METHOD FOR MANUFACTURING AN AIRCRAFT WINDOW FRAME WITH A BARRIER LAYER, WINDOW FRAME MANUFACTURED BY THIS METHOD AND AIRCRAFT WITH AT LEAST SUCH A WINDOW FRAME

Description

[0001] This application relates to a method for manufacturing an aircraft window frame comprising a barrier layer, to a window frame obtained from said method and to an aircraft comprising at least one such window frame.

[0002] According to a method of embodiment of the earlier art visible on the figures 1 et 2 , the fuselage 10 of an aircraft includes a wall 12 having an outer face 12.1 and an inner face 12.2 as well as a plurality of portholes 14.

[0003] At the right of each porthole 14, the wall 12 includes an opening 16 delimited by an edge 16.1 connecting the outer and inner faces 12.1, 12.2. As illustrated on the figure 3 , each porthole 14 includes a frame 18 supporting two transparent walls 20, 20' and a peripheral seal 22. The frame 18 includes a first frame 18.1 connected to the wall 12 and a second frame 18.2 connected to the first frame 18.1 by connecting elements 18.3, the transparent walls 20, 20' and the peripheral seal 22 being interposed between the first and second frames 18.1, 18.2.

[0004] The first frame 18.1 comprises a first part 26 positioned in the opening 16, a second part 28 pressed against the inner face 12.2 of the fuselage wall 12, an intermediate part 30 connecting the first and second parts 26 and 28, and a third part 32 connected to the second part 28 and substantially perpendicular to it, the second frame 18.2 bearing against the third part 28. In one configuration, the intermediate part 30 is located at one end of the second part 28, and the third part 32 is located at one end of the second part 28 and forms an L with it. Once the frame 18 is mounted, the first part 26 has an outer face 26.1 flush with the outer face 12.1 of the fuselage wall 12 and an inner face 26.2 substantially parallel to the outer face 26.1. The second part 28 comprises an outer face 28.1 pressed against the inner face 12.2 of the fuselage wall 12, offset inwards relative to the outer face 26.1 of the first part 26, and an inner face 28.2 substantially parallel to the outer face 28.1. The intermediate part 30 has an outer face 30.1 connecting the outer faces 26.1, 28.1 of the first and second parts 26, 28 and an inner face 30.2 connecting the inner faces 26.2, 28.2 of the first and second parts 26, 28.

[0005] Thus, the first section 18.1 includes: a first surface S1 composed of the outer faces 26.1, 28.1, 30.1 of the first and second parts 26, 28 as well as the intermediate part 30, a second surface S2 composed of the inner faces 26.2, 28.2, 30.2 of the first and second parts 26, 28 as well as the intermediate part 30.

[0006] Geometrically, the junction zone 33, connecting the outer faces 26.1, 30.1 of the first part 26 and the intermediate part 30, has a strong curvature so that the outer face 30.1 of the intermediate part 30 is substantially parallel to the edge 16.1 of the opening 16 and is slightly spaced from said edge 16.1. This geometry helps to limit aerodynamic disturbances.

[0007] According to one embodiment, the first frame 18.1 is made in one piece, of composite material, and includes reinforcing fibers embedded in a resin matrix.

[0008] As illustrated on the figures 4 et 5 The first frame 18.1 comprises layers of fibers 34, 34', 34", reinforcements 36, a layer of conductive material 38, and seams 40 to hold the layers 34, 38, and reinforcements 36 together. For example, the layer of conductive material 38 is a copper mesh and provides a lightning protection layer.

[0009] According to an embodiment visible on the figure 5 The first frame 18.1 includes, starting from the first surface S1: a layer of conductive material 38 which extends over the outer face 26.1 of the first part 26 and extends into the junction zone 33 with high curvature, two layers of fibers 34, 34' which extend over the outer faces 28.1, 30.1 of the second part 28 and of the intermediate part 30 as well as into the junction zone 33 with high curvature, a reinforcement 36 with a D-shaped section positioned at the junction zone 33 with high curvature.

[0010] Generally, the first frame 18.1 includes further layers of 34" fibers, with the reinforcement 36 sandwiched between the 34', 34" fiber layers.

[0011] As illustrated on the figure 5 , the seams 40 connect at least the first and second layers of fibers 34, 34' as well as the reinforcement 36 and are positioned at the level of the first and second parts 26, 28 as well as the intermediate part 30.

[0012] After the seams 40 are in place, the assembly of the fiber layers 34, the reinforcements 36, and the conductive material layer 38 is consolidated or polymerized. During this consolidation or polymerization step, the fibers of the different fiber layers 34, 34' are embedded in a thermosetting resin using a resin transfer molding process.

