METHOD FOR JOINING A FUSELAGE BY WELDING WITH IMPROVED FLEXIBILITY, FUSELAGE AND AIRCRAFT SO LAST OBTAINED

Description

[0001] The present invention relates to the field of aircraft fuselage assembly. In particular, it relates to the assembly of fuselage panels to form fuselage portions and in particular fuselage sections as well as the assembly between these formed sections. The present invention also relates to the fuselage portion, the fuselage section and the aircraft thus obtained.

[0002] As shown on the figures 1 et 2 , the fuselage 2 of an aircraft 4 comprises several fuselage sections 6, 8 butted against each other and assembled together along circumferential junction lines 5 defining planes perpendicular to the longitudinal axis of the aircraft. Each section 6, 8 is itself obtained by assembling fuselage panels 10, 12, 14, 16 along longitudinal junction lines 17A and 17B.

[0003] As illustrated in the figure 2 , the method of assembling an aircraft fuselage 2 comprises a longitudinal joining step and the welding assembly technique is studied to carry it out. Thus at least two panels 10, 12 are positioned contiguously and assembled by edge-to-edge welding along a joining line 17A of the panels 10 and 12 to form a section 6 (of which only the two panels 10, 12 are shown on the figure 2 ). The term longitudinal refers to the longitudinal X direction of the aircraft 4. The section 6 thus formed is positioned contiguously with another section 8 and the sections 6 and 8 are assembled together in a more conventional manner, namely using fasteners 19, for example of the rivet type. Welding from one end to the other longitudinally between two panels deprives the fuselage of any flexibility. However, during assembly, flexibility of the junction is necessary to adjust the sections together. Longitudinal welding between two panels positioned contiguously is described in patent US2009 / 283509. In patent US2010 / 044514, the assembly of two shells at the transverse seam having stiffeners of different shapes is described. Document DE102008041172 presents the assembly of two components at a transverse seam, varying the thickness of the components assembled at the seam.

[0004] The present invention aims to propose a welding assembly method making it possible to improve its flexibility.

[0005] To this end, the present invention relates to a method of assembling aircraft fuselage panels, panels being butted along longitudinal joining lines and fixed to each other by their longitudinal edges by welding, characterized in that the longitudinal ends of their welded edges are not connected to each other and in that longitudinal ferrules are fixed so as to partially cover the concave surface of the panels at least partially at the level of said ends.

[0006] In this way, the assembly process ensures a certain flexibility to the fuselage once the panels are fixed to each other.

[0007] The invention provides at least one of the following optional features, taken alone or in combination.

[0008] The panels are welded to each other along their entire length L and the longitudinal ends of the welded edges are unwelded.

[0009] The welding operation is carried out only on the part of the edges to be joined and not at the ends.

[0010] The longitudinal ferrules at least partially cover the unwelded ends of the edges and a portion of the welded edges over a length allowing at least one fastener to be installed to fix the ferrules to the panels.

[0011] The length of the unwelded ends is less than the inter-frame distance.

[0012] The panels, once assembled, form a section, and the sections are assembled two by two using a circumferential ferrule which spans the longitudinal ferrules.

[0013] The panels, once assembled, form a section, and the sections are assembled two by two using a circumferential ferrule which adjoins the longitudinal ferrules to which they are connected by means of a fishplate.

[0014] The present invention also relates to a fuselage portion comprising at least two panels connected along longitudinal junction lines by their longitudinal edges welded together, characterized in that the longitudinal ends of their welded edges are not connected together, longitudinal ferrules being fixed so as to partially cover the concave surface of the panels at least partially at the level of said ends.

[0015] The invention provides the following optional feature, taken alone or in combination.

[0016] The longitudinal ferrules at least partially cover the unwelded ends of the edges and a portion of the welded edges over a length allowing at least one fastener to be installed to fix the ferrules to the panels.

[0017] The present invention also relates to an aircraft comprising fuselage portions having at least one of the optional characteristics presented above, taken individually or in combination, characterized in that each fuselage portion forms a section and in that the sections are assembled two by two using a circumferential ferrule.

[0018] Other aims, characteristics and advantages will emerge from the description of the invention which follows, a description given by way of non-limiting example only, with reference to the attached drawings in which: [ Fig. 1 ] is a perspective view of an aircraft according to the present invention; [ Fig. 2 ] is a schematic view of the assembly of fuselage panels using in particular the welding technique; [ Fig. 3 ] is a schematic view of two fuselage panels assembled along a longitudinal junction line by welding, the longitudinal ends of the edges of the welded panels not being connected according to the present invention, the stiffening frames of said panels being shown to materialize the inter-frame distance at the level of the panels of the illustrated section; [ Fig. 4 ] is the same view as the figure 3 in which the unbonded ends have been covered by a longitudinal ferrule; [ Fig. 5 ] is the same view as the figure 4 in which two panels of the same section are positioned contiguously with the two panels of the section represented on the figure 4 forming a circumferential joining line covered by a circumferential ferrule; [ Fig. 6 ] is the same view as the figure 5 in which fasteners are placed on the circumferential ferrule, in particular at the level of the longitudinal ferrule; [ Fig. 7 ] is the same view as the figure 5 but representing a variant in which the ferrules are joined by means of a splint. Fig. 8 ] is the same view as the figure 7 but with a different shape of splint.

