EP0124408A1 - Apparatus for the continuous coating of a strip, especially for galvanizing a steel sheet - Google Patents

Apparatus for the continuous coating of a strip, especially for galvanizing a steel sheet Download PDF

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Publication number
EP0124408A1
EP0124408A1 EP84400724A EP84400724A EP0124408A1 EP 0124408 A1 EP0124408 A1 EP 0124408A1 EP 84400724 A EP84400724 A EP 84400724A EP 84400724 A EP84400724 A EP 84400724A EP 0124408 A1 EP0124408 A1 EP 0124408A1
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EP
European Patent Office
Prior art keywords
gas
enclosure
strip
installation according
nozzle
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EP84400724A
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German (de)
French (fr)
Inventor
Jean-Paul Hennechart
Bernard Bramaud
François Prat
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Ziegler SA
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Ziegler SA
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Publication of EP0124408A1 publication Critical patent/EP0124408A1/en
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26—After-treatment
    • C23C2/265—After-treatment by applying solid particles to the molten coating
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/14—Removing excess of molten coatings; Controlling or regulating the coating thickness
    • C23C2/16—Removing excess of molten coatings; Controlling or regulating the coating thickness using fluids under pressure, e.g. air knives
    • C23C2/18—Removing excess of molten coatings from elongated material

Definitions

  • the present invention relates to an installation for the continuous deposition of a coating on a strip, this deposition being carried out by passing the strip through a bath of the heated coating material beyond its melting point.
  • the invention applies in particular to the coating of a steel sheet with a layer of metal such as zinc.
  • Patent FR 1,563,457 describes a more efficient method which consists in sending a gas jet, preferably air in the case of a coating of lead and vapor, onto this layer of liquid coating material. of dry water in the case of zinc, this gas jet being supplied by a slot-shaped nozzle whose shape, position and orientation are precisely defined, as well as the gas pressure, in order to provide a jet in the form of a blade which removes the external fraction of the thickness of liquid and causes it to fall back towards the bath, bringing with it the dross and oxides which for could come from the surface of the bath.
  • a gas jet preferably air in the case of a coating of lead and vapor
  • a process known as "minimized flowering" is known in which a gas laden with crystallization seeds is sprayed onto the strip.
  • this gas is compressed air into which fine solid particles of zinc have been introduced.
  • a suction mouth is placed in the immediate vicinity of the blowing nozzle and the air sucked in is recycled after filtration.
  • the main object of the present invention therefore is to allow better control of the crystallization of the coating material, especially for low thicknesses of steel and low unit weight of coating.
  • Another object of the invention is to obtain the result which has just been stated for a low cost price, and with a simple installation.
  • the invention therefore provides an installation for continuously coating the strip, comprising means for successively passing the strip through a molten bair of coating material and for removing the strip from the bath in an upward and substantially vertical direction; means for regulating the thickness of liquid coating material entrained by the strip at the bottom of the bath; an enclosure surrounding said regulation means, this enclosure being open downwards and comprising side walls which plunge into the bath while its upper wall has a narrow slot for the exit of the strip; means for maintaining a protective atmosphere in said enclosure; and at least one germ-blowing nozzle arranged to blow on the ladi the strip, above the said regulation means, a gas jet charged with germs of crystallization of the coating material, this installation having the particularity that the said nozzle is placed inside an enclosure, the strip of which leaves by a narrow slot, and which is provided with means for maintaining a protective atmosphere inside said enclosure.
  • the strip is also protected from contact of air between the wiping enclosure and the flowering enclosure minimized, for example by providing that these enclosures are joined.
  • the enclosure which contains the germ-blowing nozzle or nozzles is one with the enclosure which contains regulation means.
  • blowing nozzle or nozzles are supplied with gas that is at least partially recycled, according to the current technique, it is advantageous to provide that said recycled gas is taken from said enclosure in which said blowing nozzle (s) are placed.
  • This arrangement makes it possible to limit the eddies caused by the presence of a suction mouth in the immediate vicinity of the blowing nozzle. These eddies are all the more detrimental to the quality as the strip is thinner and more flexible.
  • the speed and the temperature of the gas leaving the germ-blowing nozzle must be controlled with great precision which is more difficult to obtain with a common recycling circuit.
  • the gas recycling circuit supplying the germ-blowing nozzle or nozzles to comprise means for purifying this gas in order to lower its content. oxygen.
  • said gas purification means are arranged to supply at the same time the seeds of crystallization and preferably said purification means comprise means for introducing into the gas vapor of a material at a time reducing and capable of providing seeds and means for subsequently cooling the gas in order to form said seeds by crystallization.
  • the gas recycling circuit of the regulation means comprises gas purification means to lower its oxygen content, these means may be the only ones or operate at the same time as others provided on the other circuit.
  • the installation includes gas purification means, arranged in the enclosure which entrusts the nozzle for blowing germs, or communicating directly with it.
  • said purification means are placed in the immediate vicinity of the slot provided in the upper wall of the enclosure. This avoids untimely re-entry of oxygen through the slit, against the flow of the strip. Indeed, the slit cannot ensure perfect sealing since its edges must not come into contact with the strip, the coating of which is solidifying or just solidified.
  • the strip to be coated 1 arrives to the left of the figure. It first passes through an oven 2, with a controlled reducing atmosphere, which ensures both the preparation of the surface, by reduction of the oxides, and its preheating to a temperature close to that of the bath.
  • the strip 1, guided by rollers 3, 4, 5 then descends into the bath of molten zinc T, then rises vertically above the bath and is sent after a roll 6 to a winding station, not shown.
  • a sheath 8 which plunges into the bath and communicates with the oven 2, surrounds the strip on its path between the oven 2 and the bath 7, so as to prevent any formation of oxide on the cleaned and hot metal before it comes into contact with the bath zinc.
  • the strip On leaving the bath, the strip is surrounded by a bottomless box 9, the side walls of which dip into the molten zinc.
  • the roof of the box has a very narrow slot 10 for the exit of the strip 1 upwards.
  • the box 9 is without communication with the sheath 8, therefore with the oven 1. It would indeed be very difficult to control the composition, the temperature and the dust in the casing 9 if such a communication existed.
  • nozzles 11 Inside the box are arranged two nozzles 11, in the form of an elongated slot, intended to maintain the thickness of the coating at the desired thickness, and, above the nozzles 11, two other nozzles 12, of minimized flowering.
  • the spinning nozzles 11 are supplied with nitrogen by a recycling circuit which comprises an extraction pipe 13 by which gas is extracted from the box 9, a cold water refrigerant 14, which lowers the temperature of the gas to improve the operation of the pump 15 which follows it.
  • a filter 16 is interposed between the refrigerant and the pump.
  • a supply line 17 connects the pump 15 to the wiping nozzles 11. To this line 17 is connected a line 18 of nitrogen addition, provided with a valve and connected to a source of high purity nitrogen 19 .
  • the minimized flowering nozzles are supplied by a similar circuit, comprising an extraction duct 20, a refrigerant 21, a pump 22 and a supply duct 23, but without an auxiliary duct.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Coating With Molten Metal (AREA)
  • Breeding Of Plants And Reproduction By Means Of Culturing (AREA)

