EP1375018B1 - Strip guide - Google Patents

Abstract

The sheet guiding device has a pair of deflectors (2,2') whose axes are oriented relative to the longitudinal running axis of a sheet, such that the output and input generatrices (5b,5'a) of respective deflectors (2,2'), are parallel in same tangent plane common to both the deflectors.

Description

The subject of the invention is a device for guiding a strip product intended especially for production and processing installations for hot-rolled or cold-rolled metal strips.

The steel and metallurgical industry makes available to users and processors various types of products having various sizes and, in particular, flat products consisting of sheets of varying thickness depending on use, and which are generally wound in coils.

To produce these sheets and give them the required thickness, one carries out so-called operations of hot rolling and cold rolling. In addition, the sheet must undergo various treatments before rolling, such as descaling, degreasing and pickling, as well as finishing treatments.

These various treatments must obviously be performed in different facilities. It is possible, for example, to perform a chemical stripping by scrolling the sheet in a succession of acid baths, an annealing by passing through an oven, or a cold rolling in an installation comprising several successive cages operating in tandem.

Each treatment therefore requires a specific installation and a scrolling speed adapted to the treatment. Therefore, previously, the various treatments were normally performed in separate sections each associated with a unwinder and a winder placed, respectively, upstream and downstream in the direction of travel. In this case, the web runs to pass into the processing section and is wound at the exit thereof forming a reel which is transported to the next processing facility.

The weight of the coil obviously depends on the thickness of the sheet and the rolled length, as well as the nature of the metal but it is still very important.

For example, in the case of steel sheets, the weight of a coil is commonly 15 to 25 tons. It is therefore necessary to lifting and handling equipment adapted to the dimensions and weight of the reels for transporting them from one processing section to the next.

In order to reduce these manipulations and to increase productivity, it has been proposed for several years to produce so-called continuous or semi-continuous production installations in which the tape runs continuously in several successive processing sections.

These different sections are normally placed one after the other along the same running direction of the strip and the result is that the installation extends over a very great length, especially since to compensate for variations in speed between two successive sections, it is often necessary to interpose therebetween an accumulation device with a strip length of up to several hundred meters.

Admittedly, it is possible to place on the path of the strip baffle rollers making it possible to change the level of scrolling so as, for example, to superimpose several sections, but such an installation remains very bulky and therefore requires a very large terrain.

In addition, it is often necessary to transform existing factories by modernizing certain parts of the installation and linking them together to achieve continuous band scrolling. It is then necessary to adapt to the configuration of the plant in which the processing sections to be connected are not always aligned, the scrolling directions in two successive sections being often different and can be shifted, transversely or in height. It is therefore necessary, in this case, to impose on the band a change of direction more or less important.

For this purpose, in a known arrangement, the strip may form, between two successive treatment sections, a free loop suspended between two deflection rolls whose axes can be oriented differently to change the direction of scrolling.

However, to achieve a large deviation angle without risk of friction between the two strands of the band, it is necessary that the loop is wide enough and, therefore, cumbersome.

In addition, a free loop is subjected only to its own weight and it is therefore necessary to provide, upstream and downstream, tensioning devices for reducing the tensile force on the strip to the value necessary in the other sections. This increases the size of the installation and complicates the control of the scrolling of the band.

It is therefore sometimes difficult to incorporate a free band into an existing installation.

To solve such problems, it has already been proposed in the document FR-A-2336331 , to pass the band on several rollers placed at different levels and rotating around axes parallel to the same plane but angularly offset. In this case, as there is no free loop, the band can remain under tension but the change of direction from one roll to the next determines a corresponding twist of the part of the band between the two rollers, which translates by an extension of the two banks of the band with respect to the central part.

This difference in elongation between the longitudinal fibers of the strip is compensated by giving the roll a slight bulge so as to equalize the paths traveled by the various longitudinal fibers.

