EP2926918B1 - Determination of web tension with modelling of web curvature - Google Patents

Description

• wobei zwischen den Fixorten eine Schlingenheberrolle eines Schlingenhebers an das Band angedrückt ist, so dass die Schlingenheberrolle das Band aus einer direkten Verbindungslinie zwischen den Fixorten auslenkt,
• wobei für eine Auslenkung des Bandes aus der direkten Verbindungslinie zwischen den Fixorten und ein auf die Schlingenheberrolle wirkendes Moment charakteristische Größen erfasst werden,
• wobei die charakteristischen Größen einer Steuereinrichtung zugeführt werden, von der anhand der Auslenkung und des Moments der Bandzug ermittelt wird,
• wobei das Moment von der Steuereinrichtung zur Ermittlung des Bandzuges um einen ersten Momentanteil, einen zweiten Momentanteil und einen dritten Momentanteil kompensiert wird,
• wobei der erste Momentanteil auf dem Gewicht des Bandes zwischen den Fixorten beruht, der zweite Momentanteil auf einem Eigengewicht des Schlingenhebers beruht und der dritte Momentanteil auf einer Biegung des Bandes zwischen den Fixorten beruht,
• wobei von der Steuereinrichtung anhand des um den ersten, den zweiten und den dritten Momentanteil kompensierten Moments der Bandzug ermittelt wird.

The present invention relates to a strip tension detecting method applied to a tape between a front fixing location and a back fixing location.

• wherein between the fixing locations a looper roll of a loop lifter is pressed against the band, so that the looper roll deflects the band from a direct connecting line between the fixing locations,
• wherein characteristic variables are detected for a deflection of the strip from the direct line of connection between the fixing locations and a moment acting on the loop-lifting roller,
• wherein the characteristic quantities are fed to a control device, from which the strip tension is determined on the basis of the deflection and the moment,
• wherein the torque is compensated by the control device for determining the strip tension by a first moment portion, a second moment portion and a third moment portion,
• wherein the first moment proportion is based on the weight of the band between the fixing locations, the second moment portion is based on an own weight of the loop lifter and the third moment portion is based on a bending of the band between the fixing locations,
• wherein the belt tension is determined by the control device on the basis of the torque compensated by the first, the second and the third torque portion.

The Oberbgriff of claim 1 is based on the technical article " Precise looper simulation for hot strip mills using an auto tuning approach "by Chi-Cheng Cheng et al., International Journal of Advanced Manufacturing Technology, Vol. 27, 2006, pp. 481-487 , (XP 19380521 A).

The present invention further relates to machine-readable program code for a control device for controlling a front and / or a rear holding element, each having a Fixort, between which a band is acted upon with a strip tension, wherein between the Fixorten a Schliegerheberrolle a loop lifter is pressed against the tape so that the looper roll out the tape deflecting a direct line of communication between the fix locations, the program code having control instructions the execution of which causes the controller to perform a detection method according to any of the above claims.

The present invention further relates to a software programmable control device for controlling a front and / or a rear retaining element, wherein the holding elements each have a Fixort, between which a band is acted upon by a strip tension, wherein between the Fixorten a Schliegerheberrolle a loop lifter is pressed against the tape ,

• wobei die Fördereinrichtung ein vorderes Halteelement und ein hinteres Halteelement aufweist, welche jeweils einen Fixort aufweisen, zwischen denen das Band mit einem Bandzug beaufschlagt ist,
• wobei die Fördereinrichtung einen zwischen den Halteelementen angeordneten Schlingenheber aufweist,
• wobei der Schlingenheber eine Schlingenheberrolle aufweist, die an das Band angedrückt ist, so dass die Schlingenheberrolle das Band aus einer direkten Verbindungslinie zwischen den Fixorten auslenkt,
• wobei Erfassungseinrichtungen vorhanden sind, mittels derer für eine Auslenkung des Bandes aus der direkten Verbindungslinie zwischen den Fixorten und ein auf die Schlingenheberrolle wirkendes Moment charakteristische Größen erfasst werden,
• wobei die Erfassungseinrichtungen zur Zuführung der erfassten charakteristischen Größen mit einer Steuereinrichtung verbunden sind.

The present invention further relates to a conveyor for conveying a belt,

• wherein the conveyor has a front holding element and a rear holding element, each having a Fixort, between which the tape is subjected to a strip tension,
• wherein the conveyor has a looper arranged between the holding elements,
• the loop lifter having a looper roll pressed against the band so that the looper roll deflects the band from a direct line of communication between the fixation locations,
• wherein detection means are provided by means of which characteristic variables are detected for a deflection of the strip from the direct line of connection between the fixing locations and a moment acting on the loop-removing roller,
• wherein the detection means for supplying the detected characteristic quantities are connected to a control device.

When rolling metal strip - especially when hot rolling of metal strip - looper rolls of loop lifters (Looper) are often arranged between each two stands of multi-stand rolling mills. By means of the Looper will be adjusted in cooperation with rolling speeds of each participating rolling stands, the strip tension between the rolling stands.

• der erste Momentanteil, der auf dem Gewicht des Bandes zwischen den Fixorten beruht,
• der zweite Momentanteil, der auf einem Eigengewicht des Schlingenhebers beruht,
• der dritte Momentanteil, der auf einer Biegung des Bandes zwischen den Fixorten beruht, und
• der vierte Momentanteil, der auf dem Bandzug beruht.

The looper rolls of the Looper have four momentary parts each, namely

• the first moment proportion based on the weight of the band between the fix locations,
• the second moment proportion, which is based on a dead weight of the looper,
• the third moment proportion based on a bend of the band between the fix locations, and
• the fourth moment proportion based on the strip tension.

In the technological sense, the strip tension should be adjusted. However, only the entire moment acting on the respective looper roller can be measured. It is therefore necessary to compensate for the detected torque by the first torque component, the second torque component and the third torque component. The more accurate this compensation is, the more accurately the actually desired strip tension can be determined and optionally also adjusted.

The determination of the first moment proportion, which is based on the weight of the band between the Fixorten, is readily possible. In particular, the mass of the strip is given by the cross section of the strip and, at least substantially, by the length of the connecting line between the fixing points. The thus caused first moment proportion can be determined in a simple manner on the basis of the mass of the band in conjunction with the readily known constructional geometric relationships of the loop lifter.

The determination of the second moment proportion, which is based on the weight of the loop lifter, is readily possible. In particular, the mass of the looper is readily determined in advance once. The resulting second moment proportion can be determined by the mass of the loop lifter be easily determined in conjunction with the readily known constructional geometric relationships of the loop lifter.

