ROTOR BLADE FOR AN AIRCRAFT TURBOMACHINE PROPELLER AND ITS MANUFACTURING METHOD

Abstract

Rotor blade (14) for a propeller (10) of an aircraft turbomachine, this blade (14) comprising a blade (20) connected to a root (40) which is housed in a platform (22), the blade (20) and the root (40) being made of a composite material comprising a fibrous body (50) embedded in a polymer matrix, the root (40) having a generally elongated shape, the platform (22) comprising a housing (38) for receiving said root (40), this housing (38) having a shape complementary to this root (40), the platform (22) being configured to define an axis (Y) for setting the blade (10) which extends along an axis of elongation of the blade (20), characterized in that the housing (38) comprises teeth (60) for hooking the root (40). Figure for the abstract: Figure 2

Description

Title of the invention: ROTOR BLADE FOR AN AIRCRAFT TURBOMACHINE PROPELLER AND METHOD FOR MAKING SAME BRICATION Technical field of the invention

[0001] The present invention relates to the field of aircraft turbomachines and in particular to the propulsion propellers of these turbomachines which comprise variable-pitch blades. Technical background

[0002] The state of the art includes in particular documents FR-A1-3 017 163 and FR-Al-3 080 322.

[0003] An aircraft turbomachine propeller may be shrouded, as is the case with a fan for example, or unshrouded as is the case with an open-rotor type architecture for example.

[0004] A propeller comprises blades which can be variable pitch. The turbomachine then comprises a mechanism for modifying the pitch angle of the blades in order to adapt the thrust generated by the propeller according to the different phases of flight.

[0005] The design of a propeller blade involves several disciplines whose objectives are generally antagonistic. It must allow optimal aerodynamic performance (i.e. provide thrust while maximizing efficiency), guarantee mechanical strength of the blade (i.e. withstand the mechanical constraints resulting from static and dynamic loadings) while limiting the mass as well as the acoustic signature. In particular, the improvement of the aerodynamic performance of the propeller tends towards an increase in the BPR (By Pass Ratio), which results in an increase in its external diameter and therefore in the span of the blades.

[0006] In current technology, it is common to fix a blade to its support by a so-called broached fastener. The blade comprises a foot which has a general dovetail shape and which is intended to be engaged by complementary shapes in a housing of a support platform, this housing being conventionally produced by broaching.

[0007] The support platform is housed in an orifice of a hub of the propeller and defines the pitch axis of the blade. The platform is therefore movable in rotation around the pitch axis inside this orifice of the hub.

[0008] For a blade with a pinned attachment, the aerodynamic force is so intense that it can cause rigid solid movements of the blade root in its housing which are similar to swiveling. Indeed, during a feather start, the reduced speed of the fan does not generate sufficient centrifugal force to prevent these movements induced by the aerodynamic force. This results in frictional damage to the blade and the shim inserted between the root and the bottom of its housing, in just a few cycles. This shim is intended to take up the assembly clearances in the broaching between the blade and its mounting housing, and must also perfectly position the blade perpendicular to the propeller's rotation axis. For the same reasons, this problem may arise in a freewheeling situation (or "windmilling") following an engine failure because variable pitch blades are generally equipped with a feathering system.

[0009] In addition, intense vibration excitation can also occur at much higher rotational speeds on unducted architectures due to the effects of engine installation on the aircraft and the direction of the upstream infinite flow. Indeed, an unducted engine is subject to the influence of the ground and the fuselage, which causes a distortion in the supply of the propeller, in flow speed, according to the engine azimuths. This results in a vibration response of the propeller blades on the first engine orders IN, 2N and 3N (possibly more). On the other hand, in the absence of an air intake sleeve, the direction of the air flowing through the blades is not parallel to the engine axis. This sideslip angle results in so-called "IP" forces which cause a vibration response of the propeller blades on the engine order IN.Similarly, these IP forces can also occur during the aircraft's climb or approach phases because the air flows through the blades at an angle of incidence. These high rotational speed vibration excitations can cause the same friction damage discussed above if the blade attachment is not suitable.

