EP1448322B1 - Method and device for stabilizing high-speed unwinding of a strip product - Google Patents

Abstract

The invention relates to a method and a device for stabilizing high speed running along a longitudinal direction, of a band ( 4 ) applied on a rotary surface ( 3 ) and along which a portion of the surrounding air forms a boundary layer ( 43 ) trapped with the band ( 4 ). According to the invention, a deflecting member ( 5 ) is placed in the dihedron (G) between the band ( 4 ) and the rotary surface ( 3 ). Said deflecting member ( 5 ) has a face ( 50 ) directed toward the band which is tilted with respect thereto and is fitted with at least one orifice ( 55 ) emerging into an inner space ( 51 ) provided inside said deflecting member ( 5 ) and connected to an outer zone. Thus, said tilted face ( 50 ) forms, with the inner face ( 41 ) of the band ( 4 ), a convergent (C<SUB>1</SUB>) wherein the pressure increases with respect to the pressure in the inner space ( 51 ) and the differential pressure determines the exhaust of a certain air flow rate through the orifice ( 55 ) and the separation of the remaining portion of the air mass trapped in the boundary layer ( 43 ).

Description

The subject of the invention is a method and a device for stabilizing and guiding a product traveling at high speed in a longitudinal direction, in particular in a cold rolling plant for metal strips, more particularly thin sheets of foil. aluminum.

A cold rolling plant of a strip metal product generally comprises one or more rolling mill stands each comprising two working rolls resting on support rolls and associated with means for controlling the movement of the roll. the band between the working rolls. Typically, the web runs from a spool on an upstream side of the cage (s) and coils on a downstream winder. The installation also comprises numerous additional members such as means for introducing the strip into the rolling mill stands, means for adjusting the rotational speeds of the various members and a certain number of deflection rollers that can have a position. adjustable and on which the strip is applied so as to be guided along a determined path.

Taking into account the criteria of productivity, production and profitability, a facility for rolling very thin sheets, in particular of aluminum, generally comprises a single roll-to-roll rolling mill between a reel and a rewinder. .

Conventionally, a roll stand comprises two spaced apart columns between which are mounted a set of rolls, for example, in the case of a quarto cage, two working rolls respectively associated with two support rolls. Each cylinder is rotatably mounted at its ends on bearings carried by chocks slidably mounted between the column posts of the cage and clamping means resting on the chocks of the support cylinders make it possible to achieve the desired thickness reduction on the rolled strip.

It is thus possible to obtain a very thin thickness and, for example, in the case of aluminum foils, the thickness range can range from 3 to 300 micrometers. The equipment of the installation must, of course, be adapted to such fine thicknesses, in particular for winding the coil.

For example, the figure 1 schematically represents a rolling installation of an aluminum foil comprising a roll stand A placed between a unrolling machine D carrying a reel B ₁ and a reel E on which a roll B ₂ is formed after passing the product M between the rolls of working of the rolling mill A.

On its path between the unwinder and the winder, the belt M is guided by a certain number of deflection rollers D. In particular, a roller D ₁ of flatness measurement is placed downstream of the cage A in order to detect any defects to be corrected by acting on means for adjusting the rolling conditions. In addition, a feed roller D ₂ , adjustable level, adjusts the winding angle of the band on the flatness roller D ₁ . This roller D ₂ can be spread upwards to facilitate the engagement of the strip on the winder E.

Of course, the installation of the figure 1 is shown only by way of example, other types of installation that can be used. For example, it is possible to carry out tandem rolling in a rolling mill comprising several cages successively placed in the path of the strip in order to achieve a gradual reduction in thickness or alternatively reversible rolling carried out alternately in one direction and in the other, the rolling mill. being associated with two winders that work alternately in unwinding and winding. On the other hand, the rolled strip can undergo a number of treatments, either upstream or downstream of the rolling and, in the most recent installations, it is sought to achieve as much as possible these various treatments in a continuous line.

However, in the case of rolling thin sheets of aluminum, the small thickness of the rolled metal strip causes a particular operation of the installation because the length of a coil can be several tens of thousands of meters and the duration a rolling pass can therefore reach several hours. Under these conditions, it is not a question of reversible rolling.