[0019] The following description refers to an orthonormal X, Y, Z coordinate system (visible on the figure 1 ) in which the horizontal directions X, Y and vertical Z are defined with reference to an aircraft placed on horizontal ground. The three directions X, Y, Z are orthogonal to each other. The fuselage of the aircraft extends along a longitudinal direction X, a direction parallel to the roll axis. The Y direction corresponds to the direction oriented transversely and horizontally with respect to the longitudinal direction X, a direction parallel to the pitch axis. The Z direction corresponds to the vertical direction or height parallel to the yaw axis. To qualify as longitudinal respectively transverse, vertical means parallel to the longitudinal, respectively transverse, vertical direction. Concerning the fuselage panels, in the illustrated embodiments, the panels are rectangular: the term longitudinal therefore also qualifies here the direction of the longest edges of the panel, those intended to come in the longitudinal direction of the aircraft.However, it is possible to have embodiments in which the shorter edges of the rectangular panels are in the longitudinal direction or panels which are not rectangular and have at least one at least partially rectilinear edge which extends in the longitudinal direction. The edge of the at least partially rectilinear panel lying in the longitudinal direction is the edge intended to be joined with an edge of an adjacent panel at the circumferential level. The outer surface of the fuselage is oriented towards the air outside the aircraft as opposed to the inner surface of the fuselage oriented towards the interior of the fuselage, namely towards the cockpit, the cabin or the like. Since the panels are curved, the inner surface also corresponds to the concave surface of the panel and the outer surface to the convex surface thereof.

[0020] As shown in the figure 3 , the assembly method according to the present invention comprises a first step consisting of assembling together by welding two facing panels 26, 28 joined longitudinally without overlapping each other so as to ensure the junction and the continuity of the transfer of the flows along the panels. The panels 26, 28 thus assembled form a portion 27 of panels. A portion 27 of fuselage corresponds to the assembly of at least two panels 26, 28. The panels are joined along a line 29 called the longitudinal junction line. The assembled panels 26, 28 form a continuous whole without any separation of surfaces. Only the assembly of two panels is described because the assembly along longitudinal junction lines is the same for all the panels forming the same section.The panels 26, 28 are positioned contiguously so as to weld their adjoining longitudinal edges 30, 32 without the longitudinal ends 30A, 30B, 32A, 32B of these edges being connected to each other. The panels 26, 28 are shown in a simplified manner. They are curved so that once several panels are assembled as explained above, they form between them a section whose shape can be varied: it can be a cylindrical shape or a more complex one, for example with several lobes, or even a shape whose section has an evolving contour in the longitudinal direction, such as that of the front tip or the tail of an aircraft or other.

[0021] According to a first embodiment, the panels are assembled longitudinally by welding over their entire length L. Length L is understood to mean the largest dimension of the panel extending parallel to the direction X in the case of the rectangular panels illustrated. According to an additional step, the longitudinal ends 30A, 30B, 32A, 32B of the edges 30, 32 of the panels are unwelded by any type of means and for example by cutting. According to a second embodiment, the welding is not carried out longitudinally over the entire length L of the panel: the longitudinal ends 30A, 30B, 32A, 32B of the edges 30, 32 of the panels are not assembled together. According to one embodiment of the two embodiments presented, the length of each unwelded end 30A, 30B, 32A, 32B is determined by the need for flexibility of the section during assembly.According to one possible form, the length of each unwelded end does not exceed the inter-frame distance I illustrated in the . figure 3 . As a reminder, a fuselage section comprises a skin 35, for example made of composite material, stiffened by circumferential stiffeners 37 referred to as a frame. The inter-frame distance I corresponds to the distance between two frames located at the level of the panel concerned or, if there is only one frame at the level of said panel, the distance between the frame located at the level of the panel and the nearest frame located at the level of an adjacent panel in the longitudinal direction.

