DE102009043401A1 - Method for the model-based determination of actuator setpoints for the symmetrical and asymmetric actuators of the rolling mills of a hot strip mill - Google Patents

Abstract

The invention relates to a concept for the model-based determination of actuator target values for the symmetrical and asymmetrical actuators of the rolling stands of a hot strip mill, with which a desired target contour of the roll gaps of the stands can be set when executing the actuator target values. In a first step, a target speed distribution is specified at the exit of each stand. In a second step, strip flatness models are used to determine strip thickness contours at the outlets of the stands. In a third step, the rolling force distributions to be applied to each stand are determined with the help of material flow models. In a fourth step, a target contour for the symmetrical actuators and a target contour for the asymmetrical actuators are determined. In a fifth step, the target values for the symmetrical and asymmetrical actuators are calculated for each stand with the aid of optimization methods from the determined target contours.

Description

The invention relates to a concept for a model-based stripline control for a hot strip mill, in particular a finishing train.

A hot strip mill, in particular a finishing train, comprises several of a strip to be rolled, typically a metal strip such as a steel, aluminum, copper or generally a non-ferrous metal strip, successively passed rolling stands G ₁ , G ₂ , G ₃ , ... G _n , whereby it can be achieved by means of conventional control methods that the rolled strip has a desired final temperature and a desired final thickness. Other relevant parameters for assessing the rolling quality are, for example, the profile, the contour and the flatness of the strip. In this context, the DE 102 11 623 A1 in which some of the relevant basic concepts are described in detail. The most important terms are redefined here. The "band profile" or the "profile value" of the band indicates the deviation of the band thickness at the band edges from the band thickness in the band center. The term "tape thickness contour" is understood to mean the strip thickness profile over the strip width minus the strip thickness in the middle of the strip. The strip thickness contour can be split into one with respect to the center of the band symmetric and an asymmetric portion. The asymmetric portion is called "band thickness wedging". The term "flatness" is used synonymously with the internal stresses prevailing in the strip, regardless of whether or not these internal stresses lead to visible distortions of the metal strip.

The strip, always viewed relative to a rolling line centerline, is fed into each of the rolling stands G _i (i = 1, ..., n) with a known respective center offset with respect to the center of the frame (at z = 0) and with a known respective entry side strip thickness. Threaded wedging, so that the tape or the head of the tape from the respective rolling stand with the respective center offset, a respective outlet side strip thickness wedge and a respective outlet side strip curvature expires.

When rolling a belt, internal stresses can be "rolled in" into the belt. Depending on the strip thickness, the band width, the material properties of the strip and the possibly acting on the strip outer tensile stresses cause these internal stresses to more or less pronounced band deformations such as. Wave or saber formation. One of the major causes of "rolling in" intrinsic stresses in a rolling stand is a non-negligible band-thickness wedging of the belt entering the skeleton. The strip thickness wedging can have various causes. For example, the strip may already have a wedge-shaped strip thickness contour prior to rolling. Alternatively, the strip thickness taper may have been caused by rolling in the nip of an upstream stand. For stamping a strip thickness wedge into the strip during material conversion in a rolling stand, several causes are possible. For example, the tape may have a temperature gradient across the tape, the tape may enter the nip off-center, or the nip itself may be wedge-shaped. Also combinations of these (and other) causes are possible.

Thus, if a hot strip with a non-vanishing strip thickness and / or off-center enters a stand G _i , the strip shape in the following intermediate stand section between the stands G _i and G _{i + 1 will} generally not be straight but saber-shaped. The saber-shaped course depends on whether the tape is clamped on one side only in a framework (when threading or unthreading from the framework) or on both sides of two successive stands (when rolling the main part of the tape, ie with the exception of tape head and strip foot). The influence of the band coating to the saber shape and thus on the tape and the tape position, that in particular the variation of the tape position from the center position is clearly easy to understand: Considering a band edge of an expiring of a framework G _i band and assuming that the rate of plastic material flow at this band edge is less than that at the other band edge, it is clear that the ribbon will be inhomogeneous across the bandwidth as soon as the next frame G _{i + 1} reaches. In particular, the strip tension is higher on the considered "shorter" strip edge. The higher strip tension causes a greater decrease in the thickness of the strip at this strip edge and thus an increase in the speed of the plastic material flow at this edge. The velocity wedge of the plastic material flow over the bandwidth is reduced; the inter-frame stresses have a stabilizing effect on the strip run within the finishing train.

