The present invention relates to the general field of additive manufacturing processes. The present invention relates more particularly to a blade manufacturing process for a turbomachine by selective melting of the powder bed.

It's pretty normal and beneficial to use additive manufacturing techniques to achieve quick and easy complex three-dimensional pieces. The aeronautical sector is particularly suited to the use of such processes.

When it comes to the manufacture of parts made of metal or metal alloy, the selective melting process of the powder bed allows to obtain complex parts that are very difficult or not realizable with conventional methods such as molding, forging or machining.

Such a process typically includes a step during which depositing a layer of powder on a manufacturing tray and selective step of melting a portion of the powder layer deposited by means of a heater. The preceding steps are repeated successively to form, layer by layer, the final part.

Figure 1 1 shows a turbine nozzle sector for aviation turbomachine comprising a plurality of blades 2 fixed extending between two concentric rings 3 and 4, disposed over a 5-manufacturing horizontal tray. When the dispenser is in such a configuration, the blades 2 are "suspended" or cantilever with respect to the rings 3 and 4.

When it is desired to manufacture such a nozzle sector 1 by selective melting of the powder bed, it is necessary to provide during manufacture of the removable or breakable supports 6 (see Figure 1) which hold the vanes during their manufacture. Indeed, in the selective melting processes on powder bed, it is mandatory that each fused layer can be supported by the already previously fused material. Such carriers 6 are inevitably present

at the leading edge or the trailing edge (depending on whether the nozzle sector is manufactured in one direction or the other) of the blades 2, and a portion of the face 2a of the blades opposite the plate manufacturing 5 (see Figure 5).

However, the presence of removable media at the leading edge and the trailing edge is not desirable. Indeed, once the nozzle sector made in the selective melting equipment on powder bed and separated from its manufacturing tray, removable media must be removed. A manual polishing step is necessary to remove the residues of these supports. During manual polishing step, the operator is caused to move the polishing tool on the edge on which the carriers are present (corresponding to the leading edge or trailing of the blade) and rely above. The manual polishing can thereby cause deformities and irregularities on the edge concerned because of an excessive removal of material. Such faults may be problematic for aerodynamics of the blades during their subsequent use in a turbomachine.

Purpose and Summary of the Invention

The present invention therefore has the main purpose to overcome such drawbacks by providing a selectively melt manufacturing process powder bed of a blade preform for a turbomachine comprising a blade and at least one removable support secured to the blade, the vane being fabricated layer by layer from a first edge of the blade corresponding to a leading edge or a trailing edge of the blade to a second edge of the blade corresponding to an edge trailing or a leading edge of the blade, the method comprising the manufacture of the removable media and of the blade, said removable holder being intended to be fixed on a manufacturing tray on the one hand, and on a portion a face forming intrados or extrados of the blade in the vicinity of the first edge of the blade opposite said second fabrication tray.

According to the invention, the forming face intrados or extrados of the blade facing the build tray comprises a flat extending from said face, the flat surface being present on a portion of said face located outside the first edge of the blade, the

removable support being fixed on the wafer or both the flat surface and on a portion of said face located outside the first edge.

The process according to the invention is characterized by the integration during the manufacture of the preform with a flat blade at the first edge of the blade (the first board may correspond to a leading edge or a trailing edge according to the orientation of the blade in the selective melting equipment on the powder bed). The presence of this flat advantageously makes it away the portion of the blade on which the removable medium is attached the first edge considered. In other words, the removable medium is set back with respect to the first edge of the blade. When the removable medium is subsequently removed to obtain the blade, the supporting residues are located on the flat and possibly a part of the face of the blade facing the manufacturing plate, but not directly on the first edge. Thus, during polishing of dawn to remove these residues, the operator can be based either on the first edge of the blade, but on the flat and the face of the blade in the vicinity of which the flat is present. Such an arrangement thus makes it possible to limit the occurrence of defects due to shrinkage of the brackets ensuring a homogeneous and controlled polishing of the blade. In addition, the adjustment time or polishing of the blade is reduced by such a technique, making this more systematic step. Of course, other techniques as polishing can be used to adjust the shape of the blade after removal of the supports.

