EP2709831A1

EP2709831A1 - Fibre application head including a segmented compaction roller

Info

Publication number: EP2709831A1
Application number: EP12728640.9A
Authority: EP
Inventors: Johann Caffiau; Loïc GAILLARD; Yvan Hardy
Original assignee: Coriolis Composites SAS
Current assignee: Coriolis Composites SAS
Priority date: 2011-05-20
Filing date: 2012-05-15
Publication date: 2014-03-26
Also published as: US9248591B2; US20140083620A1; FR2975334A1; KR20140057494A; JP2014519995A; WO2012160269A1; FR2975334B1

Abstract

The invention relates a fibre application head for a fibre application machine for producing parts from composite materials. The head comprises a compaction roller including multiple independent roller segments (3) mounted side by side on an axial rod. Each roller segment comprises a central tubular portion (31) by means of which the segment is mounted on the axial rod, a peripheral tubular portion (32) having a cylindrical external surface and one or more curved spring plates (40) disposed between the external surface (31a) of the central portion and the internal surface (32b) of the peripheral portion.

Description

FIBER APPLICATION HEAD WITH SEGMENTED COMPACTION ROLL

The present invention relates to a fiber application head for a fiber application machine for producing parts made of composite materials, and more particularly to a head equipped with a so-called segmented compacting roller comprising a plurality of independent roller segments.

Fiber application machines, commonly known as fiber placement machines, are known for contacting drape tools, such as a male or female mold, with a wide web of multiple flat fibers. continuous, ribbon type, dry or impregnated with thermosetting or thermoplastic resin, in particular carbon fibers, consisting of a multitude of carbon threads or filaments.

These machines are used to produce preforms formed of several superimposed folds, each fold being formed by draping on the mold of one or more joined strips. In the case of a lay-up of fibers pre-impregnated with resin, the preform, said pre-impregnated, is cured or polymerized by passing through an oven to obtain a piece of composite material. In the case of so-called dry fibers, not pre-impregnated with resins possibly comprising a very small amount of so-called binding resin, to impart a tackiness to the fibers during draping, the resin is injected or infused into the dry preform before the step hardening.

These machines, as described in the patent document WO2006 / 092514, conventionally comprise a fiber application head, a displacement system of said fiber application head, fiber storage means, and conveyance means. fibers for feeding the fibers of said storage means to the application head.

The fiber application head conventionally comprises an application roller, also called a compaction roller, intended to come into contact with the mold for applying the web, and fiber guiding means on said application roller. The head further generally comprises a heating system for heating the fibers. The compaction roller presses the fiber web against the application surface of the mold, or against the previously deposited fiber web or strips, in order to facilitate the adhesion of the strips deposited between them, as well as to gradually evacuate the trapped air between the deposited tapes. The heating system provides heating of the fiber web, and / or the mold or strips already applied upstream of the compaction roller, just before compaction of the web, to at least soften the prepreg or the bonding resin, and thus promote the adhesion of the strips together.

The displacement system ensures the displacement of the application head in at least three directions perpendicular to each other. The displacement system may be formed by a standard six-axis robot-type poly-articulated arm, arranged on the ground or mounted on a linear axis, with an end wrist to which the application head is attached, or by a Cartesian robot. gantry type equipped with an end wrist carrying the application head.

In the case of fibers packaged in the form of reels, the fiber storage means conventionally comprise a creel or bobbin cabinet. The creel can be placed on the ground close to the application head, for example in the case of a standard fixed robot, or can be mounted on an element of the displacement system, for example on one of the carriages of the Cartesian robot or on a follower carriage sliding on the linear axis of the standard robot.

To ensure substantially uniform compaction over the entire width of the strip, the fiber placement head advantageously comprises a compacting roller adapted to adapt to the application surface, in particular to convex and / or concave application surfaces. .

