Pressing unit and method for operating such a pressing unit, and pressing belt and method for producing such a pressing belt

Abstract

The invention relates to a pressing unit (14) which has a pressing belt (16), a sensor unit (22) and a control unit (20), wherein the pressing belt (16) is designed to run in a circulating direction (U) during operation, wherein the pressing belt (16) has at least one marking (26a, 26b) which can be detected contactlessly by the sensor unit (20), wherein the control unit (22) is designed to repeatedly detect the marking (26a, 26b) using the sensor unit (20) and, on the basis thereof, to determine at least one running property of the pressing belt (16). The invention further relates to a method for operating a pressing unit (14), to a pressing belt (16), and to a method for producing a pressing belt (16).

Description

[0001] Description of pressure unit and method for operating such a unit, as well as pressure belt and method for manufacturing such a unit

[0002] The invention relates to a pressure unit, particularly for use in a corrugated board machine. The invention further relates to a pressure belt for such a pressure unit. It also relates to a method for operating such a pressure unit and a method for manufacturing such a pressure belt.

[0003] A pressure belt is typically designed as an endless belt. The pressure belt is wrapped around several guide elements, which drive and regularly tension it. In operation, a pressure belt serves to convey and press an elongated material against another material or a machine part. In a corrugated board plant, a pressure unit with a pressure belt is regularly used as part of a single facer, in which, during operation, the pressure belt presses a flat paper web, also called the "cover web," against a corrugated paper web, also called the "flute." The single facer has a corrugating roll that transforms a flat paper web into a corrugated paper web. This web is coated with glue on one side facing away from the corrugating roll. The pressure belt then presses the cover web onto the glued flute to bond them together.

[0004] A pressure unit with a pressure band is described, for example, in EP 0 698 752 A2, page 2.

[0005] The pressure belt is subjected to heavy wear during operation and is a consumable part that requires regular replacement. Therefore, it is desirable to minimize the stress on the pressure belt during operation of the pressure unit to ensure the longest possible service life. Furthermore, it is desirable that the pressure belt itself be as robust as possible to enable the longest possible and trouble-free operation of the pressure unit, even under adverse environmental conditions.

[0006] Accordingly, it is an object of the invention to provide an improved pressure unit, an improved pressure band, an improved method for operating a pressure unit and an improved method for manufacturing a pressure band.

[0007] The problem is solved according to the invention by a pressure unit with the features of claim 1, a method for operating a pressure unit (operating method) with the features of claim 16, a pressure belt with the features of claim 17, and a method for manufacturing a pressure belt (manufacturing method) with the features of claim 18. Advantageous embodiments, further developments, and variants are the subject of the dependent claims. The descriptions relating to the pressure unit also apply mutatis mutandis to the pressure belt and the two methods, and vice versa. Where steps of the method for operating the pressure unit are specified below, either implicitly or explicitly, advantageous embodiments for the pressure unit result from its configuration to perform one or more of these steps, in particular by means of a correspondingly designed control unit of the pressure unit.

[0008] The pressure unit comprises a pressure belt, a sensor unit, and a control unit. The pressure belt is designed to rotate in a cyclical direction during operation. For this purpose, the pressure unit includes a drive to which the pressure belt is coupled. During operation, the pressure belt rotates in a cyclical direction, which is parallel to the machine direction in which a web-shaped material is conveyed through the pressure unit (page 3). The cyclical direction also corresponds to a longitudinal direction in which the pressure belt extends. Perpendicular to the cyclical direction is a transverse direction (cross machine direction).

[0009] In the following, without limitation of generality, it is assumed that the pressure unit is part of a corrugated board machine, in particular part of a single facer of a corrugated board machine. A corrugated board machine is used to produce corrugated board from several paper webs, which are suitably processed and joined together to form a corrugated board web by means of the corrugated board machine. Although use in the single facer of a corrugated board machine is particularly preferred, the concepts described here can also be advantageously applied to pressure belts for other uses. For example, the pressure unit is part of a double facer of a corrugated board machine or is used in a completely different context, i.e., not in a corrugated board machine, e.g., as part of a printing machine.

[0010] In the assumed case of using the pressure unit as part of a single facer, the pressure unit, as described above, serves to press a flat paper web against a sizing-coated, corrugated paper web. The pressure unit is preferably arranged such that the pressure belt presses the flat paper web against the corrugated paper web while the latter is still in contact with the corrugating roller. The corrugating roller thus serves as a counter-contour when pressing the two paper webs together.

[0011] The pressure belt has at least one marking (i.e., one or more markings) that can be detected non-contactly by the sensor unit. The control unit is configured to use the sensor unit to repeatedly detect the marking and, based on this, to determine at least one running characteristic of the pressure belt. During operation, the marking is therefore detected non-contactly by the sensor unit. Since the marking is located at a fixed position on the pressure belt, it also rotates in the direction of rotation, corresponding to the rotation of the pressure belt as a whole. The marking and the sensor unit are designed and arranged such that, as shown on page 4, a measuring field of the sensor unit is directed onto the pressure belt, and during operation of the pressure unit, the marking repeatedly passes the sensor unit and moves through its measuring field, at which point the marking is detected.The detection of the marking then advantageously allows for monitoring the movement of the pressure belt, which is characterized by one or more running characteristics. Various advantageous designs for the marking and the sensor unit are possible with regard to detection and monitoring; furthermore, depending on the design, it is possible to determine one or more different running characteristics. Various concepts for advantageous designs will be discussed in more detail below.

[0012] A fundamental concept of the invention is the use of a pressure band with a marking, which is preferably permanently integrated into the pressure band and moves with the pressure band during operation. Alternatively or additionally, the marking is applied wholly or partially to a surface of the pressure band. The marking is made of a material, also referred to as marking material, which is integrated into the pressure band during manufacturing. Integration of the marking into the pressure band is possible in various ways. The marking is detected by means of a sensor unit. The sensor unit is, in particular, stationary, while the pressure band moves relative to it, especially such that the marking repeatedly passes the sensor unit and is detected accordingly.The following is an assumption, without limitation of generality, that the pressure band has multiple markings and the sensor unit has multiple sensors. The arrangement of the markings and sensors may vary depending on which of the concepts described below are actually implemented.

[0013] Concept 1: Marking principle and derivation of the transverse course (oblique marking)

[0014] The pressure belt can shift laterally during operation, i.e., in the transverse direction. This is referred to as "lateral drift" (also "belt drift"). Lateral drift is a running characteristic of the pressure belt. The cause of lateral drift cannot be optimally parallel guide elements for the pressure belt or a belt length that varies in the transverse direction (measured in the direction of rotation). To keep the pressure belt in position when viewed in the transverse direction, the lateral drift must be determined and compensated for. In principle, this is possible by mechanically or optically scanning the lateral edges of the pressure belt, but this requires high-quality edges, which can, however, decrease with increasing use. Especially with mechanical contact, there is always an inherently detrimental wear. Therefore, a non-contact concept with an additional marking is used here.The edge is no longer needed, thus avoiding the associated disadvantages.

