EP2346625B1 - Method for setting a run-off thickness for a milled item that passes through a multiple scaffold mill train, control and/or regulating device and mill train - Google Patents

Description

The invention relates to a method for adjusting a run-out thickness of a rolling stock passing through a multi-stand rolling train, in particular hot strip, wherein a first portion of the rolling stock is rolled to a first run-out thickness, wherein a second portion of the rolling stock is rolled to a second run-out thickness different from the first run-out thickness. Moreover, the invention relates to a control and / or regulating device for a rolling mill comprising a multi-stand rolling mill. Furthermore, the invention relates to a rolling mill with a multi-stand rolling line for rolling metallic rolling. A generic method is eg off JP-A 08300010 known.

The present invention is in the technical field of rolling mill technology. The rolling of metallic goods is usually used for the production of semi-finished products, which are subsequently used in the metalworking industry, for example in the automotive industry.

As a rule, a rolling mill must be able to produce a wide variety of metallic semi-finished products, which differ, for example, in the metal to be processed, in the structural properties of steel to be processed and in the spatial dimensions, in particular the thickness.

In this respect, it is necessary that an operation of a rolling mill can be changed so that, for example, bands of different properties can be produced as quickly as possible in succession, so that a high system throughput is achieved. This is necessary for both hot rolling and cold rolling.

Methods are known from the prior art, which allow such a conversion of the properties of produced strips by means of a rolling mill.

From the Japanese patent application JP 2001293510 A2 For example, a method of controlling a flying thickness change of a continuous hot strip mill is known. A method is disclosed with which the automatic change in thickness per rolling stand can be determined.

The Japanese patent application JP 59191509 A2 discloses a method of changing material dimensions during the passage of rolling stock in a continuous mill train. In this case, manipulated variables are calculated from an initial state and position tracking is performed for the section of the strip for which the thickness is to be changed. Accordingly, a roll gap and a rolling speed are set for the respective rolling stand. In particular, it is provided that no reduction in thickness occurs at the last roll stand.

Object of the present invention is to provide an improved method for performing a flying thickness change, and a corresponding control and / or regulating device and rolling mill for this purpose.

The procedural part of the object is achieved by a method of the aforementioned type, wherein a transfer takes place during the rolling from the first to the second outlet thickness at an entry speed of the rolling stock in the rolling train, which in dependence of a discharge speed of the rolling stock of the rolling train in the mass flow direction upstream aggregate is set.

Such a transfer of the rolling stock from the first to the second outlet thickness during the rolling of the rolling stock is also referred to below as a flying change or change of the outlet thickness.

The determined entry velocity serves as a fixed, not arbitrarily adaptable input variable for the rolling train, which is not changed in particular by downstream in the mass flow direction of the first rolling stand of the rolling mill processes. Rather, the entry speed of the rolling stock in the rolling train is dependent on a discharge speed of the rolling stock of one or more units, which are arranged upstream of the rolling mill in the mass flow direction.

The discharge speed is preferably an actual discharge speed of the rolling stock of an upstream unit in the mass flow direction of the rolling mill. Alternatively, a target discharge speed of the rolling stock of an upstream in mass flow direction of the rolling mill unit can be used. Preferably, the outlet speed of that aggregate of the rolling mill is used, which has the least time dynamics and therefore carrier reacts to changes in the process, as the other units. This aggregate represents the limitation in the flying change of the outlet thickness. Further limitation for the flying change of the outlet thickness can result from the required or possible adjustment paths on the rolling stands and the required or possible acceleration of the work rolls of the rolling stands in the rolling train.

The term "outlet thickness" is understood to mean the thickness of the rolling stock after the last roll stand of the rolling train; "inlet thickness" is understood to mean the thickness of the rolled stock before the first rolling stand of the rolling train. The method is both suitable to convert a thinner outlet thickness in a thicker outlet thickness and vice versa. In general, however, the change of the outlet thickness to a thinner outlet thickness is technically more demanding than the conversion of a thinner outlet thickness into a thicker outlet thickness.

An aggregate is a rolling process to be processed or generating device in a rolling mill, which with the Walzstraße in indirect or direct operative connection stands. Examples include reel, furnace, rolling stand, caster, scissors, descalers, cooling section, etc.

In previous methods for flying thickness change in a rolling train, the inlet velocity is usually a variable manipulated variable, which is reacted for example to mass flow fluctuations or Bandzugschwankungen in the rolling mill - caused by the change of the operation of the rolling mill - by changing just this manipulated variable. Thus, the deviations caused by the transfer in process variables, such as the mass flow, can be corrected.

However, the change in the inlet velocity, if appropriate, propagates to the mass flow direction upstream aggregates of the rolling train. Depending on the structure of the rolling mill, this can lead to significant problems in the process of running on the running in the mass flow direction of the rolling mill units running processes.

However, this can be avoided by the present invention by the infeed speed of the rolling stock in the rolling train is determined, adjusted and maintained, that an adaptation of a Walzgut-discharge speed of a mass flow direction upstream aggregate on the inlet speed of the rolling train is not required or to a lesser extent is. In particular, the units arranged upstream of the rolling train in the mass flow direction can be operated according to their desired values, without a correction of the desired values due to downstream processes in the mass flow direction, in particular due to a transfer of a rolling stock from a first outlet thickness to a second outlet thickness ,

In other words, by the invention, the mass flow turbulences in the rolling train caused by the transfer can be completely cascaded out in the mass flow direction. This means that it is not absolutely necessary to cascade out against the mass flow direction, as is usual today, by either increasing the inlet speed - for example, when transferring a first outlet thickness into a larger second outlet thickness - or lowering it - for example, when transferring the first outlet thickness into a smaller second outlet thickness - becomes. The infeed speed, which is set as a function of an outfeed speed of the rolling stock of an upstream unit in the mass flow direction of the rolling train, can be handled according to the invention as a hard, to be observed boundary condition of the rolling process.

However, it is also possible to use a mixed cascading of mass flow fluctuations in the mill train during the mass flow direction and mass flow direction transfer. For example. If the entry speed of the rolling stock in the rolling train during the transfer only so retroactively changed upstream in the mass flow direction processes that they can follow the change in the feed rate in the rolling line control technology still sufficiently fast, i. no process disturbance occurs in the upstream of the rolling mill in mass flow direction aggregates. For this purpose, in addition to the discharge speed, the time dynamics of the aggregate is taken into account, i. how fast and to what extent this unit can react to changes in the process without process interruptions.

Further required corrections of the mass flow are then cascaded out in the mass flow direction. This has the advantage that - especially when reducing the outlet thickness - the actuators are less stressed in the rear stands in a mixed forward and backward Auskascadierung, because by the reduced inlet speed of the rolling stock in the rolling mill and the rolling speed of the rolling stock at the rear rolling stands the rolling mill is sinking.