In the case of thermosetting resins, the prepreg fibers are simply heated to soften them, typically at temperatures of the order of 40 ° C. At these temperatures, the compacting roller is advantageously made of a material said to be flexible, elastically deformable, generally of elastomer material, so as to be deformed by matching the profile of said surfaces.

In the case of thermoplastic resins, the pre-impregnated fibers must be heated to higher temperatures, at least up to the melting temperature of the resin, of the order of 200 ° C for resins of the nylon type, and up to about 400 ° C for resins of PEE type. Due to the high heating temperatures, the fiber placement heads are equipped with heat-resistant metal compaction rollers.

In order to be able to adapt to the profile of the application surface, it has been proposed, in particular in US Pat. No. 6,390,169, segmented metal compacting rollers comprising a plurality of independent roller segments mounted side by side on the same axial rod. each segment being displaceable on said axial rod, perpendicular thereto, independently, and resiliently biased against the application surface by resilient means, such as expandable bag systems.

These segmented metal rollers, however, are complex in structure and implementation.

The object of the present invention is to provide a solution to overcome the aforementioned drawbacks, which allows in particular the implementation of a wide variety of resins, both thermosetting and thermoplastic, with a substantially uniform compression of the applied band, which is simple design and realization.

To this end, the present invention provides a fiber application head for a fiber application machine, comprising a compacting roller, said compacting roller comprising a plurality of independent roller segments mounted side-by-side on an axial rod by the ends. of which the compacting roller is mounted, optionally rotatable, on a support structure of the fiber placement head, characterized in that each segment of rolls comprises

a tubular central portion, of axis Al, of rigid material, through which said segment is mounted on the axial rod, said central portion having an internal passage in which said axial rod of the roller passes,

a tubular peripheral part, of axis Al, of rigid material, having a cylindrical outer surface constituting the cylindrical outer surface of the segment through which said segment is able to come into contact against an application surface, and

one or more curved spring blades, also called spiral spring blades, of rigid material, preferably identical, arranged between the outer surface of the central portion and the inner surface of the peripheral portion.

According to the invention, the fiber application head is equipped with a segmented roller whose peripheral portions of the segments are able to move independently of each other perpendicular to the axis of the axial rod, by means of one or more curved spring blades interposed between said peripheral portions forming the outer surface of the segments coming against the application surface to be draped and central tubular portions of the segments for mounting said segments on the axial rod.

Each leaf spring, preferably of rectangular section, is fixed by a first end to the outer surface of the central portion, its second end being in contact with the inner surface of the peripheral portion, and possibly fixed thereto, the convex surface preferably the blade is oriented towards the outside.

Such segments, with a spring blade system to allow this freedom of movement perpendicular to the axis of the axial shaft, allow to obtain a simple compaction roll of design and implementation.

A machine equipped with a roller according to the invention offers the possibility of using a wide variety of thermosetting or thermoplastic resins combined with a wide variety of fibers, synthetic or natural, hybrid or otherwise, including fibers commonly used in the field of composites, such as glass fibers, carbon, quartz, and aramid fibers.

Preferably, each blade extends substantially tangentially from the outer surface of the central portion and substantially tangentially from the inner surface of the peripheral portion.

In the case of several blades, these are preferably fixed at regular angular intervals on the outer surface of the tubular peripheral portion.

Preferably, the segments of the roll are identical.

According to one embodiment, each segment comprises a plurality of curved spring blades, preferably each curved spring leaf extends over at least a quarter turn of the perimeter of the central portion, preferably over at least one third of the perimeter turns, ie the angle says blade between the point of attachment of the leaf spring to the central portion and the point of attachment of the blade to the peripheral portion is at least 90 °, preferably at least 120 °, and / or the spring blade assembly extending over at least one turn around the perimeter of the central portion, i. e the sum of said blade angles is greater than or equal to 360 °. For example, in the case of three identical flexible blades, each blade extends over at least one third of a turn.

According to one embodiment, each curved spring leaf extends over at least one third of a circumference of the perimeter of the peripheral portion.

