Method for determining the course of the radius of curvature of a metal strip wound into a coil

Abstract

The invention relates to a method for building a database (18) for a coiling device (1) for winding metal strips (4). For a plurality of metal strips (4), in a first step (S1) of said method the respective strip (4) is wound into a coil (6), wherein adjustment variables (A) of a coiling mandrel (2) of the coiling device (1) and production data (P) of the strip (4) are acquired. In a second step (S2), a course of the radius of curvature (CR) of the strip (4) is ascertained on the basis of a two-dimensional digital image (15) of an end face (8) of the coil (6) formed by a lateral surface (9) of the strip (4) in the direction of the coil axis (7), and in a third step (S3), the course of the radius of curvature (CR) is input into the database (18), together with the acquired adjustment variables (A) and production data (P), as a data set (D).

Description

[0001] 202300221 1 Description Method for determining the radius of curvature profile of a metallic strip wound into a coil The invention relates to a method for determining the radius of curvature profile C Rof a metal strip wound into a coil based on a digital image of an end face of the coil. The invention further relates to a method for creating a database for a reeling device comprising a reel mandrel and at least one cage roller. Rolled metal strip – hereinafter referred to as 'strip' – generally has a constant strip thickness d along its length and, after exiting the last rolling stand, is wound into a cylindrical coil on a reeling device with radially expandable segments. The two side surfaces (strip edges) of the wound strip, running in the thickness direction of the strip, form the end faces of the coil. A winding layer of the strip is also referred to as a turn or coil turn. The strip thickness of a strip to be wound, in particular a hot-rolled strip, can range from approximately 0.5 mm to approximately 1.5 mm.25 mm, whereby when reeling strips with a strip thickness of approximately 10 mm or more, damage to the innermost coil turns can occur in the form of mechanical indentations from the underlying strip beginning or in the form of kinks in these coil turns. A reeling device for strips further comprises one or more cage rollers arranged circumferentially around the reeling mandrel, which support the start of the reeling process: before the strip beginning of the strip to be reeled meets the reeling mandrel, the cage rollers are spaced apart in a respective radial starting position relative to the reeling mandrel by means of corresponding actuators, whereby the radial distances of the individual cage rollers decrease in the winding direction, so that an incoming strip is guided around the reeling mandrel and simultaneously directed towards the reeling mandrel. The position of the strip beginning is determined by the plant automation of the system producing the strip.The position of the coiling device is known to the plant automation system at all times. As soon as the strip beginning reaches the coiling mandrel, the cage rollers press the corresponding strip section radially against the mandrel. To minimize the aforementioned damage to the inner coil windings during coiling, each cage roller is briefly disengaged from the strip (i.e., moved radially outwards) as soon as the strip beginning passes under the respective cage roller in a radial direction. Furthermore, during the winding process, the coiling mandrel is initially in an extended position, meaning the extendable segments of the mandrel are at least partially extended radially, allowing the coil to be easily unwound from the mandrel after the segments have retracted and the winding process is complete.Furthermore, when winding the strip, the reel mandrel rotates in the winding direction with a certain lead V (this is a function of the difference between the reel mandrel speed v). D (specifically: the velocity of the lateral surface of the approximately cylindrical reel mandrel) and the inlet velocity v B(of the tape to be wound): this prevents, on the one hand, the tape beginning from jamming in the spaces between the spread mandrel segments, and on the other hand, the lead V, in conjunction with the cage rollers that press the incoming tape beginning radially against the reel mandrel, generates a corresponding sliding friction force between the tape and the reel mandrel. As the incoming tape wraps around the reel mandrel, the sliding friction force increases until static friction sets in and the already wound section of the tape and the reel mandrel rotate synchronously. This marks the end of the winding phase and can be detected, for example, by the motor torque of the reel mandrel drive, which increases significantly at this point.After the winding phase is complete, the cage rollers are no longer needed for the further winding process and are completely removed from the forming coil (i.e., moved radially away from it). Additionally, the winding mandrel is usually re-spread: this means that the mandrel segments are pressed radially outwards with a specific force to create a secure frictional connection with the coil. Furthermore, after the winding phase is complete, the winding mandrel drive is switched from a pre-winding control to a strip tension control, in which a specific, predetermined strip tension (in the sense of a tensile force) is exerted on the strip by the winding mandrel. This is necessary because the strip speed v. BThe winding process is determined by the last rolling stand, and applying a corresponding tensile force to the strip prevents it from winding too loosely or from becoming jammed ("cobbled") in the reeling device. When the strip winds correctly, it forms a spiral around the reel mandrel – viewed in the axial direction – consisting of adjacent turns. Each turn has an inner and an outer surface with respect to the reel mandrel, and a "local radius of curvature" is geometrically defined as an oscillating circle at a given point on the spiral. The spirally wound strip can thus be described as having a so-called radius of curvature profile C. Ras a sequence of local radii of curvature, which, as a function of the wrap angle around the reel mandrel from the