RU2779375C2 - Frequency-dependent distribution of adjusting values for changing cross-section of roll in rolling mill - Google Patents

Abstract

FIELD: material processing.

SUBSTANCE: invention relates to the control of a rolling mill for rolling rolled products. The rolling mill contains several rolling stands, through which a rolled product passes alternately. A control device determines a corresponding preliminary adjusting value for preceding rolling stands by corresponding frequency filtration of the specified characteristic value. The determination of the corresponding preliminary adjusting value for preceding rolling stands always includes only frequency components of the characteristic value, which lie below a corresponding boundary frequency. The boundary frequency from one rolling stand to another rolling stand always remains constant or increases. The control device determines the preliminary adjusting value for a certain rolling stand in such a way that the determination of the preliminary adjusting value for a certain rolling stand includes at least those frequency components of the characteristic value that lie above the boundary frequency of the rolling stand immediately preceding a certain rolling stand.

EFFECT: flatness errors in inter-stand areas are excluded.

12 cl, 7 dwg

Description

Technical field

The present invention relates to a method for operating a rolling mill for rolling rolled metal,

- in this case, the rolling mill has several rolling stands, through which the rolling passes in turn in the same direction of transport for these rolling stands, so that the rolled products are alternately rolled in the rolling stands,

- in this case, the control device of the rolling mill, on the basis of a certain value characteristic of the change in the cross section with which the rolled product must exit a certain rolling stand of the rolling mill, determines for this rolling stand and several preceding this rolling stand, when viewed in the direction of transport, rolling stands rolling mill, first the corresponding preliminary control variable, and using this respective preliminary control variable, the corresponding final control variable,

- in this case, the corresponding final control value affects the cross-section with which the rolled product exits each rolling stand of the rolling mill,

- in this case, the control device activates the rolling stands according to this final control value.

The present invention also relates to a control program, which control program includes a program code that can be processed by a control device for a rolling mill having several rolling stands, and as a result of processing the program code, the control device controls the rolling mill in accordance with such a method of operation.

The present invention also relates to a control device for a rolling mill for rolling metal rolled products, wherein the rolling mill has several rolling stands, through which the rolled stock passes in turn in the direction of transport common to these rolling stands, so that the rolled stock is alternately rolled in the rolling stands,

in this case, the control device has determination circuits, by means of which the control device, on the basis of a certain value characteristic of the change in the cross section with which the rolled product must exit a certain rolling stand of the rolling mill, determines for this rolling stand and several preceding this rolling stand, if you look at in the conveying direction, rolling stands of the rolling mill, first the corresponding preliminary control variable, and using this respective preliminary control variable, the corresponding final control variable,

- in this case, the corresponding final control value affects the cross-section with which the rolled product exits each rolling stand of the rolling mill,

- in this case, the control device activates the rolling stands according to this final control value.

The present invention also relates to a flat rolling mill,

in this case, the rolling mill has several rolling stands, through which the rolling passes in turn in the same transport direction for these rolling stands, so that the rolled products are alternately rolled in the rolling stands of the rolling mill,

wherein the rolling mill has a control device which controls the rolling stands of the rolling mill.

State of the art

Metal rolled products, in particular metal strips, are often rolled in multi-stand rolling mills. In particular, when rolling a metal strip, maintaining a given contour and maintaining a given flatness is of great importance. Contour and flatness generally cannot be influenced independently of each other. In particular, they are decisively determined by the shape of the roll gap in front of the measurement point.

Corresponding contour and flatness (or profile and flatness) adjustments are known for maintaining contour and flatness. These adjustments can affect, for example, roll bending, roll inclination, roll offset and/or roll cooling of a particular rolling stand.

When a control action is made by means of these adjustments, i.e., a change in the characteristics of the roll gap, the contour with which the metal strip leaves a certain rolling stand changes. The contour with which the metal strip leaves a particular rolling stand is at the same time also the contour with which the metal strip enters the next rolling stand. In this case, the flatness of the metal strip after the next rolling stand changes, unless the characteristic of the roll gap of the next rolling stand also changes accordingly.

A similar state of affairs is also true in the other direction. When the contour of the metal strip downstream of this rolling stand is changed by appropriate adjustment of the roll gap of a particular rolling stand, the flatness downstream of this rolling stand is also changed, unless the previous rolling stand is also adapted accordingly.

That is, when it is desired to resize the contour of a rolling stock after a certain rolling stand of a rolling mill (for example, after the last rolling stand of a rolling mill), at least this rolling stand must be rearranged. In an earlier European patent application 18 198 437.8 (date of filing 10/03/2018), not yet published on the day of filing the application for the present invention, a method for operating a rolling mill with several rolling stands is described, in which the rolling stand is also rearranged in front of a specified specific rolling stand, so that both the contour of the metal strip and the profile of the metal strip can be adjusted to their respective target values with the highest possible dynamics. In this case, the flatness error is shifted into the inter-stand region between the specified specific rolling stand and the rolling stand preceding it.

