CH667678A5 - DEVICE FOR LAYING OUT A CABLE OF CONTINUOUS FILAMENTS. - Google Patents

Description

DESCRIPTION

The present invention relates to a device for spreading a continuous filament cable in order to obtain a web usable in particular in the manufacture of nonwoven articles.

There are many ways to achieve spreading or widening - the two terms having the same meaning in this text - of a continuous filament cable in order to obtain a web.

In French patent No. 1418403, the use of curved bars and air expanders is described. In French patent No. 1498481, an apron-transporter is described, made of elastically extensible material, which widens transversely as it advances. The surface of the carpet can be provided with small, closely spaced points causing a temporary connection of said surface with the network of filaments and resulting in a more uniform distribution of the filaments. According to American Patent No. 3808639, a sheet of filaments is spread by passing it over a series of discs located close to each other which rotate around the same axis but in divergent directions, the periphery of the discs being provided with flexible protuberances intended to engage the filaments. In Japanese application No. 72/04738 is described an apron-transporter which widens transversely as it advances and which is constituted by helical springs arranged transversely to the direction of advance, the spreading of the cable or ribbon being due to the sliding on the turns of the springs while these 'elongate when advancing the apron.

However, the above devices are not satisfactory, especially if you want large spreading rates (7 to 8 times the initial width). Among the disadvantages they present, we can cite:

- limited performance, low enlargement rate for curved bars,

- noise pollution, high consumption of fluid for air expanders according to French patent N ° 1418403,

- limited enlargement rate, otherwise reduced lifespan of the elastic apron for the device according to French patent N ° 1498481,

- lack of homogeneity of the sheet coming from the fact that it is not sufficiently fixed during spreading, limited rate of widening for the device according to American patent N ° 3808639,

- irregularity of the sheet resulting from groupings in packages, problems of service life of the springs, limited rate of enlargement for the device according to Japanese application No. 72/04378.

To avoid the drawbacks of the above devices, another device for spreading a continuous filament cable comprises at least one spreading assembly comprising at least:

- a roller mounted on an axis driven in rotation,

- elongate extendable elements, integral in rotation with the roller, arranged at the periphery of the latter in a direction parallel to the generatrices, each element being provided with at least one row of pins facing outwards,

Means for subjecting the elongated elements to an extension phase and to a retraction phase during a revolution of the roller,

Means for bringing the cable into contact with the elongated elements at the start of the extension phase and means for taking up the cable at the end of the extension phase.

In operation, the pins penetrate the cable at the start of the extension phase and move apart during this phase, entraining and therefore spreading the filaments. At the end of the extension phase, the

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spread cable is taken by means of recovery and therefore removed from the action of the pins; the elongated elements undergo alone (without the cable) the retraction phase at the end of which they have regained their original length. Advantageously, the spreading device comprises several assemblies (for example 10 to 12) as above arranged one after the other in a horizontal plane, the overall spreading rate being the product of the spreading rates of all sets.

The above device is satisfactory in the sense that it eliminates the drawbacks of the prior devices and in particular makes it possible to obtain a perfectly homogeneous and regular sheet. However, due to the horizontal arrangement of the spreading assemblies, it has a fairly large footprint, not always compatible with the space available. In addition, the multiplication of spreading assemblies and in particular cams which are expensive members poses cost problems.

The object of the present invention is to create a device for spreading, or widening, a continuous filament cable, making it possible to solve these problems. It relates to a device for spreading a cable of continuous filaments which is characterized in that it comprises at least one spreading assembly comprising at least:

- a drum driven in rotation,

Elongate extendable elements integral in rotation with the drum, arranged at the periphery of the latter, according to generatrices, each element being provided with at least one row of pins facing outwards,

Means for subjecting the elongated elements to several successive alternating phases of extension and retraction during one revolution of the drum,

Means for bringing the cable to the extendable elongated elements and means for taking up the spread cable,

- Means for submitting the cable to the action of the pins during the extension phases and means for removing it from their action during the retraction phases.

The periphery of the drum defines a path for the cable during which it is subjected to spreading in a spreading zone which extends over all or part of the periphery of the drum and comprises several stages of spreading. The entrance to the spreading zone is defined by the fixed position of at least part of the means for taking up the spread cable. The drum can advantageously consist of two end flanges wedged on an axis, the two flanges being optionally connected at their periphery by a solid or perforated cylindrical skirt, or simply by spacers.

