WO2002066177A1 - Method and device for determining the shape, in a longitudinal direction, of a moving strip - Google Patents

Method and device for determining the shape, in a longitudinal direction, of a moving strip Download PDF

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Publication number
WO2002066177A1
WO2002066177A1 PCT/FR2002/000470 FR0200470W WO02066177A1 WO 2002066177 A1 WO2002066177 A1 WO 2002066177A1 FR 0200470 W FR0200470 W FR 0200470W WO 02066177 A1 WO02066177 A1 WO 02066177A1
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WO
WIPO (PCT)
Prior art keywords
strip
measurements
shape
transverse
edges
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Application number
PCT/FR2002/000470
Other languages
French (fr)
Inventor
Eric Tonnon
Jean-Michel Philippe
Bertrand Schrifve
Marc Malhomme
Original Assignee
Usinor
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Publication date
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Publication of WO2002066177A1 publication Critical patent/WO2002066177A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
    • B21B38/02—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product for measuring flatness or profile of strips
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2273/00—Path parameters
    • B21B2273/04—Lateral deviation, meandering, camber of product

Definitions

  • the present invention relates to measuring the shape, in a longitudinal direction, of a moving strip, in particular of a metal sheet or strip during manufacture by rolling. It is more particularly, but not limited to, determining the curvature of the strip, which is substantially flat, in its own plane, curvature which is commonly designated by the name of "saber” by analogy with the conventional form of this weapon.
  • the saber of a rolled sheet in particular at the outlet from the roughing stand of a hot strip rolling mill, is therefore generally characterized by a deviation of the rolled strip, in its plane, and a on either side of its general longitudinal direction, this deviation being more or less wide and regular, extended over the entire length of the strip or, on the contrary, localized, generally towards the ends of the laminated strip.
  • This deformation can have several causes, either due to the very nature of the strip, and depending on its physical and dimensional characteristics before it passes through the coarse cage, or to the characteristics of the coarse cage itself. For example, it will be easily understood that a defect in the parallelism of the cylinders can induce such a defect in the strip, by causing different metal elongations between the two lateral edges of the strip.
  • the methods known measurement of the saber during the movement of the strip are based on the principle of a reconstruction of a shape from the synchronous acquisition of measurements carried out at three points spaced apart in said general longitudinal direction of travel.
  • three position sensors are arranged so as to synchronously measure the position of an edge of the strip, at three points spaced apart by a distance of the order of a few meters. From the coordinates of the three points thus determined, a calculation algorithm makes it possible to determine the local curvature of the edge of the strip, which is invariant whatever the transverse position of the strip. In other words, the determination of the curvature is not influenced by a deviation of the strip causing it to approach or move away from the sensors, deviation inevitable in the presence of a saber.
  • the synchronous measurements at three points being carried out continuously or sequentially, it is possible to deduce from the calculation of the local curvatures successively determined, and by integration over the length of the strip, the shape of the observed edge of said strip.
  • the difference between the position of a point and the line passing through the lines is determined at each synchronous acquisition carried out by the three sensors.
  • two other points which makes it possible to define the coefficients of a polynomial of degree n representative of the curve giving the shape of the edge of the strip.
  • the first problem which arises in practice is therefore to be able to determine in a synchronous manner at three points the position of an edge of the strip in movement. It is known for this to use optical type sensors detecting for example the transition between the light radiation coming from the strip and that passing near its edge. Such sensors are in particular also used for continuous measurements of the width of the moving strip.
  • FIG. 1 There is shown schematically in FIG. 1, and only by way of a simplified example, a rolling installation comprising rollers 1 of a rolling stand for a sheet or strip 2, supported downstream of the stand by rollers 3 of a conventional roller table. In this drawing there is shown the saber of the band 2 in an intentionally exaggerated manner.
  • Each gantry comprises means for detecting the position of an edge of the sheet, in order to synchronously determine the position of said edge at the same instant at each gantry.
  • the saber of the strip can be determined, by using one of the aforementioned algorithms, with an accuracy of the order of a few millimeters or even less.
  • a disadvantage of this type of installation is that it requires the use of three sets of sensors, spaced several meters apart, and therefore results in a significant bulk.
  • the installation of an additional set of sensors also poses problems of congestion which can be difficult if not even impossible to solve.
  • the present invention aims to solve these problems.
  • the intended application being essentially the detection and measurement of saber-type shape defects in strip blanks at the outlet of roughing cage, a measurement accuracy of the order of 5 mm is satisfactory, taking into account the measurement conditions and vibration disturbances inherent in the roughing cage outlet of a conventional strip train for rolling steel strips , which pass at speeds of the order of 120 to 300 m / min.
  • the invention therefore also aims to propose a new method and a new device, simpler and less expensive, for measuring the shape of such a strip.
  • the invention relates to a method for determining the shape, in a longitudinal direction and in a longitudinal plane, of a strip running along said direction, in particular of a metal sheet or strip in manufacturing course by rolling and extending in the said longitudinal plane, characterized in that, during the running: one measures, synchronously in each of two fixed planes transverse to the direction of running of the strip and spaced apart one from the other in said direction, the position of the two edges of the strip at the intersection between said longitudinal plane and each of the two transverse planes, for each measurement carried out in a transverse plane, the position of a midpoint between the two edges, representative of the transverse position of the strip in the corresponding transverse plane, these measurements are repeated on at least part the length of the strip during its travel, all of said points constituting a virtual center line of the strip, and the shape of said part of the strip is deduced from all the measurements carried out, by a calculation algorithm according to which: the slope of the straight line passing through the two points, the position of which is determined,
  • the shape of the strip can be determined by using only measurements made in two distant planes in the general longitudinal direction of the strip, whereas the prior techniques required making measurements in three successive shots in the direction of travel. Furthermore, by determining this shape from a set of points constituting a center line of the strip, and no longer an edge thereof, one is freed from all disturbances due to variations in width of the strip. The tests carried out made it possible to show that the dimensional precision of the shape finally obtained is less than 5 mm, which is sufficient in particular for the measurements particularly targeted by the present invention, concerning the determination of the saber on blanks of laminated strips, leaving the roughing cage.
  • the present invention makes it possible to dispense with a third measurement assembly placed at the outlet of the roughing stand, which significantly reduces the overall cost of the installation, and limits the problems of '' clutter.
  • Another advantage of the invention is that the two transverse planes can be located in a more restricted space than the three planes necessary in the systems according to the prior art. Consequently, the length of the strip ends, the shape of which cannot be determined because they are not seen simultaneously by the different measurement areas, is considerably reduced compared to systems requiring three measurement planes, the distance between the extreme planes, typically several meters, is more important than in the present invention, or the distance between the two planes can be reduced to less than one meter. Yet another advantage is that the number of sensors required is reduced, the number and cost of maintenance operations is also reduced.
  • the measurements are carried out at a frequency corresponding to a predetermined distance traveled by the strip between two measurements, this predetermined distance preferably being between 20 and 100 mm, and even more preferably around 50 mm , said predetermined distance can also be a sub-multiple of the distance between the two transverse measurement planes.
  • the said straight line is determined from all of the measurements carried out over the length of the strip by the method of least squares.
