EP2353742A1 - Heat rolling train for rolling hot rolled strips, method for operating same to roll hot rolled strips, control and/or regulating device - Google Patents

Abstract

The hot rolling mill (1) comprises a cooling section (4) for cooling the hot strips, and strip driving devices arranged in a mass flow direction after the start of the cooling section and in mass flow direction before the end of the cooling section, where a tensile stress of the hot strips is adjustable by the strip driving device. Two adjacent strip driving devices have an interval f 20-50 m. The cooling section has cooling segments (5) releasing a cooling agent spaced apart from each other in the mass flow direction. The strip driving device is formed as a set of driving rollers. The hot rolling mill (1) comprises a cooling section (4) for cooling the hot strips, and strip driving devices arranged in a mass flow direction after the start of the cooling section and in mass flow direction before the end of the cooling section, where a tensile stress of the hot strips is adjustable by the strip driving device. Two adjacent strip driving devices have an interval f 20-50 m. The cooling section has cooling segments (5) releasing a cooling agent spaced apart from each other in the mass flow direction. The strip driving device is formed as a set of driving rollers, where the strip driving device is arranged between all the adjacent cooling segments. A further strip driving device is arranged upstream and/or downstream to the cooling section in the mass flow direction. Independent claims are included for: (1) a method for operating a hot rolling mill; and (2) a control- and/or regulating device for a hot rolling mill.

Description

The invention relates to a hot rolling mill for rolling hot strip, comprising a cooling section for cooling the hot strip. Furthermore, the invention relates to a method for operating a hot rolling line for rolling hot strip, wherein the hot strip is rolled by means of at least one roll stand, wherein the rolled strip passes through a cooling section, wherein the cooled by means of the cooling section hot strip is wound on a reel. Moreover, the invention relates to a control and / or regulating device for a hot rolling mill.

The patent application relates to the technical field of hot rolling technology. In hot rolling, in particular of metal strips, a solid metal piece of liquid metal is produced by means of any casting process, for example a slab which is processed by further processing, in particular rolling and cooling, to form a hot strip end product which is wound up at the end of the hot rolling train to form a hot strip bundle. The hot rolling process essentially determines the geometric dimensions of the hot strip and its material properties.

The temperature of the metal strip changes during the hot rolling process and ranges from about 500 ° C to 600 ° C in the reel, so-called coiler temperature, at the end of the hot rolling mill to temperatures of about 1300 ° C to 1400 ° C in mass flow direction of the reel upstream areas of the hot rolling mill.

Modern material grades, especially steel grades, are produced by sophisticated cooling strategies. The microstructure is depends on a specific cooling process. Examples of such cooling methods of hot strip are, for example, in EP 1244816-B1 disclosed as well as in DE 10129565 B4 , Such methods make it possible to adjust the material properties of the hot strip in a desired manner with high accuracy.

However, even small disturbances in the cooling can lead to serious microstructural inhomogeneities of the hot strip. With such structure inhomogeneities flow resistance fluctuations are connected, which in turn lead to barely controllable thickness errors in a subsequent cold rolling of the produced hot strip. Microstructure inhomogeneities or microstructural disturbances in the material structure, which occur at a frequency of more than one microstructure disturbance per meter of hot strip, are no longer manageable under production-oriented rolling speeds in the cold rolling mill by means of the actuators available on the market. Such microstructural disturbances occur increasingly in the area of the beginning of the tape, also called tape head, and the end of the tape, also called tape foot.

As a result of this microstructural disorder, needle-shaped, i.e. spatially limited, but magnitude large thickness error, which violate the allowable thickness tolerances. These defective band areas must be removed before further processing in an additional step. Thus, the processing costs for the metal strip is increased by such errors and the throughput reduced by the increased scrap content.

The object of the invention is to increase the quality of a manufactured hot strip, in particular to reduce microstructural inhomogeneities of the hot strip in the region of the band foot and / or the beginning of the strip.

An apparatus part of the object is achieved by a hot rolling mill of the type mentioned, wherein at least one in mass flow direction after the start of the cooling section and in Mass flow direction arranged before the end of the cooling section belt drive device is present, by means of a, in particular different from zero, tensile stress of the hot strip is adjustable. Alternatively, for the term belt drive device, the term belt influencing device can be used. Essential for this type of device is that by means of this a tensile stress on the band can be acted upon.

