Method for producing part of an aircraft fuselage and tool for implementing said method

Abstract

The subject matter disclosed herein relates to a method for assembling at least one panel and frames for producing part of an aircraft fuselage, the method including shaping the panel on support surfaces of a tool, wherein it includes holding each frame clamped against at least one sliding support surface arranged in a transverse plane, the sliding support surfaces of the various frames and the support surfaces being secured to the same tool and positioned relative to one another, and in putting in place permanent attachment elements for connecting the panel and the frames. The subject matter disclosed herein also proposes a tool for implementing the assembly method.

Claims

1. A method for assembling at least one panel and frames, which are part of an aircraft fuselage, the method comprising: shaping the at least one panel on support surfaces of a tool, the support surfaces having at least one radius of curvature in a transverse plane, the frames following a reference line of curvature; holding each frame clamped against at least one sliding support surface arranged in a transverse plane, the sliding support surfaces and the support surfaces being secured to the same tool and positioned relative to one another; and putting in place permanent attachment elements for connecting the at least one panel to the frames.

2. The assembly method according to claim 1, comprising positioning each frame with respect to its sliding support surface after having shaped the panel.

3. The assembly method according to claim 2, comprising positioning each frame by immobilizing it along its line of curvature while allowing a translational movement in a radial direction.

4. The assembly method according to claim 3, wherein each frame is positioned with respect to a positioner arranged equidistant from the ends of the frame, and wherein the ends are subsequently unrolled so as to come into contact with the panel.

5. The assembly method according to claim 3, comprising using at least one brace for holding each frame clamped against the sliding support surface, the brace comprising a counter-support in contact with the frame which allows the frame to move in translation in the radial direction.

6. The assembly method according to claim 1, comprising using straps for holding the panel clamped against the support surfaces.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages will emerge from the following purely exemplary description of the subject matter disclosed herein, given with reference to the appended drawings, in which:

(2) FIG. 1A is a perspective view of part of an aircraft fuselage;

(3) FIG. 1B is a section through the plane P in FIG. 1A;

(4) FIG. 2A is a side view of a frame equipped with clips;

(5) FIG. 2B is a section through the line BB in FIG. 2A;

(6) FIG. 3 is a perspective view of a tool showing the subject matter disclosed herein before the placement of a panel;

(7) FIG. 4 is a perspective view of the tool shown in FIG. 3 after the placement of a panel and the frames;

(8) FIG. 5 is a section through a longitudinal plane of part of the tool shown in FIG. 3; and

(9) FIG. 6 is a front view of a positioner for positioning a frame, showing an embodiment of the subject matter disclosed herein.

DETAILED DESCRIPTION

(10) For the description, once assembled, the panel 30 extends over half a section of the fuselage and is semi-cylindrical with a radius of curvature in a transverse plane. Of course, the subject matter disclosed herein is not limited to this form. Thus, the panel 30 may have a shape the to be not developable with a double radius of curvature.

(11) FIGS. 2A, 2B, 3 to 5 show, labelled 30, a panel of part of an aircraft fuselage.

(12) This panel 30 comprises an internal face 30I and an external face 30E and is reinforced by stringers 32 attached to the internal face 30I. It is delimited by an upper edge 30H, a lower edge 30B and lateral edges 31, 31. By way of example, each lateral edge is arranged in a transverse plane. The upper edge 30H corresponds to a portion of an upper generatrix of the fuselage. The lower edge 30B corresponds to a portion of a lower generatrix of the fuselage.

(13) According to one embodiment, the panel 30 and the stringers 32 are made of composite material. Other materials could be envisioned.

(14) In order to obtain a part of the fuselage, the reinforced panel 30 is attached to frames 34 arranged in parallel planes (corresponding to transverse planes PT) and spaced apart along a direction (corresponding to the longitudinal direction DL). Thus, the frames 34 are positioned against the internal face 30I of the panel 30.

(15) According to one embodiment, shown in FIGS. 2A and 2B, each frame 34 comprises a profile which extends along a line of curvature Lc corresponding approximately to a semi-circle. This profile has a Z-shaped cross section. Thus, each frame comprises a web 36 with at each end flanges 38, 38 substantially perpendicular to the web 36.

