Aircraft pelvic fin of foam sandwich structure and forming method of aircraft pelvic fin

Abstract

The invention discloses an aircraft pelvic fin of a foam sandwich structure and a forming method of the aircraft pelvic fin, the longitudinal section of the pelvic fin is of an acute triangle narrowing gradual change structure, the pelvic fin comprises a pelvic fin front section and a pelvic fin rear section which are formed by splicing, and the matching surface of the pelvic fin front section and an aircraft fuselage adopts shape following design; threaded holes used for fixing are formed in the matching faces of the front ventral fin section and the fuselage and the matching faces of the rear ventral fin section and the fuselage respectively, the front ventral fin section and the rear ventral fin section are alternately filled with foam filling blocks and nylon filling blocks respectively, and the upper end face of the front ventral fin section is fixedly connected with the fuselage of the aircraft through a fixing assembly. The lightweight design is created, the overall weight of the aircraft can be effectively reduced, and the flight efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft, and relates to an aircraft ventral fin with a foam sandwich structure and a molding method thereof. Background Art

[0002] With the continuous development of aerospace technology, the requirements for aircraft performance are increasing. As an important component of an aircraft, the ventral fin plays a key role in improving flight stability and controlling flight attitude. Traditional ventral fin materials have problems such as heavy weight, insufficient strength, poor corrosion resistance, difficulty in processing, and unsuitability for mass production, which restrict the performance improvement and mass production of aircraft. Therefore, it is of great significance to develop a new type of ventral fin material that is lightweight, high-strength, and corrosion-resistant. The purpose of the present invention is to provide a foam sandwich structure aircraft ventral fin to solve the problems existing in the prior art, which must not only ensure the use strength and rigidity, but also meet the weight requirements and better adapt to mass production. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide an aircraft ventral fin with a foam sandwich structure to solve the above-mentioned problems, so as to solve the problems that traditional ventral fins are heavy, insufficient in strength, poor in corrosion resistance, difficult to process, and unsuitable for mass production.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A ventral fin of an aircraft with a foam sandwich structure, wherein the longitudinal cross-section of the ventral fin is an acute-angled triangle with a gradually decreasing structure, the ventral fin comprises a front ventral fin section and a rear ventral fin section which are spliced ​​together, the mating surface between the front ventral fin section and the aircraft fuselage adopts a free-form design, threaded holes for fixation are respectively arranged on the mating surfaces between the front ventral fin section, the rear ventral fin section and the fuselage, the front ventral fin section and the rear ventral fin section are respectively alternately filled with foam filling blocks and nylon filling blocks, and the upper end surface of the front ventral fin section is fixedly connected to the aircraft fuselage through a fixing component.

[0006] Furthermore, a step matching structure is provided between the front section and the rear section of the ventral fin, a groove is provided on the middle part of the end surface of the front section of the ventral fin that is spliced ​​with the rear section of the ventral fin, and a protrusion that is integrated with it is provided on the middle part of the end surface of the rear section of the ventral fin that is spliced ​​with the front section of the ventral fin, and the protrusion matches the groove.

[0007] Furthermore, a connecting shaft for connecting to the aircraft fuselage is embedded in the foam filling block of the front section of the ventral fin. The upper end of the connecting shaft passes through the front section of the ventral fin and then passes through the aircraft fuselage and is fixedly connected to the aircraft fuselage by a fixing assembly.

[0008] Furthermore, the fixing assembly includes a thin nut, a clamping block and a gasket. After the clamping block is put on the upper end of the connecting shaft passing through the aircraft fuselage, a gasket is covered on top of it. The thin nut cooperates with the upper end thread of the connecting shaft. The thin nut presses the gasket and the clamping block in turn so that the clamping block presses the aircraft fuselage.

[0009] Furthermore, the pressing block is a cylindrical structure with a through hole in the middle, the pressing block has an annular cavity, the pressing block is a thin-walled structure with an opening at the upper end, and the gasket covers the upper end surface of the pressing block.

