EP3009205B1 - Consideration of a reference speed when determining a transport speed - Google Patents

Description

• wobei das Metallband in einer Anzahl von Walzgerüsten der Walzanlage gewalzt wird, sodann in einer zwischen den Walzgerüsten und einer Haspeleinrichtung der Walzanlage angeordneten Kühlstrecke der Walzanlage gekühlt wird und schließlich in der Haspeleinrichtung aufgehaspelt wird,
• wobei eine Steuereinrichtung der Walzanlage vor dem Walzen des Metallbandes in den Walzgerüsten eine Leitgeschwindigkeit für die Walzanlage ermittelt und beim Walzen des Metallbandes die Walzanlage entsprechend der ermittelten Leitgeschwindigkeit betreibt.

The present invention is based on an operating method for a rolling mill for rolling a metal strip,

• wherein the metal strip is rolled in a number of rolling stands of the rolling mill, then cooled in a cooling section of the rolling mill arranged between the rolling stands and a reeling device of the rolling mill, and finally wound up in the reeling device,
• wherein a control device of the rolling mill determined before rolling the metal strip in the rolling stands, a guide speed for the rolling mill and when rolling the metal strip, the rolling mill operates according to the determined guide speed.

The present invention is further based on a computer program comprising machine code which can be executed by a control device for a rolling mill, wherein the processing of the machine code by the control device causes the control device to operate the rolling mill according to such an operating method.

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

• wobei die Walzanlage eine Anzahl von Walzgerüsten aufweist, in denen das Metallband gewalzt wird,
• wobei die Walzanlage eine Kühlstrecke aufweist, in der das Metallband nach dem Walzen gekühlt wird,
• wobei die Walzanlage eine Haspeleinrichtung aufweist, in der das Metallband nach dem Kühlen aufgehaspelt wird,
• wobei die Kühlstrecke zwischen den Walzgerüsten und der Haspeleinrichtung angeordnet ist,
• wobei die Walzstraße eine Steuereinrichtung aufweist, welche die Walzstraße gemäß einem derartigen Betriebsverfahren betreibt.

The present invention is further based on a rolling plant for rolling a metal strip,

• wherein the rolling mill has a number of rolling stands in which the metal strip is rolled,
• wherein the rolling mill has a cooling section in which the metal strip is cooled after rolling,
• wherein the rolling mill has a reeling device in which the metal strip is rewound after cooling,
• wherein the cooling section is arranged between the rolling stands and the reel device,
• wherein the rolling train has a control device which operates the rolling train according to such an operating method.

These items are from the WO 2011/138 067 A2 known.

In hot strip mills and heavy plate mills steel is also often produced for pipelines, for example steel grades X70 and X80. These are particularly thick strips or sheets, which are later bent into tubes. In particular, in pipelines for natural gas must be ensured that the material used has a high strength and high toughness, since the gas is under a high pressure (sometimes up to 200 bar) and a leak can cause a serious accident. The production of the steel grades mentioned succeeds in heavy plate mills mostly with good quality, but is relatively expensive. Furthermore, the maximum throughput of a plate mill is significantly lower than the maximum throughput of a hot strip mill. It is therefore increasingly being attempted to produce high-quality steel in hot strip mills, which meets the requirements of pipelines. One of the requirements is intensive cooling after rolling, otherwise the required material properties can not be achieved. Nevertheless, the production of high-quality steels - especially the material grades X70 and X80 - does not succeed with sufficiently good reproducibility.

In the prior art, the roughing train is used for thermodynamic rolling. Thereafter, the finished pre-bands are left on the roller table in front of the roughing road or between the roughing road and the finishing train for a certain period of time. After reaching a predetermined pre-strip temperature, the remaining stitches of the roughing mill are carried out or the pre-strip is led directly to the finishing train. The pass plan calculation of the finishing train determines a guide speed or a Leitgeschwindigkeitsverlauf and the Stichabnahmen to transport the then finished rolled metal strip with a predetermined Endwalztemperatur and a predetermined thickness in the cooling section. In the cooling section, the metal strip is cooled by means of intensive cooling with a predetermined temperature gradient and then finally wound up in the coiler.

A major problem with the cooling of thick metal strips in the intensive cooling is the temperature difference that occurs between the surface of the metal strip and the inside of the metal strip. The temperature difference can be several 100 ° C. The (cold) metal near the surface forms bainite, while the metal inside usually remains ferritic. As a result, the surface is significantly harder than the core of the metal strip. This is a desired effect. The problem, however, is that in the procedure used in the prior art, a large dispersion of the material properties arises, the reproducibility is therefore given only to a limited extent. Therefore, a relatively high proportion of metal strips does not maintain the desired reel temperatures neither during coiling nor does it have the desired material properties. The deviations of the actual material properties from the desired material properties can go so far that the metal bands get stuck during rolling or rewind already coiled coils, so that malfunctions and considerable economic damage are the result. The metal strips, which do not meet the desired material properties, therefore represent scrap, which must be remelted.

