EP3544751B1 - Strip position control with force-limited placement of lateral guiding devices on the metal strip - Google Patents

Description

Title of the invention

Strip position control with force-limited adjustment of side guides to the metal strip and correction of the roller adjustment

Field of technology

• wobei die Walzstraße mindestens ein vorderes Walzgerüst und ein dem vorderen Walzgerüst nachgeordnetes hinteres Walzgerüst aufweist und weiterhin zwischen den beiden Walzgerüsten Seitenführungen für das Metallband aufweist,
• wobei die Seitenführungen kraftbegrenzt betrieben werden,
• wobei während des Zeitraums zwischen dem Auslaufen des Bandkopfes aus dem vorderen Walzgerüst und dem Einlaufen des Bandkopfes in das hintere Walzgerüst mittels der Seitenführungen eine Abweichung der seitlichen Lage des Bandkopfes von einer Solllage quantitativ erfasst wird,
• wobei mittels eines Bandlagereglers ein Stellbefehl für das vordere Walzgerüst ermittelt wird,
• wobei das vordere Walzgerüst vom Bandlageregler entsprechend dem ermittelten Stellbefehl beaufschlagt wird.

The present invention is based on an operating method for a rolling train in which a metal strip is rolled,

• wherein the rolling train has at least one front roll stand and a rear roll stand arranged downstream of the front roll stand and furthermore has lateral guides for the metal strip between the two roll stands,
• where the side guides are operated with limited force,
• during the period between the exit of the strip head from the front roll stand and the entry of the strip head into the rear roll stand, a deviation of the lateral position of the strip head from a target position is quantified by means of the side guides,
• whereby a control command for the front roll stand is determined by means of a strip position controller,
• whereby the front roll stand is acted upon by the strip position controller in accordance with the determined control command.

The present invention is further based on a computer program that includes machine code that can be processed by a control device for a rolling train, the processing of the machine code by the control device causing the control device to operate the rolling train according to such an operating method.

The present invention is further based on a control device for a rolling train, the control device being programmed with such a computer program, so that the control device operates the rolling train according to such an operating method.

• wobei die Walzstraße mindestens ein vorderes Walzgerüst und ein dem vorderen Walzgerüst nachgeordnetes hinteres Walzgerüst aufweist und weiterhin zwischen den beiden Walzgerüsten Seitenführungen für das Metallband aufweist,
• wobei die Walzstraße eine derartige Steuereinrichtung aufweist, welche die Walzstraße gemäß einem derartigen Betriebsverfahren betreibt.

The present invention is further based on a rolling train for rolling a metal strip which has a strip head,

• wherein the rolling train has at least one front roll stand and a rear roll stand arranged downstream of the front roll stand and furthermore has lateral guides for the metal strip between the two roll stands,
• wherein the rolling train has such a control device which operates the rolling train according to such an operating method.

State of the art

Such an operating method, the corresponding computer program, the control device and the rolling train are for example from the WO 2006/119 984 A1 known.

From the WO 2006/119 984 A1 it is known to roll a slab in a roughing stand. Strong side guides are arranged both in front of and behind the roughing stand. By means of the arrangement of the WO 2006/119 984 A1 The aim is to specifically influence the geometry of a sliver in order to produce a straight sliver without a thickness wedge and without lateral curvature. The controls of the side guides and the roughing stand are linked in such a way that a saber-shaped or wedge-shaped slab is formed into a straight and wedge-free pre-strip. The side guides are held in place with great force and only give way if this is necessary to protect the side guides and / or the roughing stand from damage. The corresponding position of the side guides is recorded quantitatively. The roll gap in the roughing stand is regulated depending on different sizes so that it remains parallel.

From the DE 10 2004 043 790 A1 It is known to arrange side guides in front of and / or behind a roll stand and to detect the lateral position of the side guides and / or forces exerted on the side guides by the metal strip. Depending on the recorded values, the geometry of the roll gap is changed in order to avoid a saber and / or a wedge.

When rolling metal strip in a hot strip finishing train, the metal strip should, if possible, be guided through the individual roll stands of the rolling train with the greatest possible running stability and with an optimal flatness result. For this purpose, it is particularly desirable to guide the metal strip centrally and straight through the individual rolling stands of the rolling train. This also and especially applies in the threading phase of the metal strip, when the beginning of the metal strip (= strip head) has already emerged from one of the roll stands and is heading towards the next roll stand.