By tape drive means is meant any device which is capable of tensioning the tape, i. with a tension in the direction of transport of the metal strip to apply.

The inventor has recognized that the structural inhomogeneities of the strip beginning region and the strip end region are due to their draft-free state when passing through the cooling section. Because the lack of tension during threading and / or unthreading of the hot strip leads to unevenness of the strip are present, which increase by cooling in the cooling section, which leads to lowering and lifting of the metal strip, which cause an uneven deflection of the cooling water. Thus, for example, the water of the cooling section collects in depressions of the band, while on the other hand, the water flows quickly away from the elevations of the band. The consequent unevenness of the cooling leads to the above structural inhomogeneities. These can be reduced by putting a tension-free band area in the cooling section under tension during threading. This is achieved with the hot rolling mill according to the invention by providing at least one belt drive device between the beginning of the cooling section and the end of the cooling section, by means of which a strip section of the hot strip passing through the cooling section can be subjected to a tensile stress. The start of the cooling section and the end of the cooling section is to be defined with regard to the mass flow direction of the rolling train. That is, where the tape enters the cooling section is the beginning of the cooling section; there where the tape runs out of the cooling section is the end of the cooling section.

The length of the band, which is subject to error as a result of the structure inhomogeneities, depends on which distance, for example, the beginning of the tape is to be moved in the cooling section before a tension for the band can be established.

In conventional hot rolling mills, such a device, which can build up tension, is typically the last mill stand of the finishing train and a driver roll set which is located just before the reel. Between these two facilities is the cooling section and in practice, depending on the type of hot rolling mill, up to several hundred meters.

As a result, in the prior art, the tape undergoes, during threading, that distance between the last roll stand and driver roll set prior to the reel in draft-free condition, i. in particular, the cooling section.

When unthreading there is an analogous situation. As soon as the strip foot has left the last rolling stand, the strip share from the strip foot to the set of driver rolls immediately before the reel is no longer under tension. There is therefore a cooling for these parts of the tape without train.

This effective length of the tensionless cooled strip portion, ie the strip portion which passes through the cooling line without tension at the beginning and end of the strip, can be significantly reduced by the hot rolling mill according to the invention, whereby the above-described, previously existing structure inhomogeneities can be avoided for a considerable band share. As a result, the thickness errors during cold rolling can be largely avoided, whereby the caused by the thickness error scrap accumulation is also greatly reduced.

In an advantageous embodiment of the hot rolling mill according to the invention a plurality of belt drive means is provided. These are arranged between the beginning of the cooling section and the end of the cooling section. Since the maximum distance between two devices which are able to build up a tensile stress determines the band region - both at the beginning of the strip and at the end of the strip - which passes through the cooling section without tension, it is advantageous to shorten this distance by using a plurality of belt drive devices , By providing a plurality of belt drive means between the beginning and the end of the cooling section, this shortening can be achieved. Because the more belt drive devices are provided and the smaller the maximum distance between two adjacent belt drive devices, the lower the proportion of the belt which passes through the cooling section without tension. By virtue of a correspondingly high number of belt drive devices, it is therefore possible to reduce the band gap passing through the cooling section so that this proportion is almost negligible in relation to the total length of the hot strip.

In a preferred embodiment, two adjacent belt drivers are spaced more than 10 meters and less than 70 meters, more preferably more than 20 meters and less than 50 meters. Such an arrangement is advantageous in that the band portion, which passes through the cooling section without tension, on the one hand greatly reduced. On the other hand, the number of required tape drive means, however, is not so high that here a plurality of, in particular more than ten, tape drive means must be provided, which reduce the thickness errors during cold rolling in the band foot area and in the tape head area. At the intervals mentioned above, therefore, the effect is good and the technical effort, in particular for retrofitting the belt drive devices, limited for the operator of the hot rolling mill.

In a further advantageous embodiment, the cooling section in the mass flow direction at least two spaced-apart cooling segments, wherein between the cooling segments, a belt drive device is arranged. This has the advantage that the tape drive device is not constantly sprayed from the cooling section with water, and so possibly their life is reduced.

On the other hand, it may be desired as an advantageous embodiment that the belt drive devices arranged between the beginning and the end of the cooling section are cooled with coolant from the cooling section, in particular continuously. Because this ensures that the respective belt drive device does not overheat during adjustment of the tension. Because it should be remembered that hot strip in the cooling section depending on the location in the cooling section can still have a significant temperature, which is a burden on the belt drive device.

