Measuring roller for determining a property of a ribbon-shaped item guided over a measuring roller, and use of such a measuring roller

Description

[0001] The invention relates to a measuring roller for determining a property of a band-shaped material guided over a measuring roller.

[0002] WO 2020 / 174001 A1 discloses a measuring roller for determining a property of a strip-shaped material, in particular metal strip, guided over the measuring roller. This measuring roller has a base body with a circumferential surface, wherein at least one recess is provided in the base body and a force sensor is arranged in the recess. WO 2020 / 174001 A1 proposes forming a layer over the recess.

[0003] From WO 2020 / 120329 A1 it is known to arrange a first piezoelectric force sensor next to a second piezoelectric force sensor in a recess of the measuring roller body of a measuring roller and to arrange the two force sensors so close to each other that either the sensor surface of the first piezoelectric force sensor is directly adjacent to the sensor surface of the second piezoelectric force sensor or the first piezoelectric force sensor is arranged so close to the second piezoelectric force sensor that the angle between an end boundary line extending in the radial direction of the measuring roller, which intersects the point of the sensor surface of the first force sensor that is closest to the sensor surface of the second force sensor, and a line that runs in the plane containing the end boundary line and the line that intersects the point of the sensor surface of the first force sensor that is closest to the sensor surface of the second force sensor,The angle between the end boundary line and the point on the sensor surface of the second force sensor that is closest to the sensor surface of the first force sensor is less than 65°. The sensor surface of piezoelectric force sensors commonly used in measuring rollers in this technical field typically has a diameter of ≥ 30 mm.

[0004] With the sensor types used so far, it is difficult to detect unevenness at the edge of the strip with the required or desired measurement accuracy. The position of the strip edge often cannot be determined with sufficient precision. In thin strips, the length distribution in both the width and length directions can exhibit highly variable characteristics. Furthermore, the limited number of available discrete sensors imposes restrictions on the representation of the length distribution in thin strips.

[0005] DE 10 2014 115023 A1 relates to a flatness measuring roller for determining flatness errors of a metal strip by measuring the strip tension distribution across the strip width.

[0006] Against this background, the invention was based on the objective of proposing a measuring roller for determining a property of a ribbon-shaped material guided over a measuring roller, in which the resolution of the determined properties is increased.

[0007] This problem is solved by the subject matter of claim 1. Advantageous embodiments are described in the dependent claims and the following description.

[0008] The invention is based on the fundamental idea of ​​using other sensors instead of the piezoelectric force sensors known from the prior art, which, in the form currently used in this technical field, have sensor areas larger than 600 mm², so that in a segment of the measuring roller body, the through a region of the circumferential surface, two radial planes that intersect in the longitudinal axis of the base body and each extend in a radial direction and intersect the circumferential surface, and two planes perpendicular to the longitudinal axis that intersect the circumferential surface, is limited, wherein the area of ​​the circumferential surface rolled into a plane has a size of x mm 2<, a number y sensors are arranged, wherein y > 2 x / 100 .

[0009] The fundamental concept of the invention, namely the use of compact sensors, makes it possible to integrate multiple sensors into a single segment of the measuring roller body. The invention also allows, for example, the determination of microripples. In a preferred embodiment, the invention aims to equip a measuring roller with sensors, particularly pressure sensors, in the same way that a camera chip is equipped with pixels. In a preferred embodiment, this enables the preprocessing and compression of the sensor data, especially the pressure sensor data, and its transmission in the same or a similar manner to the transmission of images from a camera chip. Suitable solutions for this exist in information technology and can be adapted to the application of the invention.

[0010] The measuring roller according to the invention enables a higher lateral measurement resolution. This high lateral resolution for flatness measurement can be achieved in both the width and length directions. Due to the high lateral resolution along the circumference of the measuring roller, additional parameters such as transverse arcs or strip alignment can be determined. Strip cracks at the strip edge or defects can be detected. Furthermore, sufficiently large defects in the strip topography (e.g., scale pits, scale, holes) can be detected. When using a counter roller, thickness variations can also be derived. Flatness defects in the range of wavelengths <10 mm and amplitudes around 1 µm (so-called micro-ripples) can also be detected with the targeted resolution. It can be assumed that statements can be made regarding residual stresses or their distribution, as well as Lüders effects.

[0011] The design rule y>2x / 100 is to be regarded as a low lower limit with which the advantages of the invention can be achieved. In a preferred embodiment, the number y of sensors in the segment y>2x / 10 is... y > FAKTOR / 10 x with FACTOR >20, preferably with FACTOR >200, preferably with FACTOR >2000, preferably with FACTOR >20,000, preferably with FACTOR >200,000.

[0012] The prior art, where a rotatably mounted base body is used, regularly employs solid rollers with recesses in their circumferential surface. These recesses are often pockets extending radially inwards from the circumferential surface of the base body. In other embodiments, a groove is formed in the circumferential surface of the base body. In some embodiments, this groove runs parallel to the longitudinal direction of the base body. In other embodiments, the groove extends around the circumferential surface of the base body like part of a helix. The approach of integrating force sensors into recesses formed in the outer surface of a measuring roller's base body has purely mechanical limitations with regard to the possible resolution of the measured property of the strip-shaped material.Even if the number of force sensors were increased in existing designs, the number of pocket-like recesses or grooves would have to be increased. However, the possible number of such pockets or grooves is limited by purely mechanical constraints. The higher the number of force sensors, the smaller the remaining web width between two recesses.

[0013] The narrower the bridge width between two adjacent recesses, the lower the stability of the base body's outer circumference. Depending on the application, and especially on the typical force exerted on the measuring roller by the strip-shaped material guided over it, the recesses must be spaced significantly apart to prevent damage to the base body due to the applied force and to ensure the measuring roller's long-term usability.

[0014] In a preferred embodiment, the invention provides that the measuring roller body comprises a base body and a layer applied to the base body, and that the measuring roller is equipped with a rotatably mounted base body and a plurality of sensors, wherein, according to the inventive approach, a layer is applied to the base body, with at least one of the sensors being arranged in the layer. With this preferred embodiment, the invention departs from the concept of inserting sensors in recesses that are formed as pockets or grooves in the outer circumferential surface of a base body.

[0015] In a preferred embodiment, the two radial planes that intersect in the longitudinal axis of the base body and each extend in a radial direction and intersect the circumferential surface enclose an angle ALPHA that lies between 2° and 180°, preferably between 5° and 180°, preferably between 10° and 180°, preferably between 2° and 135°, preferably between 2° and 95°, preferably between 2° and 45°, preferably between 5° and 135°, preferably between 5° and 95°, preferably between 5° and 45°, preferably between 10° and 135°, preferably between 10° and 95°, preferably between 10° and 45°.