[0010] For all of these reasons, there is a need to improve the existing technology for fixing and securing the blade root to its support platform. Summary of the invention

[0011] The invention relates to a rotor blade for an aircraft turbomachine propeller, this blade comprising a blade connected to a root which is housed in a platform,

[0012] the blade and the root being made of a composite material comprising a fibrous body embedded in a polymer matrix, the blade comprising a lower surface and an upper surface connected together at a leading edge and a trailing edge of the blade, the root having a generally elongated shape,

[0013] the platform being configured to define a blade setting axis which extends along an elongation axis of the blade, the platform comprising a housing for receiving said root, this housing having a shape complementary to this root and comprising a bottom connected to two lateral bearing surfaces, the lateral bearing surfaces being capable of

[0014]

[0015]

[0016]

[0017]

[0018]

[0019] retaining the foot along the axis, characterized in that the lateral bearing surfaces of the housing comprise teeth for hooking the foot. The hooking teeth improve the mechanical holding of the foot by the platform. The contact surfaces between the lateral bearing surfaces of the platform housing and the foot are increased, which ensures reliable support and guarantees optimal transmission of forces during operation. The blade 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: — the foot has a dovetail shape in section; — the housing has a dovetail shape in section; — the foot and the housing cooperate with each other by broached attachment and complementarity of shapes; - the hooking teeth are anchored in the foot; - at least some of the teeth on each of the litters have different shapes different from the other teeth in this litter; - the teeth are separated from each other by inter-tooth cavities, at least some of the inter-tooth cavities on each of the spans having different shapes from the other inter-tooth cavities on that span; - the inter-tooth cavities have in section a shape chosen from a concave curved shape, a dovetail shape, a shape of which at least one lateral face is inclined towards a leading edge or a trailing edge of the blade, and a random shape produced by machining; - the root is housed without any play in said housing and is secured to the platform thanks to said polymer matrix; This is made possible by the fact that the platform of the blade is used to mold the root. It is therefore understood that the root of the blade will take up all the space available in the housing of the platform. There is therefore no play between the root and the walls of the housing because the polymer matrix at the root will occupy all the space in the housing. Furthermore, the polymer matrix will harden upon contact with the walls of the housing and thus allows the blade to be further secured to the platform and therefore to participate in the retention of the blade by the platform; - the inter-tooth cavities are completely filled with the polymer matrix; - the teeth have a minimum height or minimum protruding dimension of between 0.05 and 2 mm; - the foot is mounted in a non-removable manner in the housing of the platform ; - the teeth are distributed over the entire length or longitudinal dimension of the housing; - the teeth extend over a dimension along the axis which represents at least 20% of a maximum dimension of the housing along this axis, and preferably at least 40% of this maximum dimension;

[0020] — the platform comprises a first aerodynamic surface located on the side of said intrados, and a second aerodynamic surface located on the side of said extrados, said first and second aerodynamic surfaces being capable of being swept by an air flow when the propeller is operating;

[0021] — said housing has an elongated shape and opens at its two long ends tudinal, the longitudinal ends of the foot being aligned with the longitudinal ends of the housing;

[0022] — said foot occupies the entire volume of this housing, • the longitudinal ends of the housing open onto a cylindrical surface of the platform which extends around said wedging axis, the longitudinal ends of the foot comprising portions of cylindrical surface which extend in the extension of the cylindrical surface of the platform and which complete this cylindrical surface at the level of the outlets of the housing;

[0023] — the dawn further comprises two locks fixed on the platform, on either side of the foot, and configured to cover the longitudinal ends of the foot respectively; the locks thus make it possible to block the foot in its housing;

[0024] — a first of the locks comprises a first aerodynamic surface located on the side of said leading edge, and a second of said locks comprises a second aerodynamic surface located on the side of said trailing edge, said first and second aerodynamic surfaces of the first and second locks being capable of being swept by an air flow when the propeller is operating; the locks thus make it possible to reconstitute part of the aerodynamic vein of the propeller,

[0025] — the platform comprises a cylindrical body which extends under the foot along said timing axis;

[0026] — the platform comprises a disc centered on the wedging axis and comprising the foot reception housing.