Preferably, the flattened portion comprises a first face parallel to manufacturing plate and tangent to the first edge of the blade. For example, the first surface may form an angle less than or equal to 5 ° with the manufacture of board. As the part is produced layer by layer, each layer being parallel to the build tray, this means that the first layer forming the blade will be a surface, for example rectangular. It is advantageous that the first layer is a surface rather than a line, to ensure better maintenance and dawn, especially at its first edge.

Preferably also, the flat further comprises a second face perpendicular to the first face. For example, the second face may be angled between 85 ° and 95 ° with the first face. In this case, a point of the land at the intersection of

first and second faces of said flattened portion can be located at a distance from the face of the blade facing the lower plate manufacture or equal to 0.5 mm, for example less than or equal to 0.3 mm. More generally, the flat part can be integrated with the blade so that it does not exceed the default allowable shape of the vane (dictated by the specifications for example) or, in other words, enter the formal requirements of the blade. Thus, when the flat is constructed in this way, its dimensions are less than the default allowable to form the blade, and its subsequent removal, for example by machining, can become optional.

The removable carrier may be a honeycomb carrier. The invention also provides a method of manufacturing a blade for a turbomachine, comprising the steps of:

- manufacture of a blade preform by a process such as that presented above, and

- removing the removable media and the flat of the blade preform.

Preferably, removal of the removable media and the flat comprises polishing of the blade.

The invention further provides a method of manufacturing a selective fusion turbomachine nozzle sector on the powder bed, the nozzle sector comprising a plurality of vanes carried by two ring sectors, the fixed blades are manufactured by a method of manufacturing a blade as described above.

The invention finally relates to a turbomachine blade preform comprising a blade and at least one removable support secured to the blade, one of the faces of the vane member intrados or extrados comprising a flat extending from said face, the flat is present on a portion of said face located outside of a first edge of the blade corresponding to a leading edge or a trailing edge of the blade, the removable support being fixed on the wafer or both on flat and on a portion of said face located outside the first edge.

Preferably, the flattened portion includes a first face tangent to the first edge of the blade and a second face substantially perpendicular to the first face.

Brief Description of Drawings

Other features and advantages of the present invention will be apparent from the description given below, with reference to the accompanying drawings. In the figures:

- Figure 1 is a perspective view of a nozzle sector can be manufactured by a method according to the invention,

- Figure 2 is a flowchart showing the main steps of a method of manufacturing a blade according to the invention,

- Figure 3 is a schematic sectional view of a selective melting equipment on powder bed wherein manufacturing a nozzle sector,

- Figure 4 is a detail view of Figure 3 at the first edge of a blade and its removable media, and

- Figure 5 is a view similar to that of Figure 3 illustrating a method of the prior art.

Detailed Description of the Invention

Figure 1 shows a distributor sector 1 or turbine stator for aircraft turbine engine, which has already been briefly described. Such a nozzle sector 1 may be manufactured by a method according to the invention by selective melting of the powder bed. A step of the manufacturing method comprises the manufacture of the blades 2 of the nozzle sector 1. Note that the invention applies equally to the blades for land or aeronautical turbomachines.

A method of manufacturing a blade 2 according to the invention will now be described with reference to the flowchart of FIG 2 and the selective fusion of tooling shown in Figures 3 and 4. Such a method comprises first the manufacture of a blade preform (step E), and then removing (step E2) of the removable support 6 of the preform into the blade. The support 6 is thus called "removable" because it is intended to be removed from the blade 2 after its manufacture by a method according to the invention.

Figure 3 shows a 10 selectively melting equipment on the powder bed can be used for manufacturing a nozzle sector 1 provided with a plurality of fixed vanes 2. For reasons of simplification, there is illustrated tooling 10 in section during the manufacture of a nozzle sector 1 comprising only two blades 2.

In known manner, the equipment 10 comprises a powder tank 12 and a manufacturing area 14 wherein the nozzle sector is made 1. The powder reservoir 12 contains the 16 metal powder or a metal alloy which will to manufacture the nozzle sector 1, while the zone 14 is adapted to contain the nozzle sector 1 once manufactured and the unfused powder 18.