[0016] In a preferred embodiment, the distance between the two planes perpendicular to the longitudinal axis corresponds to the length of the base body. In an alternative, also preferred embodiment, the distance between the two planes perpendicular to the longitudinal axis corresponds to 5% to 95% of the length of the base body, preferably 5% to 75% of the length of the base body, preferably 5% to 50% of the length of the base body, preferably 25% to 95% of the length of the base body, preferably 25% to 75% of the length of the base body, preferably 25% to 50% of the length of the base body.

[0017] In a preferred embodiment, the circumferential surface of the base body is the outer surface of a cylinder and has a size in the range of 0.4 to 3.5 m², preferably in the range of 2.5 to 3 m².

[0018] In this preferred embodiment, the invention pursues the approach of arranging a layer and at least one of the sensors within the layer. This approach allows, for example, the use of different materials for the base body and the layer in a preferred embodiment. For example, a material can be selected for the base body that gives the measuring roller its fundamental stability, while a material can be used for the layer that is possibly not as rigid as the material used for the base body and thus possibly even allows the layer to be compressed, but which, due to this elasticity, also allows the sensors to be arranged as close together as possible.

[0019] The measuring roller preferably has a base body. Preferably, the base body has a closed circumferential surface. In a preferred embodiment, the base body is a solid roller extending along a longitudinal axis.

[0020] It is conceivable to implement designs in which the layer applied to the base body is only applied to the circumferential surface of the base body in the area of ​​a force sensor. After the layer has been applied, the measuring roller would thus have surface sections formed by the circumferential surface of the base body (in the areas where no layer has been applied to the circumferential surface of the base body) and surface sections formed by the outward-facing surface of the layer. Such designs have the advantage of being more economical to manufacture because the layer structure does not have to be applied over the entire circumferential surface of the base body.

[0021] It is conceivable to implement embodiments in which the circumferential surface of the base body is not continuously cylindrical before the layer is applied, but rather has a depression in the area of ​​the layer to be applied. The layer can then be formed in this depression in such a way that it is in contact with the portion of the circumferential surface of the base body located at the bottom of the depression and has an outer surface that seamlessly connects to the surface sections of the base body that are located next to the depression.

[0022] In a preferred embodiment, the layer is applied to the entire circumferential surface of the base body. In a preferred embodiment, the base body has a cylindrical outer surface. In a preferred embodiment, the layer has a constant thickness, such that the outer surface of the layer is parallel to the outer surface of the base body.

[0023] In a preferred embodiment, at least one of the sensors is arranged within the layer. In a preferred embodiment, the layer is bounded by interfaces. One interface of the layer is, for example, the contact surface of the layer with the outer circumferential surface of the base body. Another interface of the layer is, for example, the outer surface of the layer. If the layer is applied as a hollow cylinder to a cylindrical base body, further interfaces of the layer are the annular end faces of the hollow cylinder. If a layer is formed in a recess of a base body, one interface of the layer is the contact surface of the layer with the surface of the base body forming the recess, and another interface of the layer is the outer surface formed by the layer. In a preferred embodiment, the sensor is arranged in the space bounded by the interfaces of the layer.

[0024] It is conceivable to implement embodiments in which several layers are applied to the base body distributed across its circumferential surface, with each layer having a specific sensor.

[0025] In one embodiment, one of the existing sensors would be arranged in the layer, while other sensors would be arranged in the base body or in another layer. However, it is preferred that the majority (more than 50%), more than 75%, more than 90%, and especially all sensors are arranged in the layer. It is also preferred that the majority (more than 50%), more than 75%, more than 90%, and especially all sensors are arranged in the space bounded by the interfaces of a single layer.

[0026] Several approaches are possible for arranging the sensor within the layer. In a preferred embodiment, the sensor is embedded in the material forming the layer. In such an embodiment, each interface of the sensor is in contact with the material forming the layer, or the interface is in indirect contact with the material forming the layer, for example via an adhesive.

[0027] In a preferred embodiment, the sensor is arranged in a recess in the layer, wherein the recess, viewed from the sensor, is limited by the material of the layer at least in the majority (more than 50%), particularly preferably in the predominant majority (more than 75%) and particularly preferably in all circumferential directions and / or is limited by the material of the layer in the radial rolling direction from the sensor.

[0028] In a particularly preferred embodiment, the recess, as seen from the sensor, is also bounded radially inwards by the material of the layer. In such an embodiment, the recess would thus be completely enclosed by the material of the layer. In an alternative embodiment, it can be provided that, as seen from the sensor, the recess in the layer is bounded externally only by the material of a further layer applied to the layer forming the recess. Additionally or alternatively, the recess formed in the layer for the sensor can be bounded radially inwards, as seen from the sensor, by the material of a further layer or by the material of the base body.It is conceivable to implement embodiments in which the sensor is placed on the outer surface of the base body and then, while simultaneously forming the recess, the layer is built up around the sensor in a layer application.

[0029] In a preferred embodiment, a preload is provided for the force sensor to maintain a continuous relationship between the pressure force and the sensor signal. The sensor can be inserted as a separate component into a recess in the roller body and preloaded at the designated position to ensure a force-fit connection to the roller body. This closes the gap required for insertion. If the sensor is integrated "in one piece" into the layer, a preload of this kind may no longer be necessary. Another reason for a preload could be to operate the sensor in as linear a range as possible or to bring it into its operating range (around a specific operating point). This could also be achieved on a sensor within a layer by local thermal, mechanical, electrical, UV light, piezoelectric, or similar influences.These considerations apply equally to system calibration.

[0030] With this embodiment, it is possible for the layer to be built up around the sensor, forming the recess, in such a way that, viewed from the force sensor, the layer also limits the recess radially outwards. In an alternative embodiment, the sensor is placed on the outer surface of the base body, and the layer is built up around the sensor, forming the recess that receives the sensor. The recess formed in the layer initially remains open radially outwards and is then closed by another layer, so that, viewed from the sensor, the recess is limited radially outwards by the material of this further layer.

[0031] In a preferred embodiment, the recess in the layer in which a force sensor is arranged is limited only by the material of the layer, or only by the material of the layer and the material of the base body, or only by the material of the layer and a coating applied to the outer perimeter of the layer, or only by the material of the layer, the material of the base body and the material of a coating applied externally to the layer.

[0032] In a preferred embodiment, the recess in the layer in which a force sensor is arranged is not closed by a cover.

