Method and device for monitoring a roller for a roller press and roller press system

Abstract

The invention relates to a method for monitoring a three-dimensional structure of a surface (1) of a roller (2) for a roller press (3) for crushing, briquetting or compacting, with a monitoring device (4) that determines the surface structure (1) of the roller (2) by distance measurements. The method is characterized in that, during the distance measurements, at least one three-dimensional reference means (5) is attached to the surface of the roller within the working width (b) of the roller (2).

Description

The invention relates to a method for monitoring a three-dimensional structure of a surface of a roller for a roller press, for example a high-pressure roller press, for crushing, carburizing or compacting material, with a monitoring device which determines the surface structure of the roller (three-dimensionally) by distance measurements.The invention also relates to a device for monitoring a three-dimensional structure of a surface of a roller for a roller press, with which such a method is or can be carried out, and to a roller press installation with a roller press, the roller or rollers of which are or are monitored with such a method.A roller press, for example a high-pressure roller press, for comminution of material is also referred to as a material bed roller mill. In the case of material bed roll mills, the individual particles of the feed material are not broken between the surfaces of the two rolls as in the case of a crusher, but rather they are pressed under high pressure in a material bed or material bed and are thus comminuted in a highly efficient manner. The material is in particular a highly abrasive material, for example ore, cement clinker, slag or ceramic bases.The roller press can also be designed for compacting or briculating material, for example for compacting fertiliser. In a compacting press, the material is compacted in the nip between rollers with a structured surface at high pressure to form a continuous strand of material, which is referred to as a slug. In a bricette press, the material is compacted in the roll gap by the bricette tools arranged on the roll surfaces (with bricette troughs to form briquettes or a length of briquettes from a plurality of briquettes). The briquettes are also made, for example, for the production of briquettes of directly reduced iron (DRI) or for the production of hot-colored iron (HBI)The roller press has two rollers driven in rotation (in the opposite direction), the so-called press rollers or work rollers, between which a roller gap is formed. The nip width of the nip is variable during operation of the press. For this purpose, one of the press rollers can be designed as a fixed roller and the other as a loose roller, wherein the loose roller can be adjusted against the fixed roller by force generating means. The outside diameter of the rollers decreases as a result of wear during production operation.The press rollers can each have, for example, a roller core and a bandage arranged on the roller core, the outer diameter of which decreases during operation as a result of wear. In such an embodiment, the roller surfaces subject to wear are consequently formed by the bandages. Wear protection elements can be incorporated into the surface. The wear protection elements can be designed pin-shaped as so-called stubs for a comminution roller or plate-shaped as so-called tiles. In addition, the roller can have special edge protection elements.Overall, the rollers of the roller press can have different surface structures. In addition to the briquettes of a briquettesing roll, these also include different compacting structures of a compacting roll. Also detected are comminution rollers which have special wear layers with wear protection elements, such as pin-shaped or plate-shaped elements. All of these different three-dimensional surface structures of a roller for a roller press are encompassed by the present invention.It is known from practice to monitor the condition of the surfaces of the rolls of a roll press in order to check the wear condition and to derive therefrom corresponding measures in order to ensure the smooth operation of the press and to avoid malfunctions or interruptions in operation. In the case of a comminution roller, it is important to monitor the presence and the state of the wear protection elements, in the case of a briquettes roller the state of the corresponding briquettes troughs and in the case of a compacting roller the state of the compacting structures.WO 2022 / 023869 A1 discloses a wear detection device for detecting the wear of a roller. This includes a sensing sensor connected to a controller which senses a portion of the surface to determine possible wear or total lack of wear elements of the roller surface. The apparatus also includes an additional alignment sensor which serves to sense a reference mark on the roller to determine the relative position of the scan sensor to the roller. This reference mark is formed as a depression or as a projection on the surface of the roller.Furthermore, WO 2014 / 068453 A1 discloses a device for monitoring the surface of a roller of a roller crusher, in which a light sensor is arranged in such a way that it projects a line onto the surface of the roller. An additional image capturing device captures an image of a portion of that surface that also includes a portion of the projected line. By means of a processor unit, the captured image is processed to obtain information about the surface of the roller. In addition, a plurality of images are recorded at different rotational positions of the roller in order to be able to represent the entire roller as much as possible.Furthermore, WO 2008 / 090016 A1 describes a roller mill having two counter-driven paint rollers which are equipped with a multiplicity of profile bodies. With the aid of a monitoring device, the presence or absence of these profile bodies is determined in order to prevent downtime. For this purpose, a sensor is used which checks the roller mill during the grinding operation and counts the detected profile bodies. This sensor can be moved parallel to the axis of the grinding roller.A roller mill with two rotating rollers is also known from DE 20 2015 106 156 U1, wherein a roller to be measured is assigned a sensor unit which measures the distance to the grinding surface of this roller during operation of the roller mill in order to be able to draw conclusions about the wear state of the rollers by means of an evaluation unit.WO 2023 / 104294 A1 describes a roller machine for crushing or compacting feed material with at least one roller, wherein the roller has a plurality of impact elements and / or edge protection elements on the outer surface. On this roller machine a radar unit is provided which emits a radar beam onto the outer surface of the roller which is reflected on said elements, whereby the condition of these elements can be monitored.Furthermore, DE 10 2022 134 175 A1 