  • the values of the measurements carried out, or the values of the dimensions defining the position of each of the midpoints determined from these measurements are weighted according to the position, over the length tape, measured or determined points. This weighting makes it possible to take into account in determining the said average straight line the fact that the deformations of the strip are not generally distributed over its entire length, the weighting making it possible, for example, to moderate the incidence of end faults, such as we will understand it better later.
  • the invention also relates to a device for determining the shape, in a longitudinal direction and in a longitudinal plane, of a strip running along the said direction, in particular of a metal sheet or strip during manufacture by rolling and extending in said longitudinal plane, characterized in that it comprises: two measuring assemblies located in two fixed planes transverse to the direction of travel of the strip and spaced from one another in said direction, for simultaneously measuring the position of the two edges of the strip at the intersection between said longitudinal plane and each of the two transverse planes, control means for controlling measurements synchronous positions of the edges of the strip in each of said transverse planes, at a predetermined frequency, and calculation means for deducing the shape of the strip from all the measurements carried out, by running a calculation algorithm and including:
  • the measuring assemblies comprise means for optical measurement of the position of the two edges of the strip in each of said planes.
  • FIG. 1 is a simplified view of a measuring installation according to the prior art, already described at the beginning of this thesis
  • FIG. 2 is a simplified view of a measurement installation in accordance with the present invention
  • Figure 3 is a schematic view illustrating the method of measuring the transverse position of the strip
  • Figure 4 is an enlarged schematic view illustrating the principle of the synchronous acquisition of the position of the edges and the determination of the position of the center line L1 of the strip blank.
  • FIG. 2 there is shown a blank 20 of strip during rolling in a roughing stand 10 equipped with rolling cylinders 11 counter-rotating and rotated in a manner known per se.
  • the strip runs in the direction of arrow F, typically at a speed of the order of 120 to 300 m per minute.
  • the strip 20 is supported by rollers 30 of a roller table also of known type.
  • a first measuring assembly 41 is placed, in a first transverse plane PT1
  • a second measuring assembly is placed in a second transverse plane PT2, parallel to and distant from PTl approximately 0.75 m for example, the said measuring assemblies being themselves typically located at a distance of a few meters downstream of the cage 10.
  • the measuring assemblies 41 and 42 are, for example, optical devices for measuring the width of the strip, such as stereoscopic width measuring gauges. Devices of this type are known, and it will only be recalled here that they are typically equipped with detectors with linear sensors making it possible to detect a transition of light radiation at the edges of the strip, thus making it possible to locate, with a precision of the order of a millimeter, the transverse position of each bank perpendicular to each device, therefore in each of the planes PT1 and PT2, as illustrated in FIG. 3.
  • the two sets of measurements 41 and 42 are connected to a computer 43, which controls the measurement sequences and which can itself be connected to the cage 10 to control the conventional actuators for adjusting said cage.
  • Each measurement gauge permanently determines the position of the two edges of the strip in the respective plane of the gauge.
  • the measurement gauge 41 supplies the dimensions C1 and C3 of the two banks in a fixed reference point of the installation, in the plane PT1; the measurement gauge 42 provides the dimensions C2 and C4 of the two banks in the plane PT2.
  • the computer carries out acquisitions of the measured values, in synchronism in the two planes, and with an undersampling of the distance between the two planes PT1 and PT2.
  • fifteen acquisitions are made for example while the strip travels a distance equal to the distance between the two planes PT1 and PT2, which corresponds in the example considered to acquisitions made approximately every 50 mm, that is to say, taking into account with a running speed between 120 and 300 m per minute, at a frequency of 40 to 100 acquisitions per second.
  • the position of a midpoint Bl, B2, equidistant from the two edges and situated in this plane is determined, the set of these points constituting a line Longitudinal center of the strip.
  • the shape of the strip is then determined, considering that it is the shape of the said center line L1, by a calculation algorithm according to which, y k (n) being the n-th position of the midpoint representative of the position of the strip, determined from the measurements made by gauge number k, and E being the distance between the two gauges (see FIG.
  • f (n) 1 / E * [y 2 ( n) - y ⁇ (n)] which corresponds to the slope, in the absolute fixed frame of reference of the installation, of the straight line passing through the points Bl and B2 whose positions are calculated during each acquisition of measurement. It will be noted that this value is insensitive to the offset of the strip on the roller table, that is to say that the same value of the said pseudo-derivative would be obtained if the strip were offset laterally.
  • the weighting is used to define more precisely the zone of the strip on which the strip is considered to be rectilinear.
  • the weighting will aim to reduce the influence of the high values of position deviations measured on said ends, compared to the low values of deviations measured in the substantially rectilinear intermediate part.
  • the general direction of the strip will be considered to be that defined by the said rectilinear intermediate part, and the extreme saber zones will be well defined by their increasing deviation from this mean straight line Dl.
  • the possible weighting will be less marked, and defined so that the medium straight line giving the general direction of the strip, ie a cord intersecting the said arc and not a cord connecting its ends.
  • this straight line Dl would be precisely as illustrated in FIG. 3, that is to say exactly according to the direction of travel, it would not be necessary to define said straight line by calculation from the measurements carried out .
  • this is not possible due to the many parameters that can be taken into account to define the shape of the strip and its trajectory, and it is therefore necessary to estimate the direction of this straight line representing the general longitudinal direction of the strip from the position measurements made in order to then be able to determine the value of the saber in relation to this straight line.
  • This operation makes it possible in fact to carry out a change of coordinate system to pass from the absolute fixed coordinate system constituted by the installation and in which the position measurements are carried out, to a relative coordinate system linked to the strip itself.
  • sampling frequency may be modified, in particular as a function of the tape speed.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)

Abstract

The invention relates to a synchronous measurement method using two planes (PT1, PT2) which are transversal to the moving direction (F) of a strip, particularly a metal strip undergoing production by rolling, and which are spaced out from each other in said direction. The position of the two edges of the strip is measured thus at the intersection between said longitudinal plane and each of said transverse planes and the position of a midpoint (B1, B2) between the two edges is deduced, which is representative of the transverse position of the strip in the corresponding transverse plane. Said measurements are taken again along at least part of the length of the strip as it moves, all of said points forming a virtual centre line (L1) of the strip. The shape of said part of the strip is deduced from all of the measurements taken using a calculation algorithm according to which: for each pair of synchronous measurements, the slope of the line passing through the two points (B1, B2) is calculated, the position of said points being determined; the calculated slope values are subsequently integrated on said part of the length of the strip; the shape of the curved line (L1) is deduced.

Description

Procédé et dispositif de détermination de la forme, selon une direction longitudinale, d'une bande en défilement. Method and device for determining the shape, in a longitudinal direction, of a moving strip.
