METHOD FOR MANUFACTURING A PANEL WITH A DOUBLER

Abstract

Disclosed is a panel for an aircraft structure, including a laminated skin of layers of metal of which in each case two are joined together by a fibre-reinforced adhesive layer, as well as a laminated doubler of layers of metal and at least one fibre-reinforced adhesive layer in each case between two layers of metal, wherein the doubler has a smaller size of perimeter than the skin and is bonded to an outermost layer of metal of the laminated skin by a fibre-reinforced supplementary adhesive layer, with the feature that at least one part of the perimeter of the fibre-reinforced supplementary adhesive layer is staggered inwards relative to the corresponding perimeter of the doubler and that that part of the inwards-staggered perimeter of the fibre-reinforced supplementary adhesive layer is delimited by a glued edge. Also disclosed is a method for manufacturing such a panel.

Claims

1. Method for manufacturing a panel (200) for an aircraft structure, said panel being provided with a doubler (310, 311), wherein the method comprises: supplying the doubler in the form of a laminate of layers of metal (320) and at least one fibre-reinforced adhesive layer (321) in each case between two layers of metal, and by means of said at least one fibre-reinforced adhesive layer the at least two layers of metal are fastened together, supplying a jig (400), supplying, in the jig, a stack of layers of metal (304) and layers of fibres (303) embedded in a precursor of an adhesive included in each case between two layers of metal to form a skin (301), placing a further layer of fibres (340) embedded in a precursor of an adhesive on the stack, placing the doubler on the further layer of fibres embedded in a precursor of an adhesive, so that the further layer of fibres embedded in a precursor of an adhesive forms an intermediate layer between the stack and the doubler, placing an air-tight covering layer over the stack, the intermediate layer and the doubler, thereby forming a space between the jig and the covering layer, air-tight closure of the covering layer around the perimeter of the stack, the intermediate layer and the doubler with respect to the jig, putting the jig with the stack, the intermediate layer and the doubler as well as the sealed covering layer in an autoclave, lowering the pressure in the space between the jig and the covering layer, under the effect of heat and pressure in the autoclave, gluing the layers of metal together by activating the precursor of the adhesive of each embedded layer of fibres with formation of a laminated skin, as well as simultaneously, under the effect of the heat and pressure in the autoclave, activating the precursor of the adhesive of the further layer of fibres in the intermediate layer with formation of a supplementary adhesive layer, by means of which the doubler is bonded to the laminated skin, thereby forming the panel, removing the panel from the autoclave.

2. Method according to claim 1, comprising the steps of: causing the perimeter of the further layer of fibres (342) to recede relative to the perimeter (322) of the doubler, filling the space (343) delimited by the doubler, the stack and the perimeter of the further layer of fibres with glue, forming a glued edge (330), activating the glued edge under the effect of heat in the autoclave.

3. Method according to claim 1, comprising the step of: after removal of the panel from the autoclave, simultaneous material-removal machining of a combined edge part of the laminated skin and the doubler of the panel to provide a predetermined nominal edge shape and dimensioning of the panel.

4. Method according to claim 3, further comprising: providing positioning openings (370) in the doubler, providing positioning openings (370) in the layers of metal and embedded layers of fibres for forming the skin, in the jig, aligning said positioning openings in the doubler and in the skin relative to one another, fastening positioning pins (380) to the jig that extend through said positioning openings in the doubler and in the skin.

5. Method according to claim 4, further comprising: manufacturing a doubler (310, 311) and a skin (301) with oversize with formation of a supplementary region (350) into which both the skin and the doubler extend, providing the positioning openings (370) through the skin and the doubler of the panel in the location of the supplementary region, removing the supplementary region with formation of an edge of the panel.