discloses a device for measuring the wear of a roller of a high-pressure roller press. The wear is determined from the quotient of the surface speed and the angular speed of the roller, from which the circumference and the diameter of the roller can be calculated. For this purpose, a movable sensor for measuring the surface speed is used over the length of the roller, as well as an angular velocity meter cooperating with a shaft of the roller. The sensor can be a laser sensor which operates according to the differential Doppler method and the angular velocity meter can be designed as a Hall effect sensor which is excited via a magnet.Finally, DE 21 2021 000 130 U1 discloses a device for detecting defects on the roller surface of a roller press. This uses a 3D scanner for acquiring three-dimensional point cloud data of the roller surface. By determining the change in the height values, it is possible to draw conclusions about the wear of the roller.Starting from the prior art known in the art, the invention is based on the technical problem, in connection with (high-pressure) roller presses which are intended for comminution, compaction or briquettes of material, of creating a method and a device which, with simple means, enables reliable monitoring of the three-dimensional structure of the surface of a roller over the entire width or working width of the roller. The method and the device should be usable in particular flexibly and with little installation and installation complexityTo achieve this object, the invention teaches, in a method of the generic type for monitoring the surface structure of a roller, that during the distance measurements at least one three-dimensional reference means is attached to the surface of the roller within the working width of the roller.The invention is based on the finding that the monitoring of a three-dimensional surface structure of a roller can be carried out simply with the aid of distance measurements. On the basis of this, the invention proposes the use of at least one three-dimensional reference means which is attached (for example temporarily) to the roller surface within the working width of the roller and is likewise measured during the measurement within the working width using the monitoring device. This three-dimensional reference means serves during the distance measurements as a reference or as a reference point for the monitoring direction and simplifies and optimizes the evaluation. Since the reference means, like the surface structure of the roller, itself also has a characteristic three-dimensional structure, it can be detected with the (same) monitoring device in an excellent manner and taken into account during the evaluation. The use of such a reference means enables in particular an optimum normalization or scaling of the measurement data or of the 3D image data set, e.g. also when using a mobile measurement arrangement. In addition, the reference means can on the one hand make it possible to monitor irregular surface structures and on the other hand also to measure relatively large widths of a roller. This will be discussed in more detail in the further course of the description. It is also particularly advantageous that the reference means is detected directly together with the entire surface structure by the monitoring device, e.g. its measuring device, and thus no additional device is necessary which recognizes and evaluates the reference marking or a reference marking.It is particularly advantageous that or if the three-dimensional geometry of the reference means, i.e. the geometry in the X, Y and Z directions, is stored as a three-dimensional reference data set (e.g. in the monitoring device). During the measurement of the roller surface, not only is a measurement of the surface structure to be examined carried out, but in particular also a measurement of this reference means takes place, so that a so-called scaling measurement data set is generated with the measurement of the reference means. During the evaluation, the 3D image data set representing the surface structure of the roller is then scaled taking into account this recorded scaling measurement data set and taking into account the stored reference data set. The scaling measurement data set is the data set which is generated during the actual measurement of the reference means, so that the scaling can be carried out on the one hand on the basis of the stored reference data set and the scaling measurement data set generated by measurement on the other hand, for example by generating scaling factors with which the 3D image data set representing the surface structure of the roller is scaled. These measures have the advantage that a defined positioning of the monitoring device relative to the roller surface is not important during the measurements or during the monitoring of the roller surface. It is therefore not important that the monitoring device or the distance and / or the angle of the source and the sensor relative to the roller are the same during each measurement. By knowing the geometry of the reference means in each image data set, all angular and size distortions which arise due to different alignments or distances of the measuring device to the roller can be calculated, so that a dimensionally and angularly accurate image of the entire roller surface is produced. The reference means consequently serves primarily for the unique scaling and consequently normalization of the measurement data, which are generally carried out by measurements with a time interval in different positions of the source and / or of the sensor. In addition, the reference means or the detection of the known geometry of the reference means also enables the measurement of roller surfaces with a greater width, which is, for example, greater than the measurement width of the monitoring device. This will be discussed in more detail below.The monitoring device can be a known measurement system which is suitable for generating a three-dimensional image of a structured surface with the aid of distance measurements. In this case, the monitoring device can carry out the measurement, process, evaluate and (directly) process the data obtained from the measurement and generate the 3D image data set and / or a three-dimensional image in the sense of an evaluation unit. Alternatively, a separate evaluation unit can also be used, which communicates with the monitoring device and further processes the measured values. In addition, a computer can be connected to the monitoring device and / or the evaluation unit or such a computer can be a component of the monitoring device. Consequently, at least the described sensor device is preferably part of the monitoring device positioned on the roller. Optionally, the or an evaluation unit can also be integrated into the monitoring device, wherein the reference data set required for the scaling is stored, for example, in the (internal) evaluation unit in the monitoring device. If the evaluation unit is not a component of the (mobile) monitoring device, but