La présente invention concerne la mesure de la forme, selon une direction longitudinale, d'une bande en défilement, notamment d'une tôle ou bande métallique en cours de fabrication par laminage. Elle s'adresse plus particulièrement, mais non limitativement, à la détermination de la courbure de la bande, sensiblement plate, dans son propre plan, courbure que l'on désigne couramment sous le nom de « sabre » par analogie avec la forme classique de cette arme. Le sabre d'une tôle laminée, en particulier au niveau de la sortie de la cage dégrossisseuse d'un laminoir à bandes à chaud, se caractérise donc de manière générale par une déviation de la bande laminée, dans son plan, et d'un côté ou de l'autre de sa direction longitudinale générale, cette déviation étant plus ou moins ample et régulière, étendue sur toute la longueur de la bande ou au contraire localisée, en général vers les extrémités de la bande laminée. Cette déformation peut avoir plusieurs causes, tenant soit à la nature même de la bande, et dépendant de ses caractéristiques physiques et dimensionnelles avant son passage dans la cage dégrossisseuse, soit aux caractéristiques de la cage dégrossisseuse elle-même. Par exemple, on comprendra facilement qu'un défaut de parallélisme des cylindres puisse induire un tel défaut dans la bande, en provoquant des allongements de métal différents entre les deux bords latéraux de la bande .The present invention relates to measuring the shape, in a longitudinal direction, of a moving strip, in particular of a metal sheet or strip during manufacture by rolling. It is more particularly, but not limited to, determining the curvature of the strip, which is substantially flat, in its own plane, curvature which is commonly designated by the name of "saber" by analogy with the conventional form of this weapon. The saber of a rolled sheet, in particular at the outlet from the roughing stand of a hot strip rolling mill, is therefore generally characterized by a deviation of the rolled strip, in its plane, and a on either side of its general longitudinal direction, this deviation being more or less wide and regular, extended over the entire length of the strip or, on the contrary, localized, generally towards the ends of the laminated strip. This deformation can have several causes, either due to the very nature of the strip, and depending on its physical and dimensional characteristics before it passes through the coarse cage, or to the characteristics of the coarse cage itself. For example, it will be easily understood that a defect in the parallelism of the cylinders can induce such a defect in the strip, by causing different metal elongations between the two lateral edges of the strip.
On comprendra donc aussi que la mesure du sabre sur la bande en cours de défilement permet de corriger le plus rapidement possible un tel défaut dés son apparition, en agissant sur les actionneurs de réglage du laminoir.It will therefore also be understood that the measurement of the saber on the strip being scrolled makes it possible to correct such a defect as soon as possible as soon as it appears, by acting on the adjustment actuators of the rolling mill.
Actuellement, de manière générale, les méthodes connues de mesure du sabre pendant le défilement de la bande reposent sur le principe d'une reconstitution d'une forme à partir de l'acquisition synchrone de mesures effectuées en trois points espacés selon la dite direction longitudinale générale de défilement.Currently, in general, the methods known measurement of the saber during the movement of the strip are based on the principle of a reconstruction of a shape from the synchronous acquisition of measurements carried out at three points spaced apart in said general longitudinal direction of travel.
Par exemple, trois capteurs de position sont disposés de manière à mesurer en synchronisme la position d'un bord de la bande, en trois points espacés d'une distance de l'ordre de quelques mètres. A partir des coordonnées des trois points ainsi déterminés, un algorithme de calcul permet de déterminer la courbure locale du bord de la bande, laquelle est invariante quelle que soit la position transversale de la bande. Autrement dit, la détermination de la courbure n'est pas influencée par une déviation de la bande la faisant se rapprocher ou s'éloigner des capteurs, déviation inévitable en présence d'un sabre. Les mesures synchrones en trois points étant effectuées en continu ou séquentiellement, on peut déduire du calcul des courbures locales successivement déterminées, et par intégration sur la longueur de la bande, la forme du bord observé de la dite bande.For example, three position sensors are arranged so as to synchronously measure the position of an edge of the strip, at three points spaced apart by a distance of the order of a few meters. From the coordinates of the three points thus determined, a calculation algorithm makes it possible to determine the local curvature of the edge of the strip, which is invariant whatever the transverse position of the strip. In other words, the determination of the curvature is not influenced by a deviation of the strip causing it to approach or move away from the sensors, deviation inevitable in the presence of a saber. The synchronous measurements at three points being carried out continuously or sequentially, it is possible to deduce from the calculation of the local curvatures successively determined, and by integration over the length of the strip, the shape of the observed edge of said strip.
Selon une autre méthode similaire, au lieu de calculer successivement les courbures locales puis procéder à une intégration des valeurs obtenues, on détermine à chaque acquisition synchrone effectuée par les trois capteurs l'écart entre la position d'un point et la droite passant par les deux autres points, ce qui permet de définir les coefficients d'un polynôme de degré n représentatif de la courbe donnant la forme du bord de la bande .According to another similar method, instead of successively calculating the local curvatures and then integrating the values obtained, the difference between the position of a point and the line passing through the lines is determined at each synchronous acquisition carried out by the three sensors. two other points, which makes it possible to define the coefficients of a polynomial of degree n representative of the curve giving the shape of the edge of the strip.
Le premier problème qui se pose dans la pratique est donc de pouvoir déterminer de manière synchrone en trois points la position d'un bord de la bande en défilement. Il est connu pour cela d'utiliser des capteurs de type optique détectant par exemple la transition entre le rayonnement lumineux issu de la bande et celui passant à côté de sa rive. De tels capteurs sont notamment utilisés également pour des mesures en continu de la largeur de la bande en défilement. On a représenté de manière schématique sur la figure 1, et uniquement à titre d'exemple simplifié, une installation de laminage comportant des rouleaux 1 d'une cage de laminage d'une tôle ou bande 2, supportée en aval de la cage par des rouleaux 3 d'une table à rouleaux classique. Sur ce dessin on a représenté le sabre de la bande 2 de manière volontairement exagérée. Trois portiques de mesure 4 enjambent le chemin de roulement et donc la bande laminée, en étant espacés l'un de l'autre d'une distance voisine de 4 m . Chaque portique comporte des moyens de détection de la position d'un bord de la tôle, pour déterminer de manière synchrone la position du dit bord au même instant au niveau de chaque portique.The first problem which arises in practice is therefore to be able to determine in a synchronous manner at three points the position of an edge of the strip in movement. It is known for this to use optical type sensors detecting for example the transition between the light radiation coming from the strip and that passing near its edge. Such sensors are in particular also used for continuous measurements of the width of the moving strip. There is shown schematically in FIG. 1, and only by way of a simplified example, a rolling installation comprising rollers 1 of a rolling stand for a sheet or strip 2, supported downstream of the stand by rollers 3 of a conventional roller table. In this drawing there is shown the saber of the band 2 in an intentionally exaggerated manner. Three measuring gantries 4 span the raceway and therefore the laminated strip, being spaced from each other by a distance close to 4 m. Each gantry comprises means for detecting the position of an edge of the sheet, in order to synchronously determine the position of said edge at the same instant at each gantry.
A partir des mesures effectuées avec une telle installation, on peut déterminer le sabre de la bande, par utilisation de l'un des algorithmes précités, avec une précision de l'ordre de quelques millimètres ou même moins .From the measurements made with such an installation, the saber of the strip can be determined, by using one of the aforementioned algorithms, with an accuracy of the order of a few millimeters or even less.
