WO2012117202A1

WO2012117202A1 - Method for producing a metal component such as a turbomachine blade reinforcement

Info

Publication number: WO2012117202A1
Application number: PCT/FR2012/050424
Authority: WO
Inventors: Thierry Godon; Bruno Jacques Gérard DAMBRINE; Alain Robert Yves Perroux
Original assignee: Snecma
Priority date: 2011-03-01
Filing date: 2012-02-29
Publication date: 2012-09-07

Abstract

The present invention relates to a method for producing a metal component such as a metal turbomachine blade reinforcement, comprising, in succession, a step of producing a plurality of three-dimensional metal structures (350) by securing together a plurality of metal clips (301'), each of said three-dimensional metal structures (350) forming a portion of a preform of said component to be produced; a step of positioning said plurality of three-dimensional metal structures (350) in a forming tool; a step of hot isostatic pressing of said plurality of three-dimensional metal structures (350) causing the agglomeration of said three-dimensional metal structures so as to obtain a solid component.

Description

PROCESS FOR PRODUCING A METAL PIECE

SUCH AS A TURBOMACHINE WAVE REINFORCEMENT.

The present invention relates to a method of producing a metal part such as a composite blade metal reinforcement or metal turbomachine.

More particularly, the invention relates to a method for producing a leading edge metal reinforcement or turbomachine blade trailing edge.

The field of the invention is that of turbomachines and more particularly that of the fan blades, made of composite or metallic material, of a turbomachine and whose leading edge comprises a metallic structural reinforcement.

However, the invention is also applicable to the production of a metal reinforcement intended to reinforce a leading edge or a blade trailing edge of any type of turbomachine, whether terrestrial or aeronautical, and in particular a helicopter turbine engine or an airplane turbojet engine, but also propellers such as propellers of double uncontrolled contra-rotating fans ("open rotor" in English).

The invention is also applicable to the realization of any massive metal piece and complex geometric shape.

It is recalled that the leading edge corresponds to the front part of an airfoil which faces the airflow and which divides the airflow into an intrados airflow and a flow of air. extrados air. The trailing edge corresponds to the posterior part of an aerodynamic profile where the intrados and extrados flows meet.

The turbomachine blades, and in particular the fan blades, undergo significant mechanical stresses, particularly related to the speed of rotation, and must satisfy strict weight and weight conditions. congestion. Therefore, blades made of composite materials are used which are lighter.

It is known to equip the fan blades of a turbomachine, made of composite materials, with a metallic structural reinforcement extending over the entire height of the blade and beyond their leading edge as mentioned in EP1908919. Such a reinforcement makes it possible to protect the composite blading during an impact of a foreign body on the blower, such as, for example, a bird, hail or pebbles.

In particular, the metallic structural reinforcement protects the leading edge of the composite blade by avoiding risks of delamination, fiber breakage or damage by fiber / matrix decohesion.

In a conventional manner, a turbomachine blade has an aerodynamic surface extending, in a first direction, between a leading edge and a trailing edge and, in a second direction substantially perpendicular to the first direction, between a foot and a dawn summit. The metallic structural reinforcement follows the shape of the leading edge of the aerodynamic surface of the blade and extends in the first direction beyond the leading edge of the aerodynamic surface of the blade to match the profile of the blade. the intrados and the upper surface of the dawn and in the second direction between the foot and the top of the dawn.

In known manner, the metal structural reinforcement is a titanium metal part made entirely by milling from a block of material.

However, the metal reinforcement of a blade leading edge is a complex piece to achieve, requiring many rework operations and complex tools involving significant realization costs.

It is known to produce massive parts, including metal reinforcements turbomachine blade from a fibrous structure three-dimensional metal made by wire weaving and a method of hot isostatic pressing in a tool causing the agglomeration of the metal son of the metal fibrous structure so as to obtain a massive piece, this method is described in the patent application FR0858098.

Conventionally, the weaving of the fibrous structure is carried out by weaving by means of a plurality of warp threads and metal weft threads, the thickness of the threads of which is limited to a diameter of the order of a few tenths of a millimeter, typically between 0.1 mm and 0.3 mm.

The fibrous structure thus obtained by weaving is a flat and relatively rigid structure that is necessary to deform to obtain a preformed fibrous structure so as to allow its introduction into a form tool.

