Method for correcting the moment weight of a rotor blade for an aircraft turbomachine

Description

Technical field of the invention

[0001] The invention relates to the technical field of blades for aircraft turbomachines, in particular fan blades. The invention relates to a method for correcting the radial moment weight of a blade for an aircraft turbomachine. Technical background

[0002] The state of the art is illustrated by documents FR-A1-2906320, FR-A1-2962483, GB-A-2484726, FR-A1-2989991, FR-A1-3026033, FR-A1-3102378, US-A1-2014030106, US-A1-2014030107 and EP-A2-3812547.

[0003] As is well known, an aircraft turbomachine extends along a longitudinal axis and comprises, from upstream to downstream in the direction of gas flow, a fan, a low-pressure compressor and a high-pressure compressor, an annular combustion chamber, a high-pressure turbine and a low-pressure turbine, and finally a gas exhaust nozzle.

[0004] The fan consists of a central disc rotating around an axis of rotation. The axis of rotation is, for example, the longitudinal axis of the turbomachine. The central disc is surmounted by a plurality of blades allowing the initial compression of the air entering the turbomachine. The blades are surrounded by a retention casing allowing the blades to be retained in the event of their breakage.

[0005] A fan blade is generally composed of a blade having an aerodynamic profile comprising a leading edge and a trailing edge connected by a pressure face and an extrados face opposite the pressure face. The blade also comprises an upper end and an opposite lower end connected to a root. The root is intended to cooperate with a corresponding cell of the central disc to fix the blade on the central disc.

[0006] Furthermore, in order to reduce the weight of the fan, the blade of the vane is for example made of a composite material, typically an organic matrix composite (OMC). The composite material comprises a polymer matrix for example, a thermoplastic or thermosetting matrix and fibers such as carbon fibers or glass fibers embedded in the matrix.

[0007] In addition, in order to protect the leading edge from erosion wear and / or degradation caused by impacts with foreign bodies, the leading edge is covered with a metal protective shield. The shield is assembled and fixed to the leading edge by gluing. For this purpose, the leading edge or the shield is coated with a layer of glue, then the shield is assembled on the leading edge. The assembly is then subjected to a heat treatment to ensure the polymerization of the glue layer. The shield is thus fixed on the leading edge.

[0008] After manufacturing, each blade is mounted on the central disc according to its own inertia and its relative inertia compared to the neighboring blades. This meticulous assembly is traditionally called "balancing". Balancing the fan is essential to prevent rotation from inducing a force perpendicular to the axis of rotation and prematurely wearing the central disc and the turbomachine, as well as for better efficiency and optimal performance.

[0009] Balancing the fan requires balancing the forces generated by the blades relative to the axis of rotation. The force generated by a blade is called its radial moment weight (RMW). The radial moment weight of a blade is equal to the blade's mass multiplied by the distance between the blade's center of gravity and the axis of rotation. When the radial moment weight of each blade is equal to that of the others, the fan rotor is perfectly balanced. The rotor's lifespan depends in part on its balancing: the more balanced the rotor, the less quickly it wears.

[0010] However, blade manufacturing processes result in a significant dispersion of the radial moment weight of the blades. Thus, in order to perfectly balance the rotor, it is known to add balancing weights in the cone of the fan module when mounting the fan on the turbomachine. Without such balancing, an unbalance appears and the rotor wears prematurely.

[0011] This solution is not entirely satisfactory in that it allows the radial moment weight to be adjusted on the entire set of fan blades, i.e. after the fan has been fitted, and not on the individual blades before they have been fitted. Furthermore, this solution uses added parts, which complicates the assembly of the fan.

[0012] Therefore, there is a need to provide a method for limiting the dispersion of the radial moment weight of the blades in order to facilitate the assembly of the fan while ensuring the balancing of the latter. Summary of the invention

[0013] To this end, the invention proposes a method for correcting the radial moment weight of a blade for an aircraft turbomachine, the method comprising the following steps: (a) providing a blade extending along an elongation axis Z between a free end opposite a root, the blade comprising a composite material blade having a leading edge, a trailing edge connected to the leading edge by an extrados face and an intrados face opposite the extrados face, the blade further comprising a protective shield fixed on the leading edge, (b) measuring the radial moment weight of the blade, (c) comparing the measured radial moment weight with a reference value and adjusting the radial moment weight of the blade according to the result of the comparison.