(16) According to one variant, the frames 34 are metallic. However, they may be made of composite material.

(17) The frames 34 and the panel 30 are connected by clips 40. According to one embodiment shown in FIG. 2B, each clip 40 comprises at least two flanges 42.1 and 42.2 connected so as to form an angle bar, a first flange 42.1, called the sole, clamped against the internal face 30I of a panel 30 and a second flange 42.2 clamped against the web 36 of a frame 34.

(18) The sole 42.1 of each clip 40 is secured to the panel 30 using connection elements 44 such as bolts or rivets (some are shown in FIG. 4). These connection elements 44 comprise milled heads which are housed in milled portions provided in the external face 30E of the panel 30 so as not to impair its aerodynamic properties.

(19) The second flange 42.2 of each clip 40 is secured to the web 36 using connection elements 46 such as bolts or rivets.

(20) According to one variant, these clips are metallic. However, other materials could be envisioned.

(21) The panel 30, the frames 34 and the clips 40 are not described further as they can be identical to those of the first operating method of the prior art.

(22) As shown in FIG. 3, before assembly, the panel 30 is produced and reinforced with the stringers 32 while flat. This solution makes it possible to simplify the method for producing the reinforced panels 30. Thus, in the case of panels 30 and stringers 32 made of composite material, it is possible to automate the method for manufacturing the panels, in particular by using automatic lay-up machines.

(23) As shown in FIGS. 2A and 2B, the frames 34 have a profile which follows a reference line of curvature Lc in a transverse plane, the line of curvature Lc depending on the position of the frame in the fuselage. Before assembly with the panel or panels, the clips 40 are attached to the frames 34 with the permanent attachment elements 46. According to one embodiment, each frame is curved along its reference line of curvature Lc and the clips 40 are attached by an automatic structure for installing the attachment elements 46.

(24) The subject matter disclosed herein is not limited to the embodiments described above relating to the panel 30 and the frames. Thus, the panel 30 may be reinforced with elements other than stringers. Moreover, according to another variant, the frames 34 are connected directly to the panel 30, without the intermediary of clips. In this case, the frames are the to be integral.

(25) For the remainder of the description, a frame is understood as an integral frame directly connected to the panel or the assembly formed by a frame equipped with clips.

(26) Whatever the variant, a frame 34 comprises soles 42.1 which are clamped against the internal face 30I of the panel 30 and which are connected to the panel 30 by attachment elements 44.

(27) Advantageously, before assembly with the panel or panels, the soles 42.1 comprise at least one pilot hole 48 which will be used to place a pin in order to immobilize each sole 42.1 relative to the panel 30 when installing the permanent attachment elements 44. For preference, each sole 42.1 comprises at least two pilot holes 48 (shown in FIG. 2B).

(28) Once the panel 30 and the frames 34 are assembled, the external surface 30E of the panel 30 must be positioned according to a reference surface, to within the shape tolerances. Similarly, each frame must be positioned according to a reference position, to within the dimensional tolerances.

(29) For assembling the panel 30 and the integral frames 34, use is made of a tool 50 comprising a scaffold 52 which supports a plurality of support surfaces 54 and ribs 56, one for each integral frame 34. These support surfaces 54 are distinct from the frames and are positioned on the side of the internal face 30I of the panel 30. Moreover, the support surfaces 54 and the ribs are positioned on the same side of the panel 30.

(30) During assembly, the internal face 30I of the panel is clamped against the support surfaces 54 which are connected to the scaffold 52 sufficiently rigidly to allow the panel to deform from a flat shape to a curved shape. To that end, the shapes of the support surfaces 54 are such that, when the panel 30 bears against them, it has a curved shape matching that of the corresponding portion of the fuselage. Consequently, the support surfaces 54 have at least one radius of curvature in a transverse plane.

(31) Thus, when the internal surface 30I of the panel 30 is clamped against the support surfaces 54, certain points of the panel 30 are positioned within a tolerance range with respect to their reference positions.

(32) According to one embodiment, each support surface 54 comprises a strip of material 58 with lateral edges 60, 60 arranged in transverse planes. To indicate an order of magnitude, the lateral edges 60, 60 are separated by a distance of the order of 3 to 15 cm.