In order to avoid a flatness error in this inter-stand region, it is also possible to rearrange the contour in the following previous rolling stands and adapt these stands accordingly. In this case, the flatness error is shifted further and further into the front region of the rolling mill. However, when rolling in the front rolling stands of the rolling mill, the metal strip is often still so thick that a transverse flow of the material occurs during rolling, and consequently, flatness errors do not occur. But the dynamics of regulation is dependent on the transport time of the metal strip, which passes from the first participating rolling stand to the measuring point. Due to the long distance and the associated long transport times, the state of the art circuit in a larger rolling mill having, for example, seven rolling stands cannot be adjusted quickly and accurately.

Brief summary of the invention

The aim of the present invention is to create possibilities by means of which the contour of the rolled product can be adjusted with high dynamics, while at the same time flatness errors in the inter-stand areas are avoided as far as possible.

The problem is solved using a method of operating a rolling mill with the features of claim 1 of the claims. Preferred embodiments of the method of operation are the subject of dependent claims 2-5 of the claims.

According to the invention, the method of operating a rolling mill of the above type is carried out in such a way that

- that the control device determines the appropriate preliminary control value for the previous rolling stands by appropriate frequency filtering of the characteristic value or a corresponding intermediate value determined from the characteristic value;

- that the frequency filterings are designed in such a way that the determination of the respective pre-control variable for previous rolling stands always only includes the frequency components of the characteristic quantity that lie below the respective cut-off frequency, and

- that, in the case of several preceding rolling stands of a rolling mill when viewed from a particular rolling stand in the transport direction and viewed in the transport direction, the cut-off frequency from one rolling stand to another rolling stand always remains constant or increases.

That is, within the scope of the present invention, frequency separation of contour changes is performed. Rapid contour changes in the rear rolling stands of the rolling mill are compensated with high dynamics, while slow contour changes are shifted to the front rolling stands. Moreover, this shift is carried out the farther forward, the slower the contour changes. As a result, a high control dynamics is achieved, while at the same time the flatness error in the inter-stand areas of the rolling stands of the rolling mill remains low. In addition, the rear rolling stands are unloaded.

The control device generally determines the preliminary control variable for a certain rolling stand of the rolling mill on the basis of said characteristic value, in particular by frequency filtering this characteristic value. For previous rolling stands, this definition is always frequency filtering. In this case, it is possible for the control device to determine preliminary control variables for previous rolling stands by frequency filtering of the characteristic variable. Preferably, however, the control device determines the preliminary control values for the previous rolling stands by frequency filtering the corresponding intermediate value. In this case, the control device determines the corresponding intermediate value on the basis of the final control variable, which is always directly following the rolling stand as seen in the transport direction. The definition based on the respective intermediate value has, in particular, the advantage that the filterings can be more easily parameterised. In addition, as a rule, the remaining, unavoidable non-flatness of the metal strip in the inter-stand areas is less than when determined on the basis of the characteristic value itself.

Preferably, the control device determines the appropriate final control value for each rolling stand based on the preliminary control value for each rolling stand and the corresponding correction value. In this case, the control device determines the appropriate correction value on the basis of the pre-adjusting variable, which is always immediately preceding, as viewed in the transport direction, the rolling stand. Therefore, when activating each rolling stand, the contour change that has already been caused by the previous rolling stand or, respectively, previous rolling stands, can be taken into account.

Preferably, the control device delays the corresponding correction value with respect to the pre-control value of the rolling stand immediately preceding, as seen in the transport direction, by a corresponding delay time. As a result, a time-coordinated connection of this correction variable to the respective pre-control variable can be carried out.

Preferably, the control device limits the final control values by means of a corresponding limiting element. In this way, in particular, the adjustment limits of the actuators can be taken into account.

The problem is also solved with the help of a control program with the features of claim 6 of the claims. According to the invention, as a result of running the program code, the control device controls the rolling mill in accordance with this method of operation.

The problem is solved by means of a control device for a rolling mill with the features of claim 7 of the claims. Preferred embodiments of the control device are the subject of dependent claims 8-12 of the claims.

In accordance with the invention, the control device for the rolling mill of the above type is made so that

- that the chains for determining the previous rolling stands have frequency filters, by means of which the control device determines the appropriate preliminary control value for the previous rolling stands by appropriate frequency filtering of the characteristic value or the corresponding intermediate value determined from the characteristic value;

- that the frequency filters are designed in such a way that only the frequency components of the characteristic value that lie below the respective cut-off frequency always enter into the determination of the respective pre-control variable for previous rolling stands, and

- that, in the case of several preceding rolling stands of a rolling mill when viewed from a particular rolling stand in the transport direction, and viewed in the transport direction, the cut-off frequency from one rolling stand to another rolling stand always remains constant or increases, and

- that the determination chain for a particular rolling stand is designed in such a way that at least those frequency components of the characteristic value that lie above the cut-off frequency of the rolling stand immediately preceding, as viewed in the direction of transport, are included in the determination of the preliminary control variable for a certain rolling stand rolling stand.

That is, similar to the operation method, frequency separation of contour changes is performed so that fast contour changes in the rear rolling stands of the rolling mill are compensated with high dynamics, while slow contour changes are shifted to the front rolling stands.