If an asymmetrical deformation occurs in the roll stand in the threading phase (i.e. if a thickness wedge is applied to the metal strip), the metal strip does not run straight, but in an arc (also called saber in professional circles) towards the next roll stand. The metal strip therefore arrives eccentrically at the downstream roll stand. This in turn results in an asymmetrical reduction in the downstream roll stand. The metal strip can therefore also run out of the downstream roll stand with a saber. The saber can point in the same direction as before or in the opposite direction.

Lateral guides are provided to limit the lateral migration of the metal strip. The lateral guides are operated in a position-controlled manner in the prior art. If the lateral position of the metal strip deviates only slightly from the target position, the metal strip does not contact the side guides. Otherwise, the sideways migration is caused by one-sided grinding on one of the two side guides limited or takes place in a snake shape within the two side guides. One-sided sanding damages the belt edges. Because of the uncontrolled lateral movement of the strip, a snake-like wandering leads to an off-center piercing in the downstream roll stand and thus to flatness errors. In the extreme case, the strip head can completely miss the roll gap of the following roll stand or enter the roll gap of the following roll stand twice. This applies in particular to the rear roll stands of a multi-stand finishing train, when the metal strip is already relatively thin. Both doubling the strip head and missing the roll gap lead to negative results. In extreme cases it is possible that the metal strip can only be recycled as scrap or that the rolling train is even damaged.

In the prior art, the side guides are usually set tightly in order to leave the metal strip only a small amount of lateral movement. This also has the consequence that the tape edges are ground off by the side guides and that the tape is tensioned in itself.

In practice, control people try to influence the straight running of the strip head on sight by quickly correcting the inclination of the work rolls. This job is very demanding and requires a lot of experience. In addition, even experienced helmsmen often only manage to do this to a limited extent, as the view from the control platform onto the metal strip is from an unfavorable angle. Steam and dust also often impair visibility. Furthermore, only sections of the metal strip between the roll stands are visible. In addition, because of the high transport speeds, a very fast response is required at the rear rolling stands of the rolling train.

From the DE 10 2014 215 397 A1 an operating method for a rolling train is known in which a metal strip is rolled, which has a tape head. The rolling train has a front and a rear roll stand, between which side guides for the metal strip are arranged. In the DE 10 2014 215 397 A1 the lateral position of the strip head is detected by means of an optical detection device and used to track the adjustment of the upstream roll stand. This approach gives good results. However, it is disadvantageous that the optical detection device is required.

Summary of the invention

The object of the present invention is to create ways of being able to adjust the tape position quickly, easily and reliably. In particular, the presence of an independent detection device for the deviation of the lateral position of the metal strip from the target position should not be necessary. Furthermore, the risk of tape doublers should be reduced or avoided.

The object is achieved by an operating method for a rolling train with the features of claim 1. Advantageous refinements of the operating method are the subject matter of dependent claims 2 to 10.

• dass der Bandlageregler den Stellbefehl unter Verwertung der zeitlichen Ableitung der Abweichung der seitlichen Lage des Bandkopfes von der Solllage derart ermittelt, dass einer Änderung der Abweichung der seitlichen Lage des Bandkopfes von der Solllage entgegengewirkt wird.

According to the invention, an operating method of the type mentioned is designed in that

• that the tape position controller determines the setting command using the time derivative of the deviation of the lateral position of the tape head from the target position in such a way that a change in the deviation of the lateral position of the tape head from the target position is counteracted.

As a result of the force limitation - in contrast to the position-controlled operation of the prior art - it is achieved that when the metal strip hits the side guide, the corresponding side guide yields. As a result, the forces exerted on the metal strip by the side guide are first limited. This reduces the risk of tape doublers. Due to the fact that the width of the metal strip is known and one side edge of the metal strip is in contact with the yielding lateral guide, the lateral position of the metal strip can also be determined quantitatively. Above all, however, the time derivative of the deviation of the lateral position of the tape head from the target position is used when determining the setting command, and the setting command is determined in such a way that a change in the deviation of the lateral position of the tape head from the target position - mind you, the change - is counteracted . In this way, it can be achieved that the metal strip runs out of the front roll stand as straight as possible by means of a finely metered counter control.

It is possible for the lateral guides to be set against the metal strip in a force-controlled manner via a respective force regulator and for a force setpoint effecting the force limitation to be specified for the respective force regulator. In this case, both side guides are always in contact with the metal band. This has the advantage that even slight deviations of the lateral position of the metal strip from the desired position can be easily detected.

