling force caused Walzspaltauffederung .DELTA.S ₁ and the desired roll gap s ₁ * determines the frame controller 11 then a roll adjustment correction value .DELTA.a ₁ for the roll adjustment a _1, so that the actual roll gap s ₁ the desired roll gap s ₁ * is approached. The stand controller 11 then outputs the sum of the previous set position a ₁ * and the roll position correction value δa ₁ as the new set position a ₁ 'to hydraulic cylinder units 12, by means of which the roll position a _{1 is changed} by the roll position correction value δa ₁ . The roll adjustment a ₁ is changed within a stand control time T of approx. 30 ms. After the stand control time T, the actual roll gap s ₁ is then set again to the desired roll gap s ₁ *, so that the rolling stock 5 runs out of the roll stand 1 again with the desired height h ₀ * and the desired width b *.

Height h ₀ and width b _{0 of} the rolling stock 5 depend not only on the rolling force F ₁ and the position a _{1 of} the rolling stand 1, but also on the train with which the rolling stock 5 enters or leaves the rolling stand 1 1 expires. In order to rule out train fluctuations, which would result in fluctuations in height and width, the rolling stock 5 is subjected to a train control in front of the roll stand 1. The tension control is preferably designed as a minimum tension control. It can be implemented, for example, by means of a loop control. By means of the tension control it is achieved that the rolling stock 5 enters the rolling stand 1 with an essentially constant tension.

The maximum allowable train fluctuations are 5 MPa. Even better it is when the train fluctuations are limited to 2 MPa.

With the method described above, the actual roll gap s _{1 can} always be kept at its desired roll gap s ₁ * when the roll gap control is fully reached. The rolling force F ₁ is also dependent, among other things, on the temperature and the cross section of the incoming rolling stock. If the stand controller 11 would always regulate the actual roll gap s ₁ to its target roll gap s ₁ *, the actual height h ₀ would always be equal to the target height h ₀ *. The actual width b ₀ would fluctuate greatly. It is therefore generally more favorable if the difference between the actual roll gap s ₁ and the target roll gap s ₁ * is only partially compensated by the stand controller 11 by means of the roll pitch correction value δa ₁ . The part is usually between 20 and 90 percent of the full correction. In particular, it can be dependent on the rolling force and frequency. With such a partial correction, the rolling error is distributed more evenly over both dimensions h ₀ , b ₀ .

The rolling speed v ₄ to v ₀ increases continuously from the roll stand 4 to the roll stand 1. In contrast, the diameters of the work rolls 8 either remain the same or decrease from the roll stand 4 to the roll stand 1. As a result, the work rolls 8 of the roll stand 1 rotate fastest. Periodic errors caused by any eccentricities of the work rolls 8 can therefore have a maximum of a frequency which corresponds to the speed n _{1 of} the roll stand 1. According to the scanning theorem, the actual rolling force F _{1 of} the roll stand 1 is therefore recorded at least twice per revolution of the work rolls 8 of the roll stand 1. The roll adjustment correction value δa ₁ is frequency-filtered in accordance with the known frequencies corresponding to the speeds n ₁ to n ₄ in the stand controller 11. Only the frequency-filtered roll adjustment correction value δa ₁ is then fed to the roll stand 1.

The regulation of the eccentricities is particularly effective when the roll adjustment correction value δa _{1 is} fed to the roll stand 1 as the sum of frequency components. The frequency component corresponding to the operating speed n ₁ of the roll stand 1 is fed to the roll stand 1 after a filter time T '. If necessary, this frequency component can be weighted with its own gain factor between 0.15 and 10.0 relative to the other frequency components. The filter time T 'is selected such that the work rolls 8 of the roll stand 1 during the sum of the stand control time T and filter time T' between 0.4 and 0.55 revolutions, that is to say approximately half a revolution, plus any number of complete revolutions if necessary , return.

The roll stand 2 is regulated in the same way according to FIG. 4 like the rolling stand 1.

The rolling stock length l ₁ is located between the roll stands 1 and 2. The rolling stock length l ₀ is located between the roll stand 1 and the detection point 6. The dynamic range of the monitor control is therefore limited by the sum of l ₁ : v ₁ + l ₀ : v ₀ . Faster faults cannot be corrected using the method described above.