Abstract

Installation pour le revêtement en continu de bande, notamment pour la galvanisation de tôle d'acier. Le but de l'invention est d'améliorer la qualité du revêtement et la régularité de sa cristallisation notamment pour les tôles minces à faibles épaisseur de revêtement. Pour ce résultat, la ou les buses de fleurage minimisée sont placées dans une enceinte dont la bande sort par une fente étroite et qui est pourvue de moyens pour entretenir une atmosphère protectrice à l'intérieur de cette enceinte. De préférence, cette enceinte est confondue avec une enceinte entourant les moyens d'essorage, et des moyens pour le recyclage et l'épuration en oxygène de l'atmosphère protectrice sont prévus.Installation for the continuous coating of strip, in particular for the galvanization of sheet steel. The object of the invention is to improve the quality of the coating and the regularity of its crystallization, in particular for thin sheets with thin coating thickness. For this result, the minimized flowering nozzle (s) are placed in an enclosure whose strip exits through a narrow slot and which is provided with means for maintaining a protective atmosphere inside this enclosure. Preferably, this enclosure is merged with an enclosure surrounding the wringing means, and means for recycling and purifying the protective atmosphere of oxygen are provided.

Description

La presente invention est relative a une installation pour le dépôt en continu d'un revêtement sur une bande, ce dépôt étant fait par passage de la bande dans un bain de la matière de revêtement chauffée au-delà de son point de fusion. L'invention s'applique en particulier au revêtement d'une tôle d'acier par une couche de métal.tel que du zinc.The present invention relates to an installation for the continuous deposition of a coating on a strip, this deposition being carried out by passing the strip through a bath of the heated coating material beyond its melting point. The invention applies in particular to the coating of a steel sheet with a layer of metal such as zinc.

On connaît depuis longtemps des procédés dans lesquels une bande mince de métal est entrainée en continu d'abord dans des postes de préparation de surface et de préchauffage, puis,grâce à des rouleaux immergés, passe dans un bain de matière de revêtement fondu, du zinc par exemple, après quoi elle sort du bain en suivant un trajet vertical ascendant. Elle entraîne à sa sortie du bain une couche de matière de revêtement liquide dont l'épaisseur dépend, notamment, de la vitesse de déroulement, de la température du bain et de l'état de surface de la bande. Cette couche liquide se solidifie lorsque la bande se refroidit alors qu'el le est au-dessus du bain.Methods have been known for a long time in which a thin strip of metal is driven continuously first in surface preparation and preheating stations, then, using immersed rollers, passes through a bath of molten coating material, zinc for example, after which it leaves the bath following an upward vertical path. On leaving the bath, it causes a layer of liquid coating material, the thickness of which depends, in particular, on the speed of unwinding, the temperature of the bath and the surface condition of the strip. This liquid layer solidifies when the strip cools while it is above the bath.

