WO2015079127A1

WO2015079127A1 - Application head for fibres, having particular redirecting means

Info

Publication number: WO2015079127A1
Application number: PCT/FR2014/000253
Authority: WO
Inventors: Alexander Hamlyn; Loïc GAILLARD
Original assignee: Coriolis Composites
Priority date: 2013-11-28
Filing date: 2014-11-18
Publication date: 2015-06-04
Also published as: FR3013626B1; FR3013626A1

Abstract

The present invention relates to an application head for fibres and an application method for fibres for producing parts made of composite material, the head comprising cutting means that are able to cut the fibres and redirecting means comprising at least one motorized drive roller (105) and a counter-roller that is actuated by an actuating system between a rest position and a redirecting position for pinching at least one fibre between the drive roller and the counter-roller. Said drive roller comprises a core (106) coupled to a motor, a ring (107) mounted so as to move angularly on said core between an initial position and a driving position in which the core drives the ring positively in rotation, and urging means (109) that apply a return force in order to urge the ring towards the initial position thereof.

Description

FIBER APPLICATION HEAD WITH PARTICULAR MEANS OF ROUTING

The present invention relates to a fiber application head for producing parts made of composite materials. The present invention more particularly relates to a fiber application head with particular fiber re-routing means. The present invention also relates to a fiber application method for producing parts made of composite material by means of a corresponding application head.

Fiber application machines are known for the contact application on a draping tool, such as a male or female mold, of a wide band formed of one or more continuous flat fibers, of the wick type, dry or impregnated with thermosetting or thermoplastic resin, especially carbon fibers, consisting of a multitude of carbon threads or filaments.

These machines conventionally comprise a displacement system of a fiber application head, said head comprising an application roller intended to come into contact against the mold for applying the strip, and a guide system for guiding the fiber or fibers. on said roll. In the case of a multi-fiber web, the head is conventionally referred to as a fiber placement head, and includes a guide system for guiding the fibers to the roll in the form of two webs and forming at the roll. a fiber web in which the fibers are substantially edge to edge. The fiber placement head conventionally comprises, as described in particular in the international application WO2008 / 132299, cutting means for individually cutting each fiber upstream of the roll, and means of rerouting upstream of the cutting means to reroute each fiber to be able to stop and resume the application of a band, as well as to choose the width of the band.

For each fiber, the cutting means comprise a planar blade which is actuated by a pneumatic cutting ram and for example disposed opposite a fixed counter-tool. The rerouting means comprise a counter-roller actuated by a cylinder of re-routing and arranged opposite a drive roller. For each sheet, the drive rollers are formed of the same drive roller, driven continuously in rotation at a given speed. Blocking means are provided for individually blocking each fiber that has just been cut, to prevent the fibers from moving, particularly under the effect of the tension of the fibers. These blocking means are conventionally arranged upstream of the rerouting means and comprise their own actuating cylinders. For the rerouting of a fiber, the blocking means associated with said fiber are controlled to their rest position to unblock the fiber, and the drive roller is controlled in the re-routing position to reroute the fiber.

These rerouting means combined with the locking means ensure a satisfactory re-routing accuracy, especially for obtaining a tape start with cutting edges of the fibers as aligned as possible. This re-routing accuracy depends in particular on the control precision of the different actuating cylinders.

The object of the present invention is to propose a solution to improve the routing accuracy of the fibers.

For this purpose, the present invention relates to a fiber application head, preferably intended to be mounted at the end of a displacement system, for application to an application surface of at least one fiber, comprising

cutting means capable of cutting, preferably individually, the fibers and,

- Rerouting means arranged upstream of the cutting means, able to reroute each cut fiber for its application to the application surface, said redirecting means comprising for each fiber at least one motorized drive roller , coupled directly or indirectly to a drive motor for driving it in a first direction of rotation, preferably continuously, and a counter-roller actuated by an actuating system between a rest position and a re-routing position for gripping at least one fiber between the roller drive and counter-roller for rerouting said fiber, characterized in that said drive roller comprises

a driving part or core, coupled to said drive motor for driving in the first direction of rotation,

a driven part or outer ring, by which said roller is in contact with the fiber in the position of re-routing of the counter-roller, and mounted to move angularly on said core on an angular deflection defined between an initial position in which at least a first bearing surface of the core is against a first bearing surface of the crown, and a driving position in which at least a second bearing surface of the core is against a second bearing surface of the crown, so that the core positively rotates the ring in the first direction of rotation,

- And biasing means applying a biasing force to urge the ring in the second direction of rotation, opposite the first direction of rotation, to its initial position, so that when the against-roller is moved from its rest position towards its re-routing position to reroute a fiber, the ring being in the initial position, the ring rotates without driving the ring gear until the ring is in the driving position, and rotates by rotating the ring when the latter is in the driving position, and when the counter-roller is moved from its re-routing position to its rest position, the crown is returned to its initial position by the biasing means.

