FR2635339A1 - FREE SPINNING TYPE SPINNING PROCESS, AND DEVICE FOR CARRYING OUT SAID METHOD - Google Patents

Abstract

The invention relates to a method and a device for the open end type spinning, improved in order to obtain a good quality yarn due to a uniform torsion throughout the yarn cross-section. By means of a rotary drum (20) or similar member, the fibers taken from a feed rove (11) are longitudinally driven up to the vicinity of a yarn forming area defined by a sucking slot (32) on a first air permeable surface (30) which is preferably a rotary disc. The fibers are then transversally displaced, while remaining parallel to each other, up to the point of the yarn being formed. This point rolls without sliding so that it is not subjected to any torsion. The yarn (1) is then twisted by progressive suppression of the rotation speed while rolling without sliding on a second air permeable surface (disc 31) opposite to a second sucking slot (33). The method is applicable to the fabrication of fine or coarse textile yarns.

Description

SPINNING METHOD OF THE FREE TIP TYPE, AND DEVICE
TO IMPLEMENT THIS PROCESS
The invention relates to a spinning method of the loose-end type, in which fibers or bundles of fibers are taken cyclically from a wick of fibers, these fibers are drawn close to a yarn-forming area defined by a suction slit on a surface permeable to air, moving in front of this slit, the fibers are deposited on the formation area near a conical point of the wire, this point is rotated by rolling on the surface permeable to air, and the wire thus formed is simultaneously driven in the longitudinal direction. The invention also relates to a device for implementing this method.

The current development of processes and machines with loose ends, commonly called "open end", proves the interest that there is to manufacture continuously and at high speed a large coil of wire by initially dissociating the fibers of the food wick and by placing them around the wire being formed. There are several types of "open end" processes.

The most common method uses a rotating bowl which collects in the interior of its throat fibers that have been torn from the wick and which arrive in the rain in the bowl. After priming, the wire is pulled through the center of the bowl and it picks up as the circular deposit of fibers formed in said groove. The fibers of this deposit are generally very well parallelized, but the method of picking up the fibers by the wire following an elbow, without drawing possible, and the fact that incoming fibers necessarily fall on the pickup point, are reasons which make that the structure of the thread thus obtained and its solidity cannot be as good as that of a conventional thread. The development of this process is nevertheless very important, but for the moment it is not applicable to fine threads and it requires, in the wire section, a number of fibers systematically higher than for a conventional wire. In addition, it only applies with short fibers.

More recently, attempts have been made, in so-called "open end friction" methods, to rotate in fiber bundles previously torn from the food wick, by means of a thin air permeable surface, moving above a stationary suction slot which defines the area of formation of the wire on the permeable surface. Different processes of this kind are described in a publication by 3. Lünenschloss and K.-J. Brockmanns "Mechanisms of
OE-friction spinning ", International Textile Bulletin, Yarn forming 3j85.

This technique has mainly developed in the spinning of carded wool, because the fibers used are generally short and the yarns requested quite large, and their quality does not need to be perfect.

On the other hand, this technique has practically not yet been successful for quality yarns, with short or long fibers. In fact, when you defiber and transport the fibers freely to the training area, you do not have a good handle on how they arrive at the end of the wire which rotates at high speed. The twist pitch thus formed can be different depending on whether one end of the fiber or the other is taken first by the wire. In addition, the rotational drive of the conical tip of the nascent wire makes the tip of the tip rotate faster than its base, because of its smaller radius, that is to say that the torsion is much stronger in the core of the wire than at its periphery.

There is therefore in the section of the wire a non-uniform distribution of the longitudinal elasticity and significant differences in tensile stresses when the wire is stretched, which significantly lowers the resistance of the wire.

In addition, the torsional reaction forces in the tip of the emerging wire cause friction on the permeable surface, that is to say a transverse slip, so that one is not master of the final given twist over. Finally, the fibers free in the air can very well marry together and arrive in uncontrolled bundles on the wire in formation.

It therefore appears that too many very important points are left to chance in known processes of the "open end" type and this is why the yarn thus produced has practically never been able to be classified as "good", which considerably restricts the application of these methods, despite their enormous productivity.

