Method of fabricating a rotor blade filler body, and a rotor blade filler body comprising at least one cellular assembly having closed cells

Abstract

A method of fabricating a filler body for a blade of a rotor. In addition, such a method comprises a succession of steps of adding material layer by layer, each step consisting in making a new layer of material on a preceding layer of material made in the preceding step, at least one of the steps consisting in making an openwork layer of material presenting a plurality of openings, the succession of steps of adding material layer by layer generating openwork layers of material, each having a closed outline, the respective closed outlines of the openwork layers of material touching mutually in pairs and forming a closed envelope of the filler body for the blade.

Claims

1. A fabrication method for fabricating a filler body of a blade for a rotor, the method comprising a succession of steps of adding material layer by layer, each step consisting in making a new layer of material on a preceding layer of material made in the preceding step, at least one of the steps consisting in making an openwork layer of material presenting a plurality of openings, the succession of steps of adding material layer by layer generating openwork layers of material, each having a closed outline, the respective closed outlines of the openwork layers of material touching mutually in pairs and forming a closed envelope of the filler body for the blade, wherein the succession of steps of adding material layer by layer generates openwork layers of material, each having a plurality of geometrical shapes arranged within the closed outline and allowing to define the plurality of openings of the openwork layer of material, the pluralities of respective geometrical shapes in the openwork layers of material touching mutually in pairs and forming a cellular lattice of closed cells arranged inside the closed envelope of the filler body of the blade, wherein the cells have the form of a polyhedra selected from the group consisting of tetrahedra, hexahedra, octahedra, dodecahedra and icosahedra.

2. The fabrication method according to claim 1, wherein the succession of steps of adding material layer by layer generates openwork layers of material made out of the same substance.

3. The fabrication method according to claim 1, wherein the succession of steps of adding material layer by layer generates openwork layers of material made of at least two substances distinct from each other.

4. The fabrication method according to claim 3, wherein the succession of steps of adding material layer by layer generates at least two openwork layers of material distinct from each other, a first layer being formed out of a first substance and a second layer being formed out of a second substance distinct from the first substance.

5. The fabrication method according to claim 3, wherein the succession of steps of adding material layer by layer generates at least one openwork layer of material made out of the at least two substances that are distinct from each other.

6. A filler body for a blade of a rotor, the filler body comprising at least one cellular lattice of closed cells made by a fabrication method according to claim 1, wherein the closed envelope totally covers the cellular lattice.

7. The filler body according to claim 6, wherein the cellular lattice is made up of cells each having at least four faces each face of the cells being formed by a respective polygon having at least three sides.

8. The filler body according to claim 7, wherein the cellular lattice includes at least two groups of cells that are distinct from each other.

9. The filler body according to claim 8, wherein the cellular lattice comprises a first group of cells for which each of the at least three sides presents a respective first length L1, and a second group of cells for which each of the at least three sides presents a respective second length L2 distinct from the first length L1.

10. The filler body according to claim 8, wherein the cellular lattice includes a third group of cells for which each of the at least three sides presents a respective first thickness e1, and a fourth group of cells for which each of the at least three sides presents a respective second thickness e2 distinct from the first thickness e1.

11. The filler body according to claim 8, wherein the cellular lattice includes a fifth group of cells for which each of the polygons forming the at least four faces presents a respective first shape and a sixth group of cells for which each of the polygons forming the at least four faces presents a respective second shape distinct from the first shape.

12. The filler body according to claim 8, wherein the cellular lattice includes a seventh group of cells made of a first substance, and an eighth group of cells made of a second substance distinct from the first substance.

13. A fabrication method for fabricating a filler body of a blade for a rotor, the method comprising a succession of steps of adding material layer by layer, each step comprising making a new layer of material on a preceding layer of material, at least one of the steps comprising making an openwork layer of material presenting a plurality of openings, the succession of steps of adding material layer by layer generating openwork layers of material, each having a closed outline, the respective closed outlines of the openwork layers of material touching mutually in pairs and forming a closed envelope of the filler body for the blade, wherein the succession of steps of adding material layer by layer generates openwork layers of material, each having a plurality of geometrical shapes arranged within the closed outline and allowing to define the plurality of openings of the openwork layer of material, the pluralities of respective geometrical shapes in the openwork layers of material touching mutually in pairs and forming a cellular lattice of closed cells arranged inside the closed envelope of the filler body of the blade, the closed cells having the form of a polyhedra selected from the group consisting of tetrahedra, hexahedra, octahedra, dodecahedra and icosahedra.

14. The fabrication method according to claim 13, wherein the succession of steps of adding material layer by layer generates openwork layers of material made out of the same substance.

15. The fabrication method according to claim 13, wherein the succession of steps of adding material layer by layer generates openwork layers of material made of at least two substances distinct from each other.