The Applicant has noted that, in the case of prior art rerouting means, when the drive roller is controlled to press the fiber against the roller or drive roller, more or less significant slippage may occur between the fiber and the drive roller when the fiber comes in contact with it. Furthermore, this sliding phenomenon depends on the tension of the fiber, this fiber tension is not constant and varies greatly, especially as a function of the position of the head in space. This slippage on the one hand greatly reduces the re-routing accuracy and on the other hand can generate a mark on the fiber and a deterioration of the fiber. The drive roller according to the invention comprises a ring mounted on a core, as defined above, so that when the fiber contacts the crown, the ring initially remains stationary while the core rotates, until the second bearing surfaces come into contact. This delay in the rotational drive of the crown ensures optimal pinching of the fiber between the crown and counter-roller before the crown is rotated. The roller according to the invention makes it possible, in a small space requirement, to pinch the fiber in a first step between two immobile elements, namely the counter-roller and the crown, the rotational drive of the crown being carried out thereafter to reroute the fiber. The invention thus makes it possible to limit as much as possible the sliding of the fiber during its contact with the re-routing roller. The head according to the invention makes it possible to obtain better re-routing precision, and in particular a precision which is independent of the tension in the fiber and which varies little.

In addition, several rollers according to the invention can be mounted on the same motorized axis to form in the head a multi-fiber rerouting system limiting the slip and thus ensuring a good re-routing accuracy while having a limited footprint.

According to one embodiment, said head further comprises locking means, arranged upstream of the redirection means with respect to the direction of travel of the fibers, capable of blocking at least one fiber that has just been cut, and to unlock said fiber after maneuvering in its driving position of the counter-roller associated with said fiber, when the crown of the associated drive roller reaches its driving position.

Said locking means comprise at least one locking pin actuated by an actuating system between a rest position and a locking position, the locking pin being returned to its rest position when the crown of the counter-roller is in its position. driving position.

This blocking of the fiber upstream of the rerouting means is opposed to the biasing force of the biasing means, so that the crown remains stationary when the roller against is maneuver in re-routing position. Such blocking in combination with the drive roller according to the invention ensures optimum re-routing accuracy.

According to other embodiments, the fiber is not blocked when the fiber comes into contact with the ring. In such a case, the return force of the biasing means is defined so that the tension in the fiber opposes said return forces to ensure the immobilization of the crown and allow its passage from its initial position to its position drive.

According to one embodiment, the biasing means comprise at least one magnetic element mounted on the ring gear and at least one magnetic element mounted on the core, the return force consisting of a magnetic attraction force between said magnetic elements and / or a magnetic repulsion force between said magnetic elements.

According to another embodiment, the biasing means comprise at least one tension spring or a compression spring interposed between the ring and the core.

According to one embodiment, the angular displacement of the ring gear on the core, defined between the initial position and the driving position, is less than 180 °, preferably less than 90 °, better still less than 60 °, and preferably greater than 10 °, more preferably greater than 30 °.

According to one embodiment, the core has on its outer surface at least one stop, preferably at least two stops, arranged at regular angular space, each forming a first bearing surface and a second bearing surface, the ring having on its inner surface at least one abutment, preferably at least two abutments, each forming a first bearing surface and a second bearing surface.

The core and the ring preferably have several stops, preferably 2 to 4 stops, distributed at regular angular space on the inner surface of the ring and on the outer surface of the core. According to one embodiment, the ring and the core each comprise at least three stops each forming a first bearing surface and a second bearing surface, the angular clearance of the ring being preferably less than 60 °.

According to one embodiment, the stops of the core and the ring are provided with first magnetic elements generating attraction forces. Advantageously, the stops of the core and the ring are further provided with second magnetic elements generating repulsive forces.