(33) According to one embodiment, the scaffold 52 comprises a frame with uprights 62, 62 connected by an upper crosspiece 64H and a lower crosspiece 64B. For a given panel 30, the upper crosspiece 64H extends according to a profile identical to that of the upper edge 30H of the panel and the lower crosspiece 64B extends according to a profile identical to that of the lower edge 30B of the panel.

(34) Each strip of material 58 extends from the upper crosspiece 64H to the lower crosspiece 64B and has a curvature which depends on the curvature of the panel 30 in the transverse plane occupied by the strip of material 58.

(35) The tool 50 also comprises a holder for holding the panel 30 clamped against the support surfaces 54. According to one embodiment, the holder comprises straps 66 which are tautened between the upper crosspiece 64H and the lower crosspiece 64B of the scaffold 52. The tool comprises as many straps 66 as there are support surfaces 54. For preference, the straps 66 are arranged facing the support surfaces 54 (in the same transverse planes), such that the panel 30 is positioned between a strap and a support surface.

(36) Advantageously, the tool 50 comprises a positioner for positioning the panel 30 with respect to the tool 50. The positioner can comprise at least one locating pin 67 and at least one point support 67.

(37) According to one embodiment, the locating pin 67 is secured to the tool and comprises a cylindrical peg with an axis perpendicular to the support surface. In addition, the panel 30 comprises an orifice 68 whose diameter is substantially equal to that of the peg. Thus, the locating pin 67 makes it possible to immobilize the panel 30 in translation with respect to the tool 50. The locating pin allows only one degree of freedom: that of rotation about the locating pin. This degree of freedom is eliminated by the point support 67.

(38) According to one embodiment, the point support 67 is secured to the tool and comprises a cylindrical peg with an axis perpendicular to the support surface. In addition, the panel 30 comprises an oblong hole 70 in which the peg is housed, the width of the oblong hole being substantially equal to the diameter of the peg.

(39) Other variants may be envisioned for the positioner.

(40) The panel can comprise pilot holes 72 (shown in FIG. 3) positioned so as to line up with the pilot holes 48 of the soles of the frames. The diameter of these pilot holes 72 is greater than that of the pilot holes 48 of the soles.

(41) According to one feature of the subject matter disclosed herein, each rib 56 comprises at least one sliding support surface 74. These sliding surfaces 74 are all positioned on the same side of the panel 30, on the concave side.

(42) According to one embodiment, each rib 56 comprises a single sliding support surface 74 which extends over approximately an arc of 180. As a variant, each rib 56 comprises multiple separate and coplanar sliding support surfaces.

(43) For each rib, the sliding support surface or surfaces extends or extend in a transverse plane.

(44) The support surfaces 54 and the sliding support surfaces 74 are secured to the same tool and are positioned relative to one another such that, once mounted, the frames are positioned correctly relative to the panel 30.

(45) According to one embodiment, each rib 56 comprises at least one sliding support surface 74 and at least one support surface 54.

(46) Each rib 56 comprises a rigid structure connected to the scaffold which extends in a transverse plane with a peripheral support surface 54 and on one of its faces at least one sliding support surface 74 parallel to a transverse plane.

(47) During assembly, the frame 34 is clamped against the sliding support surface 74. In the case of a frame with a Z-shaped cross section, the web 36 of the frame is clamped against the sliding support surface 74.

(48) According to one embodiment, the sliding support surface 74 comprises a coating or is made of a material which promotes sliding, such as polyacetal.

(49) The tool 50 also comprises for each rib 56 at least one brace 76 by which the frame can be held clamped against the sliding support surface 74. Advantageously, each rib comprises multiple braces 76 distributed all along the line of curvature Lc.

(50) According to one embodiment, each brace 76 comprises a counter-support 78 which can move between an active position in which the counter-support 78 is in contact with the frame 34 and holds it clamped against the sliding support surface 74 and a free position in which the counter-support 78 is moved away from the frame such that the latter can be mounted and removed. For preference, the brace 76 comprises a clevis 80 which is fixed with respect to the tool 50 and a lever 82 which pivots with respect to the clevis 80 and which supports the counter-support 78.

(51) Each brace 76 comprises a locking and unlocking system for keeping the counter-support 78 in the active position.

