Method for manufacturing an aircraft engine thrust reverser cascade, and cascade manufactured in this way
Patent Information
- Application Number
- EP2023844360
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-12-29
- Filing Date
- 2023-12-28
- Publication Date
- 2025-11-05
Smart Images
Figure 1.1
Abstract
Description
DESCRIPTION TITLE: METHOD FOR MANUFACTURING A THRUST REVERSER GRID FOR AN AIRCRAFT ENGINE AND GRID THUS MANUFACTURED Technical field
[0001] This disclosure relates to a method of manufacturing an aircraft jet engine thrust reverser grid by injection molding. Prior art
[0002] An aircraft jet engine thrust reverser grid generally comprises a plurality of spars each extending axially in a longitudinal direction X and the spars are arranged parallel to each other while being spaced from each other in a transverse direction Y. The grid also comprises a plurality of vanes extending between the spars in the transverse direction Y, spaced from each other in the longitudinal direction X. The vanes define with the spars a plurality of cavities through which a thrust reversing airflow can flow to perform the thrust reversing function of the jet engine. Each vane extends transversely between two consecutive spars to which it is connected by two respective opposite connecting edges.Each blade also extends in a direction Z perpendicular to the longitudinal directions X and transverse directions Y, from a so-called leading edge and to an opposite edge, called the trailing edge, and according to a curvature so as to form an aerodynamic profile of the blade between the two edges.
[0003] Various techniques for manufacturing inverter grids are known, in particular from documents US 2019 / 0176382, US 9587582, FR 2 869 258.
[0004] However, the techniques described in these documents are often complex to implement insofar as they either use a large number of molds to manufacture a grid with fins of complex shapes, or they use assembly methods, for example by gluing, to assemble at least some of the constituent elements of the grid.
[0005] In view of the above, it would therefore be interesting to be able to simply manufacture an aircraft jet engine thrust reverser grid entirely by injection. Statement of the invention
[0006] The invention thus relates to a method of manufacturing by injection molding a thrust reverser grid of an aircraft reactor, characterized in that the method comprises the use of a mold formed of two parts, each mold part comprising a bearing surface from which extend, away from the bearing surface, a plurality of projections spaced from each other so as to form a matrix according to a projection view in a plane perpendicular to the direction of extension of the projections and which is defined by a first longitudinal direction and by a second transverse direction, the two parts of the mold being positioned head to tail with respect to each other and brought together along a displacement axis D so that the projections of one mold part are inserted between the projections of the other mold part,such that certain areas of the two mold parts are in contact with each other to form a joint plane and that other areas of the two mold parts are spaced from each other and define between them cavities intended to be filled with an injection material to form a single-piece part comprising a plurality of longitudinal spars and a plurality of blades extending transversely between the spars and which jointly form a thrust reverser grid of an aircraft jet engine, the bearing surface and the plurality of projections associated with the bearing surface of each mold part being inclined in a direction of inclination forming an angle α relative to the axis of movement D between the two mold parts contained in a plane containing the first longitudinal direction and a third direction perpendicular to the first two directions,the angle a formed with the axis D being a positive acute angle strictly between 0 and 90° (the angle a thus defined is non-zero).,
[0007] The joint use of a two-part mold and a globally inclined arrangement (along the overall direction of inclination), with respect to the axis of movement D (also subsequently called the demolding axis or direction) of the two parts of the mold relative to each other, of the succession of relief elements of each of the two parts of the mold, makes it possible to manufacture in a simple manner (in a single molding operation) a thrust reverser grid while avoiding the problems of undercutting which arise for certain configurations of grids depending on the orientation of the blades in the grid and their camber. The two parts of the mold include all the projections which, jointly (when the two mold parts are assembled with each other and the injection material is injected into the spaces left free between the two parts), define the set of all the spars and blades integral with the grid.Thus, during the single molding operation carried out with the two mold parts thus configured, a single-piece part is obtained which includes all the spars and blades secured to each other and which forms the inverter grille. The grille is therefore formed in a single operation and not in several parts which would then have to be assembled together. This results in a considerable time saving.