inside out (or equivalently, as a function of the wound strip length), essentially increases monotonically. The expression "essentially" in this context means that local deviations, relating to short sections of the spiral in the circumferential direction of, for example, up to 30°, may deviate from the monotonic behavior. At those points where the strip is wound over its own beginning, the strip thickness causes a certain vertical offset of the windings above it, with this offset being most pronounced for the innermost winding and decreasing continuously for windings above it. This vertical offset also determines the local radius of curvature of the spiral.of the band at the relevant points, which is reflected in corresponding fluctuations in the radius of curvature curve C. R This has an effect. If such a deviation lies outside predefined limits, this corresponds to a correspondingly strong local bending of the wound metal strip, so that it may have to be downgraded, since the bending, for example, represents a non-elastic deformation of the strip and can therefore be permanent. The extent of the deformation in the area above the beginning of the strip can be controlled by the control of the cage rollers (engagement and disengagement times as well as the engagement force on the strip), the lead or strip tension control, and the spreading force F. S the reel mandrel can be influenced. However, the infeed speed v B not affected by the reeling device, since the infeed speed v BThe winding process is determined by the last rolling stand through which the strip passes. Gentle winding of the strip by the reeling device reduces local bending of the innermost turns but increases the risk of cobble. Conversely, tight winding (for example, with a correspondingly strong lead or strip tension control) leads to a reliable winding process, but the bending or indentations of the innermost turns are more pronounced. EP 3671 113 A1 discloses a method for determining a kink in the innermost turn of a strip wound into a coil, according to which an image of an end face of the coil with a laser line projected onto it is evaluated. From the measured intensity differences at different points of the laser line, a winding distance of the innermost winding layer to the coil axis is determined for three different angular positions with respect to the coil axis.If the winding spacing falls below a certain threshold, this is classified as a kink. JP 3669096 B2 teaches how to detect wrinkling in individual windings of a metal strip wound into a coil. For this purpose, the number of windings is determined from several images of the coil's end face. Using a CCD line scan camera, multiple images are taken at different angular positions relative to the coil's circumference, and the number of windings is determined in each image. Wrinkling is detected by differences in the number of windings relative to the angular positions. A first object of the present invention is to provide a method for determining a measure of the winding quality of strips wound into coils in a simple and reproducible manner.Since, as mentioned above, the local bending of the inner windings depends on details of the winding process itself, a second object of the invention is to find a sensible compromise between sufficient process reliability of the winding process on the one hand and a material-friendly winding process on a specific reeling device on the other. A third object of the present invention relates to the fact that, due to inherent defects in the tape material itself (e.g., sabering), even on an optimally adjusted reeling device, tapes are generally wound into coils with a non-ideal winding shape. In other words, an optimally adjusted reeling device would only be able to produce ideally wound coils if the tapes themselves did not have any defects.According to the invention, it is proposed in this context to create a database based on a plurality of strips that are wound into coils on the same reeling device. To solve the third problem of the invention, this database can then be evaluated after the plurality of strips have been wound in order to distinguish the effects of inherent defects in the strips from the effects of suboptimally set winding parameters on the respective reeling device. In other words, those parameters that are relevant for an optimal setting of the reeling device can be filtered out from such a database using statistical methods. Basic methods for setting up and evaluating such a database are known, for example, from EP 4124 398 A1.The first problem is solved according to the invention by a method with the features of claim 1, which provides a radius of curvature profile C. R The second and third problems are solved by a method for creating a database for a specific reel device with the features of claim 9, wherein the respective radius of curvature profile C is stored in the database. Ras well as the associated winding parameters of a larger number of strips wound on the respective reeling device. Advantageous embodiments of the invention are the subject of the respective dependent claims. In the inventive method for setting up a database for a reeling device, wherein the reeling device comprises a reeling mandrel and at least one basket roller, a metallic strip with a strip thickness d is wound onto a coil by the reeling device around a coil axis in a first step S1. In this step, the setting parameters A of the reeling mandrel and production data P of the strip are recorded. In a second step S2, after the strip has been wound, a radius of curvature profile C is recorded. RThe radius of curvature of the strip is determined using a two-dimensional digital image of an end face of the coil formed by a side surface of the strip in the direction of the coil axis. In a third step S3, the determined radius of curvature profile C is R The recorded settings A and production data P are inserted into the database as a data record D. The sequence of steps (S1, S2, S3) is repeated for a plurality (e.g., at least 50) of further strips. According to a preferred embodiment of the method according to the invention, the production data P comprise at least a strip thickness d and / or a winding temperature T. cof the respective strip. Furthermore, the