Preferably, the control device enters into the determination circuit for a certain rolling stand of the rolling mill the specified characteristic value. In addition, the control device preferably has intermediate blocks, by means of which the control device determines for the previous rolling stands the corresponding intermediate value on the basis of the final control variable always for the immediately following, as seen in the direction of transport, the rolling stand. This achieves high control dynamics. In addition, the flatness error in the inter-stand areas between the rolling stands of the rolling mill remains low. Finally, the rear rolling stands are unloaded.

Preferably, the determination circuits have nodal points at which the controller determines the respective final control value by adding the respective pre-control value for each rolling stand and the respective correction value. In this case, the control device also has bridge elements, by means of which the control device determines the appropriate correction value on the basis of the final control variable, which is always directly preceding, as seen in the transport direction, the rolling stand. As a result, when each rolling stand is activated, the contour change that has already been caused by the previous rolling stand or the previous rolling stands can be taken into account.

Preferably, the bridge elements have delay elements, by means of which the control device delays the respective correction value by the respective delay time with respect to the final control value of the rolling stand immediately preceding, as seen in the transport direction. As a result, a time-coordinated connection of this correction variable to the respective pre-control variable can be carried out.

Preferably, the detection circuits have a corresponding limiting element, by means of which the control device limits the corresponding final control value. In this way, in particular, the adjustment limits of the actuators can be taken into account.

According to the implementation of the invention with a control program, the control device is preferably in the form of a control device with programmable software.

The problem is also solved with the help of a rolling mill with features of claim 13 of the claims. In accordance with the invention, in the case of a rolling mill of the type mentioned above, the control device is in the form of the control device according to the invention.

Brief description of the drawings

The above described features, features and advantages of this invention, as well as how they are achieved, become clearer and more clearly understood in the context of the following description of exemplary embodiments, which are explained in more detail with reference to the drawings. In this case, the schematic image shows:

figure 1: rolling mill for rolling flat products;

figure 2: rear rolling stands rolling mill;

figure 3: several rolling stands of one rolling mill and their management;

figure 4: several rolling stands of one rolling mill and alternative controls belonging to them;

figure 5: modification of figure 3;

figure 6: modification of figure 4 and

Fig. 7: determination chain.

Description of Embodiments

In accordance with figure 1 in the rolling mill 1 is rolled long products. Rolled product 2 is generally a flat product, in particular a strip. However, in some cases, we can talk about long products of a different type, for example, about a profile. This profile may be, for example, an I-profile, an I-beam broadband profile, a channel profile, etc. Rolled material 2 is typically steel, in some cases aluminium. But in some cases, we can also talk about rolling 2 from another metal, for example, from copper.

Rental 2, as a rule, is subjected to rolling mill 1 hot rolling. For example, the rolling mill 1 may be a hot rolling mill for metal strip. But cold rolling is not ruled out. However, regardless of the steel design, the rolling mill 1 has several rolling stands 3a-3f. Figure 1 shows a total of six rolling stands 3a-3f. But the rolling mill 1 can also have a larger number of rolling stands 3a-3f, for example seven or eight rolling stands 3a-3f. Similarly, rolling mill 1 could have fewer rolling stands 3a-3f, such as three, four or five rolling stands 3a-3f. It is decisive that there are at least two rolling stands 3a-3f and that the rolling stands 3a-3f alternately pass the rolling stock 2. The proper transport direction x is the same for the rolling stands 3a-3f. When passing through the respective rolling stand 3a-3f, the rolled stock 2 is rolled, ie its cross section is reduced.

The term "passes through them alternately" should not mean that the rolled stock 2 is first completely rolled in one of the rolling stands 3a-3f, and only then is completely rolled in the next of the rolling stands 3a-3f, etc. Moreover, this term implies that the rental 2, considered as a whole, although rolled simultaneously in several rolling stands 3a-3f, but that each individual section of the rental 2 passes in turn successively through the rolling stands 3a-3f. In addition, figure 1 and figure 2 shows only the work rolls of rolling stands 3a-3f. However, as a rule, the rolling stands 3a to 3f have other rolls, in particular in the case of a glue-type quarto back-up roll or in the case of a stand-type sixth back-up roll and intermediate rolls.

When the terms "preceding" and "subsequent (located after)" are used below, they refer without exception to the sequence in which the roll 2 passes through the rolling stands 3a-3f. For example, rolling stands 3a and 3b are preceding rolling stands 3c, with rolling stands 3b directly preceding rolling stands 3c and rolling stands 3a indirectly preceding rolling stands 3c. Similarly, rolling stands 3d, 3e and 3f are subsequent to rolling stand 3c, with rolling stand 3d immediately following rolling stand 3c and rolling stands 3e and 3f being indirectly following rolling stand 3c. Similar considerations apply to the relationships between the other rolling stands 3a-3f.