rather is implemented as an external evaluation unit, for example, by a separate computer, the reference data set is preferably not stored in the monitoring device, but in the separate evaluation unit. The evaluation unit can be realized by a separate computer and consequently separate hardware.However, the invention also includes embodiments in which the evaluation unit is implemented on a separate (external) server or in a cloud, so that the evaluation unit is then implemented as an evaluation algorithm or job in a cloud, for example, and the reference data set is / are also stored on a separate server or in a cloud, for example.Preferably, the at least one reference means is releasably attached to the roller, e.g. adhesively or magnetically. Thus, the reference means for carrying out the distance measurements can be reversibly attached to the roller surface by means of the monitoring device. Before, for example, the roller is reinserted in the production plant after monitoring the surface, the releasably attached reference means is removed from the surface of the roller. In order to make this possible, the reference means can be adhesively attached, i.e. it can be adhesively bonded, for example as an adhesive reference stick or by means of an additional adhesive which can be released again, for example, by heating. Alternatively, the reference means can be designed magnetically and can be attached to the metallic roller via a magnetic connection. Alternatively, the reference means can also be fastened to the roller surface by clamping (e.g. between the wear elements, e.g. stubs) or by clipping (e.g. onto the wear elements, e.g. stubs). This allows rapid and flexible mounting and dismantling of the reference means on the roller surface. This is important because the reference means is preferably attached to the roll surface (namely within the working width) only during the monitoring process and is removed during the press operation.This is because the method for monitoring the surface structure is preferably carried out not during the production operation or pressing operation of the roller or press, but during an interruption of the operation, but particularly preferably in a state in which the roller is installed in a press. Compared to the prior art, this has the advantage that the performance of such measurements is not impaired by the conditions during the ongoing production operation. The monitoring can thus be carried out particularly simply and with high accuracy. It is advantageous if measurement is made during the maintenance operation or during another shutdown of the production. Nevertheless, the roll can be monitored while it is installed in the press by mounting the reference means on the roll surface and positioning the monitoring device in the region of the roll to be measured. Alternatively, the roller can also be removed from the press for carrying out the distance measurement and measured, for example, in a special test stand.In a preferred embodiment, the roller rotates during the monitoring of the three-dimensional surface structure and preferably at a constant rotational speed. The monitoring device can thus perform distance measurements over the entire circumference of the roller-even with a limited measuring range-and thereby determine the surface structure of the entire roller, i.e. over the entire circumference of the roller. It is appropriate that the roller rotates at a constant speed in order to avoid any errors, such as distorted representations of the surface. If uniform structures are concerned on the roller surface, however, varying speeds of rotation can be accepted. An uneven mapping of the actually regular structure resulting from varying speeds can be corrected by the evaluation unit with knowledge of the regular structure. In the measurement of uneven surface structures, on the other hand, it is advantageous for obtaining troublefree results that the roller rotates at a constant speed during the monitoring of the surface structure.By means of the distance measurements, a complete three-dimensional information (as a 3D image data set) and optionally also a three-dimensional image (as a graphic representation or visualization) of the surface structure of the roller can be created over the circumference and over at least a part of the working width of the roller. The roller surface can be partially or completely detected and, for example, depicted graphically. The recorded data and / or the representation of the surface in 3D allow reliable conclusions to be drawn about the wear of the surface. This is because, on the basis of the three-dimensional information and / or representation, differences in the height of the surface and thus differences in the wear of the roller can be seen. The three-dimensional data set and / or the three-dimensional image of the surface are either generated by the monitoring device (with an integrated evaluation unit) and optionally output or by a separate evaluation unit, which communicates with the monitoring device and receives from the latter the (raw) data of the distance measurements. The graphical representation of the surface can alternatively take place on a computer connected to the monitoring device.The monitoring device preferably has at least one sensor device, wherein the sensor device has a source, e.g. a radiation source, which generates a measurement beam, and wherein the sensor device has a detector or sensor or receiver (receiving element) which detects the measurement beam, e.g. light beam, generated by the source and reflected by the surface of the roller.The measurement beam is preferably a beam of electromagnetic radiation projected onto the roller surface, for example a light beam which can be visible light. Alternatively, however, electromagnetic radiation outside the visible spectrum, e.g. IR or UV radiation, is also detected. The sensor device is configured to receive the measurement radiation, e.g. the light. By detecting the rays reflected by the roller surface, the distance of the respective point to be measured on the surface can be determined, for example, by triangulation. This will be discussed in more detail below.In a particularly preferred embodiment, the source projects the measurement beam as a measurement line oriented along the roller width onto the roller surface, e.g. as a laser line, wherein preferably the length of the measurement line, e.g. of the laser line, extending along the roller width (e.g. in an X direction oriented parallel to the roller axis) defines the measurement width of the sensor device and / or of the monitoring device. The sensor device can consequently be designed as a line scanner, e.g. a laser line scanner, which preferably uses the laser triangulation principle for detecting the surface profiles on the roller surface. For this purpose, for example, a suitable optical system, for example a line optical system, can project a line, for example a laser line, onto the roller surface. The (diffusely) reflected light of this line, e.g. laser line, is imaged onto the detector / sensor of the sensor device, e.g. via a suitable optical system. In this case, the detector can enable a position-resolved measurement, for example as a sensor matrix, for example, so that the spatial position of the light reflected by the laser line (in the width direction) can be detected. The generation and measurement of such a measurement line, e.g. laser line, e.g. with a laser line scanner initially enables two-dimensional detection by detecting the distance information (e.g. as a Z axis oriented in the radial direction) over a width position along the measurement line (as an X axis). 