BE1024125B1 - AXIAL TURBOMACHINE COMPRESSOR BLADE WITH TREILLIS - Google Patents

Abstract

The invention proposes a method for manufacturing an axial turbomachine compressor blade. The method comprises a step (c) producing a raw blade (32) having a lower surface (38) and an extrados surface. Said surfaces comprise an extra thickness (44) relative to the blade to be produced (26). The extra thickness (44) comprises a stiffening mesh (50) outside the body (46) of the raw blade (32) in which the blade to be produced (26) is cut. The lattice (50) is away from the body (46). The raw blade (32) with its lattice (50) are produced simultaneously by additive manufacturing based on titanium powder. The method further comprises a step (d) machining the raw blade (32) with a bur (56) so as to form the blade to be made (26), this being accompanied by a removal of the lattice (50). ). The invention also provides a raw blade (32).

Description

Description TECHNICAL FIELD The invention relates to the production of a turbomachine blade. More specifically, the invention addresses the machining of an axial turbomachine compressor blade.

Prior art

The aerodynamic requirements lead to thin turbomachine blades. This makes it possible to manage the flows optimally. However, the reduction of the thicknesses limits the mechanical strength as well as the rigidity. For this purpose, a turbomachine blade will generally be made of a metal material from a forged crude. The forged element makes it possible to approach the desired shapes at a lower cost. It usually has rough surfaces with extra thicknesses to be machined to reach the finished envelope of the dawn. Machining also improves the surface condition. These operations are commonly performed by milling with large depths of pass in order to reduce the machining times and thus the manufacturing cost. However, such milling solicit dawn vibration; which affects the quality of the surfaces produced. This phenomenon is all the more marked as the blades are thinned.

EP 1 285 714 A1 discloses a method of manufacturing a blisk rotor disc. The method comprises machining a raw rotor by forming a central hub, an outer rim, and raw blades connecting the central hub to the outer rim. The blades are roughed and refined while being held by the outer rim, which prevents them from being deformed under the cutting forces. When the blades reach a predetermined shape, they are separated from the outer rim. This solution guarantees a certain quality of dawn.

However, this process requires several methods of formatting, including long machining steps. Their own realization as well as their control represent all expenses. Moreover, the quantity of cut material; and therefore evacuated; is important. This impacts the final cost price because of the cost of the raw material required at the start. In addition, the maintenance of elongated blades is reduced in the center because the holding zones are only at the ends of the blades. The quality of the surfaces produced is therefore variable. Summary of the invention

TECHNICAL PROBLEM The invention aims to solve at least one of the problems posed by the prior art. More specifically, the invention aims to improve the quality and possibly the homogeneity of the surfaces of a blade. The invention also aims to reduce the cost of achieving a blade. The invention also aims to provide a simple solution, reliable, fast and simplifying controls.

TECHNICAL SOLUTION The subject of the invention is a method for manufacturing an axial turbomachine blade, in particular a compressor, the method comprising the following steps: (c) supplying or producing a raw blade having a leading edge , a trailing edge, an intrados surface and an extrados surface which extend from the leading edge to the trailing edge, at least one or each of said surfaces comprising an excess thickness with respect to the blade to be produced; then (d) machining the raw blade so as to form the blade to be produced; remarkable in that in step (c) supply or realization, the extra thickness comprises an external stiffening mesh which is removed during step (d) machining; preferably each lattice is removed during or by machining step (d) machining.

According to an advantageous embodiment of the invention, the raw blade and the trellis are made simultaneously in step (c) supply or production by additive manufacturing, in particular based on powder.

According to an advantageous embodiment of the invention, the step (d) machining comprises a milling removing the lattice, while possibly generating surfaces of the blade to be produced.

According to an advantageous embodiment of the invention, the minimum or average thickness of the excess thickness is greater than or equal to 0.50 mm, preferably greater than 1.00 mm, more preferably greater than 2.00 mm, possibly greater than equal to at 3.00 mm.

