EP1986795A1 - Method for suppressing the influence of roll eccentricities - Google Patents

Abstract

The invention relates to a method for suppressing the influence of roll eccentricities on the run-out thickness (ha) of a rolled stock (10), which runs through a rolling stand (1), roll eccentricities being identified by using a process model (27) and taken into consideration in the determination of a correction signal for at least one final control element, preferably a final control element for the adjustment position, of the rolling stand (1), wherein the measured tensile force (Fz) upstream of the rolling stand (1) is fed to the process model (27) to identify the roll eccentricities. According to the invention, variations in tensile force are fed back in a targeted manner to reduce the effects of periodic roll eccentricities on the rolled stock (10), whereas all other sources of variation are eliminated. A process model (27) of the rolling nip and the rolls, preferably based on the observer principle, produces reliable data on the roll eccentricity. In this way, given dimensions of the rolled stock (10) are achieved more uniformly than previously.

Description

description

Method for suppressing the influence of roll eccentricities

The invention relates to a method of suppressing the influence of roll eccentricities on the run-out thickness ei ^¬ nes rolled stock, which passes through a rolling stand, wherein Wal ^¬ zenexzentrizitäten using a process model are dentifiziert i and for the determination of a correction signal for at least one control device for an actuator ^¬ be considered member of the rolling mill.

In roll stands are often found, for example, by imprecise machined backup rolls or by imprecise mounting of the support rollers eccentricities of the rollers, affecting the quality of the rolled strip, wherein, depending on the stiffness of the roll stand and the rolled Wal ^¬ zenexzentrizitäten with the speed of the eccentricity-bearing rollers, usually the back-up rollers, in the belt. The frequency spectrum of the eccentricities and the disturbances they cause in the band essentially comprises the fundamental frequencies of the upper and lower support rollers; but there are also higher harmonic harmonics, but often occur only with reduced amplitudes in appearance. Due to slightly different diameters and speeds of the upper and lower support roller, the frequencies assigned to the support rollers may differ from one another.

EP 0170016 Bl describes a method of the ge ^¬ type mentioned, wherein the influence is compensated by roll eccentricities in the Position-or thickness control of roll stands, where the roll eccentricities on the basis of egg ner measurement of the rolling force to be identified in the roll stand. To measure the rolling force oil pressure sensors are usually used, the measured values are significantly distorted by friction influences. This requires that there is no sufficient Reliable and effective suppression of the influence of roller eccentricities can be done with the help of the measuring instruments. More reliable and accurate measuring methods for the rolling force are too expensive and too expensive.

From EP 0 698 427 B1 it is known to use the outlet thickness of the rolling stock instead of the rolling force as the measured value in a method for suppressing the influence of roll eccentricities. Thickness encoders, however, are very expensive and therefore generally only provided in front of and behind the first and after the last rolling mill in multi-stand rolling trains.

The object of the invention is to provide a method for suppressing the influence of roller eccentricities, which avoids the known from the prior art and in particular the disadvantages described above.

This object is achieved by a method for suppressing the influence of roll eccentricities on the outlet thickness of a rolling stock which passes through a roll stand, wherein roll eccentricities are identified using a process model and in the determination of a Cor ^¬ rectification signal for at least one control device for an actuator be taken into account of the rolling stand, wherein for identifying the Walzenexzentrizitäten the at least one process model measured values of the tensile force are fed before the mill stand. Such a highly accurate identifi cation of ^¬ will roll eccentricities and thus allows a particularly reliable and efficient method for Un ^¬ suppression of the influence of roll provided. Since reliable measuring encoders for strip tensioning in rolling mills are provided anyway, the expense of installing additional encoders specifically for identifying roll eccentricities is also avoided. Advantageously, the tensile force can be measured after the roll stand.

Advantageously, the process model and / or at least one additional model describes the transmission behavior from the setting position to the strip tension.

Advantageously, a model with observer structure can be used.

Advantageously, which measured values can be up to the strip tension inversely taken into account the transmission characteristics of the outlet thickness of a module supplied ^¬ leads are of the tensile force.

Advantageously, the dependence on the belt speed can be taken into account adaptively.

Advantageously, the process model describing at least the roll gap ^¬ and the rolls of the rolling stand.

Advantageously, a process model with an observer structure is used.

Advantageously, an inlet thickness compensation of the measured values used for the identification of the roll eccentricities can take place.

The object underlying the invention is also achieved by a computer program product according to claim 9.

