WO2011006851A1

WO2011006851A1 - Belt tension and loop control unit

Info

Publication number: WO2011006851A1
Application number: PCT/EP2010/059941
Authority: WO
Inventors: Wilfried Tautz; Dietrich Wohld
Original assignee: Siemens Aktiengesellschaft
Priority date: 2009-07-15
Filing date: 2010-07-09
Publication date: 2011-01-20
Also published as: CN102470410B; EP2277639A1; PL2454033T3; EP2454033A1; CN102470410A; EP2454033B1

Abstract

A characteristic value (Z'*) of the desired tension (Z*) of a belt (2) clamped between two roll stands (1', 1") and the corresponding actual value (Z') are fed to a tension control unit (15). On the basis of the characteristic values (Z'*, Z') fed to it, the tension control unit (15) determines a tension compensating signal (ZA), which comprises an integral portion (IA). On the basis of the integral portion (IA), a first additional speed target value (δv1*) is determined for at least one of the two roll stands (1', 1"). The integral portion (IA) is temporally delayed and subtracted, with this delay, from the tension output signal (ZA). On the basis of the difference thus determined, a first target adjustment speed portion (ωl*) for the loop lifter (3) is determined. A loop control unit (16) is fed an actual position (φ) of a loop lifter (3), which is disposed between the two roll stands (1', 1") and placed against the belt (2), and the corresponding target position (φ*). The loop control unit (16) determines a loop compensating signal (SA) on the basis of the target position (φ*) and the actual position (φ). By delaying the loop compensating signal (SA), a second target adjustment speed portion (ω2*) for the loop lifter (3) is determined. On the basis of the loop compensating signal (SA), a second additional speed target value (δv2*) is determined for at least one of the two roll stands (1', 1"). The sum (δv*) of the first and second additional speed target values ((δv1*, δv2*) is output to a speed controller (12) for the at least one of the two roll stands (1', 1"). A resulting target adjustment speed (ω*) is put to an adjustment unit (14), by way of which the position of the loop lifter (3) is adjusted, with the first and second target adjustment speed portions (ω1*, ω2*) being included in said speed as addends.

Description

description

Bandzug- and Schiingenregelung The present invention relates to a control method for controlling a Istzuges, which prevails in a clamped between two stands rolling on a debit train and an actual position of an arranged between the two rolling stands, employed on the band ski lifter to a SoIl position.

The present invention further relates to a computer program which has machine code which can be processed directly by a control device and whose execution by the control device causes the control device to carry out such a control method.

The present invention further relates to a control device which is designed such that it carries out such a control method during operation.

When rolling strips - in particular of metal strips - in multi-stand rolling mills, a strip tension is usually set in the individual strip sections (that is to say in the sections of the strip which are located between each two successive strip rolling mills of the rolling train). For technological reasons - for example, to maintain the thickness and width constancy of the strip - the strip tension should be kept as constant as possible. To set the strip tension, a speed setpoint is usually determined, which acts on one of the two roll stands delimiting the strip section. Furthermore, an employment of a ski lifter is set, which is arranged between the two successive rolling stands and is set against the belt.

Also, for detecting the tape tension the ski jacks are often used in the prior art. Hiring the Ski jacks take place in the prior art by means of an electric drive (more rarely) or a hydraulic cylinder unit (more frequently). By means of the loop lifter not only the tension in the band is measured. Furthermore, an amount of band that is buffered in the respective band section (loop) is set via the deflection of the loop lifter. Not only the train in the band, but also the position of the ski lifter must be regulated. Thus, in particular, the loop lifter can be brought into its raised position only after the threading of the tape, in which he deflects the tape. Also, the ski jack must be lowered before unthreading the tape again. As is clear from simple geometrical considerations, an adjustment of the loop lifter directly affects the length of the band located in the band section and thus indirectly the strip tension. The loop control is therefore coupled to the tension control.

From the technical paper "Development of Looper Tension Control Systems for Hot Strip Mill" by C.J. Park et al., Proceedings of the International IASTED Conference, Applied Simulation and Modeling 2000, July 24-26, 2000, Banff, Alberta,

Canada, pages 423 to 427, is a control method for controlling a Istzuges, which prevails in a clamped between two stands rolling on a debit train and an actual position of an arranged between the two rolling stands, attached to the band ski jacks on a reference position known, the Includes tension regulator and a loop controller. The train tension and the actual tension are fed to the tension controller. The loop controller, the target position and the actual position are supplied. Both controllers are designed as PI controllers. Both controllers each determine an output signal.

