EP1375018A1 - 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 specially intended for production and processing of rolled metal strips hot or cold.

The steel and metallurgical industry provides available to users and processors various types of products with various dimensions and, in particular, flat products made of sheets of variable thickness according to use, and which are generally wound in coils.

To produce these sheets and give them the required thickness, so-called hot rolling operations 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 carried out in different facilities. We can, for example realize a chemical pickling by scrolling of the sheet in a succession of acid baths, annealing by passage through an oven, or cold rolling in an installation comprising several successive cages operating in tandem.

Each treatment therefore requires an installation specific and a scrolling speed adapted to the treatment. This is why, before, the various treatments were, normally made in separate associated sections each with an unwinder and a winder placed, respectively, upstream and downstream in the direction of travel. In this case, the tape unwinds to pass in the section of treatment then is rolled up at the exit thereof forming a coil which is transported to the processing facility next.

The weight of the coil obviously depends on the thickness sheet and 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. So you have to plan lifting and handling equipment adapted to the dimensions and the weight of the coils to transport them from one section processing to the next.

To reduce these manipulations and increase the productivity, we have proposed, for several years, to realize so-called continuous or semi-continuous production facilities in which the tape runs continuously in several successive processing sections.

These different sections are normally placed one after another along the same direction of travel of the tape and as a result the installation spans a very great length, especially since, to compensate for speed variations between two successive sections, we are often led to interpose a device between them accumulation of up to a strip length several hundred meters.

Of course, we can place on the path of the strip deflector rollers for changing the level of scroll in order to, for example, superimpose several sections but such an installation remains very bulky and requires, therefore, a very large plot.

In addition, we often have to transform factories existing by modernizing parts of the installation and connecting them together to achieve continuous scrolling of the bandaged. It is then necessary to adapt to the configuration of the factory in which processing sections to be connected do not are not always aligned, the scrolling directions in two successive sections are often different and can be offset, transversely or vertically. It is therefore necessary, in this case, to impose on the band a change more or less important direction.

For this, in a known arrangement, the strip can form, between two successive treatment sections, a free loop suspended between two deflector rollers whose axes can be oriented differently to change the scroll direction.

However, to achieve a sufficient deflection angle important without risk of friction between the two strands of the strip, the loop must be wide enough and, therefore, cumbersome.

In addition, a free loop is only subject to its own weight and it is therefore necessary to provide, upstream and downstream, tensioning devices to reduce the effort of traction on the strip to the value necessary in the others sections. This increases the size of the installation and complicates the control of the tape travel.

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

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

This difference in elongation between the fibers longitudinal the tape is offset by giving the roller a slight bulge in order to equalize the paths traveled by the different longitudinal fibers.

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

Such facilities, often called "turn turns", therefore remain very bulky and quite expensive.

To make an angular direction change of the longitudinal axis of travel of a strip, it has also been proposed to use a conical deflection roller on which the strip winds in a spiral. Such a device described, for example, in the document US-A-4,687,125 is much less bulky than a turn and can therefore be fixed on the frame existing mechanical equipment or directly to ground, on a light frame.

In such a device, the strip normally arrives, at near the small base of the tapered roller and moves away gradually towards the large base, during its rotation. The orientation of the strip in relation to the generators of the cone on which it rests varies gradually as well as tangential velocity and so it's necessary, to avoid deterioration of the strip, to apply it on a set of rotating mounted rollers around axes perpendicular to the direction of travel and which are divided into series each defining a generator support of a virtual conical surface enveloping the assembly shingles.

In these known arrangements, the support rollers of the tape are mounted on a fixed support. Their orientation and spacing must therefore vary from one series to another to follow the unwinding of the tape. However, due to the taper of the support surface, the strip tends to slide towards the large base and must therefore be held laterally. The use of two deflectors placed head to tail, as described in the document JP-A-59-229230 allows, however, to avoid this disadvantage.