production data P can include a yield strength and / or a modulus of elasticity and / or a saberness and / or a flatness and / or a wedge value of the strip in question. Saberness – also referred to as lateral straightness – is the deviation of a side edge – or a side surface – of the strip from a straight line over a predetermined measuring length. The definitions for flatness and for a wedge value of a strip are known, for example, from EP 3691 806 B1 and WO 2019 / 086172 A1, respectively. In a further preferred embodiment of the inventive method for building a database, the parameters A include at least a strip tension B and / or a pre-tension V of the reel mandrel and / or a spreading force F. S for the subsequent spreading of the reel mandrel and / or a subsequent spreading time t Sof the mandrel and / or a pre-spreading degree G of the mandrel. The pre-spreading degree G corresponds to a specific opening position of the mandrel segments in the radial direction and is specified, for example, as a percentage of a maximum possible opening position; a pre-spreading degree greater than zero during the winding process is a prerequisite to be able to pull the coil off the mandrel after completion, whereby the mandrel segments are drawn together in the radial direction. Furthermore, the adjustment parameters A can be an adjustment force F. K and / or a positioning position P Kfor at least one basket roller of the reel mandrel. According to a further preferred embodiment of the inventive method, in the first step S1, a material class M of the strip in question is also recorded, which is added to the data set D in the third step S3. The material class can, for example, be a steel grade that characterizes the chemical composition of the strip. According to a further preferred embodiment of the inventive method, in the first step S1, the input variables A and the production data P are time-resolved in a plurality of successive time intervals. er- The second step, S2, is defined according to the time intervals, which range from 200ms to 500ms. tervallen - After determining the radius of curvature profile CR, this is assigned section by section to the time-resolved input parameters A and the time-resolved production data P (e.g., using a timestamp). Because the inlet speed v B Since the length of the relevant band on the reeling device is predetermined or known in each time interval ^j, in this preferred embodiment, this knowledge allows each time interval ^j to be assigned to a corresponding band section or a corresponding section C. R j of the radius of curvature profile C R It can be assigned if it encompasses the physical starting or ending point of the belt (corresponding to the belt head or belt foot). In summary, according to this described design, the radius of curvature profile C RTogether with the recorded setup parameters A and production data P, this data is stored in the database in the form of a time-resolved dataset D, which can additionally include the material class M. This advantageously allows the temporal variability of the setup parameters A and production data P to be taken into account and a precise functional relationship C to be established. R = C R (P, A; M) between the determined radius of curvature profile C R and to determine the setup parameters A or production data P (optionally with the respective material class M as a parameter). This functional relationship C R (P, A; M) can be used to optimize the adjustment parameters (A) of the reeling device in order to achieve a desired radius of curvature profile C. RIn a further preferred embodiment of the inventive method, a two-dimensional digital image of an end face of the coil in the direction of the coil axis is created in a first intermediate step Z21, wherein the end face is formed by a side surface of the strip. The expression "in the direction of the coil axis" in this context means that the image plane is essentially oriented normally to the coil axis, although a deviation from this by up to 15° can be compensated for by the subsequent image-processing algorithm: this allows the digital image to be created, for example, freehand by an operator, for instance, using a digital camera. Furthermore, an inner or outer edge of a side surface is formed by its transition to the corresponding inner or outer surface (with respect to the coil axis) of the wound strip.The digital image exists as a digital data set and is composed of individual pixels, each pixel carrying at least brightness information and optionally color information. Since the coil axis coincides with the axis of rotation of the coiling mandrel during the winding process, the individual turns of the coil are visible from the aforementioned perspective. To distinguish the individual turns from one another in the image, only sufficient area illumination of the coil's end face is required; the projection of special light patterns (e.g., laser lines) onto the coil's end face is not necessary for the inventive method. In a subsequent second intermediate step Z22, the coil's end face is detected in the digital image, for example, by executing a first image processing algorithm. This can be achieved, for example, by applying a Hough transform specialized for circular shapes to the image (or...on the digital dataset of the image)202300221 10. Alternatively, the image or the digital image data can also be fed into a neural network that has been trained to recognize circular structures. In any case, those pixel areas in the image that are not recognized as part of the front face (surroundings outside the coil circumference as well as the area within the coil eye) are excluded from the image data, for example by setting the brightness information of the pixels in question to a characteristic value (e.g. 0). Optionally, the image can be cropped to specific areas so that essentially only a rectangle describing the coil circumference remains as the image data area. After the second intermediate step Z22, i.e.After detecting the end face in the image, a third intermediate step Z23 determines an inner and / or outer edge of the side surface of the strip captured in the image, for example by executing a second image processing algorithm. Preferably, the determination of an inner and / or outer edge can be based on local brightness gradients in the image. The determination of local brightness gradients is performed separately for each image pixel based on the difference between the brightness value of the considered image pixel and the brightness values ​​of neighboring image pixels and is known from the literature, for example, in the form of the so-called "Canny Edge Detection" algorithm. In this process, those pixels in the image data that lie outside image areas with significant brightness gradients are excluded.The determination of an inner and / or outer edge can be implemented by modifying the image data, for example, so that only those pixels are marked in the image data (e.g., set to a specific value, while the remaining pixels of the image are set to a different value) that trace the aforementioned inner or outer edges of a face. The term "tracing" in this context is to be understood as "essentially parallel," since, strictly speaking, in a coil whose turns are usually directly adjacent to each other, an inner edge defined in the above sense coincides with the outer edge of the turn below it. However, by determining an inner and / or outer edge based on local brightness gradients, lines typically result in the image data that are slightly parallel and offset with respect to the actual inner or outer edges.The outer edges run. In a subsequent fourth intermediate step Z24, the coordinates X are determined. i / X i The pixels corresponding to the inner and / or outer edge are determined, and their coordinates are arranged in a respective data array. For example, at least one endpoint (or at least one pixel corresponding to a respective endpoint) is determined for each inner and / or outer edge. Thus, for the inner or outer edge, either the endpoint closer to the coil axis is determined, or, alternatively, the endpoint farther from the coil axis. The coordinates of the endpoints are entered as the first elements X1 and X1', respectively, into a corresponding data array. Subsequently, starting from the respective endpoints, the coordinates are / X iThe pixel of the next adjacent pixel corresponding to the inner or outer edge is also inserted as an element into the respective data array. This process is repeated until the second endpoint of the inner or outer edge defined in the image data is reached. The arrangement in the data array thus corresponds to the spatial arrangement of the adjacent image pixels tracing the inner or outer edge; each of the data arrays therefore represents – depending on the position of the respective identified endpoint X1 or X1' – an ordered set of coordinates {X} running either from the inside out or from the outside in. i} or {X i'}, which corresponds to the spiral shape of the corresponding inner or outer edge of the side surface of the strip. Since the invention is aimed at the shape of the radius of curvature and not at absolute values ​​of the curvature of the wound strip, it is irrelevant in this context at what scale or in which units the coordinates X are defined. i / X i ' be saved or that the determined coordinates X i / X i 'For example, it concerns image coordinates and not coordinates in absolute units of measurement. The only crucial point is that the coordinate values ​​of the individual pixels are correct relative to each other. In a subsequent fifth intermediate step Z25, the curvature radius profile C is determined. RThe radius of curvature C is determined from the data array of the corresponding inner and / or outer edge of the band. If the data array exists for both the inner and outer edges of the side surface, only one of the two data arrays can be used for evaluating the radius of curvature profile C. R can be used (e.g., the one with more elements) or an average radius of curvature profile C can be used. RThe thickness of the band is determined from the two data arrays. According to a preferred embodiment of the method according to the invention, the image resolution is dimensioned such that the band thickness d is mapped onto at least three pixels of the image. The image resolution results from the focal length of the recording optics and its distance to the end face of the coil, as well as the resolving power of the image-generating sensor (e.g., the pixel pitch in the case of an electronic sensor). Sufficient image resolution can be quickly and easily checked visually by an operator on a live display of the image recording device (e.g., a mobile phone camera). According to a further preferred embodiment of the method according to the invention, after the execution of the second intermediate step Z22, i.e., after detecting the end face of the coil in the image, the image is blurred in the tangential direction R. Twith respect to the coil axis. The tangential direction is R. T at each pixel normal to a connecting line between the considered pixel and the coil axis in the image. For example, a Gaussian filter can be applied to the image data for blurring, which – relative to polar coordinates whose origin coincides with the center of the coil eye or the coil axis – only affects the tangential direction R. T It works by blurring the image data in the tangential direction R. TIrregularities (e.g., dirt or scale) on the depicted, spirally wound side surfaces of the strip are blurred and attenuated, while at the same time, no or only a much weaker blurring occurs in the radial direction. This type of blurring is also referred to as direction-dependent blurring or "adaptive blurring," which more clearly emphasizes the boundaries between adjacent side surfaces (corresponding to the superimposed coil windings of the strip). This facilitates subsequent measurement of the exact course of the windings. If the image of the coil or its end face is a color image (i.e., if each pixel of the image carries color information), the image data can be converted to monochrome values ​​(so-called color rendering) before blurring.Grayscale conversion is performed because, on the one hand, no color information is required for the subsequent process steps, and on the other hand, grayscale conversion reduces noise in the image information, thus enabling better detection of the inner or outer edge. According to a further preferred embodiment of the