According to one embodiment, the head is a so-called fiber placement head for application to contact on a tool of a wide band formed of several continuous flat fibers, called wicks. In this case, the head comprises an application roller and a guiding system capable of guiding a plurality of fibers towards the application roller in the form of a strip, the re-routing means comprising a plurality of re-routing rollers, each roller A drive is associated with a counter-roller for rerouting at least one fiber, preferably a single fiber, the cores of the rerouting rollers are rotatably mounted on at least one rerouting rod coupled directly or indirectly to a motor.

According to one embodiment, the guidance system comprises first and second guide means staggered in two guide planes approaching each other from upstream to downstream to guide the fibers to the roll in the form two webs of fibers and form at the roll a fiber web in which the fibers are disposed substantially edge to edge, the redirecting means comprising for each web a re-routing rod on which are mounted the cores of the re-routing rollers. Said guidance system preferably has a mean plane, the two guide planes are arranged symmetrically on either side of the mean plane.

According to one embodiment, the placement head comprises re-routing means for individually redirecting each fiber, the redirecting means comprising a system of driving roller and counter-roller by fiber. Advantageously, the head then comprises cutting means capable of individually cutting each fiber, with a blade per fiber, and of preferably blocking means capable of individually blocking each fiber, with a pad by fiber.

According to other embodiments, the head comprises drive roller and counter-roller systems for simultaneously rerouting a group of fibers, for example from 2 to 4 fibers. In this case the head advantageously comprises corresponding blades for simultaneously cutting groups of fibers and pads to block groups of fibers.

According to another embodiment, the head is provided for the application to the contact on a tool of a strip formed of a single flat fiber in the form of a wide ribbon. In this case, the head comprises a guidance system capable of guiding a single flat fiber towards the roll.

According to another embodiment, the head is provided for the non-contacting application of fibers to a mold, for example a filament winding head for the application of a strip formed of one or more ribbon type fibers.

The subject of the present invention is also a process for draping fibers on an application surface by means of a fiber application head for producing parts made of composite material, comprising steps for automatic cutting of fibers and steps automatic fiber rerouting device for rerouting each cut-off fiber, each rerouting step including moving a counter-roller from a home position to a rerouting position to clamp at least one fiber between the counter-roller and a drive roller driven in rotation and the ^maneuvering against the roller to its rest position, characterized in that the diversion step is performed with a driving roller comprising a core driven in rotation, preferably continuously, and an outer ring mounted angularly on said core between an initial position and a driving position in which e kernel positively rotates the crown, and biasing means urging the crown to its initial position,

- So that during the maneuver against the roller from its rest position to its re-routing position, the crown remains at first immobile, with a relative rotation of the crown by relative to the core, from its initial position to its driving position, the core then positively rotating the crown when the crown has reached its driving position,

- Maneuver the counter-roller to its rest position causing the return of the crown in its initial position under the effect of the biasing means.

According to one embodiment, the maneuver of the counter-roller from its rest position to its re-routing position is preceded by the blocking of the fiber upstream of the drive roller and the counter-roller by locking means operated by a rest position to a locking position, said locking means being operable to their rest position when the ring reaches its driving position.

The fibers applied may be fibers pre-impregnated with a thermoplastic or thermosetting resin, dry fibers, and / or dry fibers provided with a binder, conventionally called "binder", to impart a stickiness to the fibers during the layup. .

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 two presently preferred embodiments of the invention, with reference to the accompanying schematic drawings. on which ones :

- Figure 1 is a schematic side view of a fiber placement head according to the invention;

FIG. 2 is an exploded perspective view of the various elements constituting a drive roller of the means for rerouting a fiber of the head of FIG. 1 according to a first embodiment;

- Figure 3A is a cross sectional view of the drive roller of Figure 1, the crown in the initial position;

- Figure 3b is a view similar to that of Figure 3 A, the crown in the driving position, under the effect of an external force applied to the crown;

FIGS. 4A to 4F are diagrammatic side views of the blocking means, the means of diversion and the means of section of the head of Figure 1 illustrating the different steps for the rerouting of a fiber;

FIG. 5 is an exploded perspective view of the different elements constituting a driving roller of the means for rerouting a fiber according to a second embodiment;

- Figures 6A and 6B are schematic sectional views of the drive roller of Figure 5, respectively with the crown in the initial position and with the crown in the driving position.