The rolling mill 1 and thus also the rolling stands 3a to 3f are controlled by means of a control device 4 . The control device 4 is generally designed as a control device with programmable software. The control device 4 is programmed with a control program 5. The control program 5 includes a program code 6 which can be processed by the control device 4. During operation, the control device 4 executes the program code 6. As a result of the program code 6 being executed by the control device 4, the control device 4 controls the rolling mill 1 in accordance with the operation method, which will be explained in more detail below.

The control device 4 becomes aware of a certain value δQ, which is characteristic of the change in the cross-section with which the rolled product 2 must leave a certain rolling stand 3a-3f of the rolling mill 1. This determined rolling stand 3a-3f may represent the last rolling stand 3f of the rolling mill 1. In the following, however, it is assumed that this is the penultimate rolling stand 3e of the rolling mill 1. If the rolled stock 2 is a strip, the value δQ is generally characteristic of a contour change. This characteristic value δQ may represent the desired change in cross section as such. Alternatively, it can be a value from which the change in cross section can be determined. An example of such a quantity is flatness, for which, in turn, the contour must change. In turn, alternatively, we can talk about the value that is obtained with a given change in the cross section within the definition of activation of the rolling stands 3a-3f. Below, it is assumed that the characteristic value δQ is the change set point itself. That is, the characteristic value δQ is directly called the change setpoint. However, all these considerations also take place when another value is given under the characteristic value δQ, which can be converted into the desired change in the cross section.

It is possible that the change setpoint δQ is given to the control device 4 by means of an appropriate control command from an operator (not shown). As an alternative to the representation in FIG. 2, for example, it is possible for a measuring device 7 to be located at a measurement point, by means of which a certain actual value M of the rolled stock 2 is recorded, for example, in the case of flat rolled stock 2, contour and/or flatness. When the actual value M is registered, the registered actual value M as well as the proper nominal value M* can be input to the adjustment device 8.

The adjustment device 8 can in this case determine the change set point δQ on the basis of the actual value M and the nominal value M*, in particular on the basis of the deviation of the actual value M from the nominal value M*. The adjustment device 8 can be an integral part of the control device 4 .

As already mentioned, within the framework of this embodiment, it is assumed that the change setpoint δQ acts on the penultimate rolling stand 3e of the rolling mill 1. This embodiment is expedient, in particular, within the framework of the already mentioned, unpublished European patent application 18 198 437.8 of 03.10. 2018. However, the action on the penultimate rolling stand 3e of the rolling mill 1 is not necessarily necessary. The change setting δQ, with the exception of the first rolling stand 3a of the rolling mill 1, could also act on some other rolling stand 3a-3f of the rolling mill 1.

The control device 4 has several detection circuits 9b to 9e according to the representation in FIG. One of the detection circuits 9b to 9e, specifically the detection circuit 9e, is for the rolling stand 3e affected by the change setting δQ. In addition, for several rolling stands 3b-3d that precede this rolling stand 3e, one corresponding determination circuit 9b-9e is also assigned. This number of previous rolling stands 3b-3d, for which one determination chain 9b-9e is available within the framework of the method according to the invention, can be selected according to need. The minimum number is 1. However, as a rule, this number is greater than 1. This number can be so large that there is also a determination circuit for the frontmost rolling stand 3a of rolling mill 1. However, it is assumed below that, when viewed in the transport direction x , the determination chain 9b is present only from the second rolling stand 3b of the rolling mill 1.

The following considerations apply without exception to a specific rolling stand 3e and the rolling stands 3b-3d preceding this specific rolling stand 3e, for which there is a definition chain 9b-9e, i.e. here the rolling stands 3b-3e. The first and last rolling stands 3a, 3f of the rolling mill 1 are not considered. In general, within the scope of the present invention, this applies to all rolling stands 3a-3f located after the rolling stand 3e and all rolling stands 3a-3f from the first rolling stand 3a, for which there are no longer definition chains. This state of affairs takes place not only in figure 3, but also in figure 4-7. For the sake of order, it should also be mentioned that the control device 4 determines the control values for these rolling stands 3a, 3f. But these rolling stands 3a, 3f, that is, in the present case, the first and last rolling stands 3a, 3f of the rolling mill 1, are not included in the present invention.

In the determination circuits 9b to 9e, the control device 4, on the basis of the change setpoint δQ, which is determined as such for a particular rolling stand 3e, determines for a certain rolling stand 3e as well as for the previous rolling stands 3b to 3d the corresponding preliminary control value Sb-Se. This determination can be carried out, for example, in the determination blocks 10b-10e.

The control device 4 controls the rolling stands 3b to 3e respectively each of the final control values Sb'-Se'. These final control values Sb'-Se' influence the cross-section with which the rolled product 2 exits each rolling stand 3b-3e of the rolling mill 1. The final control values Sb'-Se' can act on each rolling stand 3b-3e as required. For example, in the case of flat products 2, they can act on the bending of the rolls, on the cooling of the rolls, on the lubrication of the rolls, on the axial displacement of the rolls, on the wedge installation and much more.