[0008] According to other possible characteristics, taken alone or in combination: -the angle a is between 5° and 30°; -according to a projection view in a plane defined by the first longitudinal direction and by the third direction, the projections of the two mold parts which are inserted between each other each have two opposite faces, namely a rectilinear face and a curved face, convex or concave depending on the mold part, which meet at a vertex of the projection concerned in such a way that, when a projection A of one mold part is inserted between two projections B and C of the other mold part, the curved face of projection A is opposite and distant from the curved face of projection B and the rectilinear face of projection A is in contact with the rectilinear face of projection C, the curved face of projection A being convex while the curved face of projection B is concave so as to jointly define between the two faces a cavity intended to form a blading,the convex face of projection A extending from an edge joining the support surface to the top of the projection; -the convex face of projection A being intended to form an intrados profile of, the blading, a tangent T being defined, according to a projection view in a plane defined by the first longitudinal direction and by the third direction, at a point on this convex face which corresponds to a point of inflection of the curve formed by this face, the tangent T forming an angle pii of between 40 and 90° with the direction of inclination I of the bearing surface and of the plurality of associated projections of the part of the mold of which the projection A forms part; -the angle of inclination a is less than or equal to the angle pii; -the distance along the direction of inclination between two consecutive bladings is chosen so as to provide a bearing zone between the two mold parts, in a region intended to be located on the extrados of the blading of at least 1 mm, preferably at least 2 mm; - the distance along the direction of inclination between two consecutive blades is chosen so as to provide a support zone between the two parts of the mold, in a region intended to be located on the intrados of the blade of at least 1 mm, preferably at least 2 mm; - the two parts of the mold are configured to form the aerodynamic surfaces of the thrust reverser grid; - the support surface and the top of each of the projections of each mold part are locally inclined according to the angle of inclination a relative to the axis of movement D; -the bearing surface and the apex of each of the projections of each mold part extend locally perpendicular to the axis of movement D and extend generally in the manner of a staircase along the angle of inclination a relative to the axis of movement D, the plurality of associated projections of each mold part being inclined along the angle of inclination a (non-zero); -an injection material is injected between the two mold parts when they are in local contact with each other along the joint plane so that the injection material thus injected fills the cavities left free between certain zones, distant from and facing each other, of the two mold parts in order to form a plurality of longitudinal spars and a plurality of blades extending transversely between the spars and which jointly form a thrust reverser grid of an aircraft reactor;-after solidification of the injection material thus injected, the two parts of the mold are moved apart from each other along the axis of movement D in order to demold the injection grid thus manufactured by injection molding.;
[0009] The invention also relates to an aircraft jet engine thrust reverser grid which has been obtained by the method briefly described above. Such a grid comprises a plurality of spars each extending axially in a longitudinal direction X, parallel to each other, and a plurality of blades extending between the spars in a transverse direction Y, the blades which extend transversely between two consecutive spars being spaced from each other in the longitudinal direction X in such a way that the plurality of transverse blades defines with the spars a plurality of spaces through which air can pass, each blade which extends transversely between two consecutive spars is connected to the latter by two respective opposite connecting edges, each blade also extending in a direction Z perpendicular to the longitudinal directions X and transverse directions Y, from an edge,said leading edge, and up to an opposite edge, said trailing edge, so as to form an aerodynamic profile of the blade between the two edges, a tangent to the intrados of the leading edge of each blade forming with the longitudinal direction X of extension of the side members an angle pii which is between 40 and 90°., Brief description of the drawings
[0010] Other characteristics and advantages of the subject of the present disclosure will emerge from the following description of embodiments, given as non-limiting examples, with reference to the appended figures.