[0013] At the end of the consolidation or polymerization stage, the first frame 18.1 presents, at the level of the first surface S1, areas of resin accumulation at the seams 40 as well as at the level of the junction area 33 with a high curvature due to the presence of the reinforcement 36 with a D-shaped section. Thus, due to these localized excesses of resin, the outer face 26.1 of the first part 26 of the first frame 18.1 does not have a homogeneous behavior, particularly at the level of the junction area 33 with a high curvature.

[0014] After the aircraft has been assembled and in particular after the windows 14 have been fitted, the outer face 12.1 of the fuselage wall 12 is covered with at least one layer of paint which also covers the outer face 26.1 of the first part 26 of the first frame 18.1 of each window 14.

[0015] Because the outer face 26.1 of the first part 26 of the first frame 18.1 does not behave homogeneously, this can cause a visual change in the painting.

[0016] US2012 / 119031 A1 describes a porthole frame comprising several layers of fibers embedded in a resin matrix, with a barrier layer positioned on one part of one face of the frame. This solution is unsatisfactory because one of the faces is not homogeneous.

[0017] US8096506 B2 describes a porthole frame comprising several preforms or layers of fibers embedded in a resin matrix. This solution does not allow for the production of homogeneous surfaces.

[0018] The present invention aims to remedy all or part of the drawbacks of the prior art.

[0019] To this end, the invention relates to a method for manufacturing an aircraft window frame, said frame comprising a first surface having at least first and second faces extending around the entire perimeter of the frame and connected by a curved junction zone, said frame being made of a composite material comprising fibers embedded in a resin matrix. This manufacturing method includes a step of assembling layers of fibers and at least one reinforcement located at the junction zone and having first and second peripheral edges, a step of consolidating or polymerizing the assembly, and a step of demolding the frame.

[0020] According to the invention, during the assembly stage, a barrier layer is positioned between the reinforcement and the first surface so as to cover the reinforcement and form a barrier limiting the spread of resin towards the first surface.

[0021] The presence of this barrier layer prevents the resin from spreading to the first surface and the formation of localized areas of resin accumulation. As a result, the outer surface of the frame behaves more uniformly and does not cause any visual changes to the paintwork.

[0022] Depending on other characteristics taken individually or in combination: During the assembly step, the barrier layer is positioned in contact with the reinforcement; the barrier layer does not extend beyond the first and second peripheral edges of the reinforcement; at least one seam is made so as to connect at least the reinforcement and the barrier layer, the seam comprising stitches offset from the first surface at least at the level of the first and second faces; the process includes a step of sprinkling a resin between the layers of fibers and heating to a temperature below a polymerization or consolidation temperature to activate the tackiness of the resin in order to keep the different layers bonded together before the consolidation or polymerization step.

[0023] The invention also relates to an aircraft window frame comprising a first surface which has at least first and second faces, extending mainly around the perimeter of the frame, connected by a curved junction zone, said frame being made of a composite material which has fibers embedded in a resin matrix, said frame comprising a stack of fiber layers as well as at least one reinforcement located at the junction zone and having first and second peripheral edges.

[0024] According to the invention, the frame includes at least one barrier layer covering the reinforcement, positioned between the reinforcement and the first surface and configured to form a barrier limiting the propagation of the resin towards the first surface.

[0025] Depending on other characteristics taken individually or in combination: the barrier layer is in contact with the reinforcement; the barrier layer does not extend beyond the first and second peripheral edges of the reinforcement; the barrier layer includes at least one fiberglass ply; the frame includes at least one seam connecting at least the reinforcement and the barrier layer and having stitches spaced from the first surface.

[0026] The invention also relates to an aircraft comprising at least one window frame according to one of the preceding characteristics.

[0027] Other features and advantages will become apparent from the following description of the invention, given by way of example only, with reference to the accompanying drawings, among which: There figure 1 is a side view of an aircraft, The figure 2 is a front view through a porthole, The figure 3 is a cut along line III-III of the figure 2 of a porthole frame illustrating a method of realization of the earlier art, The figure 4 is a perspective view of part of an early porthole frame illustrating an early form of the art, The figure 5 is a schematic cross-section of a porthole frame illustrating a method of embodiment from the earlier art, The figure 6 is a cross-section of a porthole frame illustrating one embodiment of the invention. figure 7 is a schematic cross-section of a porthole frame illustrating one embodiment of the invention.