The extendable elongated elements are angularly and regularly distributed around the axis of the drum. They each consist of at least one strap or elastic band, the section of which can be square or rectangular and more or less flat. The outer face of the strip, which can be either the flat of the strip or the edge, is provided with at least one row of pins extending in a direction parallel to the generatrices of the roller. There can be several rows of pins; in this case, they are advantageously arranged in staggered rows. Each extendable elongate element may comprise several adjacent elastic bands, integral at their two ends.

The extendable elongated elements are of even number and at least four. During the rotation of the roller, each element is subjected on a fraction of a turn to an extension phase and then on the next fraction of the same length to a retraction phase, the extension-retraction cycle being repeated over one revolution, a number times equal to half the number of elongated extendable elements, two consecutive elements being in two different phases. Each extension phase located in the spreading zone corresponds to a spreading stage.

According to a preferred embodiment, the means for subjecting the extensible elongate elements to several successive alternating phases of extension and retraction comprise:

- a series of rod-crank assemblies mounted at the two ends of the drum, each associated and connected to the end of at least one elongate extendable element,

A fixed ring gear, coaxial with the axis carrying the drum, disposed at each of the two ends of said drum,

s - satellites mounted on the drum, associated with each rod-crank assembly, and engaged with the corresponding toothed crown in order to ensure the rotation of the crank.

The crank of each rod-crank assembly is coaxial and integral in rotation with the corresponding satellite, while the foot of the connecting rod is connected directly or indirectly to the end of an elongate extendable element or of two consecutive elements in such a way that a return trip of the big end corresponds to an extension-retraction cycle. In the case where the same rod-crank assembly is connected to two consecutive elongated elements, the connection is designed in such a way that, when one of the elements is in extension, the other is in retraction.

For a crank turn, that is to say a return trip of the connecting rod end or an extension-retraction cycle, there is a turn of the corresponding satellite. If N is the number of extension-retraction cycles 20 per turn of the roller (the number of elongated extendable elements being 2 N), if D is the number of teeth of the ring gear, the number of teeth of each satellite will be D / NOT.

However, the means for subjecting the extensible elongate elements to several successive alternating phases of extension and re-traction can take other embodiments.

For example, an embodiment consisting of:

- a rotary cylindrical cam provided with a left circumferential groove, mounted on the drum, associated with each of the two ends of each extendable elongated element,

30 - a movable roller in the groove of each cam and a connecting bar between said roller and the corresponding end of the extendable elongate element and, as before,

A fixed toothed ring coaxial with the axis carrying the drum, disposed at each of the two ends of said drum and of the satellites.

35 tes, which, associated with each cam, ensure their rotation from the corresponding toothed crown.

In this embodiment, advantageously, the circumferential groove of each cam comprises two propeller sections of opposite pitch, each extending over 180 ° and one corresponding to an extension phase, the other to a phase retraction, one revolution of the cam corresponding to one complete cycle. As for the previous embodiment, if N is the number of extension-retraction cycles per revolution of the roller, D the number of teeth of the ring gear, the number of teeth of each satellite will be

45 N

The means for supplying the cable to the extendable elongate elements may comprise a fixed curved bar, disposed in the immediate vicinity of the drum and determining the entry to the spreading zone.

The means for taking up the spread cable can comprise a duo so presser rollers, at least one of which is positively driven, the relative position of this duo relative to the drum defining the exit from the spreading zone.

The means for subjecting the cable to the action of the pins during the extension phases and for withdrawing it from their action during the 55 retraction phases include, according to a preferred embodiment:

- a movable member for lifting the cable adjacent and parallel to each extendable elongated element,

A lever associated with each of the two ends of each 60 cable lifting member, articulated on the drum,

- A fixed cam for controlling the above levers, arranged at each of the two ends of the drum and coaxial with the latter.

The movable cable lifting member is movable in a radial direction. It is for example constituted by a gated allon-65 plate extending along the extendable elongated element or a profile, for example with a U-section partially surrounding the elongate extensible element. The lever control cam associated with each cable lifting member present in the region of its periphery

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rie a cam path consisting of repetitive zones, each corresponding to an extension-retraction cycle.