However, for the differences in elongation between the central part and the banks are acceptable, it is necessary that the angular deflection is relatively low, for example 20 ° and that the distance between two consecutive rollers is of the order five times the width of the strip. Therefore, to make a deflection, for example, of 90 °, it is necessary to multiply the number of rolls. In addition, the difference in level between two consecutive rolls must be in the order of 7 to 10 meters for a bandwidth of between 1.5 and 2 meters.

Such installations, often called "turning turns", therefore remain very cumbersome and quite expensive.

To achieve an angular directional change of the longitudinal axis of travel of a band, it has also been proposed to use a conical deflection roll on which the band winds in a spiral. Such a device describes, for example, in the document US Patent 4,687,125 is much less bulky than a turn and can be fixed on the existing framework of mechanical equipment or directly on the ground, on a light frame.

In such a device, the band normally arrives near the small base of the conical roller and progressively moves away towards the large base during its rotation. The orientation of the strip with respect to the successive generatrices of the cone on which it is based varies progressively as well as the tangential speed and it is therefore necessary, in order to avoid deterioration of the strip, to apply it to a set of rollers rotatably mounted about axes perpendicular to the direction of travel and which are divided into series each defining a bearing generatrix of a virtual conical surface enveloping all the rollers.

In these known arrangements, the support rollers of the strip are mounted on a fixed support. Their orientation and their spacing must therefore vary from one series to another to follow the progress of the tape. However, because of the conicity of the bearing surface, the band tends to slide towards the large base and must therefore be maintained laterally. The use of two baffles placed upside down, as described in the document JP-A-59-229230 allows, however, to avoid this disadvantage.

In another provision, described in the document JP-A-59179210 , we use a conical deflector mounted rotating around of an axis and carrying a plurality of satellite rollers which define successive generatrices of support of the strip. As it winds in a spiral, each roller must move axially during the rotation of the deflector, to follow the movement of the band towards the large base of the cone.

Such devices are therefore quite complex and expensive and do not prevent slipping of the band on its support members which may therefore deteriorate its surface quality.

In addition, to allow rotation of the rollers, the application pressure of the band must be limited. However, in the case of a relatively rigid metal strip, it must be subjected to a fairly strong tension.

The object of the invention is to solve all of these problems by means of a device that is simpler and less expensive than the known devices and also makes it possible to maintain the orientation of the strip with respect to its support members by thus reducing the risk of slipping and deterioration of its surface.

In addition, such a device provides many possibilities of deflection and change of direction to adapt simply and inexpensively to an existing or new plant, using shorter hall lengths and a number of lifting bridges less important than in a conventional installation.

The invention therefore relates to a device for guiding a strip product moving along a longitudinal axis and comprising at least two conical deflectors each having a right end and a wide end and arranged head to tail, the narrow end of one deflectors being placed on the same side, with respect to the axis of the strip as the wide end of the other deflector.

According to the invention, each deflector comprises each deflector comprises a fixed support on which are mounted, in the manner of satellites, a plurality of rollers of guiding distributed over an angular deflector deflector sector and rotatably mounted about axes forming the same angle (A) with an axis of the deflector and, the strip being applied under tension on each deflector, along a passing virtual conical surface by an external generatrix of each roller, the axes of the deflectors are oriented relative to the longitudinal axis of travel of the strip so that it comprises successively, in the direction of travel, an upstream portion tangent to a generator of input to a first deflector and having an axis perpendicular to said input generator, a central portion tangent, upstream to an output generator of the first deflector and, downstream, to an input generator on the second deflector and having a longitudinal axis perpendicular to said generatrices, respectively output and input, and a downstream portion tangent to a generator output of the sec deflector and having a longitudinal axis perpendicular to said output generator.

With this arrangement, the strip can be subjected to a tensile stress determined according to the rigidity of the strip so as to produce an application under tension with elastic deformation of the strip on the set of rollers of each of the deflectors, the head-to-tail assembly of said deflectors compensating for differences in elongation on both sides of the strip, on either side of the longitudinal axis and determining a centering effect of the strip with a progressive rotation of its longitudinal axis capable of maintaining the perpendicularity of the latter with the external generatrix of each of the rollers of the deflector.