Into the powder container 12 is a plate 20 adapted to move vertically to bring the powder to a scraper or roller 22 which can then drive the powder to the manufacturing area 14 to form a powder layer. The bottom of the production zone 14 is a manufacturing plate 5 capable of moving vertically As the manufacture of the nozzle sector 1. The scraper or roller 22 constituting a powder spreading means, allows to deposit a layer of powder on the manufacturing plate 5.

The tool 10 finally comprises a heating member 23 provided with a generating portion 24 of a laser beam or an electron beam and a portion 25 for controlling the path of the generated beam to fuse selectively a powder layer deposited in the production zone 14.

For each blade 2, there is provided the production of a removable support 6 fixed to the manufacture of plate 5 on one hand, and on the blade 2 on the other, which keeps the blade 2 throughout the manufacturing process. It will thus make a blade preform which comprises a blade 2, the removable support 6.

4 shows an enlarged schematic view of a blade preform in the manufacturing area 14 at the removable support 6. The blade preform is here made in the direction indicated by the arrow 26. The manufacture of the preform blade starts with the holder 6 and then manufactures the blade 2 by starting from a first edge 28 (corresponding here to the trailing edge of the blade) and to a second edge (corresponding here to the edge attack of the blade, not shown). Thus, as can be seen in the figures, the first edge 28 is located opposite the manufacture of plate 5, while the second edge is located opposite said build tray 5. Furthermore, the first 28 and the second edges are generally parallel to the upper surface of the build tray.

According to the invention, a flat 30 is provided on the blade 2, more precisely on one side 2a of the blade, and at the first edge 28 of the blade. This flat 30 extends from a vicinity of the first edge 28 and in a direction opposite to the first edge 28, the side of face 2a of the blade opposite the manufacturing platen 5 (this face corresponds here to the upper surface of the 'dawn). In the example illustrated the flat 30 includes a first face 30a substantially parallel to the manufacture of plate 5 and tangent to the first edge 28 of the blade, and a second face 30b substantially perpendicular to the first face 30a. In this configuration, a point 30c located at the intersection of the two faces is at a distance d from the face 2a of the blade. Preferably, this distance d is less than or equal to 0.5 mm, even less than or equal to 0.3 mm, to comply with the allowable defect shape to the blade 2. In general, the distance d may be selected to be less or equal to the value of the fault acceptable form for the blade 2, the deformity being generally defined by a specification.

The removable support 6 here comprises a plurality of walls 6a (or tabs) which are intended to support the blade 2. These walls 6a are fixed to a portion of the blade 2 extending from the flat surface 30 onto the face 2a of the blade and in a direction opposite to the first edge 28. the walls 6a can be fixed to the flat and removal of the first edge 28 of the blade, that is to say the walls 6a are not positioned at the first edge of the blade and are removed therefrom. In an embodiment not illustrated, the walls 6a can be fixed to a portion extending from the middle of the face 30a of the flat 30 and onto the face 2a of the blade.

It will be appreciated that the support 6, the flat surface 30 and the blade 2 to form a single and same piece (called here the blade preform) after the step El.

The removable support 6 is preferably of the honeycomb type. Generally, the removable medium 6 can not be solid, and for example be hollow. This avoids consuming too much material during the manufacturing process, because the support 6 will be finally removed from the blade preform.

Line 32 in broken lines in Figure 4 shows the first layer which constitutes the blade, it is seen that the fused portion of the first layer that starts the manufacture of the vane 2 forms a plane due to the presence of the flat part 30. The obtaining a first vane layer constituted by a plane is advantageous. Indeed, additive manufacturing is avoided as possible to begin a workpiece by fusion of a single line to minimize manufacturing defects. In addition, by starting the manufacture of the blade 2 by a plane, it will be better held by the support 6.

