Method for manufacturing blade leading edges from a mass

Abstract

This disclosure relates to a process for manufacturing blade leading edges (1), the process comprising the following steps: - extraction (31) of several blanks (9) from a single mass (17), in particular a billet, and - production of at least one leading edge (1) in each blank. Figure for the abstract: Fig. 1

Description

Title of the invention: Method for manufacturing blade leading edges from a mass FIELD OF THE INVENTION

[0001] The invention relates generally to the field of turbomachines, and more particularly to the manufacture of the leading edges of turbomachine fan blades. STATE OF THE ART

[0002] A turbomachine has a main direction extending along a longitudinal axis, and typically comprises, from upstream to downstream in the direction of gas flow, a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, and a low-pressure turbine including in particular an exhaust casing.

[0003] For turbomachines comprising a fan, called "turbofans", a part of the air flow, called primary flow, passes through the fan as well as the core of the engine, while a part of the air flow, called secondary flow, does not pass through the core of the turbomachine, but is ejected directly after passing the fan, providing thrust without a combustion stage.

[0004] The fan blades comprise a leading edge, which is the part of the blade first exposed to the air flow. It is known to make these leading edges of metal, so that they have high mechanical strength, in particular to protect the fan blade during an impact with a bird.

[0005] It is known to form a leading edge from a sheet metal or by forging a bar. To produce all the leading edges of a fan, a number of starting elements equivalent to the number of blades that the fan comprises is provided. Therefore, the transport of all these elements, which have a high weight and volume, and therefore significant means of transport to the manufacturing site are provided. In addition, the individual removal of a leading edge from a mass of metal, such as a billet, requires a number of operations that must be repeated for each blade of the fan. Thus, the time required to manufacture all the leading edges intended for the fan is high. In addition, the waste resulting from the removal of a leading edge from a mass represents a significant quantity of material. It is therefore advantageous to optimize the use of the volume of metal contained in the masses. Statement of the invention

[0006] An object of the invention is to reduce the material and the time required for the fa- fabrication of leading edges of turbomachine blades.

[0007] To this end, a first aspect of the invention relates to a method of manufacturing blade leading edges, the method comprising the following steps:

[0008] - extraction of several raw parts from the same mass, in particular being a billet, and

[0009] - production of at least one leading edge in each raw part.

[0010] Thus, the quantity of material and masses required to manufacture the desired number of leading edges is minimized. Transport of this material is also facilitated.

[0011] According to one implementation, the method comprises the following steps:

[0012] - extraction of at least one block in the mass, then

[0013] - obtaining raw parts from at least one block.

[0014] According to one implementation of the method, the blade is a turbine fan blade. bomachine.

[0015] According to one implementation of the method, the block(s) are cut into slices parallel to each other, the extraction of the raw pieces taking place from the respective slices.

[0016] According to one implementation of the method, the extraction is carried out so that at least two leading edges extend side by side in the mass, front edges of the leading edges being located on the same plane of the mass.

[0017] According to one implementation, the method comprises manufacturing at least a first leading edge and a second leading edge, the first leading edge comprising an internal volume, the first leading edge and the second leading edge extending into the blank such that at least a portion of the second leading edge is located within the internal volume of the first leading edge.

[0018] According to one implementation of the method, one of a first rear corner and a second rear corner of the second leading edge being located in the internal volume of the first leading edge, the other of the first rear corner and the second rear corner of the second leading edge being located outside the internal volume of the first leading edge.

[0019] According to one implementation of the method, the extraction is carried out so that the leading edges extend in at least two rows located one above the other in the mass, in particular so that the leading edges extend in at least three rows located one above the other in the mass.

[0020] According to one implementation, the method further comprises:

[0021] - an adaptation of at least one fall coming from the mass,

[0022] - using as support the or each suitable fall, a treatment, in particular thermal, of at least one of the raw parts or of at least one of the leading edges.

[0023] According to one implementation of the method, the adaptation of the offcuts comprises producing at least one support plate in the offcut configured to support the raw part(s), or the leading edge(s) on the offcut.

[0024] According to one implementation of the method, the adaptation of the falls comprises fixing pins in an upper face of the fall.

[0025] According to one implementation of the method, the pins comprise at least two pairs of pins located at ends of the drop and one pair of pins located in a middle zone of the drop, a space between the two pins of each pair of pins being adapted for receiving and holding the leading edge or the raw part on the drop.

[0026] According to one implementation of the method, the adaptation of the drop comprises shaping the drop, in particular comprising forming notches in a lower part of the drop, allowing the drop to be gripped by a lifting means, in order to allow the drop to be handled by a tool,

[0027] According to one implementation of the method, the adaptation of the falls comprises the production of orifices in an upper face of the fall.

