Textile coating machine with tension limiting system and coating head

Abstract

The invention particularly relates to a textile application machine with a textile application head comprising a fixed part (21) and a mobile part (22) slidably mounted on the fixed part and biased by at least one compression cylinder (25). The mobile part comprises an application roller (23) and a guide system for guiding at least one fibre (F1, F2) to the application roller in a guide surface (P1, P2). The machine further comprises a tension limiting system (4) comprising at least one cylinder (41-44) around which each fibre is at least partially wound and drive means (29) capable of rotating said cylinder. The tension limiting system is attached to the mobile part of said head upstream of the guide system.

Description

Detailed Description of the Invention

[0001] The present invention relates to a textile application machine equipped with a particular tension limiting system and to a method for producing composite material parts using such a machine.

[0002] Known, in particular from patent WO 2006 / 092514, is a fiber application or lay-up machine for automatically laying up one or more fibers, in particular wide bands made of ribbon-type flat continuous fibers (commonly referred to as tows), in particular carbon fibers consisting of a multiplicity of carbon threads or carbon filaments, on a lay-up surface (for example the surface of a male or female mould).

[0003] These machines, conventionally called fiber placement machines, conventionally comprise a fiber application head including a fixed part and a movable part, the movable part comprising an application roller for applying at least one fiber, in particular a strip formed of one or more fibers, to an application surface, a guide system for guiding the at least one fiber along a guide surface towards said application roller, and, for each fiber, a fiber cutting system, a fiber re-routing system and a fiber clamping system. The movable part is slidably mounted on the fixed part and biased by at least one compression jack. These machines also comprise fiber storage means, such as a remote spool creel, transport means for transporting the fibers from said storage means to the head, and a displacement system, for example, allowing the head to be displaced relative to the lay-up surface.

[0004] The conveying means may consist of flexible tubes, each flexible tube capable of receiving the fibers in its internal passage and preferably comprising at least one longitudinal flexible blade arranged substantially parallel to the conveying plane of the fibers received in the internal passage of the flexible tube. Such flexible tubes constitute conveying means which are simple in design, compact in size and low in cost, which allows to achieve high movement speeds, offset the storage means from the displacement system, isolate the fibers from the outside, simplify the displacement system of the application head, and in particular to use a displacement system such as a standard 6-axis robot-type articulated arm.

[0005] In order to limit the tension of the fibre, it is proposed in the above mentioned patent document to provide at least one tension limiting system arranged between the fibre storage means and the application head, said tension limiting system comprising at least two cylinders parallel to each other on which a plurality of fibres can be partially wound and drive means for driving said cylinders rotating at substantially the same speed. The drive means are controlled by a machine control unit and exert a tensioning force on the fibre coming from the storage means at the application roller such that the peripheral speed of the cylinders is greater than the moving speed of the fibres. As a result, the winding tension of the fibres at the application roller can be limited, regardless of the moving speed of the fibres. The tension limiting system is usually arranged between the storage means and the head, in the creel, at the creel outlet or along the fibre path defined by the conveying means. Such a tension limiting system makes it possible to unwind several spools or several fibre balls with a single control system for fibres running at different speeds at the application head. The tension limiting system reduces the tension of the fibres at the application roller, regardless of their speed.

[0006] Machines available today with this type of tension limiting system allow one or more fibers to be applied at low tension. However, this low residual tension can have a detrimental effect on layup quality, especially when the layup is performed at high speeds, especially when the fibers are cut and rerouted on the fly at high speeds.

[0007] The aim of the present invention is to propose a solution which overcomes the aforementioned drawbacks.

