METHOD, INJECTION MOULDING TOOL FOR MANUFACTURING A LEADING EDGE SECTION WITH HYBRID LAMINAR FLOW CONTROL FOR AN AIRCRAFT, AND LEADING EDGE SECTION WITH HYBRID LAMINAR FLOW CONTROL OBTAINED THEREOF

Abstract

This disclosure relates to the manufacturing of a leading edge section with hybrid laminar flow control for an aircraft. A manufacturing method involves: providing an outer hood, a plurality of elongated modules, first and second C-shaped profiles having comprising cavities, and an inner mandrel; assembling an injection moulding tool by placing each profile on each end of the inner mandrel, arranging a first extreme of each elongated module in one cavity of the first profile and a second extreme of the module in another cavity of the second profile, both cavities positioned in the same radial direction; and placing the hood on first and second profiles to close the tool. Further, the injection moulding tool is closed and filled with an injection compound comprising thermoplastic and short-fiber. Finally, the compound is hardened and demoulded.

Claims

1. A method for manufacturing a leading edge section with hybrid laminar flow control for an aircraft, the method comprising the steps of: providing a plurality of elongated modules; providing an inner mandrel shaped with an inner surface of an aerodynamic leading edge profile; providing an outer hood shaped with an outer surface of the aerodynamic leading edge profile; providing first and second C-shaped profiles comprising a plurality of passing-through cavities configured to receive the modules; assembling an injection moulding tool by a method comprising: placing the first profile on a first end of the inner mandrel, and the second profile on a second end of the inner mandrel, both profiles contacting the inner mandrel; arranging a first extreme of each elongated module in one cavity of the first profile, and a second extreme of said module in another cavity of the second profile, both cavities positioned in a same radial direction, and such arrangement leaving a lower gap defining the thickness of the inner surface of the leading edge section; and placing the hood on the first and second profiles to close the tool, leaving an upper gap defining the thickness of the outer surface of the leading edge section; closing the injection moulding tool; filling the closed injection moulding tool with an injection compound comprising resin and a reinforcing additive; demoulding after the hardening of the injection compound to obtain a leading edge section; and perforating the outer and the inner surface of said leading edge section to finally obtain a leading edge section with hybrid laminar flow control.

2. The method of claim 1, wherein assembling an injection moulding tool further comprises allocating a plurality of protuberances on the inner mandrel to retain the modules along its radial directions.

3. The method of claim 2, wherein the protuberances are placed in consecutive positions of different radial directions of the inner mandrel between its first and second ends, and wherein the protuberances are dimensioned to perforate the inner surface of the leading edge section to create suction holes for the venture effect.

4. The method of claim 2, wherein the protuberances are fixedly allocated on the inner mandrel.

5. The method of claim 2, wherein the protuberances are removable allocated on the inner mandrel, and wherein the demoulding step further comprises removing the protuberances from the hardened injection compound.

6. The method of claim 2, wherein the inner mandrel comprises notches for the allocation of the protuberances.

7. The method of claim 1, wherein the resin is a thermoplastic resin or a thermoset resin.

8. The method of claim 1, wherein the reinforcing additive comprises at least one of the following: glass fiber, short-fiber carbon fiber, medium fiber carbon fiber, large fiber carbon fiber, ceramic flakes, metal flakes, nanoparticles, nanotubes, and nanofibers.

9. A leading edge section with hybrid laminar flow control for an aircraft, the leading edge section comprising an outer surface, an inner surface, and obtained by injecting a compound comprising thermoplastic and short-fiber in a closed injection moulding tool, and said injection moulding tool comprising: an inner mandrel shaped with an inner surface of an aerodynamic leading edge profile and having first and second ends; an outer hood shaped with an outer surface of an aerodynamic leading edge profile; a plurality of elongated modules having a first and second extremes; and first and second C-shaped profiles comprising a plurality of passing-through cavities configured to receive the modules; wherein the first profile is placed on the first end of the inner mandrel, and the second profile is placed on the second end of the inner mandrel; wherein the first extreme of each elongated module is arranged in one cavity of the first profile, and the second extreme of the module in another cavity of the second profile, both cavities positioned in a same radial direction; wherein a lower gap is formed between both first and second profiles and the inner mandrel, said lower gap defining the thickness of the inner surface of the leading edge section; and wherein the outer hood is placed on the first and second profiles forming an upper gap between said first and second profiles and the outer hood, said upper gap defining the thickness of the outer surface of the leading edge section.

