FR2680240A1 - Method for continuously measuring the thickness of a film of oil on the surface of sheet metal advancing through a cold rolling installation - Google Patents

Method for continuously measuring the thickness of a film of oil on the surface of sheet metal advancing through a cold rolling installation Download PDF

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Publication number
FR2680240A1
FR2680240A1 FR9110071A FR9110071A FR2680240A1 FR 2680240 A1 FR2680240 A1 FR 2680240A1 FR 9110071 A FR9110071 A FR 9110071A FR 9110071 A FR9110071 A FR 9110071A FR 2680240 A1 FR2680240 A1 FR 2680240A1
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FR
France
Prior art keywords
oil
thickness
film
sheet
wavelengths
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
FR9110071A
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French (fr)
Inventor
Philippe Jean
Micque Noelle
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Institut de Recherches de la Siderurgie Francaise IRSID
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Institut de Recherches de la Siderurgie Francaise IRSID
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Priority to FR9110071A priority Critical patent/FR2680240A1/en
Publication of FR2680240A1 publication Critical patent/FR2680240A1/en
Pending legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
    • G01B11/0625—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of absorption or reflection
    • G01B11/0633—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of absorption or reflection using one or more discrete wavelengths
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0691—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of objects while moving
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0266—Measuring or controlling thickness of liquid films

Abstract

According to this invention, two infrared wavelengths are determined, one ( lambda 1) of which is practically unabsorbed by the oil and the other ( lambda 2) is absorbed by the oil, an infrared beam (F) containing these two wavelengths is directed onto the surface of the film of oil covering the sheet metal, at a suitable incidence for allowing it to be reflected onto a quantum detector (11), and the analog voltages (V) delivered by this detector for each of the two aforementioned wavelengths ( lambda 1 and lambda 2) are recorded as a function of time, the difference ( DELTA ) between these two analog voltages corresponding to a thickness (e) of the film of oil; the device comprises an optical system for emitting and reflecting an infrared beam onto the surface of the sheet metal (T).

Description

La présente invention a pour objet un procédé de mesure en continu de l'épaisseur d'un film d'huile sur la surface d'une tôle en défilement dans une installation de laminage à froid, et plus particulièrement en entrée de four de recuit continu. The subject of the present invention is a process for continuously measuring the thickness of an oil film on the surface of a moving sheet metal in a cold rolling plant, and more particularly at the inlet of a continuous annealing furnace. .

On sait que la mesure de l'épaisseur du film d'huile présent sur la surface de la tôle durant son processus de recuit présente un très grand intérêt pour le pilotage du four. En effet, la température de la tôle à la sortie du four dépend de l'émissivité de la tôle elle-même liée à l'épaisseur du film d'huile. La connaissance de l'épaisseur du film d'huile à l'entrée du four permet alors d'agir sur le modèle de pilotage de ce four, en réglant les résistances de chauffage afin d'obtenir la température de sortie voulue. It is known that the measurement of the thickness of the oil film present on the surface of the sheet during its annealing process is of great interest for controlling the furnace. Indeed, the temperature of the sheet at the outlet of the furnace depends on the emissivity of the sheet itself related to the thickness of the oil film. Knowledge of the thickness of the oil film at the furnace inlet then makes it possible to act on the piloting model of this furnace, by adjusting the heating resistances in order to obtain the desired outlet temperature.

Or, jusqu'à présent cette mesure n'a été possible qu'en laboratoire) et de façon discontinue, de sorte que durant le processus de recuit, la température de sortie recherchée ne peut être obtenue avec précision. However, until now this measurement has been possible in the laboratory) and discontinuously, so that during the annealing process, the desired exit temperature can not be obtained accurately.

L'invention a donc pour but de proposer un procédé permettant de mesurer in situ et en continu l'épaisseur d'huile sur la surface de la tôle en défilement, et ce de façon simple et rapide, afin de permettre la correction immédiate sur les résistances de chauffage. The object of the invention is therefore to propose a method for measuring in situ and continuously the thickness of oil on the surface of the scrolling sheet, in a simple and rapid manner, in order to allow the immediate correction on the heating resistors.

