Tubular insert for a sandwich panel, method of installing such a tubular insert in a through hole of a sandwich panel, and sandwich panel comprising at least one such tubular insert

Abstract

Tubular insert for a sandwich panel, method for installing such a tubular insert in a through hole of a sandwich panel, and sandwich panel comprising at least one such tubular insert. The invention relates to a tubular insert intended to be positioned in a through hole of a sandwich panel. This tubular insert comprises a tubular body (52) and at least one tab (58) having a first end (58.1) connected to the tubular body (52) and a second end (58.2) distant from the first end (58.1), said tab (58) being movable between an extended position in which the second end (58.2) is away from the tubular body (52) and a retracted position in which the second end (58.2) is positioned at the level of the tubular body (52). The invention also relates to a sandwich panel comprising at least one such insert and a method for installing such an insert. Figure 4

Description

Title of the invention: Tubular insert for a sandwich panel, method for installing such a tubular insert in a through hole of a sandwich panel, and sandwich panel comprising at least one such tubular insert

[0001] The present application relates to a tubular insert for a sandwich panel, to a method of installing such a tubular insert in a through hole of a sandwich panel and to a sandwich panel comprising at least one such tubular insert.

[0002] As illustrated in [Fig.1], a sandwich panel 10 comprises first and second outer walls 12, 14 and at least one honeycomb structure 16 interposed between the first and second outer walls 12, 14. Each of the first and second outer walls 12, 14 comprises an inner face 12.1, 14.1 connected to the honeycomb structure 16 and an outer face 12.2, 14.2 opposite the inner face 12.1, 14.1.

[0003] According to an embodiment visible in [Fig.2], the sandwich panel 10 includes a tubular insert 20 opening at the external faces 12.2, 14.2 of the first and second external walls 12, 14. The sandwich panel 10 includes a through orifice 22, piercing the external walls 12, 14 and the honeycomb structure 16, configured to house the tubular insert 20.

[0004] This tubular insert 20 comprises a first portion 24 inserted into the through-hole 22 from the outer face 12.2 of the first outer wall 12 and a second portion 26 inserted into the through-hole 22 from the outer face 14.2 of the second outer wall 14. The first portion 24 comprises a first tubular segment 24.1 and a first flange 24.2 provided at one end of the first tubular segment 24.1 and configured to be pressed against the outer face 12.2 of the first outer wall 12. The second portion 26 comprises a second tubular segment 26.1 and a second flange 26.2 provided at one end of the second tubular segment 26.1 and configured to be pressed against the outer face 14.2 of the second outer wall 14. The first and second tubular segments 24.1, 26.1 are configured to to fit together.

[0005] According to a prior art method, a method for installing a tubular insert 20 comprises a step of creating a through hole 22, a step of hollowing out the honeycomb structure 16 between the first and second outer walls 12, 14, so as to generate an annular recess 28 around the through hole 22, a step of filling the annular recess 28 with a sealant (or adhesive) 30 and coating the surfaces of the sandwich panel 10 with sealant 30. contact with the first and second parts 24, 26 of the tubular insert 20, a step of successively placing the first and second parts 24, 26 of the tubular insert 20 and finally a step of removing the sealant 30 inside the tubular portions 24.1, 26.1 of the tubular insert 20.

[0006] This method of installing a tubular insert 20 is not satisfactory because its implementation is relatively time-consuming. Furthermore, this method generates protruding shapes relative to the outer faces 12.2, 14.2 of the outer walls 12, 14 at each end of the tubular insert 20. Finally, the height of these protruding shapes is difficult to control, as the thickness of the sealant between the collars 24.2, 26.2 and the outer walls 12, 14 is itself difficult to control.

[0007] The present invention aims to remedy all or part of the drawbacks of the prior art.

[0008] For this purpose, the invention relates to a tubular insert comprising a tubular body which has coaxial inner and outer cylindrical faces and first and second annular terminal faces connecting the inner and outer cylindrical faces.

[0009] According to the invention, the tubular insert comprises at least one tab which has a first end connected to the tubular body and a second end distant from the first end, said tab being movable between a deployed position in which the second end is away from the tubular body and a retracted position in which the second end is positioned at the level of the tubular body.

