EP2846987A1

EP2846987A1 - Method for producing a composite skin forming a non-strippable rotationally-symmetrical collar

Info

Publication number: EP2846987A1
Application number: EP13723893.7A
Authority: EP
Inventors: Frédéric FOSSE; Guy Bernard Vauchel
Original assignee: Aircelle SA
Current assignee: Safran Nacelles SAS
Priority date: 2012-05-10
Filing date: 2013-05-02
Publication date: 2015-03-18
Also published as: RU2014148725A; US20150059967A1; CN104271336A; BR112014026973A2; CA2870946A1; FR2990376A1; FR2990376B1; WO2013167826A1

Abstract

The invention relates to a method for producing a composite skin forming a non-strippable rotationally-symmetrical collar, consisting in: draping (3) plies of fabric over a mould (1) forming a rotationally-symmetrical collar, providing a separating line on the drape thus obtained, pre-impregnating or post-impregnating the drape with resin, curing the resin, removing the resulting skin from the mould (1) using the separating line, and, subsequently, splinting the two edges (13a, 13b) of the skin defined by the separating line.

Description

Method of manufacturing a non-demoldable ferrule composite skin

The present invention relates to the field of manufacture of skins composites forming ferrules, that is to say substantially having a symmetrical shape of revolution about an axis.

Such composite skins, obtained by arranging folds of fabric on a tool forming a ferrule, impregnated with resin beforehand (folds of "pre-impregnated") or subsequently (so-called "post-impregnated" or "infused") to their set-up on the tooling, are used in particular for the nacelle air intakes for aircraft turbojets, where they are then drilled and coupled to honeycomb-like honeycomb structures.

In this way, so-called "360 °" sandwich structures are obtained, that is to say making it possible to perform an acoustic absorption function over the entire inner periphery of the air inlet: such structures are known for example documents FR 2 847 304, FR 2 931 205 and WO 2005/090156.

A constant problem involved in the manufacture of such sandwich structures is that the skin forming ferrule generally has convex zones which exclude the possibility of demolding the skin of a tool in a single operation.

It is therefore necessary to realize a complex tool comprising several moving parts relative to each other (called "keys"), or to realize the composite skin in several parts that is then connected to each other.

In either case, the operations are complex, and give rise to numerous aerodynamic accidents on the surface of the skin obtained at the end of the process, in the connection zone or between the different keys of the tooling either between the different parts forming the skin.

The present invention aims in particular to reduce these disadvantages, and provides for this a method of manufacturing a shell composite skin comprising the following successive steps to:

- draping folds of fabrics, either pre-impregnated or dry, on a mold, said mold forming a shell and having a bulge prevented hantled é moul ag e pe at the co m po s ite by axial sliding of said skin on said mold, - provide a separation line defining two edges on the draping thus obtained,

post-impregnating this resin draping if the deposited fabric is dry,

- cook this resin,

- Remove from the mold the skin thus obtained thanks to the separating line,

- splint the two edges of the skin.

Thus, to remove the cooked skin of the shell mold, it is sufficient to separate the two edges of the skin located on either side of the line of separation, using the elasticity of this skin.

The present invention thus makes it possible to considerably simplify the manufacture of composite skins forming non-demoldable ferrules, and to limit aerodynamic accidents on the surface of such skins.

According to other optional features of the present invention:

said separation line is produced by means of a groove formed in said shell mold, into which a cutting tool is introduced before the arrival of the resin;

- A strip is placed in said groove prior to the impregnation of the folds by the resin;

said separation line is made with at least one fixed strip integral with said shell mold, against which two edges of the draping of folds abut;

- o n m and e n p l a u co-v re-reg lette on rite rite prior to the impregnation of the plies by the resin;

said dividing line is made by simply cutting the ply draping in its thickness, possibly with a cut in full thickness followed by cuts in only a part of the thickness of the draping, making it possible to obtain stepped edges;

said separation line is made by overlapping two edges of the draping;

a separator is placed between the two edges of the draping adjacent to the separation line prior to impregnation of the folds with the resin;

said separation line is produced by covering an imprint formed on the shell mold; said dividing line is made by draping the folds on a mold forming a ferrule of dimensions greater than those of the final piece, in order to obtain an open skin, and the two edges of this drape adjacent to the separation after baking of the resin;

said separation line is produced in a direction chosen from the group comprising the longitudinal direction, the transverse direction, and any position intermediate between these two positions;

said resin draping is impregnated if it is dry fabric used, especially in the "infusion" version, by means of a bladder which is applied on this drapery against the mold forming a ferrule, and which is put under empty;

the two edges of the skin are made to be spliced on the inside of a tool with keys;

- It is reported on said skin lined disposed on or inside said key tool, honeycomb-like honeycomb structure;

said composite skin is glued inside or outside of an assembly formed of a honeycomb-like honeycomb structure fixed on another composite skin, and the splicing of the two edges of the composite is carried out; the skin on or inside this set.

