WO2012032071A1

WO2012032071A1 - Method for producing steel strips by continuous rolling or semi-continuous rolling

Info

Publication number: WO2012032071A1
Application number: PCT/EP2011/065426
Authority: WO
Inventors: Gerald Hohenbichler; Alois Seilinger
Original assignee: Siemens Vai Metals Technologies Gmbh
Priority date: 2010-09-08
Filing date: 2011-09-07
Publication date: 2012-03-15
Also published as: RU2013114982A; RU2579842C2; KR101802898B1; UA107981C2; EP2428288A1; CN103079719B; CN103079719A; EP2428288B1; KR20130099091A

Abstract

The invention relates to a method for producing steel strips (1) by continuous rolling or semi-continuous rolling, wherein a slab (3) is first of all cast in a casting installation (2), the slab (3) is rolled to form a rough strip (3') in a rough-rolling mill train (4), the rough strip (3') is heated in a furnace (7) and the rough strip (3') is finish-rolled in a finishing rolling mill train (5) to a predetermined final thickness and at a predetermined final rolling temperature. In order to ensure the desired final thickness and final rolling temperature of the steel strip, it is provided that, when the entry temperature (T2) and/or the entry mass flow of the rough strip (3') are/is changed, a new pass sequence is selected, by way of which the desired final thickness and the desired final rolling temperature are achieved, wherein the final engaged rolling stand of the finishing rolling mill train (5) is taken out of rolling engagement or a rolling stand of the finishing rolling mill train, said rolling stand being connected downstream of the final engaged rolling stand, is brought into rolling engagement and additionally allows the energy supplied to the furnace (7) and/or the finishing rolling mill train (5) to be minimized.

Description

description

Method for producing steel strips by continuous rolling or semi-endless rolling

FIELD OF THE INVENTION

The invention relates to a method for producing

Steel strips by endless rolls or semi-endless rolls, wherein first in a casting plant, a slab is poured, the slab is rolled in a roughing mill to a pre-strip, the pre-strip is heated in an oven and heated

Vorband in a finishing mill on a given

Final thickness and a predetermined final rolling temperature is finished rolled.

One speaks of "continuous rolls" when a casting plant is so connected to a rolling mill, that the cast in the casting plant slab directly - without separation from the straight

cast slab part and without intermediate storage - fed into a rolling mill and rolled there to the final thickness. The beginning of the slab can therefore already be finished rolled to a steel strip to the final thickness, while the casting plant continues to pour on the same slab, so there is no end of the slab. One speaks also of directly coupled operation or endless operation of the casting and rolling plant.

In the so-called "semi-continuous rolling" the cast slabs are divided after casting and fed the separated slabs without intermediate storage and cooling to ambient temperature of the rolling mill.

The emerging from the casting slab is usually descaled, pre-rolled, the resulting pre-strip is heated in an oven and finished in the finishing train

rolled. In the finishing train usually hot rolled, that is, the rolling stock during rolling a Temperature above its recrystallization temperature. For steel, this is the range above about 720 ° C, usually is rolled at temperatures up to 1200 ° C warm.

When hot rolling steel, the metal is usually in the austenitic state, where the iron atoms are cubic

are arranged surface centered. One then speaks of rolls in the austenitic state, when both the initial and the final rolling temperature are in the austenitic region of the respective steel. The austenite area of a steel depends on the steel composition, but is usually above 800 ° C. In order to safely roll in the austenitic state during the entire process of finish rolling, usually in the pass plans, a correspondingly high final rolling temperature

predetermined.

STATE OF THE ART From the prior art, continuous rolling or semi-continuous

Continuous rolling of steel strips well known, as well as the disadvantages that arise from it: especially in

Continuous rolling transfers to the rolling process every variation in the casting process due to the direct coupling of the casting plant and the rolling mill. At the sprue, at a staggering

Casting speed and disturbances of the casting machine can lead to fluctuations in the speed and the temperature of the pre-strip, which in turn affects the

Finish rolling of the steel strip and can lead to quality variations. In particular, the mass or

Change the volume flow of the pre-strip and / or the temperature of the pre-strip. The mass or volume flow changes z. B. if, with the same thickness and width of the Vorbandes the speed of the Vorbandes changes or if at the same width and speed of the

Vorbandes the thickness changes. Instead of the volume flow, the width-specific volume flow is often used in the rolling technique, ie as a volume flow per unit width (1 m), as a product of thickness of a band and