The reason for the different material properties lies in the different bainite parts of the steel at the surface and the different thicknesses of the purely ferritic core. The reason for this is the rolling in the rolling stands of the rolling mill. Because depending on the temperature at which the pre-strip fed to the rolling stands of the rolling mill is, are determined by the control device different conduction velocities. This leads - even with the same final rolling temperature and the same coiler temperature - to different temporal cooling progressions in the cooling section.

The variations in the pre-strip temperature are often unavoidable. They often arise out of technical production needs, because, for example, the waiting time in thermodynamic rolling could not be calculated accurately enough or because the next slab was already pulled out of the oven and therefore must be pre-rolled, so that the lying of the already pre-rolled metal strip must be prematurely terminated ,

An operating method of the type mentioned is from the JP S63 168 211 A known. In this method, based on an actual temperature of the metal strip before rolling in the rolling stands, model-based an expected temperature after rolling in the rolling stands determined. The determined temperature is compared with a setpoint temperature range. If the detected temperature is outside the target temperature range, an intended rolling speed pattern is corrected.

The object of the present invention is to provide possibilities by means of which the proportion of metal strips which have the desired material properties can be increased - if possible to 100%.

The object is achieved by an operating method with the features of claim 1. Advantageous embodiments of the operating method according to the invention are the subject of the dependent claims 2 to 7.

• dass die Steuereinrichtung die Leitgeschwindigkeit anhand eines Istenergieinhalts des Metallbandes vor dem Walzen in den Walzgerüsten, eines Sollenergieinhalts des Metallbandes nach dem Walzen in den Walzgerüsten und einer Referenzgeschwindigkeit ermittelt,
• dass die Steuereinrichtung, ausgehend von dem Istenergieinhalt des Metallbandes vor dem Walzen in den Walzgerüsten, mittels eines Modells der Walzgerüste der Walzanlage einen erwarteten Energieinhalt ermittelt, der bei einer angesetzten Leitgeschwindigkeit nach dem Walzen in den Walzgerüsten erwartet wird,
• dass die Steuereinrichtung durch Variieren der angesetzten Leitgeschwindigkeit eine Zielfunktion optimiert, in welche die Abweichung des erwarteten Energieinhalts vom Sollenergieinhalt des Metallbandes nach dem Walzen in den Walzgerüsten eingeht,
• dass entweder in die Zielfunktion zusätzlich auch eine Abweichung der angesetzten Leitgeschwindigkeit von der Referenzgeschwindigkeit eingeht, oder die Zielfunktion unabhängig von der Abweichung der angesetzten Leitgeschwindigkeit von der Referenzgeschwindigkeit ist und die Steuereinrichtung als Leitgeschwindigkeit eine Linearkombination derjenigen angesetzten Leitgeschwindigkeit, bei welcher die Zielfunktion ihren optimalen Wert aufweist, und der Referenzgeschwindigkeit verwendet.

According to the invention, an operating method of the initially mentioned type is configured by

• that the control device according to a Istenergieinhalts of the metal strip before rolling in the rolling stands, a desired energy content of the metal strip after rolling in the rolling stands and a reference speed,
• the control device determines, based on the energy content of the metal strip before rolling in the roll stands, by means of a model of the rolling stands of the rolling mill, an expected energy content which is expected at an applied guide speed after rolling in the rolling stands;
• in that the control device optimizes a target function by varying the set guide speed, in which the deviation of the expected energy content from the desired energy content of the metal strip after rolling in the rolling stands is received,
• that either in the objective function also a deviation of the set guide speed of the reference speed is received, or the target function is independent of the deviation of the set guide speed of the reference speed and the control device as a guide velocity linear combination of those scheduled guide speed, at which the target function has its optimum value , and the reference speed used.

Thus, as a substitute variable for the structure of the metal strip which can not be directly determined, it is not the approximation to a desired energy content that is used as such and alone, but a mixture of this energy content and a reference speed. Although this procedure can not - at least not necessarily and necessarily - the material properties of the metal strip after passing through the cooling section are predicted reliable. This is not necessary. The decisive factor is that this measure leads to better reproducibility. Thus, it only has to be determined to what extent the reference speed has to be taken into account when determining the guide speed in order to be able to reproduce material properties well.

In the simplest case, it is possible that an extent to which the control device takes into account the reference speed in the determination of the guide speed, the control device is fixed or is specified by an operator of the rolling mill. In this case, the optimum value for the extent, for example, based on microstructural investigations of already rolled metal strips can be determined by applying different values of the extent on the rolling mill and then continue to use the value at which the lowest dispersion of the material properties has been obtained.