In a further advantageous embodiment of the invention, the cooling section in the mass flow direction on a plurality of spaced-apart cooling segments, wherein between each respective adjacent cooling segments, a belt drive means is arranged. As a result, the reduction of microstructural inhomogeneities in the hot strip is achieved particularly advantageous.

It is likewise particularly advantageous for the cooling section to be preceded and / or arranged downstream of at least one further belt drive device in the direction of mass flow. It is particularly advantageous if the beginning of the cooling section directly upstream of a belt drive means and the end of the cooling section is immediately downstream of a belt drive means, wherein the respective belt drive means is configured such that the tape drive means continuous belt can be acted upon with a tensile stress. An immediately preceding the cooling section in the direction of mass flow belt drive device has the advantage that when the hot strip from the rolling train, especially if the end of the tape has left the last stand of the rolling mill, a tension for the band can be maintained throughout the cooling section. This is namely possible as long as the end of the tape has passed the immediately preceding the cooling section upstream tape drive means.

An immediately downstream of the cooling section in the direction of mass flow belt drive device has the advantage that during the threading of the hot strip early in the entire cooling section, a tensile stress is built, although the band may not yet reached the reel. As a result, the proportion of the strip, which has structure-inhomogeneities due to the draft-free passage of the cooling section, significantly reduced.

It is advantageous that at least one belt drive device comprises a set of driver rollers. Preferably, all the tape drive means are each formed as a set of driver rollers with associated drive means. The use of driver rollers as a belt drive device seems particularly suitable because they do not have a large footprint and, for example, can be easily arranged between the adjacent cooling segments of the cooling section. Driver roller sets are well suited for applying tension to a belt.

A procedural part of the object is achieved by a method of the type mentioned above, wherein at least in the presence of a free end of the hot strip between the reel and upstream of the cooling section in the mass flow direction upstream rolling stand at least one arranged between the beginning and the end of the cooling section belt drive means operated in such a way is that by means of this a tensile stress on a section of the hot strip passing through the cooling section is acted upon. The above-mentioned advantages to the device Solution apply analogously to the procedural part of the solution.

In an advantageous embodiment, a plurality of belt drive means is arranged between the beginning of the cooling section and the end of the cooling section, wherein during the threading of a belt into the rolling mill, a first belt drive device is brought into engagement with the belt after the belt head has passed the first belt drive device, and the first tape drive means is disengaged from the tape after the tape head has passed a second tape drive means following in the mass flow direction. As a result, a simple and possible error-free tension control during threading is achieved.

In particular, it is advantageous that the first tape drive means is disengaged while the second tape drive means is brought into engagement with the tape. This has the advantage that the tension - with the exception of the transfer period from the first belt drive device to the second belt drive device - is essentially always provided by only one belt drive device. This avoids a dynamic load distribution of the tape drive means which would always have to be adjusted if additional tape drive means were brought into engagement with the tape. This is technically complex and requires a higher error rate. In particular, it is avoided by the above procedure that arise by unwanted load deviations of the first and second belt drive means tensionless areas between the first and the second belt drive means, which are undesirable during cooling. In order to avoid or reduce this safely, in turn, a train control would have to be provided for the cooling section, which can be saved by the above procedure.

A tape drive means is considered to be "engaged" if it fulfills a tape driver function, ie still able to build a tension for the band. By "engaging" is meant the process in which a tape drive means has an initial state in which it is not "engaged" with the tape and is transferred to a final state in which it "engages" the tape is. This applies analogously to the formulation "disengage" or a tape drive device "disengage".

It is particularly advantageous that the first belt drive device and the second belt drive device are operated such that they are simultaneously in engagement with the belt, at least for a limited period of time. This is particularly important when transferring the tensile structure from the first belt drive device to the second belt drive device. Because so a desired tensile stress can be maintained upon transfer of the tensile structure from the first belt drive means to the second belt drive means, i. the belt is not draft-free during the transfer of the tensile structure from the first belt drive device to the second belt drive device.

