EP2173918B1 - Equipment for coating a metal strip - Google Patents

Abstract

The invention relates to an equipment for coating a strip product (M) by passage in a liquid metal bath (31), that comprises means for controlling the running of the strip (M) between the metal bath (31) and a final quenching bath (35) along a continuous running line defined by a succession of deviation cylinders and including at least three portions, respectively a first portion (T1) at inlet of the metal bath, a second portion at the outlet of the bath (31) in an ascending direction and at least a third descending portion (T3) giving into the final quenching bath (35). According to the invention, the final quenching bath (35) is located above the metal bath (31) so that the entire running line of the strip (M) between the metal bath (31) and the final quenching bath (35) occupies an area over the ground of the same magnitude as that of the metal bath (31).

Description

The invention relates to an installation for coating a strip product, in particular, a metal strip, by galvanizing.

In order to improve the corrosion resistance of the metal sheets used, in particular, in certain applications such as the building, automobile or household appliances, it is common to deposit on the surface of these sheets, a layer of zinc coating or a zinc-based alloy. The sheet being made, normally, by rolling a metal strip, it can be subjected to a galvanizing treatment performed during the running of the strip in a continuous galvanizing line.

• une section d'entrée 1 avec une ou deux dérouleuses de bande 10, 10', une cisaille 11, par exemple à guillotine, une soudeuse de raboutage 12 permettant de raccorder la queue d'une première bande issue d'une des dérouleuses 10 à la tête de la bande suivante issue de l'autre dérouleuse 10', de façon à assurer un fonctionnement continu de la ligne, et un accumulateur de bande 13 qui permet de mettre en réserve une certaine longueur de bande de façon à la restituer à la ligne, lorsque le déroulement est stoppé en amont de l'accumulateur, pour réaliser le raboutage dans la soudeuse 12 ;
• une section 14 de dégraissage des bandes laminées à froid ou de décapage acide des bandes laminées à chaud ;
• un four de recuit 2 comprenant successivement une section de chauffage 21, une section 22 de maintien à la température de recuit, une section de refroidissement rapide 23 et une section 24 de maintien de la bande à une température contrôlée, éventuellement pour un traitement de surveillissement (overaging) et/ou pour porter la bande à la température souhaitable avant son entrée dans le bain de zinc en fusion ;
• une section 3 de galvanisation proprement dite, comprenant un bain de zinc 31 dans lequel est immergée la bande à la sortie de la section de maintien en température 24, un dispositif 32 d'essorage du zinc liquide permettant de contrôler l'épaisseur de la couche de revêtement déposée sur les deux faces de la bande, éventuellement un four à induction 33 dont le rôle sera indiqué plus loin, un dispositif de refroidissement 34 et un bac de trempe 35 pour le refroidissement final de la bande ;
• une section de sortie avec, par exemple, un laminoir skin-pass 15, une section de passivation 16, un accumulateur de sortie 17, une cisaille 18 et une ou deux enrouleuses 19.

For example, the figure 1 shows schematically the usual constitution of a continuous line of annealing and galvanization comprising successively, in the direction of travel of the strip, that is to say from left to right in the figure:

• an inlet section 1 with one or two belt unrollers 10, 10 ', a shear 11, for example a guillotine, a splicing welder 12 for connecting the tail of a first band from one of the unwinders 10 to the head of the next strip coming from the other unwinder 10 ', so as to ensure a continuous operation of the line, and a tape accumulator 13 which allows to reserve a certain length of tape so as to restore it to the line, when the flow is stopped upstream of the accumulator, to achieve the splicing in the welder 12;
• a section 14 for degreasing the cold-rolled strips or acid pickling of the hot-rolled strips;
• an annealing furnace 2 successively comprising a heating section 21, a retention section 22 at the annealing temperature, a rapid cooling section 23 and a section 24 for holding the strip at a controlled temperature, possibly for a monitoring treatment (overaging) and / or to bring the band to the desired temperature before entering the molten zinc bath;
• a galvanizing section 3 itself, comprising a zinc bath 31 in which is immersed the strip at the outlet of the temperature holding section 24, a device 32 for spinning the liquid zinc to control the thickness of the layer coated on both sides of the strip, optionally an induction furnace 33 whose role will be indicated later, a cooling device 34 and a quenching tank 35 for the final cooling of the strip;
• an outlet section with, for example, a skin-pass mill 15, a passivation section 16, an outlet accumulator 17, a shear 18 and one or two winders 19.

