Apparatus for influencing a running material web

An apparatus (1) serves to influence a running material web (2). To this end, the apparatus (1) has at least one adjustable roller (4), which deflects the material web (2). In order to improve the web running characteristics of the material web (2), the at least one roller (4) is adjustable by at least two degrees of freedom. Moreover, the at least one roller (4) is operatively connected to at least two actuators (17) such that at least one of the actuators (17) is assigned to each of the degrees of freedom.

The present application claims priority to German Patent Application no: DE 10 2012 005 439.4, filed Mar. 20, 2012.

FIELD OF THE INVENTION

The invention relates to an apparatus for influencing a running material web

DESCRIPTION OF THE PRIOR ART

An apparatus is known from DE 100 22 926 C2. This apparatus has two rollers, which deflect a material web. The rollers are held rotatably in a common rotating frame. Twisting of the roller relative to the running direction of the web generates a transverse force, which is directed axially to the rollers and displaces the web. This apparatus can thus be used, for example, to regulate the web run. Given a suitable choice of pivot axis relative to the running direction of the web, an equalization of tension can also be realized in the material web transversely to the running direction of the web. In any event, the choice of position of the pivot axis of the rotating frame is of crucial importance to the control result. In order to bring the pivot axis as close as possible to the infeed of the material web, this printed document proposes to use a segmentally tailored roller bearing as the pivot axis. This apparatus has proved itself very well in practice and forms the basis of the present invention.

From DE 1 206 297 B, a strip position controller having a swivel roller is known. This pivoting roller is adjustable by means of two servo drives, which act on the same roller end. The pivoting roller is pivot-mounted in a bearing, so that the pivot axis is geometrically preset and is in no way adjustable.

From DE 695 28 224 T2, a web tensioner is known. This has a rotating frame, which is pivotable about two different axes. These axes are oriented orthogonally to each other, the position of the axes being fixed.

From DE 1 198 162 B, an adjusting device for a roller for the descaling of metal plates is known. This roller is adjusted on both sides by independent hydraulic cylinders. This roller can thus be both pivoted and displaced within preset limits. The driving of this roller is complicated, however, since the movement of each hydraulic cylinder results in both a pivot motion and a sliding motion of the roller.

DE 30 19 001 A1 discloses a roller of the generic type, which has independent actuating cylinders on both sides. Both actuating cylinders are coupled to each other by a pressure-equalizing device. This ensures that the same tensile force acts on both roller ends. An undefined adjustment of the roller is hereby obtained, however, so that this drive system is only suitable for dancer rollers. This printed document forms the basis of the present invention.

The object of the invention is to provide an apparatus of the type stated in the introduction, which apparatus, upon pivoting of the roller, produces improved web running characteristics for the material web.

This object is achieved according to the invention with the following features.

BRIEF SUMMARY OF THE INVENTION

The apparatus according to the invention serves to influence a running material web, wherein it is basically unimportant whether the apparatus influences the web run, the web tension or both. In any event, the apparatus has at least one adjustable roller, which deflects the material web. The at least one roller is hence wrapped through a certain angle by the material web. Only in this way can the at least one roller somehow influence the material web.

In order to improve the web running characteristics of the material web, it is proposed according to the invention to configure the at least one roller such that it is adjustable by at least two degrees of freedom. The at least one roller can have 2, 3, 4 or 5 degrees of freedom, according to requirement. Thus no fixed pivot axis, about which the at least one roller is pivotable, is any longer preset. In order that the roller nevertheless assumes a defined position during operation, it is operatively connected to at least two actuators. The actuators must here be arranged such that at least one of the actuators is assigned to each of the degrees of freedom. The position of the roller is thus defined as a function of the individual actuators. The at least one roller is hence no longer freely adjustable. This is important in order to obtain a defined reaction of the material web to the adjustment of the at least one roller. As a result of this measure, the adjustment of the roller can be realized very liberally, so that in particular an imaginary pivot axis is optionally adjustable within a preset range. In the case of asymmetrical web guidance, it is expedient, for example, to arrange the pivot axis not central to the roller, but central to the web. Where it is desired to influence the web run, this measure reduces secondary effects in relation to the web tension. It has transpired, moreover, that the optimal position of the pivot axis of the at least one roller lies at around ⅔ of the infeed length of the material web. This infeed length is dependent not only on the concrete installation situation, but also on the chosen operating mode of the upstream station. If the upstream station is capable, for example, of removing the last roller, viewed in the web running direction of the web, from the web run, then the infeed length of the downstream station is thereby altered. As a result of the multidimensional adjustability of the at least one roller without fixed pivot axis, allowance can be made for this alteration by simple offsetting of the imaginary pivot axis. This requires, in particular, no change in the mechanics and can therefore be conducted during current operation. There are also applications in which a web guiding device, according to the type of material web, will pass through once in the forward direction and once in the rearward direction. The web guiding device cannot generally be turned round. As a result of the variable pivot axis, the apparatus for influencing the running material web can in this case be adapted without difficulty to the altered direction of passage, without the need for mechanical changes.