According to another embodiment, each segment comprises a single leaf spring having more than one turn, the leaf spring extends over more than one revolution of the perimeter of the central portion. Said spring blade is of spiral spring flat type, non-contiguous turn. When the segment is at rest, that is to say without external force applied to said segment, outside its ends fixed to the central part and the peripheral part, the blade is not in contact with the outer surface of the central part, nor with the inner surface of the peripheral part, and in the case of a multi-turn plate, the turns are without contact between them. The spring blade has a substantially identical radial stiffness in all radial directions. According to one embodiment, the curved spring blade comprises less than two turns, ie a first complete turn starting from the central part, extending by a second incomplete turn, extending for example on less than half a turn of the perimeter. .

According to one embodiment, the thickness of the blade is substantially equal to the thickness of the central portion and the peripheral portion.

According to one embodiment, the curved spring leaf (s) are fixed to the central part and the blade (s) being formed in one piece.

According to one embodiment, each leaf spring extends tangentially from the central portion, said central portion having a substantially circular hole at the junction of the leaf spring to the central portion to reduce the stress concentrations at said junction. According to another embodiment, each leaf spring is formed of a separate piece from those forming the central portion and the peripheral portion, each blade being preferably attached to the central portion by an assembly system, for example tail type dove.

According to one embodiment, the peripheral portion is formed of a part distinct from that of the central portion, said peripheral portion having for example a U-shaped cross section.

According to another embodiment, each curved spring blade is fixed by a first end to the outer surface of the central portion, each blade coming against the inner surface of the peripheral portion and being able to slide against the latter, each blade being of preferably resiliently bearing against said surface in the rest position of the segment. In the case of a peripheral portion of U-shaped section, the blade or blades are arranged between the two branches of the U.

According to another embodiment, for each segment, the spring blades are attached to the peripheral portion and the central portion, the peripheral portion, the central portion and the spring blade or blades are preferably formed in one piece, the or the blades being obtained by making one or more cuts in a disk of rigid material. Preferably, the peripheral portion also comprises one or more circular holes for limiting the stress concentrations at the junction between the spring blades and the peripheral portion.

According to one embodiment, each segment comprises stop means capable of limiting the radial displacement of the peripheral portion relative to the central portion.

According to one embodiment, the abutment means comprise for each segment at least one disc of rigid material, integral with the central portion and / or mounted on said axial rod, adapted to abut against a circular portion of the inner surface of the peripheral portion, said circular portion being for example formed by the free edge of a sidewall of the U-section peripheral portion.

According to one embodiment, said segments are made from one or more rigid materials, preferably resistant to heat, preferably the segments are metallic, each formed from one or more metal parts. The present invention also relates to a fiber application machine comprising

a fiber application head comprising a compacting roller and means for guiding the fibers on said application roller, in particular in the form of a strip of several adjoining fibers, and preferably

a displacement system for moving said fiber application head, as well as possibly fiber storage means, and fiber routing means for conveying the fibers of said storage means to the application head,

characterized in that it comprises a head as defined above.

The present invention also relates to a compacting roller as described above for a fiber application head.

The invention will be better understood, and other objects, details, features and advantages will become more clearly apparent from the following detailed explanatory description of particular embodiments currently preferred of the invention, with reference to the accompanying schematic drawings, on which ones :

- Figure 1 is a schematic perspective view of a head according to the invention during the application of a fiber web on a non-planar application surface;

FIG. 2 is a diagrammatic perspective view of the compaction roll of the head of FIG. 1, said roll comprising segments, referred to as monoblocks, with a single leaf spring according to a first embodiment;

FIG. 3 is a schematic side view of FIG. 1, illustrating the radial displacement of the peripheral portions of the segments;

- Figure 4 is a sectional view of a segment of the roller of Figure 2;

- Figures 5 and 6 are schematic side views of monobloc segments with a single leaf spring according to two embodiments;