Both output signals act both on the rolling speed of the upstream or downstream roll stand and on the position of the loop lifter. Each of the four gene is set via a corresponding gain factor.

The technical paper "Application of ILQ control theory to steel rolling processes" by H. Imanari et al., Proceedings of The 7th International Conference on Steel Rolling 1998, Chiba, Japan, pages 36 to 41, is to be taken from a substantially equivalent stored disclosure. The control methods known from the technical articles represent an advance over the conventional control methods and work with a decoupling of the control interventions.The object of the present invention is to create possibilities by means of which the interventions of the loop controller have no or only a very little have little effect on the Istzug and operations of the Zugreglers done with high dynamics.

The object is achieved by a control method having the features of claim 1. Advantageous embodiments of the control method according to the invention are the subject of the dependent claims 2 to 8.

The object is further achieved by a computer program having the features of claim 9. Furthermore, the object is achieved by a control device having the features of claim 11.

In the control method according to the invention, it is provided

that characteristic values are supplied to a draft regulator for the desired tension and for the actual tension,

- That the tension controller determines a train compensation signal based on the characteristic values supplied to it

Integral part comprises, in that, based on the integral component, a first additional speed setpoint is determined for at least one of the two rolling stands,

- that the integral part is delayed in time,

in that, based on the difference between the train compensation signal and the delayed integral component, a first desired shift speed component for the ski lift is determined,

that the set position and the actual position are fed to a loop controller which determines a loop compensation signal on the basis of the set position and the actual position,

in that, by delaying the loop compensation signal, a second desired adjustment speed portion for the sling lifter is determined,

in that a second additional speed setpoint for the at least one of the two rolling stands is determined on the basis of the loop compensation signal,

- That the sum of the first and second additional speed setpoint is output to a speed control for the at least one of the two rolling stands, and

- That an adjusting unit, by means of which the position of the loop lifter is adjusted, a resulting Sollverstellgeschwindigkeit is output, enter into the summaries as the first and the second target speed component.

The terms "train compensation signal" and "loop compensation signal" have been chosen because they express which controller they originate from, what deviation they are to counteract, and to be able to distinguish them verbally. A more important meaning is not the word choice. One would have the two signals as well as "output of Zugreglers" and "output of the

For the correct adaptation of the interventions made by one of the two controllers, it is preferably provided that, when determining the additional speed setpoint values relative to the desired adjustment speed portions, the derivative the length of the band clamped between the two stands according to the position of the loop lifter. As part of the determination of the resulting Sollverstellgeschwindigkeit both the integral component of the Zugausgangssignals and the loop output signal are delayed in time. The control method can therefore be simplified by subtracting the instantaneous integral component from a modified loop compensation signal, delaying the resulting difference, and adding the delayed difference to the train output signal as the result of determining the resulting desired adjustment rate, wherein the modified loop compensation signal is obtained by scaling the Loop compensation signal is determined with a derivation taking into account value.

It is possible that the characteristic value for the actual tension is measured directly. In general, however, the value is either not measurable or at least not easy to measure. In the context of the present invention, it is therefore preferable for the value characteristic of the actual tension to be determined indirectly on the basis of measured variables by means of a tape tension observer. Tape tension observers as such are known to those skilled in the art.

In the resulting Sollverstellgeschwindigkeit - among other things - the first Sollverstellgeschwindigkeitsanteil included, which is determined by the tension controller. In many cases, the tape tension observer will continue to be supplied with the resulting target adjustment speed, that is, the sum of the target adjustment speed components. Due to this circumstance, there is a positive feedback within the control. The positive feedback can lead to instability of the tension controller. Therefore, it is preferably provided that a substitute time constant for the tape tension observer is determined dynamically on the basis of variables which are characteristic of the stability of the tension controller, and the tape tension observer determines the characteristic value for the actual tension, taking into account the equivalent time constant. te determined. Alternatively or additionally, it can be provided that a control gain for the tension controller is determined dynamically on the basis of the variables characteristic of the stability of the tension controller, and the tension controller determines the tension compensation signal taking into account the control gain.

In a preferred embodiment of the control method according to the invention, it is further provided that a feedforward control is connected in parallel with the tape tension observer. As a result, the dynamics by means of which the value characteristic of the actual tension is determined can be increased.

