WO2002083969A1 - Method and device for dip coating a metal strip - Google Patents

Method and device for dip coating a metal strip Download PDF

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Publication number
WO2002083969A1
WO2002083969A1 PCT/BE2002/000047 BE0200047W WO02083969A1 WO 2002083969 A1 WO2002083969 A1 WO 2002083969A1 BE 0200047 W BE0200047 W BE 0200047W WO 02083969 A1 WO02083969 A1 WO 02083969A1
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WO
WIPO (PCT)
Prior art keywords
liquid metal
strip
thin channel
channel
thin
Prior art date
Application number
PCT/BE2002/000047
Other languages
French (fr)
Inventor
Yves Hardy
Jean Crahay
Original Assignee
Centre De Recherches Metallurgiques, A.S.B.L.
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.)
Filing date
Publication date
Application filed by Centre De Recherches Metallurgiques, A.S.B.L. filed Critical Centre De Recherches Metallurgiques, A.S.B.L.
Priority to EP02719575A priority Critical patent/EP1386016B1/en
Priority to DE60204453T priority patent/DE60204453T2/en
Priority to AT02719575T priority patent/ATE296905T1/en
Publication of WO2002083969A1 publication Critical patent/WO2002083969A1/en

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Classifications

    • 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
    • C23C2/003—Apparatus
    • C23C2/0035—Means for continuously moving substrate through, into or out of the bath
    • 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
    • C23C2/50—Controlling or regulating the coating processes
    • C23C2/52—Controlling or regulating the coating processes with means for measuring or sensing