[0033] In a preferred embodiment, the layer is formed by a film or mat that wraps around the outer circumference of the base body by at least 180°, more preferably by more than 180°, more preferably by more than 270°, and most preferably by 360°. Using a film or mat to form the layer allows the manufacturing processes for the base body and the layer to be separated. The base body can, for example, be manufactured in a first way, such as from a semi-finished product, while the layer can be manufactured in another way, such as from plastic. Using a film or mat also makes it possible to integrate any wiring for the force sensors into the layer. This eliminates the need to incorporate channels for cables into the base body. A corresponding base body can therefore be manufactured more easily.

[0034] In a preferred embodiment, the film or mat is firmly connected to the outer circumferential surface of the base body. This connection can be achieved, for example, by gluing, by a hook and loop fastener, or by positive-locking connections such as snap fasteners or tongue and groove connections with grooves in the base body and ridges on the side of the film facing the base body.

[0035] It is also conceivable to wrap the film or mat under tension around the outer surface of the base body, so that the tension of the film or mat alone creates a radially inward holding force that holds the film or mat to the outer surface of the base body. It is also conceivable to prepare the outer surface of the base body to increase adhesion, for example, by roughening it. Connections are also conceivable that, for example, through charge separation (rubbing a balloon -> hair stands on end), result in micro-forces and thus enable adhesion. In chemistry, for example, micro-forces can result from the angular arrangement of molecular structure components, dipoles (water), or from electron imbalances in the bonds.

[0036] In a preferred embodiment, a film is provided that contains the sensors and, more preferably, also the wiring. In areas where neither sensors nor electrical connections nor electronic components are located, recesses, e.g., holes, could be provided. In a preferred embodiment, the film is bonded to the base body with a suitable compound (layer application by spraying, rolling, troweling, or 3D printing). The proposed holes would create bridges between the sensors.

[0037] Another embodiment is conceivable in which the layer is formed by a film or mat, and a retaining tube is slid onto the outside of the film or mat. The retaining tube could be shrunk onto the film.

[0038] In a preferred embodiment, a first sensor is provided in the layer, which is located less than 1.5 m, and more preferably less than 1 mm, and more preferably less than 0.5 mm, in the circumferential direction from a second sensor, which is also arranged in the layer. The distance "in the circumferential direction" refers to the circumferential component of a line connecting the center point of the first sensor with the center point of the second sensor. If the first sensor and the second sensor are arranged on a purely circumferential line, then, in the preferred embodiment, the center of the first sensor is located less than 1.5 mm in the circumferential direction from the center of the second sensor.If the first sensor and the second sensor are not arranged on a circumferential line, but are spaced apart from each other in the circumferential direction, but are also offset from each other in a direction parallel to the longitudinal axis of the base body, then the dimension for the circumferential spacing refers to the circumferential component of the line connecting the centers of the two sensors.

[0039] In a preferred embodiment, the majority of the sensors present in the segment (more than 50%), and more preferably the vast majority (more than 75%), or even more preferably all sensors present in the segment, are arranged circumferentially less than 1.5 mm from an adjacent sensor. This particularly close arrangement of the sensors increases the resolution. Since, according to the concept of the invention, the sensors no longer need to be arranged in recesses of the base body of the measuring roller, but, according to a preferred embodiment, are arranged in the layer applied to the base body, it is made possible to arrange the sensors closer to each other than is possible with measuring rollers known from the prior art.

[0040] In a preferred embodiment, the majority (more than 50%), and in particular preferably the vast majority (more than 75%), of the sensors arranged in the segment, and in particular preferably all sensors present in the segment, are arranged according to a grid in the layer. In a preferred embodiment, the distances between adjacent sensors within the grid are equal. Embodiments are conceivable in which individual sensors are additionally arranged between the sensors arranged according to a grid.

[0041] In a preferred embodiment, the grid is formed by intersecting lines, at whose intersection points the sensors are arranged. The following embodiments are conceivable with regard to the orientation of the lines: According to a first embodiment, two groups of lines are provided, wherein the lines of the first group are parallel to each other and extend circumferentially, and the lines of the second group are parallel to each other and parallel to the longitudinal direction of the base body. According to a second embodiment, two groups of lines are provided, wherein the lines of the first group are parallel to each other and extend at a first angle to the circumferential direction and at an angle to the longitudinal axis of the base body, and the lines of the second group are parallel to each other and extend at a second angle to the circumferential direction and at an angle to the longitudinal axis of the base body, wherein in a particularly preferred embodiment, a line of the first group intersects a line of the second group, and the line of the first group at the point of intersection extends at an angle of 90° to the line of the second group.

[0042] In a preferred embodiment, a first sensor is arranged at a first radial distance to the longitudinal axis of the measuring roller body, and a second sensor is arranged at a second distance to the longitudinal axis that differs from the first. The sensors can therefore be arranged in different planes. Arranging the sensors in different planes can offer various advantages that can be combined, for example... 1. In terms of extending the measuring range, a more sensitive and a less sensitive sensor could be arranged one above the other. At lower pressure forces, the measurement signal could be read from the more sensitive sensor. As the pressure force increases, this sensor reaches its limit. The less sensitive sensor could then take over for the further increased pressure forces. 2. For space reasons, arranging different sensors on different levels is advantageous. For example, temperature and pressure sensors could be arranged one above the other. 3. Additional pressure sensors in other planes are conceivable, which register lateral forces rather than radial ones. When a corrugated belt is guided around a roller, reaction forces arise in the lateral direction. Sensors that register different force directions can be mounted one above the other. 4. The variation of individual sensors may be too high.The resulting measurement error could be reduced by stacking (connecting in series) individual sensors to form a single, combined sensor.

[0043] In a preferred embodiment, the majority (more than 50%) of the sensors arranged in the segment, and in particular preferably the predominant majority (more than 75%) of the sensors arranged in the segment, and in particular preferably all sensors present in the segment, are arranged with the same radial distance to the longitudinal axis of the measuring roller body.

[0044] In a preferred embodiment, the base body of the measuring roller has a first end with a bearing journal and a second end with a bearing journal, wherein the bearing journals of the base body are rotatably mounted in supports of the measuring roller, for example in ball bearings.

[0045] In a preferred embodiment, the base body of the measuring roller is cylindrical.

[0046] A solid roll is understood to be a basic body that is a single piece and whose shape was either produced by a primary forming process, such as casting, and / or whose geometric shapes are produced from a single semi-finished product by separation processes, in particular by machining, especially by turning, drilling, milling, or grinding. It is also conceivable that the basic body itself is produced from a layered deposit, for example, by one of the layering processes described in this description, such as a 3D printing process.