[0008] For this purpose, the invention proposes a textile application machine for producing composite material parts, which comprises: - a support structure or a fibre application head comprising a fixed part and a movable part, The moving part is a compression system including at least one application roller for applying the coating to the application surface of at least one fiber, in particular a strip formed from one or more fibers; a guiding system for guiding at least one fiber along a guiding surface towards the application roller, and a fiber cutting system, a fiber redirection system, and preferably a fiber clamping system, the movable part is slidably mounted on the fixed part along a sliding plane and biased by at least one compression jack mounted between the fixed part and the movable part; The machine further comprises a tension limiting system including at least one cylinder around which each fiber can be partially wound and drive means capable of rotating said cylinder such that the peripheral speed of the cylinder is greater than the speed of movement of the fiber in the head, The tension limiting system is characterized in that it is attached to a movable part of the application head, upstream of the guiding system with respect to the forward advancement direction of the fiber in the head.

[0009] According to the invention, the tension limiting system is mounted on the moving part of the head as close as possible to the re-routing system, the cutting system and the compression system, preferably without any intermediate return system between the tension limiting system and the compression system, so that the fiber tension during lay-up is as low as possible. This very low fiber tension in the head allows for accurate positioning of the fiber ends at high lay-up speeds, for example above 1 m / s, especially during fiber cutting and / or fiber re-routing in the air. The low fiber tension avoids problems such as slippage during fiber re-routing and thus allows for accurate positioning of the fiber ends. This low fiber tension also allows for an increased lay-up capability of fibers with high curvatures in the plane of the fibers, traditionally called "steering". In the case of a head capable of applying strip-shaped fibers, the tension limiting system thus arranged on the moving part allows for the fiber tension at the application roller to be substantially the same for all fibers, as a result of which an optimal strip-shaped fiber lay-up quality is guaranteed.

[0010] According to one embodiment, the tension limiting system is attached to a movable part of the application head, and the fibres exiting the tension limiting system are arranged along the guiding plane defined by the guiding system.

[0011] According to one embodiment, in the case of a machine intended for applying a band formed of several fibers, said guiding system is adapted to guide the several fibers in the form of bands towards the application roller, the guiding system comprising first and second guiding means for guiding the fibers in the form of two bundles towards the application roller along two guiding planes arranged in a staggered manner and approaching each other from upstream to downstream, the tension limiting system comprising a first assembly of at least one cylinder, preferably at least two cylinders, over which the fiber(s) of the first bundle pass, and a second assembly of at least one cylinder, preferably at least two cylinders, over which the fiber(s) of the second bundle pass, the fiber(s) of the first bundle being preferably arranged at the outlet of the first assembly in the first guiding plane and the fiber(s) of the second bundle being arranged at the outlet of the second assembly in the second guiding plane. The tension limiting system according to the invention advantageously makes it possible to limit the tension difference between the fibers of the bands, thus ensuring a good lay-up quality.

[0012] According to one embodiment, the guiding means comprises a first and a second flow channel intended to receive the fibers of the first and second bundles individually, respectively, said first flow channel being formed at the assembly interface between a first outer plate and a central plate and said second flow channel being formed at the assembly interface between said central plate and a second outer plate.

[0013] According to one embodiment, the rerouting system comprises for each fibre a counter roller actuated by an actuation system, for example a pneumatic jack, between a rest position and an active position in order to press the fibre against at least one drive roller, said drive roller and the cylinder or cylinders of the tension limiting system being preferably driven in rotation by a common drive motor, preferably mounted on the moving part, via a transmission system, such that the circumferential speed of the cylinder is preferably at least 5%, for example about 20%, greater than the circumferential speed of the drive roller. Mounting the tension limiting device on the moving part advantageously makes it possible to use the motor of the rerouting device to drive the cylinder, by providing suitable transmission means for obtaining the desired circumferential speed of the cylinder and the drive roller. This solution makes it possible to simplify the speed control of the cylinder and to avoid embedding a second motor in the moving part, thereby providing a tension limiting system with small overall dimensions and reduced weight.

[0014] The transmission means may, for example, comprise one or more belts and / or one or more gearings meshing with a toothed wheel associated with each cylinder, a pinion associated with the drive roller, and one or more pinions associated with the shaft of the drive motor, and optionally a return roller.