Linearly adjustable drives have proved to be most suitable. It is in this case immaterial whether these actuators are hydraulically, pneumatically or electrically driven. It is merely important that, with the said actuators, a distance between two points on the actuator is adjustable, including counter to corresponding force action. Actuators of this type can easily be used in combination in order to adjust the at least one roller into the different degrees of freedom.

Since the actuators are intended to realize, apart from sliding motions, also pivot motions, it is important that these corresponding pivot motions do not jam. This can most easily be realized by both sides of the at least one actuator being held in pivot mountings. A first pivot mounting is here located on one side of the actuator, whilst a second pivot mounting on the second side of the actuator is connected to the at least one roller. It is here immaterial whether the first pivot mounting is fixed on the machine frame or is adjustable, for example, by further actuators. It is merely crucial that only one side of the actuator engages with the roller or its mounting.

A basic problem of the actuators is, however, that the motion of the roller, due to the actuator motion, is relatively complex and thus difficult to reproduce. It would generally be desirable that the at least one roller top executes a defined pivot motion through a preset pivot angle and about a preset imaginary pivot axis. The pivot angle is here regularly preset by a controller. The position of the pivot axis, as well as, where necessary, the direction thereof, is adapted however to the respective requirements. In order to achieve this in tandem with simple operability of the apparatus, it is proposed to connect at least one of the actuators to at least one computation circuit. This computation circuit calculates from the relative vectorial distance {right arrow over (A)} of the first pivot mounting and the relative vectorial distance {right arrow over (B)} of the second pivot mounting from a preset, imaginary pivot axis, and from a preset pivot angle α of the at least one roller, an actuator length L according to the following formula:

It should here be borne in mind that though the position of the second pivot mounting is basically dependent on the pivot angle of the at least one roller, the above formula should be taken to mean that the position of the second pivot mounting should be used for the non-pivoted roller (α=0). Hence the vectors {right arrow over (A)} and {right arrow over (B)} are not dependent on the pivot angle α. Though the above formula is relatively complicated, it can still be evaluated without difficulty during current operation by available microcontrollers. If a plurality of linearly acting actuators act on the at least one roller, then the above formula can be applied in materially the same way for each of these actuators. Only the values {right arrow over (A)} and {right arrow over (B)} have to be individually calculated for each individual actuator. In the above formula, it should be borne in mind that the “t” in respect of the vector {right arrow over (A)} should be regarded as a transposition code. The vectors {right arrow over (A)} and {right arrow over (B)} are basically column vectors. The transposition gives rise to a line vector, which then, multiplied by the following modified rotation matrix, in turn produces a column vector. This column vector is then multiplied scalarly by the vector {right arrow over (B)}.

If the rotational symmetry of the at least one roller is taken into account, then this has 5 possible degrees of freedom. In the absence of further measures, at least 5 actuators would therefore be necessary to hold this roller in a defined position. This makes the apparatus complex, expensive and, at the same time, prone to faults. In general, however, there is no need at all for the roller to be adjustable by all 5 possible degrees of freedom. For simplification of the apparatus, it is therefore advantageous if the at least one roller is held in at least one guide. This guide restricts one or more degrees of freedom of the at least one roller, without the need for an additional actuator. If the apparatus is intended, for example, to correct the run of a material web, then the two degrees of freedom of the at least one roller are blocked in the direction of the angle bisector between the web infeed and the web outfeed by an appropriate guide. The functionality of the apparatus is not hereby impaired. If, on the other hand, the web tension transversely to the running direction of the web is intended to be influenced, degrees of freedom in the running direction of the web are meaningless and can be blocked by appropriate guides. The number of necessary actuators is thereby considerably reduced. In parallel to this, the complexity of the drive system for the apparatus as a whole is also reduced.