inventive method, after the third intermediate step Z23, i.e., after the determination of the inner and / or outer edge of the side surface of the strip, a skeletonization of the inner and / or outer edge determined in the image data is performed. During skeletonization, short (e.g., up to a maximum of 30 to 50 pixels), contiguous pixel groups are eliminated from the image data (e.g., brightness values ​​of these pixels are set to 0), since these pixels do not represent real structures but merely artifacts of the evaluation of the brightness gradients from the preceding third step S3.Furthermore, the remaining, spatially contiguous, and not yet eliminated pixels of the image are reduced to a line width of one pixel using morphological image operations; that is, pixels that result in a width greater than one pixel for a contiguous line are also eliminated. Finally, the image processed in this way can be binarized by, for example, setting the brightness values ​​of the pixels not yet eliminated to 1 and those of the remaining pixels to 0. As a result, the image information consists of one or two contiguous, essentially parallel lines of pixels that correspond to the inner or outer edge of the side surface of the spirally wound band. In such skeletal lines, for example, each endpoint (with, for example,Each pixel with a brightness value of 1 is characterized by only one immediately adjacent pixel (also with a brightness value of 1), whereas each pixel that lies – in a geometric sense – within one of the lines is characterized by two immediately adjacent pixels with the same brightness value (e.g., 1). The immediately adjacent pixels include up to 8 pixels surrounding a pixel under consideration. Preferably, the curvature radius profile C is determined. RThis is achieved – geometrically speaking – by determining a circle (so-called oscillating circle) for each point set that includes a specific point in the data array and its N nearest neighbors on both sides. This circle approximates the point set as closely as possible at the point under consideration. The radius of the resulting circle is stored as the radius of curvature of the band at the point under consideration, and the process is repeated for all other points in a data array. Even if a selected point does not have N neighboring points on one side (e.g., at or near the respective endpoint of the determined inner or outer edge), a corresponding circle can still be determined using the smaller point set. Specifically, this is done for each element X. i or X i ' of the data array of the inner and / or outer edge the respective element X i or itself and additionally N before and N after the element X i or Xi ' arranged elements X i-N ,…,X i+N or X i-N ',…,X i+N ' selected from the respective data array (with N as a natural number); into the spatial coordinates of the (maximum) 2N+1 selected elements X i-N ,…,X i+N or X i-N ',…,X i+N ' becomes a circle with radius R i or R i ' fitted and the radius R i or R i ' (or a combination of R i and R i ') is considered a value corresponding to the radius of curvature profile C R added. Since the inner and outer edges continue to trace the spiral path of the wound band, the pixel coordinates can be converted into a band length, so that the determined radius of curvature profile C RThis is subsequently represented as a pointwise function of the length of the wound strip. Again, this length is not necessarily in absolute units of measurement with respect to the coil, but in relative units with respect to the determined pixel coordinates, which, however, is irrelevant for evaluating the curvature radius. Although three points are in principle sufficient to define a circle using a set of points, it is advantageous to use a larger number of points. In a further preferred embodiment of the inventive method, therefore, points are measured on both sides of a considered element X. i or X i ' between N = 50 and 200 upstream and downstream elements of the respective array for determining the radius of curvature in the relevant element X i or X i'The following is used. Geometrically, between N=50 and 200 adjacent points are used on both sides to fit a circle through a specific point. For example, the circle is fitted into the selected set of points using a least-squares-fit method. A least-squares-fit method is a well-known mathematical procedure for determining a target quantity (in this specific case, a circle) that also provides a reliable result for the target quantities (position and radius of the desired circle) even with input quantities that are subject to significant errors (in this case, the coordinates of the selected pixels are subject to errors).The described procedure allows the radius of curvature at each point to be determined with particularly high accuracy, since a suitably chosen method and a correspondingly high number of points used can compensate for statistical errors caused, for example, by the finite pixel size and the associated spatial discretization errors in image processing. The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of an embodiment, which will be explained in more detail in conjunction with the figures.Figure 1A (FIG 1A) shows a reel mandrel during the winding of a strip into a coil before completion of the first turn, Figure 1B (FIG 1B) shows a reel mandrel during the winding of a strip into a coil at the completion of the first turn, Figure 2A – Figure 2G (FIG 2A - FIG 2G) shows an implementation example of the second step S2 for determining a radius of curvature profile C. R Figure 3 (FIG 3) shows an embodiment of the inventive method for building a database. Corresponding parts in the figures are provided with the same reference numerals. FIG 1A shows a reeling device 1 with a reel mandrel 2 onto which a metallic strip 4 is wound to form a coil 6. The reel mandrel 2 is shown in the direction of its axis of rotation, which coincides with the coil axis 7. The coil is wound at an entry speed v BThe incoming strip 4 has a strip thickness d and is deflected by drive rollers 17 towards the reel mandrel 2. The reel mandrel 2 (specifically: the outer surface of the reel mandrel) rotates in FIG. 1A at a reel mandrel speed v. D Clockwise. Around the reel mandrel 202300221 17, basket rollers 