3D recording or three-dimensional detection of the roller surface then takes place by the movement of the roller surface relative to the measuring or sensor device and consequently by the rotation of the roller, so that the roller surface moves along a Y axis (oriented in the circumferential direction or in the tangential direction) relative to the measuring device. A 3D point cloud is thus obtained from the stringing of the 2D profiles determined via the line detection (in the X direction).In a preferred embodiment of the invention, the distance measurements are carried out by triangulation, preferably by laser triangulation. Triangulation is a distance measurement by angle calculation in the sense of depth image acquisition. The measurement beam, e.g. laser beam, is projected onto the object to be measured, i.e. in the present invention onto the surface of the roller. The reflected light impinges on a receiver at a specific angle, depending on the distance to the surface or the object to be determined. The distance to the measurement object is calculated by the position of the reflected beam on the receiver or receiving element and the distance between the transmitter and the receiving element. Alternatively to a laser, other light sources can also be used, such as diodes. Alternatively, a "LIDAR system" can be used. "LIDAR" stands for "light detection and ranging" or "light harvesting, detection and ranging".It is particularly advantageous if the sensor device projects onto the roller surface-as described-a (strip-shaped) measurement line, e.g. laser line, with a length which defines the measurement width M of the measurement device and which extends along the width of the roller (i.e. parallel to its axis). This makes it possible for the roller surface to be measured (in a measurement process and thus an image data set) over a specific measurement width. The positioning of the monitoring device enables the measurement of the specific measurement range with the measurement width M.The monitoring device or its sensor device can have a measurement width M that is smaller than the working width b of the roller, wherein, in order to record the total working width of the roller, a plurality of distance measurements are carried out (one after the other) in each case over the circumference one after the other at different width positions of the roller, which record the at least one reference means. Thus, the measurement width of the monitoring device can be smaller than the working width of the roller. In practice, the rollers and in particular also the wear range or the working width are often wider than the measurement range of conventional measurement systems and thus of the monitoring device, which can only cover a specific width range of the roller with a predefined positioning of the measurement system. To record and monitor the entire working width of the roller, a plurality of distance measurements can be carried out over the working width of the roller, wherein the monitoring device is not traversed in this case, but is stationary during each recording. The monitoring device can accordingly successively carry out a plurality of distance measurements of the described type at different positions along the working width. The reference means located in each case on the surface of the roller is detected by the monitoring device for the orientation and determination of the position of the respective measurements. The three-dimensional reference means according to the invention is consequently of particular importance when it is intended to measure roller surfaces with a working width which is greater than the measurement width of the sensor device used. By means of the reference means, the measurement data obtained successively in different width positions can be "assembled" as it were to form an image or data record of the complete roller surface. The reference means according to the invention consequently makes it possible, even with known measuring devices having a limited measuring width of, for example, 10 cm to 50 cm, preferably 20 cm to 40 cm, to measure press rolls having customary roll widths which can also (significantly) be wider than the indicated measuring width. This is achieved with very simple means, for example by positioning or aligning the measuring device as a mobile sensor device in different positions, without a particularly high accuracy of the positioning of the measuring device being important in this case, since the measurement data is normalized or scaled on the roller surface via the reference means in the form of 3D image data sets. This is because, according to the invention, a plurality of 3D image data sets are generated one after the other in order to record relatively large working widths, wherein the plurality of distance measurements overlap in at least one overlap region in which the reference means is arranged. The plurality of 3D image data sets generated over the working width are combined and identically scaled taking into account the stored reference data set and the scaling data set recorded at the reference means. It is also important here that the three-dimensional structure of the reference means is known and stored, for example, in the monitoring device as a reference data set. During the measurement, not only the structures of the roller surface to be examined, but in particular also the reference means, are measured and a scaling data set is thus generated, which allows the successively obtained image data sets to be put together and an identical scaling during the evaluation.Consequently, in order to generate the three-dimensional image of the surface structure of the entire working width of the roller, a plurality of measurements overlapping in an area are preferably carried out, wherein the at least one reference means is attached in this overlap area. This serves to allow the entire working width of the roller to be subsequently displayed in a single three-dimensional view for evaluation. The reference means serves here-as described-for the orientation or normalization / scaling of the measurement data. Because the reference means is included in the overlap region during the overlapping recordings or measurements of the surface, doubly measured regions can be calculated, so that the entire 3D data set of the roller surface and thus the overall image of the roller results. In this case, the reference means