On the other hand, it is not interesting, as for other installations, to produce continuous assemblies because the ratio of the rolling time to the replacement time of the coils is very large.

In practice, the only parameter on which one can act effectively to increase productivity is the speed of rolling and one has therefore sought to improve the performance of the facilities. In particular, for the rolling of thin sheets of aluminum, it is now possible to achieve very high rolling speeds, for example of the order of 2000 meters per minute, speeds of 3000 meters per minute are even envisaged.

However, at such high speeds, it becomes very difficult to ensure the stability of the web guide which has a tendency to float on the baffle rollers, in particular the loading roller, which can result in defects in the machine. coil winding. It is therefore necessary, in installations operating at very high speed, to immediately detect a possible defect in guiding so as to reduce the speed to a level making it possible to restore the stability of the scrolling.

But other disadvantages arise, for the coil winding, at high speed, of a metal strip.

It is known, in fact, that, to be wound in well-joined turns, the strip must be kept under tension by the winder E. However, the traction that can be applied to an aluminum foil is small and, even with a typical specific traction of the order of 3 to 5 kg / mm ² the traction force which ensures the application of the strip on the wound coil can be only a few tens of kg and does not exceed, in practice, 200 kg.

However, it has been observed that, at high speed, such traction is too low to ensure proper application of the turns on one another and this results in an increase in the overall diameter of the coil.

This phenomenon, called expansion, distorts the usual calculations of tape length and coil diameter.

To overcome this disadvantage, it has been proposed to equip the winder with an additional roller said roller ironer which is mounted on an articulated arm and bears, from the outside, on the strip during winding.

However, it is not desirable to increase the number of rolls or devices in contact with the web as this results in a risk of product marking.

The object of the invention is to remedy such disadvantages by means of a method and a device making it possible to ensure the stability of the scrolling and the winding of the strip, even at very high rolling speeds and, thus, significantly increase the productivity of a plant without any significant change in it.

In order to solve this problem, the applicant company has studied in detail the running conditions of a high speed band, in particular for rolling an aluminum foil, and it has become apparent that the difficulties encountered in guiding the band, the measure of flatness and the coil winding after rolling, could all be explained by the fact that from a certain speed of movement, a part of the air being in the vicinity of the strip, could be driven with it, by abutting the obstacles placed in the path of the band such as guide rollers or work rolls.

In the case of work rolls which are rotated and whose tightening determines the reduction in thickness, this air entrainment does not matter.

On the other hand, in the case of a deflector roll on which the strip is simply applied under tension, the air entrainment with the strip causes, upstream of the zone of application, a dynamic pressure which, by a wedge effect , is able to slightly lift the band. This is particularly noticeable in the case of rolling thin sheets of aluminum because, as we have seen above, the tensile force that determines the application of the strip on the roll, is necessarily limited.

A cushion of air is formed between the sheet and the roll, which, in the case of a deflector roll or anger, may disturb the guiding the band, the latter being slightly raised and can therefore move laterally.

Such a phenomenon of forming an air cushion by air entrainment between a high speed traveling band and a baffle roll or a spool had already been observed in the paper industry.

To avoid this inconvenience, it was proposed in the document DE-A-19839916 to place in the dihedron formed upstream of the nip, a flexible blade which enters the gap between the inner face of the strip and the coil and brakes the air flow, the pressure upstream of the line of contact contact being thus diminished.

It has also been observed, in the case of an offset printing machine chilling roll, that the paper web can cause a certain amount of air which may enter between the web and the roll, the resulting air cushion. constituting an insulating layer which decreases the cooling effect.

To avoid this, it was proposed in the document EP-A-0812695 placing in the dihedral upstream between the belt and the roller a suction device in the form of a hollow box connected to a suction fan and having a plane face and a curved face, respectively parallel to the belt and to the roller, which converge up to at one end thinned along which is formed a slot which opens out between the strip and the roller, close to the nip. The air in this part is thus sucked by this slot and the pressure upstream of the nip is reduced, the band being thus maintained applied to the roll, without risk of lifting.

Having found that the various disadvantages mentioned above in the case of the very high speed rolling of metal strips resulted from the air entrainment effect with the strip, it was suggested that the devices previously provided in In order to avoid this disadvantage, the paper industry could advantageously be used for the high-speed rolling of metal strips.

