WO2014096562A2

WO2014096562A2 - Method for producing preforms from fibers provided with a binder, and corresponding machine

Info

Publication number: WO2014096562A2
Application number: PCT/FR2013/000337
Authority: WO
Inventors: Alexander Hamlyn
Original assignee: Coriolis Composites
Priority date: 2012-12-21
Filing date: 2013-12-12
Publication date: 2014-06-26
Also published as: WO2014096562A3; FR2999973B1; FR2999973A1

Abstract

The present invention relates to a method for producing preforms by draping fibers over a draping surface, including feeding at least one dry fiber (9) from a storage and dispensing system (3) to a draping head (2) for draping said fiber onto a draping surface, characterized in that it includes: during the draping of a fiber, applying a binder (8) onto said fiber, preferably in the form of at least one thread or at least one strand; moving the fiber with the binder to the draping head; and heating said fiber with the binder so as to enable the adhesion of said fiber to the draping surface and/or to one or more previously draped fibers provided with the binder. The invention also relates to a corresponding draping machine and to a method for creating composite-material parts from such preforms.

Description

PROCESS FOR MAKING PREFORMS FROM FIBERS HAVING A BINDER, AND MACHINE

CORRESPONDENT

The present invention relates to a method of producing preforms by lay-up on a drape surface of fibers provided with a binder. The present invention also relates to a process for producing composite material parts from such preforms, and a fiber draping machine for producing such preforms.

Fiber applicator or draping machines are known for automatically draping on draping tools, such as a male or female mold, a broad band formed of one or more fibers, in particular continuous fibers. flat ribbon type, in particular carbon fibers consisting of a multitude of carbon threads or filaments.

These machines conventionally comprise a fiber application head comprising guiding means for guiding the fiber or fibers to the draping surface. These machines further comprise fiber storage means, and routing means for conveying fibers from said storage means to the head, and possibly a moving system of the drape head. In the case of a band formed of several fibers, also called bits, the means for guiding the head make it possible to bring the fibers in the form of a strip to the draping surface, in which the fibers are arranged in a substantially parallel manner. edge to edge, or with a defined spacing between two adjacent fibers. For draping in contact with the fibers, these machines, conventionally called fiber placement machines, comprise a head equipped with a compacting roller intended to come into contact against the draping surface to apply the strip, the guide means guiding the fibers. fibers to the roll in the form of a band.

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 give a stickiness to the fibers during draping.

In the case of a lay-up of fibers pre-impregnated with resin, the preform, said pre-impregnated, obtained after draping, is subsequently cured or polymerized by passing through an oven to obtain a piece of composite material.

In the case of dry fibers, with or without a binder, resin is injected or infused into the so-called dry preform before a curing step. Dry preforms with binder include a small amount of binder, generally less than 5%, to maintain the cohesion of the preform, while allowing its subsequent impregnation.

For the draping of dry fibers provided with a binder, a first technique consists in producing a coating of the binder in line, for example between the exit of the guiding system and the compaction roller, as described in patent WO2006 / 092514. in the name of the plaintiff. This technique has the disadvantage of the implementation of a binder application system for the hot application of the binder, independently on each fiber. Such an application system is cumbersome and complex, and has a significant cost. In addition, the binders are generally hot melt, it is necessary to heat the binder in liquid form, which implies a long start time of the machine.

A second solution is to implement fibers already coated with a binder by the raw material supplier. It is proposed to date such fibers, called powdered and / or veiled, packaged in coils, in which the binders are in the form of powder and / or a veil on one surface or on each surface of the fibers. This technique has the disadvantage of implementing an expensive product, difficult to use for certain applications, particularly in the automotive field.

The object of the present invention is to propose a solution to overcome the aforementioned drawbacks.

For this purpose, the present invention proposes a process for producing preforms by draping continuous fibers on a PT / FR2013 / 000337

3 draping surface, comprising conveying at least one dry fiber from a storage and dispensing system to guide means of a draping head for draping said fiber on a draping surface, characterized in that that he understands, when draping a fiber,

upstream of the guiding means of the draping head, the on-line application, preferably in a continuous manner, against said fiber of a binder,

transporting the fiber with the binder to the drape head, in particular to the guide means of the drape head,

at the level of the draping head, in particular downstream of the guiding means, heating said fiber with the binder to allow adhesion of said fiber to the draping surface and / or one or more fibers provided with binder previously draped on said draping surface.