[0014] The method is characterized in that, in step (a), the blade comprises at least one adjustment cavity extending along the leading edge and opening onto the free end of the blade, and in that, in step, the adjustment is carried out by inserting a first material into the adjustment cavity.

[0015] According to the invention, the radial moment weight of the blade is measured a first time after its manufacture, then compared to a reference value. The radial moment weight is then adjusted to correspond to the reference value. Indeed, the adjustment cavity allows the addition of at least a first material to adjust the radial moment weight of the blade. The radial moment weight of each blade can then be adjusted on a case-by-case basis, thus limiting the dispersion of the radial moment weight of the blades. The risks of creating an unbalance when mounting the blades on the fan are therefore reduced and it is no longer necessary to add balancing weights. Furthermore, the cavity is accessible via the end of the blade, which facilitates the insertion of the first material at the end of the blade manufacture. Such a method also allows precise adjustment of the radial moment weight of the blade.In fact, the radial moment weight of the blade is measured at the end of the blade manufacturing phase, which makes it possible to precisely determine the necessary adjustment to be made.

[0016] The method according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another: in step (c) the adjustment is carried out by inserting a second material into the adjustment cavity, the density of the first material being different from the density of the second material; the first material is lead; the quantity of the first material is between 5g and 50g, and preferably between 10g and 30g; the adjustment cavity is provided in the protective shield; the protective shield comprises a first lateral fin extending over at least a portion of the extrados face, a second lateral fin extending over at least a portion of the intrados face, a central portion connecting the first and second lateral fins and extending along the leading edge along the elongation axis, the adjustment cavity being provided in the central portion; the adjustment cavity extends over the entire height of the leading edge along the elongation axis;the blade comprises a layer of glue arranged between the blade and the protective shield, the adjustment cavity being provided in the layer of glue; step (a) comprises the following sub-step (a1): forming the adjustment cavity in the blade; at the end of sub-step (a1), the adjustment cavity has an upper longitudinal end opposite the root and a lower longitudinal end opposite the upper longitudinal end along the longitudinal axis which are closed, and in that the method comprises, after sub-step (a1), the following sub-step (a2): cutting or removing an end portion of the blade, opposite the root, so as to open the upper longitudinal end of the adjustment cavity. ; Brief description of the figures

[0017] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which: [ Fig. 1 ] there Figure 1 is a schematic representation of a half aircraft turbomachine; [ Fig.2 ] there Figure 2 is a schematic perspective representation of a blade according to the invention; [ Fig. 3 ] there Figure 3 is a partial cross-sectional view of the dawn of the Figure 2 in which the fitting cavity has been omitted for clarity; [ Fig.4 ] there Figure 4 is a schematic representation of a part of a blade according to a first embodiment of the invention; [ Fig.5 ] there Figure 5 is a cross-sectional view of the protective shield according to the first embodiment of the invention; [ Fig.6 ] there Figure 6 is a partial cross-sectional view of the dawn of the Figure 4 ; [ Fig.7 ] there Figure 7 is a schematic representation of a part of a blade according to a second embodiment of the invention; [ Fig.8 ] there figure 8is a cross-sectional view of the dawn of the Figure 7 ; [ Fig.9 ] there Figure 9 is a partial schematic representation of the dawn of the Figure 7 in a step of the process; [ Fig. 10 ] there Figure 10 is a block diagram of a method of manufacturing the blade of the first embodiment; [ Fig. 11 ] there Figure 11 is a block diagram of a manufacturing process for the blade of the second embodiment. Detailed description of the invention

[0018] An aircraft turbomachine 1 is for example represented on the Figure 1 The turbomachine 1 extends along a longitudinal axis X. The turbomachine 1 comprises, from upstream to downstream in the direction of flow of the gases F, a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, at least one annular combustion chamber 5, a high-pressure turbine 6, a low-pressure turbine 7 and a gas exhaust nozzle (not shown).

[0019] The high-pressure turbine 6 comprises a rotor which rotates a rotor of the high-pressure compressor 4 via a high-pressure shaft 8. The low-pressure turbine 7 comprises a rotor which rotates the rotor of the low-pressure compressor 3 and of the blower 2 via a low-pressure shaft 9.