Suivant l'invention, on détermine deux longueurs d'onde infrarouge dont l'une n'est pratiquement pas absorbée par l'huile et l'autre est absorbée par l'huile, on dirige sur la surface du film d'huile recouvrant la tôle un faisceau infrarouge contenant ces deux longueurs d'onde, suivant une incidence appropriée pour permettre sa réflexion sur un détecteur quantique, et on enregistre en fonction du temps les tensions analogiques délivrées par ce détecteur pour chacune des deux lon gueurs d'onde précitées, la différence entre ces deux tensions analogiques correspondant à une épaisseur du film d'huile lue sur une courbe d'étalonnage caractéristique d'un couple déterminé huile/tôle. According to the invention, two infrared wavelengths are determined, one of which is practically not absorbed by the oil and the other is absorbed by the oil, and the surface of the film of oil covering the plate an infrared beam containing these two wavelengths, at an appropriate incidence to allow its reflection on a quantum detector, and recorded as a function of time the analog voltages delivered by this detector for each of the two wavelengths above, the difference between these two analog voltages corresponding to a thickness of the oil film read on a calibration curve characteristic of a specific oil / sheet torque.

L'invention sera maintenant décrite en référence aux dessins annexés qui en illustrent un mode de réali sation non limitatif. The invention will now be described with reference to the accompanying drawings which illustrate a non-limiting embodiment thereof.

La figure 1 est une vue en élévation schématique d'un dispositif de mesure en continu de l'épaisseur d'un film d'huile sur la surface d'une tôle, agencé pour mettre en oeuvre le procédé selon l'invention. Figure 1 is a schematic elevational view of a device for continuously measuring the thickness of an oil film on the surface of a sheet, arranged to implement the method according to the invention.

La figure 2 est un diagramme représentant les variations de la tension analogique en fonction du temps, délivrée par le dispositif de la Fig.1, pour deux longueurs d'onde infrarouge dont l'une est absorbée par l'huile et l'autre ne l'est pas. FIG. 2 is a diagram representing the variations of the analog voltage as a function of time, delivered by the device of FIG. 1, for two infrared wavelengths of which one is absorbed by the oil and the other does not is not.

La figure 3 est un diagramme représentant trois courbes d'étalonnage pour des couples tôle-huile déterminés. Figure 3 is a diagram showing three calibration curves for specific oil-sheet pairs.

Le dispositif représenté à la Fig.1 est destiné à la mise en oeuvre du procédé visé par l'invention, pour mesurer en continu l'épaisseur d'un film d'huile sur la surface d'une tôle (T) d'acier en défilement dans une installation de laminage à froid, et plus particulièrement dans un four de recuit continu (non représenté). The device represented in FIG. 1 is intended for carrying out the process according to the invention, for continuously measuring the thickness of an oil film on the surface of a steel sheet (T). in scrolling in a cold rolling plant, and more particularly in a continuous annealing furnace (not shown).

Ce dispositif est monté sur un support non représenté au-dessus de la tôle T. I1 comprend une source émettrice 1 d'un faisceau infrarouge (F), une lentille biconvexe 2 recevant le faisceau F, un miroir plan 3 convenablement orienté et sur lequel est réfléchi le faisceau provenant de la lentille 2, des filtres interférentiels 4 et 5 placés sur le trajet du faisceau réfléchi par le miroir 3 et pouvant être déplacés, de manière connue en soi, par un moteur 6, une lentille biconvexe 7 recevant le faisceau réfléchi par le miroir 3 et qui a traversé l'un des deux filtres 4 et 5. This device is mounted on a support not shown above the sheet T. It comprises an emitter source 1 of an infrared beam (F), a biconvex lens 2 receiving the beam F, a plane mirror 3 suitably oriented and on which is reflected the beam from the lens 2, interference filters 4 and 5 placed in the path of the beam reflected by the mirror 3 and can be moved, in a manner known per se, by a motor 6, a biconvex lens 7 receiving the beam reflected by the mirror 3 and which passed through one of the two filters 4 and 5.