According to an advantageous embodiment of the invention, the mesh surrounds the raw blade, preferentially the mesh forms the intrados surface and / or the surface extrados. According to an advantageous embodiment of the invention, the lattice extends over the majority, preferably over the entire axial length of the intrados surface and / or the extrados surface.

According to an advantageous embodiment of the invention, the lattice extends over the majority, preferably over the entire radial height of the intrados surface and / or the extrados surface.

According to an advantageous embodiment of the invention, the mesh has a variable density, preferably the raw blade has a head, the density of the mesh decreasing towards the head.

According to an advantageous embodiment of the invention, the extra thickness has a variable thickness, preferably the raw blade comprises a head, the thickness of the extra thickness decreasing towards the head.

According to an advantageous embodiment of the invention, the trellis comprises an intercrossing of stems, possibly generally inclined a quarter turn relative to the height of the raw blade, and / or the stems are linked to their crossings.

According to an advantageous embodiment of the invention, the raw blade comprises a substantially shaped body of the blade to be produced, preferably with a leading edge and / or a substantially salient trailing edge.

According to an advantageous embodiment of the invention, the mesh comprises meshes forming a veil, possibly away from the body of the raw blade; and / or the mesh forms a sieve.

According to an advantageous embodiment of the invention, the raw blade comprises binding bars of the lattice and / or the web to the body, preferably the connecting bars extend generally perpendicular to the body and / or the lattice, and / or generally perpendicular to the veil.

According to an advantageous embodiment of the invention, the extra thickness, in particular the mesh, came from material with the raw blade, in particular with its body.

According to an advantageous embodiment of the invention, the extra thickness also comprises a skin, possibly continuous, which marries the lattice.

According to an advantageous embodiment of the invention, the extra thickness comprises a generally empty space inside the lattice, said space possibly separating the lattice from the body.

According to an advantageous embodiment of the invention, the raw blade comprises a platform, in particular a fixing platform, the stiffening mesh being joined to said platform.

According to an advantageous embodiment of the invention, the raw blade comprises a stack of aerodynamic profiles, the mesh increasing the length and / or the width of the profiles.

According to an advantageous embodiment of the invention, the mesh forms a sheath around the body.

According to an advantageous embodiment of the invention, the blade comprises two opposite platforms according to the height of the blade, in particular radially opposite, the mesh joining the two platforms, and / or the lattice extends from a platform to the other. According to an advantageous embodiment of the invention, the intrados surface is curved with respect to the rope, and / or the extrados surface is curved with respect to the rope. According to an advantageous embodiment of the invention, the lattice covers the majority of the intrados surface and / or the majority of the extrados surface.

According to an advantageous embodiment of the invention, the mesh and the body form a monoblock assembly, preferentially made of material, possibly all around a blade profile.

According to an advantageous embodiment of the invention, the average body thickness is less than or equal to 10.00 mm, preferably less than or equal to 5.00 mm, more preferably less than or equal to 3.00 mm; and / or the body is full. According to an advantageous embodiment of the invention, the mesh envelopes the intrados surface and / or the extrados surface.

According to an advantageous embodiment of the invention, the mesh comprises stems and / or meshes, which preferentially form the intrados surface and / or the extrados surface, and / or the leading edge and / or the trailing edge.

According to an advantageous embodiment of the invention, the intrados surface and / or the extrados surface and / or the lattice are granular.

According to an advantageous embodiment of the invention, the extra thickness is predominantly empty, preferably at least 70% empty, more preferably at least 80% empty.

According to an advantageous embodiment of the invention, the extra thickness comprises at least two layers, preferably at least three layers, including an empty core layer.

According to an advantageous embodiment of the invention, the lattice is a three-dimensional lattice. According to an advantageous embodiment of the invention, the lattice is remote and / or separated from the body; possibly the outer shell of the body; for example, the skin of the overthickness.

According to an advantageous embodiment of the invention, the extra thickness comprises connecting bars joined to the lattice, and extending inwardly and / or joined to the skin and / or the body. The subject of the invention is also a raw blade of a turbomachine, in particular a compressor, the raw blade comprising a lower surface and an extrados surface, remarkable in that at least one of said surfaces comprises an external stiffening mesh, the trellis forming optionally an extra thickness relative to the blade to be produced on the associated surface.