It has appeared, however, that the devices known previously and realizing, either a simple braking or a suction air entrained, would be insufficiently effective or even harmful, in the case of a metal strip, particularly aluminum.

Indeed, as indicated above, due to the very thin thickness of the aluminum foils, the pulling force that can be applied is relatively low and a suction nozzle placed near the The line of contact between the belt and the reel could deflect the belt which, while sticking to the suction element, could be damaged or even torn.

The aerodynamic conditions of the air circulation have been studied in detail to develop a device which, without requiring air suction, which could deflect the strip, produces a laminar phenomenon acting solely on the air boundary layer. trained with the band.

The invention therefore relates generally to a method and a device for stabilizing the high-speed movement, in a longitudinal direction of a band coming from a contact line, on at least one angular sector of a rotating surface of revolution about an axis transverse to the running direction, and connecting tangentially to the rotating surface forming, on the upstream side in the direction of travel, a dihedral limited on one side by an outer face of the rotating surface and the other, by an inner face of the strip along which part of the ambient air forms a boundary layer driven with the strip towards the nip, a deflection member being placed in the dihedral so as to modify the conditions of circulation of the air entrained with the band, said deflection member having a first side facing the inner face of the band and a second side facing towards the outer face of the rotating surface.

According to the invention, at least the first face of the deflection member is inclined towards the inner face of the strip, in the running direction thereof and is provided with at least one orifice opening into an internal space formed inside the deflection member and connected to an outer zone, said inclined face forming, with the inner face of the strip, a convergent in which the pressure increases with respect to the pressure in the internal space), the difference pressure determining the evacuation, through the orifice of the inclined face and the internal space, a certain air flow and the recess of the remaining part of the air mass constituting the boundary layer driven with the band .

Particularly advantageously, the internal space of the deflection member is not connected to a suction fan but simply to an external zone at atmospheric pressure, the circulation of the air thus occurring naturally, without any real suction, at the level of the deflection member.

Preferably, the second face of the deflection member, facing the rotating surface, is inclined relative thereto, so as to form a convergent determining a pressure increase of the air entrained with the rotating surface, of which a portion is discharged to the outer zone connected to the internal space through at least one orifice in said second face.

Such a stabilizing device according to the invention can be applied either to a baffle roll with a cylindrical profile determining a change of direction of the strip running plane, or to the coil winding of the strip in order to avoid the air entrainment between the superimposed turns.

In the case of a coil winding, the air deflection member consists of a hollow section, mounted on an adjustable support means depending on the diameter of the coil, so as to maintain the body of deviation in an optimal position relative to the inner face of the strip, as and when winding thereof in a coil.

Preferably, this support arm of the air deflection member has a variable length and is rotatably mounted about an axis parallel to the axis of the coil, said arm being associated with means for adjusting its sound. orientation and its length depending on the diameter of the coil, for the positioning of the profiled member inside the dihedral upstream.

Advantageously, the adjustable support means of the deflection member is mounted on a wrapper associated with the spool to facilitate the beginning of winding of the strip, the support means being folded in the template of the wrapper when it is in winding start position and unfolded after winding a few turns and spacing of the wrapper, so as to place the deflection member near the nip , at the end of the dihedral upstream.

The invention also covers the use, in a rolling installation of metal strips, in particular of aluminum, of such a stabilizing device which can be placed upstream of at least one deflection roll, in order to ensure direct application of the strip on the roll without the interposition of a layer of air. This deflector roll may advantageously be a flatness measuring roller, the device thus making it possible to avoid disturbance of the measurement by air entrainment between the strip and the roll.

But the invention can also be advantageously used for winding the rolled strip on a reel placed at the end of the line, the stabilizing device then being placed upstream of the contact line with the coil already wound in order to avoid the There is no air entrainment between the turns and to ensure the guiding stability of the band during the winding.

Other advantageous features are mentioned in the claims.

• La figure 1 est une vue schématique d'une installation de laminage de feuille mince.
• La figure 2 est une vue en coupe transversale, à échelle agrandie, d'un organe de déviation de l'air selon l'invention, appliqué à l'enroulement d'une bobine.
• La figure 3 montre, en élévation, l'ensemble du dispositif équipant une enrouleuse placée à la sortie d'un laminoir.