[0010] Furthermore, a plurality of reinforcing columns are arranged on the inner wall of the outer ring of the clamping block, and a cylindrical protrusion protruding from the reinforcing column is arranged on the top of the reinforcing column. A threaded countersunk hole matching the adjusting screw is opened on the lower end surface of the gasket at the cylindrical protrusion, and the adjusting screw is assembled to the gasket from the lower end of the gasket.

[0011] Furthermore, the outer diameter of the gasket is larger than that of the clamping block, the upper end of the connecting shaft is a step structure with a smaller outer diameter at the end, the inner hole of the gasket is larger than the outer diameter of the external thread at the upper end of the connecting shaft, and the inner hole of the gasket is smaller than the outer diameter of the lower part of the external thread section of the connecting shaft.

[0012] Furthermore, the foam filling block is made of PMI foam material, and the nylon filling block is made of nylon 1010 material.

[0013] Furthermore, threaded holes for connecting the front section and the rear section of the ventral fin with the aircraft fuselage are respectively opened at positions where nylon filling blocks are provided, and pin screw sleeves are respectively embedded in the threaded holes.

[0014] A method for forming a ventral fin of an aircraft with a foam sandwich structure, wherein the front section of the ventral fin comprises a front section skin of the ventral fin, the front section skin of the ventral fin is alternately filled with foam filling blocks and nylon filling blocks, the connecting shaft, the front section skin of the ventral fin, the foam filling blocks and the nylon filling blocks are formed into one body by a co-curing method, and the latch screw sleeve is a post-installation structure;

[0015] The rear section of the ventral fin includes a rear section skin of the ventral fin, and the rear section skin of the ventral fin is alternately filled with foam filling blocks and nylon filling blocks. The rear section skin of the ventral fin, the foam filling blocks and the nylon filling blocks are formed into one body through a co-curing method, and the latch screw sleeve is a post-installed structure.

[0016] The beneficial effects of the present invention are:

[0017] The invention creates a lightweight design, which can effectively reduce the overall weight of the aircraft and improve flight efficiency;

[0018] The invention has the characteristics of high strength and can enhance the structural strength and stability of the aircraft;

[0019] The invention has excellent corrosion resistance and can be applied to various harsh flight environments;

[0020] The manufacturing process created by the invention is simple, low in cost and convenient for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0023] Figure 2 It is a structural schematic diagram of the front section of the ventral fin without the skin of the front section of the ventral fin in an embodiment of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the ventral fin rear section without the ventral fin rear section skin in an embodiment of the present invention;

[0025] Figure 4 A longitudinal cross-sectional view of the front section of the pelvic fin of an embodiment of the present invention;

[0026] Figure 5 A schematic structural diagram of a connecting shaft according to an embodiment of the present invention;

[0027] Figure 6 Schematic diagram of the structure of a compression block according to an embodiment of the present invention.

[0028] Description of reference numerals:

[0029] 1. Front section of ventral fin; 11. Groove; 12. Front section of ventral fin skin; 2. Rear section of ventral fin; 21. Bump; 3. Fixing assembly; 31. Thin nut; 32. Washer; 33. Pressing block; 331. Reinforcing column; 332. Cylindrical protrusion; 34. Adjusting screw; 4. Connecting shaft; 5. Pin nut; a. Foam filling block; b. Nylon filling block. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0033] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0034] like Figures 1 to 6 As shown, a foam sandwich structure aircraft ventral fin includes a spliced ​​ventral fin front section 1 and a ventral fin rear section 2. The entire ventral fin is about 4 meters long, about 300 mm high, about 110 mm wide, and weighs 15-25 kg. The mating surface with the aircraft fuselage adopts a conformal design. The longitudinal section of the ventral fin is an acute triangle with a gradual reduction structure, which can effectively reduce air resistance, increase the heading stability of the aircraft, and offset part of the torque of the vertical tail lateral force on the aircraft fuselage.