[0027] The present invention also relates to a propeller for an aircraft turbomachine, comprising an annular hub which extends around an axis of rotation and which comprises a series of orifices which are regularly distributed around the axis of rotation and which are oriented radially relative to the axis of rotation, and blades as described above, the platforms of which are mounted respectively in these holes such that the blades extend radially outwardly from the hub, each of the platforms being rotatable about its pitch axis within the hole in the hub.

[0028] The present invention also relates to a turbomachine, in particular for an aircraft, comprising a propeller as described above.

[0029] The invention further provides a method of manufacturing a blade as described above, comprising the following steps:

[0030] a) preparation of the fibrous body of the blade,

[0031] b) insertion of the foot into the platform housing,

[0032] c) injection of a resin into the housing of the platform so as to give it the function of an injection mold, or molding of the foot previously impregnated with resin in the housing of the platform, the resin being intended to form said polymer matrix, to eliminate any play between the foot and the housing, and to secure the foot to the platform.

[0033] It is therefore understood that the resin is injected into the platform forming the injection-molding mold, which is advantageous because it is not necessary to provide a foot demolding operation in this case.

[0034] 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:

[0035] — the resin injected or which impregnates the foot or the fibrous body is liquid or pasty;

[0036] — between steps b) and c) or in step c), molding shells are added to the platform;

[0037] — the shells compress the foot and / or the resin in the platform housing, the foot preferably having a volume greater than that of the housing; the molding shells are thus shells for compressing the foot and / or the resin in the housing of the platform; compressing the foot is advantageous for guaranteeing molding without play of the foot and stressing the foot in the housing of the platform after polymerization;

[0038] — the foot has a length or longitudinal extent greater than that of the housing and includes longitudinal portions projecting at the end of step b);

[0039] — after step c), the process comprises a step d) of cooking with a view to polymerizing resinization; the difference in thermal expansion intrinsic to each material allows, during cooling, the platform to exert a constant and homogeneous pressure force on the blade root; the clearances are not only consumed, but a retention force between the parts is naturally applied;

[0040] — after step c) or d), the method comprises a cooling step e) controlled and homogeneous resin to control thermal expansion forces between the platform and the foot;

[0041] — for example after step c), d) or e), the method comprises a step f) of sup pressure, for example by machining, of said longitudinal portions;

[0042] — the method further comprises a following step g) of fixing two locks on the platform, on either side of the foot, these locks respectively covering the longitudinal ends of the foot. Brief description of the figures

[0043] 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:

[0044] [Fig-1] [Fig.l] is a schematic perspective view of a propeller for a tur- aircraft engine,

[0045] [Fig.2] [Fig.2] is a schematic perspective view of a rotor blade for a propeller such as that of [Fig.l],

[0046] [Fig.3] [Fig.3] is another schematic perspective view of the rotor blade of [Fig.2],

[0047] [Fig.4] [Fig.4] is a schematic perspective view of a blade of the dawn of the [Fig.l], and illustrates a step in a blade manufacturing process,

[0048] [Fig.5] [Fig.5] is another schematic perspective view of another stage of the method, in particular of mounting the blade of [Fig.4] in a platform,

[0049] [Fig.6] [Fig.6] is a schematic perspective view of the blade and the platform assembled after the step in [Fig.5],

[0050] [Fig.7] [Fig.7] is a schematic sectional view of the blade and the platform as assemblies of [Fig.6],

[0051] [Fig.8] [Fig.8] is a schematic perspective view of the blade and the assembled platform of [Fig.6] with in addition a schematic representation of molding and compression shells, and illustrates another step of the manufacturing process,

[0052] [Fig.9] [Fig.9] is a view similar to that of [Fig.6] and illustrates a step of elimination of the manufacturing process,

[0053] [Fig. 10] [Fig. 10] is a view similar to that of [Fig.6] and illustrates the end of the removal step of the manufacturing process,

[0054] [Fig. 11] [Fig. 11] is a partial schematic perspective view of the rotor blade platform and latches, and illustrates another step in the manufacturing process,

