EP1655383B1 - Process and device for limiting the vibrations of aluminium or steel sheets during gas cooling - Google Patents

Description

The present invention relates to the treatment lines of steel or aluminum strips using at least one gas or air jet cooling chamber, or a gas or air jet cooling section, such as the heat treatment lines, in particular continuous annealing lines, or such as coating lines, in particular metal or non-metallic coating lines.

More specifically, the subject of the invention is a method for cooling a strip of steel or aluminum moving in a treatment or coating line, in which gas or air jets are sprayed towards each of the moving web faces according to the preamble of claim 1.

This process aims to increase the cooling of the band while avoiding vibration phenomena on the band.

BACKGROUND OF THE INVENTION

We will present, with reference to Figures 1 to 8 , a general description of the processing lines of steel or aluminum strips.

A vertical cooling chamber of a steel or aluminum strip processing line produced according to the state of the art is constructed according to the principle shown in FIG. figure 1 , on which there is a cooling chamber 4 of a treatment furnace, in which circulates a steel or aluminum strip 1, which is subjected to the action of cooling elements 2 when it passes over upper idler rollers 3 and lower idler rollers 3 '. Strip 1 is cooled in chamber 4 mainly by the cooling elements 2 consisting of gas blowing assemblies at a temperature below the strip temperature.

During its passage in the cooling chamber 4, the band 1 is cooled on both sides by the cooling elements 2 located on either side of the line of the pass, and in case of cooling on several lines of pass, said band changes line of pass to each return roller 3 or 3 '. The cooling curve of the strip in the chamber is controlled by the indexing of the different cooling elements 2 or groups of cooling elements operating identically.

A vertical cooling section of a steel or aluminum strip processing line produced according to the state of the art is constructed according to the principle shown in FIG. figure 2 , on which is distinguished a vertical cooling section 10, in which circulates a strip 11 which is subjected to the action of cooling elements 12. The strip 11 is cooled in the section mainly by the cooling elements 12 consisting of air blowing assemblies at a temperature below the strip temperature. The theoretical line of the band 11 is determined by the upper idler roll 13 and the lower idler roll 13 '.

During its passage in the cooling section 10, the strip 11 is cooled on both sides by the cooling elements 12 located on either side of the line of passage. The cooling curve of the strip in the section is controlled by the indexing of the different cooling elements 12 or groups of cooling elements operating identically.

PRODUCTIVITY OF THE LINE AND QUALITY OF THE FINAL PRODUCT

The productivity of the cooling chamber or section is determined by the ability to provide cooling heat transfer to reach strip temperatures at the outlet of the cooling chamber or section and the cooling slopes (expressed in ° C / second) that determine the metallurgical quality of the final product. This heat transfer is dependent on the blowing distance between the strip and the cooling system, the geometry of the blowing, and the blowing speed. The heat transfer will also be more effective if the blowing distance is small and / or if the blowing speed is important.

Increasing the blowing speed and decreasing the distance between the strip and the blowing system generate, from a certain limit, vibrations and / or oscillations of the strip which can cause contact between the strip and the strip. the blowing system (or the protections of the blowing system), causing marks (scratches) incompatible with the desired surface quality, and even in extreme cases of tape breaks.

VIBRATIONS OF THE BAND

The increase in the performance of steel or aluminum treatment lines imposes greater cooling slopes on products that are becoming thinner and larger and wider.

For example, with regard to the annealing of the steel strips, it is not uncommon to specify in the cooling chamber of a continuous annealing furnace, the need for high cooling slopes (typically greater than 80 ° C. / second) for the so-called DQ (Drawing Quality), DDQ (Deep Drawing Quality) and HSS (High Strength Steel) steels. Cooling slopes are lower (typically 20 ° C / second) for steels of commercial quality called CQ (Commercial Quality). The document EP 0 803 583 A2 describes this need and the various applications.

It should be noted that the proportion of steels with a high drawing limit (for example of the DDQ type) or with a high elastic limit (for example of the HSS type) increases significantly.

Similarly, to gain weight, particularly in automotive applications, the average thickness of the steels decreases, while the average width of the strips to be treated increases with the optimization of the stamping means.

Finally, the capacities of the treatment lines, in particular the galvanizing or annealing lines, evolve towards greater capacities.

This combined evolution of the various parameters above causes the appearance of a new problem in the chambers or cooling sections, namely the vibrations of the band, this phenomenon being limited or even unknown in the equipment made according to the state prior art.