In the case of force regulation, the force regulators are preferably only activated at a point in time at which the strip head has run out of the front roll stand by a predetermined length. This ensures that the tape head can reliably run into the area between the two side guides. In particular, this prevents the front edge of the belt extending in the direction of the width of the belt from hitting one of the side guides and thereby causing a high walker.

The force regulators can in particular determine a respective additional setpoint value for a respective subordinate position regulator, by means of which a position control of the respective lateral guidance takes place.

Alternatively, it is possible for the lateral guides to be moved to a respective reference position in a position-controlled manner via a respective position controller. In this case, the reference positions are preferably specified in such a way that, in the case of a central, completely straight transport, the metal strip has a respective distance from both side guides. In the case of position control, the position regulators each determine a force setpoint for a respective subordinate force regulator as the respective manipulated variable. The respective force setpoint is limited to a force limit value by means of a respective limiter. The limiters can be part of the respective position regulator or independent units arranged between the position regulators and the force regulators.

In the case of the subordinate or superimposed position control, there is a tolerance range within which the metal strip can migrate (usually slightly) without contacting the side guides. In this case, the belt edges are not damaged at all by the side guides if the metal belt runs straight in the middle.

The strip position controller preferably determines the control command in such a way that the change in the deviation is reduced as much as possible, in particular becomes zero. As a result, the metal strip runs out of the front roll stand as straight as possible - in the ideal case completely straight - from the point in time at which the change in the deviation is reduced as much as possible.

When determining the setting command, the strip position controller preferably takes into account a current length by which the strip head has run out of the front roll stand. This results in a linearization of the positioning action of the belt position controller.

Before the strip head enters the front roll stand, a setting is made using a model of the rolling train of the front roll stand determines to which the front roll stand is set from the entry of the strip head into the front roll stand. This setting is retained until the deviation of the lateral position of the tape head from the target position is detected by means of the side guides. The model is preferably adapted on the basis of the setting command determined by the strip position controller and, when a further metal strip is rolled, the setting of the front roll stand is determined on the basis of the adapted model. As a result, the model can be gradually improved, so that continuously improved settings can be determined for metal strips to be rolled in the future.

In an analogous manner, before the strip head enters the rear roll stand, a model of the rolling train can also be used to determine a setting of the rear roll stand to which the rear roll stand is set at the point in time at which the strip head enters the rear roll stand. It is possible that when determining the setting of the rear roll stand, the adjustment command determined by the strip position controller for the front roll stand and / or the deviation of the lateral position of the strip head from the target position and / or the temporal change in the lateral position of the strip head are taken into account. In this way, under certain circumstances, the strip run can already be optimized for the strip currently being rolled.

The object is also achieved by a computer program with the features of claim 11. According to the invention, the processing of the computer program causes the control device to operate the rolling train according to an operating method according to the invention.

The object is also achieved by a control device for a rolling train having the features of claim 12. According to the invention, the control device is programmed with a computer program according to the invention, so that the control device operates the rolling train according to an operating method according to the invention.

The object is also achieved by a rolling mill having the features of claim 13. According to the invention, the control device operates the rolling train in accordance with an operating method according to the invention.

The front and rear roll stands are preferably roll stands of a rolling train designed as a finishing train.

Brief description of the drawings

FIG 1

eine Walzstraße mit mehreren Walzgerüsten,

FIG 2

zwei Walzgerüste der Walzstraße in perspektivischer Ansicht,

FIG 3

die zwei Walzgerüste der Walzstraße von FIG 2 von oben,

FIG 4

eine Regelanordnung,

FIG 5

eine weitere Regelanordnung und

FIG 6

eine weitere Regelanordnung.

The above-described properties, features and advantages of this invention as well as the manner in which they are achieved will become more clearly and clearly understood in connection with the following description of the exemplary embodiments, which are explained in more detail in connection with the drawings. Here show in a schematic representation:

FIG 1

a rolling train with several rolling stands,

FIG 2

two roll stands of the rolling train in perspective view,

FIG 3

the two rolling stands of the rolling mill from FIG 2 from above,

FIG 4

a rule arrangement,

FIG 5

another rule arrangement and

FIG 6

another rule arrangement.

