EP2519365B1 - Method of controlling 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 mills, for example in the inlet or outlet of rolling mills or before blowing apparatus or in other band processing lines, according to the preamble of claim 1 (see, eg, JP 2001 047 120 A ).

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.

Methods for controlling side guides of a metal strip are known, for example from the publications JP 2001 047120 A . JP 2 235519 A and US 4,590,778 ,

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 above technical problem is solved by the inventive method for controlling a side guide of a metal strip, in particular in the inlet or outlet of rolling mills or blowing machines, wherein the side guide on both sides of the metal strip in each case comprises a laterally arranged to the metal strip ruler and the rulers independently can be moved and a first of the rulers is operated position-controlled and a second of the rulers is operated force-controlled and forces of the metal strip, which act on the first ruler and on the second ruler are measured. According to the invention, moreover, the setpoint force for the second force-controlled ruler is predefined as a function of the measured force on the first position-controlled ruler, the setpoint force for the second, force-controlled ruler being reduced as the force on the first position-controlled ruler increases and / or the force decreases on the first, position-controlled ruler, the setpoint force for the second, force-controlled ruler is increased. The fact that both rulers are operated separately by a control loop, namely on the one hand by a position control loop and the other by a force control loop, the influence on the leadership is greatly improved. Since the predetermined forces prescribed for the second ruler are predetermined as a function of the forces measured on the first ruler and are not simply defined exclusively by material parameters or a user, the control of the system is significantly improved. Lower contact forces between the rulers and the belt result in less damage. Greater maintenance intervals and better belt quality result from the Features of the method according to the invention. In addition, the braking effect on the belt is reduced, so that the energy required for transporting the belt is reduced. What is also avoided is that the band presses the position-controlled side together with the effect of the force-regulated side. In particular, this also means that when width changes occur, the rulers can be better adapted to a widening or narrowing band, whereby the leadership of such bands is improved and damage is reduced.

In a preferred embodiment of the method, the setpoint force for the second force-controlled ruler is reduced to a predefinable, lower limit. By means of this predeterminable lower limit, it can be ensured, in particular, that the friction of the guide rule is overcome. If the desired force were chosen too low, the band could not be adjusted in any case despite employment of the ruler on the force-controlled side. By setting a lower force limit, the effectiveness of the scheme can thus be further improved.

In a further preferred embodiment of the method, the target power for the second, force-regulated ruler from the parameters a, b, c and d and = of the force acting on the first, position-controlled ruler force and actual force, with the equations F ₁ K ₁ - a and S2 = b - c · F ₁ determined, wherein the parameters a, b, c and d are greater than or equal to zero and the parameter b indicates the required maximum contact force of the second, force-controlled ruler and further S2 ≥ d and F ₁ ≥ 0, where F _{1 represents} an auxiliary quantity. By this choice of the desired force on the second ruler in dependence on the actual force on the side of the first, position-controlled ruler, a particularly advantageous control can take place.

In a further preferred embodiment of the method, the parameter a indicates a predeterminable minimum force on the first position-controlled ruler. Furthermore, the specifiable parameter c gives the ratio of the discharge of the second, force-controlled ruler with increasing force on the first, position-controlled ruler. The parameter d forms the lower limit force, which should not be undershot when reducing the setpoint force for the second, force-controlled ruler. By appropriate choice of these parameters, which depends on the actual application or the present system, the regulation can be further improved.

In a further preferred embodiment of the method, the forces measured on the first position-controlled ruler are filtered with a low-pass filter. Filtering with a low-pass filter filters out high frequencies, such as noise, which further improves or stabilizes the control. The regulation, and in particular the specification of the force setpoint of the second force-controlled ruler, is thus also less sensitive to short-term fluctuations in the measured actual forces on the position-controlled side.

In a further preferred embodiment of the method, the first and the second ruler are driven by a drive, wherein at least one of these drives is optionally formed hydraulically or pneumatically.

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

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

In a further preferred embodiment of the method, the force acting on the first or the second ruler is determined from measured electrical variables of the linear motor. By such a measurement or determination, the control can be simplified.

In a further preferred embodiment of the method, 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 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 side guides, which are known per se, each comprise a ruler 2, 4. The metal strip 1 can be 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 electromagnetic waves. Furthermore, in FIG. 1 Pressure measuring 8, or pressure transducer 8 shown that can measure pressure values in a piston-cylinder unit 3, 5. 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.

