DE20011832U1 - Device for the correct winding of a rolled hot strip in a reel device - Google Patents

Description

KING · PALGEN

Patent Attorneys *..**..· *.,··..·

Lohengrinstrasse 1 1 · 4D549 Düsseldorf · Tel. D21 1-3O2O2OO · Fax &Ogr;21 1-3&Ogr;2&Ogr;2&Ogr;1

3 August 2000
43 578 K

B F I VDEh Institute for Applied Research GmbH

Sohnstraße 65, 40237 Düsseldorf

ThyssenKrupp Steel AG

Kaiser-Wilhelm-Strasse 100, 47166 Duisburg

" Device for the correct winding of a rolled hot strip in

a reeling device"

The invention relates to a device for the correct positional winding of a metal strip, in particular a rolled hot strip, in a coiling device, wherein the hot strip is fed to the coiling device via a driving device with driving rollers, the driving rollers can be inclined relative to one another via a controller by means of actuators for changing the driving roller gap and the resulting influence on the lateral position of the hot strip, and the position of the edge of the hot strip in front of the driving device is fed to the controller as a measured variable and as a target reference variable.

Furthermore, the invention relates to a device for the correct winding of a rolled hot strip in a coiling device, with

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a driving device with driving rollers feeding the hot strip to the coiling device, with actuators and a controller for this purpose for changing the driving roller gap and the resulting influence on the lateral position of the hot strip and with a measuring device for determining the position of the edge of the hot strip in front of the driving device, the measured values of which are fed to the controller.

It is generally known that in hot strip rolling, the finished hot strip is transported from the run-out roller table through a cooling section, preferably a system of spray water nozzles, to a coiling device after it leaves the last stand of the finishing train. The hot strip is wound up into coils by the coiling device. In the area in front of the coiling device, the hot strip on the run-out roller table can be guided by side guides that can be hydraulically adjusted to the strip edges in order to align the rolled hot strip for entry into the coiling device. Accordingly, the side guides are in contact with the strip edges of the hot strip during the coiling process.

At the end of the run-out roller table there is a driving device which essentially consists of a lower driving roller which is mounted in the frame of the reeling device and an upper driving roller which is mounted in a driving rocker. The upper driving roller can be pivoted using hydraulic cylinders to set and adjust the gap between the driving rollers. With the aim of stabilizing the strip, primarily curved lower driving rollers or driving rollers with a cylindrical middle section and conical roller ends are used. The main functions of the driving device, including its drives, are to pull the beginning of the rolled strip coming from the finishing train tight, to guide the incoming strip tip towards the reeling device and to ensure retraction against the reeling device during the winding process.

The main components of the coiling device are an expandable mandrel for winding up the rolled strip, pressure rollers and guide shells for guiding the rolled strip during the winding process, and a mandrel drive. The free mandrel end (coil pull-off side) is generally supported during coiling by a pivoting mandrel bearing.

To start the winding process, the tip of the hot strip coming from the finishing stand is deflected by the pair of drive rollers from the level of the run-out roller table down to the winding mandrel. The pressure rollers and the guide shells of the coiler device then guide the beginning of the strip several times around the rotating mandrel. The mandrel consists of several segments that are continuously spread apart shortly after the arrival of the tip of the strip until the strip is wound into tightly fitted turns. The main functions of the coiler device are to ensure the positive connection between the beginning of the strip and the mandrel, to support the coil created during winding and to apply a defined tension to the strip during winding.

Furthermore, the German patent application DE 38 28 356 A1 already discloses a method for influencing the position of hot strip, which is fed to a coiling device via a pair of drive rollers, as well as a drive device for carrying out this method. In this strip position control method, the strip is guided for the coiling device exclusively via an asymmetrical adjustment of the drive roller gap using a pivoting upper drive roller. For this purpose, the upper drive roller is mounted in a driver swing, which has a hydraulic adjustment and balancing. This also means that the side guide rulers are open during the coiling process.

The adjusting effect of this driving device in relation to the hot strip is based on a local shift of the point of application of the strip tensile force and the resulting non-uniform elastic strip elongation (bending).