Belt speed can be displayed, especially if the width of the tape plays no special role for the process under consideration. This often applies when the width is at least seven to ten times the thickness. The (broad specific) mass flow is known to be obtained by multiplying the (specific volume) volume flow by the density of the belt. Fluctuations in temperature and / or the

Width-specific mass or volume flow can lead to the actual final rolling temperature, ie the temperature of the steel strip after the last mill stand of the finishing train, deviating from the desired final rolling temperature, which can be associated with quality losses. Thus, as an essential product property, the microstructure of the steel strip may deviate from the desired microstructure, such as an austenitic microstructure. But it can also come to deviations from the desired thickness or the desired profile of the steel strip. But the quality of the finished steel strip can also be so bad that it has to be treated as scrap.

In the conventional hot rolling of slabs or slivers, which are separated from the cast strand, usually a change in the final thickness of the steel strip is only allowed from one slab or a preliminary sliver to the next slab or to the next slate. Likewise, the temporal

Inlet temperature curve of the Vorbandes in the

Finish rolling mill and the volume flow curve

(Thickness change, width change) and in particular a fixed finish rolling temperature (on the last roll stand) for a slab or an opening band always set in advance. During rolling of the same slab or sliver, deviations from those intended or expected will occur

Gradients usually not allowed. Slowly decreasing inlet temperatures of the pre-strip when entering the

Finishing mill will be over an increase in Speed of the pre-strip (speed-up) compensated, so that the Stichabnahmeperteilung on the individual stands and the final rolling temperature can still be approximated. Changes to the pass plan, ie a distribution of the sampling on the individual rolling stands, are carried out in the idle time between leakage of a finished steel strip and the arrival of the next Vorbandes.

There are no critical operating conditions in the finishing mill because the basic rolling mill control has already been determined in advance for each pre-strip. Sudden changes in the inlet temperature of the Vorbandes in the

Prefabricated rolling mill lead to increased rejects, sudden changes in the volume flow at the inlet of the pre-strip in the finishing train are excluded.

In semi-endless rolling, the usually overlong slab is separated from the strand of the casting plant, a newly incoming slab can be braked to the pass schedule of the finishing train due to changes in properties (temperature, width, thickness, speed of the slab or Vorbands) or because of the Recalculation of a new final thickness.

When fully continuous endless rolling accounts for the

Idle times between the individual metal bands or

Slabs and all changes of the operating condition of the

Composite system must be carried out during load operation, ie while a steel strip is being rolled in the finishing train.

To be sufficiently high for relevant procedures

To ensure final rolling temperature, proposes the DE 10 2007 058 709 AI, a functional relationship of

Casting speed or mass flow on the one hand and

On the other hand, to determine the final rolling temperature for a given number of active stands and different final thicknesses, the optimum number of active stands is provided

Specifying a specific casting speed or mass flow, with which a desired Endwalztemperatur is achieved and optionally a number of rolling stands drive so that only the optimum number of rolling stands is active.

But only by achieving a desired

Endwalztemperatur can not be ensured that a certain final thickness of the steel strip is achieved. According to DE 10 2007 058 709 AI, paragraph 20, this is not at all desirable. PRESENTATION OF THE INVENTION

It is therefore an object of the invention to provide a method which, in the event of fluctuations in the mass or

Volume flow and / or the speed of the Vorbandes - if technically possible - the achievement of the desired

Final thickness and - at least - that ensures the achievement of the desired final rolling temperature of the steel strip, so reaching that final thickness or that Endwalztemperatur that is desired and achievable without the aforementioned fluctuations in undisturbed operation of the endless compound system. Such a procedure is also in the case of starting the

Endless compound system applicable, if the broadly specific mass or volume flow of the Vorbandes only slowly

rises.

The problem is solved by that

- When changing the inlet temperature of the Vorbandes when

Entering the finishing train by more than 1 K / second, in particular by more than 5 K / second, and / or

- When changing the inlet mass flow of the Vorbandes when

Entering the finishing train by more than 0.2% / second, in particular by more than 1.5% / second,

a new stitch plan is selected, with which the desired final thickness and the desired final rolling temperature is achieved, wherein the last engaged rolling stand of

A finishing train is brought out of the rolling engagement or a rolling mill of the finishing train is brought into rolling engagement, the last engaged rolling mill is downstream, under the - substantial - secondary condition that a minimization of the energy that is supplied to the furnace and / or the finishing train is achieved,

and that the inlet temperature of the Vorbandes by controlling the furnace and the rolling stands according to the new

Stitch plan to be set.