A preferred variant is that the first belt drive means so out of engagement with the belt and the second belt drive means are brought into engagement with the belt, that during the transfer of tensile structure from the first belt drive means to the second belt drive means a tensile stress of the belt already Beginning of the transfer by means of the first belt drive device under train set band area always greater than zero in amount, preferably greater than a predetermined threshold is. In particular, it is advantageous that the tensile stress of the belt area set under tension by means of the first belt drive device is constant during the transfer. By the described modes of operation is achieved that during threading or unthreading of the strip from the rolling mill as little as possible or no structural inhomogeneities are produced by the operation of the belt drive means, and the structure inhomogeneities are limited to the smallest possible band rate.

In a further embodiment of the method according to the invention, a plurality of belt drive means is arranged between the start of the cooling section and the end of the cooling section, during the Ausfädelns a tape from the rolling train, a first belt drive means is brought into engagement with the tape before the tape end has passed this first belt drive means , and a second mass-flow direction-following second tape drive means is brought into engagement with the tape before the tape end has passed the first tape drive means. As a result, the microstructural inhomogeneities of the strip are kept as low as possible during unthreading.

Preferably, the at least one belt drive device, in particular the plurality of belt drive devices, is brought out of engagement with the belt during stationary operation of the mill train. In stationary operation of the mill train, i. during a substantially error-free operation, which does not involve threading and unthreading the strip from the mill train, it is not necessary to operate the at least one tape drive means, since in this case the strip is tensioned in the cooling section and possibly occurring in a conventional manner Microstructure inhomogeneities are usually not caused by the absence of a band tension in the cooling section.

The invention also extends to a data carrier with a machine-readable program code for a control and / or regulating device according to claim 15, wherein the program code comprises control commands, which causes the control and / or regulating device to carry out the method according to one of claims 8 to 14 ,

Furthermore, the invention also extends to a machine-readable program code for a control and / or regulating device according to claim 15, wherein the program code comprises control commands, which causes the control and / or regulating device to carry out the method according to one of claims 8 to 14.

The invention can be used for both one way hot rolling mills and reversing hot rolling mills.

FIG 1

einen Ausschnitt einer schematisch dargestellten Warmwalzstraße in einer ersten Ausführungsform der Erfindung,

FIG 2

einen Ausschnitt einer schematisch dargestellten Warmwalzstraße mit einer zweiten Ausführungsform der Erfindung,

FIG 3

ein Ablaufdiagramm zur Veranschaulichung einer Ausführungsform des erfindungsgemäßen Verfahrens beim Einfädeln,

FIG 4

ein Ablaufdiagramm zur Veranschaulichung einer Ausführungsform des erfindungsgemäßen Verfahrens beim Ausfädeln.

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

FIG. 1

a detail of a schematically illustrated hot rolling mill in a first embodiment of the invention,

FIG. 2

a detail of a schematically illustrated hot rolling mill with a second embodiment of the invention,

FIG. 3

a flow diagram illustrating an embodiment of the method according to the invention during threading,

FIG. 4

a flow diagram illustrating an embodiment of the method according to the invention during unthreading.

FIG. 1 shows a schematic representation of a hot rolling line 1, by means of which metallic hot strip B can be produced. The hot rolling mill 1 is supplied to warm rolling stock, for example. From a casting device, not shown. Alternatively, heated slabs can be fed to the rolling train, which are rolled.

In the exemplary embodiment, the rolling train 1 comprises a finishing train 2 for finish rolling of the hot strip B to its target outlet thickness. The finishing train 2 includes rolling stands, from which in the mass flow direction last mill stand 3 in FIG. 1 is shown.

As a rule, a finishing train comprises three scaffolds or more. In particular, this may be four, five or six-stand construction.

In the case of a reversing hot rolling mill, not shown, a so-called Steckel Mill, the rolling train may also comprise only a single or two rolling stands. For the implementation of the invention, the number of existing stands is of minor importance. As a rule, however, a rolling train comprises at least one rolling stand.

The finishing train 2 is followed by a cooling section 4 in the present hot rolling mill 1, by means of which the mechanical properties, such as phase components and microstructure of the strip B, are set.

After the cooling section 4, the cooled hot strip B reaches a reel 6, by means of which the hot strip B is wound up into a hot strip collar.