To overcome this deformation step by a folder subsequent to the weaving of the fibrous structure and therefore limiting the dimensions of the fibrous structure, it has been developed a method of manufacturing a fibrous metal structure by successive weaving of metal staples, bent or folded so as to form for example a substantially U-shaped piece or V, acting as weft son. In this process described in the patent application FR1058237, weaving is performed by introducing each of the branches of the metal staples in at least one stride formed by two warp son.

However, weaving metal staples formed by folded metal son requires the use of a specific loom capable of forming two strides at the same time for the passage of each of the staple branches.

In this context, the invention aims at providing a method for producing a metal part, such as a turbomachine blade reinforcement, from a preformed three-dimensional metal structure. large size and does not require the use of a loom.

To this end, the invention proposes a method for producing a metal part, such as a turbomachine blade metal reinforcement, comprising successively:

a step of producing a plurality of three-dimensional metal structures by joining a plurality of metal staples formed by rectilinear metal sections bent or curved in the shape of a U or a V, each of said three-dimensional metal structures constituting a portion a preform of said part to be produced;

a step of positioning said plurality of three-dimensional metal structures in a form tool;

a step of hot isostatic pressing of said plurality of three-dimensional metal structures causing the agglomeration of said three-dimensional metal structures so as to obtain a massive piece.

The term "staple" means a metal piece bent or folded so as to form, for example, a substantially U-shaped or V-shaped part.

The term "three-dimensional metal preform" means a plurality of staples that are joined together and form part of a preformed metal structure.

Thanks to the invention, the metal part, such as for example a metal structural reinforcement comprising two curvatures in two distinct planes (or a twisting along an axis), is made simply and quickly from a plurality of metal structures three-dimensional formed by a plurality of staples joined together, obtained by a simple operation of forming rectilinear metal sections, and a method of pressing or hot isostatic pressing (HIP for hot isostatic pressing in English) allowing to get a piece compact and porosity-free by the combination of plastic deformation, creep and diffusion welding.

The metal staples are advantageously formed by the folding of the metal sections coming from a die which may be of circular, square, hexagonal, and so on.

The metal staples made and secured in portions, which may have variable lengths, are easily positionable in the shape tooling and thus make it possible to produce parts of complex geometry such as a blade reinforcement, parts having non-developable shapes, or else parts having enveloping shapes such as for example a part partially covering the ends of a blade.

This production method thus makes it possible to dispense with the complex realization of the blade reinforcement by machining in the mass, such as milling, broaching, from flats requiring large volume of processing material and consequently costs. important in raw material supply. The method also makes it easy to produce metal reinforcements that meet strict requirements of mass and / or geometric.

Advantageously, the metal part is a metal reinforcement of the leading edge or trailing edge of the turbomachine fan blade.

The method of producing a metal part according to the invention may also have one or more of the following characteristics, considered individually or in any technically possible combination:

said method is a process for producing a leading edge, or trailing edge, turbomachine blade or a metallic helical reinforcement, so that said massive piece obtained during said step isostatic pressing is a metal reinforcement; said step of producing a plurality of three-dimensional metal structures is performed by welding or gluing a plurality of metal staples;

said step of producing a plurality of three-dimensional metal structures is performed by welding or gluing a metal foil on said metal staples constituting a three-dimensional metal structure, said metal foil connecting each metal clip of a three-dimensional metal structure;

said step of producing a plurality of three-dimensional metal structures is performed by welding or bonding at least one wire to said metal staples constituting a three-dimensional metal structure, said at least one wire connecting each metal staple of a metal structure three-dimensional;

each of said staples comprises a first branch and a second branch, said welding or said bonding of said metal foil or said at least one wire being made on each first branch of each of said metal staples and / or on each second branch of each of said metal staples ; said staples and / or said at least one wire are formed by titanium-based metal wires and / or titanium-coated silicon carbide composite wires, and / or silicon carbide-based wires coated with Boron and / or silicon carbide-based silicon carbide-coated wires;

said step of positioning said plurality of metal structures is accomplished by positioning said plurality of metal structures in a die of said form tool; said step of positioning said plurality of metal structures is performed by positioning said plurality of metal structures on the punch of said form tool;

- Said step of positioning said plurality of metal structures is achieved by embedding the branches of said metal staples in embedding means arranged in said punch, said recess being formed by elastic deformation of said branches of metal staples;

said step of positioning said plurality of metal structures is carried out by embedding the branches of said metal staples in embedding means arranged in two rails forming a holding frame, said embedding being achieved by elastic deformation of said metal staple branches; said holding frame being positioned in a housing provided in said punch;

said method comprises a step of producing said metal staples by folding rectilinear metal sections, said staples being bent in the shape of a U and / or in a V shape.