[0015] Preferably, a specially shaped marker is used to determine the transverse direction. Due to the special marker, a single sensor is sufficient to determine the transverse direction.

[0016] In a suitable embodiment, the marking has at least two edges arranged one behind the other with respect to the direction of rotation, thus passing the sensor unit sequentially. The two edges are spaced apart longitudinally in the direction of rotation. This longitudinal distance varies in the transverse direction; advantageously, the longitudinal distance decreases or increases monotonically or strictly monotonically in the transverse direction. Advantageously, the two edges are each straight, but this is not strictly necessary. In particular, the two edges enclose an angle of more than 0° and less than 180°, preferably an angle in the range of 60° to 120°. In principle, one of the two edges can run perpendicular to the direction of rotation, while the other edge then runs at an angle (i.e., neither parallel nor perpendicular) to the direction of rotation.Alternatively, both edges run obliquely to the direction of rotation, but not parallel to each other, i.e., at different angles relative to the direction of rotation. For example, one edge runs at an angle of +45° relative to the transverse direction and the other edge at an angle of -45° relative to the transverse direction, so that the two edges run at an angle of 90° relative to each other (page 6). The two edges do not necessarily have to touch or cross each other; what is more important is that they are positioned one after the other in such a way that they can be detected successively by the same sensor.

[0017] The sensor unit now suitably includes a first sensor, and the control unit is configured to use this first sensor to measure the longitudinal distance and, based on this measurement, determine the transverse path of the pressure belt. During operation, the control unit thus determines the transverse path. The longitudinal distance is suitably measured simply as the time interval between the detection of the two edges by the sensor. Alternatively, this time interval is converted into a spatial length, for example, using a differently determined speed of the pressure belt. Regardless of how the longitudinal distance is specifically measured, it is, due to the specially shaped marking, a measure of the position of the pressure belt relative to the first sensor, viewed in the transverse direction; the longitudinal distance is therefore directly a measure of the transverse path.

[0018] In an advantageous embodiment, the transverse profile is determined analogously on both sides of the pressure belt. For this purpose, the pressure belt has two markings, and the sensor unit has two sensors (i.e., a first sensor and a second sensor) as described. One marking and one sensor are then arranged on each side of the pressure belt. In a suitable embodiment, this also determines any transverse shrinkage of the pressure belt, which is a consequence of belt distortion in the running direction. This utilizes the fact that transverse shrinkage on the two sides leads to different results for the transverse profile.

[0019] In another suitable embodiment, the marking has a wedge-shaped and / or V-shaped field. This also provides a simple way to form two edges as described above. The wedge-shaped and / or V-shaped field is, in particular, formed in one piece (i.e., monolithically). The two edges are then, in particular, part of a single, e.g., triangular or trapezoidal, border around this field. The marking can then have one or more such fields or fields of other shapes. Page 7

[0020] An additional determination of the speed or rotational time of the pressure belt is not strictly necessary for determining the transverse path itself, but can be advantageous to account for any belt elongation and thus a longitudinal distance that varies over time at the same transverse position. However, this effect is usually negligible, as belt elongation occurs on significantly longer timescales than the transverse path. This effect is usefully used to make predictions about the wear condition (predictive maintenance).

[0021] Concept 2: Magnetic Marking and Magnetic Detection Concept. Optical and inductive measurements are both suitable for non-contact detection, but each has its own disadvantages. An optical sensor can become dirty and then fail. The result of an inductive measurement, on the other hand, is strongly influenced by the distance between the sensor and the mark, and the choice of materials for producing the mark is also limited. A metal strip would be suitable as a mark, but it is difficult to integrate into the pressure strip. Therefore, a magnetic measurement is preferably used for non-contact detection of the mark. In a suitable embodiment, the mark is magnetic, and the sensor unit has at least one magnetic field sensor for detecting the mark, i.e., a sensor that can detect magnetic fields, e.g.,Hall sensor, TMR sensor, or GMR sensor (TMR = "magnetic tunnel resistance," GMR = "giant magnetoresistance"). The marking is produced using a magnetic material integrated into one or more specific areas of the pressure strip, so that these areas (also referred to as "fields") then form the marking. The magnetic marking generates a locally varying magnetic field, which can be measured by the sensor unit. The magnetic field sensor preferably measures not just the magnetic field strength, but a magnetic field gradient, i.e., a change, e.g., an increase or decrease. In this way, the edges of the marking, i.e., the transition between areas with and without magnetic material, are detected. Page 8.

[0022] The pressure band, regardless of the actual design concepts implemented, preferably has a core structure. This core structure is also referred to as the "core." The core structure is preferably made of a material that is as robust as possible, i.e., abrasion- and temperature-resistant, such as steel wires, aramid fibers, and / or carbon fibers, or the like. The core structure is also preferably manufactured in such a way that it is flexible overall, in particular by being produced as a braid, woven fabric, knitted fabric, or similar. For example, the core structure is constructed in a plain weave. Suitablely, the core structure has corresponding gaps, i.e., spaces are formed within it, particularly due to its construction as a braid, woven fabric, knitted fabric, or the like. The core structure therefore has a braided, woven, knitted, or similar structure with corresponding gaps within it.The gaps have a size that depends on the material used and the specific structure, and can be larger or smaller, even vanishingly small, depending on how densely the structure is formed, i.e., braided, woven or knitted.

[0023] Concept 3: Integration of the marking

[0024] Two preferred embodiments for integrating the marking into the pressure band are described below, which can also be combined with each other. Both embodiments are also fundamentally independent of the detection concept used, although the magnetic detection concept with magnetic markings described above is preferred.

[0025] In a first preferred embodiment, the marking is integrated into the pressure band by arranging the marking material in the spaces between the bands. The marking is thus integrated into the base structure and therefore particularly well protected against wear. However, this embodiment requires that the spaces between the bands be sufficiently large to accommodate enough material for reliable marking detection. This can be verified through appropriate tests. In a more advantageous embodiment (page 9), the base structure, more precisely its spaces, is filled with a filler material. The filler material is preferably elastic and / or flexible and as resistant as possible. During the manufacture of the pressure band, the base structure is embedded in the filler material, which then fills the spaces in the base structure accordingly.The filler material is preferably an elastic, one- or multi-component filler, preferably a silicone, and particularly preferably a two-component silicone, which will be assumed hereafter without limitation of generality. The marking is then preferably formed by integrating a magnetic material into the filler material in certain areas, so that marking material (= filler material + magnetic material) is formed in corresponding areas. The magnetic material is either already magnetized during production or, alternatively, is initially magnetizable and is only magnetized during the production of the marking.