[0055] [Fig. 12] [Fig. 12] is a partial schematic perspective view of a propeller and the blade platform housed in an orifice of a hub of this propeller,

[0056] [Fig. 13] [Fig. 13] is a schematic perspective view of a platform for a blade according to the invention;

[0057] [Fig. 14] [Fig. 14] is another schematic perspective view of a platform for a blade according to the invention;

[0058] [Fig. 15] [Fig. 15] is a very schematic cross-sectional view of the housing of a platform; and

[0059] [Fig.l6a-16b] Figures 16a and 16b are very schematic sectional views of a lateral scope of a platform housing, according to two variant embodiments. Detailed description of the invention

[0060] [Fig.l] shows a propeller 10 for an aircraft turbomachine, this propeller 10 being able to be shrouded or unshrouded, that is to say surrounded or not by an annular casing of the turbomachine.

[0061] The propeller 10 is rotatable about an axis X and comprises a hub 12 and blades 14 carried by the hub 12. The hub 12 has an annular shape about the axis X and comprises a series of orifices 16 regularly distributed about the axis X. These orifices 16 have substantially radial orientations relative to the axis X and generally open in a radial direction inside the hub 12, and outside the hub 12. The orifices 16 open for example onto an external annular surface 12a of the hub 12, which may be cylindrical or frustoconical.

[0062] Each of the blades 14 comprises a blade 20 and a platform 22 secured to a root of the blade 20. Conventionally, the blade 20 comprises a lower surface face 21, an upper surface face 24, a leading edge 26, and a trailing edge 28. The blade 20 comprises a free end opposite its root, called the apex 29. The root and the platform 22 are located at the end opposite the apex 29.

[0063] The orifices 16 are intended to receive the platforms 22 of the blades 14 which make it possible to guide the blades 14 in rotation around radial axes Y and to wedge them angularly around these radial axes Y, called wedge axes.

[0064] Figures 2 and 3 show a rotor blade 14, which can equip a propeller 10 such as that illustrated in [Fig.l].

[0065] The platform 22 has a particular shape in the example shown. It essentially comprises two parts, namely a cylindrical body 30 and a disc 32. The cylindrical body 30 forms a pivot for setting the blade 14. The disc 32 can have a function of holding the blade and ensuring an aerodynamic junction between the vein and the body / pivot.

[0066] The body 30 is centered on the setting axis Y and has a generally elongated shape along this axis Y. The upper or radially external end of the body 30, relative to the axis X, is connected to the disc 32 and located on the side of the blade 20. The lower end or radially internal to the body 30, relative to the axis X, is intended to be connected to a mechanism for actuating the setting of the blade 14 which is generally located inside the hub 12 of the propeller 10 and which is not shown in the drawings.

[0067] The platform 22, and in particular the disc 32, comprises an aerodynamic surface 34 intended to be aligned with the surface 12a of the hub 12 and therefore to be swept by a flow of gas in operation.

[0068] In the example shown, the disc 32 comprises a first aerodynamic surface 34a located on the side of the intrados face 21, and a second aerodynamic surface 34b located on the side of the extrados face 24.

[0069] The platform 22, and in particular the body 30, comprises a cylindrical surface 36 which extends around the Y axis.

[0070] The platform 22 comprises a housing 38 for receiving the root 40 of the blade 20. In the example shown, the housing 38 is of the broached type and the root 40 of the blade 20 has a generally elongated shape with a preferably dovetail section.

[0071] Alternatively, other types of pinned attachment are conceivable. Instead of a dovetail section, the foot 40 and the housing 38 could have another sectional shape and for example a fir tree, C, Z shape, etc.

[0072] The housing 38 has an elongated shape along an elongation axis Z substantially perpendicular to the setting axis Y and opens at its two longitudinal ends at the surface 36 in the example shown. There are therefore two outlets of the housing 38, on the surface 36, diametrically opposite relative to the axis Y.

[0073] The foot 40 of the blade 20 also has an elongated shape along the aforementioned elongation axis Z, and has a shape complementary to that of the housing 38

[0074] It can be seen in Figures 2 and 3 that the longitudinal ends of the foot 40 have convex curved shapes which extend at the level of the aforementioned outlets and which reproduce the missing portions of the surface 36 by extending in the extension thereof.

