FIBER APPLICATION HEAD WITH RETRACTABLE FLAP

Abstract

The present invention relates to a fibre application head for the production of composite material parts, comprising a compaction roller (3), guiding means (4), a retractable flap (6) which can be displaced between an active position in which the said flap is able to come by its distal end (63) against the fibre in order to bring the said fibre in abutment against with the roller, and a retracted position in which said flap is spaced apart from the roller, and a heating system (5) able to emit thermal radiation (51) towards of the nip zone between the roller and the application surface. Said flap is displaceable by actuation means (7) between its active position and its retracted position so that the roller is subjected to the radiation of the heating system over a greater surface area in the retracted position than in the active position of the flap.

Claims

1. Fibre application head (1) for the production of composite material parts comprising a compaction system comprising at least one compaction roller (3) guiding means (4) for guiding at least one fibre (9) towards said compaction roller, and a retractable flap (6) displaceable by actuation means (7) between an active position in which said retractable flap is able to come by its distal end (63) against the fibre exiting from the guiding means in order to bring said fibre in abutment against the compaction roller, and a retracted position in which said retractable flap is spaced apart from the compaction roller, characterized in that it comprises a heating system (5) able to emit thermal radiation (51) towards the nip zone between the compaction roller (3) and the application surface, in order to heat the fibre exiting from the guiding means, as well as the application surface and/or one or more fibres previously applied, said retractable flap (6) being displaceable by actuation means between its active position and its retracted position so that the compaction roller (3) is subjected to the radiation (51) of the heating system (5) over a greater surface area in the retracted position than in the active position of the retractable flap.

2. Application head according to claim 1, characterized in that the retractable flap (6) is displaceable by a translational movement between its active position and its retracted position, said actuation means (7) comprising at least one cylinder.

3. Application head according to claim 1 or 2, characterized in that the retractable flap (6) in its active position is elastically in abutment with its distal end (63) against the compaction roller (3).

4. Application head according to one of claims 1 to 3, characterized in that said guiding means (4) are able to guide a plurality of fibres onto a compaction roller in the form of a band, the head comprising one or more retractable flaps associated with the compaction roller.

5. Fibre application head according to one of the claims 1 to 3, characterized in that said head is able to apply several fibres by means of a compaction system comprising several independent compaction rollers (3) and compaction cylinders for each fibre, the head comprises a functional module (2a, 2b) comprising cutting means and rerouting means, each functional module is mounted so as to be mobile in translation in a compaction direction (T2) on a support element (10) of the head, each compaction roller is mounted on one or more adjacent functional modules and a compaction cylinder is associated with the functional module(s) associated with a compaction roller the head comprising an independent heating system (5) associated with each compaction roller (3), and at least one retractable flap (6) associated with at least one compaction roller.

6. Fibre application head according to claim 5, characterized in that it comprises one compaction roller (3) per functional module (2a, 2b).

7. Application head according to claim 5 or 6, characterized in that each first functional module (2a) comprises guiding means able to guide a first fibre towards the compaction roller (3) along a first guiding plane (P1) forming a first non-zero angle (al) with the compaction plane (C) of the rotation axis (B) of the compaction rollers, each second functional module (2b) comprises guiding means able to guide a second fibre towards the compaction roller along a second guiding plane (P2) forming a second non-zero angle (α2) with the compaction plane (C), said second angle being greater than the first angle, said guiding planes (P1, P2) being arranged on the same side of the compaction plane (C).

8. Application head according to claims 6 and 7 taken in combination, characterized in that it comprises a retractable flap (6) associated with each first functional module (2a).

9. Fibre application head according to any of claims 1 to 8, characterized in that each heating system (5) comprises a laser type heating system, or a flash lamp type heating system.