Changes in the inlet temperature or the

Inlet mass flow are recorded by measuring instruments, whereby the usual measures are taken to ensure the validity and accuracy of the signals, which are sometimes already integrated in the measuring instruments, or in which

Measured value processing can be carried out on a statistical basis. In particular, so-called

Filtering methods applied so that only statistically

significant and freed from the usual signal noise

Measured values for assessing the current constancy or

Variability of inlet mass flow or

Inlet temperature are used.

Thus, if there is a significant change in the mass flow and / or temperature of the pre-strip as it enters the finishing train, then a new pass schedule must be used to continue to achieve the desired final thickness and finish rolling temperature of the steel strip. A change in the inlet temperature of the pre-strip when entering the finishing train by more than 1 K / second or

Inlet mass flow of more than 0.2% / second corresponds to the conditions when starting up the cast roll compound plant and represents a constant or slow change of

Inlet temperature and inlet mass flow. The values of more than 5 K / second or more than 1.5% / second correspond to the values of a fault of the cast roll composite system and represent a significant and usually also suddenly occurring change in inlet temperature and inlet mass flow. In the determination of the new stitch plan, the desired final thickness and finish rolling temperature of the steel strip is attempted while minimizing the in the furnace and / or in the

Roughing mill for energy used to achieve.

Energy can be saved, if not necessarily

required rolling stand is driven up, which is then no longer in engagement with the steel strip and where the steel strip passes through this mill without changing the thickness. In this case, however, only a rolling stand is ever driven up and also only that which was previously in the past in engagement with the steel strip. Thus, if only six of the rolling mills of the finishing train were previously in engagement with the steel strip, ie "active", then only the fifth could be used

Roll stand may be raised, and not the fourth.

But it may also be necessary, a rolling mill

turn on, because otherwise the desired final thickness and

Endwalztemperatur can not be achieved, even if this leads to an increase in the required energy. At the same time, only one mill stand per change in the pass schedule

switched on and only that which is directly downstream of the last in-service roll stand. Thus, of the six rolling mills of the finishing train last - before the stitch plan change - only the first four in engagement with the steel strip ("active"), so only the fifth mill stand can be switched, and not the sixth, which in this case the When minimizing the energy, therefore, care must always be taken, for example by formulating a corresponding boundary condition in a mathematical process model, that the desired final rolling thickness is achieved without change.

Energy can also be saved if the

Inlet temperature is lowered, so that temperature with which exits the opening band from the oven and into the

Finish rolling mill enters. This will be particularly possible if the number of active rolling stands of the finishing train is reduced by one and in the

remaining active rolling stands Thickness reductions of the steel strip close to the maximum possible reduction degrees

(Relative change in thickness of the steel strip after and in front of the rolling stand) carried out, because thereby more rolling heat dissipative forming heat is produced, which is the steel strip

additionally heated. The maximum possible reduction rates are on the one hand due to the material properties of the

Steel band itself determined, on the other hand by the

Roll stand, which can apply only a finite rolling force. It does not need to be specifically mentioned that when

According to the invention, only settings of the rolling stands within predefined limit values are useful in order to achieve the desired results

Composite plant and in particular the finishing train not to be damaged. Thus, for rolling stands, for example, maximum permissible rolling and bending forces are predetermined, the exceeding of which may lead to damage to the rolling stands or to roll breakage. Furthermore, there are limits for the maximum possible speed of the steel strip, which can be determined both by the drive of the rolling stands and / or the reels and by the properties of the steel strip, for example, to prevent damage thereof.

But if the individual active stands of the

Fertigwalzstraße have not yet reached the limits, it is provided according to the invention to open the last active rolling stand with increasing mass flow of the Vorbandes and distribute the Stichabnahmen on the then remaining active rolling stands. This can save energy for the stove because of the now higher

Thickness changes per rolling stand more energy in the form of

Heat of transformation is introduced into the steel strip and the steel strip is thereby heated. The term "if technically possible" in the task (more precisely: if possible within plant limits) is therefore to be understood that the originally desired final thickness may be sought only if this is within the applicable limits for the finishing train, in particular the maximum permissible Rolling and bending forces, which is usually possible when the inlet temperature or the

Increase inlet flow and an additional rolling stand is switched on. The originally desired final thickness can, however, possibly not be maintained if the inlet temperature or the inlet mass flow decrease and a rolling mill is driven up, because then in some cases the necessary to maintain the final thickness rolling and bending force of the finishing train would exceed the corresponding limits. It must be allowed then so a greater final thickness, which must not be a disadvantage if in the

Rolling program later anyway a larger final thickness is to roll.