Pour obtenir une couche de revêtement d'épaisseur uniforme, sans impuretés et à cristallisation régulière, il convient de contrôler avec précision tous les facteurs qui interviennent dans l'opération.To obtain a coating layer of uniform thickness, free from impurities and with regular crystallization, it is necessary to precisely control all the factors involved in the operation.

Dans la technique la plus ancienne, on utilisait des rouleaux pour égaliser l'épaisseur de la couche de revêtement alors qu'elle était encore liquide. Le brevet FR 1.563.457 a décrit une méthode plus efficace qui consiste à envoyer sur cette couche de matière de revêtement liquide un jet de gaz, de préférence de l'air dans le cas d'un revé- tement de plomb et de la vapeur d'eau sèche dans le cas de zinc, ce jet de gaz étant fourni par une buse en forme de fente dont la forme,la position et l'orientation sont définies avec précision, de même que la pression de gaz, afin de fournir un jet en forme de lame qui enlève la fraction externe de l'épaisseur de liquide et la fait retomber vers le bain, entratnant avec elle les crasses et oxydes qui pourraient provénir de la surface du bain.In the oldest technique, rollers were used to equalize the thickness of the coating layer while it was still liquid. Patent FR 1,563,457 describes a more efficient method which consists in sending a gas jet, preferably air in the case of a coating of lead and vapor, onto this layer of liquid coating material. of dry water in the case of zinc, this gas jet being supplied by a slot-shaped nozzle whose shape, position and orientation are precisely defined, as well as the gas pressure, in order to provide a jet in the form of a blade which removes the external fraction of the thickness of liquid and causes it to fall back towards the bath, bringing with it the dross and oxides which for could come from the surface of the bath.

Dans la pratique actuelle, le gaz utilisé le plus fréquemment pour cette opération d'essorage est l'air.In current practice, the gas most frequently used for this spinning operation is air.

Par ailleurs, pour obtenir une couche de revè- tement à cristallisation fine et régulière, on connaît un procédé, dit de "fleurage minimisé" dans lequel on projette sur la bande un gaz chargé de germes de cristallisation.Furthermore, to obtain a coating layer with fine and regular crystallization, a process known as "minimized flowering" is known in which a gas laden with crystallization seeds is sprayed onto the strip.

Usuellement ce gaz est de l'air comprimé dans lequel on a introduit de fines particules solides de zinc. Pour éviter que celles de ces particules qui ne se fixent pas sur la bande aillent se répandre dans l'atelier, une bouche d'aspiration est placée à proximité immédiate de la buse de soufflage et l'air aspiré est recyclé après filtre- tion.Usually this gas is compressed air into which fine solid particles of zinc have been introduced. To prevent those of these particles which do not attach to the strip from spreading in the workshop, a suction mouth is placed in the immediate vicinity of the blowing nozzle and the air sucked in is recycled after filtration.

La combinaison du refroidissement accéléré sous l'effet du jet de gaz et de la présence d'un grand nombre de germes conduit à une cristallisation fine et régulière.The combination of accelerated cooling under the effect of the gas jet and the presence of a large number of germs leads to fine and regular crystallization.

Ces méthodes donnent dans l'ensemble des résultats satisfaisants; toutefois, les exigences des utilisateurs sont toujours dans le sens d'une sévérité croissante, et il a été constaté que la constance du produit fini n'est pas tout à fait parfaite en ce qui concerne la présence d'oxydes en surface et la cristallisation de la matière de revêtement, notamment en ce qui concerne les tôles minces à faible épaisseur de revêtement.These methods generally give satisfactory results; however, the requirements of the users are always in the direction of an increasing severity, and it has been found that the consistency of the finished product is not entirely perfect as regards the presence of oxides on the surface and the crystallization coating material, in particular with regard to thin sheets with a thin coating thickness.

Ilétait connu (GB-A-777.353) de préserver le revêtement de l'oxydation au moment.de sa sortie du bain en faisant traverser à la bande une enceinte dont les parois plongent dans le bain et qui présente à sa partie supérieure une ouverture étroite par ou sort la bande. Un gaz inerte séjourne dans cette enceinte, qui contient des rouleaux destinés à égaliser l'épaisseur du revêtement.It was known (GB-A-777.353) to preserve the coating from oxidation at the time of its exit from the bath by passing the strip through an enclosure whose walls plunge into the bath and which has at its upper part a narrow opening through or out of the tape. An inert gas remains in this enclosure, which contains rollers intended to equalize the thickness of the coating.