5a-5d are arranged, which are actuated by a respective actuator 19a-19d in a radial direction with respect to the rotation axis of the reel mandrel 2 with a respective actuating force F K The basket rollers 5a-5d can be positioned against or moved away from the reel mandrel 2 (lifted off). The actuators 19a-19d move the basket rollers 5a-5d to their respective positioning positions P. KThe procedure is as follows: To assist the winding process of the strip 4, it is pressed against the reel mandrel 2 by the cage rollers 5a-5d during the winding of the first turns (e.g., until the innermost three to five turns are completed). To prevent strip damage, a cage roller 5a-5d is briefly lifted whenever the beginning of the strip 3 moves directly (in a radial direction with respect to the rotation axis of the reel mandrel 2) beneath the respective cage roller 5a-5d. During the winding phase, the reel mandrel speed is v D greater than the inlet velocity v Bof the band 4 (corresponding to a lead V), such that the sliding friction between band 4 and the reel mandrel 2 exerts a force – also referred to as band tension B – on the incoming band 4. Furthermore, during the winding of the band 4, the reel mandrel is opened radially with a specific degree of pre-expansion G (by correspondingly opening the mandrel segments). A spreading force F s , with which the reel mandrel 2 or the mandrel segments after completion of the winding phase at a specific post-spreading time t S The force that can be pressed against the coil 6 is symbolized by two arrows pointing radially away from the coil axis 7. The specified winding mandrel speed v D corresponding to a lead V, the spreading force F S , of the post-spreading time t S and the pre-spreading degree G of the reel mandrel 2 as well as the respective actuating forces F K and the positioning positions P KThe individual basket rollers 5a-d are controlled by an automation unit 16 and are symbolized in FIG. 1A by means of corresponding connecting lines. The aforementioned parameters can either be predetermined (controlled) or adjusted (regulated) for the respective components by means of corresponding feedback. FIG. 1A shows the strip 4 in a state shortly before completion of the first turn, i.e., the incoming strip 4 is about to be laid over the strip beginning 3 in a second winding layer. The point in time shortly after completion of the first turn is shown in FIG. 1B, where the basket roller 5a closest to the driver rollers 17 with respect to the strip direction is lifted from the strip 4 to prevent damage to the strip from the underlying strip beginning 3.A small-scale change in the curvature of the winding path of the strip 4 is also visible in the region of the strip start 3. This change is more pronounced the greater the strip thickness d, i.e., the higher the step in the radial direction due to the strip start 3 for a winding above it. FIGS. 2A – FIGS. 2F show, in an exemplary embodiment, the intermediate steps Z21 to Z25 for determining a radius of curvature profile C. Rof a coil 6 from a digital image 15 of this coil in the second step S2 of the inventive method. The intermediate steps Z21 to Z25 can, for example, be performed by a separate computing unit 20 (^ see FIG. 3). FIG. 2A shows an image 15 of a strip 4 wound into a coil 6, created in a first intermediate step Z21 by a digital camera 13 (not shown in FIG. 2A). A side surface 9 of the spirally wound strip 4 forms the end face 8 of the coil 6 via the individual coil turns 10. In the image 15, in addition to the end face 8, the surroundings of the coil 6 are also captured and indicated by corresponding structures. In a second intermediate step Z22, the front face 8 is detected in the digital image 15 (or in the digital image data) by executing a first image processing algorithm.Specifically, the annular area of ​​the end face 8, indicated in FIG. 2A by two concentric circles, is determined. Those image areas that are not part of the end face 8 are excluded. This is shown in FIG. 2B; in addition, the position of the coil axis 7 in the image is also determined, which is indicated in FIG. 2B by a cross. Subsequently, in the case of color image data (e.g., because the image 15 was taken with a mobile phone camera), a grayscale conversion is performed (e.g., by extracting an artificial luminance channel from the individual color channels of the image), which leads to an increase in contrast in the image data, since the signal-to-noise ratio is improved by combining several color channels. According to the illustrated embodiment, the monochrome image data is then subjected to a blurring process that only applies in the tangential direction R. Twith respect to the coil axis 7, this leads to a suppression of image disturbances (e.g., due to impurities on the end face 8) and thus to a clearer highlighting of the individual coil windings 10 forming the side surface 9 in the image data (FIG 2C). In a subsequent third intermediate step Z23, at least one inner edge 12a and / or one outer edge 12b of the side surface 9 are determined in the image 15 by executing a second image processing algorithm (FIG 2D). In the illustrated embodiment, the second image processing algorithm evaluates local brightness gradients in the image data, resulting in one or more pairs of parallel line segments – one line corresponding to the inner edge 12a and one to the outer edge 12b.Subsequently, as described above and shown in FIG. 2E, the inner and outer edges 12a and 12b determined in the image data are skeletonized and binarized, resulting in only those image areas that trace a simply connected section of the inner edge 12a and the outer edge 12b. FIG. 2F shows a fourth intermediate step Z24 in an embodiment of the method according to the invention, in which the coordinates X. i the inner edge 12a and the coordinates X iThe pixels corresponding to the outer edge 12b are determined. The coordinates X1 and X1' correspond to the inner (with respect to the spiral coil winding) endpoint of the inner and outer edges 12a and 12b, respectively, and form the first entry in a data array 14a and 14b, respectively. Subsequently, the other pixels corresponding to the inner and outer edges 12a and 12b are determined and arranged in the respective data array 