The control device 4 determines the final control values Sb'-Se' using the respective preliminary control values Sb-Se'. Within the framework of the embodiment of FIG. 3, the final control values Sbʽ-Seʽ correspond directly and immediately to the preliminary control values Sb-Se. However, if a change in numerical values is still carried out, the preliminary control variables Sb-Se and the final control variables Sb'-Se' are at least as a rule values of the same type. That is, if, purely by way of example, the roll bending is determined as a preliminary control variable Sd, this roll bending can still be increased or decreased within the framework of determining the final control variable Sdʽ. However, the type of control variable, that is to say that it is, for example, the bending of the rolls, is retained.

The determination blocks 10b-10d have a frequency filter 11b-11d. Into each frequency filter 11b-11d, a change amount δQ is input. By means of the frequency filters 11b-11d, the control unit 4 determines the respective pre-control variable Sb-Sd by appropriate frequency filtering of the change setpoint δQ.

By means of the frequency filters 11b-11d, low-pass filtering is performed. That is, below the respective cut-off frequency fb-fd, the signal entered into the respective frequency filter 11b-11d remains unchanged or substantially unchanged, above the respective cut-off frequency fb-fd, the signal entered into the respective frequency filter 11b-11d is filtered out, so that it has more the output signal of the corresponding frequency filter 11b-11d is not contained. By their design, the frequency filters 11b-11d can be made in accordance with the need. For example, they may be in the form of Cauer filters or Butterworth filters. Other embodiments are also possible, for example in the form of PT1 filters.

Under known conditions, each frequency filter 11b-11d may be preceded by a corresponding multiplier 12b-12d. In this case, the change amount δQ in each multiplier 12b to 12d is multiplied by the respective scaling factor Kb to Kd before being input to the respective frequency filter 11b to 11d. Alternatively, the multipliers 12b-12d may be located after their respective frequency filter 11b-11d. In this case, the respective scaling factor Kb-Kd is not multiplied by the input signal of the respective frequency filter 11b-11d, that is, the change amount δQ, but the output signal of the respective frequency filter 11b-11d. In this case, the pre-control values Sb-Sd correspond to the output signal of the frequency filters 11b-11d after being multiplied by the corresponding scaling factor Kb-Kd. The scaling factors Kb-Kd can be determined in particular by the sensitivities of the rolling stands 3b-3d.

Frequency filtering may alternatively be linear or non-linear. In the case of linear frequency filtering, the location of the multipliers 12b-12d before the frequency filters 11b-11d is equivalent to the location after the frequency filters 11b-11d. However, in the case of non-linear frequency filtering, different actions are obtained.

The rolling stands 3b to 3d located in front of a particular rolling stand 3e are always frequency filtered. For the definition circuit 9e, a completely analogous method is possible. It is also selected, according to the image in Fig.3. That is, there is also a frequency filter 11e for the determination circuit 9e and the corresponding determination unit 10e, and under certain conditions there is also a multiplier 12e. The frequency filtering of the determination unit 10e is in this case implemented in such a way that at least those frequency components of the change setpoint δQ that lie above the cutoff frequency fd of the rolling stand 3d are included in the determination of the preliminary control variable Se for a particular rolling stand 3e.

However, the detection circuit 9e does not necessarily require frequency filtering. Therefore, alternatively, it is also possible that no frequency filtering is performed at all when the preliminary control variable Se, ie the change setpoint δQ, is used as it is under known conditions after being multiplied by the corresponding scaling factor Ke. In this case, the preliminary control variable Se already by definition contains those frequency components of the change setpoint δQ which lie above the cutoff frequency fd of the rolling stand 3d.

The frequency filters 11b-11d (and under certain conditions also 11e) are designed in such a way that only the frequency components of the setpoint change δQ that lie below the corresponding cut-off frequency fb-fd or fe . The respective cut-off frequency fb-fd of each previous rolling stand 3b-3d is preferably determined by the transport time from each previous rolling stand 3b-3d to a particular rolling stand 3e. The cut-off frequency fe of a particular rolling stand 3e is either (if no filtering is carried out at all) practically infinite or (if filtering is carried out) is so high that it has practically no effect, i.e. the pre-sensor signal Se contains a signal component having the highest practically usable frequencies.

Here it can be stated, firstly, that the cutoff frequency fb of the rolling stand 3b is smaller than the cutoff frequency fe of the rolling stand 3e. For example, the cutoff frequency fb may be 1 Hz, while for rolling stand 3e it is 20 Hz. In the normal case, the cutoff frequency fb-fe always increases from one rolling stand 3b-3e to another rolling stand 3b-3e. But at least the cutoff frequency fb-fe does not decrease from one rolling stand 3b-3e to another rolling stand 3b-3e. If, according to the example just mentioned, the cutoff frequency fb of the rolling stand 3b is 1 Hz and the cutoff frequency fe of the rolling stand 3e is 20 Hz, for example, the cutoff frequency fc of the rolling stand 3c can be 3 Hz and the cutoff frequency fd of the rolling stand 3d is 8 Hz . However, these numerical values are not to be understood in a limiting manner. They serve only to better explain this principle.

Figure 4 shows one alternative to the method of figure 3. Therefore, below we will dwell in more detail only on significant differences from Fig.3.