If a rolling mill is closed or driven up, then in any case the Stichabnahmen, so the

Thickness changes per rolling stand, are redistributed to the individual then active rolling stands. The distribution of the pass decreases on the individual rolling stands is what the person skilled in the art refers to as the "pass schedule." However, a pass schedule also contains further information about the rolling process, as is well known to the person skilled in the art.

The rolling stock, ie the steel strip, is described at any time during the rolling process and thus also in the pass schedule, at least by the following variables: speed, thickness,

Temperature and relative profile (thickness of the band in the middle relative to the edge). Each roll stand is characterized - also in the pass chart - at least by the following variables, which simultaneously represent the manipulated variables of the roll stand: peripheral speed of the work rolls, rolling force and bending force. It can be provided that the new stitch plan is determined during the ongoing rolling process. In doing so, the new pass schedule can be recalculated with the aid of the current measurement data of the rolling process and therefore particularly accurate.

Of course it would also be possible to have different ones

Predicting pass plans with various data of the rolling process before the rolling process and in a database

store, so then with a significant change in the inlet temperature and / or the inlet mass flow a suitable new stitch plan can be selected from the stored stitch plans. But there is always only a finite one

If the number of pass-through plans can be predicted and stored in a database, and these will then not be entirely suitable for the given rolling process, this procedure will lead to comparatively worse results than the calculation of the new pass-plan during the rolling process (online calculation).

Best of the new stitch plan according to the invention is created by means of a mathematical process model that the

Rolling process simulates at least all rolling stands of the finishing train. During the ongoing rolling process, the

Rolling in the finishing train due to

Process model recalculated several times per minute.

In each calculation step, for example, the

Final rolling temperature, the final thickness per framework

required rolling and bending forces as well as the energy requirements of the finished Walwalstraße and the furnace are calculated. Then the distribution of the rolling force on the individual rolling stands and also the number of active rolling stands is varied and thereby determined whether an active rolling mill would be less energetically advantageous in compliance with plant limits and operational limits.

Those skilled in the art are familiar with such mathematical process models, some examples of which are in the Publication EP 1 014 239 A1 called, where usually several sub-models are used: rolling force models,

Speed models, temperature models and profile models

In order to achieve a minimization of the energy that is supplied to the furnace and / or the finishing train, a so-called target function can be formed, which is a

mathematical optimization, such as B. one

And the thus determined function values of the objective function are used to create a stitch plan.

For example, the function values of the objective function determined by the optimization can be used directly as parameters of the stitch plan. One possible embodiment is that the objective function is a function of

Material variables of the rolling stock, such as speed, thickness, temperature, relative profile, and / or control variables such as peripheral speed, rolling force, bending force.

In the subject invention, the objective function will be the energy supplied to the furnace and / or the finishing train so that, for example, a very low energy pass schedule is calculated. The fact that at least one condition imposed on the pass schedule in the form of a limit value is taken into account in the optimization as a constraint, be in a simple manner

technical or technological limits are included in the optimization. Furthermore, at least one

Condition that specifies a fixed value for a control or state variable when optimizing as

Secondary condition taken into account. As a result, fixed values, just the desired final thickness and the

Final rolling temperature, are included in the optimization.

Which mathematical methods are used concretely for the optimization, is left to the expert and becomes not explained here. Some applicable methods are given in the already mentioned EP 1 014 239 AI.

If it is not possible to find a new stitch plan with the desired final thickness and finish rolling temperature, then the stitch plan can be used for which the solution with the smallest violation of the secondary conditions occurs under given constraints. For example, a deviation from the desired final thickness may be allowed if such a product had to be manufactured anyway at a later date according to the production plan. But at least a final rolling temperature can be achieved, where the metal is in the austenitic state.