According to the invention, the draping is made from dry fibers, a binder is applied to each dry fiber, upstream of the draping head, and is activated in the draping head with a heating system. The fibers are continuous and preferably comprise a multitude of continuous or non-continuous yarns or filaments, and preferably are in the form of a ribbon having two opposite major faces. The method according to the invention makes it possible to drape dry fibers with binder starting from an inexpensive raw material. Different types of dry fibers can be implemented. By way of non-limiting example, the dry fibers used are carbon fibers, glass fibers, aramid fibers, polyethylene fibers, and / or natural fibers, such as, for example, flax fibers.

According to one embodiment, said application against said fiber of a binder comprises the application of a binder in the form of at least one wire or at least one ribbon. In the case of a binder yarn, the yarn may be mono-filament or multi-filament.

According to one embodiment, the application of the binder to the fiber comprises bonding said binder to the fiber. Said binding of the binder to the fiber can be obtained by heating said binder. advantageously, said process then comprises a step of cooling the fiber provided with the binder after application of said binder.

According to one embodiment, the binder is advantageously supplied in the form of wire or ribbon, then optionally applied hot to the fiber. For example, each fiber may have its associated binder yarn package, and the advance of each fiber directly results in its binder yarn. The method according to the invention is then characterized in that it comprises the application of a binder in the form of at least one unwound wire from a reel or a ball, or a ribbon unrolled from a reel, the advancement a fiber during its draping causing the unfolding of the binder wire or the binder tape, said fiber also preferably being unwound from a coil or a ball.

One or more binder yarns may be arranged, preferably continuously, in the length of the fiber or zigzag, either on a main face or on both major faces of the fiber, depending on the weight of the yarn used and the desired binder level in the preform. Thus, according to embodiments, the method comprises

- The application of several binder son on said fiber, preferably continuously and substantially parallel to each other, each fiber is preferably in the form of a ribbon having two opposite major faces, and / or

- The application of at least one zigzag binder wire on the fiber, said fiber being preferably in the form of a ribbon.

Alternatively, instead of a wire, the binder is applied in the form of a ribbon, for example nonwoven.

According to another embodiment, the binder is applied, not in the form of a solid wire coming from a coil, but in the form of a liquid or pasty wire via a nozzle, said wire being preferably solidified during of the application on the fiber. According to another embodiment, the binder is applied in the form of powder.

According to one embodiment, the binder is applied at the level of the storage and distribution system which is offset from the draping head, said fiber provided with a binder then being conveyed to the draping head, via routing means comprising for example flexible tubes - each fiber passing in the internal passage of a flexible tube.

According to another embodiment, the storage and distribution system is integrated with the application head.

Preferably, the draping method is a tape placement method comprising draping in contact with a wide web of a broad ribbon type fiber, or a fiber placement method including draping in contact with a web broad formed of several fibers in particular ribbon type. The method then comprises draping webs formed of one or more fibers by means of a draping head provided with a compacting roll for draping in contact with said web against the draping surface, the binder application being carried out independently on each fiber in the case of multi-fiber tape placement.

According to one embodiment, the method comprises a calibration operation of each fiber, before the application of the binder to the fiber and / or after the application of the binder to the fiber, for example just before removal, on arrival fibers in the drape head, especially when the binder applied does not ensure good cohesion in width of the fiber.

According to one embodiment, the process according to the invention is a process for producing dry preforms, comprising the application of a binder to dry fibers, to form a dry fiber with a binder comprising less than 10% by weight of binder. , preferably less than 5% by weight of binder, said dry preform obtained will subsequently be subjected to an impregnation operation of a resin to form a composite part.

According to another embodiment, the method is a process for producing pre-impregnated preforms, comprising applying a binder formed from one or more resins to dry fibers to form a binder fiber comprising at least 30% by weight of binder, preferably at least 40% by weight of binder, the preimpregnated preform obtained being not subsequently subjected to an impregnation operation, for impregnation of the binder in the fibers at the core, then a hardening operation. In the case of dry fibers with binder, resin is injected or infused into the dry preform prior to the hardening step. In the case of a lay-up of fibers pre-impregnated with resin, the preform, said pre-impregnated, is subsequently cured or polymerized.