Actuators on the individual stands G _{i of} the rolling train are used for the strip running control, which influence the shape of the roll gap - and thus the strip thickness profile - asymmetrically with respect to the center of the frame or the center of the strip. Such actuators are, for example, pivoting and asymmetric bending forces. Furthermore, symmetrical actuators are provided, for example. Symmetrical bending forces, means for the axial displacement of so-called. CVC work rolls (rolls with S-shaped cut) and / or so-called. "Pair crossing". These symmetrical actuators are used for profile and flatness control. An automatic, model-based method or a Device for profile and flatness control is in DE 102 11 623 A1 disclosed.

In the prior art, for example, it is also known that a helmsman of the rolling train when threading the tape visually tracks the tape head and - according to his personal impression of tape position and tape waviness - the employment of the tape head just traversed mill stand (in particular a pivoting position of the rollers) sets ,

It is the object of the present invention to provide a control method and a control device for a stripline control of a rolling mill having a plurality of stands, in particular a hot strip mill or finishing train.

This object is achieved by the inventions specified in the independent claims. Advantageous embodiments emerge from the dependent claims.

In the solution according to the invention, a concept of a complete, model-based control method for the stripline control and for the profile and flatness control of the rolling mill is presented, with which simultaneously the nominal values of the asymmetrical rolling mill actuators for the stripline control in a first partial method and the nominal values of the symmetrical rolling mill -Stellglieder for the profile and flatness control in a second sub-procedure can be calculated. The two sub-procedures are coordinated.

_According to the invention, an iterative method for model-based determination of actuator target values SET _sym , SET _asym for symmetrical and asymmetric actuators of a hot strip mill having a plurality of rolling stands G _i with i = 1,..., N and n ≥ 2 is proposed for rolling a hot strip wherein each rolling mill G _i having a nip with a roll gap contour and the actuators act on such rolls of the stand G _i that a certain roll gap contour is adjustable. A method cycle k of the iterative method comprises the following steps:

• 1) In a first step, a desired velocity distribution v _{i, soll} (z; k) is set at the outlet of each gantry G _i .
• 2) In a second step, strip thickness contours θ _i (z; k) are determined at the outlets of the stands G _i , where 2.1) first using band flatness models for each gantry G _i a velocity distribution v _i (z; k) at the respective Out of the framework G _{i is} calculated, wherein each frame G _{i is assigned} a band flatness model and wherein in the band flatness model a band thickness contour θ _i-1 (z; k) of the band at the inlet and a band thickness contour θ _i (z; k) of the band at the outlet of respective stand G _i are taken into consideration, 2.2) then the calculated velocity distributions v _i (z k) by the predetermined first step target velocity distributions v _{i, to} be compared (k), 2.3) the strip thickness contours θ ₁ (z; k) to θ _n-1 (z; k) are modified if the calculated velocity distributions v _i (k) are not within a tolerance range around the desired velocity distributions v _{i, soll} (k) and then m or if the calculated velocity distributions v _i (k) are within the tolerance range around the desired velocity distributions v _{i, soll} (k).
• 3) In a third step, rolling force distributions f _i (z; k) to be applied for each gantry G _i are determined with the aid of material flow models, with each material gantry G _{i being assigned} a material flow model.
• 4) In a fourth step, a target contour H _i (z; k) for the symmetrical actuators and a target contour K _i (z; k) for the asymmetric actuators is determined, for each framework G _i 4.1) first from the rolling force distributions f _i (z; k) a flattening Δ _i (z; k) of the rolls in the frame G _{i is} calculated on the basis of a work roll flattening model, 4.2) a residual strip thickness profile Ω _i (z; k) is calculated by the flattening Δ _i (z; k) is subtracted from the respective strip thickness contour θ _i (z; k) determined in the second step at the outlet of the stand G _i , 4.3) the symmetrical target contour H _i (z; k) is calculated by calculating from the residual Band thickness profile Ω _i (z; k) an asymmetrical portion of the residual band thickness profile is masked out, the target contour H _i (z; k) corresponding to the remaining portion of the residual band thickness profile, 4.4) the asymmetrical target contour K _i (z; k) is calculated by from the residual band thickness profile Ω _i (z; k) a symme trischer portion of the residual band thickness profile is hidden, wherein the target contour H _i (z; k) corresponds to the remaining proportion of the residual strip thickness profile.
• 5) In a fifth step, the setpoint values for the symmetrical actuators from the target contour H _i (z; k) are determined for each framework G _i by means of optimization methods in a first substep and in a second substep the setpoint values for the asymmetrical actuators from the target contour K _i (z; k) are calculated.