10. Method for manufacturing a composite material part comprising the application of continuous fibres onto an application surface, characterized in that the application of fibres is performed by means of a fibre application head according to one of claims 1 to 9, by relative displacement of the application head with respect to the lay-up surface according to deposition trajectories, the retractable flap (6) associated with a fibre being displaced into the active position at least during a fibre rerouting operation and/or fibre cutting operation, and returned to the retracted position when the end of the rerouted fibre is no longer compacted by the compaction roller, so as to heat said fibre before it is compacted by the compaction roller over a greater length of fibre.

Description

[0027] The invention will be better understood, and other purposes, details, features and advantages will become clearer in the course of the following detailed explanatory description of a presently preferred particular embodiment of the invention, with reference to the appended schematic drawings, in which:

[0028] FIG. 1 is a schematic side view of a fibre application head according to an embodiment of the invention;

[0029] FIG. 2 is an enlarged partial view of FIG. 1 illustrating the retractable flap and its actuation system in the vicinity of the compaction roller, the flap being in retracted position;

[0030] FIG. 3 is a view similar to that of FIG. 2 with a partial sectional view at the level of the flap actuation system;

[0031] FIG. 4 is a view similar to that of FIG. 3 with the retractable flap in active position; and

[0032] FIG. 5 is a perspective view of the retractable flap and its actuation system, without the protective cover.

[0033] FIG. 1 illustrates a fibre application head 1 according to the invention for the lay-up of a plurality of continuous fibres arranged edge-to-edge in the form of a band. In the present embodiment, the head comprises one independent compaction roller per fibre. The head 1 is intended to be assembled to a displacement system to perform the fibre lay-up operations, the fibres being in the present embodiment packaged in the form of cassettes, and the cassettes are carried on the head. The head comprises a support structure or frame 10 provided with assembly means (not shown) for assembling the head, according to an assembly axis A, to a head displacement system, for example the wrist of a poly-articulated robot or a gantry-type Cartesian displacement system.

[0034] The head carries a plurality of functional modules 2a, 2b arranged side by side. Each functional module is associated with a fibre cassette 91a, 91b and comprises cutting means, rerouting means, clamping means and a compaction roller 3.

[0035] The head comprises two types of functional module, first functional modules 2a, also called downstream functional modules, associated with downstream fibre cassettes 91a, arranged downstream of the functional modules with respect to the advance direction D of the head during lay-up, and second functional modules 2b, also called upstream functional modules, associated with upstream fibre cassettes 91b, arranged upstream of the functional modules with respect to the advance direction D. The functional modules are arranged in a row, the row comprising alternating downstream functional modules 2a and upstream functional modules 2b.

[0036] The functional modules are mounted on the frame by means of support elements 11, each support element carrying a downstream functional module 2a and an upstream functional module 2b. Each functional module is mounted independently on the support element, mobile in translation in a compaction direction T2, which is parallel to the assembly axis A, and is connected at the top to the end of the rod of a compaction cylinder 12, said cylinder being connected by its body to the support element.

[0037] The compaction roller 3 is mounted between two flanges of the functional module, mobile in rotation around a rotation axis B, which is perpendicular to the direction T2. During the translational displacement of a functional module in the direction T2, the rotation axis B of its compaction roller moves in a plane C, called the compaction plane, which is parallel to the direction T2. The support elements are mounted on the frame in such a way that the rotation axis of the rollers are all arranged substantially in the same plane C.

[0038] Each downstream functional module comprises means for guiding a fibre allowing to guide the fibre entering the module towards the compaction roller along a plane P1, said plane forming an angle α1 with the plane C. Each upstream functional module comprises means for guiding a fibre allowing to guide the fibre entering the module towards the compaction roller along to a plane P2, the planes P1 and P2 being arranged on the same side of the plane C, said plane P2 forming an angle α2 with the plane C which is greater than the angle α1. The planes P1 and P2 are arranged upstream of the plane C with respect to the advance direction of the head during lay-up, the plane P2 being arranged upstream of the plane P1.