The problem is, however, the determination of the third moment proportion, which is based on a bending of the band between the Fixorten. For the determination of the third moment proportion, various approaches are known in the prior art.

From the technical paper " The Hot Strip Mill Looper System "by John C. Price, IEEE Transactions on Industry Applications, Vol. IA-9, Number 5, September / October 1973, pages 556-562 , It is known to neglect the third moment, that is, the proportion of moment which is based on a bending of the band between the Fixorten. This approach is consistent with the assumption that when hot rolling metal due to the temperatures prevailing there, the band will be bent by its own weight to a sufficient extent.

From the technical paper " Precise looper simulation for hot strip mills using an auto tuning approach "by Chi-Cheng Cheng et al., International Journal of Advanced Manufacturing Technology, Vol. 27, 2006, pp. 481-487 It is known to assume that the looper roll is located exactly in the middle between two stands and that the strip is articulated in the rolling stands. Furthermore, it is assumed in this article that the band bending is purely elastic and that the deflection is low. In this case, the bending force of the belt is calculated on the looper roll. It is proportional to the deflection and acts vertically downwards. It is converted into the third part of the moment in connection with the length and the angle of the looper arm, ie the moment proportion based on the bending of the band between the fix places.

In practice, there is still the approach to assume that the looper roll is located exactly in the middle between two rolling stands and that a plastic band bending he follows. In this case, the bending force of the belt is calculated on the looper roll. The bending force is constant, so does not depend on the deflection, and acts vertically downwards. It is converted into the third part of the moment in connection with the length and the angle of the looper arm, ie the moment proportion based on the bending of the band between the fix places.

The object of the present invention is to provide possibilities by means of which an exact determination of the strip tension prevailing in the strip is possible.

The object is achieved by a preliminary investigation with the features of claim 1. Advantageous embodiments of the determination method according to the invention are the subject of the dependent claims 2 to 5.

• dass von der Steuereinrichtung eine vordere Bandkurve des Bandes zwischen der Schlingenheberrolle und dem vorderen Fixort und eine hintere Bandkurve des Bandes zwischen der Schlingenheberrolle und dem hinteren Fixort ermittelt werden,
• dass die vordere Bandkurve von der Steuereinrichtung derart ermittelt wird, dass ein vorderer Biegemomentverlauf im Band, ausgehend von einem Maximalwert an der Schlingenheberrolle, in Richtung der Verbindungslinie gesehen auf den vorderen Fixort zu linear auf einen vorderen Minimalwert abfällt,
• dass die hintere Bandkurve von der Steuereinrichtung derart ermittelt wird, dass ein hinterer Biegemomentverlauf im Band, ausgehend von dem Maximalwert an der Schlingenheberrolle, in Richtung der Verbindungslinie gesehen auf den hinteren Fixort zu linear auf einen hinteren Minimalwert abfällt,
• dass der vordere Biegemomentverlauf und ein durch die vordere Bandkurve gegebener vorderer Krümmungsverlauf sowie der hintere Biegemomentverlauf und ein durch die hintere Bandkurve gegebener hinterer Krümmungsverlauf gemäß einer Biegekennlinie des Bandes miteinander verknüpft sind,
• dass die Biegekennlinie für Krümmungen der Bandkurven unterhalb einer Grenzkrümmung einen linearen Anstieg des jeweils korrespondierenden Biegemomentes auf ein erstes Grenzbiegemoment aufweist und
• dass die Biegekennlinie für Krümmungen der Bandkurven oberhalb der Grenzkrümmung zu einem zweiten Grenzbiegemoment hin abflacht.

According to the invention, a preliminary method of the type mentioned above is configured by

• in that a front band curve of the band between the looper roll and the front fixing location and a rear band curve of the band between the loop lifter roll and the rear fixing location are determined by the control device,
• the front band curve is determined by the control device in such a way that a front bending moment profile in the band, starting from a maximum value at the slinger pulley, falls linearly to a front minimum value as seen in the direction of the connecting line towards the front fixing location,
• the rear band curve is determined by the control device in such a way that a rear bending moment profile in the band, starting from the maximum value at the slinger pulley, falls linearly to a rear minimum value as seen in the direction of the connecting line towards the rear fixing location,
• that the front bending moment course and a given by the front band curve front curvature course and the rear bending moment course and a back curve given by the rear band curve are linked together according to a bending characteristic of the band,
• that the bending characteristic for curves of the band curves below a limit curvature has a linear increase of the respective corresponding bending moment to a first limit bending moment, and
• that the bending characteristic for curvatures of the band curves above the limit curvature flattens off to a second limit bending moment.

By means of these measures, a very realistic modeling of the actual behavior of the band between the two fixing locations and, correspondingly, a highly accurate determination of the third torque component can be achieved. In conjunction with the - as such known - accurate determination of the first torque component and the second torque component can thus also a highly accurate determination of the fourth torque component, ie based on the tape tension torque proportion can be achieved.

The bending characteristic is preferably determined by the control device as a function of the geometry properties of the strip between the fixing locations and the instantaneous material properties of the strip. The geometry properties may include in particular the band thickness and possibly also the bandwidth. In particular, the instantaneous material properties may include a current temperature of the belt, a momentary modulus of elasticity, and a momentary yield stress. If the strip is subjected to a phase transformation, for example in the case of a steel strip, a phase transformation of austenite into ferrite and / or cementite, phase components may also be taken into account in addition to the temperature of the strip. By determining the bending characteristic, it is achieved that the bending characteristic curve used in the course of determining the curvature profiles can be adapted to the actual conditions at any time.

It is preferably provided that a location of the looper roll is determined by the control device on the basis of the deflection of the strip from the direct connection line between the fixing locations in the direction of the direct connection line and / or that the location of the looper roll is viewed in the direction of the direct connecting line from the two fixing locations is not equidistant and that the location of the looper roller in the direction of the connecting line as viewed by the control device in the context of the determination of the third torque component is taken into account. This ensures that the modeling can be adapted at any time to the actual given geometric conditions. This approach is in particular in contrast to the prior art, in which at least as a rule it is assumed in the context of determining the third moment proportion that the looper roll is located in the middle between the two rolling stands.

It is preferably provided that the control unit is given a proportion to which the band is articulated in the front fixing location, and / or that the control unit determines this portion as a function of the geometry properties and instantaneous material properties of the band and that the control unit determines this proportion during the determination of the third moment proportion. This ensures that actual conditions at the front Fixort can be considered correctly.