If, on the other hand, only the roll stand 1 were controlled, the maximum control dynamics of the monitor control would be given by l ₀ : v ₀ . The control dynamics would be higher. This can be exploited in that an additional target roll gap δs * is determined for the roll stand 1. This value is determined in such a way that the ratio of the relative errors δh, δb in the height and the width of the rolling stock 5 remains as constant as possible, in any case within a preselectable barrier. The relative error δh in height is given by the difference between the actual height h ₀ and the target height h ₀ *, divided by the target height h ₀ *. The relative error δb in the width is given in an analogous manner by the difference between the actual width b ₀ and the target width b ₀ *, divided by the target width b ₀ *. The influence of the additional target roll gap δs ₁ * on the actual height h ₀ and the actual width b ₀ must of course be taken into account when determining the target roll gaps s ₁ *, s ₂ * for the roll stands 1 and 2.

The method described above for setting the desired roll gaps s ₁ *, s ₂ * can of course only be carried out if the beginning of the rolling stock 5 has already reached or passed the detection point 6, that is to say the monitor control is closed. The control loop is open before this point. The roll stands 1, 2 must therefore be operated in controlled mode during this period. From measurements of the actual height h ₀ , the actual width b ₀ and the corresponding target values h ₀ *, b ₀ *, 9 target rolling gaps s ₁ *, s ₂ * can be determined using a rolling model in the rolling schedule computer which the desired actual values h ₀ , b ₀ can be expected. The roll stands 1, 2 are then operated with these values for the target roll gaps s ₁ *, s ₂ * as long as the control loop of the monitor control is open.

The roll stands 1, 2 can only be optimally operated within a predetermined range of employment. In order to always ensure that the actual positions a ₁ , a _{2 of} the roll stands 1, 2 move within this range, the actual positions a ₁ , a ₂ of the roll stands 1, 2 are transmitted to the rolling plan computer 9. As soon as the actual positions a ₁ , a ₂ reach the limits of their permissible ranges, the desired roll gaps s ₃ *, s ₄ * of the roll stands 3, 4 are changed such that the actual positions a _1, a _{2 of} the roll stands 1, 2 are shifted back into the middle of their permissible dynamic range. Thus, from the roll positions a ₁ , a _{2 of} the roll stands 1, 2 for the upstream roll stands 3, 4, new desired roll gaps s ₃ *, s ₄ * are determined.

With the rolling method according to the invention, wire and Bar steel lines achieve unprecedented levels of accuracy. In particular can the ovality of the rolling stock 5 at the exit of the rolling mill reduced to a quarter of the value permitted by ASTM-A29 become.

Reference list

1-4

Mill stands

5

Rolling stock

6

Registration office

7

Thickness gauge

8th

Work rolls

9

Rolling plan calculator

10th

Frequency filter

11

Scaffolding regulator

12th

Hydraulic cylinder units

a ₁ -a ₄

Actual jobs

a ₁ * -a ₄ *, a ₁

'Target employment

b ₀ , b ₀ *

Widths

C ₁ -C ₄

Spring constants

F ₁ -F ₄

Rolling forces

h ₀ , h ₀ *

Heights

l ₀ , l ₁

Rolled lengths

n ₁ -n ₄

Speeds

s ₁ -s ₄

Actual nip

s ₁ * -s ₄ *

Target roll gap

t, T, T '

Times

v ₀ -v ₄

Rolling speeds

x ₀ -x ₄ ,

y ₀ -y ₄

Dimensions

x, y

Directions of attack

e.g.

Direction of transport

δa ₁

Roll setting correction value

δb, δh

relative errors

δs ₁

Roll gap suspension

δs ₁ *

Additional nominal roll gap

Claims (15)