[0010] Unlike the prior art, which uses collars on the outside of the sandwich panel to secure the tubular insert to the sandwich panel along a longitudinal direction (perpendicular to the outer walls), the invention provides at least one tab positioned between the outer walls of the sandwich panel when the tubular insert is positioned in the through-hole of the sandwich panel to secure the tubular insert to the sandwich panel along the longitudinal direction. Thus, the tubular insert may not have any protruding parts beyond the outer walls of the sandwich panel. Furthermore, the tubular insert can be made in a single piece, which reduces its installation time.

[0011] According to another feature, the tubular insert comprises several tabs distributed around the tubular body.

[0012] According to another feature, at least each tab is made of an elastic material, the deployed position of the tab corresponding to a rest position, the retracted position corresponding to an elastic deformation of the tab.

[0013] According to another feature, the tubular body includes at least one opening allowing communication between the inner and outer cylindrical faces of the tubular body.

[0014] According to another feature, the tubular body includes, for each tab, a cutout delimiting the tab and an opening when the corresponding tab is in the deployed position.

[0015] According to another feature, at least one of the first and second terminal faces includes at least one indentation configured to rotate the tubular insert on itself.

[0016] According to another feature, the tubular insert has a sleeve with a solid wall, fitted into the tubular body.

[0017] The invention also relates to a sandwich panel comprising first and second outer walls, at least one honeycomb structure interposed between the first and second outer walls and at least one tubular insert according to one of the preceding characteristics, positioned in a through hole of the sandwich panel.

[0018] According to another feature, the through-hole comprises first and second sections at the level of the first and second outer walls. In addition, the tubular insert has a cross-section greater than that of the first and second sections of the through-hole when each tab is in the deployed position and a cross-section less than that of the first and second sections of the through-hole when each tab is in the retracted position.

[0019] According to another feature, the tubular body has an outside diameter substantially equal to the sections of the through orifice.

[0020] According to another feature, the tubular body has a height substantially equal to the thickness of the sandwich panel.

[0021] According to another feature, each tab comprises upper and lower edges substantially parallel to each other, connecting the first and second ends, the upper and lower edges being spaced at a distance substantially equal to the thickness of the alveolar structure.

[0022] According to another feature, the upper edge of each tab is separated from the first end face by a distance substantially equal to the thickness of the first outer wall. In addition, the lower edge is separated from the second end face by a distance substantially equal to the thickness of the second outer wall.

[0023] The invention also relates to a method for installing a tubular insert in a through hole of a sandwich panel comprising first and second outer walls and at least one honeycomb structure interposed between the first and second outer walls. This installation method includes an insertion step of the tubular insert in the through orifice, each tab being in the retracted position, until each tab is positioned between the first and second outer walls and returns to the deployed position, a pivoting step of the tubular insert on itself so as to generate, around the tubular body of the tubular insert, an annular housing between the first and second outer walls as well as a step of injecting a sealant into the annular housing to secure the tubular insert and the sandwich panel.

[0024] 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:

[0025] [Fig-1] is a perspective view of a sandwich panel comprising a honeycomb structure sandwiched between two outer walls illustrating one embodiment,

[0026] [Fig.2] is a cross-section of a sandwich panel comprising an insert tubular illustrating a method of realization from earlier art,

[0027] [Fig.3] is a cross-section of a sandwich panel comprising an insert tubular illustration of one embodiment of the invention,

[0028] [Fig.4] is a perspective view of a tubular insert illustrating a method of publication of the invention,

[0029] [Fig.5] is a top view of the tubular insert visible in [Fig.4],

[0030] [Fig.6] is a perspective view of the tubular insert visible on the [Fig.4] prea attached to its insertion into a through hole in a sandwich panel illustrating one embodiment of the invention,

[0031] [Fig.7] schematically represents different stages of an installation process of a tubular insert in a sandwich panel illustrating one embodiment of the invention,

[0032] [Fig.8] is a perspective view of a tubular insert illustrating another embodiment of the invention.