According to an advantageous embodiment of the invention, the raw blade is granular and / or produced by additive manufacturing based on powder, optionally titanium powder.

The notion of overthickness is not essential to the definition of the invention. The subject of the invention is also a raw blade of a turbomachine, in particular a compressor, the raw blade comprising a body with a lower surface and an extrados surface, remarkable in that it comprises a reinforcement mesh of the separated body and / or away from said surfaces.

In general, the advantageous modes of each object of the invention are also applicable to the other objects of the invention. As far as possible, each object of the invention is combinable with other objects.

Benefits brought

The trellis is placed around the dawn in the manner of a scaffolding around a building under construction. It forms a holding structure around the blade during its machining. Its removal does not require any additional step since it is removed as the dawn is sided.

The mesh is sized to provide more rigidity to the base, where the leverage is the most important. Conversely, the density and the thickness of the mesh can be reduced at the top of the blade to limit the amount of material necessary for producing the raw blade. By this, it is possible to achieve a saving since the amount of material is limited to what is necessary to generate a smooth blade that respects the theoretical model.

The realization by additive manufacturing allows to realize in one go the body of the blade and the lattice which will maintain it while it is machined. This powder-based technology makes it possible to produce complex geometries and a particularly fine lattice. Despite the presence of the lattice and the possible granular surface induced by additive manufacturing, milling achieves a smooth surface in one pass.

Brief description of the drawings

FIG. 1 represents an axial turbomachine according to the invention.

FIG. 2 is a diagram of a turbomachine compressor according to the invention.

Figure 3 illustrates a raw blade according to the invention.

FIG. 4 illustrates a raw blade during machining according to the invention.

FIG. 5 is a section of the raw blade according to the invention along the axis 5-5 drawn in FIG.

Figure 6 is a sketch of a diagram of the method of manufacturing a blade according to the invention.

Description of the embodiments

In the following description, the terms inner or inner and outer or outer refer to a positioning relative to the axis of rotation of an axial turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine. The radial direction is perpendicular to the axis of rotation. Upstream and downstream are in reference to the main flow direction of the flow in the turbomachine.

FIG. 1 is a simplified representation of an axial turbomachine. It is in this case a double-flow turbojet engine. The turbojet engine 2 comprises a first compression level, called a low-pressure compressor 4, a second compression level, called a high-pressure compressor 6, a combustion chamber 8 and one or more levels of turbines 10. In operation, the mechanical power the turbine 10 transmitted via the central shaft to the rotor 12 sets in motion the two compressors 4 and 6. The latter comprise several rows of rotor blades associated with rows of stator vanes. The rotation of the rotor about its axis of rotation 14 thus makes it possible to generate an air flow and to compress it progressively until it reaches the combustion chamber 8.

An inlet fan commonly referred to as fan or blower 16 is coupled to the rotor 12 and generates an air flow which splits into a primary flow 18 passing through the various aforementioned levels of the turbomachine, and a secondary flow 20 passing through an annular duct (partially shown) along the machine to then join the primary flow at the turbine outlet. The secondary flow can be accelerated to generate a thrust reaction.

FIG. 2 is a sectional view of a compressor of an axial turbomachine such as that of FIG. 1. The compressor can be a low-pressure compressor 4. There can be seen a part of the fan 16 and the separation nozzle 22 of the primary flow 18 and the secondary flow 20. The rotor 12 comprises several rows of rotor blades 24, in this case three.

The low pressure compressor 4 comprises several rectifiers, in this case four, each containing a row of stator vanes 26. The rectifiers are associated with the fan 16 or a row of rotor vanes to straighten the flow of air, so as to convert the speed of the flow into static pressure. The stator vanes 26 extend essentially radially from an outer casing 28. They may comprise a base, in particular a platform 30, and an aerodynamic blade extending from the base. The blade extends in the annular flow, and eventually passes through. The blade is configured to deflect the associated flow, thanks to its stack of aerodynamic profiles. The platforms may comprise fixing pins 30, possibly with fixing pins. The platforms 30 are pressed against the outer casing 28 of the compressor 4 which has orifices for the introduction and locking of the fixing pins. The fixing pins ensure immobilization.