Such an arrangement is quite conventional but, of course, may be subject to variants, depending on the processing carried out upstream or downstream of the galvanizing section itself.

The figure 2 shows schematically, on a larger scale, the constitution of such a galvanizing section comprising means for controlling the continuous movement of the band M between a liquid zinc bath 31 and a final cooling bath or "tank of quenching "along a path defined by a plurality of baffle rollers and having, generally speaking, a first inlet portion T1 of the web M in the metal bath 31, in a downward direction, to a first roll deflector 41 immersed in the bath 31, a second portion T2 of the bath outlet 31, in an upward direction, to a pair of deflector rollers 42, 42 'placed at a higher level above the bath 31 and at least one third part T3 extending between an upper baffle roll 42 'and a lower baffle roll 43 immersed in the final cooling bath 35 and along which are placed cooling means by blowing a gaseous fluid, the band M then being evacuated, passing on a deflector roll 44, towards the rest of the installation, for example a skin-pass rolling mill.

Leaving the bath 31, the strip is covered on both sides with a zinc layer driven upwardly with the strip. The covered strip then passes into a wiper device 32 of known type which makes it possible to control the thicknesses of these two coating layers.

For example, French Patent No. 2,726,288 from the same company describes such an air knife dewatering device.

In known manner, the installation may comprise, on the upstream part T2 of the path of the strip, at the outlet of the metal bath 31, a heating furnace 33 making it possible to perform a so-called alloy heat treatment which ensures the diffusion of iron from the band, to the zinc coating, to create a real iron / zinc alloy. Such a Alliation is interesting, in particular, for the automotive industry because it makes it possible to improve certain surface qualities of the coated sheets such as the adhesion of the paints or the drawing capacity.

The strip must, however, be cooled before being immersed in the quenching tank 35. The installation therefore comprises, above the alloying oven 33 and / or on the downward path T3 of the strip, a cooling device 34 comprising for example, variable speed motor-blowers blowing air on the belt and whose flow rate can be regulated by measuring the temperature.

The surface quality requirements of metal sheets are becoming more severe. In particular, for automotive body panels, a visible part finish quality is required which imposes a very high level of surface quality of the strips after galvanizing.

However, metallurgical reactions occur in the zinc bath which degrade the surface of the roller 41 immersed in the zinc bath 31 quite rapidly and this results in defects which can affect the quality of the side A of the strip which is supported on the roller 41 for the change of direction, that is to say the upper face of the strip in the first portion T1 entering the bath 31.

That is why, usually, it is the second face A 'of the band M, turned outwards when passing over the submerged roll 41, which is reserved for the visible parts of the finished products, for example a bodywork automotive and the user is told which of the two faces called "exposed face" has the best surface quality.

However, in a conventional installation of the type shown on the figure 2 , the path of the strip at the outlet of the zinc bath 31 imposes several contacts of this exposed face A 'with baffle rollers, before sufficient cooling to prevent any degradation of the surface of the coating.

For example, in the conventional layout shown on the figure 2 it is the upper face A of the band M which passes over the submerged roll 41 and may therefore be degraded by the defects of this roll. But in the upper part of the upward path T2, it is the second face A 'which passes over the upper deflector rollers 42, 42' before leaving the installation following the downward path T3 to the quenching bath 35 placed next to the metal bath 31. This contact of the exposed face A 'with the deflector rollers 42, 42' constitutes a risk of degradation of the surface of the coating, in particular, if an alloying treatment is carried out by passing through a oven 33 on the upward path T2 at the exit of the bath 31.