If necessary, the acoustic piercing of the skin can be done after polymerization of this skin, before implantation of the honeycomb structure. Alternatively, this skin can be pierced after implantation of the alveolar structure.

Other features and advantages of the present invention will emerge in the light of the description which follows, in which:

FIG. 1 is a view from above of a shell mold on which fabric folds for the formation of a composite skin have been draped, corresponding to a first embodiment of the process according to the invention,

FIG. 1a is a detailed view of zone I of FIG. 1; FIGS. 1b to 1f are views similar to those of FIG.

1 a, highlighting the different steps of this first embodiment of the method according to the invention,

FIGS. 1 g and 1 h are similar respectively to FIGS. 1 and 1 a, and relate to a variant of the first embodiment of the method according to the invention, FIGS. 2 to 2i are similar respectively to FIGS. 1a to 1h, and relate to a second embodiment of the method according to the invention,

FIGS. 3 to 3e relate to a third embodiment of the method according to the invention, it being noted that FIG. 3b is a cross-sectional view of the separation zone of the draping disposed on the shell mold,

FIGS. 4 to 4e are cross-sectional views of this separation zone, for a fourth embodiment of the method according to the invention,

FIGS. 5 to 5b are cross-sectional views of this separation zone, for a fifth embodiment of the method according to the invention,

FIGS. 6 and 6a are cross-sectional views of this separation zone, for a sixth embodiment of the embodiment method according to the invention,

Figures 7 and 8 are views similar to those of Figures 1 and 2, in the case where the dividing line on the draping is transverse,

FIG. 8a is a detailed view of zone VIII of FIG. 8, FIG. 9 schematically shows the production of a composite skin on a shell mold, when this skin is disposed outside this mold,

FIG. 9a shows the splicing of the composite skin thus obtained, arranged outside a key tool,

FIG. 9b illustrates the placement of a honeycomb-like honeycomb structure on the composite skin spliced at the end of the step of FIG. 9a,

FIGS. 10 to 10b illustrate steps analogous to those of FIGS. 9 to 9b, when the composite skin is deposited inside a shell mold, then spliced and covered with a honeycomb-type honeycomb structure. bee inside a key tool,

FIGS. 1 1 to 1 1 c are similar respectively to FIGS. 9 to 9b, and relate to the embodiment of FIGS. 6 or 6a, being noted that Figure 11b is an enlargement of the area XI of Figure 11a,

FIGS. 12 to 12c are similar to FIGS. 10 to 10b, respectively, for a mode of realization analogous to that of FIGS. 6 to 6a, being noted that FIG. 12b is an enlargement of zone XII of FIG. 12a, and

FIGS. 1a and 1b are views of another embodiment of the method according to the invention.

In all of these figures, identical or similar references designate members or sets of identical or similar members.

It should also be noted that, for each of the figures, an XYZ mark has been represented, each axis of which is inseparable, respectively, to the longitudinal, transverse and vertical directions of an aircraft on which is mounted a nacelle incorporating the less a composite skin obtained by the process according to the invention.

Referring to Figure 1, we can see a mold forming shell 1, made for example of steel or other metal alloys.

This mold 1 is intended to be covered with a draping fabric for the formation of a piece in com posite having a substantially symmetrical shape of revolution.

As can be seen in FIG. 1, the mold 1 has a bulge 5 preventing the demolding of the composite skin simply by axial sliding of this skin on this mold.

To allow this release, a longitudinal groove is provided

7 formed in the thickness of the mold 1, and extending slightly beyond the area of the mold to be draped by the folds of fabric 3, as can be seen in particular in Figure 1 b.

To achieve the composite skin, it begins by draping the plies of fabric over the entire periphery of the mold 1, including the groove 7, as shown in Figure 1 b.

Then, as can be seen in FIG. 1c, by means of a cutting tool 9 actuated manually or automatically, the pleat draping is cut along the groove 7. Then, as can be seen in FIG. 1b, a strip 1 1 having a substantially T-shaped section inside the groove 7 is brought in so as to close this groove along its entire length.

Then covering the entire draping, including the strip 1 1, a flexible bladder 14 which is put under vacuum, thus ensuring the tight overlap of the entire draping 3 and the strip 1 1.

In the case of infusion of resin, the polymerizable resin is introduced under pressure under the flexible bladder 14 ("post-impregnation" also known as "infusion" of resin), so that this resin impregnates all the draping.