additionally serves for the assignment of a plurality of measurements or measurement ranges of the surface in order to compile the images of the surface of the roller as an overall image or as an entire data set.In one embodiment, the monitoring device is fixed stationary during the monitoring of the three-dimensional surface structure, i.e. it is mounted stationary. Although it can be mobile, it is not moved during the measurement / data recording. Compared to a measuring device traversing e.g. a rail, the monitoring device according to the invention has the advantage that it does not move within the (working) width of the roller during the execution of the distance measurements. This increases the measurement accuracy and simplifies the measurement process. The monitoring device is thus operated stationary during each measurement. This means that a stationary positioning of the monitoring device takes place, which is not changed during the execution of the distance measurements with a rotating roller. Only for further distance measurements, for example one after the other over the working width of the roller, can the monitoring device be displaced.In an advantageous embodiment of the invention, the at least one three-dimensional reference means is designed in cross section as a step-shaped reference means, for example as a step-shaped pyramid, wherein the steps can each have a different height and / or width. The defined geometry of the reference means known to the system (i.e. the evaluation unit) is detected by the monitoring device, i.e. distance measurements are also carried out on the reference means, which are taken into account in the evaluation and used for scaling / normalizing the measurement data. However, the present invention is not limited to the described geometry and generally also not only to a symmetrical geometry of the reference means.Preferably, the at least one three-dimensional reference means is formed asymmetrically in a plan view, for example with an asymmetrically formed corner region. On the basis of the asymmetry or an asymmetric region-for example in a corner-the orientation of the reference means and thus, for example, the direction of the rotation of the roller can be reliably determined during the measurement.Within the scope of the invention, a plurality of three-dimensional reference means (of the type described) can be arranged on the surface of the roller and distributed over the working width b of the roller at a distance from one another. The plurality of reference means can optionally each differ in their geometry. In order to measure rolls with a larger working width which are many times wider than the measuring range of the monitoring device, a plurality of three-dimensional reference means are each arranged in the overlap region of the measurements, which, in addition to scaling / normalization, also serve for orientation and assignment during the evaluation. In order that the individual detected reference means can be distinguished from one another, they have differing geometries. This means that, in the case of the configuration as a pyramid, for example in a stepped manner, different reference means can each have different widths, heights or outlines in the individual steps.In a further embodiment of the invention, for absolute measurement of the surface, e.g. for absolute determination of the wear, at least one additional reference device can additionally be provided outside the working width of the roll, which is arranged, e.g., in an edge region on the roll periphery, on the roll end side or on the press frame. For carrying out absolute measurements, the additional reference device is arranged in a region which is not subject to wear, i.e. it is not arranged in the wear region to be examined and consequently not within the working width of the roller. This reference device is nevertheless detected by the same monitoring device, preferably the same sensor device, and serves as an absolute reference for the evaluation of the surface structure. The absolute measurement is consequently carried out relative to the absolute reference device by measuring the one or more three-dimensional reference means du of the associated sections of the roller surface within the working width of the roller. The reference device arranged outside the working area is consequently to be distinguished from the reference means arranged (temporarily) in the working area of the roller.The invention relates not only to the described method but also to a device for monitoring a three-dimensional structure of a surface of a roller for a roller press for comminution, briquettes or compacting, having a monitoring device and at least one three-dimensional reference means, wherein the at least one reference means can be fastened to the surface of the roller within the working width of the roller. The combination of monitoring device and reference means is consequently of particular importance.All preferred embodiments and features of the invention mentioned in connection with the method also apply to the device according to the invention.The monitoring device is preferably designed to be mobile or transportable. It consequently does not have to be an integral part of the press or press installation, but can be positioned in the region of the press or its roller for the purpose of measurement and can be removed again after the measurement has been carried out. Alternatively, the mobile monitoring device can also be mounted on a separate test stand, into which the roller is installed, for the (distance) measurements. In any case, the monitor can be positioned flexibly for carrying out the measurements on account of the transportable configuration and is not permanently attached to the roller press in order to protect it from damage even during operation of the press (during which measurement is not carried out). The mobile configuration is advantageous above all for measuring large roll widths with a plurality of measurements in different positions.The monitoring device according to the invention and the reference means used in this context are consequently also of particular importance within the claimed press plant. For the design and function of the monitoring device and for the optional and preferred embodiments, reference is made to the explanations relating to the described method and the described monitoring apparatus.The present invention also comprises a roll press installation having a roll press with two rolls rotatably mounted in a press frame, between which rolls a roll nip is formed, and having at least one three-dimensional reference means and a monitoring device for monitoring the three-dimensional structure of the surface of the roll, wherein the at least one reference means can be attached to the surface of this roll within the working width of one of the rolls. The monitoring device is consequently protected particularly preferably in combination with the roller press.The features relating to the method and the apparatus also apply to the roll