In practice it is therefore preferable to perform a first cooling of the strip before it passes over the upper deflector rollers 42, 42 '. For this purpose, means 34 'of cooling by air blowing can also be placed on the upward path T2 above the alloying furnace 33. This blowing cooling must, itself, be carried out carefully so as to not to degrade the quality of the zinc deposit.

However, it is necessary to have the necessary space to place the numerous apparatuses, ventilators, supply and exhaust ducts, mechanical and electrical organs, etc.

In practice, two zones, respectively heating 33 and cooling 34 'are superimposed on the upward path T2, before the change of direction of the band. Such an installation must therefore be placed in a frame that can have a very high height, for example several tens of meters.

Furthermore, the metal strips themselves have a large enough width, for example up to two meters and the control of their scrolling at high speed requires the use of complex and bulky equipment.

The building in which is placed such a galvanizing plant thus has a significant footprint.

Now, as schematically shows figure 1 the galvanizing plant is only part of the production line, which usually includes other sections which are also very cumbersome, in particular the upstream and downstream accumulators 13, the annealing furnace 2 which comprises several sections on the one hand, to anneal and on the other hand to bring the strip to the desired temperature for galvanizing, the skin-pass 15, the degreasing section 14 and the section of passivation 16, as well as unwinding 10 and winding devices 19.

The whole of such a facility is therefore an extremely important set and it is difficult, after construction, to make some sections the necessary changes while keeping the neighboring sections.

It is therefore advantageous to reduce as much as possible the size of the installation, while providing opportunities for its evolution, for example by having the possibility of adding, if necessary, a furnace of alliation, and / or cooling means.

The object of the invention is to solve such problems thanks to a new arrangement of the installation making it possible to reduce its footprint. On the other hand, the invention also makes it possible to delay the moment when one of the so-called "exposed face of the strip" comes into contact with a deflector roll, in order to ensure excellent quality of the coating on this exposed face. .

The invention therefore applies, in a general manner, to a coating installation of a strip product by passing it into a bath of liquid metal, comprising at least three parts, respectively a first part of entering the metal bath, passing on a first baffle roll placed at a lower level, a second brewing portion of the bath in an upward direction, between said first lower roll and a second baffle roll placed at a higher level, above metal bath, at least a third cooling portion extending between said second upper roll and a final coolant bath, and a fourth output portion of said cooling bath.

According to the invention, the final cooling liquid bath is placed at a level higher than that of the metal bath and is shifted with respect thereto towards the inlet side, so that the fourth bath outlet portion cooling passes over the metal bath, and that the footprint of the entire coating installation does not significantly exceed that of the metal bath.

Particularly advantageously, the strip is supported, by a first face, on the first baffle roll, coming from a first inlet side in the metal bath and is supported by the same first face on the second baffle roll placed at higher level, so that the third cooling part is placed towards the same first side of the metal bath with respect to the second outlet portion of the bath.

According to another advantageous characteristic of the invention, the installation comprises a quality control station of the coating, placed on the second side of the metal bath, opposite to the first input side of the strip and in front of which passes, in the first ascending portion of the metal bath outlet, the second face of the strip opposite the first bearing face on the first and second deflection rolls, and the band passes over a baffle roll immersed in the final cooling bath taking resting on said roll immersed by its second face, then passes over the whole of the installation, in the fourth part of the outlet of the cooling bath, taking support by the same second face on two upper rollers spread apart and back down by a last descending part of output of the installation by passing in front of the station of verification the same second face of the band, so that the state of the coating on this second face can be verified, firstly at the outlet of the metal bath and, secondly, at the outlet of the installation, after final cooling.

In a preferred embodiment, the installation comprises at least one cooling means, by gas blowing, on both sides of the strip, arranged along the path thereof, or upstream of the second baffle roll in the second outlet portion of the metal bath, or downstream of said second deflector roll, at the beginning of the third cooling part.