[0026] Preferably, the filler material also forms a wear layer on one or both sides of the base structure of the pressure belt. During operation, this wear layer is in contact with a paper web and wears down. The wear layer has a suitable thickness to prevent contact between the base structure and the paper web for as long as possible. As soon as the wear layer is worn away, and possibly even the base structure is exposed, the pressure belt is replaced. The thickness of the wear layer is advantageously in the range of 0.3 mm to 3 mm.

[0027] The material from which the marking is made is preferably located in the spaces within the base structure and is therefore not merely printed, glued, or the like on the surface, although such a design (printed, glued, or the like) is also advantageous in principle. The marking is, so to speak, integrated into the core of the pressure band. This advantageously prevents wear of the marking due to abrasion. Page 10

[0028] In a second preferred embodiment, the marking is integrated into the pressure belt by providing the pressure belt with a wear layer into which the marking material is integrated. As described above, the wear layer is an additional layer on one or both sides of the base structure, thus surrounding the core of the pressure belt. The above explanations apply accordingly. The wear layer is applied to one or both sides of the base structure. The marking is then integrated into the wear layer. This is particularly advantageous for a pressure belt whose base structure has very small or no spaces in which the marking material could be placed. Instead, the marking material is embedded in the wear layer. The explanations regarding the filler material above apply analogously, i.e.,The wear layer is made from a filler material into which a suitable, particularly magnetic, material is embedded in certain areas to form the marking material and thus the marking itself. In a suitable embodiment, the marking is produced separately from the base structure by mixing the filler material with a suitable, particularly magnetic, material and shaping it as desired. This marking is then placed on or attached to the base structure, e.g., by gluing, preferably directly, or alternatively with an additional spacer. Finally, the complete wear layer is formed with further filler material, so that the marking is embedded within it. Suitable filler materials include PTFE, PFA, PEEK, or similar materials, optionally with additional fillers such as glass in the form of so-called "glass beads."The marking is either applied to one side only or to both sides, in which case it is expediently mirrored. If the marking is applied to only one side, it is located on the inside (facing away from the paper web) or on the outside (facing the paper web).

[0029] The marking is significantly thinner than the wear layer. The wear layer is typically between 0.3 mm and 3 mm thick, preferably between 0.5 mm and 1 mm. In contrast, the marking is approximately 1 / 5 to 1 / 10 thinner. The thickness of the marking (see page 11) is advantageously kept as small as possible to avoid pressure marks on the paper web.

[0030] Regardless of how the marking is integrated into the pressure band, the band is preferably only a single layer. In other words, the filler material and the embedded base structure, as well as any wear layer formed from the filler material, together constitute a single, primary layer of the pressure band. The pressure band has no further layers. Such a pressure band is particularly durable because individual layers cannot detach.

[0031] Concept 4: Strain measurement and belt wear

[0032] In a suitable embodiment, the sensor unit comprises two sensors (i.e., a sensor pair) arranged one behind the other in the direction of rotation, so that during operation the marker passes the two sensors sequentially. The control unit is then advantageously configured to: first, detect the marker sequentially with the two sensors and determine the speed of the pressure belt from this; second, detect the marker repeatedly with one of the two sensors and determine the rotational period of the pressure belt from this; and third, determine the belt elongation (also called belt stretch) of the pressure belt (considered in the direction of rotation) based on the speed and the rotational period. The speed and the rotational period are each a running characteristic of the pressure belt. The two sensors thus measure the time interval that the marker requires to travel from one sensor to the other.The spatial distance between the sensors in the direction of rotation is known by design. The speed is then calculated from this distance and the measured time interval. The rotational time, however, is measured using only one of the two sensors, namely as the time it takes for the marker to pass this sensor again after its initial passage. The belt length is variable due to belt elongation and therefore not directly determined by the rotational time. However, the belt length can be calculated in combination with a speed measurement. Using the speed and the rotational time, the belt length, i.e., the actual length of the pressure belt, is then calculated (see page 12), for example, simply as the product of speed and rotational time. By repeatedly measuring the belt length at different times, the belt elongation is then determined, e.g.,as a change in tape length as a function of time or by comparing (difference, ratio) the last determined tape length with a predetermined reference tape length (e.g. at time t = 0).

[0033] Determining the speed and the cycle time as described above are also independent of determining the belt elongation and can be carried out independently of each other, and are advantageous.

[0034] The belt elongation is preferably determined using a statistical method, e.g. averaging, over several, e.g. 100 to 1000 or more, revolutions of the pressure belt in order to obtain the most meaningful measurement result possible.

[0035] Belt elongation is an important indicator of the wear of the pressure belt. Belt elongation is preferably used to determine or predict whether and when the pressure belt needs to be replaced. This prevents machine downtime and production losses. In particular, a new pressure belt can be ordered and made available in a timely manner.

[0036] In a suitable design, the tension of the pressure belt is adjusted depending on the belt elongation, in particular such that a specific target belt tension is maintained. For this purpose, for example, the distance between two guide elements (e.g., rollers) for the pressure belt is changed accordingly.

[0037] A particular advantage of the solution described here is that the determination of the belt elongation is based on a measurement directly at the pressure belt. This measurement does not require an angular position sensor and is independent of paper thickness, corrugated roller, and, in general, the single facer. The belt elongation can also be advantageously determined separately at different points, e.g., on both sides of the pressure belt, by using a sensor pair and a marker at each point to be monitored. Page 13

[0038] An additional advantage is that the two sensors provide redundancy for determining the lateral orientation (Concept 1). Since only a single sensor is required for this, if one of the two sensors fails, the lateral orientation can still be determined and compensated for.

[0039] In principle, it is also possible to determine the belt tension with only a single sensor if the speed is measured by other means, e.g., with an angular position sensor (resolver, encoder) on a roller guiding the pressure belt, on the corrugated roller, or on another roller rotating at the same speed as the pressure belt. However, such a speed measurement is less reliable. Nevertheless, this solution is expediently used in case one of the two sensors fails.