[0028] Another aspect of the invention relates to an assembly comprising:

[0029] - at least two elements each formed by a raw part configured to form at least one blade leading edge and

[0030] - a support for processing elements,

[0031] the support and the elements having faces configured for the assembly of the support with the elements by shape complementarity. DESCRIPTION OF FIGURES

[0032] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0033] [Fig.l] schematically illustrates a fan blade for a turbomachine.

[0034] [Fig.2] illustrates an embodiment of the method according to one aspect of the invention, involving a block.

[0035] [Fig.3], [Fig.4] and [Fig.5] illustrate embodiments of the method according to one aspect of the invention.

[0036] [Fig.6a] and [Fig.6b] illustrate relative arrangements of two leading edges in a mass.

[0037] [Fig.7a], [Fig.7b], [Fig.7c] and [Fig.7d] illustrate the use of scraps in a method of treating an element.

[0038] [Fig.8] illustrates a fixing of pins in a support obtained from a scrap of material.

[0039] [Fig.9] is a functional diagram illustrating the method according to one aspect of the invention.

[0040] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0041] A leading edge 1 of a fan blade for a turbomachine typically comprises, and as shown in [Fig.l], a front edge 10, two sides 13 and 14, one side being configured to form the intrados of the blade and the other side the extrados, as well as two rear corners 11 and 12. The leading edge 1 is arranged on a body 15 of the fan blade.

[0042] The leading edges may be taken from a mass of metal 17, in particular from a bar of elongated shape and rectangular section, called a billet. However, it may be other forms of mass of metal, such as for example and in a non-limiting manner, a mass having a section of circular, hexagonal, elliptical, square or rectangular shape, a bar, a rod or a sheet.

[0043] The method according to the invention comprises the extraction 31 of several raw parts 9 in the same mass 17, then the production of at least one leading edge in each raw part 9. Thus, the leading edge is a finished product obtained by transformation of the raw part 9. By raw part, we mean a part with excess thickness of the leading edge and capable of containing at least one leading edge blank.

[0044] Although these are generally fan blade leading edges, the method can relate to leading edges of other aerodynamic elements, in particular compressor blades.

[0045] Providing a mass 17 of round or elliptical section makes it easier to extract 31 the raw parts. This can also make it possible to minimize the material waste produced during extraction 31.

[0046] The raw parts 9 can be directly extracted from the mass 17. Alternatively, and with reference to [Fig. 2], it will be possible to start by extracting a block 7 from the mass, to then obtain raw parts 9 from the block 7. The raw parts 9 can in particular be obtained by cutting the block 7. Since the block 7 is less voluminous than the mass 17, it is easier to manipulate the block 7 in order to obtain the raw parts 9 than to manipulate the mass 17 itself. According to one embodiment, visible in [Fig. 2], the raw parts 9 are obtained by cutting the block 7 into slices parallel to each other. This has the advantage of maximizing the volume of material from the mass 17 used in the raw parts 9.

[0047] According to another embodiment, illustrated in [Fig. 3], the raw parts 9 are taken side by side from the mass 17. The front edges 10 of the leading edges 1 are then located on the same plane T of the mass 17. As for the embodiment previous, we thus maximize the volume of material of mass 17 used in the raw parts 9.

[0048] According to another embodiment, illustrated in [Fig. 4], the raw parts 9 are taken in rows 21 arranged one above the other in the mass 17. Each row 21 may comprise a single raw part 9, so as to have a purely vertical arrangement of the raw parts 9. Alternatively, certain rows 21 may comprise several raw parts 9 located side by side, as explained previously. Such an arrangement in rows arranged one above the other also aims to maximize the use of the volume of the mass 17, when the height of the latter is greater than twice that of a raw part 9.

[0049] In particular, two rows or three rows of raw parts 9 may be provided.

[0050] It will also be possible to provide rows 21 of raw parts 9 having numbers different blanks arranged side by side. [Fig. 5] shows an example of a configuration with three rows 21 of blanks 9, namely two rows 21 at the edge of the mass, each comprising two blanks 9 located side by side, as well as a third intermediate row 21, located between the two rows at the edge and comprising four blanks 9 located side by side. The extraction 31 of the blanks 9 in the mass 17 can be done in several ways. It is possible to carry out this extraction by sawing or by laser cutting. It is also possible to carry it out by wire cutting. This cutting method allows the machining of high-hardness materials such as metals, by passing a taut wire through the material. This produces a trace slightly thicker than the diameter of the wire. Alternatively, the extraction 31 can be carried out by water jet cutting, which consists of cutting the material using a high-pressure water jet.