press installation.In a preferred embodiment, the roller has a regular surface structure over the width and / or the circumference. A regular structure of the surface, i.e. a structure of the surface repeating over the width and / or the circumference, additionally facilitates the orientation on the roller surface or the combination of individual recorded three-dimensional images. For example, in a briculating press having respective troughs on the surface of the rolls, the formation and arrangement of these troughs is generally uniform. The wear protection elements of comminution rollers can also have a regular configuration and arrangement on the surface of the roller.The roller can be designed as a briculating or compacting roller with a trough-shaped surface structure or as a comminution roller with pin-shaped or plate-shaped wear protection elements. Both the depressions and the wear protection elements, such as, for example, "stubs" during "studlining", can be measured with the aid of the monitoring device. On the basis of the distance measurements carried out, it is possible, for example, to record the wear of the respective surface structure of the roller.According to the invention, the described at least one three-dimensional reference means, which is not subject to wear and is attached or attached to the surface of the roller (for example temporarily) within the working width of the roller during the distance measurements, is of particular importance, and is preferably releasable. This reference means is not only claimed-as described-in combination with the monitoring device, but also insulated and alternatively also in combination with a press roll of a roll press of the described type. The invention consequently also relates to a press roll of a roll press for crushing, carburizing or compacting material, wherein at least one three-dimensional reference means of the described type (not subject to wear) can be or is attached to the surface of the press roll within the working width. The combination of a fundamentally known press roller on the one hand and the reference means according to the invention (or a plurality of such reference means) on the other hand is consequently likewise protected as a press roller or press roller assembly according to the invention. The reference means itself can be configured in the described manner. To avoid repetitions, reference is made to the preferred configurations of the reference means which are described in connection with the claimed method, the claimed apparatus and the claimed press plant. All the features described or claimed of the reference means are also isolated and claimed in the combination of the reference means with or on a press roll.The invention is explained in more detail below with reference to drawings which merely represent exemplary embodiments. The following are shown: FIG. 1 : Roller press in a simplified side view, FIG. 2 : a roller or roller surface with the device according to the invention for monitoring, FIG. 3 : an embodiment of a reference means according to the invention in a side view, and FIG. 4 : a three-dimensional representation of the surface structure of a rollerIn FIG. 1, a roller press 3, for example a high-pressure roller press, is shown, which has two counterrotating press rollers 2 (shown schematically with their roller surface). A nip is arranged between the press rolls, wherein the nip width of the nip is variable during operation of the roll press 3. This is because one of the press rollers is designed as a fixed roller and the other press roller as a loose roller, wherein the loose roller can be adjusted by means of force generating means, e.g. hydraulically, against the fixed roller, so that the gap width changes within certain limits during operation.The material to be processed is fed from above, for example via a feed shaft, and drawn into the printing zone by the counter-rotating of the press rollers 2. There, the material can be comminuted, briquettes or compacted under the action of the existing pressure-depending on the application and design.FIG. 2 shows (simplified) one of the press rollers 2 of the roller press 3, wherein the three-dimensional surface structure 1 of the roller surface can be seen. If the roller is designed as a briculating or compacting roller, it has a trough-shaped surface structure, as is shown in simplified form in FIG. 2. In the embodiment of the roller as a comminution roller of a material bed roller mill, the roller can be configured with pin-shaped or plate-shaped wear protection elements. Such a wear protection layer is not shown in the figures. Nevertheless, the invention also encompasses this configuration of the surface of a roller. The three-dimensional surface structure of the roller can be formed both regularly and irregularly.The three-dimensional surface structure 1 of the roller 2 extends over the entire working width b of the roller 2, which however can be smaller than the entire width of the roller. The surface structure 1, which also forms the defect area, is detected by the monitoring device 4. This monitoring device 4 has an electromagnetic radiation source 9, for example a laser, which projects a beam 8 onto the surface, which beam is reflected by the surface structure 1 and recorded by a receiver 10, for example in the monitoring device 4. This is schematically shown in FIG. 2. The distance of the measuring device from the surface is determined by triangulation, so that the three-dimensional surface texture 2 of the roller 1 is detected by measurements while the roller 2 is rotating 12 over the circumference and the roller width or working width. The press roll 1 shown in FIG. 2 can be the roll shown on the left in FIG. 1, wherein the figures do not show the complete rolls, but above all the roll surfaces or an annular bandage of a press roll with the roll surface. If the analysis of the roller surface takes place within the press in the assembled state of the press roller, it is expedient to carry out the measurement on the "rear side" of the roller or roller surface opposite the roller nip, as is indicated in FIG. 2.In the exemplary embodiment shown, the source 9, e.g. the laser 8 of the monitoring device 4, projects a strip-shaped line, e.g. laser line, with a measurement range M extending along the width of the roller (i.e. axially parallel) or a measurement width M onto the surface of the roller.In the exemplary embodiment, this measurement width M is smaller than the working width b of the roller. The measuring device is preferably designed as a line scanner, so that a (initially two-dimensional) height profile is detected via the line. By rotating 12 the roller 1 and consequently by moving the roller surface relative to the measuring device, the complete three-dimensional structure is mapped, as it were, from a stringing together of the individually detected linear height profiles.On the surface of the roller and thus within the three-dimensional surface structure 1 of the roller 2 a three-dimensional reference means 