In this way, the tensile force applied to the strip is distributed over the width of the latter gradually increasing from its inner edge located on the narrow side of the deflector to the outer side of the bank on the broad side, with a gradual elongation of the fibers of the web, so that the tangential velocity of each fiber along a external generator of each satellite roller is substantially constant from one bank to another.

In a preferred embodiment, each roll of a deflector has a curved outer profile, with a central portion of diameter slightly greater than the ends, and the tensile force applied to the strip determines a self-centering of the strip of which the longitudinal axis remains in the central portion and orthogonal to the external generatrix of each of the rollers of the deflector.

According to another preferred feature, the device comprises an even number of baffles associated two by two, the two baffles of each pair having the same angle (A) of inclination of the guide rollers.

In a first embodiment of the invention, the axes of two successive deflectors are oriented so that the output generator of the first deflector and the input generator on the second deflector are parallel and placed in the same tangent plane common to the two deflectors, in which extends the central portion of the strip.

But, in another embodiment, the output generator of the first deflector and the input generator on the second deflector are placed in two planes parallel to each other and perpendicular to the axis of the central portion of the strip and are between they have a non-zero angle, said generatrices being spaced apart by a sufficient distance so that the longitudinal median plane of the central part rotates progressively about the axis.

Preferably, the two baffles are placed on the same side of the strip and thus perform an inversion of the direction of travel.

In this case, a right roll can return in the first direction. But it is possible, also, to place the two deflectors on both sides of the band whose direction of scrolling then preserved.

Moreover, the invention makes it possible to vary, on the one hand, the angle at the apex of the baffles, and on the other hand, their relative positions and their orientations to determine a lateral offset or an angular deviation of the band.

In a particularly advantageous manner, two successive deflectors are arranged so that the input generator on the first deflector, and the output generator of the second deflector are placed in two parallel planes of scroll, respectively of the upstream part and the downstream part. and that the longitudinal axes of said upstream and downstream parts are spaced apart, at said input and output generating deflectors, by a distance $$\mathrm{D}\mathrm{=}\mathrm{H\; tg\; A}\mathrm{,}$$

A being the angle at the apex of each deflector and H the distance between the two scroll planes respectively upstream and downstream of the strip.

In a first embodiment, the generators respectively of entry on the first deflector and of exit of the second deflector are parallel, the upstream part and the downstream part of the band being centered, respectively, on two longitudinal median planes parallel to each other and away from the distance D = H tg A.

In another embodiment, the axes of the two deflectors are oriented so that the input generators on the first deflector and output of the second deflector are between them a non-zero angle, the upstream part and the downstream part of the band. being centered, respectively, on two longitudinal median planes forming between them the same non-zero angle.

It can thus be seen that the invention offers multiple possibilities making it possible to adapt to the most diverse situations.

But the invention will be better understood from the following description of certain particular embodiments given to As a simple non-limiting example, and shown in the accompanying drawings.

The figure 1 shows, in perspective, a satellite roller deflector according to the invention.

The figure 2 is a front view of a device with two baffles according to the invention.

The figure 3 is a perspective view of the device of the figure 2 .

The figure 4 shows, in front view, a lateral offset device with four deflectors.

The figure 5 is a schematic view from above of the device of the figure 4 .

The figure 6 shows, in perspective, an angular deflection device.

The figure 7 shows an angular deflection device of two substantially horizontal strands.

The figure 8 is a side view of the device of the figure 7 .

The figure 9 is a top view of the entire device of the figure 7 .

As indicated, until now, it seemed natural, in the web guiding devices and, in particular, the metal strip, to use deflection rollers having a cylindrical profile and rotating about an orthogonal axis to the longitudinal axis of scrolling of the product. In this case, the baffle roller modifies the direction of the plane of travel of the two parts, respectively upstream and downstream of the strip tangential to the baffle rollers, but these remain centered in the same longitudinal median plane orthogonal to the axis of rotation of the roll. cylindrical.