16. The fabrication method according to claim 15, wherein the succession of steps of adding material layer by layer generates at least two openwork layers of material distinct from each other, a first layer being formed out of a first substance and a second layer being formed out of a second substance distinct from the first substance.

17. The fabrication method according to claim 15, wherein the succession of steps of adding material layer by layer generates at least one openwork layer of material made out of the at least two substances that are distinct from each other.

18. A filler body for a blade of a rotor, the filler body comprising at least one cellular lattice of closed cells made by a fabrication method according to claim 13, wherein the closed envelope totally covers the cellular lattice.

19. The filler body according to claim 18, wherein the cellular lattice is made up of cells each having at least four faces each face of the cells being formed by a respective polygon having at least three sides, wherein the cellular lattice includes at least two groups of cells that are distinct from each other, and wherein the cellular lattice comprises a first group of cells for which each of the at least three sides presents a respective first length L1, and a second group of cells for which each of the at least three sides presents a respective second length L2 distinct from the first length L1.

20. A fabrication method for fabricating a filler body of a blade for a rotor, the method comprising a succession of steps of adding material layer by layer, each step comprising making a new layer of material on a preceding layer of material made in the preceding step, at least one of the steps comprising making an openwork layer of material presenting a plurality of openings, the succession of steps of adding material layer by layer generating superimposing openwork layers of material, each having a closed outline, the respective closed outlines of the openwork layers of material touching mutually in pairs and forming a closed envelope of the filler body for the blade, wherein the succession of steps of adding material layer by layer generates openwork layers of material, each having a plurality of geometrical shapes arranged within the closed outline and allowing to define the plurality of openings of the openwork layer of material, the pluralities of respective geometrical shapes in the openwork layers of material touching mutually in pairs and forming a cellular lattice of three dimensional closed cells arranged inside the closed envelope of the filler body of the blade, the closed cells having the form of a tetrahedra, hexahedra, octahedra, dodecahedra or icosahedra.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and its advantages appear in greater detail from the context of the following description of examples given by way of illustration and with reference to the accompanying figures, in which:

(2) FIG. 1 is a diagrammatic side view of a rotorcraft fitted with blades, in accordance with the invention;

(3) FIGS. 2, 3, and 5 are cross-section views of various embodiments of filler bodies in accordance with the invention;

(4) FIG. 4a comprises two perspective views of two distinct groups of cells forming a cellular lattice in a filler body in accordance with the invention;

(5) FIG. 4b shows projections onto a plane of two polygons illustrating the shape of two distinct groups of cells forming a cellular lattice of a filler body in accordance with the invention;

(6) FIG. 6 shows two perspective views of two other distinct groups of cells forming a cellular lattice of a filler body in accordance with the invention; and

(7) FIGS. 7 and 8 are two flow charts showing two methods of fabrication in accordance with the invention.

(8) Elements present in more than one of the figures are given the same references in each of them.

DETAILED DESCRIPTION OF THE INVENTION

(9) It should be observed that three mutually orthogonal axes X, Y, and Z are shown in FIGS. 2, 3, and 5.

(10) The axis X is said to be transverse insofar as it extends transversely along a chord of the aerodynamic profiles of sections of a blade between a leading edge and a trailing edge, the blade including a filler body in accordance with the invention.

(11) Another axis Y is said to be longitudinal and it extends perpendicularly relative to the axis X, substantially in the span direction of the blade.

(12) Finally, a third axis Z is said to be in elevation and corresponds to the thickness dimensions of the aerodynamic profiles of sections of the blades between a suction side face and a pressure side face of the aerodynamic profile.

(13) As mentioned above, the invention thus relates to a filler body for a rotor blade or a propeller blade, e.g. for a rotorcraft.

(14) As shown in FIG. 1, such a filler body may be arranged in a blade 5 of a main rotor 9 and/or in a blade 15 of a tail rotor 19 of a rotorcraft 6.

(15) As mentioned above, such a filler body is remarkable in that it is fabricated by an ALM type method by superposing layers of material on one another, e.g. by stereo lithography or by three-dimensional printing.

(16) As shown in FIG. 2, and in a first embodiment, the filler body 1 is made by superposing openwork layers 2 of material, each including a plurality of geometrical shapes 7 inscribed in each of the planes parallel to the XY plane. In addition, each of these geometrical shapes 7 defines an opening 101 arranged in the openwork layers 2 of material.

(17) Furthermore, these geometrical shapes 7 are defined by respective closed outlines 3 in each plane parallel to the XY plane and they make it possible to generate a closed three-dimensional envelope 4 for the filler body 1. For example, an openwork layer of material may be printed by moving a print head in a plane parallel to the XY plane, then moving the print head along the axis Z, and then printing a new openwork layer of material on the preceding layer parallel to the XY plane.

(18) Such combined movement of the print head along the axes X, Y, and Z thus makes it possible to make a blade filler body that extends in three dimensions along the three axes X, Y, and Z.