Description of the embodiments

According to FIG 1 a metal strip 1 is to be rolled in a rolling train. The metal strip 1 is conveyed through the rolling train in a transport direction x. The metal band 1 can be, for example, a steel band, an aluminum band, a copper band, a brass band or a band made of another metal. The rolling train has several rolling stands 2. As a rule, the rolling train is designed as a finishing train. Accordingly, the roll stands 2 are generally the roll stands 2 of a finishing train.

The number of roll stands 2 is usually between four and eight, for example five, six or seven. Of the roll stands 2 are in FIG 1 (and also in the other figures) only their work rolls 3 are shown. As a rule, however, the roll stands 2 have, in addition to the work rolls 3, additional rolls, especially in the case of four-high stands in addition to the work rolls 3, and in the case of six-high stands, in addition to the work rolls, 3 back-up rolls and intermediate rolls. The work rolls 3, the intermediate rolls and / or the backup rolls can be axially displaceable. However, this is not absolutely necessary. Behind the last roll stand 2 there is often a cooling section and / or a reel (not shown in the figures).

The rolling train is controlled by a control device 4. The control device 4 usually controls the entire rolling train. It is therefore usually only available once for all roll stands 2 of the rolling train. A parameterization of the control device 4 with regard to the individual roll stands 2 can, however, be different from roll stand 2 to roll stand 2.

The control device 4 is generally designed as a software-programmable control device 4. It is therefore usually programmed with a computer program 5. The computer program 5 determines the mode of operation of the control device 4. The computer program 5 comprises machine code 6 which can be processed by the control device 4. The processing of the machine code 6 has the effect that the control device 4 operates the rolling train in accordance with an operating method which is explained in more detail below in connection with the other FIG.

The procedure according to the invention, which is explained in more detail below, is still generally used for each pair of roll stands 2 seized. In the following, in connection with the FIG 2 and 3 and also the other FIG only a single pair of roll stands 2 is considered. The corresponding explanations can, however, apply to each such group of two roll stands 2 directly following one another in the transport direction x of the metal strip 1.

The front roll stand 2 of FIG 2 and 3 , ie that roll stand from which the metal strip 1 runs out is the mainly relevant roll stand 2. With regard to the rear roll stand 2, it is essentially only important that the metal strip 1 is guided to the rear roll stand 2. The reference symbol 2a is used below for the front roll stand 2 and the reference symbol 2b is used for the rear roll stand 2.

In many cases it is also important that the tape head 7 of the metal tape 1, i.e. the beginning of the metal strip 1 has already run out of the front roll stand 2a, but has not yet reached the rear roll stand 2b. This state is usually and also hereinafter referred to as the strip head 7 running out of the front roll stand 2a.

The rolling train also has between two roll stands 2 each - this is only shown in FIG FIG 3 for the area between the front and rear roll stands 2a, 2b - side guides 8, 8 '. The side guides 8, 8 'are adjustable via corresponding adjusting devices 9, 9'. The actuating devices 9, 9 'are generally designed as hydraulic cylinder units. The type and manner of adjustability is, however, of subordinate importance in the context of the present invention. The metal strip 1 is guided laterally by means of the side guides 8, 8 '.

The side guides 8, 8 '(more precisely: the actuating devices 9, 9') are operated in a force-limited manner within the scope of the present invention. This is true at least during the period between the exit of the strip head 7 from the front roll stand 2a and the entry of the strip head 7 into the rear roll stand 2b. Forces F, F ', which are exerted by the side guides 8, 8' on the side edges 10, 10 'of the metal strip 1, are therefore limited. In particular, the side guides 8, 8 'yield when the metal strip 1 exerts too great a force - that is, a force above a force limit value Fmax - on the side guides 8, 8'. The force limit value Fmax can for example be between 2 kN and 10 kN, in particular between 4 kN and 6 kN. According to the representation in FIG 3 the control device 4 can be specified as a parameter. Regardless of whether the force limit value Fmax is specified as a parameter or not, the force limit value Fmax is kept constant within the scope of the operating method according to the invention.

The respective position p, p 'of the side guides 8, 8' can be detected by means of corresponding sensors 11, 11 '. If the detection takes place while the strip head 7 is between the front roll stand 2a and the rear roll stand 2b, the positions p, p 'are for the lateral position y of the tape head 7 and thus also for the deviation δy of the lateral position y from one Target position y * characteristic. This will be explained in more detail later in connection with two possible embodiments of the present invention. The deviation δy of the lateral position y of the tape head 7 from a desired position y * can thus be quantitatively determined by means of the side guides 8, 8 '. It can therefore not only be recorded in a purely binary manner that the deviation δy has occurred and which direction the deviation δy may have. Rather, the extent of the deviation δy can also be recorded, that is to say to what extent the deviation δy occurred.