In an analogous manner, it is preferably provided that the control unit is given a proportion to which the band is articulated in the rear fixation location, and / or that the control unit determines this proportion as a function of geometry properties and instantaneous material properties of the band and that the control unit determines this proportion considered in the determination of the third moment proportion. This ensures that actual conditions can be correctly considered at the rear Fixort.

The object is further achieved by machine-readable program code with the features of claim 6. According to the invention, the execution of the control commands causes the control device to carry out a determination method according to the invention. The program code may be stored on a storage medium according to claim 7.

The object is further achieved by a software programmable control device having the features of claim 8. According to the invention a control device of the type mentioned is configured in that the control device is programmed with a program code according to the invention.

The object is further achieved by a conveyor for conveying a belt having the features of claim 9. According to the invention, the control device is formed according to the invention in a conveyor of the type mentioned.

FIG 1

eine Fördereinrichtung zum Fördern eines Bandes,

FIG 2

ein Ablaufdiagramm,

FIG 3

ein weiteres Ablaufdiagramm,

FIG 4

eine Biegekennlinie,

FIG 5

Bandkurven,

FIG 6

Biegemomentverläufe,

FIG 7

eine Fördereinrichtung zum Fördern eines Bandes,

FIG 8

zugehörige Biegemomentverläufe,

FIG 9

zugehörige Bandkurven,

FIG 10

eine Fördereinrichtung zum Fördern eines Bandes,

FIG 11

zugehörige Biegemomentverläufe,

FIG 12

zugehörige Bandkurven,

FIG 13

Biegemomentverläufe,

FIG 14

eine Fördereinrichtung zum Fördern eines Bandes,

FIG 15

eine Schlingenheberrolle und ein Band,

FIG 16

geometrisch-konstruktive Verhältnisse der Fördereinrichtung von FIG 14 und

FIG 17

ein Ablaufdiagramm.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which will be described in more detail in conjunction with the drawings. Here are shown in a schematic representation:

FIG. 1

a conveyor for conveying a belt,

FIG. 2

a flow chart,

FIG. 3

another flowchart,

FIG. 4

a bending characteristic,

FIG. 5

Belt curves

FIG. 6

Bending moment diagrams,

FIG. 7

a conveyor for conveying a belt,

FIG. 8

associated bending moment curves,

FIG. 9

associated band curves,

FIG. 10

a conveyor for conveying a belt,

FIG. 11

associated bending moment curves,

FIG. 12

associated band curves,

FIG. 13

Bending moment diagrams,

FIG. 14

a conveyor for conveying a belt,

FIG. 15

a looper roll and a band,

FIG. 16

geometric-constructive conditions of the conveyor of FIG. 14 and

FIG. 17

a flowchart.

According to FIG. 1 For example, a conveyor for conveying a belt 1 has a front holding element 2 and a rear holding element 3. As shown in FIG. 1 both holding elements 2, 3 are designed as rolling stands. Alternatively, one of the two holding elements 2, 3 could be designed differently, for example as a drive roller set. The band 1 is usually a metal band, for example a steel band or an aluminum band.

The two holding elements 2, 3 each have a fixing point 4, 5. Between the two fixed locations 4, 5, the band 1 is subjected to a strip tension Z. In the case of the embodiment of the two holding elements 2, 3 as rolling mills, the fixed locations 4, 5 correspond to the roll nips of the rolling mills. If one of the holding elements 2, 3 is designed as a drive roller set, the point at which the belt 1 runs out of the drive roller set or enters the drive roller set corresponds to the respective fix location 4 or 5. In both cases, the respective fix location 4 resp 5 constant.

The conveyor device furthermore has a loop lifter 6, which is arranged between the holding elements 2, 3. The loop lifter 6 has a loop lifter roller 7. The loop lifter roller 7 is pressed by means of an adjusting device 8 of the loop lifter 6 to the belt 1. As a result, the loop lifter roller 7 deflects the band 1 from a direct connecting line 9 between the fixed locations 4, 5. The adjusting device 8, for example, as shown in FIG FIG. 1 be designed as a hydraulic cylinder unit.

Furthermore, detection devices 10 are present. By means of the detection devices 10, variables are detected which are characteristic of a deflection hL of the strip 1 from the direct connecting line 9 between the fixing locations 4, 5 and a moment M acting on the loop lifter roller 7. For example, a travel s of the adjusting device 8 can be detected, from which in conjunction with the known geometrical-constructional conditions of the loop lifter 6, the deflection hL of the band 1 can be determined. Furthermore, for example, working pressures p1, p2 can be detected, from which, in conjunction with the known sizes of working surfaces of the piston of the hydraulic cylinder unit, the force exerted by the adjusting device 8 is determined. Based on the force exerted by the adjusting device 8, the moment M can then be determined in conjunction with the known geometrical-constructional conditions of the loop lifter 6. The corresponding facts are generally known to experts and therefore do not need to be explained in detail. Alternatively, under some circumstances it may be possible to detect the deflection hL and / or the moment M directly.

The detection devices 10 are connected to a control device 11 for supplying the detected deflection hL and the detected torque M (or the corresponding characteristic variables s, p1, p2). The deflection hL and the moment M or the characteristic variables s, p1, p2 are thus supplied to the control device 11.

The control device 11 serves to control the front and / or the rear holding element 2, 3. The control device 11 is designed as a software programmable control device. It is programmed with machine-readable program code 12. The machine-readable program code 12 may be stored on a storage medium 13, for example. The storage medium 13 can in principle be configured as desired. The representation in FIG. 1 , according to which the storage medium 13 is shown as a USB memory stick is purely exemplary.

The machine-readable program code 12 has control commands 14. The execution of the control commands 14 causes the controller 11 to perform a determination procedure for the strip tension Z, which will be described below in connection with FIG FIG. 2 is explained in more detail.

According to FIG. 2 takes the control device 11 in a step S1, the characteristic quantities s, p1, p2 against. On the basis of the accepted characteristic quantities s, p1, p2, the control device 11 determines the deflection hL and the moment M. in a step S2.

In a step S3, the control device 11 determines a first momentary proportion M1. The first moment proportion M1 is based on the weight G1 of the band 1 between the fix locations 4, 5. Procedures for implementing the step S3 are well known to those skilled in the art and therefore need not be discussed in detail. At this point, it should merely be pointed out that the geometrical-constructional conditions of the loop lifter 6 are taken into account in the implementation of step S3.

In an analogous manner, the control device 11 determines a second torque component M2 in a step S4. The second instant M2 is based on the net weight G2 of the looper 6. Procedures for implementing step S4 are also well known to those skilled in the art and therefore need not be discussed in detail. Analogous to step S3, the geometric-constructional circumstances of the loop lifter 6 are included in the implementation of step S4.

