METHOD FOR THE ASSEMBLY OF FRAMES IN AN AIRCRAFT SHELL

Abstract

A method for the assembly of frames in an aircraft shell, wherein the aircraft shell comprises a skin and a plurality of stringers co-cured with the skin, wherein the skin has a plurality of reference marks. Identifying the reference marks on the skin using a first robot with artificial vision, establishing a local reference for the positioning of each frame based on a reference mark, grabbing a frame using the first robot, establishing a relative position between the first robot and the frame based on the reference mark, positioning the frame on an inner side of the aircraft shell using the first robot, and with a second robot, drilling holes through the frame and skin, and attaching the frame to the skin with fasteners.

Claims

1. A method for an assembly of frames in an aircraft shell, wherein the aircraft shell comprises a skin and a plurality of stringers co-cured with the skin, wherein the skin has a plurality of reference marks, the method comprising the following steps: (a) identifying the reference marks on the skin using a first robot with artificial vision on board; (b) establishing a local reference for the positioning of each frame based on at least one reference mark; (c) grabbing a frame using the first robot; (d) establishing a relative position between the first robot and the frame based on at least one reference feature of the frame; (e) positioning the frame on an inner side of the aircraft shell using the first robot; (f) drilling holes through the frame and skin; and (g) attaching the frame to the skin with fasteners; wherein steps (f) and (g) are performed by a second robot.

2. The method according to claim 1, wherein steps (f) and (g) are performed by the second robot working from an outer side of the aircraft shell while the first robot holds the frame in place on the inner side of the aircraft shell.

3. The method according to claim 1, wherein the at least one reference feature of the frame is a mark, a contour of the frame, a hole or a combination thereof

4. The method according to claim 1, wherein step (g) comprises a first sub-step of installing temporary fasteners and a second sub-step of installing final fasteners.

5. The method according to claim 4, wherein step (f) comprises a first sub-step of drilling holes up to a first diameter for installing temporary fasteners and a second sub-step of drilling holes up to a second diameter for installing final fasteners, the second diameter being different from the first diameter.

6. The method according to claim 1, wherein step (b) further comprises recording the established local reference.

7. The method according to claim 1, wherein the skin is made of composite material.

8. The method according to claim 7, wherein the composite material comprises carbon fiber reinforced polymer.

9. The method according to claim 1, wherein steps (b) to (g) are repeated to assembly a plurality of frames.

10. The method according to claim 1, wherein the aircraft shell is of full barrel type, and wherein the method comprises, once the frames of a first portion of the aircraft shell have been assembled, rotate the aircraft shell and perform steps (a) to (g) to assemble at least one frame of a second portion of the aircraft shell.

11. The method according to claim 1, wherein the reference marks are engraved on the skin.

12. The method according to claim 11, wherein the reference marks are performed onto the skin during a curing process.

13. A method for the manufacturing of an aircraft shell with frames, the method comprising the following steps: (i) positioning a plurality of stringers in a male mandrel, the male mandrel comprising pocket allocations for receiving the stringers, and laying up on the male mandrel a skin, the male mandrel comprising at least one of projections or indentations for performing a plurality of reference marks onto the skin; (ii) co-curing the skin with the stringers, thus obtaining an aircraft shell; (iii) removing the aircraft shell from the male mandrel and fixing the aircraft shell (1) to avoid movement thereof; and (iv) assembling at least one frame in the aircraft shell; wherein the assembly of at least one frame is performed according to the method of claim 1.

14. The method for the manufacturing of an aircraft shell according to claim 13, wherein the projections or the indentations are dent line shaped.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] These and other characteristics and advantages of the invention will become clearly understood in view of the detailed description of the invention which becomes apparent from a preferred embodiment of the invention, given just as an example and not being limited thereto, with reference to the drawings.

[0070] FIG. 1 shows a mark performed according to a process of the state of the art.

[0071] FIG. 2 schematically shows the position of three tooling holes in an aircraft skin according to a process of the state of the art.

[0072] FIG. 3 shows reference marks on the skin of an aircraft shell.

[0073] FIG. 4 schematically shows part of a method for the assembly of frames according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0074] The present invention provides a method for the assembly of frames (4) in an aircraft shell (1), wherein the aircraft shell (1) comprises a skin (2) and a plurality of stringers (3) co-cured with the skin (2). An embodiment of an aircraft shell (1) is shown in FIG. 3.

[0075] As visible in FIG. 3, the inner side of the skin (2) has a plurality of reference marks (5). The inner side of the skin (2) will be understood as the side intended for placing the frames (4), whereas the outer side of the skin (2) is the opposite side. In FIG. 3 the aircraft shell (1) is of full barrel type and the inner side of the skin (2) is the side defining the inner of the barrel shape and provided with stringers (3). In an embodiment the skin (2) is made of CFRP. In an embodiment the stringers (3) are omega stringers.

[0076] The method of the invention comprises the following steps:

[0077] (a) identifying the reference marks (5) on the skin (2) using a first robot (6) with artificial vision on board;

[0078] (b) establishing a local reference for the positioning of each frame (4) based on at least one reference mark (5);

[0079] (c) grabbing a frame (4) using the first robot (6);

[0080] (d) establishing a relative position between the first robot (6) and the frame (4) based on at least one reference feature of the frame (4);

[0081] (e) positioning the frame (4) on an inner side of the aircraft shell (1) using the first robot (6);

[0082] (f) drilling holes through the frame (4) and skin (2); and

[0083] (g) attaching the frame (4) to the skin (2) with fasteners;

[0084] wherein steps (f) and (g) are performed by a second robot (7).