[0047] In a preferred embodiment, in such a base body designed as a solid roller, the measuring roller journals arranged at the end faces of the measuring roller for rotatable mounting in the measuring roller, for example in ball bearings, are also parts of the one-piece base body. However, designs such as those found, for example, in Figur 2 as shown in DE 20 2014 006 820 U1, it is conceivable that the main part of the base body is designed as a cylindrical solid roller, which has end-faced covers on which the measuring roller pins are designed.

[0048] In a preferred embodiment, the base body has a closed circumferential surface. In a preferred embodiment, the circumferential surface of the base body is closed except for one or more channels leading into the interior of the base body for receiving cables. In a preferred embodiment, no force sensors are arranged in the channels. The base body can be closed at one end by an end face, in which at least one cable entry or cable channel may be provided. It may be provided that, apart from the cable entry or cable channel, no other opening is present in the end face of the base body. In a preferred embodiment, the end faces of the base body are arranged at an angle of 90° to the circumferential surface of the base body.

[0049] The base body can be connected to one or more devices that enable its rotatable mounting. In a preferred embodiment, the measuring roller, in particular the base body of the measuring roller, has bearing journals.

[0050] According to the invention, the measuring roller has a plurality of sensors. In a preferred embodiment, the plurality (more than 50%) of the sensors arranged in the segment, and in particular preferably the predominant plurality (more than 75%) of the sensors arranged in the segment, are all sensors present in the segment that measure the same property, for example a force, a temperature, or a chemical composition.

[0051] In a preferred embodiment, the majority (more than 50%), and in particular preferably the vast majority (more than 75%), of the sensors arranged in the segment, and in particular preferably all sensors present in the segment, are force sensors. The term "force sensor" as used in this description comprises a sensor that has a sensor surface and is designed such that it can generate a sensor signal when the position of the sensor surface changes.

[0052] A force sensor, as described, typically has an associated reference system and reacts to changes in the position of the sensor surface within this reference system. The force sensor may have a housing. The housing is then often the reference system. In a housing-equipped embodiment, the force sensor can, for example, detect whether the position of the sensor surface relative to the housing has changed. If the force sensor is designed as a piezoelectric force sensor, for example, it has a piezoelectric quartz crystal that can generate an electrical signal when the position of one of its surfaces relative to a reference surface, such as an opposite surface of the piezoelectric quartz crystal, changes—that is, when the piezoelectric quartz crystal is compressed. In a force sensor designed as a strain gauge, a change in the position of the surface of the force sensor causes the length of the measuring wire or strain gauge to change.The position of the measuring grid formed from measuring wires is changed, usually by stretching, but also, for example, by compression. In a force sensor designed as an optical force sensor, the optical properties of the force sensor, such as the refractive index or reflection properties, are changed by the change in the position of the surface.

[0053] The layer can accommodate 3D printed structures, which in turn contain strain gauges or similar structures.

[0054] In a preferred embodiment, the majority (more than 50%) of the sensors arranged in the segment, in particular preferably the vast majority (more than 75%) of the sensors arranged in the segment, and in particular preferably all sensors present in the segment, are by 3D printing, vapor deposition, SMD assembly, painting generated.

[0055] For example, the sensor shown at this link can be used as a sensor produced by SMD assembly: https: / / www.digikey.de / product-detail / de / honeywell-sensing-and-productivitysolutions / FMAMSDXX025WCSC3 / 480-FMAMSDXX025WCSC3CT-ND / 12088280

[0056] These sensors can be factory calibrated and internally temperature-compensated. The measurement signal is provided via I2C or SPI bus. For example, the I2C bus can accommodate multiple masters and up to 128 slaves. This allows 128 sensors to be grouped together and fed to a distribution board, referred to here as the channel module. The supply voltage can also be provided from there. The aggregated sensor signals are forwarded to a main board, also located on the reel and referred to here as the group module. Transmission from the group module on the reel to the evaluation module outside the reel can be wireless or optical.

[0057] For a measuring range of 1270 mm across the width, a row of 128 sensors would be required, assuming a sensor spacing of 10 mm. Corresponding channel modules would be needed for each N row around the roll's circumference. For a roll circumference of 1 m, with a sensor spacing of 10 mm in the circumferential direction, M = 100 / N channel modules would be required. These would be received, processed, and forwarded by the group module. In this example, the measuring roll has 12,800 individual sensors. The channel modules and the group module can be located on the ends of the roll. The group module does not necessarily need to receive all 100 channels mentioned in this example simultaneously, but only needs to process the sensor rows currently being monitored at any given time. This can be achieved through flexible switching (similar to a multiplexer). The same applies to the channel modules.If the belt only covers part of the measuring range in the width direction, reducing the number of sensor signals transmitted is advisable. Each scan provides visual information about the pressure distribution between the material being measured and the roller. This information is updated with each scan step during the evaluation process, allowing the desired quality parameters for belt flatness to be determined.

[0058] An insulating layer can be applied to the roller body, and the conductor connections with the pads for contacting the pressure sensors are located in or on this layer. The pressure sensors are located on the insulating layer, and their pins are connected to the pads of the conductor tracks. The pressure sensors are surrounded by a compressible layer; only the pressure spheres are located in the elastic outer sheath, preferably made of steel. A large proportion of the compressive force exerted by the belt on the outer sheath acts directly on the force sensors. Pre-tensioning of the sensors is not required.

[0059] In a preferred embodiment, the sensor is applied using additive technology, although alternatively, it is also possible to equip it with finished passive sensors.

[0060] In this variant, pressure sensors with analog outputs are either integrated or additively manufactured. Each sensor is connected via a horizontal and a vertical electrical conductor, creating a matrix structure. For a square matrix with 10x10 sensors, 20 lines need to be evaluated. Two multiplexers for the horizontal and vertical lines allow the individual measured values ​​to be read, amplified, and analog-to-digital converted. This electronics can be placed either on the end face of the roller or, to avoid additional wiring, between the sensors. An additional layer beneath the sensors is also conceivable. The individual channels are transmitted via a bus (e.g., I2C or SPC) to group modules. These group modules can be located on the end face of the roller or inside the roller.

[0061] Force sensors can be derived from resistors, capacitors, inductors, voltage elements, piezo sensors, Hall circuits, or other semiconductors.