6. Method according to claim 1, comprising manufacturing the doubler by the steps of: supplying a supplementary jig, supplying, in the supplementary jig, a supplementary stack of layers of metal and layers of fibres embedded in a precursor of an adhesive included in each case between two layers of metal, placing an air-tight covering layer over the supplementary stack, thereby forming a space between the supplementary jig and the covering layer, air-tight closure of the covering layer around the perimeter of the supplementary stack relative to the supplementary jig, putting the supplementary jig with the supplementary stack in an autoclave, lowering the pressure in the space between the supplementary jig and the covering layer, under the effect of heat and pressure in the autoclave, gluing the layers of metal together by activating the precursor of the adhesive of each layer of fibres, with formation of a doubler in the form of a laminate of layers of metal and at least one fibre-reinforced adhesive layer in each case between two layers of metal, removing the doubler from the autoclave.

7. Method according to claim 1, wherein supplying the doubler in the form of a laminate comprises manufacturing the doubler by the steps of: supplying a supplementary stack of layers of metal and layers of fibres embedded in a precursor of an adhesive included in each case between two layers of metal, and placing the supplementary stack on the intermediate layer, wherein during the step of gluing the layers of metal together under the effect of heat and pressure by activating the precursor of the adhesive of each layer of fibres, a doubler is formed in the form of a laminate of layers of metal and at least one fibre-reinforced adhesive layer in each case between two layers of metal on the laminated skin.

8. Method according to claim 7, wherein each layer of metal of the supplementary stack has a smaller perimeter than an underlying layer of metal of the supplementary stack.

9. Method according to claim 1, comprising applying a doubler that has a smaller perimeter than the skin.

10. Method according to claim 1, comprising, before placing an air-tight covering layer over the stack, the intermediate layer and the doubler, the step of placing a further intermediate layer (340) on a free side of the doubler, wherein the further intermediate layer comprises a further layer of fibres embedded in a precursor of an adhesive, and placing a further doubler (312-316) on the further intermediate layer.

11. Panel (200) for an aircraft structure, manufactured according to the method of claim 1, said panel comprising a laminated skin (301) of layers of metal (304), of which in each case two are joined together by a fibre-reinforced adhesive layer (303), as well as a laminated doubler (310, 311) of layers of metal (320) and at least one fibre-reinforced adhesive layer (321) in each case between two layers of metal, where said doubler has a smaller size of perimeter than the skin and is bonded to an outermost layer of metal of the laminated skin by a fibre-reinforced supplementary adhesive layer (340), wherein at least one part of the perimeter (342) of the fibre-reinforced supplementary adhesive layer is staggered inwards relative to the corresponding perimeter of the doubler and wherein that part of the inwards-staggered perimeter of the fibre-reinforced supplementary adhesive layer is delimited by a glued edge (330).

12. Panel according to claim 11, further comprising a further laminated doubler (312-316), wherein said further doubler has a smaller size of perimeter than the skin and/or the laminated doubler and is bonded to an outermost layer of metal of the laminated doubler by a fibre-reinforced supplementary adhesive layer (340), wherein at least one part of the perimeter of the fibre-reinforced supplementary adhesive layer is staggered inwards relative to the corresponding perimeter of the further doubler and wherein that part of the inwards-staggered perimeter of the fibre-reinforced supplementary adhesive layer is delimited by a glued edge.

13. Panel according to claim 11, wherein the glued edge extends to, or beyond, said corresponding perimeter of the doubler.

14. Panel according to claim 11, wherein a first part of the perimeter of the doubler borders on and coincides with a part of an edge of the skin and a second part of the perimeter of the doubler is located at a distance from the edge of the skin, wherein the supplementary adhesive layer extends to the first part of the perimeter of the doubler and wherein the supplementary adhesive layer is staggered inwards relative to the second part of the perimeter of the doubler.

15. Panel according to claim 14, wherein the glued edge is located exclusively at the location of the inwards-staggered part of the supplementary adhesive layer on the second part of the perimeter of the doubler, which is located at a distance from the edge of the skin.