[0028] As illustrated on the figure 6 A fuselage wall 112 of an aircraft comprises an outer face 112.1, an inner face 112.2 opposite the outer face 112.1, and at least one window 114 positioned at an opening 116 delimited by an edge 116.1 connecting the outer and inner faces 112.1, 112.2. The window 114 comprises at least one transparent wall 120 and a frame 118 situated around the transparent wall 120 and configured to connect it to the fuselage wall 112. This frame 118 comprises first and second frames 118.1, 118.2 between which the transparent wall 120 of the window 118 is positioned.

[0029] The first frame 118.1 includes a first part 126 intended to be positioned in the opening 116 of the fuselage wall 112 and a second part 128 intended to be pressed against the inner face 112.2 of the fuselage wall 112.

[0030] When the frame 118 is positioned in an opening 116 in the fuselage wall 112, the first part 126 comprises an outer face 126.1 flush with the outer face 112.1 of the fuselage wall 112 and an inner face 126.2 opposite the outer face 126.1. The second part 128 comprises an outer face 128.1 pressed against the inner face 112.2 of the fuselage wall 112 and an inner face 128.2 opposite the outer face 128.1.

[0031] According to one configuration, the first and second parts 126, 128 are directly connected. According to this configuration, the first part 126 includes a lateral face 130 opposite the edge 116.1 of the opening 116 of the fuselage wall 112.

[0032] According to another configuration, the first frame 118.1 includes an intermediate part, connecting the first and second parts 126, 128, which has a lateral face 130, connecting the outer faces 126.1, 128.1 of the first and second parts 126, 128, configured to face the edge 116.1 of the opening 116 of the fuselage wall 112.

[0033] The first frame 118.1 may include other parts, such as a third part 131 connected to the second part 128 and substantially perpendicular to the latter, the second frame 118.2 of the frame 118 taking support against this third part 131 in operation.

[0034] According to these configurations, the first frame 118.1 includes a first surface S1, comprising at least the outer faces 126.1, 128.1 of the first and second parts 126, 128 as well as the lateral face 130, connecting the outer faces 126.1, 128.1, configured to face the edge 116.1 of the opening 116 of the fuselage wall 112.

[0035] Geometrically, the first surface S1 of the first frame 118.1 includes a junction zone 133, connecting the outer face 126.1 of the first part 126 and the lateral face 130, which has a strong curvature so that the lateral face 130 is substantially parallel to the edge 116.1 of the opening 116 of the fuselage wall 112 and is slightly spaced from said edge 116.1. This geometry helps to limit aerodynamic disturbances.

[0036] Regardless of the embodiment, a window 114 of a fuselage wall 112 of an aircraft includes at least one frame 118.1 having a first surface S1 which extends around the entire perimeter of the frame 118.1.

[0037] This first surface S1 has at least two faces, extending around the entire perimeter of the frame 118.1, connected by a curved junction zone 133 that also extends around the entire perimeter of the frame 11.1. The first surface S1 may include other faces. The first face corresponds to the outer face 126.1 of the first part 126 of the frame 118.1. It is substantially flat and visible from outside the aircraft when the window 114 is positioned in the opening 116 of the fuselage wall 112. When the frame 118.1 is positioned at an opening 116 of the fuselage wall 112, the first face 126.1 is flush with the outer face 112.1 of the fuselage wall 112. The second face corresponds to the lateral face 130. It is substantially perpendicular to the first face 126.1. The junction zone 133 exhibits a strong curvature.

[0038] According to one embodiment, the frame 118.1 is made in one piece from a composite material and comprises fibers embedded in a resin matrix. Preferably, the resin is a thermosetting resin.

[0039] As illustrated on the figure 7 , the frame 118.1 includes layers of fibers 132, 134 as well as at least one reinforcement 136 located at the junction area 133.

[0040] This reinforcement 136 extends around the entire perimeter of the frame 118.1 and has a D-shaped cross-section. It extends between the first and second peripheral edges 136.1, 136.2. This reinforcement 136 may be in the form of a preform of pre-impregnated or unpre-impregnated fibers. It is not described further because it may be identical to that of the prior art.

[0041] The 118.1 framework may include other reinforcements.

[0042] According to one embodiment, frame 118.1 comprises, starting from the first surface S1: a first layer 132 of dry fibers at the level of the first surface S1, which extends over the entire first surface S1, intermediate layers 134 of dry fibers positioned under the first layer 132, which extend over the entire first surface S1, a reinforcement 136 with a D-shaped section, positioned at the level of the junction area 133 with high curvature.

[0043] Generally, the 118.1 frame comprises 134' inner layers of dry fibers, with the 136 reinforcement sandwiched between the intermediate and inner layers 134, 134'.