The hot rolling mill 1 further shows a plurality of sets of driver rollers 7, 8, 9, 10 and 11, respectively, which are arranged between the last rolling stand 3 of the finishing train 2 and the reel 6. These are used to apply the hot strip B as long as possible during the threading and / or unthreading of the hot strip B with a train greater than zero over the widest possible parts in the cooling section 4. The driver roller sets 7, 8, 9, 10 and 11 shorten that portion of the belt which passes the cooling section in the tension-free state. This improves the quality, in particular the microstructure, of the produced strip, since thus the strip share at the beginning of the strip and at the strip base, which is cooled without tension in the cooling section and thus has increased structure inhomogeneities, is reduced. In particular shows FIG. 1 a driver roller pair 10 arranged directly in the mass flow direction in front of the cooling section 4 and a driver roller pair 11 arranged immediately downstream of the cooling section in the mass flow direction FIG. 1 a first driver roller pair 7, a second driver roller pair 8 and a third driver roller pair 9, which is arranged between the beginning and end of the cooling section 4.

The number of driver roles between the beginning and end of the cooling section is relatively freely selectable by the skilled person. This is a cost / benefit analysis, as the installation of a pair of driver rolls causes a certain expense. In return, however, the quality of the band is increased. The more pairs of driver rollers are used and the smaller their spacing, the lower the proportion of the band which has microstructural inhomogeneities.

For an advantageous cost / benefit ratio, it has been found practicable to distribute tape drive devices, such as pairs of drive rollers, over the entire cooling path, with the distance between adjacent belt drive devices being equidistant and chosen between 20 and 50 meters.

According to FIG. 1 the cooling section 4 is divided into a plurality of cooling segments 5, which are operable independently of each other. Between the respective cooling segments 5, a set of driver rollers 7, 8 and 9, in the present case, a driver roller pair 7, 8 and 9 respectively. Immediately in the mass flow direction before the cooling section and immediately in the mass flow direction after the cooling section, a further pair of drive rollers 10 and 11 is arranged in each case.

The pairs of driver rollers 7, 8, 9, 10 and 11 are independently operable. In stationary operation of the hot rolling mill, the pairs of driver rollers 7, 8, 9, 10 and 11 are preferably out of engagement with the belt B.

Alternatively, they may be engaged with the band. This is possible in principle, but requires a more complex control.

Immediately before and behind the cooling section 4, a further pair of driver rollers 10 and 11 is arranged in each case. This is particularly advantageous because in this way the band portion, which passes through the cooling section 4 at the beginning and end of the production process without tension, can be further shortened.

The spacing of adjacent pairs of driver rollers, e.g. the first driver roller pair 9 from the second driver roller pair 10 is preferably between 20 meters to 50 meters. The spacing of adjacent pairs of driver rollers may be variable. This allows for local features, e.g. structurally, to enter along the rolling mill. Preferably, however, the distance between adjacent pairs of driver rollers is equidistant. In the exemplary embodiment, the distance between adjacent driver rollers should each be 40 meters. As a result, the best possible cost / benefit ratio is achieved for commonly used cooling sections achieved.

The driver roller pair 7, 8, 9, 10, 11 are operatively connected to a control and / or regulating device 20. The control and / or regulating device is prepared for carrying out an embodiment of the method according to the invention, for example 3 and FIG. 4 realized embodiments. For this purpose, the control and / or regulating device 20 is supplied with machine-readable program code 22 and preferably stored in memory-programmed form. The program code 22 includes control commands which, when executed, cause the control and / or regulating device to carry out the method. The transmission of the program code 22 to the control and / or regulating device 20 can take place, for example, via a data carrier 21, for example a CD, DVD or a flash memory, or via a network to which the control and / or regulating device 20 is connected is.

The operation of a rolling mill 1 according to FIG. 1 is determined by the 3 and FIG. 4 therefore explains and follows below.

FIG. 2 shows a similar hot rolling mill like FIG. 1 , The hot rolling mill according to FIG. 2 differs only from the in FIG. 1 shown that the cooling section 4 not in spaced cooling segments 5, see FIG. 1 , is divided. Rather, the cooling section 4 is formed continuously. Thus, the plurality of pairs of driver rollers 7, 8 and 9, respectively, are exposed to continuous cooling by the cooling section 4, which may thus be - if desired - continuously in engagement with the hot strip B to be cooled. By cooling the arranged between the beginning and end of the cooling section driver roller pairs 7, 8 and 9, an overheating of the pairs of driver rollers 7, 8 and 9 is avoided.