[0075] The blade 20 and the foot 40 are made of a composite material comprising a fibrous body embedded in a polymer matrix. The fibrous body is made by three-dimensional weaving of fibers, for example carbon, or by draping of folds or fabrics (woven or non-woven) which are superimposed on each other.

[0076] The polymer matrix is ​​generally obtained by polymerization of a resin, which can be thermosetting and which is for example an epoxy resin.

[0077] Advantageously, the foot 40 of the blade 20 is housed without any play in the housing 38 of the platform 22 and is secured to the platform 22 by means of the polymer matrix.

[0078] For this, a method of manufacturing the blade 12 is proposed which will be described below with reference to Figures 4 and following. Figures 4 and following illustrate several stages of this process.

[0079] [Fig. 4] illustrates a first step a) of the method in which the fibrous body 50 of the blade 20 and the root 40 of the vane 14 is prepared. As mentioned above, the fibrous body can be prepared by three-dimensional weaving of fibers or draping of folds. A three-dimensional shape is thus obtained comprising a (part of) blade and a / a (part of) root, the blade and the root being integral. The root 40 of the fibrous body 50 has a generally elongated and preferably dovetailed shape with a length along its elongation axis Z which is denoted LL

[0080] [Fig. 5] illustrates another step b) of the method in which the foot 40 is inserted into the housing 38 of the platform 22. As mentioned above, the housing 38 is obtained by broaching and the foot 40 is intended to be inserted into the housing 38 by translation along the elongation axis Z. The foot 40 is thus intended to slide or slide into the housing 38. It can be seen in [Fig. 6], after mounting the foot 40 in the housing 38 of the platform 22, that the length L1 of the foot 40 is greater than the length L2 of the housing 38. [Fig. 7] shows that the foot 40 has a complementary shape with the housing 38 of the platform 22, mounting clearances being able to exist between them after step b).

[0081] [Fig.8] illustrates another step c) of the method in which a resin is injected into the housing 38 of the platform 22 so as to give it an injection mold function. Alternatively, the fibrous body or only the foot could be impregnated or pre-impregnated with a resin. Step c) would then consist of molding the foot previously impregnated with resin in the housing of the platform.

[0082] The resin is intended to form the aforementioned polymer matrix, to eliminate any play between the foot 40 and the housing 38, and to secure the foot 40 to the platform 22.

[0083] In practice, the platform 22 may constitute a part of the injection mold and additional elements, such as molding shells 52, may be added to the platform 22 in order to constitute the molding cavity all around the platform 22.

[0084] [Fig. 8] very schematically represents two molding shells 52 which are arranged on two diametrically opposite sides of the platform 22, with respect to the Y axis. In particular, these two shells 52 can make it possible to cover the portions of the foot 40 which protrude from the housing 38.

[0085] The molding shells 52 may have the function of compressing these portions of the foot 40 radially inwards, with respect to the setting axis Y (see arrows F). The molding shells 52 are then shells for compressing the foot and / or the resin. This solution has the advantage of filling the assembly clearances to create a fitting connection.

[0086] To facilitate or allow compression of the foot in the platform housing, the foot may initially have a volume greater than that of the platform housing.

[0087] During compression (and preferably also during polymerization of the resin), the blade 20 and the platform 22 are perfectly positioned to guarantee the repeatability of each blade 14 of the propeller 10.

[0088] [Fig. 8] thus also represents an optional step of the process in which, between steps b) and c) or after step c), molding shells 52 are attached to the platform 22.

[0089] After step c), the method may include a step d) of curing for the polymerization of the resin. The difference in thermal expansion intrinsic to each material allows, during cooling, the platform to exert a constant and homogeneous pressure force on the blade root. The clearances are not only consumed, but a retention force between the parts is naturally applied.

[0090] After step c) or d), the method comprises a cooling step e). During cooling of the blade, the material (generally metallic) of the platform 22 generally has a coefficient of expansion greater than the composite material of the blade, which allows the cold clearance to become negative between the parts. The cooling of the resin is preferably controlled and homogeneous to control the thermal expansion forces between the platform and the root.