Un inconvénient de ce type d'installation est qu'il nécessite l'utilisation de trois ensembles de capteurs, espacés de plusieurs mètres, et donc entraîne un encombrement important . De plus , même lorsque des portiques tels que ceux mentionnés ci-dessus existent déjà dans une installation industrielle pour faire par exemple des mesures de largeur de bande, l'implantation d'un ensemble de capteurs supplémentaire pose aussi des problèmes d'encombrement qui peuvent être difficiles sinon même impossibles à résoudre.A disadvantage of this type of installation is that it requires the use of three sets of sensors, spaced several meters apart, and therefore results in a significant bulk. In addition, even when gantries such as those mentioned above already exist in an industrial installation for making bandwidth measurements for example, the installation of an additional set of sensors also poses problems of congestion which can be difficult if not even impossible to solve.
La présente invention vise à résoudre ces problêmes. En particulier, l'application visée étant essentiellement la détection et la mesure de défauts de forme de type sabre des ébauches de bande en sortie de cage dégrossisseuse, une précision de mesure de l'ordre de 5 mm est satisfaisante, compte tenu des conditions de mesure et des perturbations vibratoires inhérentes au niveau de la sortie de cage dégrossisseuse d'un train à bande classique pour le laminage de bandes en acier, qui défilent à des vitesses de l'ordre de 120 à 300 m/mn.The present invention aims to solve these problems. In particular, the intended application being essentially the detection and measurement of saber-type shape defects in strip blanks at the outlet of roughing cage, a measurement accuracy of the order of 5 mm is satisfactory, taking into account the measurement conditions and vibration disturbances inherent in the roughing cage outlet of a conventional strip train for rolling steel strips , which pass at speeds of the order of 120 to 300 m / min.
Cependant, des problèmes d'encombrement similaires peuvent se poser pour des moyens de mesure d'autres caractéristiques géométriques que le sabre, et donc de manière générale pour la mesure de la forme, selon une direction longitudinale, d'une bande en défilement, notamment d'une tôle ou bande métallique en cours de fabrication par laminage. L'invention vise donc également à proposer un nouveau procédé et un nouveau dispositif, plus simple et moins onéreux, de mesure de la forme d'une telle bande.However, similar dimensions problems can arise for means for measuring other geometrical characteristics than the saber, and therefore generally for measuring the shape, in a longitudinal direction, of a moving strip, in particular of a metal sheet or strip during manufacture by rolling. The invention therefore also aims to propose a new method and a new device, simpler and less expensive, for measuring the shape of such a strip.
Avec ces objectifs en vue, l'invention a pour objet un procédé de détermination de la forme, selon une direction longitudinale et dans un plan longitudinal, d'une bande en défilement selon la dite direction, notamment d'une tôle ou bande métallique en cours de fabrication par laminage et s 'étendant dans le dit plan longitudinal, caractérisé en ce que, au cours du défilement : on mesure, de manière synchrone dans chacun de deux plans fixes transversaux à la direction du défilement de la bande et espacés l'un de l'autre selon la dite direction, la position des deux bords de la bande à l'intersection entre le dit plan longitudinal et chacun des deux plans transversaux, pour chaque mesure effectuée dans un plan transversal, on détermine la position d'un point médian entre les deux bords, représentatif de la position transversale de la bande dans le plan transversal correspondant, on renouvelle ces mesures sur au moins une partie de la longueur de la bande au cours de son défilement, l'ensemble des dits points constituant une ligne virtuelle médiane de la bande, et on déduit la forme de la dite partie de la bande à partir de l'ensemble des mesures effectuées, par un algorithme de calcul selon lequel : on calcule pour chaque couple de mesures synchrones la pente de la droite passant par les deux points dont la position est déterminée, - puis on effectue une intégration sur la dite partie de la longueur de la bande des valeurs de pentes calculées en prenant comme pas d'intégration la distance parcourue par la bande entre deux mesures successives,With these objectives in view, the invention relates to a method for determining the shape, in a longitudinal direction and in a longitudinal plane, of a strip running along said direction, in particular of a metal sheet or strip in manufacturing course by rolling and extending in the said longitudinal plane, characterized in that, during the running: one measures, synchronously in each of two fixed planes transverse to the direction of running of the strip and spaced apart one from the other in said direction, the position of the two edges of the strip at the intersection between said longitudinal plane and each of the two transverse planes, for each measurement carried out in a transverse plane, the position of a midpoint between the two edges, representative of the transverse position of the strip in the corresponding transverse plane, these measurements are repeated on at least part the length of the strip during its travel, all of said points constituting a virtual center line of the strip, and the shape of said part of the strip is deduced from all the measurements carried out, by a calculation algorithm according to which: the slope of the straight line passing through the two points, the position of which is determined, is calculated for each pair of synchronous measurements, then an integration is carried out on said part of the length of the band of the values of slopes calculated by taking the distance traveled by the strip between two successive measurements as integration step,
- et on en déduit la forme de la ligne courbe reliant les différents points dont la position a été déterminée .- and we deduce the shape of the curved line connecting the different points whose position has been determined.
Ainsi, on peut déterminer la forme de la bande, ou au moins une forme approchante, en utilisant uniquement des mesures effectuées dans deux plans distants selon la direction longitudinale générale de la bande, alors que les techniques antérieures nécessitaient d'effectuer des mesures dans trois plans successifs selon la direction de défilement. Par ailleurs, en déterminant cette forme à partir d'un ensemble de points constituant une ligne médiane de la bande, et non plus un bord de celle-ci, on s'affranchit de toutes perturbations dues à des variations de largeur de la bande. Les essais effectués ont permis de montrer que la précision dimensionnelle de la forme finalement obtenue est inférieure à 5 mm, ce qui est suffisant en particulier pour les mesures particulièrement visées par la présente invention, concernant la détermination du sabre sur des ébauches de bandes laminées, en sortie de cage dégrossisseuse. Si la précision de mesure n'est pas accrue par rapport aux méthodes antérieures, la présente invention permet par contre de s'affranchir d'un troisième ensemble de mesure placé à la sortie de la cage dégrossisseuse, ce qui réduit notablement le coût global de l'installation, et limite les problèmes d' encombrement .Thus, the shape of the strip, or at least one approaching shape, can be determined by using only measurements made in two distant planes in the general longitudinal direction of the strip, whereas the prior techniques required making measurements in three successive shots in the direction of travel. Furthermore, by determining this shape from a set of points constituting a center line of the strip, and no longer an edge thereof, one is freed from all disturbances due to variations in width of the strip. The tests carried out made it possible to show that the dimensional precision of the shape finally obtained is less than 5 mm, which is sufficient in particular for the measurements particularly targeted by the present invention, concerning the determination of the saber on blanks of laminated strips, leaving the roughing cage. If the measurement accuracy is not increased compared to previous methods, the present invention on the other hand makes it possible to dispense with a third measurement assembly placed at the outlet of the roughing stand, which significantly reduces the overall cost of the installation, and limits the problems of '' clutter.