As well in 1 and FIG. 2 are the pairs of driver rollers 7, 8, 9, 10 and 11 intended to apply this during the input and / or Ausfädelns of hot strip this with a tensile stress, in particular a band portion, which is located between the beginning and end of the cooling section. As a result, microstructural inhomogeneities are reduced for those band shares, which would arise when cooling this band portions in draft-free state.

FIG. 3 shows a possible advantageous operation of the drive roller pairs when threading the tape in the rolling train. In this case, it is assumed that all pairs of driver rollers are open, ie the tape head can run in without hitting the outer surface of the driver rollers.

The process step 100 indicates that the strip is subjected to a threading operation in the rolling train. The belt thus passes in the mass flow direction one unit after another in the direction of the reel.

Immediately in the mass flow direction before the cooling section is a first pair of drive rollers, see FIG. 1 or 2 driver roller pair 10, arranged. In a method step 101, it is checked whether the beginning of the tape has already reached this pair of driver rollers. If this is not the case, the event "Passing the beginning of the tape" will continue to be checked for the next pair of driver rollers to be traversed by the tape head. This can be done, for example, by means of a suitable measuring device and / or a tape tracking calculation.

If the beginning of the tape or tape head has passed the pair of driver rollers arranged directly in front of the cooling section, then in a method step 102 this pair of driver rollers is brought into engagement with the tape and a set tension for the tape portion between the last stand of the finishing train and the pair of driver rollers is set immediately before the cooling section.

In a method step 103, it is checked whether the beginning of the tape already contains the following pair of driver rollers, that is to say the pair of driver rollers 7, following the pair of driver rollers arranged immediately before the cooling section FIG. 1 respectively. FIG. 2 , happened. If this is not the case, it is checked further for occurrence of this event.

If the beginning of the tape has the first pair of drive rollers 7, see FIG. 1 in the cooling section, this is brought into engagement with the strip in a method step 104.

At least at times in parallel with the process of engaging the first pair of driver rollers 7, see FIG. 1 respectively. FIG. 2 in the cooling section, the driver roller pair 10 is brought out of engagement with the belt before the cooling section. This is done in a step 106. The structure of the tension for the arranged between the finishing line and cooling section band share is thus transferred from the pair of drive rollers immediately before the cooling section on the first pair of drive rollers in the cooling section, ie between the beginning and end of the cooling section. In this case, the transfer of the tensile stress, ie the pairs of driver rollers involved in the transfer of the tensile stress, controlled such that the tension of the band portion between the last frame of the finishing train and the immediately before the cooling section arranged driver roller set remains substantially constant.

This transfer of the drive train of drive roller pairs is successively carried out for adjacent mass flow direction consecutive driver roller pairs, i. From the driver roller pair 7 to the driver roller pair 8, from the driver roller pair 8 to the driver roller pair 9 and from the driver roller pair 9 to the driver roller pair 11. The transfer of the tensile structure from a pair of driver rollers on the next in the mass flow direction driver roller pair is always then after the beginning of each band in the mass flow direction next driver roller pair happened.

In a method step 107 it is checked whether the beginning of the strip in the mass flow direction or transport direction last pair of driver rollers, ie according to FIG. 1 respectively. FIG. 2 the driver roller pair 11, has happened. If this is not the case, continue as described above. In the exemplary embodiment, the last driver roller pair is the driver roller pair, which is located immediately behind the cooling section in the mass flow direction.

If the beginning of the tape has passed the last pair of drive rollers in the mass flow direction, then this last pair of drive rollers remains in engagement until the tape has reached the reel and a tension has been built up by means of the reel.

Whether the belt has already reached the reel is checked in a method step 108.

If the beginning of the tape has reached the reel, then the last pair of drive rollers and the reel are operated in such a way that the tension of the tape part already under tension and passing through the cooling section is transferred from the last pair of drive rollers to the transfer unit The reel is always greater in magnitude than zero, preferably constant and equal to the tension value set prior to the transfer of the tensile structure to the reel.

As soon as the reel has taken over the tensile structure for the metal strip, the last pair of driver rolls is disengaged in a method step 109. The rolling train is then in stationary operation. All driver roles are then disengaged in the present example.

FIG. 4 shows an exemplary procedure for a Ausfädelvorgang for in FIG. 1 respectively. FIG. 2 shown hot rolling mills. Also in this case it is assumed that at the beginning of the threading all pairs of driver rolls according to FIG. 1 respectively. FIG. 2 are out of engagement with the tape.