It is favourable if the at least one roller is operatively connected to at least one material web controller. This material web controller can regulate any chosen characteristics of the material web by pivoting of the at least one roller. If the at least one roller possesses a sufficient number of degrees of freedom, then influence can be exerted on a plurality of material web controllers, which regulate, on the one hand, the web run and, on the other hand, the web tension. These material web controllers in this case act on differently directed pivot axes of the at least one roller. The use of the at least one roller as a combined web run and web tension control roller, for example, is thus possible. In principle, the pivot axis for both pivot directions can here be individually freely chosen. It is also possible, however, to couple both pivot axes, which facilitates the adjustment.

It is favourable if the apparatus has at least one web edge sensor. This registers the position of a web edge of the material web. It is thus possible to correct the position of the web edge by pivoting of the at least one roller about the imaginary pivot axis. The pivot axis can thus be optionally adjusted in accordance with the requirements.

Alternatively or additionally, it is favourable, if the apparatus has at least two force sensors, which register the tensioning force differential of the material web across its width. Pivoting of the at least one roller then enables this tensioning force differential to be corrected.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a three-dimensional representation of an apparatus1for influencing a material web2. The material web2possesses a running direction3and is deflected around at least one roller4. In the illustrative embodiment according toFIG. 1, the rear one of the two rollers4is necessarily provided, whilst the front roller4, drawn in dashed representation, is merely optional. According to the type of material web and the geometrical infeed and outfeed conditions of the material web2, a single roller4can also suffice, so that the roller4shown in dashed representation can also be dispensed with.

The two rollers4are rotatably supported at the ends in roller bearings5. It is here immaterial whether the rollers4are freely rotatably or are motor-driven. This choice is essentially dependent on the friction losses of the material web2as it is deflected around the roller4.

Held on the rollers4by further roller bearings are rolls6, which are guided in rolling arrangement on a guide7. In principle, the rolls6can also be supported on the roller bearings5, which leads, in particular, to reduced load upon the bearings. Moreover, instead of the rolls6, slide shoes can also be attached directly to the roller bearings5, which slide shoes slide along the guide7. If the material web2, in accordance with the representation inFIG. 1, is fed from below to the apparatus1and is led away downwards from this, then the tensile force of the material web2exerts solely a downwardly directed force component on the rollers4. In this case, it is wholly sufficient to provide an appropriate guide7only beneath the rollers6or the alternative slide shoes. In particular, if alternative web courses are also intended to be allowed, it is necessary, where appropriate, to make the guide7double-sided, so that the rolls6reach into an appropriate free space of the guide7provided on the top side and bottom side of the rolls6.

Although the material web2moves basically in the direction of the running direction3, owing to external influences or inaccuracies in the alignments of rollers in upstream processing equipment, a slight transverse course8of the material web2is also obtained. In the absence of further measures, the material web2would be displaced beyond the roller ends, which would make further processing of the material web2impossible. For this purpose, the rollers4of the apparatus1are made adjustable. The adjustment of the rollers4is here realized such that a web edge9is held in a preset desired position. For this purpose, the apparatus1has a web edge sensor10, which registers the position of the web edge9permanently or cylindrically and feeds it via a signal path11to an actual value input12of a material web controller13. The material web controller13preferably has a P, PI or PID behaviour. The material web controller13additionally possesses a desired value input14, which is operatively connected to a desired value transmitter15.

In order to form a closed control loop, the material web controller13must be operatively connected to the rollers4such that the output signal of the material web controller13provokes an adjustment of the roller4. It is known to connect the material web controller directly to an actuator which pivots the roller4. In this case, however, the roller4would have to have a fixed pivot axis, thereby considerably restricting the applicability of the apparatus1.