The present invention also relates to a method for manufacturing composite material parts, characterized in that it comprises

the production of a preform by draping fibers according to the method defined above,

a resin impregnation step in the preform, after a possible step of adding resin to said preform by infusion or injection, and

a curing step by passing through an oven to obtain a composite material part.

According to one embodiment, the method of manufacturing composite material parts comprises the production of a dry preform, as described above, the impregnation step comprising the addition of one or more resins by infusion or injection. According to another embodiment, the method comprises the production of a so-called prepreg preform, as described above, the impregnation step comprising heating the preform to impregnate the whole of the preform or the resins forming the binder.

The present invention also relates to a fiber lay-up machine comprising

a draping head including guiding means for guiding one or more fibers to a draping surface to drape said fibers onto the draping surface, and preferably a compacting roll intended to come into contact with the draping surface;

a storage and distribution system comprising storage and distribution means for storing and dispensing at least one fiber, and

conveying means for conveying the fiber or fibers from said storage and dispensing system to the guide means of the drape head, characterized in that the storage and dispensing system further comprises

storage and distribution means for storing and dispensing a binder, and

application means for applying said binder against each fiber, preferably in the form of at least one wire or at least one ribbon,

said draping head comprising heating means for heating each fiber with the binder to allow adhesion of said fiber to the draping surface or to one or more fibers previously draped over said draping surface.

According to one embodiment, the storage and distribution means are capable of storing and dispensing a binder in the form of at least one wire or ribbon, the application means preferably being able to apply to hot at least one binder yarn against each fiber to bond said fiber and said binder yarn.

According to one embodiment, the fiber storage and distribution system comprises a creel for receiving at least one fiber reel and at least one spool of binder yarn per fiber reel.

According to one embodiment, the application means comprise for each fiber, a roller and a counter-roller adapted to receive between them a fiber and the binder, said roller being preferably mounted movably between an inactive position in which the roller is disposed at a distance from its associated counter-roller, and an active position in which the fiber and the binder are clamped between the roller and the counter-roller. According to a variant, each counter-roller is able to be heated to allow binding of the fiber and the binder by heating the binder in the active position of the roller.

According to one embodiment, said application means are able to apply at least one zigzag binder wire on each fiber.

The machine according to the invention can be:

a so-called tape placement machine for application in contact with a wide band formed of a broad ribbon type fiber or wick, or a so-called fiber placement machine for application in contact with a wide band formed of several fibers or wicks, in particular of the ribbons type, or

a machine for non-contact application, for example a filament winding machine for applying a strip formed of one or more fibers, in particular of the ribbon type.

In the case of a web placement machine or a fiber placement machine, the head comprises a compacting roll for draping in contact with a web of one or more fibers, said machine preferably comprising in addition to a system for moving the drape head.

According to one embodiment, the storage and dispensing system is disposed at a distance from the drape head, for example placed on the ground or is mounted on one of the elements of the head displacement system. According to another embodiment, the storage and distribution system is integrated in the application head, the conveying means are for example formed of pulleys carrying the fibers of said storage and distribution system to the guide means of the head, a displacement system for moving the head and the storage and distribution system.

According to one embodiment, for the draping of a strip formed of a plurality of fibers, the storage and dispensing system comprises a creel for receiving a plurality of fiber bobbins and receiving at least one bobbin thread spool by fiber coil, the binder application means being capable of independently applying at least one binder yarn to each fiber.

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 a particular presently preferred embodiment of the invention, with reference to the schematic drawings. annexed, in which:

FIG. 1 is a schematic side view of a fiber lay-up machine according to one embodiment;

FIG. 2 is an enlarged schematic view of the creel of the machine of FIG. 1; FIG. 3 is an enlarged partial view along the plane III-III of FIG. 2, illustrating the system for applying binder yarns to the fibers;

FIG. 4 is an enlarged view of the detail D of FIG. 3;

- Figure 5 is a schematic side view of a creel according to an alternative embodiment; and,

- Figure 6 is a schematic top view of a binder application system according to an alternative embodiment, for the application of zigzag son on the fibers.