• dass es wiederholt mit verschiedenen Metallbändern ausgeführt wird,
• dass der Steuereinrichtung eine jeweilige Endwalztemperatur, die das jeweilige Metallband nach dem Walzen, aber vor dem Kühlen aufweist, zugeführt wird,
• dass die Steuereinrichtung, ausgehend von der jeweiligen Endwalztemperatur, für das jeweilige Metallband mittels eines Modells der Kühlstrecke der Walzanlage jeweils eine erwartete Haspeltemperatur ermittelt, die für das jeweilige Metallband beim Haspeln erwartet wird,
• dass die Steuereinrichtung jeweils die erwartete Haspeltemperatur mit einer jeweiligen tatsächlichen Haspeltemperatur vergleicht und anhand des Vergleichs einen Korrekturfaktor für das Modell der Kühlstrecke ermittelt und
• dass die Steuereinrichtung durch Auswertung der Korrekturfaktoren in Abhängigkeit von den jeweiligen Leitgeschwindigkeiten und/oder den jeweiligen Endwalztemperaturen das Ausmaß derart nachführt, dass der Einfluss der Leitgeschwindigkeit und/oder der Endwalztemperatur auf den Korrekturfaktor minimiert wird.

However, a particularly preferred procedure is given by

• that it is repeatedly carried out with different metal bands,
• the control device is supplied with a respective final rolling temperature which the respective metal strip has after rolling but before cooling,
• that the control device, based on the respective final rolling temperature, for the respective metal strip by means of a model of the cooling section of the rolling mill in each case determines an expected reel temperature which is expected for the respective metal strip during reeling,
• that the control device in each case compares the expected reel temperature with a respective actual coiler temperature and, based on the comparison, determines a correction factor for the model of the cooling section and
• the control device, by evaluating the correction factors as a function of the respective guide speeds and / or the respective final rolling temperatures, tracks the extent such that the influence of the guide speed and / or the final rolling temperature on the correction factor is minimized.

It is possible that the conduction velocity is determined uniformly for the entire metal strip. Alternatively, it is possible that the guide speed is determined individually for individual sections of the metal strip. In the latter case, the Reference speed be determined individually for the individual sections of the metal strip. Also, a determination of the conduction velocity as a function of the location of a particular portion of the metal strip - for example, the tape head - or as a function of time is possible. In this case, the reference velocity may also be a function of the location of the particular section of the metal strip
or time.

Preferably, a so-called intensive cooling takes place in the cooling section. In this case, the metal strip is cooled in the cooling section with standing under a pressure between 1.5 bar and 5.0 bar standing water.

The object is further achieved by a computer program having the features of claim 8. According to the invention, the execution of the computer program by the control device causes the control device to operate the rolling mill in accordance with an operating method according to the invention.

The object is further achieved by a control device for a rolling mill with the features of claim 9. According to the invention, the control device is programmed with a computer program according to the invention, so that the control device operates the rolling mill according to an operating method according to the invention.

The object is further achieved by a rolling mill with the features of claim 10. According to the invention, the control device operates the rolling mill in each case according to an operating method according to the invention.

FIG 1 und 2

je eine Walzanlage zum Walzen eines Metallbandes,

FIG 3 und 4

mögliche Vorgehensweisen zur Ermittlung einer Leitgeschwindigkeit,

FIG 5

ein Ablaufdiagramm,

FIG 6

ein Modell einer Kühlstrecke und

FIG 7 und 8

Metallbänder.

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

1 and 2

one rolling mill each for rolling a metal strip,

3 and 4

possible procedures for determining a guide speed,

FIG. 5

a flow chart,

FIG. 6

a model of a cooling line and

FIGS. 7 and 8

Metal bands.

According to FIG. 1 is a rolling mill for rolling a metal strip 1 as a finishing train 2 with downstream cooling section 3 and the cooling section 3 downstream coiler 4 is formed. The cooling section 3 is thus arranged between the finishing train 2 and the coiler 4. The finishing train 2 has a plurality of rolling stands 5, which are traversed by the metal strip 1 successively in a transport direction x. The number of rolling stands 5 is in the rolling mill of FIG. 1 greater than 1. Usually it is 5, 6, 7 or 8. The metal strip 1 is usually a steel strip.

In the rolling stands 5, the metal strip 1 is rolled. Each rolling stand 5 of the finishing train 2 performs a single pass. After rolling in the rolling stands 5 of the finishing train 2, the metal strip 1 is cooled in the cooling section 3. Preferably, the metal strip 1 is cooled in the cooling section 3 with water, which is under a pressure p between 1.5 bar and 5.0 bar (so-called intensive cooling). After cooling the metal strip 1 in the cooling section 3, the metal strip 1 is reeled in the coiler 4.

FIG. 2 shows a possible alternative embodiment of the rolling mill for rolling a metal strip 1. Comparable elements are in FIG. 2 provided with the same reference numerals as in FIG. 1 , Again, the metal strip 1 is usually a steel strip.

According to FIG. 2 the rolling mill is designed as Steckel mill 6. The Steckel mill 6 generally has a single roll stand 5, in which the metal strip 1 reversing in several rolling passes is rolled. In individual cases, two rolling stands 5 may be present. Also in this case, however, the metal strip in the two stands 5 is reversibly rolled. On both sides of the roll stand 5 (or the rolling stands 5) is ever a Coilbox 7 available in which the metal strip 1 is reeled between the individual rolling passes.