16. Aircraft comprising a panel according to claim 11.

17. Method according to claim 2, comprising the step of: after removal of the panel from the autoclave, simultaneous material-removal machining of a combined edge part of the laminated skin and the doubler of the panel to provide a predetermined nominal edge shape and dimensioning of the panel.

18. Method according to claim 1, further comprising: providing positioning openings (370) in the doubler, providing positioning openings (370) in the layers of metal and embedded layers of fibres for forming the skin, in the jig, aligning said positioning openings in the doubler and in the skin relative to one another, fastening positioning pins (380) to the jig that extend through said positioning openings in the doubler and in the skin.

19. Method according to claim 2, further comprising: providing positioning openings (370) in the doubler, providing positioning openings (370) in the layers of metal and embedded layers of fibres for forming the skin, in the jig, aligning said positioning openings in the doubler and in the skin relative to one another, fastening positioning pins (380) to the jig that extend through said positioning openings in the doubler and in the skin.

20. Method according to claim 2, comprising manufacturing the doubler by the steps of: supplying a supplementary jig, supplying, in the supplementary jig, a supplementary stack of layers of metal and layers of fibres embedded in a precursor of an adhesive included in each case between two layers of metal, placing an air-tight covering layer over the supplementary stack, thereby forming a space between the supplementary jig and the covering layer, air-tight closure of the covering layer around the perimeter of the supplementary stack relative to the supplementary jig, putting the supplementary jig with the supplementary stack in an autoclave, lowering the pressure in the space between the supplementary jig and the covering layer, under the effect of heat and pressure in the autoclave, gluing the layers of metal together by activating the precursor of the adhesive of each layer of fibres, with formation of a doubler in the form of a laminate of layers of metal and at least one fibre-reinforced adhesive layer in each case between two layers of metal, removing the doubler from the autoclave.

Description

[0071] The invention will be explained further hereunder, on the basis of the figures.

[0072] FIG. 1 shows a block diagram of the manufacturing process for a panel with doubler according to the prior art.

[0073] FIG. 2 shows a stack of laminates on a jig during manufacture according to the prior art.

[0074] FIG. 3 shows a block diagram of the manufacturing process for a panel with doubler according to the invention.

[0075] FIG. 4 shows a stack of layers on a jig during manufacture according to the invention.

[0076] FIG. 5 shows a cross-section of a panel provided with a doubler according to the invention.

[0077] FIG. 6 shows a perspective view of the inside of a panel provided with several doublers, such as for an aircraft fuselage, according to the invention.

[0078] FIG. 7 shows a cross-section of the panel according to FIG. 6.

[0079] FIG. 1 shows, in a block diagram 10, the manufacturing process for a panel 1, see FIG. 2, according to the prior art. FIG. 2 shows a stack 6 of laminates 2, 3 on a jig 5 during manufacture of a panel 1 according to the prior art from FIG. 1. The manufacturing process starts with the preparation 11 of the various components of the final panel 1. These components comprise the layers of metal and the layers of fibres embedded in a precursor of an adhesive that make up the laminated skin 2 and the doubler 3 of the panel 1. After the preparatory steps 11, the respective layers for forming the laminated skin 2 and for forming the doubler 3 are stacked on one another (steps 12 and 20). During stacking for both components, the layers of metal and the layers of fibres are stacked on one another in such a way that in each case at least one layer of fibres embedded in a precursor of an adhesive is included between two layers of metal.

[0080] The stack for forming the skin is put in an autoclave (13), in which, under the effect of pressure and heat, the precursor of the adhesive in the layers of fibres is activated and the layers of metal and the layers of fibres are bonded together so that a laminated skin is produced. The formed skin 2 undergoes non-destructive inspection, for example by detecting inclusions of air, to check whether the skin meets the quality requirements (14). If the inspection is passed, the laminated skin undergoes material-removal machining (15), for example to make a precursor of a door opening and/or window opening 4.