[0040] Concept 5: Marking for identifying the pressure band

[0041] In an advantageous embodiment, the marking forms an individual code by which the pressure band can preferably be uniquely identified. A marking with multiple edges is particularly suitable for this purpose, the number and / or longitudinal spacing of which (viewed in the direction of rotation) are used to encode, for example, an identification number (also serial number or simply ID). Each individual pressure band then suitably has a unique marking, and the markings of different pressure bands differ in the number of edges and / or their longitudinal spacing. The control unit is then designed accordingly to identify the pressure band with the help of the sensor unit by measuring the precise configuration of the marking, for example, by detecting the number of edges and / or their longitudinal spacing.Advantageously, only the longitudinal spacing of the marking is used as a code and detected by the control unit, while the number of markings preferably remains the same for different pressure strips and is therefore predictable. The edges can, in principle, be formed by fields of any shape, which are spatially separated from one another and together form the marking. However, strip-shaped fields are particularly advantageous. These can be arranged both perpendicular and oblique to the direction of rotation (page 14). It is particularly important that the fields forming the code are arranged in such a way that they pass by at least one sensor of the sensor unit sequentially during operation.

[0042] The marking is designed and arranged in such a way that it represents a unique identifier (code) for the pressure band. During the production of each pressure band, the marking is varied accordingly to generate an individual code, e.g., similar to a barcode.

[0043] Using the code, the control unit efficiently retrieves individual calibration data for the pressure belt from a central database to optimize the operation of the pressure unit. Conversely, all measured values ​​and generated data, especially the determined running characteristics, are efficiently stored by the control unit either locally or externally, e.g., in the aforementioned database, along with the code. This ensures that these measured values ​​and data are assigned to the corresponding pressure belt, enabling subsequent analysis and / or statistical evaluation.

[0044] Concept 6: Marking with multiple stripes

[0045] In a suitable embodiment, the marking has at least two stripes arranged one behind the other in the direction of rotation, each running obliquely relative to the direction of rotation and in opposite directions. "Opposite directions" means, in particular, that, viewed in the direction of rotation, one of the two stripes runs from the outside in (from the edge towards the center of the pressure band), while the other of the two stripes runs conversely from the inside out. The stripes are, in particular, separated from each other, thus forming independent and spatially distinct fields of the marking, so that it is essentially composed of two partial markings (fields). This embodiment is specifically compatible with Concept 1 and suitable for determining the transverse direction.Each strip forms one of the two edges; due to the differently inclined paths of the strips, two differently inclined edges are formed (page 15), between which a longitudinal distance varying in the transverse direction is formed as described above.

[0046] Marking with at least two stripes can also be used for all other concepts and is particularly advantageous for concept 5 in order to create a unique code. In this case, it is expedient to use more than two stripes, e.g., up to ten stripes or more. The number of stripes, their longitudinal distances from each other (measured in the direction of rotation), and / or their respective lengths (i.e., the longitudinal distance between the two edges of a single stripe; also measured in the direction of rotation) are expediently used as variable parameters for generating the code.

[0047] In a particularly suitable embodiment, the marking has two groups of stripes, whereby the stripes within each group are parallel to each other, but the stripes of different groups run at different angles, as described in connection with Concept 1, in order to measure the transverse orientation. One of the two required edges is then part of one group, and the other of the two required edges is part of the other group. The longitudinal distance, which is then used to determine the transverse orientation, is expediently not varied to form the code, but remains the same for all pressure strips (but still varies in the transverse direction to implement Concept 1).

[0048] Concept 7: Determining the S-delay

[0049] In an advantageous embodiment, the pressure belt has at least two markings arranged at different positions (transverse positions) relative to the direction of rotation, preferably in opposite edge regions of the pressure belt. Furthermore, the sensor unit has, in particular, two sensors, one for detecting each of the two markings. If concept 4 is also to be implemented, the sensor unit analogously has two pairs of sensors, i.e., a total of four sensors, namely two on each side of the pressure belt. The control unit is suitably designed to use the two sensors (at different transverse positions) to measure a phase between the two rotating markings while the pressure belt is running (page 16) and to determine an S-shaped distortion of the pressure belt based on this phase. The S-shaped distortion is a running characteristic and quantifies an S-shaped distortion of the pressure belt.An S-shaped distortion occurs particularly when the web path varies in the transverse direction and / or when there are differences in the belt tension on both sides of the pressure belt.

[0050] The S-shaped distortion is then suitably compensated for by controlling a guide element for guiding and / or tensioning the pressure belt separately on each side, depending on the phase, and thereby tilting it accordingly. The guide element is, in particular, a roller that guides the pressure belt. The guide element has an adjustable inclination, i.e., an axis whose angle relative to the transverse direction can be adjusted by means of one or more actuators (e.g., pressure cylinders). The control unit is then designed to adjust the inclination of the guide element depending on the S-shaped distortion in such a way that the S-shaped distortion is reduced, in particular minimized. In this way, an S-shaped distortion control system is implemented with the control unit.

[0051] The aforementioned concepts 1 to 7 are each independently feasible and advantageous on their own. However, combining two or more of these concepts results in beneficial synergies, at least in that the same markers and / or sensors now combine different functions and / or advantages.

[0052] Operating procedures

[0053] In the method for operating a pressure unit, in particular a pressure unit as described above, the pressure unit comprises a pressure belt, a sensor unit, and a control unit. During operation, the pressure belt rotates in a single direction. The pressure belt has at least one marking which can be detected non-contact by the sensor. Using the sensor unit, the control unit repeatedly detects the marking and determines at least one running characteristic of the pressure belt based on this detection. Advantageous embodiments result analogously from what has already been said. Advantageously, as shown on page 17, the operation of the pressure unit is appropriately controlled by the control unit based on the at least one running characteristic, for example, by compensating for belt elongation or distortion.

[0054] Pressure belt and its manufacture

[0055] As previously described, the pressure strip preferably has a base structure. This structure is optionally filled and / or coated (on one or both sides) with a filler material. During the manufacturing of the pressure strip, the marking is generally integrated by mixing a material detectable by the sensor unit and a filler material to form a marking material, which is then integrated into the pressure strip. In particular, the marking material is integrated, as described, into the spaces between the base structure and / or into the wear layer. The material detectable by the sensor unit is preferably a magnetic or magnetizable powder (and thus detectable), e.g., iron powder or, more generally, a hard magnetic powder, e.g., samarium-cobalt or neodymium-iron-boron. The filler material is, for example, a silicone, PTFE, PFA, PEEK, or the like.

[0056] For example, the marking material is produced by mixing a magnetic or magnetizable powder with a filler material, which serves primarily as a binder. This marking material is then filled into a suitably shaped recess in the pressure belt and magnetized, thus forming a correspondingly shaped, magnetic marking. Alternatively, the marking is first formed separately and then integrated as a whole into the pressure belt. The filler material is advantageously identical to the filler material used for the rest of the pressure belt production, and in particular for its wear layer, so that a metallurgical bond between the marking and the pressure belt is achieved.