The phenomenon is of course very critical for the vertical chambers or sections as represented on the Figures 1 and 2 , but also exists with a horizontal pass line, although this phenomenon is then attenuated by the tape's own weight.

The cooling zone after coating of a hot-dip galvanizing line shown on the figure 3 is also very sensitive to this phenomenon. After coating by immersion of a steel strip 21 in a bath 22 of molten zinc alloy, the thickness of the coating is controlled by spinning in air or nitrogen of the liquid coating. This wringing is generally carried out by a pair of blowing nozzles 23, 23 '. The vertical cooling zone 24 which follows is intended to freeze coating and achieving a temperature at the turn-up baffle roll 25 which is process-compatible, in particular avoiding any trace on the coating.

The increase in the capacity of the lines makes the free strand height of the web 21 between the last roller 26 immersed in the molten zinc bath 22 and the tower top baffle roll 25 can exceed 50 meters on large lines. capacity.

A reduction of this height, which is desirable for technico-economic reasons, would impose higher exchange coefficients which again generate vibrations that are not compatible with the quality of the final product. These vibrations can generate marks by contact between the band and the external elements, but are also detrimental to the regularity of the zinc coating. Indeed, one of the essential parameters of the spin is the distance between the blast nozzle 23 or 23 'and the band 21, whose pass line is ideally fixed. The vibrations of the band 21 cause a line change in the longitudinal and / or transverse direction of the band, and therefore a non-uniform coating.

STATE OF THE ART

In order to limit the undesirable effects of the vibrations of the band, it has been attempted, in a prior art, to limit the vibrations by reducing the length of the casing (or zones), in order to install stabilizing rollers. However, this technique limits the length involved in the cooling and thus the cooling efficiency of the zone, and moreover this technique imposes a contact between the strip and the stabilizing rollers, which is incompatible with applications in cooling zones. after hot dip galvanizing because the coating is not yet completely frozen.

Aeraulic stabilization systems have also been proposed to replace the aforementioned stabilizing rollers. These systems are relatively efficient and can contribute to cooling, but they are not optimized to favor the exchange coefficient, and therefore to optimize cooling. In addition the energy consumption is relatively important.

Another attempt has been to increase web tension, but this solution is only feasible for thick webs, and for reduced web temperatures, since the thermomechanical stresses generated on high temperature thin webs may exceed the elastic limit of the bands and can cause permanent deformations, or even breakages of tape.

Another solution is to control the vibrations of the band by adjusting the blowing speed and / or the distance between the band and the blowing elements and / or the blowing flow rate in the event of occurrence of vibrations. This then leads to a limitation of the efficiency of the cooling, and therefore of the performance of the installation.

Another solution illustrated in figure 4 has been proposed to promote lateral flow of the blown gas. This solution consists in arranging blow tubes 31, 31 'on blow boxes 32, 32' located on either side of the band 33 which runs in a direction marked 100. The blowing tubes 31, 31 'allow and to guide the blowing jets 34, 34 'emitted in a direction which is perpendicular to the plane of the strip 33 scrolling. Although this system leads to an improvement over simple boxes the holes are not satisfactory, and the band flutations observed in such systems lead either to deterioration of the tubes when the band is thick, or to tape breaks when the band is thin. As the evacuation of the gas after blowing can only be done towards the edge of the boxes, either in the direction of travel of the strip, or laterally, it follows a large flow of gas flowing parallel to the strip, in a volume which is confined between the strip and the boxes towards the edges of said boxes. The presence of the tubes 31, 31 'de facto increases the available volume confined between the strip and the boxes, compared to simply perforated boxes.

The disturbances that have been observed with the layout of the figure 4 are illustrated in Figures 5 and 6 , which are end views along arrow A of the figure 4 .

On the figure 5 , the simulations of fluid mechanics on industrial geometries show that, when the band 33 is decentered towards one of the two boxes, here the box 32 ', the resultant of the pressures on the band exerts a force F tending to bring even more the strip of said box. The system is therefore unstable, and does not tend to stabilize the band in a pass line centered between the boxes. On the figure 6 , the simulations of fluid mechanics on industrial geometries show that, when the band 33 is inclined, the resultant of the pressures exerted on the band exerts a torque C, tending to further incline the band and thus to bring the edges of the band closer together caissons. The system is also unstable, and does not tend to stabilize the band in a pass line centered between the boxes. The results of Figures 5 and 6 have been demonstrated by simulation of fluid mechanics software, and by a calculation of the resultant pressures exerted on each side of the strip. The resultant pressure exerted on each side of the strip is the result of positive pressures in areas that are substantially right of the blowing tubes, and depressions at the parts that are not located in line with these tubes.