The present invention is applicable to both hot rolling and cold rolling of metal strips.

In particular, it is advantageous in the case of the flying change of the outlet thickness according to the method according to the invention to temporarily turn off the automatic gauge control (AGC) for a respective roll stand of the rolling train, in order to avoid faulty control interventions during the transfer of the rolling stock.

It is likewise advantageous that the inlet speed is set substantially constant as a function of an outlet speed of the rolling stock of an upstream unit in the mass flow direction of the rolling train. In particular, advantages according to the invention can also be achieved hereby for slowly changing processes preceded by the rolling train. This is particularly advantageous in cast roll composite systems, since the casting speed is usually constant and the casting unit is usually the aggregate with the least dynamic in time.

In particular, the invention makes it possible to ensure a constant mass flow on the input side into the rolling mill. This leads to the corresponding planning reliability and a smoother process of the processes, which are upstream of the rolling mill in the mass flow direction.

In an advantageous embodiment of the invention, the entry speed is set substantially to the exit speed of a next, upstream of the rolling mill unit. This is particularly useful if, for example, in "batch rolling" the distance of the rolled or to be rolled slabs is very low. This is advantageous for example in continuous operation, the "conti" - operation or in the "semi-endless" operation of a rolling mill. As a result, an undisturbed process of the entry speed of the rolling mill in the rolling mill in the mass flow direction upstream units possible, in particular, there are no deviations from the desired belt tension or the desired mass flow.

In a further advantageous embodiment of the invention, the rolling train and at least one upstream in the mass flow direction of the rolling mill unit, preferably a casting unit, coupled by the production of the first and the second rolling stock having rolling. That is, a change of the entry speed, which is not caused by the upstream aggregate, into the rolling train propagates via the rolling stock into the aggregates upstream of the mass flow direction of the rolling mill and thus adversely affects the processes taking place in these aggregates. In particular, it is possible that in the mass flow direction of the mill train upstream units are not able to respond to the relatively rapid changes in the inlet velocity, as are common in the art and also required to compensate for mass flow fluctuations during the transfer. As a result, it can lead to a mal-processing of rolling in at least one of the rolling mill in the mass flow direction upstream units, provided that they can not follow the changes in the inlet velocity sufficiently quickly. This is of particular importance for cast roll composite systems in which, for example, as in the case of the Endless Strip Production plant of Arvedi, the rolling stock extends from a casting machine through the entire rolling mill, in particular through the rolling mill, to a reel. There the finished rolled metal strip is wound up. In terms of control engineering, the casting plant is the "weakest" link in the chain with regard to the dynamics of the aggregate over time. The manipulated variables which can be set during casting can generally not influence the casting process as quickly as changes in the inlet speed of the rolling train take place. This means that unwanted casting defects occur. Analogously, this also applies to other units of the mill train in mass flow direction. All this can be avoided by this advantageous embodiment of the invention.

In a further advantageous embodiment of the invention, a first pass plan and a second pass schedule is given, wherein the execution of the first pass plan, the first outlet thickness and the execution of the second pass plan, the second outlet thickness is rolled, wherein an operation of the rolling mill according to the first pass schedule during rolling of a Walzguts is transferred in an operation of the rolling mill according to the second pass schedule, wherein the transfer takes place for each stand of the rolling mill substantially during the rolling of a predetermined transfer section of the rolling stock through the respective rolling stand. This makes it possible to minimize the consumption of rolling stock for flying change of the outlet thickness, since only the transfer section is obtained as a committee and not the entire length of the rolling mill, such as simultaneous transfer of the rolling stands from operation according to the first pass schedule in the operation according to the second pass schedule , Accordingly, the scrap of rolling stock is reduced. In particular, this method is advantageously used in a "conti" operation of a rolling mill. Because there is only a single transfer section, which can be assigned to a flying change in the outlet thickness of the rolling train, whereas in "batch" operation additional strike losses of rolling stock always occur.

In a particularly advantageous embodiment of the invention, the transfer section is determined such that this at any time during its passage through the rolling train has a length which is at most equal to a distance between two adjacent rolling stands. This ensures that the flying change of the outlet thickness of the rolling train is technically particularly easy and fast. Namely, if the thickness wedge at the same time in two rolling stands, this means a considerable overhead for the control of the flying change of the outlet thickness. Therefore, it is advantageous to determine the length of a transfer section in such a way that at a certain time during the transfer of the thickness wedge always only in a rolling mill of the Rolling mill is being processed. In general, this condition is met when the length of the transfer section between the last in the mass flow direction and penultimate a change in thickness of the rolling stock causing roll stand of the rolling line is not greater than a distance of these two stands from each other. The length of the transfer section to be determined depends on the number of rolling stands in the rolling train, as well as the inlet thickness of the rolling stock in the rolling train and the desired outlet thickness of the rolling stock from the rolling train.

In a further advantageous embodiment of the invention, the transfer section is rolled by means of a plurality of roll stands comprised of the rolling train, wherein at least one rolling stand is operated during the rolling of the transfer section as a rolling force-controlled rolling stand. This is particularly advantageous in that, for rolling stands arranged increasingly closer to the end of the rolling train, the tracking of the tape may lead to inaccurate values with regard to the position of the thickness wedge or the transfer section in the rolling train since the rolling stock speed is already comparatively high in this area of the rolling train is. Accordingly, a position-controlled roll gap adjustment for processing the transfer section in a desired manner, in particular by the last rolling stands of the rolling train, is technically difficult. On the other hand, if a rolling-force-controlled rolling stand is used to roll the transfer section according to the specifications, the thickness wedge is automatically detected, since the rolling stand changes to a rolling force change due to the changed thickness of the thickness wedge when the transfer section enters the rolling gap. The change in rolling force on the respective rolling stand is dependent on whether the running-in thickness into the respective roll stand becomes lower or higher as a result of the transfer. Before and after the rolling of the transfer section by the respective rolling stands, these are preferably operated position-regulated.

With a reduced infeed thickness of the transfer section compared to the preceding rolled section processed by this mill stand, when the transfer section enters the nip of this mill stand, the rolling force on this mill stand falls. The rolling force controller is now trying to set the desired nominal rolling force again according to the first pass schedule for this mill. Preferably, however, at the same time the set rolling force to be set is continuously changed in the direction of the rolling force target value according to the second pass schedule. There is a so-called "ramp in" of the target rolling force of the second stitch plan in the target rolling force of the first stitch plan instead. This "ramp in" means that when the transfer section from the respective rolling mill standstill, the corresponding manipulated variables are then set according to the second pass schedule and the outlet thickness desired according to the second pass schedule is reached from the respective rolling stand. This happens for each mill stand of the rolling mill.