The positions p, p ′ can therefore be fed to a determination device 12. The determination device 12 can use the detected positions p, p 'to determine the lateral position y of the tape head 7 and the deviation δy of the lateral position y of the tape head 7 from the target position y *.

The lateral position y can, as required, be related to one of the two side edges 10, 10 'or to a location between the two side edges 10, 10' - in particular the middle of the strip. In the following it is assumed that the lateral layer y is on the middle of the tape - in FIG 3 indicated by a dashed line - is related. This definition facilitates the arithmetic and the explanation of the invention, but is not associated with a content restriction.

The control device 4 implements as shown in FIG FIG 3 while processing the computer program 5, often a strip position controller 13 for the front roll stand 2a, among other things. The strip position controller 13 can be designed, for example, as a conventional PI controller. Alternatively, the strip position controller can be designed as a model predictive controller, for example. The deviation δy is fed to the strip position controller 13. The strip position controller 13 determines a control command S for the front roll stand 2a. The change in the deviation δy (that is to say not the absolute value of the deviation δy, but the speed at which the tape head 7 migrates laterally) is counteracted by means of the setting command S. The roll stand 2a is acted upon in accordance with the control command S determined. The control command S can in particular cause a differential rolling force or a differential rolling gap. The strip position controller 13 acts on the front roll stand 2a according to the determined control command S.

In a possible embodiment of the present invention, the side guides 8, 8 'are according to the illustration in FIG 4 Attached to the metal strip 1 in a force-controlled manner via a respective force regulator 14, 14 '. The force regulators 14, 14 ′ are implemented by the control device 4 on the basis of the execution of the computer program 5. The force regulators 14, 14 'can be designed as conventional regulators, in particular as a P controller or PI controller. The force limit value Fmax is given uniformly to the two force regulators 14, 14 'as the force setpoint F *, F' *. According to the difference between the force setpoint F *, F '* and the respective actual force value F, F', the two force regulators 14, 14 'determine corresponding control commands q, q' for the actuating devices 9, 9 'and control them accordingly. The specification of the force limit value Fmax as the force setpoint value F *, F '* for both force regulators 14, 14' causes the force to be limited in this case.

In the case of force regulation, both side guides 8, 8 'rest on the side edges 10, 10'. It is therefore possible in principle to calculate the mean value of the two positions p, p 'and use it as the value for the lateral position y: $$y=\frac{p+p\prime }{2}$$

$$y=p\prime +\raisebox{1ex}{$b$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$$

However, only one of the two positions p, p 'is preferably used. In particular, it is possible, on the basis of the positions p, p ', to determine the side to which the metal strip 1 is deflected, and to use only the position p, p' on this side. As a result, the accuracy of the determination of the lateral position y can be improved. In order to determine the side to which the metal strip 1 is deflected, the sign of the sum of the positions p, p ′ can be evaluated, for example. Depending on the direction of the deflection, the lateral position y - depending on the sign - can then be determined according to one of the two equations below, where b is the - easily known - width of the metal strip 1: $$y=p-\raisebox{1ex}{$b$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$$

$$y=p\prime +\raisebox{1ex}{$\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="imgf0001.png"\; state="\{\{state\}\}">b</figure-callout>}$}\!\left/ \!\raisebox{-1ex}{$2$}\right.$$

In the case of a pure force control, both side guides 8, 8 'rest on the side edges 10, 10'. To a proper To ensure insertion of the tape head 7 into the area between the two side guides 8, 8 ', the force regulators 14, 14' are therefore preferably only activated at a point in time at which the tape head 7 has run out of the front roll stand 2a by a predetermined length Lmin . The predetermined length Lmin is as shown in FIG FIG 3 greater than the distance between the side guides 8, 8 'from the front roll stand 2a. The force regulators 14, 14 are only activated after the mentioned point in time and the side guides 8, 8 'are thereby positioned against the side edges 10, 10'. Before this, for example, a position control can be active which holds the side guides 8, 8 'in a retracted position. The current length L by which the strip head 7 has run out of the front roll stand 2a can be determined, for example, by integrating a transport speed v at which the metal strip 1 runs out of the roll stand 2a.