[0091] The method may further comprise an optional step f) illustrated in [Fig.9], in which the projecting longitudinal portions of the foot 40 are removed, for example by machining.

[0092] At the end of step f) or directly after step c), a blade is obtained as illustrated in [Fig. 10] in which the longitudinal ends of the root 40 comprise portions of cylindrical surface which extend in the extension of the cylindrical surface 36 of the platform 22 and complete this cylindrical surface 36 at the level of the outlets of the housing 36.

[0093] The method may further comprise a following step g) of fixing two locks 54 on the platform 22, on either side of the foot 40 ([Fig. 11]). The locks 54 may be fixed by elements of the screw-nut type or the like.

[0094] These locks 54 are intended to cover respectively the longitudinal ends of the foot 40.

[0095] A first of the locks 54 comprises a first aerodynamic surface 54a located on the side of the leading edge 26, and a second of the locks 54 comprises a second aerodynamic surface 54b located on the side of the trailing edge 28.

[0096] These aerodynamic surfaces 54a, 54b are aligned on the one hand with the surface 34 of the platform 22, and are further intended to be aligned with the surface 12a of the hub (cf. [Fig. 12]).

[0097] Figures 13 and 14 represent an embodiment of a platform 22 for a rotor blade 14 according to the invention.

[0098] The blade 14 includes all the features of those illustrated in Figures 2 to 12 to the extent that these features do not contradict the following.

[0099] As can be seen in [Fig. 15] which shows a simplified cross-sectional view of the housing 38 of a platform 22, this housing 38 is preferably dovetail-shaped and comprises a bottom 38a extending between two lateral bearing surfaces 38b and connected to these lateral bearing surfaces. As mentioned above, the root 40 of the blade preferably occupies the entire volume of this housing 38.

[0100] As illustrated in Figures 13 and 14, the bearing surfaces 38b of the housing 38 comprise teeth 60 for hooking the foot 40.

[0101] The hooking teeth 60 are preferably anchored in the root 40. This means that the teeth 60 penetrate and are engaged in the material of the root 40. This mechanical anchoring reinforces the mechanical strength of the connection between the blade and the platform 22.

[0102] The teeth 60 are preferably distributed over the entire length L2 or longitudinal dimension of the housing 38, as in the example shown. The teeth 60 preferably extend over a dimension L3 along the Y axis which represents at least 20% of a maximum dimension Lmax of the housing 38 along this Y axis, and preferably at least 40% of this maximum dimension Lmax ([Fig. 15]).

[0103] The teeth 60 may extend to the opening of the housing 38 on the surface 34, as illustrated in the drawings.

[0104] Figures 16a and 16b illustrate alternative embodiments of the lateral bearing surfaces 38b and the teeth 60.

[0105] At least some of the teeth 60 on each of the bearing surfaces 38b may have different shapes from the other teeth 60 of this bearing surface 38b.

[0106] The teeth 60 are separated from each other by inter-tooth cavities 62. At least some of these inter-tooth cavities 62 on each of the bearing surfaces 38b may have different shapes from the other inter-tooth cavities 62 of this bearing surface 38b.

[0107] The inter-tooth cavities 62 have, for example, in section a shape chosen from a concave curved shape (shapes a, b and c in FIG. 16a), a shape preferably in a dovetail (shapes d in FIG. 16b), a shape of which at least one lateral face is inclined towards a leading edge or a trailing edge of the blade (shape e in FIG. 16b), and a random shape produced by machining (shapes f and F in FIG. 16b).

[0108] The teeth 60 preferably have a minimum height H or minimum protruding dimension of between 0.05 and 2 mm. This height can be measured from the bottom of the inter-tooth cavities 62.

[0109] In the case where the blade 14 is obtained by the method described above, the foot 40 is housed without any play in the housing 38 and is secured to the platform 22. thanks to said polymer matrix.

[0110] The inter-tooth cavities 62 are then preferably filled entirely with the polymer matrix.