[0020] The rotor of the fan 2 is composed of a central disc 2a surmounted by a plurality of blades 20 regularly distributed over the circumference of the central disc 2a. The disc 2a is movable in rotation about the longitudinal axis X. The blades 20 of the fan 2 are for example surrounded by a retention casing 11 intended to retain the blades 20 in the event of their rupture. The retention casing 11 has an internal surface coated with a layer of an abradable material 12. The layer of abradable material 12 is a layer which is capable of wearing down by friction with the blades 20. The blades 20 according to the invention are therefore for example blades 20 of the fan 2.

[0021] As best seen on the Figure 2 , the blade 20 comprises a blade 21 and a protective shield 26. The blade 21 is for example secured to a foot 22.

[0022] The blade 20 extends along an elongation axis Z. The elongation axis Z extends transversely relative to the longitudinal axis X of the turbomachine 1. The blade 20 has a free end 21a opposite the root 22. The free end 21a faces the abradable layer 12. The root 22 cooperates with a corresponding cell (not shown) of the disk 2a in order to fix the blade 20 on the disk 2a.

[0023] The blade 21 is made of a composite material. The composite material comprises a matrix and fibers embedded in the matrix. The composite material is, for example, an organic matrix composite (OMC). The matrix is, for example, a thermoplastic or thermosetting polymer matrix. The fibers are, for example, carbon fibers or glass fibers. The fibers are, for example, organized in the form of a fiber preform. The blade 21 is, for example, made by resin transfer molding, injection molding, or draping.

[0024] The blade 21 has an aerodynamic profile. The blade 21 comprises a leading edge 23 and a trailing edge 24 connected by an extrados face 25a and an intrados face 25b opposite the extrados face 25a.

[0025] The protective shield 26 is fixed on the blade 21. The protective shield 26 is for example metallic. The metallic material is for example titanium.

[0026] The protective shield 26 has an elongated shape along the elongation axis Z and extends along the blade 21, and in particular along the leading edge 23.

[0027] As best seen on the Figure 3, the protective shield 26 has a dihedral-shaped section and comprises a first lateral fin 26a and a second lateral fin 26b. The first and second lateral fins 26a, 26b are connected by a central portion 26c. The first lateral fin 26a extends over at least a portion of the extrados face 25a and the second lateral fin 26b extends over at least a portion of the intrados face 25b. The central portion 26c covers the leading edge 23. Advantageously, the central portion 26c has, for example, a thickness e1 as measured in a direction transverse to the elongation axis Z greater than the thickness e2, e3 respectively of the first and second lateral fins 26a, 26b. The first and second lateral fins 26a, 26b are tapered towards the trailing edge 24 of the blade 21 and respectively match the intrados 25b and extrados 25a faces.The thicknesses e2, e3 of the first and second lateral fins 26a, 26b decrease towards the longitudinal ends of the protective shield 26 opposite the central portion 26c. Furthermore, as best seen by way of example in the . Figure 5, the protective shield 26 comprises a receiving cavity 29. The leading edge 23 is arranged in the receiving cavity 29. The receiving cavity 29 extends along the leading edge 23 along the elongation axis Z. The receiving cavity 29 is delimited laterally by the first and second lateral fins 26a, 26b. More particularly, the receiving cavity 29 has a general U-shaped or V-shaped shape. The receiving cavity 29 comprises a first wall formed by the first lateral fin 26a, a second wall formed by the second lateral fin 26b and a transverse wall 26d connecting the first and second lateral walls. The protective shield 26 makes it possible to protect the leading edge 23 from external impacts for example and from wear.

[0028] The protective shield 26 is fixed to the blade 21 by gluing for example. The blade 20 thus comprises a layer of glue 27 arranged between the protective shield 26 and the blade 21.

[0029] The adhesive layer 27 has a U-shaped section. The adhesive layer 27 comprises an extrados fin 27a arranged between the extrados face 25a of the blade 21 and the first lateral fin 26a of the protective shield 26 and an intrados fin 27b arranged between the intrados face 25b of the blade 21 and the second lateral fin 26b of the protective shield 26. The adhesive layer 27 further comprises a central base 27c connecting the extrados fin 27a and the intrados fin 27b. The central base 27c is arranged between the leading edge 23 and the central portion 26c of the protective shield 26.

