EP2552629B1 - Method of manufacturing an elongate insert made of a metal matrix composite - Google Patents

Description

The present invention relates to the field of composite metal matrix materials and more particularly to a method of manufacturing an insert formed of ceramic fibers in a metal matrix to reinforce a metal part.

In the field of aeronautics, in particular, a constant objective is the optimization of the resistance of the parts for a minimum mass and a bulk. Some parts may now include a composite metal matrix insert, hereafter referred to as CMM, the part possibly being monolithic. 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 tensile strength much higher than that of titanium (typically 4000 MPa against 1000 MPa). It is therefore 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. other. In addition, the ceramic fibers are resistant to erosion, but must necessarily be reinforced with metal.

These composite materials can be used in the manufacture of disks, shafts, cylinder bodies, housings, spacers, as reinforcements of monolithic parts such as blades, etc.

For compressor disks in a turbojet engine, for example, a known reinforcement technique consists in inserting a circular winding of coated fibers into the part. A CMM insert manufacturing technique is based on the principle of coated wire winding described in the patent EP 1.726.677 deposited in the name of Snecma. The insert is obtained from a plurality of coated yarns each comprising a ceramic fiber coated with a metal sheath. This type of yarn is referred to as coated yarn thereafter. The manufacture comprises a step of winding a bundle or a sheet connected son son coated around a piece of revolution perpendicular to the axis of the piece. The insert is then subjected to a hot isostatic pressing step in a container. A container is a blank of a metal part in which a cavity for receiving the insert made of CMM material has been machined and which is then subjected to a hot isostatic compaction treatment. This treatment is designated CIC thereafter.

The described parts thus obtained are of circular type and are particularly suitable, in addition to the compressor discs for producing circular parts such as shafts, cylinder bodies or housings.

Other mechanical parts require properties different from those presented by the circular parts. This is particularly the case of rods used for example in landing systems or structural parts such as engine suspensions, substantially oblong shape. The function of these parts is to transmit a tensile force and / or unidirectional compression. The reinforcement of these parts then requires CMM inserts of rectilinear or substantially rectilinear shape, at least in part. Indeed, the fibers must be oriented in the direction of the efforts.

The manufacture of these inserts industrially and at the least cost is delicate.

There is known a method of manufacturing a mechanical part comprising at least one insert of CMM material. The method comprises producing an insert blank by winding a bundle or a bonded web of coated wires around an annular support, a portion of which comprises a rectilinear or substantially rectilinear portion, as described in FIG. document EP-1950003-A1 .

The process described in the patent FR 2,919,284 to Snecma and Messier-Dowty , develops this principle and then comprises inserting the above insert blank into a first metal container, hot isostatic compaction of the first container, followed by machining thereof to form an element. insert. After the manufacture of this insert member, the method of manufacturing a mechanical part comprises the following steps: insertion of the insert element into a second container, hot isostatic compaction of the second container and machining of the second container for form the desired mechanical part. The mechanical part thus obtained, for example a connecting rod, advantageously makes it possible to transmit unidirectional tensile and / or compressive forces in the direction of the ceramic fibers that have been integrated therein.

Instead of going through the intermediate step of compaction of the insert blank followed by its cutting into rectilinear insert elements, it is conceivable to cut the annular coil forming the blank while maintaining the bundled coated wires. . The patent application FR 2,925,896 teaches to incorporate this type of beam in a rectilinear groove opening at its ends.

This solution has several drawbacks that impact the industrialization of these operations:
The coated wires are lost at the non-straight parts. This loss is not negligible because the semi-finished wire product represents a significant cost in the total cost of the part.

The winding, in particular on oval shapes, induces stresses in the wound insert that may loosen resulting in deformation of the insert during cutting.

These techniques require the multiplication of the maintenance systems of the coated wires to the right of the cutting zones.
Moreover, a technique based on the winding by winding of a ply of pre-assembled coated yarns is essentially aimed at producing inserts of cross section, perpendicular to the fibers, square or rectangular.
For some applications, it would be desirable to have an insert of different section square or rectangle to improve the recovery of forces between the composite insert and the rest of the structure of the room. Indeed, sectional reinforcements, for example trapezoidal or elliptical, would avoid or at least limit stiffness jumps and thus improve the mechanical strength of the transition zones.
For example, for elongated parts such as landing gear pieces or engine suspension connecting rods having lateral fasteners between their ends, a reinforcement whose number of fibers is lower along the edge of the integral piece of the fastener allows a better transition of efforts at the latter.
The patent US3828417 discloses a method for forming a bundle of coated fibers. However, it appears that the product obtained is not able to form an insert in the context of a CIC process.
The objective of the present invention is the development of a technique for making inserts at reduced cost and easily industrializable.
The invention also aims a manufacturing technique that allows the realization of so-called form inserts that is to say whose cross section may be different from the square or rectangular shape.
This object is achieved by a method of manufacturing an elongated insert according to claim 1. Preferably, the beam is formed from coated yarns which are unwound from yarn packages.