As mentioned above, the use of conical deflectors makes it possible to achieve an angular deflection of the longitudinal median plane of the strip, but the arrangements provided up to now were rather complex and presented certain disadvantages.

To solve these problems, the object of the invention is a new type of conical deflector constituted, as shown in FIG. figure 1 , a fixed support 3 carrying a plurality of cylindrical rollers 4 distributed on its periphery in the manner of satellites.

Each satellite roll 4 is rotatably mounted about an axis 40 on two bearings 41, 41 'housed in housings fixed respectively on two ends, respectively enlarged 31 and thinned 31' of the support 3 which, in the example shown is limited by a conical face 33 of revolution about an axis 30, having an angle at the apex A. It should be noted that only the rollers 4 rotate about their axis under the action of the band 1, the support 3 being fixed . In addition, because it does not rotate with the band, the support 3 carries rollers 4 only on an angular sector 32 of winding of the band 1. Therefore, the conical face 33 of the support rollers 4 could be limited to this angular sector 32 which, most often will cover substantially a quadrant.

The axes of the rollers 4 are parallel to this conical face 33 and are therefore themselves placed in a virtual conical surface centered on the same axis 30 and having the same angle at the apex A.

When the band 1 winds on the deflector 2, it bears on each roll 4 along an external generatrix 5 opposite the support 3 and parallel to the axis 40 of the roll and to the conical face 33 of the support 3.

Therefore, the band 1 rotates around the deflector 2 following a virtual conical surface 43, symbolized in dashed line on the figure 6 , which passes through the generatrices of support 5 by wrapping all the rollers 4.

In this way, the strip comes into contact with the deflector 2 only along the external generatrices 5 of the rollers 4 which rotate about their axis 40.

Moreover, the strip to be guided is normally a metal strip which, given its rigidity, must be subjected to a large tensile force to apply on the baffle roll. According to another characteristic of the invention, the axis 30 of the deflector is oriented with respect to the general running direction of the strip so that the axis 10a of the upstream portion 1a thereof is perpendicular to the external generator. 5a of the first roller 4a and that the axis 10b of the downstream portion 1b is perpendicular to the external generator 5b of the last roller 4b of the series.

Because the strip is made of an elastoplastic material such as a metal and is kept under tension, it can be progressively deflected while remaining orthogonal to each roll and elastically deforming between two successive rolls, the elongation rate of the fibers longitudinally of the strip gradually increasing from its inner edge 12 facing the narrower end 31 'of the support 3 to the outer edge 13 facing the enlarged end 31.

Thanks to this increase in the rate of elongation, the speed of travel of the various longitudinal fibers of the band remains constant and equal to the tangential speed of the roll 4 at each point of the bearing generator 5.

Moreover, this variation in the elongation rates of the longitudinal fibers of the strip is compensated in a guiding device according to the invention which comprises two baffles 2, 2 'having the same angle at the apex A and placed head to tail, of the as shown in the other figures, the narrow end of one of the deflectors 2 being placed on the same side as the wide end of the other deflector 2 'relative to the longitudinal axis of travel of the strip.

So, as shown in figure 6 between two successive rollers 4i, 4j, the longitudinal axis 10 of the band rotates by an angle i equal to the angle between the axes of the two rollers.

Thus, on each roll, a recovery of the axis of travel of the strip 1 which remains orthogonal to the axis 30 of the conical deflector, the band remaining centered on each of the satellite rollers 4 and elastically deforming between each pair of two successive rollers.

In addition, according to another preferred and particularly advantageous feature of the invention, the profile of each roller 4 is not rigorously cylindrical but may be slightly curved, the diameter of its central portion 44 being a little larger than that of the ends. 42.

This produces a self-centering effect similar to that used in belt drive devices whose rollers are slightly curved in order to avoid an axial shift of the belt rotating at high speed.