Definitions

  • the present invention relates to a method for coating a metallic strip by dipping, that is to say by continuous scrolling through a liquid metal.
  • the invention also relates to a device for implementing this method.
  • Dip galvanizing of a steel strip generally comprises two main operations, namely annealing the strip and depositing the coating.
  • the corresponding installation therefore comprises two large parts, namely an annealing oven and a galvanizing tank.
  • annealing The purpose of annealing is to prepare the strip, in particular its surface, for the following coating operation. In particular, it recrystallizes the work hardened structure in the case of a cold rolled strip; it also operates, in all cases, cleaning and brightening the surface by means of an appropriate atmosphere, generally reducing, comprising hydrogen and nitrogen.
  • conventional galvanizing consists in passing a steel strip through a bath of molten zinc and then, at the exit of this bath, adjusting the thickness of the zinc layer by wringing using air knives or nitrogen under pressure.
  • the strip is guided by several rollers, in particular a first roller, called the bottom roller, entirely immersed in the zinc, under which it passes before rising vertically towards the surface of the bath, and other rollers, called stabilization, deflection or guide rollers, often partially or even completely submerged near the upper surface of the liquid metal bath, intended to ensure stabilization, possibly the flatness of the coated strip, before it is spun.
  • a first roller called the bottom roller
  • stabilization, deflection or guide rollers often partially or even completely submerged near the upper surface of the liquid metal bath, intended to ensure stabilization, possibly the flatness of the coated strip, before it is spun.
  • rollers motorized or free, come into contact with the surface of the moving band and can thus cause surface defects. They must therefore be frequently dismantled to be inspected, repaired or even replaced, since their condition considerably influences the quality of the zinc coating. This results in frequent shutdowns of the production line and a significant loss of productivity. Furthermore, those skilled in the art are well aware of the difficulty of adjusting and maintaining the composition of the coating metal. It is hardly ever a pure metal, but rather an alloy containing different elements in determined quantities but variable from one type to another, intended to improve the performances of coatings, such as for example the additions of aluminum in galvanizing baths.
  • the mattes that is to say aggregates of particles of intermetallic compounds, formed inter alia by the dissolution of the extreme surface of the steel strips by the bath of liquid metal, also cause appearance defects well known, and must therefore be regularly eliminated. This results in wasted time and metal, which adversely affects the productivity and profitability of conventional processes.
  • the object of the invention is to propose a method for coating a metallic strip by dipping, which makes it possible to remedy the aforementioned drawbacks, in particular removing all submerged rollers and ensuring a constant composition of the liquid metal in the coating area.
  • it proposes a device for implementing this method.
  • a method for coating a metallic strip by dipping by means of a liquid metal in which said strip is passed through a volume of said liquid metal, is characterized in that one circulates said strip in a thin channel, in that the liquid metal is introduced into said thin channel at least on either side of said strip, and in that a movement of circulation of said liquid metal is created relative to to said strip, inside said thin channel. It is then found that the coating is therefore carried out by contacting the surface of the metal strip with a flow of liquid metal rather than coating the said surface by immersion in a bath of liquid metal.
  • said thin channel is supplied with liquid metal from a separate source, constituted for example by a separate reservoir; such a separate tank is advantageously disposed higher than said thin channel, so as to supply at least partially by a gravimetric effect.
  • a separate source constituted for example by a separate reservoir
  • the separate tank is advantageously disposed higher than said thin channel, so as to supply at least partially by a gravimetric effect.
  • Part or all of the supply can however also be provided by one or more pumps.
  • the liquid metal is subjected to at least one treatment before introducing it into said thin channel.
  • said treatment can consist in filtering the liquid metal before introducing it into the thin channel. This reduces the risk of depositing floating particles, such as intermetallic compounds, on the surface of the strip.
  • the chemical composition and / or the temperature of the liquid metal are measured at determined intervals, preferably continuously, and, if necessary, this chemical composition and / or this temperature is adjusted before introducing the metal. liquid in said thin channel. It is thus possible to maintain at least substantially constant these conditions governing the dip coating operation of the metal strip.
  • the supply of said thin channel is carried out in a closed circuit. This avoids any contact of the liquid metal with the ambient air, and therefore any risk of deterioration of the liquid metal, in particular by oxidation.
  • said thin channel is supplied with liquid metal under an independently adjustable pressure on each face of the strip.
  • the liquid metal feed pressure is adjusted, as the case may be, by varying the level difference between the thin channel and the separate reservoir, or by modifying the pressure supplied by the pumps. food.
  • the speed of circulation of the stream of liquid metal with respect to the strip, inside said thin channel is between 0.1 m / s and 5 m / s.
  • a device for implementing this method essentially comprises a thin channel, means for circulating the strip to be coated through said thin channel, as well as means for supplying said thin channel with liquid metal and for creating a circulation movement. liquid metal relative to the strip, inside the thin channel.
  • the section of the thin channel according to the invention is determined so as to allow the passage of the widest strip which must be coated therein, without requiring an excessive flow of liquid metal.
  • the width of the thin channel according to the invention is generally between 1 m and 2 m. It goes without saying that this width could be increased or decreased depending on particular circumstances.
  • the height of the thin channel defines the thickness of the layer of liquid metal in circulation, and therefore also influences the flow of liquid metal in the thin channel. This height is preferably less than 6 cm, and more preferably less than 3 cm, so as to be able to limit the flow of liquid metal in the thin channel.
  • the thin channel according to the invention may have a shape either planar or curved, in particular partially cylindrical. In the latter case, the curvature must be limited so as not to unnecessarily complicate the trajectory and guiding of the strip.
  • the strip to be coated circulates through said channel under the action of the traction exerted by the drive systems of the coating line. Its trajectory is determined by guide means, generally rollers, arranged outside the channel, upstream and downstream thereof, so as not to damage the surface of the strip during the coating operation.
  • the strip must therefore be kept at a minimum distance from the walls of the channel, in order to avoid any risk of contact with them.
  • this distance is between 1 mm and 15 mm, depending on various parameters such as the speed and width of the strip, the nature of the liquid metal, the length and / or the shape of the path of the thin channel. .
  • the thin channel according to the invention comprises on the one hand means for supplying liquid metal, and on the other hand means for creating a movement of circulation of the liquid metal with respect to the strip, inside the thin channel .
  • Said supply means comprise at least one separate tank, with a capacity much larger than the thin channel; this reservoir is connected to the thin channel by a supply circuit leading to means for introducing the liquid metal into the thin channel, on either side of the strip which circulates there.
  • introduction means can be constituted either by injectors arranged at at least one of the ends of the channel, or by injectors formed in the walls of the channel parallel to the plane of the strip, or even by a combination of these two types of injectors.
  • the separate reservoir can be raised relative to the thin channel, or the supply circuit can comprise at least one pump.
  • the device also comprises means for controlling and adjusting the temperature and / or the composition of the liquid metal, means for adding fresh liquid metal as well as means for filtering the liquid metal before it introduction into the thin channel.
  • the channel is provided with sealing means, such as airlocks at its ends, allowing the passage of the strip but preventing the leakage of liquid metal.
  • the channel can advantageously be integrated into a closed circuit, also comprising at least one supply reservoir, possibly raised, a circuit for supplying the thin channel, a circuit for recovering excess liquid metal, means for treating the liquid metal, and optionally at least one liquid metal circulation pump.
  • the method and the device of the invention make it possible to coat a strip by immersion in a current of liquid metal animated at high speeds relative to the strip. These speeds are higher than those which result from the running of the strip in a bath of liquid metal at rest.
  • Fig. 1 recalls the principle of a conventional dip coating installation of the prior art
  • Fig. 2 shows the principle of the process of the present invention
  • the Fig. 3a illustrates a first case of application of the method of the invention, with a thin rectilinear practically horizontal channel
  • Fig. 3b illustrates a second case of application of the method of the invention, with a thin curved channel in the form of a parabola
  • Fig. 3c illustrates a third case of application of the method of the invention, with a thin channel approaching the usual trajectory of the strip in a bath of liquid metal
  • Fig. 4 shows different arrangements of the liquid metal supply orifices, formed in the walls of the thin channel (Fig. 4a, b, c)