FIG. 1 partially illustrates a fiber application head 1 according to the invention, provided here for the application on the application surface of a mold of a band formed of several fibers by relative displacement of the head relative to to the mold. The head 1 comprises an application roll 11, also called a compacting roll, a guide system 12 for guiding the fibers entering the head towards the roll in the form of two sheets of fibers, to form a fiber web wherein the fibers are disposed substantially edge to edge.

The guidance system comprises, for example, first guide channels and second guide channels in which pass respectively first fibers F1 of the first sheet and second fibers F2 of the second sheet. The first channels and the second channels are arranged in staggered rows, in two planes PI, P2 of guidance approaching each other from upstream to downstream so that the fibers F 1 and F 2 of the two layers are substantially disposed on edge. edge at the application roller. The PI planes, P2 guide are arranged symmetrically on either side of the plane P3 median symmetry of the guidance system. These guide channels are for example formed at the assembly interface of a central piece 121, wedge-shaped, and two side plates (not shown).

The head comprises for example a support structure (not shown) on which is mounted the guide system and by which the head can be assembled to a displacement system adapted to move the head in at least three directions perpendicular to each other. The displacement system comprises for example a robot comprising a wrist or poly-articulated arm at the end of which is mounted said application head. Alternatively, the head is fixed and the mold is able to be moved relative to the head to perform the draping operations. The fibers are conveyed from storage means (not shown) to the head via conveying means (not shown). The fiber storage means may comprise a creel in the case of fibers packaged in the form of coils. The conveying means may be formed of flexible tubes, each tube receiving a fiber in its internal passage.

The head further comprises, on either side of the guiding system, cutting means, shown schematically under the reference 2, for individually cutting each fiber passing in the guiding systems, locking means, shown schematically under the reference 3, for blocking each fiber that has just been cut, and rerouting means, shown schematically under the reference 4, to reroute individually individually to the roller each newly cut fiber.

For each fiber of a web, the cutting means comprise a blade 21 mounted at the end of the rod of a cylinder 22 of pneumatic cut. The cutting cylinder is able to move its blade from a rest position to a cutting position to cut a fiber. The cutting means comprise for example counter-tools arranged on the central part 121, vis-à-vis the cutting edges of the blades, and against which the blades abut in the cutting position. For each sheet, the cylinders are arranged in a row, and the counter-tools comprise a bar, for example of elastomeric material, housed in the central piece.

For each fiber of a web, the locking means 3 comprise a stud 31 mounted at the end of the rod of a pneumatic locking cylinder 32. The locking cylinder is able to move its block from a rest position to a blocking position to block a fiber. The locking means comprise counter-locking tools disposed on the central piece, vis-à-vis the bearing surfaces of the pads, and against which the pads abut in the locking position. For each sheet, the locking cylinders are arranged in a row, above the row of cutting cylinders, said counter tools are formed for example of the same rigid bar housed in a housing of the central part. For each fiber of a web, the rerouting means 4 comprise a counter-roller 41 actuated by a cylinder 42 for rerouting between a remote position, said rest position, in which the counter-roller is disposed at a distance from the drive roller , and a re-routing position for pressing the fiber against a drive roller 5. The counter-roller 41 is rotatably mounted on a yoke 43 mounted at the free end of the rod 42 of the rerouting cylinder. For each sheet, the rerouting cylinders and against-rollers are arranged in a row, between the row of cutting cylinders and the row of locking cylinders. The drive rollers are mounted on the same axis or drive rod 44. The two drive rods carrying the drive rollers are rotatably mounted on the central part 121. During draping operations, the drive rods are driven continuously in rotation, in the direction of rotation represented by the arrows SI. The drive rods are for example rotated by the same motor, by means of a belt mounted on the ends of the drive rods and the motor shaft.

The locking means, the rerouting means and the cutting means of the first ply and the second ply are arranged symmetrically on both sides of the plane of symmetry P3.

During draping operations, the cutting, blocking and re-routing cylinders are controlled by a control unit of the head.

According to alternative embodiments, depending on the size and the width of the deposited fibers, the means for rerouting, cutting and / or blocking for a fiber sheet are arranged in two superposed rows, said means for two adjacent fibers of the same sheet being on different rows.

According to the invention, with reference to FIGS. 2, 3A and 3B, each drive roller 5 comprises a driving portion 6 and a coaxial driven portion 7.