In many cases, it is still beneficial

- That a moment regulator of the value characteristic value for the train, a caused by the ski jam own moment and one of an adjusting device for the loop lifter adjusting torque are supplied and

in that the torque controller determines an additional target displacement speed component, which likewise enters into the resulting setpoint speed as a summand.

This allows a higher dynamics can be achieved. The torque controller is preferably designed as a P controller (P = proportional) or PD controller (= proportional differential).

The computer program according to the invention is characterized in that the execution of its machine code by a control device causes the control device to carry out a control method according to the invention. The same applies analogously to the control device itself. The computer program can in particular be stored on a data carrier in machine-readable form. Further advantages and details will become apparent from the following description of exemplary embodiments in conjunction with the drawings. In a schematic representation: 1 shows a multi-stand rolling train,

2 shows a single band section,

3 shows a tension control,

4 shows a loop control,

5 shows a possible combination of the tension control of FIG. 3 and the loop control of FIG. 4, FIG.

6 shows an overall circuit diagram of several controllers,

7 shows a further overall circuit diagram of several controllers and

8 shows a possible supplement to a tape tension observer.

According to FIG. 1, a rolling train has a plurality of rolling stands 1. The rolling mill may in particular be a hot rolling mill. In FIG. 1, a total of three rolling stands 1 are shown. As a rule, however, the rolling train has more than three rolling stands 1, for example five to eight rolling stands. In the rolling stands 1, a band 2 is rolled. The band 2 is usually a metal band, for example a steel band, an aluminum band or a copper band. However, it may be made of a different material, such as a non-ferrous metal or a non-metal. The rolling mills 1 are driven to roll the strip 2 at a roll speed v specific to the respective rolling stand 1.

Between each of two immediately consecutive WaIz- scaffolds 1 each a loop lifter 3 is arranged. Each ski lifter 3 has a looper roller 4, which is employed on the belt 2. By means of the loop lifter 3, the belt 2 is deflected between the rolling stands 1 from a rolling line 5 (that is, the direct connecting line of the roll nips of the rolling stands 1 with each other), usually upwards.

Between the rolling stands 1 (and usually also between a Abhaspei 6 and the first of the rolling stands 1 and between see the last of the rolling stands 1 and a reel 7), the band 2 is clamped. In band 2, therefore, there is a current Z. The actual Z within each band section is (of course) uniform. In the individual band the actual Z trains may be the same or different from each other.

2 shows a single belt section including the two rolling stands 1 delimiting the belt section 1. The two rolling stands 1 are provided with the reference symbols 1 'and 1 "in FIG 2 in order to be able to differentiate them from one another in accordance with their sequence as a front rolling stand 1 'and as a rear rolling stand 1 ", the section shown in FIG. 2 is an arbitrary section.

According to FIG 2, a control device 8 is present. The control device 8 is designed such that it performs a control method during operation, which will be explained in more detail below.

The control device 8 can be implemented by circuitry. As a rule, however, the control device 8 is designed as a software programmable control device 8 in accordance with the representation of FIG. In this case, the control device 8 is programmed with a computer program 9. The computer program 9 has machine code 10. The machine code 10 can be processed directly by the control device 8. The processing of the machine code 10 by the control device 8 causes the control device 8 carries out the steps of the control method explained below. The computer program 9 can be supplied to the control device 8 in any manner. For example, it is possible to supply the computer program 9 to the control device 8 via a computer-computer connection, for example a LAN or the Internet. It is likewise possible to supply the computer program 9 to the control device 8 via a data carrier 11, on which the computer program 9 is stored in machine-readable form. The data carrier 11 can be designed for this purpose as needed. Purely by way of example is in FIG the disk 11 shown as a USB stick. However, the data carrier 11 could be designed differently, for example as an SD memory card or as a CD-ROM. According to FIG 2, the control device 8 is supplied with a desired train Z *. Furthermore, the control device 8 is supplied with a characteristic Z 'characteristic of the actual Z train. Finally, an actual position φ of the loop lifter 3 and a set position φ * of the loop lifter 3 are fed to the control device 8. By means of the control device 8, the actual tension Z and the desired tension Z * and the actual position φ are to be regulated to the desired position φ *.