Figure 1 schematically illustrates a draping machine, or fiber placement machine according to the invention, for draping the contact on a mold of a strip formed of several fibers.

The machine comprises a displacement system 1 which is formed of a poly-articulated arm 11 of the six-axis poly-articulated robot type, known per se, mounted mobile on a linear rail 12 fixed to the ground. The poly-articulated arm 11 is fixed by its base 112 on a carriage 13 slidably mounted on the rail 12.

The placement head 2 is mounted on the end wrist 11a of the poly-articulated arm. The head comprises, in known manner, guiding means for guiding a plurality of fibers in the form of a band towards a compaction roller 21, the compaction roller being able to come into contact with a mold for applying the band. The head further comprises cutting means for individually cutting each fiber, re-routing means for rerouting each fiber that has just been cut, in order to be able to stop and resume the application of a fiber at any time, as well as to choose the width of the band, and locking means for blocking a fiber that has just been cut. By way of example, the machine comprises a drape head as described in the patent document WO2008 / 132299.

The machine is provided here for the lay-up of fibers, for example carbon fiber type 9, in the form of ribbon, packaged in coils. The storage and dispensing system comprises a creel, diagrammatically represented under the reference 3, for receiving the fiber reels and delivering the fibers independently of one another. Each coil is mounted on a mandrel 32, motorized or not. By way of example, each mandrel is rotatably mounted and is equipped with an automatic braking system controlled in a closed loop as a function of the tension of the fiber. The creel comprises a support frame carrying the mandrels 32 on which the fiber coils are mounted. The mandrels 32 are arranged substantially horizontally parallel to each other. The creel is also mounted on a follower carriage 31, disposed on the rail 12 and mechanically connected to the carriage 13 carrying the robot. In the illustrated embodiment, the machine and provided for draping a strip of eight fibers 9, the creel comprising comprises eight coils 90 of fiber.

The conveying means for conveying the fibers of the creel to the placement head are here formed of flexible tubes, as described for example in the patent document WO2012 / 160270. The tubes are gathered in a bundle, shown schematically under the reference 40 , and are placed in the internal passage of a flexible sheath 41, optionally cooled to cool and maintain the fibers at a low temperature, at which the fibers remain low tack.

According to the invention, the machine comprises binder storage and distribution means and binder application means on the fibers. In this embodiment, the binder is in the form of coil-wrapped wire 80. The storage and dispensing means, as well as the application means are arranged at the level of the creel and are intended to apply up to five binder yarn on each fiber.

The storage and distribution means of the binder are formed here of mandrels 51, mounted on the support frame of the creel and arranged parallel to the mandrels 32 for receiving fiber coils. Each mandrel 32 for receiving a fiber reel is associated with a mandrel 51 for receiving at least one binder wire spool. Each mandrel is intended to receive here five bobbins of binder yarn.

For the application of the five binder yarns to a fiber, the application means 6 comprise for each fiber a roller 61 and a heating counter-roller 62 between which are fed a fiber and the five binder son 8 coming from coils 80 mounted on the same mandrel 51. Each roller 61 is operable via actuating means 63 between an inactive position in which the roller is arranged at a distance its associated counter-roller 62, and an active position in which the fiber and the five son are pinched between the roller 61 and the counter-roller 62. The actuating means 63 comprise for example for each roller a cylinder, preferably pneumatic. Each roller is rotatably mounted on a yoke 64 which is fixed to the end of the rod 63a of its associated cylinder. The counter-rollers 62 are rotatably mounted, independently of one another, on a common rod 65, said rod is heated by heating means (not shown), for example of the ultrasound type, in order to heat the counter-rollers.

First guiding means 33, preferably pulleys, guide the fibers to the binder application means. Second guide means guide the binder son to the application system, to bring five son, substantially parallel to each other, against the main face of a fiber which is opposed to the counterwheel 62 heating. These second guide means may comprise pulley and / or eyelet systems, represented diagrammatically under the reference 52, and / or comb systems diagrammatically represented under the reference 53.

To ensure the positioning of the fibers on the rollers 61, each roller advantageously has a recess 61a for receiving the fibers and son, in which is inserted the counter roller 61 in the active position of the roller.