The present invention proposes to overcome the drawbacks indicated above, by providing an "open end" process capable of ensuring uniform torsion throughout the section of the wire, that is to say a twisting pitch which is substantially the same from the core of the wire to its periphery, in order to best respect the well-known laws of Koechlin which define the best conditions for manufacturing a wire by obtaining the same pitch in the different cylindrical layers of the wire.

By fulfilling these conditions, the invention aims to extend the application of the method to a wide variety of textile threads, large or fine.

To this end, the invention provides a method of the type indicated in the preamble, characterized in that the fibers are driven substantially in their longitudinal direction up to the vicinity of the wire formation area defined by a first suction slot on a first air-permeable surface, in that they are deposited on the training area by moving them transversely, parallel to themselves, so that they arrive all at once over their entire length over a generator of the cone formed by the tip of the wire, in that said tip is driven in longitudinal translation and in rotation by rolling without sliding on the first air-permeable surface so as not to twist the tip, and in this twist the wire in a torsion area located downstream of the point, gradually eliminating its rotation speed by rolling without sliding, during its longitudinal translation, on a second surface permeable to l air moving in front of a second suction slot which defines the torsion area.

Preferably, the fibers are gripped at their front end to take them from the wick and move them longitudinally in a direction substantially parallel to the first breathable surface, the fibers are kept away from the first breathable surface
The air during this movement, and the fibers are released when their front end is near the downstream end of the training area, to allow their transverse movement to the tip of the wire.

In a preferred embodiment of the method, the first and the second air-permeable surface consist respectively of a first and a second rotary disc, these discs being consecutive along the wire. Preferably, the transverse speed component of the surface of the first disc relative to the tip of the wire increases from zero to a determined value along the formation area, and the transverse speed component of the surface of the second disc with respect to the wire decreases from said determined value to zero along the torsional area. It is possible to impose on the wire a regulating stretch between the two discs before it is twisted, by driving it with a longitudinal speed component of the air permeable surface which is higher on the second disc than on the first.

There are already systems of this kind, using rotary discs having suction slots offset with respect to a given radius, for example according to the German patent N 2 655 337 in the name of FEHRER or the English patent N "1 231 198 in the name from GREENWOOD and SHEPARD. But in these systems, the length of the slit is used both for the conical tip of the wire, corresponding to the area where the fibers are deposited, and for the cylindrical part in which a twist is applied by progressive reduction of the speed of rotation of the wire. This solution does not make it possible to maintain a rolling without sliding of the wire on the air-permeable surface, because there is a geometric impossibility. In the present invention, this problem is resolved by the use of two separate permeable surfaces which may be discs.

For the implementation of this method, the invention provides a device comprising feeding members for advancing a wick of fibers, means for gripping the fibers, arranged to cyclically extract fibers from the wick and to drive them up to '' near a wire tip formation area, a first air permeable surface moving in front of a first suction slot which defines the wire formation area on this surface, means for twisting the wire and means for longitudinally driving the formed wire.This device is characterized in that the means for gripping the fibers are arranged to drive the latter substantially in their longitudinal direction up to near the training area, in that the device comprises, between the means for gripping the fibers and the training area, guide means for determining the orientation of the fibers on this area so that the fibers reach nent the tip of the wire at once over their entire length, in that the shape of the formation area is arranged so that the displacement of the first air permeable surface communicates with the tip of the wire a rotation on itself without torsion, superimposed on a longitudinal translation, by rolling without sliding, and in that the means for twisting the wire comprise a second air-permeable surface moving in front of a second suction slot defining a torsion area which is separate from the training area.

In a first variant, the means for gripping the fibers comprise protrusions carried by a drum driven in rotation, and an endless belt applied against said protrusions on a part of the periphery of the drum. In another variant, the means for gripping the fibers comprise perforated protruding sectors formed on the periphery of a drum driven in rotation, a stationary wheel arranged to roll against a peripheral surface of said sectors passing in front of it to pinch the wick, and means for sucking air through the sectors towards the inside of the drum to maintain the fibers on the peripheral surface of the sectors on a part of the periphery of the drum.

English patent NO 411 862 describes an extraction method of the latter type, in which the fibers are extracted from the food wick by pinching a fluted sector, rolling against a rubberized wheel.

In this case, a suction intervening further attempts to prevent the fibers thus extracted from escaping by centrifugal force before they are fully integrated into the wire which, in this process, is pulled through the center of the fluted sector. In fact, this method of extraction remains usable, provided that it is combined with the method of transverse deposition of the fibers on the area where the tip of the thread is reconstituted, and no longer directly on the thread itself.