In a further possible embodiment of the present invention, the force regulators 14, 14 'act on the lateral guides 8, 8' via subordinate position regulators 15, 15 '. In this case, the position of the respective lateral guide 8, 8 'is controlled by means of the subordinate position regulators 15, 15'. For this purpose, the position regulators 15, 15 'as shown in FIG FIG 5 corresponding reference positions p *, p '* and the associated positions p, p' are supplied.

δ ist eine geeignet gewählte Schranke. Sie kann beispielsweise im Bereich weniger Zentimeter liegen. In der Regel liegt sie bei maximal 20 cm.The reference positions p *, p '* are determined in such a way that their difference is slightly greater than the width b of the metal strip 1: $$p^{\ast }-p{\prime }^{\ast }=b+\delta$$

δ is a suitably chosen limit. For example, it can be in the range of a few centimeters. As a rule, it is a maximum of 20 cm.

The force controllers 14, 14 'determine a respective additional setpoint δp, δp' for the respective subordinate position controller 15, 15 '. In this case the force regulators 14, 14 'are generally designed as I regulators, that is to say they have an integrating effect. Furthermore, the force regulators 14, 14 'in this case are generally followed by a respective limiter 16, 16', by means of which the output signal of the respective force regulator 14, 14 'is limited on one side. It is thereby achieved that the force regulators 14, 14 'can cause the lateral guides 8, 8' to yield, but not the closing of the lateral guides 8, 8 '.

In a further possible embodiment of the present invention, the side guides 8, 8 'are according to the illustration in FIG FIG 6 Moved to a respective reference position p *, p '* in a position-controlled manner via a respective position controller 15, 15'. The reference positions p *, p '* are as before in connection with FIG 5 explained, determined in such a way that their difference is slightly greater than the width b of the metal strip 1.

In this case, the two position regulators 15, 15 '- independently of one another - each determine a force setpoint F *, F' * as the respective manipulated variable. The two force setpoints F *, F '* are fed to limiters 16, 16'. In the limiters 16, 16 ', the force setpoints F *, F' * are limited on one side to the uniform force limit value Fmax. The force setpoints F *, F '*, which may be limited, are then fed to the force regulators 14, 14'. The force regulators 14, 14 'are within the scope of the embodiment of FIG 6 the position regulators 15, 15 are subordinated. You determine - as before in the case of the force control according to FIG 4 - Corresponding to the difference between the respective (possibly limited) force setpoint F *, F '* and the respective actual force value F, F', corresponding control commands q, q 'for the actuating devices 9, 9' and control them accordingly.

In the case of force control with subordinate position control and also in the case of position control with force limitation and subordinate force control, a maximum of one of the two side guides 8, 8 'is usually in contact with the respective adjacent side edge 10, 10'. The other side guide 8 ', 8 is spaced apart from its adjacent side edge 10', 10. Only the position p, p 'of the side guide 8, 8', which rests on its associated side edge 10, 10 ', can be used to quantitatively determine the lateral position y. Which of the two side guides 8, 8 'this is can easily be determined using the forces F, F' and the positions p, p '. In particular, that side guide 8, 8 'which does not contact its side edge 10, 10' is in its respective reference position p *, p '*. In addition, no force F, F 'is required to hold this side guide 8, 8' because there is no contact with the corresponding side edge 10, 10 '. For this force F, F 'it is therefore true that it has the value 0. For the determination of the deflected lateral guide 8, 8 ', in particular one condition, the other condition or a combination of both conditions can be used.

As already mentioned, the tape position controller 13 does not use the deviation δy of the lateral position y from the target position y * as part of the determination of the control command S, but rather its time derivative, i.e. the speed at which the tape head 7 migrates laterally. The belt position controller 13 can also take into account the current length L and possibly other variables such as the transport speed v as part of the determination of the setting command S. This allows the behavior of the control to be linearized. If necessary, the strip position controller 13 can continue to smooth and / or limit the control command S.

The strip position controller 13 preferably determines the setting command S in such a way that the change in the deviation δy is reduced as much as possible, in particular to zero. Especially The reduction in the change in the deviation δy to zero means that the metal strip 1 is just running out of the front roll stand 2a from this point in time. This control is thus the desired control of the roll stand 2a. In contrast, the control command S is not determined in such a way that the deviation δy itself is reduced as far as possible.