[0011] [Fig. 1] Figure 1 is a schematic general view of a mold for manufacturing a thrust reverser grid of an aircraft reactor according to an exemplary embodiment;
[0012] [Fig. 2] Figure 2 is a schematic general top view of a portion of the mold of Figure 1;
[0013] [Fig. 3] Figure 3 is an enlarged partial schematic general view of the two mold parts of Figure 1 before nesting and closing of the mold;
[0014] [Fig. 4A] Figure 4A is an enlarged partial schematic general view of a transverse cavity Ct of the mold of Figure 1;
[0015] [Fig. 4B] Figure 4B is a schematic general view similar to that of Figure 4A showing a transverse cavity C't with an undercut area;
[0016] [Fig. 4C] Figure 4C is a schematic general view showing the transverse cavity C't of Figure 4B inclined in the mold;
[0017] [Fig. 5] Figure 5 is a schematic general view of a mold for manufacturing a thrust reverser grid of an aircraft reactor according to an embodiment of the invention;
[0018] [Fig. 6] Figure 6 is an enlarged partial schematic general view of the two mold parts of Figure 5 after nesting (closed mold);
[0019] [Fig. 7] Figure 7 is a schematic general view of a mold for manufacturing a thrust reverser grid of an aircraft reactor according to another embodiment of the invention;
[0020] [Fig. 8] Figure 8 is a perspective view of a thrust reverser grid of an aircraft jet engine according to one embodiment of the invention. Detailed description
[0021] Figures 1 to 4A-4C illustrate the principle that is applied in the embodiments of the invention that will be described below to explain the injection molding of a thrust reverser grid of an aircraft jet engine using a mold formed only of two parts.
[0022] A thrust reverser grid 1 of an aircraft jet engine, a possible embodiment of which is illustrated in FIG. 8, generally comprises, in top view, a plurality of longitudinal (axial) spars 3 which extend longitudinally in a direction X and a plurality of blades 5 extending transversely between the spars 3 in a direction Y, intersecting with the latter to which they are connected so as to jointly form a grid structure. The grid 1 also extends along its height in a third direction Z perpendicular to the first two directions X and Y. Insofar as the blades are aerodynamic profiles, they also extend in the plane X, Z. The grid also comprises a front flange 7 and a rear flange 9 respectively arranged at the two opposite ends of the grid along its longitudinal direction. These flanges are used to fix the grid to a nacelle of the aircraft reactor.
[0023] Figure 1 illustrates the use of a mold 10 which is, in this embodiment, only in two parts 12 and 14 to manufacture by injection molding such a thrust reverser grid of an aircraft reactor. In this figure each mold part 12, 14 comprises a base or bearing surface from which extend, away from the surface, a plurality of projections spaced from each other. The projections generally extend substantially perpendicular to the base / bearing surface to which they are connected.
[0024] In Figure 1, the mold 12 comprises a base / support surface 16 from which extend, away from the surface 16, a plurality of projections 18 spaced from each other so as to form a matrix according to a projection view in a plane perpendicular to the direction of extension Z of the projections and which is defined by the longitudinal direction X and by the transverse direction Y, as illustrated very schematically in a top view in Figure 2. The mold 14 also comprises a support surface 20 from which extend, away from the surface 20, a plurality of projections 22 which, themselves, are spaced from each other so as to form a matrix similar to that of Figure 2.
[0025] The shapes and positions in an XY plane of projections 18 and 22 are different from each other and complementary in some respects as described later.
[0026] As shown in Figure 1, the two mold parts 12 and 14 are positioned head to tail with respect to each other, the part 12 of Figure 2 having been turned over and positioned above the part 14 with the respective base / support surfaces 16 and 20 being generally horizontally oriented (i.e. the XY plane of Figure 2 is arranged horizontally) and brought together along the vertical axis Z so that the projections 18 of the mold part 12 are inserted or interposed between the projections 22 of the other mold part 14 and the two mold parts locally abut against each other to close the mold. Figure 3 illustrates the vertical bringing together along the vertical arrow descending portions of the two mold parts 12, 14 facing each other in order to close the mold. Thus, in the final position of Figure 1 (mold closed), certain zones (bearing surface) of the two mold parts 12, 14 are in contact with each other to form a joint plane while other zones of the two mold parts are distant from each other and define between them longitudinal and transverse cavities which are intended to be filled with an injection material to form a plurality of longitudinal spars and a plurality of blades extending transversely between the spars and which jointly form a thrust reverser grid of an aircraft reactor like that of Figure 8.