[0057] The ratio of binder to magnetic or magnetizable material is generally not critical. Studies have shown that a wide variety of mixing ratios are generally practical. It is advisable to use as much magnetic or magnetizable material as possible (page 18) so that it can still be detected as reliably as possible with the given sensor unit. However, the amount of magnetic or magnetizable material should not be so high that the mechanical stability or integrity of the pressure band is significantly compromised. Depending on the specific design of the pressure band and where exactly the marking is integrated or applied, the optimal proportion of magnetic material in the marking material can vary.

[0058] For the production, specifically the integration of the marking, the filler material in the areas for the marking (in the base structure and / or the wear layer) of an otherwise finished, unmarked pressure belt can first be removed, and then the marking material inserted into the exposed areas in the base structure and / or the wear layer. Alternatively, the marking is formed first, and then the remaining base structure is embedded in filler material.

[0059] The marking can be formed (integrated or applied) at virtually any point on the pressure belt, including areas away from the edges and perimeter, such as in the center. The marking is also advantageously temperature-resistant, particularly up to approximately 200°C. This is especially useful when used in corrugated board production lines, where correspondingly high temperatures can occur.

[0060] The manufacturing process is fundamentally feasible and advantageous even independently of the previously described concepts 1 to 7.

[0061] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Each drawing schematically shows:

[0062] Fig. 1 shows a corrugated board plant,

[0063] Fig. 2 shows a pressure unit, page 19

[0064] Fig. 3 shows the determination of the transverse path of a pressure belt,

[0065] Fig. 4a shows a cross-section of a pressure belt,

[0066] Fig. 4b shows a variant of the pressure band from Fig. 4a,

[0067] Fig. 5 shows the determination of the belt elongation of a pressure belt.

[0068] Fig. 6 shows a pressure band with a marking consisting of several stripes,

[0069] Fig. 7 shows the determination of an S-distortion of a pressure belt,

[0070] Fig. 8 shows a method for manufacturing a pressure band,

[0071] Fig. 9 shows a section of a pressure belt with the base body partially exposed.

[0072] Figure 1 shows an embodiment of a corrugated board machine 2. This machine has several unwinders 4, a single facer 6, a double facer 8, a cutting unit 10, and a delivery unit 12. The corrugated board machine 2 also has a pressure unit 14, which is part of the single facer 6. The corrugated board machine 2 is used to produce corrugated board W from several paper webs P, which are suitably processed by the corrugated board machine 2 and joined together to form a corrugated board web. The concepts described here are also applicable in other contexts.

[0073] An exemplary embodiment of the pressure unit 14 is shown in detail in Fig. 2. The pressure unit 14 comprises a pressure belt 16, a drive 18, a sensor unit 20, and a control unit 22. The pressure belt 16 is designed to rotate in a direction U during operation and is coupled to the drive 18 for this purpose. The drive 18 is optional; alternatively, the pressure belt 16 can be driven, for example, via the corrugated roller 24. The direction U is parallel to a machine direction in which the corresponding side 20

[0074] The paper web P is conveyed through the pressure unit 14. Perpendicular to the direction of rotation U is a transverse direction Q (“cross machine direction”).

[0075] In the present case, the pressure unit 14 serves to press a flat paper web P (shown in Fig. 2 with a solid line) against a sizing-coated, corrugated paper web P (shown in Fig. 2 from the corrugating roller 24 with a dashed line). The pressure unit 14 is arranged in Fig. 2 such that the pressure belt 16 presses the flat paper web P against the corrugated paper web P, while the latter is still in contact with a corrugating roller 24 of the single facer 6. The corrugating roller 24 thus serves as a counter-contour when pressing the two paper webs P together.

[0076] The pressure belt 16 has at least one marking 26a, 26b, which can be detected non-contactly by the sensor unit 20. Various examples of a marking 26a, 26b are shown in Figures 3, 5, 6, and 7. The control unit 22 is configured to repeatedly detect the marking 26a, 26b with the aid of the sensor unit 20 and, depending on this, to determine at least one running characteristic of the pressure belt 16. By detecting the marking 26a, 26b, the running of the pressure belt 16 is then monitored; this running is characterized by one or more running characteristics.

[0077] Figure 3 illustrates how the pressure belt 16 can move laterally, i.e., in the transverse direction Q, during operation. This is referred to as the "transverse movement" QV. The transverse movement QV is a running characteristic of the pressure belt 16. To keep the pressure belt 16 in position when viewed in the transverse direction Q, the transverse movement QV must be determined and compensated for. A specially shaped marker 26a, 26b is used to determine the transverse movement QV. Due to the special marker 26a, 26b, a single sensor 28a, 28b, 28c, 28d is sufficient for this purpose.

[0078] The markings 26a, 26b shown here each have at least two edges 30a, 30b, which are arranged one behind the other with respect to the direction of rotation U and thus pass the sensor unit 20 one after the other. The two sides 21

[0079] Edges 30a and 30b are spaced apart by a longitudinal distance L1 in the direction of rotation U. The longitudinal distance L1 varies in the transverse direction Q. In this case, the two edges 30a and 30b are straight, but this is not strictly necessary. The two edges 30a and 30b form an angle 32 of more than 0° and less than 180°. Basically, one of the two edges 30a and 30b, e.g., edge 30a, can run perpendicular to the direction of rotation U, as shown in Fig. 3, while the other edge 30b then runs obliquely (i.e., neither parallel nor perpendicular) to the direction of rotation U. Alternatively, both edges 30a and 30b run obliquely to the direction of rotation U, but not parallel to each other, i.e., at different angles relative to the direction of rotation U. For example, as shown in Fig.6. One edge 30a is at an angle of +45° relative to the transverse direction Q, and the other edge 30b is at an angle of -45° relative to the transverse direction Q, such that the two edges 30a and 30b are at an angle of 90° to each other. The two edges 30a and 30b do not necessarily have to touch or cross each other; it is more important that they are positioned one after the other in such a way that they can be detected successively by the same sensor 28a, 28b, 28c, 28d.

[0080] The sensor unit 20 now suitably includes a first sensor, e.g., sensor 28a, and the control unit 22 is configured to use the first sensor 28a to measure the longitudinal distance L1 and, based on this, to determine the transverse direction QV of the pressure band 16. Due to the specially shaped markings 26a, 26b, the longitudinal distance L1 is a measure of the position of the pressure band 16 relative to the first sensor 28a, viewed in the transverse direction Q. The longitudinal distance L1 is thus directly a measure of the transverse direction QV.