The control device 4 implements, among other things, a model 17 of the rolling train based on the processing of the computer program 5 or the machine code 6. The control device 4 uses the model 17 to determine a setting of the respective roll stand 2 to which the respective roll stand 2 is set. This determination is made before the strip head 7 enters the respective roll stand 2. The determined setting applies to the point in time from the entry of the strip head 7 into the respective roll stand 2 or - essentially equivalent to this - for the point in time at which the strip head 7 the respective roll stand 2 is reached. This applies to each roll stand 2 of the rolling train and thus also to the front roll stand 2a and the rear roll stand 2b. The setting determined by means of the model 17 for the front roll stand 2a is retained until the deviation δy of the lateral position y of the strip head 7 from the target position y * is detected by means of the side guides 8, 8 '. Up to this point in time, the setting of the front roll stand 2a is not corrected. Without further measures, a subsequent further metal strip 1 is therefore initially rolled with the same, possibly faulty settings. The model 17 is therefore preferably adapted on the basis of the actuating command S determined by the strip position controller 13. This makes it possible to use the adapted model 17 as the basis for determining the setting of the front roll stand 2a when rolling the further metal strip 1. The control command S is that control command S in which the change in the deviation δy is reduced as much as possible.

In the simplest case, the adjustment of the front roll stand 2a is adjusted in advance by means of the model, despite the adjustment 17 determined setting of the rear roll stand 2b retained unchanged. However, it is alternatively possible, when determining the setting of the rear roll stand 2b, to use the setting command S determined by the strip position controller 13 for the front roll stand 2a and / or the deviation δy of the lateral position y of the strip head 7 from the target position y * and / or the time Change in the lateral position y must be taken into account, i.e. correct the previously determined setting. This correction can also take place without adapting the model 17. In particular, the model 17 can be designed in such a way that it determines the setting of the roll stands 2 taking into account the variables mentioned. Here, too, the control command S is that control command S in which the change in the deviation δy is reduced as far as possible.

The control device 4, which implements the operating method according to the invention, is designed in this way on the basis of the programming with the computer program 5. The computer program thus effects as shown in FIG 3 , 4 and 5 that the control device 4 realizes corresponding software blocks.

The invention has many advantages. In particular, the side guides 8, 8 'are usually present anyway. No additional devices are therefore required in order to determine the lateral position y of the tape head 7. Furthermore, due to their force limitation, damage to the side edges 10, 10 'and also to the side guides 8, 8' can be reliably avoided. The risk of tape Doppler can also be significantly reduced. Nevertheless, it can be ensured in a simple manner that the metal strip 1 runs out of the front roll stand 2a as straight as possible.

Although the invention has been illustrated and described in more detail by the preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be made therefrom by the person skilled in the art can be derived without departing from the scope of the invention.

List of reference symbols

1

Metal band

2

Roll stands in general

2a

front roll stand

2 B

rear roll stand

3

Work rolls

4th

Control device

5

Computer program

6th

Machine code

7th

Tape head

8, 8 '

Side guides

9, 9 '

Control devices

10, 10 '

Side edges

11, 11 '

Sensors

12th

Investigative facility

13

Belt position controller

14, 14 '

Force regulator

15, 15 '

Position controller

16, 16 '

Limiter

17th

model

b

width

F *, F '*

Force setpoints

F, F '

Powers

Fmax

Force limit

L.

current length

Lmin

predetermined length

p, p '

Positions

p *, p '*

Reference positions

q, q '

Control commands for control devices

S.

Control command for the front roll stand

v

Transport speed

x

Transport direction

y

lateral position

y *

Target position

δ

Cabinets

δp, δp '

Additional setpoints

δy

deviation

Claims (14)

1. Operating method for a rolling train, in which a metal strip (1) is rolled which has a strip head (7),

   - wherein the rolling train has at least one front roll stand (2a) and one rear roll stand (2b) arranged downstream of the front roll stand (2a) and furthermore has lateral guides (8, 8') for the metal strip (1) between the two roll stands (2a, 2b),

   - wherein the lateral guides (8, 8') are operated with force limitation,

   - wherein during the period between the exit of the strip head (7) from the front roll stand (2a) and the entry of the strip head (7) into the rear roll stand (2b), a deviation (δy) in the lateral position (y) of the strip head (7) from a setpoint position (y*) is quantitatively detected by means of the lateral guides (8, 8'),

   - wherein a control command (S) for the front roll stand (2a) is determined by means of a strip position controller (13),