FIG. 3 illustrates a raw blade 32, for example one of the blades represented in FIG. 2 or in FIG. 1. The present raw blade 32 corresponds to a stator blade, however the invention can be applied to a rotor blade. The invention finds applications in both a compressor and a turbine. The raw blade 32 resumes the general shape of the dawn to be made. It reproduces the shape of the blade, the aerodynamic portion intended to extend radially through the flow. The raw blade 32 has a leading edge 34 and a trailing edge 36. It also shows an intrados surface 38 and an extrados surface linking the leading edge 34 to the trailing edge 36. The raw blade 32 comprises optionally a base, such as a mounting platform 32. This platform can be fixed by means of its attachment pin 40, or be fixed by welding. The base may be a dovetail foot for mounting in a rotor groove, or a stub for welding, for example by friction. The raw blade 32 includes the dawn to be made, at least partially, preferentially totally. The contour 42 of the dawn to be produced is drawn in dashed lines. It is written in the contour of the raw blade 32, or between the leading edge 34 and the trailing edge 36. The raw blade 32 has an extra thickness 44 relative to the blade to be produced. This extra thickness 44 may measure at least 4.00 mm, possibly at least 5.00 mm thick. The raw blade 32 comprises a body 46, possibly a main body. This body 46 can be full. It also includes the dawn to make, or at least its blade.

The extra thickness 44 may be local. It may be at the level of the intrados surface 38 and / or the extrados surface, and / or the leading edge 34 and trailing edge 36. It may be a common excess thickness 44. It can also form the leading edge 34 and the trailing edge 36 of the raw blade 32; these edges (34; 36) become rounded. The extra thickness 44 can also extend radially the blade to achieve.

Optionally, the extra thickness 44 includes a skin 48 which lines the blade to be made so as to form the body 46 of the raw blade 32. The extra thickness 44 further comprises a stiffening structure, in particular with a lattice 50. The lattice 50 is placed outside the body 46 of the raw blade 32, it strengthens and stiffens it. It can cover the majority, preferably all of at least one or each of the intrados surfaces 38 and extrados. The lattice 50 may be generally empty.

The lattice 50 may comprise linked rods. The lattice 50 may form an intercrossing of integral rods 52 forming meshes, for example triangular, or quadrilateral. The lattice 50 may be three-dimensional, its meshes may form cubes or tetrahedra. The mesh width may be greater than or equal to 1.00 mm, preferably greater than or equal to 3.00 mm, more preferably greater than or equal to 5.00 mm. All other forms of mesh are obviously conceivable. The meshes are open, so that the body 46 can remain visible through the mesh 50. The body 46 can be encapsulated in the mesh 50, which then forms a sheath.

The mesh 50 may form a web, or a web. It forms the intrados surface 38 and the extrados surface of the raw blade 32. The lattice 50 forms a partition offset from the surface of the body 46. The lattice 50 is also connected to this body 46 so as to strengthen it . The stiffening mesh 50 is joined to the platform 30. Thus, it provides stiffening to the dawn while benefiting from the intrinsic rigidity of the platform 30. It forms an additional link between the raw blade 32 and the platform 30. trellis 50 may also extend on the upper face of the platform 30 to improve its anchoring. The raw blade 30 has a head 54 which forms its outer end. This head 54 may be a free end of the raw blade 32, for example an end opposite to the platform 30. The extra thickness 44, in particular the mesh 50 may show a thickness and / or a variable density. The density of the lattice 50 can be modulated by shortening and / or thickening the rods 52. This modulates the stiffness that brings the mesh 50 to the raw blade 32. The density and / or the thickness of the lattice can decrease towards the head 54. Conversely, it can increase towards the platform 30. It is also conceivable that it increases towards the leading edge 34 and / or the trailing edge 36.

Figure 4 shows the raw blade 32 of Figure 3 during machining.