On one side of the Steckel mill 6, a cooling section 3 connects. After the last pass, the metal strip 1 is not coiled in the coil box 7 between the roll stand 5 and the cooling section 3, but fed to the cooling section 3. There, the metal strip 1 is cooled after rolling. Also in the rolling mill of FIG. 2 For example, the metal strip 1 in the cooling section 3 is preferably cooled with water which is at a pressure p between 1.5 bar and 5.0 bar (so-called intensive cooling). The cooling section 3 is arranged downstream of a reeling device 4. The cooling section 3 is therefore also in the embodiment of the rolling mill according to FIG. 2 between the rolling mill 5 and the coiler 4. As a rule, one of the two coil boxes 7 is furthermore arranged between the roll stand 5 and the cooling section 3.

The respective rolling mill has according to the FIG. 1 and 2 a control device 8. The control device 8 is programmed with a computer program 9. The computer program 9 can be supplied to the control device 8, for example via a data carrier 10, on which the computer program 9 is stored in (exclusively) machine-readable form-for example in electronic form. The computer program 9 comprises machine code 11 which can be processed by the control device 8. The execution of the machine code 11 by the control device 8 causes the control device 8 to operate the rolling mill in accordance with an operating method which will be explained in more detail below.

The processing of the machine code 11 by the control device 8 first causes the above explained in connection with the structural design of the rolling plants operation of the rolling mill, so the rolling of the metal strip 1 in the rolling stands 5 ( FIG. 1 ) or the roll stand 5 ( FIG. 2 ), the cooling of the metal strip 1 in the cooling section 3 after rolling and the coiling of the metal strip 1 after cooling in the cooling section. 3

The execution of the machine code 11 by the control device 8 furthermore causes the control device 8 to operate the rolling mill during rolling of the metal strip 1 and also during cooling of the metal strip 1 at a guide speed vL. The guide speed vL is a speed, from which - possibly in conjunction with the set in the rolling mill stubs and trains - occurring within the rolling system transport speeds of the metal strip 1 and the respective corresponding roller peripheral speeds of the work rolls of the rolling stands 5 are clearly determined. For example, it may be a fictitious speed of the tape head or the rotational speed of the first rolling stand 5 of the finishing train 2 or the speed of the work rolls of the rolling stand 5 of the Steckel rolling mill 6 at the first rolling pass. The guide speed vL can be defined, for example, as a function of the location of the tape head.

The guide speed vL is determined by the control device 8 before the metal strip 1 is rolled in the rolling stands 5 of the rolling mill. The control device 8 determines the guide speed vL as shown in FIG FIG. 1 and 2 based on a Istenergieinhalts E1 of the metal strip 1, a target energy content E2 * of the metal strip 1 and a reference speed vR.

The Istenergieinhalt E1 is related to a time prior to rolling of the metal strip 1 in the rolling stands 5. For example, the energy content E1 may be the temperature or the enthalpy of the metal strip 1 before rolling in the roll stands 5. The energy content E1 can for example be determined by means of a measurement at a first temperature measuring point 12 or be given directly by this measurement.

In the case of a temperature, this is the initial rolling temperature at which the metal strip 1 is fed to the finishing train 2 or the Steckel rolling mill 6.

The target energy content E 2 * of the metal strip 1 is based on a time after rolling of the metal strip 1 in the rolling stands 5, but before cooling of the metal strip 1 in the cooling section 3. The desired energy content E2 * can be, for example, the temperature or the enthalpy of the metal strip 1 after rolling in the roll stands 5, analogous to the energy content E1. The target energy content E2 * is determined according to the technological requirements as needed. In the case of a temperature is the final rolling temperature, with which the metal strip 1 is fed from the finishing train 2 and the Steckel mill 6 of the cooling section 3. As a rule, the target energy content E2 * is of the same type as the energy I1. Thus, if the energy content I1 is a temperature, the energy content E2 * is usually also a temperature. In an analogous manner, in the case that the energy content of the energy E1 is an enthalpy, as a rule, the energy content E2 * is also an enthalpy. However, this is not necessary.

The reference speed vR is a meaningful value for the guide speed vL based on empirical values.

According to FIG. 3 For example, the control device 8 can determine the guide speed vL as follows:
According to FIG. 3 the control device 8 implements a function block 13. By means of the function block 13, the control device 8 determines a pass schedule SP. As part of the function block 13, the control device 8 also sets a value for the associated guide speed vL. This value is - because it is only provisional and therefore not yet final - hereinafter referred to as scheduled guide speed and provided with the reference numeral vL '. Possible implementations of functional block 13 are well known to those skilled in the art.