[0027] As shown in Figure 3, the projections 18 each comprise, according to a view projected in a plane XZ, two inclined walls 18a, 18b in the direction of the flattened summit 18c of the projection 18 which they join and which forms a plane span. One 18a of the walls is rectilinear while the other 18b is concave. The two walls extend respectively from two flat portions 18d which each form a span of the base / support surface 16 on either side of each projection 18. Each of the two inclined faces 18a, 18b has surfaces open with respect to the demolding axis or direction D (axis of movement) of figure 1, that is to say that these surfaces do not comprise local tangent planes undercut with respect to the direction D. The inclined face 18a generally has an opening angle of at least 1 to 2°.The demolding axis or direction is the axis or direction along which the two parts of the mold are moved apart from each other to demold the part that has been manufactured by molding inside the mold.
[0028] The projections 22 each comprise, according to a view projected in a plane XZ, two inclined walls 22a, 22b in the direction of the flattened apex 22c of the projection 22 which they join and which forms a plane bearing surface. One 22a of the walls is rectilinear while the other 22b is convex. The wall 22a extends from a plane portion 22d which forms a bearing surface of the base / support surface 20, while the wall 22b extends from a descending indentation formed from the bearing surface 22d and which is intended to form the leading edge of the blade. Each of the two inclined faces 22a, 22b has surfaces open with respect to the axis or direction of demolding D, that is to say that these surfaces do not comprise local tangent planes in undercut relative to direction D. The inclined face 22a generally has an opening angle of at least 1 to 2°.
[0029] The curvatures of the two curved walls 18b and 22b are different from each other so that, in the final close position of Figure 1 (closed mold), the two walls are longitudinally spaced apart from each other and define between them a transverse cavity Ct in which a transverse blading of the grid will be formed after injection of an injection material into the mold by conduits not shown here, and filling of the different cavities, in particular of the transverse cavity Ct. The two walls 18b and 22b facing each other for each pair of walls 18b and 22b (see for example Figure 4A) respectively define the extrados and the intrados of the future blading and their respective curvatures jointly define (in the XZ plane) the curvature of the aerodynamic profile of the blading which can be more or less pronounced according to the selected grid configurations.
[0030] Furthermore, in the final close position of Figure 1 (closed mold), the base / support surfaces 16, 20 with the respective support surfaces 18d, 18c, 22c, 22d are in contact with each other and thus form a parting plane. It will be noted more particularly that the two inclined rectilinear walls 18a and 22a (identical inclination) of the two adjacent projections 18 and 22 are arranged against each other and define the closing slope of the mold. Similarly, the respective surfaces 18d and 22c, 18c and 22d facing each other in Figure 3 are also arranged against each other and define two respective closing support surfaces of the mold. In the example shown, these surfaces are flat, but they can alternatively adopt a different shape.The sum of the dimensions along the X axis of the span 18d, the face 18a, the span 18c and the face 18b determine what is called the longitudinal "pitch" (along X) between two blades, as illustrated by the distance 'p' between the two vertical dotted lines in Figures 1 and 3. The inclination of the closing slope (inclined faces 18a, 22a) directly influences the pitch p between the blades, as does the dimension along the X direction (length) of the closing support surfaces.
[0031] The internal configuration of the two mold parts 12, 14 in an XY plane to define longitudinal cavities between the projections 18 and 22 (in order to subsequently form the thrust reverser grid spars), shown in Figure 8, is known per se and will therefore not be developed further here.
[0032] The manufacture of the thrust reverser grid by injection molding using the mold of Figure 1 requires, in particular, to introduce into the mold an injection material of known type, for example a thermoplastic or short fiber reinforced thermoplastic material, so that it is distributed in the various longitudinal and transverse cavities which are jointly defined between the two mold parts. After solidification of the material, the grid thus manufactured is demolded by removing the molded part from one and the other mold part along the demolding axis or direction D mentioned above.