In a process step 200, the threading of the strip from the hot rolling line is started, i. There is a free end of the tape, especially band foot, in the rolling mill before.

In a method step 201, it is checked whether the belt foot has passed a predetermined reference point before the last rolling stand. This reference point can be arranged between the last in the mass flow direction and injured framework of the finishing train, or even further forward, possibly even in the direction of mass flow in front of the first stand of the finishing train. As long as the band foot has not passed the given reference point, the test will continue. The reference point is preferably to be determined such that it is ensured that when transferring the tensile structure, the tensile stress does not become zero, i. a corresponding reaction time for the system is taken into account.

If the band foot has reached the reference point, the pair of driver rollers arranged directly in front of the cooling section is brought into engagement with the band in a method step 202 so that the construction of a tensile stress in the cooling section can be adopted with this at the latest the strip foot emerges from the last mill stand of the finishing train.

This ensures that the pair of driver rollers can build up a tensile stress in the cooling section before the belt foot leaves the last rolling stand. If this were not the case, the tensile stress in the cooling section would collapse when the strip foot emerges from the last stand of the finishing train. Thus, the strip arranged between the last stand of the finishing train and the end of the cooling section would pass through the cooling section at least partially without tension, which can lead to the structure inhomogeneities described above. By bringing the first mass flow direction pair of driven rollers into engagement with the belt before the belt foot has passed the finishing mill last mill, this problem can be avoided by continuing to build tension for that part of the belt which is interposed between them Start and end of the cooling section is located.

In a method step 203, it is checked whether the belt foot has passed a predetermined reference point in the direction of mass flow in front of the pair of driver rollers arranged immediately before the cooling section.

If this is not the case, further testing is performed until the belt foot passes the predetermined reference point.

In a method step 204, the pair of driver rollers following the pair of driver rollers located immediately in front of the cooling section is then brought into engagement with the band. In 1 and FIG. 2 this corresponds to the first driver roller pair, which is arranged in the mass flow direction between the beginning and end of the cooling section.

The first pair of driver rollers is brought into engagement with the belt in such a manner that it does not exceed the upstream of the mass flow direction at the latest when the belt foot exits Driver roller pair has built a tension for that part of the belt, which extends between the first pair of drive rollers and the end of the cooling section.

As soon as a tensile stress is built up by the first pair of driver rollers, either the pair of driver rollers arranged immediately in front of the cooling section can be opened. This has the advantage that the tension is generated only by a driver set of rollers. Alternatively, the driver roller pair arranged immediately in front of the cooling section can remain closed until the belt foot has passed through it. Between these boundary conditions can be varied as desired. For example. The upstream driver roll set can also be opened just before passing the belt foot to improve the tape run.

The method described for the pair of driver rollers arranged immediately in front of the cooling section and the first pair of driver rollers between the beginning and the end of the cooling section is applied successively and analogously to the following pairs of driver rollers. Thus, the driver roller pair adjacent in the mass flow direction is always closed before the belt foot has passed upstream and adjacent driver roller pairs in the mass flow direction. This happens as long as, for example, the last pair of driver rollers, ie according to 1 and FIG. 2 the pair of driver rollers immediately behind the cooling section, is engaged.

In a method step 205, it is checked whether the belt foot has passed a predetermined, in mass flow direction the last pair of drive rollers upstream reference point. Depending on the control strategy, then the last driver roll pair can be opened or disengaged, closed, i. be kept in operation or otherwise operated.

Since the last set of driver rollers immediately after the cooling section in particular no longer exerts any influence on the tension in the cooling section, if no further upstream Driver sets are more in engagement with the tape, this is left to the discretion of the expert.

Possibly. can be completely dispensed with the engagement of the last driver set of rollers during the unthreading of the tape, as this pair of driver rollers usually provides the greater advantages during threading.