The lattice 50 is provisional, sacrificial. During the machining of the surfaces of the blade to be made 26, it is removed. A cutting tool such as a cutter 56 evacuates the mesh 50 progressively. The mesh 50 forms a reinforcing structure around the raw blade 32 during machining. Thanks to its rigidity, it maintains the raw blade 32 and prevents it from vibrating since it maintains the part of the blade where the cutting forces are exerted.

Figure 5 shows a section of the raw blade 32 to be made along the axis 5-5 which is drawn in Figure 3. The platform 30 is visible below. The blade to be produced 26 comprises a radial stack of aerodynamic profiles 58. Their sides form the intrados surface and the extrados surface of the blade to be produced. The cut reveals one of these aerodynamic profiles 58. The profile 58 shows an upstream tip 60 corresponding to the leading edge of the blade to be produced 26, and a downstream tip 62 corresponding to the trailing edge of the blade to be produced. Once again, the outline of the raw blade 32 encompasses the contour of the body 46 in which is inscribed the profile 58 of the blade to be made 26 (in dashed lines). The profile of the raw blade 32 is rounded, in particular at its leading edge 34 and its trailing edge 36. In section, the mesh 50 has rods 52 or portions of rods 52 arranged along and at distance of the contour 58 of the blade to be produced 26. The raw blade 32 may comprise links 64 connecting the lattice to the body. These links 64 may be bars 64, for example transverse. They may be perpendicular to the intrados surface 38 and the extrados surface 66 of the raw blade 32, or to the outer surface of the body 46. These bars 64 may be distributed over the mesh 50 to retain it.

The extra thickness 44 may comprise three layers. It may have the mesh 50, the skin 48, and a void space 68 which separates the skin 48 from the mesh 50. The links 64 may pass through the empty space 68. The latter may surround and / or surround the body 46, forming a closed loop.

FIG. 6 outlines a method for manufacturing a blade according to the invention, this method may make it possible to produce a blade such as those drawn in FIG. 1 and FIG.

The method may comprise the following steps, possibly carried out in the following order: (a) definition 100 of a theoretical model of a blade to be produced; (b) design 102 of a raw blade by adding extra thickness to the previously defined theoretical blade, one of the extra thickness comprising a stiffening mesh; (c) providing or producing 104 of the raw blade; (d) machining 106 of the raw blade by removing the lattice, so as to form the blade to be produced; (e) polishing 108 of the blade to be produced; (f) surface treatment 110 on the blade to be produced. In step (c) supply or realization 104 of the raw blade, the latter may have been produced by additive manufacturing. It can be produced using solidified powder in successive layers using an electron beam. Titanium, or a titanium alloy is advantageously employed. Any other material can be considered. With this method, it is possible to realize both the body of the raw blade, the lattice, the bars; to bind them in one operation. This technology makes it possible to materialize complex shapes, and in particular the gap between the lattice and the body. Additive manufacturing is put forward, but other solutions are possible. The state of the step (c) supply or embodiment 104 is shown in FIG. 4. The step (d) machining 106 may be performed by milling, which allows high rates. This step is shown in Figure 5. The presence of the lattice supports the dawn, and prevents it from vibrating. Consequently, the machining rates can be increased, in particular the chips can be enlarged. The mesh forms a fine and homogeneous structure that does not disturb the machining. Likewise, the bars are thin and do not significantly influence the machining.

In addition, the method may comprise one or more test phases. These can be done at the end, or between process steps. Step (a) definition 100 of a theoretical model is optional in the present invention since it may have been done previously, or by another company. The steps: (b) design 102 of a raw blade, and (c) supply or realization 104 of the raw blade, can be combined in one step. Likewise, the steps (e) polishing 108, and (f) surface treatment 110, are entirely optional. Their results are not essential to obtain a dawn.