14a and 14b according to their position along the inner and outer edges 12a and 12b, respectively, until the second (outer) endpoint Y1 and Y1', respectively, is reached as the last entry in the data array 14a and 14b, respectively. FIG 2G shows the result of a fifth intermediate step Z25, in which the radius of curvature profile C Ras a function of the length of the inner or outer edge 12a, 12b from one or both of the data arrays 14a or 14b. The horizontal axis denotes a length coordinate of the inner or outer edge 12a, 12b (or the band length) in arbitrary units, while the vertical axis is a measure of the curvature radius profile C. R indicates the radius of curvature profile C. R Although S5 is available as a pointwise function after the fifth step (corresponding to the evaluated image pixels), it is shown as a solid line in FIG. 2G due to the large number of function values. Only at one point is a single value representing a determined radius of curvature R. i or R i ' represented as a point on the solid line. The dashed line C m represents a course of C averaged over the length coordinate RThis represents, for example, the average of 20 to 50 adjacent CR values ​​(so-called moving average). The dashed line C th This represents a threshold curve shifted vertically relative to the averaged curve. FIG 2G shows that the radius of curvature curve C R and its average course C m Globally considered (i.e., across the entire determined range of values), it decreases, meaning that the curvature of the strip 4 wound into a coil 6 decreases accordingly. This corresponds to the fact that, in the implementation example, the respective inner endpoint of the inner 21 or outer edge 12a, 12b was used as the starting value X1 or X1' for the data array 14a, 14b, and the radius of curvature profile C R accordingly follows the spiral coil winding from the inside out. Besides minor fluctuations in the course of C. RIn addition to image errors and discretization errors (due to the finite pixel size in the digital image 15), pronounced local maxima and minima are also discernible, which repeat periodically: these are due to spatially limited changes in the winding profile of the tape 4, which arise from the tape start 3. The determined radius of curvature profile C R or an exceedance / fall below the threshold curve C th through the radius of curvature profile C RThis can therefore be used as a quality criterion for assessing the winding quality of the strip 4 by the reeling device 1. FIG. 3 shows a perspective view of a digital camera 13 positioned in front of a finished coil 6 along its coil axis 7, with the camera 13's viewing direction being directed (with a tolerable deviation of up to 15°) towards an end face 8 of the coil 6. The distance between the digital camera 13 and the end face 8 is chosen such that the individual coil turns 10 of the coil 6 are distinguishable from one another in an image 15 produced by the digital camera 13. The coil turns 10 visible to the digital camera 13 are formed by one of the two side surfaces 9 of the strip 4.According to an embodiment of the inventive method for building a database 18, in a first step S1, a metallic strip 4 with a strip thickness d is wound onto a mandrel 2 of a specific winding device 1 (not shown in FIG. 3) around a coil axis 7 to form the coil 6. In the first step S1, in addition to the information shown in Figure 15, the setting parameters A of the mandrel 2 of the winding device 1 and production data P of the strip 4 are also recorded. According to the illustrated embodiment, the setting parameters A include a strip tension B, a lead V, and a spreading force F. S , a post-spreading time t S and a pre-spreading degree G for the reel mandrel 2 as well as an engagement force F K and a positioning position P K for at least one of the basket rollers of the reeling device 1, while the production data P at least the strip thickness d and a winding temperature T Cof the strip 4. The setting parameters A are specified during the winding process by the associated automation unit 16, the reel mandrel 2, or the actuators 19 of the basket rollers 5a,...,5d of the reeling device 1 (not shown in FIG. 3). These parameters, along with the production data P of the strip 4, are recorded for further processing by a dedicated computing unit 20, symbolized by a dashed rectangle in FIG. 3. For recording the setting parameters A and the production data P, the computing unit 20 is connected to at least one control system 21 that is superior to the reeling device 1. In this case, the computing unit 20 receives both the setting parameters A and the production data P directly from the control system 21.Alternatively, as shown in FIG. 3, the computing unit 20 is also directly connected to the automation unit 16 via data transmission in order to directly receive the input parameters A from it. The input parameters A and the production data P are acquired with time resolution in a plurality of time intervals ^j, each with a duration of 200 ms to 500 ms, which is indicated in FIG. 3 by a corresponding rectangular border and curved brackets for the time intervals ^jan. Thus, for each image 15 (created in a subsequent second step S2), a plurality of partial data records are generated, containing the input parameters A and the production data P from a respective time interval ^j.In a second step S2, after the winding of the strip 4 to the coil 6, a radius of curvature profile C is obtained from an image 15 created by means of the digital camera 13 according to the method described above according to the invention (comprising intermediate steps Z21 to Z25). RThe data set is determined and, in a subsequent third step S3, is inserted into a database 18 as a data set D together with the setting parameters A and production data P recorded in the first step S1 (which, as explained above, are available as time-resolved partial data sets). The sequence of steps S1, S2, S3 is repeated for a large number (e.g., several dozen or hundreds) of further strips that are wound on the same reeling device 1 and of which the further strips 4' and 4^ are indicated representatively in FIG. 3: this is symbolized in FIG. 3 by the additional production data P', P^, setting parameters A', A^, and the data sets D', D^.