It has been proposed to channel the flow of the blown gas by providing caissons equipped with blowing tubes, with an inclination of the blowing tubes towards the edges of the strip, mainly to avoid the vibrations of the moving strip when it is cooled by blowing of gas jets as described in the document WO-A-01/09397 , but the modeling only leads to a slight improvement in the effects illustrated schematically in the Figures 5 and 6 .

The document US-A-6,054,095 teaches also to incline to the edges of the strip the blowing tubes equipping the boxes, but to have a better homogeneity of the temperature of the strip, so without worrying about the stability of the scrolling of said strip. Alternatively, the document US-A-4,673,447 discloses the use of blowholes with holes, said holes being formed in a thick plate to have an inclination of gas jets. It should be noted that the jets are inclined not towards the edges, but on the contrary towards a median plane, symmetrically with respect to said plane. It is therefore rather a simple stabilizing pad. The document US-A-3,116,788 proceeds from the same approach, with possible baffles arranged inside the blow boxes, thereby producing gas jets which are either directed perpendicularly to the plane of the moving strip, or directed towards the upstream of said band for countercurrent heat exchange.

The document EP-A-1,108,795 describes a variant of the preceding techniques, in which one also uses boxes with straight blow tubes (perpendicular to the plane of the strip). In fact, the aim is only to modify the intensity of cooling by varying the length of the tubes, which are chosen shorter at the edges of the strip.

The document EP-A-1,029,933 discloses another variant with bladed nozzle boxes. The transverse blades produce no inclined jets, and the boxes do not allow to organize a recovery of the blowing gas perpendicular to the strip, as already mentioned above.

According to another design, and in order to limit the flow of gas in a direction parallel to the running direction of the strip, a commonly used solution is shown in FIGS. Figures 7 and 8 (the figure 8 being a section according to VIII-VIII of the figure 7 ). This solution consists in using tubular blowing nozzles 41 of axis 48, having bottoms 46 and a gas inlet 47, said nozzles being pierced with several circular holes 42, which are oblong or slit-shaped, allowing blowing jets 45 on the strip 43 scrolling in the direction 100, in a direction normal to the plane of the strip. Even if the confinement between the strip 43 and the blast nozzles 41 is smaller than with the arrangements using tube boxes, and allows some recovery of the gases in a direction normal to the plane of the strip between the blowing nozzles, this confinement generates very unfavorable pressure effects leading to the same phenomena as those described with reference to Figures 5 and 6 . This result can be demonstrated by modeling the pressures generated by this configuration, and the band is not stabilized in an optimal pass line, that is to say centered between the blowing nozzles. Alternatively, the document US-A-3,262,688 teaches to use cylindrical blow nozzles pierced with circular holes which are arranged to produce either straight jets and transversely inclined jets (FIGS. 13 to 15), or straight jets and longitudinally inclined jets (FIGS. 16 to 18). For inclined jets, the nozzles are arranged in pairs so as to direct their jet towards the same point of impact on the moving strip.

Finally, the document EP 1 067 204 A1 discloses a solution for suppressing vibrations by adjusting the pressure and / or the flow rate of gas blown in the transverse direction of the strip. In addition to the complexity of the adjustment to be adapted to each product to be treated, this method has two major disadvantages. In the first place, the strip may be made to be not parallel to the blowing devices, thus reducing the distance between the strip and the device, and increasing the risks of contact. Finally, the cooling capacity is not maximum, and the reduction of the speed and / or the pressure on one side can not be compensated by an increase in the speed or pressure of the jets on the other side if the speed or blowing capacity limits have already been reached.

OBJECT OF THE INVENTION

The aim of the invention is to propose a cooling method that optimizes both the thermal and aeraulic aspects, that is to say maximizing the cooling, while minimizing the vibrations or the strip offsets by a self-centering effect tending to reduce the band in an ideal pass line when it is deported or when it is rotated relative to its theoretical line.

