A manufacturing method of a fuselage shell

Abstract

The present invention relates to the technical field of aircraft, and discloses a manufacturing method for an aircraft fuselage shell, comprising the following steps: designing an aviation model to determine the size and shape of the fuselage shell; disassembling the fuselage shell into multiple structural components; obtaining the cross-sectional profiles of the two end faces of each structural component and drawing the outer contour processing drawings and the inner contour processing drawings; manufacturing an auxiliary plate according to the outer contour processing drawings and printing the paper patterns of the inner contour processing drawings; manufacturing the annular structures of each structural component by using the auxiliary plate and the paper patterns; finely processing the multiple annular structures and bonding them in sequence to form a fuselage; and performing overall polishing and grinding on the fuselage. The present invention is applicable to complex curved surface structures and large parts, does not require mold opening, and can be manufactured by itself. It has low cost, short cycle, simple manufacturing, is convenient for modification and replacement, and is applicable to the rapid verification stage of aircraft. At the same time, compared with manual mechanical cutting, it does not generate debris, has relatively high processing accuracy, and fast processing efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft, and particularly to a manufacturing method for an airframe shell. Background Art

[0002] The development of each new type of aircraft requires a large number of design iterations. As an important method in the aircraft design and manufacturing process, the aircraft model is used to verify the flight performance of the aircraft, and its processing and manufacturing method is very crucial.

[0003] Currently, there are three common manufacturing methods for the airframe of aircraft models:

[0004] ① CNC manufacturing, which refers to computer numerical control precision machining. Through fine engraving, the processing quality is stable, the processing accuracy is high, and the repeat accuracy is high, meeting the processing requirements of aircraft (such as patent CN201910546896.6).

[0005] ② 3D printing manufacturing, which is a new type of rapid prototyping technology. Based on digital model files, materials are printed and stacked layer by layer using methods such as laser beams and hot melt nozzles to construct objects (such as patent CN201910996790.6).

[0006] ③ Manual manufacturing, usually manually engraving and cutting structural lines on a KT board (polyethylene), cutting flat components and then pasting and assembling them, with a high degree of personalization. The shaping of the curved surface is achieved by bending or folding the board (such as patent CN202220430669.4).

[0007] However, CNC manufacturing and 3D printing manufacturing usually require commissioning a factory to make a mold, which is costly and has a long production cycle. In addition, limited by the printing size of 3D printers, 3D printing is currently mainly used for the production of components and the assembly type fuselage production of some small fixed-wing aircraft models, and is not suitable for the production of the fuselage of large aircraft models. Manual manufacturing has low precision and low efficiency, and it is difficult to process complex curved surfaces such as streamlined fuselages. The curved surface is uneven, the overall realism is poor, and the mechanical strength of the whole model is not strong.

[0008] The overall size of the fuselage of a large aircraft is large, the outer shape is a complex curved surface, and the inside is often a hollow structure. The overall processing difficulty is large. Currently, it still mostly relies on factory CNC manufacturing, lacking a manufacturing method with high efficiency and low cost suitable for the rapid verification stage of the aircraft model fuselage. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides a manufacturing method for an airframe shell, which is applicable to large complex curved surface fuselages, and improves manufacturing precision and efficiency while reducing manufacturing costs.

[0010] The technical solution adopted by the present invention to solve its technical problems is:

[0011] A manufacturing method for a fuselage shell, comprising the following steps:

[0012] Design an aircraft model to determine the size and shape of the fuselage shell;

[0013] Disassemble the fuselage shell into multiple structural members;

[0014] Obtain the cross-sectional profiles of the two end faces of each structural member, and draw the outer contour processing drawing and the inner contour processing drawing;

[0015] Manufacture an auxiliary plate according to the outer contour processing drawing, and print the paper pattern of the inner contour processing drawing;

[0016] Use the auxiliary plate and the paper pattern to manufacture the annular structures of each structural member;

[0017] Precision machine the multiple annular structures and bond them together in sequence to form the fuselage;

[0018] Perform overall polishing and grinding on the fuselage.

[0019] Preferably, when determining the size and shape of the fuselage shell, obtain multiple fuselages through over-design, model using Solidworks and conduct aerodynamic simulation comparison through ANSYS Fluent, and select the most suitable fuselage shape.