The temperature of the assembly thus obtained is raised, for example inside an autoclave, so as to cure the resin.

Subsequently, the flexible bladder is removed, then the ruler 11, and the resulting composite skin is removed from the mold 1 by means of the dividing line previously made along the groove 7, and the relative flexibility of this skin.

Note that it is possible to provide two substantially parallel grooves 7a and 7b, as shown in FIG. 1h, making it possible to produce two cutting lines in the draping, for example when it is desired that the composite skin thus obtained has a greater diameter than the final need.

Note that in this particular case, one can provide a strip similar to that of Figure 1 e, but having two feet for insertion respectively into the grooves 7a and 7b.

In the embodiment of Figure 2, a strip 1 1 fixedly mounted on the mold 1, and extending longitudinally slightly beyond the two ends of the draping 3, as can be seen in particular in Figures 2 and 2b.

In this embodiment, it is possible to perform the draping 3 so that one of its edges 13a abuts against the strip 1 1, and the other of its edges 13b slightly covers this strip 1 1, being noted that in the next step shown in Figure 2c, it comes cut by means of a tool 9 the su rong ueu r r d rap rapage so that both edges of cel u i-ci come properly abut on both sides of the strip 1 1.

In another variant shown in FIG. 2d, it is possible to use the two faces of the control unit 1 1 as the start and finish faces of the draping, the pla ying of the dif- ferent elements forming this draping being realisé at the arrival in abutment against the faces of this strip: in this case, no cutting tool is necessary.

In one or the other of these two variants, the strip 1 1 is then covered with a strip cover 15, which is in fact a female part capable of receiving this strip 1 1 while pressing on the edges adjacent to the draping 3.

Step 2f is similar to step 1 f: this step consists in fact covering the draping and the cover-ruler 15 of a bladder 14 that is put under vacuum, then to introduce the resin under pressure if c The dry fabric is used in the "infusion" version, the assembly thus obtained being placed in an autoclave in order to harden the resin.

The demolding of the composite skin thus obtained is shown in FIG. 2g. As in the preceding embodiment, the elasticity of this skin is used to separate the two adjacent edges of this skin of the strip 1. (Arrows F1, F2), to exit axially (arrows F3 and F4) this skin of the mold 1.

Note that, alternatively, it is also possible to use fabric folds pre-impregnated with resin. This is also applicable to the embodiments which will be described in the following.

In the variant represented in FIGS. 2h and 2i, it can be seen that two strips 11a and 11b can be provided, similarly to the two grooves 7a and 7b of the preceding embodiment, in which case it is necessary to envisage a two-groove strip cover, suitable for fitting respectively on these two strips 1 1 a and 1 1 b.

In the embodiment of FIGS. 3a and 3e, no groove or ruler is provided on the surface of the mold 1.

As shown in Figure 3, it is sufficient to cut the draping 3 full skin by means of a cutting tool 9, as indicated by the cutting line 17.

Alternatively, as shown in FIG. 3, it is possible to make a cutout 17 on a thickness of the lay-up 3, as well as a plurality of adjacent cut-outs 17a, 17b, 17c, 1 7d, on the different layers of draping. Once this cut is made, as shown in Figures 3b and 3c, is placed a sheet of a separator January 9 between the two edges 1 3a and 1 3b of the draping.

This light, which can be made, for example, from PTFE (polytetrafluoroethylene), is chosen so that its outer surface 19a is polymerizable with the resin, while its inner surface 19b (that is to say its face facing the mold 1) is not.

This separator 19 allows, during the resin impregnation step (see Figure 3d similar to that of Figures 1f and 2f) if it is dry fabric used in "infusion" version, to prevent the resin does not is glisse between the two edges 13a and 13b of the draping.

Once the polymerization step of the resin has been carried out, the two edges of the composite skin thus obtained can be removed and removed from the mold 1, as shown in FIG. 3e.

The protruding portion of a separator 19 may be removed, for example by cutting.

The embodiment of FIGS. 4a and 4e differs from the preceding one in that provision is made for overlap between the edges 13a and 13b of the draping 3.

It is envisaged, as in the previous embodiment, the establishment of a separator 19, having the same characteristics of polymerization on its faces 19a and 19b that those described with reference to Figure 3b.

In the variant shown in Figure 4, this separator is glued under the edge 13b of the draping 3, which edge is kept spaced from the other edge 13a of this draping by a strip 21 of appropriate shape.

In the variant shown in Figure 4a, the separator 1 9 is bonded to the edge 13a of the draping 3, to be covered by the other edge 13b of this layup.