   - wherein the front roll stand (2a) is acted upon by the strip position controller (13) in accordance with the determined control command (S) and

   - characterised in that the strip position controller (13) determines the control command (S) utilising the time derivative of the deviation (δy) in the lateral position (y) of the strip head (7) from the setpoint position (y*), such that a change in the deviation (δy) in the lateral position (y) of the strip head (7) from the setpoint position (y*) is counteracted.
2. Operating method according to claim 1,
   characterised in that
   the lateral guides (8, 8') are set against the metal strip (1) in a force-controlled manner via a respective force controller (14, 14'), and a force-limiting force setpoint value (F*, F'*) is predefined for the respective force controller (14, 14').
3. Operating method according to claim 2,
   characterised in that
   the force controllers (14, 14') are only activated at a point in time at which the strip head (7) has exited the front roll stand (2a) by a predetermined length (Lmin).
4. Operating method according to claim 2 or 3,
   characterised in that
   the force controllers (14, 14') determine a respective additional setpoint value (δρ, δρ') for a respective subordinate position controller (15, 15'), by means of which a position control of the respective lateral guide (8, 8') takes place.
5. Operating method according to claim 1,
   characterised in that
   the lateral guides (8, 8') are moved in a position-controlled manner to a respective reference position (p*, p'*) via a respective position controller (15, 15'), the position controllers (15, 15') respectively determine, as the respective manipulated variable, a force setpoint value (F*, F'*) for a respective subordinate force controller (14, 14'), and the respective force setpoint value (F*, F'*) is limited to a force limit value (Fmax) by means of a respective limiter (16, 16').
6. Operating method according to one of the above claims,
   characterised in that
   the strip position controller (13) determines the control command (S) such that the change in the deviation (δy) is reduced as much as possible, in particular to zero.
7. Operating method according to one of the above claims,
   characterised in that
   the strip position controller (13) takes into account a current length (L) by which the strip head (7) has exited the front roll stand (2a) when determining the control command (S) .
8. Operating method according to one of the above claims,
   characterised in that
   before the strip head (7) enters the front roll stand (2a) an adjustment of the front roll stand (2a) is determined by means of a model (17) of the rolling train, to which adjustment the front roll stand (2a) is adjusted from the entry of the strip head (7) into the front roll stand (2a) until the deviation (δy) in the lateral position (y) of the strip head (7) from the setpoint position (y*) is detected by means of the lateral guides (8, 8'), the model (17) is adapted on the basis of the control command (S) determined by the strip position controller (13), and when rolling a further metal strip (1) the adapted model (17) is used as the basis for the determination of the adjustment of the front roll stand (2a).
9. Operating method according to one of the above claims,
   characterised in that
   before the strip head (7) enters the rear roll stand (2b) an adjustment of the rear roll stand (2b) is determined by means of a model (17) of the rolling train, to which adjustment the rear roll stand (2b) is adjusted at the time at which the strip head (7) enters the rear roll stand (2b), and when determining the adjustment of the rear roll stand (2b) the control command (S) determined by the strip position controller (13) for the front roll stand (2a) and/or the deviation (δy) in the lateral position (y) of the strip head (7) from the setpoint position (y*) and/or the temporal change in the lateral position (y) of the strip head (7) are taken into account.
10. Operating method according to one of the above claims,
    characterised in that
    the front and rear roll stands (2a, 2b) are roll stands (2a, 2b) of a rolling train designed as a finishing train.
11. Computer program which comprises machine code (6) which can be processed by a control device (4) for a rolling train, wherein the processing of the machine code (6) by the control device (4) causes the control device (4) to operate the rolling train in accordance with an operating method according to one of the above claims.
12. Control device for a rolling train, wherein the control device is programmed with a computer program (5) according to claim 11, such that the control device operates the rolling train in accordance with an operating method according to one of claims 1 to 10.
13. Rolling train for rolling a metal strip (1) which has a strip head (7),

    - wherein the rolling train has at least one front roll stand (2a) and one rear roll stand (2b) arranged downstream of the front roll stand (2a) and furthermore has lateral guides (8, 8') for the metal strip (1) between the two roll stands (2a, 2b),

    - wherein the rolling train has a control device (4) which operates the rolling train in accordance with an operating method according to one of claims 1 to 10.
14. Rolling train according to claim 13,
    characterised in that
    the front and rear roll stands (2a, 2b) are roll stands (2a, 2b) of a rolling train designed as a finishing train.

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