Within the method of figure 4, as well as in figure 3, are determined by the preliminary control values Sb-Se, and from them the final control values Sb'-Se'. In contrast to the method of FIG. 3, in which the preliminary control variables Sb-Se are determined for all participating rolling stands 3b-3e directly on the basis of the change setpoint δQ, in the method of FIG. 4 this only occurs for the preliminary control variable Se for a particular rolling stand 3e. That is, only the change setting δQ is directly input to the determination circuit 9e. In the other chains 9b-9d of the definition, the corresponding intermediate value Zb-Zd is entered. In this case, the control device 4 determines the preliminary control values Sb-Sd for the previous rolling stands 3b-3d by frequency filtering the corresponding intermediate value Zb-Zd. The respective intermediate value Zb-Zd is in turn determined by the controller 4 on the basis of the final control variable Scʽ-Seʽ always for the immediately following rolling stand 3c-3e. The determination is carried out in the intermediate blocks 13c-13e, which are part of the determination circuits 9c-9e. In the simplest case, the intermediate blocks 13c-13e are made in the form of simple taps for taking readings.

3 and 4, it is possible for the controller 4 to always take into account the respective preliminary control variable Sc-Se when determining each final control variable Scʽ-Seʽ. Preferably, however, the embodiments of FIGS. 3 and 4 are modified according to the depictions of FIGS. 5 and 6. Within the modification of FIGS. 5 and 6, the control device 4 determines each final control variable Scʽ-Seʽ for each rolling stand 3c-3e based on the preliminary control variable Sc -Se for each rolling stand 3c-3e and the corresponding Scʽʽ-Seʽʽ correction value. In particular, the determination circuits 9c-9e have nodal points 14c-14e at which the control device 4 determines each final control variable Scʽ-Seʽ by adding the respective preliminary control variable Sc-Se for each rolling stand 3c-3e and the respective Scʽʽ-Seʽʽ corrections.

The control device 4 determines the corresponding correction value Scʽʽ-Seʽʽ on the basis of the preliminary control value Sb-Sd of the always immediately preceding rolling stand 3b-3d. In particular, the control device 4 has bridge elements 15c-15e into which the pre-adjustment value Sb-Sd of the always immediately preceding rolling stand 3b-3d is input and by means of which the control device 4 determines the corresponding correction value Scʽʽ-Seʽʽ. In particular, the control device 4 in the multipliers 16c-16e of the bridge elements 15c-15e can, for example, perform scaling with an appropriate scaling factor Kc'-Ki'. The scaling factors Kc'-Ki', like the scaling factors Kb-Kd, can be determined in particular by the sensitivities of the rolling stands 3b-3e.

An exception to this method is for the frontmost rolling stand 3b, which has a definition chain 9b-9d. Its preliminary control variable Sb is no longer corrected by a correction value within the framework of determining the appropriate final control variable Sbʽ. This is the case, as far as the present invention is concerned, even if the respective rolling stand 3b is preceded by at least one more rolling stand 3a of the rolling mill 1, here the rolling stand 3a.

As shown in FIGS. 5 and 6, the bridge elements 15c-15e preferably also have delay links 17c-17e. By means of these delay links 17c-17e, the control device 4 delays the respective correction amount Scʽʽ-Seʽʽ with respect to the precontrol value Sb-Sd of the immediately preceding rolling stand 3b-3d by a corresponding delay time Tc-Te. This corresponding delay time Tc-Te is generally determined by the substantially corresponding transport time that the rolling stock 2 needs to pass from the respectively preceding rolling stand 3b-3d to the given rolling stand 3c-3e. That is, the respective delay time Tc-Te is generally determined by the distance from a given rolling stand 3c-3e to the respective immediately preceding rolling stand 3b-3d and the corresponding rolling speed vc-ve at which the rolling stock 2 exits from the respective immediately preceding rolling stand 3b -3d or, respectively, enters the corresponding rolling stand 3c-3e. Under known conditions, the corresponding delay time Tc-Te, which is derived from the corresponding transport time, can still be scaled by an appropriate scaling factor. This corresponding scaling factor is typically 0.5 to 2.0, most commonly 0.8 to 1.25. The scaling factors for delay links 17c-17e may be defined uniformly or individually.

Within the embodiments of FIGS. 3-6, frequency filtering is performed in the corresponding frequency filter 11b-11e. Figure 7 shows one of the possible embodiments of the definition chain 9c. For chains 9b, 9d and 9e of the definition, the same reasoning takes place.

According to the image in Fig.7, a limiting element 18 can be located after the determining block 10c. In this case, the control device 4 limits the output signal of the determining block 10c by means of the limiting element 18. Since there is an anchor point 14c, the restrictor element 18 is located in the signal flow after the anchor point 14c. Since there is an intermediate block 13c, the restrictor element 18 precedes the intermediate block 13c in the signal flow.

The control device 4, as already mentioned, is generally designed as a control device with programmable software. Therefore, the operating principle of the control device 4 is determined by the control program 5. Therefore, the control program 5 and the execution of its program code 6 by the control device 4 cause the control device 4 to implement the above-mentioned functional units, for example, the determination circuits 9b-9e, or the intermediate blocks 13c- 13e or bridge elements 15c-15e as software blocks.