[0020] Preferably, when disassembling the fuselage shell into multiple structural members, according to the fuselage shape, divide the fuselage curve into several curve segments with small curvature and approximate straight lines, and then disassemble the fuselage into several hollow structural members similar to truncated cones.

[0021] Preferably, the thickness of each segment is 1.2 to 1.5 times the curvature radius of the fuselage outer shape of this segment, and the curvature radius takes the minimum value of the curvature radius within the fuselage segment.

[0022] Preferably, if the outer shape of the fuselage structural member has no curvature, the length of this structural member is selected to be 60 - 100 mm.

[0023] Preferably, after obtaining the cross-sectional profiles of the two end faces of each structural member, export the engineering drawings in two-dimensional formats such as dxf and dwg, mark the serial numbers and positioning holes within the cross-sectional profiles, edit and typeset with AutoCAD, and draw the outer contour processing drawing and the inner contour processing drawing.

[0024] Preferably, the positioning holes are three round holes, and the three round holes are distributed in a triangle;

[0025] Or the positioning hole is a polygon hole.

[0026] Preferably, manufacturing the annular structure includes the following steps:

[0027] Select polystyrene - high - density microcellular foamed foam, first perform rough machining to form a foam board with the thickness of the multi - segment structural member;

[0028] Then align the positioning holes with the auxiliary board and fix it at both end cross - sections of the foam board;

[0029] Take a hand - held cutting machine and use a hot cutting wire to cut the foam board along the outer contour of the auxiliary board to form multi - segment frustum - shaped structural bodies;

[0030] Attach the paper pattern to both ends of the auxiliary corresponding frustum - shaped structural member, pass the hot cutting wire through both end cross - sections, and cut along the inner contour of the fuselage structural member shown by the paper pattern to form an annular structural body.

[0031] Preferably, the fuselage structural member that needs to place internal parts is temporarily bonded to the adjacent fuselage structural member with double - sided tape, and then bonded after the internal parts of the fuselage are adjusted.

[0032] A manufacturing method of a fuselage shell according to an embodiment of the present invention, compared with the prior art, its beneficial effects are as follows: The present invention uses multi - segment line fitting curves, simplifies the complex and breaks the whole into parts, is applicable to complex curved surface structures and large parts, does not require mold opening, and can be made by itself. It has low cost, short cycle, simple manufacturing, is convenient for modification and replacement, and is applicable to the rapid verification stage of aircraft. At the same time, compared with manual mechanical cutting, electro - thermal cutting basically does not generate debris, and has relatively high processing accuracy and fast processing efficiency. Brief Description of the Drawings

[0033] Figure 1 It is a process flow chart of the manufacturing method of the fuselage shell of the present invention.

[0034] Figure 2 It is a schematic diagram of the outer contour of the structural member.

[0035] Figure 3 It is a schematic diagram of the inner contour of the structural member. Detailed Description of the Embodiment

[0036] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but do not limit the scope of the present invention.

[0037] As Figure 1 shown, a manufacturing method of a fuselage shell according to a preferred embodiment of an embodiment of the present invention includes the following steps:

[0038] Design an aircraft model to determine the size and shape of the fuselage shell;

[0039] The shape and size of the fuselage shell are restricted by the sizes of the driving mechanism and the flapping mechanism. Considering material, the fixing method of the fuselage skeleton, the strength of the shell, the elastic requirements, and the requirements for reducing the weight of the UAV, an appropriate shell thickness is selected.

[0040] When determining the size and shape of the fuselage shell, multiple fuselages are obtained through over-design, modeled using Solidworks, and aerodynamic simulations are carried out and compared through ANSYS Fluent to select the most suitable fuselage shape.

[0041] In this embodiment, taking a specific fuselage as an example, the maximum size reference of its fuselage cross-section is formulated based on the carbon plate of the flapping aircraft frame, and the fuselage length is set to about 500 mm.