[0081] The stack for forming the doubler 3 is also put in an autoclave (21), in which, under the effect of pressure and heat, the precursor of the adhesive in the layers of fibres is activated and the layers of metal and the layers of fibres are bonded together so that the laminated doubler is produced. The formed doubler 3 undergoes non-destructive inspection, for example by detecting inclusions of air, to check whether the laminate meets the quality requirements (22). If the inspection is passed, the doubler undergoes material-removal machining (23), for example to make a precursor 7 of the final form of the doubler, and to bring the further edges of the laminated skin to size.

[0082] After separate manufacture of the laminated skin 2 and the doubler 3, the doubler 3 is stacked on the laminated skin 2 (30). A further layer of fibres embedded in a precursor of an adhesive is placed between the doubler 3 and the laminated skin 2. This third stack is put in an autoclave (31), in which, under the effect of pressure and heat, the precursor of the adhesive in the further layer of fibres is activated and the laminated skin and the doubler are bonded together so that the panel 1 is produced. The formed panel 1 undergoes non-destructive inspection, for example by detecting inclusions of air, to check whether the panel meets the quality requirements (32). If the inspection is passed, the panel undergoes mechanical testing (33).

[0083] After this material-removal machining, the panel undergoes finishing (40), including levelling of the surface and closing of various openings and cavities in the panel (41). Before the panel can be transported (43) to the assembly station, the panel is provided with a coat of paint (42).

[0084] FIG. 3 shows a block diagram 100 of the manufacturing process for a panel 200 with doubler 310 according to the invention. FIG. 4 shows a stack 300 of layers on a jig 400 during manufacture of the panel 200 according to the invention. The manufacturing process again starts with preparation 101 of the various components of the final panel 200. These components comprise the layers of metal and the layers of fibres embedded in a precursor of an adhesive that make up the laminated skin 301 and the doubler 310 of the panel 200. After the preparatory steps 101, first the layers for forming the doubler 310 are stacked on one another (step 102). During stacking of the layers for the doubler 310, the layers of metal and the layers of fibres are stacked on one another in such a way that in each case at least one layer of fibres embedded in a precursor of an adhesive is included between two layers of metal.

[0085] The stack for forming the doubler 310 is put in an autoclave (103), in which, under the effect of pressure and heat, the precursor of the adhesive in the layers of fibres is activated and the layers of metal and the layers of fibres are bonded together so that the laminated doubler 310 is produced. The formed doubler 310 undergoes non-destructive inspection, for example by detecting inclusions of air, to check whether the laminate meets the quality requirements (104). If the inspection is passed, the doubler undergoes material-removal machining (105), for example to make a precursor of the final form of the doubler. The doubler 310 is to be understood as the doubler shown 311 and the further doublers 312, 313, 314, 315, 316. These various doublers 311-316 form the complete doubler 310. At least one layer of fibres embedded in a precursor of an adhesive is placed in each case between two doublers 311-316, to form a supplementary adhesive layer between the doublers after activation.

[0086] Then the layers for forming the laminated skin 301 are stacked on one another (110). During stacking of the layers for forming the skin 301, the layers of metal and the layers of fibres are stacked on one another in such a way that in each case at least one layer of fibres embedded in a precursor of an adhesive is included between two layers of metal. A further layer of fibres embedded in a precursor of an adhesive is placed on the stack of the layers for the skin 301 (see FIG. 5). Then the doubler 310 is placed on this further layer of fibres, so that the further layer of fibres forms an intermediate layer between the stack and the doubler 310.

[0087] The stack for forming the skin 301, the intermediate layer and the doubler 310 is put in an autoclave (111), in which, under the effect of pressure and heat, the precursor of the adhesive in the layers of fibres is activated and the layers of metal and the layers of fibres of the stack are bonded together so that a laminated skin 301 is produced. Furthermore, the precursor of the adhesive in the intermediate layer is activated so that the doubler is bonded to an outermost layer of metal of the laminated skin and the panel 200 is formed. The formed panel 200 undergoes non-destructive inspection, for example by detecting inclusions of air, to check whether the panel 1 meets the quality requirements (112). If the inspection is passed, the laminated skin undergoes material-removal machining (113) to obtain the final form of the panel.