[0022] The second step of the assembly process shown in the figure 4 consists of placing a longitudinal ferrule 38, 40, namely a plate 42, 44, on the inner surface (concave surface) of the fuselage in such a way that it partially covers each of said two panels 26, 28 at the ends 30A, 30B, 32A, 32B not connected to each other and slightly beyond. The ferrule 38, 40 is placed after the adjacent section 48 has been positioned ( figure 5 ) on the side of the ferrule 38 concerned but could be made before. The plate 42, 44 is made for example from an aluminum-based alloy but any other material is possible. Its length is such that the ferrule 38, 40 covers the edges 30, 32 of the panels 26, 28 over the entire length of the unbonded ends 30A, 30B, 32A, 32B and extends beyond to allow the installation of at least one fixing 46 of the plate 42, 44 with the panels 26, 28 in the X direction at the welded edges 30, 32; in the illustrated embodiment, two fixings 46 are provided on either side of the longitudinal junction line, namely 4 fixings 46 for the plate 42 at the welded edges only. The fixings 46 can be arranged in at least one row. The fasteners 46 are of a known type, for example of the rivet type. The width of the ferrule is such that it allows the installation of fasteners 46 in the Y direction.The thickness of the ferrule results from dimensioning calculations which take into account the material used. Fasteners 46 are provided to fix the ferrule 38, 40 to the panels 26, 28 at the welded edges as seen above but also at a portion of the ends 30A, 30B, 32A, 32B of the non-welded edges. At least one row of fasteners 46 is provided to fix the plate 42, 44 to the panel 26 and at least one row of fasteners opposite it with respect to the longitudinal junction line 29 to fix the plate 42, 44 to the panel 28. According to the form illustrated, the rows of fasteners 46 are parallel to each other and the fasteners 46 are positioned equidistantly but any other positioning is possible. No fixing is provided on the longitudinally most extreme zone of the shell 38, 40 and closest to the adjacent section 48.The area without fixing is intended, as will be seen later, to be covered by a circumferential ferrule 50 placed at the level of the circumferential junction line 52.

[0023] The third step of the assembly process shown in the figure 5 comprises the assembly of the section 54 formed as described above with an adjacent section, here the section 48. The sections 48, 54 are positioned opposite each other, butted so as to be in extension of one another. The shell 50, namely a plate 56, is placed on the inner surface (concave surface) of the fuselage at the circumferential junction line 52 so that it partially covers each of said two panels 26, 28 and the panels 58 of the adjacent section 48. The panels 58 of the section 48 have not been distinguished for the sake of simplification. The circumferential shell 50 spans the longitudinal shell 38 by superimposing itself on it.

[0024] As shown in the figure 6 , the ferrule 50 is assembled to the panels 26, 28, 58 using fasteners 60 of known type such as rivets. Fasteners 60 are provided at the level of the superposition of the ferrules 38, 50.

[0025] The present invention also relates to portions 27 ( figure 3 ) of fuselage thus formed, the fuselage section 48, 54 as well as the aircraft 2 coming from the assembly of such sections.

[0026] As shown in the figure 3 , a fuselage portion 27 comprises at least two panels 26, 28 assembled together by their longitudinal edges 30, 32 joined by welding without their longitudinal ends 30A, 30B, 32A, 32B being connected together. The panels 26, 28 are positioned facing each other, joined longitudinally without overlapping each other so as to ensure the junction and the continuity of the transfer of the flows along the panels. The fuselage section corresponds to a fuselage portion 27 of which all the panels 26, 28 are assembled at longitudinal junction lines 29 forming a cylindrical surface or a more complex curvature such as for example with several lobes or even a shape whose section has an evolving contour in the longitudinal direction such as that of the front tip or the tail of an aircraft (the panels then not being of rectangular shape) or other.The assembled panels form a continuous whole without any separation of surfaces either on their inner (concave) or outer (convex) surfaces. To form a fuselage section, the panels are curved so that once several panels are assembled in this way, they form a section between them.A ferrule 38, 40, namely a plate 42, 44, partially covers each of said two panels 26, 28 on their inner (concave) surface at the ends 30A, 30B, 32A, 32B not connected to each other and beyond: its length is such that the ferrule 38, 40 covers the edges 30, 32 of the panels 26, 28 over the entire length of the ends 30A, 30B, 32A, 32B not connected and extends beyond to allow the installation of at least one fixing 46 of the plate 42, 44 with the panels 26, 28 in the direction X at the welded edges 30, 32; in the illustrated embodiment, two fasteners 46 are provided on either side of the longitudinal junction line, namely 4 fasteners 46 for the plate 40 at the welded edges only.At least one row of fasteners 46 is provided for fixing the plate 42, 44 to the panel 26 and at least one row of fasteners opposite the latter with respect to the longitudinal junction line 29 for fixing the plate 42, 44 to the panel 28. According to the form illustrated, the rows of fasteners are parallel to each other and the fasteners are positioned equidistantly but any other positioning is possible. No fastener is provided on the longitudinally most extreme zone of the shell 38, 40 and closest to the adjacent section 48. The fuselage section is formed from a set of panels thus assembled.