[0030] The central base 27c has a first thickness e1', as measured in a direction transverse to the elongation axis Z, greater than second and third thicknesses e2', e3' respectively of the extrados and intrados fins 27a, 27b. The second and third thicknesses e2', e3' are advantageously identical.

[0031] The first thickness e1' is for example between 1 mm and 10 mm. The second thickness e2' is for example between 0.10 mm and 0.50 mm, preferably between 0.10 mm and 0.35 mm. The third thickness e3' is advantageously identical to the second thickness e2'. The adhesive layer 27 is for example made of a polymeric material preferably chosen from epoxy resins. The polymeric material has a density for example between 1 g / cm3 and 2 g / cm3.

[0032] According to the invention, the blade 20 comprises at least one adjustment cavity 28 extending at least partly along the leading edge 23, along the elongation axis Z.

[0033] According to an advantageous embodiment of the invention, the adjustment cavity 28 extends over at least a portion of the height of the leading edge 23 along the elongation axis Z. Preferably, the adjustment cavity 28 extends over the entire height of the leading edge 23 along the elongation axis Z. The adjustment cavity 28 can thus receive a greater quantity of material to adjust its radial moment weight precisely. Also, the balance of the blade 20 is ensured. The adjustment cavity 28 is closed at its longitudinal ends along the elongation axis Z.

[0034] The blade 20 advantageously comprises at least one first material (not shown) arranged in the adjustment cavity 28. The first material is for example powder. The quantity of the first material is advantageously between 5g and 50g, preferably between 5g and 30g, for example between 10g and 30g and even more preferably between 10g and 20g. The first material has a density for example between 5g / cm 3< and 15g / cm 3<. The first material is for example lead. The first material makes it possible to adjust the radial moment weight of the blade 20.

[0035] In order to more precisely adjust the radial moment weight of the blade 20, and / or to complete the remaining space of the adjustment cavity 28 to avoid movements of the first material therein, the blade 20 optionally comprises a second material (not shown) arranged in the adjustment cavity 28. The second material has a density different from the density of the first material. For example, the density of the second material is lower than the density of the first material. The amount of the sum of the first and second materials is advantageously between 0g and 20g, preferably between 5g and 20g and even more preferably between 10g and 20g. The ratio between the mass of the first material and the second material is between 0 and 1.

[0036] The second material is, for example, polymeric. The polymeric material is chosen from thermoplastics or thermosets, such as an epoxy resin. The second material is, for example, identical to the material of the adhesive layer 27. This simplifies the manufacturing process since the behavior of the materials is identical.

[0037] According to a first embodiment shown in the Figure 4, the adjustment cavity 28 is provided in the protective shield 26. For example, the adjustment cavity 28 is provided in the central portion 26c. This thus makes it possible to adjust the radial moment weight of the blade 20 without impacting the quality of bonding of the protective shield 26 to the blade 21. Indeed, the central portion 26c Also, the central portion 26c has a substantially elongated profile which makes it easy to have an adjustment cavity 28 over the entire length of the protective shield 26 and to reduce its master torque in order to preserve the mechanical properties of the protective shield 26.

[0038] The adjustment cavity 28 has a central axis Y1 parallel to the elongation axis Z. The height H of the adjustment cavity 28 measured along its central axis Y1 is advantageously between 100 mm and 500 mm, for example between 200 mm and 400 mm and preferably 350 mm. Preferably, the adjustment cavity 28 according to this example extends over the entire height of the blade 20. The adjustment cavity 28 is partly delimited by the central portion 26c.

[0039] As illustrated for example on the Figure 6, the adjustment cavity 28 has a trapezoidal cross-section. The trapezoid has a height L of between 1 mm and 10 mm, for example between 1 mm and 5 mm and in particular between 2 mm and 4 mm, an internal base of length I2, of between 1 mm and 10 mm, for example between 1 mm and 5 mm and in particular between 2 mm and 4 mm, and an external base of length l1, of between 1 mm and 10 mm, for example between 1 mm and 5 mm and in particular between 2 mm and 4 mm. The lengths l1 and l2 may be different in order to adapt the shape of the adjustment cavity 28 to the geometry of the protective shield 26, as shown, or of the same dimensions. According to an example not shown, the adjustment cavity 28 has a circular, elliptical, ovoid or polygonal cross-section.