[0088] After this material-removal machining, the panel undergoes mechanical testing (106) and then finishing (130), including levelling of the surface and closing of various openings and cavities in the panel (131). Before the panel can be transported (133) to the assembly station, the panel is provided with a coat of paint (132).

[0089] As shown in FIG. 3, steps 121, 122, 123 under block 120 are omitted. This means that in the manufacturing process according to the invention, compared to that according to the prior art from FIG. 1, at least one stacking step 121, an autoclave step 122 and an inspection step 123 are omitted.

[0090] FIG. 5 shows a cross-section of the panel 200 provided with the doubler 310 according to the invention. The complete doubler 310 consists of a single doubler 311. The doubler 311 comprises two layers of metal 320 between which there are two fibre-reinforced adhesive layers 321. The doubler 311 is provided on a laminated skin 301 that is formed from two layers of metal 304 with two fibre-reinforced adhesive layers 303 between them. The doubler 311 is bonded to the laminated skin 301 by means of the supplementary adhesive layer 340. This supplementary adhesive layer 340 consists of two fibre-reinforced intermediate adhesive layers 341. As shown in FIG. 5, the final perimeter 342 of the intermediate layers 341 is set back from the perimeter 322 of the doubler 311. The space 343 that is thus created between the doubler 311 and the laminated skin 301 is filled with a layer of glue 330. This layer of glue 330 prevents the doubler 311 becoming detached at the perimeter 322 from the laminated skin 301 through detachment of the supplementary adhesive layer 340 from the laminated skin 301. The layer of glue 330 extends beyond the perimeter 322 of the doubler 311 and covers it on the full thickness.

[0091] FIG. 6 shows a perspective view of the inside of a panel 200 provided with a doubler 310 comprising several strengthening layers 311-316, such as for an aircraft fuselage, according to the invention. After manufacture of the panel 200 in the autoclave, the doubler 310 does not yet have the final form for assembly. After manufacture, the panel 200 comprises two parts 350, 360. A first part 350 is provided with positioning openings 370 (shown in FIG. 7 and shown schematically in FIG. 6), which for manufacturing the panel 200 are provided in the layers of the stack for forming the laminated skin and in the one or more doublers 311-316 that form the doubler 310. Positioning pins 380 are provided in the jig 400, see FIG. 7, which are included in the positioning openings 370 of the various components during stacking in the jig 400. The interaction between the positioning pins 380 and the positioning openings 370 provides good mutual alignment or positioning of the layers 304, 303 in the stack and of the stack with the doubler 310. After manufacture of the panel 200, the first part 350, provided with the positioning openings, will be removed by material-removal machining from the second part 360. This second part 360 of the panel 200 then forms the panel ready for assembly.

[0092] FIG. 7 shows a cross-section of the panel according to line VII-VII in FIG. 6. The cross-section shows the panel 200 placed on the jig 400, wherein the jig 400 is provided with a positioning pin 380. The laminated skin 301, consisting of layers of metal 304 with a fibre-reinforced adhesive layer (not shown) in each case between two layers of metal, is provided with a positioning opening 370, into which the positioning pin 380 of the jig 400 fits. The complete doubler 310 comprises several doublers 311-314. In each case between two doublers 311-314, a supplementary adhesive layer 340 is provided for bonding between two doublers. Furthermore, a supplementary adhesive layer 340 of this kind is provided between the complete doubler and the laminated skin 301.

[0093] The complete doubler is provided with a positioning opening 370 for receiving the positioning pin 380. This ensures that the complete doubler and the layers of the laminated skin 301 are aligned relative to one another. The positioning openings 370 are provided in the first part 350 of the panel 200, which after machining is removed from the second part 360 along the machining line 302. The second part 360 of the panel 200 then forms the panel ready for assembly.