EP2191029B1 - Mechanical part including an insert made of a composite material - Google Patents

Description

The present invention relates to a mechanical part comprising an insert made of composite material of the type consisting of ceramic fibers in a metal matrix, as well as a method of manufacturing this mechanical part and a winding device designed for implementing the manufacturing method. . The invention applies to any type of mechanical part whose function is to transmit a traction force and / or compression mainly unidirectional.

In the aeronautical field, in particular, a constant objective is the optimization of the resistance of mechanical parts for a minimum mass and size. Thus, some mechanical parts may comprise an insert made of composite material with a metal matrix, such parts being able to be monobloc. Such a composite material comprises a matrix of metal alloy, for example titanium alloy Ti, within which fibers extend, for example ceramic fibers of SiC silicon carbide. Such fibers have a much higher tensile and compressive strength than titanium. It is therefore mainly the fibers that take up the efforts, the metal alloy matrix ensuring a binder function with the rest of the part, as well as protection and insulation of the fibers, which must not come into contact with each other. others. In addition, the ceramic fibers are resistant to erosion, but must necessarily be reinforced with metal.

The composite materials as described above are known to be used, in the aeronautical field, for the manufacture of disks, shafts, bodies of jacks, housings, spacers or as reinforcements of single-piece parts such as blades.

A technique for manufacturing these parts is described in the document FR 2886290 , representative of the technological background of the invention, in which one of the essential manufacturing steps consists in winding a bundle or a ply of coated wires around a piece of circular revolution perpendicular to the axis of rotation thereof. The described parts thus obtained are of circular type and are particularly suitable for producing circular parts such as shafts, cylinder bodies, housings or discs. The patent US3669364 describes the manufacture of a panel by winding wires coated around a mandrel and forming the workpiece after diffusion welding. DE10005250 describes the manufacture of a piece of complex shape by winding son coated around a mandrel followed by shaping the assembly before diffusion welding.

However, some mechanical parts require properties different from those presented by the circular parts. This is the case in particular connecting rods, essentially oblong shape, whose function is to transmit a tensile force and / or unidirectional compression.

A metal matrix rod reinforced with conferred ceramic fibers is described by US Patent 4671336 .

The invention particularly relates to a method of manufacturing a mechanical part comprising at least one composite material insert of the type consisting of ceramic fibers in a metal matrix capable of transmitting tensile forces and / or unidirectional compression between its ends .

For this purpose, the invention relates to a method for manufacturing a mechanical part according to the features of claim 1.

The mechanical part thus obtained, for example a connecting rod, advantageously makes it possible to transmit unidirectional traction and / or compression forces.

• la figure 1 représente une vue en perspective d'un exemple de pièce mécanique selon l'art antérieur ;
• la figure 2 représente une vue en perspective d'un exemple de dispositif de bobinage selon l'invention ;
• la figure 3 représente une vue en perspective d'un exemple d'insert obtenu selon le procédé de fabrication de l'invention ;
• la figure 4 représente un exemple d'insert, de conteneur destiné à accueillir l'insert et de couvercle métallique destiné à recouvrir de manière étanche le conteneur et l'insert ;
• la figure 5 représente une vue en perspective d'un exemple de pièce mécanique obtenue selon le procédé de fabrication de l'invention ;
• la figure 6 représente une variante du procédé de fabrication de l'invention ;
• la figure 7 représente une vue en coupe d'un autre exemple de pièce mécanique obtenue selon la variante du procédé de fabrication de l'invention ; et
  • la figure 8 représente une vue en perspective de l'exemple de pièce mécanique obtenue selon la variante du procédé de fabrication de l'invention.

Other advantages and characteristics of the invention will emerge on reading the detailed description which follows with reference to the appended figures in which:

• the figure 1 is a perspective view of an example of a mechanical part according to the prior art;
• the figure 2 is a perspective view of an exemplary winding device according to the invention;
• the figure 3 represents a perspective view of an example of an insert obtained according to the manufacturing method of the invention;
• the figure 4 represents an example of an insert, a container for receiving the insert and a metal lid for sealingly covering the container and the insert;
• the figure 5 is a perspective view of an example of a mechanical part obtained according to the manufacturing method of the invention;
• the figure 6 represents a variant of the manufacturing method of the invention;
• the figure 7 is a sectional view of another example of a mechanical part obtained according to the variant of the manufacturing method of the invention; and
  • the figure 8 represents a perspective view of the example of mechanical part obtained according to the variant of the manufacturing method of the invention.