In another arrangement, described in document JP-A-59179210, we use a conical deflector rotatably mounted around of an axis and carrying a plurality of satellite rollers which define successive generators for supporting the strip. As this wraps in a spiral, each roll must be move axially during rotation of the deflector, to follow the movement of the strip towards the large base of the cone.

Such devices are therefore quite complex and expensive and do not make it possible to avoid a sliding of the strip on its supporting bodies which therefore risk deteriorating its quality area.

In addition, to allow the rollers to rotate, the pressure tape application should be limited. However, in the case of a relatively rigid metal strip, this must be subjected to quite strong tension.

The object of the invention is to resolve all of these problems thanks to a simpler and less expensive device that the known devices and making it possible, moreover, to maintain the orientation of the strip relative to its support members in thus reducing the risk of slipping and deterioration of its surface.

In addition, such a device gives many possibilities deviation and change of direction allowing simple and inexpensive adaptation to an existing factory or new, using shorter hall lengths and a fewer lifting bridges than in a classic installation.

The invention therefore relates to a device for guiding a produced in a strip running along a longitudinal axis and comprising at least two conical deflectors each having a straight end and a wide end and arranged head to tail, the narrow end of one of the deflectors being placed from the same side, relative to the axis of the strip as the wide end on the other deflector.

According to the invention, each deflector comprises each deflector comprises a fixed support on which are mounted, like satellites, a plurality of rolls of guidance distributed over an angular sector of deviation of the deflector and rotatably mounted around axes making the same angle (A) with an axis of the deflector and, the strip being applied energized on each deflector, along a surface virtual conical passing through an external generator of each roller, the axes of the deflectors are oriented relative to the longitudinal axis of travel of the strip so that the latter successively comprises, in the direction of scrolling, a upstream part tangent to an input generator on a first deflector and having an axis perpendicular to said generator input, a tangent central part, upstream at a output generator of the first deflector and, downstream, at a input generator on the second deflector and having an axis longitudinal perpendicular to said generators, output and input respectively, and a tangent downstream part to an output generator of the second deflector and having an axis longitudinal perpendicular to said output generator.

Thanks to this arrangement, the strip can be subjected to a tensile force determined as a function of the stiffness of the strip so as to produce a live application with elastic deformation of the strip on all the rollers of each of the deflectors, the head-to-tail mounting of said deflectors compensating for the differences in elongation of the two sides of the strip, on either side of the longitudinal axis and determining a centering effect of the strip with a rotation progressive of its longitudinal axis capable of maintaining the perpendicularity of it with the external generator of each of the deflector rollers.

In this way, the tensile force applied to the strip is spreads over the width thereof gradually increasing from its inner edge located on the narrow side of the deflector to the edge external located on the broad side, with a progressive lengthening of the longitudinal fibers of the strip, so that the speed tangential of travel of each fiber along a external generator of each satellite roller either substantially constant from one bank to the other.

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

According to another preferred characteristic, the device includes an even number of deflectors associated two by two, the two deflectors of each pair having the same angle (A) 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 generator inlet on the second deflector are parallel and placed in the same tangent plane common to the two deflectors, in which extends the central part of the strip.

But, in another embodiment, the generator of output of the first deflector and the input generator on the second deflector are placed in two parallel planes between them and perpendicular to the axis of the central part of the strip and form a non-zero angle between them, said generators being spaced apart by enough distance for the midplane longitudinal of the central part gradually turns around of the axis.

Preferably, the two deflectors are placed in the same side of the tape and therefore achieve a reversal of the direction of scrolling.

In this case, a straight roller allows you to return to the first sense. But it is also possible to place the two deflectors on both sides of the strip whose direction of scrolling then kept.

Furthermore, the invention makes it possible to vary, on the one hand the angle at the top of the deflectors, and on the other hand, their relative positions and their directions to determine a lateral offset or angular deviation of the strip.