[0042] In this embodiment, the fuselage shape is a streamlined structure. The upper side is relatively flat, and the lower side presents a convex surface that is narrow at the front, wide in the middle, and narrow at the rear. The fuselage thickness is mainly 10 mm, and fixing holes for the carbon tube skeleton are reserved inside the fuselage. Since the fuselage shape is an irregular streamline, when modeling with Solidworks, it is divided into 17 segments with 30 mm for each segment, and lofting and stretching are carried out based on 18 reference planes to obtain the three-dimensional model of the fuselage shell. Based on 30 mm, segmental modeling of the fuselage can realize the simulation of the fuselage shell model and facilitate the adjustment of the segmental thickness of the structural members in subsequent steps.

[0043] The fuselage shell is disassembled into multiple structural members;

[0044] According to the fuselage shape, the fuselage curve is divided into several curve segments with small curvature and approximately straight lines, and then the fuselage is disassembled into several hollow structural members similar to truncated cones. The thickness of each segment is 1.2 - 1.5 times the curvature radius of the fuselage shape of this segment, such as 4 / 3 times. And the curvature radius is taken as the minimum value of the curvature radius within the fuselage segment. If the shape of the fuselage structural member has no curvature, the length of this structural member is selected to be 60 - 100 mm.

[0045] In this embodiment, when disassembling the fuselage shell, the segmental thickness is adjusted according to the fuselage arc. The shape of the middle part of the fuselage is uniform and has no curvature, and the segmental thickness is increased accordingly (78 mm). The shape of the fuselage head is complex, and the segmental thickness is thinned accordingly.

[0046] Obtain the cross-sectional profiles of the two end faces of each structural member, and draw the outer contour processing drawing and the inner contour processing drawing;

[0047] After obtaining the cross-sectional profiles of the two end faces of each structural member, export engineering drawings in two-dimensional formats such as dxf and dwg, mark the serial numbers and positioning holes within the cross-sectional profiles, edit and typeset with AutoCAD, and draw the outer contour processing drawing and the inner contour processing drawing (such as Figure 2 、 3 ).

[0048] The positioning holes are three round holes, and the three round holes are distributed in a triangular shape; or the positioning hole is a polygon hole, which is convenient for fixing two adjacent cross-section auxiliary plates during processing.

[0049] Manufacture the auxiliary plate according to the outer contour processing drawing, and print the pattern of the inner contour processing drawing;

[0050] According to the outer contour processing drawing, use the laser cutting method to make the auxiliary plate from basswood. The auxiliary plate is a closed surface surrounded by the outer contour of the cross section (refer to Figure 2 ). The surface of the fuselage shell will affect the aerodynamic characteristics of the aircraft, and high processing accuracy is required. Therefore, basswood is used for assistance.

[0051] In contrast, the processing accuracy required for the inside of the fuselage is lower. Printing the pattern of the inner contour processing drawing can meet the requirements. The pattern is used to assist in cutting the inner contour of the fuselage structure members.

[0052] Use the auxiliary plate and the pattern to make the ring-shaped structures of each section of the structural members, including the following steps:

[0053] Select polystyrene-high density microcellular foamed foam, and first perform rough machining to form a foam board with the thickness of the multi-section structural members;

[0054] Then align the positioning holes with the auxiliary plate and fix them at both ends of the cross section of the foam board;

[0055] Take a hand-held cutting machine and use a hot cutting wire to cut the foam board along the outer contour of the auxiliary plate to form multi-section frustum-shaped structures;

[0056] Attach the pattern to both ends of the auxiliary corresponding frustum-shaped structural members, pass the hot cutting wire through both ends of the cross section, and cut along the inner contour of the fuselage structural members shown by the pattern to form ring-shaped structures.

[0057] The advantage of using a hand-held rather than a bench cutting machine is that it is convenient for observation, and it is easy to closely adhere to the auxiliary plate or the pattern, more flexible, and has higher processing accuracy.

[0058] Three lines can be marked on each ring-shaped structure and arranged in order according to the serial numbers, which is convenient for alignment during assembly.

[0059] Fine process the multi-section ring-shaped structures and bond them together in sequence to form the fuselage;

[0060] According to the model design drawing, finely process the formed fuselage structure and decorate the side surfaces of the ring-shaped structures. In this embodiment, there are parts of the fuselage skeleton extending out of the fuselage, and grooves need to be opened at the corresponding positions; the tail is relatively long, and it needs to be hollowed out at the tail end to avoid affecting the pitch of the tail wing.