The fundamental principles of the approach of the invention are to combine the advantages of a minimized containment, and a limitation of the flow of gases in a plane parallel to the band with optimized blowing by directed jets ensuring both cooling and stability of the band.

This approach therefore excludes previous solutions using cooling boxes (following the Figures 4 to 6 ) which by nature limit de facto the available volume between the band and the boxes (and this even in the case of blown tubes added).

This approach is also very far from previous solutions with blow-through nozzles pierced with holes (depending on the Figures 7 and 8 ) which leave substantial containment between the band and the nozzles. In addition, the usually small thickness of the blowing nozzles makes it impossible to direct the jets by simple drilling or machining of the blast nozzles.

GENERAL DEFINITION OF THE INVENTION

The aforementioned technical problem is solved according to the invention by a cooling method of the aforementioned type, wherein the gas or air jets are emitted from blowing tubes fitted to tubular nozzles arranged remotely one of the other transversely to the direction of movement of the strip, said jets being directed towards the relevant face of the strip by being inclined both substantially towards the edges of said strip in a plane perpendicular to the plane of the strip and to the direction moving said strip, and upstream or downstream of the strip in a plane perpendicular to the plane of the strip and parallel to the direction of movement of said strip, according to the characterizing part of claim 1.

Advantageously, the jets of gas or air emitted from the same tubular nozzle are inclined upstream and downstream of the strip. We thus obtain a better blowing efficiency for the same number of tubular nozzles.

Also preferably, the distance between two adjacent tubular nozzles on the same side of the strip is chosen such that the points of impact of the gas or air jets on the strip are substantially equidistant in a direction parallel to the direction of movement of said band. This is very favorable for the stability of the band during the scrolling thereof.

Advantageously, the jets of gas or air emitted from the same tubular nozzle are inclined essentially towards the edges of the strip in such a way that the points of impact of said jets on said strip are substantially equidistant in a direction perpendicular to the direction of movement of the strip. In particular, the jets of gas or air emitted from the same tubular nozzle are inclined essentially towards the edges of the strip at an increasing inclination, from the center line of the strip towards the edges of said strip, from about 0 ° to an angle less than 15 °.

More preferably, the jets of gas or air are organized to have a substantially constant jet distance regardless of their inclination.

The invention also relates to a device for implementing an improvement method having at least one of the abovementioned characteristics, said device being remarkable in that it comprises, on either side of the moving strip, a plurality of tubular nozzles arranged at a distance from one another transversely to the direction of movement of the strip, each tubular nozzle being equipped with blowing tubes pointing towards one side of the strip, said blowing tubes being inclined at the times substantially to the edges of said strip in a plane perpendicular to the plane of the strip and to the direction of movement of said strip, and upstream or downstream of the strip in a plane perpendicular to the plane of the strip and parallel to the direction of movement of said band.

It is advantageous to provide that each tubular nozzle is equipped with two rows of blowing tubes, the tubes of one row being inclined upstream while the tubes of the other row are inclined downstream, preferably with the same angle of inclination. In particular, the distance between two adjacent tubular nozzles on the same side of the strip is chosen in such a way that the points of impact of the jets emitted by the shot rows of blow tubes are substantially equidistant in a direction parallel to the direction of movement of said strip.

Advantageously then, the blowing tubes of each row of the same tubular nozzle are inclined essentially towards the edges of the strip in such a way that the points of impact of the jets emitted from the blowing tubes of said row are substantially equidistant in a direction perpendicular to the direction of movement of said strip. In particular, the blow tubes of the same row are inclined essentially towards the edges of the strip at an increasing inclination, starting from the median line of the strip towards the edges of said strip, of approximately 0 ° to an angle less than 15 °.

More preferably, the blowing tubes of each tubular nozzle are dimensioned in length so that the jets of gas or air emitted by said tubes have a substantially constant jet distance regardless of their inclination.

Finally, it can be provided that the tubular nozzles have a circular, oblong, triangular, square, rectangular or polygonal section.

Other characteristics and advantages of the invention will emerge more clearly in the light of the following description of a particular embodiment, with reference to the following Figures 9 and 10 , the figure 9 being a section according to IX-IX of the figure 10 .