Analogously, a transfer of the operation of the rolling stand according to the first is handled in a second pass schedule, in which the first outlet thickness of the rolling line is less than the second outlet thickness. In this case, for example, in the first rolling stand of the rolling train does not result in an increased reduction in thickness, but in comparison to rolling according to the first stitch plan to a reduced thickness reduction. As a result, it comes when entering the processed through the first rolling stand transfer section in the second and possibly the subsequent rolling stands to a rolling force increase. This rolling force increase can be used to detect the entry of the transfer section into the respective rolling stand. Analogous to the above explanations, a so-called "ramp in" of the rolling force setpoint according to the second pass schedule then takes place in the rolling force setpoint according to the first pass schedule during the rolling of the transfer section by the respective rolling stand. The use of at least one rolling-force-controlled rolling stand provides a simple possibility of a flying change of the outlet thickness without much effort, in particular with regard to a position tracking of the transfer section and a position-controlled roll gap.

In a further advantageous embodiment of the invention, during rolling of the transfer section, an actual process variable set on the basis of the first pass-through plan is continuously transferred to a target process variable determined on the basis of the second pass-through plan. This avoids a sudden change in process variables when rolling the transfer section. Examples of process variables which experience a continuous change during the rolling of the transition section are, for example: setting position, setting force, peripheral speed of the work rolls, acceleration rate, etc. This is particularly advantageous for the above-mentioned change in rolling force during rolling of the transfer section. A continuous transfer, i. non-impact or bumpless change of the process variables, simplifies the handling of the rolling stock for the rolling mill in the mass flow direction downstream units and reduces the load on the system. This can be achieved, for example, with the above-described "ramp in" of a second setpoint value, a first setpoint size. A superimposition of the setpoint variables is carried out in such a way that a continuous change takes place from the actual process variable in the direction of the new setpoint process variable.

In a further advantageous embodiment of the invention, compliance with plant-technical restrictions is checked during rolling or expected violation of the restrictions the transfer of the operation of the rolling mill according to the first pass schedule in the operation of the rolling mill according to the second pass schedule. Under plant-technical restrictions are given by the plant given limiting boundary conditions, in particular technical nature, which must be complied with, so that a plant over a long time is scheduled to operate and a desired product to be manufactured can. Examples of plant-specific restriction are, for example, maximum Anstellgeschwindigkeiten the rolling stands, maximum permissible drive loads, etc .. By preferably continuously performed during operation of the system review of plant restrictions, it is ensured that any overloads occurring by rolling the transfer section does not lead to a plant defect and thus plant downtimes.

By interrupting the transfer is accepted in favor of the plant safety that more Walzgutausschuss is rolled than intended to avoid damage to the plant or individual plant components. Specifically, for example, in the case of a flying change of the outlet thickness from a first higher outlet thickness to a second smaller outlet thickness, an overload of the drives on the rolling stands can occur. If the overload during rolling of the transfer section becomes too large, damage or failure of one or more drives can occur. Since this would lead to a longer standstill of the rolling train and thus the rolling mill, this should be avoided if possible.

By interrupting the transfer, any directed deviation from the planned execution, advantageously this is usually understood to be the fastest possible execution of the transfer. In particular, a slower execution of the transfer can also be considered as an interruption of the scheduled transfer. As a result, gradients can be reduced during the setting of manipulated variables and process variables, as a result of which system restrictions can be maintained, if necessary.

In a further advantageous embodiment of the invention, the rolling force and / or the nip of a roll stand to be passed next by the transfer section in addition to the first and second pass schedule depending on the strip tension between this stand and the in Mass flow direction of this rolling mill upstream rolling mill set. Due to the flying change of the outlet thickness in the rolling train, it may be between the rolling stands depending on the type of transfer, ie from a smaller outlet thickness to a higher outlet thickness or from a higher outlet thickness to a lower outlet thickness to overvoltages in the band or to the loss of belt tension come. These can be caused by mass flow turbulences between the rolling mills of the rolling train. A belt tension can be detected, for example, by means of a loop lifter between the individual rolling stands of the rolling train. On the basis of the detected belt tension or the deflection of the loop lifter, the employment of the rolling stand to be passed through by the transfer section is now changed. The change of employment may have an adjustment of the roll gap to the goal or a setting of a desired rolling force for the rolling stock. If, for example, a voltage drop is detected, an opening of the roll gap of the rolling stand to be passed next from the transfer section to the strip tension is restored, since more material can thereby be transported through the next rolling stand. Analogously, when the belt tension is excessive, the adjustment is closed in order to lower the belt tension between the rolling mill to be passed next from the transfer section and the rolling mill upstream of this rolling mill in the direction of mass flow. This ensures that a desired belt tension between the individual rolling stands of the rolling train is maintained even during the flying change of the outlet thickness. However, with the appropriate nip changes it must be ensured that the thickness tolerances of the product to be produced are complied with.

In a further advantageous embodiment of the invention, during the transfer of the operation of the rolling mill according to the first pass schedule in the operation of the rolling mill according to the second pass schedule, each rolling stand of the rolling train is operated such that each rolling stand has an identical relative change the rolling stock thickness achieved. By changing the relative change in the rolling stock thickness, a measure of the ratio of the outlet thickness of the respective rolling mill according to the first and second pass plans is understood. This allows the respective drives of the rolling stands during the transfer of the operation of the rolling mill according to the first pass schedule in the operation of the rolling mill according to the second pass schedule are uniformly accelerated. If the change in thickness is initiated by the setting of a first roll stand with simultaneous acceleration or deceleration of the following forming steps with the corresponding increase of the discharge speed from the first staffed mill stand of the rolling mill and further traced the relative Auslaufdickenänderung for the respective rolling stand in the following rolling stands of the rolling mill, so the entire rolling train can be converted with little effort to the second outlet thickness of the rolling train. By virtue of the fact that each rolling stand achieves the same relative change in the rolling stock thickness during the rolling of the transfer section, an acceleration or deceleration of the drives of the entire rolling mill need only be carried out at the respectively first change in the position of the respective rolling stands.

In particular, it is advantageous, after the transfer of the operation of the rolling train according to the first pass schedule, to redistribute drive loads of rolling mill drives assigned to the rolling train during rolling of the second run-out thickness into an operation of the rolling train according to the second pass schedule. The second stitch plan may not be optimized for stationary operation of the rolling train to produce the second outlet thickness, but is optimized for the smoothest possible implementation of the transfer of the first outlet thickness in the second outlet thickness. Therefore, a redistribution of the drive loads after the transfer can lead to a permanent reduction of the drive loads, which increases the reliability. As rolling mill drives those drives are called, which drive the work rolls of the respective rolling mills of the rolling mill.