An advantageous embodiment provides that said guide means comprise a stationary plate extending between the tip of the wire and the means for gripping the fibers and provided with a toothed edge which extends longitudinally opposite the area of formation and which is inclined transversely towards this area.

In the preferred form of the device according to the invention, the first and the second air-permeable surface consist respectively of a first and a second rotary disc, these discs being consecutive along the wire. In this way, provision can be made for the formation area to extend from an initial point to an end point situated near the periphery of the first disc, said initial point being closer to the center of this disc than the end point. , and that the longitudinal direction of the formation area at the initial point is substantially perpendicular to the radius going from the center of the disc at this point. It is also possible to provide that the torsion area is substantially rectilinear and extends from an initial point. located near the periphery of the second disc to an end point which is closer to the center of this disc, and in that the direction of the torsion area is perpendicular to the radius from the center of the disc to the end point.

Preferably, the first and the second disc are located substantially in the same plane and the wire is on the same side on the two discs.

To better understand the invention, a known method and an embodiment of the method according to the invention will be described below, with reference to the appended drawings, in which: FIG. 1 is a perspective diagram illustrating the formation of the wire in a known method of the loose end and friction type, FIG. 2 is a diagram similar to FIG. 1, illustrating the formation of the wire in the method according to the invention, FIG. 3 schematically represents the rolling of a conical tip of the wire on a rotating disc, FIG. 4 is a schematic plan view of a first embodiment of a device implementing the method according to the invention, FIG. 5 shows a part of the device of FIG. 4, after the upper elements of this device have been removed, FIG. 6 is a sectional view along line VI-VI of FIG. 4, fig. 7 is a side view in the direction of arrow VII in FIG. 6, fig. 8 is a schematic view of the wire formation area, FIG. 9 is a sectional view along line IX-IX of FIG. 8, and fig. 10 is a view similar to FIG. 4, - representing a variant of the means for driving the fibers to the area of formation of the wire.

In a known method, illustrated in FIG. 1, of the open end and friction type, a wire I is formed by means of fibers 2 between two parallel cylinders 3 and 4 porous or perforated, which are rotated in the same direction, as indicated the arrows, so that the wire rotates by friction between them in the direction of arrow A, at the same time as it is driven axially by other means in the direction of arrow B. An air suction is carried out in each cylinder 3, 4, while stationary members disposed behind the air-permeable peripheral wall of the cylinder define a suction slot 5 opposite the tip 6 of the wire in formation. In this drawing, there are shown four parallel planes PO to P3 which separate different processing zones of the wire 1 along the cylinders 3 and 4. Beyond P3, the wire 1 is driven so as not to rotate. Between P1 and P2 is the driving part of the surface of the cylinders which drives the wire in rotation at its maximum speed. Between P2 and P3 there is a transverse sliding of the wire on the cylinders since in P3 the wire no longer turns. P2 is therefore poorly defined.

The fibers 2 arrive on the tip 6 in the feeding zone located between PO and P1. The end of the conical tip 6, having a smaller diameter than its base, can turn faster than the wire if it is pressed on one of the two slots 5. Depending on whether the fibers 2 arrive with an inciinage 'fl or f2, they will wrap around the tip 6 with a different pitch. It will then be impossible to regularize this step later. In addition, since the fibers are generally free and uncontrolled before reaching the tip of the thread, they can mix with one another before incorporating into the thread. It has been proposed to mechanically extract the fibers from the food wick and transport them by controlling their position to the tip of the forming wire. This prevents the fibers from becoming tangled during transport, but problems arise at the time. where you have to drop them. If they are left too early, their correct way to reach the tip of the wire is not guaranteed, and if they are kept too long they wrap around the wire and block the linear drive of it before d 'be released;
On the other hand, the drive of the rotating wire, as it has been done until now, is generally not satisfactory. If it is produced by means of a false twist whistle, there is an inversion of the pitch in the whistle, which is detrimental to the advance of the wire which is drawn at this point on a zero pitch. If the drive is done by friction, so with a slip, you are not able to control the torsion.