Le dispositif comporte ensuite les éléments suivants : un miroir plan 8 qui réfléchit le faisceau convergent provenant de la lentille 7, un miroir parabolique 9 de dimension convenable, placé au-dessus du miroir 8, un détecteur quantique 11 positionné au foyer du miroir parabolique 9, au-dessus du miroir 8, et un enregistreur 12 relié au détecteur 11. The device then comprises the following elements: a plane mirror 8 which reflects the convergent beam coming from the lens 7, a parabolic mirror 9 of suitable size, placed above the mirror 8, a quantum detector 11 positioned at the focus of the parabolic mirror 9 , above the mirror 8, and a recorder 12 connected to the detector 11.

Le faisceau infrarouge F provenant de la lentille 7 est réfléchi sur le miroir 8, puis sur la surface de la tôle T qui le renvoie, de part et d'autre du miroir 8, en deux faisceaux F1, F2 sur le miroir parabolique 9, qui le réfléchit et le concentre sur le détecteur 11. Ce détecteur à photons, d'un type connu en soi, compte des impulsions qu'il transforme en courant électrique reçu par ltenregistreur 12, qui fournit un enregistrement dans lequel une tension analogique est en ordonnées et le temps en abscisses. The infrared beam F coming from the lens 7 is reflected on the mirror 8, then on the surface of the sheet T which sends it, on both sides of the mirror 8, into two beams F1, F2 on the parabolic mirror 9, which reflects it and focuses it on the detector 11. This photon detector, of a type known per se, counts pulses which it transforms into electric current received by the recorder 12, which provides a recording in which an analog voltage is in ordered and the time on the abscissa.

Pour mettre en oeuvre au moyen de ce système, le procédé conforme à l'invention, on opère de la manière suivante. To implement by means of this system, the method according to the invention, the procedure is as follows.

Tout d'abord, on réalise l'étalonnage du dispositif comme suit. Pour un couple tôle T-huile détermi née, on choisit deux longueurs d'onde infrarouge > 1 et # 2, dont l'une par exemple # 1, est très peu absorbée ou pas absorbée par l'huile, et l'autre par exemple ) 2 est absorbée. Cette détermination s'effectue à l'aide d'un spectroradiomètre, qui mesure l'absorption en fonction de la longueur d'onde. Cette mesure doit être rapidement exécutée du fait du défilement de la tôle. First, the device calibration is performed as follows. For a given T-oil sheet couple, two infrared wavelengths> 1 and # 2, one of which, for example # 1, is very little absorbed or not absorbed by the oil, and the other by example) 2 is absorbed. This determination is made using a spectroradiometer, which measures the absorption as a function of the wavelength. This measurement must be quickly executed because of the scrolling of the sheet.

Une fois cette sélection des longueurs d'onde infrarouge effectuée, on émet par la source 1 un fais ceau infrarouge F contenant ces deux longueurs d'onde et > 2. Ce faisceau traverse les divers éléments du dispositif décrit ci-dessus et est finalement regu dans le détecteur 11, dont les signaux électriques transmis à l'enregistreur 12 permettent l'obtention d'un graphique selon la Fig.2. La tension analogique V1 correspond à la longueur d'onde > 1 non absorbée ou très faiblement absorbée, et la tension V2 correspond au pic d'absorption de la longueur d'onde # 2. La différence V2-V1 = est proportionnelle à l'épaisseur e du film d'huile. Once this selection of the infrared wavelengths has been performed, an infrared beam F containing these two wavelengths and> 2 is emitted by the source 1. This beam passes through the various elements of the device described above and is finally received. in the detector 11, whose electrical signals transmitted to the recorder 12 allow to obtain a graph according to Fig.2. The analog voltage V1 corresponds to the wavelength> 1 unabsorbed or very slightly absorbed, and the voltage V2 corresponds to the absorption peak of the wavelength # 2. The difference V2-V1 = is proportional to the thickness e of the oil film.