[0035] A step matching structure is provided before the front section 1 and the rear section 2 of the ventral fin. A groove 11 is provided in the middle of the end face of the front section 1 of the ventral fin spliced ​​with the rear section 2 of the ventral fin. The groove 11 is 5-20mm deep. A convex block 21 is provided in the middle of the end face of the rear section 2 of the ventral fin spliced ​​with the front section 1 of the ventral fin. The convex block 21 is 5-20mm high. The convex block 21 matches with the groove 11, which not only plays a positioning role, but also effectively prevents the rear section 2 of the ventral fin from falling. The end face of the front section 1 of the ventral fin that matches with the yaw rudder is an arc surface. The matching surfaces of the front section 1 of the ventral fin, the rear section 2 of the ventral fin and the fuselage are provided with threaded holes to further fix the aircraft ventral fin of the foam sandwich structure. The upper end face of the front section 1 of the ventral fin is fixedly connected to the aircraft fuselage through a fixing component 3.

[0036] The front section 1 of the ventral fin includes a front section skin 12 of the ventral fin. The front section skin 12 of the ventral fin adopts a carbon wave hybrid composite material, which has the performance of carbon fiber and appropriately reduces the cost, so as to be suitable for mass production. The front section skin 12 of the ventral fin is alternately filled with foam filling blocks a and nylon filling blocks b. The foam filling block a adopts PMI foam material, which reduces the weight of the entire ventral fin while meeting the strength requirements. The nylon filling block b adopts nylon 1010 material, which strengthens the ventral fin and appropriately reduces the weight. In order to ensure the connection strength, a connecting shaft 4 for connecting with the fuselage is embedded in the foam filling block a, wherein the connecting shaft 4 is a high-strength aluminum alloy material, and the part of the connecting shaft 4 embedded in the foam area is designed as an inverted cone structure to improve the strength. The upper end of the connecting shaft 4 extends out of the front section 1 of the ventral fin and passes through the fuselage of the aircraft and is fixed by a fixing assembly 3. The threaded hole connecting the front section 1 of the ventral fin and the fuselage of the aircraft is opened at the position with the nylon filling block b. In order to ensure the connection strength, the threaded hole is embedded with a pin screw sleeve 5. The connecting shaft 4, the front section skin 12 of the ventral fin, the foam filling block a and the nylon filling block b are formed into one body through a co-curing method, and the latch screw sleeve 5 is a post-installation structure.

[0037] The fixing assembly 3 includes a thin nut 31, a clamping block 33 and a gasket 32. The clamping block 33 is sleeved on the upper end of the connecting shaft 4 passing through the aircraft fuselage, and is covered with a gasket 32. The thin nut 31 is threadedly matched with the upper end of the connecting shaft 4. The thin nut 31 locks the clamping block 33 so that the clamping block 33 presses the aircraft fuselage to fix the front section 1 of the ventral fin and the aircraft fuselage.

[0038] The pressing block 33 is a cylindrical structure with a through hole in the middle. In order to reduce the weight of the pressing block 33 , the pressing block 33 has an annular cavity. The pressing block 33 is a thin-walled structure with an opening at the upper end. The gasket 32 ​​covers the upper end surface of the pressing block 33 .

[0039] A plurality of evenly distributed reinforcing columns 331 are arranged on the inner wall of the outer ring of the pressing block 33, and the preferred number of reinforcing columns 331 is 4. The top of the reinforcing column 331 is provided with a cylindrical protrusion 332 protruding from the reinforcing column 331, and a threaded countersunk hole matching with the adjusting screw 34 is opened on the lower end surface of the gasket 32 ​​at the cylindrical protrusion 332, and the adjusting screw 34 is assembled to the gasket 32 ​​from the lower end of the gasket 32. The outer diameter of the gasket 32 ​​is larger than the outer diameter of the pressing block 33, the upper end of the connecting shaft 4 is a step structure with a smaller outer diameter at the end, the inner hole of the gasket 32 ​​is larger than the outer diameter of the external thread at the upper end of the connecting shaft 4, and the inner hole of the gasket 32 ​​is smaller than the outer diameter of the lower part of the external thread section of the connecting shaft 4, so that the gasket 32 ​​can press the pressing block 33.