Other characteristics and advantages of the invention will emerge more clearly from the description which is given below, by way of indication and in no way limiting, with reference to the appended figures, in which: FIG. 1 is a side view of a blade comprising a metal structural reinforcement of the leading edge obtained by means of the embodiment method according to the invention;

- Figure 2 is a partial sectional view of Figure 1 along a cutting plane AA;

FIG. 3 is a block diagram showing the main steps for producing a turbomachine blade leading edge metallic structural reinforcement of the embodiment method according to the invention;

FIG. 4 illustrates a view of the turbomachine blade leading edge metal reinforcement during the first step of the method illustrated in FIG. Figure 3;

FIG. 5 illustrates a view of the turbomachine blade leading edge metal reinforcement during the second step of the process illustrated in FIG. 3;

FIG. 6 illustrates a sectional view of the turbomachine blade leading edge metal reinforcement during the third step of the method illustrated in FIG. 3;

- Figure 7 illustrates a sectional view of the turbomachine blade leading edge metal reinforcement according to a first embodiment of the fourth step of the method illustrated in Figure 3;

FIG. 8 illustrates a sectional view of the turbomachine blade leading edge metal reinforcement according to a second embodiment of the fourth step of the method illustrated in FIG. 3

FIG. 9 illustrates a sectional view of the turbomachine blade leading edge metal reinforcement according to a third exemplary embodiment of the fourth step of the method illustrated in FIG. 3;

FIG. 10 illustrates a sectional view of the turbomachine blade leading edge metal reinforcement during the fifth step of the process illustrated in FIG. 3.

In all the figures, the common elements bear the same reference numbers unless otherwise specified.

FIG. 1 is a side view of a blade comprising a metallic leading edge structural reinforcement obtained by means of the embodiment method according to the invention.

The blade 10 illustrated is for example a mobile blade of a fan of a turbomachine (not shown).

The blade 10 has an aerodynamic surface 12 extending in a first axial direction 14 between a leading edge 16 and a trailing edge 18 and in a second radial direction 20 substantially perpendicular to the first direction 14 between a foot 22 and a vertex 24.

The aerodynamic surface 12 forms the extrados face 13 and intrados 1 1 of the blade 10, only the extrados face 13 of the blade 10 is shown in Figure 1. The intrados 11 and the extrados 13 form the lateral faces of the blade 10 which connect the leading edge 16 to the trailing edge 18 of the blade 10.

In this embodiment, the blade 10 is a composite blade typically obtained by shaping a woven fiber texture. By way of example, the composite material used may be composed of an assembly of woven carbon fibers and a resinous matrix, the assembly being formed by molding using an RTM-type resin injection process ( for Resin Transfer Molding) or VARTM (for Vccum Resin Transfer Molding).

The blade 10 has a metal structural reinforcement 30 bonded at its leading edge 16 and which extends both in the first direction 14 beyond the leading edge 16 of the aerodynamic surface 12 of the blade. dawn 10 and in the second direction 20 between the foot 22 and the apex 24 of the dawn.

As represented in FIG. 2, the structural reinforcement 30 matches the shape of the leading edge 16 of the aerodynamic surface 12 of the blade 10 that it extends to form a leading edge 31, said leading edge of the reinforcement .

Conventionally, the structural reinforcement 30 is a one-piece piece having a substantially V-shaped section having a base 39 forming the leading edge 31 and extended by two lateral flanks 35 and 37 respectively fitting the intrados 11 and extrados 13 the aerodynamic surface 12 of the dawn. Flanks 35, 37 have a tapered or thinned profile towards the trailing edge of the blade.

The base 39 has a rounded internal profile 33 capable of conforming to the rounded shape of the leading edge 16 of the blade 10.

The structural reinforcement 30 is metallic and preferably based on titanium. This material has indeed a high energy absorption capacity due to shocks. The reinforcement is glued on the blade 10 by means of adhesive known to those skilled in the art, such as an epoxy adhesive.

This type of metal structural reinforcement 30 used for the turbomachine composite blade reinforcement is more particularly described in the patent application EP1908919.

The method according to the invention makes it possible to produce in particular a structural reinforcement as illustrated in FIG. 2, FIG. 2 illustrating the reinforcement 30 in its final state.

FIG. 3 represents a block diagram illustrating the main steps of a method for producing a metal part 200 making it possible, for example, to produce a metal structural reinforcement 30 for the blade leading edge 10 as illustrated in FIGS. 2.