Following more advantages and details will be announced the He-making ^¬ example and with reference to the drawings be ^¬. Show it:

1 shows a rolling mill in connection with a control device with a process model, 2 shows a schematic representation of the observer principle used for identifying the roll eccentricities,

3 shows the coupling of the tension measurement to the process model, FIG. 4 shows an inlet thickness compensation for the measured values used.

1 shows schematically and exemplarily a rolling stand 1 ei ^¬ ner rolling mill for rolling a rolled product 10. A WaIz- train for rolling a rolled material 10 includes one or more such rolling stands 1 on. Before or after a roll stand 1, a further roll stand 1, a reel device, a cooling device and / or another device, eg for thermal and / or mechanical Walzgutbeeinflussung and / or means for transporting the rolling stock 10 before ^{¬ be} seen. The rolling stock 10 is preferably a band, a profile, a wire or a slab. For example, the rolled material 10, a metal strip, for example a steel band, a non-ferrous metal ^¬ band or an aluminum band.

A rolling stand 1 has at least one upper support roller 4 with a radius R ₀ and at least one lower support roller 5 with a radius R _n . The roll stand 1 shown has Minim ^¬ least an upper work roll 2 and at least one lower work roll 3, wherein the diameter of a work roll 2 or 3 is usually smaller than the diameter of a supporting roller 4 and 5. In the example shown to regulate the setting position of the roll stand 1, a hydraulic actuating device 7 which can be actuated via a control valve 6 is provided. Alternatively or additionally, an electromechanical adjustment system can also be provided. The adjusting device 7 and the Anstellsystem not shown serve to adjust the roller adjustment s. The hydraulic adjustment is based on the scaffolding frames. The elastic frame is symbolically represented by a spring with the spring constant C _G. The roll stand 1 is traversed by a rolling stock 10, wherein the thickness of the rolling stock 10 when passing through the roll gap with the aid of the work rolls 2, 3 from the inlet thickness h _{e is} reduced to the outlet thickness h _a . The rolled stock 10, to an equivalent material defects with the spring constant C _M is associated in the nip, runs at the speed v ^¬ Einlaufge _SE in the nip, and leaves the roll gap ^¬ with the exit speed v _SL.

The roll eccentricities of the upper back-up roll 4 and the lower back-up roll 5, respectively, may be due to uneven roll wear, deformation due to thermal stresses, and / or the deviations of the geometric cylinder axis of the rolls from the operationally-setting rotation axes. The roll eccentricities are .DELTA.R with _O or .DELTA.R _U, ie as deviations from the ideal backup roll radius R ₀ or R _u denotes.

The measurement of the rolling speed n _o or n _{u of} the upper and lower support rollers 4 and 5 is used to determine the fundamental vibration of Walzenexzentrizitäten. Under the simplifying conditions that the upper and lower rollers of the roll stand 1 rotate at the same speed, it is sufficient to detect the speed of only one driven roller, eg the lower work roll 3, by means of a tachometer 11.

If, as in most cases, the back-up rolls 4 and 5 are the eccentric rolls, then in at least one conversion unit 14 or 12 the measured speed of the work roll 2 or 3 is determined by the ratio of the diameter of the work roll 2 or 3 Diameter of the support roller 4 or 5 in the speed n _o or n _{u of} the support roller 4 and 5 converted. As a rule, the speeds of the upper rollers 4, 2 and the lower rollers 5, 3 are different due to slightly different diameter, is in the shown

Embodiment both a tachometer 13 above the rolling stock 10 and a tachometer 11 below the Rolled material 10, each with a downstream conversion unit 14 or 12 for detecting the speed n _o or n _u provided.

The roll adjustment s is measured with a position sensor 9 on the adjusting device 7 or on the positioning system. The roller adjustment s is fed to a control device 18. For roller eccentricity identification and suppression, the control device 18 is supplied with at least one roller speed n _o or n _u . Furthermore, a Zugmessvorrich- device 8 for measuring the tensile force F _{z is provided in} front of the roll stand 1. The Zugmessvorrichtung 8, as indicated in FIG 1, have a measuring roller for tension measurement. This measuring roller may preferably be formed segmented. The Zugmess ^¬ device 8 may also be designed as a non-contact Zugmess- device. A corresponding device for non-contact measurement of the tensile force F _z in a rolling stock formed as a metal strip is described for example in DE 198 39 286 B4.

For the identification and / or suppression of roll eccentricities, the control device 18 has a process model 27. The process model 27 is based on an observer and models the behavior of the roll gap and the rolls. In this case, the process model 27 is frequency-controlled with the aid of the WaIz speed, ie, for example, with the aid of the determined roller speeds n _o or n _u . The time course of about model ^¬ lierenden interference is indeed periodic but not purely sinusoidal. This means that the vibration to be modeled consists of a fundamental vibration and several harmonics.