10. An injection moulding tool for manufacturing a leading edge section with hybrid laminar flow control for an aircraft, comprising: an inner mandrel having a first and second ends, and being shaped with an inner surface of an aerodynamic leading edge profile; an outer hood shaped with an outer surface of an aerodynamic leading edge profile; a plurality of elongated modules having a first and second extremes; and first and second C-shaped profiles comprising a plurality of passing-through cavities configured to receive the modules; wherein the first profile is placed on the first end of the inner mandrel, and the second profile on the second end of the inner mandrel; wherein the first extreme of each elongated module is arranged in one cavity of the first profile, and the second extreme of the module in another cavity of the second profile, wherein both cavities are positioned in the same radial direction, and wherein a lower gap between both the first and second profiles and the inner mandrel is formed, said lower gap defining the thickness of the inner surface of the leading edge section; and wherein the outer hood is placed on the first and second profiles forming an upper gap between both first and second profiles and the outer hood, said upper gap defining the thickness of the outer surface of the leading edge section.

11. The injection moulding tool of claim 10, wherein the inner mandrel further comprises a plurality of protuberances on the inner mandrel to retain the modules.

12. The injection moulding tool of claim 11, wherein the protuberances are placed in consecutive positions of different radial directions of the inner mandrel between its first and second ends, and wherein the protuberances are dimensioned to perforate the inner surface of the leading edge section to create suction holes for the venture effect.

13. The injection moulding tool of claim 11, wherein the protuberances are fixedly allocated on the inner mandrel.

14. The injection moulding tool of claim 11, wherein the protuberances are removable allocated on the inner mandrel.

15. The injection moulding tool of claim 11, wherein the inner mandrel comprises notches for the allocation of the protuberances.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Preferred embodiments of the invention are henceforth described with reference to the accompanying drawings, in which:

[0052] FIG. 1 shows a cross-sectional view of an schematic representation of a wing or lifting surface with a hybrid laminar flow configuration according to the prior art, wherein laminar and turbulent air flow is represented with thin lines on upper and lower surfaces.

[0053] FIG. 2a shows a cross-sectional view of a leading edge section with hybrid laminar flow control, as the one shown in FIG. 1.

[0054] FIG. 2b shows an enlarged view of a detailed section of the leading edge section shown in FIG. 2a.

[0055] FIG. 2c shows a perspective view of a leading edge section with hybrid laminar flow control, as the one shown in FIG. 1.

[0056] FIG. 3 schematically shows images of the assembling of the injection moulding tool for the manufacturing of a leading edge section of an aircraft.

[0057] FIG. 4 shows a further step of the assembling of the injection moulding tool, in which the C-shaped profiles are placed on the inner mandrel, and the elongated modules are retained into the cavities of the C-shaped profiles.

[0058] FIG. 5 shows a detailed view of the closed injection moulding tool.

[0059] FIG. 6 shows an inner mandrel for the manufacturing of a leading edge section of an aircraft, according to a preferred embodiment of the invention.

[0060] FIG. 7 shows an alternative for the joint of the outer and inner skins to obtain a leading edge section.

[0061] FIG. 8 shows another alternative for the joint of the stringers with one of the outer or inner skins to obtain the leading edge section.

DETAILED DESCRIPTION

[0062] The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

[0063] FIG. 3 shows the assembling of the injection moulding tool for manufacturing a leading edge section 1 with hybrid laminar flow control for an aircraft. According to embodiments of the invention, the manufacturing requires an outer hood 4 shaped with an outer surface 11 of the aerodynamic leading edge profile, a plurality of elongated modules 2 having a length equal to the span-wise dimension of the leading edge section 1 to be manufactured, first and second C-shaped profiles 5, 7 comprising a plurality of passing-through cavities 10 arranged around the profiles, and an inner mandrel 3 shaped with an inner surface 12 of an aerodynamic leading edge profile.

[0064] For the assembling, the first profile 5 is placed on a first end of the inner mandrel 3, and the second profile 7 is placed on a second end of the inner mandrel 3, both profiles 5, 7 surrounding the inner mandrel 3, such that the profiles 5, 7 are in contact with said inner mandrel 3.

[0065] Once the profiles 5, 7 have been positioned on the inner mandrel 3, the elongated modules 2 are arranged between each pair of radially corresponding cavities 10 of the profiles 5, 7, to retain and support the modules 2 over the inner mandrel 3. FIG. 4 shows the result of this arrangement.

[0066] The assembling of the injection moulding tool ends by placing the hood 4 on the first and second profiles 5, 7 to close the tool.