[0015] In the case of a machine intended for the application of multiple fibers, the path changing system comprises a first path changing means including at least a first drive roller and a counter roller actuated between a rest position and an operating position by an actuation system for individually pressing the fibers of a first bundle against said first drive roller, and a second path changing means including at least a second drive roller and a counter roller actuated between a rest position and an operating position by an actuation system for individually pressing the fibers of a second bundle against said second drive roller, the drive rollers being driven by a common drive motor.

[0016] The machine may further comprise fibre storage means, such as a spool creel mounted on a support remote from the head or integral with a fixed part of the head, transport means for transporting the fibre or fibres from the storage means to the head, and a displacement system adapted to effect a relative displacement of the head with respect to the lay-up surface, in particular capable of displacing the head. According to one embodiment, the transport means comprises at least one flexible transport tube, each transport tube capable of receiving a fibre in its internal passage.

[0017] In an embodiment, preferably when the storage means is remote from the head and the conveying means comprises one or more conveying tubes, the machine comprises a second tension limiting system arranged upstream of the conveying means capable of conveying one or more fibres from the storage means to the application head. This second tension limiting system allows the tension of the fibres to be effectively reduced before they enter the conveying tube, thus ensuring an efficient conveying of the fibres in the tube and a low fibre tension at the outlet of the conveying tube. This low fibre tension at the outlet of the tube can be effectively reduced and made uniform from one fibre to another by a tension limiting system according to the invention mounted on the moving part of the head, in particular a tension limiting system with reduced overall dimensions, including a reduced number of cylinders, for example only two cylinders for each fibre.

[0018] According to the embodiment described in FR2114113 filed by the applicant on 23 December 2021, for each fibre a belt is attached around each cylinder. As a result, the belt is interposed between each fibre and the cylinder, each belt can adhere to the fibre and is more or less driven by the cylinder depending on the pressure that the fibre exerts on the belt. To limit the contact angle portion between the belt and the cylinder, each belt is preferably mounted in a loop on a sliding path formed in part by a cylinder and a crescent-shaped complementary part fixedly mounted around the cylinder, the ends of said complementary part fitting tangentially to the cylinder. As a result, each fibre and each belt is guided between two flanges, each flange including at least one tab at each end that can be elastically snapped into a recess in the intermediate part. In this embodiment, the flanges can be easily disassembled for replacement or to allow replacement of the belt.

[0019] Another object of the invention is a method for manufacturing a composite part comprising applying continuous fibres to a lay-up surface, characterized in that the application of the fibres is carried out using a fibre application machine as defined above, by displacing a application head relative to the lay-up surface according to a lay-up trajectory.

[0020] The invention will be better understood, and other objects, details, features and advantages will become apparent, in the course of the following detailed description of certain presently preferred embodiments of the invention, taken in conjunction with the accompanying schematic drawings, in which: FIG. 1 is a schematic side view of a textile coating machine according to the invention, including a head equipped with a tension limiting system; 2 and 3 are enlarged schematic side views of the application head of FIG. 1;

[0021] 1 shows diagrammatically a fibre placement machine according to the invention, enabling the lay-up of a strip formed of a plurality of fibres by contact on a mould. This application machine comprises a displacement system 1 consisting of a per se known six-axis robot-type articulated arm 11 movably mounted on a linear axis 12, an application head 2 attached to the end wrist 11a of the articulated arm, fibre storage means 7 and transport means 8 for transporting the fibres from said storage means to the application head.

[0022] The articulated arm 11 is attached by its base 112 to a carriage 13 slidably mounted on a linear axis 12, said linear axis consisting of two parallel rails 121 fixed to the floor. The carriage is provided with drive means, such as motorized rollers, controlled by a machine control unit, for displacing the placement head along these rails.