In a further advantageous embodiment of the invention, a change of manipulated variables required for at least one of the rolling train downstream in the mass flow direction due to the changed outlet thickness of the rolling train during the influence of the transfer section by this at least one unit. It is thus achieved that the downstream of the rolling mill in the mass flow direction aggregates also use the transfer section, in which the first outlet thickness merges into the second outlet thickness to make the change in their control variables. For example, the coolant flow in the cooling section can be adapted accordingly to the new outlet thickness from the rolling train. Likewise, for example, the torque and / or the rotational speed of the reel can be adapted to the new outlet thickness from the rolling train. This adaptation of the respective manipulated variables preferably takes place precisely when the transfer section of the rolling stock is influenced by changing this manipulated variable.

The part of the object to be assigned to the control and / or regulating device is achieved by a control and / or regulating device for a rolling mill comprising a multi-stand rolling mill, with a machine-readable program code which has control commands which, when executed, include the control and / or regulating device for causing a method according to any one of claims 1 to 12 cause.

The object is further achieved by a rolling mill with a multi-stand rolling mill for rolling metallic rolling, with a control and / or regulating device according to claim 13, with a device for supplying the discharge speed of the rolling stock of a rolling mill in the mass flow direction upstream aggregate to the control and / or regulating device according to claim 13, wherein the rolling stands of the rolling train with the control and / or regulating device operatively connected are. As a result, a rolling plant is provided, by means of which a flying change in the outlet thickness of a rolling train can be carried out easily. In this context, rolling plant is understood to mean any plant which comprises a rolling train, preferably for processing metallic rolling stock, in particular cast roll composite systems.

In a further advantageous embodiment of the rolling mill, the rolling train is a high-reduction mill downstream of a casting unit in the mass flow direction and / or a finishing train. A high-reduction mill is a rolling mill consisting of several stands in the present case, which rolls the rolling stock with a large decrease in thickness while it is still very hot. It can be differentiated between Liquid Core Reduction and Soft Core Reduction. As a rule, liquid core reduction in a high-reduction-mill is not used, but the soft core reduction of the rolled stock is certainly applicable. Soft core reduction means that the core of the rolling stock is already solid, but still very soft due to the high temperature of, for example, 1200 ° C to 1300 ° C. If the rolling stock in the High Reduction Mill still had a liquid core, the high forces in the High Reduction Mill would lead to considerable process disruptions. Thanks to the High Reduction Mill, the Soft Core Reduction can achieve large reductions in the rolling stock with comparatively low rolling forces. For such a multi-stand high-reduction mill, the method according to the invention can be used advantageously. In addition, the rolling train can alternatively or additionally be formed as a multi-stand finishing train, which rolls rolling to desired final dimensions.

FIG 1

schematisch dargestellte Anlage zur Durchführung einer Ausführungsform des erfindungsgemäßen Verfahrens, wobei ein Metall vergießendes Aggregat als Kokille ausgebildet ist,

FIG 2

schematisch dargestellte Anlage zur Durchführung einer Ausführungsform des erfindungsgemäßen Verfahrens, wobei ein Metall vergießendes Aggregat als Zweirollengießmaschine ausgebildet ist.

Further advantages of the invention will become apparent from an embodiment which is explained in more detail with reference to the schematic drawing. Show it:

FIG. 1

schematically illustrated system for carrying out an embodiment of the method according to the invention, wherein a metal-casting aggregate is formed as a mold,

FIG. 2

schematically illustrated system for carrying out an embodiment of the method according to the invention, wherein a metal casting unit is designed as Zweirollengießmaschine.

The FIG. 1 a schematically illustrated system for carrying out an embodiment of the method according to the invention. Furthermore, it shows thickness profiles of a rolling mill rolled from the rolling mill during the transfer of the rolling mill operation according to a first pass schedule in a rolling mill operation according to the second pass schedule for different advanced transfer states of the rolling stock. In addition, shows FIG. 1 Rolling force and peripheral speed curves as a function of time for the individual rolling mills of the rolling train.

FIG. 1 shows a section of a rolling mill 1, which comprises a three-stand mill train 2. The rolling train 2 can be designed, for example, as a high-reduction mill for a system for endless strip production. The rolling train 2 may alternatively or additionally be designed as a multi-stand, for example five-stand finishing train of a rolling mill 1. In the present case, the rolling train 2 comprises a first rolling stand 3, a second rolling stand 4, and a third rolling stand 5.

FIG. 1 shows the rolling mill 1 in a state in which rolling stock G, the rolling mill 1, in particular the rolling mill 2, passes through. In the exemplary embodiment, the entire rolling mill is coupled through the rolling mill passing through the rolling mill G, since from the beginning to the end of the rolling mill 1 is integrally formed and different sections of the rolling stock G are each in other units of the rolling mill 1 for their processing. Basically, for this mode, ie for the "endless process", the invention can be used particularly advantageous. However, this invention is not limited to this mode.

According to a first pass schedule, the rolling train 2 rolls a first section G-1 of the rolling stock to a first outlet thickness H3 of the rolling train 2.

If a change in the outlet thickness is now to take place without, for example, providing a cast-iron discontinuation, this can be done with the present method during the rolling of the rolling stock G which couples the system.

In the exemplary embodiment, the outlet thickness from the rolling train 2 is to be converted from a first outlet thickness H3 for a first section G-1 of the rolling stock G into a second, thinner outlet thickness H3 'for a second section G-2 of the rolled stock G.

In the rolling train 2 of the rolling mill 1, in particular between the rolling stand 3 and the rolling stand 4 and between the rolling stand 4 and the roll stand 5, each loop lifter 7, in particular for a rolling mill 2 formed as a finishing line, are arranged. These are used to check the strip tension of the rolling mill 2 continuous rolling G.

FIG. 1 further shows an upstream of the rolling mill 2 in the mass flow direction unit 6, which is designed as a casting unit for casting steel.

Further shows FIG. 1 Also, one of the rolling mill in the mass flow direction subordinate unit 8, which is designed for example as a cooling section. The cast of the casting unit 6 rolling G coupled in stationary operation all the band influencing units of the rolling mill 1 shown with each other.

A control and / or regulating device 9 controls the operation of the units 6, 2 and 8, in particular the operation of the rolling train 2, and is ertüchtigt by a machine-readable program code for carrying out the flying change of the outlet thickness. The machine-readable program code includes control commands which, when executed, cause the control and / or regulating device 9 to carry out the method.