[0062] In a preferred embodiment, the sensor is implemented as an active sensor with an analog output. Such a sensor is described in more detail, for example, at this link: https: / / www.digikey.de / product-detail / de / honeywell-sensing-and-productivitysolutions / FSS020WNSB / 480-6894-ND / 6605549

[0063] Alternatively, active sensors with analog output can also be housed in the layer.

[0064] In a preferred embodiment, an additively manufactured or discretely integrated sensor is clamped, namely embedded in a compressible layer.

[0065] In a preferred embodiment, a layer in which a sensor is arranged is a single layer and part of a layer system. Each layer can perform one or more specific tasks. Possible tasks include, for example: Insulation, embedding, mechanical joining, electrical joining, sensor technology (pressure, temperature, humidity, conductivity, ultrasound-based, electromagnetic, electrostatic), signal processing.

[0066] In a preferred embodiment, the sensors are distributed on a grid (possibly pre-arranged separately from the reel), wired, and fixed. The spaces between the sensors and possibly a thin layer over the sensors are filled with, for example, resin (e.g., epoxy), rubber, ceramic (e.g., via sol-gel), etc. Additionally, a steel sleeve can be fitted onto the sensor, or the sensors can be inserted into a steel sleeve with recesses provided for this purpose (possibly filled with a fixing material (resin, rubber, etc.)) and fitted onto the steel core.

[0067] In a preferred embodiment, a pressure-sensing film that can be firmly bonded to the roller base (e.g., by soldering or gluing) is produced, for example, by depositing piezoresistive thin films and applying them to a separately manufactured roller base. Likewise, the application of a layer system such as the pressure-sensing film directly onto the roller base with an insulating layer (e.g., sol-gel, PVD / CVD, varnish) is conceivable.

[0068] In a preferred embodiment, the layer and a sensor provided in the layer are produced using one or more of the following production steps: 3D printed sensor structures cast or overcoated with insulating / protective material (e.g., rubber, resin, PVD / CVD, sol-gel, sprayed ceramic). Multi-material 3D printing on a rotating spool, alternating application of sensor material + insulating / protective material, CAD-controlled, layer-by-layer build-up. Photolithographic masking → deposition of sensor structure (e.g., via PVD / CVD, electroplating, chemical) → overcoating with insulating / protective layer. Possibly an additional protective layer against wear.

[0069] Suitable materials for the deposition of force measuring sensors via 3D printing or PVD / CVD are Piezoelectric ceramics, e.g. PZT, ZnO, AIN, alloys e.g., PdCr, CuNi (see literature) Amorphous DLC layers Suitable materials for the deposition of force measuring sensors by 3D printing or PVD / CVD Any standard thermocouple combination, e.g. type R: PtRh vs. Pt.

[0070] In a preferred embodiment, the layer is a layer produced in a single layer application. In a preferred embodiment, the measuring roller according to the invention has several layers produced in a single layer application, wherein, according to the invention, the sensor is arranged in one or more of the layers.

[0071] A "layer application" as described here comprises the application of material by means of which a layer, particularly of metal, can be applied initially point by point, line by line, or column by column and / or in a grid pattern to form a three-dimensional object in the form of one or more layers. During layer application, the layer currently being applied can be firmly bonded to an underlying layer or to the base material, provided that the layer is the first to be applied to the base material. The material application can be carried out layer by layer, computer-controlled, from one or more liquid or solid materials according to predefined dimensions and shapes. Physical or chemical hardening or melting processes can take place during the material application. A closed, essentially smooth surface can be created by means of layer application. The layer application can consist of a single layer.A single layer can be created by applying it once in a dot-by-dot, line-by-line, column-by-column, and / or grid pattern. In such a setup, no further layer is applied dot-by-dot, line-by-line, column-by-column, and / or grid pattern to a first layer that has already been created. In a preferred embodiment, however, the layer structure consists of several layers, which are preferably produced sequentially.

[0072] Furthermore, embodiments are conceivable in which the layer in which the force sensor is arranged is formed by several "layers," which, for conceptual differentiation, are referred to as sublayers. The respective sublayer can be created by applying it point by point, line by line, column by column, and / or in a grid pattern.

[0073] The term "pointwise" refers to the application of a layer or part of a layer in a single operation that does not involve any relative movement along the circumferential surface of the base body. The term "pointwise" does not imply any limitation on the size of the layer or part of the layer applied in this operation. "Pointwise" can also refer to the application of a large-area layer or part of a layer, as long as this operation can be carried out without any relative movement along the circumferential surface of the base body.

[0074] In a preferred embodiment, the layer application is carried out by means of a printing process using a 3D printer, laser beam melting (LBM), electron beam melting (EBM), laser powder deposition welding, wire-fed arc welding, thermal spraying, cladding, wire laser cladding, a powder bed process, in particular preferably the so-called "Selective Laser Sintering" (SLS) or the so-called "Selective Laser Melting" (SLM), laser metal deposition (LMD), extreme high-speed laser cladding (EHLA) and / or brazing.

[0075] This enables layer-by-layer application using additive manufacturing based on 3D models. If examples of layer-by-layer manufacturing are given, this additive manufacturing based on 3D models includes... a free jet binder application, a material application with directed energy input, a material extrusion, a free jet material application, a powder bed-based melting, a layer lamination, a bath-based photopolymerization and combinations of the aforementioned processes.

[0076] The aforementioned methods offer the advantage that material for layer application can be moved across the base body using linear axes or a robot. A material mix or essentially a pure material can be used. Melting is possible. In particular, a laser or electron beam can be used to create a melt of the supplied material, which is then applied to the base body or to layers already present above it. The material for layer application can be conveyed as a powder with a protective gas stream or by wire feed into the area where a material melt is generated. In particular, these methods can be used to implement a joining principle, especially fusion welding. This allows for a material bond.

[0077] In a preferred embodiment, the layer application process as described can be distinguished in particular by the fact that the methods mentioned in the description are used as 3D printing processes by means of control with 3D data in appropriately designed systems.

[0078] In a preferred embodiment, the first layer, or, if only a single layer is present, the single layer of the coating, is connected to the substrate, thus enabling a stable bond between the substrate and the coating. This bond can be achieved through one or a combination of the following mechanisms: mechanical interlocking at the molecular level, adhesion, diffusion, surface energy, and / or electrostatic forces. Welding can also be used to create a stable joint between the coating, in this case, the first layer on top of the substrate.

[0079] In a preferred embodiment, at least some of the layers (if the coating has multiple layers) of the coating are connected to one another, in particular welded, so that a stable connection of the coating itself is also possible. This prevents delamination in the event of a thermally induced change in the geometry of the measuring rollers.