For example, the figure 2 shows, in front view, such a guiding device shown in perspective on the figure 3 and comprising two deflector members 2, 2 'mounted on a frame C at two different levels.

Each deflector 2, 2 'is of the type shown in the figure 1 and therefore comprises a support 3 centered on an axis 30 and on which are mounted a plurality of satellite rollers 4 each rotating about an axis making, with the axis 30 of the support, an angle A which constitutes the angle at the apex of the conical deflector.

In the embodiment of Figures 2 and 3 , the two baffles 2, 2 'have parallel axes and inclined at the same angle A with respect to the horizontal. In this way, as we see on the figure 3 , the band 1 which arrives at a lower level in a running direction F successively passes on the two deflectors 2, 2 'and leaves in the opposite direction F', at a higher level.

As shown in figure 2 , the axis 30 of the lower baffle 2 is parallel to the plane of the figure and inclined relative to the horizontal of the angle at the apex A. The part 1a of the band arriving upstream of the lower baffle 2 is centered on a horizontal axis perpendicular to the plane of the figure and the lower generatrix 5a of the deflector 2 which constitutes the input generator on it. The band wraps around the lower deflector 2 by elastically deforming, and its central portion 1b between the two deflectors 2, 2 'is centered on an axis 10b perpendicular to the output generator 5b which is placed in an inclined plane of the angle A with respect to the horizontal. The longitudinal axis 10b of the central portion 1b is therefore inclined at the same angle A with respect to the vertical and perpendicular to the inlet generator 5'a on the second deflector 2 ', which is itself placed in an inclined plane the same angle A with respect to the horizontal.

The band 2 then winds on a quadrant of the upper deflector 2 'and its downstream part 1c leaves the device in a horizontal direction F' perpendicular to the plane of the figure 2 and the output generator 5'b of the upper baffle 2 '.

H étant la différence de niveau entre les génératrices, respectivement d'entrée 5a et de sortie 5'b des deux déflecteurs 2, 2' et A l'angle au sommet de chacun desdits déflecteurs.With this arrangement, the scrolling directions F, F 'of the two parts, respectively upstream 1a and downstream 1c of the band 1 remain parallel but are spaced transversely by a distance D such that: $$\mathrm{D}\mathrm{=}\mathrm{H}\mathrm{.}\mathrm{tg\; A}\mathrm{,}$$

H being the difference in level between the generators, respectively 5a input and 5'b output of the two deflectors 2, 2 'and A the apex angle of each of said baffles.

It should be noted that the output generator 5b of the first deflector 2 and the input generator 5'a on the second deflector 2 'are not parallel. The central portion 1b of the strip is thus subjected to a slight twist which does not, however, have any disadvantage if the height H is large relative to the width of the strip.

If this difference in level does not correspond to the implantation of the different sections of the treatment line, it is possible to pass the band on cylindrical rollers of conventional type to bring it to the desired level, misalignment D being, however, retained.

Similarly, the passage on a cylindrical roller can restore the general sense of scroll if it should be kept.

In any case, the longitudinal axis 10b being perpendicular to the two generatrices, respectively 5b output and input 5'a, the two banks 12b, 13b of the central portion 1b of the strip have the same length and mounting head- spade of the two deflectors 2, 2 'makes it possible to compensate for the differences in elongation along each conical deflector, so that the paths followed by the different longitudinal fibers of the strip have the same length.

As mentioned above, the use according to the invention of deflector members having a conical winding surface provides multiple possibilities of arrangement of said conical deflectors whose number and orientations can be varied in order to optimally respond to the installation requirements of the different sections of an installation, in particular for the modernization of an existing installation.

Thus, in the case of Figures 2 and 3 , the two conical deflectors 2, 2 'bear on the same face of the band by determining an inversion of the direction of travel. On the other hand, if the two deflectors 2, 2 'bear on the two opposite faces of the band 1, the incoming strand 1a and the outgoing strand 1c run in the same direction and are simply shifted transversely, which allows, for example to bypass a part of the structure of the building in which the installation is located.