[0023] The fibre application head 2, also called fibre placement head, comprises an application or compression roller 23 capable of contacting a mould for applying a strip formed, for example, of a plurality of fibres previously impregnated with resin. The machine is designed to apply flat continuous ribbon-like fibres, such as carbon fibres wrapped in spools. The storage means consist of a creel, shown diagrammatically in FIG. 7, for receiving the fibre spools 9. The creel is also mounted on a follower carriage 71, arranged on rails 121 and mechanically linked to the carriage 13 carrying the robot. The machine is for laying up eight fibre strips, the creel comprising eight mandrels 72, possibly motorised, for receiving the eight fibre spools 9. In a manner known per se, the creel may comprise an oscillating roller or pulley through which each fibre passes, the rotation of the mandrel being controllable depending on the position of the oscillating roller. Similarly, a secondary mandrel may be associated with each mandrel for unwinding the separator film as the fibre is unwound.

[0024] The conveying means 8 comprises a flexible conveying tube with a flexible reinforcing braid, for example as described in patent WO2012 / 160270. The fibres are conveyed individually in this conveying tube from the creel 7 to the head 2. The tubes are gathered into bundles, shown diagrammatically by reference number 80 in Fig. 1, and placed in an internal passage of a flexible sheath 81, possibly cooled to cool the fibres.

[0025] 2 and 3, the head 2 comprises a support structure or fixed part 21 by which the head is attached to an articulated arm, on which the movable part 22 is translationally mounted. The fixed part 21 comprises a support plate 211 provided on a first upper surface with a bracket 212 for attachment to an end wrist of the articulated arm along the assembly axis A. The support plate 211 comprises on its second main surface, opposite the first main surface, two spaced apart and vertically extending mounting plates 213, the movable part 22 being slidably mounted on the front edges of the mounting plates. The mobile part 22 comprises, in a manner known per se, an application roller 23, a guiding system 24 for guiding the fibres towards the roller in two batches or bundles of fibres along two guiding surfaces P1, P2, a cutting system for cutting each fibre individually, a re-routing system for re-routing each freshly cut fibre individually so that the application of the fibres can be stopped and restarted at any time as well as the width of the web can be selected, and a clamping system for clamping each freshly cut fibre. By way of example, the guiding system, the cutting system, the re-routing system and the clamping system are similar to those described in patent WO2008 / 132299. The mobile part 22 comprises two flanges 221 interconnected by a crosspiece, between which the compression roller, the guiding system, the cutting system, the re-routing system and the clamping system are mounted. At the rear edge of the flanges there is a carriage 214 which slides in a plane parallel to the axis A in complementary rails 214 attached to the front edges of the two mounting plates. The mobile part is connected to the fixed part by at least one compression jack 25, preferably pneumatic, for example two compression jacks, which determine the shaping force with which the fibres are applied to the mould by the compression roller 23. Each jack is attached to the fixed part by its jack body 25a and its rod 25b runs parallel to the sliding surface and is connected to the upper edge of the flange 221. The jacks bias the mobile part in the direction opposite to the support plate, i.e. vertically downwards in the configuration shown in Fig. 2. The compression jacks are for example double-acting pneumatic and are pressure controlled to adjust the compression force.

[0026] The guiding system comprises first and second channels arranged in a staggered manner along two guiding surfaces P1, P2 approaching each other from downstream to upstream, and guides the fibers to the roller in the form of two fiber bundles. The first and second channels are designed to receive the fibers F1, F2 of the first and second bundles, respectively. The guiding system comprises, for example, three plates, preferably made of metal, mounted flat against each other and defining between them a first guiding channel and a second guiding channel, through which the fibers of the first bundle and the fibers of the second bundle, respectively, are fed tangentially to the application roller. The first channel is formed at the assembly interface between a first outer plate and a central plate having a triangular cross section, and the second channel is formed at the assembly interface between the central plate and a second outer plate.