The FIG. 2 schematically shows an inventive embodiment of a control scheme for controlling the side guides or the rulers 2, 4. According to the invention, a first ruler 2 is operated position-controlled. The control circuit for regulating the ruler 2 is on the left side of FIG. 2 shown. Its controlled system RS 1, or its course, is disturbed by a fault Z1. Such a disturbance Z1 is, for example, a force of the metal strip 1 on the ruler 2. This disturbance results in a position of the ruler 2, for example the position P1. Such a position P1 of the ruler 2 can be determined by a position measuring device 7, which forms the measuring element MG 1 of the position control loop of the first ruler 2. Subsequently, will checked whether the measured value of the position of the first ruler 2 with a setpoint S1 for the position of the first ruler 2 matches. Subsequently, a control element RG 1 or a control device RG 1 is preferably provided, which outputs an amount of travel of the ruler 2 in a corrected position. By the actuator SG 1, for example by a piston-cylinder unit 3, then the control system RS 1 and thus the position of the ruler 2 can be influenced. Furthermore, a position value of the ruler 2, such as the value P1, always has a force K1 acting on the ruler 2. This can be measured by a measuring device or the measuring element MG 1 '. This can be formed for example by a measuring device 6 or 8. Preferably, the ruler 2 is held by the position control at a constant position. This means that in this case the target position S1 is constant.

The second ruler, ruler 4, is preferably operated with force control, that is to say by means of a force control loop, as in FIG FIG. 2 is shown on the right. By a pressure of the belt 1 against the ruler 4 a disturbance Z2 acts on the second ruler 4. By the action of the disturbance Z2 on the controlled system RS 2 and the adjusting force of the ruler 4 against the metal strip 1 exists a force K2, or total force K2 between the metal strip 1 and ruler 4. This force K2 can be determined by a measuring element MG 2. As a measuring element MG 2 are, inter alia, measuring devices of type 6 or 8 in question. Subsequently, the measured force K2 is compared with a setpoint force S2 and a possible difference passed on to the control element RG 2. By the control element RG 2 adjustment paths are passed to an actuator SG 2, which finally takes influence on the controlled system RS 2. The actuator SG 2 is also formed, for example, by a piston-cylinder unit 5 or by an electric or rotary motor.

The measured force values, which are determined by the measuring element MG 1 'on the side of the first position-controlled ruler 2, are preferably set by a controller R or a regulating device R to setpoint values for the forces S2 of the control loop of the second, force-controlled ruler 4 processed. In other words, this means that the desired forces S2 of the force control circuit of the second ruler 4, are selected in dependence on the forces K1 measured on the position control side. If, for example, a force K1 approaches the position-controlled ruler 2, this can be counteracted by reducing the setpoint force S2 on the force-controlled side. Conversely, if the force K1 decreases on the position-controlled side, the desired value for the setpoint force S2 on the force-controlled side is preferably increased. Furthermore, it is also possible that in this scheme further process parameters are included, such as the material of the tape or other its properties or various investment parameters. If, in addition, a lower limit is selected for the setpoint force S2 on the force-regulated side, then it can be ensured that the control can always overcome the friction of the band in particular. It is furthermore preferably possible for the forces K1 measured on the position-controlled side to be filtered with a low-pass filter. The choice of the setpoint force S2 for the second ruler 4 can furthermore be determined preferably via the equations F1 = K1-a and S2 = b-c * F1, where the parameters a, b, c and d are greater than or equal to zero and the parameter b indicates the technologically required maximum contact force of the second, force-controlled ruler 4 and where S2 ≥ d and F1 ≥ 0, where F1 represents an auxiliary variable. This calculation represents an advantageous example of the relationship between measured forces K1 on the position-controlled side and the setpoint forces S2 for the force-controlled side of the control. In particular, the parameters a, c, d can be chosen such that the parameter a is a predeterminable minimum force indicates on the first, position-controlled ruler 2 and the predetermined parameter c, the ratio of the relief of the second force-controlled ruler 4 with increasing force K1 on the first, position-controlled ruler 2 indicates and the parameter d represents the lower limit force, which in reducing the desired force S2 for the second, force-controlled ruler 4 should not fall below. It should be emphasized, however, that the choice of these parameters depends on the concrete technical problem and therefore can not be specified here. It is further stated that the previous description of the regulation on the equations mentioned is only an example of the realization of the regulation according to the invention and may not be understood as limiting.