DETAILED DESCRIPTION OF THE MEANS FOR IMPLEMENTING THE INVENTION

• Possibilité de reprise des gaz soufflés après impact sur la bande dans une direction sensiblement normale au plan de la bande par utilisation de buses de soufflage de section préférentiellement circulaire, oblongue, carrée ou rectangulaire, ou polygonale, permettant une reprise des gaz soufflés dans les espaces situés entre les buses.
• Limitation du confinement entre la bande et les dispositifs de soufflage en augmentant le volume disponible entre les buses de soufflage et la bande, afin d'avoir une force (respectivement un couple) de rappel tendant à ramener la bande dans sa ligne de passe théorique lorsque celle-ci présente un déport (respectivement une rotation) par rapport à sa ligne de passe théorique, ceci sans augmenter la distance de soufflage. Cette limitation du confinement peut être réalisée en augmentant la distance entre la bande et les buses sans augmenter la distance de soufflage par utilisation de tubes creux de soufflage fixés sur les buses en une ou plusieurs rangées.
• Canalisation ou guidage des jets de soufflage vers les bords de la bande afin d'avoir une force (respectivement un couple) de rappel tendant à ramener la bande dans sa ligne de passe théorique lorsque celle-ci présente un déport (respectivement une rotation) par rapport à sa ligne de passe théorique. Cette orientation des jets par inclinaison de tout ou partie des tubes par rapport à une direction normale au plan de la bande est compatible avec un refroidissement optimisé, c'est-à-dire un maillage des points d'impact du gaz soufflé sensiblement constant et une distance de soufflage sensiblement constante.

Basically, the means for implementing the invention in a chamber or a cooling zone consist in combining the technical effects described below.

• Possibility of recovery of the blown gases after impact on the strip in a direction substantially normal to the plane of the strip by using blowing nozzles of preferably circular, oblong, square or rectangular, or polygonal section, allowing a recovery of the gases blown into the spaces between the nozzles.
• Limiting the confinement between the band and the blowing devices by increasing the available volume between the blast nozzles and the band, so as to have a restoring force (or torque) tending to bring the band back to its theoretical line of this has an offset (respectively a rotation) with respect to its theoretical line of passage, without increasing the blowing distance. This limitation of confinement can be achieved by increasing the distance between the band and the nozzles without increasing the blowing distance by using hollow blow tubes fixed on the nozzles in one or more rows.
• Channeling or guiding the blowing jets towards the edges of the strip in order to have a force (respectively a torque) of return tending to bring the strip back to its theoretical line of passage when the latter has an offset (respectively a rotation) by relation to its theoretical line of This orientation of the jets by inclining all or part of the tubes relative to a normal direction to the plane of the band is compatible with optimized cooling, that is to say a mesh of the impact points of the substantially constant blast gas and a substantially constant blowing distance.

Thus, cooling and tape stability are optimized.

We will now refer to Figures 9 and 10 to describe more concretely and in detail a particular embodiment of the invention.

The Figures 9 and 10 illustrate a cooling device 50, of which only two pairs of tubular blowing nozzles 51 have been shown, these blowing nozzles being situated on either side of the band 53 which moves in a running direction denoted 100. The blow nozzles 51 preferably have a circular section as shown here with an axis 56, but may according to other embodiments of the invention have an oblong, triangular, square, rectangular or polygonal section.

Hollow discharge tubes 52 are fixed on the tubular nozzles 51. These tubes are arranged in one or more rows. The arrangement and the row number of the blowing tubes must be provided in order to have a mesh of the points of impact on the strip which is substantially equidistant in order to optimize the cooling and to limit the thermomechanical stresses exerted on the strip.

As illustrated on the figure 9 , the tubular nozzles 51 are arranged at a distance from each other transversely to the direction of travel 100 of the band, each tubular nozzle 51 being equipped with blow tubes 52 pointing towards one face of the band, with a symmetrical disposition relative to the plane of said strip so as to have points of impact of the emitted jets 58 which are in correspondence on each of the faces of the strip 53.

According to a feature of the invention, the blow tubes 52 are inclined both substantially to the edges of the band 53 in a plane perpendicular to the plane of the band and to the direction of movement of said band (as is visible on the figure 10 ), and upstream or downstream of the band 53 (with reference to the direction of travel) in a plane P perpendicular to the plane of the strip and parallel to the direction 100 of displacement of said strip (as is visible on the figure 9 ).

The term "substantially" used above is intended to indicate that some blowing tubes 52, near the center line LM of the strip 53, may emit jets which are perpendicular to the plane of the strip, the great majority of blast tubes 52 nevertheless having an inclination at an angle α with respect to the normal to the plane of the strip. This inclination is preferably increasing, from the center line LM of the strip towards the edges of said strip, from about 0 ° to an angle of less than 15 °.

