EP2519364B1 - Method of controlling the side guides of a metal strip - Google Patents

Description

The invention relates to a method for controlling side guides of a metal strip, in particular in rolling plants according to the preamble of claim 1 (see, for example, US Pat. DE 698 29 454 T ), for example in the inlet or outlet of rolling mills or before blowing apparatus or in other belt processing lines.

State of the art

Methods for controlling side guides of a metal strip are already known from the prior art. Such guides usually consist of two laterally arranged to the path of the tape rulers, which can be positioned with hydraulic cylinders and pressed or employed in the passage of a tape to the tape. Frequently, the known systems have a mechanical coupling of both rulers, as well as a common control for the adjustment on. Although such systems are relatively easy to conceptualize, but their adjustment options and in particular their control are very limited. Not all band progressions can be sufficiently corrected. Damage to the metal bands and rulers is not always to be avoided sufficiently.

Furthermore, methods are known in which a ruler is operated position-controlled while guiding a band, while the other ruler is pressed against the band with a defined force. The determination of the contact force between ruler and belt is carried out in this method for both sides. While guiding the tape, the ruler on one Position-controlled held on a fixed position. The other ruler is force-controlled with a defined force pressed against the belt. The nominal force of the force-controlled ruler is fixed depending on the characteristics of the belt to be led such as material, width, thickness, temperature or speed. This target force is chosen such that it is greater than the contact force of the band on the force-controlled side in any case, otherwise the guide could be opened on this side of the band. A disadvantage of this method is that when the band exerts a force on the position-controlled side, both this reaction force and, in addition, the predetermined force of the force-regulated side must be recorded on this side. Damage to the band and also to the rulers are the result. To repair the rulers, long plant downtimes are unavoidable. In addition, another disadvantage of this method results from the fact that the width of the tape to be fed is generally not constant. By specifying a fixed target force regardless of the width of the tape to be led the rulers can not be adjusted to different bandwidth gradients, so at best the leadership is deficient or such high forces between band and rulers that considerable damage occurs.

The publication DE 4003717 A1 discloses another method for side guidance of a rolled strip. The object of the disclosed method is to increase the service life of the guide rulers in a roller table. For this purpose, a regulation of the guide rulers is proposed, which operates in such a way that they can be pressed against the strip edges alternately and then lifted off from them again. A disadvantage of this method is, inter alia, that setpoints for a force control loop are predetermined by a process computer according to an input and thereby the control can not run sufficiently accurate in many cases. Due to the predetermined desired forces, this method also has the above-mentioned disadvantages, so that the rulers still wear unsatisfactorily fast by this method and also significant band edge damage can occur.

The technical task, which results from the prior art, is therefore to be seen to provide an improved control method for side guides of metal bands available or at least to avoid one of the above-mentioned disadvantages.

Disclosure of the invention

The invention is defined by the defined in claim 1 method for controlling a side guide of a metal strip, wherein the side guide on one side of the metal strip comprises a first and on the other side of the metal strip a second ruler, the rulers can be moved independently and each operated position-controlled and forces of the metal strip, which act on the first and on the second ruler, are measured and according to the invention, the target position for the first and / or the second ruler is controlled depending on the forces measured on the first and on the second ruler forces in that only the smaller value of the forces measured on the first and second ruler is above a selectable lower limit force and below a selectable upper limit force. The fact that both rulers are operated position-controlled independently of each other and that the forces measured at the rulers are used for the determination of the desired position as described, reduces damage to the rulers. Especially with stiff guides, the control of the invention proves to be extremely advantageous. The control according to the invention is also particularly advantageous when width variations of the band occur.

In a preferred embodiment of the method according to the invention, the upper limit force is greater than the lower limit force. Furthermore, this embodiment comprises the feature that when the smaller value of the forces measured on the first ruler and the second ruler falls below the lower limit force, the positions for the first and / or second ruler are adjusted such that the forces measured at the first and at the second ruler are increased. In addition, when the smaller value of the forces measured on the first ruler and the second ruler exceeds the upper limit force, the positions for the first and / or second ruler are adjusted so that those at the first and second rulers measured forces are lowered. If this is done in a controlled manner, the forces between the belt and the rulers are particularly effectively reduced, which reduces the wear on the rulers and prevents damage to the rulers even more effectively.

In a further preferred embodiment of the method according to the invention, the measured forces are filtered with a low-pass filter. Due to the low-pass filtering, the process can work reliably and insensitive. High frequencies, which are often due to interference, can be filtered out in this way.

In a further embodiment of the method according to the invention, the first and the second ruler are driven by a drive, wherein at least one of these drives is either hydraulically or pneumatically.

In a further embodiment of the method according to the invention, the hydraulic or pneumatic drives comprise two cylinder chambers, wherein the forces acting on the first or on the second ruler are determined from the pressures measured in the cylinder chambers.

In a further embodiment of the method according to the invention, the first and the second ruler are driven by a drive, wherein at least one of these drives is optionally effected by an electric linear motor.