The invention also makes it possible to place a means for heating the strip in the second outlet portion of the metal bath, immediately above it, in order to perform an alloying treatment.

In a first embodiment, the third cooling portion of the strip comprises a single strand descending from the second baffle roll to the coolant bath placed above the metal bath.

In another embodiment, the third cooling portion comprises, from the second baffle roll placed at a higher level, a first descending strand to a third baffle roll placed below the second roll and above the bath metallic, a second ascending strand between said third roll and a fourth baffle roll placed substantially at the second roll, and a third descending strand between said fourth roll and the coolant bath, cooling means being placed at least on the one of the two ascending and descending strands, upstream of the third deflector roll so as to allow a support of the band on said third deflector roll, by its second face opposite to the first bearing face on the first and the second deflection roll, without deterioration of the coating deposited on this second face.

Advantageously, cooling means are arranged, respectively, on the upward path between the first and second baffle rolls and on the descending path between the second upper roll and the third lower roll, said cooling means being offset in height and arranged in a staggered arrangement.

The invention is particularly applicable to a coating installation arranged downstream, in the direction of travel, of an annealing line placed inside a closed enclosure for maintaining a non-oxidizing atmosphere, with scrolling the strip between two sets of deflector rollers spaced apart in height, said enclosure being closed at an outlet end by a vertical wall having a height corresponding to the spacing between the deflection rollers and provided at its lower part with a closed chute outlet strip to the metal bath gulvanization. In this case, the entire coating installation can be arranged in a constricted space extending vertically along the vertical closing wall of the enclosure and horizontally over a distance corresponding to the footprint of the bath metal with the exit chute of the band.

But the invention can also be applied, advantageously, to a coating installation disposed downstream from an annealing line placed inside a closed enclosure extending horizontally between an inlet end and an end of outlet equipped with a connecting chute opening into the galvanizing metal bath.

In this case, the final cooling bath can be placed above the annealing enclosure, some distance upstream of the outlet end, and the third part of the path of the strip, along which cooling means are placed horizontally above the annealing chamber and returning upstream to the final cooling bath from which the fourth bath outlet portion extends horizontally downstream. passing over said cooling means.

• La figure 1 est un schéma général de l'ensemble d'une ligne de recuit et de galvanisation de type connu ;
• La figure 2 montre schématiquement la disposition classique d'une installation de galvanisation ;
• La figure 3 est un schéma d'une installation de galvanisation selon l'invention ;
• La figure 4 montre une variante avec disposition en quinconce des moyens de refroidissement ;
• La figure 5 montre schématiquement une autre disposition d'une installation de galvanisation selon l'invention.

The invention also covers other advantageous features which will appear in the following description of certain particular embodiments, given by way of example and shown schematically in the accompanying drawings.

• The figure 1 is a general diagram of the assembly of an annealing and galvanizing line of known type;
• The figure 2 schematically shows the conventional layout of a galvanizing plant;
• The figure 3 is a diagram of a galvanizing plant according to the invention;
• The figure 4 shows a variant with staggered arrangement of the cooling means;
• The figure 5 schematically shows another arrangement of a galvanizing installation according to the invention.

The figure 3 shows schematically a preferred embodiment of a galvanizing plant according to the invention as indicated above, the strip M to be treated was first brought to a temperature desirable for galvanizing, preferably in an annealing furnace terminating in a temperature-controlled holding section 24 and having, at its outlet, a baffle roll 40 which directs the strip to the galvanizing metal bath 31 formed in a tank 30 and into which is immersed a first baffle roll 41. The band M therefore follows a downward path T1 between the output roll 40 and the submerged roll 41 on which it bears by its upper face A.

The strip M then comes out of the bath 31 along an upward vertical path T2 to an upper roll 42 past a wiper device 32 for controlling the thickness of the coating.

All these provisions are classic and correspond to those described above with reference to the figure 2 .

In the invention, however, the band M is supported on the upper roll 42 by the same side A passing on the immersed roll 41.