  • Fig. 5 illustrates different possible configurations of the thin channel with its liquid metal supply circuit (Fig. 5a, b, c, d).
  • Embodiments of the Invention Figure 1 shows a conventional dip galvanizing device for a steel strip, integrated in a treatment line.
  • a strip to be coated 1 is treated in a continuous annealing oven 2, from which it leaves by a tube 3 to plunge into a bath of molten zinc 4.
  • the strip 1 passes under a bottom roller 5, completely submerged in liquid zinc 4, then it is guided by stabilization rollers 6 immersed near the upper surface of the zinc bath 4, before leaving the zinc bath along a vertical path.
  • the excess zinc is drained by means of blades of gas, generally air or nitrogen, under pressure 7.
  • the strip 1 then rises vertically to an upper deflection roller 8, which is situated high enough for the zinc coating is solidified before reaching it.
  • Strip 1 then continues on its way in the processing line.
  • the strip to be coated 1 circulates through a bath of liquid zinc at rest 4, and it is in direct contact with several immersed rollers 5, 6.
  • the principle of the process of the invention is illustrated in FIG. 2.
  • the strip to be coated 1 coming from a continuous annealing furnace not shown, circulates through a thin channel 10 in which a stream of metal has been created liquid 9.
  • the channel 10 is rectilinear and slightly inclined upwards, and the circulation of the liquid metal is ensured by a pump 1 1.
  • the strip 1 and the stream of liquid metal 9 circulate in the upward direction, indicated by arrows. Sealing systems, not shown, are provided at the inlet and outlet ends of the strip 1 in the channel 10.
  • FIG. 3 shows how it is possible to control, at least in part, the position of the strip in a thin channel, according to the method of the invention.
  • a movement of circulation of the liquid metal for example molten zinc, is created in the channel 10, on either side of the strip 1.
  • This current preferably flows at high speed. , and is inevitably accompanied by pressure gradients between the strip 1 and the walls of the channel 10.
  • the hydraulic paths that the liquid metal follows in the channel 10 can be designed so as to create pressure differences between the faces of the strip and thereby influence the position of the band in the channel. Indeed, even if they are of small amplitude, these pressure differences act on large surfaces, namely the surface of the two faces of the strip in the channel, and they can thus generate considerable forces.
  • a pressure difference between the two faces of the strip can be obtained in several ways: by creating different liquid metal flow rates on the two faces, while maintaining sufficient circulation speeds; > by modifying the distance between the strip and the wall of the channel: at equal metal flow, a reduction in this distance leads to an increase in pressure; by differentiating the injection of liquid metal between the two faces of the strip, as regards both the injection pressure and the number and / or the arrangement of the injectors.
  • FIG. 3a illustrates the simple case of a thin rectilinear channel 12, practically horizontal, in which the strip 1 circulates at equal distance from the two walls.
  • the pressures 13 exerted on the lower face of the strip are higher than those 14 applied on the upper face, in order to support the weight of the strip 1 while maintaining the latter in position centered in the channel 12.
  • the channel 15 has the shape of a parabola, corresponding to the so-called “chain” shape that naturally takes the strip 1 suspended freely between two upper rollers not shown.
  • Such a parabolic trajectory of the strip 1 can be maintained by permanent control of the speed of the strip upstream and downstream of the channel 15. It is also maintained thanks to the pressures that the liquid metal exerts on the strip; if the pressures 16 on the internal face are higher than those 17 exerted on the external face, they are even capable of compensating for a traction in the strip.
  • it is particularly easy to seal the channel by collecting the liquid metal overflowing at the two ends of the channel to reintroduce it into the lower part, for example using pumps 18.
  • FIG. 3c shows a channel 15 of a shape close to that of the usual path of a strip 1 in a dip coating installation of the type illustrated in FIG. 1.
  • the strip 1, which undergoes the traction exerted by the treatment line is supported by the application of pressures 19 higher on the internal face than those 20 exerted on the external face.
  • the strip 1 can be guided in a controlled manner both at the inlet and at the outlet of the channel, by differential pressures 21, which advantageously replace, that is to say without contact, the guide rollers 6 of figure 1.
  • the channel is easily sealed by collecting excess liquid metal at the two ends of the channel to reintroduce it into the lower part, for example using a common pump 22.
  • the thin metal is supplied with liquid metal preferably by orifices in the walls of the channel, so as to distribute the pressures acting on the faces of the strip as uniformly as possible.
  • FIG. 4 shows various possible arrangements of these supply orifices in a portion of a channel wall 23.
  • the orifices can be either slots 24 parallel and / or perpendicular to the direction 25 of movement of the strip (Fig. 4a), or orifices, for example circular 26, arranged in lines also parallel to the direction 25 of movement of the strip (Fig. 4b), or even orifices, for example circular 27, distributed regularly, for example in staggered rows, in the wall of the canal (Fig. 4c).
  • FIG. 5 illustrates different possible configurations of the liquid metal circuit, with a treatment unit, possibly combined with a raised external tank.
  • FIG. 5a a horizontal rectilinear channel 12, traversed by a strip 1, is supplied directly by means of a pump 28.
  • the liquid metal is collected at the ends of the channel 12 and returned by the pump 28, d first to a processing unit 29 and then directly into the channel 12.
  • FIG. 5b also represents a horizontal rectilinear channel 12 traversed by a strip to be coated 1.
  • This channel 12 is fed by gravity from a raised reservoir 30 of large capacity, while the excess liquid metal is recovered at the ends of the channel 12 and returned, still by gravity, to a collection tank 32. From this, the liquid metal is then returned to the raised tank 30 by means of a pump 31.
  • a treatment unit 29 is placed between the tank 30 and the channel 12 and / or between the pump 31 and the reservoir 30.
  • FIG. 5c The configuration of FIG. 5c is similar to that of FIG. 5a, with the difference that the channel 33 follows here the path of the strip 1 in a conventional dip coating line.
  • the excess liquid metal is recovered at the raised ends of the channel 33 and returned to the low point of this channel, through a pump 28 and a treatment unit 29.
  • FIG. 5d illustrates an arrangement, similar to that of FIG. 5b, but where the channel 33 follows the path of the strip 1 in a conventional dip coating line.
  • the channel 33 is fed directly at its low point by gravity, from a raised reservoir 30 of large capacity; the excess liquid metal is collected at the raised ends of the channel 33 and returned, also by gravity, to a collection tank 32. From this, the liquid metal is returned to the raised tank 30 by means of a pump 31
  • a processing unit 29 is provided between the reservoir 30 and the channel 33, and / or between the pump 31 and the reservoir 30.
  • the present invention offers numerous advantages, as regards both the process itself and the quality coated products.
  • the continuous circulation of the liquid metal between the coating channel and a separate tank makes it possible to process the liquid metal continuously.
  • mattes that is to say the particles of intermetallic compounds which float in the liquid metal and which are liable to deposit on the strip.
  • This elimination can be done by any suitable method, such as filtering, decantation, centrifugation, etc., in particular in the processing unit mentioned above.
  • the quality of the coating depends in particular on the reactivity between the coating metal and the surface of the strip to be coated.
  • high-strength steels intended to be galvanized for the automotive industry have a surface that is weakly reactive with regard to zinc; this results in a lack of wettability which can lead to serious coating defects.
  • the high relative speed between the strip and the liquid metal in the coating channel causes an improvement in the reactivity between the liquid metal and the strip, and contributes to eliminating the abovementioned coating defects.
  • the introduction of a significant relative speed, for example from 0.5 m / s to 1 m / s, between the strip and the liquid metal in the channel contributes to reducing the risk of sticking to the strip, of particles suspended in the liquid metal. This effect is in addition to that of the matte removal operation mentioned above.
  • the method of the invention restores the symmetry between the two faces of the strip, owing to the fact that neither of the two faces of the strip is no longer in contact with rollers.
  • the actual duration and the conditions of exposure of the two faces of the strip to liquid metal are identical.
  • the device of the invention is much simpler than conventional dip galvanizing devices. It requires less liquid metal, it offers greater flexibility of operation and it allows obtaining better quality coated products. Finally, it can be integrated, without significant difficulty, into an existing processing line, as shown in Figure 3c.

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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)
  • Continuous Casting (AREA)
  • Chemically Coating (AREA)

Abstract

The invention concerns a method for dip coating a metal strip using a molten metal which consists in causing the metal strip to pass in a volume of said molten metal by causing said strip to circulate in a thin channel wherein the molten metal is introduced at least on either side of said strip and so as to generate a circulating movement of said molten liquid relative to the strip inside said thin channel. The pressure on the two surfaces of the strip inside said thin channel is adjusted independently of each other, and the circulating speed of the molten liquid current relative to the strip is adjusted at a value ranging between 0.5 m/s and 1 m/s.