The control device 8 also implements a model 14. The model 14 is a model of the rolling stands 5 of the rolling mill. By means of the model 14, the behavior of the metal strip 1 during rolling in the rolling stands 5 of the rolling mill is modeled. In particular, by means of the model 14, the temporal evolution of the temperature or the enthalpy of the metal strip 1 can be determined. The determined pass schedule SP and the set guide speed vL 'are fed to the model 14. The model 14, the Istenergieinhalt E1 of the metal strip 1 is further supplied. Based on the Istenergieinhalt E1 determines the controller 8 by means of the model 14 an expected energy content E2E. The energy content E2E is that energy content which is expected at the applied guide speed vL 'after rolling in the rolling stands 5 of the rolling mill in the metal strip 1. The expected energy content E2E is of the same type as the target energy content E2 *. Thus, the expected energy content E2E and the target energy content E2 * are either both times around temperatures or both times around enthalpies.

aufweisen. n1 und n2 sind positive - nicht notwendigerweise natürliche - Zahlen. In der Regel weisen die Zahlen n1 und n2 denselben Wert auf. Zwingend ist dies jedoch nicht erforderlich. Beispielsweise können die Zahlen n1 und n2 beide den Wert 2 aufweisen. a ist ein frei wählbarer Wichtungsfaktor. Der Wichtungsfaktor a legt fest, in welchem Ausmaß die Abweichung der angesetzten Leitgeschwindigkeit vL' von der Referenzgeschwindigkeit vR bei der endgültigen Ermittlung der Leitgeschwindigkeit vL berücksichtigt wird.In a function block 15, the control device 8 forms a target function Z. Both a deviation of the expected energy content E2E from the target energy content E2 * of the metal strip 1 and a deviation of the set guide speed vL 'from the reference speed vR enter the target function Z. For example, the objective function Z may be the form $$Z={\left|e2e-\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="imgf0001.png"\; state="\{\{state\}\}">e</figure-callout>}2*\right|}^{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="imgf0002.png,imgf0004.png"\; state="\{\{state\}\}">n</figure-callout>}1}+a\cdot {\left|\mathit{vL}\text{'}\mathrm{}-\mathit{vR}\right|}^{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="imgf0001.png"\; state="\{\{state\}\}">n</figure-callout>}2}$$

exhibit. n1 and n2 are positive - not necessarily natural - numbers. As a rule, the numbers n1 and n2 have the same value. However, this is not necessary. For example, the numbers n1 and n2 may both be 2. a is a freely selectable weighting factor. The weighting factor a determines to what extent the deviation of the set guide speed vL 'from the reference speed vR is taken into account in the final determination of the guide speed vL.

tA ist hierbei der Zeitpunkt, zu dem der Bandkopf des Metallbandes 1 in das vorderste Walzgerüst 5 der Fertigstraße 2
oder erstmals in das Walzgerüst 5 des Steckelwalzwerks 6 einläuft. tE ist der Zeitpunkt, zu dem der Bandfuß des Metallbandes 1 aus dem letzten Walzgerüst 5 der Fertigstraße oder letztmals aus dem Walzgerüst 5 des Steckelwalzwerks 6 ausläuft.Equation (1) can be solved in the simplest case as a scalar equation. Alternatively, equation (1) may be applied as a functional over the location of a particular portion of the metal tape 1 - for example the tape head - or time. For example, in the case of a function of time, equation (1) may be set as follows: $$Z={\displaystyle {\int }_{\mathit{tA}}^{\mathit{tE}}{\left|e2e\left(t\right)-\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="imgf0001.png"\; state="\{\{state\}\}">e</figure-callout>}2*\left(t\right)\right|}^{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="imgf0002.png,imgf0004.png"\; state="\{\{state\}\}">n</figure-callout>}1}+a\left(t\right)\cdot {\left|\mathit{vL}\text{'}\left(t\right)-\mathit{vR}\left(t\right)\right|}^{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="imgf0001.png"\; state="\{\{state\}\}">n</figure-callout>}2}\mathit{dt}}$$

tA is the time at which the tape head of the metal strip 1 in the foremost rolling stand 5 of the finishing train. 2
or enters the rolling stand 5 of the Steckel mill 6 for the first time. tE is the time at which the band foot of the metal strip 1 expires from the last rolling stand 5 of the finishing train or last time out of the rolling stand 5 of the Steckel rolling mill 6.

In a decision block 16, the control device 8 checks whether the target function Z is already optimized, for example, is minimal or - with a suitable definition of the target function Z - is maximum. If this is not the case, the control device 8 returns to the function block 13. There, at least the scheduled guide speed vL 'is varied. If necessary, the stitch plan SP is also varied. Varying takes place with the aim of optimizing the objective function Z. If this is the case, however, the target function Z is already optimized, the control device 8 takes over in a function block 17, the last set guide speed vL '- ie the applied guide speed vL', in which the target function Z has its optimal value - as a guide speed vL , This value is therefore used as the guide speed vL.