In a step S5, the control device 11 determines a third torque component M3. The third moment proportion M3 is based on a bending of the strip 1 between the fixing locations 4, 5. The step S5 corresponds to the actual core object of the present invention. It will be explained in more detail later.

In a step S6, the moment M is compensated for by the control device 11 by the first momentary component M1, the second momentary component M2 and the third torque component M3. The control device 11 thereby determines a fourth torque component M4. The fourth moment component M4 is based on the strip tension Z prevailing in band 1.

In a step S7, the control device 11 determines the strip tension Z based on the fourth moment proportion M4. In the context of step S7, the control device 11 - analogous to the steps S3 and S4 - takes into account the geometric-constructional conditions of the loop lifter 6.

As a rule, a step S8 continues to exist. Within the scope of step S8, the control device 11 uses the strip tension Z and a reference pull Z * to determine a manipulated variable δv1 for the front holding element 2 and / or a manipulated variable δv2 for the rear holding element 3 and / or a manipulated variable Q for the setting device 8 Step S8, the controller 11 returns to step S1. If step S8 should not be present, the controller 11 returns to step S1 from step S7. The sequence of steps S1 to S8 (S7) is thus executed iteratively. The latter is in FIG. 2 indicated by dashed lines. A clock cycle is usually between 1 ms and 10 ms, usually between 2 ms and 5 ms. For example, it can be 2.5 ms to 3.0 ms.

FIG. 3 shows a possible implementation of step S5. According to FIG. 3 For example, in step S11 the control device 11 becomes aware of a bending characteristic. The bending characteristic provides the relationship between the curvature K of the strip 1 at a certain point and a bending moment MB acting at this point. FIG. 4 shows a typical bending characteristic. According to FIG. 4 has the bending characteristic curve for curvatures K below a limit curvature KEL a linear increase of each corresponding bending moment MB on a first boundary bending moment MEL on. For curvatures K above the limit curvature KEL the bending characteristic flattens off. The increase is therefore lower than in the linear range. The increase is due to a second limit bending moment. The second limit bending moment corresponds to FIG. 4 1.5 times the first limit bending moment MEL. The factor is not necessarily given. There could be another value. The bending characteristic is point symmetrical to the zero point of the bending characteristic.

$$\mathit{MEL}=\frac{\mathit{\sigma F}\cdot b\cdot h^2}{6}$$

$$\mathit{MB}=\mathit{MEL}\left(\frac{3}{2}-\frac{{\mathit{KEL}}^2}{2K^2}\right)=\frac{\mathit{\sigma F}\cdot b\cdot h^2}{12}\left(3-\frac{{\mathit{KEL}}^2}{K^2}\right)$$

It is possible that the bending characteristic of the control device 11 is predetermined once - for example, in the context of the programming of the control device 11 - and then fixed and fixed fixed. Alternatively, it is possible that the bending characteristic of the control device 11 from the outside - for example, by a user (not shown) - is specified. Preferably, however, the controller 11 geometry properties of the belt 1 between the fixed locations 4, 5 and current material properties of the belt 1 are known. In this case, the control device 11 can determine the bending characteristic as a function of the geometry properties of the strip 1 between the fixing locations 4, 5 and the instantaneous material properties of the strip 1. In particular, for example, the bending characteristic of the control device 11 can be parameterized as follows: $$\mathit{KEL}=\frac{2\mathit{\sigma F}}{\mathit{Eh}}$$

$$\mathit{MEL}=\frac{\mathit{\sigma F}\cdot b\cdot {\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="imgf0001.png,imgf0004.png"\; state="\{\{state\}\}">H</figure-callout>}}^2}{6}$$

$$\mathit{MB}=\mathit{<figure-callout\; id="3"\; label="MEL"\; filenames="imgf0001.png,imgf0004.png"\; state="\{\{state\}\}">MEL</figure-callout>}\left(\frac{3}{2}-\frac{{\mathit{<figure-callout\; id="2"\; label="KEL"\; filenames="imgf0001.png,imgf0004.png"\; state="\{\{state\}\}">KEL</figure-callout>}}^2}{2{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="imgf0001.png,imgf0004.png"\; state="\{\{state\}\}">K</figure-callout>}}^2}\right)=\frac{\mathit{\sigma F}\cdot b\cdot {\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="imgf0001.png,imgf0004.png"\; state="\{\{state\}\}">H</figure-callout>}}^2}{12}\left(3-\frac{{\mathit{KEL}}^2}{{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="imgf0001.png,imgf0004.png"\; state="\{\{state\}\}">K</figure-callout>}}^2}\right)$$

In the above formulas, σF is the yield point of tape 1, E is Young's modulus of tape 1, h is the thickness of tape 1, and b is the width of tape 1. The yield strength σF and modulus of elasticity E of Bandes 1 are instantaneous material properties of the band 1, which comprises the band 1, while it is between the two holding elements 2, 3 or between the two fixed locations 4, 5. The current material properties can be specified directly to the control device 11. Alternatively, it is possible that they are the control device 11 indirectly - for example, specified by specifying chemical composition, temperature, possibly phase fractions, microstructure and the like.

Regardless of the specific nature of the specification of the bending characteristic, however, it is possible for step S11 to be carried out in advance, ie outside the loop consisting of steps S1 to S8 or S1 to S7.

Using the bending characteristic, the controller 11 determines a front band curve KA of the band 1 in a step S12. The front band curve KA extends according to FIG. 5 between the looper roller 7 and the front Fixort 4. The determination is made such that a front bending moment curve BA in the band 1 according to FIG. 6 on the looper pulley 7 has a maximum value ML and, starting from the location of the looper pulley 7 and the maximum value ML in the direction of the connecting line 9, falls to the front fixing point 4 linearly to a front minimum value MV.

In an analogous manner, the control device 11 determines a rear band curve KB of the band 1 in a step S13. The rear band curve KB extends according to FIG. 5 between the loop lifter roller 7 and the rear Fixort 5. The determination is made such that a rear bending moment curve BB in the band 1 according to FIG. 6 on the looper pulley 7 has the maximum value ML - ie the same maximum value ML - and, starting from the location of the looper pulley 7 and the maximum value ML in the direction of the connecting line 9, falls to the rear fixing point 5 linearly to a rear minimum value MH.