5 is attached. This reference means 5 can be seen by way of example in an enlarged illustration in a plan view. The step-shaped geometry and an asymmetric corner region 6 are visible, which serves to identify the direction of rotation of the roller 2. The reference means 5 is also detected by the monitoring device 4 during the distance measurements, since it is positioned within the measurement range M. This allows the data to be scaled correctly independently of the positioning of the monitoring device and, in addition, allows simple and reliable analysis over a working width b which is greater than the measuring width M of the measuring device. This is because the reference means 5 is fastened to the roller surface in an overlap region of two successive width regions. Since the working width b of the roller 2 is greater than the measurement width M of the monitoring device 4, a plurality of distance measurements must be carried out one after the other over the working width b, which distance measurements are then merged into an image or a data record in the evaluation as a three-dimensional recording of the complete roller surface in order to represent the entire roller surface. In this case, a plurality of measurements are carried out in an overlapping manner. A three-dimensional reference means 5 is located in each of the overlap regions and is likewise detected by the monitoring device 4 when the distance measurement is carried out.It is consequently important within the scope of the invention that the geometry of the reference means 5 in the X direction, Y direction and Z direction is respectively known and stored in the monitoring device as a reference data set. The X direction refers to the direction along the roller width parallel to the roller axis, the Y direction is the direction along the roller circumference or the tangential direction, and the Z direction is the height direction, which consequently runs in the radial direction. During the measurement of the roller surface, consequently, not only the three-dimensional structure of the roller surface, but in particular also the reference means 5, is measured with the monitoring device and is detected, for example, on the basis of its specific asymmetry. By measuring the reference means 5, a so-called scaling data set is generated which varies--with respect to the previously stored reference data set--depending on the positioning of the monitoring device 4 relative to the roller surface. This acquisition of the scaling data set, which can also be referred to as a normalization data set, makes it possible during the evaluation to compensate for the possibly varying positioning of the measuring device relative to the surface of the roller 2. Thus, in particular measurements carried out successively can be standardized independently of the positioning of the monitoring device 4. Consequently, it is not important that, in the case of measurements carried out successively, the distance and or the angle of the monitoring device 4 or of the sensor relative to the roller 2 is identical. By knowing the geometry of the reference means 5 in each image data set, all angular and size distortions can be calculated by different alignments or distances of the measuring device 4 to the roller, so that a dimensionally and angularly accurate image of the entire roller surface is produced.With the described measurements taking into account the reference means 5 arranged in the wear region, planar images of the roller surfaces in the X, Y and Z directions that are true to dimensions and angles can be produced. From the height differences in the Z direction, the wear in the Z direction can be determined, namely relative to image points or regions of the same surface. However, in order to be able to analyze the absolute wear of the roller surface as well, in a particularly preferred embodiment a reference device 7 is additionally provided, which is arranged outside the wear region. It is expedient here to specify the absolute wear of the roller surface relative to the roller axis, i.e. the distance of the respective image points of the 3D image data set from the roller axis 13. Taking into account the additional measurement of this reference device 7, all data sets can be related to the roller axis 13 during the evaluation and the absolute distance of all surface points from the roller axis 13 can thus be determined. The absolute wear, i.e. the reduction in diameter of each point on the roller surface, can thus also be determined.The additional reference device 7 is indicated in FIG. 2. In the present illustration, this is arranged on the end face or flank of the roller 2. However, it can also be provided in an edge region on the roller periphery. In principle, it is also possible-at least in the case of the fixed roller-to arrange it at a suitable position on the press frame. The arrangement on the roller itself is, however, advantageous above all in the case of the movable roller of the press, since in this case the position of the movable roller and thus also of the roller axis relative to the press frame varies.The reference device 7 thus serves to perform absolute measurements of the surface structure 1 in the manner described and is therefore in any case arranged outside the wear area and consequently the working area of the roller 2. The reference device 7 is detected by the same monitoring device or by the same sensor device as the reference means 5, i.e. measured with the same device.FIG. 3 schematically illustrates a possible embodiment of a three-dimensional reference means 5 in cross section. The reference means 5 is formed as a step-shaped pyramid. This pyramid has several steps. In the present example, these have the same height, but can also have different heights. The width of the individual steps can vary; it decreases, for example, from bottom to top (to the tip of the reference means 5). One of the steps has a geometrically deviating contour 6, so that its identification or differentiation from further reference means 5 and / or the orientation of this reference means 5 relative to the roller 2 can be clearly established.Finally, FIG. 4 shows, by way of example, a three-dimensional representation of the surface structure 1 of a roller 2 determined using the method according to the invention. The different grey levels are each associated with different heights / depths of the profile. FIG. 4 shows the representation of the various briquettes in a briquettesing roll. The grey levels thus represent the Z direction. The darker the region is illustrated, the deeper the structure is, i.e. the greater the distance from the measuring device. FIG. 4 shows the darker and deeper troughs and the lighter and thus upwardly projecting webs which delimit the individual troughs and thus form the briquettes. If a reference device 7 is additionally used when performing the measurements, absolute values for the profile of the surface can be determined from this representation or the measurement data on which the representation is based.