[0040] When the gap between the clamping block 33 and the front section 1 of the ventral fin is not appropriate, it can be adjusted to a reasonable gap by rotating the adjusting screw 34. The four cylindrical protrusions 332 and the mounting holes of the adjusting screws 34 are clearance-matched, and the clearance is 0.2-0.8mm. The end face of the adjusting screw 34 is in face-to-face contact with the cylindrical protrusion 332, that is, after clamping, the end face of the cylindrical protrusion 332 is the force-bearing surface.

[0041] The thin nut 31 is made of stainless steel. The clamping block 33 is made of high-strength aluminum alloy material, which can withstand a large clamping force. The washer 32 and the adjusting screw 34 are made of stainless steel.

[0042] The ventral fin rear section 2 includes a ventral fin rear section skin 22, a foam filling block a and a nylon filling block b, wherein the ventral fin rear section skin 22 is the same as the ventral fin front section 1, using a carbon wave hybrid composite material, the foam filling block a using a PMI foam material, and the nylon filling block b using a nylon 1010 material. The entire ventral fin rear section 2 is a typical foam sandwich structure. To improve the overall strength, a nylon filling block b is inlaid every foam block. To ensure the connection strength, the threaded hole connecting the ventral fin rear section 2 and the aircraft fuselage is opened at the position with the nylon filling block b. To ensure the thread strength, the threaded hole is inlaid with a pin screw sleeve 5. The ventral fin rear section skin 22, the foam filling block a and the nylon filling block b are formed into one piece by a co-curing method, and the pin screw sleeve 5 is a post-installed structure.

[0043] The front skin 12 of the ventral fin and the rear skin 22 of the ventral fin are respectively made by prepreg layering and autoclave curing. In order to ensure the uniformity of the product, the foam filling block a and the nylon filling block b are used as positive molds, and there is no need to make new molds. When laying the layers, a layer of adhesive film is first laid on the surface of the foam filling block a and the nylon filling block b, so that the small holes on the surface of the foam filling block a can be filled, and the interface between the foam filling block a and the prepreg can be strengthened. Then, according to the design requirements, the prepreg is laid on the surface of the foam filling block a and the nylon filling block b. After the layering is completed and the vacuum auxiliary material is coated, it is put into the autoclave for pressurized temperature curing and molding.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An aircraft ventral fin with a foam sandwich structure, characterized in that: The longitudinal cross-section of the ventral fin is an acute-angled triangle with a gradually decreasing structure. The ventral fin comprises a front ventral fin section (1) and a rear ventral fin section (2) which are spliced ​​together. The mating surface between the front ventral fin section (1) and the aircraft fuselage adopts a free-form design. The mating surfaces between the front ventral fin section (1), the rear ventral fin section (2) and the aircraft fuselage are respectively provided with threaded holes for fixing. The front ventral fin section (1) and the rear ventral fin section (2) are respectively alternately filled with foam filling blocks (a) and nylon filling blocks (b). The upper end surface of the front ventral fin section (1) is fixedly connected to the aircraft fuselage through a fixing component (3).

2. The aircraft ventral fin of the foam sandwich structure according to claim 1, characterized in that: A step matching structure is provided between the front section (1) of the ventral fin and the rear section (2) of the ventral fin. A groove (11) is provided in the middle of the end surface of the front section (1) of the ventral fin connected with the rear section (2). A convex block (2) which is integrated with the rear section (2) of the ventral fin is provided in the middle of the end surface of the rear section (2) of the ventral fin connected with the front section (1). The convex block (2) matches with the groove (11).