But the invention will be better understood by the following description of some embodiments given by way of example and shown in the accompanying drawings.

• The figure 1 is a schematic view of a thin-sheet rolling mill.
• The figure 2 is a cross-sectional view, on an enlarged scale, of an air deflection member according to the invention, applied to the winding of a coil.
• The figure 3 shows, in elevation, the entire device equipping a winder placed at the exit of a rolling mill.

As noted above, the figure 1 shows, schematically, the assembly of a rolling plant of an aluminum sheet-which takes place from a coil B ₁ and is rewound at the exit of the rolling mill A to form a new coil B ₂ . The band M is guided by a plurality of deflection rollers which provide the scroll stability, in particular, a flatness measuring roll D ₁ and an embossing roll D ₂ .

In addition, a looper D ₃ consists of two fixed rollers flanking an adjustable level central roll, used to regulate the tension-upstream of mill A.

The rolling mill A schematically represented on the figure 1 and more in detail on the figure 3 , can be, for example, of the quarto type comprising two working rolls 1, 1 'supported respectively on support cylinders 11, 11' and each rotating around a shaft carried at its ends by chocks respectively 12, 12 ', 13, 13' which are slidably mounted along vertical guide faces 14 provided on two fixed columns 10 constituting the roll stand.

Downstream of the rolling mill, the strip passes successively on a roll 15 of flatness measurement and on a loading roller 16 which is slidably mounted on the two columns 10 of the cage and whose position can be adjusted by a jack 17 according to the the nature of the metal and the thickness of the strip in order to adjust the angle of application on the flatness roller 15.

The winder E on which the rolled coil B _{2 is formed} comprises, in a conventional manner, an expandable mandrel 2 mounted cantilevered on a frame 21 and driven in rotation about its axis 20. In known manner, as the show the figures 1 and 3 , the winder E is associated with a wrapper F mounted on a frame 22 articulated on the columns 10 of the rolling mill about an axis 23 parallel to the running plane of the band M and which can rotate, under the action of a means not shown, between a raised position and a remote position. The wrapper F comprises an open portion 24 which, in the raised position of the frame 22, is engaged on the mandrel 2 of the winder E.

At the beginning of the rolling, the loading roller 16 is raised by the jack 17 in a spaced position 16 'allowing the passage of the head M ₁ of the band M- and its engagement on the mandrel 2. Known means, provided in the part 24 of the wrapper F and not shown in the figure, support the head of the band for facilitate the beginning of the winding in superimposed turns. When the number of turns is sufficient to support the traction of the band, the wrapper F is removed by the jack 24 to move to the position shown on the figure 3 .

Thus, on the mandrel 2, a coil 3 is formed whose diameter increases progressively, as indicated on FIG. figure 3 .

The band M thus connects tangentially to the coil 3, along a line of contact 30 parallel to the axis 20 of the mandrel 2, forming a dihedral angle G with the outer face 31 of the coil 3 facing the upstream relative to the direction of scrolling.

It is known that the high-speed movement, parallel to itself, of a thin surface in a fluid causes, by friction, entrainment of the molecules of the fluid, for example the ambient air, being in the immediate vicinity of the strip. movement.

On the figure 2 for example, which shows on an enlarged scale, the winding area of the band M on the coil 3, there is shown, on the right, the variation diagram of the speed vector (U) of the air which, starting from a distance (e) of the inner face 41 of the band 4 goes from a zero value to the value (V) of the running speed of the band 4, remaining parallel to itself. There is thus, along the inner face 41 of the strip 4 facing the coil 3, a moving air thickness 43 called boundary layer in which a laminar flow occurs at a speed which increases progressively, approaching the band 4, to reach the speed thereof along its inner face 41. It is the same along the outer face 42 of the strip.

This boundary layer 43 accompanies the band 4 in its movement and abuts against the coil 3, the outer face 31 facing upstream, that is to say the opposite of the direction of travel, shape, with the inner face 41 of the band 4, a dihedron G which converges towards a line of contact 30 of the band 4 with the last wound coil 32.

This blocking, upstream of the contact line 30, of the air entrained along the face 41 of the strip determines a pressure increase which can cause a slight uplift of the strip 4 and the introduction a thin layer of air between the inner face 41 of the strip 4 and the coil 3.

