Manufacture of an air inlet lip or ring sector of an air inlet lip incorporating openings with turned-in edges

The disclosure relates to a method for manufacturing an air intake lip comprising: the arrangement of a blank facing a three-dimensional forming surface of a die of a hydroforming tool, the forming of an air intake lip preform by hydroforming the blank on the three-dimensional surface of the die, the air intake lip preform having in section a U-shape, the outer wall of the air intake lip comprising at least one hollow housing with an inturned edge and a bottom, the housing having a shape corresponding to the shape of the at least one opening cavity, the cutting of an opening in each hollow housing keeping at least the inturned edge so as to obtain an air intake lip comprising at least one opening having an edge integrally formed with the outer wall of the lip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a National Stage Application under 35 U.S.C. § 371 of International Application No. PCT/FR2021/051833, filed Oct. 20, 2021, now published as WO 2022/084629 A1, which claims priority to French Patent Application No. 2010782, filed on Oct. 21, 2020.

TECHNICAL FIELD

The present invention relates to the manufacture of air intake lips of aeronautical engine nacelles.

PRIOR ART

The nacelles of aeronautical engines include an air intake cowl extended at the front by a lip having in section a U-shape open towards the rear. The air intake lip has in particular the function of ensuring the aerodynamic flow of the air, on the one hand, towards the fan channel and, on the other hand, towards the outside of the nacelle.

The air intake lips are generally manufactured in one piece or from several individual annular sectors assembled together subsequently.

The air intake lips or annular sectors are individually manufactured by sheet metal forming and more specifically by spin forming. Once the air intake lip or the annular sector is manufactured, it is common to make openings by machining into the wall of the lip or of the sector, particularly to house and fix add-on parts there.

The machining of openings in the wall of the lip or of the annular sector after forming can entail so-called “laminarity” defects corresponding to a modification of the aerodynamic profile of the lip or of the sector which is liable to disturb the flow along the outer wall of the lip or of the lip sector.

Furthermore, when an add-on part is fixed at the level of an opening, the fixing members used protrude over the surface of the outer wall of the lip or of the sector, which also disrupts the flow along the outer wall of the lip or of the lip sector. However, there is a need for the manufacture of air intake lips or annular sectors of air intake lips including one or more openings which do not modify the aerodynamic profile of the lip or of the annular sector after forming.

DISCLOSURE OF THE INVENTION

To this end, the invention proposes a method for manufacturing an air intake lip or an air intake lip annular sector comprising:the arrangement of a blank facing a three-dimensional surface of a die of a hydroforming tool, the three-dimensional surface comprising an outer annular portion for forming the outer wall of an air intake lip or of an air intake lip annular sector, the outer annular portion comprising at least one opening cavity protruding over the three-dimensional surface,the forming of an air intake lip or an air intake lip sector by hydroforming the blank on the three-dimensional surface of the die, the air intake lip or the air intake lip annular sector preform having in section a U-shape, the outer wall of the air intake lip or of the air intake lip annular sector preform comprising at least one hollow housing with an inturned edge and a bottom, the housing having a shape corresponding to the shape of said at least one opening cavity,the cutting of an opening in each hollow housing, keeping at least the edge inturned in such a way as to obtain an air intake lip or an air intake lip annular sector comprising at least one opening having an edge integrally formed with the outer wall of said lip or of said sector.

Thus, owing to the method of the invention, each opening is made from a housing formed at the same time as the air intake lip or the air intake lip sector. The forming of the housing can therefore not modify the geometry and the aerodynamic profile of the outer wall when it is carried out simultaneously with the forming of the lip or of the sector. Furthermore, each housing extends under the outer wall. Consequently, each subsequent machining of the housing to form an opening has no impact on the geometry of the outer wall and therefore on the aerodynamic profile of the lip or of the sector.

According to one particular characteristic of the method of the invention, when cutting an opening in one or more hollow housings, only all or part of the inturned edge is kept. In this case, an add-on part can be fixed on the inturned edge of the opening of the hollow housing, said part extending under the outer wall of the air intake lip or of the air intake lip annular sector. The add-on part can in particular be a scoop.