[0044] According to a simplified variant, the frame 118.1 does not include any intermediate layer 134 between the first layer 132 and the reinforcement 136. According to one configuration, the frame 118.1 includes a single intermediate layer 134 between the first layer 132 and the reinforcement 136.

[0045] The first layer 132 covers the reinforcement 136 and extends on either side of the latter, beyond the first and second peripheral edges 136.1, 136.2. Depending on one configuration, the first layer 132 covers the entire first face corresponding to the outer face 126.1 of the first part 126. It can also cover the entire second face corresponding to the lateral face 130.

[0046] The intermediate layers 134 cover the reinforcement 136 and extend on either side of it, beyond the first and second peripheral edges 136.1, 136.2. According to one configuration, the intermediate layers 134 cover the entire first face corresponding to the outer face 126.1 of the first part 126. They can also cover the entire second face corresponding to the lateral face 130.

[0047] The fibers of the different layers 132, 134, 134' are made of carbon. Of course, the invention is not limited to this material.

[0048] The different layers 132, 134, 134' can be woven or non-woven layers.

[0049] The different layers 132, 134, 134' have fibers that can be oriented in the same way or in different ways.

[0050] According to one feature, the frame 118.1 includes at least one barrier layer 138 covering the reinforcement 136, sandwiched between the reinforcement 136 and the first surface S1, and configured to limit the spread of resin from the reinforcement 136 to the first surface S1. The presence of this barrier layer 138 prevents, at the junction zone 133, the spread of resin to the first surface S1 and the formation of localized areas of resin accumulation. Thus, the outer surface S1 of the frame 118.1 exhibits more uniform behavior and does not cause any visual changes to the paintwork.

[0051] Depending on one configuration, the 118.1 frame comprises a single 138 barrier layer.

[0052] According to an arrangement, the barrier layer 138 is in contact with the reinforcement 136. It is sandwiched between the reinforcement 136 and the intermediate layers 134.

[0053] In a non-limiting configuration, the barrier layer 138 extends from the first peripheral edge 136.1 of the reinforcement 136 to its second peripheral edge 136.2. It does not extend beyond the first and second peripheral edges 136.1, 136.2 of the reinforcement 136. In one embodiment, the barrier layer 138 comprises at least one ply of glass fibers. Of course, the invention is not limited to this material.

[0054] Depending on one configuration, the barrier layer 138 is a woven ply that has reduced meshes limiting the spread of resin through the barrier layer 138.

[0055] According to one embodiment, the frame 118.1 includes at least one first seam 140 connecting at least the reinforcement 136 and at least some layers, such as the barrier layer 138, the first seam 140 having a set of stitches not passing through any layer of fibers 132, 134 present between the reinforcement 136 and the first surface S1 at least at the level of the first face (corresponding to the outer face 126.1 of the first part 126) and the junction area 133. Regardless of the embodiment, the stitches of the first seam 140 do not reach the first surface S1 and are offset from the latter so as not to be visible from the first surface S1 at least at the level of the first face 126.1 and the junction area 133.

[0056] The fact that the stitches of the first seam 140 are offset from (and at a distance from) the first surface S1, at the junction zone 133 and the first face, prevents resin from reaching the first layer 132 by migrating along the threads of the first seam 140. This arrangement limits the propagation of resin migration towards the first surface S1 and the formation of localized areas of resin accumulation. Thus, the first surface S1 of the frame 118.1, at least at the first face and the junction zone, exhibits more homogeneous behavior and does not cause any visual alterations to the paintwork.

[0057] According to an embodiment visible on the figure 7, the frame 118.1 includes at least one second seam 142 offset from the junction area 133, from the first face corresponding to the outer face 126.1 of the first part 126 and preferably from the second face corresponding to the lateral face 130. This second seam 142 may include through stitches (which pass through all the layers of fibers 132, 134, 134') and visible from the first surface S1.

[0058] Unlike the prior art, the frame 118.1 does not include any layer of conductive material covering the first layer of dry fibers 132 at least at the first and second faces (corresponding to the outer face 126.1 of the first part 126 and the side face 130) and the junction area 133. Thus, the surface S1 has a homogeneous appearance at the right of these areas.