According to FIG. 4 can the controller 8 - as an alternative to the procedure according to FIG. 3 For example, determine the conduction velocity vL as follows:
According to FIG. 4 implements the controller 8 analogously to FIG. 3 Function block 13, model 14, and decision block 16. These elements 13, 14, 16 are identical to those of FIG FIG. 3 , However, the functional blocks 15 and 17 are replaced by functional blocks 18 and 19.

aufweisen. n ist eine positive - nicht notwendigerweise natürliche - Zahl. Beispielsweise kann die Zahl n den Wert 2 aufweisen. Analog zu Gleichung (1) kann auch Gleichung (2) alternativ als skalare Gleichung oder als Funktional angesetzt werden.In the function block 18, the control device 8 forms - analogous to the function block 15 - a target function Z. However, only the deviation of the expected energy content E2E from the target energy content E2 * of the metal strip 1 enters the target function Z of the function block 18. On the other hand, the deviation of the set guide speed vL 'from the reference speed vR does not enter into the objective function Z of the function block 18. For example, the objective function Z may be the form $$Z={\left|e2e-\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="imgf0001.png"\; state="\{\{state\}\}">e</figure-callout>}2*\right|}^n$$

exhibit. n is a positive - not necessarily natural - number. For example, the number n may have the value 2. Analogously to equation (1), equation (2) can alternatively be stated as a scalar equation or as a functional.

ermittelt. a ist - wie auch in Gleichung 1 - ein frei wählbarer Wichtungsfaktor. Der Wichtungsfaktor a legt fest, in welchem Ausmaß die Abweichung der angesetzten Leitgeschwindigkeit vL' von der Referenzgeschwindigkeit vR bei der endgültigen Ermittlung der Leitgeschwindigkeit vL berücksichtigt wird. Den im Funktionsblock 19 ermittelten Wert übernimmt die Steuereinrichtung 8 als Leitgeschwindigkeit vL. Dieser Wert wird also als Leitgeschwindigkeit vL verwendet.In the function block 19, the control device 8 forms a linear combination of the set guide speed vL ', at which the target function Z has its optimum value, and the reference speed vR. For example, this can be done by the controller 8, the guide speed vL by the equation $$\mathit{vL}=\left(1-a\right)\cdot \mathit{vL}\text{'}+a\cdot \mathit{vR}$$

determined. a is - as in Equation 1 - a freely selectable weighting factor. The weighting factor a determines to what extent the deviation of the set guide speed vL 'from the reference speed vR is taken into account in the final determination of the guide speed vL. The im Functional block 19 determined value takes over the control device 8 as a guide speed vL. This value is therefore used as the guide speed vL.

It is possible that the weighting factor a of the control device 8 is fixed. This is in the FIG. 1 and 2 indicated that the weighting factor a is registered within the control device 8. Alternatively, it is possible that the weighting factor a of the control device 8 is predetermined by an operator 20. This too is in the FIG. 1 and 2 shown schematically. However, particularly preferred is a procedure which will be described below in connection with FIG. 5 is explained in more detail. In addition are the FIG. 1 and 2 to bring with.

As part of the approach of FIG. 5 It is first necessary that the procedure is carried out repeatedly with different metal bands 1. This is in FIG. 5 indicated that the local measures are involved in a loop. Furthermore, it is within the framework of FIG. 5 required that the control device 8 is fed to a respective final rolling temperature T2. The final rolling temperature T2 is the temperature that the metal strip 1 has after rolling but before cooling. For example, the final rolling temperature T2 can be determined by a measurement at a second temperature measuring station 21. The second temperature measuring station 21 is as shown in the FIG. 1 and 2 On the output side of the rolling stands 5, but arranged in front of the cooling section 3. Finally, it is necessary for the control device 8 to be supplied with a respective reel temperature T3. The reel temperature T3 is the temperature that the metal strip 1 has after cooling in the cooling section 3. For example, the reel temperature T3 can be determined by a measurement at a third temperature measuring station 22. The third temperature measuring station 22 is as shown in the FIG. 1 and 2 on the output side of the cooling section 3, but arranged in front of the coiler 4.

According to FIG. 5 takes the control device 8 in a step S1 against the detected Endwalztemperatur T2. The step S1 is - of course - performed prior to cooling of the metal strip 1 in the cooling section 3.

In a step S2, the control device 8 determines, based on the respective final rolling temperature T2, by means of a model 23, an expected reel temperature T3E. The model 23 is a model of the cooling section 3 of the rolling mill. The model 23 are in a conventional manner according to FIG. 6 In addition to the final rolling temperature T2 influencing B supplied, with which the metal strip 1 is acted upon in the cooling section 4. Within the framework of the model 23, the temperature development and the phase development in the metal strip 1 are determined-as a rule by iteratively solving a heat conduction equation and a phase transformation equation.

The determination is made for the respective metal strip 1. Thus, the final rolling temperature T2 of the respective metal strip 1 is used by the model 23 and (at least among other things) the expected reel temperature T3E for the respective metal strip 1 is determined. The expected reel temperature T3E corresponds to the temperature that is expected for the respective metal strip 1 when entering the reeling device 4 and thus during reeling.