The bundle of wires before it passes through the shaping element has interstitial spaces resulting from the circular section of the coated wires. The shaping element is dimensioned so as to reduce the expansion of the wires and the interstitial spaces while giving the beam the desired shape. This solves the problem of industrialization and formatting of the wire bundle. The passage section of the shaping element is chosen freely according to the shape, in the transverse plane, desired of the insert.

According to one embodiment, the shaping element comprises at least two rotary rollers, the axes of the two rollers being oriented perpendicular to the direction of advancement of the coated son. To complete the contour, the shaping element comprises in particular fixed lateral supports between the rollers. The shaping element may also comprise a plurality of rollers constituting the contour of the passage section. The function of the rollers is to reduce the friction on the bundle of coated threads accompanying its movement. Fixed elements are also suitable insofar as the friction of the fibers is reduced.

It is thus possible to form a shaping element whose passage section is polygonal with rectilinear or curved sides or of oval or circular section.

In order to facilitate the guiding of the fibers to the shaping element and subsequently to hold them together in the bundle, a metal foil, also referred to as a foil, is advantageously interposed between the coated strands of the bundle and at least a portion of the sides of the shaping element. .

Maintaining the assembly of coated son by rings or rings placed along the insert downstream of its passage through the shaping element. The rings are formed for example of a metal sheet, forming a strap with which the beam is tightly wrapped and whose ends are welded after being folded over one another.

The bundle of coated wires is then cut to the desired length corresponding to the length of the insert to be placed in the metal container. To avoid the proliferation of son coated end of the insert, making it difficult to handle it and its introduction in the container, it is advisable to saw the beam through a clamping ring because the ring portions obtained are placed at the end and ensure the tightening of the beam.

According to one implementation of the method, the son coated before their bundling are guided in their movement towards the shaping element so as to form subassemblies or elementary beams. It may be sheets that are superimposed on each other to form said beam. An elementary beam is formed by simultaneously unwinding the coated son of the subassembly from separate coils. For example one can thus form a stack of plies of rectilinear coated son obtained by flat juxtaposing a given number of coated son, until a number of layers determined. More particularly, a first ply is deposited on a bearing surface, in particular comprising a metal sheet, and the last sheet is covered through the shaping element. Instead of plies, the elementary beams can have any shape of cross section.

According to another embodiment, the son is coated in elementary bundles in a plurality of guides, chutes or tubes which are arranged to converge towards the passage section of the forming element.

The method of the invention is a step of a method of manufacturing a metal part comprising the incorporation of the insert thus formed into a metal container and hot isostatic compaction of the assembly, as described by example in the patent application FR2933422 or the request FR2933423 in the name of Messier Dowty .

• au moins un logement pour un insert est usiné dans un corps métallique formant le conteneur,
• ledit insert est disposé dans le logement,
• un couvercle métallique est placé sur le corps de façon à recouvrir l'insert,
• le couvercle est soudé sur le corps métallique,
• l'ensemble du corps métallique avec couvercle est soudé par compression isostatique à chaud et
• on usine ledit ensemble traité pour obtenir ladite pièce.

According to this type of process,

• at least one housing for an insert is machined in a metal body forming the container,
• said insert is disposed in the housing,
• a metal cover is placed on the body so as to cover the insert,
• the lid is welded to the metal body,
• the entire metal body with cover is welded by hot isostatic compression and
• said treated assembly is machined to obtain said workpiece.

The solution of the invention allows the incorporation of the insert in a container, immediately downstream of the shaping element. For example, the container may comprise a longitudinal through housing in which it comes to slide the bundle of coated son.

The invention will be better understood and other features and advantages thereof will become more clearly apparent in the following detailed explanatory description of embodiments of the invention given by way of purely illustrative and non-illustrative example. limiting with reference to the attached schematic drawings.

• La figure 1 montre les différentes étapes 1a, à 1d de fabrication d'une pièce de forme allongée selon l'art antérieur ;
• La figure 2 représente une vue de côté d'une installation de fabrication d'un insert rectiligne conforme à l'invention ;
• La figure 3 montre l'installation de la figure 2, vue de face ;
• La figure 4 montre un insert fabriqué conformément à l'invention ;
• La figure 5 montre une variante de filière de forme.