In a further embodiment of the method according to the invention, the force acting on the first or the second ruler is determined from measured electrical variables of the linear motor.

In a further embodiment of the method according to the invention, the first and the second ruler are driven by a drive, wherein at least one of these drives via a rotary motor and a spindle gear and wherein the rotary motor is selectively driven hydraulically or pneumatically.

Brief description of the figures

The figures of the embodiments will be briefly described below. Further details can be found in the detailed description of the embodiments.

Figur 1

eine Schemaskizze einer Seitenführung eines Metallbandes samt Steuer- und Regeltechnik; und

Figur 2

ein Regelschema.

Show it:

FIG. 1

a schematic of a side guide of a metal strip together with control and regulation technology; and

FIG. 2

a rule scheme.

Detailed description of the embodiments

In FIG. 1 an example of an arrangement for carrying out the method according to the invention is shown. A metal strip 1, preferably a steel strip 1, is guided on its two sides, or longitudinal sides, by lateral guides. Such per se known side guides each comprise a ruler 2, 4. The metal strip 1 is contacted by the guide edges 9, 10 of the ruler 2, 4. The rulers 2, 4 are preferably made laterally to the belt 1 by drives or adjusting devices 3, 5. Optionally it is as in FIG. 1 shown possible, that between the leading edges 9, 10 and the drives or adjusting devices 3, 5 of the rulers 2, 4 force transducer 6 are provided. It is also possible that the rulers 2, 4, as shown, are made up of several parts. The adjusting devices 3, 5 may be formed, for example, by hydraulic or pneumatic cylinders, as shown. Moreover, according to FIG. 1 Position measuring sensor 7 is provided which can measure the travel of the piston in the adjusting devices 3, 5. Alternatively, it is also possible to provide other Positionmessaufnehmer 7, for example, so that they determine directly in contact with the rulers 2, 4, the position of the rulers. Also possible and advantageous are contactless position measurements, such as with the help of electromagnetic waves. Furthermore, in FIG. 1 Pressure measuring 8, or pressure transducer 8 shown that can measure 3.5 pressure values in a piston-cylinder unit. From these values, it is possible to deduce the forces K1, K2 which act on the rulers 2, 4 according to a known procedure. Alternatively, in the case of a drive with a motor 3, 5, in particular a rotary motor whose drive torque for determining a force on the rulers 2, 4 are used.

In FIG. 2 a control loop scheme is shown, which is intended to illustrate the inventive method purely by way of example. Left in the FIG. 2 a position control loop for the first ruler 2 is shown, to the right of a position control loop for the second ruler 4. By the position control loop of the first ruler 2, the ruler 2 is to be maintained at a desired position S1. However, a fault Z1 acts in the form of a pressure of the belt 1 on the controlled system RS 1 of the control loop, ie on the ruler 2. This fault results in a resulting position P1 of the first ruler, which can be determined by the measuring element MG. Such a measuring element can be, for example, the position measuring transducer 7. The measured value follows with the setpoint S1 the position of the ruler 2 compared. If there is a difference between the actual value of the position P1 and the desired value of the position S1, this difference is converted by a control element RG 1 into an information for the actuator SG 1. The actuator SG 1 is preferably made by one of the adjusting devices 3, 5 FIG. 1 educated. Alternatively, however, are also electric or rotary motors in question. Finally, the actuator SG 1 again influences the controlled system RS 1 or the ruler 2 and its position.

The position control loop of the ruler 4 or of the second ruler 4 operates analogously to the control loop just described. A disturbance Z2, or a pressure of the metal strip 1, acts on the controlled system RS 2 of the position of the ruler 4. Overall, the position P2 of the ruler 4 on. This position P2 can be measured by the measuring element MG 2. Subsequently, this measured position P2 is compared with a target position S2 of the ruler 4. An existing difference between these two values is transferred to the control element RG 2. This control element RG 2 is, as usual in control technology, a control value to the actuator SG 2, which thus has an influence on the controlled system RS 2, whereby the control circuit closes.