Before an embodiment of the method according to the invention is used, the rolling train 2 rolls a first outlet thickness H3 according to a first stitch plan. The rolling stock G-1 runs in this case with a thickness h0 in the rolling train 2 and in the first rolling stand 3 of the rolling train 2 a. The first rolling stand 3 rolls the rolling stock G-1 to a thickness H1.

Subsequently, the rolling stock of the thickness h1 enters the second rolling stand 4 of the rolling train 2 and is rolled by this to its thickness H2. Subsequently, the rolling stock G-1 enters the third rolling stand 5 with the thickness H2 and is rolled by this to an outlet thickness H3. A reduction in thickness of the first section G-1 of the rolling stock G according to the first pass plan is shown directly below the rolling mill 1 shown schematically.

Starting from this thickness distribution for producing a first outlet thickness H3, a rolling operation of the rolling train 2 is carried out from a rolling operation according to the first pass schedule into a rolling operation of the rolling train 2 according to the second pass schedule during the rolling of rolling stock due to a changed product request.

The usual calculation methods can be used to calculate pass-through plans. Such a calculation method can, for example, the DE 37 21 744 A1 be removed.

In order to carry out a transfer of the outlet thickness H3 into an outlet thickness H3 'from the rolling train 2, a transfer section X0 is first determined in front of the first rolling stand. The transfer section is a section of the rolling stock between the first and second sections G-1 and G-2 of the rolling stock G, which usually serves exclusively to transfer the rolling operation of the rolling train 2 according to a first pass schedule into an operation of the rolling mill 2 according to the second pass schedule , In this respect, the beginning of a transfer section is usually processed according to a first pass schedule, the end of the transfer section according to a second pass schedule.

Specifically, the transfer section X0 is determined to have a length no greater than the distance between two stands from each other during the transfer of the rolling operation according to the first pass schedule to the second pass plan rolling operation at any time during the transfer. This ensures that the transfer control technology is comparatively easy to handle, because the transfer section is at any time of the transfer in two rolling stands simultaneously.

Alternatively, however, it may be provided, for example, due to plant-specific restrictions, that during the transfer of the thickness wedge is rolled simultaneously in two or more adjacent rolling stands. This makes it possible to reduce the demands on the rolling train, for example, with regard to setting paths and acceleration for the respective rolling stands of the rolling train, and thus a transfer of the rolling train at

In such a determination of the length of the transfer section X0 in front of the first rolling stand 3 of the rolling train 2, in particular the number of rolling stands of the rolling train 2 or the desired outlet thickness H3 'from the rolling mill 2 according to the second pass schedule must be taken into account.

If the second runout thickness H3 'rolled according to the second pass schedule is smaller than the first run-out thickness H3 rolled according to the first pass schedule, then it is necessary to select the transfer section X0 correspondingly short. Since this is significantly extended by the mass flow caused in the rolling stands in the transport direction of the rolling stock G, it can be ensured that the transfer section X2 to be processed by the last rolling stand 5 of the rolling train 2 has already run out of the rolling stand 4 upstream of this rolling stand 5 in the mass flow direction.

For a five-stand finishing line, the length of the transfer section X0 in front of the first stand of the finishing train for usual outlet thicknesses at the end of the rolling mill is about 1 m. It can thus be ensured that the length of the transfer section between the fourth and fifth stands is no longer than the distance between these stands, which is for example approximately 4.70 m.

If there is a change in the outlet thickness towards larger outlet thicknesses, i. thicker bands, the transfer section X0 can also be chosen correspondingly larger, since the mass flow is correspondingly lower in the transport direction of the tape.

An extension of the transfer section X0 has the advantage that there is more time for the transfer, whereby the changes for the actuators to adjust the process variables correspondingly lower and thus reduces the probability of violation of given by the rolling mill 1 boundary conditions.

In the transfer step S1, the transfer of the operation of the first rolling stand 3 of the rolling train 2 according to the first pass schedule is shown in a rolling operation according to the second pass schedule. For this purpose, the temporal rolling force curve and the time course of the peripheral speed of the work rolls, in particular during the transfer from the rolling operation of Roll stand 3 according to the first stitch plan in the rolling operation according to the second stitch plan, shown. For smaller times in the representation of the rolling force or the peripheral speed of the work rolls, the first rolling stand 3 is operated according to the first pass schedule, ie with the rolling force F1 and the work roll circumferential speed V1. For larger times, the first rolling stand 3 is operated according to the second pass schedule, ie with the rolling force F1 'and the work roll circumferential speed V1'.

In between, a change in the rolling force during the rolling of the transfer section by the first stand 3 from the rolling force F1 and the work roll peripheral speed V1 according to the first pass schedule to the corresponding rolling force F1 'and work roll peripheral speed V1' according to the second pass schedule. The change is continuous and jump-free or bum-free.

During the transfer, the automatic gauge control, abbreviated AGC, is preferably switched off. This has the advantage that the risk is avoided that the AGC tries to regulate the roll gap on the first roll stand 3 on the first pass schedule and thus counteracts the transfer of the operation of the roll stand 3 from the operation according to the first in the second pass schedule.

The work roll circumferential speed V1 'at the first stand 3 after the transfer is generally dependent on the thickness change made on the first stand 3. In the embodiment according to the embodiment, the thickness reduction of H1 according to the first pass schedule on H1' according to the second pass schedule, the peripheral speed of the work rolls of the rolling mill 3 is increased to keep the mass flow through the rolling train 2 constant.

The difference ΔV1 between the peripheral speed V1 according to the first pass schedule and the peripheral speed V1 'according to FIG second stitch plan is passed to the first roll stand 3 downstream rolling stands 4 and 5 or the work roll peripheral speeds of the first roll stand 3 downstream rolling stands 4 and 5, the circulation speed change tracked on the first roll stand 3.

The work rolls of the second stand 4, while the transfer section X1 is between the first stand 3 and the second stand 4, thus have a work roll peripheral speed of V2 + ΔV1. Also, the third rolling stand 5 has a work roll peripheral speed of V3 + ΔV1 during the above-mentioned period of time. However, the rolling forces F2 and F3 for the rolling stand 4 and 5 are kept substantially constant.

By changing the rolling operation of the first rolling stand 3 during rolling of the transfer section X0, a transfer section X1 having a thickness course, also called a thickness wedge, is formed. This is shown, for example, in the transfer step S2, which shows the thickness profile of the rolling stock G after the first rolling stand has been transferred from the rolling operation according to the first pass schedule to the rolling operation according to the second pass schedule.

Between the first rolling stand 3 and the second rolling stand 4 there is now a thickness progression from a "new", thinner outlet thickness H1 'to an "old", thicker outlet thickness H1. This thickness wedge is to be processed by the second or third rolling stand 4 or 5 arranged downstream of the first rolling stand 3 in the direction of mass flow.