[0085] Thus, according to the present invention, a first robot (6) with artificial vision on board identifies the reference marks (5) present on the skin (2) of the aircraft shell (1). The reference marks (5) are preferably performed during a curing process of the skin (2) with the stringers (3) to form the aircraft shell (1).

[0086] The known process for manufacturing an aircraft shell (16) involves performing marks (12) on the skin (11) of the aircraft shell (16). A detailed view of a skin (11) and marks (12) performed according to the state of the art are shown in FIG. 1. The marks (12) are used in the state of the art to perform tooling holes (13, 14, 15). FIG. 2 shows an aircraft shell (16) produced according to the state of the art, where the position of three tooling holes (13, 14, 15) is shown. The tooling holes (13, 14, 15) are used to fix the aircraft shell (16) to a jig using tooling pins, for positioning and carrying the aircraft shell (16) and keeping the aircraft shell geometry during the assembly of the frames.

[0087] According to the present invention, reference marks (5) are not used to perform tooling holes for fixing and carrying the aircraft shell. Instead, reference marks (5) are used as a visual reference for positioning the frames (4). In the present invention reference marks present on the skin are identified using a first robot (6) with artificial vision on board. FIG. 4 schematically shows part of a method for the assembly of frames according to an embodiment of the present invention, where the first robot (6) is visible. Based on at least one identified reference mark (5), a local reference is established for the positioning of each frame (4). This involves defining the position of the first robot (6) relative to the aircraft shell (1) for the positioning of each frame (4). Preferably, the local reference is recorded and/or controlled with a controller to ensure that the first robot (6) is able to repeat it.

[0088] A frame (4) to be assembled is grabbed using the first robot (6) and a relative position between the first robot (6) and the frame (4) is established based on at least one reference feature of the frame (4). The reference feature of the frame (4) shall be understood as any feature of the frame visually detectable by the first robot (6), such as a mark, a contour of the frame, a hole or any combination thereof In an embodiment, the frames (4) are aluminum frames and machine contours of holes present in the frames (4) are used as reference features. A single reference feature or a combination of reference features may be used.

[0089] Once the relative position between the first robot (6) and the frame (4) is established, the first robot (6) positions the frame (4) on an inner side of the aircraft shell (1). FIG. 4 shows the first robot (6) holding a frame (4) positioned on the inner side of the aircraft shell (1). As visible in FIG. 4, a platform may be placed to facilitate movement of the first robot (6) along a longitudinal direction of the barrel-type aircraft shell (1).

[0090] While the first robot (6) holds the frame (4) in place, a second robot (7) drills holes through the frame (4) and the skin (2). The holes are used to attach the frame (4) to the skin (2) with fasteners, such as bolts. FIG. 4 schematically shows an embodiment where the first robot (6) holds a frame (4) in place on the inner side of the aircraft shell (1) while a second robot (7) working from an outer side of the aircraft shell (1) drills holes through the frame (4) and skin (2) and attaches the frame (4) to the skin (2) with fasteners. FIG. 4 shows a view of the process where several frames (4) have been already assembled. Assembly of several frames (4) may be performed by repeating steps (b) to (g) for each frame (4).

[0091] In an embodiment, the position of the second robot (7) is established based on the position of the first robot (6) and/or on a local reference for the positioning of a frame. According to this embodiment, the first robot (6) itself and/or a controller sends data to the second robot (7), the data comprising the position of the first robot (6) and/or the local reference for the positioning of the frame already established. The second robot (7) establishes its own position based on the location of the first robot and/or on the local reference in order to drill holes through the skin (2) and the frame (4) hold by the first robot (6).

[0092] In an embodiment, step (f) of drilling comprises a first sub-step of drilling holes up to a first diameter for installing temporary fasteners and a second sub-step of drilling holes up to a second diameter for installing final fasteners, the second diameter being different from the first diameter. Also, in an embodiment, step (g) comprises a first sub-step of installing temporary fasteners and a second sub-step of installing final fasteners. The installation of temporary fasteners for temporary securing the frames (4) allows the first robot (6) to initiate picking and positioning of a subsequent frame (4) while the second robot (7) finishes the attachment of a previous frame (4) by installing the final fasteners. In an embodiment the number of temporary fasteners is at least 20% the number of the final fasteners.

[0093] In the embodiment shown in FIG. 4 the aircraft shell (1) is of full barrel type. In an embodiment, the method comprises assembling the frames (4) of a first portion of the aircraft shell (1), such as a first half of the aircraft shell (1), rotating the aircraft shell (1) and performing steps (a) to (g) to assemble one or several frames (4) of a second portion of the aircraft shell, such as a second half of the aircraft shell.

[0094] Although the invention has been described for a full barrel type shell, it will be understood that the method of the invention is applicable to any type of aircraft shells (1).

[0095] The present invention also provides a method for the manufacturing of an aircraft shell (1) with frames (4), the method comprising the following steps:

[0096] (i) positioning a plurality of stringers (3) in a male mandrel, the male mandrel comprising pocket allocations for receiving the stringers (3), and laying up on the male mandrel a skin (2), the male mandrel comprising projections and/or indentations for performing a plurality of reference marks (5) onto the skin (2);

[0097] (ii) co-curing the skin (2) with the stringers (3), thus obtaining an aircraft shell (1);

[0098] (iii) removing the aircraft shell (1) from the male mandrel and fixing the aircraft shell (1) to avoid movement thereof; and

[0099] (iv) assembling at least one frame (4) in the aircraft shell (1);

[0100] wherein the assembly of at least one frame (4) is performed according to the method of the first inventive aspect.

[0101] In an embodiment, the projections and/or indentations are dent line shaped.

[0102] While at least one exemplary embodiment of the present invention(s) is disclosed herein, 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 this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.