[0081] In Fig. 3, the transverse path QV is determined analogously on both sides of the pressure band 16 (this is not mandatory). For this purpose, the pressure band 16 has two markings 26a, 26b, and the sensor unit 20 has two sensors, e.g., sensors 28a, 28b. One marking 26a, 26b and one sensor 28a, 28b are then arranged on each of the two sides of the pressure band 16. Page 22

[0082] In the exemplary embodiment shown in Fig. 3, the marking 26a, 26b has a wedge-shaped and V-shaped field, and is in fact identical to this field. The wedge-shaped and / or V-shaped field is formed in one piece (i.e., monolithically). The two edges 30a, 30b then form part of a single, triangular border around this field. The marking 26a, 26b can optionally also have several fields (e.g., as in Fig. 6), and these need not necessarily be of the same shape.

[0083] A magnetic measurement is performed here for the non-contact detection of the markings 26a, 26b, which are magnetic. The sensor unit 20 has at least one magnetic field sensor 28a, 28b, 28c, 28d for detecting the markings 26a, 26b, which is capable of detecting magnetic fields. The magnetic markings 26a, 26b generate a locally varying magnetic field, which can be measured by the sensor unit 20. The magnetic field sensor 28a, 28b, 28c, 28d measures a magnetic field gradient, i.e., a change, e.g., an increase or decrease, such that the edges 30a, 30b are detected.

[0084] The pressure band 16 has a base structure 34. This can be seen in Figures 4a and 4b, which each show a cross-sectional embodiment of the pressure band 16. Figure 4a shows a woven version of the pressure band 16, but other versions are also possible. The base structure 34 is also referred to as the "core" and is made of a material that is as robust as possible, i.e., abrasion- and temperature-resistant. The base structure 34 is manufactured as a braid, woven fabric, knitted fabric, or similar, and is therefore flexible overall. In Figures 4a and 4b, the base structure 34 is shown in a plain weave as an example. The base structure 34 has corresponding spaces 35, i.e., spaces 35 are formed within the base structure 34.

[0085] Figures 4a and 4b each show a possible embodiment for integrating the markings 26a and 26b. These embodiments are generally combinable and independent of the detection concept used, although in this case the magnetic detection concept described above is implemented with magnetic markings 26a and 26b. Page 23

[0086] In the embodiment according to Fig. 4a, the marking 26a, 26b is integrated into the pressure band 16 by arranging a marking material in the spaces 35. The marking 26a, 26b is thus integrated into the base structure 34. The spaces 35 are filled with a filler material 36. The marking 26a, 26b is then formed by integrating a magnetic material into the filler material 36 in certain areas, so that marking material (= filler material + magnetic material) is formed in corresponding areas. The resulting markings 26a, 26b are represented in Fig. 4a by rectangles with dashed borders. The magnetic material is either already magnetized during manufacturing or, alternatively, is initially magnetizable and is only magnetized during the production of the marking 26a, 26b. The material from which the marking 26a, 26b is made is shown in Fig.4 is located in the spaces 35 of the base structure 34 and is not merely printed, glued, or otherwise superficially applied. The marking 26a, 26b is, so to speak, integrated into the core of the pressure band 16.

[0087] The filler material 26 forms a wear layer 37 of the pressure belt 16 on both sides of the base frame 34, as shown in both Fig. 4a and Fig. 4b. During operation, the wear layer 37 is in contact with the paper web and wears down. The wear layer 37 has a suitable thickness D to prevent contact between the base frame 34 and the paper web for as long as possible. Once the wear layer 37 is worn away, the pressure belt 16 is replaced.

[0088] In the embodiment shown in Fig. 4b, the markings 26a, 26b are integrated into the pressure belt 16 by integrating the marking material into the wear layer 37. The wear layer 37 is made of filler material 36, into which a suitable material is embedded in certain areas to form marking material and thus the markings 26a, 26b in those areas. In Fig. 4b, the markings 26a, 26b are represented by rectangles. In Fig. 4b, the markings 26a, 26b are only present on one side; in a variant not shown, they are present on both sides and optionally even mirrored. In Fig. 4b, page 24, the markings 26a, 26b are significantly thinner than the wear layer 37.

[0089] Regardless of how the markings 26a, 26b are integrated into the pressure band 16, the latter is shown in Figures 4a, 4b as a single layer. In other words, the filler material 36 and the embedded base structure 34, as well as the wear layer 37, which may be formed from the filler material 36, together constitute a first and only layer of the pressure band 16. The pressure band 16 has no further layers.

[0090] In one possible embodiment, the sensor unit 20 has two sensors 28a, 28b, 28c, 28d (i.e., a sensor pair) arranged one behind the other in the direction of rotation U, so that during operation the marking 26a, 26b passes successively by the two sensors 28a, 28b, 28c, 28d. This is shown by way of example in Fig. 5, where the two sensors 28a, 28c form a first sensor pair on one side of the pressure belt and the two sensors 28b, 28d form a second sensor pair on the other, opposite side of the pressure belt 16.The control unit 22 is configured to: first, detect the marker 26a sequentially with the two sensors 28a and 28c and determine the speed of the pressure belt 16 from this; second, detect the marker 26a repeatedly with one of the two sensors 28a and 28c and determine the rotational period of the pressure belt 16 from this; and third, determine the belt elongation BD of the pressure belt 16 (viewed in the direction of rotation U) based on the speed and the rotational period. The speed and the rotational period are each a running property of the pressure belt 16. The two sensors 28a and 28c measure the time interval that the marker 26a requires to travel from sensor 28c to sensor 28a. The spatial distance between these sensors 28a and 28c in the direction of rotation U is known by design. The speed is then calculated from this distance and the measured time period.The orbital period, however, is measured using only one of the two sensors 28a, 28c, namely as the time it takes for the marker 26a to pass this sensor 28a, 28c again after its initial passage (page 25). The belt elongation BD is then determined by repeatedly measuring the belt length at different times.

[0091] In the solution described here, the determination of the belt elongation BD is based on a measurement directly on the pressure belt 16. This measurement does not require an angular position sensor and is independent of paper thickness, corrugated roller 24, and generally the single facer 6. The belt elongation BD can also be determined separately at different locations, e.g., as shown in Fig. 5, on both sides of the pressure belt 16, by using a sensor pair and a marker 26a, 26b at each location to be monitored. The explanations above regarding the marker 26a and the sensors 28a, 28c apply analogously to the marker 26b and the sensors 28b, 28d.

[0092] In Fig. 5, only simple bars are shown as markings 26a, 26b. However, other markings 26a, 26b can also be used here, especially those described in connection with the other figures.