0n a proposé(FR-A-2.501.724) pour améliorer encore la qualité, d'utiliser un gaz inerte de haute pureté, par exemple de l'azote à très basse teneur en oxygène. Un tel gaz est coûteux, et on a prévu de le recycler, mais, malgré les précautions prises : circuits aussi étanches que possible, refraidissement, filtration, on arrive difficilement à un taux de recyclage supérieur à 50%.0n proposed (FR-A-2.501.724) to further improve the quality, to use an inert gas of high purity, for example nitrogen with very low oxygen content. Such a gas is expensive, and plans have been made to recycle it, but, despite the precautions taken: circuits as tight as possible, cooling, filtration, it is difficult to achieve a recycling rate of more than 50%.

D'autre part, malgré ces précautions prises au moment de la sortie de la bande hors du bain et de l'essorage, on n'arrive pas toujours à un contrôle satisfaisant de la cristallisation, notamment pour des épaisseurs faibles d'acier de la tôle et pour des revêtements minces. Il semble que dans ce cas la faible inertie thermique de la bande a pour conséquence l'apparition de problèmes particuliers.On the other hand, despite these precautions taken at the time of the exit of the strip from the bath and of the spinning, one does not always arrive at a satisfactory control of the crystallization, in particular for small thicknesses of steel of the sheet metal and for thin coatings. It seems that in this case the low thermal inertia of the strip results in the appearance of particular problems.

La présente invention a donc pour but principal de permettre un meilleur contrôla de la cristallisatior de la matière de revêtement, spécialement pour des épaisseurs faibles d'acier et de faibles poids unitaires de revêtement.The main object of the present invention therefore is to allow better control of the crystallization of the coating material, especially for low thicknesses of steel and low unit weight of coating.

Un autre but de l'invention est d'obtenir le résultat qu'on vient d'énoncer pour un prix de revient peu élevé, et avec une installation simple.Another object of the invention is to obtain the result which has just been stated for a low cost price, and with a simple installation.

L'invention fournit donc une installation pour le revêtement en continu de bande, comportant des moyens pour faire passer successivement la bande à travers un bair fondu de matière de revêtement et pour faire sortir la ban de du bain dans une direction ascendante et sensiblement verticale; des moyens pour régulariser l'épaisseur de matière de revêtement liquide entraînée par la bande à la soi tie du bain; une enceinte entourant lesdits moyens dé régularisation, cette enceinte étant ouverte vers le bas et comportant des parois latérales qui plongent dans le bain alors que sa paroi supérieurs comporte une fente étroite pour la sortie de la bande; des moyens pour entretenir dans ladite enceinte une atmosphère protectrice; et au moins une buse de soufflage de germes disposée pour souffler sur ladi te bande, au-dessus desdits moyens de régularisation, un jet de gaz chargé de germes de cristallisation de la matière de revêtement, cette installation présentant la particularité que ladite buse est placée à l'intérieur d'une enceinte, dont la bande sort par une fente étroite, et qui est pourvue de moyens pour entretenir une atmosphère protectrice à l'intérieur de ladite enceinte.The invention therefore provides an installation for continuously coating the strip, comprising means for successively passing the strip through a molten bair of coating material and for removing the strip from the bath in an upward and substantially vertical direction; means for regulating the thickness of liquid coating material entrained by the strip at the bottom of the bath; an enclosure surrounding said regulation means, this enclosure being open downwards and comprising side walls which plunge into the bath while its upper wall has a narrow slot for the exit of the strip; means for maintaining a protective atmosphere in said enclosure; and at least one germ-blowing nozzle arranged to blow on the ladi the strip, above the said regulation means, a gas jet charged with germs of crystallization of the coating material, this installation having the particularity that the said nozzle is placed inside an enclosure, the strip of which leaves by a narrow slot, and which is provided with means for maintaining a protective atmosphere inside said enclosure.

Le fait de prévoir une enceinte de protection autour de la buse de projection de germes, permet d'éviter la formation de traces 'd'oxydes dans le revêtement, en outra cette enceinte permet une température plus constante au moment du "fleurage minimisé".The fact of providing a protective enclosure around the germ projection nozzle makes it possible to avoid the formation of traces of oxides in the coating, in addition this enclosure allows a more constant temperature at the time of "minimized flowering".

Bien entendu, pour réduire au maximum la formation de traces d'oxydes, il est avantageux que la bande soit également protégée du contact de l'air entre l'enceinte d'essorage et l'enceinte de fleurage minimisé par exemple en prévoyant que ces enceintes soient jointives. Tau- tefois, suivant une modalité préférée l'enceinte qui contient la ou les buses de soufflage de germes ne fait qu'un avec l'enceinte qui contient des moyens de régularisation.Of course, to minimize the formation of traces of oxides, it is advantageous that the strip is also protected from contact of air between the wiping enclosure and the flowering enclosure minimized, for example by providing that these enclosures are joined. However, according to a preferred method, the enclosure which contains the germ-blowing nozzle or nozzles is one with the enclosure which contains regulation means.