Each lifting member is controlled by the two levers located at its ends, which are connected to the cam track and follow its profile. Said profile in each zone is drawn so that during the rotation of the drum the movements of the lifting member occur at the start of each phase. At the start of the retraction phase, there is displacement towards the outside of the lifting member, which puts the cable out of the action of the pins during the entire retraction phase. At the start of the extension phase, there is displacement towards the interior of the lifting member, thus subjecting the cable to the action of the pins during the entire extension phase.

Advantageously, each elongate extensible element is associated with means for assisting with deformation (extension and retraction) accompanying said element in its deformation.

In the extension phase, their role is to lighten the stretching stresses of the elongated element and, in the retraction phase, they allow it to be carried out uniformly over the entire length of said elongated element. .

These means are two slides with which each extendable elongated element is in contact directly or indirectly over at least part of its length - substantially half in the retracted state - and over at least part of the periphery of its section outside the zone. fitted with pins. The slides are integral in translation with one and the other of the means subjecting the elongate extensible elements to the extension-retraction cycles and move in opposite directions by accompanying each element in its movement of extension and retraction. In the extension phase, the two slides move outward and, given their contact with the elongated element, act on the latter by reducing the stretching stresses to which it is subjected. In the retraction phase, the two slides are pushed inward under the effect of the means subjecting the elongated elements to the extension-retraction cycles (connecting rods of the connecting rod-crank systems or connecting bars). Since contact is maintained between the extendable elongated members and the slides, the thrust of the latter helps the former to retract uniformly over their entire length.

The device according to the invention can comprise several spreading assemblies as described above, arranged one after the other. For example, it can comprise three assemblies, the axes of the three drums being arranged according to the vertices of an equilateral triangle.

In operation, for each cycle, during the extension phase, the pins, which have penetrated into the cable, move apart, thus causing the filaments to spread; during the retraction phase, the pins tighten, but since they have been removed from the cable, the cable retains the width it had at the end of the extension phase, until the next cycle.

However, the invention will be better understood with the aid of the exemplary embodiments and the schematic figures below, given by way of illustration and not limitation.

Figures 1 and 2 show a device according to the invention with three spreading assemblies, respectively seen at the end and seen from the front.

Figure 3 is a longitudinal sectional view of a spreading assembly.

Figure 4 is a partial end view of a spreading assembly. showing in particular the cable lifting devices.

Figure 5 is a partial view of an embodiment of an elongate expandable member.

FIG. 6 represents in longitudinal section an elongate extensible element mounted on the drum.

Figure 7 shows in cross section an elongate expandable member mounted on the drum.

Figure 8 is a cross-sectional view of the mounting means on the drum of an elongate expandable member.

FIGS. 9 and 10 show extensible elongate elements and the associated means for subjecting them to extension and retraction phases, the latter being produced in two different forms.

The device according to FIGS. 1 and 2 comprising three spreading assemblies comprises three rotary drums 2, 3, 4 whose axes 5 are arranged according to the vertices of an equilateral triangle on a chassis 5, the cable 1 passing through the drums in the 'order 2, 3, 4.

The drum 2 comprises 14 elongate extensible elements 6 shown diagrammatically by lines, defining 7 theoretical spreading stages; the drum 3 comprises 10 elongate extendable elements defining io 5 theoretical spreading stages, and the drum 4 comprises 6 elongate extensible elements defining 3 theoretical spreading stages. In fact, given the relative arrangement of the drums and the resulting cable route, the number of active stages is respectively 5, 3, 2 for the drums 2, 3, 4, which makes a total of 10 stages i5 of sprawl. A curved bar 7 forming part of the cable feeding means is disposed near the first drum 2. It serves to define the entry to the spreading zone and also constitutes an entry brake limiting the ascent to the rear of the spreading effect. Near the roller 4 is arranged a duo 8 of pressure rollers 20 81-82 of which at least one is positively driven. This duo constitutes the means of recovery of the spread sheet and determines the exit from the spreading area of the drum 4. The relative position of the drums 2 and 3 determines the exit from the spreading area of the drum 2 and the entry of the spreading area of the drum 3. Likewise, the exit from the spreading area of the drum 3 and the entry of the spreading area of the drum 4 are determined by the relative positions of the drums 3 and 4. The drums 2, 3, 4 are fitted with pivoting anti-winding safety flaps 9. An accidental winding of the cable over the entire periphery of a drum causes the flap to tip over, .m which then triggers an alarm and stops the machine.