[0080] In a preferred embodiment, the coating comprises at least one weldable metal, at least one weldable alloy, and / or ceramic reinforcing particles. By selecting a suitable material for the coating, the requirements for the measuring roller can be met and / or good thermal stability can be achieved while maintaining good manufacturability. Metals with high strength and toughness are particularly preferred. Iron, cobalt, nickel, chromium, molybdenum, vanadium, and their alloys are particularly preferred, for example, a chromium-molybdenum alloy (CrMo), such as 42CrMo4, or a chromium-molybdenum-vanadium alloy (CrMoVa), such as 86CrMoV7, or, for example, a tungsten-nickel-chromium alloy (WCNiCr).

[0081] In a preferred embodiment, the layer application has layers of different composition on top of each other, so that different requirements for the layers with regard to their position on the base body can be taken into account.

[0082] In a preferred embodiment, the layers of a multilayer structure are produced in the same way. However, embodiments are also conceivable in which the layers of a multilayer structure are produced by different manufacturing methods, or in which a group of first layers are produced by a first manufacturing process and a group of second layers by a second manufacturing process. Such an approach is particularly advantageous if the layers are of different types, for example, if they are made of different materials, and one manufacturing process is particularly well suited for producing a first layer, while another manufacturing process is particularly well suited for producing a second layer that differs from the first.For example, it is conceivable to apply a layer in a first manufacturing process whose material corresponds to or is at least similar to that of the base body, for example, metallic, while a protective layer, such as a plastic or rubber layer, is applied as a further layer in another manufacturing process. It is also conceivable to apply a protective layer of tungsten carbide as the outermost layer.

[0083] In a preferred embodiment, in embodiments where the layer structure comprises only one layer, the single layer of the layer structure is made of a metallic material or a ceramic material. In a preferred embodiment, in embodiments where the layer structure comprises multiple layers, the layer of the layer structure that is closest to the base body (the bottom layer; the innermost layer) is made of a metallic material or a ceramic material.

[0084] In a preferred embodiment, in embodiments where the layer structure comprises only one layer, the single layer of the layer structure, or in embodiments where the layer structure comprises multiple layers, at least the layer of the layer structure closest to the base body (the bottom layer; the innermost layer), is matched to the material properties of the base body, in particular with regard to the coefficient of thermal expansion and / or strength. It is particularly preferred that, in embodiments where the layer structure comprises only one layer, the single layer of the layer structure, or in embodiments where the layer structure comprises multiple layers, at least the layer of the layer structure closest to the base body (the bottom layer; the innermost layer), the material is selected such that the coefficient of thermal expansion of the material, measured in 10⁻⁶ / K, is not less than 0.5 times, in particular preferably not less than 0.6 times, in particular preferably not less than 0.7 times, in particular preferably not less than 0.8 times, in particular preferably not less than 0.9 times, the coefficient of thermal expansion of the material of the base body, measured in 10⁻⁶ / K (if the base body is made of steel, the coefficient of thermal expansion measured in 10⁻⁶ / K is approximately in the range of 11 to 13 10⁻⁶ / K; the material of the sole orIn a preferred embodiment, the lowest / innermost layer should then have a coefficient of thermal expansion measured in 10⁻⁶ / K that is not less than 5.5 10⁻⁶ / K (0.5 times 11), and / or the material should be selected such that the coefficient of thermal expansion of the material measured in 10⁻⁶ / K is not less than 9 10⁻⁶ / K, preferably not less than 10 10⁻⁶ / K, and / or the material should be selected such that the tensile strength of the material measured in MPa is not less than 0.7 times, particularly preferably not less than 0.8 times, particularly preferably not less than 0.9 times the tensile strength of the material of the base body measured in MPa (if the base body is made of steel, the tensile strength measured in MPa is approximately in the range of 700 to 1100 MPa; the material of the single orIn a preferred embodiment, the lowest / innermost layer should then have a tensile strength measured in MPa that is not less than 490 MPa (0.7 times 700), and / or the material should be selected such that the tensile strength of the material measured in MPa is not less than 600 MPa, preferably not less than 650 MPa.

[0085] The aforementioned material properties refer to the layer in its applied state. By adhering to the design rules for the layer material as applied to the substrate, it can be ensured that the layer – particularly in the area of ​​the recess – does not become brittle or flake off.

[0086] Embodiments are conceivable in which the layers of a multilayer structure, according to a preferred embodiment, have different extents. For example, it is conceivable that a base body has a depression around the recess, which is filled by applying a first layer or a first group of layers. This first layer or this first group of layers then has the geometric shape of the depression. Building upon this first layer or this first group of layers, the structure can then have a second layer or a second group of layers that have a greater extent than the depression, for example, covering the entire remaining circumferential surface of the base body, including the circumferential surface of the depression filled with the first layer / the first group of layers.

[0087] In a preferred embodiment, the layer applied to the base body can be made of the same material as the base body. It is possible to provide that the material changes in the thickness of the layer applied to meet different requirements.

[0088] The film or mat can be a printed film.

[0089] The film and / or mat can function as force sensors, comprising a matrix of piezoresistive-based sensors that can be incorporated as thin mats into a casing.

[0090] When a roller is wrapped with a pressure-sensitive film, the pressure distribution on its surface can be measured. As a belt runs over the roller, a pressure distribution is registered in the film. If the belt is flat, the pressure distribution will be evenly distributed. If the belt is uneven, higher pressures will be measured in shorter fibers and lower pressures in longer fibers.

[0091] The pressure-sensitive film may be located beneath another layer, in particular a protective layer, which may be made of, for example, rubber, ceramic, steel or polyurethane.

[0092] The film or mat can also be produced by placing electrodes or similar devices on the underside of the layer (on the side facing the base material). Each electrode forms a capacitance with the tape-like material running over the measuring roller. The layer material can serve as a dielectric, for example, a rubber layer. The capacitance increases with increasing pressure because the distance between the electrode and the tape decreases. The coating can also consist of another flexible insulating or dielectric layer, for example, a ceramic.

[0093] In a method to be carried out with the measuring roller according to the invention, the measured values ​​of the sensors can be pre-processed, compressed and transported in the same or a similar way as in the transmission of images.

[0094] Data transmission from the measuring roller to a stationary evaluation unit outside the measuring roller can be achieved using electromagnetic waves. An optical rotary transmitter or a radio link can be used.

[0095] Calibration of the measuring roller can be performed at the factory by rolling it on a flat surface. When installed, this could be temporarily achieved using a counter roller. During operation, the total belt tension can be measured via pressure sensors in the bearing blocks to correct the matrix readings.