(52) For preference, the counter-support 78 allows the frame to slide in a radial direction.

(53) According to one embodiment, the counter-support comprises a coating or is made of a material which promotes sliding, such as polyacetal.

(54) According to another embodiment shown in FIG. 5, the counter-support 78 takes the form of a roller mounted such that it can pivot on a pivot spindle 84 arranged in a transverse plane and perpendicular to a radial direction 86. This configuration allows the frame to move in translation in the radial direction 86 while still being held clamped against the sliding support surface 74.

(55) A radial direction at a given point corresponds to a direction perpendicular to the tangent to the line of curvature at the given point.

(56) Advantageously, the tool 50 comprises for each rib 56 at least one positioner 88 for positioning the frame 36. For preference, each positioner 88 immobilizes the frame along the line of curvature Lc but allows a translational movement in the radial direction 86 so as to allow the position of the frame to be adjusted in the radial direction.

(57) According to one embodiment shown in FIG. 6, each positioner 88 comprises a locating pin 90 secured to the tool and the frame 36 comprises an oblong opening 92 in which the locating pin 90 is housed. The width of the oblong opening 92 is substantially equal to the diameter of the locating pin and the length of the oblong opening is greater than the diameter of the locating pin so as to allow the frame to move radially.

(58) In one aspect, each rib comprises a single positioner 88 arranged equidistant from the ends of the frame.

(59) The assembly method will now be described:

(60) First, the panel 30 is positioned on the tool 50. To that end, the panel 30 is curved so as to be clamped against the support surfaces 54. The panel 30 is positioned with respect to the tool 30 by the locating pin 67 and the point support 67. The straps 66 are put in place so as to hold the panel 30 clamped against the support surfaces 54. Bracing the panel in this manner makes it very rigid when the panel is subjected to a force perpendicular to its surface.

(61) Then, the frames are put in place one after another. Each one is first positioned using the positioner 88, then clamped against the sliding support surface 74 and held clamped by the braces 76.

(62) Then, at each sole, the frame 36 is connected to the panel 30 by pins which pass through the pilot holes 48 and 72. In order to control the internal stresses induced during assembly, the pins exert a clamping force on the skin and the sole of the order of 20 daN. According to the subject matter disclosed herein, the clamping forces applied to the frame generate no torsion provided that the frame is held clamped against the sliding support surfaces and can slide radially.

(63) The clearance between the soles and the panel 30 is measured to determine if the use of shims is necessary. If the clearance measured is less than a given value of the order of 0.3 mm, it is considered that the stresses produced by the permanent attachment elements to compensate for the clearance will be acceptable. In the opposite case, if the clearance is greater than the given value, shims are placed between the parts to be assembled so as to reduce the clearance.

(64) Then, all the holes intended for placing the permanent attachment elements are drilled and milled.

(65) Once these machining steps have been performed, the frames are removed in order to clean the surfaces of the soles and to coat them with an interposition mastic.

(66) Each frame is then re-mounted starting from the positioner 88 located equidistant from the ends of the frame, then by unrolling each of the ends. The frames are held in position by the braces 76.

(67) Once the frames have been braced, the permanent attachment elements are put in place.

(68) As for the drilling/milling, the permanent attachment elements can be placed by an automatic machine acting from the external face of the panel.

(69) After the permanent attachment elements have been placed, the straps 66 are removed and the braces 76 are positioned in the free position so as to remove the panel/frames assembly from the tool 50.

(70) The method of the subject matter disclosed herein makes it possible to assemble at least one panel and frames in an automated manner, wherein, in a first phase, the clips are attached to the frames, then, in a second phase, the panel or panels is/are attached to the frames equipped with clips.

(71) Moreover, this method makes it possible to control the internal stresses induced during assembly.

(72) Another advantage is that it is easier to position the frames one after another relative to the panel than to position the panel with respect to all the frames.

(73) While at least one exemplary embodiment of the present invention has been shown and described, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of the disclosure described herein. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, and the terms a or one do not exclude a plural number. Furthermore, characteristics or steps which have been described with reference to one of the above exemplary embodiments may also be used in combination with other characteristics or steps of other exemplary embodiments described above.