[0033] According to an embodiment in [Fig.3], a sandwich panel 40 comprises first and second outer walls 42, 44 and at least one honeycomb structure 46 interposed between the first and second outer walls 42, 44. Each of the first and second outer walls 42, 44 comprises an inner face 42.1, 44.1 connected to the honeycomb structure 46 and an outer face 42.2, 44.2 opposite the inner face 42.1, 44.1. Each of the first and second outer walls 42, 44 has a thickness corresponding to the distance separating the inner and outer faces 42.1, 44.1, 42.2, 44.2 of the first or second outer wall 42, 44. The honeycomb structure 46 comprises a first face 46.1 connected to the inner face 42.1 of the first outer wall 42, and a second face 46.2 connected to the inner face 44.1 of the second outer wall 44. The honeycomb structure The veolar 46 has a thickness corresponding to the distance separating the first and second faces 46.1, 46.2. The sandwich panel 40 has a thickness corresponding to the distance separating the outer faces 42.2, 44.2 from the outer walls 42, 44.

[0034] According to one configuration, an adhesive film 47 is intercalated between each of the first and second outer walls 42, 44 and the honeycomb structure 46 to ensure the bond between the inner face 42.1, 44.1 of each outer wall 42, 44 and the honeycomb structure 46.

[0035] The sandwich panel 40 is not described further as it is known from the prior art.

[0036] This sandwich panel 40 comprises at least one tubular insert 48 positioned in A through-hole 50 opens at the outer faces 42.2, 44.2 of the first and second outer walls 42, 44. The through-hole A50 has an axis A50 substantially perpendicular to the outer walls 42, 44 and a diameter D50. It comprises first and second sections 50.1, 50.2 at the first and second outer walls 42, 44 which have diameters identical to the diameter D50 of the through-hole 50.

[0037] As illustrated in Figures 4 and 5, this tubular insert 48 comprises a tubular body 52 which has an inner cylindrical face 52.1, an outer cylindrical face 52.2 and first and second terminal faces 54.1, 54.2. The inner and outer cylindrical faces 52.1, 52.2 are coaxial with each other and with an axis of revolution A52. The tubular body 52 of the tubular insert 48 has a thickness, corresponding to the distance separating the inner and outer cylindrical faces 52.1, 52.2, of between 1 and a few millimeters.

[0038] The first and second terminal faces 54.1, 54.2 are annular and connect the inner and outer cylindrical faces 52.1, 52.2. They are substantially parallel to each other and substantially perpendicular to the axis of revolution A52 of the tubular body 52 of the tubular insert 48. The tubular body 52 has a height, corresponding to the distance separating the first and second end faces 54.1, 54.2, substantially equal to the thickness of the sandwich panel 40. Thus, when the tubular insert 48 is positioned in the through-hole 50, the first and second end faces 54.1, 54.2 are respectively flush with the outer faces 42.2, 44.2 of the first and second outer walls 42, 44. Unlike the prior art, once in place, the tubular insert 48 according to the invention does not include any part projecting from the outer faces 42.2, 44.2 of the sandwich panel 40.

[0039] According to one configuration, at least one of the first and second end faces 54.1, 54.2 comprises at least one recess configured to rotate the tubular insert 48 about itself, around the axis of revolution A52, with a tool. For this purpose, at least one of the first and second end faces 54.1, 54.2 comprises at less one pair of radial slots 56.1, 56.2 diametrically opposed. According to different configurations, several pairs of radial slots 56.1, 56.2 may be provided on the same first or second terminal face 54.1, 54.2 and / or at least one pair of radial slots 56.1, 56.2 is provided on each of the first and second terminal faces 54.1, 54.2.

[0040] According to one feature of the invention, the tubular insert 48 comprises at least one tab 58 which has a first end 58.1 connected to the tubular body 52, more particularly to the outer cylindrical face 52.2, and a second end 58.2 distant from the first end 58.1, said tab 58 being movable between a deployed position (visible in Figures 4 and 5) in which the second end 58.2 is away from the tubular body 52 and a retracted position in which the second end 58.2 is positioned at the level of the tubular body 52. ​​In the deployed position, the tubular insert 48 has a cross-section (perpendicular to the axis of revolution A52) greater than that of the first and second sections 50.1, 50.2 of the through orifice 50, preventing the tubular insert 48 from exiting the through orifice 50.In the retracted position, the tubular insert 48 has a reduced cross-section, smaller than the cross-section of the first and second sections 50.1, 50.2 of the through orifice 50, allowing it to be inserted into the through orifice 50.

[0041] According to one configuration, at least each tab 58 is made of an elastic material, the deployed position of the tab 58 corresponding to a rest position in which the tab 58 is not subjected to any stress, the retracted position corresponding to an elastic deformation of the tab 58 in the presence of a stress tending to push the second end 58.2 of the tab 58 towards the outer cylindrical face 52.2 of the tubular insert 48.