Based on the mentioned variables Z *, Z ', φ, φ *, the control device 8 determines a resulting additional speed setpoint value δv * for the rolling stand 1' arranged upstream of the ski lifter 3. The resulting additional speed setpoint δv * is output to a speed controller 12 for the upstream rolling stand 1 '. Alternatively, the resulting additional speed setpoint δv * could be determined for the roll stand 1 "downstream of the ski lifter 3 and output to a speed control 13 of this rolling stand 1". This is indicated by dashed lines in FIG. A division into both rolling stands 1 ', 1 "can be made.

Furthermore, the control device 8 uses the quantities Z *, Z ', φ, φ * to determine a resulting setpoint speed ω * for the loop lifter 3. The resulting setpoint speed ω * is output to an adjusting unit 14, by means of which the position of the loop lifter 3 is set , The adjustment unit 14 can operate electrically or - preferably - hydraulically.

The manner of determining the resulting additional speed setpoint value δv * and the resulting setpoint speed co * is the subject matter of the present invention. The control device 8 comprises a tension regulator 15. The tension regulator 15 and its mode of action are explained in more detail below in conjunction with FIG. The control device 8 further comprises a loop controller 16. The loop controller 16 and its mode of action will be explained in more detail below in conjunction with FIG. The entire control device 8 will be explained again in connection with FIG 5 below.

According to FIG. 3, the tension regulator 15 is supplied with a value Z '* characteristic of the desired tension Z * and the value Z' characteristic of the actual tension Z. The tension regulator 15 is preferably designed as a PI controller (PI = proportional-integral). On the basis of the characteristic values Z '*, Z' supplied to it, it determines a train compensation signal ZA.

For example, a setpoint determination device 8 'may be present, to which the desired train Z * and further variables are supplied. The further variables can include, for example, the actual position φ of the loop lifter 3, the distances of the loop lifter 3 from the upstream and downstream rolling stand 1 ', 1 "and further geometry parameters, so that the setpoint determination device 8' is able to reference it Size of the distances of the looper roller 4 of the rolling stands 1 ', 1 "and the height of

Loop lifter role 4 relative to the rolling line 5 to determine.

Furthermore, the setpoint determination device 8 'is supplied with quantities which describe the strip 2, for example its thickness, its width and its elasticity mode. If these quantities are known, the value Z '* characteristic of the desired tension Z * can be determined on the basis of simple geometric calculations. The characteristic value Z '* corresponds in this case a desired force, the tape 2 on the

Should exercise ski jig 3, or a target torque, which should exercise the band 2 on the ski jig 3.

Of the variables which are supplied to the setpoint determination device 8 ', at least the desired train Z * and the actual position φ (alternatively the desired position φ *) are variables. Both other sizes may alternatively be variables or parameters. The difference between variables and parameters is that variables can vary dynamically in the operation of the control device 8, while parameters are set once during the commissioning of the control device 8 and are then kept constant.

The setpoint determination device 8 'can be part of the control device 8. Alternatively, it may be arranged outside the control device 8. In the latter case, the control device 8 is supplied with the corresponding characteristic value Z '* instead of the reference pull Z *.

The value Z 'characteristic of the actual pull Z can be measured alternatively or otherwise determined. This will be discussed later.

According to FIG. 3, the tension controller 15 comprises an integrator 17. The train compensation signal ZA therefore comprises an integral component IA. Furthermore, the tension controller 15 comprises a branch 18, via which a proportional component PA of the train compensation signal ZA is output.

An integration gain kl of the integrator 17 may be a constant. However, it is preferably a variable which increases, inter alia, with increasing control deviation (| Z '* - Z' |).

According to FIG. 3, based on the integral component IA, a first additional speed setpoint value δvl * for the upstream rolling stand 1 'is determined. The first additional speed setpoint δvl * enters the resulting additional speed setpoint value δv * as one of two summands. According to FIG. 3, furthermore, the integral component IA is fed to a delay element 19, in which the integral component IA is delayed in time. The time-delayed integral component is referred to below as a delayed integral component IA 'to distinguish it from the instantaneous integral component IA.

The time-delayed integral component IA 'is subtracted in a node point 20 from the train compensation signal ZA. On the basis of the resulting difference, a first Sollverstellge- speed ratio ωl * is determined for the ski looper 3. The first Sollverstellgeschwindigkeitsanteil ωl * goes as one of several summands in the resulting Sollver- Stellgeschwindigkeit ω * a.