[0093] In one possible embodiment, the marking 26a, 26b forms an individual code by which the pressure band 16 can be identified. An embodiment of this is shown in Fig. 6. The marking 26a, 26b has several edges 30, 30a, 30b, the number and / or longitudinal distances L1, L2 (viewed in the direction of rotation U) to each other are used to encode, for example, an identification number. Each individual pressure band 16 then has a unique marking 26a, 26b, and the markings 26a, 26b of different pressure bands 16 differ in the number of edges 30, 30a, 30b and / or their longitudinal distances L1, L2, L3. Accordingly, the control unit 22 is designed to identify the pressure band 16 with the aid of the sensor unit 20 by measuring the exact configuration of the marking 26a, 26b. In Fig.In Figure 6, only the longitudinal distances L2 between adjacent strips 38 are used as an example to form the code; the longitudinal distances L1 and L3, however, are the same for all pressure strips 16. This variant is preferred, but other variants are also suitable. Page 26.

[0094] The longitudinal distances L2 and L3 are also configured such that they do not vary in the transverse direction Q, but remain constant. In this way, the code is unchanged in the transverse direction Q except for the longitudinal distance L1 and comprises five longitudinal distances L1, L2, of which the first and the last two, i.e., the longitudinal distances L2, then form a four-digit code. The control unit 22, using the sensor unit 20, first detects the five longitudinal distances L1, L2, L3 and then extracts the four longitudinal distances L2, which form the code, in order to identify the pressure band 16. An analogous procedure is followed if a different combination of longitudinal distances L1, L2, L3 is used to form the code. The code does not necessarily have to be formed directly from the longitudinal distances L1, L2, L3, but can also be derived in other ways, e.g., from the ratios of the longitudinal distances L1, L2, L3.

[0095] In the embodiment shown in Fig. 6, the marking 26a, 26b has at least two strips 38 (i.e., strip-shaped fields 38) arranged one behind the other in the direction of rotation U, and which run obliquely relative to the direction of rotation U and in opposite directions to each other. "Opposite directions" means that, viewed in the direction of rotation U, one of the two strips runs from the outside to the inside (from the edge towards the center of the pressure band 16) (in Fig. 6, the three left strips 38), while the other of the two strips 38 runs conversely from the inside to the outside (in Fig. 6, the three right strips 38). The strips 38 are separated from each other, thus forming independent and spatially separated fields 38 of the marking 26a, 26b.The edges 30a, 30b required to determine the transverse direction QV are formed by the two middle strips 38, so that a longitudinal distance L1 varying in the transverse direction Q is formed between them as already described.

[0096] In the embodiment according to Fig. 6, the markings 26a, 26b also show, by way of example, two groups of strips 38: the first group consisting of the three strips 38 on the left and the second group consisting of the three strips 38 on the right. The strips 38 of each group are parallel to each other, but the strips 38 of different groups run at different angles. One edge 30a is part of page 27 of one group, while the other edge 30b is part of the other group.

[0097] In one possible embodiment, the pressure belt 16 has at least two markings 26a, 26b, which are arranged transversely to the direction of rotation U at different positions (transverse positions), e.g., as shown in Fig. 7 in opposite edge regions of the pressure belt 16. Furthermore, the sensor unit 20 has two sensors 28a, 28b, one each for detecting one of the two markings 26a, 26b. The control unit 20 is configured to use the two sensors 28a, 28b to measure a phase 40 between the two rotating markings 26a, 26b while the pressure belt 16 is running, and to determine an S-shaped distortion SV of the pressure belt 16 based on the phase 40. The S-shaped distortion SV is a running characteristic and quantifies an S-shaped distortion of the pressure belt 16, as can be seen in Fig. 7.

[0098] The S-delay SV is then compensated for by controlling a guide element 42 for guiding the pressure belt 16 separately on each side, depending on the phase 40, and thereby tilting it accordingly. In Fig. 7, the guide element 42 is a roller with which the pressure belt 16 is guided. The guide element 42 has an adjustable inclination, i.e., an axis whose angle relative to the transverse direction Q can be adjusted by means of one or more actuators 44, e.g., pressure cylinders. The control unit 22 is then configured to adjust the inclination of the guide element 42 depending on the S-delay SV such that it is minimized. In this way, S-delay control is implemented with the control unit 22.

[0099] The concepts described in connection with Figures 3 to 7 can be implemented independently of one another and combined in any way. Furthermore, the combinations of partial aspects described in Figures 3 to 7 are not necessarily mandatory, and only partial aspects of Figures 3 to 7 can be combined (e.g., only the markings 26a, 26b from Figure 3 or 6 in Figure 5 or 7; or only the sensors 28a, 28b, 28c, 28d from Figure 5 in Figures 3 and 7). Page 28

[0100] As already described in connection with Figures 4a and 4b, the pressure band 16 has a base structure 34 which is filled with a filler material 36. During the manufacture of the pressure band 16, the marking 26a and 26b is generally integrated into the pressure band 16 by mixing a material detectable by the sensor unit 20 and a filler material 36 to form a marking material. The material detectable by the sensor unit 20 is, in this case, a magnetic or magnetizable powder (and thus detectable), and the filler material 36 is, in this case, a two-component silicone.

[0101] A possible manufacturing process is shown schematically in Fig. 8. In the first step S1, the marking material is produced by mixing a magnetic or magnetizable powder with a filler material 36, which serves as a binder. In the second step S2, the filler material 36 is first dissolved from an otherwise finished, unmarked pressure strip 16 in the areas for the markings 26a, 26b. A possible result of this is shown in Fig. 9, in which the basic structure 34 is clearly visible in area 46. In the third step S3, the marking material is then inserted into these now-free areas 46, resulting in a pressure strip 16 with markings 26a, 26b as shown in Fig. 4a. In Fig. 9, the area 46 shown is shaped such that a strip 38 is produced there as shown in Fig. 6.Alternatively, in the second step S2 the marking 26a, 26b is formed first and then in the third step S3 the remaining basic framework 34 is embedded in filling material 36.

[0102] In this process, the markings 26a, 26b are formed before the base structure 34 is completely filled, and only afterwards are the remaining, marking-free areas of the pressure band 16 around the markings 26a, 26b filled with simple filler material 34, i.e. without the magnetic or magnetizable material.

[0103] Alternatively, the markings 26a, 26b are produced separately from the base structure 34 by mixing filler material 36 with suitable material and shaping it as desired. These markings 26a, 26b are then placed on or attached to the base structure 34, e.g., glued. Finally, with further information (see page 29)

[0104] The filler material 36 forms the complete wear layer 37, so that the marking 26a, 26b is embedded therein, resulting in a pressure band 16 as shown in Fig. 4b. The marking 26a, 26b can, in principle, be formed at any point on the pressure band 16, especially away from the edges and peripheral areas of the pressure band 16, e.g., in its center (not shown).