[0111] The foot 40 is also preferably mounted in a non-removable manner in the housing 38 of the platform 22.

Claims

Claims

1. Rotor blade (14) for a propeller (10) of an aircraft turbomachine, this blade (14) comprising a blade (20) connected to a root (40) which is housed in a platform (22), the blade (20) and the root (40) being made of a composite material comprising a fibrous body (50) embedded in a polymer matrix, the blade (20) comprising a lower surface (21) and an upper surface (24) connected together at a leading edge (26) and a trailing edge (28) of the blade (20), the root (40) having a generally elongated shape, the platform (22) being configured to define a setting axis (Y) of the blade (14) which extends along an elongation axis of the blade (20), the platform (22) comprising a housing (38) for receiving said root (40), this housing (38) having a shape complementary to this foot (40) and comprising a bottom (38a) connected to two lateral supports (38b), the lateral supports (38b) being capable of retaining the foot (40) along the axis (Y),characterized in that the lateral bearing surfaces (38b) of the housing (38) comprise teeth (60) for hooking the foot (40).,

2. A blade (14) according to claim 1, wherein the hooking teeth (60) are anchored in the root (40).

3. A blade (14) according to any preceding claim, wherein at least some of the teeth (60) on each of the bearing surfaces (38b) have different shapes from the other teeth (60) of that bearing surface (38b).

4. A blade (14) according to any preceding claim, wherein the teeth (60) are separated from each other by inter-tooth cavities (62), at least some of the inter-tooth cavities (62) on each of the bearing surfaces (38b) having different shapes from the other inter-tooth cavities (62) of that bearing surface (38b).

5. Blade (14) according to the preceding claim, in which the inter-tooth cavities (62) have in section a shape chosen from a concave curved shape, a dovetail shape, a shape of which at least one lateral face is inclined towards a leading edge or a trailing edge of the blade, and a random shape produced by machining.

6. Blade (14) according to one of the preceding claims, in which the foot (40) is housed without any play in said housing (38) and is secured to the platform (22) by means of said polymer matrix.

7. Blade (14) according to the preceding claim, dependent on the resale- indication 4 or 5, in which the inter-tooth cavities (62) are filled entirely by the polymer matrix.

8. Blade (14) according to one of the preceding claims, in which the teeth (60) have a minimum height (H) or minimum projecting dimension of between 0.05 and 2 mm.

9. Blade (14) according to one of the preceding claims, in which the foot (40) is mounted in a non-removable manner in the housing (38) of the platform (22).

10. Blade (14) according to one of the preceding claims, in which the teeth (60) are distributed over an entire length (L2) or longitudinal dimension of the housing (38).

11. Blade (14) according to one of the preceding claims, in which the teeth (60) extend over a dimension (L3) along the axis (Y) which represents at least 20% of a maximum dimension (Lmax) of the housing (38) along this axis (Y), and preferably at least 40% of this maximum dimension (Lmax).

12. Blade (14) according to one of the preceding claims, in which said housing (38) has an elongated shape and opens at its two longitudinal ends, the longitudinal ends of the foot (40) being aligned with the longitudinal ends of the housing (38).

13. Blade (14) according to the preceding claim, in which the longitudinal ends of the housing (38) open onto a cylindrical surface (36) of the platform (22) which extends around said setting axis (Y), the longitudinal ends of the foot (40) comprising portions of cylindrical surface which extend in the extension of the cylindrical surface (36) of the platform (22) and which complete this cylindrical surface (36) at the outlets of the housing (38).

14. Propeller (10) for an aircraft turbomachine, comprising an annular hub (12) which extends around an axis of rotation (X) and which comprises a series of orifices (16) which are regularly distributed around the axis of rotation (X) and which are oriented radially relative to the axis of rotation (X), and blades (14) according to one of the preceding claims, the platforms (22) of which are mounted respectively in these orifices (16) so that the blades (20) extend radially outwards from the hub (12), each of the platforms (22) being able to rotate around its pitch axis (Y) inside the orifice (16) of the hub (12).

15. Aircraft turbomachine, comprising a propeller (10) according to claim- previous instruction.

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