Claims

Method for monitoring a three-dimensional structure of a surface (1) of a roller (2) for a roller press (3) for crushing, carburizing or compacting, having a monitoring device (4) which determines the surface structure (1) of the roller (2) by distance measurements as at least one 3D image data set, characterized in that during the distance measurements at least one three-dimensional reference means (5) is attached to the surface of the roller within the working width (b) of the roller (2).Method according to Claim 1, characterized in that the three-dimensional geometry of the at least one reference means is stored as a reference data set, in that distance measurements are carried out on the reference means during the measurement of the roll surface and a scaling measurement data set is generated therefrom, and in that the 3D image data set representing the surface structure of the roll is scaled taking into account the stored reference data set and the scaling measurement data set.Method according to claim 1 or 2, characterised in that the at least one reference means (5) is releasably attached to the roller (2), e.g. adhesively or magnetically.Method according to one of Claims 1 to 3, characterized in that the method is carried out outside or during an interruption of the production operation of the roller press (3), preferably in a state in which the roller (2) is installed in the roller press (3).Method according to one of Claims 1 to 4, characterized in that the roller (2) rotates during the monitoring of the three-dimensional surface structure (1), preferably at a constant speed.Method according to one of Claims 1 to 5, characterized in that the 3D image data record is generated by the distance measurements over the circumference and at least over a part of the working width (b) of the roller (2).Method according to one of Claims 1 to 6, characterized in that the monitoring device has at least one sensor device, wherein the sensor device has a source which generates at least one measurement beam, and wherein the sensor device has at least one detector or receiver which detects the measurement beam generated by the source and reflected by the surface of the roller.Method according to claim 7, characterised in that the measurement beam is an electromagnetic beam, e.g. a light beam, preferably a laser beam.Method according to claim 7 or 8, characterised in that the source projects the measuring beam onto the roller surface as a measuring line oriented along the roller width, e.g. as a light or laser line, wherein the length of the measuring line extending along the roller width defines the measuring width (M) of the sensor device or monitoring device.Method according to one of Claims 1 to 9, characterized in that the distance measurements are carried out by triangulation, preferably by laser triangulation.Method according to one of Claims 1 to 10, characterized in that the monitoring device (4) has a measurement width (M) which is less than the working width (b) of the roller (2), wherein, in order to record the entire working width (b) of the roller (2), a plurality of distance measurements are carried out (one after the other) over the working width (b) of the roller (2) and a plurality of 3D image data sets are thus generated, wherein the plurality of distance measurements overlap in at least one overlap region in which the at least one reference means (5) is arranged, wherein the plurality of 3D image data sets generated over the working width are combined and identically scaled taking into account the reference data set respectively stored for the reference means (5) and the scaling data set respectively recorded at the reference means.Method according to one of Claims 1 to 11, characterized in that the monitoring device (4) is mounted in a stationary manner, i.e. in a stationary manner, during the monitoring of the three-dimensional surface structure (1), in particular during the measurement over a measurement width (M).Method according to one of Claims 1 to 12, characterized in that the monitoring device, for example its sensor device for measuring a working width (b) which is greater than the measuring width (M), is positioned one after the other in different positions relative to the roll.Method according to one of Claims 1 to 13, characterized in that the at least one three-dimensional reference means (5) is designed in cross section as a step-shaped reference means (5), for example as a step-shaped pyramid.Method according to one of Claims 1 to 14, characterized in that the at least one three-dimensional reference means (5) is formed asymmetrically (6) in a plan view, for example with an asymmetrically formed corner region (6).Method according to one of Claims 1 to 15, characterized in that a plurality of three-dimensional reference means (5), which preferably differ in their geometry, are arranged distributed over their working width (b) at a distance from one another on the surface of the roller (2).Method according to one of Claims 1 to 16, characterized in that, for absolute measurement of the surface, for example for absolute determination of the wear, at least one reference device (7) is additionally provided outside the working width (b) of the roll (2), which reference device is preferably positioned at a defined distance from the roll axis (13), for example is arranged in an edge region on the roll periphery, on the roll end side or on the press frame.Device for monitoring a three-dimensional structure of a surface (1) of a roller (2) for a roller press (3) for crushing, carburizing or compacting material, for carrying out a method according to one of Claims 1 to 17 having a monitoring device (4) and at least one three-dimensional reference means (5), wherein the at least one reference means (5) can be fastened to the surface of the roller (2) within the working width (b) of the roller (2).Apparatus according to claim 18, characterised in that the monitoring device (4) has at least one sensor device, wherein the sensor device has a source with which a measurement beam can be generated and wherein the sensor device has a detector or receiver with which the measurement beam generated by the source and reflected by the surface of the roller can be detected.Device according to one of claims 18 or 19, characterised in that the monitoring device (4) or its sensor device is designed to be mobile or transportable.Device according to one of Claims 18 to 20, having an evaluation unit which is integrated into the monitoring device as an internal evaluation unit or is connected to the monitoring device as an external evaluation unit and / or communicates with the latter, wherein the reference data set for scaling the 3D image data set is preferably stored in the internal evaluation unit or the external evaluation unit.Apparatus according to one of Claims 18 to 21, characterized in that the source generates electromagnetic radiation, for example is designed as a light source, preferably as a laser, and / or in that the sensor device is designed as a line scanner, a measurement line extending along the roll width being projected onto the roll surface by means of the source.Roller press installation having a roller press (3) with two rollers (2) which are rotatably mounted in a press frame and between which a roller nip is formed, and with a device for monitoring according to one of Claims 18 to 22, in particular for monitoring the three-dimensional structure of the surface (1) of the roller (2) according to a method according to one of Claims 1 to 16, wherein the at least one reference means (5) can be attached to the surface of this roller (2) within the working width (b) of one of the rollers (2).Roller press installation according to claim 23, characterised in that the roller (2) has a regular surface structure over the width and / or the circumference.Roller press installation according to claim 23 or 24, characterised in that the roller (2) is designed as a briculating or compacting roller with a trough-shaped surface structure or as a comminution roller with pin-shaped or plate-shaped wear protection elements.Press roll, in particular for a roll press installation according to one of Claims 23 to 25, characterized in that at least one three-dimensional reference means of the described type is attachable or attached to the surface of the roll (2) within the working width of the roll (2).

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