In FIG. 2, it can be seen that the drums 2, 3, 4 are of increasing length, depending on the increasing width of the cable being spread, and that they are driven by a common motor-variator assembly 10.

.15 In Figure 3, there is shown schematically, in longitudinal section, a spreading assembly. There is a drum, for example the drum 3, comprising two end flanges 11, provided with longitudinal extensions 110, secured by keying an axis 12 mounted rotating on the chassis 5. The drive is carried out by 4o l 'Intermediate of a pulley or toothed wheel 14 and a belt or chain 15, from the motor-variator 10. The two flanges 11 are connected by spacers not shown. We can also see in this figure 3 an elongate extendable element 6, provided with pins 25, mounted on the periphery of the drum 3 and the ends of which are each secured to extension means 13 (subjecting the elongate elements to successive phases extension-retraction) based on the principle of the connecting rod-crank system according to the embodiment shown in Figure 10. The crank 16 of the connecting rod-crank system is integral and coaxial with a satellite 17, itself engaged with a 5ii fixed toothed crown 18 coaxial with the axis 12. The toothed ring 18 is integral and coaxial with a tubular member 19, fixedly mounted on the frame 5 and serving as a bearing on the axis 12. The drum 3 comprising 10 elongated extendable elements, each end of the drum 3 is provided with 10 extension means 13 and 10 satellites 17. At each end of the drum 3, a fixed cam 20 is mounted integral and coaxial with the tubular member 19. It is provided with a cam 21 to zone s repetitive, each corresponding to an ex-tension-retraction cycle. The cam path 21 controls levers such as 22 serving for the movement of members 23 for lifting the mid-cable. In FIG. 4, we can notice in particular the drum 3, its axis 12, the tubular member 19, the cam 20 which is integral with it, extendable elongated elements 6 arranged at the periphery of the drum 3 in their mounting means 24, the members 23 for lifting the cable and the levers 22 acting on the members 23. The cam track 65 21 is a groove formed in the body of the cam 20 and comprises a succession of sectoral zones S, each comprising a part A corresponding to a extension phase during which the cable is subjected to the action of pins 25 and a corresponding part B

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during a retraction phase during which the cable is "unstuck", the levers 22 having pushed outward the members 23 for lifting the cable (see lever 22.b). The levers 22 are L-shaped. One of their ends is articulated around an axis 26 parallel to the axis 12 of the drum 3, while the other is secured to the cam track 21 by means of a stud 27, the central part of the lever being made integral with one end of the corresponding member 23 for lifting the cable.

As can be seen, the cable lifting member 23 is constituted by a U-shaped section, surrounding the extendable elongate element 6 and its mounting means 24. It is therefore subjected to the action of the levers 22 to its radial outward movement and its return to the original position, and it is guided in this movement by guide means not shown.

An embodiment of an extendable elongate member is shown in Figure 5 in partial view. It is constituted by a strap 28 made of elastomeric material provided at each of its ends with a fastener 29 carrying a threaded rod 30 for its attachment to the drum by suitable means shown in FIGS. 6, 7, 8. It is noted that in this realization the pins 25 are arranged parallel to the flat of the strap and fixed by hooking. The density of the pins is chosen according to parameters such as cable title, strand title, width, spreading rate, etc.

In Figures 6 to 9, there is shown an elongate expandable member and its mounting means on the drum. Figure 6 is a simplified longitudinal sectional view. Figure 7 is a more detailed sectional view along line a-a of Figure 6. Figure 8 is also a detailed sectional view along line b-b. FIG. 9 shows a stretchy elongate element, its mounting means and an embodiment of the means for subjecting it to repetitive extension-retraction cycles, these means being represented in three positions (9- 1, 9-2, 9-3).

The mounting means of each extendable elongate element (FIGS. 6 to 9) comprise for each end of the element a profile 32 made of a material such as stainless steel which can slide in an appropriate guide path formed at the periphery of the drum. The profile 32 is provided with an end piece 33, made of polyamide, which is integral with it. The end of the extendable elongate element 6 is fixed by screw-nut system on the end piece 33 by means of its threaded rod 30 passing through a hole 34 formed in said piece 33. This method of fixing allows adjustment of the strap tension 28 at rest. The guide path of the profile 32 is constituted, on the one hand, by rollers 35, on the other hand, by a slide 36, arranged at the periphery of the flanges 11 or on their extensions 110 (fig. 7-8 ). The profile 32 is mounted in the slide 36 by means of friction parts 37 made of plastic (fig. 7) and guided by the rollers 35 by means of guide pieces 38 (fig. 8).