The first step 210 of the production method 200 is a step of cutting a plurality of metal sections 301 from a continuous metal wire for example from a die, each section length 301 is determined according to the final piece to realize. Metal sections 301 thus cut are illustrated in FIG.

Each metal section 301 may therefore have a specific length depending on the portion of the metal reinforcement 30 that it represents, the overlap length of the sidewalls 35, 37 of the reinforcement 30 varying in the second direction 20 between the foot 22 and the top 24. of dawn.

The diameter of the metal sections 301 may vary according to the needs of the user, and the material thickness necessary for the production of the part. The determination of the diameter of the sections is made according to a compromise between flexibility and material thickness required in the tooling.

The substantially straight metal section is typically formed from a wire of circular section but may equally well be formed from a metal section of square, rectangular, hexagonal, etc. section.

The second step 220 of the manufacturing method 200 is a step of cold forming or shaping of the metal sections 301 cut during the first step 210. This second step is illustrated in FIG.

This second step 220 allows the cold forming (ie at room temperature) of each straight metal section 301, by plastic deformation, so as to obtain a preformed metal section 301 ', called a staple, whose geometry is determined as a function of the final piece to be made and in particular according to the shape of the compaction tool used to produce the final piece.

The staples 301 'are made by deformation of the rectilinear metal sections 301 by means of a simple tool that can be operated manually, the individual deformation of each section does not require hydraulic means therefore to achieve the deformation. Advantageously, the deformation tooling is a conventional deformation tool that can be automated and calibrated both in the final shape of the metal clips 301 'and pressure force according to the needs of the user .

Thus, the staples 301 'can be formed individually or as a group of a plurality of metal sections 301.

The deformation step 220 of the sections thus makes it possible to pass from a metal section 301 of rectilinear shape to a preformed metal section 301 ', in the form of a clip, comprising two substantially rectilinear branches 302 and 303 interconnected by each other. a junction element 304 having undergone at least one deformation. The lengths of the branches 302 and 303 may be different for the same staple. The metal section 301 can also be completely or partially crushed (for example for a local thickness restriction).

In the context of the realization of a turbomachine blade metal reinforcement, the staples 301 'are advantageously U-shaped or V-shaped.

The metal sections 301 for producing the staples 301 'are mainly titanium-based yarns and have a thickness substantially varying between 0.1 mm and 5 mm.

The third step 230 of the production method 200, illustrated in FIG. 6, is a step of joining a plurality of staples so as to form a three-dimensional metal structure 350. Advantageously, the metal preform of the part to be produced positioned in the form tool is constituted by a plurality of three-dimensional metal structures 350, each forming a portion of the metal preform.

The third securing step 230 may comprise a preliminary sub-step of positioning the staples 301 'on a shape template (not shown) in order to facilitate the joining operation.

The shape template advantageously has an external geometry adapted to conform to the internal shape of the staples 301 'formed during the previous step.

In the case of producing a turbine engine blade metal reinforcement, the template advantageously has the outer shape of the blade (i.e. the final internal shape of the metal reinforcement).

The template may also have notches on the outer surface of the template capable of defining the positions of the various staples and to perform a pre-holding of the staples in position thereby facilitating the various manipulations of the template or the securing operation of the staples 301 .

The space separating two staples 301 '(ie the positioning pitch of the staples) is defined according to the thickness of the staple 301 'and the material requirements of the part to be produced.

The staples 301 'are secured by welding or gluing metal strips 310, said foils, on the branches 302, 303 of the staples 301' so that the assembly of the foils 310 on the staples 301 'makes it possible to form a metal structure 350 preformed and nonwoven (ie not using a loom).

The foils 310 are cut from at least one sheet or metal strip of small thickness, that is to say of the order of a few hundredths of a millimeter thick.

When the metal structure 350 is made of titanium, the bonding of the titanium metal foils 310 on the titanium clips 301 'can be achieved simply by heating the metal staples 301' and foils 310 superimposed under a low pressure atmosphere.

The welding of the foils 310 on the staples 301 'is performed by known welding means for welding small thicknesses of titanium. Thus, by way of example, the staples 301 'and the foils 310 are joined by soldering points by an electric spot welding method.