Since no thickness wedge caused by the transfer of the rolling operation according to the first pass schedule according to the second pass schedule is present for the first roll stand 3, the first rolling stand 3 can be operated only position-controlled SC or only rolling force-controlled FC. A position-controlled operation of a rolling mill is in FIG. 1 marked SC, a rolling force controlled Operation of a roll stand with FC. This position-controlled or rolling-force-controlled operation is in FIG. 1 in relation to the time axis of the rolling force course and the peripheral speed course of the work rolls.

According to transfer step S1, shortly before entry of the transfer section X0, the operation of the first stand 3 is changed from a position-controlled SC operation to a rolling-force controlled FC operation. The change of rolling force controlled operation in position controlled operation and vice versa is made by means of the tape tracking by means of which the transfer section is tracked. When the transfer section X0 has passed the first rolling stand 3, the operation of the rolling stand 3 is changed from a rolling force controlled operation to a position-controlled SC operation again. Analogously, the aforementioned changes for the subsequent rolling stands 4 and 5, if the transfer section X1 or X2 is processed by this.

In particular, when transferring the runout thickness of the mill train to smaller thicknesses, tape tracking for mill stands of the mill train with increasing proximity to the exit of the mill train is too inaccurate to ensure position controlled SC operation of a millstand with adequate accuracy. For this reason, it is necessary for these rolling mills to perform a rolling force controlled FC operation, as this - either by rolling force increase or decrease - automatic detection of the incoming thickness wedge or the transfer section is possible in the respective rolling mill.

According to S2, now after the transfer of the operation of the first rolling stand 3 from the operation according to the first pass schedule to the operation according to the second pass schedule, rolling on the rolling stand 3 with the illustrated thickness distribution. In the rolling stand 3, a reduction in thickness of the rolling stock H0 to now a new Walzgutauslaufdicke H1 'from the first rolling mill. 3 takes place.

In the transfer step S2, the transfer of the operation of the second roll stand 4 of the rolling train 2 according to the first pass schedule is shown in a rolling operation according to the second pass schedule, wherein the first rolling stand is already operated stationary according to the second pass schedule.

After rolling the transfer section X0 by means of the first roll stand 3, this now lies in the form of the transfer section X1 after the first roll stand 3. During the passage of the transfer section X1 through the second stand 4, it is continuously transferred from the operation according to the first pass schedule to the operation according to the second pass schedule.

Up to the shrinkage of the thickness wedge or the transfer section X1 in the second rolling stand 4, the rolling stand 4 must feed the Walzgutdicke H1 on the inlet side and roll to a Auslaufdicke H2 on the second stand 4, but the work rolls of the second stand 4, a peripheral speed of V2 + .DELTA.V1 have due to the changed operation of the first rolling mill 3.

This can lead to an overload of the drive and / or to a reduction of the entry speed of the rolling stock G in the second rolling stand 4. If there is a reduction in the lead-in speed, this has an effect on the tension of the rolling stock, since inlet speed at the second stand and Outfeed speed on the first stand are no longer equal.

If unwanted belt tension deviation occur, they are detected by the loop lifter 7 and an intervention in the operation of the second rolling stand 4 takes place on this basis, for example by the rolling nip of the rolling stand 4 being changed in such a way that the disturbance of the desired belt tension or the Overload of a drive is compensated. Such interference in the nip of the roll stand. 4 can optionally be compensated by the following roll stand 5 again. The intervention always takes place in such a way that it does not react on the entry speed of the rolling stock of the rolling train 2.

The required loads or overloads of the drives are preferably taken into account in the calculation of the new pass-through plan, so that they do not occur as planned in the transfer of the operation of the rolling train from the operation according to the first pass schedule to the operation according to the second pass-up plan.

However, in particular during the transfer constantly checking whether plant-technical restrictions are violated in the transfer of the operation of the rolling train 2 or whether predetermined thresholds to ensure the operation of the system are violated.

During the transfer of the second rolling stand 4 from the first pass schedule to the second pass schedule, the rolling force F2 is changed to a rolling force F2 'during the rolling of the transfer section. Associated with this is usually also a change in the peripheral speed of the work rolls in the second rolling stand 4 of the roller peripheral speed V2 + .DELTA.V1 in a roller peripheral speed V2 'according to the second pass schedule, which essentially consists of the sums of V2, .DELTA.V1 and .DELTA.V2, wherein .DELTA.V2 that one Part of the roller circumferential speed V2 ', which goes back to the changed outlet thickness H2' at the rolling stand 4. The rolling of the transfer section X1 in the second stand 4 is carried out as described above, rolling force-controlled FC. In stationary operation of the roll stand 4 according to the respective stitch plan, a position-controlled SC operation of the roll stand 4 preferably takes place.

After passing through the second stand 4, the transfer section X1 is transferred to the transfer section X2. Due to the change made in the roller peripheral speed in the second rolling stand 4, the roller peripheral speed is the work rolls in the third rolling mill 5 according to the discharge speed of the second portion G-2 of the rolling stock G to adapt, which is now processed according to the second pass schedule.

In the transfer step S4, the thickness profile of the rolling stock G is shown after the transfer section X2 has emerged from the second rolling stand 4. There is now a thickness wedge between the second rolling stand 4 and the third rolling stand 5, wherein the thickness wedge a thickness curve of a "new" outlet thickness H2 ', rolled after the second stitch plan, to an "old" outlet thickness H2, rolled according to the first stitch plan , having.

The peripheral speed V3 of the work rolls of the third stand 5 is adapted to the exit speed of the work G from the second stand 4.

S5 shows the temporal rolling force curve and the course of the work roll circumferential speed for the respective rolling stands, while the transfer section passes through the third rolling stand 5. Meanwhile, the first and second rolling stands are already operated in a stationary operation according to the second pass schedule.

The transfer section X2 or the thickness wedge, before the last rolling stand 5 of the rolling train 2, has a length which is less than the distance between the last rolling stand and the second to last rolling stand of the rolling train, in the present exemplary embodiment thus the second rolling stand 4 and the third rolling stand 5.

The transfer of the operation of the third rolling stand 5 from the operation according to the first pass schedule in the operation according to the second pass schedule, ie the rolling of the transfer section X2, takes place - in particular due to the increased rolling speeds on the third rolling stand 5 - with rolling force-controlled FC operation of the third rolling stand 5. In stationary operation of the rolling mill 5 according to the first or second pass schedule, this position-controlled SC is operated.

If the transfer section X2 has completed the third rolling stand, then all the stands of the rolling mill are operated according to the second pass schedule. There is then a stationary operation of the rolling mill 2 according to the second pass schedule.