[0033] Figure 4A illustrates a partial view of a part of the mold of Figure 1 showing a transverse cavity Ct defined jointly by the walls 18b and 22b opposite two adjacent projections 18 and 22 of the two mold parts 12, 14. A blading will be manufactured in this transverse cavity Ct by molding and demolding along the demolding axis D jointly with the two longitudinal members which frame it and to which the blading will be connected.
[0034] Figure 4B illustrates a partial view similar to that of Figure 4A showing a transverse cavity C't jointly defined by the walls 18b' and 22b' opposite two adjacent projections of two mold parts. The orientation of the transverse cavity C't in the mold and possibly its camber (camber of the future blading given by the respective curvatures of the two walls 18b' and 22b') are different from those of Figure 4A.
[0035] Thus, in Figure 4A, we define the angle pii formed between the direction X corresponding to the longitudinal direction of the future spars of the grid and the tangent T to the intrados profile of the blade at the point of the profile where this tangent forms a minimum angle with the longitudinal axis X (outside the radius of the leading edge of the blade). This angle characterizes in particular the orientation of the transverse cavity C't in the mold and its demoldable nature relative to the demolding axis D. In other words, the point of the intrados profile of the blade where the tangent T is defined corresponds to the point of inflection of the curve formed by the intrados, that is to say at the place where the direction of curvature of the intrados profile is reversed.
[0036] Taking this angle pii into account allows us to see that for angles pii greater than or equal to 90° (fig. 4A), the blading from the cavity Ct can be demolded with a two-part mold along the demolding axis D (Z). On the contrary, for angles less than 90° (fig. 4B), the blading from the cavity C't cannot be demolded with a two-part mold along the demolding axis D (Z), due to the undercut zone Zed visible in figure 4B and which corresponds to the area of the intrados of the blading where the curvature is most pronounced. To manufacture such a blading from the transverse cavity C't it is therefore necessary to use more than two molds.
[0037] The inventors have however found a method for demolding a blade with an angle pii less than 90° using a mold comprising only two parts (simplified tooling), in particular to produce the aerodynamic surfaces of the grille. To do this, the inventors planned to tilt in the mold all of the transverse and longitudinal cavities defined jointly by the relief elements of each mold part (plurality of projections spaced from each other in an XY plane following a grid) nested with each other, so as to be able to demold the transverse cavities of the grille along the demolding axis D while avoiding the undercut zones Zed as illustrated in Figure 4B.The overall inclination of the base / support surface and the plurality of projections associated with the base / support surface of each mold part is chosen with an acute angle a which is positive and strictly between 0 and 90° (the angle a is non-zero) relative to the demolding (displacement) axis D between the two mold parts contained in the XZ plane (fig. 4C, inclination direction I). In an exemplary embodiment, the angle a is between 5° and 30°. In figures 1, 3 and 4A-B, the base / support surface and the plurality of projections associated with the / support surface of each mold part are generally perpendicular to the demolding (displacement) axis D between the two mold parts.The inclination angle a is generally less than or equal to the angle pii defined above (in the figures, the angle a is generally represented as being equal to the angle pii but this is only a possibility) so as to eliminate any undercutting of the part relative to the tooling element 14 (mold) and the projections 22 between the blades.
[0038] Figure 5 is a schematic representation of a two-part mold M1 and M2 according to an embodiment of the invention which has the same characteristics as those of Figures 1 to 3 except that the relief elements of each mold part are generally inclined at the angle of inclination a (direction of inclination I) relative to the displacement axis D (90°-o relative to the axis X).