According to another embodiment, the welding or gluing of the staples 301 'is carried out by one or a plurality of metal wires having a diameter smaller than the diameter of the metal staples 301' so as to present a certain flexibility and thus facilitate the assembly of the staples. different metal staples 301 '. Thus, by way of example, the metal wires making it possible to produce the metal structure 350 have a diameter that varies substantially between 0.1 mm and 1 mm. These metal son are advantageously titanium; however, it is also possible to use composite silicon carbide-based yarns coated with titanium (SiC-Ti), silicon carbide-based wires and Boron-coated wires (SiC-Bore wire) or silicon carbide wires (SiC-SiC wire).

The metal sections 301 for producing the staples 301 'are mainly titanium-based yarns. However, it is possible to incorporate in the metal structure 350 among the titanium staples metal staples based on silicon carbide and titanium (SiC-Ti), boron coated son (SiC-Bore wire) or Carbide of Silicon (SiC-SiC wire), insofar as the radius of curvature of the metal sections 301 allows the deformation of these "composite" wires without breaking them, so as to create localized and localized structural reinforcements in the workpiece. achieve.

The fourth step 240 of the production method 200 is a step of positioning the various three-dimensional metal structures 350 made during the previous step in a form tool. The various three-dimensional metal structures 350 placed end to end make it possible to form a preform of the part to be produced which is easily positionable in a tool of complex shape.

The shaped tool 400 comprises a cavity 410 (matrix) corresponding to the final external shape of the metal reinforcement 30 and a counterprint 420, 520 (punch) corresponding to the final internal shape of the leading edge metal reinforcement.

According to a first embodiment illustrated in FIG. 7, the positioning step 240 is performed by positioning the three-dimensional metal structures in the cavity 410 of the shape tool 400. The positioning is performed by sequentially positioning the metal structures 350 along the entire length of the impression 410 (ie along the longitudinal axis of the impression). Each metal structure 350 forms a portion of the complete preform, each of the metal structures having a plurality of staples 301 '.

The staples 301 ', and therefore the metal structure three-dimensional 350, having the complementary shape of the cavity 410, the positioning step is simply performed by interlocking the different sections (ie the various three-dimensional metal structures) forming the preform. The division of the preform into a plurality of sections therefore makes it possible to produce a deposit of metallic material conforming to a complex shape of a cavity 410 having two curvatures in two distinct planes.

During this positioning step 240, several layers of metal structures 350, as illustrated in Figure 6, may be superimposed to meet the material thicknesses necessary for the production of the part which can of course vary.

Of course, the shape of the staples 301 'and the length of the branches 302, 303, and therefore the shape of the metal structures 350 of the different layers, can also be adjusted according to the material requirements necessary for the realization of the metal reinforcement 30.

In order to improve the maintenance of the metal structures 350 positioned in the cavity, the staples may advantageously comprise two shoulders made during the cold forming step 220 at each free end of the V-shaped or U-shaped staples. The shoulders are made by folding a portion of the end of each branch so as to make two parts capable of forming supports helping the positioning of the staples and keeps them in the impression.

According to another exemplary embodiment, the ends, capable of forming the shoulders, may also be deformed so that the shoulders have the shape of flats comprising at least one plane surface able to bear against the impression.

For this purpose, the form tooling is arranged to provide at the level of the footprint a recess material allowing the metal structures 350 to take support in the footprint. In a way complementary, the punch of the shaped tool comprises two shoulders on either side of the V-shaped punch able to be positioned in the recesses of material arranged in the impression during the closure of the tool.

According to a second embodiment illustrated in FIG. 8, the positioning step 240 is performed by positioning the three-dimensional metal structures 350, constituting different sections of the preform of the part to be produced, on the punch 520 of the form tooling. 500.

For this purpose, the form tool 500 comprises a cavity 410

(matrix) similar to the first embodiment, and a counterprint 520 (punch) corresponding to the final internal shape of the leading edge metal reinforcement and having in its upper part two shoulders 521 on either side of the V shape corresponding to the final internal shape of the metal reinforcement. The face of the shoulders 521, facing towards the inside of the tooling 500, comprises embedding means 522, distributed over the entire length of the punch 520 (ie along the longitudinal axis of the punch), able to receive the ends of the branches 302, 303 of the staples 301 '. These means 522 are advantageously orifices whose diameter makes it possible to receive each branch 302, 303 of the staples 301 ', or grooves extending over the entire length of the punch, or grooves whose length substantially corresponds to the length of the structures three-dimensional metal 350.