[0039] Each functional module comprises cutting means for cutting the fibre, rerouting means for rerouting the fibre to the compaction roller after a cutting operation, and clamping means for clamping the fibre just cut, such means being known per se. As an example, the downstream functional module comprises cutting means and clamping means, as described in patent document EP2134532, WO2017/072421 or FR17/01245 and FR17/01247.

[0040] The guiding means allow to guide the fibre 9 between the clamping means, the rerouting means and the cutting means, and towards the compaction roller. To guide the fibre from the clamping means to the cutting means, the guiding means comprise a first guiding system (not shown) comprising for example a channel, formed at the assembly interface of two plates. In order to guide the fibre between the cutting means and the roller, the guiding means comprise for example, as illustrated in FIGS. 2 to 4, a second guiding system 4 comprising a channel 41 formed at the assembly interface of two plates, including a first inner plate 42 and a second outer plate 43. This second guiding system is for example mounted on the mounting clevis of the compaction roller, by its inner plate 42.

[0041] The compaction rollers are all identical and are preferably able to conform to the application surface, especially to convex and/or concave application surfaces. Each compaction roller is preferably a compaction roller made of a flexible material, which is elastically deformable, such as an elastomer. The roller comprises a cylinder made of flexible material, which is mounted in a rotationally fixed manner on a rigid axle, for example metallic, by means of which the roller is mounted in a rotationally free manner between two flanges.

[0042] Each compaction cylinder 12 is able to displace its associated functional module between an extreme high position and an extreme low position. For the lay-up of a fibre with a functional module, the module is elastically urged towards its extreme low position by its compaction cylinder. The head is brought into contact with the lay-up surface, the roller in contact with the lay-up surface. The compaction force for the lay-up can be regulated by adjusting the air supply pressure in the upper chamber of the cylinder. During lay-up, the functional module can move between its extreme low position and its extreme high position to conform to the lay-up surface. When the module is not being used to lay-up a fibre, the module is held in the extreme high position by supplying compressed air to the lower chamber. For the sake of simplicity, the compaction roller is illustrated with a cylindrical shape in FIGS. 2 to 4. In practice, the compaction roller made of a flexible material is deformed by the compaction force and has a crushed shape.

[0043] The head comprises a heating system 5, associated with each functional module, whose radiation 51 is directed obliquely towards the nip zone or contact zone between the compaction roller and the application surface, to heat the fibre to be laid up, prior to its compaction by the latter, as well as the application surface and/or one or more previously applied fibres to heat the application surface upstream of the roller. In the present embodiment, each module carries a heating system 5, upstream of the roller with respect to the advance direction of the head. Each heating system comprises, for example, a flash lamp, as described in patent document WO2014/029969 or WO2017/134453, comprising an optic formed by a quartz 52 to guide the radiation. The lamp is mounted so that the main radiation from the lamp is directed towards the nip zone between the roller and the application surface.

[0044] According to the invention, the downstream functional modules are each equipped with a retractable flap 6 that is able to be displaced by an actuation system 7 between two positions. With reference to FIGS. 3 to 5, the flap is formed by a flexible metal plate mounted at the end of the rod 72 of a cylinder 71 of the actuation system 7. The cylinder is mounted by its body 73 on the second guiding system 4, in particular on its second outer plate 43. For mounting the flap, the rod is equipped at its end with a slide 74 whose side edges are able to slide in two grooves 76 of two guiding plates 75 extending from the body 73 of the cylinder parallelly to the rod. The flap is mounted by its proximal part 71 flat on the slide by means of a counter-plate 77. The proximal part is placed between the slide and the counter-plate, and is fixed by means of screws, passing through holes in the counter-plate and holes in the proximal part, and screwed into tapped holes in the slide. A protective cover 78 is mounted on the body to cover the rod.

[0045] The flap 6 comprises a flat proximal part 61 extended by a flat distal part 62 inclined towards the roller, forming for example an angle of 10 to 35° with respect to the proximal part, this distal part ending in a curved distal end 63 by which the flap is able to come into contact, flat, against the roller.