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as a result of pivoting of the upper drive roller. Pivoting of the upper roller leads to a one-sided opening of the driver gap and thus to a shift in the point of application of the pressing force that the drive rollers exert on the belt. The point of application of the force, which in the case of a symmetrical driver gap is in the middle of the system, is now shifted by a distance from the middle of the system towards the side of the driver gap that is not open. As a result, the belt retraction force resulting from the braking torque of the drive device also acts on the belt, which was previously still running in the middle, at a distance from the middle of the system. This force introduction situation brought about by the pivoting/tilting of the upper drive roller results in a moment being exerted on the belt, which is still running in the middle, which causes the belt to bend elastically transversely. As a result of this belt deformation, the longitudinal belt fibers in the area of the drive device are oriented at an angle to the center axis of the system or at an angle to the drive roller axes. Thus, a belt that is guided frictionally over a drive roller tends to follow the trajectories of the roller shell points in the contact area. In this case, this means that the belt does not run through the drive device following the longitudinal direction of the belt fibers, but that the belt point currently in the contact area is transported in the direction of the roller circumferential speed vector at the contact point, i.e. in the direction of the longitudinal axis of the system. This results in a transverse displacement of the belt in the drive device. This displacement of the belt also causes a gradual increase in the distance between the force application point of the driver retraction force and the tension center at the belt run-on point on the coil. If the upper drive roller is tilted too far, however, the distance to the center of the system will be considerably greater than the transverse belt displacements that occur, so that the influence of the resulting change in the distance to the center of the system can be neglected.

The belt position control system known from the aforementioned German patent application DE 38 28 356 A1 essentially consists of a belt

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edge detection system, a belt position controller and a hydraulic adjustment of the upper drive roller with force and inclination control. The belt position is influenced by swiveling/tilting the upper drive roller in accordance with the mechanical principles described above. The control difference for the belt position controller is formed from the current position of the belt edge, which is detected by means of a belt edge scanner, and the position setpoint, which is determined from the belt width and the system dimensions. The output variable of the belt position controller is the setpoint of the drive roller inclination, which is specified for the drive roller adjustment. Since there is no contact between the rulers and the belt when the side guide rulers are open, both the usual wear of the rulers and damage to the belt edges caused by the side guide rulers are avoided.

Operational tests have shown that strip guidance through the drive device with open side guides is basically possible for hot-rolled strips up to a thickness of around 5 mm. However, the quality requirements for the winding state have not yet been fully met with this process. The contour of the coil end face showed limited but unacceptable residual waviness (fluctuation range approx. ± 10 mm). Winding offsets occur when threading out of the finishing stand. The following causes are crucial for these errors, i.e. for the lateral shearing of coil windings:

The influence on the run-out angle of the belt (angle between the belt center line and the drive roller axis) is essential for the function of the drive device as an actuator for belt position control. In the case of curved belts ("saber shape"), the angle caused by the curvature has the effect of a disturbance variable, i.e. the angle from the belt curvature is not taken into account when generating the control variable and distorts it to an initially unknown extent.

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Since the armature current of the drive roller drives is controlled by the higher-level drive control and can therefore also be limited, if the current limit is set too low, the resulting tension in the strip between the mandrel and the drive device means that the desired actuating effect by pivoting the upper drive roller to drive the strip into the target position cannot be achieved.

When the strip is unthreaded from the finishing stand, a sudden strain relief of the strip occurs, which can cause slipping in the driver gap and thus cause a winding offset in the coil.

Furthermore, the German patent DE 197 09 992 C1 describes a method for measuring the surface geometry of hot strip by generating lines on the strip surface using a light source. This method is intended to enable simple and effective detection of the strip flatness in order to use this for more sensitive control of rolling and coiling parameters. A line pattern is projected onto the measuring surface, the hot strip or the end face of a coil in the process of being produced, using a slide projector. This line pattern is recorded using a CCD camera (charge coupled device). The projector is arranged above the hot strip and projects the line pattern onto the surface of the hot strip at an angle to the vertical, so that the lines preferably extend transversely to the strip surface and thus cover the entire strip width.