[0042] According to one embodiment, the tubular body 52 and the tongue(s) 58 are metallic and made in one piece.

[0043] According to one arrangement, each tab 58 is configured to be able to cut the honeycomb structure 46 when the tubular insert 48, inserted into the through orifice 50, pivots on itself. In the deployed position, each tab 58 forms an angle of between 20° and 70° with a tangent to the outer cylindrical face 52.2 passing through the first end 58.1 of the tab 58. According to one configuration, the second end 58.2 of each tab 58 can be tapered.

[0044] According to one embodiment, the tubular insert 48 comprises several tabs 58 regularly distributed around the tubular body 52. ​​According to an arrangement visible in figures 4 and 5, the tubular insert 48 comprises six tabs.

[0045] Each tab 48 comprises upper and lower edges 60.1, 60.2 substantially parallel to each other, connecting the first and second ends 58.1, 58.2. The upper edge 60.1 is closest to the first terminal wall 54.1, the lower edge 60.2 being closest to the second terminal wall 54.2. The first and second ends 58.1, 58.2 are substantially parallel to the axis of revolution A52 of the tubular body 52 of the tubular insert 48. The upper and lower edges are substantially perpendicular to the axis of revolution A52 of the tubular body 52 of the tubular insert 48. Thus, each tab 58 has a substantially rectangular shape, the first and second ends 58.1, 58.2 corresponding to the long sides of the rectangle, the upper and lower edges 60.1, 60.2 corresponding to the short sides of the rectangle.

[0046] According to one configuration, the upper and lower edges 60.1, 60.2 are spaced apart by a distance substantially equal to that separating the inner faces 42.1, 44.1 from the outer walls 42, 44 or to the thickness of the alveolar structure 46. Thus, the tubular insert 48 is immobilized in translation along a direction parallel to the axis A50 of the through orifice 50 when the tubular insert 48 is positioned in the through orifice 50.

[0047] According to a preferred embodiment, the upper edge 60.1 is separated from the first end face 54.1 by a distance substantially equal to the thickness of the first outer wall 42. Thus, the first end face 54.1 of the tubular insert 48 is flush with the outer face 42.2 of the first outer wall 42 when the tubular insert 48 is positioned in the through-hole 50. The lower edge 60.2 is separated from the second end face 54.2 by a distance substantially equal to the thickness of the second outer wall 44. Thus, the second end face 54.2 of the tubular insert 48 is flush with the outer face 44.2 of the second outer wall 44 when the tubular insert 48 is positioned in the through-hole 50.

[0048] According to one configuration, the tubular body 52 includes at least one opening 62 allowing communication between the inner and outer cylindrical faces 52.1, 52.2 of the tubular body 52.

[0049] According to one embodiment, the tubular body 52 comprises, for each tab 58, a cutout 64 delimiting the tab 58. This cutout 64 comprises upper and lower sections 64.1, 64.2 which correspond to the upper and lower edges 60.1, 60.2 of the tab 58, as well as a longitudinal section 64.3, connecting the first and second sections 64.1, 64.2, which corresponds to the second end 58.2 of the tab 58. Each cutout 64 delimits an opening 62 when the corresponding tab 58 is in the deployed position. The fact that each tab 58 is formed from a cutout 64 of the tubular body 52 allows each tab 58 to be positioned in the opening 62 delimited by the cutout 64 in the retracted position. Thus, the tabs 58 do not form any additional thickness relative to the outer cylindrical face 52.2 of the tubular body 52 in the retracted position. In this case, the The tubular body 52 has an outside diameter substantially equal to those of the sections 50.1, 50.2 of the through hole 50. Thus, the tubular insert 48 is immobilized in a transverse plane (perpendicular to the axis A50 of the through hole 50) with respect to the sandwich panel 40 when the tubular insert 48 is positioned in the through hole 50.