For this, instead of being diverted to the outside of the tray 30, the band M returns to the side by which it had entered the tray, that is to say the left side on the figure 3 .

In this way, it is only at the lower end of the downward path T3 that the second face A 'of the strip M, turned downwards in the galvanizing bath 31, makes contact with a deflector roll 43. This face A 'can therefore cool successively, along the upward path T2 and the downward path T3, to a temperature enabling it to rest on the lower roller 43 without risk of degradation of the coating.

If it is desired to carry out an alloying treatment, an oven 33 is placed above the dewatering device 32 and is followed by cooling cells 6 which can be placed, not only on the upward path T2, upstream of the upper roll 42, but also on the downward path T3, above the lower roll 43. It is thus possible to achieve sufficient cooling of the band before the contact of its side A 'with the lower roll 43.

As a result of this arrangement of the path of the strip, the tank 5 containing the quenching bath 35, in which the final cooling of the band M is achieved, is placed above the tank 30 containing the galvanizing bath. 31 and offset from it, to the inlet side of the galvanizing plant whose footprint is thus reduced compared to the conventional layout of the figure 2 .

As indicated above and in the way shown on the figure 1 the galvanizing plant 3 is preceded, usually, by an annealing line 2 terminating in a section 24 in which the strip is brought to the desired temperature for galvanizing. In addition, to avoid the risk of oxidation of the band, the assembly is placed under a protective atmosphere in a closed enclosure 8 extended at its outlet end of the band M, by a chute 81 immersed in the metal bath 31 to maintain the seal.

Generally, to reduce the length of the line, the band passes on two series of deflector rollers spaced in height and the enclosure 8 is therefore closed, at its outlet end, by a vertical wall 80 of corresponding height.

According to the invention, the quench tank 35 is placed above the metal bath 31 and the outlet trough 81 and the assembly of the coating installation can therefore be arranged in a constricted space extending vertically in height, along the closing wall 80 of the annealing enclosure 8 and horizontally over a distance not exceeding the footprint of the metal bath 31 with the connecting trough 81.

Thus, the overall size, in length, of the treatment line can be decreased compared to the conventional arrangement of Figures 1 and 2 .

Admittedly, such an arrangement requires the construction, above the metal bath 31, of a floor to support the quench tank 5, but this increase in height of the installation does not constitute a real disadvantage, particularly for the transformation of an existing installation. On the contrary, the transfer of the quench bath above the metal bath makes it possible to release, next to it, a space which, as will be seen below, can be used, for example, to place a station 7 of check the quality of the tape.

Similarly, the upper roller 42 may be placed at a height sufficient to have the cooling means 6 extending over the length necessary to obtain sufficient cooling of the strip before the contact of its side A 'with the lower roller 43. In this case, this roll 43 can be immersed in the quench bath 35.

However, to achieve sufficient cooling of the strip before quenching, without unduly increasing the height of the installation, after the downward path T3 and its passage on the lower roller 43, the band M can go up an ascending path T31 until to a second upper roll 44, then descend, in a descending path T32, to a deflector roll 45 immersed in the final cooling bath 35.

At the exit of this quenching bath 35, the band M follows a rising path T4 to a pair of upper deflector rollers 46, 46 'spaced apart from each other, so as to pass the band over of the whole of the galvanizing section, then down, by a downward path T5, up to a lower roll 47 to be directed towards the rest of the installation, for example a skin-pass 15 mill.

As indicated above, on the side of the galvanizing tank opposite the entry side of the strip, that is to say to the right of the tray 30 on the figure 3 can be placed a verification station 7, for example a control cabin for an operator.

This station 7 can thus be placed between the first ascending section T2 of the outlet of the metal bath 31 and the last descending section T5 of the outlet of the installation, deflector rollers 48 allowing, possibly, to provide the necessary location for the station 7 .

The operator placed in the control cabin thus passes, in the ascending section T2, the outer face A 'of the strip which, because of the arrangement according to the invention, comes into contact with the roll 43 after cooling along the ascending section T2 and the descending section T3. This external face A 'therefore undergoes no degradation and thus constitutes the so-called "exposed" face which will subsequently be the visible face of the sheet for example for a car body.