[0059] The method for manufacturing the frame 118.1 includes an assembly step of the various layers 132, 134, 134', the reinforcement 136, and the barrier layer 138 by overlapping them. During this assembly step, at least one barrier layer 138 is positioned between the reinforcement 136 and the first surface S1 so as to cover the reinforcement 136 and form a barrier limiting the spread of resin towards the first surface S1. During the assembly step, at least one first seam 140 may be made to join the assembled reinforcement 136 and barrier layer 138. This first seam 140 includes stitches that are not visible from the first surface S1 and are located away from it in order to limit the spread of resin towards the first surface S1.Alternatively, to keep the different layers 132, 134, 134' bonded together before they are polymerized or consolidated, the process includes a step of sprinkling a resin between the layers and heating them to a temperature, on the order of 80°C, lower than the polymerization or consolidation temperature to activate the resin's tackiness. Thus, it is no longer necessary to provide seams.

[0060] The process then includes a resin consolidation or polymerization step. The assembly of the various layers 132, 134, 134', the reinforcement 136, and the barrier layer 138 is positioned on a mold and covered with at least one flexible, airtight envelope that is hermetically sealed to the mold all around the assembly. During the consolidation or polymerization step, the assembly is subjected to a cycle of pressures and temperatures. In one method, the various layers 132, 134, 134' are dry and not pre-impregnated. In this case, during the consolidation or polymerization step, the fibers of the various layers 132, 134, 134' are embedded in a thermosetting resin in a resin transfer molding process.

[0061] Following this consolidation or polymerization step, the process includes a demolding step of the hardened frame 118.1.

Claims

1. Method of manufacturing an aircraft window frame (118.1), said frame having a first surface (S1) that has at least first and second faces (126.1, 130) extending all around the frame and connected by a curved junction zone (133), said frame (118.1) being made of a composite material that includes fibers embedded in a resin matrix, the method of manufacture including a step of assembling fiber layers (132, 134, 134') and at least one reinforcement (136) situated at the level of the junction zone (133) and having first and second peripheral edges (136.1, 136.2), a step of consolidation or polymerization of the assembly, and a step of removing the frame from the mold; characterized in that during the assembly step a barrier layer (138) is positioned between the reinforcement (136) and the first surface (S1) in such a manner as to cover the reinforcement (136) and to form a barrier limiting propagation of resin in the direction of the first surface (S1).

2. Method as claimed in claim 1 of manufacturing an aircraft window frame characterized in that during the assembly step the barrier layer (138) is positioned in contact with the reinforcement (136).

3. Method as claimed in either one of the preceding claims of manufacturing an aircraft window frame characterized in that the barrier layer (138) does not extend beyond first and second peripheral edges (136.1, 136.2) of the reinforcement (136).

4. Method as claimed in the preceding claim of manufacturing an aircraft window frame characterized in that during the assembly step at least one seam (140) is produced in such a manner as to connect at least the reinforcement (136) and the barrier layer (138), the seam (140) including stitching offset from the first surface (S1) at least at the level of the first and second faces (126.1, 130).

5. Method as claimed in any one of the preceding claims of manufacturing an aircraft window frame characterized in that the method includes a step of scattering a resin between the fiber layers (132, 134) and heating to a temperature below a polymerization or consolidation temperature to activate the tackiness of the resin in order to keep the various layers (132, 134) interconnected before the consolidation or polymerization step.

6. Aircraft window frame manufactured by the method as claimed in any one of the preceding claims, said frame including a first surface (S1) that has at least first and second faces (126.1, 130) extending all around the frame and connected by a curved junction zone (133), said frame (118.1) being made of a composite material that includes fibers embedded in a resin matrix, said frame (118.1) including a stack of layers (132, 134, 134') and at least one reinforcement (136) situated at the level of the junction zone (133) and having first and second peripheral edges (136.1, 136.2), characterized in that the frame (118.1) includes at least one barrier layer (138) covering the reinforcement (136), positioned between the reinforcement (136) and the first surface (S1) and configured to form a barrier limiting propagation of resin in the direction of the first surface (S1).

7. Aircraft window frame as claimed in the preceding claim characterized in that the barrier layer (138) is in contact with the reinforcement (136).

8. Aircraft window frame as claimed in either one of claims 6 or 7 characterized in that the barrier layer (138) does not extend beyond the first and second peripheral edges of the reinforcement (136).

9. Aircraft window frame as claimed in any one of claims 6 to 8 characterized in that the barrier layer (138) includes at least one ply of glass fibers.

10. Aircraft window frame as claimed in any one of claims 6 to 9 characterized in that the frame includes at least one seam (140) connecting at least the reinforcement (136) and the barrier layer (138) and including stitching spaced from the first surface (S1).

11. Aircraft window frame as claimed in any one of claims 6 to 10 characterized in that the frame includes at least one first layer (132) of fibers interleaved between the reinforcement (136) and the first surface (S1).

12. Aircraft including at least one window frame as claimed in any one of claims 6 to 11.