The CCD camera records the lines running across the strip surface. With absolute strip flatness, a uniform pattern of straight lines with an unchanged line spacing is created. Deviations of the strip surface from the ideal plane cause a change in the line spacing in the area of the unevenness. The camera records this change and can be easily converted into height differences by comparing it with a reference pattern. In a similar way to

When measuring the flatness of a continuous strip, the measuring system can be used to monitor the flatness of the end faces during coiling. The end face of the coil being built up in the coiler corresponds to the strip surface. This measuring method enables rapid online determination of the actual height differences of the strip surface and thus allows real-time recording and control of continuous strip sections. This has the advantage that the measurement results allow the rolling and/or coiling parameters to be adjusted immediately after an unevenness occurs. Transverse curvature of the strip can also be determined in this way. Conventional measuring systems only record the strip fiber length. The measuring lines can also be adapted to different conditions in terms of their intensity and line thickness.

In summary, it can be concluded that when coiling rolled strip, lateral shearing of coil turns occurs as a result of transverse movements of the rolled strip being coiled, which leads to uneven front surfaces of the coil. During the further processing and conveying of such coils, the protruding strip edges are susceptible to damage. As a result of this damage, additional costs can arise during further processing or revenue losses. In addition, the conventional guidance of the rolled strip during coiling using lateral guide rails described at the beginning is associated with a relatively high maintenance effort, since the lateral guide rails are subject to increased abrasive wear due to the strip edges of the rolled strip that are to be guided.

The present invention is based on the task of creating a device for the correct positional winding of a hot strip in a coiling device, with which an optimization of the winding result of the rolled strip coil is achieved. First of all, lateral shearing of the individual coil turns of the rolled strip should be avoided during coiling and the wound coils should meet the DIN requirements as tightly wound, if possible.

as round and straight-edged as possible. The limit dimensions for a coil in the wound state are specified in DIN 1016.

This object is achieved with a device for the correct positional winding of a rolled hot strip in a coiling device, which determines the surface geometry of the rolled strip as a measurement variable and feeds it to the controller. With regard to the device for the correct positional winding of a hot strip in a coiling device, this object is achieved by arranging a measuring device for determining the surface geometry of the rolled strip in the area in front of the driving device, the measurement variable of which is fed to the controller. Advantageous embodiments of the method and device according to the invention are specified in subclaims 2 to 6 and 8 to 10.

The device according to the invention for the correct positional winding of a hot strip in a coiling device can be represented in a multi-variable strip position control system with feedforward control, which essentially consists of a measuring system for detecting the strip surface geometry and the strip edge position, a multi-variable controller for the strip tension and the strip position, a feedforward control that takes into account the influence of the surface geometry of the incoming strip, an observer for estimating the strip position on the coil and the strip tension between the driver and the mandrel, and a hydraulic adjustment of the upper drive roller via a force and inclination control.

Advantageously, the device for winding a hot strip in the correct position in a coiling device and its associated device can be retrofitted into existing systems by utilizing the existing actuators (adjustment of the drive rollers, drives of the driving device and mandrel) and the measuring device for determining the strip position and strip surface geometry.

It is particularly advantageous that the control variable for the strip tension of the driving device is dimensioned in such a way that the complete retraction by the driving device does not occur suddenly when the rolled strip is unthreaded from the last stand of the finishing train, but rather a continuously differentiable increase takes place until the tension is fully taken over before the end of the strip is unthreaded from the finishing stand. This successfully prevents winding offsets in the coil.

The main advantages of the device are that the strip surface geometry at the inlet to the coiling device is predictively taken into account by a feedforward control, the position of the strip on the coil is estimated by observers using verifiable physical models and the strip tension is optimized taking into account the incoming strip surface geometry and the current strip position.

The invention is explained in more detail below using an embodiment shown in the drawing. In the drawing:

Fig. 1 is a side view of an end section of a run-out roller table with subsequent driving and coiling device for a hot strip,

Fig. 2 a detailed view of the drive rollers of the drive device and

Fig. 3 is a block diagram of a control loop for a multi-variable control of the strip position of a hot strip in the area of a coiling device.