Thanks to the particular path of the band, shown schematically on the figure 3 it is the same exposed face A 'which passes in front of the operator in the last descending section T5, on the other side of the cabin 7.

Thus, the operator sees successively before him twice the same face. Knowing the total length of the path and the running speed of the belt which can be measured at any moment, the operator can therefore locate on the exposed face A 'of the belt, immediately above the wiper device 32, a doubtful zone and, after having allowed the time necessary for scrolling, to identify the passage of the same zone on the descending path T5 in order to check the possible presence of a defect after the final cooling and hardening of the coating.

The arrangement according to the invention thus makes it possible to guarantee the best possible integrity of the exposed face of the coated strip.

Of course, the invention is not limited to the details of the embodiment which has just been described but covers all the variants using equivalent means and remaining in the same protective frame.

For example, as we have seen, the arrangement according to the invention makes it possible to distribute cooling means 61, 62 not only along the upward path T2 but also along the downward path T3, so as to provide sufficient cooling coating to the passage of the exposed face A 'on the lower roll 43. As shown in FIG. figure 4 cooling cells 61, 62 may advantageously be staggered on the ascending and descending strands. In this way, the two strands T2, T3 can be separated by a single upper roller 42, which further reduces the footprint of the assembly. In addition, such an arrangement makes it possible to distribute the cells 6 over a greater length of strip and thus to have a less violent blowing, which reduces the risk of producing a vibration of the strip which may have an impact on the quality of the coating. , in particular, the regulation of its thickness.

Moreover, the invention is not limited to the case where, to reduce the length of the annealing line, the strip follows a zig-zag path by passing over two sets of rollers spaced apart in height. Indeed, the invention can also be applied to the case of a continuous annealing furnace in which the band scrolls horizontally over a large length.

In this case, shown schematically on the figure 5 the quenching bath 35, which, according to the invention, is offset backward from the galvanizing bath 31, can be placed above the outlet end of the annealing enclosure 8 'whose height is, then , relatively reduced. The third part T3 of the path of the strip then extends horizontally and returns upstream to the quench tank 35 which is shifted back a sufficient distance to dispose the necessary cooling means 6 along said strand T3 . The fourth portion T4 of quenching bath 35 then returns horizontally downstream passing above said cooling means 6.

As before, the footprint of the coating plant 3 does not substantially exceed that of the galvanizing bath 31.

Furthermore, the invention has been described in the usual case of a coating by passing on a roll immersed in a bath of liquid metal but it could also be applied to other coating devices, for example of the type in which the metal bath of galvanization is maintained by magnetic levitation by means of induction coils arranged along the upward path of the strip after passing on the lower roller 41 which, in this case, is not immersed.

Claims (10)