According to this second embodiment, the positioning of the metal structures 350 on the punch 520 is achieved by successive positioning of metal structures 350 and by embedding the branches 302, 303 of the clips 301 'of each structure 350 in the embedding means 522 located on both sides of the V-shape of the punch 520. Three-dimensional metal structures 350 in position is achieved by using the elastic property of the legs 302, 303 of the clips 301 'which exert a pressure against the walls of the embedding means 522 by springback.

Advantageously and to ensure that the staples 301 'constituting the metal structure 350 are held in position, the shaping of the staples during the second step 220 is performed in order to obtain staples 301' whose spacing, in position resting (ie without external stress), between the two branches 302, 303 is greater or smaller than the spacing between the embedding means 522 located on either side of the V-shaped punch 520.

Thus, when the spacing of the legs 302, 303 in the rest position is greater than the spacing of the recessing means 522, the metal structures 350 are held recessed by springback branches 302, 303 exerting a force by springback against the walls of the recessing means 522, in the direction illustrated by the arrows referenced Ef, to find their rest position.

Conversely, when the spacing of the legs 302, 303 in the rest position is less than the spacing of the embedding means 522, the metal structures 350 are held recessed by springback branches 302, 303 which exert a force by elastic return against the walls of the embedding means 522, in the direction opposite to the direction illustrated by the arrows referenced Ef, to find their rest position.

Several layers of staples, as shown in Figure 8, can be superimposed to meet the thickness of material necessary for the realization of the piece. The shape of the metal structures 350 of the different layers can also be adjusted according to the material requirements necessary for the realization of the metal reinforcement 30. According to a third embodiment illustrated in FIG. 9, the positioning step 240 is performed by positioning the three-dimensional metal structures 350, constituting different sections of the preform of the part to be produced, on a frame 610 formed by two rails 61. , 612 according to the neutral fiber of the part to be produced.

The rails 61 1, 612 comprise embedding means 622 for holding the metal structures 350 using the elastic property of the legs 302, 303 of the clips 301 'exerting pressure against the walls of the recessing means 622 by springback.

Thus, similarly to the embodiment described above, when the spacing of the legs 302, 303 of the staples 301 'in the rest position is greater than the spacing of the recessing means 622 of the rails 61 1, 612, the structures metal 350 are held recessed by elastic return branches 302, 303 which exert a force by elastic return, in the direction illustrated by the arrows referenced Ef, to find their rest position.

Conversely, when the spacing of the legs 302, 303 in the rest position is less than the spacing of the recessing means 622 of the rails 61 1, 612, the metal structures 350 are held recessed by elastic return of the branches 302, 303 which exert a force by elastic return, in the direction opposite to the direction illustrated by the arrows referenced Ef, to find their rest position.

In this embodiment, the positioning step 240 comprises an additional sub-step of positioning the frame 610 in which the three-dimensional metal structures 350 are embedded in the punch 620 of the shaped tool 600 illustrated in FIG. punch having for this purpose groove housing 630 adapted to receive the frame. The geometry of the housings 630 is obviously dependent and complementary to the geometry of the rails 61 1, 612 of the frame 610.

The rails 61 1, 612 of the frame 610 are held in the housing 630 of the punch by conventional holding means, such as for example pins, screwing means or by cold adjustment.

The step 240 for positioning the various layers of three-dimensional metal structures 350 may also comprise a sub-step of insertion of an insert between two successive layers of metal structures 350 so as to provide, for example, a larger local material excess thickness, a specific reinforcement made of a specific material or to make a hollow metal piece, such as a hollow metal reinforcement.

By way of example, the insert may be a solid insert made by a forging, machining or casting process, or an insert woven by means of metal threads, for example with titanium threads and / or threads. based on silicon carbide and titanium (SiC-Ti), and / or son coated boron (SiC-Bore), or silicon carbide (SiC-SiC).

Whatever the nature of the material used for producing the insert inserted between the different layers, it is necessary that this material is compatible with the nature of the material used for producing the metal structures 350 and has properties for superplastic forming. and diffusion welding.

For the production of a hollow metal reinforcement (not shown), the insert is a fugitive insert made of a material different from the material used for producing metal staples 301 '.

The term "fugitive insert" means an insert which is not intended to be permanent and which is only necessary for the realization of the leading edge hollow metal reinforcement. The fugitive insert is therefore not present in the metal reinforcement in its final state and does not participate in any way in mechanical characteristics of the metal reinforcement.

The fugitive insert is for example made of a material capable of withstanding a high temperature, of the order of 900 ° C, a high pressure, of the order of 1000 bar, and which is compatible with the materials of metal staples 301 'so as not to create impurities or oxidation.