In this case, the blowing tubes 52 are inclined towards the edges of the strip by an angle α ranging from 0 ° to 15 ° at the maximum, as represented by FIG. figure 10 which is a view following B of the figure 9 . This inclination may concern all or part of the tubes according to different embodiments of the invention. This makes it possible to channel the residual flow of gas (that is to say the non-evacuated flow to a rear direction perpendicular to the plane of the strip after heat exchange with said strip) in preferential directions towards the band edges tending to stabilize. said band.

One of the cooling performance parameters is the blowing distance, that is the distance of the emitted jet 58, between the free end 54 of a tube 52 and the corresponding point of impact 55 on the strip, for the jet emitted by this tube. In order to maintain a homogeneous cooling capacity on the strip whatever the inclination of the tubes, the length of each tube 52 can be determined according to its inclination in order to have jet distances substantially constant, and therefore a homogeneous cooling capacity. In practice, the length of the tubes will be greater as the inclination α is large. Numerical modelings show an optimal stabilizing effect for a tilting angle of the tubes that remains less than 15 ° towards the band edges.

The numerical modeling of this configuration shows a self-stabilizing effect during a shift or a rotation of the band with respect to the theoretical line of the pass. The resultant of the pressures thus tends to bring the band to the center.

It should be noted that the reminder of the band in position is carried out naturally without any particular adjustment, and without operator or computer action, and that the optimum cooling capacity is preserved.

On the figure 10 the distance between the tubular nozzles 51 and the band 53 was noted D. This distance D is greater than that which would exist with nozzles simply perforated at equal blowing distances.

The blowing tubes 52 are also inclined upstream or downstream of the band 53 in a plane perpendicular to the plane of the strip and parallel to the direction 100 of displacement of said strip.

Tubular nozzles 51 could be provided with a single row of blowing tubes 52, oriented either downstream or upstream. For greater efficiency and compactness, it is interesting to predict, as illustrated in figure 9 , that each tubular nozzle 51 is equipped with two rows of blast tubes 52, the tubes of one row being inclined upstream while the tubes of the other row are inclined downstream, and preferably with the same angle of inclination noted here β.

The impact points 55 of the jets 58 emitted from the two rows of tubes 52 of each tubular nozzle 51 are at a distance denoted i. It is then advantageous to choose the distance d between two adjacent tubular nozzles 51 located in the same side of the band 53 so that all the points of impact 55 are equidistant (distance i). This results in obtaining a regular and optimized mesh of the impact points of the blowing 55. This distance d then allows an optimal recovery of the gases, in a direction substantially normal to the plane of the band, which has the effect of reducing the depressions may exist between the impact zones.

Finally, it is advantageous to provide that the blowing tubes 52 are all dimensioned in length so that the jets of gas or air 58 have a jet distance a (between the outlet orifice 54 of a tube 52 and the corresponding point of impact 55) which is substantially constant regardless of their inclination.

It is thus ensured to provide a cooling power distributed in a perfectly homogeneous manner on the part of the strip which is subjected to the jets of gas or air.

• gain de productivité de la ligne, par application d'une capacité de refroidissement supérieure à celle des solutions conventionnelles, sans vibrations de la bande ;
• gain de qualité et de productivité par garantie de non marquage de la bande par contact dû aux vibrations (avec les conséquences associées de production de second choix, de ralentissement de ligne, ou de casse de bande) ;
• gain de flexibilité par la disparition de tout réglage et/ou action visant à réduire l'apparition de vibrations brations dans les solutions traditionnelles ;
• augmentation de la capacité des installations :
  • le procédé réduit les vibrations tout en optimisant le refroidissement, ce qui permet de réduire la distance entre les appuis de bande dans les chambres ou les zones de refroidissement. Un exemple d'avantage particulièrement important est la possibilité de réduction de hauteur des tours de refroidissement après galvanisation à chaud suivant la figure 3.