[0051] According to one embodiment, the extraction 31 in the same mass 17 is carried out by means of at least two extraction methods among those cited in the preceding paragraph. It is thus possible to maximize the efficiency of the extraction according to the geometry of the mass 17 and the arrangement of the raw parts 9 in the mass 17.

[0052] According to one embodiment, a blank 9 may comprise two nested leading edges 1' and 1”. An internal volume of a first leading edge 1' is defined as being a volume extending between, on the one hand, the front edge 10' of the first leading edge 1' and, on the other hand, a substantially planar surface comprising the first rear corner 11' and the second rear corner 12' of the first leading edge 1' - the internal volume being further closed by the two planes orthogonal to the front edge 10' and comprising each of its two ends. A second leading edge 1” is defined as being nested in the first leading edge 1' if at least a portion of the second leading edge 1” extends into the internal volume of the first leading edge 1'.

[0053] It may in particular be provided that the front edge 10” of the second leading edge 1” extends into the internal volume of the first leading edge 1', and that the first and second leading edges 1', 1” have substantially the same orientation, as illustrated by [Fig.6a].

[0054] Alternatively, and with reference to [Fig.6b], it may be provided that one of the first corner 11” and the second corner 12” of the second leading edge 1” extends into the internal volume of the first leading edge 1', the front edge 10” and the other of the first corner 11” and the second corner 12'' of the second leading edge 1'' then extends outside this internal volume.

[0055] Obviously, other configurations of nested leading edges 1', 1” are conceivable, according to the definition given above.

[0056] The dimensions of the section of the mass are a function of the number of raw parts 9 that are to be removed from it. The method therefore generally uses large masses 17. For example, a reference dimension of the mass 17 is between 150 and 300 mm, this reference dimension being a diameter in the case of a mass 17 of cylindrical section. In the case of a mass 17 of polygonal section, the reference dimension is the dimension of a segment extending between two opposite vertices of the polygon. Generally speaking, the number of raw parts 9 that can be extracted from the mass 17 depends not only on the diameter thereof, but also on the bending and twisting of the leading edge.

[0057] According to one embodiment, once the extraction 31 of the raw parts 9 in the mass 17 has been carried out, the method comprises a treatment 33 of the raw parts 9. Alternatively, the treatment 33 is carried out directly on the leading edges 1 obtained by transformation of the raw parts 9. This may in particular be a heat treatment step.

[0058] With reference to figures 7a to d, scraps 2 of material, originating from the mass 17 and obtained during the extraction 31 of the raw parts 9, can be used so as to serve as a support 22 for one or more elements chosen from raw parts 9 or leading edges 1 during the treatment 33. Indeed, certain scraps 2, in particular those originating from material adjacent to the surfaces of the elements 1, 9 form a counter-form complementary to the shape of the elements 1, 9 and can therefore receive the elements 1, 9 in a stable manner. These scraps 2 are therefore particularly suitable for the formation of a support 22. The adaptation of these scraps 2, which is done by means of only a few operations, makes it possible to provide supports 22 at lower cost for the treatment of the elements 1, 9 and to optimize the use of the material originating from a mass 17.Finally, the falls 2 being formed from the same material as the elements 1, 9, the use of the falls 2 as supports 22 makes it possible to avoid any difference in thermal expansion behavior between the supports 22 and the elements 1, 9 during. of temperature changes. [Fig.7d] illustrates the production of such a support 22, the scraps 2 being obtained following an extraction of raw parts 9 involving wire cutting.

[0059] In order to make the offcuts 2 compatible with use as supports 22, the method may comprise, before the treatment 33 of the leading edges, an adaptation 32 of the offcuts.

[0060] The adaptation 32 of the falls may comprise a realization 3201 of at least one support plate 4 in the fall 2 which is used as support 22. This makes it possible to guarantee the stabilization of the element 1, 9 on the support 22 during the treatment 33.

[0061] The adaptation 32 of the falls can also comprise the fixing 3203 of pins 3 on an upper face 23 of the support 22. These pins 3 can in particular be placed in pairs 8, a pair 8 of pins 3 then being preferentially arranged in the width direction of the fall 2. Advantageously, the space between the two pins of each pair 8 is adapted for the reception and lateral maintenance of the element 1, 9 on the support 22, and possibly for the guidance of the leading edges during their placement on the support 22. This placement can be done by inserting the leading edges in the space located between the pairs 8, in a vertical direction, or by sliding in this space in a horizontal direction.