In the process model 27 sinusoidal correction target values assigned to the eccentricity frequencies are calculated for an actuator of the roll stand 1 with the appropriate phase position and amplitude for the position of the roll gap control. Advertising As shown in FIG 1, the correction reference values may have a tax advantage ^¬ direction 19 and possibly via a control valve 6 provided to the adjusting device 7 or to a screwdown the. By using the measured tensile force F _z, the required strip thickness, ie, the exit thickness h _a of the rolled stock 10 by means of the control device 18 is extremely uniform a ^¬ are provided. Thickness deviations caused by the roller eccentricity ΔR _O or ΔR _U can thus be avoided.

Alternatively or additionally, it is possible, for example by means of a pressure sensor 15, to measure the rolling force F _w and to take it into account in the identification and suppression of roller eccentricities.

By means of a thickness gauge 16 the thickness of, for example, the off-running ^¬ thickness h _a, are measured, alternatively or additionally to ^¬ the rolled stock 10.

2 shows schematically and exemplarily the ^¬ the identifi cation of roll eccentricities structure used in accordance with the observer principle. Here, a desired value s ^{* of} the Anstellpo ^¬ position both a real process 29, as it runs, for example, in one of a rolling stock 10 continuous rolling stand 1 ( ^see FIG 1), as well as an observer module 30 supplied. The observer module 30 has a process model 27, with the aid of which roll eccentricities can be identified and with the aid of which the identified roll eccentricities AR ₁ can be provided for compensation purposes. ^Below the aid of the process model 27, an identified outlet thickness h _ai can preferably be determined, which can be linked to the measured tensile force F _z to determine an observer error e. The measured tensile force F _z is first supplied to a module 21 in the measuring channel, which takes into account the transmission behavior of the outlet thickness to the strip tension inverse. With the aid of the module 21, the measured value of the tensile force F _z is thus converted to the outlet thickness and compared with the identified run-out thickness h _{ai determined} using the process model 27. The resulting from this comparison is the eighth error Obs ^¬ e. The states of the process model 27 are un ^¬ ter consideration of the observer error e as long as cor- yaws, join to measurement and model at least substantially over ^¬ and the observer error e is sufficiently small or zero. Then the ed in the process model 27 identifi ^¬ roll eccentricities AR ₁ match existing roll eccentricities with the fact in the rolling stand 1 (see FIG 1). The identified roller eccentricities AR ₁ thus determined by the observation module 30 enable extremely reliable and accurate eccentricity compensation.

As shown in the example shown in FIG. 3, a selection can be made as to whether the process model 27 should take into account the outlet thickness h _a , the rolling force F _w or the tensile force F _z in the identification of roll eccentricities.

FIG. 3 shows by way of example how the transfer behavior from the setting position to the strip tension can be taken into account when using the tensile force F _z for identifying and suppressing roll eccentricities. Thus, in the example gezeig- th preferably in the measuring channel, a module 21 hen vorgese ^¬ which up to the strip tension inversely taken into account the transmission characteristics of the outlet thickness. Preferably, the measured values of the tensile force F _{z are} linked to the corresponding transfer function H _Zug . This can be done, for example, by multiplication with a factor which corresponds to the inverse transfer function H _Zug . In addition, an adaptation circuit may be provided which takes into account the dependence on the belt speed v _B. Preferably, the present at the output of the module 21 value that was determined with the aid of the tensile force F _z is the Prozessmo ^¬ supplied dell 27th

As can also be seen in the example shown in FIG. 2, the process model 27 preferably simulates the behavior of the process 29 from the setting position s or from the setpoint value s ^{* of} the setting position to the outlet thickness h _a . If, alternatively or in addition to the tensile force F _z, the rolling force F _{w is to be} taken into account in the process model 27, then it is expedient to provide a module 28 in the measuring channel of the rolling force F _w , wel ^¬ ches having a suitable transmission characteristic.

4 shows an example of the use of an inlet thickness compensation in connection with the method according to the invention. In this case, a Dickenmessgeber 17 is provided in front of the roll stand, by means of which a measured inlet thickness h _{em is} detected. The shown inlet thickness compensation module 22 has a tape tracking module 23. By means of the belt tracking module 23, the measured inlet thickness h _{em is} traced to the mill stand 1. With the aid of the inlet ^¬ speed V _SE is a wegverfolgte inlet thickness h _ev determined. The tape tracking module 23 preferably operates model-based.