In order to enable not only the roller4to be pivotable, but also a pivot axis16to be variably adjustable, the roller4is adjustable by three degrees of freedom—two translatory and one pivotal degree of freedom. The roller is acted on by three actuators17, which are configured, for example, in the form of hydraulic cylinders, pneumatic cylinders or electric servo drives. These actuators17respectively have a first pivot mounting18and a second pivot mounting19. The first pivot mounting18is here configured fixed to a machine frame (not represented) and is therefore, in terms of its position, independent of the setting of the actuator17. By contrast, the second pivot mounting19is connected to the roller bearings5of the roller4and is thus dependent, in terms of its position, on the actuator setting. By adjustment of the actuators17, the distance of the first pivot mounting18from the second pivot mounting19changes, whereby the roller bearing5adjusts itself in accordance with the roller4.

On each actuator17there is additionally provided a displacement transducer20, which registers the respective setting of the actuator17and delivers this via a signal path21.

To each actuator17is assigned a computation circuit22. This computation circuit22is operatively connected via a signal path23to an X-value transmitter24, which adjustably sets the X-coordinate of the pivot axis16. Via a further signal path25, the computation circuit22is operatively connected to a Y-value transmitter26, which sets the Y-coordinate of the pivot axis16. Via a further signal path27, the computation circuit22receives the output signal of the material web controller13. The signal paths23,25and27are identical for all computation circuits22, so that these are mutually connected in accordance with a parallel circuit. By contrast, the signal path21transmits the momentary position of the respective actuator17and is individual to each of the computation circuits22. The computation circuits22respectively possess an output28, which is connected to respectively one of the actuators17via, in each case, a signal path29. The driving of the individual actuators17is thus calculated independently from one another in accordance with the presets of the material web controller13and of the X-value transmitter24, as well as of the Y-value transmitter26.

FIG. 2shows the apparatus1according toFIG. 1in the adjusted position of the rollers4. The pivot axis16has here been used as a virtual axis, which is defined in terms of its position by no mechanics whatsoever. The pivoting of the roller4about the pivot axis16is realized only by appropriately coordinated driving of the actuators17.

It is pointed out that the application of the apparatus1for regulating the web edge9of the material web2should be construed as merely illustrative. In principle, the apparatus1can influence the material web2in any chosen manner, insofar as this is possible by adjustment of at least one of the rollers4.FIG. 3shows an alternative embodiment of the apparatus1according toFIG. 1, wherein the same reference symbols denote the same parts. Instead of the web edge sensor10, force sensors30, which measure the bearing force of the roller4, are provided in the roller bearings5. Both force sensors30are operatively connected to a differential amplifier31, which calculates the differential of the bearing forces at both roller ends and feeds this to the actual value input12of the material web controller13. In this case, the apparatus1operates as a tension equalizing device in order to equalize tensions of the material web2which are formed transversely to its running direction3. The web run of the material web2is chosen such that it has a greatest possible change in length upon adjustment of the roller4. This is achieved by the material web departing from the horizontal direction, being deflected through 180° and being led off again in the horizontal direction. One roller4is here sufficient to regulate the tensioning force.

The computation circuits22are constructed identically to one another and are described by way of example with reference to the basic circuit diagram according toFIG. 4. The same reference symbols here denote the sane parts. The computation circuit22receives via the signal path23a signal proportional to the X-coordinate of the imaginary pivot axis16. Via the signal path25, it receives a signal proportional to the Y-coordinate of the pivot axis16. The output signal of the material web controller13represents the necessary pivot angle of the rollers4and is fed to the computation circuit22via the signal path27. Finally, the computation circuit22receives the signal of the displacement transducer20via the signal path29. The computation circuit22calculates an output signal, which is fed via the signal path21to the actuators17.

The computation circuit22has four value transmitters40-43, the output signals of which represent the X- and Y-coordinates of the rest positions of the pivot mountings18,19. The value transmitter40here delivers the X-coordinate and the value transmitter41the Y-coordinate of the first pivot mounting18, which is fixedly provided in the frame of the apparatus1. By contrast, the value transmitter42delivers the X-coordinate and the value transmitter43the Y-coordinate of the rest position of the second pivot mounting19, which is connected to the roller bearing5of the roller4. As the rest position should here be understood that non-pivoted position of the roller4which is assumed by the at least one roller4when the signal at the signal path27is equal to zero. The roller4will assume this position only when no correction of the web run of the material web2is necessary.