Dans une installation dans laquelle la ou les buses de soufflage sont alimentées en gaz au moins partiellement recyclé, selon la technique courante on prévoit avantageusement que ledit gaz recyclé est prélevé dans ladite enceinte dans laquelle sont placées ladite ou lesdites buses de soufflage. Cette disposition permet de limiter les remous causés par la présence d'une bouche d'aspiration à proximité immédiate de la buse de soufflage. Ces remous sont d'autant plus nuisibles à la qualité que la bande est plus mince et plus flexible.In an installation in which the blowing nozzle or nozzles are supplied with gas that is at least partially recycled, according to the current technique, it is advantageous to provide that said recycled gas is taken from said enclosure in which said blowing nozzle (s) are placed. This arrangement makes it possible to limit the eddies caused by the presence of a suction mouth in the immediate vicinity of the blowing nozzle. These eddies are all the more detrimental to the quality as the strip is thinner and more flexible.

Comme on l'a indiqué plus haut, on connait des installations dans lesquelles l'enceinte entourant les moyens d'essorage est associée à un circuit pour recycler au moins partiellement le gaz constituant l'atmosphère protectrice. Il pourrait être envisagé, pour simplifier, de prévoir un circuit de recyclage unique, surtout si l'enceinte est commune.L'expérience a montré que cette solution n'sst pas la plus avantageuse, et qu'il vautmieux prévoir que le circuit pour le recyclage de ce gaz estindépendant du circuit pour le recyclage du gaz de soufflage de germes, même si l'enceinte est commune.As indicated above, there are known installations in which the enclosure surrounding the wringing means is associated with a circuit for at least partially recycling the gas constituting the protective atmosphere. It could be envisaged, for simplicity, to provide a unique recycling system, especially if the speaker is commune.L'expérience showed that this solution not n'sst most advantageous and that vautmieux predict that the circuit for recycling this gas e s t independent circuit for recycling the germ blowing gas, even if the enclosure is common.

En effet la vitesse et la température du gaz sortant de la buse de soufflage de germes doivent être contrôles avec une grande précision qui est plus difficile à obtenir avec un circuit de recyclage commun.In fact, the speed and the temperature of the gas leaving the germ-blowing nozzle must be controlled with great precision which is more difficult to obtain with a common recycling circuit.

Avantageusement, pour économiser le gaz, lequel peut être de l'azote de haute pureté, on prévoit que le circuit de recyclage du gaz alimentant la ou les buses de soufflage de germes comprend des moyens d'épuration de ce gaz pour abaisser sa teneur en oxygène.Advantageously, to save gas, which can be high purity nitrogen, provision is made for the gas recycling circuit supplying the germ-blowing nozzle or nozzles to comprise means for purifying this gas in order to lower its content. oxygen.

Suivant une modalité particulièrement intéressante, lesdits moyens d'épuration de gaz sont disposés pour fournir en même temps les germes de cristallisation et de préférence lesdits moyens d'épuration comportent des moyens pour introduire dans le gaz de la vapeur d'une matière à la fois réductrice et capable de fournir des germes et des moyens pour refroidir ensuite le gaz afin de former lesdits germes par cristallisation.According to a particularly advantageous modality, said gas purification means are arranged to supply at the same time the seeds of crystallization and preferably said purification means comprise means for introducing into the gas vapor of a material at a time reducing and capable of providing seeds and means for subsequently cooling the gas in order to form said seeds by crystallization.

On peut aussi prévoir, si les deux circuits de recyclage de gaz sont séparés, que le circuit de recyclage du gaz des moyens de.régularisation comprend des moyens d'épuration de gaz pour abaisser sa teneur en oxygène, ces moyens peuvent être les seuls ou fonctionnent en même temps,que d'autres prévus sur l'autre circuit. Dans le cas où la ou les buses de soufflage de germes et les moyens de régularisation sont dans la même enceinte, on peut aussi prévoir que l'installation comprend des moyens d'épuration de gaz, disposés dans l'enceinte qui confiant la buse de soufflage de germes, ou communiquant directement avec elle.It is also possible to provide, if the two gas recycling circuits are separate, that the gas recycling circuit of the regulation means comprises gas purification means to lower its oxygen content, these means may be the only ones or operate at the same time as others provided on the other circuit. In the case where the germ blowing nozzle or nozzles and the regulation means are in the same enclosure, it is also possible to provide that the installation includes gas purification means, arranged in the enclosure which entrusts the nozzle for blowing germs, or communicating directly with it.

Ces moyens sont ainsi placés dans la partie commune aux deux circuits de recyclage-s'il y en a deux. De préférence lesdits moyens d'épuration sont placés à proximité immédiate de la fente prévue dans la paroi supérieure de l'enceinte. On évite ainsi des rentrées d'oxygène intempestives par la fente, à contre-courant de la bande. En effet, la fente ne peut assurer une étanchéité parfaite puisque ses bords ne doivent pas entrer en contact avec la bande, dont le revêtement est en cours de solidification ou tout juste solidifié.These means are thus placed in the part common to the two recycling circuits-if there are two. Preferably said purification means are placed in the immediate vicinity of the slot provided in the upper wall of the enclosure. This avoids untimely re-entry of oxygen through the slit, against the flow of the strip. Indeed, the slit cannot ensure perfect sealing since its edges must not come into contact with the strip, the coating of which is solidifying or just solidified.

