EP1360018B1 - Method and device for pre-adjusting process variables of a mill train for milling metal strips - Google Patents

Abstract

Method and apparatus for presetting process variables in at least one actuating element of a rolling train for rolling metal strips, in which guarantee values are predefined. The guarantee values specified, which cover the intended stipulations and the associated tolerance bands for the quality features of the metal strip, are, for example, strip flatness and/or strip contour and/or strip profile. The tolerance bands of the intended stipulations over a predefinable number of metal strips are taken into account in such a way that an optimum set point calculation of at least one process variable is carried out over the predefined number of metal strips.

Description

The invention relates to a method and a device for presetting process variables of a rolling train for rolling metal strips, the tolerance ranges of the guaranteed values being used over a predeterminable number of metal strips for optimum setpoint calculation of the process variables.

When rolling a metal strip, especially when flat rolling, the quality of a metal strip in the form of predetermined guaranteed values of strip flatness, strip contour and strip profile is determined. To achieve these guaranteed values, which serve as quality features of a metal strip, actuators are used, which set the shape of the roll gap, also referred to as a roll gap profile. The setpoint values for the actuators are referred to below as process variables.

During the rolling of a metal strip, due to high strip temperatures and the associated heat input into the rolls, dynamic thermal crowns are formed which influence the roll gap profile via the strip run and from strip to strip. Depending on the installation location, rolled material and roll material, a more or less pronounced wear contour is formed over the service life of a roller.

From the DE 198 51 554 A1 a method and device for presetting a rolling line for rolling a metal strip is known, wherein the default setting is such that the difference between the profile and / or the flatness of the metal strip when leaving the rolling train and a predetermined Nominal profile and / or a predetermined Sollplanheit is minimal. In this case, the difference between the profile and / or the flatness of the metal strip when leaving the mill train and a predetermined nominal profile and / or a predetermined Sollplanheit depending on the difference of parameters of the metal strip and the corresponding parameters of a previously rolled metal strip is corrected.

In order to be able to set the desired roll gap profile in so-called conversion tapes, large setpoint value changes of the process variables often have to be carried out. Conversion tapes are to be understood as meaning metal tapes whose properties deviate from the properties of a previously rolled metal strip or which are assigned to a different rolling program with respect to a preceding metal strip. With pronounced thermal crowning of the rolls, a change in the setpoint values of the process variables often leads to an undesired deviation of the roll gap profile from its ideal shape. This effect has a negative effect on the required quality features of the strip flatness, strip contour and the strip profile.

The previously known devices or methods always tried to determine the best solution (solution in which the target specifications of the guarantee values for flatness and / or strip contour and / or strip profile are maximally fulfilled) for the respectively following metal strip. Possible tolerance ranges of the target specifications were not considered in advance.

Starting from the prior art, it is an object of the invention to provide a method or a device that allows or achieve the required quality features of metal bands.

The object is achieved by a method according to claim 1 and a device according to claim 7 solved. Further developments of the method according to the invention are specified in the dependent claims 2 to 6.

In the method according to the invention, the presetting of process variables of the actuators of a rolling train for rolling metal strips takes place over a predeterminable number of metal strips. The required guarantee values, ie. H. Target specifications and associated tolerance ranges for quality features of the metal strips, such. As strip flatness and / or band contour and / or band profile, taken into account over the predetermined number of metal bands such that depending on the tolerance ranges of the guaranteed values optimal setpoint calculation of the process variables of the actuators is performed.

An advantageous embodiment of the invention is that at least 2 metal strips are taken into account for the setpoint calculation.

In a further advantageous embodiment of the invention, the presetting of process variables of the actuators takes place in conversion belts, depending on the required guaranteed values.

An advantageous embodiment of the invention is that the metal strips are identified in the given number of metal bands, where the predetermined guaranteed values due to the current setpoint adjustment of the process variables can not be met. Furthermore, so-called priority features are evaluated in the identification of critical metal bands. Priority features are z. As geometric sizes (eg, tape thickness, bandwidth) and / or material properties (eg strength, assortment - stainless steel).

In an advantageous embodiment of the invention, a new setpoint calculation of the process variables of the actuators is performed depending on the identified metal bands.

A further advantageous embodiment of the invention is characterized in that the new setpoint calculation exploits the tolerance ranges of the setpoint specifications in such a way that the guaranteed values of the identified metal strips are achieved, whereby a targeted deviation of the setpoint specifications lies in the tolerance range.

The inventive device according to claim 7 comprises a computing system for presetting process variables in at least one actuator of a rolling train for rolling metal strips, in which guaranteed values are given, which include the target specifications and the associated tolerance ranges for the quality characteristics of the metal strips. As quality features are z. B. band flatness and / or band contour and / or band profile specified. In this case, the computing system is designed such that an optimal setpoint calculation can be carried out for at least one process variable over a predeterminable number of metal strips, wherein the tolerance ranges of the setpoint specifications over the predetermined number of metal strips are taken into account.

FIG 1

ein Beispiel für die erfindungsgemäße Ausführung zur Voreinstellung von Prozessgrößen der Stellglieder ei- ner Walzstraße.

The invention and further advantages and details are explained in more detail below with reference to a schematically illustrated exemplary embodiment in the drawing. Show it:

FIG. 1

an example of the embodiment according to the invention for the presetting of process variables of the actuators of a rolling train.