In a particularly advantageous manner, two successive deflectors are arranged so that the inlet generator on the first deflector, and the outlet generator of the second deflector are placed in two parallel planes of travel, 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 inlet and outlet generating deflectors, by a distance D = H tg A,

A being the angle at the top 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 inlet on the first deflector and outlet of the second deflector are parallel, the upstream part and the part downstream of the strip being centered, respectively, on two planes longitudinal medians parallel to each other and spaced 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 outlet of the second deflector make a non-zero angle between them, the upstream part and the part downstream of the strip being centered, respectively, on two planes longitudinal medians making the same non-zero angle between them.

So we see that the invention gives multiple possibilities allowing to adapt to the most diverse situations.

But the invention will be better understood by the description following of some particular embodiments given to title of simple nonlimiting example, and represented on the attached drawings.

Figure 1 shows, in perspective, a deflector with satellite rollers according to the invention.

Figure 2 is a front view of a device with two deflectors according to the invention.

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

Figure 4 shows, in front view, a device for lateral offset with four deflectors.

Figure 5 is a schematic top view of the Figure 4 device.

Figure 6 shows, in perspective, a device for angular deviation.

Figure 7 shows an angular deflection device two substantially horizontal strands.

FIG. 8 is a side view of the device in FIG. 7.

Figure 9 is a top view of the entire Figure 7 device.

As mentioned, so far it seemed natural, in tape guiding devices and, in particular, metal strip, to use deflector rollers having a cylindrical profile and rotating around an axis orthogonal to the axis longitudinal movement of the product. In this case, the roller deflector changes the direction of the scroll plane of the two parts, respectively upstream and downstream of the strip tangent to deflector rollers but these remain centered in a same longitudinal median plane orthogonal to the axis of rotation of the cylindrical roller.

As mentioned above, the use of deflectors conical allows to realize an angular deviation of the plane longitudinal median of the strip but the planned arrangements so far were quite complex and presented some disadvantages.

To solve these problems, the subject of the invention is a new type of conical deflector made, as shown Figure 1, a fixed support 3 carrying a plurality of rollers cylindrical 4 distributed around its periphery in the manner of satellites.

Each satellite roller 4 is rotatably mounted around an axis 40 on two bearings 41, 41 ′ housed in fixed housings, 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 top A. It should be noted, that only the rollers 4 rotate around their axis under the action of band 1, the support 3 being fixed. In addition, the fact that it does not rotate with the strip, the support 3 only carries rollers 4 on one sector angular 32 of winding of the strip 1. Consequently, the conical face 33 for supporting the 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 face conical 33 and are therefore placed in a surface virtual conical centered on the same axis 30 and having the same angle at vertex A.

When the strip 1 is wound on the deflector 2, it takes support on each roller 4 along an external generator 5 opposite the support 3 and parallel to the axis 40 of the roller and to the conical face 33 of the support 3.

Consequently, the strip 1 rotates around the deflector 2 by following a virtual conical surface 43, symbolized in line mixed in FIG. 6, which passes through the support generators 5 in wrapping all the rollers 4.

In this way, the strip does not come into contact with the deflector 2 as along the external generators 5 of the rollers 4 which revolve around their axis 40.

Furthermore, the strip to be guided is normally a metal strip which, given its rigidity, must be subjected to a significant tensile force to apply to the deflector roller. According to another characteristic of the invention, the axis 30 of the deflector is oriented relative to the general direction of travel of the strip so that the axis 10a of the upstream part 1a thereof is perpendicular to the external generator 5a of the first roller 4a and that the axis 10b of the downstream part 1b is perpendicular to the external generator 5b of the last roll 4b in the series.

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

With this increase in the elongation rate, the running speed of the different longitudinal fibers of the band remains constant and equal to the tangential speed of the roller 4 at each point of the support generator 5.

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

Thus, as shown in Figure 6, between two rollers successive 4i, 4j, the longitudinal axis 10 of the strip turns one angle i equal to the angle between the axes of the two rollers.