Figure 1 shows a schematic side view of an end section of a run-out roller table 1, which is connected on the input side to a finishing stand of a hot strip mill (not shown). On the run-out roller table

2, a finished hot-rolled strip 2 is fed towards a coiling device

3 with an upstream drive device 4. From the reel pre-

The hot strip 2 can be wound up into coils 5 in the direction of travel. The driving device 4 arranged at the end of the run-out roller table 1 essentially consists of a lower driving roller 6 and an upper driving roller 7. The upper driving roller 7 can be adjusted in the direction of the lower driving roller 6 and can be tilted sideways using hydraulic piston/cylinder units (not shown) for setting and adjusting the gap between the driving rollers 6 and 7. Figure 2, which shows a detailed view of the driving rollers 6 and 7 of the driving device 4, shows an inclined upper driving roller 7 and a wedge-shaped driving roller gap 17. The alignment of the incoming rolled strip 2 in the direction of the coiler device 3 exclusively by adjusting the inclination of the drive rollers 6 and 7 relative to one another, as well as the mechanical basis of the transverse displacement of the hot strip in the drive roller gap that can be brought about by this, has already been described in detail in the assessment of the German laid-open specification DE 38 28 356 A1 mentioned at the beginning, which hereby becomes part of the description. In addition to the strip run stabilization, the lower drive roller 6 is cambered.

The driving device 5 including its drives (not shown) has, in addition to the previously described task of guiding and aligning the incoming hot strip in the direction of the coiling device 3, the tasks of pulling the beginning of the hot strip 2 coming from the finishing train tight, guiding the incoming strip tip in the direction of the coiling device 3 and ensuring the retraction of the hot strip 2 against the coiling device 3 during the winding process.

The coiling device 3 essentially consists of a driven and expandable mandrel 8 for winding the rolled strip 2 as well as pressure rollers and guide shells (not shown) for guiding the rolled strip 2 during the winding process. To initiate the winding process, the tip of the hot strip 2 is deflected by the drive rollers 6 and 7 from the level of the run-out roller table 1 downwards to the winding mandrel 8. Then the pressure rollers and the guide shells of the coiling device 3 guide the

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The beginning of the strip is wound several times around the rotating mandrel, whereby the segments of the mandrel 8 are continuously spread until the rolled strip 2 is wound into firmly attached turns. The main functions of the coiling device 3 are to ensure the force-fitting connection between the beginning of the strip and the mandrel 8, to support the coil 5 created during winding and to apply a defined strip tension to the strip 2 during winding.

Furthermore, in the area of the end of the run-out roller table 1, side guide rulers 11 are provided which are arranged at the respective ends of the rollers 9 of the run-out roller table 1 and can be adjusted laterally to the edges 10 of the hot strip 2 in order to align the beginning of the hot strip 2 for running into the coiling device 3. The side guide rulers 11 are open during the coiling process.

Also in the area of the end of the run-out roller table 1, a measuring device 12 for determining the position of the edge of the rolled strip 2 and a further measuring device 13 for determining the surface geometry of the rolled strip 2, in particular for detecting any "saber shape" of the rolled strip 2, are arranged. The measuring devices 12 and 13 are preferably arranged in front of the side guide rulers 11 and after the cooling section (not shown) in the course of the run-out roller table 1. The measuring device 13 for determining the surface geometry of the rolled strip 2 has a projector 18 and a camera 19 and their function has already been explained in more detail at the beginning in connection with the assessment of the German patent DE 197 09 992 C1, which hereby becomes part of the description.

Figure 3 shows a block diagram of a control circuit for a multi-variable control of the strip position of a hot strip 2 in the area of a coiler device 3. It can be seen that the control variables for the drive roller setting (target drive roller inclination) and the drive roller drive (target strip tension torque)

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ment) using a multi-variable controller 14. The influence of the strip surface geometry, in particular the so-called "saber" shape, is compensated by a pre-control 15. For this pre-control 15, a fictitious transverse bending moment is determined from the result of the strip surface geometry measurement 13 and the strip tension, which is compensated by a corresponding inclination of the upper drive roller 6 in order to avoid lateral displacement of the rolled strip 2 due to the strip surface geometry.

The strip position on the coil, for the measurement of which no methods are known that can be implemented in rolling operations, and the strip tension between the driving device 5 and the mandrel 8 are estimated with the help of observers 16 (model-controlled determination of non-measurable variables from measured variables) and fed back to form the control differences. For this purpose, the strip edge position in front of the driver is determined using the measuring device 17.

The target strip edge position and the target strip tension are fed to the multi-variable controller 14 as reference variables. The reference variable for the strip tension of the driving device 5 is designed in such a way that the complete retraction takeover by the driving device 5 when the rolled strip 2 is unthreaded from the last stand of the finishing train does not occur abruptly, but rather there is a continuously differentiable increase until the tension is fully taken over, which begins even before the strip end is unthreaded.