The driving part 6, also called core, is mounted fixed in rotation on the drive rod, shown schematically under the reference 44 in Figure 2. The core 6 is tubular and has on its outer surface 61 three protuberances or stops 63 disposed at regular angular space, and each having two opposite bearing surfaces: a first bearing surface 63a and a second bearing surface 63b. The locking in rotation of the core on the drive rod is obtained here by three studs or ribs 441 of the drive rod 44 being inserted into longitudinal grooves 64 formed on the inner surface 62 of the core. Although not shown, the cores of the drive rollers of a fiber web are mounted fixed in rotation on the same drive rod.

The driving part, also called crown 7, has a tubular shape and has an outer surface 71 through which the drive roller is intended to come into contact with a fiber, and an inner surface 72 provided with three protuberances or stops 73 each presenting two bearing surfaces: a first bearing surface referenced 73a and a second bearing surface referenced 73b. The core and the ring gear are coaxially mounted on the A-axis drive rod, so that each stopper 73 of the ring gear is disposed between two stops 63 of the core, with its first bearing surface 63a facing the first surface. 73a support a first abutment of the core and its second bearing surface 63b oriented towards the second bearing surface 73b of a second abutment of the core.

The crown 7 is mounted on the core 6 by means of two annular lateral flanges 8 arranged on either side of the abutments 63 of the core and assembled to the latter by means of screws 82 screwed into threaded holes 65 of said stops. . After assembling the flanges, the circular edge 81 of the flanges is in sliding contact with the inner surface 72 of the ring, and the abutments 73 of the ring placed between the two flanges 8 ensure the longitudinal retention of the ring on the core.

The ring gear 7 is thus rotatably mounted relative to the core 6 between a first so-called initial position, illustrated in FIG. 3A, in which each stop 73 of the ring is supported by its first bearing surface 73a against the first surface. support 63a of a stop 63 of the core 6, and a second so-called driving position, illustrated in FIG. 3B, in which each abutment of the crown is supported by its second bearing surface 73b against the second surface support 63b of a stop of the core. The crown is mounted movable in rotation relative to the core on an angular deflection βΐ defined between these two positions, this deflection βΐ being is about 45 ° in the present embodiment.

The drive roller 5 is equipped with biasing means, biasing the crown in its initial position of Figure 3A. These biasing means, designated by the general reference 9, are of the magnetic type, and comprise first permanent magnets 91a, 92a generating a magnetic attraction force between the first surfaces 63a, 73a of the abutments 63, 73 of the crown and the core, and second permanent magnets 91b, 92b generating a repulsive force between the second surfaces 63b, 73b of the ring and the core.

Each stop 63 of the crown is equipped with a first magnet 91a disposed near its first bearing surface 63a and a second magnet 91b disposed near its second bearing surface 63b. Each stop 73 of the core is equipped with a first magnet 92a disposed near its first bearing surface 73a and a second magnet 92b disposed near its second bearing surface 73b. The polarities of the first magnets 91a, 92a are defined so that the first magnets attract each other, and the polarities of the second magnets 91b, 92b are defined so that the second magnets repel each other. The first and second magnets are for example inserted in housings opening on the lateral faces of the stops 63, 73.

A description of the operation of the drive roller during the rerouting of a fiber F1 according to the invention will now be made with reference to FIGS. 4A to 4F.

FIG. 4A illustrates the cutting means, the rerouting means, and the blocking means in the case of a fiber that has just been cut. The blade 21 of the cutting means is in the rest position, and the pad 31 of the locking means is in the locking position, so as to block the fiber just cut. Regarding the re-routing means, the counter-roller 41 is in the inactive position, remote from the re-routing roller. The core 6 of the drive roller is continuously rotated in the SI direction by the drive rod. The ring 7 is in initial position and rotates with the core, the first bearing surfaces 73a of its abutments 73 resting against the first bearing surfaces 63a of the stops 63 of the core under the effect of the force of attraction of the first magnets 91a, 92a.

For the rerouting of the fiber, the locking pin 31 is held in the locking position and the locking cylinder is controlled to bring the counter-roller 41 in the active position, as shown in FIG. 4B, in order to pinch the fiber between the counter-roller and the re-routing roller. The fiber being blocked by the locking pin, the rotation of the ring in contact with the fiber is stopped, while the core driven by the drive rod continues to rotate, the first bearing surfaces 63a of the stops of the core thus move away from the first bearing surfaces 73a of the ring until the ring arrives in the active position illustrated in FIG. 4C. At the moment when the crown reaches its active position, the locking pin 71 is maneuvered to its rest position to unlock the fiber, the core with its second bearing surfaces 63b against the second bearing surfaces 73b of the crown drives positively. in rotation the crown as shown in Figure 4D. The fiber pinched between the counter roller and the crown is then rerouted, as shown by the arrow S3.