LIST OF REFERENCE NUMBERS

1

metal band

2

first ruler

3

adjusting equipment

4

second ruler

5

adjusting equipment

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

MG 1

Position measuring device of the first ruler

MG 1 '

Force gauge of the first ruler

MG 2

Force gauge of the second ruler

P1

Position of the first ruler

R

Controller for the output of the setpoint of the force S2

RG 1

Control member of the first ruler

RG 2

Control member of the second ruler

RS 1

Controlled system of the first ruler

RS 2

Controlled system of the second ruler

S1

Setpoint for the position of the first ruler

S2

Target force of the second ruler

SG 1

Actuator of the first ruler

SG 2

Actuator of the second ruler

Z1

Disturbance of the position control loop of the first ruler

Z2

Disturbance of the power ruler of the second ruler

Claims (10)

1. Method of regulating a lateral guide of a metal strip (1), particularly in the entry to or exit from roll stands or in front of drive apparatus, wherein the lateral guide comprises a respective guide bar (2, 4) arranged laterally with respect to the metal strip (1) on each side of the metal strip (1), wherein the guide bars (2, 4) can be moved independently of one another and a first one of the guide bars (2) is operated with positional regulation and a second one of the guide bars (4) with force regulation and wherein forces of the metal strip (1) acting on the first guide bar (2) and the second guide bar (4) are measured, characterised in that the target force (S2) for the second, force-regulated guide bar (4) is predetermined in dependence on the measured force (K1) on the first, positionally regulated guide bar (2), wherein with increasing force (K1) on the first, positionally regulated guide bar (2) the target force (S2) for the second, force-regulated guide bar (4) is reduced and selectably with decreasing force (K1) on the first, positionally regulated guide bar (2) the target force (S2) for the second, force-regulated guide bar (4) is increased.
2. The method according to claim 1, wherein with increasing force (K1) on the first, positionally-regulated guide bar (2) the target force (S2) for the second, force-regulated guide bar (4) is reduced to a predeterminable lower limit.
3. The method according to claim 2, wherein the target force (S2) for the second, force-regulated guide bar (4) is determined from the parameters a, b, c and d and the measured force (K1) on the first, positionally regulated guide bar (2) by the equations: $${\mathrm{F}}_{\mathrm{1}}\mathrm{=}\mathrm{K}\mathrm{1}\mathrm{-}\mathrm{a}$$

   

   
   and $$\mathrm{S}\mathrm{2}\mathrm{=}\mathrm{b}\mathrm{-}\mathrm{c}\mathrm{\cdot }{\mathrm{F}}_{\mathrm{1}},$$

   

   
   wherein the parameters a, b, c and d are greater than or equal to zero and the parameter b indicates the required maximum pressing force of the second, force-regulated guide bar (4) and in addition S2 ≥ d as well as F₁ ≥ 0 and F₁ represents an auxiliary magnitude.
4. The method according to claim 3, wherein the parameter a indicates a predeterminable minimum force at the first, positionally regulated guide bar (2) and the predeterminable parameter c indicates the ratio of the load relief of the second, force-regulated guide bar (4) with increasing measured force (K1) on the first, positionally regulated guide bar (2) and the parameter d represents the lower limit force which is not to be fallen below when the target force (S2) for the second, force-regulated guide bar (4) is reduced.
5. The method according to any one of the preceding claims, wherein forces (K1) measured at the first, positionally regulated guide bar (2) are filtered by a low-pass filter.
6. The method according to any one of the preceding claims, wherein the first and second guide bars (2, 4) are each driven by a respective drive (3, 5) and at least one of these drives is selectably of hydraulic or pneumatic construction.
7. The method according to claim 6, wherein the hydraulic or pneumatic drives (3, 5) comprise a cylinder chamber and the forces (K1, K2) acting on the first or second guide bar (2, 4) are determined from the pressures measured in the cylinder chamber.
8. The method according to any one of claims 1 to 5, wherein the first and second guide bars (2, 4) are each driven by a respective drive (3, 5) and at least one of these drives is selectably formed by an electric linear motor.
9. The method according to claim 8, wherein the force (K1, K2) acting on the first or second guide bar (2, 4) is determined from measured electrical variables of the linear motor.
10. The method according to any one of claims 1 to 5, wherein the first and second guide bars (2, 4) are each driven by a respective drive (3, 5) and wherein at least one of these drives is effected by way of a rotary motor and a spindle drive, wherein the rotary motor is selectably hydraulically or pneumatically driven.

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