[0027] The aircraft comprises a set of such sections positioned opposite each other and abutted so as to be in extension of each other. The circumferential ferrule 50, namely a plate 56, is placed on the inner surface of the fuselage at each of the circumferential junction lines 52 so that it partially covers the contiguous panels of two adjacent sections. According to an embodiment illustrated in the figure 6 , the circumferential ferrule 50 spans the longitudinal ferrules 38 by superimposing itself on it. The circumferential ferrule 50 is assembled to the panels 26, 28, 58 as well as to the longitudinal ferrules using fasteners 60 of known type such as rivets. The ferrule 50 can be made in one piece or in several parts.

[0028] According to another embodiment illustrated in the figures 7 And 8, the circumferential ferrule 50 and the longitudinal ferrules 38 are joined by means of at least one fishplate 39.

[0029] In the embodiment of the figure 7 , the fishplate 39 is rectangular in shape. It is shown with a greater width but it could be the same width as the ferrule 38. The fishplate allows the junction between the longitudinal ferrule and the circumferential ferrule which adjoin (i.e. which are contiguous) but do not overlap. The fishplate 39 may have shapes different from the rectangular one illustrated.

[0030] In the embodiment shown in the figure 8 , the fishplate 39 has a T shape having two branches 62, 64 in one piece, the branch 62 called longitudinal being the one linked to the center of the branch 64 called circumferential. The circumferential branch 64 has the same width as that of the circumferential ferrule 50. The longitudinal branch 62 has a width at least equal to that of the longitudinal ferrule 38.

[0031] Whether in the form of realization of the figure 7 or that of the figure 8, the circumferential ferrule 50 is assembled to the panels 26, 28, 58 as well as to the intermediate fishplate 39 using fasteners 60 of known type such as rivets. The fasteners 60 are arranged in at least one circumferential row on either side of the junction 52, parallel to each other. Similarly, the longitudinal ferrule 38 is assembled to the panels 26, 28 as well as to the intermediate fishplate 39 using fasteners 60 of known type such as rivets. The ferrule 50 can be made in a single piece or in several parts. The fasteners 60 are arranged in at least one longitudinal row on either side of the longitudinal junction 29, parallel to each other. The fasteners 60 are distributed at equal distances but any other arrangement is possible.

Claims

1. Method for assembling aircraft fuselage panels (26, 28, 58), panels (26, 28) being butted together along longitudinal joining lines (29) and fixed to one another via their longitudinal edges (30, 32) by welding, characterized in that the longitudinal ends (30A, 30B, 32A, 32B) of their welded edges (30, 32) are not connected to one another and in that longitudinal hoops (38, 40) are fixed in such a way as to partially cover the concave surface of the panels (26, 28) at least partially at said ends (30A, 30B, 32A, 32B).

2. Method of assembly according to Claim 1, characterized in that the panels (26, 28) are welded to one another along their entire length L and in that the longitudinal ends (30A, 30B, 32A, 32B) of the welded edges are unwelded.

3. Method of assembly according to Claim 1, characterized in that the welding operation is performed over only part of the edges (30, 32) that are to be connected and not at the ends (30A, 30B, 32A, 32B).

4. Method of assembly according to one of Claims 1 to 3, characterized in that the longitudinal hoops at least partially cover the unwelded ends of the edges (30, 32) and part of the welded edges over a length that allows the fitting of at least one fixing (46) for fixing the hoops to the panels (26, 28).

5. Method of assembly according to one of Claims 1 to 4, characterized in that the length of the unwelded ends is less than the inter-frame distance.

6. Method of assembly according to one of Claims 1 to 5, characterized in that, once assembled, the panels (26, 28) form a section, and the sections are assembled in pairs using a circumferential hoop (50) which straddles the longitudinal hoops (38, 40).

7. Method of assembly according to one of Claims 1 to 5, characterized in that, once assembled, the panels (26, 28) form a section, and the sections are assembled in pairs using a circumferential hoop (50) which adjoins the longitudinal hoops (38, 40) to which they are connected using a fishplate (39).

8. Fuselage portion comprising at least two panels which are connected along longitudinal joining lines (29) by their longitudinal edges (30, 32) which are welded together, characterized in that the longitudinal ends (30A, 30B, 32A, 32B) of their welded edges (30, 32) are not connected to one another and in that longitudinal hoops (38, 40) are fixed in such a way as to partially cover the concave surface of the panels (26, 28) at least partially at said ends (30A, 30B, 32A, 32B).

9. Fuselage portion according to Claim 8, characterized in that the longitudinal hoops (38, 40) at least partially cover the unwelded ends of the edges (30, 32) and part of the welded edges over a length that allows the fitting of at least one fixing (46) for fixing the hoops to the panels (26, 28).

10. Aircraft comprising fuselage portions according to Claim 9, characterized in that each fuselage portion (27) forms a section and in that the sections are assembled in pairs using a circumferential hoop (50).