[0046] The cylinder 71 is able to be controlled to displace the flap in translation between a retracted position and an active position. The cylinder is, for example, a single-acting pneumatic cylinder, which is supplied with compressed air to displace the flap to the active position, a spring (not shown) ensuring the return to the retracted position.

[0047] In its retracted position, the flap is spaced apart from the compaction roller, its distal end 63 is set back or at the level of the distal end 44 of the second guiding system, against the outer surface of the outer plate, as shown in FIG. 3. In its active position, the flap is in contact against the outer surface of the roller with its distal end. Preferably, the flap comes in abutment substantially tangentially and elastically by its distal end against the surface of the roller. The flap has, at least at its distal end, a width substantially equal to the width of the roller. In the retracted position, the surface of the roller receiving the radiation extends from the guiding system, more precisely from the distal end 44 of the outer plate, to the nip zone between the roller and the lay-up surface, this roller surface corresponding to the angle 131 in FIG. 3.

[0048] In the active position, the surface area of the roller receiving the radiation is reduced, this one extending from the distal end of the flap to the nip zone. This surface area of the roller corresponds to the angle 132 in FIG. 4, which is smaller than the aforementioned angle 131. As previously indicated, in practice the roller has a crushed, non-cylindrical shape, the angles 131 and 132 are in practice smaller than those illustrated.

[0049] Advantageously, the flap is brought into an active position during the fibre rerouting, to press the fibre against the roller. The downstream functional modules have a guiding plane P1 with a small angle α1, and as a result, are more sensitive to fibre rerouting issues. In the absence of flap, the fibre exiting the guiding system tends to follow the guiding plane P1 and to hit the lay-up surface before passing under the roller. According to an embodiment, only the downstream modules are each equipped with a retractable flap. During their re-routing, the flap allows the fibre to be oriented against the roller towards the nip zone, so that the end of the fibre is nipped and compacted by the roller. As soon as the end of the fibre is no longer compacted by the compaction roller, the flap can be returned to its retracted position, so that the fibre exiting the guiding system is more heated by the radiation, and thus the lay-up can be performed at high speeds. The cylinder 71 can be controlled by its own pneumatic valve system. For the sake of space, the cylinder may be controlled by the same valve system used for the fibre re-routing means.

[0050] When a fibre is cut by the cutting means of the functional module, the end of the cut fibre exiting the guiding system may tend to come against the heating system, in particular the waveguide formed by the quartz 52, especially in the case of fibres having a certain rigidity, which may lead to a clogging of the quartz and thus a deterioration of the heating quality. Advantageously, the flap is brought to the active position when a fibre is cut, so that the end of the fibre is pressed by the flap against the roller.

[0051] According to an embodiment, the downstream and upstream modules are each equipped with a retractable flap as described above.

[0052] According to other embodiments, the aforementioned flash lamp heating system is replaced with a laser type heating system.

[0053] The fibres are preferably flat continuous fibres, such as tows, pre-impregnated with a thermosetting resin or a thermoplastic resin, or dry fibres provided with a binder. The binder is in the form of powder and/or one or more veils, preferably of the thermoplastic type.

[0054] The head can be adapted for lay-up of fibres of various widths, but is particularly advantageous for lay-up of fibres of at least one-half inch wide, for example one inch, one and one-half inches, or two inches. For widths up to one-half inch, the fibres can be wound into helical winding spools. For widths greater than one-half inch, the fibre is wound into a spool or cassette without traverse winding.

[0055] According to another embodiment, the retractable flap according to the invention is mounted on a head comprising a single compaction roller and equipped with a guiding system for guiding a plurality of fibres towards the roller in the form of a band of fibres in which the fibres are arranged edge to edge. In this case, the head comprises a flap advantageously having a plurality of flexible tabs, as described in the aforementioned patent WO2013/030467, each tab being able to press on the face of a fibre opposite the roller in order to press said fibre against the roller.

[0056] Although the invention has been described in connection with a particular embodiment, it is clear that it is by no means limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.