In FIG. 9 and partially in FIG. 8, one can see means for subjecting an elongate extensible element to extension-retraction cycles. They consist of a connecting rod-crank system, namely the crank wheel 16 (already mentioned in the description of FIG. 3), integral with the satellite 17, itself engaged with the toothed crown 18 and a connecting rod 39 connecting the crank 16 to the corresponding profile 32. The means for fixing the connecting rod 39 to the profile 32 are visible in FIG. 8. There is a connecting rod-crank system at the end of each extendable elongated element.

In FIG. 9 in position 9-1, the elongated element is shown in maximum extension, in position 9-2 in the retracted state, and in position 9-3 in an intermediate state. Positions 9-1 and 9-2 are also representative of the relative positions of two successive elongated elements on the drum.

Another embodiment of the means for subjecting the extensible elongate elements to extension-retraction cycles is shown in FIG. 10.

Here, two consecutive extendable elongated elements 61 and 62 are actuated at each of their ends by a single rod-crank system. The foot of the connecting rod 39, moved by the crank 16, is fixed

on a toothed wheel 40 engaged in two opposite 180 ° points with two racks 411, 412, respectively secured to profiles 321 and 322 corresponding to the elongated elements 61 and 62. It can be seen that the two elongated elements deform well in the opposite direction; when the element 61 is in maximum extension (case of the figure), the element 62 is at its minimum length.

In the embodiment described above, the slides assisting each extendable elongated element during the extension and retraction phases are constituted by the profiles 32 themselves, which extend to the middle part of the elongate extensible elements . Driven by the connecting rod-crank system, each section operates a push on jumpers 42 with which it comes into contact, said jumpers being integral with the strap 28 and judiciously distributed along the latter. The pushing takes place each time in the direction of deformation of the strap, it brings about a reduction in the stretching stresses of the strap at extension and promotes a uniform retraction of the strap over its entire length in the retraction phase.

In operation, referring to FIG. 1, the cable having been put in place and the machine started, half of the extendable elongated elements 6 are in the retraction phase and in “hacking”,

the other half in the shrinking phase and in "skinning". On each drum (2, 3, 4), there is a succession of fixed sectors S, S ', ... etc., each corresponding to an extension-retraction cycle, the extension phase corresponding to a half-sector A, A '... etc., and the retraction phase to a half-sector B, B' ... etc. Either the first spreading stage S, on the drum 2, or an extendable elongate element 6 arriving in position a at the start of the sector A, it begins at this point its extension phase at the same time as the "pecking" is carried out " The extension continues throughout the course of the arc ab; thus, the cable undergoes a first phase of spreading. Arrived at point b, there is at the same time “skinning” and beginning of the retraction phase. The elongated element 6 traverses the arc bc (sector B) while retracting and the cable which is no longer subjected to the pins of this elongated element does not undergo any modification of its width. Arrived at the point, the elongated element 6 has completed its first extension-retraction cycle and begins the second (sector S '). There is again “pecking” of the cable taken at its exit width from sector A, extension of the elongated element on the path of the arc cd (sector A ') and second phase of spreading. Note that "pecking" takes place in the same place on the cable as "pecking" in a. Then on the arc of (sector B ') there is retraction with "unpicking". The extension-retraction cycles thus continue on the five active stages of the drum 2, then the three active stages of the drum 3 and finally the two active stages of the drum 4. At the machine output, at the duo 8, the cable has been subject to ten stages of spreading.

On leaving the device, the tablecloth can be collected by known means for subsequent manipulation or else supply a lapper.

The operating speed of the device depends on the cable title, its presentation and the speed of recovery of the sheet. Of course, if the web directly feeds another transformation device, the output speed will be a function of the feed speed of the other device.

By way of example, the device, according to the present description, was used for spreading a cable of continuous filaments of polyethylene terephthalate with a global title of 70 ktex, of 6.7 dtex per strand. The machine has 10 spreading stages, the spreading rate for each stage being 1.25. The width of the cable at the entrance to the first stage is 22 cm, the width of the sheet at the exit of the machine is 207.5 cm. The operating speed was 70 m / min. The tablecloth obtained is perfectly regular. Indeed, the progressive taking over of the sheet from one stage to another ensures uniform spreading of the cable. On this point, the drawbacks of known devices are avoided. In addition, the multiplication of the spreading stages makes it possible to obtain a significant overall spreading rate greater than 10, while having a limited spreading rate on each

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stage, which guarantees good resistance of the mechanical members, in particular of the elongated extendable elements with pins.