According to the transfer step S6, after passing through the transfer section X2 of the third rolling stand 5, the thickness distribution shown is present. From the roll stand 5 now runs out of the "new" outlet thickness H3 ', rolled according to the second stitch plan. Furthermore, in the thickness distribution according to S6, the thickness wedge is still visible, which has a thickness profile from the thickness H3 'to the thickness H3.

The transfer from the operation of the rolling mill according to the first pass schedule to the operation of the rolling mill according to the second pass schedule during the rolling of a rolling stock is completed.

In the transfer step S7, the time profiles of the rolling force and the roller circumferential speed for the respective rolling stands 3 to 5 are shown. The rolling stands 3 to 5 are now operated stationary, position-controlled according to the second pass schedule. The rolling forces on the respective rolling stands and the peripheral speeds of the work rolls of the rolling stands are - in the context of the then again switched AGC - substantially constant.

The invention is not limited to the application on three-stand rolling mills 2, but is particularly advantageous in four-, five-, six- and seven-stand rolling mills 2 can be used. Likewise, the method can be used in batch mode, in semi-continuous operation or in the endless operation of a rolling mill or a Gießwalzverbundanlage.

The conversion from a thicker outlet thickness to a thinner outlet thickness of the rolling train is technically more demanding, since the speeds towards the end of the rolling mill become comparatively high, since the entry speed of the rolling mill is not available as a compensation variable for the high rolling speeds at the end of the rolling mill.

In particular, even with such transfers towards thinner outlet thicknesses from the rolling train, an overload of individual drives on the respective rolling stands may be possible and thus possibly completely collapse the belt tension. This can lead to plant shutdowns or damage, which should be avoided if possible.

During the entire transfer of the operation of the rolling mill according to the first pass schedule in the operation of the rolling mill according to the second pass schedule is continuously checked whether the planned transfer of rolling mill plant restrictions are violated in order to avoid damage to the rolling mill or components of the rolling mill ,

If the control and / or regulating device 9 determines such a violation or if the control and / or regulating device determines a high probability of a shortly occurring violation of system restrictions, then the operation of the rolling train according to the first pass schedule becomes operative according to the second Stitch plan interrupted, ie it is deviated from the planned transfer in such a way that the corresponding plant-technical restrictions are not violated.

This ensures that the rolling mill 1 is not damaged during the transfer of the operation of the rolling mill 2 according to the first pass schedule in the operation according to the second pass schedule.

In FIG. 1 is the rolling mill 2 in the mass flow direction upstream aggregate a casting unit 6. This pours with a casting speed V0, which is used as an entry velocity into the rolling train 2. The inlet speed is therefore adapted to the casting speed V0 of the casting unit. In FIG. 1 the casting unit is designed as a mold.

In a multi-stand finishing train, a casting unit of the finishing train is usually not arranged directly in the mass flow direction. In such a case, however, it is nevertheless expedient to set the entry speed into the rolling train as a function of the casting speed V0 in such a way that the casting speed is essentially free of any reaction from the entry speed of the rolling stock into the rolling train. Because the casting unit is only a short time dynamics with regard to control interventions. Due to this inertia, the casting unit is often the limiting aggregate.

If the rolling stock now runs out of the rolling train 2 with the outlet thickness H3 ', the thickness wedge is transported away in the direction of mass flow. In the rolling mill subsequent units, for example. The cooling section 8 or a in FIG. 1 not shown reel is now up to a certain time to process the old outlet thickness H3, then the transfer section X3, and then the new outlet thickness H3 '. The conversion of an aggregate from the processing of rolling stock according to the first pass schedule to the processing of rolling stock according to the second pass schedule takes place during the influencing of the transfer section X3 by the respective unit.

Since the cooling section 8 is usually longer than the transfer section X3, when passing through the cooling section 8 through the transfer section X3 part of the cooling section is operated such that it cools the first section G-1 of the rolling stock G as planned and that this second Section G-2 also on schedule, but in a modified, up the corresponding product co-ordinated way, cools. The changeover of the operation of the cooling section thus always takes place for the section of the cooling section 8, which currently influences the transfer section X3. As a result, the rejects of rolling stock continue to be kept low, as are the rolling mill 2 downstream in the mass flow direction of operation according to a first product plan on the operation according to a second product plan, the first pass schedule is assigned to the first product and the second pass schedule the second product , is converted.

In a particularly advantageous embodiment, during the transfer of the operation of the rolling train according to the first pass schedule in the operation of the rolling mill according to the second pass schedule each mill stand of the rolling mill operated such that each rolling mill takes place an equal relative change in Walzgutdicke. That the relative change in thickness in order to move from the first outlet thickness of the rolling train to the second outlet thickness of the rolling train is distributed equally over all the rolling mills of the rolling train.

By way of example, in a subsequent table, a first pass schedule and a second pass schedule, as well as an indication of the relative change in thickness during the transfer of the operation of the rolling mill according to the first pass schedule in the operation of the rolling mill according to the second pass schedule: Tab. 1 Inlet thickness [mm] relative reduction [%] Outlet thickness [mm] Roller circumferential speed Vi [m / s] Outlet thickness according to second stitch plan / outlet thickness according to first stitch plan Roller circumferential speed Vi according to the second stitch plan / roller circumferential speed Vi according to the second stitch plan first pass schedule Roll stand i = 1 15.00 40,00 9.00 1.67 Roll stand i = 2 9.00 40,00 5.40 2.78 Roll stand i = 3 5.40 25,00 4.05 3.70 Roll stand i = 4 4.05 10.00 3.65 4.12 second pass schedule Roll stand i = 1 15.00 50,00 7.50 2.00 Roll stand i = 2 7.50 40,00 4.50 3.33 Roll stand i = 3 4.50 25,00 3.38 4.44 Roll stand i = 4 3.38 10.00 3.04 4.94 Roll stand i = 1 0.83 1.20 Roll stand i = 2 0.83 1.20 Roll stand i = 3 0.83 1.20 Roll stand i = 4 0.83 1.20

By such a transfer of the operation of the rolling mill from an operation according to the first pass schedule in an operation of the rolling mill according to the second pass schedule, the relative thickness changes per rolling stand in the transfer is constant, it is achieved that a speed change, especially acceleration, the entire road only at the first modification of the rolling stand caused by the change in the pass plan must be carried out. That is, the speed change will occur in all scaffolds except on the scaffold where the thickness change is made, typically the rolling stand 1.

In this way, a change in the outlet thickness of the rolling stock from the rolling mill is achieved with low acceleration peaks and possibly constant mass flow through the rolling mill, whereby, for example, a rolling mill upstream in the mass flow direction casting unit is not affected in his operation by changing the outlet thickness in the rolling mill.