The front bending moment curve BA and a front curve course given by the front band curve KA are linked to one another according to the bending characteristic. Analogously, the rear bending moment curve BB and a given by the rear band curve KB back curve curve according to the bending characteristic are linked together. This will be described below in connection with the FIGS. 7 to 16 explained in more detail. FIGS. 7 to 9 and FIGS. 10 to 12 show two special cases, FIG. 13 one on the FIGS. 7 to 12 constructive generalization and the FIGS. 14 to 16 after that the general case, in turn to the two in conjunction with FIGS. 7 to 12 described special cases and the generalization of FIG. 13 is used.

benötigt, die aufgrund der Biegung des Bandes 1 auf die Schlingenheberrolle 7 ausgeübt wird.In the context of FIG. 7 It is assumed that the loop lifter roller 7 is arranged in the direction of the connecting line 9 exactly in the middle between the two fixing locations 4, 5. With LA and LB, the distances of the loop lifter roller 7 of the two fixed locations 4, 5 are designated. Due to the central arrangement of the looper roller 7 LA = LB. With FLA and FLB holding forces are designated, by means of which the band 1 is acted upon at the fixed locations 4, 5 seen orthogonal to the connecting line 9. The holding forces FLA, FLB cause in particular that the band 1 does not lift off at the fixed locations 4, 5. Furthermore, it is assumed that the band 1 is articulated in the fixed points 4, 5. The holding forces FLA, FLB need not be known as such, but they are used in the following calculations to derive a force $$\mathit{FL}=\mathit{FLA}+\mathit{FLB}=\frac{\mathit{ML}}{\mathit{LA}}+\frac{\mathit{ML}}{\mathit{LB}}$$

required, which is exerted due to the bending of the belt 1 on the loop pulley roller 7.

Under the assumptions mentioned, the minimum values MH, MV are zero. FIG. 8 shows the associated front and rear bending moment curves BA, BB, FIG. 9 the associated front and rear band curves KA, KB.

The band curves KA, KB for a given deflection hL can not be calculated easily closed. In order to come to a solution, therefore, the inverse approach is taken. Thus, the associated maximum value ML is not determined for a given deflection hL, but conversely, for a given maximum value ML, the associated deflection hL is determined. This will be explained below for the front band curve KA. Analogous versions apply to the rear band curve KB.

Given the maximum value ML and the given distance LA from the front fixing point 4, the associated value of the bending moment MB can be determined without further ado for each location x along the connecting line 9: $$\mathit{MB}\left(x\right)=\mathit{ML}\left(1-\frac{x}{\mathit{LA}}\right)$$

The zero point of the coordinate system is in this case at the loop lifter roller. 7

die zugehörige vordere Bahnkurve KA, welche das Band 1 annimmt, ermittelt werden. Der gesamte Weg, den das Band 1 orthogonal zur Verbindungslinie 9 zurücklegt, entspricht der Auslenkung hL. Die vordere Bandkurve KA und der korrespondierende Krümmungsverlauf sind somit 1:1 ineinander umrechenbar.Based on the respective bending moment MB, the associated curvature K (x) can thus be determined in a simple manner for each location x along the connecting line 9 on the basis of the given bending characteristic. However, given the curvature K (x), according to the known differential equation $$K\left(x\right)=\frac{\frac{d^{2}y}{d{x}^2}}{{\left[1+{\left(\frac{d}{dx}\right)}^2\right]}^{{}^3{/}_2}}$$

the associated front trajectory KA, which assumes the band 1, are determined. The entire path traveled by the band 1 orthogonal to the connecting line 9, corresponds to the Deflection hL. The front band curve KA and the corresponding curvature are thus 1: 1 convertible into each other.

Thus, for each of the several maximum values ML, the associated deflection hL can be determined. The totality of these pairs of values can be stored in the control device 11 as a table or as a parameterized function (for example as an n-th degree polynomial with n = 4, 5, 6,...), So that the associated one is readily associated with any displacements hL Maximum value ML can be determined.

It is therefore possible for the configuration according to FIG. 7 for each deflection hL in each case to determine the force exerted on the loop lifter roller 7 FL. Due to the fact that both the magnitude of the force FL and its direction are known, can thus in conjunction with the known geometrical-constructional conditions of the loop lifter 6 in the embodiment according to FIG FIG. 7 the third moment M3 be determined.

The design of FIG. 10 corresponds essentially to that of FIG. 7 , The difference to the design of FIG. 7 is that in the context of FIG. 10 it is assumed that the band 1 is clamped in the fixed points 4, 5. The tape 1 thus runs at the front Fixort 4 parallel to the connecting line 9 from the front Fixort 4 from. In an analogous manner, the band 1 runs at the rear Fixort 5 parallel to the connecting line 9 in the rear Fixort 5 a. In this case, the minimum values MH, MV are equal in magnitude to the maximum value ML, but have a negative sign. FIG. 11 shows the associated front and rear bending moment curves BA, BB, FIG. 12 the associated front and rear band curves KA, KB.

Also in the embodiment according to FIG. 10 For example, the band curves KA, KB can not be easily calculated for a given deflection hL. To come to a solution is therefore as before FIG. 7 the inverse approach. This will be explained below for the front band curve KA. For the rear band curve KB apply analogous versions as before.

Given the maximum value ML and given distance LA from the front fixing point 4, the associated value of the bending moment MB can be determined without further ado for each location x along the connecting line 9: $$\mathit{MB}\left(x\right)=\mathit{ML}\left(1-\frac{2x}{\mathit{LA}}\right)$$

The zero point of the coordinate system is in this case as in the case of the looper roll 7.

Based on the respective bending moment MB, the associated curvature K (x) can thus be determined in a simple manner for each location x along the connecting line 9 on the basis of the given bending characteristic. However, given the curvature, according to the known differential equation - see Equation 6 above - the associated line assuming the band 1 can be determined. The entire path traveled by the band 1 orthogonal to the connecting line 9 corresponds to the deflection hL. Due to considerations of symmetry, it is still sufficient, starting from the location of the looper pulley 7 to the center between the looper roller 7 and the front Fixort 4 to be expected. The remaining section can be determined by point mirroring.

The holding forces FLA, FLB are needed as before to derive the force FL. Effective lever arms hA, hB are in the embodiment according to FIG. 10 but only half as long as in the embodiment according to FIG. 7 , So it applies $$\mathit{FL}=\mathit{FLA}+\mathit{FLB}=\frac{\mathit{ML}}{\mathit{LA}/2}+\frac{\mathit{ML}}{\mathit{LB}/2}$$

As previously in the embodiment according to FIG. 7 can therefore also in the embodiment according to FIG. 10 for several maximum values ML, the respective displacements hL are determined in each case. The totality of these pairs of values can be stored in the control device 11 as a table or as a parameterized function (for example as an n-th degree polynomial with n = 4, 5, 6,...), So that the associated one is readily associated with any displacements hL Maximum value ML can be determined.