Un autre avantage de l'invention est que les deux plans transversaux peuvent être situés dans un espace plus restreint que les trois plans nécessaires dans les systèmes selon l'art antérieur. En conséquence la longueur des extrémités de bande, dont la forme ne peut être déterminée parce qu'elles ne sont pas vues simultanément par les différents zones de mesures, est notablement réduite par rapport aux systèmes nécessitant trois plans de mesure, dont la distance entre les plans extrêmes, classiquement de plusieurs mètres, est plus importante que dans la présente invention, ou la distance entre les deux plans peut être réduite à moins d'un mètre. Un autre avantage encore est que le nombre de capteurs nécessaires étant réduit, le nombre et le coût des opérations de maintenance se trouve également réduit .Another advantage of the invention is that the two transverse planes can be located in a more restricted space than the three planes necessary in the systems according to the prior art. Consequently, the length of the strip ends, the shape of which cannot be determined because they are not seen simultaneously by the different measurement areas, is considerably reduced compared to systems requiring three measurement planes, the distance between the extreme planes, typically several meters, is more important than in the present invention, or the distance between the two planes can be reduced to less than one meter. Yet another advantage is that the number of sensors required is reduced, the number and cost of maintenance operations is also reduced.
Selon d'autres dispositions de la présente invention : les mesures sont effectuées à une fréquence correspondant à une distance prédéterminée parcourue par la bande entre deux mesures, cette distance prédéterminée étant préférentiellement comprise entre 20 et 100 mm, et encore préférentiellement d'environ 50 mm, la dite distance prédéterminée pouvant être par ailleurs un sous multiple de la distance entre les deux plans transversaux de mesure .According to other provisions of the present invention: the measurements are carried out at a frequency corresponding to a predetermined distance traveled by the strip between two measurements, this predetermined distance preferably being between 20 and 100 mm, and even more preferably around 50 mm , said predetermined distance can also be a sub-multiple of the distance between the two transverse measurement planes.
- pour déterminer et évaluer la forme de la bande, on définit à partir de l'ensemble des mesures une droite représentative de la direction longitudinale moyenne de la bande sur la partie de longueur de bande considérée, la forme de la bande étant définie par comparaison de la ligne courbe constituée par la suite des points par rapport à la dite droite, la distance des points de la courbe par rapport à cette droite résultant de l'algorithme de calcul.- to determine and evaluate the shape of the strip, we define from the set of measurements a straight line representative of the mean longitudinal direction of the strip on the part of the strip length considered, the shape of the strip being defined by comparison of the curved line formed thereafter of the points relative to said straight line, the distance of the points of the curve relative to this straight line resulting of the calculation algorithm.
- préférentiellement, la dite droite est déterminée à partir de l'ensemble des mesures effectuées sur la longueur de la bande par la méthode des moindres carrés . Selon une disposition particulière, pour la détermination de la dite droite, on pondère les valeurs des mesures effectuées, ou les valeurs des cotes définissant la position de chacun des points médians déterminés à partir de ces mesures, en fonction de la position, sur la longueur de la bande, des points mesurés ou déterminés. Cette pondération permet de tenir compte dans la détermination de la dite droite moyenne du fait que les déformations de la bande ne sont pas en général réparties sur toute sa longueur, la pondération permettant par exemple de modérer l'incidence des défauts d'extrémités, comme on le comprendra mieux par la suite.- Preferably, the said straight line is determined from all of the measurements carried out over the length of the strip by the method of least squares. According to a particular arrangement, for the determination of the said straight line, the values of the measurements carried out, or the values of the dimensions defining the position of each of the midpoints determined from these measurements, are weighted according to the position, over the length tape, measured or determined points. This weighting makes it possible to take into account in determining the said average straight line the fact that the deformations of the strip are not generally distributed over its entire length, the weighting making it possible, for example, to moderate the incidence of end faults, such as we will understand it better later.
L'invention a aussi pour objet un dispositif de détermination de la forme, selon une direction longitudinale et dans un plan longitudinal, d'une bande en défilement selon la dite direction, notamment d'une tôle ou bande métallique en cours de fabrication par laminage et s ' étendant dans le dit plan longitudinal , caractérisé en ce qu'il comporte : deux ensembles de mesure situés dans deux plans fixes transversaux à la direction du défilement de la bande et espacés l'un de l'autre selon la dite direction, pour mesurer simultanément la position des deux bords de la bande à l'intersection entre le dit plan longitudinal et chacun des deux plans transversaux, des moyens de commande pour commander des mesures synchrones des positions des bords de la bande dans chacun desdits plans transversaux, à une fréquence prédéterminée, et des moyens de calcul pour déduire la forme de la bande à partir de l'ensemble des mesures effectuées, par déroulement d'un algorithme de calcul et comprenant :The invention also relates to a device for determining the shape, in a longitudinal direction and in a longitudinal plane, of a strip running along the said direction, in particular of a metal sheet or strip during manufacture by rolling and extending in said longitudinal plane, characterized in that it comprises: two measuring assemblies located in two fixed planes transverse to the direction of travel of the strip and spaced from one another in said direction, for simultaneously measuring the position of the two edges of the strip at the intersection between said longitudinal plane and each of the two transverse planes, control means for controlling measurements synchronous positions of the edges of the strip in each of said transverse planes, at a predetermined frequency, and calculation means for deducing the shape of the strip from all the measurements carried out, by running a calculation algorithm and including:
- des moyens pour déterminer, à partir des mesures de position des bords, la position d'un point médian entre les deux bords, représentatif de la position transversale de la bande dans le plan transversal correspondant,means for determining, from the position measurements of the edges, the position of a midpoint between the two edges, representative of the transverse position of the strip in the corresponding transverse plane,
- des moyens pour déterminer pour chaque couple de mesures synchrones la pente de la droite passant par les deux points dont la position est déterminée, - des moyens subséquents pour effectuer une intégration selon la longueur de la bande des valeurs de pentes calculées, prenant comme pas d'intégration la distance parcourue par la bande entre deux mesures successives, - et des moyens pour déduire la forme de la courbe reliant les différents points dont la position a été déterminée.- means for determining for each pair of synchronous measurements the slope of the straight line passing through the two points whose position is determined, - subsequent means for carrying out an integration along the length of the strip of the calculated slope values, taking as a step integrating the distance traveled by the strip between two successive measurements, - and means for deducing the shape of the curve connecting the different points whose position has been determined.
Selon une disposition préférée, les ensembles de mesure comportent des moyens de mesure optique de la position des deux bords de la bande dans chacun des dits plans .According to a preferred arrangement, the measuring assemblies comprise means for optical measurement of the position of the two edges of the strip in each of said planes.
D'autres caractéristiques et avantages apparaîtront dans la description qui va être faite d'une installation de détermination du sabre sur une ébauche de bande en acier en sortie d'une cage dégrossisseuse d'un train de laminoir, et de sa mise en oeuvre.Other characteristics and advantages will appear in the description which will be given of an installation for determining the saber on a rough steel strip leaving a roughing stand of a rolling mill train, and of its implementation.
On se reportera aux dessins annexés dans lesquels : - la figure 1 est une vue simplifiée d'une installation de mesure selon l'art antérieur, déjà décrite au début de ce mémoire, la figure 2 est une vue simplifiée d'une installation de mesure conforme à la présente invention,Reference will be made to the appended drawings in which: FIG. 1 is a simplified view of a measuring installation according to the prior art, already described at the beginning of this thesis, FIG. 2 is a simplified view of a measurement installation in accordance with the present invention,
- la figure 3 est une vue schématique illustrant la méthode de mesure de la position transversale de la bande, la figure 4 est une vue schématique agrandie illustrant le principe de l'acquisition synchrone de la position des bords et de la détermination de la position de la ligne médiane Ll de l'ébauche de bande.- Figure 3 is a schematic view illustrating the method of measuring the transverse position of the strip, Figure 4 is an enlarged schematic view illustrating the principle of the synchronous acquisition of the position of the edges and the determination of the position of the center line L1 of the strip blank.