The idea of the invention is to achieve aerodynamic conditions of air circulation in the upstream dihedron G for detaching the boundary layer 43 upstream of the nip 30.

This recess of the boundary layer 43 is obtained by discharging outwardly a portion of the air flow entrained with the strip, by means of a deflection member 5 placed in the upstream dihedron G and extending between the inner face 41 of the strip and the outer face 31 of the coil, parallel to the contact line 30. This deflection member 5 consists of a hollow section having at least one face 50 facing the inner face 41 of the strip 4 and inclined relative thereto, in the direction of travel, so as to form a convergent C ₁ whose section decreases gradually causing an increase in pressure of the air entrained with the band in the boundary layer 43.

This inclined face 50 is provided with a plurality of slot-shaped orifices 55 which open into the internal space 51 formed inside the hollow profile 5. The latter is closed at its ends and provided with an orifice connected by a pipe 53 to an external zone 54 located, for example, at atmospheric pressure.

The increase, by wedge effect, of the pressure in the convergent C ₁ thus determines the passage in the slots 55 of a portion of the air entrained in the boundary layer 43 which escapes via the pipe 53 to the zone at lower pressure 54. The flow of air entrained towards the contact line 30 decreases and the boundary layer 43 is thus detached from the inner face 41 of the band 4 to catch on the inclined face 50 of the deflection 5 forming a laminar flow stream which escapes through the slot 55 and the conduit 53.

The pressure of the entrained air only increases to the downstream end of the deflection member 5 and then decreases. The pressure being lower upstream of the contact line 30, the air is not likely to penetrate between the last turn 32 of the coil 3 and the turn 33 being formed.

In the preferred embodiment shown in the figure 2 the second face 50 'of the deflection member 5 facing the winding surface 3 is also inclined with respect thereto so as to form a second convergent C ₂ which progressively increases the pressure of the air entrained by the rotation of the coil 3. This second inclined face 50 'is also provided with a slot 55' which opens into the internal space 51 of the hollow section 5.

There is thus a natural circulation along the two faces 50, 50 'of the hollow section 5 which decreases the pressure at the end of the dihedron G, upstream of the contact line 30, without any suction of the air at the end. end 52 of the deflection member 5 which enters the dihedron G between the inner face 41 of the strip and the face 31 of the coil 3. It should be noted, moreover, that it is unnecessary to taper the end 52 of the deflection member 5 which must simply limit the two convergent C ₁ , C ₂ to determine the laminar flow of air along the two inclined faces 50, 50 'without extending towards the line contact 30.

To determine this laminar flow, it is sufficient, normally, that the pipe 53 simply emerges in a calm zone where the speed of the air is zero and the pressure equal to the atmospheric pressure.

Indeed, the pressure difference between the two convergent C ₁ , C ₂ and the outlet 54 of the exhaust pipe 53 determines a natural circulation of the air passing through the slots 55, 55 '.

However, if the width of the strip and, therefore, the length of the profile 5 and the length of the exhaust pipe 55 are too great and may result in a high pressure drop, given the dynamic overpressure due at the rotational speed of the coil, it may be preferable to connect the exhaust pipe 53 to a suction device. However, it is simply intended to compensate the pressure drop in the circuit and not to achieve a real aspiration of air into the dihedral top downstream of the deflection member 5. This avoids the risk deterioration of the band by application thereof on the downstream end 52 of the deflection member 5, even in the case where the band is subjected to a relatively low traction force.

The shape of the hollow profile 5, in particular the profile and the inclination of the faces 50, 50 'and their optimal positioning with respect to the band to be wound 4 and the contact line 30 can be determined empirically or by calculation so as to obtain the desired effect, by studying the conditions of air circulation taking into account the speed of travel v of the band 4, and pressure losses in the section 5 and the evacuation circuit.

On the other hand, the diameter of the spool and, consequently, the position of the contact line 30 and the orientation of the strip 4 obviously vary, during the winding. It is therefore necessary to maintain permanently the position of the deflection member 5 inside the dihedron G and, for this, it is advantageous to use the device shown in detail on the figure 3 .