Description

Procédé et dispositif pour le revêtement d'une bande métallique au trempé.Method and device for coating a metal strip by dipping.
Domaine techniqueTechnical area
La présente invention porte sur un procédé pour le revêtement d'une bande métallique au trempé, c'est-à-dire par défilement continu à travers un métal liquide. L'invention concerne également un dispositif pour la mise en oeuvre de ce procédé.The present invention relates to a method for coating a metallic strip by dipping, that is to say by continuous scrolling through a liquid metal. The invention also relates to a device for implementing this method.
Etat de la techniqueState of the art
L'invention sera décrite ici en faisant référence à la galvanisation au trempé d'une bande d'acier. Il faut cependant considérer que cette application n'est mentionnée qu'à titre d'exemple, et que l'invention peut aussi avantageusement être appliquée à d'autres types de substrats métalliques en forme de bande ou de fil, ainsi qu'avec d'autres métaux et alliages de revêtement.The invention will be described here with reference to the dip galvanizing of a steel strip. It should however be considered that this application is only mentioned by way of example, and that the invention can also advantageously be applied to other types of metal substrates in the form of a strip or a wire, as well as with d other coating metals and alloys.
La galvanisation au trempé d'une bande d'acier comprend généralement deux opérations principales, à savoir un recuit de la bande et le dépôt du revêtement. L'installation correspondante comporte dès lors deux grandes parties, à savoir un four de recuit et une cuve de galvanisation.Dip galvanizing of a steel strip generally comprises two main operations, namely annealing the strip and depositing the coating. The corresponding installation therefore comprises two large parts, namely an annealing oven and a galvanizing tank.
Le recuit a pour but de préparer la bande, en particulier sa surface, en vue de l'opération de revêtement qui suit. En particulier, il assure la recristallisation de la structure écrouie dans le cas d'une bande laminée à froid ; il opère également, dans tous les cas, un nettoyage et un avivage de la surface au moyen d'une atmosphère appropriée, généralement réductrice, comprenant de l'hydrogène et de l'azote.The purpose of annealing is to prepare the strip, in particular its surface, for the following coating operation. In particular, it recrystallizes the work hardened structure in the case of a cold rolled strip; it also operates, in all cases, cleaning and brightening the surface by means of an appropriate atmosphere, generally reducing, comprising hydrogen and nitrogen.
Schématiquement, la galvanisation conventionnelle consiste à faire passer une bande d'acier à travers un bain de zinc fondu puis, à la sortie de ce bain, à régler l'épaisseur de la couche de zinc par essorage au moyen de lames d'air ou d'azote sous pression.Schematically, conventional galvanizing consists in passing a steel strip through a bath of molten zinc and then, at the exit of this bath, adjusting the thickness of the zinc layer by wringing using air knives or nitrogen under pressure.
Au cours de son trajet dans le bain de zinc, la bande est guidée par plusieurs rouleaux, notamment un premier rouleau, dit rouleau de fond, entièrement immergé dans le zinc, sous lequel elle passe avant de remonter verticalement vers la surface du bain, et d'autres rouleaux, dits rouleaux de stabilisation, de déflexion ou de guidage, souvent partiellement ou même totalement immergés à proximité de la surface supérieure du bain de métal liquide, destinés à assurer la stabilisation, éventuellement la planéité de la bande revêtue, avant son essorage.During its journey in the zinc bath, the strip is guided by several rollers, in particular a first roller, called the bottom roller, entirely immersed in the zinc, under which it passes before rising vertically towards the surface of the bath, and other rollers, called stabilization, deflection or guide rollers, often partially or even completely submerged near the upper surface of the liquid metal bath, intended to ensure stabilization, possibly the flatness of the coated strip, before it is spun.
Ces rouleaux, motorisés ou libres, entrent en contact avec la surface de la bande en mouvement et peuvent ainsi engendrer des défauts de surface. Ils doivent donc être fréquemment démontés pour être inspectés, réparés voire remplacés, car leur état influence considérablement la qualité du revêtement de zinc. Il en résulte dès lors des arrêts fréquents de la ligne de production et une perte de productivité non négligeable. Par ailleurs, l'homme du métier connaît bien la difficulté de régler et de maintenir la composition du métal de revêtement. Celui-ci n'est pratiquement jamais un métal pur, mais plutôt un alliage contenant différents éléments en quantités déterminées mais variables d'un type à l'autre, destinés à améliorer les performances des revêtements, comme par exemple les additions d'aluminium dans les bains de galvanisation.These rollers, motorized or free, come into contact with the surface of the moving band and can thus cause surface defects. They must therefore be frequently dismantled to be inspected, repaired or even replaced, since their condition considerably influences the quality of the zinc coating. This results in frequent shutdowns of the production line and a significant loss of productivity. Furthermore, those skilled in the art are well aware of the difficulty of adjusting and maintaining the composition of the coating metal. It is hardly ever a pure metal, but rather an alloy containing different elements in determined quantities but variable from one type to another, intended to improve the performances of coatings, such as for example the additions of aluminum in galvanizing baths.
Enfin, les mattes, c'est-à-dire des agrégats de particules de composés intermétalliques, formés entre autres par la dissolution de l'extrême surface des bandes d'acier par le bain de métal liquide, entraînent également des défauts d'aspect bien connus, et doivent donc être régulièrement éliminées. Il en résulte des pertes de temps et de métal, qui nuisent à la productivité et à la rentabilité des procédés conventionnels.Finally, the mattes, that is to say aggregates of particles of intermetallic compounds, formed inter alia by the dissolution of the extreme surface of the steel strips by the bath of liquid metal, also cause appearance defects well known, and must therefore be regularly eliminated. This results in wasted time and metal, which adversely affects the productivity and profitability of conventional processes.
Il a déjà été proposé de remplacer le rouleau de fond par un tube semi-circulaire fixe, également immergé dans le bain de métal liquide, et muni de fentes à travers lesquelles on injecte du métal liquide de revêtement. Il se forme ainsi une zone de métal sous pression qui maintient la bande à distance de la surface du tube immergé, sans toutefois que cette distance puisse être réglée et contrôlée de façon précise. Dans la pratique également, cette solution ne remédie pas aux problèmes de stabilité de la bande, ni aux défauts de surface causés par le contact avec les rouleaux de guidage, ni davantage à la difficulté de régler la composition du métal liquide, ni enfin aux problèmes liés aux mattes à éliminer.It has already been proposed to replace the bottom roller with a fixed semi-circular tube, also immersed in the bath of liquid metal, and provided with slots through which liquid coating metal is injected. A zone of pressurized metal is thus formed which keeps the strip away from the surface of the submerged tube, without however this distance being able to be adjusted and controlled precisely. In practice also, this solution does not remedy the problems of stability of the strip, nor the surface defects caused by contact with the guide rollers, nor more the difficulty of adjusting the composition of the liquid metal, nor finally the problems related to the mattes to be eliminated.
Présentation de l'inventionPresentation of the invention
L'invention a pour objet de proposer un procédé pour le revêtement d'une bande métallique au trempé, qui permet de remédier aux inconvénients précités, notamment en supprimant tous les rouleaux immergés et en assurant une composition constante du métal liquide dans la zone de revêtement. Dans un autre aspect, elle propose un dispositif pour la mise en oeuvre de ce procédé.The object of the invention is to propose a method for coating a metallic strip by dipping, which makes it possible to remedy the aforementioned drawbacks, in particular removing all submerged rollers and ensuring a constant composition of the liquid metal in the coating area. In another aspect, it proposes a device for implementing this method.
Conformément à l'invention, un procédé pour le revêtement d'une bande métallique au trempé au moyen d'un métal liquide, dans lequel on fait passer ladite bande dans un volume dudit métal liquide, est caractérisé en ce que l'on fait circuler ladite bande dans un mince canal, en ce que l'on introduit le métal liquide dans ledit mince canal au moins de part et d'autre de ladite bande, et en ce que l'on crée un mouvement de circulation dudit métal liquide par rapport à ladite bande, à l'intérieur dudit mince canal. On constate alors qu'on effectue donc le revêtement par contact de la surface de la bande métallique avec un flux de métal liquide plutôt que d'effectuer un revêtement de ladite surface par immersion dans un bain de métal liquide.According to the invention, a method for coating a metallic strip by dipping by means of a liquid metal, in which said strip is passed through a volume of said liquid metal, is characterized in that one circulates said strip in a thin channel, in that the liquid metal is introduced into said thin channel at least on either side of said strip, and in that a movement of circulation of said liquid metal is created relative to to said strip, inside said thin channel. It is then found that the coating is therefore carried out by contacting the surface of the metal strip with a flow of liquid metal rather than coating the said surface by immersion in a bath of liquid metal.
Selon l'invention, on alimente ledit mince canal en métal liquide à partir d'une source séparée, constituée par exemple par un réservoir séparé; un tel réservoir séparé est avantageusement disposé plus haut que ledit mince canal, de façon à assurer l'alimentation au moins partiellement par un effet gravimétrique. Une partie ou la totalité de l'alimentation peut cependant aussi être assurée par une ou plusieurs pompes.According to the invention, said thin channel is supplied with liquid metal from a separate source, constituted for example by a separate reservoir; such a separate tank is advantageously disposed higher than said thin channel, so as to supply at least partially by a gravimetric effect. Part or all of the supply can however also be provided by one or more pumps.
Selon une caractéristique intéressante, on soumet le métal liquide à au moins un traitement avant de l'introduire dans ledit mince canal. En particulier, ledit traitement peut consister à filtrer le métal liquide avant de l'introduire dans le mince canal. On réduit ainsi le risque de déposer des particules flottantes, telles que des composés intermétalliques, sur la surface de la bande.According to an advantageous characteristic, the liquid metal is subjected to at least one treatment before introducing it into said thin channel. In particular, said treatment can consist in filtering the liquid metal before introducing it into the thin channel. This reduces the risk of depositing floating particles, such as intermetallic compounds, on the surface of the strip.
Suivant une autre caractéristique, on mesure à des intervalles déterminés, de préférence en continu, la composition chimique et/ou la température du métal liquide et, le cas échéant, on ajuste cette composition chimique et/ou cette température avant d'introduire le métal liquide dans ledit mince canal. Il est ainsi possible de maintenir au moins sensiblement constantes ces conditions régissant l'opération de revêtement au trempé de la bande métallique. Selon une autre caractéristique avantageuse, on réalise l'alimentation dudit mince canal en circuit fermé. On évite ainsi tout contact du métal liquide avec l'air ambiant, et de ce fait tout risque d'altération du métal liquide, en particulier par oxydation.According to another characteristic, the chemical composition and / or the temperature of the liquid metal are measured at determined intervals, preferably continuously, and, if necessary, this chemical composition and / or this temperature is adjusted before introducing the metal. liquid in said thin channel. It is thus possible to maintain at least substantially constant these conditions governing the dip coating operation of the metal strip. According to another advantageous characteristic, the supply of said thin channel is carried out in a closed circuit. This avoids any contact of the liquid metal with the ambient air, and therefore any risk of deterioration of the liquid metal, in particular by oxidation.