Specifically, it can be provided that, with the process model of the stitch plan, at least the final rolling temperature of the

Steel strip, the final thickness of the steel strip, and the

the number of rolling stands is varied and the associated energy for the rolling mills and the furnace is determined, and if a reduction in the value of the rolling mills and the furnace is observed in accordance with preset limits for the settings of the rolling mills and the furnace common energy needs, which will be used as the basis for the new

But it can also be sought only a minimization of the furnace energy, it is then provided that at least with the process model of the stitch plan

Final rolling temperature of the steel strip, the final thickness of the

Steel band, and the energy demand of the furnace is calculated, wherein the number of rolling mills varies and the associated energy is determined for the furnace, and if adhering to predetermined limits for the

Settings of the rolling stands and the furnace at a

Variation results in a reduction of energy for the furnace, this is based on the new pass schedule. Another way to minimize the energy required for the furnace is to change the thickness of the pre-strip. Here are the rolling stands of

Include the roughing mill in the recalculation plan to be recalculated. Although the thinner the pre-band is, the lower the energy required to heat the pre-band in the oven. However, it is intended here, at given values for inlet mass flow, Endbanddicke and

Endwalztemperatur to select the Vorbanddicke so high that the active rolling stands of the finishing train as close as possible to the maximum possible reduction levels to replace the energy saved at the furnace by the dissipative forming heat. The temperature of the steel strip as it exits the furnace, which is proportional to the energy supplied to the furnace, should generally not exceed 1250 ° C, more preferably be less than 1220 ° C. If the reduction rates in the

However, rolling stands of the finishing train can be increased, the temperature of the steel strip at the exit from the furnace can be lowered to, for example, about 1090 ° C.

The method according to the invention can be used both for endless rolling or semi-endless rolling. In particular, it can be used to start and run a cast roll compound plant after a casting-rolling break, so the daily restart of the system and not just one

System standstill due to an error.

If it is used for semi-endless rolling, then there is

Basically, there are two possibilities when the change of stitch plan takes place and thus when a rolling stand is switched on or set up to execute the new stitch plan.

The pre-band to be rolled can already be found in the

Finishing mill are located when a rolling stand in

Rolling engagement or brought out of the rolling engagement. This corresponds to the continuous rolling process, where the endless steel strip runs through all the rolling stands. Semi-endless rolling produces from the split slabs several pre-bands that are relatively close to each other in the Run in finishing mill, usually only with a time interval of less than 20 seconds, preferably less than 10 seconds, in particular less than five seconds. In this first variant, the connection or driving of a rolling mill is carried out regardless of whether a steel strip is in the finishing train or not. Therefore, it is likely to take place when there is just a steel strip in the relevant rolling stand.

In the second variant, it is provided that the pre-strip to be rolled in the semi-endless rolling only in the

Finish rolling mill enters if a rolling stand has been opened or closed according to the new pass schedule. That means it's a pair of scissors in front of the finishing train

must be arranged, which cuts through the sub-band, so that part, which is already in the finishing train

can be accelerated out of the finishing mill, while not yet in the finishing mill part as long as not in the finishing mill (or at least not in the rolling mill to be adjusted) enters until the corresponding rolling mill according to the new

Stitch plan has been set. The severing of the

Vorbandes is not a disadvantage, because a finished strip is usually too long for a bunch and therefore must be cut anyway after the finishing train at least once to wind it up to at least two coils. So you can cut the steel strip instead of after

Complete the finishing stand already in front of the finishing stand and at the same time make a break for the necessary changeover to the new pass schedule.

When starting or connecting a roll stand, the roll gap per second can be increased by about 5 mm or

be downsized.

The inventive method can with the help of a

Computer program product to be executed at his Loading and Performing on a computer determines a pass schedule according to one of the method claims.

With the method according to the invention can be ensured that the finish rolling despite considerable or

sudden reduction of inlet temperature and / or

wide-specific inlet mass flow, for example, due to faults in the furnace, the descaling or the casting, can be done with the highest possible reliability.

It can be either the total energy consumption of the furnace plus finishing train or only the energy consumption of the furnace, especially at constant or slowly changing

Input state (inlet temperature and mass flow)

be minimized.

The inventive method requires only a small control effort in the actuators for the strip temperature (oven, cooling).

The inventive method allows a very early start of finish rolling after casting start, even if the

Inlet mass flow is still relatively low. By the

Joining from one rolling stand to another in the

Finishing mill, the strip thickness can be gradually reduced when the inlet mass flow and / or the heating power of the furnace are gradually increased.