Advantageously, in the first step, setpoints v (1) / i, should . v (2) / i, should For v (1) / i and for v (2) / i given that it is assumed that for a velocity distribution v _i (z) holds v _i (z) = v (1) / i * z + v (2) / i * z ² + O (z ³ ) , in which v (1) / i the material flow wedging and v (2) / i is a material flow coefficient, which is a measure of strip flatness. In the second step these setpoints become v (1) / i, should . v (2) / i, should with the corresponding calculated values v (1) / i . v (2) / i compared.

• – eine Außermittigkeit d_i–1 des Bandes vor jedem Gerüst G_i und die Außermittigkeit d_n des Bandes nach dem letzten Gerüst G_n gemessen,
• – die Banddickenkontur θ_n(z; k) nach dem letzten Gerüst G_n gemessen,
• – die Banddickenkontur θ₀(z; k) vor dem ersten Gerüst G₁ ermittelt, insbesondere durch Messung oder Schätzung,
• – die Bandplanheit s_n(z; k) des Bandes (10) nach dem letzten Gerüst G_n gemessen.

In the first step, first:

• An eccentricity d _{i-1 of} the band before each gantry G _i and the eccentricity d _{n of} the band after the last gantry G _{n are} measured,
• The band thickness contour θ _n (z; k) is measured after the last framework G _n ,
• The strip thickness contour θ ₀ (z; k) is determined before the first stand G ₁ , in particular by measurement or estimation,
• The band flatness s _n (z; k) of the band ( 10 ) measured after the last framework G _n .

In addition, in the second step, the desired speed distributions v _{i, soll} (z; k) to be preset are calculated in a control loop

• - the desired velocity distributions v _{i, soll} (z, k-1) and the measured values for the eccentricity d _i-1 (k-1), for the band thickness contour θ _n (z; k-1) and for the band flatness s _n (z; k - 1) from the previous cycle k - 1 as well
• The measured values for the eccentricity d _i-1 (k), for the band thickness contour θ _n (z; k) and for the band flatness s _n (z; k) from the current cycle k.

• – Außermittigkeits-Messwert d_i(k) am Einlauf des Gerüsts G_i,
• – angenommene, berechnete oder gemessene Bandzüge am Einlauf sowie am Auslauf des Gerüsts G_i,
• – Banddickenkonturen θ_i–1(z; k) und θ_i(z; k) am Einlauf und Auslauf des Gerüsts G_i,
• – Bandzüge am Einlauf und Auslauf des Gerüsts G_i,
• – angenommene oder berechnete Geschwindigkeitsverteilung v_i–1(z; k) am Einlauf des Gerüsts G_i,
• – gemessene Walzkraft f_i(z; k) im Gerüst G_i,
• – Sollwerte für Bandbreite, Eintrittsdicke in der Bandmitte und Abnahme des Warmbandes (10) im Gerüst G_i.

Specifically, in the second step, the following data is supplied to the band flatness model assigned to the frame G _i :

• - external measurement value d _i (k) at the inlet of the framework G _i ,
• - assumed, calculated or measured strip tension at the inlet and at the outlet of the gantry G _i ,
• Band thickness contours θ _i-1 (z; k) and θ _i (z; k) at the inlet and outlet of the framework G _i ,
• Bandgaps at the inlet and outlet of the gantry G _i ,
• Assumed or calculated velocity distribution v _i-1 (z; k) at the inlet of the framework G _i ,
• Measured rolling force f _i (z; k) in the framework G _i ,
• - nominal values for bandwidth, entrance thickness in the center of the strip and decrease of the hot strip ( 10 ) in the framework G _i .

In the third step, the same data will be fed to the material flow models as the band flatness models. In addition, the input variables of the material flow models are friction parameters R, which describe the friction ratios in the longitudinal and transverse direction in the roll nip.

• – a_i(z; k) eine anfängliche Kontur der Arbeitswalzen darstellt,
• – b_i(z; k) eine aktuell berechnete thermische und Verschleiß-Balligkeit darstellt,

und wobei in der folgenden Teilschritten des vierten Schrittes das so korrigierte Rest-Banddickenprofil Ω_i,korr(z; k) zur Ermittlung der Zielkonturen H_i(z; k), K_i(z; k) verwendet wird.In the fourth step, after the partial step 4.2), a corrected residual strip thickness profile Ω _{i, corr} (z; k) is first calculated by additionally applying correction values a _i (z; k) from the residual strip thickness profile Ω _i (z; b _i (z; k) are subtracted, where

• A _i (z; k) represents an initial contour of the work rolls,
• - b _i (z; k) represents a currently calculated thermal and wear crown,

and wherein in the following substeps of the fourth step, the thus corrected residual band thickness profile Ω _{i, corr} (z; k) is used to determine the target contours H _i (z; k), K _i (z; k).