Selon une caractéristique particulièrement intéressante, on alimente ledit mince canal en métal liquide sous une pression réglable de façon indépendante sur chaque face de la bande. Suivant une méthode bien connue en soi, on règle la pression d'alimentation du métal liquide, selon le cas, en faisant varier la différence de niveau entre le mince canal et le réservoir séparé, ou en modifiant la pression fournie par les pompes d'alimentation.According to a particularly advantageous characteristic, said thin channel is supplied with liquid metal under an independently adjustable pressure on each face of the strip. According to a method well known in itself, the liquid metal feed pressure is adjusted, as the case may be, by varying the level difference between the thin channel and the separate reservoir, or by modifying the pressure supplied by the pumps. food.
Suivant encore une autre caractéristique particulièrement avantageuse, la vitesse de circulation du courant de métal liquide par rapport à la bande, à l'intérieur dudit canal mince, est comprise entre 0,1 m/s et 5 m/s.According to yet another particularly advantageous characteristic, the speed of circulation of the stream of liquid metal with respect to the strip, inside said thin channel, is between 0.1 m / s and 5 m / s.
Il s'est avéré avantageux d'appliquer une pression identique de part et d'autre de la bande dans le mince canal. On peut cependant imaginer d'appliquer des pressions différentes de part et d'autre de la bande, notamment en vue d'influer sur la réactivité de surface de ladite bande métallique.It has proven advantageous to apply identical pressure on either side of the strip in the thin channel. One can however imagine applying different pressures on either side of the strip, in particular in order to influence the surface reactivity of said metal strip.
Un dispositif pour la mise en oeuvre de ce procédé comprend essentiellement un mince canal, des moyens pour faire circuler la bande à revêtir à travers ledit mince canal, ainsi que des moyens pour alimenter ledit mince canal en métal liquide et pour créer un mouvement de circulation du métal liquide par rapport à la bande, à l'intérieur du mince canal.A device for implementing this method essentially comprises a thin channel, means for circulating the strip to be coated through said thin channel, as well as means for supplying said thin channel with liquid metal and for creating a circulation movement. liquid metal relative to the strip, inside the thin channel.
La section du mince canal suivant l'invention est déterminée de façon à permettre le passage de la bande la plus large qui doit y être revêtue, sans nécessiter de débit excessif de métal liquide.The section of the thin channel according to the invention is determined so as to allow the passage of the widest strip which must be coated therein, without requiring an excessive flow of liquid metal.
Compte tenu de la largeur des bandes actuelles, la largeur du mince canal suivant l'invention est généralement comprise entre 1 m et 2 m. Il va de soi que cette largeur pourrait être augmentée ou diminuée en fonction de circonstances particulières. La hauteur du mince canal définit l'épaisseur de la couche de métal liquide en circulation, et par conséquent influence aussi le débit de métal liquide dans le mince canal. Cette hauteur est de préférence inférieure à 6 cm, et de préférence encore inférieure à 3 cm, de façon à pouvoir limiter le débit de métal liquide dans le mince canal.Given the width of the current strips, the width of the thin channel according to the invention is generally between 1 m and 2 m. It goes without saying that this width could be increased or decreased depending on particular circumstances. The height of the thin channel defines the thickness of the layer of liquid metal in circulation, and therefore also influences the flow of liquid metal in the thin channel. This height is preferably less than 6 cm, and more preferably less than 3 cm, so as to be able to limit the flow of liquid metal in the thin channel.
Le mince canal suivant l'invention peut présenter une forme soit plane, soit courbe, en particulier partiellement cylindrique. Dans ce dernier cas, la courbure doit être limitée afin de ne pas compliquer inutilement la trajectoire et le guidage de la bande.The thin channel according to the invention may have a shape either planar or curved, in particular partially cylindrical. In the latter case, the curvature must be limited so as not to unnecessarily complicate the trajectory and guiding of the strip.
La bande à revêtir circule à travers ledit canal sous l'action de la traction exercée par les systèmes d'entraînement de la ligne de revêtement. Sa trajectoire est déterminée par des moyens de guidage, généralement des rouleaux, disposés à l'extérieur du canal, en amont et en aval de celui-ci, de façon à ne pas endommager la surface de la bande pendant l'opération de revêtement.The strip to be coated circulates through said channel under the action of the traction exerted by the drive systems of the coating line. Its trajectory is determined by guide means, generally rollers, arranged outside the channel, upstream and downstream thereof, so as not to damage the surface of the strip during the coating operation.
A l'intérieur du mince canal, la bande doit dès lors être maintenue à une distance minimale des parois du canal, afin d'éviter tout risque de contact avec celles-ci. En règle générale, cette distance est comprise entre 1 mm et 15 mm, en fonction de divers paramètres tels que la vitesse et la largeur de la bande, la nature du métal liquide, la longueur et/ou la forme de la trajectoire du mince canal.Inside the thin channel, the strip must therefore be kept at a minimum distance from the walls of the channel, in order to avoid any risk of contact with them. As a rule, this distance is between 1 mm and 15 mm, depending on various parameters such as the speed and width of the strip, the nature of the liquid metal, the length and / or the shape of the path of the thin channel. .
Le mince canal suivant l'invention comporte d'une part des moyens d'alimentation en métal liquide, et d'autre part des moyens pour créer un mouvement de circulation du métal liquide par rapport à la bande, à l'intérieur du mince canal.The thin channel according to the invention comprises on the one hand means for supplying liquid metal, and on the other hand means for creating a movement of circulation of the liquid metal with respect to the strip, inside the thin channel .
Lesdits moyens d'alimentation comprennent au moins un réservoir séparé, d'une capacité nettement plus grande que le mince canal; ce réservoir est relié au mince canal par un circuit d'alimentation conduisant à des moyens d'introduction du métal liquide dans le mince canal, de part et d'autre de la bande qui y circule. Ces moyens d'introduction peuvent être constitués soit par des injecteurs disposés à au moins une des extrémités du canal, soit par des injecteurs ménagés dans les parois du canal parallèles au plan de la bande, soit encore par une combinaison de ces deux types d'injecteurs. Pour assurer la circulation du métal liquide, y compris dans le mince canal, le réservoir séparé peut être surélevé par rapport au mince canal, ou le circuit d'alimentation peut comporter au moins une pompe.Said supply means comprise at least one separate tank, with a capacity much larger than the thin channel; this reservoir is connected to the thin channel by a supply circuit leading to means for introducing the liquid metal into the thin channel, on either side of the strip which circulates there. These introduction means can be constituted either by injectors arranged at at least one of the ends of the channel, or by injectors formed in the walls of the channel parallel to the plane of the strip, or even by a combination of these two types of injectors. To ensure the circulation of the liquid metal, including in the thin channel, the separate reservoir can be raised relative to the thin channel, or the supply circuit can comprise at least one pump.
D'une façon également avantageuse, le dispositif comprend aussi des moyens de contrôle et de réglage de la température et/ou de la composition du métal liquide, des moyens pour ajouter du métal liquide frais ainsi que des moyens pour filtrer le métal liquide avant son introduction dans le mince canal.Also advantageously, the device also comprises means for controlling and adjusting the temperature and / or the composition of the liquid metal, means for adding fresh liquid metal as well as means for filtering the liquid metal before it introduction into the thin channel.
En outre, le canal est pourvu de moyens d'étanchéité, tels que des sas à ses extrémités, permettant le passage de la bande mais empêchant les fuites de métal liquide.In addition, the channel is provided with sealing means, such as airlocks at its ends, allowing the passage of the strip but preventing the leakage of liquid metal.
Enfin, le canal peut avantageusement être intégré dans un circuit fermé, comprenant également au moins un réservoir d'alimentation, éventuellement surélevé, un circuit d'alimentation du mince canal, un circuit de récupération du métal liquide en excès, des moyens de traitement du métal liquide, et éventuellement au moins une pompe de circulation du métal liquide.Finally, the channel can advantageously be integrated into a closed circuit, also comprising at least one supply reservoir, possibly raised, a circuit for supplying the thin channel, a circuit for recovering excess liquid metal, means for treating the liquid metal, and optionally at least one liquid metal circulation pump.
Le procédé et le dispositif de l'invention permettent de revêtir une bande par immersion dans un courant de métal liquide animé de vitesses élevées par rapport à la bande. Ces vitesses sont supérieures à celles qui résultent du défilement de la bande dans un bain de métal liquide au repos.The method and the device of the invention make it possible to coat a strip by immersion in a current of liquid metal animated at high speeds relative to the strip. These speeds are higher than those which result from the running of the strip in a bath of liquid metal at rest.
Par rapport à la technique antérieure, le procédé de l'invention offre de nombreux avantages, qui seront explicités plus loin, lors de la description des dessins annexés.Compared to the prior art, the method of the invention offers numerous advantages, which will be explained below, when describing the accompanying drawings.
Brève description des dessinsBrief description of the drawings
Des exemples de réalisation du dispositif de l'invention sont représentés de façon schématique dans les dessins annexés, dans lesquels laExamples of the device of the invention are shown schematically in the accompanying drawings, in which the
Fig. 1 rappelle le principe d'une installation conventionnelle de revêtement au trempé de la technique antérieure; la Fig. 2 montre le principe du procédé de la présente invention; la Fig. 3a illustre un premier cas d'application du procédé de l'invention, avec un mince canal rectiligne pratiquement horizontal; la Fig. 3b illustre un deuxième cas d'application du procédé de l'invention, avec un mince canal courbe en forme de parabole; la Fig. 3c illustre un troisième cas d'application du procédé de l'invention, avec un mince canal approchant la trajectoire habituelle de la bande dans un bain de métal liquide; la Fig. 4 montre différentes dispositions des orifices d'alimentation en métal liquide, ménagés dans les parois du mince canal (Fig. 4a, b, c); et la Fig. 5 illustre différentes configurations possibles du mince canal avec son circuit d'alimentation en métal liquide (Fig. 5a, b, c, d).Fig. 1 recalls the principle of a conventional dip coating installation of the prior art; Fig. 2 shows the principle of the process of the present invention; the Fig. 3a illustrates a first case of application of the method of the invention, with a thin rectilinear practically horizontal channel; Fig. 3b illustrates a second case of application of the method of the invention, with a thin curved channel in the form of a parabola; Fig. 3c illustrates a third case of application of the method of the invention, with a thin channel approaching the usual trajectory of the strip in a bath of liquid metal; Fig. 4 shows different arrangements of the liquid metal supply orifices, formed in the walls of the thin channel (Fig. 4a, b, c); and Fig. 5 illustrates different possible configurations of the thin channel with its liquid metal supply circuit (Fig. 5a, b, c, d).