L'invention va maintenant être exposée plus en détail à l'aide d'un exemple non limitatif de réalisation pratique d'installation de préparation de tôle zinguée, illustrée par la figure annexée qui représente une coupe verticale schématique de l'installation.The invention will now be explained in more detail with the aid of a nonlimiting example of a practical embodiment of an installation for preparing galvanized sheet, illustrated by the appended figure which represents a schematic vertical section of the installation.

La bande à revêtir 1 arrive à la gauche de la figure. Elle traverse d'abord un four 2, à atmosphère réductrice contrôlée, qui assure à la fois la préparation de la surface, par réduction des oxydes, et son préchauffage à une température voisine de celle du bain. La bande 1, guidée par des rouleaux 3, 4, 5 descend ensuite dans le bain de zinc fondu T, puis remonte à la verticale au-dessus du bain et est envoyée après un rouleau 6 vers un poste d'enroulage non représenté. Une gaine 8 qui plonge dans le bain et communique avec le four 2, entoure la bande sur son trajet entre le four 2 et le bain 7, de façon à empêcher toute formation d'oxyde sur le métal nettoyé et chaud avant son contact avec le zinc du bain.The strip to be coated 1 arrives to the left of the figure. It first passes through an oven 2, with a controlled reducing atmosphere, which ensures both the preparation of the surface, by reduction of the oxides, and its preheating to a temperature close to that of the bath. The strip 1, guided by rollers 3, 4, 5 then descends into the bath of molten zinc T, then rises vertically above the bath and is sent after a roll 6 to a winding station, not shown. A sheath 8 which plunges into the bath and communicates with the oven 2, surrounds the strip on its path between the oven 2 and the bath 7, so as to prevent any formation of oxide on the cleaned and hot metal before it comes into contact with the bath zinc.

A sa sortie du bain, la bande est entourée par un caisson 9 sans fond et dont les parois latérales plongent dans le zinc fondu. Le toit du caisson comporte une fente 10, très étroite pour la sortie de la bande 1 vers le haut.On leaving the bath, the strip is surrounded by a bottomless box 9, the side walls of which dip into the molten zinc. The roof of the box has a very narrow slot 10 for the exit of the strip 1 upwards.

Le caisson 9 est sans communication avec la gaine 8, donc avec le four 1. Il serait en effet très difficile de contrôler la composition, la température et les poussières dans le caisson 9 si une telle communication existait.The box 9 is without communication with the sheath 8, therefore with the oven 1. It would indeed be very difficult to control the composition, the temperature and the dust in the casing 9 if such a communication existed.

A l'intérieur du caisson sont disposées deux buses 11, en forme de fente allongée, destinées à maintenir l'épaisseur du revêtement à l'épaisseur voulue, et, au-dessus des buses 11, deux autres buses 12, de fleurage minimisé.Inside the box are arranged two nozzles 11, in the form of an elongated slot, intended to maintain the thickness of the coating at the desired thickness, and, above the nozzles 11, two other nozzles 12, of minimized flowering.

Les buses d'essorage 11 sont alimentées en azote par un circuit de recyclage qui comprend une conduite d'extraction 13 par laquelle du gaz est extrait du caisson 9, un réfrigérant à eau froide 14, qui abaisse la température du gaz pour améliorer le fonctionnement de la pompe 15 qui lui fait suite. Un filtre 16 est intercalé entre le réfrigérant et la pompe. Une conduite d'alimentation 17 relie la pompe 15 aux buses d'essorage 11. Sur cette conduite 17 vient se brancher une conduite 18 d'appoint en azote, munie d'une vanne et reliée à une source d'azote de grande pureté 19.The spinning nozzles 11 are supplied with nitrogen by a recycling circuit which comprises an extraction pipe 13 by which gas is extracted from the box 9, a cold water refrigerant 14, which lowers the temperature of the gas to improve the operation of the pump 15 which follows it. A filter 16 is interposed between the refrigerant and the pump. A supply line 17 connects the pump 15 to the wiping nozzles 11. To this line 17 is connected a line 18 of nitrogen addition, provided with a valve and connected to a source of high purity nitrogen 19 .

Les buses de fleurage minimisé sont alimentées par un circuit analogue, comportant un conduit d'extraction 20, un réfrigérant 21, une pompe 22 et une conduite d'alimentation 23, mais sans conduite d'appoint.The minimized flowering nozzles are supplied by a similar circuit, comprising an extraction duct 20, a refrigerant 21, a pump 22 and a supply duct 23, but without an auxiliary duct.