En répétant cette mesure avec un certain nombre d'épaisseurs de film différentes, on peut obtenir une courbe d'étalonnage de l'épaisseur e en fonction ded
V2-V1. Pour un couple tôle T - huile déterminé, on obtient alors une courbe d'étalonnage telle que C1, pour un autre couple une courbe C2, un troisième couple une courbe C3 etc.By repeating this measurement with a number of different film thicknesses, it is possible to obtain a calibration curve of the thickness e as a function of
V2-V1. For a specific T - oil sheet couple, a calibration curve such as C1 is obtained, for another pair a C2 curve, a third pair a C3 curve, and so on.

A partir d'un ensemble de courbes d'étalonnage appropriées, on comprend donc que la mesure de l'épaisseur du film d'huile sur la tôle en défilement T à l'en- trée du four de recuit, peut être exécutée de manière très rapide, ce qui permet d'agir en un temps très bref sur le réglage des résistances de chauffe du four, afin d'obtenir la température de sortie souhaitée. From a set of suitable calibration curves, it is therefore understood that the measurement of the thickness of the oil film on the moving sheet T at the inlet of the annealing furnace can be carried out very fast, which makes it possible to act in a very short time on the setting of the heating resistances of the oven, in order to obtain the desired exit temperature.

A chaque filtre 4, 5 correspond le filtrage d'une longueur d'onde déterminée, le filtre 4 autorisant par exemple le passage de la longueur d'onde non absorbée et le filtre 5 le passage de la longueur d'onde absorbée. Each filter 4, 5 corresponds to the filtering of a determined wavelength, the filter 4 allowing for example the passage of the unabsorbed wavelength and the filter 5 the passage of the wavelength absorbed.

A titre d'exemple numérique indicatif, pour un couple "tôle d'acier-huile type "Tinol", on peut choisir
#1 = 3,38 m et #2 = 3,84 m. As a numerical example indicative, for a couple "sheet steel-oil type" Tinol ", one can choose
# 1 = 3.38 m and # 2 = 3.84 m.

Claims (2)

REVENDICATIONS 1. Procédé de mesure en continu de l'épaisseur (e) d'un film d'huile sur la surface d'une tôle (T) en défilement dans une chaîne de laminage à froid, caractérisé en ce qu'on on détermine deux longueurs d'onde infrarouge dont l'une ( > 1) n'est pratiquement pas absorbée par l'huile et l'autre ( > 2) est absorbée par I'huile, on dirige sur la surface du film d'huile recouvrant la tôle un faisceau infrarouge (F) contenant ces deux longueurs d'onde, suivant une incidence appropriée pour permettre sa réflexion sur un détecteur quantique (11), et on enregistre en fonction du temps les tensions analogiques (V) délivrées par ce détecteur pour chacune des deux longueurs d'onde précitées ( > î et # 2), la différence ( ) entre ces deux tensions analogiques correspondant à une épaisseur (e) du film d'huile lue sur une courbe d'étalonnage (Cl, C2 ou C3...) caractéristique d'un couple déterminé huile/tôle. 1. Method for continuously measuring the thickness (e) of an oil film on the surface of a sheet (T) running in a cold rolling line, characterized in that two infrared wavelengths of which one (> 1) is practically not absorbed by the oil and the other (> 2) is absorbed by the oil, the surface of the film of oil covering the plate an infrared beam (F) containing these two wavelengths, at an appropriate incidence to allow its reflection on a quantum detector (11), and recorded as a function of time the analog voltages (V) delivered by this detector for each of the two aforementioned wavelengths (> 1 and # 2), the difference () between these two analog voltages corresponding to a thickness (e) of the oil film read on a calibration curve (C1, C2 or C3. ..) characteristic of a specific torque oil / sheet. 2. Procédé selon la revendications 1, caractérisé en ce qu'on dirige le faisceau infrarouge (F) à travers des filtres interférentiels (4, 5) sur un miroir plan (8) situé au-dessus de la tôle (T) en défilement, on reçoit le faisceau réfléchi sur un miroir parabolique (9) qui le concentre sur le détecteur quantique (11), dont les signaux électriques sont captés par un enregistreur (12).  2. Method according to claim 1, characterized in that directs the infrared beam (F) through interference filters (4, 5) on a plane mirror (8) located above the sheet (T) in scrolling the reflected beam is received on a parabolic mirror (9) which focuses it on the quantum detector (11) whose electrical signals are picked up by a recorder (12).
FR9110071A 1991-08-07 1991-08-07 Method for continuously measuring the thickness of a film of oil on the surface of sheet metal advancing through a cold rolling installation Pending FR2680240A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
FR9110071A FR2680240A1 (en) 1991-08-07 1991-08-07 Method for continuously measuring the thickness of a film of oil on the surface of sheet metal advancing through a cold rolling installation