Ces figures ne constituent que des représentations schématiques simplifiées, dans lesquelles on n'a reproduit que les éléments nécessaires à la compréhension de l'invention. Le sens de circulation du métal liquide est indiqué par des flèches. Des éléments identiques sont désignés par les mêmes repères numériques dans toutes les figures.These figures constitute only simplified schematic representations, in which only the elements necessary for understanding the invention have been reproduced. The direction of flow of the liquid metal is indicated by arrows. Identical elements are designated by the same reference numerals in all the figures.
Modes de réalisation de l'invention La figure 1 représente un dispositif conventionnel de galvanisation au trempé d'une bande d'acier, intégré dans une ligne de traitement. Dans ce dispositif, une bande à revêtir 1 est traitée dans un four de recuit continu 2, dont elle sort par une trompe 3 pour plonger dans un bain de zinc en fusion 4. La bande 1 passe sous un rouleau de fond 5, complètement immergé dans le zinc liquide 4, puis elle est guidée par des rouleaux de stabilisation 6 immergés à proximité de la surface supérieure du bain de zinc 4, avant de quitter le bain de zinc suivant une trajectoire verticale. L'excès de zinc est essoré au moyen de lames de gaz, généralement d'air ou d'azote, sous pression 7. La bande 1 monte ensuite verticalement jusqu'à un rouleau de déviation supérieur 8, qui est situé suffisamment haut pour que le revêtement de zinc soit solidifié avant de l'atteindre. La bande 1 poursuit ensuite son chemin dans la ligne de traitement.Embodiments of the Invention Figure 1 shows a conventional dip galvanizing device for a steel strip, integrated in a treatment line. In this device, a strip to be coated 1 is treated in a continuous annealing oven 2, from which it leaves by a tube 3 to plunge into a bath of molten zinc 4. The strip 1 passes under a bottom roller 5, completely submerged in liquid zinc 4, then it is guided by stabilization rollers 6 immersed near the upper surface of the zinc bath 4, before leaving the zinc bath along a vertical path. The excess zinc is drained by means of blades of gas, generally air or nitrogen, under pressure 7. The strip 1 then rises vertically to an upper deflection roller 8, which is situated high enough for the zinc coating is solidified before reaching it. Strip 1 then continues on its way in the processing line.
Dans ce dispositif classique, la bande à revêtir 1 circule à travers un bain de zinc liquide au repos 4, et elle est en contact direct avec plusieurs rouleaux immergés 5, 6. Le principe du procédé de l'invention est illustré dans la figure 2. Ici, la bande à revêtir 1 , provenant d'un four de recuit continu non représenté, circule à travers un mince canal 10 dans lequel on a créé un courant de métal liquide 9. Dans cette figure, le canal 10 est rectiligne et légèrement incliné vers le haut, et la circulation du métal liquide est assurée par une pompe 1 1. Dans cette illustration, la bande 1 et le courant de métal liquide 9 circulent dans le sens ascendant, indiqué par des flèches. Des systèmes d'étanchéité, non représentés, sont prévus aux extrémités d'entrée et de sortie de la bande 1 dans le canal 10.In this conventional device, the strip to be coated 1 circulates through a bath of liquid zinc at rest 4, and it is in direct contact with several immersed rollers 5, 6. The principle of the process of the invention is illustrated in FIG. 2. Here, the strip to be coated 1, coming from a continuous annealing furnace not shown, circulates through a thin channel 10 in which a stream of metal has been created liquid 9. In this figure, the channel 10 is rectilinear and slightly inclined upwards, and the circulation of the liquid metal is ensured by a pump 1 1. In this illustration, the strip 1 and the stream of liquid metal 9 circulate in the upward direction, indicated by arrows. Sealing systems, not shown, are provided at the inlet and outlet ends of the strip 1 in the channel 10.
D'autres configurations possibles sont illustrées et décrites dans la figure 3. Cette figure 3 montre comment il est possible de contrôler, au moins en partie, la position de la bande dans un mince canal, suivant le procédé de l'invention.Other possible configurations are illustrated and described in FIG. 3. This FIG. 3 shows how it is possible to control, at least in part, the position of the strip in a thin channel, according to the method of the invention.
Comme on l'a indiqué plus haut, on crée un mouvement de circulation du métal liquide, par exemple du zinc en fusion, dans le canal 10, de part et d'autre de la bande 1. Ce courant circule de préférence à grande vitesse, et s'accompagne inévitablement de gradients de pression entre la bande 1 et les parois du canal 10. Les chemins hydrauliques que le métal liquide suit dans le canal 10 peuvent être conçus de façon à créer des différences de pression entre les faces de la bande et à influencer ainsi la position de la bande dans le canal. En effet, même si elles sont de faible amplitude, ces différences de pression agissent sur des surfaces importantes, à savoir la surface des deux faces de la bande dans le canal, et elles peuvent ainsi générer des forces considérables.As indicated above, a movement of circulation of the liquid metal, for example molten zinc, is created in the channel 10, on either side of the strip 1. This current preferably flows at high speed. , and is inevitably accompanied by pressure gradients between the strip 1 and the walls of the channel 10. The hydraulic paths that the liquid metal follows in the channel 10 can be designed so as to create pressure differences between the faces of the strip and thereby influence the position of the band in the channel. Indeed, even if they are of small amplitude, these pressure differences act on large surfaces, namely the surface of the two faces of the strip in the channel, and they can thus generate considerable forces.
A titre d'exemple, une différence de pression entre les deux faces de la bande peut être obtenue de plusieurs manières: en créant des débits de métal liquide différents sur les deux faces, tout en conservant des vitesses de circulation suffisantes; > en modifiant la distance entre la bande et la paroi du canal: à débit de métal égal, une diminution de cette distance entraîne une augmentation de la pression; en différenciant l'injection de métal liquide entre les deux faces de la bande, en ce qui concerne aussi bien la pression d'injection que le nombre et/ou la disposition des injecteurs. La figure 3a illustre le cas simple d'un mince canal 12 rectiligne, pratiquement horizontal, dans lequel la bande 1 circule à égale distance des deux parois. Les pressions 13 exercées sur la face inférieure de la bande sont plus élevées que celles 14 appliquées sur la face supérieure, afin de supporter le poids de la bande 1 tout en maintenant celle-ci en position centrée dans le canal 12.By way of example, a pressure difference between the two faces of the strip can be obtained in several ways: by creating different liquid metal flow rates on the two faces, while maintaining sufficient circulation speeds; > by modifying the distance between the strip and the wall of the channel: at equal metal flow, a reduction in this distance leads to an increase in pressure; by differentiating the injection of liquid metal between the two faces of the strip, as regards both the injection pressure and the number and / or the arrangement of the injectors. FIG. 3a illustrates the simple case of a thin rectilinear channel 12, practically horizontal, in which the strip 1 circulates at equal distance from the two walls. The pressures 13 exerted on the lower face of the strip are higher than those 14 applied on the upper face, in order to support the weight of the strip 1 while maintaining the latter in position centered in the channel 12.
Dans la figure 3b, le canal 15 présente la forme d'une parabole, correspondant à la forme dite "en chaînette" que prend naturellement la bande 1 suspendue librement entre deux rouleaux supérieurs non représentés.In Figure 3b, the channel 15 has the shape of a parabola, corresponding to the so-called "chain" shape that naturally takes the strip 1 suspended freely between two upper rollers not shown.
Une telle trajectoire parabolique de la bande 1 peut être maintenue par un contrôle permanent de la vitesse de la bande en amont et en aval du canal 15. Elle est aussi maintenue grâce aux pressions que le métal liquide exerce sur la bande; si les pressions 16 sur la face interne sont plus élevées que celles 17 exercées sur la face externe, elles sont même capables de compenser une traction dans la bande. Dans une telle configuration du canal, il est particulièrement aisé d'assurer l'étanchéité du canal, en recueillant le métal liquide débordant aux deux extrémités du canal pour le réintroduire dans la partie inférieure, par exemple à l'aide de pompes 18.Such a parabolic trajectory of the strip 1 can be maintained by permanent control of the speed of the strip upstream and downstream of the channel 15. It is also maintained thanks to the pressures that the liquid metal exerts on the strip; if the pressures 16 on the internal face are higher than those 17 exerted on the external face, they are even capable of compensating for a traction in the strip. In such a configuration of the channel, it is particularly easy to seal the channel, by collecting the liquid metal overflowing at the two ends of the channel to reintroduce it into the lower part, for example using pumps 18.
Enfin, la figure 3c montre un canal 15 d'une forme proche de celle du trajet habituel d'une bande 1 dans une installation de revêtement au trempé du type illustré dans la figure 1. Dans cette configuration, la bande 1 , qui subit la traction exercée par la ligne de traitement, est supportée par l'application de pressions 19 plus élevées sur la face interne que celles 20 exercées sur la face externe. En outre, la bande 1 peut être guidée de façon contrôlée tant à l'entrée qu'à la sortie du canal, par des pressions différentielles 21 , qui remplacent avantageusement, c'est-à-dire sans contact, les rouleaux de guidage 6 de la figure 1.Finally, FIG. 3c shows a channel 15 of a shape close to that of the usual path of a strip 1 in a dip coating installation of the type illustrated in FIG. 1. In this configuration, the strip 1, which undergoes the traction exerted by the treatment line is supported by the application of pressures 19 higher on the internal face than those 20 exerted on the external face. In addition, the strip 1 can be guided in a controlled manner both at the inlet and at the outlet of the channel, by differential pressures 21, which advantageously replace, that is to say without contact, the guide rollers 6 of figure 1.
Ici également, l'étanchéité du canal est assurée avec facilité en recueillant le métal liquide en excès aux deux extrémités du canal pour le réintroduire dans la partie inférieure, par exemple à l'aide d'une pompe commune 22. L'alimentation du mince canal en métal liquide est de préférence assurée par des orifices ménagés dans les parois du canal, de façon à répartir d'une façon aussi uniforme que possible les pressions agissant sur les faces de la bande.Here too, the channel is easily sealed by collecting excess liquid metal at the two ends of the channel to reintroduce it into the lower part, for example using a common pump 22. The thin metal is supplied with liquid metal preferably by orifices in the walls of the channel, so as to distribute the pressures acting on the faces of the strip as uniformly as possible.
