METHOD FOR MANUFACTURING A PART MADE OF COMPOSITE MATERIAL

Abstract

A method for manufacturing a part made of composite material includes three-dimensionally weaving a structure having a longitudinal axis (A). The method further includes the step of braiding of at least one layer of braiding threads at at least one predetermined angle relative to the longitudinal axis around the woven structure.

Claims

1. A method for manufacturing a composite material part, the method comprising the steps of: weaving three dimensionally a structure having a longitudinal axis, and braiding at least one layer of braiding threads at at least one predetermined angle relative to the longitudinal axis around the structure.

2. The method according to claim 1, further comprising a step of resin transfer molding the woven structure prior to the braiding step.

3. The method according to claim 1, further comprising a step of resin transfer molding after the braiding step to form the part with a final shape.

4. The method according to claim 1, wherein the braiding comprises braiding at least two layers and wherein the predetermined angle of the braiding threads of one braiding layer is different from one braiding layer to another.

5. The method according to claim 1, wherein the angle along the longitudinal axis is between 15 and 75.

6. The method according to claim 1, wherein the predetermined angle varies along the longitudinal axis during the braiding of a layer.

7. The method according to claim 6, wherein the angle along the longitudinal axis varies between 15 and 75.

8. The method according to claim 6, wherein the woven structure comprises a first segment and a second segment and wherein for a braiding layer the predetermined angle (1) of weaving about the second segment is greater than the predetermined angle (2) of weaving about the first segment.

9. The method according to claim 1, wherein the structure is formed of warp threads and first weft threads and comprises an area formed of warp threads and second weft threads and wherein the second weft threads are finer than the first weft threads and the number of second weft threads is smaller than the number of first weft threads.

10. The method according to claim 1, wherein the weaving threads and/or the braiding threads are carbon or glass.

11. A composite material part manufactured by the method according to claim 1, the part being a composite material spar for a turbomachine vane.

12. The method according to claim 7, wherein the angle along the longitudinal axis varies between 45 and 75.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0043] Further characteristics and advantages of the invention will become apparent from the following detailed description, for the understanding of which reference is made to the attached drawings in which:

[0044] FIG. 1, already described, is a schematic side view of a turbomachine vane covered by the invention;

[0045] FIG. 2 is a flowchart of a method for manufacturing a composite material part according to the invention;

[0046] FIG. 3 is a schematic perspective view of a structure obtained by 3D weaving according to a step in the method of the invention; and

[0047] FIG. 4 is a schematic front view of a spar comprising different braid segments.

DETAILED DESCRIPTION OF THE INVENTION

[0048] Referring to FIG. 2, a method for manufacturing a composite material part comprises a step S10 of three-dimensional weaving of a structure having a longitudinal axis noted A. In the remainder of the description, the part to be manufactured is a spar for a turbomachine vane such as that shown in FIG. 1. However, the invention can be applied to any part that has to be subjected in tension, bending and torsion, such as parts for renewable energy devices like wind turbines or aeronautical propulsion devices, for example fan vanes, whether rotating (rotor), ducted (fan) or unducted (propeller) and with variable or stationary pitch.

[0049] During this 3D weaving step, a 3D woven structure 20 or preform is produced from threads or fibres made of carbon, glass or any other composite material.

[0050] As shown in FIG. 3, this is essentially a conventional weaving with warp strands, threads or fibres 21 running in the span wise direction and weft strands, threads or fibres 22 running around the profile in a substantially perpendicular direction. The preform is woven on an industrial loom. The direction of weaving is indicated by the arrow F. The direction of the warp threads forms the longitudinal direction of the woven structure.

[0051] In the 3D woven structure, all the strands, for example of carbon, are woven into each other, by corrugating/entangling the warp threads between the weft threads, to form the fabric that holds the assembly together.

[0052] According to one variant, the structure may comprise one or more areas that are quasi-unidirectional from a mechanical point of view, i.e. in which the weft threads are finer and less numerous than in the rest of the structure so that the warp threads are virtually straight, thereby locally increasing the stiffness in the warp direction of the structure.

[0053] Advantageously, the method also comprises a step S20 of consolidating the preform obtained by injecting and polymerising a resin to obtain a mechanical strength using a known resin transfer moulding (RTM) method. At the end of this step, the raw structure is obtained.

[0054] The method also comprises a step S30 of machining the raw structure to obtain the geometry on which the braid will be made.

[0055] The method also comprises a step S40 of braiding at least one layer of braiding threads at at least one predetermined angle to the longitudinal axis around the woven structure. Advantageously, the predetermined angle of braiding around the woven structure along the longitudinal axis is between 15 and 75, preferably between 45 and 75.

[0056] The braiding is carried out using carbon or glass threads or fibres on an industrial braiding machine.

[0057] The consolidated and machined 3D woven structure is then placed in a braiding machine to add braid to its external surface. In this way, the woven structure acts as a mandrel for the braiding.

[0058] Several layers may be necessary to obtain the target thickness of the part to be produced. The braiding parameters must be defined as a function of the thickness and orientation of the fibres in question, i.e. as a function of the ratio between the tension/bending force and the torsional force to which the part must respond.

[0059] Advantageously, the predetermined angle of the braiding threads relative to the longitudinal axis of the structure can be different from one braiding layer to another.

[0060] In addition, the predetermined angle can advantageously vary along the longitudinal axis during the braiding of a layer, thus allowing predetermined mechanical performances to be obtained. Advantageously, the angle along the longitudinal axis can vary between 15 and 75 and preferably between 45 and 75.

[0061] According to the example of a spar manufactured according to this embodiment and illustrated in FIG. 4, the predetermined angle 1 of weaving around a lower segment 24 intended to be close to the root 9 of the vane, is advantageously greater than the predetermined angle 2 of weaving around an upper segment 26, intended to be closer to the head 10 of the vane than the lower segment 24, thus allowing the fibres of the lower portion to be as close as possible to the circumferential direction of the part. The lower segment, which is intended to be close to the vane root, will be subjected mainly to circumferential compression. This will be partially compensated for by the circumferential orientation of the braid in this segment.

[0062] In this way, the orientation of the fibres allows the local stiffness of the part to be optimised according to the load it has to support, resulting in a part with greater mass performance.

[0063] Alternatively, the orientation of the braid threads or fibres can of course remain constant along the longitudinal axis of the part in order to simplify the manufacturing method or when the distribution of the forces is uniform over the part.

[0064] Preferably, the method continues with a step S50 of consolidating the braid obtained by injecting and polymerising a resin to obtain a mechanical strength using the resin transfer moulding (RTM) method.

[0065] Preferably, the method comprises a further step S60 of machining the consolidated part to obtain the final geometry of the part.

[0066] The method described in the embodiment comprises two resin injection steps: one to consolidate the woven structure and the other to consolidate the braid.

[0067] In one variant, the method comprises a single resin injection step, allowing to reduce the manufacturing time and costs. In this case, the method comprises a step to stiffen the woven structure so that it can be machined, for example by adding a tackifier to the structure.