The desired position .phi. * And the actual position .phi. Are supplied to the loop regulator 16 as shown in FIG. The loop controller 16 may be formed as a P-controller. It determines a loop compensation signal SA on the basis of the position φ * and the actual position φ. The loop compensation signal SA is supplied to a delay element 21 (among others). In the delay element 21, the loop compensation signal SA is delayed in time, thus determining a delayed loop compensation signal SA '. The delayed loop compensation signal SA 'corresponds to a second desired adjustment speed component ω2 * for the loop lifter 3. The second desired adjustment speed component ω2 * also enters into the determination of the resulting target adjustment speed ω * as a summand.

According to FIG. 4, a second additional speed setpoint value δv2 * for the upstream rolling stand 1 'is furthermore determined on the basis of the loop compensation signal SA. The second additional speed setpoint δv2 * is the second summand, which enters the resulting speed setpoint δv *.

According to FIG 3, a divider member 22 is present. In the divider element 22, the difference between the train output signal ZA and the delayed integral component IA 'is divided by a value kL.

The value kL corresponds to the derivation of the length of the band 2, which is between the two the band section limiting rolling stands 1 ', 1 ", according to the position φ of the loop lifter. 3

In an analogous manner, when ascertaining the second speed additional desired value δv2 * it is provided to multiply by the value kL by means of a multiplier 23 and to divide this multiplication in the context of the determination of the second desired speed component ω2 * by means of a divider 24. on by the value kL. The loop compensation signal multiplied by the value kL is hereinafter referred to as modified loop compensation signal SA ".

The activation of the adjusting unit 14 delayed relative to the output of the resulting additional speed setpoint value δv * ensures that the actual position φ of the loop lifter 3 is not tracked until a corresponding adaptation of the between the rolling stands 1 ', 1 by the resulting speed setpoint value δv * By subtracting the time-delayed integral component IA 'from the train output signal ZA, it is achieved that the integral component IA is not permanently output to the loop lifter 3, but rather from the loop lifter 3 in accordance with the time delay by the delay member 19 the upstream roll stand 1 '(optionally alternatively or additionally to the downstream roll stand 1 ") is shifted. Due to the time delay of the delay element 19, the time delay is compensated, which has the regulated path as such. Thereby, the effects of the resulting additional speed setpoint δv * and the resulting target set speed ω * are synchronized with each other. 5 shows the total interconnection of the control device 8. The embodiment according to FIG. 5 is functionally completely equivalent to the procedure explained above in connection with FIGS. 3 and 4. Only the order of individual addition, subtraction and delay measures is slightly modified. In particular, in the context of FIG. 5, the instantaneous integral component IA is subtracted from the modified loop compensation signal SA ", the difference thus determined is delayed and the delayed difference to

Zugausgangesignal ZA added. This procedure is particularly computationally simpler, because the delay element 21 can be saved. Functionally, however, there is no difference.

In principle, it is possible to measure the value Z 'characteristic of the actual Z train. In many cases, however, the measurement is technically complicated or even impossible. For this reason, according to FIGS. 3 and 5, a tape tension observer 25 is present. By means of the tape tension observer 25, the value Z 'characteristic of the actual tension Z is determined indirectly on the basis of measured variables. The measured variables may in particular comprise an adjusting moment MV applied by the ski lifter 3. Furthermore, the tape tension observer 25 can be supplied with quantities which are characteristic of the adjustment speed ω of the ski lifter 3 and a self-moment ME caused by the ski lifter 3. At the adjustment speed ω, alternatively, a measured actual value can be used or the resulting desired adjustment speed ω * can be used. The intrinsic moment ME is essentially caused by the weight force of the components of the loop lifter 3 acting on the adjusting unit 14. The intrinsic moment ME can alternatively be constant or be a function of the actual position φ of the loop lifter 3.

The construction and operation of the tape tension observer 25 are well known to those skilled in the art. In particular, the Bandzugbeobachter 25 may be constructed as the load observer, in FIG. 3 of the patent application "Load control of a hydraulic cylinder unit with load observer" of the applicant, character of the applicant 200907995, filed with the European Patent Office on 03 July 2009, official file reference 09 164 521 , shown in detail and in conjunction with This figure is described. Further details can therefore be dispensed with.

The control method according to the invention gives very good results. By the embodiments described below in connection with Figures 6 to 8, the control method is still further improved. The embodiments described below in conjunction with FIGS. 6 to 8 can alternatively be implemented individually or in combination with one another.