In the example shown, the inlet ^thickness compensation module 22 has at least one compensation model 24, 25, 26 with the aid of which the influence of the inlet thickness h _e on the outlet thickness h _{a is} determined as _a function of the measured variable m _E or the corresponding measured value , Since the quality of the run-in thickness compensation substantially from the one or more compensation models used 24, 25, depends 26, in the illustrated example, a compensation model 24 for the USAGE ^¬ extension of the exit thickness h _a as a measured variable m _E, a compensation modeil 25 for use of the rolling force F _w as a measured variable m _E and a compensation model 24 for the use of the train ^¬ force F _z as the measured variable m _E provided. The compensation signal given by the inlet thickness compensation module 22 is linked to the corresponding measured value of the measured variable m _E to form a compensated measured variable m _K.

An essential idea underlying the invention can be summarized as follows:

The invention relates to a method for suppressing the

Influence of rolling eccentricities on the outlet thickness h _{a of} a rolling stock 10, which passes through a roll stand 1, where ^¬ in roll eccentricities using a process model dells 27 are identified and taken into account in the determination of a correction signal for at least one actuator, preferably an actuator for the setting position of the roll stand 1, wherein the process model 27, the measured tensile force F _z is fed before the rolling stand 1 to identify the roller eccentricities. According to ^¬ the tension variations targeted to reduce the effects of periodic roll eccentricities on the rolling stock 10 is returned, whereas all other sources of variation are excluded. This is based on the observer principle process model testifies 27 of the nip and the rolls he ^¬ such activities with the aid of the measured tensile force F _z, the roll adjustment s and the rolling speed and the rolling speed, reliable data on the Walzenexzentrizi-. According to the invention, predetermined dimensions of the rolling stock 10 are achieved more uniformly than hitherto. Tensile measuring devices 8 work very accurately and dynamically in comparison to measuring devices for the thickness h _e or h _{a of} the rolling stock 10 and compared to measuring devices for the rolling force F _w . Preferably, the information contained in the tensile force fluctuation and roll eccentricity caused by the perio ^¬ sized vibration components are specifically used to reduce the exzent ^¬ rizitätsbedingten, undesired change in thickness in the rolling stock 10th On fluctuation parts with other frequencies not equal to the eccentricity frequencies is not reacted.

Stemming from the entry thickness periodic Dickenschwankun ^¬ gen with frequencies that are almost the same frequencies the Exzentrizitätsfre ^¬, the identification of the Walzenexzentrizi- can interfere with activities. Therefore, it is possible to provide an inlet thickness compensation which determines and compensates for the influence of the inlet thickness fluctuations on the measured variable m _{E used} and thus eliminates this type of disturbance.

Due to their limited dynamics, the tension regulators present in known control concepts of a rolling train designed, for example, as a tandem mill can only be used at low rolling speeds and only at the front stands Avoid a part of the thickness caused by the eccentricities. An inventively designed control device 18 for suppressing the influence of rolling eccentricities, which is fed to the rolling stock 10 measured tensile force F _z , can take on a rolling ^¬ scaffold 1, the compensation of the eccentricity frequencies and thus completely relieve conventional tension regulator.

Claims

claims 1. A method for suppressing the influence of roll eccentricities to the outlet thickness (h _a) a rolled stock (10) which passes through a roll stand (1), wherein Walzenexzentri ^¬ capacities using a process model (27) identifi ^¬ be decorated, and in the determination of a Correction signal for at least one control device (19) for an actuator of the roll stand (1) are taken into account, characterized in that for the identification of Walzenexzentrizitäten the at least one process model (27) Mess ^¬ values of the tensile force (F _z ) are supplied. 2. The method according to claim 1, wherein the tensile force (F _z ) in front of the roll stand (1) is measured. 3. The method according to claim 1 or 2, wherein a model is used, which describes the transmission behavior of the Anstellposition to Bandzug. 4. The method according to any one of claims 1 to 3, wherein a model is used with observer structure. 5. The method according to any one of claims 1 to 4, wherein measured values of the tensile force (F _z ) a module (21) fed ^¬ who, which takes into account the transmission behavior of the outlet thickness to the strip tension inverse. 6. The method according to claim 4 or 5, wherein the depen- is Untitled dependence on the tape speed (v _B) into account adaptively ^¬. 7. The method according to any one of claims 1 to 6, wherein the process model (27) describes at least the roll gap and the rolls of the roll stand (1). 8. Method according to one of the claims 1 to 7, wherein an inlet thickness compensation of the measured values m _E used for the identification of the roller eccentricities takes place. 9. Computer program product comprising program code means ge ^¬ suitable for performing all the steps of a method according to one of the preceding claims, when the computer program product is executed on a data processing system.