The techniques for manufacturing a mechanical part, comprising an insert made of composite material, described in the document FR 2886290 can be used in the context of the present invention. Thus, the teaching of this document must be considered as incorporated in the present application, for example, and without limitation, the structure of the coated wires, their manufacture, the manufacture of a bonded ply of coated wires, the joining together of this web is on the metal support on which it is wound or to the lower layer ply, the welding of the son by laser or by contact between two electrodes, hot isostatic compaction and machining.

The figure 1 represents an example of a mechanical part such as a rod 1 whose shape is generally oblong, that is to say of elongated shape. It has two ends 13 and 14. The function of a connecting rod 1 is to transmit a movement, and / or tensile forces T and / or compression C, between two parts articulated at its ends along parallel axes Z1 and Z2 . The rod 1 has at each of its ends 13 and 14 a cylindrical recess 11 or 12 whose axes correspond to the parallel axes Z1 and Z2. This type of rod 1 can be used, for example, in the design of the undercarriages or in that of turbomachines comprising rods for taking up thrust force.

The figure 2 represents an example of winding device 20 according to the invention. In this example, the winding device 20 is particularly suitable for producing an insert for a mechanical part such as a connecting rod. This winding device 20 comprises a hollow mandrel piece 2 of oblong shape acting as mandrel and two flanges 21 and 22 oblong and substantially identical. The mandrel part 2 has a geometry of revolution, that is to say a geometry describing a closed structure usually curved. The dimensions of the flanges 21 and 22 are greater than the dimensions of the mandrel part 2 so that the periphery 27 of each flange 21 and 22 extends beyond the periphery of the mandrel part 2. The mandrel part 2 is sandwiched between the flanges 21 and 22. The threads 32 are wound on the mandrel piece 2 when the winding device 20 is rotated along the winding axis Z. The flanges 21 and 22 retain axially the son coatings 32 and guide them.

The winding device 20 belongs to an assembly forming a winding system. The winding system further comprises means for rotating the winding device 20 and means for providing a bundle or a bonded sheet of coated threads 32.

The chuck part 2 comprises two rectilinear winding portions 24. These straight winding portions 24 are oriented perpendicular to the winding axis Z. Thus, at least a part of the winding of the wires 32 around the mandrel part 2 is performs in a rectilinear direction. The winding of the coated wires 32 is carried out perpendicularly to the winding axis Z, in other words, the coated wires 32 are substantially oriented perpendicularly to the winding axis Z.

In the example shown on the figure 2 these rectilinear winding portions 24 are parallel and interposed between two circular portions 25. It is possible to vary the dimensions of the mandrel part 2, in particular its thickness in the axial direction Z, the length of the rectilinear winding portions 24 and the radius of curvature of the circular pieces 25, depending on the dimensions of the desired insert 3. The circular pieces 25 may also have different radii. Thus, the portions of rectilinear windings 24 may not be parallel.

The winding around the chuck part 2 having rectilinear winding portions 24 allows to generate in a short time an insert 3 having at least one rectilinear generator consisting of a large number of coiled son 32 parallel and unidirectional.

The insert 3, once wound, can be removed from the winding device 20 by separating the flanges 21 and 22 from one another. The shape of the insert 3 thus formed must be fixed to prevent the son 32 lose their orientation. Several techniques can be implemented for this purpose.

A first technique for maintaining the shape of the insert 3 consists in providing, at the beginning of winding, a step of winding a first metal foil for hooking up the inner part of the insert 3 and, at the end of winding, a step of winding a second metal foil 28 of attachment of the outer part of the insert 3. In this example, the first metal foil constitutes the mandrel piece 2. The coated son 32 are thus between the foils 2 and 28, as shown on the figure 3 .

Moreover, as illustrated on the figure 2 each flange 21 and 22 has notches 23 on its periphery 27. Each notch 23 of the flange 21 is disposed opposite a notch 23 of the flange 22, thus forming a pair of notches 23. The fixing metal straps 31 is facilitated by the dimensions of the notches 23 extending inwardly of the flanges 21 and 22 to a depth d. The depth d of the notches 23 must be such that it is possible to access the hollow interior 29 of the chuck part 2 which is arranged around a hub of the winding device 20, not visible on the figure 2 , comprising an alternation of notches and teeth, the notches of the hub being in phase with the notches 23 of the flanges 21 and 22. The depth d extends beyond the winding surface of the mandrel piece 2.