In the fifth step, the first and the second substep are carried out independently of each other and in parallel with each other.

Furthermore, a computer program product according to the invention for carrying out the method according to the invention is proposed and a control computer programmed for the computer program product for a rolling train with at least two rolling stands G _i .

Compared with a non-model-based control and in particular with respect to two individual, non-coordinated (partial) method for the tape travel control and for the profile and Panheitssteuerung arise with the inventive solution bpsw. the advantages that, after successful piloting of a plant for downstream plants, shorter commissioning and service times are required and that a better extrapolability to a new product range is possible. Furthermore, no or only minimal interactions between the two control target variables "strip running" and "profile and flatness" are to be feared.

Further advantages, features and details of the invention will become apparent from the embodiment described below and with reference to the drawings.

Showing:

1 a schematic representation of a multi-stand rolling train

2 a schematic representation of the rolling mill to illustrate the second process step,

3 a schematic representation of the rolling mill to illustrate the third process step,

4 a schematic representation of the rolling mill to illustrate the fourth process step,

5 a schematic representation of the rolling mill to illustrate the fifth process step.

In the figures, identical or corresponding areas, components, component groups or method steps are identified by the same reference numerals.

The 1 shows a side view and a section of a rolling train 1 with a band to be rolled there 10 and a plurality of rolling stands G _i (i = 1, 2, ... n). In the example shown, the rolling train is to have n stands, of which only the first two stands G ₁ , G ₂ and the last two stands G _n-1 and G _n are shown.

According to 1 becomes a rolling mill 1 for rolling a metal strip 10 from a control computer 2 controlled. The operation of the control computer 2 is doing by a computer program product 2 ' set with which the control computer 2 is programmed.

The following is based on a Cartesian coordinate system, wherein the x-axis of the coordinate system of the direction of the tape 10 corresponds to the y-axis, the band thickness direction and the z-axis in the direction across the band 10 or in the direction of the longitudinal axes of the rollers 21i the frameworks G _i is oriented. The center of the roll or frame is z = 0. The strip 10 will be in the rolling mill 1 rolled in a rolling direction x. Each framework G _i has at least work rolls 21i and possibly (in 1 but not shown) also support rollers on.

From the control computer 2 become scaffold controllers 30i , wherein each framework G _{i is} a scaffold regulator 30i is provided, setpoints for only in the 1 indicated asymmetric and symmetrical actuators 22i or "actuators" given, which ultimately on the rollers 21i act and so realize the desired target shape or contour of the respective roll gap. The scaffold controllers 30i regulate the actuators 22i according to the predetermined setpoints. The basic interaction between the actuators 22i Actuators, the rollers and the resulting nip can be assumed to be known.

Due to the target values, an outlet-side nip course is influenced per rolling stand G _i , which is located between the work rolls 21i - In interaction with the metal strip located between the work rolls - sets. The outlet-side roll gap course corresponds to an outlet-side contour of the strip 10 , The setpoints for the actuators 22i must therefore be determined in such a way that the roll gap profile, which corresponds to the desired outlet side strip thickness contour, results.

To determine the setpoints for the actuators 22i be the tax calculator 2 Input variables supplied, which are explained below in connection with the five individual steps 1) to 5) of the method according to the invention. The control computer 2 thus determines the setpoint values from the input variables supplied to it.

The strip thickness contour θ (z), which, depending on the position z, the thickness of the strip 10 , ie its extension in the y-direction, minus the band-central thickness, can be approximated with the exception of the band edges to a good approximation by a polynomial of the second degree: θ (z) = θ ⁽⁰⁾ + θ ⁽¹⁾ · z - θ ⁽²⁾ · z ² (Eq. 1)

The coefficient θ ^{(1) describes} the wedging of the band 10 or the strip thickness contour.

Furthermore, the band thickness contour at the inlet of the gantry G _i is denoted by θ _i-1 (z) and at the outlet of the gantry G _i by θ _i (z) (with 1 ≤ i ≤ n).