[0039] As shown in Figure 6 which illustrates an enlarged area of the two parts M1 and M2 of the mold of Figure 5 nested one inside the other, the projections 18" and 22" extending respectively from the base / support surfaces 16", 20" of the two mold parts are inserted between each other and each have two opposite faces, namely a straight face 18a", 22a" and a curved face 18b", 22b", convex or concave depending on the mold part, which meet at a vertex 22c", 18c" of the projection concerned. Thus, when a projection A of the mold part M2 is inserted between two projections B and C of the other mold part M1, the curved face 22b" of the projection A is opposite and distant from the curved face 18b" of the projection B and the rectilinear face 22a" of the projection A is in contact with the rectilinear face 18a" of the projection C.The curved face 22b" of the projection A is convex while the curved face 18b" of the projection B is concave so as to jointly define between the two faces a transverse cavity C"t intended to form a blading. The convex face 22b" of the projection A extends from an edge ba (corresponding to the leading edge BA of the future blading) joining the base surface 22d" to the apex 22c" of the projection. The convex face 22b" is intended to form an intrados profile of the blading. The edge ba has a convex shape, for example rounded, which is in the form of a recess or indentation dug into the base / support surface 22d".The tangent T to the intrados profile of the convex face 22b" (this tangent T is defined, according to a projection view in a plane defined by the first longitudinal direction X and by the third direction Z, at a point of the convex face 22b" which corresponds to an inflection point of the curve formed by this face) forms with the overall inclination direction I of the base / support surface and of the plurality of associated projections of each mold part (in particular of the mold part M2 of which the projection A forms part) an angle pii which is for example between 40 and 90°. In the example. represented, the angle a is equal to the angle pii although it is generally less and for example equal to 45°.
[0040] In order to be able to demould the part from part Ml and to be able to demould the mould parts Ml and M2 from each other, each face 18a", 22a" (fig. 6) generally forms with the demoulding axis D a positive acute angle oriented in the opposite direction to the orientation given to the relief elements of the moulds to adopt the non-zero inclination angle a (inclination direction I).
[0041] To ensure demolding with the two-part tool, it is also necessary to have a sufficient pitch 'p' between two consecutive blades (fig. 6). The pitch and the closing slope (faces 18a", 22a" of the projections in contact with the two mold parts) are chosen jointly with the value of the inclination angle a (0 < a <90° and preferably, a is between 5° and 30°) in order to obtain a grid whose number of blades is adapted to provide satisfactory aerodynamic performance (aerodynamic efficiency). Too high an inter-blade pitch with too low an inclination angle a can in fact lead to a restricted number of blades and therefore to reduced aerodynamic performance.
[0042] The distance along the inclination direction I between two consecutive blades (inter-blade pitch) is for example chosen so as to provide a bearing zone between the two mold parts, in a region intended to be located on the blade extrados of at least 1 mm, preferably at least 2 mm, and in a region intended to be located on the blade intrados, the distance is at least 1 mm, preferably at least 2 mm. The bearing zone concerned (in the mold) for the blade extrados is that where the two bearing surfaces 18c" and 22d" of Figure 6 are in contact with each other. The bearing zone concerned (in the mold) for the blade intrados is that where the two bearing surfaces 18d" and 22c" of Figure 6 are in contact with each other.
[0043] The overall inclination of the relief elements of each mold part M1, M2 relative to the demolding axis D results in the fact that, in the XZ plane, the successive relief elements or projections of the two mold parts (e.g. B, A and C in Figure 6) are all located at different axial positions along the Z axis (also taken along the displacement axis D). Thus, projection B is located at a higher position than projection A which, itself, is located at a higher position than projection C and so on starting from one of the two opposite sides of the mold along an XZ plane and which is at the largest axial position (Z) and going to the opposite side which is at the smallest axial position (Z).
[0044] As shown in Figure 6, the base surface (formed by the succession of the bearing surfaces 18d" and 22d") and the apex 18c" and 22c" of each of the projections of each mold part are also locally inclined in the mold according to the angle of inclination a relative to the axis of movement D. According to a possibility not shown in the figures, the mold may comprise, in addition to the two mold parts (M1 and M2 in Figures 5 and 6) configured to form the aerodynamic surfaces of the thrust reverser grid, a movable carriage used to demold another part of the grid.