3. The aircraft ventral fin of the foam sandwich structure according to claim 1, characterized in that: A connecting shaft (4) for connecting with an aircraft fuselage is pre-buried in the foam filling block (a) of the front section of the ventral fin (1); the upper end of the connecting shaft (4) passes through the front section of the ventral fin (1) and then through the aircraft fuselage, and is fixedly connected with the aircraft fuselage by a fixing assembly (3).

4. The aircraft ventral fin of the foam sandwich structure according to claim 3, characterized in that: The fixing assembly (3) comprises a thin nut (31), a pressing block (33) and a gasket (32). After the pressing block (33) is sleeved on the upper end of a connecting shaft (4) passing through the aircraft fuselage, the gasket (32) is covered on the upper end thereof. The thin nut (31) is threadably matched with the upper end of the connecting shaft (4). The thin nut (31) sequentially presses the gasket (32) and the pressing block (33) so that the pressing block (33) presses the aircraft fuselage.

5. The aircraft ventral fin of the foam sandwich structure according to claim 4, characterized in that: The pressing block (33) is a cylindrical structure with a through hole in the middle, an annular cavity is formed in the pressing block (33), and a thin-walled structure with an opening at the upper end. The gasket (32) covers the upper end surface of the pressing block (33).

6. The aircraft ventral fin of the foam sandwich structure according to claim 5, characterized in that: A plurality of reinforcing columns (331) are arranged on the inner wall of the outer ring of the pressing block (33), and a cylindrical protrusion (332) protruding from the reinforcing column (331) is arranged at the top end of the reinforcing column (331). A threaded countersunk hole matching the adjusting screw (34) is opened on the lower end surface of the gasket (32) at the cylindrical protrusion (332), and the adjusting screw (34) is assembled onto the gasket (32) from the lower end of the gasket (32).

7. The aircraft ventral fin of the foam sandwich structure according to claim 4, characterized in that: The outer diameter of the gasket (32) is larger than the outer diameter of the pressing block (33); the upper end of the connecting shaft (4) is a stepped structure with a smaller outer diameter at the end; the inner hole of the gasket (32) is larger than the outer diameter of the external thread at the upper end of the connecting shaft (4); and the inner hole of the gasket (32) is smaller than the outer diameter of the lower part of the external thread section of the connecting shaft (4).

8. The aircraft ventral fin of the foam sandwich structure according to claim 1, characterized in that: The foam filling block (a) is made of PMI foam material, and the nylon filling block (b) is made of nylon 1010 material.

9. The aircraft ventral fin of the foam sandwich structure according to claim 1, characterized in that: The threaded holes for connecting the front section (1) of the ventral fin and the rear section (2) of the ventral fin with the aircraft fuselage are respectively opened at the positions where the nylon filling blocks (b) are provided, and the threaded holes are respectively embedded with pin screw sleeves (5).

10. A method for forming an aircraft ventral fin of a foam sandwich structure according to any one of claims 1 to 9, characterized in that: The front section of the ventral fin (1) comprises a front section skin of the ventral fin (12), the front section skin of the ventral fin (12) is alternately filled with foam filling blocks (a) and nylon filling blocks (b), the connecting shaft (4), the front section skin of the ventral fin (12), the foam filling blocks (a) and the nylon filling blocks (b) are formed into one piece by a co-curing method, and the latch screw sleeve (5) is a post-installation structure; The rear section of the ventral fin (2) comprises a rear section skin of the ventral fin (22), the rear section skin of the ventral fin (22) is alternately filled with foam filling blocks (a) and nylon filling blocks (b), the rear section skin of the ventral fin (22), the foam filling blocks (a) and the nylon filling blocks (b) are formed into one piece by a co-curing method, and the latch screw sleeve (5) is a post-installed structure.

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