[0050] According to a configuration visible in [Fig. 8], the tubular insert 48 has a sleeve 66 positioned within the tubular body 52. ​​This sleeve 66 has a solid wall (without openings), an outer diameter substantially identical to the diameter of the inner cylindrical face 52.1 of the tubular body 52, and a height substantially identical to that of the tubular body 52. ​​In one embodiment, the sleeve 66 is fitted into the tubular body 52. ​​To immobilize it against translation and rotation relative to the tubular body 52, the sleeve 66 includes, at one of its ends, projecting from its outer surface, at least one lug 66.1 configured to fit into one of the radial slots 56.1, 56.2 provided in one of the first and second end faces 54.1, 54.2 of the tubular body 52. ​​In one arrangement, the sleeve 66 includes two lugs 66.1, 66.2 diametrically opposed, configured to fit into the radial slots 56.1, 56.2 diametrically opposed provided at the level of one of the first and second terminal faces 54.1, 54.2 of the tubular body 52. ​​.

[0051] According to one method, prior to the installation of the tubular insert 48, a through hole 50 is made in the sandwich panel 40, as illustrated in [Fig.6]. In some cases, the through hole 50 is obtained by enlarging an existing hole.

[0052] A method for installing a tubular insert 48 includes a step of inserting the tubular insert 48 into the through orifice 50, the tabs 58 being in the retracted position, until the tabs 58 are positioned between the first and second outer walls 42, 44 and automatically return to the deployed position thanks to the elastic properties of the tubular insert 48.

[0053] Following, as illustrated in part (B) of [Fig.7], the installation process includes a step of pivoting the tubular insert 48 on itself around the axis of revolution A52. During this step, the tabs 58 cut the alveolar structure 46 so as to generate, around the tubular body 52 of the tubular insert 48, an annular housing 68 between the first and second outer walls 42, 44.

[0054] Following, as illustrated in part (C) of [Fig.7], the installation process includes a step of injecting a sealant (or glue) 70 into the annular housing 68 via the openings 62 of the tubular body 52. ​​By sealant 70, we mean any product enabling the tubular insert 48 and the sandwich panel 40 to be joined.

[0055] Finally, as illustrated in [Fig. 8], the laying process includes a step insertion of the sleeve 66 into the tubular body 52.

[0056] As illustrated in [Fig.7], the same tool 72 is used for the pivoting and sealant injection steps 70. This tool 72 comprises a cylindrical body 74, which has a diameter substantially equal to the inner diameter of the tubular body 52 of the tubular insert 48, and a cylindrical head 76, coaxial with and integral to the cylindrical body 74, which has a diameter greater than that of the cylindrical body 74. The cylindrical body 74 and the head 76 have the same axis of revolution A72.

[0057] The tool 72 has a shoulder 78 connecting the cylindrical body 74 and the head 76, substantially perpendicular to the axis of revolution A72.

[0058] The cylindrical body 74 of the tool 72 is configured to fit into the tubular body 52 of the tubular insert 48. This cylindrical body 74 has a height substantially equal to that of the tubular body 52.

[0059] When the cylindrical body 74 is inserted into the tubular body 52, the shoulder 78 is pressed against one of the first and second terminal faces 54.1, 54.2 of the tubular body 52, in this case the one provided with the radial slots 56.1, 56.2.

[0060] The tool 72 includes, at the shoulder 78, lugs 80 configured to fit into the radial slots 56.1, 56.2 of the tubular insert 48. Thus, when the lugs 80 of the tool 72 are inserted into the radial slots 56.1, 56.2 of the tubular insert 48, the pivoting of the tool 72 causes the pivoting of the tubular insert 48.

[0061] The tool 72 includes a pivoting system or can be connected to a tool incorporating a pivoting system, such as a rotary handheld tool, to allow it to pivot on itself around its axis of revolution A72.

[0062] The tool 72 includes a sealant supply system 82 having lateral ports 82.1 located on the lateral face of the cylindrical body 74 of the tool 72 and at least one supply conduit 82.2 connected to each lateral port 82.2. In operation, when the cylindrical body 74 is positioned in the tubular body 52 of the tubular insert 48, the lateral ports 82.1 are positioned opposite the openings 62 and communicate with the annular housing 68 via said openings 62. The tool 72 may include a sealant injection system or be connected to a sealant injection system configured to push the sealant 70 from the supply conduit 82.2 towards the lateral ports 82.1.

[0063] Of course, the invention is not limited to this tool 72 for pivoting the tubular insert 48 and injecting the sealant 80.