La figure 4 montre diverses dispositions possibles de ces orifices d'alimentation dans une portion d'une paroi de canal 23. Dans les exemples représentés, les orifices peuvent être soit des fentes 24 parallèles et/ou perpendiculaires à la direction 25 de déplacement de la bande (Fig. 4a), soit des orifices, par exemple circulaires 26, disposés suivant des lignes également parallèles à la direction 25 de déplacement de la bande (Fig. 4b), soit encore des orifices, par exemple circulaires 27, répartis régulièrement, par exemple en quinconce, dans la paroi du canal (Fig. 4c).FIG. 4 shows various possible arrangements of these supply orifices in a portion of a channel wall 23. In the examples shown, the orifices can be either slots 24 parallel and / or perpendicular to the direction 25 of movement of the strip (Fig. 4a), or orifices, for example circular 26, arranged in lines also parallel to the direction 25 of movement of the strip (Fig. 4b), or even orifices, for example circular 27, distributed regularly, for example in staggered rows, in the wall of the canal (Fig. 4c).
Ces dispositions sont données à titre de simples exemples et n'excluent nullement toute autre disposition d'orifices permettant d'obtenir une répartition uniforme des pressions dans le canal.These arrangements are given by way of simple examples and do not in any way exclude any other arrangement of orifices making it possible to obtain a uniform distribution of the pressures in the channel.
On a déjà mentionné plus haut la possibilité, dans le procédé de l'invention, d'effectuer différentes opérations sur le métal liquide en circulation, en particulier de filtrer les particules de composés intermétalliques et de contrôler et/ou d'ajuster la température et/ou la composition chimique du métal liquide, avant de l'introduire dans le canal de revêtement.We have already mentioned above the possibility, in the process of the invention, of carrying out different operations on the liquid metal in circulation, in particular of filtering the particles of intermetallic compounds and of controlling and / or adjusting the temperature and / or the chemical composition of the liquid metal, before introducing it into the coating channel.
Par ailleurs, on a également souligné l'intérêt de prévoir un réservoir extérieur, c'est-à- dire distinct du mince canal proprement dit mais communiquant avec celui-ci, et de mettre le métal liquide en circulation entre le mince canal - de faible capacité - et le réservoir extérieur de plus grande capacité.Furthermore, the advantage has also been emphasized of providing an external reservoir, that is to say separate from the thin channel proper but communicating with it, and of putting the liquid metal in circulation between the thin channel - low capacity - and the larger external tank.
La figure 5 illustre différentes configurations possibles du circuit du métal liquide, avec une unité de traitement, éventuellement combinée à un réservoir extérieur surélevé.FIG. 5 illustrates different possible configurations of the liquid metal circuit, with a treatment unit, possibly combined with a raised external tank.
Dans la disposition de la figure 5a, un canal rectiligne horizontal 12, parcouru par une bande 1 , est alimenté en direct au moyen d'une pompe 28. Le métal liquide est récupéré aux extrémités du canal 12 et renvoyé par la pompe 28, d'abord à une unité de traitement 29 et ensuite directement dans le canal 12. La figure 5b représente également un canal rectiligne horizontal 12 parcouru par une bande à revêtir 1. Ce canal 12 est alimenté par gravité à partir d'un réservoir surélevé 30 de grande capacité, tandis que le métal liquide en excès est récupéré aux extrémités du canal 12 et renvoyé, toujours par gravité, dans un réservoir de collecte 32. A partir de celui-ci, le métal liquide est alors renvoyé au réservoir surélevé 30 au moyen d'une pompe 31. Une unité de traitement 29 est placée entre le réservoir 30 et le canal 12 et/ou entre la pompe 31 et le réservoir 30.In the arrangement of FIG. 5a, a horizontal rectilinear channel 12, traversed by a strip 1, is supplied directly by means of a pump 28. The liquid metal is collected at the ends of the channel 12 and returned by the pump 28, d first to a processing unit 29 and then directly into the channel 12. FIG. 5b also represents a horizontal rectilinear channel 12 traversed by a strip to be coated 1. This channel 12 is fed by gravity from a raised reservoir 30 of large capacity, while the excess liquid metal is recovered at the ends of the channel 12 and returned, still by gravity, to a collection tank 32. From this, the liquid metal is then returned to the raised tank 30 by means of a pump 31. A treatment unit 29 is placed between the tank 30 and the channel 12 and / or between the pump 31 and the reservoir 30.
La configuration de la figure 5c est analogue à celle de la figure 5a, avec la différence que le canal 33 épouse ici le trajet de la bande 1 dans une ligne de revêtement au trempé conventionnelle. Le métal liquide en excès est récupéré aux extrémités surélevées du canal 33 et renvoyé au point bas de ce canal, à travers une pompe 28 et une unité de traitement 29.The configuration of FIG. 5c is similar to that of FIG. 5a, with the difference that the channel 33 follows here the path of the strip 1 in a conventional dip coating line. The excess liquid metal is recovered at the raised ends of the channel 33 and returned to the low point of this channel, through a pump 28 and a treatment unit 29.
Enfin, la figure 5d illustre une disposition, analogue à celle de la figure 5b, mais où le canal 33 épouse le trajet de la bande 1 dans une ligne de revêtement au trempé conventionnelle. Le canal 33 est alimenté directement en son point bas par gravité, à partir d'un réservoir surélevé 30 de grande capacité; le métal liquide en excès est récupéré aux extrémités surélevées du canal 33 et renvoyé, également par gravité, dans un réservoir de collecte 32. A partir de celui-ci, le métal liquide est renvoyé au réservoir surélevé 30 au moyen d'une pompe 31. Une unité de traitement 29 est prévue entre le réservoir 30 et le canal 33, et/ou entre la pompe 31 et le réservoir 30.Finally, FIG. 5d illustrates an arrangement, similar to that of FIG. 5b, but where the channel 33 follows the path of the strip 1 in a conventional dip coating line. The channel 33 is fed directly at its low point by gravity, from a raised reservoir 30 of large capacity; the excess liquid metal is collected at the raised ends of the channel 33 and returned, also by gravity, to a collection tank 32. From this, the liquid metal is returned to the raised tank 30 by means of a pump 31 A processing unit 29 is provided between the reservoir 30 and the channel 33, and / or between the pump 31 and the reservoir 30.
Par rapport à la technique antérieure d'immersion d'une bande en mouvement dans un bain de métal liquide, de grand volume, au repos, la présente invention offre de nombreux avantages, en ce qui concerne aussi bien le procédé proprement dit que la qualité des produits revêtus.Compared to the prior art of immersing a moving strip in a bath of liquid metal, of large volume, at rest, the present invention offers numerous advantages, as regards both the process itself and the quality coated products.
En matière de procédé, un avantage important est la grande souplesse conférée à la ligne de traitement concernant la nature du métal déposé. Il suffit en effet de changer de réservoir d'alimentation pour passer d'un revêtement à un autre.In terms of process, an important advantage is the great flexibility given to the treatment line concerning the nature of the metal deposited. It suffices to change the supply tank to go from one coating to another.
D'autre part, la circulation continue du métal liquide entre le canal de revêtement et un réservoir séparé permet de traiter le métal liquide en continu. On peut en effet contrôler, et au besoin ajuster, tant la température que la composition chimique du métal liquide.On the other hand, the continuous circulation of the liquid metal between the coating channel and a separate tank makes it possible to process the liquid metal continuously. We can indeed control, and if necessary adjust, both the temperature and the chemical composition of the liquid metal.
Il est également possible d'éliminer les mattes, c'est-à-dire les particules de composés intermétalliques qui flottent dans le métal liquide et qui risquent de se déposer sur la bande. Cette élimination peut se faire par toute méthode appropriée, telle que filtrage, décantation, centrifugation, etc., en particulier dans l'unité de traitement mentionnée plus haut.It is also possible to remove the mattes, that is to say the particles of intermetallic compounds which float in the liquid metal and which are liable to deposit on the strip. This elimination can be done by any suitable method, such as filtering, decantation, centrifugation, etc., in particular in the processing unit mentioned above.
Enfin, il convient de souligner la facilité de maintenance du dispositif de l'invention. Les rouleaux immergés ayant disparu, la maintenance concerne essentiellement les pompes, qui peuvent d'ailleurs être doublées et dès lors entretenues en alternance sans que la ligne de revêtement doive être mise à l'arrêt.Finally, it should be emphasized the ease of maintenance of the device of the invention. The submerged rollers having disappeared, maintenance mainly concerns the pumps, which can moreover be doubled and therefore maintained alternately without the coating line having to be stopped.
La qualité du revêtement dépend notamment de la réactivité entre le métal de revêtement et la surface de la bande à revêtir. A titre d'exemple, les aciers à haute résistance destinés à être galvanisés pour l'industrie automobile, ont une surface faiblement réactive à l'égard du zinc; il en résulte un manque de mouillabilité qui peut conduire à de graves défauts de revêtement.The quality of the coating depends in particular on the reactivity between the coating metal and the surface of the strip to be coated. By way of example, high-strength steels intended to be galvanized for the automotive industry have a surface that is weakly reactive with regard to zinc; this results in a lack of wettability which can lead to serious coating defects.
A cet égard, on a constaté que la vitesse relative élevée entre la bande et le métal liquide dans le canal de revêtement provoquait une amélioration de la réactivité entre le métal liquide et la bande, et contribuait à supprimer les défauts de revêtement précités.In this regard, it has been found that the high relative speed between the strip and the liquid metal in the coating channel causes an improvement in the reactivity between the liquid metal and the strip, and contributes to eliminating the abovementioned coating defects.
De même, l'instauration d'une vitesse relative significative, par exemple de 0,5 m/s à 1 m/s, entre la bande et le métal liquide dans le canal, contribue à réduire le risque de collage sur la bande, de particules en suspension dans le métal liquide. Cet effet s'ajoute à celui de l'opération d'élimination des mattes mentionnée plus haut. Enfin, le procédé de l'invention rétablit la symétrie entre les deux faces de la bande, du fait qu'aucune des deux faces de la bande n'est désormais plus en contact avec des rouleaux. La durée réelle et les conditions d'exposition des deux faces de la bande au métal liquide sont identiques. Le dispositif de l'invention est nettement plus simple que les dispositifs conventionnels de galvanisation au trempé. Il nécessite une moins grande quantité de métal liquide, il offre une plus grande souplesse de fonctionnement et il permet d'obtenir des produits revêtus de meilleure qualité. Enfin, il peut s'intégrer, sans difficulté importante, dans une ligne de traitement existante, comme le montre la figure 3c. Similarly, the introduction of a significant relative speed, for example from 0.5 m / s to 1 m / s, between the strip and the liquid metal in the channel, contributes to reducing the risk of sticking to the strip, of particles suspended in the liquid metal. This effect is in addition to that of the matte removal operation mentioned above. Finally, the method of the invention restores the symmetry between the two faces of the strip, owing to the fact that neither of the two faces of the strip is no longer in contact with rollers. The actual duration and the conditions of exposure of the two faces of the strip to liquid metal are identical. The device of the invention is much simpler than conventional dip galvanizing devices. It requires less liquid metal, it offers greater flexibility of operation and it allows obtaining better quality coated products. Finally, it can be integrated, without significant difficulty, into an existing processing line, as shown in Figure 3c.