In one case as in the other, once we have covered the edge 13a of the draping 3 by the edge 13b, we arrive at the configuration of Figure 4c, in which we can observe a mutual overlap of these two edges , the separator 19 then having a substantially bayonet section.

Fig ure 4d illustrates the positioning of the flexible bladder 14, permitting the impregnation of draping by the resin under pressure if it is dry fabric used in "infusion" version. FIG. 4e shows the result obtained after passing through an autoclave: the separator 9 remains in the same state as the edge 1 3b of the rapag e, the effect of the polymerization of the resin, but is easily detached from the other edge 1 3a of this draping, thus allowing the spacing of the two layers of the composite layer thus obtained in view of its axial retraction of the mold 1.

In the embodiment of FIGS. 5a and 5b, a longitudinal impression 23 integral with the shell mold 1 is provided.

The lay-up 3 is then placed so that its edge 13a abuts between this impression 23, and its other edge 13b substantially covers this impression 23.

Ai nsi, near the ispos ion of the bladder ie sou pl e 14 (fig ure 5a), impregnation of the draping resin (if it is dry fabric used in version "infusion") and autoclave cooking, one can separate the two edges of the composite skin obtained, as shown in Figure 5b, these two edges having a geometry suitable for their subsequent recovery, because of the bayonet shape imparted by the footprint 23 at the edge 1 3b of the skin composite, as visible in this figure 5b.

The embodiment of Figures 6 and 6a shows that it is also possible to perform a draping on a mold forming ferrule 1, having dimensions greater than those desired for the final composite skin.

In this case, the mold 1 is draped only over part of its periphery, so as to leave a circumferential distance d between the two edges 13a and 13b of this draping.

It is also possible to arrange the different folds of this draping so that they have a stair configuration, as can be seen in FIG. 6a.

FIG. 7 shows that the foregoing precepts can be applied to the realization of a transverse junction zone 25 between two halves 3a and 3b of the draping 3.

This transverse junction line 25 is then at the right of the bulge 5 of the shell mold 1.

FIGS. 8 and 8a illustrate the particular case in which this joining line 25 is produced according to the precepts of the embodiment of FIGS. 5a, 5b, ie with the production of a cavity 23 all around the circumference of the shell mold 1. In the latter case, as in the embodiment of FIGS. 5a, 5b, one finds oneself with a composite skin comprising two mutually overlapping edges 1 3a and 1 3b, this covering being in the circumferential species.

FIGS. 9a and 9b summarize the manufacture of a composite skin according to any one of the embodiments of FIGS. 1 to 5, in the case where the draping is carried out on a mold forming a male shell.

As can be seen in FIG. 9, therefore, the drape 3 is first made on the outer periphery of the mold 1.

After the resin impregnation steps if it is dry fabric used in the "infusion" and cooking version, it is possible to demold the composite skin obtained from the mold 1 by elastic deformation of this skin, as indicated previously.

This skin is then placed on a tool with keys 27, that is to say on a tool having several elements movable relative to each other, allowing the removal of the composite skin including when it became monobloc that is, when these two opposite edges 13a and 13b have been joined to each other.

On this key tool 27, the ecluder 29 is made of the two edges 13a, 13b of the composite skin.

This splicing is typically performed by providing and polymerization of an outer composite member.

Then, in the case where it is desired that the composite skin be covered with an acoustically absorbent structure, it is possible to relate to the outer periphery of this composite skin, by gluing, a honeycomb-like honeycomb structure 31, which i will preferably be densified in the zone 33 which is opposite the splice 29.

Once all these operations have been completed, the key tool 27 can be dismantled so as to recover the part thus obtained.

Note that the acoustic piercing of the skin can be done after polymerization of this skin, before implantation of the alveolar structure. Alternatively, this skin can be pierced after implantation of the alveolar structure.

Figures 10 to 10b are similar to Figures 9 to 9b, and relate to a variant in which the draping folds is made inside a mold 3, and then treated according to the method according to the invention. invention. More specifically, once the composite skin obtained at the end of the various steps described above, we can remove the skin from the inside of the mold 1 by elastic approximations of these two edges 13a, 13b.

The steps of splicing the skin inside a key tool

27 (FIG. 10a), then supplying honeycomb-like honeycomb structure 31 (FIG. 10b), are then similar to those described with reference to FIGS. 9a and 9b.

Figures 11 to 11c are similar to Figures 9 to 9b, but relate to the embodiment of the method according to the invention described in Figure 6a.

As indicated above, in this particular embodiment, the draping of folds 3 is carried out on a mold forming a ferrule 1 having dimensions greater than those of the part which it is finally desired to obtain.