[0040] According to a second embodiment illustrated for example on the Figure 7, the adjustment cavity 28 is provided in the glue layer 27. The adjustment cavity 28 is preferably inserted into the central base 27c.

[0041] According to this embodiment, the adjustment cavity 28 is delimited by an insert 280. The insert 280 is hollow. The adjustment cavity 28 is located in the insert 280. The insert 280 is arranged in the thickness of the adhesive layer 27, preferably in the central base 27c. Indeed, the central base 27c is weakly stressed and contributes only slightly to the bonding force of the protective shield 26 on the blade 21 unlike the extrados and intrados fins 27a, 27b. Thus, the addition of the insert 280 in this part of the adhesive layer 27 only slightly impacts the bonding force of the protective shield 26 on the blade 21. The properties of the blade 20 are preserved. Thus, this embodiment makes it possible to provide a blade 20 whose radial moment weight can be adjusted without impacting its mechanical properties.

[0042] The insert 280 extends at least partly along the leading edge 23 along the elongation axis Z. The insert 280 extends between an upper longitudinal end 28b and an opposite lower longitudinal end 28c along the elongation axis Z. The insert 280 has a cylindrical and elongated shape along an axis of revolution Y. The axis of revolution Y is parallel to the elongation axis Z. The height H of the insert 280 according to this embodiment, measured along the axis of revolution Y, is advantageously between 100 mm and 200 mm, for example between 150 mm and 200 mm. The insert 280 is for example made of polymeric material. The polymeric material is chemically compatible with the material of the adhesive layer 27.

[0043] According to a first example of realization represented on the Figure 7 , the insert 280 has a circular cross-section. The internal diameter of the insert 280 is advantageously between 1 mm and 5 mm.

[0044] According to another example of embodiment shown on the figure 8 , the insert 280 has an elliptical cross-section. According to this embodiment, the insert 280 has a large diameter L measured along the major axis, for example between 2 mm and 4 mm, and a small diameter I measured along the minor axis, for example between 2 mm and 4 mm. The large diameter L is advantageously greater than the small diameter I.

[0045] A method of correcting the radial moment weight of the blade 20 will now be described with reference to figures 10 And 11 .

[0046] The method comprises a first step (a) of providing the blade 20 as described above. The step (a) of providing the blade 20 may comprise the following sub-steps: (a00) providing the blade 21, (a01) providing the protective shield 26, (a02) applying the adhesive layer 27, (a03) bonding the protective shield 26 to the blade 21, and (a1) forming the fitting cavity 28 in the blade 20.

[0047] The sub-steps (a00) of supplying the blade 21 and (a01) of supplying the protective shield 26 can be carried out in parallel.

[0048] As illustrated on the Figure 10, according to the first embodiment in which the adjustment cavity 28 is provided in the protective shield 26, the sub-step (a1) of forming the adjustment cavity 28 is carried out during the sub-step (a01) of providing the protective shield 26. For example, the protective shield 26 is formed by folding metal sheets and welding the transverse ends of the sheets around a support element to form the adjustment cavity 28. The support element is transient, that is to say that it is present during this sub-step but absent at the end of step (a). The support element is therefore not present in the blade 20.

[0049] As illustrated on the Figure 11, according to the second embodiment in which the adjustment cavity 28 is provided in the adhesive layer 27, the sub-step (a1) is advantageously carried out after the sub-step (a03) of bonding the protective shield 26. During the sub-step (a1) the insert 280 is arranged in the adhesive layer 27. In this sub-step, the adjustment cavity 28 is closed at its two longitudinal ends. As illustrated in the Figure 9 , according to this second embodiment, after sub-step (a1), the method comprises a sub-step (a2) of cutting or removing an end portion of the blade 20, opposite the root 22, so as to open the upper end of the adjustment cavity 28 opposite the root 22. The cutting is carried out according to a cutting plane P transverse to the axis of revolution Y or the axis of elongation Z of the blade 20.