For example, Figures 4 and 5 show another arrangement for making a large transverse shift on two parallel strands of the strip moving in the same direction.

In this case, two deflectors 2, 2 'are used which are placed head to tail at the same level and associated with two other deflectors 25, 25' placed at a higher level.

In the embodiment shown, the axes of all the deflectors 25, 2, 2 ', 25' are placed in vertical planes parallel to the plane of the figure 6 and are oriented so that, in the order of succession of the deflectors, the input generators of the odd-order members and the output generatrices of the even-rank members are all horizontal and parallel.

So, as shown in figure 5 which is seen from above the layout of the figure 4 , the band 1, which is wound successively on each of the four deflectors 25, 2, 2 ', 25', comprises an inlet strand 15a which arrives in the direction of movement F and is tangential to a horizontal inlet generator 45a of the first conical baffle 25, a descending oblique strand 15b, a horizontal strand 15c, an upward oblique strand 15d and an output strand 15e tangential and perpendicular to an output generator 45'b of the last deflector 25 '.

It can be seen that the odd input generators 5a and 5'a, respectively on the first 25 and the third deflector 2 'and the even output generatrices, respectively 5b of the second deflector 2 and 45'b of the fourth deflector 25', are all horizontal and parallel to each other so that the incoming strand 15a and the outgoing strand 15e scroll horizontally and in the same direction along parallel directions F, F '.

On the other hand, the oblique strands 15b, 15d are slightly twisted, but this torsion effect is not disadvantageous if the difference in level H between the input and output generators of each pair of deflectors, respectively 25, 2 and 2. ', 25' is large relative to the width of the strip 1.

A étant l'angle au sommet des organes de déviation.With this arrangement, the misalignment D 'between the incoming strand 15a and the outgoing strand 15e is such that: $$\mathrm{OF}\mathrm{=}2\mathrm{H}\mathrm{.}\mathrm{tg\; A}$$

A being the vertex angle of the deflection members.

Compared to the provision of the figure 2 this arrangement thus makes it possible to double the misalignment without modifying the direction of travel of the strip.

It should be noted that the rollers 25, 25 'are not necessarily at the same level and that one can adjust their positions relative to the two lower rollers 2, 2 'so as to achieve the desired misalignment.

Of course, the invention is not limited to the details of the embodiments which have just been described by way of example, but also covers the equivalent provisions falling within the scope of the claims.

For example, in the provision of Figures 2 to 4 , the two successive deflectors of 2, 2 'can be arranged so that the generatrix 5b output of the first deflector 2 and the generator 5'a input on the second deflector 2' are parallel and placed in the same plane of scrolling of the central part 1b of the band. In this case, the input generatrix 5a on the first deflector 2 and the output generator 5'b of the second deflector 2 'are still placed in two parallel planes but make an angle between them 2A', A 'being the projection of the angle at the apex A on a horizontal plane. The directions F and F 'of the upstream portion 1a and the downstream portion 1c are between them the same angle 2A'. It is therefore possible, if necessary, to determine an angular deviation of the longitudinal median planes of the two parts of the strip which, in addition, are offset laterally, at the two deflectors 2, 2 'of the distance D' = 2H .tg A.

Moreover, as shown on Figures 7, 8 and 9 , the height offset of the two parts, respectively upstream 1a and downstream 1c of the band can be reduced in the case where the central portion 1b remains flat.

So, as shown in figure 9 it is possible to achieve a deflection angle of the order of twice the vertex angle A of the two conical deflection members.

For an apex angle A of 22 ° 30, a deflection angle of about 45 ° can be achieved.

However, many other arrangements are possible.

For example, in the case of the provision of the figure 6 both deflectors can be placed so that the intermediate strand is horizontal.

On the other hand, in the case where the two deflectors 2, 2 'are sufficiently spaced to admit a slight twist of the intermediate strand 1b, the axes of the supports 3, 3' can be oriented so as to increase the deflection angle between the input and output generators and, therefore, between the axes 10a, 10c of the strands entering 1a and outgoing 1c.