Each pair of notches 23 is intended to allow the attachment of a metal strap 31. The metal straps 31 are made of a metallic material identical to that of the container 4, described in connection with the figure 4 and the chuck part 2. The metal straps 31 are fixed around the insert 3 by a contact welding process. The metal straps 31 are arranged at regular intervals on the wound insert 3.

Once the insert 3 coiled and the metal straps 31 put in place, it can be removed from the winding device 20 by separating the flanges 21 and 22 from one another. An example of insert 3 thus obtained is represented in figure 3 . It consists of an oblong-shaped mandrel piece comprising two rectilinear and parallel portions 34 interposed between two circular portions 35.

A second technique for maintaining the shape of the insert 3, which does not require the use of straps 31, consists in providing a mandrel-forming piece 2 forming an oblong mandrel comprising at least one radial flange, for example of L-shaped cross-section or in U, on which the wires 32 are wound. When a bonded sheet of coated son 32 is used, it is possible to secure it to the mandrel piece 2 on which it is wound and to the sheet of the lower layer by means of a method by contact welding between two electrodes and passage of a medium frequency current. The wires 32 are thus welded as the winding progresses so that, when the insert 3 is extracted from the winding device 20, it forms a part integral with the mandrel part 2.

The insert 3 is then inserted into a container 4, as shown in FIG. figure 4 . The container 4 comprises for this purpose a groove 41 of complementary shape to the insert 3 and in which is housed the insert 3. The container 4 is the preform of the metal alloy matrix, preferably titanium Ti. A lid 5 is attached to the container 4 by electron beam welding, evacuated, and then compacted by a hot isostatic compaction process.

The assembly is then machined to obtain the final mechanical part 10: a rod 10, represented on the figure 5 . The rod 10, of identical shape to the rod 1 of the figure 1 , further comprises an insert of composite material 3, with a geometry of revolution, whose son 32 are partly oriented in a rectilinear direction. This rectilinear direction is perpendicular to the axes Z1 and Z2. This link 10 advantageously allows to transmit the unidirectional traction and / or compression forces. The rectilinear portions 34 of the inserts 3 comprise son all oriented in the same rectilinear direction.

The invention applies to any type of mechanical part whose function is to transmit a traction force and / or compression mainly unidirectional and is therefore not limited only to connecting rods that are only an example of application.

Claims (7)

1. Method for producing an elongated mechanical part (10, 110) having two ends and a cylindrical aperture (11, 12) at each end, the axes (Z1, Z2) of the apertures being mutually parallel, characterised in that an insert (3) made of composite material is produced by winding a plurality of coated wires (32), which form a bundle or a bonded mat and each comprise a ceramic fibre encased in a metal sheath, around a part (2) which forms a mandrel, at least a portion of the winding taking place in a rectilinear direction, the part (2) which forms a mandrel comprising two portions of rectilinear winding (24) interposed between two circular portions (25), and the insert being inserted, after formation, into a container (4) having a groove, the shape of which is complementary to that of the insert (3), and covered by a lid (5) in order to undergo hot isostatic compaction therein, the assembly then being machined in order to form said elongated mechanical part having two cylindrical apertures and ceramic fibres which are perpendicular to the axes of the apertures.
2. Method for producing a mechanical part (10, 110) according to claim 1, wherein the two circular portions (25) have different radii.
3. Method for producing a mechanical part (10, 110) according to either of the preceding claims, comprising the incorporation of two inserts (3) on each side of two opposite surfaces (42) of a container (4) in order to undergo hot isostatic compaction.
4. Method for producing a mechanical part (110) according to the preceding claim, comprising the positioning of the inserts (3) in planes (P2,P2) which form a non-zero angle α.
5. Elongated mechanical part (10, 110) having two ends and a cylindrical aperture at each end, comprising at least one insert (3) made of metal matrix composite material, within which ceramic fibres extend, the composite material insert (3) being obtained from a plurality of coated wires (32), which each comprise a ceramic fibre encased in a metal sheath, characterised in that the insert (3) has a geometry which describes a closed structure and the ceramic fibres of which are oriented, in part, in at least one rectilinear direction between the two cylindrical apertures (11, 12).
6. Mechanical part (110) according to claim 5, comprising at least two inserts (3) which are positioned on each side of a central plane (P1) of the mechanical part (10).
7. Mechanical part (110) according to claim 6, wherein the two inserts (3) are positioned in planes (P2, P3) which form an angle α between each other.

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