It is therefore possible for the configuration according to FIG. 10 for each deflection hL in each case to determine the force exerted on the loop lifter roller 7 FL. Due to the fact that both the magnitude of the force FL and its direction are known, can thus in connection with the known geometrical-constructional conditions of the loop lifter 6 also in the embodiment according to FIG FIG. 10 the third moment M3 be determined.

In an analogous manner, it is possible in a symmetrical arrangement of the loop lifter roller 7 in the middle between the two fixed points 4, 5 for a given maximum value ML respectively determine the associated deflection hL when the band 1 neither (compare FIG. 7 ) in the fixed points 4, 5 is still articulated (see FIG. 10 ) is firmly clamped in the fixed points 4, 5. This will be described below in connection with FIG. 13 explained in more detail.

In FIG. 13 are denoted by aA, aB shares, to which the band 1 is articulated in the fixed points 4, 5. If the proportion aA has the value one, this means that the band 1 is fully articulated in the front fixed point 4. If the proportion aA has the value zero, this means that the band 1 is completely clamped in the front fixed point 4. Analogous explanations apply with respect to the portion aB and the rear fixed point 5.

$$\mathit{MH}=-\mathit{ML}\cdot \left(1-\mathit{aB}\right)$$

Assuming that the components aA, aB are the same, the minimum values MH, MV result $$\mathit{MV}=-\mathit{ML}\cdot \left(1-\mathit{aA}\right)$$

$$\mathit{MH}=-\mathit{ML}\cdot \left(1-\mathit{from}\right)$$

$$\mathit{hB}=\frac{\mathit{LB}}{2-\mathit{aB}}$$

Furthermore, the effective lever arms hA, hB result from the zero points of the bending moment curves BA, BB and thus too $$\mathit{Ha}=\frac{\mathit{LA}}{2-\mathit{aA}}$$

$$\mathit{hB}=\frac{\mathit{LB}}{2-\mathit{from}}$$

The force FL is due to $$\mathit{FL}=\frac{\mathit{ML}}{\mathit{LA}/\left(2-\mathit{from}\right)}+\frac{\mathit{ML}}{\mathit{LB}/\left(2-\mathit{from}\right)}$$

The force FL also acts in this case vertically to the connecting line 9. On the basis of the force FL can therefore be determined in this case in connection with the known geometrical-constructional conditions of the loop lifter 6 in the embodiment of the third moment component M3.

Subsequently, the general case will be considered. In the general case is according to FIG. 14 the looper roll 7 is not necessarily located centrally between the fixing locations 4, 5. Although this is possible, it is not necessarily required, in contrast to the previous versions. It is possible that an eccentric arrangement of the loop lifter roller 7 - ie an arrangement in which the loop lifter roller 7 is not equidistant from the two fixed locations 4, 5 - due to the arrangement of the loop lifter 6 is already given as such. Alternatively or additionally, it is possible for the eccentric arrangement to be formed by the deflection hL of the loop lifter roller 7 results because it is pivoted, for example, on a circular arc. In the latter case, the exact arrangement of the loop lifter roller 7 is a function of the deflection hL.

Furthermore, the band 1 at the front fixed point 4 and the rear fixed point 5 is not necessarily articulated yet necessarily clamped firmly. In the general case, an intermediate state is given. The intermediate state can be the same for both fixed points 4, 5. Alternatively, the intermediate states may be different from each other.

In the constellation according to FIG. 14 touches the band 1 according to FIG. 15 the looper pulley 7 at a contact point P, which - with respect to the connecting line 9 - is usually not vertically above a pivot point 15 of the looper roll 7, wherein a line connecting the point of contact P with the fulcrum 15 with the vertical to the connecting line 9 forms an angle δ , At the contact point P, the bending moment MB of the strip 1 has the maximum value ML.

When the band 1 touches the loop lifter roller 7 at the contact point P, geometrical-constructive relationships result, as they are described in US Pat FIG. 16 are shown. Here, α and β mean angles which forms the band 1 with the connecting line 9. With A and B, the fixed locations 4, 5 are designated.

• Zunächst werden - im allgemeinen Fall unabhängig voneinander - für den vorderen und den hinteren Fixpunkt 4, 5 jeweilige Anteile aA, aB festgesetzt. Die Anteile aA, aB geben an, in welchem Umfang das Band 1 im jeweiligen Fixpunkt 4, 5 gelenkig gelagert ist. Sodann wird der Maximalwert ML festgesetzt. Weiterhin wird der Winkel δ festgesetzt.

In order to determine the associated band curves KA, KB for these conditions, the procedure is as follows:

• First, in the general case independently of one another, respective portions aA, aB are set for the front and the rear fixed point 4, 5. The parts aA, aB indicate the extent to which the band 1 is articulated in the respective fixed point 4, 5. Then, the maximum value ML is set. Furthermore, the angle δ is set.

For these specifications, first the bending moment curves BA, BB are determined. The bending moment curves BA, BB are as before linear functions. The minimum values MV, MH result from the maximum value and the proportions aA, aB. Next are - in the approach as before in connection with the FIGS. 7 to 12 explained - the associated band curves KA, KB determined. On the basis of the band curves KA, KB is - separately for the front band curve KA and the rear band curve KB - each determined a resulting deflection hL.

$$\mathit{LBʹ}=\mathit{LB}\cos \delta -\mathit{hL}\sin \delta$$

If the two resulting deflections hL are not equal, the angle δ is set incorrectly. He is therefore corrected. Starting from the corrected angle δ then the above measures are repeated. If the two resulting deflections hL are equal, however, the zeros of the resulting bending moment curves BA, BB are determined. This determination is readily possible because the bending moment curves BA, BB are linear functions. Effective distances LA 'and LB' of the fixed locations 4, 5 from the point of contact P result from the in FIG. 16 to illustrated geometric relationships $$\mathit{La\text{'}}=\mathit{LA}\cos \delta +\mathit{hL}\sin \delta$$

$$\mathit{LB\text{'}}=\mathit{LB}\cos \delta -\mathit{hL}\sin \delta$$

The force FL is thus too $$\mathit{FL}=\frac{\mathit{ML}}{\mathit{La\text{'}}/\left(2-\mathit{from}\right)}+\frac{\mathit{ML}}{\mathit{LB\text{'}}/\left(2-\mathit{from}\right)}$$

It is directed in the direction determined by the angle δ (see FIG. 15 ). Due to the now known size of the force FL and its direction, the third moment component M3 can be calculated in conjunction with the known geometrical-constructional conditions of the loop lifter 6.