In addition, compared to the known device and cited in the prior art, the present device saves material and therefore cost and offers a reduced footprint. Indeed, for the same number of spreading stages, the first device required forty extendable elongated elements while the present only requires thirty.

In the means of extension-retraction, the replacement of the cams by connecting rod-crank assemblies, to which the present device lends itself well, also allows cost savings. In addition, the triangular arrangement of the drums results in significant space savings on the ground. Note also the rational nature of "pecking" and "pitting" taking place perpendicular to the tablecloth and using a positive control.

The device according to the invention is capable of treating any cable of continuous filaments, crimped or not, made of natural or synthetic material.

The nonwoven tablecloth obtained can be used in the usual ha-5 range of uses for nonwoven articles, for example: furniture (draperies, coverings, etc.), coating supports, clothing, padding or reinforcement (in clothing or bedding), industrial use, etc. It can be used for the production of laminated composite articles, by association by stitching or other means with other supports, textile or not. It is also possible to carry out the spreading of several superimposed cables, for example of title, appearance (crimped, uncrimped) and / or different colors.

Obviously, the invention is not limited to the example described but encompasses other embodiments of the various parts of the machine, provided that it remains within the general definition.

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Claims (10)

667 678 1. Device for spreading a continuous filament cable, characterized in that it comprises at least one spreading assembly comprising at least: - a drum driven in rotation, - elongate extendable elements integral in rotation with the drum, arranged at the periphery of the latter according to generatrices, each element being provided with at least one row of pins facing outwards, Means for subjecting the elongated elements to several successive alternating phases of extension and retraction during one revolution of the drum, Means for bringing the cable to the extendable elongated elements and means for taking up the spread cable, - Means for subjecting the cable to the action of the pins during the extension phases and removing it from their action during the retraction phases. 2. Device according to claim 1, characterized in that the means for subjecting the elongate extensible elements to several successive alternating phases of extension and retraction comprise: - a series of rod-crank assemblies, mounted at the two ends of the drum, each associated and connected to the end of at least one elongate extendable element, - a fixed toothed ring coaxial with the drum and disposed at each of the two ends thereof, - Satellites associated with each rod-crank assembly ensuring the rotation of the crank from the corresponding toothed crown. 2 3. Device according to claim 2, characterized in that each rod-crank assembly is associated and connected to the end of a single elongate element which can be extended in such a way that a round trip of the big end corresponds to a cycle extension-retraction. 4. Device according to claim 2, characterized in that each rod-crank assembly is associated and connected to the end of two consecutive extendable elongated elements so that a round trip of the connecting rod corresponds to an extension cycle -retraction and that. when an element is in extension, the other associated element is in retraction. 5. Device according to one of claims 1 to 4, characterized in that the means for supplying the cable to the extendable elongated elements comprise a curved bar and that the means for recovering the spread cable include a duo of rollers . 6. Device according to one of claims 1 to 5, characterized in that the means for subjecting the cable to the action of the pins during the extension phases and for removing it from their action during the retraction phases comprise: A member for lifting the cable adjacent and parallel to each elongate extensible element, A fixed control cam disposed at each of the two ends of the drum coaxial with the latter, said cam being provided with a cam path comprising repetitive sectoral zones, each corresponding to an extension-retraction cycle, - A lever associated with each end of each cable lifting member, said lever being, on the one hand, articulated on the drum, on the other hand, connected to the cam track and to the lifting member. 7. Device according to one of claims 1 to 6, characterized in that each elongate extensible element consists of at least one strap of elastic material. 8. Device according to one of claims 1 to 7, characterized in that each extensible elongate element are associated with two sliders in direct or indirect contact with it, said sliders being actuated by the means subjecting the elongate extensible element to extension and retraction phases, and assisting the deformation of said elongated element during these two phases. 9. Device according to one of claims 1 to 8, characterized in that it comprises several spreading assemblies arranged one after the other. 10. Device according to claim 8, characterized in that it comprises three spreading assemblies whose axes are arranged according to the vertices of an equilateral triangle.