[0045] Figure 7 is a schematic representation of a two-part mold M'1 and M'2 according to another embodiment of the invention in which the projections 18'" and 22'" of the two mold parts are inserted between each other as in Figures 5 and 6 and, in particular, a projection A' of the mold part M'2 is inserted between two projections B' and C' of the other mold part M'1. The base / support surface 16'", 20'" (formed by the succession of bearing surfaces 18d'" and 22d'") and the apex 18c'" and 22c'" of each of the projections of each mold part extend locally perpendicular to the axis of movement D (instead of being inclined at the angle of inclination a relative to the axis of movement D as in Figure 6) and extend globally in the manner of a staircase at the angle of inclination a relative to the axis of movement D.The plurality of associated projections of each mold part is inclined at the non-zero inclination angle a.
[0046] However, the overall inclination of the plurality of associated projections of each mold part along the inclination angle a relative to the axis of movement D is identical to that of Figure 6. In other words, the only difference between the configurations of the molds of Figures 6 and 7 lies in the orientation of the portions or bearing surfaces of the base / support surfaces 18d'" and 22d'" and the vertices 18c'" and 22c'" of the projections which, in Figure 7, are horizontal and are therefore not inclined like the rest of the mold parts.
[0047] Generally, by using a simple two-part tooling, the manufacturing costs of an aircraft jet thrust reverser grid are reduced.
[0048] Generally speaking, the process described above makes it possible to mold simply, in a single operation, a single-piece part which integrates all the spars and blades of the thrust reverser grid despite the presence of undercuts (all the spars and blades of the grid are formed together in a solid manner during a single molding operation). Furthermore, particularly in the case of a thrust reverser grid whose blade attack angle is acute with the longitudinal direction X (< 90°), the leading edge is molded from a single tooling element (e.g. mold M2 in Figure 6) without any surface alteration, which contributes to good aerodynamic performance.
[0049] Although the present description refers to specific exemplary embodiments, modifications may be made to these examples without departing from the general scope of the invention as defined by the claims. Furthermore, individual features of the various embodiments illustrated or mentioned may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.
Claims
CLAIMS
1. A method of manufacturing by injection molding a thrust reverser grid of an aircraft jet engine, characterized in that the method comprises the use of a mold formed of two parts (Ml, M2), each mold part comprising a bearing surface (16", 20") from which extend, away from the bearing surface, a plurality of projections (18", 22") spaced apart from each other so as to form a matrix according to a projection view in a plane perpendicular to the direction of extension of the projections and which is defined by a first longitudinal direction and by a second transverse direction, the two parts of the mold (Ml, M2) being positioned head to tail with respect to each other and brought together along a displacement axis (D) so that the projections (22") of one mold part are inserted between the projections (18") of the other mold part,such that certain areas of the two mold parts are in contact with each other to form a joint plane and that other areas of the two mold parts are spaced from each other and define between them cavities intended to be filled with an injection material to form a single-piece part comprising a plurality of longitudinal spars and a plurality of blades extending transversely between the spars and which jointly form a thrust reverser grid (1) of an aircraft jet engine, the bearing surface (16", 20") and the plurality of projections (18", 22") associated with the bearing surface of each mold part being inclined in a direction of inclination (I) forming an angle α relative to the axis of movement (D) between the two mold parts (M1, M2) contained in a plane containing the first longitudinal direction (X) and a third direction (Z) perpendicular to the first two directions (X, Y),the angle formed with the axis (D) being a positive acute angle strictly between 0 and 90°.,
2. Method according to claim 1, characterized in that, according to a projection view in a plane defined by the first longitudinal direction (X) and by the third direction (Z), the projections (22", 18") of the two mold parts (M2, M1) which are inserted between each other each have two opposite faces, namely a rectilinear face (22c", 18a") and a curved face (22b", 18b"), convex or concave depending on the mold part, which join at a vertex of the projection concerned in such a way that, when a projection (A) of one mold part is inserted between two projections (B) and (C) of the other mold part, the curved face (22b") of the projection (A) is opposite and distant from the curved face (18b") of the projection (B) and the rectilinear face (22c") of the projection (A) is in contact with the rectilinear face (18a") of the projection (C), the curved face (22b") of the projection (A) being convex while the curved face (18b") of the projection (B) is concave so as to jointly define between the two facing faces (22b", 18b") a cavity intended to form a blading, the convex face (22b") of the projection (A) extending from an edge joining the bearing surface (22d") to the vertex (22c") of the projection.