FIG. 1 shows according to the invention, a method for presetting process variables of the actuators of a rolling line for rolling metal strips. The presetting of process variables takes place via a known method 2 and a Extended Method 1. In the known method 2, 3 process data of the current band with respect to band profile, band flatness and band contour are calculated in the stitch plan prediction. In this process, 3 process data, such as eg. As rolling force, strip thickness and bandwidth, and then the profile and flatness control 4 transmitted. In addition to the known method 2, a stitch plan prediction 3 for a predeterminable number of metal strips is carried out in the extended method 1. It has proven to be advantageous in conversion tapes usually to consider a number of two to eight metal strips. For very large deviations of the roll gap profile from its ideal shape, however, more than eight metal strips can be considered at any time.

In the stitch plan prediction 3 process data, such. B. rolling force, strip thickness and bandwidth, calculated for the predetermined number of metal bands and stored in a data buffer 6. In addition to the stored process data per metal strip, critical metal strips 7 are identified and marked as critical. An identification of critical metal strips 7 takes place in the metal strips, in which the predetermined guaranteed values can not be met due to the current setpoint adjustment of the process variables of the actuators and / or which are defined by priority features. Subsequently, the calculated process data of the identified critical metal strips 7 and the calculated process data of the current metal strip 8 of the profile and flatness control 4 are transmitted. Depending on process data and system restrictions, such as: As mechanical limits, takes place in the profile and flatness control 4, a setpoint calculation of the process variables 5 of the identified critical metal bands 7 (S _critical ) and for the current metal band 8 (S _current ). The process variables are used to set the roll gap profile by means of the associated actuators. From the calculated setpoint values of the process variables 5 for the current metal strip 8 and for the identified critical Metal bands 7 are determined in the actuator _boundary calculation 9 actuator _limits (S _limit ), so that the actuators are always placed in the direction of the identified critical metal strip 7. This avoids that too large setpoint jumps of the actuators in identified critical metal bands 7, such. B. in conversion bands result. The calculation of the actuator limits follows the following rule: $${\mathrm{S}}_{\mathrm{border}}\mathrm{=}{\mathrm{S}}_{\mathrm{critical}}\mathrm{\pm }\mathrm{\alpha }\left|{\mathrm{S}}_{\mathrm{current}}\mathrm{-}{\mathrm{S}}_{\mathrm{critical}}\right|$$

Δs ist ein Stellgliedbereich, der von der Position der identifizierten kritischen Metallbänder abhängt. Folgende Tabelle zeigt ein Beispiel für die Definition von Δs für das Stellglied CVC (Walzenverschiebung). Position Δs [mm] Bemerkung 1 10 Das identifizierte kritische Metallband wird als nächstes gewalzt. 2 20 Das identifizierte kritische Metallband wird als übernächstes gewalzt. 3 30 Das identifizierte kritische Metallband befindet sich an dritter Stelle. ... ... ... Another alternative calculation of the actuator limits is according to the following rule: $${\mathrm{S}}_{\mathrm{border}}\mathrm{=}{\mathrm{S}}_{\mathrm{critical}}\mathrm{\pm }\mathrm{.DELTA.s}$$

Δs is an actuator range that depends on the position of the identified critical metal bands. The following table shows an example of the definition of Δs for the actuator CVC (roller displacement). position Δs [mm] comment 1 10 The identified critical metal strip is rolled next. 2 20 The identified critical metal strip is rolled next. 3 30 The identified critical metal band is in third place. ... ... ...

The value α represents a factor of 1 to 0, which specifies the actuator limits. The actuator limits calculated in the actuator boundary calculation 9 are subsequently transferred to the profile and flatness control 4 of the known method 2. Depending on the calculated process data of the stitch plan prediction 3 of the known method 2 and the calculated Actuator limits of the actuator boundary calculation 9 are calculated in the profile and flatness control 4 of the known method 2, the new set values of the process variables 5 for the actuators for adjusting the Walspaltprofils.

Claims (7)

1. Method of presetting process variables in at least one actuating element of a rolling train for rolling metal strips, in which guarantee values are predefined which cover the intended stipulations and the associated tolerance bands for the quality features of the metal strips, the tolerance bands of the intended stipulations over a predefinable number of metal strips being taken into account in such a way that an optimum set point calculation is carried out in the case of at least one process variable over the predefined number of metal strips.
2. Method according to Claim 1, characterized in that at least two metal strips are taken into account for the set point calculation.
3. Method according to Claim 1 or 2, characterized in that the presetting of process variables is carried out on the basis of the required guarantee values during changeover strips.
4. Method according to Claim 1, 2 or 3, characterized in that in the predefined number of metal strips, those metal strips are identified in which the predefined guarantee values cannot be maintained on the basis of the current set point setting of the process variables and/or the metal strips are defined on the basis of priority features.
5. Method according to Claim 4, characterized in that a new set point calculation of the process variables is carried out on the basis of the identified metal strips.
6. Method according to Claim 5, characterized in that the new set point calculation uses the tolerance bands of the intended stipulations in such a way that the guarantee values of the identified metal strips are reached, there being a deliberate deviation from the intended stipulations in the tolerance band.
7. Apparatus for presetting process variables in at least one actuating element of a rolling train for rolling metal strips, in which guarantee values are predefined which cover the intended stipulations and the associated tolerance bands for the quality features of the metal strips, it being possible for a computing system to carry out an optimum set point calculation in at least one process variable over a predefinable number of metal strips, the tolerance bands of the intended stipulations over the predefined number of metal strips being taken into account.

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