As indicated above, at the exit of the rolling mill, the rolled strip M passes over two baffle rollers, respectively, a roll 15 of flatness measurement, placed at the gap between the working rolls 1, 1 and an embossing roller 16 which is slidably mounted along guide rails provided on the columns 10 of the rolling mill and whose level can be adjusted by means of a jack 17 according to the thickness and the nature of the strip. laminated, the loading roller 16 being raised in a high position 16 'at the beginning of rolling to facilitate the passage of the head of the band M and its engagement on the mandrel 2 of the winder E. On the other hand, it is associated with a wrapper F mounted on a frame 22 which can rotate about an axis 23 between a raised position, shown on the figure 1 , for which the wrapper is engaged on the mandrel 2 to facilitate starting the winding and a lowered position, shown on the figure 3 , for which the wrapper is spaced from the mandrel 2 to allow the winding of the strip and the formation of the coil 3. This increases in diameter as the winding and the contact line 30 of the band M with the coil 3 thus deviates from the winding axis 20 following a curve 34 shown in dashed line on the figure 3 .

As indicated, the deflection member 5 must follow the increase in diameter of the coil while remaining in a optimal position inside the dihedron G to allow the evacuation of the entrained air in the boundary layer.

The deflection member 5 must follow a curve 34 'similar to the path 34 of the contact line 30 away, however, slightly from it to account for the fact that the dihedron G closes gradually as and when as the winding progresses.

It is therefore possible to determine, by calculation or empirically, the position of the deflection member 5 as a function of the diameter of the coil 3.

To allow the progressive displacement of the deflection member 5, it is mounted at the end of a support 6 whose orientation and length may vary depending on the diameter of the coil 3.

As shown in figure 3 , the support 6 may consist of two spaced arms arranged at both ends of the section 5 constituting the deflection member and rotatable about a shaft 60 articulated at its ends on two sides of the frame 22 of the wrapper F .

Each arm 6 carries the body of a jack 61 whose rod 62 is provided, at its end, with a piece 63 for attaching the hollow section 5. The latter is connected by a hose to a pipework attached to the arm support 6 for the evacuation of air sucked by the slots 55, 55 '.

The frame 22 of the wrapper F also carries a member 7 for controlling the rotation of the support 6, consisting of at least one lever hinged about an axis 70 and carrying a toothed sector 71 which meshes with a pinion toothed 64 integral in rotation with one of the two arms which constitute the support 6 and are secured in rotation. The other leg of the lever 7 is articulated on the rod of a jack 72 bearing on the frame 22 and which thus controls the rotation of the support 6 between a retracted position 6a, and a spaced position 6b corresponding to the maximum diameter of the coil 3.

In the retracted position 6a which is also represented on the figure 1 , the profile 5 and its two support arms are folded into the frame of the frame 22 of the wrapper F and therefore do not interfere with the introduction of the latter on the mandrel 2 for starting the winding. -

After winding a number of turns sufficient to place the band M under the traction necessary for rolling, the control member 7 rotates the two arms of the support 6 to a position 6c for which the axis of the jack 61 is substantially tangent to the coil at the beginning of winding and the rod of the cylinder is advanced so as to place the deflection member in the desired position 5c near the inner face of the strip 4. The speed of rotation of the mandrel 2 is then increased to the level corresponding to the high speed rolling of the strip 4.

By hydraulic means that are easy to design, the cylinders 72 for controlling the rotation of the arm 6 and 61 for adjusting the radial position of the deflection member 5 are slaved to the variation in the diameter of the spool 3 so as to follow the curve 34 'remaining at the desired distance from the inner face 41 of the strip 4 and as close as possible to the nip 30.

For this purpose, the cylinders 61 and 72 are equipped with position sensors and controlled by a suitable circuit so as to adjust accurately the position of the profile 5 as a function of the diameter of the coil which is determined itself from the number of turns of the mandrel 2 taking into account the thickness of the strip 4.

The installation is equipped for this purpose with sensors and calculation means that can be programmed to determine the profile of the curve 34 'followed by the deflection member 5.

Of course, it is also necessary to take into account the position of the loading roller 16 which determines the angle of application of the web 4 on the reel 3 and the position of the nip 30.

When the diameter of the coil reaches its maximum value, the arm 6 is in the position 6b, the rod 62 of the cylinder being completely retracted.