FIG. 2 shows a further possibility for implementing the invention for rolling mill 1 comprising a two-roll casting machine 6 ', wherein the cast rolling G then passes through a mehrgerüstige, ie at least zweigüstige, rolling train 2. Die Walzstraße 2 bzw.

By means of a two-roller casting machine 6 ', rolling stock G is generally produced in an endless operation. An advantage of this type of plant is that this is again more compact than an endlessly operating system, which by means of mold 6, see. FIG. 1 , pours. Furthermore, the energy and resource consumption is reduced again.

The compactness and the reduced use of resources result from the fact that by means of a Zweirollengießmaschine can be cast even closer to the final dimensions of the desired end product. That the rolling stock emerging from the roller casting machine is i.d.R. already considerably thinner than the rolling stock emerging from a mold. Thereby, e.g. a roughing mill or High Reduction Mill accounts, which are usually subordinated to a kokillenbetriebenen casting machine. This usually has the purpose of preparing the cast from the mold rolling for a finish rolling in a transforming manner. When using a Zweirollengießmaschine this is usually not required. Rather, it only requires a finish rolling of the rolling stock with the rolling mill. 2

Also in this case, it may be desired that a discontinued product expiring from the plant - for example, due to customer requests or priority changes - to be changed. For this purpose, an embodiment of the method according to the invention can advantageously be used.

For the conversion of the outlet product from a first outlet thickness to a second outlet thickness by means of a two-roll casting machine 6 'downstream rolling train 2, the operation of the rolling mill 2 according to the explanations FIG. 1 be converted so on the fly, that this goal is achieved. The remarks to FIG. 1 apply analogously for FIG. 2 ,

Claims (14)

1. Method for adjusting a discharge thickness (H3, H3') of rolling stock (G), in particular a hot strip, passing through a multi-stand mill train (2), wherein a first section (G-1) of the rolling stock (G) is rolled to a first discharge thickness (H3), wherein a second section (G-2) of the rolling stock (G) is rolled to a second discharge thickness (H3') which is different from the first discharge thickness (H3),
   characterised in that a transition from the first discharge thickness to the second discharge thickness taking place during the rolling, takes place at a feed rate (V0) of the rolling stock (G) into the mill train (2) which is adjusted as a function of a discharge rate (Vg) of the rolling stock (G) of a unit (6) which is arranged upstream of the mill train (2) in the mass flow direction.
2. Method according to claim 1,
   characterised in that the feed rate (V0) is adjusted substantially to the discharge rate of a subsequent unit (6) which is arranged upstream of the mill train (2).
3. Method according to claim 1 or 2,
   characterised in that the mill train (2) and at least one unit (6) which is arranged upstream of the mill train (2) in the mass flow direction, preferably a casting unit (6), are coupled for fabrication purposes by the rolling stock (G) having the first and the second rolling stock section.
4. Method according to one of claims 1 to 3,
   characterised in that a first pass schedule and a second pass schedule are predefined, wherein when the first pass schedule is executed the first discharge thickness (H3) is rolled, and when the second pass schedule is executed the second discharge thickness (H3') is rolled, wherein a transition is made from operation of the mill train (2) according to the first pass schedule during the rolling of rolling stock (G) into operation of the mill train (2) according to the second pass schedule, wherein the transition for each rolling stand (3, 4, 5) of the mill train (2) takes place substantially during the rolling of a defined transition section (X0, X1, X2) of the rolling stock (G) by means of the respective rolling stand (3, 4, 5).
5. Method according to claim 4,
   characterised in that the transition section (X0, X1, X2) is determined in such a way that at every point in time during its passage through the mill train (2) it has a length which is at most equal to a distance between two adjacent rolling stands.
6. Method according to claim 4 or 5,
   characterised in that the transition section (X0, X1, X2) is rolled by means of a plurality of rolling stands (3, 4, 5) which are included in the mill train (2), wherein at least one rolling stand (3, 4, 5) is operated as a rolling stand (3, 4, 5) with regulated rolling force during the rolling of the transition section.
7. Method according to one of claims 4 to 6,
   characterised in that during the rolling of the transition section (X0, X1, X2) an actual process variable which is set on the basis of the first pass schedule is continuously converted into a setpoint process variable which is determined on the basis of the second pass schedule.
8. Method according to one of claims 4 to 7,
   characterised in that during the rolling of the transition section (X0, X1, X2) a check is made to verify compliance with technical plant restrictions and if the restrictions are infringed or expected to be infringed, the transition from operation of the mill train according to the first pass schedule to operation of the mill train (2) according to the second pass schedule is interrupted.
9. Method according to one of claims 4 to 8,
   characterised in that the rolling force and/or the rolling gap of a rolling stand (3, 4, 5) which is to be passed through next by the transition section (X0, X1, X2) is adjusted, in addition to the first and second pass schedule, as a function of the strip tension between said rolling stand (4, 5) and the rolling stand (3, 4) which is arranged upstream of said rolling stand in the mass flow direction.
10. Method according to one of claims 4 to 9,
    characterised in that during the transition from operation of the mill train (2) according to the first pass schedule to operation of the mill train according to the second pass schedule, each rolling stand (3, 4, 5) of the mill train (2) is operated in such a way that the relative change from first to second discharge thickness is substantially constant for each rolling stand (3, 4, 5) of the mill train (2).
11. Method according to one of claims 4 to 10,
    characterised in that after the transition from operation of the mill train (2) according to the first pass schedule to operation of the mill train (2) according to the second pass schedule, a redistribution of drive loads of rolling stand drives which are assigned to the mill train (2) takes place during the rolling of the second discharge thickness (H3').
12. Method according to one of claims 1 to 11,
    characterised in that a change, necessary due to the changed discharge thickness (H3, H3') of the mill train (2), in manipulated variables for at least one unit (8) which is arranged downstream of the mill train (2) in the mass flow direction takes place while the transition section (X3) is being influenced by said at least one unit (8).
13. Open- and/or closed-loop control device (9) for a rolling mill (1) which includes a multi-stand mill train (2), having a machine-readable program code which has control commands which, when executed, cause the open- and/or closed-loop control device (9) to perform a method according to one of claims 1 to 12.
14. Rolling mill having a multi-stand mill train (2) for rolling metallic rolling stock (G), having an open- and/or closed-loop control device (9) according to claim 13, and having a device for supplying the discharge rate of the rolling stock (G) of a unit (6) which is arranged upstream of the mill train (2) in the mass flow direction to the open-and/or closed-loop control device (9) according to claim 13, wherein the rolling stands (3, 4, 5) of the mill train (2) are operatively connected to the open- and/or closed-loop control device (9).

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