According to another particular characteristic of the method of the invention, when cutting an opening in one or more hollow housings, a portion of the bottom of the hollow housing is kept in such a way as to form a plunging in the opening, the method further comprising the fixing of an add-on part onto the bottom of the housing, said part being present under the outer wall of the air intake lip or of the air intake lip annular sector or flush with the outer wall of the air intake lip or of the air intake lip annular sector.

According to another particular characteristic of the method of the invention, each opening cavity is mounted on a removable key. This in particular makes it possible to facilitate the unmolding of the lip or annular sector preform.

The object of the invention is also an air intake lip or air intake lip annular sector having in section a U-shape, the outer wall of the air intake lip or of the air intake lip annular sector comprising one or more openings, each opening including at least one inturned edge integrally formed with the outer wall and extending under said outer wall.

According to one particular characteristic of the air intake lip or of the air intake lip annular sector of the invention, an add-on part is fixed to the inturned edge of one or more openings present on the outer wall of the air intake lip or of the air intake lip annular sector, said part extending under the outer wall of the air intake lip or of the air intake lip annular sector.

According to another particular characteristic of the air intake lip or of the air intake lip annular sector of the invention, the add-on part is a scoop.

According to another particular characteristic of the air intake lip or of the air intake lip annular sector of the invention, one or more openings further include a plunging and an add-on part on the plunging, said part being present under the outer wall of the air intake lip or of the air intake lip annular sector or flush with the outer wall of the air intake lip or of the air intake lip annular sector.

DESCRIPTION OF THE EMBODIMENTS

The invention generally applies to the production of air intake lips or of annular sectors for air intake lips for aeronautical engine nacelles.

FIG.1describes the steps of a method for manufacturing an air intake lip in accordance with the invention.

As illustrated inFIG.2, the method begins with the provision of a sheet metal plate10, for example made of aluminum alloy (step S1). The sheet metal10can be an integral plate or a plate obtained by assembling several plates fixed together by welding in order to obtain large-sized sheet metal plates from smaller unit sheet metal plates.

The sheet metal plate10is then cut to form a ring20illustrated inFIG.3(step S2).

The ring20is mechanically machined in thickness so as to obtain a constant sheet metal thickness after shaping (step S3).

A truncated cone30illustrated inFIG.4is then formed from the ring20by the known technique of the sheet metal rolling.

Once formed, the truncated cone30is preformed, for example by embossing and/or stamping, into a lip blank40having a general shape similar to that of the final lip, that is to say already having in section a U-shape as represented inFIG.5(step S5).

In accordance with the invention, the final shaping of an air intake lip is then carried out by hydroforming or internal high pressure forming (step S6). More precisely and as illustrated inFIG.6, the blank40is arranged in a mold51, also called die, of a hydroforming tool50, the die51including a three-dimensional surface510corresponding to the shape of the lip preform to be obtained. The tool51is then hermetically closed by a lid52as illustrated inFIG.7. The lid52includes an opening520through which a fluid53under high pressure is introduced. The high-pressure P of the fluid53exerted on the blank40forces the latter to take the shape of the three-dimensional surface510of the die51. In the example described here, the three-dimensional surface510includes an outer annular portion510afor forming the outer wall of an intake lip. The outer annular portion510aincludes two opening cavities511and512of different geometries. In the example described here, the cavity511is intended to allow the formation of a hollow housing for the incorporation of a cover on the air intake lip while the cavity512is intended to allow the formation of a hollow housing for the incorporation of an air outlet on the air intake lip. The opening cavities511and512are preferably respectively mounted on removable keys5110and5120.

Once the hydroforming is complete, a one-piece air intake lip preform60having a shape of revolution having in section a U-shape. The air intake lip is then unmolded as shown inFIG.8(step S7). The opening cavities511and512being here mounted on removable keys5110and5120, they can be removed to facilitate the unmolding of the lip after hydroforming.