Sur le dessin de la figure 2, on a représenté une ébauche 20 de bande en cours de laminage dans une cage dégrossisseuse 10 équipée de cylindres de laminage 11 contra-rotatifs et entraînés en rotation de manière connue en soi. La bande défile selon la direction de la flèche F, typiquement à une vitesse de l'ordre de 120 à 300 m par minute. En sortie de la cage 10, la bande 20 est supportée par des rouleaux 30 d'une table à rouleau également de type connu.In the drawing of Figure 2, there is shown a blank 20 of strip during rolling in a roughing stand 10 equipped with rolling cylinders 11 counter-rotating and rotated in a manner known per se. The strip runs in the direction of arrow F, typically at a speed of the order of 120 to 300 m per minute. At the exit from the cage 10, the strip 20 is supported by rollers 30 of a roller table also of known type.
Dans une position intermédiaire entre deux rouleaux 30, un premier ensemble de mesure 41 est placé, dans un premier plan transversal PTl, et un deuxième ensemble de mesure est placé dans un deuxième plan transversal PT2, parallèle à PTl, et distant de celui-ci d'environ 0,75 m par exemple, les dits ensembles de mesure étant eux mêmes typiquement situés à une distance de quelques mètres en aval de la cage 10.In an intermediate position between two rollers 30, a first measuring assembly 41 is placed, in a first transverse plane PT1, and a second measuring assembly is placed in a second transverse plane PT2, parallel to and distant from PTl approximately 0.75 m for example, the said measuring assemblies being themselves typically located at a distance of a few meters downstream of the cage 10.
Les ensembles de mesure 41 et 42 sont par exemple des dispositifs de mesure optique de largeur de la bande, tels que des jauges stéréoscopiques de mesure de largeur. Des dispositifs de ce type sont connus, et on rappellera seulement ici qu'ils sont typiquement équipés de détecteurs à capteurs linéaires permettant de détecter une transition d'un rayonnement lumineux au niveau des rives de la bande, permettant donc de situer, avec une précision de l'ordre du millimètre, la position transversale de chaque rive à l'aplomb de chaque dispositif, donc dans chacun des plans PTl et PT2, comme on l'a illustré figure 3. Les deux ensembles de mesures 41 et 42 sont reliés à un calculateur 43, qui pilote les séquences de mesure et qui peut être lui même relié à la cage 10 pour piloter les actionneurs classiques de réglage de ladite cage.The measuring assemblies 41 and 42 are, for example, optical devices for measuring the width of the strip, such as stereoscopic width measuring gauges. Devices of this type are known, and it will only be recalled here that they are typically equipped with detectors with linear sensors making it possible to detect a transition of light radiation at the edges of the strip, thus making it possible to locate, with a precision of the order of a millimeter, the transverse position of each bank perpendicular to each device, therefore in each of the planes PT1 and PT2, as illustrated in FIG. 3. The two sets of measurements 41 and 42 are connected to a computer 43, which controls the measurement sequences and which can itself be connected to the cage 10 to control the conventional actuators for adjusting said cage.
On va maintenant décrire une méthode typique de détermination du sabre de la bande 20.We will now describe a typical method for determining the saber of band 20.
Chaque jauge de mesure détermine en permanence la position des deux rives de la bande dans le plan respectif de la jauge. Ainsi la jauge de mesure 41 fournit les cotes Cl et C3 des deux rives dans un repère fixe de l'installation, dans le plan PTl ; la jauge de mesure 42 fournit les cotes C2 et C4 des deux rives dans le plan PT2.Each measurement gauge permanently determines the position of the two edges of the strip in the respective plane of the gauge. Thus the measurement gauge 41 supplies the dimensions C1 and C3 of the two banks in a fixed reference point of the installation, in the plane PT1; the measurement gauge 42 provides the dimensions C2 and C4 of the two banks in the plane PT2.
Au cours du défilement de la bande, le calculateur effectue des acquisitions des valeurs mesurées, en synchronisme dans les deux plans, et avec un sur- échantillonage sous-multiple de la distance entre les deux plans PTl et PT2. Ainsi, on effectue par exemple quinze acquisitions pendant que la bande parcourt une distance égale à la distance entre les deux plans PTl et PT2, ce qui correspond dans l'exemple considéré à des acquisitions effectuées environ tous les 50 mm, soit encore, compte tenu d'une vitesse de défilement comprise entre 120 et 300 m par minute, à une fréquence de 40 à 100 acquisitions par seconde.During the running of the strip, the computer carries out acquisitions of the measured values, in synchronism in the two planes, and with an undersampling of the distance between the two planes PT1 and PT2. Thus, fifteen acquisitions are made for example while the strip travels a distance equal to the distance between the two planes PT1 and PT2, which corresponds in the example considered to acquisitions made approximately every 50 mm, that is to say, taking into account with a running speed between 120 and 300 m per minute, at a frequency of 40 to 100 acquisitions per second.
Puis on détermine, pour chaque couple de mesures de la position des bords dans un même plan transversal, la position d'un point médian Bl, B2 , equidistant des deux bords et situé dans ce plan, l'ensemble de ces points constituant une ligne Ll longitudinale médiane de la bande . La forme de la bande est ensuite déterminée, en considérant qu'elle est la forme de la dite ligne médiane Ll, par un algorithme de calcul selon lequel, yk(n) étant la n-ième position du point médian représentatif de la position de la bande, déterminé à partir des mesures effectuées par la jauge numéro k, et E étant la distance entre les deux jauges (voir figure 4) , on calcule une pseudo dérivée : f (n) = 1/E *[ y2(n) - yλ (n) ] qui correspond à la pente, dans le repère fixe absolu de l'installation, de la droite passant par les points Bl et B2 dont les positions sont calculées lors de chaque acquisition de mesure. On notera que cette valeur est insensible au déport de la bande sur la table à rouleau, c'est à dire que la même valeur de la dite pseudo-dérivée serait obtenue si la bande était décalée latéralement .Then, for each pair of measurements of the position of the edges in the same transverse plane, the position of a midpoint Bl, B2, equidistant from the two edges and situated in this plane, is determined, the set of these points constituting a line Longitudinal center of the strip. The shape of the strip is then determined, considering that it is the shape of the said center line L1, by a calculation algorithm according to which, y k (n) being the n-th position of the midpoint representative of the position of the strip, determined from the measurements made by gauge number k, and E being the distance between the two gauges (see FIG. 4), a pseudo derivative is calculated: f (n) = 1 / E * [y 2 ( n) - y λ (n)] which corresponds to the slope, in the absolute fixed frame of reference of the installation, of the straight line passing through the points Bl and B2 whose positions are calculated during each acquisition of measurement. It will be noted that this value is insensitive to the offset of the strip on the roller table, that is to say that the same value of the said pseudo-derivative would be obtained if the strip were offset laterally.