At the outlet of a scaffold G _i , the plastic material flow of the band 10 in the rolling or strip running direction, a certain velocity profile v _i (z) over the bandwidth z, which (neglecting the average belt speed in the rolling direction) can be approximated by a polynomial without a constant term: V _i (z) = v (1) / i * z + v (2) / i * z ² + O (z ³ ) (equation 2)

The coefficient v (1) / i describes a speed wedge or a material flow wedging, the saber formation of the tape described in the introduction 10 leads while the coefficient v (2) / i a measure of the flatness or unplanarity of the volume 10 is. It corresponds v (2) / i> 0 Edge waves while v (2) / i <0 Center waves means.

Furthermore, let a deviation of the center of the strip in the z-direction from the center of the roll or frame at z = 0 immediately before a stand i be designated by d _i-1 .

A calculation cycle k of the iterative method according to the invention has five individual steps 1) to 5), which, for example, with the aid of a computer program on the control computer 2 (in the figures, the parameters "k" and "z " used in the following are not shown for the sake of clarity):

Step 1)

• – die Außermittigkeit d_i–1 des Bandes 10 vor jedem Gerüst G_i (mit i = 1, ..., n) sowie die Außermittigkeit d_n des Bandes nach dem letzten Gerüst G_n,
• – die Banddickenkontur θ_n(z) nach dem letzten Gerüst G_n und
• – die Bandplanheit s_n(z) des Bandes 10 nach dem letzten Gerüst G_n.

Measurements or measured value evaluation and setpoint specification for the material flow velocity distribution v _i (z), wherein for each gantry G _i both the material flow wedges v (1) / i as well as the quadratic material flow coefficients v (2) / i , which are a measure of the band flatness, can be determined (cf. 1 ):
Measured with the help of appropriate sensors or transducers (not shown)

• - the eccentricity d _{i-1 of} the band 10 before each framework G _i (with i = 1, ..., n) and the eccentricity d _{n of} the band after the last framework G _n ,
• - The band thickness contour θ _n (z) after the last frame G _n and
• - the band flatness s _n (z) of the band 10 after the last framework G _n .

The eccentricity d _{i-1 of} the band 10 before each scaffold G _i is preferably measured optically, z. B. by means of a laser or camera system. For the measurement of the eccentricity d _{n of} the strip after the last stand G _n no additional measuring device is required, because this size can be determined by means of the (usually traversing) strip thickness contour measuring device after the last stand.

In addition, the tape thickness contour θ ₀ (z) in front of the first gantry G _{1 is} either measured on-line, or estimates are used for θ ₀ (z) based, for example, on isolated offline or hand measurements.

Given at the outlet of each scaffold G _i (i = 1, ..., n) in each cycle k a (new) target velocity distribution is in the first calculation step of the implemented in the computer program control algorithm v _{i, soll} (k z) ,

The desired velocity distribution v _{i, soll} (z; k) is calculated in a control loop from the preceding desired velocity distributions v _{i, soll} (z; k-1), the measured values from the preceding cycle k-1 for the eccentricity d _{i- 1} (k-1), the strip thickness contour θ _n (z; k-1) and the flatness s _n (z; k-1) and from the current measured values from the current cycle k.

For the first cycle (k = 1) can be called "start values" v (1) / i, shall (0) , d _i-1 (0) and d _i (0), for example, the values still known from the rolling process of a previously rolled strip are used. Alternatively, too v (1) / i = d _i-1 (0) = d _i (0) = p where p may be any number including p = 0.

Step 2)

In step 2, the calculation of set values for the inter-frame strip thickness contours θ _i (z; k) takes place, wherein both the strip thickness wedges θ (1) / i (k) as well as the band profile coefficients θ (2) / i (k) are determined after each framework G _i (cf. 2 ):
Here, suitable setpoint values for the strip thickness contours θ _i (z; k), i = 1,..., N-1, at the outlets of the stands G _i , i = 1,..., N-1, are calculated. Using a physical band flatness model 40i (or a look-up table of a band flatness model), for each gantry G _i, the velocity distributions v _i (z) (see equation 2) are calculated at the outlets of the gantries G _i , each gantry G _i a model 40i assigned. The models 40i as well as other models used in the following are implemented in the computer program.

In the model 40i it is an extension of the in the DE 102 11 623 A1 described there and referred to as "flatness estimator" model or its approximation function with additional consideration of asymmetric effects.