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

Furthermore, according to another preferred characteristic and particularly advantageous of the invention, the profile of each roller 4 is not strictly cylindrical but can be slightly domed, the diameter of its central part 44 being a little larger than that of the ends 42.

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

By way of example, FIG. 2 shows, in front view, such a guide device shown in perspective in FIG. 3, and comprising two deflector members 2, 2 'mounted on a frame C, on 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 turning around an axis making, with axis 30 of support, an angle A which constitutes the angle at the top of the conical deflector.

In the embodiment of Figures 2 and 3, the two deflectors 2, 2 'have parallel and inclined axes of the same angle A with respect to the horizontal. So, as we can see in FIG. 3, the strip 1 which arrives at a next lower level a direction of travel F passes successively over the two deflectors 2, 2 'and starts in the opposite direction F', at one level superior.

As shown in Figure 2, the axis 30 of the deflector lower 2 is parallel to the plane of the figure and inclined relative to horizontally from the angle at the apex A. Part 1a of the strip arriving upstream of the lower deflector 2 is therefore centered on a horizontal axis perpendicular to the plane of the figure and to the lower generator 5a of the deflector 2 which constitutes the input generator on this one. The tape wraps around the lower deflector 2 by deforming elastically, and its part central 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 angle A with respect to the horizontal. The longitudinal axis 10b of the central part 1b is therefore inclined by the same angle A with respect to the vertical and perpendicular to the input generator 5'a on the second deflector 2 ', which is itself placed in an inclined plane of the same angle A with respect to the horizontal.

The strip 2 is then wound on a quadrant of the deflector upper 2 'and its downstream part 1c leaves the device according to a horizontal direction F 'perpendicular to the plane of Figure 2 and to the output generator 5'b of the upper deflector 2 '.

Thanks to this arrangement, the running directions F, F 'of the two parts, respectively upstream 1a and downstream 1c of the strip 1 remain parallel but are spaced transversely by a distance D such that: D = H.tg A, H being the difference in level between the generators, respectively of input 5a and output 5'b of the two deflectors 2, 2 'and At the angle at the top of each of said deflectors.

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 part 1b of the band therefore undergoes a slight twist which does, however, no disadvantage if the height H is large compared to the band width.

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

Similarly, the passage on a cylindrical roller allows restore the general direction of scrolling if it is to be retained.

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

As indicated above, the use according to the invention, deflector members having a surface of conical winding brings multiple possibilities arrangement of said conical deflectors which can be made vary the number and orientations in order to respond in a way optimal to the needs of setting up the different sections of an installation, in particular for the modernization of a existing installation.

Thus, in the case of Figures 2 and 3, the two conical deflectors 2, 2 'are supported on the same face of the strip by determining an inversion of the direction of travel. In on the other hand, if the two deflectors 2, 2 'rest on the two opposite sides of the strip 1, the strand returning 1a and the strand outgoing 1c scroll in the same direction and are simply offset transversely, which allows, for example bypass part of the frame of the building in which the installation is placed.

As an example, Figures 4 and 5 show another arrangement allowing transverse offset important on two parallel strands of the band running through the Same direction.

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

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

Thus, as shown in Figure 5 which is seen from above of the arrangement of Figure 4, the strip 1, which is wound successively on each of the four deflectors 25, 2, 2 ', 25', includes an input strand 15a which arrives in the direction of scroll F and is tangent to an input generator horizontal 45a of the first conical deflector 25, one strand descending oblique 15b, a horizontal strand 15c, an oblique strand ascending 15d and a tangent 15th output strand and perpendicular to an output generator 45'b of the last 25 'deflector.

We see that the odd input generators 5a and 5'a, respectively on the first 25 and the third deflector 2 'and the even output generators, 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 strand entering 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 does not have any drawback if the difference in level H between the generators of inputs and outlet of each pair of deflectors, respectively 25, 2 and 2 ', 25 'is large relative to the width of the strip 1.

Thanks to this arrangement, the misalignment D 'between the incoming strand 15a and the outgoing strand 15e is such that: D '= 2H.tg A A being the angle at the top of the deflection organs.