According to FIG. 6, a torque controller 26 is present in addition to the tension controller 15 and the sling regulator 16. The torque controller 26 is supplied with the characteristic Z '*, the characteristic torque ME and the adjusting torque MV characteristic of the reference train Z *. The torque controller 26 uses the quantities Z '*, ME, MV supplied to it to determine an additional target displacement speed component ω3 *. The additional target displacement speed component ω3 * also enters the resulting target displacement speed ω * as a summand. The torque controller 26 may be designed in particular as a P controller or as a PD controller. It causes a stabilization of the behavior of the entire control device

In addition, according to FIG. 6, a start-up controller 27 can be present. The approach controller 27 is, if it is present, active only in an initial phase. The approach controller 27 is activated as soon as it is detected that the band 2 has been threaded into the roll stand 1 "downstream of the loop lifter 3. The start-up regulator 27 is switched off when the loop lifter roll 4 contacts the band 2. The switch-off can be performed as a function of The difference between the actual pull Z and the desired pull Z * (or the corresponding characteristic values Z '*, Z') is made by the approach controller 27, which ensures that the loop lifter 3 quickly reaches the strip 2 from the lowered position (below the rolling line 5) is hired.

The control device 8 according to the invention can also have a position controller 28 according to FIG. The position Ler 28 is used in particular when the ski jig 3 is to be kept in a fixed position when threading or unthreading of the belt 2 below the rolling line 5. It is active as an alternative to the tension controller 15 and the loop controller 16 (and possibly also the torque controller 26 and / or the approach controller 27). The switchover takes place - preferably in a sliding manner - as a function of an input and output detection. The position controller 28 is preferably constructed as described in the patent application "control device for a hydraulic cylinder unit" of the applicant, character of

Applicant 200910164 filed with the European Patent Office on Jul. 03, 2009, Serial No. 09 164 543, is described in detail. In individual cases, furthermore, the resulting additional speed setpoint value δv * according to FIGS. 6 and 7 can be delayed by a PTI delay element 31.

FIG. 7 furthermore shows that the control device 8 can have an adaptation device 29. The adaptation device 29 is supplied with quantities which are characteristic of the stability of the tension regulator 15. The adaptation device 29 determines, for example, a replacement time constant T for the tape tension observer 25. If this is the case, the adaptation device 29 outputs the equivalent time constant T to the tape tension observer 25. In this case, the tension detector 25 determines the value Z 'characteristic of the actual tension Z, taking into account the equivalent time constant T.

Alternatively or additionally, the adaptation device 29 can determine a control gain k for the tension controller 15 on the basis of the variables supplied to it and output it to the tension controller 15. The tension controller 15 determines the train compensation signal ZA in this case, taking into account the control gain k transmitted to it. The characteristic of the stability of the Zugreglers 15 sizes can be determined as needed. For example, the actual position φ of the loop lifter 3 can be used. Regardless of which sizes the adaptation device Although the equivalent time constant T and / or the control gain k is determined by means 29, the determination is carried out dynamically, that is to say during operation of the control device 8. The equivalent time constant T and the control gain k are variables, not parameters.

According to FIG. 8, a feedforward control 30 can furthermore be connected in parallel with the tape tension observer 25. As a result of this refinement, the characteristic Z 'characteristic of the actual pull Z can be determined with greater dynamics. In particular, changes in the value Z 'characteristic of the actual pull Z, which arise as a result of changes in the actual position φ of the loop lifter 3, immediately appear in the characteristic value Z' without the tape tension observer 25 having to settle first. The pre-control 30 is fed at least the actual position φ of the loop lifter 3 as a variable.

The present invention has many advantages. In particular, the control method according to the invention is fast and stable. Furthermore, a simple retrofitting of existing control devices is given. Furthermore, the control method according to the invention has superior control results. In particular, a change in the actual position φ of the loop lifter 3 has virtually no effect on the actual pull Z. This is particularly important when lowering the loop lifter 3 before unthreading the strip 2. Furthermore, deviations of the actual pull Z from the set pull Z * are corrected very quickly. Nevertheless, only a very small excitation of natural vibrations occurs. Another advantage of the control method according to the invention is that no measured value for the adjustment speed ω of the loop lifter 3 is required. There are also no slow, creeping transients, but there is a quick settling. The above description is only for explanation of the present invention. The scope of the present invention, however, is intended to be determined solely by the appended claims.