At this stage, the air intake lip preform60already has the final geometry of the lip, in particular at the level of its outer wall61along which an air flow is intended to flow. It is therefore important to preserve the aerodynamic profile of the outer wall of the lip. As illustrated in the figure, the intake lip60further includes two hollow housings62and63on its outer wall61respectively formed by the cavities511and512. The hollow housing62comprises an inturned edge620and a bottom621both extending under the outer wall61. Similarly, the hollow housing63comprises an inturned edge630and a bottom631both extending under the outer wall61.

Next, an opening is cut in each of the hollow housings62and63(step S8). As illustrated inFIG.9, an opening622is made in the bottom621of the hollow housing62, for example by machining. In the example described here, the bottom621is not entirely removed in order to leave a portion6210and form a plunging623corresponding to the inturned edge620and to the portion6210both integrally formed with the rest of the air intake lip preform. An opening632is also made in the hollow housing63. In the example described here, the bottom631is entirely removed in order to keep only the inturned edge630.

If the bottom of a hollow housing is entirely removed, all or part of the inturned edge is kept according to the fixing requirements. One may for example remove only the bottom and keep the entire inturned edge. One may also remove a part of the inturned edge in such a way as to adjust the depth of extension of the edge under the outer wall of the lip as needed, or even dispense with an entire part of the inturned edge, for example on one or more sides of the hollow housing.

One thus obtains an air intake lip70of revolution shape having in section a U-shape and including an outer wall71forming the aerodynamic profile of the lip. The outer wall includes two openings710and711corresponding to the openings622and632made in the lip preform60. The opening710includes a plunging7101integrally formed with the outer wall71and extending entirely under it. The opening711includes an inturned edge7110integrally formed with the outer wall71and extending entirely under it.

For the manufacturing of an air intake lip annular sector in accordance with the method of the invention, steps are implemented similar to the previously described steps S1to S8by adapting certain of them to the manufacturing of a sector. For the sake of simplification, not all these steps will be described in detail again. The adaptation of the steps already described consists, in particular, in:cutting a ring portion in the sheet metal plate (adaptation of step S2);forming a truncated cone portion (adaptation of step S4);preforming an air intake lip annular sector blank corresponding to a segment of an air intake lip blank (adaptation of step S5);forming an air intake lip annular sector preform by hydroforming, adapting the hydroforming tooling and in particular the three-dimensional forming surface of the tooling die to the shape of an annular sector (adaptation of step S6).

Thus, the method of the invention makes it possible to form an air intake lip or an air intake lip sector including one or more openings, the plunged or unplunged edges of which are integrally formed with the structure of the lip or sector.

The opening(s) can particularly, but not exclusively, be used for the fixing of an add-on part which is present under the outer wall of the air intake lip or of the air intake lip annular sector or flush with the outer wall of the air intake lip or of the air intake lip annular sector

The method of the invention can consequently further comprise the fixing of one or more add-on parts (step S9). In the example described here and as illustrated inFIG.11, a first add-on part corresponding to a cover80is fixed in the opening710. More precisely and as illustrated inFIG.11, the cover80is fixed to the plunging7101integrally formed with the outer wall71by fixing members81of screw-nut type. The cover80is thus flush with the surface of the outer wall71of the air intake lip70(the outer surface of the cover80is on the same plane as the surface of the outer wall71). Thus the cover80does not disrupt the air flow F along the outer wall71.

A second add-on part, here a scoop90, is fixed in the opening711. More precisely, the scoop90is fixed to the inturned edge7110integrally formed with the outer wall71by the fixing members91of screw-nut type. Since the scoop90and the fixing members91extend entirely under the outer wall they cannot disrupt the flow of the air flow F along the outer wall71.

Furthermore, the presence of fixing edges (plunged or unplunged) integrally formed with the outer wall of the lip or of the annular sector makes it possible to fix an add-on part without having to use a fishplate or an additional mating surface. In this way the overall weight of the air intake lip is reduced.