On a représenté en tirets trois positions possibles du dispositif d'épuration :

  • En 24, on a représenté un dispositif d'épuration branché sur le circuit du gaz de fleurage minimisé, et qui est alors combiné avec le dispositif d'alimentation en germes de cristallisation.
  • En 25, on a représenté un dispositif d'épuration branché sur le circuit du gaz d'essorage et dans ce cas il peut être constitué par des moyens d'injecter un hydrocarbure gazeux ou liquide, ou une substance analogue et une surface chaude qui vient frapper le gaz.
  • En 26, on a représenté un dispositif d'épuration placé dans le caisson 9, à proximité de la fente 10. Ce dispositif peut comporter un ou plusieurs surfaces chaudes, l'injection de matière réductrice peut être placée à un autre endroit des circuits.
Three possible positions of the purification device have been shown in dashes:
  • In 24, there is shown a purification device connected to the circuit of the minimized flowering gas, and which is then combined with the device for supplying seeds of crystallization.
  • At 25, there is shown a purification device connected to the wiping gas circuit and in this case it can be constituted by means of injecting a gaseous or liquid hydrocarbon, or a similar substance and a hot surface which comes hit the gas.
  • At 26, there is shown a purification device placed in the box 9, near the slot 10. This device can comprise one or more hot surfaces, the injection of reducing material can be placed at another location in the circuits.

Claims (10)

1. Installation pour le revêtement en continu de bande, comportant des moyens pour faire passer successivement la bande à travers un bain fondu (7 ) de matière de revêtement et pour faire sortir la bande du bain dans une direction ascendante et sensiblement verticale; des moyens pour régulariser l'épaisseur de matière de revêtement liquide entrainée par la bande à la sortie du bain; une enceinte ( 9) entourant lesdits moyens de régularisation, cette enceinte étant ouverte vers le bas et comportant des parois latérales qui plongent dans le bain alors que sa paroi supérieure comporte une fente étroite (10) pour la sortie de la bande; des moyens pour entretenir dans ladite enceinte une atmosphère protectrice; et au moins une buse(12)de soufflage de germes disposée pour souffler sur ladite bande, au-dessus desdits moyens de régularisation, un jet de gaz chargé de germes de cristallisation de la matière de revêtement, caractérisée en ce que ladite buse est placée à l'intérieur d'une enceinte, dont la bande sort par une fente étroite, et qui est pourvue de moyens pour entretenir une atmosphère protectrice à l'intérieur de ladite enceinte.1. Installation for continuously coating the strip, comprising means for successively passing the strip through a molten bath (7) of coating material and for removing the strip from the bath in an upward and substantially vertical direction; means for regulating the thickness of liquid coating material entrained by the strip at the outlet of the bath; an enclosure (9) surrounding said regulation means, this enclosure being open downwards and comprising side walls which plunge into the bath while its upper wall has a narrow slot (10) for the exit of the strip; means for maintaining a protective atmosphere in said enclosure; and at least one nozzle (12) for blowing germs arranged to blow on said strip, above said regulation means, a gas jet charged with germs of crystallization of the coating material, characterized in that said nozzle is placed inside an enclosure, the strip of which exits through a narrow slot, and which is provided with means for maintaining a protective atmosphere inside said enclosure. 2. Installation selon la revendication 1, caractérisée en ce que l'enceinte qui contient la ou les buses de soufflage de germes ne fait qu'un avec l'enceinte qui contient les moyens de régularisation2. Installation according to claim 1, characterized in that the enclosure which contains the germ blowing nozzle or nozzles is one with the enclosure which contains the regulation means 3. Installation selon l'une des revendications 1 ou 2, dans laquelle la ou les buses de soufflagesont alimen- téesen gaz au moins partiellement recyclé, caractérisé en ce que ledit gaz recyclé est prélevé dans ladite enceinte dans laquelle sont placées ladite ou lesdites buses de soufflage.3. Installation according to one of claims 1 or 2, in which the blowing nozzle or nozzles are supplied with gas at least partially recycled, characterized in that said recycled gas is taken from said enclosure in which said said nozzle or nozzles are placed blowing. 4. Installation selon la revendication 3 et dans laquelle l'enceinte entourant les moyens d'essorage est associée à un circuit pour recycler au moins partiellement le gaz constituant l'atmosphère protectrice, caractérisée en ce que le circuit pour le recyclage de ce gaz est indépendant du circuit pour le recyclage du gaz de soufflage de germes, même si l'enceinte est commune.4. Installation according to claim 3 and in which the enclosure surrounding the wringing means is associated with a circuit for at least partially recycling the gas constituting the protective atmosphere, characterized in that the circuit for recycling this gas is independent of the circuit for recycling the germ-blowing gas, even if the enclosure is common. 5. Installation selon l'une des revendications 3 au 4, caractérisée en ce que le circuit de recyclage du gaz alimentant la ou les buses de soufflage de germes comprend des moyens d'épuration de ce gaz pour abaisser sa teneur en oxygène.5. Installation according to one of claims 3 to 4, characterized in that the gas recycling circuit supplying the germ blowing nozzle or nozzles comprises means for purifying this gas to lower its oxygen content. 6. Installation selon la revendication 5, caractérisée en ce que lesdits moyens d'épuration de gaz sont disposés pour fournir en même temps des germes de cristallisation.6. Installation according to claim 5, characterized in that said gas cleaning means are arranged to provide at the same time seeds of crystallization. 7. Installation selon la revendication 6, caractérisée en ce que lesdits moyens d'épuration comportent des moyens pour introduire dans le gaz de la vapeur d'une matière à la fois réductrice et capable de fournir des germes et des moyens pour refroidir ensuite le gaz afin de former lesdits germes par cristallisation.7. Installation according to claim 6, characterized in that said purification means comprise means for introducing into the gas vapor of a material which is both reducing and capable of supplying germs and means for subsequently cooling the gas in order to form said seeds by crystallization. 8. Installation selon l'une des revendications 4 à 7, caractériséeen ce que le circuit de recyclage du gaz des moyens de régularisation comprend des moyens d'épuration de ce gaz pour abaisser sa teneur en oxygène.8. Installation according to one of claims 4 to 7, characterized in that the gas recycling circuit of the regulation means comprises means for purifying this gas to lower its oxygen content. 9.Installation selon l'une des revendications 3 à 8, caractérisée en ce qu'elle comprend des moyens d'épuration de gaz, disposés dans l'enceinte qui contient la buse de soufflage de germes, ou communiquant directement avec elle.9.Installation according to one of claims 3 to 8, characterized in that it comprises gas cleaning means, arranged in the enclosure which contains the nozzle for blowing germs, or communicating directly with it. 10. Installation selon la revendication 9, caractérisée en ce que lesdits moyens d'épuration sont placés à proximité immédiate de la fente prévue dans la paroi supérieure de l'enceinte.10. Installation according to claim 9, characterized in that said purification means are placed in the immediate vicinity of the slot provided in the upper wall of the enclosure.
EP84400724A 1983-04-13 1984-04-11 Apparatus for the continuous coating of a strip, especially for galvanizing a steel sheet Withdrawn EP0124408A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8306055 1983-04-13
FR8306055A FR2544336B1 (en) 1983-04-13 1983-04-13 INSTALLATION FOR THE CONTINUOUS COATING OF BELT, PARTICULARLY FOR THE GALVANIZATION OF STEEL SHEET