Claims

claims

1. A control method for controlling a actual tension (Z), which prevails in a belt (2) clamped between two rolling stands (1 ', 1 "), on a desired tension (Z *) and an actual position (φ) of one between the two rolling stands ( 1 ', 1 ") arranged on the belt (2) Schiingenhebers (3) to a desired position (φ *),

wherein characteristic values (Z '*, Z') are supplied to a tension controller (15) for the desired tension (Z *) and for the actual tension (Z),

the traction controller (15) ascertaining, on the basis of the characteristic values (Z '*, Z') supplied thereto, a train compensation signal (ZA) which comprises an integral component (IA),

in which, based on the integral component (IA), a first additional speed setpoint value (δvl *) is determined for at least one of the two rolling stands (1 ', 1 "),

- wherein the integral component (IA) is delayed in time,

wherein a first Sollverstellge- speed component (ωl *) for the loop lifter (3) is determined based on the difference of train output signal (ZA) and delayed integral component (IA '),

wherein the set position (φ *) and the actual position (φ) are fed to a loop controller (16) which determines a loop compensation signal (SA) on the basis of the position (φ *) and the actual position (φ),

in which a second nominal displacement speed component (ω2 *) for the ski lifter (3) is determined by delaying the loop compensation signal (SA),

wherein a second additional speed setpoint value (δv2 *) for the at least one of the two rolling stands (1 ', 1 ") is determined on the basis of the loop compensation signal (SA),

wherein the sum (δv *) of the first and second additional speed setpoint values (δvl *, δ2v *) is output to a speed control (12) for the at least one of the two rolling stands (1 ', 1 "),

- Wherein an adjusting unit (14), by means of which the position of the Schiingenhebers (3) is set, a resul- tierende Sollverstellgeschwindigkeit (ω *) is output, in which as summands of the first and the second Sollverstell- speed share (ωl *, ω2 *) received.

2. Control method according to claim 1,

characterized ,

in determining the additional speed setpoints (δvl *, δv2 *) relative to the Sollverstellgeschwindigkeitsanteilen (ωl *, ω2 *), the derivative of the length of between the two rolling stands (1 ', 1 ") clamped band (2) after the position (φ) of the ski lifter (3) is taken into account.

3. Control method according to claim 1 or 2,

characterized ,

in that as part of the determination of the resulting desired displacement speed (ω *) the instantaneous integral component (IA) is subtracted from a modified loop compensation signal (SA "), the resulting difference is delayed and the delayed difference is added to the train output signal (ZA), the modified loop compensation signal (SA ") is determined by scaling the loop compensation signal (SA) with a derivative-taking value (kL).

4. Control method according to claim 1, 2 or 3,

characterized ,

the value (Z ') characteristic of the actual tension (Z) is determined indirectly on the basis of measured variables (MV) by means of a tension detector (25).

5. control method according to claim 4,

characterized ,

that a substitute time constant (T) for the tape tension observer (25) is determined dynamically on the basis of variables which are characteristic for the stability of the tension controller (15) and the tape tension observer (25) determines the value (Z ') characteristic of the actual tension (Z) taking into account the Substitute time constant (T) determined and / or - That on the basis of the stability of the tension controller (15) characteristic variables dynamically a control gain (k) for the tension controller (15) is determined and the tension controller (15) determines the train compensation signal (ZA) taking into account the control gain (k).

6. Control method according to claim 4 or 5,

characterized ,

in that a feedforward control (30) is connected in parallel with the tape tension observer (25).

7. Control method according to one of the above claims,

characterized ,

in that a torque controller (26) determines the characteristic value (Z '*) characteristic of the reference train (Z *), a self-torque (ME) effected by the ski lifter (3) and an adjusting device (14) for the ski lifter (3 ) Verstellmoment (MV) are supplied and

- That the torque controller (26) determines a Zusatzsollverstellgeschwindigkeitsanteil (ω3 *), which also as

Summand into the resulting Sollverstellgeschwindigkeit (ω *) received.

8. control method according to claim 7,

characterized ,

that the torque controller (26) is designed as a P-controller or as a PD controller.

9. computer program, the machine code (10), which is directly abarbeitbar of a control device (8) and its processing by the control device (8) causes the control device (8) a control method with all the steps of a control method according to one of the above claims performs.

10. Computer program according to claim 9,

characterized ,

that it is stored on a data carrier (11) in machine-readable form.

11. control device,

characterized ,

in that it is designed such that, during operation, it carries out a control method with all the steps of a control method according to one of Claims 1 to 8.