The present invention has many advantages. In particular, the control actions for compensating for the change setpoint δQ are distributed over several rolling stands 3b-3e, so that the individual rolling stands 3b-3e only need to be activated to a limited extent. However, by compensating for the δQ change setpoint, high dynamics can be achieved.

Although the invention has been illustrated and described in detail in the preferred embodiment, the invention is not limited to the disclosed examples, and other variations can be derived from the skilled person without departing from the scope of the invention.

LIST OF REFERENCES

1 rolling mill

2 rental

3a-3f rolling stands

4 Control device

5 Control program

6 Program code

7 Measuring device

8 Adjusting device

9b-9e Definition circuits

10b-10e Definition blocks

11b-11e Frequency filters

12b-12e Multipliers

13c-13e Intermediate blocks

14c-14e Anchor points

15c-15e Bridge members

16c-16e Multipliers

17c-17e Delay links

18 Limiting element

fb-fe Cutoff frequencies

Kb-Ke Scaling Factors

Kcʽ-Keʽ Scaling factors

M Actual value

M* Rated value

Sb-Se Preliminary control variables

Sbʽ-Seʽ Final control values

Scʽʽ-Seʽʽ Correction values

Tc-Te Delay times

vc-ve Rolling speeds

x Direction of transport

Zb-Zd Intermediate value

δQ Setpoint change/characteristic value

Claims (57)