For the model-based determination (observer 16) of the actual strip tension, the speed of the driver rollers (6, 7), the field current and the field voltage and the armature current and the armature voltage of the motors driving the driver rollers (6, 7), the contact pressure of the driver rollers and the bending moment of the strip around the driver rollers are preferably used.

For the model-based determination (observer 16) of the actual position of the strip edges, the strip tension, the driver roller inclination, the strip

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speed, strip position in front of the driver and surface geometry of the rolled strip.

The drive of the mandrel 8 is controlled by a speed control with a subordinate torque and current control. The specific belt data is specified to control the motor torque. This ensures that the belt tension is adapted to the belt cross-section and is constant over the length of the belt. The drives of the drive rollers 6 and 7 are controlled by a speed control with a subordinate current control. The hydraulic adjustment of the upper drive roller 7 is carried out by a force and inclination control.

Claims (10)

1. Device for the correct positional winding of a metal strip in a coiling device, in which the metal strip, in particular rolled hot strip, is fed to the coiling device via a driving device with driving rollers, the driving rollers can be inclined relative to one another via a controller by means of actuators for changing the driving roller gap, and the position of the edge of the metal strip in front of the driving device is fed to the controller as a measured variable and as a desired reference variable, characterized by a device for determining the surface geometry of the metal strip ( 2 ) and feeding it to a controller ( 14 ). 2. Device according to claim 1, characterized by a pilot control ( 15 ) for the determined surface geometry of the hot strip ( 2 ) which is connected downstream of the controller ( 14 ) and upstream of the control of the actuators of the drive rollers ( 6 , 7 ) for changing the drive roller gap ( 17 ). 3. Device according to claim 1 or 2, characterized in that the surface geometry of the hot strip ( 2 ) is determined locally before the hot strip ( 2 ) is fed to the driving device ( 4 ). 4. Device according to one of claims 1 to 3, characterized in that the controller designed as a multi-variable controller ( 14 ) is provided for the further reference variable of the desired strip tension between the drive rollers ( 6 , 7 ) and the reel device ( 3 ) and the controller ( 14 ) hereby controls the drive roller drive and the setting of the drive roller gap ( 17 ). 5. Device according to claim 4, characterized by a device which changes the desired strip tension in such a way that before the hot-rolled stock ( 2 ) is unthreaded from a finishing rolling stand upstream of the driving device ( 4 ), the retraction force of the driving rollers ( 6 , 7 ) for the metal strip ( 2 ) wound up by the coiling device ( 3 ) is continuously increased until the retraction force is fully taken over after the metal strip ( 2 ) has been unthreaded. 6. Device according to one of claims 1 to 5, characterized by a force and inclination regulator for the drive roller gap ( 17 ) of the drive rollers ( 6 , 7 ). 7. Device for the correct positional winding of a metal strip, in particular a rolled hot strip in a coiling device, in particular for carrying out a method according to claims 1 to 10, with a driving device feeding the hot strip to the coiling device with driving rollers that can be inclined towards one another, with actuators and a controller for this for changing the drive roller gap and the resulting influence on the lateral position of the hot strip and with a measuring device for determining the position of the edge of the hot strip in front of the driving device, the measured values of which are fed to the controller, characterized in that in the area in front of the driving device ( 4 ) a measuring device ( 13 ) for determining the surface geometry of the rolled strip ( 2 ) is arranged, the measured variable of which is fed to the controller ( 14 ). 8. Device according to claim 7, characterized in that the controller is designed as a multi-variable controller ( 14 ) to which the desired strip edge position and the desired strip tension are fed. 9. Device according to claim 7 or 8, characterized in that the controller ( 14 ) is linked to an observer module ( 16 ) via which the actual strip tension between the drive rollers ( 6 , 7 ) and the reel device ( 3 ) can be determined from measurable variables on the basis of a model. 10. Device according to one of claims 7 to 9, characterized in that the controller ( 14 ) is linked to an observer module ( 16 ) via which the actual position of the strip edges ( 9 ) of the strip ( 2 ) wound up by the reel device ( 3 ) can be determined from measurable variables on the basis of a model.