According to the invention, in addition to the position control on both sides of the metal strip 1 and the forces are measured, which act on the rulers 2, 4. This means, in particular, that a force K1 exists for each position P1 and that a force K2 also exists for each position P2. These forces K1, K2 are also in FIG. 2 are schematically indicated and are respectively measured by the measuring members MG 1 'and MG 2'. The measuring elements MG 1 ', MG 2' may preferably be formed by the load cells 6 or by the measuring sensors 8. In a next step of the method according to the invention, the forces K1 measured on the first ruler 2 are compared with the forces K2 measured on the second ruler 4, wherein the smaller of the two forces K1, K2, which is referred to below as the force K ', preferably passed to the controller or control devices R 1 and / or R 2 becomes. In the case that K1 is the lower force and thus corresponds to the force K ', this is passed to the controller 1, which outputs a modified setpoint S1 for the position of the first ruler 2. This value of the position of the first ruler S1 modified by the force measurement is then compared with the measured position value of the first ruler 2 when the control loop of the first ruler 2 is again passed through. In the case where K2 is the lower force of the forces K1 and K2, the force K2 or the force K 'is supplied to the regulator R 2. This controller R 2 in turn now outputs a new position setpoint S2 for the position of the second ruler 4. It is also possible for the value K 'to be transferred to both regulators R 1 and R 2 and for both regulators R 1 and R 2 to allocate new setpoint values S1 and S2 to the position control circuits in accordance with the measured force value K'. The setpoint values S1 and S2 are preferably output by the controllers R1 and R2 in such a way that the smaller of the measured forces K1, K2 or the contact forces K1, K2 lies between a predefinable lower limit or limit force and a predefinable upper limit or limit force. The lower limit is preferably chosen so that the friction of the system, or that of the belt 1, can be overcome and thus the control can always have an influence on the movement of the belt 1. The upper limit is preferably determined by plant parameters, such as the frictional forces occurring or may also depend on the desired measurement accuracy, depending on the system.

LIST OF REFERENCE NUMBERS

1

metal band

2

first ruler

3

first adjusting device

4

second ruler

5

second adjusting device

6

load cells

7

Positionsmessaufnehmer

8th

pressure transducers

9

first leading edge

10

second leading edge

K1

Power present on the first ruler

K2

Power present on the second ruler

K '

smaller of the measured forces K1, K2

MG 1

Position measuring device of the first ruler

MG 2

Position measuring device of the second ruler

MG 1 '

Force gauge of the first ruler

MG 2 '

Force gauge of the second ruler

P1

Position of the first ruler

P2

Position of the second ruler

R 1

Controller 1 for the output of the position setpoint S1 for the first ruler

R 2

Controller 2 for the output of the position setpoint S2 for the second ruler

RG 1

Control element of the position control loop of the first ruler

RG 2

Control element of the position control loop of the second ruler

RS 1

Controlled system of the position control loop of the first ruler

RS 2

Controlled system of the position control loop of the second ruler

S1

Setpoint for the position of the first ruler

S2

Setpoint for the position of the second ruler

SG 1

Actuator of the position control loop of the first ruler

SG 2

Actuator of the position control loop of the second ruler

Z1

Disturbance of the position control loop of the first ruler

Z2

Disturbance of the position control loop of the second ruler

Claims (8)

1. Method of regulating a lateral guide of a metal strip (1), particularly in the inlet or outlet of roll stands or in front of drive apparatus, wherein the lateral guide comprises a first guide (2) on one side of the metal strip (1) and a second guide (4) on the other side of the metal strip (1), wherein the guides (2, 4) can be moved independently of one another and each can be operated under positional regulation and wherein forces K1, K2), which act on the first guide (2) and on the second guide (4), of the metal strip (1) can be measured,
   characterised in that
   the target position (S1, S2) for the first and/or the second guide (2, 4) is so regulated in dependence on the forces (K1, K2) measured at the first and the second guide (2, 4) that the lower value (K') of the forces (K1, K2) respectively measured at the first guide (2) and at the second guide (4), which lower value is selected by comparison between these two measured forces (K1, K2), lies above a selectable lower limit force and below a selectable upper limit force.
2. Method according to claim 1, wherein the upper limit force is greater than the lower limit force and wherein if the lower value (K') of the forces (K1, K2) measured at the first guide (2) and at the second guide (4) falls below the lower limit force the positions for the first and/or second guide (2, 4) are so adjusted that the forces (K1, K2) measured at the first and the second guide (2, 4) are increased and if the lower value (K') of the forces (K1, K2) measured at the first guide (2) and at the second guide (4) exceeds the upper limit force the positions for the first and/or second guide (2, 4) are so adjusted that the forces (K1, K2) measured at the first and the second guide (2, 4) are decreased.
3. Method according to claim 1 or 2, wherein the measured forces (K1, K2) are filtered by a low-pass filter.
4. Method according to any one of the preceding claims, wherein the first and the second guides (2, 4) are driven by a drive (3, 5) and at least one of these drives (3, 5) is realised selectably hydraulically or pneumatically.
5. Method according to claim 4, wherein the hydraulic or pneumatic drives (3, 5) comprise a cylinder chamber and the forces (K1, K2) acting on the first or second guide (2, 4) are determined from the pressures measured in the cylinder chamber.
6. Method according to any one of claims 1 to 3, wherein the first and the second guides (2, 4) are driven by a drive (3, 5) and at least one of these drives (3, 5) is realised selectably by an electric linear motor.
7. Method according to claim 6, wherein the force acting on the first or second guide (2, 4) is determined from measured electrical variables of the linear motor.
8. Method according to any one of the preceding claims, wherein the first and the second guides (2, 4) are driven by a drive (3, 5) and wherein at least one of these drives is realised by way of a rotary motor and a spindle transmission, wherein the rotary motor is driven selectably hydraulically or pneumatically.

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