[0027] The path changing system comprises a first path changing means including a first drive roller 26 rotatably mounted in a lateral bore of the central plate, a counter roller actuated between a rest position and an active position by an actuation system to press the fibers F1 of the first bundle against the first drive roller, and a second path changing means including a second drive roller 27 rotatably mounted on a second outer plate, and a counter roller actuated between a rest position and an active position by an actuation system to press the fibers F2 of the second bundle against the second drive roller. The two drive rollers 26, 27 are driven in rotation via a belt by a motor 29 mounted on the moving part. Each drive roller comprises a pinion 26a, 27a at its end, a first belt 28 meshing with the pinion of the drive roller, and a first pinion 29a mounted on the shaft of the motor 29. To facilitate maintenance operations, the tension of the first belt is adjusted by a belt tensioning system 30 which includes a tensioning roller mounted on the end of a pivot arm which is actuated by a jack.

[0028] The cutting system, known per se, comprises first cutting means for cutting each fibre F1 of the first bundle and second cutting means for cutting each fibre F2 of the second bundle.Similarly, the clamping system comprises first clamping means for clamping each fibre F1 of the first bundle and second clamping means for clamping each fibre F2 of the second bundle.

[0029] According to the invention, the head comprises a tension limiting system 4 attached to the movable part 22 upstream of the guiding system 24 with respect to the direction of fibre movement in the head, through which the fibres F1, F2 entering the head pass in order to limit or remove the fibre tension applied by the compression rollers. The tension limiting system 4 comprises a first set of two rollers 41, 42 for the fibres F1 of the first bundle and a second set of two rollers 43, 44 for the fibres F2 of the second bundle.

[0030] At the head inlet, the head comprises a row of first pulleys 31 mounted to rotate on a first axis for guiding the F1 fibres of the first bundle coming from the tube towards the tension limiting system, and a row of second pulleys 32 mounted to rotate on a second axis for the F2 fibres of the second bundle, these pulleys 31, 32 being mounted on a support 33 fixed to the fixed part 21. A conveying tube 80 is attached at its end to said support 33 upstream of the two rows of pulleys, via a fastening system 34, for example in the form of a cassette, in two parallel rows so as to form two fibre bundles. A sheath 81 is fixed at its end to said support 33.

[0031] At the exit of the conveying tube, the fibers F1 of the first bundle pass over the first pulley 31, then over the first cylinder 41 and over the second cylinder 42. At the exit of the second cylinder 42, the fibers F1 are arranged in a plane P1 and enter directly into the first guiding channel of the guiding system 24. The fibers F2 of the second web pass over the second pulley 32 and over the first cylinder 43 and the second cylinder 44. At the exit of the second cylinder 44, the fibers F2 are arranged in a plane P2 and enter directly into the second guiding channel. Each fiber directly or indirectly contacts a first main surface with respect to the first cylinder and then a second main surface with respect to the second cylinder.

[0032] The first and second sets of rollers 41-44 are rotatably mounted in a cantilever manner on a support plate 45 assembled to the movable part, the rotation axes C of the rollers 41-44 are parallel to each other and to the rotation axis B of the compression roller 23, and the rollers extend perpendicularly from the first main surface of the support plate. The rollers 41-44 can be driven in forward rotation by the drive motor 28 of the path changing device. Each cylinder is provided with a toothed wheel 46 at its end on the side of the second main surface of the carrier plate 45. The cylinders are rotated by a second belt 47, for example a double toothed belt, which meshes with a second pinion 29b on the shaft of the drive motor 28 and with each toothed wheel 46 of the cylinder, and the second belt also passes over a return roller 48 to define a belt path for driving all the cylinders. A tension roller system can also be provided to adjust the tension of the second belt. The diameters of the drive rollers 26, 27 and their pinions 26a, 26b, and the diameter of the rollers 41-44 and their gears 46 are chosen so that the peripheral speed of the rollers 41-44 is, for example, about 20% greater than the peripheral speed of the drive rollers. Alternatively, a single belt is provided to drive the rotation of the drive rollers and cylinders.