Compared to the arrangement of Figure 2, this arrangement thus makes it possible to double the misalignment without modifying the direction tape scrolling.

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

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

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

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

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

For a vertex angle A of 22 ° 30, we can therefore achieve a deflection angle of approximately 45 °.

However, many other arrangements are possible.

For example, in the case of the arrangement in Figure 6, the two deflectors can be placed so that the strand intermediate or horizontal.

On the other hand, in the case where the two deflectors 2, 2 ', are wide enough to allow a slight twist in the strand intermediate 1b, the axes of the supports 3, 3 ′ can be oriented to increase the angle of deflection between the generators input and output and therefore between axes 10a, 10c strands entering 1a and leaving 1c.

Furthermore, 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 ascending ramp or down.

The invention therefore gives multiple possibilities of arrangement of the successive sections of an installation of processing, in particular for the realization of a continuous line in an existing factory.

The reference signs inserted after the characteristics techniques mentioned in the claims, have only purpose of facilitating the understanding of these and not in no way limit the scope.

Claims (15)

Device for guiding a strip product (1) traveling along a longitudinal axis (10) and comprising at least two conical deflectors (2, 2 ') each having a narrow end (22, 22') and a wide end (23 , 23 ') and arranged head to tail, the narrow end (22) of one of the deflectors (2) being placed on the same side, relative to the axis (10) of the strip (1), as the 'wide end (23') of the other deflector (2 '), characterized in that each deflector (2, 2') comprises a fixed support (3, 3 ') on which are mounted, like satellites , a plurality of guide rollers (4, 4 ') distributed over an angular sector of deflection of the deflector (2, 2') and rotatably mounted around axes (40, 40 ') making the same angle (A) with a axis (30, 30 ') of the deflector (2, 2'), that the strip (1) is applied under tension to each deflector (2, 2 '), along a virtual conical surface (43) passing through a external generator (5) of heat that roller (4) and that the axes (30, 30 ') of the deflectors (2, 2') are oriented relative to the longitudinal axis (10) of travel of the strip (1) so that the latter comprises successively, in the direction of travel, an upstream part (1a) tangent to an input generator (5a) on a first deflector (2) and having an axis (10a) perpendicular to said input generator (5a), central part (1b) tangent, upstream to an outlet generator (5b) of the first deflector (2) and, downstream, to an inlet generator (5'a) on the second deflector (2 ' ) and having a longitudinal axis (10b) perpendicular to said generators, respectively of outlet (5b) and inlet (5'a), and a downstream part (1c) tangent to an outlet generator (5'b) of the second deflector (2 ') and having a longitudinal axis (10c) perpendicular to said output generator (5'b). Guide device according to claim 1, characterized in that the strip (1) is subjected to a tensile force determined as a function of the rigidity of the strip (1) so as to produce a tension application with elastic deformation of the strip (1) on all of the rollers (4) of each of the deflectors (2, 2 '), the head-to-tail mounting of said deflectors (2, 2') compensating for the differences in elongation, on each deflector (2, 2 '), between the two sides of the strip (1), on either side of the longitudinal axis (10) and determining a centering effect of the strip (1) with a progressive rotation of its longitudinal axis ( 10) capable of maintaining the perpendicularity thereof with the external generator (5, 5 ') of each of the rollers (4, 4') of the deflector (2, 2 '). Guide device according to claim 2, in which each part of the strip applied to a deflector has an internal edge (12) on the side of the thinned end (22) of the deflector and an external edge (13) on the side of the enlarged end (23), characterized in that the tensile force applied to the strip (1) is distributed over the width of the latter, progressively increasing from the internal edge (12) to the external edge (13), with a progressive elongation of the longitudinal fibers of the strip, so that the tangential speed of travel of each fiber, along an external generator (5) of each satellite roller (4), is substantially constant from one bank to the other. Guide