[0061] If parts such as the internal fuselage skeleton and the drive mechanism need to be installed, this step is carried out.

[0062] Bond the multi-segment annular structures in sequence with special foam glue.

[0063] During the testing phase, since the internal parts of the fuselage need to be continuously adjusted, the middle fuselage structure for placing the internal parts and the adjacent fuselage structures can be temporarily bonded with double-sided tape, which can take into account both easy disassembly and overall strength. After the internal parts of the fuselage are adjusted, they can be bonded again.

[0064] Overall polish the fuselage with sandpaper to make the appearance more beautiful and the connection of each structural member smoother.

[0065] The manufacturing method of the fuselage shell based on the above technical features adopts multi-segment line fitting curves, simplifies the complex and breaks the whole into parts. It is applicable to complex curved surface structures and large parts, does not require mold opening, and can be made by oneself. It has low cost, short cycle, simple manufacturing, is convenient for modification and replacement, and is applicable to the rapid verification phase of the aircraft. At the same time, compared with manual mechanical cutting, electrothermal cutting basically does not generate debris, and has relatively high processing accuracy and fast processing efficiency.

[0066] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and replacements can be made, and these improvements and replacements should also be regarded as the protection scope of the present invention.

Claims

1. A manufacturing method of a fuselage shell, characterized in that: It includes the following steps: Design an aircraft model and determine the size and shape of the fuselage shell; Disassemble the fuselage shell into multiple structural components; Obtain the cross-sectional profiles of the two end faces of each structural component, draw the outer contour processing drawings and inner contour processing drawings, and mark the serial numbers and positioning holes within the cross-sectional profiles; Make auxiliary plates according to the outer contour processing drawings and print the paper patterns of the inner contour processing drawings; Use the auxiliary plates and paper patterns to make the annular structures of each structural component; Precision machine the multiple annular structures and bond them in sequence to form the fuselage; Perform overall polishing and grinding on the fuselage; When disassembling the fuselage shell into multiple structural components, according to the fuselage shape, divide the fuselage curve into several curve segments with small curvature and approximate straight lines, and then disassemble the fuselage into several hollow structural components similar to truncated cones; The thickness of each segment is 1.2 - 1.5 times the curvature radius of the outer shape of that segment of the fuselage, and the curvature radius is taken as the minimum curvature radius within the fuselage segment; Making the said annular structure includes the following steps: Select polystyrene-high density microcellular foamed foam, first perform rough machining to form a foam board with the thickness of the multiple structural components; Then align the positioning holes with the auxiliary plates and fix them at the two end cross-sections of the foam board; Adopt a hand-held cutting machine, use a hot cutting wire to cut the foam board along the outer contour of the auxiliary plate to form multiple truncated cone-shaped structures; Attach the paper pattern to the two ends of the corresponding truncated cone-shaped structure, pass the hot cutting wire through the two end cross-sections, and cut along the inner contour of the fuselage structure shown by the paper pattern to form an annular structure.

2. The manufacturing method of the fuselage shell according to claim 1, characterized in that: When determining the size and shape of the fuselage shell, obtain multiple fuselages through over-design, model them using Solidworks and conduct aerodynamic simulation and comparison through ANSYS Fluent to select the most suitable fuselage shape.

3. The manufacturing method of the fuselage shell according to claim 1, characterized in that: After obtaining the cross-sectional profiles of the two end faces of each structural component, export the engineering drawings in dxf and dwg two-dimensional formats, edit and typeset them with AutoCAD, and draw the outer contour processing drawings and inner contour processing drawings.

4. The manufacturing method of the fuselage shell according to claim 3, characterized in that: The positioning holes are three round holes, and the three round holes are distributed in a triangle; Or the positioning hole is a polygon hole.

5. The manufacturing method of the fuselage shell according to claim 1, characterized in that: For the fuselage structural components that need to place internal parts, temporarily bond them with the adjacent fuselage structural components using double-sided tape, and then bond them after the internal parts of the fuselage are adjusted.

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