In summary, the known method described above has the following defects - possibility of mixing the incoming fibers, - no uncontrolled tip, - landing of the fibers on the uncontrolled tip, - uncontrolled final step, because there is friction and not rolling
without slipping, - unnecessary friction on the finished wire, - the wire must be pulled because the cylinders do not eject it by themselves, - it is the winding of the fibers on the tip of the wire which must cause these
fibers, that is to say if they only reach the end of the
wire, this winding will be insufficient and they will form a sta deposit
tionnaire, detrimental to the quality of the thread.

Within the framework of the general aim defined above, the present invention aims to provide a method making it possible to avoid to a substantial extent the above-mentioned defects. The basic principle of this process is illustrated in fig. 2, in which the parallel planes PO and P1 delimit the point 6 of the wire 1, that is to say an area 7 for forming the wire, while the planes
PI and P4 delimit a zone 8 of twist of the wire, which follows zone 7. In the left part of the figure; a angular speed 0 of rotation of the wire has been represented by a diagram along the zones 7 and 8. In the formation zone 7, this angular speed is constant along the tip 6, while it decreases along the torsion zone 8 to be zero beyond the plane P4. As it can be assumed that the point 6 has a substantially conical shape, the transverse speed W r of a point on its surface lying at a radius r from the axis of the wire varies with r from a value zero in the plane PO to a maximum in the plane Pl, then it decreases with 1 to the plane P4. Mechanical means will be described below allowing these different tangential speeds to be imposed along the wire.

Between PO and PI, the fibers 2 feed the tip 6 of the wire arriving suddenly and parallel to themselves on a generator of the cone, so that they do not wind around the tip. As the latter rotates by rolling without sliding on an air permeable surface having, in the transverse direction of the tip 6, a transverse component of speed which is equal to zero the tip 6 is not twisted.

The air permeable surface also has a longitudinal velocity component which is substantially constant along the tip, which advances the tip in direction B without the wire 1 having to pull the tip.

Between P1 and P4, the wire rolls without sliding on a second air-permeable surface having a transverse component of speed which decreases up to P4, which gradually twists the wire in a perfectly controlled manner, while a longitudinal component of the displacement of the air permeable surface continues to advance the wire. A slight stretch may advantageously be provided in the vicinity of
P1, before twisting, by imposing a slightly higher longitudinal speed in zone 8 than in zone 7.

Beyond P4, wire 1 is finished and no longer turns on itself. It is naturally ejected from the device without having to be pulled.

The block diagram of fig. 3 shows how the conical tip 6 of the wire 1 can be arranged in a simple manner on a disc 9 rotating around its center O, so as to roll without sliding and without twisting, while being driven longitudinally at a constant speed. It is recognized that the base of the tip cone 6 coincides with the edge of the disc. If the point occupied the position 6 'drawn in broken lines, its vertex S coinciding with the center O, it is obvious that it would roll without being twisted, but also without advancing. On the other hand, if the point 6 is aligned on a straight line 10 located at a distance R from O, the angular speed of rotation of the disc 9 determines over the entire length of the tip a longitudinal component of constant speed v1, equal to lp.R. The transverse component v t of the speed at the surface of the disc varies from zero in S to vt = Re sin R along the point, R e being the outside radius of the disc. This speed vt determines the speed of rotation W of the wire I. If the tip 6 is perfectly conical, we can always obtain a uniform speed W along the tip by replacing the line 10 by a curve whose tangents pass substantially at a distance R from the center O and along which the function Re six d varies linearly with the curvilinear abscissa.

Figs. 4 to 9 show an example of a device designed to implement the method illustrated in FIG. 2. With reference to fig. 4 to 7, the device shown may have fiber supply members which are of any known type and in which, for example, a wick of fibers 11 is brought, through a funnel 12, between two belts d feed 13 and 14 which are driven by pulleys 15 and 16 and which define a pinch passage 17 regularly advancing the wick 11 in a second funnel 18.

Beyond the funnel 18, small bundles of fibers are torn from the end of the wick by gripping members comprising on the one hand a rotary drum 20 and on the other hand an endless belt 21 which is carried by rollers 22 and 23 now applied against a certain length of the periphery of the drum 20, in particular against an upper rim 25 of this drum and against radial protrusions 26 located under the rim 25 and regularly spaced around the periphery of the drum 20 The distance between two successive protrusions 26 is greater than the maximum length of the fibers 2 of the wick 11. Holes 27 are provided in the flange 25 to allow the passage of air. belts 13 and 14, the drum 20, as well as the rollers 22 and 23 are mounted in cantilever on an upper frame which is not shown in order to clarify the drawing.