Once the fiber is fed back to the roll, more precisely to the line of contact between the roll and the mold application surface, the counter-roller is maneuvered to its rest position, as shown in FIG. 4E. Under the effect at first of the repulsive force of the second magnets 91b, 92b, then of the attraction force of the first magnets 91a, 92a, the ring returns to its initial position, by relative rotation of the ring with respect to the core in the direction opposite to SI direction, supported by its first bearing surfaces against the first bearing surfaces of the core.

For subsequent cutting of the fiber, the blade and the blocking pad are simultaneously operated by their respective cylinders, respectively in the cutting position and in the locking position, as shown in Figure 4F. A rerouting of the fiber can again be performed as described above starting from Figure 4A. By way of example, the counter-roller is provided with a coating of plastics material, such as a polyurethane. The drive wheel core and crown are metal and are equipped with neodymium magnets. Depending on the type of fiber, the outer surface of the ring is smooth, for example in the case of dry fibers or fibers preimpregnated with thermoplastic resin, or knurled, for example in the case of fibers pre-impregnated with thermosetting resin.

In an alternative embodiment, the flasks are replaced by ball bearings, each bearing comprising an inner ring and an outer ring between which are placed rolling balls. The inner ring is mounted fixed in rotation on the core and / or the outer ring is fixedly mounted in rotation in the ring. For example, one of the ball bearings is fixedly mounted on the core, for example by forcibly engaging the core, while the other ball bearing is fixedly mounted in the ring.

In an alternative embodiment, to facilitate assembly and maintenance operations and / or replacement of the drive rollers, the drive rod is provided with splines cooperating with corresponding grooves of the cores to lock in rotation the drive rollers on the drive rod. The drive rollers are threaded from one end of the drive shaft by interposing spacer rings.

In another alternative embodiment, the cores of the drive rollers and the drive rod are formed of a single piece.

FIGS. 5, 6A and 6B illustrate a second embodiment of a drive roller 105 according to the invention, which differs mainly from the first embodiment in that the biasing means are here of elastic type, and comprise traction springs.

As before, the drive roller comprises a core 106 and a ring 107. The core is fixedly mounted in rotation on a drive rod 144, and is provided on its outer surface 161 with three stops 163, arranged at regular angular space. and each having a first bearing surface 163a and a second bearing surface 163b. The crown 107 has an outer surface 171 and a internal surface 172 provided with three stops 173 each having a first bearing surface 173a and a second bearing surface 173b. The mounting of the crown on the core is also provided by flanges 108, with screws 182 screwed into tapped holes 165 of said stops.

The ring 107 and the core 106 are rotatable relative to one another between an initial position, illustrated in FIG. 6A, in which each abutment 173 of the ring is supported by its first surface 173a against the first 163a surface of a stop 163 of the core 106, and a driving position, illustrated in Figure 3B, wherein each abutment 173 of the ring is supported by its second bearing surface 173b against the second bearing surface 163b of a stop of the core. Angular deflection β2 is about 45 ^° in the present embodiment.

The biasing means comprise three traction springs 109, each spring being assembled by a first end 191 to a stop 173 of the ring and by its second end 192 to a stop of the core, so as to urge the crown into its rest position. . This assembly is for example obtained by placing the curved ends of the springs around pads 166, 176 of the abutments.

When the roller against is brought into the active position, the locking pin being in the locked position, the ring 107 is locked in rotation and the core 106 rotates relative to the ring to the driving position of the ring. During this rotation, the springs 109 stretch. When the crown arrives in the driving position, the locking stud is operated in the inactive position to unlock the fiber and allow its re-routing, the core positively rotating the crown. When the drive counter-roller is maneuvered in the rest position to stop the re-routing of the fiber, the crown automatically returns to its initial position under the effect of the elastic restoring force of the springs 107.