[0050] In step (a), the adjustment cavity 28 opens onto the free end 21a of the blade 20. Such a configuration allows access to the adjustment cavity 28 after the manufacture of the blade 20, which facilitates the adjustment of its radial moment weight.

[0051] In a second step (b), a measurement of the radial moment weight is carried out.

[0052] In a third step (c), the radial moment weight measured in step (b) is compared with a reference value. This step makes it possible to determine the adjustment necessary to be made to reach the reference value. Then, the radial moment weight of the blade 20 is adjusted according to the result of the comparison. According to the invention, the adjustment is carried out by inserting the first material into the adjustment cavity 28.

[0053] Advantageously, the adjustment during step (c) is carried out by inserting the second material into the adjustment cavity 28 in combination with the first material. This makes it possible to more precisely adjust the radial moment weight of the blade 20 by using materials of different densities. Also, the insertion of the second material makes it possible to close the adjustment cavity 28. A step of polymerization of the second material can be carried out.

[0054] Thus, according to the invention, it is possible to adjust the radial moment weight of the blades 20 individually during their manufacture. This makes it possible to homogenize this parameter during manufacture and to avoid the creation of an unbalance on the rotor of the fan, for example after the assembly of the blades 20 resulting from a dispersion of the radial moment weight of the blades 20. It is for example possible to adjust the radial moment weight of the blades 20 by at least 5g.cm, for example from 5g.cm to 20g.cm and for example by 15g.cm.

Claims

1. A method for correcting the radial moment weight of a vane (20) for an aircraft turbine engine (1), the method comprising the following steps: (a) providing a vane (20) extending along an axis of elongation Z between a free end (21a) and opposite a root (22), the vane (20) comprising a blade (21) made of composite material and having a leading edge (23), a trailing edge (24) connected to the leading edge (23) by a suction side (25a) and a pressure side (25b) opposite the suction side (25a), the vane (20) further comprising a protective shield (26) attached to the leading edge (23), (b) measuring the radial moment weight of the vane (20), (c) comparing the measured radial moment weight with a reference value and adjusting the radial moment weight of the vane (20) as a function of the result of the comparison, characterized in that, in step (a), the vane (20) comprises at least one adjustment cavity (28) extending along the leading edge (23) and opening onto the free end (21a) of the vane (20), and in that, in step (c), the adjustment is carried out by inserting a first material into the adjustment cavity (28).

2. The method according to the preceding claim, characterised in that in step (c) the adjustment is carried out by inserting a second material into the adjustment cavity (28), the density of the first material being different from the density of the second material.

3. The method according to claim 1 or 2, characterised in that the first material is lead.

4. The method according to any one of the preceding claims, characterised in that the quantity of the first material is between 5g and 50g, and preferably between 10g and 30g.

5. The method according to any one of the preceding claims, characterised in that the adjustment cavity (28) is formed in the protective shield (26).

6. The method according to the preceding claim, characterised in that the protective shield (26) comprises a first lateral fin (26a) extending over at least part of the suction side (25a), a second lateral fin (26b) extending over at least part of the pressure side (25b), a central portion (26c) connecting the first and second lateral fins (26a, 26b) and extending along the leading edge (23) along the axis of elongation (Z), the adjustment cavity (28) being formed in the central portion (26c).

7. The method according to the preceding claim, characterised in that the adjustment cavity (28) extends over the entire height of the leading edge (23) along the axis of elongation Z.

8. The method according to any one of claims 1 to 4, characterised in that the vane (20) comprises an adhesive layer (27) disposed between the blade (21) and the protective shield (26), the adjustment cavity (28) being formed in the adhesive layer (27).

9. The method according to any one of the preceding claims, characterized in that step (a) comprises the following sub-step (a1): forming the adjustment cavity (28) in the vane (20).

10. The method according to the preceding claim, characterised in that, at the end of sub-step (a1), the adjustment cavity (28) has an upper longitudinal end (28b) opposite the root (22) and a lower longitudinal end (28c) opposite the upper longitudinal end (28b) along the longitudinal axis (Z) which are closed, and in that the method comprises, after the sub-step (a1), the following sub-step (a2): cutting or removing an end portion of the vane (20), opposite the root (22), so as to open the upper longitudinal end (28b) of the adjustment cavity (28).