device according to one of the preceding claims, characterized in that each roller (4, 4 ') of a deflector (2, 2') has a curved external profile, with a central part (44) of slightly larger diameter higher than the ends (45), and that the tensile force applied to the strip (1) determines self-centering of the strip (1) whose longitudinal axis (10) remains maintained in the central part (44) and orthogonal to an external generator (5, 5 ') bearing on each of the rollers (4, 4') of the deflector (2, 2 '). Guide device according to one of the preceding claims, characterized in that the strip (1) is applied to an angular sector of approximately one quadrant of each deflector (2, 2 '). Guide device according to one of the preceding claims, characterized in that it comprises an even number of deflectors (2, 2 ') associated in pairs, the two deflectors (2, 2') of each pair having the same angle (A) of inclination of the guide rollers (4, 4 '). Guide device according to one of the preceding claims, characterized in that the axes (30, 30 ') of two successive deflectors (2, 2') are oriented so that the output generator (5b) of the first deflector ( 2) and the input generator (5'a) on the second deflector (2 ') are parallel and placed in the same tangent plane common to the two deflectors (2, 2') in which the central part (1b) extends ) of the strip (1). Guide device according to one of claims 1 to 6, characterized in that the output generator (5b) of the first deflector (2) and the input generator (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 form a non-zero angle between them. Guide device according to one of the preceding claims, characterized in that the two deflectors (2, 2 ') bear on two opposite faces of the strip (1) and determine a lateral offset from the longitudinal axis (10c) of the downstream part (1c) of the strip (1) relative to that (10a) of the upstream part (1a), retaining the same general direction of travel (F). Guide device according to one of claims 1 to 8, characterized in that the two deflectors (2, 2 ') bear on the same face of the strip, and determine a lateral offset from the longitudinal axis (10c) of the downstream part (1c) of the strip (1) relative to that (10a) of the upstream part (1a), with an inversion of the direction of travel (F). Guide device according to one of claims 9 and 10, characterized in that the two deflectors (2, 2 ') are arranged so that the inlet generator (5a) on the first deflector (2) and the generator exit (5'b) of the second deflector (2 ') are placed in two parallel planes of travel, respectively of the upstream part (1a) and the downstream part (1c) of the strip (1) and that the longitudinal axes (10a, 10c) of said upstream (1a) and downstream (1c) parts are spaced, at said inlet (5a) and outlet (5'b) generators, by a distance D = H tg A, A being the angle at the top of each deflector (2, 2 ') and H the distance between the two planes of travel, respectively upstream and downstream of the strip. Guide device according to one of claims 9, 10 and 11, characterized in that the two deflectors (2, 2 ') are arranged so that the output generator (5b) of the first deflector (2) is parallel to the input generator (5'a) on the second deflector (2 '), the central part (1b) of the strip (1) being planar. Guide device according to claim 12, characterized in that the inlet generator (5a) on the first deflector (2) and the outlet generator (5'b) of the second deflector (2 ') are parallel to the same plane and make an angle between them equal to 2A ', A' being the projection of the angle at the top (A) of each deflector (2, 2 ') on said plane of the generatrices, the longitudinal median planes of the upstream parts (1a ) and downstream (1b) of the strip (1) making between them the same angle (2A '). Guide device according to one of Claims 9 to 11, characterized in that the two deflectors (2, 2 ') are arranged so that the inlet (5a) and outlet (5'b) generators, respectively first (2) and second deflector (2 ') are placed in parallel planes and make between them a non-zero angle, the longitudinal median planes of the upstream (1a) and downstream (1c) parts of the strip being perpendicular to said input (5a) and output (5'b) generators and making the same non-zero angle between them. Guide device according to claim 11, characterized in that the generators respectively of inlet (5a) on the first deflector (2) and outlet (5'b) of the second deflector (2 ') are parallel and that the part upstream (1a) and the downstream part (1c) of the strip (1) are centered, respectively, on two longitudinal median planes parallel to each other and spaced by the distance D = H tg A.

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