[0062] According to an embodiment shown in [Fig.8], at least two pairs of pins 331, 332 are provided, located at respective ends 41, 42 of the drop 2, as well as a pair of pins 333 located in a middle zone 43 of the drop 2. This makes it possible to have a limited number of pins, with few fixing steps 3203, while guaranteeing the stability and the maintenance at three points of the element 1, 9 on the support 22.

[0063] The adaptation 32 of the falls can also comprise the production of orifices 3203 in an upper face of the fall 2. These orifices allow the diffusion of heat under the element 1, 9 when a heat treatment 33 is carried out.

[0064] Finally, the step 32 of adapting the scraps may also comprise a step 3204 of shaping the scraps in order to allow them to be handled by a tool. The shaping 3204 may comprise the formation of notches 6 in the scrap 2, configured to allow the placement of a lifting means under the scrap 2, such as for example a forklift or a mobile fork. Two notches 6 may then be provided arranged on either side of the scrap 2 along its width, as shown in [Fig.7c], so as to place the two arms of such a fork or a forklift. A greater number of notches 6 may also be provided for the use of a lifting means comprising more than two arms.

[0065] [Fig.9] illustrates the different stages of the manufacturing process according to the invention.

[0066] The invention also relates to an assembly comprising at least two elements selected from a leading edge 1 of a blade or a blank 9 configured to form such a leading edge 1, as well as a support 22 for processing the elements 1, 9. The support 22 and the elements 1, 9 have faces of complementary shapes, allowing their assembly.

Claims

Claims

1. Method for manufacturing leading edges (1) of blades, the method comprising the following steps: - extraction (31) of several raw parts (9) from the same mass (17), the mass (17) being in particular a billet, and - production of at least one leading edge (1) in each raw part.

2. Method according to claim 1, comprising the following steps: - extraction of at least one block (7) in the mass (17), then - obtaining the raw parts (9) from the at least one block (7).

3. Method according to the preceding claim, in which the block(s) are cut into slices parallel to each other, the extraction of the raw pieces taking place from the respective slices.

4. A method according to any preceding claim, wherein the extraction (31) is carried out so that at least two leading edges (1) extend side by side in the mass (17), front edges (10) of the leading edges (1) being located on the same plane (T) of the mass (17).

5. A method according to any preceding claim, wherein the method comprises manufacturing at least a first leading edge (1') and a second leading edge (1”), the first leading edge (1') comprising an internal volume, the first leading edge (1') and the second leading edge (1”) extending into the blank (9) such that at least a portion of the second leading edge (1”) is located within the internal volume of the first leading edge (1').

6. Method according to the preceding claim, one of a first rear corner (11”) and a second rear corner (12”) of the second leading edge (1”) being located in the internal volume of the first leading edge (1'), the other of the first rear corner (11”) and the second rear corner (12”) of the second leading edge (1”) being located outside the internal volume of the first leading edge (1').

7. A method according to any preceding claim, wherein the extraction is carried out so that the leading edges (1) extend in at least two rows (21) located one above the other in the mass, in particular so that the leading edges (1) extend in at least three rows (21) located one above the other in the mass.

8. Method according to any one of the preceding claims, which further comprises: - an adaptation (32) of at least one offcut (2) coming from the mass (17), - using as support (22) the or each adapted offcut (2), a treatment (33), in particular thermal, of at least one of the raw parts (9) or of at least one of the leading edges (1).

9. Method according to claim 8, the adaptation (32) of the offcuts comprising a production (3201) of at least one support plate (4) in the offcut (2) configured for the support of the raw part(s) (9), or of the leading edge(s) (1) on the offcut (2).

10. Method according to any one of claims 8 and 9, the adaptation (32) of the falls comprising a fixing (3203) of pins (3) in an upper face (23) of the fall (2).

11. Method according to the preceding claim, the pins (3) comprising at least two pairs (331, 332) of pins located at ends of the drop (2) and one pair (333) of pins located in a middle zone of the drop (2), a space between the two pins (3) of each pair (8, 331, 332, 333) of pins being adapted for receiving and holding the leading edge (1) or the raw part (9) on the drop (2).

12. Method according to any one of claims 8 to 11, the adaptation (32) of the drop comprising a shaping (3204) of the drop (2), in particular comprising a formation of notches (6) in a lower part of the drop (2), allowing gripping of the drop (2) by a lifting means, in order to allow handling of the drop by a tool,

13. Method according to any one of claims 8 to 12, the adaptation (32) of the falls comprising a production (3203) of orifices in an upper face (23) of the fall (2).

14. Assembly comprising: - at least two elements each formed by a raw part (9) configured to form at least one leading edge (1) of a blade and - a support (22) for processing the elements, the support and the elements having faces configured for assembling the support with the elements by shape complementarity.

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