Claims

REVENDICATIONS
Procédé pour le revêtement d'une bande métallique au trempé au moyen d'un métal liquide, dans lequel on fait passer ladite bande dans un volume dudit métal liquide, caractérisé en ce que l'on fait circuler ladite bande dans un mince canal, en ce que l'on introduit le métal liquide dans ledit mince canal au moins de part et d'autre de ladite bande, et en ce que l'on crée un mouvement de circulation dudit métal liquide par rapport à ladite bande, à l'intérieur dudit mince canal.Method for coating a metallic strip by dipping by means of a liquid metal, in which said strip is passed through a volume of said liquid metal, characterized in that said strip is circulated in a thin channel, in that the liquid metal is introduced into said thin channel at least on either side of said strip, and in that a movement of circulation of said liquid metal is created relative to said strip, inside of said thin channel.
2. Procédé suivant la revendication 1 , caractérisé en ce que l'on alimente ledit mince canal à partir d'une source de métal liquide séparée.2. Method according to claim 1, characterized in that said thin channel is supplied from a separate source of liquid metal.
3. Procédé suivant la revendication 2, caractérisé en ce que l'on alimente ledit mince canal par gravité, à partir de ladite source séparée.3. Method according to claim 2, characterized in that one feeds said thin channel by gravity, from said separate source.
4. Procédé suivant la revendication 2, caractérisé en ce qu'on inclut dans la liaison destinée à alimenter ledit mince canal à partir d'une source de métal liquide séparée une ou plusieurs pompes.4. Method according to claim 2, characterized in that included in the connection intended to supply said thin channel from a separate source of liquid metal one or more pumps.
5. Procédé suivant l'une ou l'autre des revendications 1 à 4, caractérisé en ce que l'on filtre ledit métal liquide avant de l'introduire dans ledit mince canal.5. Method according to either of claims 1 to 4, characterized in that said liquid metal is filtered before introducing it into said thin channel.
6. Procédé suivant l'une ou l'autre des revendications 1 à 5, caractérisé en ce que l'on mesure et, le cas échéant, on ajuste la température du métal liquide avant de l'introduire dans ledit mince canal.6. Method according to either of claims 1 to 5, characterized in that the temperature of the liquid metal is measured and, if necessary, adjusted before introducing it into said thin channel.
7. Procédé suivant l'une ou l'autre des revendications 1 à 6, caractérisé en ce que l'on mesure et, le cas échéant, on ajuste la composition chimique du métal liquide avant de l'introduire dans ledit mince canal.7. Method according to either of claims 1 to 6, characterized in that the chemical composition of the liquid metal is measured and, if necessary, adjusted before introducing it into said thin channel.
8. Procédé suivant les revendications 6 et 7, caractérisé en ce qu'on opère en continu soit dans les opérations sur la température du métal liquide, soit celles sur la composition chimique du métal liquide, soit celles visant les deux. 8. Method according to claims 6 and 7, characterized in that it operates continuously either in the operations on the temperature of the liquid metal, or those on the chemical composition of the liquid metal, or those targeting both.
9. Procédé suivant les revendications 2 à 8, caractérisé en ce qu'on réalise l'alimentation dudit canal mince en circuit fermé.9. Method according to claims 2 to 8, characterized in that the supply of said thin channel in closed circuit.
10. Procédé suivant l'une ou l'autre des revendications 1 à 9, caractérisé en ce que l'on règle de façon indépendante l'une de l'autre la pression sur les deux faces de la bande à l'intérieur dudit mince canal.10. Method according to either of claims 1 to 9, characterized in that the pressure on the two faces of the strip inside said thin is adjusted independently of one another. channel.
11. Procédé suivant l'une ou l'autre des revendications 1 à 10, caractérisé en ce que la vitesse de circulation du courant de métal liquide par rapport à la bande, à l'intérieur dudit mince canal, est comprise entre 0,5 m/s et 1 m/s.11. Method according to either of claims 1 to 10, characterized in that the speed of circulation of the stream of liquid metal with respect to the strip, inside said thin channel, is between 0.5 m / s and 1 m / s.
12. Dispositif pour le revêtement d'une bande métallique au trempé suivant le procédé de l'une ou l'autre des revendications 1 à 8, caractérisé en ce qu'il comprend un mince canal (10; 12; 15; 33), des moyens pour faire circuler la bande à revêtir à travers ledit mince canal, ainsi que des moyens (11 ; 18; 22; 28; 31) pour alimenter ledit mince canal en métal liquide et pour créer un mouvement de circulation du métal liquide par rapport à la bande à l'intérieur dudit mince canal.12. Device for coating a metallic strip by dipping according to the method of either of claims 1 to 8, characterized in that it comprises a thin channel (10; 12; 15; 33), means for circulating the strip to be coated through said thin channel, as well as means (11; 18; 22; 28; 31) for supplying said thin channel with liquid metal and for creating a movement of circulation of the liquid metal with respect to to the band inside said thin channel.
13. Dispositif suivant la revendication 12, caractérisé en ce que lesdits moyens d'alimentation comprennent au moins un réservoir séparé (30), d'une capacité plus grande que le mince canal, et en ce que ledit réservoir séparé est relié au mince canal par un circuit d'alimentation conduisant à des moyens (24; 26; 27) d'introduction du métal liquide dans ledit mince canal, de part et d'autre de la bande (1 ) qui y circule.13. Device according to claim 12, characterized in that said supply means comprise at least one separate tank (30), with a capacity greater than the thin channel, and in that said separate tank is connected to the thin channel by a supply circuit leading to means (24; 26; 27) for introducing the liquid metal into said thin channel, on either side of the strip (1) which circulates there.
14. Dispositif suivant la revendication 13, caractérisé en ce que ledit réservoir séparé (30) est surélevé par rapport au mince canal, afin de créer une circulation du métal liquide par gravité d'une part entre le réservoir séparé et le mince canal, et d'autre part à l'intérieur du mince canal.14. Device according to claim 13, characterized in that said separate tank (30) is raised relative to the thin channel, in order to create a circulation of the liquid metal by gravity on the one hand between the separated tank and the thin channel, and on the other hand inside the thin channel.
15. Dispositif suivant l'une ou l'autre des revendications 12 à 14, caractérisé en ce qu'il comporte des moyens (29) pour filtrer le métal liquide avant son introduction dans ledit mince canal. 15. Device according to either of claims 12 to 14, characterized in that it comprises means (29) for filtering the liquid metal before its introduction into said thin channel.
16. Dispositif suivant l'une ou l'autre des revendications 12 à 15, caractérisé en ce qu'il comporte des moyens (29) pour mesurer et, le cas échéant, ajuster la température du métal liquide avant son introduction dans ledit mince canal.16. Device according to either of claims 12 to 15, characterized in that it comprises means (29) for measuring and, if necessary, adjusting the temperature of the liquid metal before its introduction into said thin channel .
5 17. Dispositif suivant l'une ou l'autre des revendications 12 à 16, caractérisé en ce qu'il comporte des moyens (29) pour mesurer et, le cas échéant, ajuster la composition chimique du métal liquide avant son introduction dans ledit mince canal.5 17. Device according to either of claims 12 to 16, characterized in that it comprises means (29) for measuring and, if necessary, adjusting the chemical composition of the liquid metal before its introduction into said thin channel.
10 18. Dispositif suivant l'une ou l'autre des revendications 12 à 17, caractérisé en ce que le mince 7canal est intégré dans un circuit fermé, comportant également au moins un réservoir d'alimentation, éventuellement surélevé, un circuit d'alimentation du mince canal, un circuit de récupération du métal liquide en excès, des moyens de traitement du métal liquide, et éventuellement au moins18. Device according to either of claims 12 to 17, characterized in that the thin 7 channel is integrated in a closed circuit, also comprising at least one supply tank, optionally raised, a supply circuit. the thin channel, a circuit for recovering excess liquid metal, means for treating the liquid metal, and optionally at least
15 une pompe de circulation du métal liquide. 15 a liquid metal circulation pump.
PCT/BE2002/000047 2001-04-03 2002-03-28 Method and device for dip coating a metal strip WO2002083969A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP02719575A EP1386016B1 (en) 2001-04-03 2002-03-28 Method and device for dip coating a metal strip
DE60204453T DE60204453T2 (en) 2001-04-03 2002-03-28 METHOD AND DEVICE FOR THE MELT EXTRACTION TEMPERATURE OF A METALLIC TAPE
AT02719575T ATE296905T1 (en) 2001-04-03 2002-03-28 METHOD AND DEVICE FOR FELTS-DIP COATING A METAL STRIP

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BE2001/0216 2001-04-03
BE2001/0216A BE1014093A3 (en) 2001-04-03 2001-04-03 PROCESS AND DISPSOTIVE FOR COATING A METAL STRIP WITH HARDENING.

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WO2002083969A1 true WO2002083969A1 (en) 2002-10-24

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AT (1) ATE296905T1 (en)
BE (1) BE1014093A3 (en)
DE (1) DE60204453T2 (en)
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WO (1) WO2002083969A1 (en)

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GB637537A (en) * 1941-01-29 1950-05-24 Gen Motors Corp Apparatus for coating or impregnating metal strip stock with metal
DE1771662A1 (en) * 1968-06-24 1972-01-13 Jenoptik Jena Gmbh Device for tinning copper wires
DE2105661A1 (en) * 1971-02-05 1972-08-10 Mandl J Hot dip metal coating - with melt flow along workpiece surface
GB1532554A (en) * 1976-02-10 1978-11-15 Raymond A Metallic coating of metal tubes and similar work pieces
JPS61199064A (en) * 1985-02-27 1986-09-03 Hitachi Cable Ltd Hot dip coating apparatus
JPH028356A (en) * 1988-06-25 1990-01-11 Kawasaki Steel Corp Method and apparatus for metal hot dipping
JPH02141564A (en) * 1988-11-21 1990-05-30 Furukawa Electric Co Ltd:The Production of hot dip sn coated wire
JPH08337858A (en) * 1995-06-09 1996-12-24 Kawasaki Steel Corp Method for hot dip metal plating and equipment therefor

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Publication number Priority date Publication date Assignee Title
GB637537A (en) * 1941-01-29 1950-05-24 Gen Motors Corp Apparatus for coating or impregnating metal strip stock with metal
DE1771662A1 (en) * 1968-06-24 1972-01-13 Jenoptik Jena Gmbh Device for tinning copper wires
DE2105661A1 (en) * 1971-02-05 1972-08-10 Mandl J Hot dip metal coating - with melt flow along workpiece surface
GB1532554A (en) * 1976-02-10 1978-11-15 Raymond A Metallic coating of metal tubes and similar work pieces
JPS61199064A (en) * 1985-02-27 1986-09-03 Hitachi Cable Ltd Hot dip coating apparatus
JPH028356A (en) * 1988-06-25 1990-01-11 Kawasaki Steel Corp Method and apparatus for metal hot dipping
JPH02141564A (en) * 1988-11-21 1990-05-30 Furukawa Electric Co Ltd:The Production of hot dip sn coated wire
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ES2242008T3 (en) 2005-11-01
DE60204453D1 (en) 2005-07-07
DE60204453T2 (en) 2006-05-18
EP1386016B1 (en) 2005-06-01
BE1014093A3 (en) 2003-04-01
EP1386016A1 (en) 2004-02-04
ATE296905T1 (en) 2005-06-15

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