3. Method according to claim 2, characterized in that, the convex face (22b") of the projection (A) being intended to form an intrados profile of the blade, a tangent (T) being defined, according to a projection view in a plane defined by the first longitudinal direction (X) and by the third direction (Z), at a point of this convex face which corresponds to a point of inflection of the curve formed by this face, the tangent (T) forming an angle pii of between 40 and 90° with the direction of inclination (I) of the bearing surface (20") and of the plurality of associated projections (22") of the part of the mold (M2) of which the projection (A) forms part.
4. Method according to claim 3, characterized in that the angle of inclination a is less than or equal to the angle pii.
5. Method according to one of the preceding claims, characterized in that the distance along the direction of inclination between two consecutive blades is chosen so as to provide a support zone (22d", 18c") between the two mold parts (M2, M1), in a region intended to be located on the extrados of the blade, of at least 1 mm, preferably at least 2 mm.
6. Method according to one of the preceding claims, characterized in that the distance along the direction of inclination between two consecutive blades is chosen so as to provide a support zone (22c", 18d") between the two mold parts (M2, M1), in a region intended to be located on the intrados of the blade, of at least 1 mm, preferably at least 2 mm.
7. Method according to one of the preceding claims, characterized in that the two parts of the mold (M2, M1) are configured to form the aerodynamic surfaces of the thrust reverser grid (1).
8. Method according to one of the preceding claims, characterized in that the bearing surface (16", 20") and the apex (18c", 22c") of each of the projections of each mold part are locally inclined according to the angle of inclination a relative to the axis of movement D.
9. Method according to one of claims 1 to 7, characterized in that the bearing surface and the apex of each of the projections of each mold part extend locally perpendicular to the axis of movement D and extend globally in the manner of a staircase following the angle of inclination a relative to the axis of movement D, the plurality of associated projections of each mold part being inclined according to the angle of inclination a.
10. Method according to one of the preceding claims, characterized in that an injection material is injected between the two mold parts when they are in local contact with each other along the joint plane so that the injection material thus injected fills the cavities left free between certain zones, distant from and facing each other, of the two mold parts in order to form a plurality of longitudinal spars and a plurality of blades extending transversely between the spars and which jointly form a thrust reverser grid of an aircraft reactor.
11. Method according to the preceding claim, characterized in that, after solidification of the injection material thus injected, the two parts of the mold are moved apart from each other along the axis of movement D in order to demold the injection grid thus manufactured by injection molding.
12. A thrust reverser grid (1) for an aircraft jet engine obtained by the method according to one of the preceding claims, characterized in that the grid comprises a plurality of spars (3) each extending axially in a longitudinal direction (X), parallel to each other, and a plurality of blades (5) extending between the spars in a transverse direction (Y), the blades which extend transversely between two consecutive spars being spaced from each other in the longitudinal direction (X) in such a way that the plurality of transverse blades defines with the side members a plurality of spaces through which air can pass, each blade which extends transversely between two consecutive side members is connected to the latter by two respective opposite connecting edges, each blade also extending in a direction (Z) perpendicular to the longitudinal (X) and transverse (Y) directions, from one edge, called the leading edge, and to an opposite edge, called the trailing edge, so as to form an aerodynamic profile of the blade between the two edges, a tangent to the intrados of the leading edge of each blade forming with the longitudinal direction X of extension of the side members an angle pii which is between 40 and 90°.