- Figure 7 is a side view of a one-piece segment with a plurality of spring blades according to a second embodiment; - Figure 8 is a side view of a one-piece segment with a plurality of spring blades according to an alternative embodiment;

Fig. 9 is a perspective view of a roll segment according to a third embodiment, said multi-leaf spring segment being formed of a plurality of separate members;

FIG. 10 is an exploded perspective view of the various constituent elements of the segment of FIG. 9;

- Figure 11 is a side view of the segment of Figure 9, the segment being at rest;

- Figure 12 is a view along the section plane XII-XII of Figure 11;

FIG. 13 is a side view of the segment of FIG. 11 when the segment is brought to bear against an application surface;

Figure 14 is a side view of an element of the segment of Figure 9;

- Figures 15 and 16 are respectively a side view and a front view of a roller segment according to an alternative embodiment of the third embodiment;

- Figure 17 is a sectional view along the plane XVII-XVII of Figure 16; and,

- Figure 18 is a side view of the central portion of the segment of Figure 15.

With reference to FIGS. 1 to 3, the fiber placement head 1 comprises fiber guiding means and a compaction roller 2. The guiding means guides the fibers entering the head towards the compacting roll in the form of a fiber web, the fibers of the web being arranged side by side in a substantially contiguous manner. By moving the head, by means of a suitable displacement system (not shown), such as a poly-articulated arm, of the six-axis robot type, the compaction roller is brought into contact with the application surface 91 9 of draping tool to apply the strip formed of several fibers.

The compacting roller according to the invention comprises a plurality of identical segments 3 of roller mounted side by side on an axial rod 8 of axis B, for example eight segments, referenced from 3a to 3h in Figure 3. In a manner known per se, the roller is mounted by the ends of its axial rod on a support structure of the fiber placement head. The rod 8 is for example hollow and is formed of a rigid central tube of circular section, for example metal, equipped for example at the end of bearings for its rotatable mounting about its axis B on the support structure.

With reference in particular to FIG. 4, each segment 3 comprises a rigid tubular central portion 31 and a coaxial rigid tubular peripheral portion 32, resiliently connected to one another by a spring blade 40, the axis Al of the portion central 31 and the axis A2 of the peripheral portion being merged when the segment is said to rest, without external force applied to said segment.

The central portion 31 has an inner passage 31b of circular section through which said segment is mounted on the axial shaft, free in rotation. In a variant, each segment is mounted on the rod by means of a bearing system, in particular of ball type.

The tubular peripheral portion 32 has a cylindrical outer surface 32a through which said segment is adapted to come into contact with the application surface.

The spring blade 40, called curved or spiral, is of the spiral spring flat type, non-contiguous turn, of rectangular section, and is assembled by a first end to the outer surface 31a of the central portion 31 and by its second end to the inner surface 32b of the peripheral portion 32, the convex surface of the blade being oriented outwards, that is to say on the opposite side to the axis Al of the central part, towards the inner surface of the part peripheral.

The leaf spring extends over more than one revolution of the perimeter of the central part, and thus has a first complete turn 41 extending substantially tangentially from the outer surface 31a of the central part, extending by a second incomplete turn or portion of turn 42 extending over about a third of a turn. This portion of turn extends substantially tangentially from the peripheral portion. The angle β between the zone or point of attachment of the blade spring at the central portion and the zone or point of attachment of the blade to the peripheral portion is thus about 120 °. In the present embodiment, the so-called monobloc segment is formed in one piece, from a metal disc of thickness e, having two opposite planar main surfaces, in which cutouts are made to create the internal passage, and a spiral slot 5 to form the leaf spring. The slot has a substantially constant radial dimension or height, except at its end portions, so that the leaf spring has a substantially identical radial stiffness in all radial directions.

According to an alternative embodiment, circular holes (not shown) are formed at the ends of the slot in order to reduce the stress concentrations at these ends, and thus limit the risk of tearing.