After the end of the winding, the spool 3 is removed and the rotary support 6 is folded into its position 6a inside the jig of the wrapper F. It can then be raised to engage the mandrel 2, to begin winding a new coil.

The invention which has just been described in the case of a reel winder can also be applied to a baffle roll, for example For example, the flatness measuring roller 15. The band M is then applied under tension on an angular sector of the roll 15 and the deflection member 5 is placed, as previously, in the dihedron G between the band 4 in progress. winding and the part of the surface of the roller 15 placed upstream of the contact line 30.

Since the baffle roll 15 has a constant diameter, the deflection member 5 remains in the same position relative to the roll and can be placed, for example, at the end of a fixed support arm.

As previously, the deflection member 5 may be a hollow section opening into a pipe 53 for discharging, outwards, a part of the air entrained in the boundary layer 43 in order to reduce the dynamic pressure at the end of the flow. end of the dihedron G, at the level of the contact line 30. This avoids the formation of an air cushion which, on the one hand, could cause a lateral flutter of the band on the baffle roll and other in the case of a flatness roller, could disturb the measurement.

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 (17)

1. A method for stabilising high speed running of a band-type product along a longitudinal direction, the band (4) being applied from a line of contact (30), over at least one angular sector of rotary revolution surface (3) around an axis (20) crosswise to the running direction, and connecting tangentially to the rotary surface (3) while forming, on the upstream side in the running direction, a dihedron (G) delineated, on one side by an outer face (31) of the rotary surface (3) and on the other side, by an inner face (41) of the band (4) along which a portion of the surrounding air forms a boundary layer (43) swept along by the band (4) toward the line of contact (30), a method wherein the conditions of circulation of the air in the upstream dihedron (G) are modified by means of a hollow deflecting member (5) having a first face (50) directed toward the inner face (41) of the band (4) and a second face (50') directed toward the outer face (31) of the rotary surface (3),
   characterised in that the first face (50) of the deflecting member (5) is tilted toward the inner face (41) of the band (4), in the running direction thereof, in order to decrease gradually the passageway section of the air swept by the band, along the inner face (41) thereof, by causing an increase in the pressure of the air trapped in the convergent (C₁) thus formed, with respect to the pressure prevailing inside the hollow deflecting member (5) which communicates, on the one hand with the convergent C₁ by at least one orifice (55) provided in said tilted face (50) and, on the other hand, with the outside, the differential pressure thus created determining the exhaust toward the outside of a certain air flow rate passing through said orifice (55) and the separation of the remaining portion of the air mass constituting the boundary layer (43).
2. A method for stabilising a band according to claim 1, characterised in that, the second face (50') of the deflecting member (5) is tilted toward the rotary surface (3), in the rotary direction thereof, in order to generate, by a converging effect, an increase in pressure along said second face (50') and the exhaust of a portion of the air swept by the rotary surface (3), toward a lower pressure zone, passing through at least one orifice (55') provided in said second face (50').
3. A device for stabilising high speed running along a longitudinal direction, of a band (4) being applied from a line of contact (30), over at least one angular sector rotary revolution surface (3) around an axis (20) crosswise to the running direction, and connecting tangentially to the rotary surface (3) while forming, on the upstream side in the running direction, a dihedron (G) delineated, on one side by an outer face (31) of the rotary surface (3) and on the other side, by an inner face (41) of the band (4) along which a portion of the surrounding air forms a boundary layer (43) swept along by the band (4) toward the line of contact (30), a deflecting member (5) being placed in the dihedron (G) in order to modify the conditions of circulation of the air swept by the band (4), said deflecting member (5) having a first face (50) directed toward the inner face (41) of the band (4) and a second face (50') directed toward the outer face (31) of the rotary surface (3),
   characterised in that, at least the first face (50) of the deflecting member (5) is tilted toward the inner face (41) of the band (4), in the running direction thereof and is fitted with at least one orifice (55) emerging into an inner space (51) provided inside the deflecting member (5) and connected to an outer zone, said tilted face (50) forming, with the inner face (41) of the band (4), a convergent (C₁) wherein the pressure increases with respect to the pressure in the inner space (51), the differential pressure determining the exhaust, through the orifice (55) and the inner space (51), of a certain amount of air and the separation of the remaining portion of the air mass trapped in the boundary layer (43).