Below these members, another frame supports members for forming the wire 1, comprising two rotary discs 30 and 31 porous or perforated to be breathable, under which are arranged two corresponding suction slots 32 and 33 which occupy a stationary position and which define in known manner, by suction of air through the discs, corresponding areas on which the suction applies the fibers and the yarn.

In fig. 5, the first suction slot 32 defining a wire formation area on the first disc 30, as well as the second suction slot 33, which represents a twist area of the wire on the second disc 31, is shown in broken lines. In the present case, the two discs 30 and 31 are located in the same plain and are tangent to one another. They are carried and driven in opposite directions by respective shafts 34, 35 so that the tangential speed of the two discs at their point of contact is substantially the same.

The torsion area defined by the suction slot 33 is rectilinear and it passes at a distance R2 from the center C of the disc 31, its downstream end D lying precisely in line with the center C, while its upstream end E is near the edge of the disc, at a distance R1 from the center C. The radius R1 forms an angle Ct with the direction of the wire. The same geometric reasoning as in the case of fig. 3 shows that, when the disc 31 rotates at an angular speed 9, each point on its surface coming into contact with the wire 1 has, with respect to the direction of the wire, a component of constant longitudinal speed equal to 1 × 0 R2 over the entire length of the torsion area. On the other hand, its transverse velocity component decreases linearly along this area, from a value equal to T Rl-cos l at point E, up to zero at point D, which corresponds well with the decreasing variation of the speed of rotation (fig. 2) of the wire in the torsion zone 8. It should be noted that one can freely choose the length of the torsion area by choosing the diameter of the disc 31, and we can modify the variation (linear or not) of the speed of rotation of the wire 1 along this area by modifying the layout of the slot 33, which does not need to be straight since the wire is not not fired.

In contrast, the wire formation area defined by the suction slot 32 on the first disc 30 is essentially curved in this example, since it follows the edge of the drum 20 over a large part of its length.

It begins at a point H which is substantially aligned with the center
F of the disc 30 and the center G of the drum 20, and it ends at a point I close to the edge of the disc 30. At the point H, which corresponds to the position of the plane PO of FIG. 2, the direction of the wire defined by the slot 32 is perpendicular to the radius FH, that is to say that the component of transverse speed of the disc relative to the wire is zero. On the other hand, this component is maximum at point I and it is practically equal to that of the disc 31 at point E, these two points corresponding to the position of the plane P1 of FIG. 2. This is how the conical tip 6 of the wire rolls on the training area without undergoing twisting. If necessary, a slight stretching could be carried out between points I and E by slightly increasing the speed of the second disc 31.

Fig. 5 also shows that the wire I can be guided by a pair of rollers 36, 37 as soon as it has left the disc 31, to be wound on a reel 38 by known means.

With reference to fig. 6 and 7, a horizontal plate 40, mounted in a stationary position between the first disc 30 and the drum 20, has a serrated edge forming a comb 41 which extends above the area of formation of the wire, between the slot suction 32 and the clamping members 21 and 26 bringing the fibers 2 to this area. The role of this comb will be explained later, with reference to Figs. 8 and 9.

The overall operation of the device described above is as follows. The wick 11 driven by the belts 13 and 14 has, at the outlet of the funnel 18, ends of fibers which are then pinched between the protrusions 26 of the drum 20 and the belt 21. These fibers are extracted over their entire length. the food wick, so that they constitute a small bundle or bundle of substantially parallel fibers which have various lengths and which are gripped near their front end to be transported longitudinally towards the wire formation area. As soon as the rear end of a fiber is released, it is sucked towards the air-permeable disc 30 by the slot 32. If it touches the disc, it is brought by the latter onto the teeth of the comb 41 where it hangs. As long as this fiber is in translation, its rear end cannot come into contact with the conical tip 6 of the wire which is located below the comb. It is only when the bundle of fibers is released by the pinching members 26 and 21, near the end of the training area, that it can be suddenly sucked towards the disc, there apply at the same time over its entire length, and be transported laterally by it to the tip 6 of the wire in formation.