[0096] The layer does not necessarily have to be in the form of a film or mat. It can also be a layer applied to the base body of the measuring roller, created using 3D printing, photochemical processes, spraying, or ink printing. For example, layers deposited from the gas phase (PVD; DLC) are conceivable.

[0097] A temperature sensor can also be arranged within the layer. The inclusion of a temperature sensor enables temperature compensation. In a preferred embodiment, it is conceivable to determine and transmit the temperature profile with the same resolution as the pressure distribution.

[0098] In a preferred embodiment, the measuring roller according to the invention is used to determine the flatness of the strip-shaped material guided over the measuring roller. Additionally or alternatively, the transverse arc or the strip's path can be determined using the measuring roller according to the invention. Likewise, strip cracks at the strip edge or defects in the strip can be detected. Furthermore, defects in the strip topography, such as scale, scale, or holes, can be detected. If a counter roller is used, thickness variations can also be derived.

[0099] One property of a ribbon-shaped material guided over the measuring roller can be, in particular, the flatness of the ribbon-shaped material.

[0100] The strip-shaped material can be, in particular, a metal strip, which can be guided over the measuring roller, especially during cold or hot rolling of the metal strip. The measuring roller can also be arranged in a downstream processing line, such as a finishing mill (trim mill), strip annealing line, galvanizing line, or stretch-bending-straightening line.

[0101] The invention can be used in flatness measurement and topography measurement, for example in strip rolling, especially of steel strip, but also in other industries such as aluminium production, the production of non-ferrous metals, paper or plastics.

[0102] The invention is explained below with reference to drawings that merely illustrate exemplary embodiments of the invention. These drawings show: Fig. 1 a schematic, perspective view of the system; Fig. 2 a schematic, sectioned perspective view of an edge layer of the measuring roller in unfolded representation; Fig. 3 a schematic representation of one way to combine nx128 sensor signals using a channel module; Fig. 4 a schematic representation of a grouping of M channel modules using a group module and forwarding of the sensor signals to an evaluation module outside the measuring roller; Fig. 5 a schematic, perspective view of a possible realization of the sensor installation; Fig. 6 a schematic representation of one way to combine 100 analog sensor signals using a channel module; Fig. 7 a schematic, perspective view of a possible realization of additively manufactured sensors; Fig. 8a), b), c) a schematic, perspective view of a possible realization of a clamping device for sensors in a single layer, with Fig. 8a ) Section through the measuring roller, Fig. 8b ) 3D view and Fig. 8c ) Section showing sensors embedded in a compressible layer and Fig. 9 a schematic, perspective view of a measuring roller.

[0103] The steel belt 1 runs around a roller body 3 with a wrap angle, which is equipped with a pressure-sensitive coating 2. Power transmission and signal transmission (optical or radio) are preferably implemented in one or both bearings. A bearing journal 4 is provided on the roller body 3. Force measurements can be implemented in the bearings to detect the total belt tension (for dynamic adjustment of the pressure distribution, compensation, or disturbances).

[0104] Fig. 2 This section contains an example of a possible implementation of a pressure-sensitive layer. Part of layer 2 can consist of non-conductive rubber or ceramic 2.1 and is in direct contact with the tape 1. It acts as a dielectric between an electrode matrix 2.2 and the tape. The capacitance from each electrode to the tape, or from the electrode in question to the surrounding electrodes, can be measured. The capacitance changes with increasing pressure. The pressure distribution can be determined from the individual capacitances. The electrodes are embedded in a support layer 2.3. This layer can be implemented as a flexible printed circuit board (PCB). The PCB can contain all the electronics for preprocessing and for combining the individual signals using shift registers / multiplexers. Alternatively, the entire layer can be additively manufactured. The measurement principle is not necessarily based on capacitance measurements.

[0105] For example, the sensor shown at this link can be used as a sensor produced by SMD assembly: https: / / www.digikey.de / product-detail / de / honeywell-sensing-and-productivitysolutions / FMAMSDXX025WCSC3 / 480-FMAMSDXX025WCSC3CT-ND / 12088280

[0106] Such sensors can be factory calibrated and internally temperature-compensated. The measurement signal is provided via I2C or SPI bus. For example, the I2C bus can accommodate multiple masters and up to 128 slaves. This allows 128 sensors to be grouped together and connected to a distribution board, referred to here as a channel module. The supply voltage can also be provided from there. Fig. 3 The aggregated sensor signals are forwarded to a mainboard, which is also located on the reel and is referred to here as the group module ( Fig. 4 The transfer from the group module on the role to the evaluation module outside the role can be done via radio connection or optically.

[0107] For a measuring range of 1270 mm across the width, a row with 128 sensors would be required, assuming a sensor spacing of 10 mm. Corresponding channel modules would need to be installed for each N row across the roll's circumference. For a roll circumference of 1 m, with a sensor spacing of 10 mm in the circumferential direction, M = 100 / N channel modules would need to be installed. These would be received, processed, and forwarded by the group module. In this example, the measuring roll has 12,800 individual sensors. The channel modules and the group module can be located on the ends of the roll. The group module does not necessarily need to receive all 100 channels mentioned in this example simultaneously, but only needs to process the sensor rows currently being monitored at any given time. This can be achieved through flexible switching (similar to a multiplexer). The same applies to the channel modules.If the belt only covers part of the measuring range in the width direction, reducing the number of sensor signals transmitted is advisable. Each scan provides visual information about the pressure distribution between the material being measured and the roller. This information is updated with each scan step during the evaluation process, allowing the desired quality parameters for belt flatness to be determined.

[0108] Fig. 5 Figure 1 shows the schematic setup of an implementation using SMD pressure sensors. An insulating layer is applied to the roller body, and the conductor connections with the pads for contacting the pressure sensors are located in or on this layer. The pressure sensors are located on the insulating layer, and their pins are connected to the pads of the conductor tracks. The pressure sensors are surrounded by a compressible layer; only the pressure spheres are located in the elastic outer sheath, preferably made of steel. A large portion of the compressive force exerted by the belt on the outer sheath acts directly on the force sensors. Pre-tensioning of the sensors is not required.

[0109] In a preferred embodiment, the sensor is applied using additive technology, although alternatively, it is also possible to equip it with finished passive sensors.