Upstream of the application means, the fibers advantageously pass through a calibration system 7, making it possible to calibrate the fibers to a desired width. This calibration system comprises a set of rollers 71 fixed and / or mobile over which the fibers pass so as to obtain a development of the fibers, as well as lateral guidance systems to calibrate the fibers in width.

By way of example, the fibers are dry carbon fibers, consisting of a multitude of carbon filaments and a small amount of so-called sizing resin, of the order of 0.2% by weight, for to give some cohesion to said filaments.

According to a first example, the machine is used to produce a dry preform, by hot applying five son of binder on each fiber. The binder son consist for example of one or more thermoplastic polymers, for example son of co-PES (polyethersulfone) type fusible multi-filament, sold under the trade name Grilon, under the reference KE-60, including 220 dtex, and having a melting point of about 60 ° C.

The counter rollers are heated to a temperature to activate the son of binder at a temperature above their melting temperature, to ensure their binding to the fibers. After application of the five binder yarns, the fiber comprises about 5% by weight of binder.

At the outlet of the application system, the temperature in the creel ensures cooling of the fibers at a temperature at which the fibers are little or not tacky. Alternatively, cooling means are provided for cooling the fibers exiting the application system.

The placement head 2 is equipped with heating means for heating the fiber provided with the binder and softening said binder in order to promote the adhesion of the fiber to the layup support and / or the previously draped fibers. The heating means, shown schematically under the reference 22 in Figure 1, are formed for example of an infrared lamp type heating system, for heating the fiber provided with the binder at a temperature above its melting temperature.

In the process of draping a fiber, the progress of the fiber causes the unwinding of its five associated binder son. The roller 61 of the fiber is in the active position for hot application of the five binder son on the fiber. At the head, the binder of the fiber is reactivated by the heating means 22 of the head. Advantageously, the heating means furthermore make it possible to heat the drape support and / or the previously draped fibers.

FIG. 3 illustrates the position of the rollers of the application system during draping of a strip formed of the four central fibers. The rollers of these four central fibers are in the active position in order to apply in line the binder son on these four fibers. The rollers of the un-draped fibers are in the inactive position so that the five threads of binder of these fibers are not heated by their respective counter-rollers.

To ensure good heating of the binder and better adhesion of the fiber to the lay-up support, and to avoid fouling of the roll, the fiber is brought to the head so that it comes against the roll by its opposite side to that against which the binder threads were applied.

After producing a dry preform by draping several folds, the dry preform can be subjected to an infusion or resin injection operation and then a hardening operation to obtain a composite part.

A preform in the form of a plate with the desired dimensions can be obtained by draping several plies. The binder applied to the fibers allows deformation of the preform. This may be placed in a mold corresponding to the final shape of the desired composite part in which the resin impregnation operation will be carried out by injection or infusion.

According to another example, the machine is used for the production of pre-impregnated preforms, by applying to each fiber five binder son, without bond between the fiber and the five binder son. The binder son are for example made of one or more thermoplastic resins. The counter rollers are not heated, and the rollers are optionally maintained in the inactive position. Each fiber and its five wires are routed to the head at which the heating means, formed for example of a laser heating system, heat the son to the melting temperature of the thermoplastic resin, for example of the order of 300 ° C to 400 ° C. The pre-impregnated preform obtained comprises at least 40% by weight of resin. The preform can then be subjected to a heating and pressurizing operation to impregnate the resin homogeneously throughout the preform, then a consolidation operation to obtain a composite part.

FIG. 5 illustrates an embodiment variant in which the binder threads 8 are packaged in conical 180 coils, also called fusettes. The coils are fitted, fixed in rotation, on vertical axes 151. For each fiber, a support 154, mounted on the support frame of the creel, carries five vertical axes to receive five coils of binder son. The son pass in guide means of eyelet type 152 and in a comb 153. While draping a fiber, its five associated binder son are unwound from their coils.

FIG. 6 illustrates a fiber 9 provided with a binder obtained by means of an application system allowing the zigzagging of a binder thread 8 on one of the main faces of a fiber. Such a fiber is for example obtained using wire guiding means, placed upstream of the rollers and heating rollers, comprising for each wire an eyelet 66 in which the wire passes, the eyelets are attached to the same rod 67 moved back and forth, transversely to the direction of advancement of the fibers, by actuating means, for example of pneumatic cylinder type 68.