BRIEF DESCRIPTION OF THE FIGURES

The invention is based on a schematic figure

exemplified. The figure shows the side view of a cast roll compound system. WAYS FOR CARRYING OUT THE INVENTION

In the figure, an embodiment of a Gießwalz- compound plant is outlined on the inventive Method for producing steel strips 1 can be carried out. There is a vertical casting plant 2, are poured in the slabs 3, for example, 70 mm thickness. On a pair of scissors 12, the semi-endless rolling could

Cutting to a desired slab length done. It is followed by a first oven 6, in which the slab 3 is brought to about 1000 to 1200 ° C rough rolling temperature Tl and in which there is a certain temperature compensation in the width direction. The oven 6 can also be omitted.

Then the rough rolling takes place in a rough rolling 4, which may consist of a - as here - or of several stands and in which the slab 3 is rolled to an intermediate thickness or Vorbanddicke. During roughing takes place

Conversion of cast structure into the finer-grained rolling structure instead. It is also possible to dispense with the use of a scale washer 13 or another system for descaling upstream of the rough rolling mill 4.

Behind the framework of Vorwalzstrasse 4, another furnace 7 for the pre-band 3 ^'is arranged. The furnace 7 may preferably be designed as an induction furnace, but also as a conventional furnace or as a high-temperature furnace with flame treatment. Therein, the pre-strip 3 ^{'is brought} relatively uniformly over the cross section to the desired inlet temperature T2 for the inlet to the finishing train 5, wherein the

Inlet temperature T2 is usually between 1090 ° C and 1250 ° C depending on the steel grade and subsequent rolling in the finishing train 5.

After heating in the oven 7, the finish rolling in the multi-stand finishing train 5 to the desired final thickness and final rolling temperature and then the

Strip cooling in a cooling section 14 and ultimately the

Winding by means of reel 15. The scale washer 13 before and / or between the rolling stands 51-56 can also be dispensed with. If now when starting up the Gießwalz compound system, such as after a break in operation, the inlet mass flow of the

Vorbandes 3 ^' in the finishing train 5 is still relatively low (<70% of the intake mass flow during normal operation), is rolled only with the first three rolling stands 51-53. If now the inlet mass flow increases continuously, in order to achieve the desired final thickness and final rolling temperature, first the fourth rolling stand 54, then in a further step, the fifth rolling stand 55 and possibly also the sixth rolling stand 56 closed, so active. Before connecting a further roll stand, the temperature in the furnace 7 and thus the inlet temperature T2 of the pre-strip 3 ^'would decrease with increasing inlet mass flow.

As soon as another scaffold is switched on or closed, the inlet temperature must be raised significantly,

typically between 35 and 55 K, for reasons of economy or product quality 1250 ° C, even better 1220 ° C surface temperature should not be exceeded.

Likewise, care should be taken that in the event of a sudden, unpredictable change in the inlet mass flow or inlet temperature (e.g., partial failure of the oven 7), one additional rolling stand 51-56 is opened or closed to achieve the desired final thickness and finish rolling temperature.

But it is according to the invention - both in continuous

Changes as well as sudden changes in the

Inlet sizes (temperature, mass flow) - to pay attention, always only the actually necessary number of rolling stands

51-56 to use. In particular, the pre-strip thickness is to be selected so high that at the lowest possible

Inlet temperature, e.g. 1090 ° C, the three, four or five currently still active rolling stands with maximum

Reduction levels, ie at the technical limits of

Rolling mills that just can produce the desired steel strip. The following is an example of a 1570 mm wide strip product with a finishing line inlet thickness of 15 mm and a broad specific inlet mass flow of 440 mm m / min specify. You can see the reduction of the

Total energy requirements, as well as the changes in rolling mill rolling mill capacities, the number of passes and the furnace energy required, if only four rolling stands are used instead of five:

Scaffolding 51-55 Scaffolding 51- active 54 active

Inlet temperature 1069 ° C 992 ° C

opening act

Infeed thickness preliminary strip 15 mm 15 mm

Inlet mass flow 440 mm m / min 440 mm m / min

opening act

Total energy requirement 125 102

(Oven +

Finish rolling mill)

[KWh / t]

Energy requirement oven 91.5 61.5

[KWh / t] Scaffolding 51-55 active scaffolding 51-54 active

StichWalzGesamt- StichWalzTotal- off ^¬ energy decrease due to energy consumption [MN] requires [%] [MN]