The step S2 can be carried out during the cooling of the respective metal strip 1 in the cooling section 3.

In a step S3, the control device 8 receives the detected reel temperature T3. The step S3 is - of course - performed after cooling of the metal strip 1 in the cooling section 3.

In a step S4, the control device 8 compares the expected reel temperature T3E with the respective actual reel temperature T3. Based on the comparison, the control device 8 determines a correction factor k for the model 23 of the cooling section 3. The model 23 adapted due to the change in the correction factor k uses the control device 8 in the context of the subsequent metal strip 1, that is, in the renewed execution of the steps S1 to S4.

As far explained so far, the approach of FIG. 5 known in the art and is generally used. In addition, in the approach of FIG. 5 however, a step S5 exists. In step S5, the controller 8 performs the weighting factor a. The tracking takes place by evaluating the correction factors k as a function of the respective guide speeds vL and / or the respective final rolling temperatures T2. The tracking takes place in such a way that the influence of the guide speed vL and / or the final rolling temperature T2 on the correction factor k is minimized.

The procedure of FIG. 5 based on the following considerations:
As part of the execution of the model 23 is usually first determined an average temperature over the strip thickness and determined on the basis of this temperature, the development of the phase components. Thus, in the context of the model 23, the message about the temperature is first carried out and then the phase development is determined. In reality, however, the phase development takes place individually according to the respective temperature at the respective location of the metal strip 1. Due to the preference of the averaging over the temperature before the phase development, the model 23, the microstructure which occurs during cooling of the metal strip 1 in the cooling section 3 in the metal strip 1, do not detect correctly. This systematic error is reflected in the correction factor k. In practice, it also shows that - for similar metal strips 1 before rolling in the rolling mill - larger values for the correction factor k result as the guide speed vL becomes greater. In practice, this corresponds to an increased formation of bainite. In an analogous manner, it is found in practice that larger values for the correction factor k also result for larger final rolling temperatures T2. Thus, a reduction of the correction factor k due to a decrease in the final rolling temperature T2 compensate for an increase in the correction factor k due to an increase in the guide velocity vL. The amount of compensation may be partial, complete or oversized with the same increase in the guide speed vL, depending on the extent of the decrease in the final rolling temperature T2. The extent of the compensation, in turn, is determined by the weighting factor a. It is thus possible to determine the weighting factor a in such a way that (as far as possible) complete compensation takes place.

In the simplest case, in the operating method according to the invention as shown in FIG FIG. 7 the guide speed vL determined uniformly for the entire metal strip 1 (or uniformly for the entire respective metal strip 1). In this case, the reference speed vR is uniformly defined for the entire metal strip 1 or for the entire respective metal strip 1. Alternatively, it is as shown in FIG FIG. 8 possible that the conduction velocity vL - from the beginning as it is in the WO 2011/138 067 A2 is explained - is determined individually for individual sections 24 of the metal strip 1 and the respective metal strip 1. In this case, the reference speed vR can be defined uniformly for the entire metal strip 1 or for the entire respective metal strip 1. In this case, however, the reference speed vR is preferably as shown in FIG FIG. 8 determined individually for the individual sections 24 of the metal strip 1 and the entire respective metal strip 1. Again, alternatively, it is possible that the conduction velocity v L is determined as a function of the location of a specific portion of the metal strip 1 - for example, the tape head - or as a function of time. In these cases, the reference speed v R can alternatively be uniformly defined or else also be defined as a function of the location of the specific section of the metal strip 1 or as a function of time.

In summary, the present invention thus relates to the following facts:
A metal strip 1 is rolled in a number of rolling stands 5 a rolling mill, then cooled in a cooling section 3 of the rolling mill and finally wound up in the coiler 4 of the rolling mill. The cooling section 3 is arranged between the rolling stands 5 and a reeling device 4. A control device 8 of the rolling mill determined before rolling of the metal strip 1 in the rolling stands 5 a guide speed vL for the rolling mill. It operates when rolling the metal strip 1, the rolling mill according to the determined guide speed vL. The control device 8 determines the guide speed vL on the basis of an energy content E1 of the metal strip 1 before rolling in the rolling stands 5, a desired energy content E2 * of the metal strip 1 after rolling in the rolling stands 5 and a reference speed vR.

The present invention has many advantages. In particular, it is possible to roll and cool the metal strip 1 in such a way that it has reproducible material properties. Scatters due to different Istenergieinhalte E1 before rolling in the rolling stands 5 or due to different conduction velocities vL can be reduced. Furthermore, there is a more precise control of the cooling section 3, because the correction factors k of the cooling section 3 scatter less than in the prior art. This results in a further reduction in the dispersion of the material properties. Downtime due to cold metal bands 1, which can not be rewound or jump when transporting the reeled metal strip 1 due to excessive voltages can be reduced or even avoided altogether. The operating method can be realized in a simple manner and on any rolling mill. The operating method is not only suitable for the production of so-called pipe tape, but also for other steel grades. In many cases, the economic production of the grades X70 and X80 is enabled by the operating method according to the invention.