[0105] Page 30

[0106] Reference symbol list

[0107] 2 corrugated board plants

[0108] 4 dispensers

[0109] 6 Single Facer

[0110] 8 Double Facer

[0111] 10 cutting units

[0112] 12 Storage

[0113] 14 pressure unit

[0114] 16 pressure band

[0115] 18 Drive

[0116] 20 sensor units

[0117] 22 Control unit

[0118] 24 Grooved roller

[0119] 26a, 26b Marking

[0120] 28a, 28b, 28c, 28d sensor, magnetic field sensor

[0121] 30, 30a, 30b edge

[0122] 32 angles

[0123] 34 Basic framework

[0124] 35 space

[0125] 36 Filling material

[0126] 37 Wear layer

[0127] 38 fields, strips

[0128] 40 Phase

[0129] 42 Guide element

[0130] 44 Actuator

[0131] 46 area

[0132] BD ligament strain

[0133] D Strength (thickness) of the wear layer

[0134] L1 Longitudinal spacing (varies in transverse direction)

[0135] L2, L3 longitudinal spacing

[0136] P Paper web

[0137] Q Transverse direction Page 31

[0138] QV Cross-section

[0139] 51 first step

[0140] 52 second step

[0141] 53 third step SV S-delay

[0142] U Direction of rotation

[0143] W corrugated cardboard

Claims

Page 32 Claims 1. A pressure unit (14) comprising a pressure band (16), a sensor unit (22) and a control unit (20), a. wherein the pressure band (16) is configured to run in a circular direction (U) during operation, b. wherein the pressure band (16) has at least one marking (26a, 26b) which is detectable without contact by the sensor unit (20), c. wherein the control unit (22) is configured to detect the marking (26a, 26b) repeatedly with the aid of the sensor unit (20) and to determine at least one running property of the pressure band (16) depending thereon.

2. Pressing unit (14) according to claim 1, wherein the marking (26a, 26b) has at least two edges (30a, 30b) which are arranged one behind the other with respect to the direction of rotation (U), wherein the two edges (30a, 30b) are spaced apart from each other at a longitudinal distance (L1) when viewed in the direction of rotation (U), which varies in the transverse direction (Q).

3. Pressing unit (14) according to claim 2, wherein the two edges (30a, 30b) enclose an angle (32) of more than 0° and less than 180°, preferably an angle (32) in the range of 60° to 120°.

4. Pressure unit (14) according to claim 2 or 3, wherein the sensor unit (20) has a first sensor (28a, 28b), wherein the control unit (22) is configured to measure the longitudinal distance (L1) with the first sensor (28a, 28b) and to determine a transverse path (QV) of the pressure band (16) on the basis of this. Page 33 5. Pressing unit (14) according to one of claims 2 to 4, wherein the marking (26a, 26b) has a wedge-shaped and / or v-shaped field (38).

6. Pressing unit (14) according to one of claims 1 to 5, wherein the marking (26a, 26b) is magnetic and wherein the sensor unit (20) for detecting the marking (26a, 26b) has at least one magnetic field sensor (28a, 28b, 28c, 28d).

7. Pressure unit (14) according to one of claims 1 to 6, wherein the pressure band (16) has a base frame (34) in which the marking is integrated.

8. Pressing unit (14) according to claim 7, wherein spaces are formed in the base structure (34) which are filled with a filling material (36), wherein the marking (26a, 26b) is formed by integrating a magnetic material into the filling material (36) in certain areas.

9. Pressure unit (14) according to one of claims 1 to 8, wherein the pressure band (16) has a base structure (34) and a wear layer (37) which is applied to the base structure (34), wherein the marking (26a, 26b) is integrated into the wear layer (37).

10. Pressure unit (14) according to one of claims 1 to 9, wherein the pressure band (16) is formed in a single layer.

11. Pressure unit (14) according to one of claims 1 to 10, wherein the sensor unit (20) has two sensors (28a, 28b, 28c, 28d) which are arranged one behind the other in the direction of rotation (U), wherein the control unit (22) is configured Page 34 a. to detect the marking (26a, 26b) successively with the two sensors (28a, 28b, 28c, 28d) and to determine a speed of the pressure belt (16) from this, b. to detect the marking repeatedly with one of the two sensors (28a, 28b, 28c, 28d) and to determine a rotation period of the pressure belt (16) from this, c. to determine a belt elongation (BD) of the pressure belt (16) based on the speed and the rotation period.

12. Pressure unit (14) according to one of claims 1 to 11, wherein the marking (26a, 26b) forms an individual code by which the pressure band (16) can be identified.

13. Pressing unit (14) according to one of claims 1 to 12, wherein the marking (26a, 26b) has at least two strips (38), a. which are arranged one behind the other in the direction of rotation (U) and b. which are each inclined relative to the direction of rotation (U) and run in opposite directions to each other.

14. Pressing unit (14) according to one of claims 1 to 13, wherein this is part of a corrugated board plant (2), in particular part of a single facer (6) of a corrugated board plant (2).

15. Pressure unit (14) according to one of claims 1 to 14, wherein the pressure band (16) has at least two markings (26a, 26b) which are arranged transversely to the direction of rotation (U) at different positions, preferably in opposite edge regions of the pressure band (16), wherein the sensor unit (20) has two sensors (28a, 28b, 28c, 28d), one each for detecting one of the two markings (26a, 26b), wherein the control unit (22) is configured to measure a phase (40) between the two rotating markings (26a, 26b) with the aid of the two sensors (28a, 28b, 28c, 28d) when the pressure band (16) is running and Page 35 to determine an S-displacement (SV) of the pressure band (16) based on the phase (40).

16. Method for operating a pressure unit (14), in particular a pressure unit (14) according to any one of claims 1 to 15, wherein the pressure unit (14) comprises a pressure band (16), a sensor unit (20) and a control unit (22), a. wherein the pressure band (16) runs in a circular direction (U), b. wherein the pressure band (16) has at least one marking (26a, 26b) which is detectable without contact by the sensor unit (20), c. wherein the control unit (22) detects the marking (26a, 26b) repeatedly with the aid of the sensor unit (20) and determines at least one running characteristic of the pressure band (16) depending thereon.

17. Pressure band (16) for a pressure unit (14) according to one of claims 1 to 15.

18. Method for producing a pressure band (16) according to claim 17, wherein the marking (26a, 26b) is integrated into the pressure band (16) by mixing a material detectable with the sensor unit (20) and a filler material (36) to form a marking material and integrating this into spaces (35) of a base structure (34) of the pressure band (16) and / or into a wear layer (37) of the pressure band (16).

19. Method according to claim 18, wherein the material which is detectable with the sensor unit (20) is a magnetic or magnetizable powder.

Images