Of course, the fibers 2 are transported by the drum 20 at a speed which is a multiple of that of the wire 1. For example, to spin at a speed of 100 m / min a cotton thread whose fibers do not exceed 25 mm , it can be provided to defibrate at a speed of 630 m / min by means of the drum 20 rotating at around 2000 revolutions / min if its diameter is 1G cm and if it is provided with twelve gripping members around its periphery, six bundles of staggered fibers distributed along 25 mm of wire.

It is therefore noted that the device described makes it possible to reach high working speeds without making use of members rotating at very high speed, such as are encountered in conventional shredders.

As it rolls on the first disc 30, the point 6 of the wire is transported longitudinally at a constant speed by the disc, then the wire 1, which turns, passes over the second disc 31 where its rotation is gradually stopped in the torsion area defined by the slot 33 as described above At the end of this area, the disc 31 no longer stresses the wire 1 longitudinally, which then goes towards the call and the winding. Evacuation and winding speeds can be the same; a call of the wire is not even essential, the priming being done all alone.

Figs. 8 and 9 show in more detail the operating principle of the comb 41. It can be seen that the plate 40 is folded above the point 6 of the wire, so that the teeth of the comb are close to the surface of the disc 30. The tip 6 rolls without sliding on the disc moving in the direction indicated by the arrows M, above the downstream edge of the suction slot 32.

Take the example of a fiber 2 grabbed at its front end and driven from H to I above the comb 41. As soon as the rear end 2 'of the fiber is released from the food wick in H, it is sucked by the slot 32 by sliding on the inclined surface of the comb 41. It is then driven by the disc and it engages in a tooth of the comb.

As the traction continues to be exerted on the fiber up to point J, the fiber 2 is stretched above the comb and its rear end 2 ′ can pass from one tooth to another. It is only when the fiber 2 (as well as the other fibers of the same package) is released at I that its longitudinal translation ceases and that it can slide laterally on the comb 41, come into contact with the surface disc 30 over the entire length, be transported parallel to itself to the tip 6 of the wire and integrate there without winding. In the diagram shown in fig. 8, the outline of the comb 41 is rectilinear, but it can obviously be curved as in the case of FIG. 4, provided that it is substantially parallel to that of the tip 6 of the wire.

Fig. 10 shows a variant of the fiber extraction members, usable in place of the corresponding members 20 to 26 shown in FIG. 4. This device resembles that of British patent NO 411 862 cited above, but here the entrainment of the fibers is first carried out by pinching between one of the protruding perforated sectors 51 of a rotary drum 50 and a wheel rubberized 52, then by suction through the sector 51, thanks to a suction passage 53 delimited by walls 54 and 55 inside the drum 50. After total extraction, the fibers are transported longitudinally and kept at a distance from the first disc 30 thanks to a guide member similar to the comb 41 described above, then they are released in line with the wall 55 at a stage where they are sucked against the first disc 30 by the first suction slot 32. operations take place as described with reference to FIGS. 2 to 5.

The present invention is not limited to the embodiments mentioned above, but it extends to any modification or variant obvious to a person skilled in the art. In particular, other means can be provided for bringing the fibers parallel to themselves on the wire formation area, and the geometry of this area on the first disc can be adapted as a function of these means. If, for example, the formation area must have a shape which clearly deviates from an arc of a circle, in particular a rectilinear shape, the drum 20 can be replaced by a belt equipped with similar protuberances and shouldered by a guide having a desired shape. . Furthermore, the device described can be used with fibers of different natures and of different lengths. In this regard, it will be noted that the rotary drum 20 or 50 can easily be replaced by a drum having closer protuberances if shorter fibers are to be used. On the other hand, the method according to the invention is not limited to the use of rotating discs, since it can also be carried out with other surfaces such as conical or convex, although the construction is more complicated.

Claims (13)