In order for the spring to remain in a substantially straight configuration in the driving position of the core, while ensuring a compact compact drive roller, the core is provided with notches 167 for receiving the springs in the stretched position. Although the invention has been described in connection with particular embodiments, it is obvious that it is not limited thereto and that it includes all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims

Fiber application head (1) for application to an application surface of at least one fiber, comprising

cutting means (2) capable of cutting the fibers and

- rerouting means (4), comprising at least one motorized drive roller (5, 105), coupled to a drive motor for driving in a first direction of rotation, and a counter-roller (41) actuated by an actuating system (42) between a rest position and a re-routing position for clamping at least one fiber (F1) between the drive roller and the counter-roller to reroute said fiber, characterized in that said drive roller includes

a core (6, 106) coupled to said drive motor,

- an outer ring (7, 107) mounted to move angularly on said core between an initial position in which at least a first bearing surface (63a, 163a) of the core is against a first bearing surface (73a, 173a) of the crown, and a driving position in which at least a second bearing surface (63b, 163b) of the core is against a second bearing surface (73b, 173b) of the crown, so that the core drives positively in rotation the crown,

- and biasing means (9, 109) applying a biasing force to bias the crown to its initial position so that, when the counter-roller is moved from its rest position to its re-routing position to reroute a fiber, the core rotates without driving the crown until the crown is in the driving position, and rotates by rotating the crown when the latter is in the driving position, and when the counter-roller is moved from its position of rerouting to its rest position, the crown is returned to its initial position by the biasing means.

2. Head according to claim 1, characterized in that said head (1) further comprises blocking means (3), arranged upstream of rerouting means, capable of blocking at least one fiber (Fl) coming from cut, and to unblock said fiber, after maneuver in its position of rerouting of the counter-roller (41) associated with said fiber, when the ring (7, 107) of the drive roller (5, 105) associated reaches its driving position.

3. Head according to claim 1 or 2, characterized in that the biasing means (9) comprise at least one magnetic element (92a, 92b) mounted on the ring gear (7) and at least one magnetic element (91a, 91b). mounted on the core (6), the return force consisting of a magnetic attraction force and / or a repulsive magnetic force between said magnetic elements.

4. Head according to one of claims 1 to 3, characterized in that the biasing means comprise at least one tension spring or a compression spring (109) interposed between the ring (107) and the core (106).

5. Head according to one of claims 1 to 4, characterized in that the core (6, 106) has on its outer surface (61, 161) at least two stops (63, 163), each forming a first surface of support (63a, 163a) and a second bearing surface (63b, 163b), the ring gear (7, 107) having on its inner surface (72, 172) at least two stops (73, 173), each forming a first bearing surface (73a, 173a) and a second bearing surface (73b, 173b).

6. Head according to claims 3 and 5, characterized in that the stops (63, 73) of the core (6) and the ring (7) are provided with first magnetic elements (91a, 92a) generating attraction forces .

7. Head according to claim 6, characterized in that the stops (63, 73) of the core (6) and the ring (7) are provided with second magnetic elements (91b, 92b) generating repulsive forces.

8. Fiber application head according to one of claims 1 to 4, characterized in that it comprises an application roller and a guide system is adapted to guide a plurality of fibers (F1, F2) to the application roller (11) in the form of a strip, the rerouting means comprising a plurality of rerouting rollers, each drive roller is associated with a counter-roller for rerouting at least one fiber, the cores of the rerouting rollers are rotatably mounted on at least one re-routing rod coupled to a motor.

9. A process for draping fibers on an application surface by means of a fiber application head (1) for producing composite material parts, comprising automatic fiber cutting steps and automatic re-routing steps of fibers for rerouting each cut-off fiber, each rerouting step comprising operating a counter-roller (41) from a rest position to a rerouting position to clamp at least one fiber between said counter-roller and a driving roller (5, 105) driven in rotation, then the operation of the counter-roller towards its rest position, characterized in that the re-routing step is performed with a drive roller (5, 105) comprising a rotatably driven core (6, 106) and an outer ring (7, 107) movably angularly mounted on said core between an initial position and a driving position in which the core positively drives and n rotation of the crown, and biasing means (9, 109) urging the crown towards its initial position,

- So that during the maneuver against the roller from its rest position to its re-routing position, the crown remains at first immobile, with a relative rotation of the ring relative to the core, from its initial position until at its driving position, the core then positively rotating the crown when the crown has reached its driving position,

10. Draping method according to claim 9, characterized in that the maneuver against the roller (41) from its rest position to its re-routing position is preceded by the blocking of the fiber upstream of the drive roller (5, 105) and against the roller (41) by locking means (3) operated from a rest position to a locking position, said locking means being operated to their rest position when the ring (7, 107) reaches his training position.