Each of the value transmitters40-43is operatively connected to a non-inverting input of a differential amplifier44-47. Inverting inputs of the differential amplifiers44,45are operatively connected via the signal path23to the X-value transmitter24for determination of the X-coordinate of the pivot axis16. By contrast, inverting inputs of the differential amplifiers46,47are operatively connected via the signal path25to the Y-value transmitter26for determination of the Y-coordinate of the pivot axis16. The differential amplifier44thus calculates the X-coordinate of the distance vector of the first pivot mounting18from the pivot axis16. By contrast, the differential amplifier45determines the X-coordinate of the distance vector of the second pivot mounting19in the rest position of the roller4from the pivot axis16. The differential amplifiers46,47calculate the corresponding Y-coordinates of the two said vectors. An angle signal, which is fed from the material web controller13via the signal path27to the computation circuit22, is fed, on the one hand, to a cosine generator48and, on the other hand, to a sine generator49, which calculate from the signal arriving via the signal path27the cosine value and the sine value respectively.

The differential amplifiers44,46, which represent the X- and Y-coordinate of the first pivot mounting18, are operatively connected, together with the output signals of the cosine generator48and sine generator49, to multipliers51-54. These multipliers51-54are here wired up such that any combination of output signals of the differential amplifiers44,46, on the one hand, and cosine generators48and sine generators49, on the other hand, is multiplied. These multipliers51-54are operatively connected on the output side to two summing units55,56, the summing unit55being inverting and the summing unit56being non-inverting. These summing units55,56determine the X-coordinate and the Y-coordinate of the product of the distance vector of the first pivot mounting18from the pivot axis16with a modified rotation matrix in the form:

The said distance vector should here be regarded as a line vector and not as a column vector.

In a following step60, multipliers61-64determine squares of the output signals of the differential amplifiers44-47. Further multipliers65,66determine a scalar product between the distance vector of the second pivot mounting19from the pivot axis16and the vector which is represented by output signals of the summing units55,56.

The output signals of all multipliers61,66are next added in a summing unit67and fed to an operational amplifier68. This operational amplifier68is linked back via a squarer69, so that it calculates the square root of the output signal of the summing unit67and delivers it to a signal path70. The signal at the signal path70here represents the required length of the associated actuator17, i.e. the required distance of its first pivot mounting18from the second pivot mounting19.

An output signal of the operational amplifier68is fed to a non-inverting input of a differential amplifier80, the inverting input of which is connected via the signal path29to the displacement transducer20of the actuator17. The differential amplifier80calculates an actual-desired value comparison and is operatively connected on the output side to a servo controller81. This servo controller81preferably has a P, PI or PID behaviour and ensures that the position of the actuator17is regulated, so that this, regardless of generated forces, assumes a length as is preset as a signal on the signal path70.

The described computation circuit22is relatively complex and is generally realized as a program of a microcontroller, thereby considerably reducing the wiring complexity. The description of this computation circuit as an analogue circuit makes understanding easier, however, since it can be effected, in particular, independently of program language. Each of the three computation circuits22is of basically identical construction, the signal paths23,25and27of all computation circuits22additionally being connected to one another and having the same signals. The individual computation circuits22differ only by dint of the signal path29individually led up from the associated displacement transducer20and by dint of the adjustments of the value transmitters40-43. On the output side, each computation circuit22is individually connected to a selected actuator17.

As a result of these computation circuits22, it is possible to drive each actuator17individually in such a way that the roller4assumes a pivot angle preset by the material web controller13, the position of the pivot axis16being optionally presettable by the X-value transmitters24and Y-value transmitters26. The position of the pivot axis16can here be changed even during current control operation.

Since some of the embodiments of this invention are not shown or described, it should be understood that a great number of changes and modifications of these embodiments is conceivable without departing from the rationale and scope of protection of the invention as defined by the claims.

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