Puis, ayant ainsi pour chaque acquisition effectuée par le calculateur aux instants t0, t0+1, t0+2, ...., une valeur de la dite pseudo-dérivée au point dont la position est déterminée lors de cette acquisition, on effectue une intégration des pseudo-dérivées sur la longueur de la bande par la méthode des trapèzes en utilisant un pas correspondant au pas d'échantillonnage des mesures, c'est à dire la distance Pech parcourue par la bande entre deux mesures, et on obtient la forme estimée de la ligne Ll, donc de la bande :Then, thus having for each acquisition carried out by the computer at times t 0 , t 0 + 1 , t 0 + 2 , ...., a value of said pseudo-derivative at the point whose position is determined during this acquisition , an integration of the pseudo-derivatives is carried out over the length of the strip by the trapezoid method using a step corresponding to the sampling step of the measurements, that is to say the distance P ech traveled by the strip between two measurements, and we obtain the estimated form of the line L1, therefore of the strip:
« y(n) = Pech *.∑/(w) m=\"Y (n) = P ech * .∑ / (w) m = \
Ayant déterminé l'ensemble de points formant la ligne Ll sensiblement médiane de la bande, on peut déterminer par la méthode des moindres carrés pondérés une droite moyenne que l'on considérera être la droite définissant la direction générale ou moyenne de la bande sur toute sa longueur, ou au moins sur la longueur prise en compte pour la mesure.Having determined the set of points forming the substantially median line L1 of the strip, it is possible to determine by the weighted least squares method an average straight line which will be considered to be the straight line defining the general or average direction of the strip over its whole length, or at least the length taken into account for the measurement.
La pondération sert à définir plus précisément la zone de la bande sur laquelle la bande est considérée être rectiligne. Ainsi, par exemple, dans le cas d'une bande où l'on constate une zone intermédiaire 20a sensiblement rectiligne et de grande longueur entourée par des zones d'extrémités 20b courtes mais où le sabre est important et forme des déviations de sens contraires, comme illustré de manière volontairement exagérée sur la figure 3, la pondération visera à minorer l'influence des valeurs élevées d'écarts de positions mesurées sur les dites extrémités, par rapport aux valeurs faibles d'écarts mesurées dans la partie intermédiaire sensiblement rectiligne. Ainsi, la direction générale de la bande sera considérée bien être celle définie par la dite partie intermédiaire rectiligne, et les zones extrêmes en sabre seront bien définies par leur écart croissant par rapport à cette droite moyenne Dl. Dans un autre cas considéré à titre d'exemple, où la bande aurait un sabre de sens constant sur toute sa longueur, c'est à dire en forme générale d'arc, la pondération éventuelle sera moins marquée, et définie de manière que la droite moyenne donnant la direction générale de la bande soit une corde intersectant le dit arc et non une corde reliant ses extrémités.The weighting is used to define more precisely the zone of the strip on which the strip is considered to be rectilinear. Thus, for example, in the case of a strip where there is an intermediate zone 20a which is substantially straight and of great length surrounded by short end zones 20b but where the saber is large and forms deviations in opposite directions, as illustrated in a deliberately exaggerated manner in FIG. 3, the weighting will aim to reduce the influence of the high values of position deviations measured on said ends, compared to the low values of deviations measured in the substantially rectilinear intermediate part. Thus, the general direction of the strip will be considered to be that defined by the said rectilinear intermediate part, and the extreme saber zones will be well defined by their increasing deviation from this mean straight line Dl. In another case considered as an example, where the strip would have a saber with a constant direction over its entire length, that is to say in the general shape of an arc, the possible weighting will be less marked, and defined so that the medium straight line giving the general direction of the strip, ie a cord intersecting the said arc and not a cord connecting its ends.
On notera encore que dans le cas théorique où cette droite Dl serait précisément comme illustré sur la figure 3, c'est à dire exactement selon la direction de défilement, il ne serait pas nécessaire de définir la dite droite par calcul à partir des mesures effectuées. Dans la pratique, cela n'est pas possible du fait des nombreux paramètres pouvant entrer en compte pour définir la forme de la bande et sa trajectoire, et il est donc nécessaire d'estimer la direction de cette droite représentant la direction longitudinale générale de la bande à partir des mesures de positions effectuées pour pouvoir ensuite déterminer la valeur du sabre par rapport à cette droite. Cette opération permet en fait d'effectuer un changement de repère pour passer du repère fixe absolu constitué par l'installation et dans lequel les mesures de position sont effectuées, à un repère relatif lié à la bande elle-même.It will also be noted that in the theoretical case where this straight line Dl would be precisely as illustrated in FIG. 3, that is to say exactly according to the direction of travel, it would not be necessary to define said straight line by calculation from the measurements carried out . In practice, this is not possible due to the many parameters that can be taken into account to define the shape of the strip and its trajectory, and it is therefore necessary to estimate the direction of this straight line representing the general longitudinal direction of the strip from the position measurements made in order to then be able to determine the value of the saber in relation to this straight line. This operation makes it possible in fact to carry out a change of coordinate system to pass from the absolute fixed coordinate system constituted by the installation and in which the position measurements are carried out, to a relative coordinate system linked to the strip itself.
Des essais réalisés conformément à l'invention ont montré qu'elle permet d'obtenir quasiment les mêmes performances que les algorithmes utilisant trois points de mesure. Aucun algorithme ne permet de s'affranchir totalement des mouvements de pivotement de la bande dans son propre plan, qui perturbent l'avance rectilinéaire du produit. Les inventeurs ont ainsi constaté que la sensibilité de la mesure au pivotement de la bande durant la mesure est à peine plus prononcée qu'avec les algorithmes antérieurement connus .Tests carried out in accordance with the invention have shown that it makes it possible to obtain almost the same performance as the algorithms using three measurement points. No algorithm makes it possible to completely overcome the pivoting movements of the strip in its own plane, which disturb the rectilinear advance of the product. The inventors have thus found that the sensitivity of the measurement to the pivoting of the strip during the measurement is hardly more pronounced than with the previously known algorithms.
L'invention n'est pas limité au mode de réalisation qui a été décrit ci-dessus uniquement à titre d'exemple.The invention is not limited to the embodiment which has been described above solely by way of example.
En particulier, la fréquence d'échantillonnage pourra être modifiée, en fonction notamment de la vitesse de défilement de la bande. In particular, the sampling frequency may be modified, in particular as a function of the tape speed.