• – Außermittigkeits-Messwerte d_i(k) am Einlauf des Gerüsts G_i,
• – angenommene, berechnete oder gemessene Banddickenkonturen θ_i–1(z; k) und θ_i(z; k) am Einlauf und Auslauf des Gerüsts G_i,
• – angenommene, berechnete oder gemessene Bandzüge am Einlauf und Auslauf des Gerüsts G_i,
• – angenommenes oder berechnetes Geschwindigkeitsprofil v_i–1(z; k) am Einlauf des Gerüsts G_i,
• – gemessene Walzkraft im Gerüsts G_i,
• – Rechen- bzw. Sollwerte für Bandbreite, Eintrittsdicke (in der Bandmitte) und Abnahme im Gerüst G_i.

The model assigned to the framework G _i 40i the following data are supplied:

• - external measurement values d _i (k) at the inlet of the framework G _i ,
• Assumed, calculated or measured strip thickness contours θ _i-1 (z; k) and θ _i (z; k) at the inlet and outlet of the gantry G _i ,
• - assumed, calculated or measured strip tension at the inlet and outlet of the gantry G _i ,
• Assumed or calculated velocity profile v _i-1 (z; k) at the inlet of scaffold G _i ,
• Measured rolling force in the framework G _i ,
• - Calculation or setpoint values for bandwidth, entrance thickness (in the middle of the tape) and decrease in the framework G _i .

The velocity distribution v ₀ (z), the band flatness model 401 of the first skeleton G ₁ , can not be measured as a rule and is assumed to be v ₀ (z) = 0.

By means of the models 40i and the above-mentioned input data becomes k in each cycle k 2 the velocity distributions v _i (z; k) are calculated at the outlets of the stands G _i and in a logic unit 41 with the in step 1 ) determined target velocity distributions v _{i, soll} (z; k) are compared. In this comparison, in particular, the material flow wedges v (1) / i and the square material flow coefficients v (2) / i the setpoint values from the first step and the calculated values from the second step are compared with one another.

In the event that this comparison shows that the computational values for the velocity distributions v _i (z; k) are not within a tolerance range, ie between a maximum and a minimum value, around these nominal values, the band thickness contours θ ₁ (z) to θ _n-1 (z; k) until the comparison gives a sufficient match.

In the event that the comparison reveals that the calculated values for the velocity distributions v _i (z; k) are actually within the tolerance range around the target values, the method goes to step 3), where the band thickness contours θ _i determined in the context of the described comparison. z; k) continue to be used.

Step 3)

Calculation of the rolling force distribution f _i over the bandwidth for each framework G _i (cf. 3 ):
Each framework G _i is a physical material flow model 50i (or an approximation function (look-up table) of such a material flow model) that has the same data as the model 40i in step 2). Additionally receives the material flow model 50i as input quantities of one unit 51 Friction parameters R, which describe the different friction ratios in the longitudinal and transverse direction in the roll gap.

The friction parameters R are model adaptation parameters that are determined so that the overall algorithm predicts the measured strip thickness contour and the measured strip flatness after the last stand as well as possible.

The material flow models 50i model the physical behavior of the tape 10 in the nip of the framework G _i .

As in step 2), ₀ (z) = 0 is also assumed here for the velocity profile in front of the first framework v.

With the help of material flow models 50i in each case the rolling force distributions f _i (z; k) are determined on the basis of the input data listed above. The respective material flow model 50i determines for a gantry G _i the line load distribution f _i (z; k) between belt and work rolls. The integral of f _i (z; k) over the bandwidth gives the rolling force in the framework G _i .

The main uncertainty in the modeling of the material flow in the roll gap lies in the friction conditions in the roll gap, both in the rolling direction and transverse to the rolling direction. The friction parameters R are therefore the main model adaptation parameters.

Step 4)

Calculation of the target contour for the symmetrical and asymmetric band thickness contour actuators 22i for each framework G _i (cf. 4 ):
The 4 Figure 3 shows the further processing of the rolling force distributions f _i (z; k) determined in step 3) of the cycle k, with the aim of determining the target contours for the symmetrical and the asymmetrical band thickness contour actuators. The rolling force distributions are calculated for each framework G _{i of} a computing unit assigned to the framework G _i 70i supplied in the basis of a work roll flattening model 71i the flattening Δ _i (z; k) of the work rolls in the framework G _i associated with the rolling force distributions f _i (z; k) is calculated.

This flattening Δ _i (z; k) is performed in a subtractor 72i the arithmetic unit 70i subtracted from the strip thickness contour θ _i (z; k) at the outlet of the stand G _i , ie in the subtractor 72i a residual band thickness profile Ω _i (z; k) = θ _i (z; k) -Δ _i (z; k) is calculated. From this residual band thickness profile can be found in further subtractors 73i and 74i Correction values a _i (z; k), b _i (z; k) are deducted, where a _i (z; k) is the initial contour of the work rolls (ie, the finish) and b _i (z; k) is the current calculated thermal and Wear-crowning of the framework G _i describes. When calculating the quantities a _i (z; k) and b _i (z; k), the current eccentricity d _i (k) of the band is taken into account.