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FR9110071A FR2680240A1 (en) 1991-08-07 1991-08-07 Method for continuously measuring the thickness of a film of oil on the surface of sheet metal advancing through a cold rolling installation

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1114979A1 (en) * 1999-12-27 2001-07-11 Leica Microsystems Jena GmbH Uncoupled wafer inclination measurement with an ellipsometer with spectral photometer and measurement of focus by a reflecting objective
WO2005001452A1 (en) * 2003-06-20 2005-01-06 The Boeing Company Method of measuring coating using two-wavelength infrared reflectance
US7057177B2 (en) 2003-04-29 2006-06-06 The Boeing Company Infrared imaging for evaluation of corrosion test coupons
US7115869B2 (en) 2003-09-30 2006-10-03 The Boeing Company Method for measurement of composite heat damage with infrared spectroscopy
US7130449B2 (en) 2002-12-23 2006-10-31 The Boeing Company Method and system for ground imaging
WO2007147765A1 (en) * 2006-06-19 2007-12-27 Aluminium Norf Gmbh Method and device fof process control during the rolling of metals

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3017512A (en) * 1959-06-29 1962-01-16 American Can Co Coating thickness gauge
GB1380725A (en) * 1971-05-10 1975-01-15 Infrared Eng Ltd Optical gauging systems

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3017512A (en) * 1959-06-29 1962-01-16 American Can Co Coating thickness gauge
GB1380725A (en) * 1971-05-10 1975-01-15 Infrared Eng Ltd Optical gauging systems

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1114979A1 (en) * 1999-12-27 2001-07-11 Leica Microsystems Jena GmbH Uncoupled wafer inclination measurement with an ellipsometer with spectral photometer and measurement of focus by a reflecting objective
US7130449B2 (en) 2002-12-23 2006-10-31 The Boeing Company Method and system for ground imaging
US7057177B2 (en) 2003-04-29 2006-06-06 The Boeing Company Infrared imaging for evaluation of corrosion test coupons
US7135683B2 (en) 2003-04-29 2006-11-14 The Boeing Company Infrared imaging for evaluation of corrosion test coupons
US7312453B2 (en) 2003-04-29 2007-12-25 The Boeing Company Methods for determining corrosion products on substrates using infrared imaging
WO2005001452A1 (en) * 2003-06-20 2005-01-06 The Boeing Company Method of measuring coating using two-wavelength infrared reflectance
US7119336B2 (en) 2003-06-20 2006-10-10 The Boeing Company Method of measuring coating using two-wavelength infrared reflectance
US7115869B2 (en) 2003-09-30 2006-10-03 The Boeing Company Method for measurement of composite heat damage with infrared spectroscopy
WO2007147765A1 (en) * 2006-06-19 2007-12-27 Aluminium Norf Gmbh Method and device fof process control during the rolling of metals

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