We can see in Figure 11 the layup staircase, corresponding to that shown in Figure 3.

FIG. 11b shows that splicing on a key tool 27 takes place in this case by providing a plurality of composite outer members 29a, 29b.

The embodiment of FIGS. 12 to 12c is similar to that of FIGS. 11 to 11c, but in the case where the draping of folds 3 is carried out inside a shell mold 1, and / or the splice and the contribution of a honeycomb structure are made inside a key tool 27.

As can be understood in the light of the above, the method according to the invention makes it possible to produce composite skins in the form of ferrules, that is to say at 360 °, presenting the minimum of aerodynamic accidents, with extremely simple tools.

This method, according to which a separation line is produced at a suitable location of the draping of fabric folds, and the resulting composite skin is recovered by elastic deformation with respect to its mold, makes it possible to obtain composite skins presenting forms substantially symmetrical of revolution, that it would be impossible to obtain without complex key tools. It is possible to obtain composite skins forming ferrules having areas of hollow and bulge excluding any demolding by translation compared to a traditional mold.

Of course, the present invention is not limited to the embodiments described and shown, provided as simple examples.

For example, it is also possible to envisage placing a composite skin obtained by the process described above, inside or outside an assembly formed of a honeycomb structure of the type honeycomb 31 fixed on another skin or composite shell 37 already polymerized as for example in RTM, and the two edges of the skin 13a, 13b are spliced onto or inside this assembly 35, as this is shown in Figures 13a and 13b appended hereto.

In this embodiment, the assembly 35 constitutes a monobloc housing on which the composite skin obtained by the above process is reported by gluing.

Claims

1. A method of manufacturing a composite shell skin comprising the following successive steps to:

draping (3) fabric folds, either pre-impregnated or dry, on a mold (1), said shell mold having a bulge preventing demolding of the composite skin by axial sliding of said skin on said mold,

- provide a separation line (17) defining two edges (13a, 13b) on the draping thus obtained,

post-impregnating this resin draping if the deposited fabric is dry,

- cook this resin,

- remove the skin thus obtained from the mold (1) thanks to the separating line,

- Splint the two edges (13a, 13b) of the skin.

2. Method according to claim 1, wherein said separation line is made by means of a groove (7) formed in said mold (1) forming a ferrule, into which a cutting tool (9) is introduced before the arrival of the resin.

3. Method according to claim 2, wherein is placed a strip (1 1) in said groove (7) prior to the impregnation of the folds by the resin.

4. Method according to claim 1, wherein said line of separation is made with at least one fixed strip (1 1) integral with said shell mold (1), against which abut two edges of the draping folds (3). .

5. Method according to claim 4, wherein is placed a cover-ruler (15) on said strip (1 1) prior to the impregnation of the folds with the resin if it is dry fabric used in version "infusion ".

6. A method according to claim 1, wherein said separation line (17) is made by a single ply of draping folds in its thickness, possibly with a cut in full thickness su ivie cuts (1 7a, 1 7b, 17c, 1 7d) in only one part of the thickness of the draping (3), making it possible to obtain stepped edges.

7. The method of claim 1, wherein said separation line is made by overlapping two edges of the draping (3).

8. A method according to claim 7, wherein a separator (19) is placed between the two edges (13a, 13b) of the draping (3) adjacent to the separation line prior to the impregnation of the folds with the resin if it is dry fabric used in "infusion" version.

9. The method of claim 1, wherein said separation line is formed by covering an imprint (23) formed on the shell mold (1).

10. The method of claim 1, wherein said dividing line is formed by draping the folds on a shell mold (1) of dimensions greater than those of the final piece, to obtain an open skin, and one factory the two edges of this draping adjacent to the separation line after firing the resin.

11. A method according to any one of the preceding claims, wherein said separation line is made in a direction selected from the group comprising the longitudinal direction, the transverse direction, and any intermediate position between these two positions.

12. Method according to any one of the preceding claims, wherein said draping (3) is impregnated with resin if it is dry fabric used in "infusion" version by means of a bladder (14) that is applied. on this drapery against the mold forming ferrule (1), and that is put under vacuum.

13. A method according to any one of the preceding claims, wherein the splicing (29) of the two edges of the skin is performed on or inside a key tool (27).

14. The method of claim 13, wherein there is reported on said skin lined disposed on or inside said key tool (27), a honeycomb-like honeycomb structure (31).

15. Method according to any one of claims 1 to 12, wherein said composite skin is glued inside or outside of a set (35) formed of a honeycomb honeycomb structure. (31) fixed on another skin or composite shell (37) already polymerized, and the two edges (13a, 13b) of the skin are spliced onto or within this assembly (35).