Although the invention in detail by the preferred embodiment has been illustrated and described in detail, so is the The invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention as defined by the claims.

Claims (10)

1. Operating method for a rolling installation for rolling a metal strip (1),

   - wherein the metal strip (1) is rolled in a number of roll stands (5) of the rolling installation, is then cooled in a cooling section (3) of the rolling installation, which section is arranged between the roll stands (5) and a coiling device (4) of the rolling installation, and is finally coiled in the coiling device (4),

   - wherein a control device (8) of the rolling installation determines a master speed (vL) for the rolling installation prior to the rolling of the metal strip (1) in the roll stands (5), and operates the rolling installation according to the determined master speed (vL) during the rolling of the metal strip (1), the method being characterized in that:

   - the control device (8) determines the master speed (vL) based on an actual energy content (E1) of the metal strip (1) prior to the rolling in the roll stands (5), on a setpoint energy content (E2*) of the metal strip (1) following the rolling in the roll stands (5) and on a reference speed (vR),

   - the control device (8) determines, by means of a model (15) of the roll stands (5) of the rolling installation, an expected energy content (E2E), which is expected at a set master speed (vL') following the rolling in the roll stands (5), based on the actual energy content (E1) of the metal strip (1) prior to the rolling in the roll stands (5),

   - the control device (8) optimizes a target function (Z), in which the deviation of the expected energy content (E2E) from the setpoint energy content (E2*) of the metal strip (1) following the rolling in the roll stands (5) is incorporated, by varying the set master speed (vL'),

   - either a deviation of the set master speed (vL') from the reference speed (vR) is additionally also incorporated in the target function (Z) and the control device (8) uses, as the master speed (vL), that set master speed (vL') for which the target function (Z) has its optimum value, or

   - the target function (Z) is not dependent on the deviation of the set master speed (vL') from the reference speed (vR) and the control device (8) uses, as the master speed (vL), a linear combination of that set master speed (vL') for which the target function (Z) has its optimum value and the reference speed (vR).
2. Operating method according to Claim 1, characterized in that a size factor (a) according to which the control device (8) takes into account the reference speed (vR) when determining the master speed (vL) is fixedly predefined for the control device (8) or is predefined by an operator (20) of the rolling installation.
3. Operating method according to Claim 1, characterized

   - in that said method is carried out repeatedly with different metal strips (1),

   - in that the control device (8) is supplied with a respective end rolling temperature (T2), which the respective metal strip (1) has following the rolling but prior to the cooling,

   - in that the control device (8) determines for the respective metal strip (1), by means of a model (23) of the cooling section (3) of the rolling installation, in each case an expected coiling temperature (T3E), which is expected for the respective metal strip (1) during the coiling, based on the respective end rolling temperature (T2),

   - in that the control device (8) in each case compares the expected coiling temperature (T3E) with a respective actual coiling temperature (T3) and, based on the comparison, determines a corrective factor (k) for the model (23) of the cooling section (3), and

   - in that, by evaluating the corrective factors (k) in dependence on the respective master speeds (vL) and/or the respective end rolling temperatures (T2), the control device (8) updates the size factor (a) such that the influence of the master speed (vL) and/or the end rolling temperature (T2) on the corrective factor (k) is minimized.
4. Operating method according to one of Claims 1 to 3, characterized in that the master speed (vL) is determined in a unified manner for the entire metal strip (1).
5. Operating method according to one of Claims 1 to 3, characterized in that the master speed (vL) is determined individually for individual portions (24) of the metal strip (1) .
6. Operating method according to Claim 5, characterized in that the reference speed (vR) is determined individually for the individual portions (24) of the metal strip (1).
7. Operating method according to one of the preceding claims, characterized in that the metal strip (1) is cooled in the cooling section (3) by water which is under a pressure (p) of between 1.5 bar and 5.0 bar.
8. Computer program which comprises machine code (11) which is able to be processed by a control device (8) for a rolling installation, wherein the processing of the machine code (11) by the control device (8) causes the control device (8) to operate the rolling installation on the basis of an operating method according to one of the preceding claims.
9. Control device for a rolling installation, wherein the control device is programmed using a computer program (9) according to Claim 10, with the result that the control device operates the rolling installation on the basis of an operating method according to one of Claims 1 to 7.
10. Rolling installation for rolling a metal strip (1),

    - wherein the rolling installation has a number of roll stands (5) in which the metal strip (1) is rolled,

    - wherein the rolling installation has a cooling section (3) in which the metal strip (1) is cooled following the rolling,

    - wherein the rolling installation has a coiling device (4) in which the metal strip (1) is coiled following the cooling,

    - wherein the cooling section (3) is arranged between the roll stands (5) and the coiling device (4),

    - wherein the rolling installation has a control device (8) which operates the rolling installation on the basis of an operating method according to one of Claims 1 to 7.

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