The result of the subtractor 74i ie, the corrected residual band thickness contour Ω _{i, corr} (z; k) is split into a symmetric component H _i (z; k) and an asymmetric component K _i (z; k) by a logic unit 75i the asymmetric portion of the corrected residual band thickness contour Ω _{i, corr} (z; k) is masked out so that only the symmetrical portion H _i (z; k) remains while in a logic unit 76i the asymmetric portion of the corrected residual band thickness contour is hidden.

The remaining band thickness contours are the target contours H _i (z; k), K _i (z; k), which are symmetrical and asymmetric 22i are to be adjusted.

Step 5)

Calculation of the setpoint values for the stripline actuators 22i (see. 5A . 5B ):
The fifth step is subdivided into two analogous sub-steps 5a and 5b : In sub-step 5a On the basis of H _i (z; k), the nominal values SET _{sym of} the (symmetrical) profile and flatness actuators are calculated for each gantry G _i . In partial step 5b On the basis of K _i (z; k), the set values SET _{asym of} the (asymmetrical) _{strip running} actuators are determined for each stand G _i .

In this case, for each framework G _i, for example, with the aid of a so-called "least squares" optimization 100 (Least squares method) from the target contours H _i (z; k), K _i (z; k), taking into account the technical, physical actuator limitations LIM _sym and LIM _{asym of} the symmetrical and asymmetric tape drive actuators, respectively 22i the correct actuator values are calculated, which ultimately determines the stripline actuators 22i of the gantry G _i . Possibly. You can still make corrections to the setup you have determined 101 , for example, also manual way to be added.

In the event that a plurality of independent tape drive actuators are present for a framework, for example. Panning and asymmetric bending, in the optimization step 5, the optimum combination of these actuators can be determined.

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Cited patent literature

• DE 10211623 A1 [0002, 0006, 0049]

Claims (10)