[0110] In this variant, pressure sensors with analog outputs are either integrated or applied using an additive manufacturing process. Each sensor is connected via a horizontal and a vertical electrical conductor, creating a matrix structure. For a square matrix with 10x10 sensors, 20 lines need to be evaluated. Two multiplexers for the horizontal and vertical lines allow the individual measured values ​​to be read, amplified, and analog-to-digital converted. This electronics can be placed either on the end face of the roller or, to avoid additional wiring between the sensors, on top of the sensor. An additional layer beneath the sensors is also conceivable. The individual channels are connected to group modules (such as...) via a bus (e.g., I2C or SPC). Fig. 4 ) transferred. The group modules can be placed on the front of the roll or inside the roll.

[0111] Fig. 7 This shows the schematic setup of an implementation using analog pressure sensors. These can be either pre-assembled or manufactured using additive manufacturing.

[0112] Force sensors can be derived from resistors, capacitors, inductors, voltage elements, piezo sensors, Hall circuits, or other semiconductors.

[0113] In a preferred embodiment, the sensor is implemented as an active sensor with an analog output. Such a sensor is described in more detail, for example, at this link: https: / / www.digikey.de / product-detail / de / honeywell-sensing-and-productivitysolutions / FSS020WNSB / 480-6894-ND / 6605549

[0114] Alternatively, active sensors with analog outputs can also be housed in this layer. The signal routing corresponds to the matrix structure ( Fig. 7 ), the embedding can be done according to Fig. 5 take place.

[0115] In a preferred embodiment, an additively manufactured or discretely integrated sensor is clamped, namely embedded in a compressible layer.

[0116] Fig. 5 shows a possible implementation of sensor installation with 101 Section of roller body 102 Insulating layer 103 Conductor tracks 104 Pressure sensors 105 Compressible layer 106 Elastic outer sheath (steel).

[0117] Fig. 7 shows a possible realization of additively manufactured sensors with 201 Section of roller body 202 Insulating layer 203 Conductor tracks 204 Pressure sensors 205 Compressible layer 206 Elastic outer sheath 207 Upper electrode 208 Piezoresistive or other pressure-sensitive layer 209 Lower electrode.

[0118] Fig. 8 This shows a possible realization of additively manufactured sensors with a possible realization of a clamping device for sensors in a single layer. 301 Cutout from roller body 302 Pressure plates 303 Compressible layer with pressure sensors and interconnection 304 Elastic outer shell 305 Tension screws.

[0119] Fig. 9 Figure 3 shows a measuring roller 3 for determining a property of a strip-shaped material 1 guided over the circumferential surface of the measuring roller 3. The measuring roller 3 has a measuring roller body extending along a longitudinal axis A, which has bearing pins 4 at its ends for rotatable mounting of the measuring roller body and forms the circumferential surface. The measuring roller has a plurality of sensors 5 arranged side by side below the circumferential surface. A segment 6 of the measuring roller body is defined by a region 7 of the circumferential surface, two radial planes 8, 9 that intersect in the longitudinal axis A of the measuring roller body and each extend in a radial direction and intersect the circumferential surface, and two planes perpendicular to the longitudinal axis (in Fig. 9(not highlighted), which intersect the circumferential surface, limited. The area of ​​the circumferential surface rolled out into a plane has a size of x mm. 2 In the segment, a number y sensors 5 are arranged, wherein y>2x / 100.

Claims

1. Measuring roller for determining a property of a strip-shaped material, in particular metal strip (1), guided over the circumferential surface of the measuring roller, with - a measuring roller body (3) extending along a longitudinal axis (A), the measuring roller body (3) having bearing journals (4) or bushings at the ends for rotatably supporting the measuring roller body (3) and forming the circumferential surface, and - a plurality of sensors (5) arranged next to each other below the circumferential surface, wherein the measuring roller body (3) comprises a segment (6) which • is defined by a region (7) of the circumferential surface, • two radial planes (8, 9) that intersect in the longitudinal axis (A) of the measuring roller body (3) and each extend in a radial direction and intersect the circumferential surface, and • two planes perpendicular to the longitudinal axis (A) that intersect the circumferential surface wherein the area of the region (7) of the circumferential surface rolled out into a plane has a size of x mm2, wherein a number y of sensors (5) are arranged in the segment (6), wherein y is at least greater than or equal to 3, characterized by y > 2 x / 100 .

2. Measuring roller according to claim 1, characterized in that a number y of sensors (5) are arranged in the segment (6), wherein y > 2 x / 10 .

3. Measuring roller according to claim 1 or 2, characterized in that the sensors (5) are arranged adjacent to one another in the segment (6) in the circumferential direction and / or in a direction parallel to the longitudinal axis (A) of the measuring roller body (3).

4. Measuring roller according to one of claims 1 to 3, characterized in that the measuring roller body (3) has a main body and a layer (2) arranged on the main body, and in that the sensors (5) arranged in the segment (6) are arranged in the layer.

5. Measuring roller according to claim 4, characterized in that the respective sensor (5) arranged in the segment (6) - is embedded in the material forming the layer (2), or - is arranged in a recess in the layer (2), wherein the recess is bounded by the material of the layer (2) in at least the majority of the circumferential directions as seen from the sensor (5) and / or is bounded in the radial direction outwards by the material of the layer as seen from the sensor (5).

6. Measuring roller according to one of claims 4 or 5, characterized in that the layer (2) is formed by a film or mat which wraps around the outer circumference of the main body over at least 180°.

7. Measuring roller according to one of claims 1 to 6, characterized in that at least the majority of the sensors (5) arranged in the segment (6) are sensors of the same sensor type.

8. Measuring roller according to one of claims 1 to 7, characterized in that more than 75% of the sensors (6) present in the segment (6) are arranged according to a grid and the distances between adjacent sensors within the grid are the same.

9. Measuring roller according to claim 8, characterized in that the grid is formed by intersecting lines at whose intersections the sensors (5) are arranged, wherein the lines of the grid run either in the circumferential direction or parallel to the longitudinal direction of the main body.

10. Measuring roller according to one of claims 1 to 7, characterized in that the main body of the measuring roller has a first end with a bearing journal and a second end with a bearing journal (4), and the bearing journals (4) of the main body are rotatably mounted in stands of the measuring roller, or the first end is equipped with a bushing and the second end is equipped with a bushing, and bearing journals of stands of the measuring roller engage in the bushings, so that the measuring roller is rotatably mounted in the stands of the measuring roller.

11. Use of a measuring roller according to one of claims 1 to 10 for determining the flatness of the strip-shaped material guided over the circumferential surface of the measuring roller and / or for determining surface defects and / or the temperature distribution and / or the moisture and / or internal defects and / or the internal stress distribution in the surface of the strip-shaped material guided over the circumferential surface of the measuring roller.