The segments are mounted on the rod, substantially flat against each other by their main surfaces, possibly interposing wedges. To limit or eliminate unbalance, the segments are mounted on the axial rod being angularly offset relative to each other so that the center of gravity of all segments is disposed substantially along the axis B of the rod. Means for holding between two adjacent segments, formed for example by the aforementioned wedging washers, make it possible to maintain these angular offsets. In a variant, each segment has holes that are judiciously formed on the central portion and the peripheral portion so that the center of gravity of each segment is substantially disposed along the axis B.

The segmented compacting roller adapts to variations in the curvature of the application surface, as illustrated in FIG. 3, and thus makes it possible to apply a substantially uniform pressure to the entire deposited strip. Depending on the application surface, under the effect of the compacting force applied by the head, the spring blade is deformed elastically, the peripheral portion 32 of each segment moves radially upwards, its axis A2 shifting by relative to the axis B of the stem.

The maximum radial displacement of the central portion 31 is defined by the abutment of the central portion 31 against the first turn 41 of the leaf spring, this first turn 41 being itself abutting against the peripheral portion 32, possibly via the portion 42 of coil interposed between the latter two 41, 32.

FIGS. 5 and 6 illustrate two alternative embodiments of a monobloc segment 103, 203, in which the central portion 131, 231 and the peripheral portion 132, 232 are connected to one another by a single spiral spring blade comprising more than two turns. Segment 103 of FIG. 5 comprises a spring blade 140 comprising a little more than four turns, ie four complete turns 141-144 and a turn portion 145 extending here over an angle β of approximately 20 °. Segment 203 of FIG. 6 comprises a spring blade 204 comprising a little more than two turns, ie two complete turns 241, 242 and a turn portion 243 extending here over an angle β of approximately 20 °. The segments 103, 203 are formed in one piece from a disc, the spring blades being obtained by making a slot 105, 205.

FIG. 7 illustrates a one-piece roll segment 303 according to a second embodiment, in which the central portion 331 and the peripheral portion 332 are connected to one another by a plurality of spring blades 340. Each leaf spring extends over more than one half-turn perimeter of the central portion 331, the angle a between the blade attachment zone is springing at the central portion and the blade attachment zone springing at the inner surface of the peripheral portion is more than 180 °, for example the order of 210 °. The segment comprises three identical spring blades arranged at regular angular spacing from each other, the points of attachment of the blades to the central portion being arranged at 120 ° from each other, the attachment points of the blades to the peripheral portion being arranged at 120 ° from each other. The segment 303 is formed in one piece from a disc, the spring blades being obtained by making several cuts.

FIG. 8 illustrates a segment 403 of one-piece roll with several spring blades 440 according to an alternative embodiment, in which the central portion 431 and the peripheral portion 432 are connected to one another by six identical spring blades 340, the points fixing the blades to the central portion being arranged at 60 ° from each other. Each leaf spring extends over more than a quarter turn around the perimeter of the central part 431, the angle a is more than 90 °, for example of the order of 100 °. The segment 403 is formed in one piece from a disc, the spring blades being obtained by making several cuts.

Figures 9 to 14 illustrate a segment 503 of a roller according to a third embodiment.

The segment comprises a central portion 531 of axis A1 and a peripheral portion 532 of axis A2 connected to one another by a plurality of leaf spring 540, five in the illustrated embodiment. The blades are fixed to the central part, the blades and the central part being formed from a first metal part. The peripheral portion is formed from a second metal piece distinct from the first piece.

The peripheral portion 532 is in the form of a generally U-shaped cross-section ring, with a base 5321 whose outer surface constitutes the cylindrical outer surface 532a through which said segment is able to come into contact with the surface of the surface. application, and two lateral branches 5322 extending radially inwardly from said base.

The central portion 531 has a cylindrical internal passage 531b, the blades extend tangentially from the outer surface of the central portion. Each spring blade extends about a third of a circumference of the perimeter of the central portion 531, the angle a between the blade attachment zone is springing at the central portion and the free end 540a of the blade is of the order of 150 °. The five spring blades are arranged at regular angular spacing on the outer surface 531a, the points of attachment of the blades to the central portion being arranged at 72 ° from each other.