Also in the general case, it is thus possible for a plurality of portions aA, aB and a plurality of maximum values ML to be a - in this case three-dimensional - field of associated ones Determine deflections hL. It is also possible to define correspondingly parameterized functions based on this field. It is therefore readily possible to determine the associated third torque proportion M3 from this field or the parameterized functions for arbitrary values of the deflection hL of the band 1.

FIG. 17 therefore shows the general case of the procedure according to the invention. FIG. 17 builds on the approach of FIG. 2 on. In particular, it contains the steps S1, S3, S4 and S6 and S7 and possibly also the step S8. In addition, however, steps S21 to S23 are provided. Further, the steps S2 and S5 are replaced by steps S24 and S25.

In step S21, the controller 11 is given an arrangement of the loop lifter roller 7. This arrangement can - seen in the direction of the connecting line 9 - alternatively static or dependent on the travel s of the adjusting device 8. In the former case, the location of the looper roller 7 in the direction of the direct connecting line 9 seen depending on the specification of the two fixed locations 4, 5 equidistant or not equidistant. In the latter case, the location of the loop lifter roller 7 in the direction of the direct connecting line 9 depends on the travel s of the adjusting device 8. Due to the coupling of the location of the loop lifter roller 7 in the direction of the connecting line 9 and the deflection hL together, the location of the loop lifter roller 7 in the direction of the connecting line 9 thus indirectly depends on the deflection hL.
In step S22, the control device 11 is given the proportion aA to which the band 1 is articulated in the front fixation location 4. Alternatively, it is possible for the control device 11 to determine the proportion aA as a function of geometry properties and instantaneous material properties of the strip 1 in step S22. As a geometry properties are in particular the width b and the thickness h of the belt 1 in question. As current material properties come in particular the elastic modulus E and the yield strength σF of the belt 1 in question.

In step S23, the control unit 11 is given the proportion aB to which the band 1 is articulated in the rear fixing location 5. Alternatively, it is possible for the control device 11 to determine the proportion aB as a function of geometry properties and instantaneous material properties of the strip 1 in step S23. As before, in particular the width b and the thickness h of the band 1 can be considered as geometrical properties. As before, in particular the modulus of elasticity E and the yield strength σF of the strip 1 can be considered as instantaneous material properties.

In step S24, the control device 11 - analogous to step S2 - determined on the basis of the received characteristic variables s, p1, p2, the deflection hL and the moment M. Optionally, however, the controller 11 also determines the location of the looper roll 7 seen in the direction of the connecting line 9 ,

In step S25, the control device 11 - analogous to step S5 - determines the third torque component M3. If necessary, however, the control device 11 additionally takes into account the location of the loop lifter roller 7 in the direction of the connecting line 9 as part of the step S25. Furthermore, when determining the third torque component M3, the control device 11 also takes into account the components aA and aB.

It is also possible, intermediate forms of the procedure of FIG. 17 to realize. Thus, for example, the location of the loop lifter roller 7 can be seen in the direction of the connecting line 9 constant and centered. In this case, step S21 may be omitted. In this case, the step S24 may be completed by the step S2 (refer to the explanations of FIG FIG. 2 ) be replaced. Alternatively or additionally, it is possible, for example, for the proportions aA and aB to be predetermined can be, but must have the same value. In this case, steps S22 and S23 may be summarized.

In any embodiment of the present invention, however, results in a far superior modeling of the third torque component M3 and thus a significantly improved determination of the strip tension Z.

• Ein Band 1 ist zwischen zwei Fixorten 4, 5 mit einem Bandzug Z beaufschlagt. Zwischen den Fixorten 4, 5 ist eine Schlingenheberrolle 7 an das Band 1 angedrückt und dadurch das Band 1 aus einer direkten Verbindungslinie 9 zwischen den Fixorten 4, 5 ausgelenkt. Die Auslenkung hL des Bandes 1 aus der Verbindungslinie 9 und ein auf die Schlingenheberrolle 7 wirkendes Moment M werden erfasst und einer Steuereinrichtung 11 zugeführt, die daraus den Bandzug Z ermittelt. Hierzu wird das Moment M um Momentanteile M1, M2, M3 kompensiert, die auf dem Gewicht G1 des Bandes 1 zwischen den Fixorten 4, 5, auf einem Eigengewicht G2 des Schlingenhebers 6 und auf einer Biegung des Bandes 1 zwischen den Fixorten 4, 5 beruhen. Die Steuereinrichtung 11 ermittelt den Bandzug Z anhand des entsprechend kompensierten Moments M4. Zur Ermittlung des auf der Biegung des Bandes 1 beruhenden Momentanteils M3 werden von der Steuereinrichtung 11 Bandkurven KA, KB des Bandes 1 zwischen der Schlingenheberrolle 7 und den Fixorten 4, 5 ermittelt. Die Bandkurven KA, KB werden derart ermittelt, dass Biegemomentverläufe BA, BB im Band 1, ausgehend von einem Maximalwert ML an der Schlingenheberrolle 7, auf die Fixorte 4, 5 zu linear abfallen. Die Biegemomentverläufe BA, BB und durch die Bandkurven KA, KB gegebene Krümmungsverläufe sind gemäß einer Biegekennlinie miteinander verknüpft sind. Die Biegekennlinie weist für Krümmungen K unterhalb einer Grenzkrümmung KEL einen linearen Anstieg des Biegemomentes MB auf, der für Krümmungen K oberhalb der Grenzkrümmung KEL abflacht.

In summary, the present invention thus relates to the following facts:

• A band 1 is acted upon between two fixed locations 4, 5 with a strip tension Z. Between the Fixorten 4, 5 a Schlaufenheberrolle 7 is pressed against the belt 1 and thereby deflected the belt 1 from a direct line connecting the fixed locations 4, 5. The deflection hL of the strip 1 from the connecting line 9 and a moment M acting on the loop lifter roll 7 are detected and fed to a control device 11, which determines the strip tension Z from it. For this purpose, the moment M is compensated by momentary parts M1, M2, M3, which are based on the weight G1 of the band 1 between the fixing locations 4, 5, on a dead weight G2 of the loop lifter 6 and on a bend of the band 1 between the fixing locations 4, 5 , The control device 11 determines the strip tension Z based on the correspondingly compensated moment M4. For determining the torque component M3 based on the bending of the belt 1, the control device 11 determines belt curves KA, KB of the belt 1 between the belt pulley roller 7 and the fixing locations 4, 5. The strip curves KA, KB are determined in such a way that bending moment curves BA, BB in the strip 1, starting from a maximum value ML at the loop lifter roll 7, drop too linearly onto the fixed locations 4, 5. The bending moment curves BA, BB and given by the band curves KA, KB curvature curves are linked together according to a bending characteristic. For curves K below a limit curvature KEL, the bending characteristic has a linear increase in the bending moment MB, which flattenes for curvatures K above the boundary curvature KEL.