The material of the fugitive insert must also be chemically etchable by dissolution using a chemical agent.

Advantageously, the fugitive insert is made of copper, or quartz or silica.

The shape of the fugitive insert incorporated in the stack of layers of metal structures 350 is dependent on the shape of the desired final internal cavity.

The fifth step 250 of the production method 200, illustrated in FIG. 10, is a hot isostatic pressing (HIP) step of the stack formed by the various layers of staples positioned in the tooling 400, 500, 600.

Hot isostatic pressing is a widely used manufacturing method known to reduce the porosity of metals and affect the density of many metals, for example in the form of pre-compacted powder. The isostatic pressing process also makes it possible to improve the mechanical properties and the exploitability of the materials.

Isostatic pressing is carried out at high temperature (conventionally between 400 ° C. and 1400 ° C., and of the order of 1000 ° C. for titanium) and at isostatic pressure.

Thus, the application of heat combined with the internal pressure eliminates the voids of the stack, as well as the microporosities by means of a combination of plastic deformation, creep, and diffusion welding to form a massive piece 430.

The massive piece 430 resulting from the isostatic pressing step comprises the internal and external profiles of the metal reinforcement 30. The solid piece 430 is then demolded from the tooling 400, 500, 600.

The isostatic pressing step is carried out under vacuum, advantageously under a secondary vacuum, either in a welded tool in which the secondary vacuum is produced, or in an autoclave bag, the choice of the method depending on the number of parts to be produced. The secondary vacuum makes it possible to avoid the presence of oxygen in the tooling and at the level of the fibrous structure, during the titanium isostatic pressing step.

According to a second exemplary embodiment, hot pressing may also be an isothermal forging process in a press in a vacuum chamber.

Tooling 400, 500, 600 is made of a mechanical alloy called superalloy or high performance alloy.

According to the third embodiment illustrated in FIG. 9, the rails 61 1, 612 of the frame 610 may be made in the same material as the staples 301 'of the metal structures 350 (ie in titanium), or else in a mechanical alloy identical to tooling form. If the rails 61 1, 612 of the frame 610 are made of titanium, the isostatic pressing step 250 will compact the rails 61 1, 612 of the frame 610 and the various metal structures 350 so as to form a solid piece having two massive shoulders. In this embodiment, a recovery operation will be necessary to eliminate, for example by machining, the surplus material formed by the rails.

The isostatic pressing step 250 may previously include a cleaning step, degreasing and / or chemical etching of the metal structures 350 so as to remove the residual impurities of the various layers of staples.

Advantageously, the impurity cleaning step is carried out by dipping the various metallic structures 350 in an agent bath. cleaner or chemical agent.

In the context of manufacturing a hollow metal reinforcement, the method according to the invention may comprise an additional step of chemical etching of the insert, introduced between the various layers of metal structures 350, and forming an integral part of the massive piece 430 compacted. The chemical attack is carried out by means of a chemical agent capable of attacking the material in which the insert is made. The chemical attack of the fugitive insert dissolves the fugitive insert so that the space released by the dissolved insert forms the internal cavity of the hollow metal reinforcement. Advantageously, the etching step is carried out by dipping the solid piece 430 in a bath comprising the chemical agent capable of dissolving the insert. The chemical agent is for example an acid or a base.

Advantageously, the chemical agent is capable of dissolving copper, quartz or silica.

In association with these main production steps, the method according to the invention may also comprise a finishing step and machining of the massive piece obtained at the output of the tool so as to obtain the reinforcement 30. This step of recovery includes:

a step of resuming the profile of the base 39 of the reinforcement 30 so as to refine it and in particular the aerodynamic profile of the leading edge 31; a step of recovery of the flanks 35, 37; this step consisting in particular of trimming the flanks 35, 37 and the thinning of the intrados and extrados flanks;

- A finishing step to obtain the required surface condition.

In association with these main production steps, the method according to the invention may also comprise non-destructive testing steps of the reinforcement 30 making it possible to ensure the geometrical and metallurgical conformity of the assembly obtained. For example, the non Destructive effects can be achieved by an X-ray method.

The present invention has been mainly described with the use of titanium-based metal sections; however, the production method is also applicable with any metal material having properties for superplastic forming and / or diffusion welding, such as aluminum-based wire for producing an aluminum part.

The invention has been particularly described for producing a metal reinforcement of a composite turbomachine blade; however, the invention is also applicable for producing a metal reinforcement of a turbomachine metal blade.