[0002] 202300221 24Reference symbol list 1Reel device2Reel mandrel3Strip start4, 4', 4^Strip5a,…,5dBasket roller 6 Coil7 Coil axis 8 End face 9 Side surface 10 Coil winding 12a, 12b Inner, outer edge 13 Digital camera 14a, 14b Data array 15 Digital image 16 Automation unit 17 Driver rollers 18 Database 19a,…,19d Actuator Computing unit Control system A, A', A^ Setting parameters B Bandzug d Band thicknessC R Curvature radius profile C m averaged radius of curvature Cth threshold value D , D', D^ Datensatz F K Actuation force basket roller F S Spreading force G Vorspreizgrad M Material class 202300221 25N natural number P, P', P^ Production data Position of basket roller tangential direction radius V erfahrensschritt Wrapping temperature Post-spreading time v B Infeed speed of belt vD, reel mandrel speed V, lead X1, Xi, coordinates, element data array X1', Xi' coordinates, element data array Z21 … Z25, intermediate step ^ j Time interval

Claims

202300221 26 Patent Claims 1. Method for constructing a database (18) for a reeling device (1), the reeling device (1) comprising a reeling mandrel (2) and at least one basket roller (5a,…,5d), wherein - in a first step (S1) a metallic strip (4) with a strip thickness (d) is wound by the reeling device (1) around a coil axis (7) to form a coil (6), wherein setting parameters (A) of the reeling mandrel (2) and production data (P) of the strip (4) are recorded, - in a second step (S2) a radius of curvature profile (C R ) of the band (4) is determined using a two-dimensional digital image (15) of an end face (8) of the coil (6) formed by a side surface (9) of the band (4) in the direction of the coil axis (7), - in a third step (S3) the radius of curvature profile (C R) together with the recorded setting parameters (A) and production data (P) is inserted as a data set (D) into the database (18), and - wherein the sequence of steps (S1, S2, S3) is repeated for a plurality of further tapes (4', 4^).

2. Method according to claim 1, wherein the production data (P) includes at least the tape thickness (d) and / or a winding temperature (T c ) comprise.

3. Method according to claim 2, wherein the production data (P) further comprise a yield strength and / or a modulus of elasticity and / or a saberness and / or a flatness and / or a wedge value.

4. Method according to claim 1, wherein the adjustment parameters (A) comprise at least a strip tension (B) and / or a lead (V) of the reel mandrel (2) and / or a spreading force (F). S ) for re-spreading the reel mandrel (2) and / or a re-spreading time point (t S) of the reel mandrel (2) and / or a pre-spreading degree (G) of the reel mandrel (2). 202300221 275. Method according to claim 4, wherein the adjustment parameters (A) further comprise an adjustment force (F) K ) and / or a setup position (P K ) for at least one basket roller (5a,…,5d).

6. Method according to any one of the preceding claims, wherein in the first step (S1) a material class (M) of the strip (4) is further recorded, which in the third step (S3) is added to the data set (D).

7. Method according to any one of the preceding claims, wherein in the first step (S1) the setting parameters (A) and the production data (P) are time-resolved in a plurality of time intervals (^ j ) with a duration of 200ms to 500ms, - whereby in the second step (S2) the radius of curvature profile (C R ) section by section according to the time intervals (^ j) is assigned to the time-resolved adjustment parameters (A) and production data (P).

8. Method according to one of the preceding claims, wherein the second step (S2) comprises the following intermediate steps: - first intermediate step (Z21): creating the two-dimensional digital image (15), - second intermediate step (Z22): detecting the end face (8) in the image (15), - third intermediate step (Z23): determining an inner and / or outer edge (12a, 12b) of the side surface (9), - fourth intermediate step (Z24): determining the coordinates (X i , X i ') the pixels corresponding to the inner and / or outer edge (12a, 12b) and arranging them in a respective data array (14a, 14b), - fifth intermediate step (Z25): determining the radius of curvature profile (C R) of the tape (4) from the data array (14a, 14b).

9. Method according to claim 8, wherein the resolution of the image (15) is dimensioned such that the tape thickness (d) is mapped onto at least three pixels of the image (15). 202300221 2810. Method according to claim 8 or 9, wherein after the second intermediate step (Z22) the image (15) is blurred in the tangential direction (R). T ) is carried out.

11. Method according to any one of claims 8 to 10, wherein the determination of the inner and / or outer edge (12a, 12b) is based on local brightness gradients in the image (15).

12. Method according to any one of claims 8 to 11, wherein after the third intermediate step (Z23) a skeletonization of the inner and / or outer edge (12a, 12b) is carried out.

13. Method according to any one of claims 8 to 12, wherein the radius of curvature profile (C) R ) is determined by ensuring that for each element (X i , X i ') of the data array (14a, 14b) the element (X i , X i') itself and additionally N before and N after the element (X i , X i ') arranged elements (X i-N ,…,X i+N , X i- N ',…,X i+N ') of the data array (14a, 14b) are selected, into the spatial coordinates of the selected elements (X i- N ,…,X i+N , X i-N ',…,X i+N ') a circle with radius (R i ) or (R i ') is fitted and the radius (R i ) or (R i ') or a combination value from (R i ) and (R i ') as a value corresponding to the radius of curvature profile (C R ) is added.

14. Method according to claim 13, wherein 50 ≤ N ≤ 200.

15. Method according to claim 13 or 14, wherein the circle is determined using a least-squares-fit method.

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