Moreover, the angular sector 32 of application of the strip on a deflector is not necessarily straight and the input 1a and output 1c strands may not be horizontal but form, on the contrary, an upward or downward ramp.

The invention therefore provides multiple possibilities of arrangement of the successive sections of a treatment plant, in particular for the realization of a continuous line in an existing plant.

The reference signs inserted after the technical features mentioned in the claims, are intended only to facilitate the understanding of the latter and in no way limit the scope.

Claims (15)

1. Device for guiding a product in the form of a strip (1) travelling along a longitudinal axis (10) and comprising at least two conical deflectors (2, 2') each having a narrow end (22, 22') and a broad end (23, 23') and placed the opposite ways up, the narrow end (22) of one of the deflectors (2) being placed on the same side, regarding the axis (10) of the strip (1), as the broad end (23') of the other deflector (2'), characterized by the fact that

   • each deflector (2, 2') comprises a fixed stand (3, 3') on which are assembled, like satellites, a plurality of guiding rolls (4, 4') distributed on a deviation angular sector of the deflector (2, 2') and assembled rotating around axes (40, 40') at the same angle (A) to an axis (30, 30') of the deflector (2, 2'),

   • the strip (1) is leaning under tension on each deflector (2, 2'), along a virtual conical surface (43) passing through an external generatrix (5) of each roll (4), and

   • the axes (30, 30') of the deflectors (2, 2') are pointed regarding the longitudinal axis (10) of travel of the strip (1) so that the strip (1) comprises successively, in the travelling direction,

   - an upstream part (1a) at a tangent to an input generatrix (5a) on a first deflector (2) and having an axis (10a) perpendicular to said input generatrix (5a),

   - a central part (1b) at a tangent, upstream, to an output generatrix (5b) of the first deflector (2) and, downstream, to an input generatrix (5'a) on the second deflector (2') and having a longitudinal axis (10b) perpendicular to said generatrices, respectively of output (5b) and of input (5'a), and

   - a downstream part (1c) at a tangent to an output generatrix (5'b) of the second deflector (2') and having a longitudinal axis (10c) perpendicular to said output generatrix (5'b).
2. Guiding device according to claim 1, characterized by the fact that the strip (1) is subjected to a tractive effort determined according to the rigidity of the strip (1) in order to enable a leaning under tension with an elastic bending out of shape of the strip (1) on the whole set of rolls (4) of each one of the deflectors (2, 2'), the assembling the opposite ways up (2, 2') compensating the stretching differences, on each deflector (2, 2'), between the two sides of the strip (1), on both sides of the longitudinal axis (10) and determining a centring effect of the strip (1) with a progressive rotation of its longitudinal axis (10) able to keep it (10) perpendicular to the external generatrix (5, 5') of each one of the rolls (4, 4') of the deflector (2, 2').
3. Guiding device according to claim 2, wherein each part of the strip leaning on a deflector presents an internal face (12) on the side of the narrow end (22) of the deflector and an external face (13) on the side of the broad end (23), characterized by the fact that the tractive effort applied to the strip (1) is distributed along the width of it by increasing progressively from the internal face (12) to the external face (13), with a progressive stretching of the longitudinal fibers of the strip, in such a way that the travelling tangential speed of each fiber, along an external generatrix (5) of each satellite roll (4), is about constant from a face to another.
4. Guiding device according to anyone of previous claims characterized by the fact that

   • each roll (4, 4') of a deflector (2, 2') presents an external bulging profile, with a central part (44) of diameter slightly bigger than the ends (45), and

   • the tractive effort applied to the strip (1) determines a self-centring of the strip (1) which longitudinal axis (10) is held