Claims

REVENDICATIONS
1. Procédé de détermination de la forme, selon une direction longitudinale et dans un plan longitudinal, d'une bande (20) en défilement selon la dite direction, notamment d'une tôle ou bande métallique en cours de fabrication par laminage et s ' étendant dans le dit plan longitudinal, caractérisé en ce que, au cours du défilement : on mesure de manière synchrone, dans deux plans fixes (PTl, PT2) transversaux à la direction (F) du défilement de la bande et espacés l'un de l'autre selon la dite direction, la position des deux bords de la bande à l'intersection entre le dit plan longitudinal et chacun des deux plans transversaux (PTl, PT2) , pour chaque mesure effectuée dans un plan transversal, on détermine la position d'un point médian1. Method for determining the shape, in a longitudinal direction and in a longitudinal plane, of a strip (20) running in said direction, in particular of a metal sheet or strip during manufacture by rolling and s' extending in the said longitudinal plane, characterized in that, during the running: one measures synchronously, in two fixed planes (PTl, PT2) transverse to the direction (F) of the running of the strip and spaced one of the other in said direction, the position of the two edges of the strip at the intersection between said longitudinal plane and each of the two transverse planes (PTl, PT2), for each measurement carried out in a transverse plane, the position is determined from a midpoint
(Bl, B2) entre les deux bords, représentatif de la position transversale de la bande dans le plan transversal correspondant, on renouvelle ces mesures sur au moins une partie de la longueur de la bande au cours de son défilement, l'ensemble des dits points constituant une ligne (Ll) virtuelle médiane de la bande, et on déduit la forme de la dite partie de la bande à partir de l'ensemble des mesures effectuées, par un algorithme de calcul selon lequel : on calcule pour chaque couple de mesures synchrones la pente de la droite passant par les deux points (Bl ; B2) dont la position est déterminée,(Bl, B2) between the two edges, representative of the transverse position of the strip in the corresponding transverse plane, these measurements are repeated over at least part of the length of the strip during its running, all of the said points constituting a median virtual line (L1) of the strip, and the shape of said part of the strip is deduced from the set of measurements carried out, by a calculation algorithm according to which: one calculates for each pair of measurements synchronous the slope of the line passing through the two points (Bl; B2) whose position is determined,
- puis on effectue une intégration sur la dite partie de la longueur de la bande des valeurs de pentes calculées, en prenant comme pas d'intégration la distance parcourue par la bande entre deux mesures successives,- then an integration is carried out on said part of the length of the strip of the calculated slope values, taking as the integration step the distance traveled by the strip between two successive measurements,
- et on en déduit la forme de la courbe reliant les différents points dont la position a été déterminée. - and we deduce the shape of the curve connecting the different points whose position has been determined.
2. Procédé selon la revendication 1, caractérisé en ce que les mesures sont effectuées à une fréquence correspondant à une distance prédéterminée parcourue par la bande entre deux mesures .2. Method according to claim 1, characterized in that the measurements are carried out at a frequency corresponding to a predetermined distance traveled by the strip between two measurements.
3. Procédé selon la revendication 1, caractérisé en ce que, pour déterminer et évaluer la forme de la bande, on définit à partir de l'ensemble des mesures une droite (Dl) représentative de la direction longitudinale moyenne de la bande sur la partie de longueur de bande considérée, la forme de la bande étant définie par comparaison de la ligne courbe (Ll) par rapport à la dite droite (Dl) .3. Method according to claim 1, characterized in that, to determine and evaluate the shape of the strip, a straight line (Dl) representative of the mean longitudinal direction of the strip on the part is defined from the set of measurements. of strip length considered, the shape of the strip being defined by comparison of the curved line (L1) with respect to said straight line (Dl).
4. Procédé selon la revendication 3, caractérisé en ce que la dite droite (Dl) est déterminée à partir de l'ensemble des mesures effectuées sur la longueur de la bande, par la méthode des moindres carrés.4. Method according to claim 3, characterized in that said straight line (Dl) is determined from the set of measurements made over the length of the strip, by the method of least squares.
5. Procédé selon la revendication 4, caractérisé en ce que on pondère les valeurs des mesures effectuées en fonction de la position des points mesurés sur la longueur de la bande.5. Method according to claim 4, characterized in that the values of the measurements carried out are weighted as a function of the position of the points measured over the length of the strip.
6. Dispositif de détermination de la forme, selon une direction longitudinale et dans un plan longitudinal, d'une bande en défilement selon la dite direction, notamment d'une tôle ou bande métallique en cours de fabrication par laminage et s ' étendant dans le dit plan longitudinal, caractérisé en ce qu'il comporte deux ensembles de mesure (41, 42) situés dans deux plans fixes (PTl, PT2) transversaux à la direction (F) du défilement de la bande et espacés l'un de l'autre selon la dite direction, pour mesurer simultanément la position des deux bords de la bande à l'intersection entre le dit plan longitudinal et chacun des deux plans transversaux (PTl, PT2) , des moyens de commande (43) pour commander des mesures synchrones des positions des bords de la bande dans chacun desdits plans transversaux, à une fréquence prédéterminée, et des moyens de calcul (43) pour déduire la forme de la bande à partir de l'ensemble des mesures effectuées, par déroulement d'un algorithme de calcul et comprenant :6. Device for determining the shape, in a longitudinal direction and in a longitudinal plane, of a strip running in said direction, in particular of a metal sheet or strip during manufacture by rolling and extending in the said longitudinal plane, characterized in that it comprises two measuring assemblies (41, 42) located in two fixed planes (PTl, PT2) transverse to the direction (F) of the travel of the strip and spaced one of the other according to said direction, to simultaneously measure the position of the two edges of the strip at the intersection between said longitudinal plane and each of the two transverse planes (PTl, PT2), control means (43) for controlling synchronous measurements of the positions of the edges of the strip in each of said transverse planes, at a predetermined frequency, and calculation means ( 43) to deduce the shape of the strip from all the measurements made, by running a calculation algorithm and comprising:
- des moyens pour déterminer, à partir des mesures de position des bords, la position d'un point médian (Bl, B2) entre les deux bords, représentatif de la position transversale de la bande dans le plan transversal correspondant,means for determining, from the position measurements of the edges, the position of a midpoint (B1, B2) between the two edges, representative of the transverse position of the strip in the corresponding transverse plane,
- des moyens pour déterminer pour chaque couple de mesures synchrones la pente de la droite passant par les deux points (Bl ; B2) dont la position est déterminée, des moyens subséquents pour effectuer une intégration sur la longueur de la bande des valeurs de pentes calculées, prenant comme pas d'intégration la distance parcourue par la bande entre deux mesures successives,- Means for determining for each pair of synchronous measurements the slope of the straight line passing through the two points (Bl; B2) whose position is determined, subsequent means for carrying out an integration over the length of the strip of the calculated slope values , taking as the integration step the distance traveled by the strip between two successive measurements,
- et des moyens pour déduire la forme de la courbe reliant les différents points dont la position a été déterminée .- And means to deduce the shape of the curve connecting the different points whose position has been determined.
7. Dispositif selon la revendication 6, caractérisé en ce que les ensembles de mesure comportent des moyens de mesure optique de la position des deux bords de la bande dans chacun des dits plans. 7. Device according to claim 6, characterized in that the measuring assemblies comprise means for optical measurement of the position of the two edges of the strip in each of said planes.
PCT/FR2002/000470 2001-02-16 2002-02-07 Method and device for determining the shape, in a longitudinal direction, of a moving strip WO2002066177A1 (en)

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FR01/02116 2001-02-16
FR0102116A FR2820996B1 (en) 2001-02-16 2001-02-16 METHOD AND DEVICE FOR DETERMINING THE SHAPE, ACCORDING TO A LONGITUDINAL DIRECTION, OF A TRAVELING STRIP

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JPH0719830A (en) * 1993-07-06 1995-01-20 Nippon Steel Corp Measuring apparatus for shape of hot steel plate
JPH09304035A (en) * 1996-05-17 1997-11-28 Nippon Steel Corp Waviness measuring apparatus for thread body

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JPS5785606A (en) * 1980-11-14 1982-05-28 Hitachi Ltd Controlling device of plate bending in rolling mill
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