Claims 1. spinning method of the loose end type, in which fibers or bundles of fibers are cyclically removed from a wick of fibers, these fibers are drawn close to a wire formation area defined by a suction slot on a breathable surface moving in front of this slot, the fibers are deposited on the formation area near a conical tip of the wire, this tip is rotated by rolling on the breathable surface , and the wire thus formed is simultaneously driven in the longitudinal direction, characterized in that the fibers (2) are driven substantially in their longitudinal direction up to the vicinity of the wire formation area, defined by a first suction slot on a first air-permeable surface (30), in that they are deposited on the training area by moving them transversely parallel to themselves, so that they arrive all at once ontheir entire length on a generator of the cone formed by the tip (6) of the wire, in that said tip (6) is driven in longitudinal translation and in rotation by rolling without sliding on the first surface permeable to air so as not to twist the tip, and in that the wire (1) is twisted in a torsion area located downstream of the tip, gradually eliminating its speed of rotation by rolling without sliding, during its longitudinal translation, on a second air permeable surface (31), moving in front of a second suction slot which defines the area of torsion. 2. Method according to claim 1, characterized in that one seizes the fibers (2) at their front end to take them from the wick (11) and move them longitudinally in a direction substantially parallel to the first surface permeable to the 'air (30), in that the fibers are kept away from the first air permeable surface during this movement, and in that the fibers are released when their front end is close to the downstream end (I) of the training area, to allow their transverse movement to the tip (6) of the wire. 3. Method according to claim 1, characterized in that the first and the second air-permeable surface consist respectively of a first (30) and a second rotary disc (31), these discs being consecutive along the wire ( 1). 4. Method according to claim 3, characterized in that the transverse velocity component of the surface of the first disc (30) relative to the tip (6) of the wire increases from zero to a determined value along the area of formation, and in that the transverse speed component of the surface of the second disc (31) relative to the wire (1) is decreasing from said determined value up to zero along the torsional area. 5. Method according to claim 3, characterized in that one imposes on the wire a regulating stretch between the two discs (30, 31) before it is twisted, driving it with a longitudinal speed component of the permeable surface air which is higher on the second disc (31) than on the first (30). 6. Device for implementing the method according to claim 1, comprising feed members for advancing a wick of fibers, means for gripping the fibers, arranged to cyclically extract fibers from the wick and to drive them up there. proximity to an area for forming a tip of the wire, a first air permeable surface moving in front of a first suction slot which defines the area for forming the wire on this surface, means for twisting the wire and means for longitudinally driving the formed wire, characterized in that the means (20 to 26) for gripping the fibers are arranged to drive the latter substantially in their longitudinal direction up to the vicinity of the training area, in that the device comprises, between the means for gripping the fibers and the training area, guide means (40, 41) for determining the orientation of the fibers (2) on this area so that the fibers reach the tip (6) of the wire at once over their entire length, in that the shape of the formation area is arranged so that the displacement of the first air-permeable surface (30) communicates with the tip (6) of the wire rotating on itself without torsion, superimposed on a longitudinal translation, by rolling without sliding, and in that the means for twisting the wire comprise a second air-permeable surface (31) moving in front of a second suction slot (33) defining a torsion area which is separate from the training area. 7. Device according to claim 6, characterized in that the means for gripping the fibers comprise protrusions (26) carried by a drum (20) driven in rotation, and an endless belt (21) applied against said protuberances on a part around the drum. 8. Device according to claim 6, characterized in that the means for gripping the fibers comprise perforated protruding sectors (51) formed on the periphery of a drum (50) driven in rotation, a stationary wheel (52) arranged to roll against a peripheral surface of said sectors passing in front of it to pinch the wick (11), and air suction means (53 to 55) through the sectors (51) towards the inside of the drum to maintain the fibers on the peripheral surface of the sectors on a part of the periphery of the drum. 9. Device according to claim 6, characterized in that said guide means comprise a stationary plate (40) extending between the tip (6) of the wire and the means for gripping the fibers and provided with a toothed edge (41 ) which extends longitudinally opposite the training area and which is inclined transversely towards this area. 10. Device according to claim 6, characterized in that the first and the second air-permeable surface consist respectively of a first (30) and a second rotary disc (31), these discs being consecutive along the wire ( 1). 11. Device according to claim 10, characterized in that the formation area extends from an initial point (H) to an end point (I) located near the periphery of the first disc (30), said point initial being closer to the center (F) of this disc than the end point, and in that the longitudinal direction of the formation area at the initial point is substantially perpendicular to the radius from the center of the disc to this point. 12. Device according to claim 10, characterized in that the torsion area is substantially rectilinear and extends from an initial point (E) located near the periphery of the second disc (31) to an end point (D) which is closer to the center (C) of this disc, and in that the direction of the area of torsion is perpendicular to the radius from the center of the disc to the end point. 13. Device according to claim 10, characterized in that the first and the second disc (30 and 31) are located substantially in the same plane and in that the wire (1) is on the same side on the two discs.