[%] [kWh / t] [kWh / t]

Roll stand 43 22.5 33.5 53 33 40.5 51

Roll stand 41 25 49 33

52

Rolling stand 36 22.5 37 23

53

Roll stand 30 21 20 14

54

Roll stand 20 14 0 0 0

55

LIST OF REFERENCE NUMBERS

1 steel band

2 casting plant

3 slab

3 'opening band

4 Vorwal zstrasse

5 finished rolling zstrasse

51 first rolling stand of the finishing train

52 second rolling stand of the finishing train

53 third rolling stand of the finishing train

54 fourth rolling stand of the finishing train

55 fifth rolling stand of the finishing train

56 sixth rolling stand of the finishing train

6 oven for slab

7 oven for support band

12 scissors

13 tinder scrubber

14 cooling section

15 reel

F conveying direction

Tl roughing temperature

T2 inlet temperature of the steel strip when entering the

Finishing mill

Claims

claims

1. A method for producing steel strips (1) by endless rolling or semi-endless rolling, wherein first in a casting plant (2) a slab (3) is poured, the slab (3) in a roughing train (4) to a pre-strip (3 ^' ) is rolled, the pre-strip (3 ^') in a furnace (7) is heated and the heated pre-strip ^(3') in a finishing rolling train (5) to a predetermined final thickness and a predetermined final rolling temperature is finish-rolled, characterized in that

- When changing the inlet temperature (T2) of the pre-strip (3 ^' ) when entering the finishing train (5) by more than 1 K / second, in particular by more than 5 K / second, and / or

- When changing the inlet mass flow of the pre-strip when entering the finishing train by more than 0.2% / second, in particular by more than 1.5% / second,

Finish rolling line (5) is brought out of the rolling engagement or a roll stand of the finishing train is brought into rolling engagement, which is the last engaged rolling stand downstream, under the constraint that a

Minimizing the energy to the furnace (7) and / or the

Finishing mill (5) is reached is achieved and that the inlet temperature (T2) of the pre-strip (3 ^' ) by adjusting the furnace (7) and the rolling stands (5) are set according to the new stitch plan.

2. The method according to claim 1, characterized in that the new stitch plan is determined during the ongoing rolling process.

3. The method according to claim 1 or 2, characterized

in that the new stitch plan is determined by means of a mathematical process model which determines the rolling process of at least all rolling mills (51-56) of the finishing train (5).

emulates, creates.

4. The method according to claim 3, characterized in that with the process model of the stitch plan at least the

Final rolling temperature of the steel strip, the final thickness of the

Steel band, as well as the common energy demand of

Finishing mill (5) and the furnace (7) is calculated, wherein the number of rolling stands (51-56) varies and the

associated energy is determined for the rolling mills and the furnace, and if a reduction of the common energy demand results, subject to predetermined limits for the settings of the rolling mills and the furnace, in a variation, this will be based on the new pass schedule.

5. The method according to claim 4, characterized in that with the process model of the stitch plan at least the

Final rolling temperature of the steel strip, the final thickness of the

Steel strip, as well as the energy demand of the furnace (7) is calculated, whereby the number of rolling stands (51-56) varies and the associated energy is determined for the furnace, and if, while maintaining predetermined limits for the

Settings of the rolling stands and the furnace at a

Variation results in a reduction of energy for the furnace, this is based on the new pass schedule.

6. The method according to any one of claims 1 to 5, characterized in that the thickness of the pre-strip (3 ^' ) for

Minimizing the required for the oven (7) energy is changed.

7. The method according to any one of claims 1 to 6, characterized in that it at startup and startup of a

Cast roll composite plant after a casting-rolling break for

Endless rolls or semi-endless rolls is used.

8. The method according to any one of claims 1 to 7, characterized in that the pre-strip to be rolled (3 ^' ) already in the semi-endless rolling in the finishing train (5) is when a rolling stand (51-56) is brought into rolling engagement or from the rolling engagement.

9. The method according to any one of claims 1 to 7, characterized in that the pre-strip to be rolled (3 ^' ) during semi- continuous rolling only then enters the finishing train (5), when a rolling stand (51-56) according to the new stitch plan to - or has been ascended.

10. computer program product, characterized in that it determines a stitch plan according to one of the preceding claims when loading and performing on a computer.