1. Method for controlling a rolling mill (1) for rolling rolled metal (2), - at the same time, the rolling mill (1) contains several rolling stands (3a-3f), through which the rolled metal (2) passes in turn in the transport direction (x) common for these rolling stands (3a-3f), so that the rolled metal (2) alternately rolled in rolling stands (3a-3f), - at the same time, the control device (4) of the rolling mill (1) on the basis of a certain value (δQ) characteristic of the change in the cross section with which the rolled metal (2) must exit a certain rolling stand (3e) of the rolling mill (1), determines for of this rolling stand (3e) and several preceding this rolling stand (3e), when viewed in the transport direction (x), the rolling stands (3b-3d) of the rolling mill (1) first with the corresponding preliminary control value (Sb-Se) and using this corresponding preliminary control variable (Sb-Se) the corresponding final control variable (Sb`-Se`), - in this case, the corresponding final control value (Sb`-Se`) influences the cross-section with which the rolled product (2) leaves each rolling stand (3b-3e) of the rolling mill (1), - in this case, the control device (4) activates the rolling stands according to this final control value (Sb`-Se`), different in that - that the control device (4) determines the respective preliminary control variable (Sb-Sd) for the previous rolling stands (3b-3d) by appropriate frequency filtering of said characteristic quantity (δQ) or the respective intermediate value determined from the characteristic quantity (δQ) (Zb- Zd); - frequency filtering is implemented in such a way that the determination of the respective pre-adjusting variable (Sb-Sd) for the preceding rolling stands (3b-3d) always includes only the frequency components of the characteristic quantity (δQ) that lie below the respective cut-off frequency (fb-fd) , and - in relation to several previous ones, when viewed from a certain rolling stand (3e) in the direction (x) of the transport, rolling stands (3b-3d) of the rolling mill (1) and, when viewed in the direction (x) of the transport, the cutoff frequency (fb- fd) from one rolling stand (3b-3d) to another rolling stand (3b-3d) always remains constant or increases; - the control device (4) determines the preliminary control variable (Se) for a certain rolling stand (3e) in such a way that at least those frequency components of the characteristic quantity (δQ ) that lie above the cutoff frequency (fd) of the rolling stand (3d) immediately preceding the determined rolling stand (3e) as viewed in the transport direction (x). 2. The method according to claim 1, different in that - that the control device (4) determines the preliminary control variable (Se) for a certain rolling stand (3e) of the rolling mill (1) on the basis of the indicated characteristic quantity (δQ), in particular by frequency filtering this characteristic quantity (δQ), - the control device (4) determines the preliminary control values (Sb-Sd) for the previous rolling stands (3b-3d) by frequency filtering the corresponding intermediate value (Zb-Zd), and - the control device (4) determines the appropriate intermediate value (Zb-Zd) on the basis of the final control value (Sc'-Se') always for the immediately following rolling stand (3c-3e) as viewed in the transport direction (x). 3. The method according to claim 1 or 2, different in that - that the control device (4) determines the appropriate final control value (Sc`-Se`) for each rolling stand (3c-3e) based on the preliminary control value (Sc-Se) for each rolling stand (3c-3e) and the corresponding value (Sc``-Se``) corrections, and - the control device (4) determines the appropriate correction value (Sc``-Se``) based on the preliminary control value (Sb-Sd) of each immediately preceding rolling stand (3b-3d) as viewed in the transport direction (x). 4. The method according to claim 3, different in that - that the control device (4) delays the corresponding correction value (Sc``-Se``) by the corresponding delay time (Tc-Te) relative to the pre-control value (Sb-Sd) of the immediately preceding one, when viewed in the transport direction (x), rolling stand (3b-3d). 5. The method according to any one of claims 1-4, different in that - that the control device (4) limits the final control values (Sb`-Se`) by means of an appropriate limiting element (18). 6. Control device for a rolling mill (1) for rolling rolled metal (2) from metal, while the rolling mill (1) has several rolling stands (3a-3f), through which the rolled metal (2) passes in turn in a single rolling stand for these rolling stands (3a-3f) direction (x) of transport, so that the rolled product (2) is alternately rolled in the rolling stands (3a-3f), - in this case, the control device has circuits (9b-9e) for determining, by means of which the control device, based on a certain value (δQ), characteristic of the change in the cross section with which the rolled product (2) should exit a certain rolling stand (3e) of the rolling mill ( 1), determines for this rolling stand and several preceding this rolling stand (3e), when viewed in the direction (x) of transport, the rolling stands (3b-3d) of the rolling mill (1) firstly determine the corresponding preliminary control value (Sb-Se) and using this corresponding preliminary control variable (Sb-Se) the corresponding final control variable (Sb`-Se`), - in this case, the corresponding final control value (Sb`-Se`) influences the cross-section with which the rolled product (2) leaves each rolling stand (3b-3e) of the rolling mill (1), - in this case, the control device activates the rolling stands (3b-3e) according to this final control value (Sb`-Se`), different in that - that the circuits (9b-9d) for determining the previous rolling stands (3b-3d) have frequency filters (11b-11d), by means of which the control device determines the appropriate preliminary control value (Sb-Sd) for the previous rolling stands (3b-3d) by the corresponding frequency filtering characteristic value (δQ) or determined from the characteristic value (δQ) of the corresponding intermediate value (Zb-Zd); - the frequency filters (11b-11d) are designed in such a way that only the frequency components of the characteristic quantity (δQ) that lie below the corresponding cut-off frequency are always included in the determination of the respective pre-adjusting variable (Sb-Sd) for the previous rolling stands (3b-3d) (fb-fd), and - in relation to several previous ones, when viewed from a certain rolling stand (3e) in the direction (x) of the transport, rolling stands (3b-3d) of the rolling mill (1) and, when viewed in the direction (x) of the transport, the cutoff frequency (fb- fd) from one rolling stand (3b-3d) to another rolling stand (3b-3d) always remains constant or increases, and - the circuit (9e) for determining for a certain rolling stand (3e) is designed in such a way that the determination of the preliminary control variable (Se) for a certain rolling stand (3e) includes at least those frequency components of the characteristic quantity (δQ) that lie above the limit the frequency (fd) of the rolling stand (3d) immediately preceding, as seen in the direction of transport (x), the determined rolling stand (3e). 7. The control device according to claim 6, different in that - that the control device enters into the determination circuit (9e) for a certain rolling stand (3e) of the rolling mill (1) a characteristic value (δQ), - the control device enters in the determination circuits (9b-9d) for the previous rolling stands (3b-3d) the corresponding intermediate value (Zb-Zd), and - the control device has intermediate blocks (13c-13e), by means of which the control device determines for the previous rolling stands (3b-3d) the corresponding intermediate value (Zb-Zd) on the basis of the final control variable (Sc`-Se`) always for the immediately following , as viewed in the transport direction (x), of the rolling stand (3c-3e). 8. Control device according to claim 6 or 7, different in that that the determination circuits (9c-9e) have nodal points (14c-14e) at which the controller determines the respective final control variable (Sc`-Se`) by adding the respective preliminary control variable (Sc-Se) for each rolling stand (3c -3e) and the corresponding amount (Sc``-Se``) of the correction, and - the controller has bridge elements (15c-15e) by means of which the controller determines the appropriate correction value (Sc``-Se``) based on the pre-adjustment value (Sb-Sd) always immediately preceding when viewed in the direction (x) transportation, rolling stand (3b-3d). 9. The control device according to claim 8, different in that that the bridge elements (15c-15e) have delay links (17c-17e) by means of which the control device delays by an appropriate delay time (Tc-Te) the corresponding correction value (Sc``-Se``) with respect to the pre-control value (Sb- Sd) immediately preceding, as viewed in the transport direction (x), the rolling stand (3b-3d). 10. The control device according to any one of claims 6-9, different in that that the determination circuits (9b-9d) have a corresponding limiting element (18) by means of which the control device limits the corresponding final control variable (Sb'-Se'). 11. The control device according to any one of claims 6-10, different in that that the control device is in the form of a control device with programmable software. 12. Flat rolling mill (2), - in this case, the rolling mill contains several rolling stands (3a-3f), through which the rolled metal (2) passes in turn in the transport direction (x) common for these rolling stands (3a-3f), so that the rolled metal (2) is alternately rolled in the rolling mills crates (3a-3f), - in this case, the rolling mill has a control device (4) that controls the rolling stands (3a-3f) of the rolling mill, different in that that the control device (4) is made in the form of a control device according to any one of claims 6 to 11.

Images