Iterative method for model-based determination of actuator setpoints (SET _sym , SET _asym ) for symmetrical and asymmetric actuators ( 22i ) of a hot strip mill ( 1 ) with several rolling stands G _i with i = 1,..., n and n ≥ 2, for rolling a hot strip ( 10 ), wherein each roll stand G _i has a roll gap with a roll gap contour and the actuators ( 22i ) on rollers ( 21i ) of the stand G _i act, that a certain roll gap contour is adjustable, in which in a process cycle k (k = 1, 2, ...): 1) in a first step, a desired velocity distribution v _{i, soll} (z; k ) is set at the outlet of each scaffold G _i, 2) in a second step the strip thickness contours θ _i (z k) to the bleeding of the scaffolds G _i, i = 1, ..., n - 1, are determined, 2.1 ) first with the help of band flatness models 40i for each gantry G _i, a velocity distribution v _i (z; k) is calculated at the respective outlet of the gantry G _i , wherein each gantry G _{i is} a band flatness model 40i and where in the band flatness model 40i a band thickness contour θ _{i_1} (z; k) of the band ( 10 ) at the inlet and a band thickness contour θ _i (z; k) of the hot strip ( 10 ) Are taken into account at the outlet of respective stand G _i, 2.2) then the calculated velocity distributions (v _i (z k)) with the predetermined first step target velocity distributions (v _{i, to} be compared (k)), 2.3) the Band thickness contours θ ₁ (z; k) to θ _n-1 (z; k) are modified if the calculated velocity distributions (v _i (k)) are not within a tolerance range around the desired velocity distributions (v _{i, soll} (k)) and then with the modified strip thickness contours the second step is carried out again or 2.4) is moved to the third step, if the calculated velocity distributions (v _i (k)) within the tolerance range around the desired velocity distributions (v _{i, soll} (k) ), 3) in a third step using material flow models 50i for each framework G _i to be applied rolling force distributions f _i (z; k) are determined, each framework G _i a material flow model 50i 4) in a fourth step, a target contour H _i (z; k) for the symmetrical actuators and a target contour K _i (z; k) for the asymmetric actuators is determined, wherein for each framework G _i 4.1) first of the Rolling force distributions f _i (z; k) by means of a work roll flattening model ( 71 ) A flattening Δ _i (z k) of the rolls is calculated in the frame G _i, 4.2) a residual strip thickness profile Ω _i (z k) is calculated by the flattening Δ _i (z k) by the respective, in is withdrawn at the outlet of the scaffold G _i 4.3), the symmetrical target contour H _i (z, k) is calculated by (from the residual strip thickness profile Ω _i z;; second step determined strip thickness contour θ _i (k z) k) an asymmetric proportion of the residual strip thickness profile will disappear, wherein the target contour H _i (z k) corresponds to this remaining portion of the residual strip thickness profile, 4.4) the asymmetric target contour K _i (z k) is calculated by from the residual strip thickness profile Ω _i (z; k) a symmetrical portion of the residual band thickness profile is masked out, the target contour H _i (z; k) corresponding to the remaining portion of the residual band thickness profile, 5) in a fifth step for each gantry G _i with the aid of Optimization method ( 100 ) in a first sub-step, the setpoint values for the symmetrical actuators from the target contour H _i (z; k) and in a second sub-step the setpoint values for the asymmetric actuators from the target contour K _i (z; k) are calculated. A method according to claim 1, characterized in that for a velocity distribution v _i (z) holds v _i (z) = v (1) / i * z + v (2) / i * z ² + O (z ³ ) , in which v (1) / i the material flow wedging and v (2) / i is a material flow coefficient, which is a measure of the band flatness, and wherein - in the first step, setpoints v (1) / i, should . v (2) / i, should For v (1) / i and for v (2) / i be specified and - in the second step, these setpoints v (1) / i, should . v (2) / i, should with the corresponding calculated values v (1) / i . v (2) / i be compared. Method according to claim 1 or 2, characterized in that in the first step - an eccentricity d _{i-1 of} the strip ( 10 ) in front of each framework G _i and the eccentricity d _{n of} the band ( 10 ) is measured after the last stand G _n , - the tape thickness contour θ _n (z; k) is measured after the last stand G _n , - the tape thickness contour θ ₀ (z; k) is determined before the first stand G ₁ , in particular by Measurement or estimation and - the band flatness s _n (z; k) of the band ( 10 ) is measured after the last framework G _n , and the desired speed distributions v _{i, soll} (z; k) to be given are calculated in a control loop from the desired speed distributions v _{i, soll} (z; k-1) and the measured values for the eccentricity d _i-1 (k-1), for the band thickness contour θ _n (z; k-1) and for the band flatness s _n (z; k-1) from the preceding cycle k-1 and the measured values for the eccentricity d _i-1 (k), for the band thickness contour θ _n (z; k), and for the band flatness s _n (z; k) from the current cycle k. A method according to claim 2 or 3, characterized in that in the second step to the framework G _i associated band flatness model 40i the following data are supplied: - eccentricity measured value d _i (k) at the inlet of the gantry G _i , - assumed, calculated or measured strip tension at the inlet and at the outlet of the gantry G _i , - band thickness contours θ _i-1 (z; k) and θ _i (z; k) at the inlet and outlet of the gantry G _i , - Band trains at the inlet and outlet of the gantry G _i , - assumed or calculated velocity distribution v _i-1 (z; k) at the inlet of the gantry G _i , - measured rolling force f _i (z; k) in the framework G _i , - setpoint values for the strip width, entrance thickness in the strip center and decrease of the hot strip ( 10 ) in the framework G _i . A method according to claim 4, characterized in that the material flow models 50i in the third step, the same data is supplied as the band flatness models 40i , and additionally as input variables of the material flow models 50i Friction parameters R are used, which describe the friction conditions in the longitudinal and transverse direction in the nip. Method according to one of the preceding claims, characterized in that in the fourth step, following the partial step 4.2), a corrected residual strip thickness profile Ω _{i, corr} (z; k) is first calculated by dividing the residual strip thickness profile Ω ₁ (z; k In addition, correction values a _i (z; k), b _i (z; k) are subtracted, wherein - a _i (z; k) is an initial contour of the work rolls and - b _i (z; k) is a currently calculated thermal and wear In the following steps of the fourth step, the residual band thickness profile Ω _{i, corr} (z; k) thus corrected is used to determine the target contours H _i (z; k), K _i (z; k). Method according to one of the preceding claims, characterized in that the first and the second sub-step in the fifth step are carried out independently of each other and in parallel. Computer program product for carrying out a method according to one of Claims 1 to 7. With a computer program product ( 2 ' ) according to claim 8 programmed control computer ( 2 ) for a rolling mill ( 1 ) with at least two stands G. From a control computer ( 2 ) according to claim 9 controlled rolling mill ( 1 ).

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