[0067] For the manufacturing of the leading edge section 1, the closed injection moulding tool is filled with an injection compound comprising resin and a reinforcing additive. After the hardening of the injection compound, the compound is demoulded to obtain the leading edge section 1.

[0068] Finally, the outer 11 and the inner surfaces 12 of the leading edge section 1 is perforated to thus obtain a leading edge section 1 with hybrid laminar flow control.

[0069] Exemplary embodiments of the invention allow the manufacture of a whole leading edge section with hybrid laminar flow control in a single injection process, allowing a significant manufacturing steps reduction. Thus, an embodiment of the invention provides a simpler manufacturing process that reduces the cost and time conventionally required.

[0070] FIG. 5 shows an enlarged schematic view of an upper part of the injection moulding tool after being closed. As shown, the elongated modules 2 are supported by the cavities 10 of the first and second profiles 5, 7. The cavities 10 are formed between the edges of the profile, thus allowing retaining the modules 2 separated from both the inner mandrel 3 and the outer hood 4.

[0071] Thus, the closed injection moulding tool comprises an upper gap 9 between both the first and second profiles 5, 7 and the outer hood 4, and a lower gap 8 between both the first and second profiles 5, 7 and the inner mandrel 3. The upper gap 9 defines the thickness of the outer surface 11 of the leading edge section 1 to be manufactured, and the lower gap 8 defines the thickness of the inner surface 12 of the leading edge section 1 to be manufactured.

[0072] Each pair of consecutive modules 2 is positioned to define the thickness of stringers 13. After filling the injection moulding tool with the injection compound, these stringers 13 will join the outer 11 and inner surfaces 12 of the leading edge section 1 forming chambers 16 therebetween.

[0073] According to a preferred embodiment, the inner mandrel 3 further can comprise a plurality of protuberances 14 placed on the inner mandrel 3 to retain the modules 2.

[0074] Preferably, the protuberances 14 are placed in consecutive positions of different radial directions of the inner mandrel 3 between its first and second ends, and the protuberances 14 are dimensioned to perforate the inner surface 12 of the leading edge section 1 to create suction holes 15 for the venture effect.

[0075] According to a preferred embodiment, the protuberances 14 are fixedly allocated on the inner mandrel 3. Alternatively, the protuberances 14 are removable allocated on the inner mandrel 3.

[0076] Preferably, the inner mandrel 3 comprises notches for the allocation of the protuberances 14. This notches easies the placing of the protuberances on the inner mandrel 3.

[0077] Further, according to another aspect, an embodiment of the invention also refers to an aircraft comprising the leading edge section with hybrid laminar flow control obtained as described.

[0078] Alternatively, the leading edge section 1 with hybrid laminar flow control can be obtained by producing two pieces, and clipping and welding these pieces together, applying pressure and temperature. These two pieces may consist on the inner skin and the stringers co-injected to the outer skin, or the outer skin and the stringers co-injected to the inner skin.

[0079] FIG. 7 shows the clipping system, which is based on pins 17 placed on the top of the stringers 13. These pins 17 are thinner but longer than the chamber to ensure not only positioning, but also chamber filling after welding.

[0080] This alternative manufacturing process requires simpler tooling, but later assembly steps.

[0081] Regarding the tooling, the C-shaped profiles can be removed, and in that case, the elongated modules can be positioned using the outer hood or the inner mandrel. If the inner mandrel provides recesses for positioning the modules, the stringers will be co-injected with the outer skin. Likewise, if the outer hood provides recesses for receiving the modules, the stringers will be co-injected with the inner skin. The attaching of these modules to the inner mandrel or to the outer hood can be done by mean of screws, or even by mean of magnets.

[0082] Another solution besides pins for the joint of the stringers with one of the outer or inner skins is the manufacturing of L-shaped stringers. In this case, it is not necessary to create holes to fit the pins in the other skin, but certain recess to ensure their positioning. FIG. 8 shows radialwise stringers co-injected to the outer skin.

[0083] The tooling for the manufacturing of L-shaped stringers can be also based on two separated pieces, one of them with co-injected stringers. For inner modules positioning it could be used the C-shaped profiles at the ends of the inner mandrel, but also the outer hood or the inner mandrel with recesses considering the shape of the elongated modules.

[0084] In addition, a step forward may include the integration of anti-erosion metallic sheet during injection of the outer skin. A surface treatment of metallic face in contact with plastic, as knurled, could improve adhesion between plastic and metallic sheet.

[0085] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope defined by the claims, which includes known equivalents and foreseeable equivalents at the time of filing this patent application.