   - in position in the central part (44) and

   - orthogonal to an external generatrix (5, 5') of leaning on each one of the rolls (4, 4') of the deflector (2, 2').
5. Guiding device according to anyone of previous claims, characterized by the fact that the strip (1) is leaning on an angular sector of about a quadrant of each deflector (2, 2').
6. Guiding device according to anyone of the previous claims, characterized by the fact it comprises an even number of deflectors (2, 2') working in pairs, the two deflectors (2, 2') of each pair having the same angle (A) of inclination of the guiding rolls (4, 4').
7. Guiding device according to anyone of the previous claims, characterized by the fact that the axes (30, 30') of two successive deflectors (2, 2') are pointed so that the output generatrix (5b) of the first deflector (2) and the input generatrix (5'a) on the second deflector (2') are parallel and placed in the same tangent plane common to both deflectors (2, 2') on which stretches the central part (1b) of the strip (1).
8. Guiding device according to anyone of claims 1 to 6, characterized by the fact that the output generatrix (5b) of the first deflector (2) and the input generatrix (5'a) on the second deflector (2')

   • are placed in two planes parallel to each other and perpendicular to the axis (10b) of the central part (1b) of the strip (1) and

   • are at a non null angle to each other.
9. Guiding device according to anyone of the previous claims, characterized by the fact that the two deflectors (2, 2') are leaning against two opposite faces of the strip (1) and determine a lateral shift of the longitudinal axis (10c) of the downstream part (1c) of the strip (1) regarding the one (10a) of the upstream part (1a), while keeping the same general travelling direction (F).
10. Guiding device according to anyone of claims 1 to 8, characterized by the fact that the two deflectors (2, 2') are leaning on the same face of the strip, and determine a lateral shift of the longitudinal axis (10c) of the downstream part (1c) of the strip (1) regarding the one (10a) of the upstream part (1a), with a reversal of the travelling direction (F).
11. Guiding device according to anyone of claims 9 and 10, characterized by the fact that

    • two deflectors (2, 2') are placed so that the input generatrix (5a) on the first deflector (2) and the output generatrix (5'b) of the second deflector (2') are placed in two travelling parallel planes, respectively of the upstream part (1a) and of the downstream part (1c) of the strip (1) and

    • the longitudinal axes (10a, 10c) of said upstream part (1a) and downstream part (1c) are spaced out, by said generatrices of input (5a) and of output (5'b), a distance of $$\mathrm{D}\mathrm{=}\mathrm{H\; tg\; A}$$

    

    
    apart,
    A being the angle at the top of each deflector (2, 2') and H being the distance between the two travelling planes, respectively upstream and downstream of the strip.
12. Guiding device according to anyone of claims 9, 10 and 11, characterized by the fact that the two deflectors (2, 2') are placed so that the output generatrices (5b) of the first deflector (2) is parallel to the input generatrix (5'a) on the second deflector (2'), the central part (1b) of the strip (1) being plane.
13. Guiding device according to claim 12, characterized by the fact that the input generatrix (5a) on the first deflector (2) and the output generatrix (5'b) of the second deflector (2') are parallel to the same plane and are at an angle equal to 2A' to each other, A' being the projection of the angle (A) at the top of each deflector (2, 2') on said plane of generatrices, the longitudinal median planes of the upstream part (1a) and downstream part (1b) of the strip (1) being at the same angle (2A') to each other.
14. Guiding device according to anyone of claims 9 to 11, characterized by the fact that the two deflectors (2, 2') are placed so that the generatrices of input (5a) and of output (5'b), respectively of the first (2) and of the second deflector (2') are placed in parallel planes and are at a non null angle to each other, the longitudinal median planes of upstream part (1a) and downstream part (1c) of the strip being perpendicular to said generatrices of input (5a) and of output (5'b) and being at the same non null angle to each other.
15. Guiding device according to claim 11, characterized by the fact that

    • the generatrices respectively of input (5a) on the first deflector (2) and of output (5'b) of the second deflector (2') are parallel and

    • the upstream part (1a) and the downstream part (1c) of the strip (1) are centered, respectively, on two longitudinal median planes parallel to each other and spaced out the distance D = H tg A apart.

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