1. Installation for coating a strip product (M) by passage through a molten metal bath (31), that comprises means for controlling the movement of the strip (M) between an input side of the liquid metal bath (31) and an output side of the installation, along a continuous moving line defined by a plurality of deflection rolls and comprising at least four parts, respectively a first input part (T1) in the metal bath, passing via a first deflector roll (41) placed at a lower level, a second output part (T2) of the bath (31) following an ascending direction, between said first lower roll (41) and a second deflector roll (42) placed at a higher level, above the metal bath (31), at least one third quenching part (T3) extending between said upper roll (42) and a final quenching bath (35) along which are arranged means (34) to quench the coating using a gaseous fluid, and a fourth output part (T4) of the final quenching bath (35), characterised in that the final quenching bath (35) is placed higher than the metal bath (31) and nearer than it to the input side, such that the footprint of the entire coating installation is not significantly larger than that of the metal bath (31) over which the strip (M) passes in the fourth part (T4) of its route between the final quenching bath (35) and the output of the installation.
2. Coating installation according to claim 1, characterised in that the strip (M) is supported by a first face (A) on the first deflector roll (41), coming from a first input side in the metal bath (31) and is supported by the same first face (A) on the second deflector roll (42) placed at a higher level, such that the third quenching part (T3) is placed towards the first side of the metal bath (31) in relation to the second output part (T2) of the bath.
3. Coating installation according to claim 2, characterised in that it has a coating quality checking station (7), placed on the second side of the metal bath (31), opposite the first input side of the strip (M) and before which passes, in the first ascending output part (T2) of the metal bath, the second face (A') of the strip opposite the first support face (A) on the first and second deflector rolls (41, 42), and that the strip passes over a deflector roll (45) immersed in the final quenching bath (35) supported on said immersed roll (45) by its second face (A'), then, in the fourth output part (T4) of the quenching bath (35), passes above the entire installation supported by the same second face (A') on two separate upper rolls (46, 46') and returns via a final descending output part of the installation (T5) making the same second face (A') of the strip (M) pass before the verification station (7), to check the condition of the coating on this second face, firstly at the output of the metal bath (31) and, secondly, at the output of the installation, after final quenching.
4. Coating installation according to one of the preceding claims, characterised in that it includes at least one quenching means (6) by blowing gas on both faces (A, A') of the strip (M), arranged along its route, either upstream of the second deflector roll (42) in the second output part of the metal bath (T2), or downstream of said second deflector roll (42), at the start of the third quenching part (T3).
5. Coating installation according to one of the preceding claims, characterised in that it includes a heating means (32) for the strip (M) arranged in the second output part (T2) of the metal bath (31), immediately above it.
6. Coating installation according to one of the preceding claims, characterised in that the third quenching part (T3) includes a single section descending from the second deflector roll (42) to the liquid quenching bath (35).
7. Coating installation according to one of claims 1 to 5, characterised in that the third quenching part (T3) includes, from the second deflector roll (42) placed at a higher level, a first section descending (T3) to a third deflector roll (43) placed below the second roll (42) and above the metal bath (31), a second section ascending (T31) between said third roll (43), and a fourth deflector roll (44) placed approximately at the level of the second roll (42), and a third section descending (T32) between said fourth roll (44) and the liquid quenching bath (35), quenching means (6) being placed, at least on one of the two sections, ascending T2 and descending (T3), upstream of the third deflector roll (43) such as to enable the strip to be supported on said third deflector roll by its second face (A') opposite the first support face (A) on the first and second deflector rolls (41, 42), without damaging the coating placed on this second face (A').
8. Coating installation according to one of the preceding claims, characterised in that the quenching means (61, 62) are arranged respectively, on the ascending path (T2) between the first (41) and second (42) deflector rolls as well as on the descending path (T3) between the second upper roll (42) and the third lower roll (43), said quenching means (6) being offset upwards and arranged in staggered rows.
9. Coating installation according to one of the preceding claims, characterised in that it is placed downstream, in the direction of movement, of an annealing line placed inside an enclosure sealed to retain a non-oxidising atmosphere, with movement of the strip between two series of deflector rolls offset upwards, said enclosure being closed, at an output end, by a vertical wall as high as the gap between the deflector rolls and having, in its lower part, a closed strip output chute leading to the metal galvanising bath, and that the entire coating installation is arranged in a narrow space extending vertically along the vertical wall closing the enclosure and horizontally for a distance equal to the footprint of the metal bath with the strip output chute.
10. Coating installation according to one of claims 1 to 5, characterised in that it is placed downstream, in the direction of movement of an annealing line placed inside an enclosure sealed to retain a non-oxidising atmosphere, said enclosure extending horizontally between an input end and an output end fitted with a linking chute leading to the metal galvanising bath (31), that the final quenching bath (35) is placed above the annealing enclosure, at a certain distance upstream of the output end, and that the third part (T3) of the strip route, along which are placed quenching means (6) extends horizontally above the annealing enclosure returning upstream to the final quenching bath (35) from which the fourth output part (T4) of the bath extends horizontally downstream passing above said quenching means (6).

Images