The invention has been particularly described for producing a metal reinforcement of a turbomachine blade leading edge; however, the invention is also applicable to the production of a metal reinforcement of a trailing edge of a turbomachine blade or to the production of a metallic helical reinforcement composite or metal.

Other advantages of the invention include the following:

- reduction of implementation costs;

- reduction of the production time;

- simplification of the manufacturing range;

- reduction of material costs.

Claims

Method for producing (200) a metal part (30), such as a turbomachine blade metal reinforcement, successively comprising:

a step (230) for producing a plurality of three-dimensional metal structures (350) by joining a plurality of metal staples (301 ') formed by rectilinearly bent or curved metal sections in the form of a U-shaped or V, each of said three-dimensional metal structures (350) constituting a portion of a preform of said workpiece (30) to be produced;

a step (240) of positioning said plurality of three-dimensional metal structures (350) in shape tooling (400, 500, 600);

a step (250) of hot isostatic pressing of said plurality of three-dimensional metal structures (350) causing the agglomeration of said three-dimensional metal structures (350) to obtain a solid piece (430).

A method of producing (200) a metal part (30) according to claim 1, characterized in that said method is a method of producing a leading edge metal reinforcement, or a trailing edge, of blade of turbomachine or a helical metal reinforcement so that said massive piece obtained during said step (250) of isostatic pressing is a metal reinforcement. Process for producing (200) a metal part (30) according to one of Claims 1 to 2, characterized in that said step (230) for producing a plurality of three-dimensional metal structures (350) is carried out by welding or by gluing a plurality of metal staples (301 ').

Process for producing (200) a metal part (30) according to one of Claims 1 to 3, characterized in that said step (230) for producing a plurality of three-dimensional metal structures (350) is carried out by welding or bonding a metal foil (310) to said metal staples (301 ') constituting a three-dimensional metal structure (350), said metal foil (310) connecting each metal staple (301') of a three-dimensional metal structure (350).

Process for producing (200) a metal part (30) according to one of Claims 1 to 3, characterized in that said step (230) for producing a plurality of three-dimensional metal structures is carried out by welding or gluing of at least one wire on said metal staples constituting a three-dimensional metal structure, said at least one wire connecting each metal staple of a three-dimensional metal structure.

Process for producing (200) a metal part (30) according to one of Claims 4 to 5, characterized in that each of said staples (301 ') comprises a first branch (302) and a second branch (303), said welding or said bonding said metal foil (310) or said at least one wire being formed on each first branch (302) of each of said staples metal (301 ') and / or each second leg (303) of each of said metal clips (301').

Process for producing (200) a metal part (30) according to one of Claims 5 to 6, characterized in that the said staples (301 ') and / or the said at least one metal wire are formed by metal wires based on of titanium and / or titanium-coated silicon carbide composite yarns (SiC-Ti), and / or boron-coated silicon carbide (SiC-Bore) -based yarns.

Process for producing (200) a metal part (30) according to one of claims 1 to 7, characterized in that said step (240) for positioning said plurality of metal structures (350) is performed by positioning said plurality of metal structures (350) in a die (410) of said form tool (400).

Process for producing (200) a metal part (30) according to one of Claims 1 to 7, characterized in that said step (230) for positioning said plurality of metal structures (350) is performed by positioning said a plurality of metal structures (350) on the punch (520, 620) of said form tool (500, 600).

10. A method of producing (200) a metal part (30) according to claim 9 characterized in that said step (240) for positioning said plurality of metal structures (350) is achieved by the embedding of the branches (302 , 303) of said metal staples (301 ') in fitted recess means (522) in said punch (520), said recess being made by elastic deformation of said arms (302, 303) of the metal staples (301 ').

1 1. A method of producing (200) a metal part (30) according to claim 9 characterized in that said step (240) for positioning said plurality of metal structures (350) is achieved by embedding the branches (302, 303 ) of said metal staples (301 ') in recessing means (622) arranged in two rails (61 1, 612) forming a holding frame (610), said recess being made by elastic deformation of said branches (302, 303) metal staples (301 '), said holding frame (610) being positioned in a housing (630) provided in said punch (620).

12. A method of producing (200) a metal part (30) according to one of claims 1 to 1 1 characterized in that said method comprises a step (220) for producing said metal staples (301 ') by folding of straight metal sections (301), said staples (301 ') being U-shaped and / or V-shaped folded.