Claims

Claims

1. Tubular insert comprising a tubular body (52) which has an axis of revolution (A52), inner and outer cylindrical faces (52.1, 52.2) coaxial with each other and with the axis of revolution (A52) as well as first and second annular end faces (54.1, 54.2) connecting the inner and outer cylindrical faces (52.1, 52.2), characterized in that the tubular insert comprises at least one tab (58) which has a first end (58.1) connected to the tubular body (52) as well as a second end (58.2) distant from the first end (58.1), the first and second ends (58.1, 58.2) being substantially parallel to the axis of revolution (A52) of the tubular body (52), said tab (58) being movable between a deployed position in which the second end (58.2) is spaced from the tubular body (52) and a retracted position in which the second end (58.2) is positioned at the level of the tubular body (52) and in that the tubular body (52) comprises, for each tab (58), a cutout (64) delimiting the tab (58) and an opening (62) when the corresponding tab (58) is in the deployed position.

2. Tubular insert according to claim 1, characterized in that the tubular insert comprises several tabs (58) distributed around the tubular body (52).

3. Tubular insert according to one of the preceding claims, characterized in that at least each tab (58) is made of an elastic material, the deployed position of the tab (58) corresponding to a rest position, the retracted position corresponding to an elastic deformation of the tab (58).

4. Tubular insert according to one of the preceding claims, characterized in that the tubular body (52) comprises at least one opening (62) allowing the inner and outer cylindrical faces (52.1, 52.2) of the tubular body (52) to communicate.

5. Tubular insert according to one of the preceding claims, characterized in that at least one of the first and second end faces (54.1, 54.2) comprises at least one imprint configured to pivot the tubular insert (48) on itself.

6. Tubular insert according to one of the preceding claims, characterized in that the tubular insert has a sleeve (66) with a solid wall, fitted into the tubular body (52).

7. Sandwich panel comprising first and second outer walls (42, 44), at least one honeycomb structure (46) interposed between the first and second outer walls (42, 44) and at least one tubular insert according to one of the preceding claims, positioned in a through-orifice (50) of the sandwich panel.

8. Sandwich panel according to the preceding claim, characterized in that the through-hole (50) comprises first and second sections (50.1, 50.2) at the first and second outer walls (42, 44) and in that the tubular insert (48) has a cross-section greater than that of the first and second sections (50.1, 50.2) of the through-hole (50) when each tab (58) is in the deployed position and a cross-section less than the section of the first and second sections (50.1, 50.2) of the through-hole (50) when each tab (58) is in the retracted position.

9. Sandwich panel according to the preceding claim, characterized in that the tubular body (52) has an external diameter substantially equal to the sections (50.1, 50.2) of the through-orifice (50).

10. Sandwich panel according to one of claims 7 to 9, characterized in that the sandwich panel comprises a thickness and in that the tubular body (52) has a height substantially equal to the thickness of the sandwich panel.

11. Sandwich panel according to one of claims 7 to 10, characterized in that the cellular structure (46) has a thickness and in that each tongue (58) comprises upper and lower edges (60.1, 60.2) substantially parallel to each other, connecting the first and second ends (58.1, 58.2), the upper and lower edges (60.1, 60.2) being spaced apart by a distance substantially equal to the thickness of the cellular structure (46).

12. Sandwich panel according to the preceding claim, characterized in that the first and second outer walls (42, 44) have first and second thicknesses respectively, in that the upper edge (60.1) of each tongue (58) is separated from the first end face (54.1) by a distance substantially equal to the first thickness of the first outer wall (42) and in that the lower edge (60.2) is separated from the second end face (54.2) by a distance substantially equal to the second thickness of the second outer wall (44).

13. Method for installing a tubular insert according to one of claims 1 to 6 in a through-hole (50) of a sandwich panel (40) comprising first and second outer walls (42, 44) as well as at least one cellular structure (46) interposed between the first and second outer walls (42, 44), characterized in that the installation method comprises a step of inserting the tubular insert (48) into the through-hole (50), each tab (58) being in the retracted position, until each tab (58) is positioned between the first and second outer walls (42, 44) and returns to the deployed position, a step of pivoting the tubular insert (48) on itself so as to generate, around the tubular body (52) of the tubular insert (48), an annular housing (68) between the first and second outer walls (42,44) as well as a step of injecting a mastic (70) into the annular housing (68) to secure the tubular insert (48) and the sandwich panel (40).,

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