[0033] During operation, the drive motor 29 is controlled by the machine control unit to drive the drive rollers 26, 27 such that the peripheral speed of the re-routing rollers is equal to the peripheral speed of the compression roller 26 pressed against the lay-up surface, which corresponds to the speed of the Tool Center Point (TCP) on the lay-up surface S, TCP being the midpoint of the intersection between the compression rollers and the lay-up surface. When the head is not in contact with the lay-up surface, for example during a connecting track between two lay-up tracks, each fiber end can also be re-routed from the cutting system to the compression rollers by controlling the drive motor and the re-routing counter roller associated with that fiber.

[0034] Some fibers, due to their fragility, elasticity and lightness, cannot come into direct contact with the rotating cylinder. To implement such fibers, a belt can be attached around each cylinder, as described in the aforementioned document, so that between each fiber and the cylinder there is a belt, which can adhere to the fiber and is driven more or less by the cylinder depending on the pressure that the fiber exerts on the belt, said pressure being proportional to the tension in the fiber.

[0035] In order to limit the tension in the fibres before they enter the conveying tube, the machine is equipped with a tension limiting system 104 arranged in the creel, as described in the aforementioned patent documents, preferably a system corresponding to the one described in patent application FR2114113.

[0036] Although the invention has been described in relation to specific embodiments, it is clear that the invention is in no way limited thereto, but includes all technical equivalents of the described means, and combinations thereof, if they fall within the scope of the invention. [Brief description of the drawings]

[0037] [Figure 1] 1 is a schematic side view of a textile coating machine according to the present invention, including a head with a tension limiting system; [Diagram 2] 2 is an enlarged schematic side view of the coating head of FIG. 1. [Diagram 3] 2 is an enlarged schematic side view of the coating head of FIG. 1.

Claims

1. A fiber application machine for the production of composite material parts, comprising a fiber application head (2) comprising a fixed part (21) and a movable part (22), The movable part is a compression system comprising at least one application roller (23); a guiding system for guiding at least one fiber (F1, F2) along a guiding surface (P1, P2) towards said application roller; - a fiber cutting system and a fiber redirection system, The movable part (22) is slidably mounted on the fixed part (21) and biased by at least one compression jack (25) mounted between the fixed part and the movable part; The machine further comprises a tension limiting system (4) comprising at least one cylinder (41-44) around which each fibre can be partially wound, and drive means (29) capable of driving said cylinder in rotation; A textile coating machine, characterized in that the tension limiting system (4) is attached to the moving part (22) of the coating head, upstream of the guiding system (24).

2. 2. The machine according to claim 1, characterized in that the tension limiting system (4) is attached to the movable part (22) of the application head in such a way that the fibers (F1, F2) exiting the tension limiting system are positioned on the guiding surfaces (P1, P2).

3. The guide system (24) is capable of guiding a plurality of fibers (F1, F2) in a band shape towards the application roller (23), the guiding system (24) comprises first and second guiding means for guiding the fibers towards the application roller in two bundles along two guiding surfaces (P1, P2); 3. The machine according to claim 1 or 2, wherein the tension limiting system (4) comprises a first set of at least one cylinder (41, 42) through which the fibers (F1) of the first bundle pass and a second set of at least one cylinder (42, 43) through which the fibers (F2) of the second bundle pass.

4. the path-changing system includes, for each fiber, a counter roller actuated by an actuation system between a rest position and an active position to press the fiber against at least one drive roller (26, 27); 2. The machine according to claim 1, characterized in that the drive rollers and the cylinders (41-44) of the tension limiting system (4) can be driven in rotation by a common drive motor (29) attached to the moving part via a transmission system (28, 29a, 29b, 47, 46, 47, 48) so that the peripheral speed of the cylinders is greater than the peripheral speed of the drive rollers.

5. 2. The machine according to claim 1, characterized in that it comprises a second tension limiting system (104) arranged upstream of the conveying means (8) capable of conveying one or more fibers from the storage means (7) to the application head (2).

6. 10. A method for manufacturing a composite material part, comprising applying continuous fibers onto a lay-up surface, characterized in that the application of fibers is performed using a fiber application machine according to claim 1 by displacing the application head relative to the lay-up surface according to a lay-up trajectory.

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