According to another variant embodiment, the application of a binder yarn to a fiber is obtained by heating the fiber, the thus heated fiber and the binder yarn are pressed together at the level of a fiber. pulley to ensure the connection. The application means comprise for example a heating tunnel through which the fiber passes, said tunnel being for example continuously heated by means of a hot air torch. At the end of the tunnel, the fiber is pressed against a pulley, with the binder wire interposed between said pulley and the fiber. The pulley is advantageously cooled by an air or liquid cooling system. Binding the binder to the fiber by heating the binder is obtained by applying the binder to a previously heated fiber.

Although the invention has been described in connection with various 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

15 CLAIMS

1. Method for producing preforms, by draping fibers on a draping surface, comprising conveying at least one dry fiber (9) from a storage and distribution system (3) to a head (2 ) draping for draping said fiber on a draping surface, characterized in that it comprises, when draping a fiber,

- the application against said fiber of a binder (8),

- routing the fiber with the binder to the draping head,

- heating said fiber with the binder to allow adhesion of said fiber to the draping surface and/or to one or more fibers provided with binder previously draped on said draping surface.

2. Method according to claim 1, characterized in that said application against said fiber of a binder comprises the application of a binder in the form of at least one thread or at least one ribbon.

3. Method according to claim 1 or 2, characterized in that the application of the binder (8) to the fiber (9) comprises the connection of said binder to the fiber.

4 Method according to claim 3, characterized in that said connection of the binder (8) to the fiber (9) is obtained by heating said binder.

5. Method according to claim 4, characterized in that it comprises a step of cooling the fiber (9) provided with the binder (8) after application of said binder.

6. Method according to one of claims 1 to 5, characterized in that it comprises the application of a binder (8) in the form of at least one wire unwound from a reel (80, 180), the advancement of a fiber during its draping causing the binder thread to unwind.

7. Method according to claim 6, characterized in that it comprises the application of at least one binder thread in a zigzag manner on the fiber.

8. Method according to one of claims 1 to 7, characterized in that the application of binder (8) is carried out at the level of the system (3) for storing and distributing the fibers which is offset from the draping head. 16

9. Method according to one of claims 1 to 8, characterized in that it comprises the draping of strips formed of one or more fibers by means of a draping head (2) provided with a roller (21) compaction to drape in contact with said strip against the draping surface, the application of binder being carried out independently on each fiber.

10. Method according to one of claims 1 to 9, characterized in that it comprises the application of a binder (8) to dry fibers (9) to form a dry fiber with binder comprising less than 10% in weight of binder.

11. Method according to one of claims 1 to 10, characterized in that it comprises the application of a binder (8) comprising one or more resins on dry fibers (9) to form a fiber with binder comprising at least less than 40% by weight of binder.

12. Process for manufacturing parts made of composite material, characterized in that it comprises

- producing a preform by draping fibers according to one of claims 1 to 11,

- a step of impregnating resin in the preform, and

- a hardening stage.

13. Fiber draping machine including

- a draping head (2) comprising guide means for guiding one or more fibers towards a draping surface,

- a storage and distribution system (3) comprising storage and distribution means (32) for storing and distributing at least one fiber (9), and

- routing means (40) for routing the fiber(s) from said storage and distribution system to the draping head guiding means,

characterized in that the storage and distribution system further comprises

- storage and distribution means (51; 151) for storing and distributing a binder (8), and

- application means (6) for applying said binder against each fiber, said draping head comprising heating means (22) for heating each fiber with the binder to enable adhesion of said fiber to the draping surface or to one or more previously draped fibers.

14. Machine according to claim 13, characterized in that the storage and distribution means (51; 151) are capable of storing and distributing a binder (8) in the form of at least one wire or a ribbon, the application means (6) being capable of applying hot at least one binder thread against each fiber to bind said fiber and said binder thread.

15. Machine according to claim 14, for draping a strip formed of several fibers, characterized in that the storage and distribution system (3) comprises a creel for receiving several reels (90) of fiber (9 ) and receiving at least one spool (80) of binder wire (80) per fiber spool, the binder application means (6) being capable of independently applying at least one binder wire to each fiber.