The first piece forming the leaf spring 540 and the central portion 531 is mounted in the second piece forming the peripheral portion 532, the end portions of the blades bearing substantially tangentially against the inner surface 532b cylindrical of the peripheral portion formed by the inner surface of the base 5321, said end portions being positioned between the two branches 5322 of the peripheral portion.

The central portion 531 has circular holes 521c at the junction regions of the spring blades at the central portion, so that to reduce the stresses exerted at said junctions, and thus reduce the risk of tearing.

At rest, as shown in Figure 11, the peripheral portion and the central portion are coaxial. The spring blades are in contact and resiliently bearing against the inner surface 532b of the peripheral portion. When the segment is pressed against an application surface, as illustrated in FIG. 13, the spring blades allow a radial displacement of the peripheral part, its axis A2 shifting with respect to the axis Al of the part peripheral.

In order to limit the radial displacement of the central part, and thus avoid excessive elastic deformation of the spring blades, two annular disks 507 are arranged on either side of each segment. Each disk comprises an internal passage 507b for its mounting on the axial rod of the roller, and a circular outer edge 507a adapted to abut against the circular edge 5322a of a branch of the peripheral portion. The outer diameter of the disk is defined so that its outer edge 507a is disposed at a distance from the outer edge of the branches when the segment is at rest, as illustrated in FIG. 1. The maximum radial displacement of the central portion is defined by coming into abutment of the discs against the branches of the peripheral portion, as shown in Figure 13. In this abutment position, all the blades remain resiliently bearing against the peripheral portion. The segments are mounted on the axial rod by interposing a disc between two successive segments. The thickness of a disc is defined so that each disc inserted between two successive segments is able to abut against a branch of each segment. Each disk is preferably rotatably mounted on the central portion of a segment, for example by means of screws.

Such an assembly of the blades, in which the spring blades are in contact with the peripheral portion, allows a sliding between the peripheral portion and the spring blades. This sliding avoids the stress concentrations at the ends of the blades and allows different speeds of rotation of the peripheral parts of the segments, especially during pivoting of the head substantially parallel to the application surface. The ends of the blades are advantageously bent inwards to facilitate this sliding. In a variant, replacing the peripheral portion of U-shaped section to guarantee the so-called axial blocking of the peripheral portion and of the central portion, the peripheral portion has a generally T-shaped section, the foot of the T extending radially towards inside. Each end portion of the leaf spring comprises a slot for the passage of the foot of the T and comes to bear on either side of the foot against the inner surfaces of the bar T.

Figures 15 to 18 illustrate a segment 603 according to an alternative embodiment of the third embodiment.

The segment 603 comprises, as previously, a central portion 631 of axis A1, in the form of a generally U-shaped cross-section ring and a peripheral portion 632 of axis A2 connected to one another by a plurality of blades. spring 640, in particular six spring blades. The segment 603 differs from that described above in that each blade 640 is formed of a part distinct from that constituting the central portion. Each leaf spring is fixed at one end to the central portion by a dovetail type assembly system. Each end blade has a protrusion 646 adapted to be housed in a groove 63 ld of corresponding shape formed on the outer surface 631a of the central portion and opening on at least one of the opposite major faces of the central portion. In the present embodiment, the grooves open on the two main faces, the spring blades being engaged laterally in the grooves by one of the main faces. The blades are mounted at regular angular spacing on the central portion, at 60 ° from each other, and each extend over an angle α of about 120 °. As previously, the end portions of the spring blades come between the branches 6322 of the peripheral portion bearing against the inner surface 632b of the base 6321 of the peripheral portion. Disks 607, able to abut by their outer edge 607a against the edge 6322a branches, further serve to ensure the maintenance of spring blades in the grooves 63 ld. This embodiment makes it possible to use a rigid material, in particular a metal material, which is perfectly suitable for producing spring blades, which is different from the rigid material or materials, in particular metal, used for producing the central part and the peripheral part. Although the invention has been described in connection with several particular embodiments, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims

A fiber application head (1) for a fiber application machine, comprising a compacting roller (2), said compacting roller comprising a plurality of segments (3, 103, 203, 303, 403, 503, 603). of independent rollers mounted side by side on an axial shaft (8), characterized in that each segment of rolls comprises

a central tubular portion (31, 131, 231, 331, 431, 531, 631) by which said segment is mounted on the axial rod,

a tubular peripheral portion (32, 132, 232, 332, 432, 532, 632) having a cylindrical outer surface and

one or more curved spring blades (40, 140, 240, 340, 440, 540, 640) disposed between the outer surface (31a, 531a, 631a) of the central portion and the inner surface (32b, 532b, 632b) of the peripheral part.

2. Head according to claim 1, characterized in that the convex surface of the leaf spring (40, 140, 240, 340, 440, 540, 640) is oriented outwards.

3. Head according to claim 1 or 2, characterized in that each leaf spring (40, 140, 240, 340, 440, 540, 640) extends substantially tangentially from the outer surface of the central portion (31, 131, 231, 331, 431, 531, 631), and / or substantially tangentially from the inner surface of the peripheral portion (32, 132, 232, 332, 432, 532, 632).

4. Head according to one of claims 1 to 3, characterized in that each leaf spring (40, 140, 240, 340, 440, 540, 640) is fixed to the central portion (31, 131, 231, 331, 431, 531).

5. Head according to one of claims 1 to 4, characterized in that each segment is rotatably mounted on the rod (8) axial.

6. Head according to one of claims 1 to 5, characterized in that each segment (303, 403, 503, 603) comprises a plurality of spring blades (340, 440, 540, 640) curved.

7. Head according to claim 6, characterized in that each leaf spring (340, 540, 640) curved extends over at least one third of a circumference of the perimeter of the peripheral portion.

8. Head according to one of claims 1 to 5, characterized in that each segment (3, 103, 203) comprises a single leaf spring having more than one turn.

9. Head according to one of claims 1 to 8, characterized in that the or curved spring blades (40, 140, 240, 340, 440, 540) are fixed to the central portion (31, 131, 231, 331). , 431, 531), the central portion and the at least one blade being formed in one piece.

10. Head according to claim 9, characterized in that each leaf spring extends tangentially from the central portion, said central portion having a substantially circular hole (531c) at the junction of the leaf spring to the central portion to reduce the stress concentrations at said junction.

1 1. Head according to one of claims 1 to 10, characterized in that each leaf spring (640) is formed of a separate part from those forming the central portion (631) and the peripheral portion (632).

12. Head according to one of claims 1 to 1 1, characterized in that the peripheral portion (532, 632) is formed of a separate part from that of the central portion (531, 631).

13. Head according to one of claims 1 to 12, characterized in that each curved leaf spring (540, 640) is fixed by a first end to the outer surface of the central portion, each blade coming against the inner surface of the peripheral part and being able to slide against the latter.

14. Head according to claim 9 or 10, characterized in that for each segment (3, 103, 203, 303, 403), the peripheral portion, the central portion and the spring blade or blades are formed in one piece, the blade or blades being obtained by making one or more cuts in a disk of rigid material.

15. Head according to one of claims 1 to 14, characterized in that each segment comprises abutment means (507, 607) adapted to limit the radial displacement of the peripheral portion relative to the central portion.

16. Head according to claims 13 and 15, characterized in that the abutment means comprise for each segment at least one disc (507, 607) adapted to abut against a circular portion of the inner surface of the peripheral portion.

A fiber application machine comprising a fiber application head comprising a compacting roller and fiber guiding means on said application roller, characterized in that it comprises a head according to one of the claims. 1 to 16.