Claims (20)

claims 1. A method of manufacturing a blade (26) of an axial turbomachine (2), in particular a compressor (4; 6), the method comprising the following steps: (c) providing or producing (104) a blade a leading edge (34), a trailing edge (36), an intrados surface (38) and an extrados surface (66) extending from the leading edge (34) to the edge of leakage (36), at least one or each of said surfaces (38; 66) comprising an extra thickness (44) relative to the blade to be produced (26); then (d) machining (106) the raw blade (32) so as to form the blade to be made (26); characterized in that in step (c) supply or embodiment (104), the extra thickness (44) comprises a mesh (50) external stiffening which is removed during step (d) machining (106). 2. Method according to claim 1, characterized in that the raw blade (32) and the lattice (50) are made simultaneously in step (c) supply or production (104) by additive manufacturing, including powder-based . 3. Method according to one of claims 1 to 2, characterized in that the step (d) machining (106) comprises a milling removing the mesh (50), while possibly generating surfaces of the blade to be made ( 26). 4. Method according to one of claims 1 to 3, characterized in that the minimum or average thickness of the excess thickness (44) is greater than or equal to 0.50 mm, preferably greater than 1.00 mm, more preferably greater than 2.00 mm, possibly greater than 3.00 mm. 5. Method according to one of claims 1 to 4, characterized in that the mesh (50) surrounds the raw blade (32), preferably the lattice (50) forms the intrados surface (38) and / or the surface extrados (66). 6. Method according to one of claims 1 to 5, characterized in that the lattice (50) extends over the majority, preferably over the entire axial length of the intrados surface (38) and / or the extrados surface ( 66). 7. Method according to one of claims 1 to 6, characterized in that the lattice (50) extends over the majority, preferably over the entire radial height of the intrados surface (38) and / or the extrados surface ( 66). 8. Method according to one of claims 1 to 7, characterized in that the mesh (50) has a variable density, preferably the raw blade (32) comprises a head (54), the density of the mesh (50) decreasing towards the head (54). 9. Method according to one of claims 1 to 8, characterized in that the extra thickness (44) has a variable thickness, preferably the raw blade (32) comprises a head (54), the thickness of the extra thickness (44). ) decreasing towards the head (54). 10. Method according to one of claims 1 to 9, characterized in that the mesh (50) comprises an intercrossing rods (52), optionally generally inclined a quarter of a turn relative to the height of the raw blade (32). 11. Method according to one of claims 1 to 10, characterized in that the raw blade (32) comprises a body (46) substantially in the form of the blade to be produced (26), preferably with a leading edge. and / or a substantially salient trailing edge. 12. Method according to one of claims 1 to 11, characterized in that the mesh (50) comprises mesh forming a web, possibly at a distance from the body (46) of the raw blade (32). 13. Method according to claims 11 and 12, characterized in that the raw blade (32) comprises connecting bars (64) of the mesh (50) to the body (46), preferably the connecting bars (64) s' extend generally perpendicularly to the body (46) and / or the lattice (50). 14. Method according to one of claims 1 to 13, characterized in that the extra thickness (44), including the mesh (50), is integral with the raw blade (32), in particular with its body (46) . 15. Method according to one of claims 1 to 14, characterized in that the extra thickness (44) also comprises a skin (48), possibly continuous, which marries the mesh (50). 16. Method according to one of claims 1 to 15, characterized in that the extra thickness (44) comprises a generally empty space (68) inside the trellis (50), said space possibly separating the trellis (50) from the body (46). 17. Method according to one of claims 1 to 16, characterized in that the raw blade (32) comprises a platform (30), in particular a fixing platform, the reinforcing mesh (50) being joined to said platform ( 30). 18. Method according to one of claims 1 to 17, characterized in that the raw blade (32) comprises a stack of airfoils (58), the mesh (50) increasing the length and / or the width of the profiles ( 58). 19. A raw blade (32) for a turbomachine (2), in particular a compressor (4; 6), the raw blade (32) comprising a lower surface (38) and an extrados surface (66), characterized in that at least one of said surfaces (38; 66) comprises a mesh (50) of external stiffening, the mesh (50) possibly forming an extra thickness (44) with respect to the blade to be made (26) on the associated surface (38; ). 20. Raw blade (32) according to claim 19, characterized in that the raw blade (32) is granular and / or made by additive manufacturing powder-based, optionally titanium powder.