(19) Naturally, such an orientation of the layers is given by way of non-limiting indication. In addition, the openwork layers of material may also be arranged in planes parallel to the XZ plane and the print head may be moved along the axis Y between two operations of depositing an openwork layer of material.

(20) Furthermore, such a closed envelope 4 thus contains a cellular lattice 8 made up of different closed cells 50, 60 extending in three dimensions along the three axes X, Y, and Z, and serving in particular to vary the density of the filler body 1 along the three axes X, Y, and Z, and also to vary the stiffness and/or the mechanical strength characteristics along the three axes X, Y, and Z of such a filler body 1.

(21) More particularly, these different variations in density for the filler body 1 along the three axes X, Y, and Z and variations in the stiffness and/or mechanical strength characteristics along the three axes X, Y, and Z can be implemented by using different groups of cells 50, 60.

(22) Thus, a first group 71 of cells 50 may be formed by tetrahedra, i.e. having four faces 51-54, as shown in FIG. 4a, these faces 51-54 being made up by points defined by their coordinates along the axes X, Y, and Z. Likewise, a second group 72 of cells 60 may be made up of tetrahedra each having four faces 61-64 defined by other points with coordinates along the axes X, Y, and Z.

(23) As shown in FIG. 4b, each face 51-54 of the cells 50 of the first group 71 may have sides 55-57, each having a respective length L1. Likewise, each face 61-64 of the cells 60 of the second group 72 may have sides 65-67, each having a respective length L2. Under such circumstances, the length L1 of the cells 50 is then distinct from the length L2 of the cells 60.

(24) Likewise, and as shown in FIG. 3, the filler body 11 is made by superposing layers 12, 12′ of material, each including a plurality of geometrical shapes 17 inscribed in each of the planes parallel to the XY plane. In addition, these geometrical shapes 17 are defined by respective closed outlines 13, 13′ in each plane parallel to the XY plane, enabling a closed three-dimensional envelope 14 to be generated for the filler body 11 by moving the print head along the axis Z.

(25) Such a filler body 11 may then have at least two layers 12 and 12′ that are mutually distinct. A first layer 12 may then be made of a first substance, while the second layer 12′ is made of a second substance distinct from the first substance.

(26) Furthermore, each closed envelope 14 may likewise contain a cellular lattice 18 of different closed cells 50, 60 serving in particular to vary the density of the filler body 11 along the three axes X, Y, and Z and to vary the stiffness and/or the mechanical strength characteristics along the three axes X, Y, and Z of such a filler body 11.

(27) As shown in FIG. 4b, each face 51-54 of the cells 50 of a third group 73 may have sides 55-57, each presenting a thickness e1. Likewise, each face 61-64 of the cells 60 of the third group 74 may have sides 65-67, each having a thickness e2. Under such circumstances, the thickness e1 of the cells 50 is distinct from the thickness e2 of the cells 60.

(28) As shown in FIGS. 5 and 6, the cellular lattice 28 includes a fifth group 75 of cells 150 in which the respective polygons forming the four faces 151-154 present a first shape 155 so as to produce a tetrahedron, and a sixth group 76 of cells 160 in which the respective polygons forming the six faces 161-164 present a second shape 165 suitable for forming a cube or a hexahedron.

(29) In addition, the cellular lattice 28 may also have a seventh group 77 of cells 150 made of a first substance and an eighth group 78 of cells 160 made of a second substance distinct from the first substance.

(30) Furthermore, a single layer 22 of material in the filler body 21 may thus be made up of two substances that are mutually distinct.

(31) Consequently, such a cellular lattice 28 comprises different closed cells 150, 160 allowing in particular to vary the density of the filler body 21 along the three axes X, Y, and Z, and to vary the stiffness and/or the mechanical strength characteristics of such a filler body 21 along the three axes X, Y, and Z.

(32) As shown in FIGS. 7 and 8, the invention also relates to a method of fabricating such a filler body 1, 11, 21. As mentioned above, the fabrication method 30, 40 comprises a succession of steps 31, 32, 41, 42 of adding material layer by layer, each step 32, 42 consisting in making a new layer of material on a preceding layer of material made in the preceding steps 31, 41.

(33) In a first method of fabrication 30, as shown in FIG. 7, the succession of steps 31, 32 of adding material layer by layer may generate openwork layers 2 of material that are made of the same substance.

(34) Nevertheless, in a second fabrication method 40, as shown in FIG. 8, the succession of steps 41, 42 of adding material layer by layer may generate openwork layers of material 12, 12′, 22 made up of at least two substances that are distinct from each other.

(35) Naturally, the present invention may be subjected to numerous variations and combinations as to its implementation. Although several embodiments are described, it will readily be understood that it is not conceivable to identify exhaustively all possible embodiments. It is naturally possible to replace any of the means described by equivalent means without going beyond the ambit of the present invention.