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EP (1) EP0124408A1 (en)
JP (1) JPS59205462A (en)
CA (1) CA1210576A (en)
DE (1) DE124408T1 (en)
ES (1) ES531556A0 (en)
FR (1) FR2544336B1 (en)

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EP0122856B1 (en) * 1983-04-13 1988-06-01 Galvanor Ziegler Method and apparatus for the continuous coating of a strip with an oxidizable coating
EP0395759A1 (en) * 1988-09-29 1990-11-07 Nisshin Steel Co., Ltd. Apparatus for manufacturing minimized spangle molten plated steel plate

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NO176484C (en) * 1992-02-12 1995-04-12 Norsk Hydro As A flux adhesive aluminum based component and process for its manufacture
AU666354B2 (en) * 1992-04-06 1996-02-08 Bhp Steel (Jla) Pty Limited Stripping liquid coatings
EP0565272B1 (en) * 1992-04-06 1997-05-21 BHP STEEL (JLA) PTY Ltd Stripping liquid coatings
US5593499A (en) * 1994-12-30 1997-01-14 Photocircuits Corporation Dual air knife for hot air solder levelling
FR2735044B1 (en) * 1995-06-07 1997-07-25 Air Liquide APPARATUS FOR TREATING SOLID OBJECTS BY DIPPING IN A LIQUID BATH
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US20050281953A1 (en) * 2004-06-21 2005-12-22 Carroll Kevin R Coating apparatus and method
US9863029B2 (en) * 2012-08-01 2018-01-09 Dongkuk Steel Mill Co., Ltd. Apparatus for forming nitrogen cloud to produce hot dip coated steel sheet
AU2013209303B2 (en) * 2012-08-01 2015-05-07 Dongkuk Coated Metal Co., Ltd. Method and apparatus for producing zinc-aluminum alloy-coated steel sheet with superior workability and corrosion resistance
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EP0122856B1 (en) * 1983-04-13 1988-06-01 Galvanor Ziegler Method and apparatus for the continuous coating of a strip with an oxidizable coating
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Also Published As

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DE124408T1 (en) 1985-03-14
ES8501806A1 (en) 1984-12-01
FR2544336B1 (en) 1985-08-09
JPS59205462A (en) 1984-11-21
FR2544336A1 (en) 1984-10-19
US4502408A (en) 1985-03-05
CA1210576A (en) 1986-09-02
ES531556A0 (en) 1984-12-01

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