On these drawings

• The figure 1 shows the different steps 1a to 1d of manufacturing an elongate piece according to the prior art;
• The figure 2 represents a side view of an installation for manufacturing a rectilinear insert according to the invention;
• The figure 3 shows the installation of the figure 2 , front view ;
• The figure 4 shows an insert manufactured according to the invention;
• The figure 5 shows a variant of shape die.

On the figure 1a , extracted from the patent application FR 2,919,284 to Snecma and Messier-Dowty we see a container 1 with a main body 4 of elongate shape, intended to form a connecting rod of a landing gear for example. It has machined a groove 41 on each of the two faces of the body 4. This groove allows the housing of an insert 3 which comprises two straight portions parallel or not between them joined at the ends by a portion in an arc. The inserts are of the ceramic fiber type coated with metal such as titanium.

The grooves and the inserts are complementary shapes so that the insert is fit without play in the groove. Note that the groove in the container and the pin on the lid must be perfectly assembled to prevent the fibers, which have a very small diameter, of the order of 0.25 mm, can not escape during the hot isostatic compaction. Two covers 5 are provided with a projecting portion forming a pin 51 and cover the faces of the body 4. The ten bears on the insert housed in the groove and closes the latter. The cover 5 is welded, for example by electron beam, to the body 4, providing a vacuum inside the container.

The container is visible on the figure 1b ; it is partly torn off to show the inserts. The container is then placed in a suitable enclosure to undergo hot isostatic compaction treatment. This treatment is intended to make the container, its lid and the plies of coated son solidarity with each other and form a monolithic piece. The cross-section of the container of the figure 1c shows that the edges 42 of the groove 41 are chamfered so as to provide clearance with the portion of the cover 5 adjacent to the pin 51. During the hot isostatic compaction operation, the pressure is exerted in the direction perpendicular to the surface of the cover causing the collapse of the covers.

The heat and the pressure, respectively of the order of 1000 ° C. and 1000 bars allow the metal of the matrix to fill the voids between the coated wires constituting the insert. The volume of the insert decreases by about 23%. The post is thus moved towards the bottom of the groove and the game on either side of the post is absorbed. At the end of the process, the metal parts soldered by diffusion and the coated wire insert compacted; the part is thus reinforced by the coated threads imprisoned in the mass.

The figure 1d represents the part blank obtained with two inserts visible in transparency. The blank is then machined to obtain the desired part. The ceramic fibers are thus incorporated in the areas of the part which ensure the transmission of the forces in traction and compression.

The inserts used according to the teaching of this patent FR 2 919 283 are ring-shaped but as described in the patent application FR 2 919 284 they can be formed of elongated elements in bars. In the latter case the inserts are incorporated, according to the technique described in this document, in the container after having been compacted beforehand.

The realization of rectilinear inserts according to FR 2 919 284 comprises winding the coated wires around a ring-shaped winding device with rectilinear portions. The shape may be oblong, with rectilinear portions, or polygonal whose sides of the polygon constitute the rectilinear portions.

After forming the winding of the son or son coated in a ring, the turns of the ring are immobilized together by means of welded metal straps. The assembly is incorporated in a container and undergoes hot isostatic compaction treatment according to the technique described above. From the semi-finished part, elongated compact inserts are manufactured which are individually incorporated into containers for the manufacture of parts with ceramic fiber reinforcements.

According to the invention, the embodiment of the inserts is simplified by forming inserts of elongate shape made directly of coated wires 13 assembled in the manner of bundles or bundles.

Referring to the figure 2 an example of an installation for carrying out the method of the invention comprises a reel 10 supporting a plurality of rows of reels 12 on which the coated wires 13 are wound. Coated wires are driven from their respective coils in a system slides chute 14 to which they converge. The system gathers the coated wires into a bundle. At this stage the beam is relatively abundant. The coated yarns are advantageously arranged in a plurality of subassemblies or layers of coated yarns 13 juxtaposed, parallel to each other.

A foil or foil 16, thin, is disposed on the bottom of the gutter-shaped tool 14. The metal foil is preferably the same as that of the metal part to which the insert is intended. This is for example a titanium alloy.

Coated son rest on the lower foil 16. They are stacked on each other for example in layers. The width of the plies, the number of coated threads which constitute the plies, may vary from the base to the upper ply. For example, the beam may have a trapezoidal shape in section. A foil 15 is placed on the top of the stack of plies son coated.

The number of threads in the plies is not limiting, it depends on the part to be manufactured, the representation of the figures is merely indicative, the diameter of the threads is not at the same scale as that of the gutter. The coated yarns are juxtaposed in the webs without fluttering or with a minimum of floating between the yarns. At this stage the coated wires have not undergone any transverse stress.

Instead of layers, the wires can be arranged in sub-assemblies formed of elementary beams that are united in a single beam, 13f.