Claims (15)

Hot rolling mill (1) for rolling hot strip (B), comprising a cooling section (4) for cooling the hot strip (B),
characterized by at least one in the mass flow direction after the start of the cooling section (4) and in the mass flow direction before the end of the cooling section (4) arranged belt drive means (7, 8, 9), by means of a tension of the hot strip (B) is adjustable. Hot rolling mill according to claim 1,
characterized by a plurality of in the mass flow direction after the start of the cooling section (4) and in the mass flow direction before the end of the cooling section (4) arranged belt drive means (7, 8, 9). Hot rolling mill according to claim 2,
characterized in that two adjacent belt drive means (7, 8, 9, 10, 11) have a distance of more than 10m and less than 70m, in particular more than 20m and less than 50m. Hot rolling mill according to claim 2 or 3,
characterized in that the cooling section (5) in the mass flow direction at least two spaced apart coolant dispensing cooling segments (5), wherein between the cooling segments (5) a belt drive means (7, 8, 9) is arranged. Hot rolling mill according to claim 4,
characterized in that the cooling section (4) in the mass flow direction has a plurality of spaced-apart cooling segments (5), wherein between each respective adjacent cooling segments (5) a belt drive means (7, 8, 9) is arranged. Hot rolling mill according to one of the preceding claims,
characterized in that the cooling section (4) at least one further belt drive means (10, 11) is arranged upstream and / or downstream in the mass flow direction. Hot rolling mill according to one of the preceding claims,
characterized in that the at least one tape drive means (7, 8, 9, 10, 11) is formed as a set of drive rollers (7, 8, 9, 10, 11). Method for operating a hot rolling train (1) for rolling hot strip (B), wherein the hot strip (B) is rolled by means of at least one roll stand (3), wherein the rolled strip passes through a cooling section (4), wherein the means of the cooling section (4 ) cooled hot strip (5) on a reel (6), characterized in that at least in the presence of a free end of the hot strip (B) between the reel (6) and the cooling section (4) upstream in the mass flow direction last mill stand (3) at least one between the beginning and the end of the cooling section (4) arranged belt drive means (7, 8, 9, 10, 11) is operated such that by means of this a tensile stress on the cooling section (4) passing portion of the hot strip (B) acted upon becomes. Method according to claim 8,
characterized in that a plurality of belt drive means (7, 8, 9, 10, 11) between the beginning of the cooling section (4) and the end of the cooling section (4) is arranged, wherein during the threading a first belt drive means (7, 8, 9, 10, 11) is brought into engagement with the belt (B) after the beginning of the belt has passed the first belt drive means (7, 8, 9, 10, 11), and at least one of the first belt drive means (7, 8, 9, 10, 11) in the mass flow direction following second belt drive means (7, 8, 9, 10, 11) brought into engagement with the belt after the beginning of the tape has passed the second tape drive means (7, 8, 9, 10, 11). Method according to claim 9,
characterized in that the first tape drive means (7, 8, 9, 10, 11) is disengaged while the second tape drive means (7, 8, 9, 10, 11) is brought into engagement with the tape (B). Method according to claim 10,
characterized in that the first tape drive means (7, 8, 9, 10, 11) and the second tape drive means (7, 8, 9, 10, 11) are operated to disengage during the process bring at least temporarily simultaneously engaged with the band. Method according to claim 10 or 11,
characterized in that the first tape drive means (7, 8, 9, 10, 11) are disengaged from the tape and the second tape drive means are engaged with the tape so as to disengage during the process a tensile stress of the belt (B) of an already prior to the start of the process by means of the first belt drive means (7, 8, 9, 10, 11) under train set band area always greater than zero, in particular greater than zero and substantially constant, is. Method according to one of claims 8 to 12,
characterized in that a plurality of belt drive means (7, 8, 9, 10, 11) between the beginning of the cooling section (4) and the end of the cooling section (4) is arranged, wherein during the Ausfädelns a band (B) from the rolling train (1 ) a first tape drive means (7, 8, 9, 10, 11) is brought into engagement with the tape (B) before the tape end has passed through said first tape drive means (7, 8, 9, 10, 11) and a second tape drive means in mass flow direction subsequent tape drive means (7, 8, 9, 10, 11) is brought into engagement with the tape (B) before the tape end passes the first tape drive means (7, 8, 9, 10, 11). Method according to one of claims 8 to 13,
characterized in that the at least one belt drive means (7, 8, 9, 10, 11), in particular the plurality of belt drive means (7, 8, 9, 10, 11), during stationary operation of the rolling train (1) is disengaged from Band is brought. Control and / or regulating device for a hot rolling mill (1), having a machine-readable program code which has control commands which cause the control and / or regulating device to carry out the method according to one of Claims 8 to 14.

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