4. A device according to claim 5, characterised in that the inner space (51) of the hollow deflecting member (5) is connected to an outer zone (54) situated outside the upstream dihedron (G), at a pressure lower than the pressure (P) in the convergent (C₁) at the inlet orifice (55).
5. A device according to claim 4, characterised in that the inner space (51) of the deflecting member (5) is connected to an outer zone situated at atmospheric pressure.
6. A device according to any of the claims 3, 4, 5, characterised in that the second face (50') of the deflecting member (5), directed toward the rotary surface (3), is tilted with respect thereto, in order to form a convergent determining an increase in pressure of the air swept by the rotary surface (3), whereof a portion is evacuated toward the outer zone (54) connected to the inner space (51) passing through at least one orifice (55') provided in said second face (50').
7. A stabilisation device according to any of the claims 3 to 6, characterised in that the revolution surface whereon is applied the band is a deflecting roll (D) with a cylindrical profile, determining a change in direction of the running plane of the band (M).
8. A stabilisation device according to any of the claims 3 to 6, characterised in that it is arranged upstream of a spool (3) for winding the band into superimposed spires, in order to prevent the trapping of air between the spires (31, 32).
9. A stabilisation device according to claim 8, characterised in that the deflecting member (5) of the air consists of a hollow profile, installed on a supporting means (6) adjustable relative to the diameter of the spool (3), in order to maintain the deflecting member (5) in optimum position with respect to the inner face (41) of the band (4), as the latter is wound gradually into a spool.
10. A device according to claim 9, characterised in that the profiled deflecting member (5) of the air is installed at the end of at least one supporting arm (6) having a variable length and rotatably mounted around an axis (60) parallel to the axis (20) of the spool (3), said arm (6) being associate with means for adjusting (7) its orientation and (61) its length, relative to the diameter of the spool (3), to position the profiled member (5) inside the upstream dihedron (G).
11. A device according to claim 10, characterised in that the supporting arm (6) is rotatably mounted around an axis parallel to the axis of the spool and carries a hydraulic actuator (61) having a first element attached to the arm (6) and a second element (62) slidingly mounted on the first element and carrying the deflecting member (5), the position of the second element (62) with respect to the first (61) being adjusted relative to the diameter of the spool (3).
12. A device according to any of the claims 10 and 11, characterised in that the means for adjusting the orientation of the supporting arm comprises a lever (7) rotatably connected to the supporting arm (6) and whereof the angular position is adjusted by a hydraulic actuator (72).
13. A device according to claim 12, characterised in that the lever (7) is rotatably mounted around an axis (70) parallel to that (60) of the supporting arm (6) and is interconnected with a toothed sector (71) with a circular profile centred round the axis (70) of the lever (7) of the crank and engaging a toothed wheel (64) rotatably interconnected with the supporting arm (6).
14. A device according to any of the claims 9 to 13, characterised in that the supporting means (6) for adjusting the deflecting member is installed on a wrapper (F) associated with the spool (3) for easier beginning of the winding thereof, the supporting means (6) being folded in the jig of the wrapper (F) when the latter is at the beginning of the winding position and unfolded after winding a few spires and spacing the wrapper apart (F), in order to place the deflecting member (5) close to the band (M), in the upstream dihedron (G).
15. A use of a stabilisation device according to any of the claims 3 to 7, in a rolling mill for a metal band, the stabilisation device (5) being arranged upstream of at least one deflecting roll (D) placed on the path of the band, in order to ensure direct application of the band on the roll without interposition of an air layer capable of disturbing the guiding of the band.
16. A use of a stabilisation device according to any of the claims 6 to 15, in a rolling mill for a metal band including at least one rolling stand (10) associated with a roll (15) for measuring the flatness whereon the band is applied under traction, the stabilisation device (5) being arranged upstream of the flatness roll (15) in order to prevent the trapping, between the band (M) and the roll (15), of an air layer capable of disturbing the flatness measurement.
17. A use of a stabilisation device according to any of the claims 8 to 14, in a rolling mill for a metal band (M) including a winder (E) placed at the end of the line, the stabilisation device (5) being placed in the dihedron (G) upstream of the line of contact (30) with the band (4) already wound in order to prevent the trapping of air between the spires (31, 32) and to ensure guiding stability of the band (4) during the winding process.

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