Once the preform blade was manufactured (or plurality of blade preforms from a distributor or a rectifier), the removable medium 6 can be removed by cutting at the walls 6a (step E2). The residue walls 6a of the remaining support 6 and the land 30 are then removed, for example, with a polishing tool of the type grinder. The presence of the flat 30 enables not to press the polishing tool on the first board 28 during this step. Indeed, it may instead position the polishing tool on the flat 30 and at the surface 2a, so as not to damage the first edge 28. In addition, it is more easy to bear with the tool polishing on the face 2a, rather than the first edge 28. the presence of the flat allows to obtain blades whose first edges 28 are regular and have no defects beyond the allowable defect defined by specifications loads.

Note that it is not beyond the scope of the invention when several supports 6 are used to support a blade 2.

For comparison, the positioning of a removable media

6 as it can be achieved in the prior art is illustrated in Figure 5. In this configuration at least one wall 6a of the holder 6 is positioned on the first edge 28 in order to keep the blade properly during manufacture. In addition, the first layer forming the blade 2 (shown by dashed line 32) is constituted by a line, which is undesirable for the reasons mentioned previously. After removal section by the support 6, at least one residue of wall 6a will inevitably positioned on the first board 28. The presence of this residue will make more difficult the steps of adjusting and polishing of the blade, and may cause defects at this edge and an irregularity on the set of vanes 2 manufactured.

CLAIMS

1. A method of manufacture by selective melting of the powder bed of a blade preform for a turbomachine comprising a blade (2) and at least a removable support (6) fixed to the blade, the blade being manufactured layer by layer from a first edge (28) of the blade corresponding to a leading edge or a trailing edge of the blade to a second edge of the blade corresponding to a trailing edge or a leading edge of the blade, the method comprising the manufacture of the removable media and of the blade, said removable holder being intended to be fixed on a manufacturing plate (5) on the one hand, and on a portion of one face (2a) forming intrados or extrados of the blade in the vicinity of the first edge of the blade opposite said second plate manufacturing,

characterized in that the face (2a) forming intrados or extrados of the blade opposite the manufacture of plate comprises a flat (30) extending from said face, the flat surface being present on a portion of said face located outside the first edge (28) of the blade, the removable support (6) being attached to the wafer or both the flat (30) and on a portion of said face (2a) located outside the first edge ( 28).

2. Method according to claim 1, characterized in that the flat (30) comprises a first face (30a) parallel to manufacturing plate and tangent to the first edge (28) of the blade.

3. A method according to claim 2, characterized in that the flat (30) further comprises a second face (30b) perpendicular to the first face (30a).

4. A method according to claim 3, characterized in that a point (30c) of the flat at the intersection of first (30a) and second

(30b) faces of said flat portion is located at a distance (d) of the face of the blade (2a) facing the fabrication table (5) less than or equal to 0.5 mm.

5. A method according to any one of claims 1 to 4, characterized in that the removable support (6) is a honeycomb carrier.

6. A method of manufacturing a blade (2) for a turbomachine, characterized in that it comprises the following steps:

- manufacture of a blade preform (step E) by a method according to any one of claims 1 to 5, and

- removing (step E2) of the removable support (6) and the flat (30) of the blade preform.

7. A method according to claim 6, characterized in that the removal of the removable support (6) and the flat (30) comprises polishing of the blade (2).

8. A method of manufacturing a nozzle sector (1) for a turbomachine by selective melting of the powder bed, the nozzle sector comprising a plurality of blades (2) fixed carried by two ring sectors (3, 4) characterized in that the vanes are manufactured by a method of manufacturing a blade according to any one of claims 6 and 7.

9. A preform of a turbomachine blade comprising a blade (2) and at least a removable support (6) fixed to the blade, characterized in that one of the faces of the blade (2a) forming intrados or extrados comprises a flat (30) extending from said face, the flat surface being present on a portion of said face located outside of a first edge (28) of the blade corresponding to a leading edge or an edge leakage of the blade, the removable support (6) being fixed to the flat (30) or both on the flat surface and on a portion of said face (2a) located outside the first edge (28).

10. A preform according to claim 9, characterized in that the flat (30) comprises a first face (30a) tangential to the first edge

(28) of the blade (2) and a second face (30b) substantially perpendicular to the first face (30a).