The invention provides very important advantages, which are recalled below:

• increased productivity of the line, by applying a cooling capacity greater than that of conventional solutions, without vibrations of the band;
• gain in quality and productivity by guaranteeing non-marking of the band by vibration contact (with the associated consequences of production of second choice, slowing of line, or breaking of tape);
• increased flexibility by the disappearance of any adjustment and / or action aimed at reducing the appearance of vibrations brations in traditional solutions;
• increased capacity of facilities:
  • the method reduces vibration while optimizing cooling, thereby reducing the distance between the tape bearings in the chambers or cooling zones. An example of a particularly important advantage is the possibility of reducing the height of the cooling towers after hot-dip galvanizing according to the figure 3 .

Claims (13)

1. Method of cooling a strip of steel or aluminum traveling in a line for heat treating or coating, in which jets of gas or air are projected against each of the faces of the traveling strip, wherein the jets of gas or air (58) are emitted from blow tubes (52) fitted to tubular nozzles (51) arranged at a distance one from the other transversely to the travel direction (100) of the strip (53), said jets being directed towards the corresponding face of the strip while being inclined simultaneously essentially towards the edges of said strip in a plane perpendicular to the plane of the strip and to the travel direction (100) of said strip, and towards the upstream or downstream end of the strip in a plane perpendicular to the plane of the strip and parallel to the travel direction (100) of said strip.
2. Method according to claim 1, wherein the jets of gas or air (58) emitted from a single tubular nozzle (51) are inclined both towards the upstream end and towards the downstream end of the strip (53).
3. Method according claim 2, wherein the distance (d) between two adjacent tubular nozzles (51) on the same side of the strip (53) is selected in such a manner that the points of impact (55) of the jets of gas or air (58) on the strip are substantially equidistant in a direction parallel to the travel direction (100) of said strip.
4. Method according to any of claims 1 to 3, wherein the jets of gas or air (58) emitted from a given tubular nozzle (51) are inclined essentially towards the edges of the strip (53) in such a manner that the points of impact (55) of said jets on said strip are substantially equidistant in a direction perpendicular to the travel direction (100) of the strip.
5. Method according claim 4, wherein the jets of gas or air (58) emitted from a given tubular nozzle (51) are inclined essentially towards the edges of the strip (53) at an inclination that increases going from the midline of the strip towards the edges of said strip from about 0° to an angle of less than 15°.
6. Method according to any of claims 1 to 5, wherein the jets of gas or air (58) are organized to present a jet distance (a) that is substantially constant regardless of their angle of inclination.
7. Apparatus for implementing the method according to any of claims 1 to 6, wherein the apparatus includes a plurality of tubular nozzles (51) on either side of the traveling strip (53), the nozzles being arranged at a distance from one another transversely to the travel direction (100) of the strip, each tubular nozzle (51) being fitted with blow tubes (52) pointing towards a face of the strip, said blow tubes being inclined both essentially towards the edges of said strip in a plane perpendicular to the plane of the strip and to the travel direction (100) of said strip, and towards the upstream end or downstream end of the strip in a plane perpendicular to the plane of the strip and parallel to the travel direction (100) of said strip.
8. Apparatus according to claim 7, wherein each tubular nozzle (51) is fitted with two rows of blow tubes (52), the tubes of one row being inclined upstream while the tubes of the other row are inclined downstream, preferably at the same angle of inclination.
9. Apparatus according to claim 8, wherein the distance (d) between two adjacent tubular nozzles (51) on the same side of the strip (53) is selected in such a manner that the points of impact (55) of the jets (58) emitted from the rows of blow tubes (52) are substantially equidistant in a direction parallel to the travel direction (100) of said strip.
10. Apparatus according to claim 8 or claim 9, wherein the blow tubes (52) of each row of a given tubular nozzle (51) are inclined essentially towards the edges of the strip (53) in such a manner that the points of impact (55) of the jets (58) emitted from the blow tubes of said row are substantially equidistant in a direction perpendicular to the travel direction (100) of said strip.
11. Apparatus according to claim 10, wherein the blow tubes (52) of a given row are inclined essentially towards the edges of the strip (53) at an angle of inclination that increases from the midline of the strip going towards the edges of said strip from about 0° to an angle of less than 15°.
12. Apparatus according to any of claims 7 to 11, wherein the blow tubes (52) of each tubular nozzle (51) are dimensioned lengthwise in such a manner that the jets of gas or air (58) emitted by said tubes present a jet distance (a) that is substantially constant regardless of their angle of inclination.
13. Apparatus according to any of claims 7 to 12, wherein the tubular nozzles (51) are circular, oblong, triangular, square, rectangular, or polygonal in section.

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