Although the invention has been further illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention as defined by the claims.

Claims (9)

1. Determination method for a strip tension (Z) which is applied to a strip (1) between an upstream fixing location (4) and a downstream fixing location (5),

   - a pressure being applied to the strip (1) between the fixing locations (4, 5) of a loop lifter roller (7) of a loop lifter (6), so that the loop lifter roller (7) deflects the strip (1) out of a direct connecting line (9) between the fixing locations (4, 5),

   - characteristic variables (s, p1, p2) being determined for a deflection (hL) of the strip (1) out of the direct connecting line (9) between the fixing locations (4, 5) and a moment (M) acting on the loop lifter roller (7),

   - the characteristic variables (s, p1, p2) being supplied to a control device (11), by which the strip tension (Z) is determined by using the deflection (hL) and the moment (M),

   - the moment (M) being compensated by a first moment term (M1), a second moment term (M2) and a third moment term (M3) by the control device (11) to determine the strip tension (Z),

   - the first moment term (M1) being based on the weight (G1) of the strip (1) between the fixing locations (4, 5), the second moment term (M2) being based on the inherent weight (G2) of the loop lifter (6), and the third moment term (M3) being based on a bending of the strip (1) between the fixing locations (4, 5),

   - the strip tension (Z) being determined by the control device (11) by using the moment (M4) compensated by the first, the second and the third moment terms (M1, M2, M3), characterized

   - in that an upstream strip curve (KA) of the strip (1) between the loop lifter roller (7) and the upstream fixing location (4), and a downstream strip curve (KB) of the strip (1) between the loop lifter roller (7) and the downstream fixing location (5) are determined by the control device (11),

   - in that the upstream strip curve (KA) is determined by the control device (11) in such a way that an upstream bending moment variation (BA) in the strip (1), starting from a maximum value (ML) on the loop lifter roller (7), as viewed in the direction of the connecting line (9) towards the upstream fixing location (4), falls linearly to an upstream minimum value (MV),

   - in that the downstream strip curve (KB) is determined by the control device (11) in such a way that a downstream bending moment variation (BB) in the strip (1), starting from the maximum value (ML) on the loop lifter roller (7), as viewed in the direction of the connecting line (9) towards the downstream fixed location (5), falls linearly to a downstream minimum value (MH),

   - in that the upstream bending moment variation (BA) and an upstream curvature variation given by the upstream strip curve (KA), and the downstream bending moment variation (BB) and a downstream curvature variation given by the downstream strip curve (KB) are linked with each other in accordance with a bending characteristic curve,

   - in that the bending characteristic curve for curvatures (K) of the strip curves (KA, KB) below a limiting curvature (KEL) exhibits a linear rise of the respective corresponding bending moment (MB) to a first limiting bending moment (MEL), and

   - in that the bending characteristic curve for curvatures (K) of the strip curves (KA, KB) above the limiting curvature (KEL) flattens towards a second limiting bending moment.
2. Determination method according to Claim 1, characterized in that the bending characteristic curve is determined by the control device (11) in accordance with geometric properties (b, h) of the strip (1) between the fixing locations (4, 5), and instantaneous material properties (σF, E) of the strip (1).
3. Determination method according to Claim 1 or 2, characterized in that a location of the loop lifter roller (7) is determined by the control device (11) by using the deflection (hL) of the strip (1) out of the direct connecting line (9) between the fixing locations (4, 5), as viewed in the direction of the direct connecting line (9), and/or in that the location of the loop lifter roller (7), as viewed in the direction of the direct connecting line (9) is not equally far away from the two fixing locations (4, 5), and in that the location of the loop lifter roller (7), as viewed in the direction of the connecting line (9) is taken into account by the control device (11) within the context of determining the third moment term (M3).
4. Determination method according to Claim 1, 2 or 3, characterized in that the control device (11) is predefined a term (aA) by which the strip (1) is supported in an articulated manner at the upstream fixing location (4), and/or in that the control device (11) determines this term (aA) in accordance with geometric properties (b, h) and instantaneous material properties (oF, E) of the strip (1), and in that the control device (11) takes this term (aA) into account when determining the third moment term (M3).
5. Determination method according to one of the above claims, characterized in that the control device (11) is predefined a term (aB) by which the strip (1) is supported in an articulated manner at the downstream fixing location (5), and/or in that the control device (11) determines this term (aB) in accordance with geometric properties (b, h) and instantaneous material properties(σF, E) of the strip (1), and in that the control device (11) takes this term (aB) into account when determining the third moment term (M3).
6. Machine-readable program code for a control device (11) for controlling an upstream and/or a downstream holding element (2, 3), which each have a fixing location (4, 5) between which a strip tension (Z) is applied to a strip (1), wherein a loop lifter roller (7) of a loop lifter (6) is pressed against a strip (1) between the fixing locations (4, 5), so that the loop lifter roller (7) deflects the strip (1) out of a direct connecting line (9) between the fixing locations (4, 5), wherein the program code has control commands (14), the execution of which has the effect that the control device (11) carries out a determination method according to one of the above claims.
7. Machine-readable program code according to Claim 6, characterized in that the program code is stored on a storage medium (13).
8. Software programmable control device for controlling an upstream and/or a downstream holding element (2, 3), the holding elements (2, 3) each having a fixing location (4, 5) between which a strip tension (Z) is applied to a strip (1), a loop lifter roller (7) of a loop lifter (6) being pressed against the strip (1) between the fixing locations (4, 5), characterized in that the control device is programmed with program code (12) according to Claim 6.
9. Conveying device for conveying a strip (1),

   - the conveying device having an upstream holding element (2) and a downstream holding element (3), which each have a fixing location (4, 5) between which a strip tension (Z) is applied to the strip (1),

   - the conveying device having a loop lifter (6) arranged between the holding elements (2, 3),

   - the loop lifter (6) having a loop lifter roller (7) which is pressed against the strip (1), so that the loop lifter roller (7) deflects the strip (1) out of a direct connecting line (9) between the fixing locations (4, 5),

   - there being detection devices (10), by means of which characteristic variables (s, p1, p2) are determined for a deflection (hL) of the strip (1) out of the direct connecting line (9) between the fixing locations (4, 5), and a moment (M) acting on the loop lifter roller (7),

   - the detection devices (10) for supplying the determined characteristic variables (s, p1, p2) being connected to a control device (11),

   characterized in that the control device (11) is formed in accordance with Claim 8.

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