Rolling process for rod-shaped rolling stock (5), in particular bar steel or wire (5), in a roll stand (1) with two work rolls (8) which can be adjusted relative to one another in a setting direction (x) by means of a hydraulic cylinder unit (12), which together is a rolling caliber with an actual Form rolling gap (s ₁ ) so that the rolling stock (5) runs out of the rolling stand (1) with an actual height (h ₀ ) and an actual width (b ₀ ) at a rolling speed (v ₀ ), the rolling stock (5) being rolled with an actual rolling force (F ₁₎ , the actual rolling force (F _{1) being} detected, where a roll gap suspension (δs ₁ ) is determined on the basis of the actual rolling force (F ₁ ), wherein on the basis of the rolling force caused Walzspaltauffederung (.DELTA.S ₁₎ and a desired roll gap (s ₁ *), a roll adjustment correction value (.DELTA.a ₁₎ is determined such that the actual roll gap approximated (s ₁₎ the desired roll gap (s ₁ *) will, and wherein a roll pitch (a ₁ ) is changed within a stand control time (T) by the roll pitch correction value (δa ₁ ). Rolling method according to claim 1,
characterized,
that the rolling stock (5) enters the rolling stand (1) with an essentially constant train. Rolling method according to claim 2,
characterized,
that the rolling stock (5) in front of the rolling stand (1) is subjected to tension control. Rolling method according to claim 3,
characterized,
that the draft control is designed as a minimum draft control. Rolling method according to claim 3 or 4,
characterized,
that the rolling stock (5) in front of the rolling stand (1) is subjected to loop control. Rolling method according to one of the above claims,
characterized,
that the difference between the actual roll gap (s ₁ ) and the target roll gap (s ₁ *) is partially compensated for by the roll pitch correction value (δa ₁ ). Rolling method according to claim 6,
characterized,
that the part is dependent on the rolling force and / or frequency. Rolling method according to one of the above claims,
characterized, that the work rolls (8) of the roll stand ( ₁ ) rotate at an operating speed (n ₁ ), that the actual rolling force (F ₁ ) is recorded at least twice per revolution of the work rolls (8) of the roll stand (1), that the roll pitch correction value (δa ₁ ) is fed to the roll stand (1) as a sum of frequency components, that the frequency component corresponding to the operating speed (n ₁ ) is fed to the roll stand (1) after a filter time (T ') and that the work rolls (8) of the roll stand (1) cover an odd multiple of half a turn during the sum of the stand control time (T) and filter time (T '). Rolling process in which a rod-shaped rolling stock (5), in particular bar steel or wire (5), first passes through a front and then a rear rolling stand (2, 1),
characterized,
that both the front and the rear roll stand (2, 1) are operated with a rolling process according to one of the above claims and that the directions of adjustment (y, x) of the work rolls (8) of the roll stands (2, 1) are perpendicular to each other. Rolling method according to claim 9,
characterized,
that the actual height (h ₀ ) and the actual width (b ₀ ) of the rolling stock (5) are detected at a detection point (6) behind the rear rolling stand (1) and that from the actual height (h ₀ ) and the actual width (b ₀ ) from a rolling plan, the target roll gaps s ₁ *, (s ₂ *) for the roll stands (1, 2) are determined such that the difference between the actual height (h ₀ ) and a target height (h ₀ *) and the difference between the actual width (b ₀ ) and a target width (b ₀ *) approach zero. Rolling method according to claim 10,
characterized,
that the actual height (h ₀ ) and the actual width (b ₀ ) are recorded simultaneously. Rolling method according to claim 10 or 11,
characterized,
that the desired roll gaps (s ₁ *, s ₂ *) are fed to the roll stands (1, 2) with a delay (t), the waiting time (t) being determined by the quotient between a between the rear and the front roll stand ( 2, 1) located rolling stock length (l ₁ ) and the rolling speed (v ₁ ) of the front roll stand (2) is determined. Rolling method according to claim 12,
characterized,
that an additional target roll gap (δs ₁ *) is determined for the rear roll stand (1) in such a way that the ratio of the relative errors (δh, δb) in height and width remains as constant as possible, the relative error (δh ) in height by the difference between the actual height (h ₀ ) and target height (h ₀ *), divided by the target height (h ₀ *), and the relative error (δb) in width by the difference of actual width (b ₀ ) and target width (b ₀ *) divided by the target width (b ₀ *). Rolling method according to one of claims 10 to 13,
characterized,
that from the actual height (h ₀ ), the target height (h ₀ *), the actual width (b ₀ ) and the target width (b ₀ *) target roll gaps (s ₁ *, s ₂ * ) for the roll stands (1, 2) in controlled operation. Rolling method according to one of claims 10 to 14,
characterized,
that a desired roll gap (s ₃ *, s ₄ *) is determined from the roll positions (a ₁ , a ₂ ) of the roll stands (1, 2) for at least one roll stand (3, 4) upstream of the front roll stand (2).

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