The beam 13f coated son is thus guided through the shaping element 17 where it undergoes a transverse compression. The shaping element here comprises two rollers 17g with horizontal axes. As we see on the figure 3 , the rollers are rotatably mounted in a frame 17b. The spacing between the two rollers can be adjusted by vertical displacement of their support. Appropriate motors possibly, not shown, drive them in rotation. The contour of the passage section of the shaping element is completed by two fixed supports, forming slides 17l, arranged laterally on either side of the beam. The supports 17l are integral with the frame 17b. According to this example, they are inclined relative to the vertical. The contour of the passage section of the shaping element is thus trapezoidal.

Passing through the shaping element, the bundle of coated wires takes the form of the shaping element, here trapezoidal. At the output of the shaping element, it is therefore necessary to maintain the beam in the given form.

Small foils 18 forming straps are then put in place to hold the assembly, by going around the bundle of coated wires.

The beam is thus pulled through the shaping element by means of a traction tool by means of clamps for example.

The insert 13i is shown finished at figure 4 .

It is understood that the present method is not limited to the production of inserts of square, rectangular or trapezoidal section. Many forms are within the reach of the skilled person. A plurality of rollers or rollers may be arranged in the shaping element around the beam to give it a polygonal shape. The sides of the polygon can be straight but they can also be curved. Just choose a suitable profile.

The shape and the transverse dimensions of the shaping element can be defined by the geometry and the dimensions of the insert that one wishes to use. In this case, the number of coated wires required to form the insert is determined. Conversely, an insert with a determined number of coated wires may be needed. In this case, the passage section of the shaping element is adjusted so that it can contain as output the desired number of coated wires.

It is advantageous to have guide members adjustable in position transversely to allow in the retracted position the establishment of the bundle of coated son before they are tight on the beam. The adjustment of the spacing of the rollers and the metal supports makes it possible to adjust the passage section and the output section of the bundle of coated threads.

It may also be advantageous to have vibrating elements promoting the compression of the coated wires in the bundle.

The figure 5 shows another non-limiting example of embodiment of the shaping element. It is formed of two rollers 17'g of horizontal axes and curved profile cooperating with two rollers 17'l of vertical axes and straight profile.

The present method also allows the realization of a plurality of inserts simultaneously, cutting the inserts in the length of the beam thus obtained.

The insert once finished; as represented in figure 4 , is incorporated in a metal container according to the known method and described above to form a metal part. Compared with the embodiment of the prior art illustrated by the figure 1 , of an elongated piece, grooves are made rectilinear in which there are two rectilinear inserts per side of the container. For the rest the process is the same.

According to a particular embodiment of the metal part, one of the foils is used both as a support and as a lid of the metal container in which the insert is disposed. The lid is welded to the container while realizing the vacuum in the room before the hot isostatic compaction treatment.

Claims (12)

1. Method for manufacturing an insert of elongate shape designed to be incorporated by CIC into a metal container, comprising coated yarns bound together, the said coated yarns being formed of metal-coated ceramic fibres, characterized in that it comprises a step consisting in placing the coated yarns (13) side by side in a bundle (13f) consisting of a plurality of layers of coated yarns, in pulling the bundle of coated yarns through a shaping element (17) so as to compact it transversely while forming it with a determined cross section by the shaping element, and in placing straps (18) transversely clamping the bundle, downstream of the shaping element.
2. Method according to the preceding claim, the shaping element (17) comprising at least two rotary rollers (17g) between which the bundle is guided.
3. Method according to the preceding claim, the two rollers having parallel axes.
4. Method according to the preceding claim, the shaping element comprising two lateral supports (171) between the rollers (17g).
5. Method according to one of the preceding claims, the passageway cross section of the shaping element (17) being polygonal with rectilinear or curved sides.
6. Method according to one of Claims 1 to 4, the passageway cross section of the shaping element being oval or circular.
7. Method according to one of Claims 1 to 4, the passageway cross section of the shaping element being rectangular or square.
8. Method according to one of Claims 1 to 4, the passageway cross section of the shaping element being trapezoidal.
9. Method according to one of the preceding claims, a metal sheet (15, 16) being interposed between the coated yarns of the bundle and at least one portion of the sides of the shaping element.
10. Method according to one of the preceding claims, wherein, before they are grouped into the bundle, the coated yarns are placed in elementary bundles that are assembled together to form the said bundle.
11. Method according to one of the preceding claims, the straps (18) being placed along the insert downstream of the shaping element.
12. Method for manufacturing a metal part comprising the following steps :

    - manufacturing an insert according to one of the preceding claims,

    - incorporation of said insert in a metal container, and

    - the hot isostatic compaction of the assembly.

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