Method and device for replacing outer curved skin of aircraft

Abstract

Disclosed in the present invention are a method and device for replacing an outer curved skin of an aircraft. Initial holes are drilled using a counterbore drill bushing; then, the coaxiality of a hole in a curved drill jig is verified using the counterbore drill bushing and a stepped pin; and finally, a replaceable drill bushing is used to perform staged enlarging of the hole, thereby achieving precise hole drilling of the skin. The method changes a conventional replacement, assembly and machining method for a curved skin, reduces the difficulty in replacing the curved skin, lowers the requirements for operator skill level and experience, decreases the scrap rate of parts, improves the quality of rework and assembly, enhances rework efficiency, and reduces rework manufacturing costs.

Description

A method and device for replacing curved surface skin of an aircraft. Technical Field

[0001] This invention belongs to the field of aircraft curved skin technology, specifically relating to a method and device for replacing the curved skin of an aircraft exterior. Background Technology

[0002] Occasional damage to curved surface skins during the assembly and manufacturing process of aircraft exteriors and during aircraft service is unavoidable. Because the skin connects to the fuselage frame and consists of numerous, difficult-to-replace, and high-value components, it is generally not necessary to scrap the skin and its connected components when skin damage prevents it from meeting functional and strength design requirements. Therefore, when an aircraft requires repair due to skin damage, it is essential to employ an assembly and manufacturing method that replaces the skin while preserving the frame components.

[0003] Currently, in the process of drilling and assembling curved aircraft skin panels, drilling is generally done from one side of the skin towards the other side of the frame. Therefore, the space on the side of the frame located on the curved skin is relatively open, while the space on the frame side is relatively narrow. When replacing curved skin panels, if holes are enlarged or reamed from the frame side, the narrow space makes it difficult to use a vertical drill, and the perpendicularity and coaxiality of the holes cannot be effectively guaranteed, resulting in the risk of "figure-eight" holes and excessive unidirectional clearance after fastener installation. If holes are enlarged or reamed from the skin side, although the space is open, relying solely on a vertical drill cannot effectively guarantee coaxiality with the holes on the frame, still resulting in the risk of "figure-eight" holes or excessive hole diameter. Furthermore, because there are many holes involved on the skin, relying on operators' skills and traditional manual assembly methods makes it difficult to ensure that all holes meet the design department's performance and strength requirements for the aircraft, easily leading to the scrapping of a large number of parts. Summary of the Invention

[0004] The purpose of this invention is to provide a method and device for replacing curved surface skin of an aircraft that can greatly reduce the difficulty of making initial holes in new skin while ensuring coaxiality with holes on the frame components, while reducing the requirements for the operator's skill and experience, improving rework efficiency and assembly quality, and reducing rework manufacturing costs, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for replacing curved surface skin on an aircraft:

[0007] S1: Remove the damaged skin and reposition the new skin. Remove the fasteners connecting the skeleton and the damaged curved skin and reposition the skeleton and the new curved skin according to the fixture.

[0008] S2: Initial hole through reverse drilling. Based on the final hole on the skeleton, the initial hole on the new skin is made using a reverse drilling tool in the operable area on the template frame, and temporary fasteners are installed to clamp the skin and skeleton.

[0009] S3: Enlarging holes. Based on the initial holes made in the new skin, use a vertical drill and a step drill to enlarge all the initial holes, and install temporary fasteners to clamp the skin and the skeleton.

[0010] S4: Check and verify the coaxiality and fixation of the curved surface drill jig by using reverse hole drill bushings, reverse hole drill bushings, temporary fasteners, etc.

[0011] S5: Expanding and reaming the final hole, using a replaceable drill bushing according to the curved surface drill jig to expand and ream the final hole of the new skin and deburr it, and install temporary fasteners to clamp the skin and skeleton.

[0012] S6: Complete the drilling of the skin, change the position of the curved surface drill jig, and complete the drilling operation of other areas of the curved surface skin according to S4-S5.

[0013] S7: Skin countersunk socket. After deburring, use locating pins or temporary fasteners to reposition the skeleton and skin countersunk socket on the jig tooling and install fasteners.

[0014] S8: Complete the skin replacement and installation, remove the frame, and perform the final hole countersinking and fastener installation on the remaining areas that cannot be operated on the frame according to S2-S6.

[0015] Furthermore, in S4, a feeler gauge is used to check the gap between the skin and the frame, as well as the gap between the curved drill jig and the skin. A reverse hole drill sleeve is installed on the frame stringer, and a stepped pin is inserted into the curved drill jig. Temporary fasteners are used to fix the curved drill jig by ensuring that the drill jig hole and the frame stringer hole are coaxial through the skin, the frame, and the reverse hole drill sleeve.

[0016] Furthermore, the inner diameter of the replaceable drill sleeve is determined according to the tool specifications in the processing and operation specifications of the relevant machine model, and the final hole diameter required by the drawing and specifications is gradually increased based on the initial hole.

[0017] Furthermore, the curved surface drill jig is obtained by establishing a curved surface drill jig model with corresponding curvature in CATIA based on the three-dimensional model of the surface skin to be processed, and then machining it with a CNC machine tool.

[0018] Furthermore, the normal direction of the drill bushing hole on the curved drill jig is machined by a CNC machine tool according to the theoretical normal direction of the hole to ensure the perpendicularity of the hole.

[0019] An aircraft exterior curved skin replacement device includes a curved drill jig, a reverse hole drill sleeve, and a replaceable drill sleeve. The curved drill jig is in complete contact with the skin on the side closest to it. The curved drill jig has a drill sleeve hole that is perpendicular to the contact surface between the curved drill jig and the skin. The outer diameter of the reverse hole drill sleeve is adapted to the diameter of the final hole on the frame part. The outer diameter of the replaceable drill sleeve is adapted to the diameter of the drill sleeve hole.

[0020] Furthermore, the number of drill bushing holes is at least three, the drill bushing holes are arranged adjacently and symmetrically, and the positional spacing between the drill bushing holes is consistent with the positional spacing of the holes on the aircraft frame.

[0021] Furthermore, the skin replacement device also includes a stepped pin, the maximum diameter of which is adapted to the inner diameter of the drill jig hole.

[0022] Furthermore, the skin replacement device also includes temporary fasteners, spring pins, and washers, which are used to clamp the aircraft frame and skin.

[0023] Furthermore, the replaceable drill sleeve includes several different inner diameter specifications, enabling progressive enlargement of the curved skin hole.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] In this invention, an initial hole is created using a reverse-hole drill bushing. Then, the coaxiality of the curved surface drill jig hole is verified using the reverse-hole drill bushing and a stepped pin. Finally, a replaceable drill bushing is used to progressively enlarge the hole, achieving precise drilling of the skin. This method changes the traditional method of replacing and assembling curved surface skins, reducing the difficulty of replacing curved surface skins, lowering the skill and experience requirements for operators, reducing the scrap rate of parts, improving rework assembly quality, increasing rework efficiency, and reducing rework manufacturing costs. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0027] Figure 1 is a flowchart of the method of the present invention;

[0028] Figure 2 is a schematic diagram of the overall structure of the present invention;

[0029] Figure 3 is a magnified view of a portion of Figure 1;

[0030] Figure 4 is a schematic diagram of a partial embodiment of the present invention using a reverse hole drill sleeve to make the initial hole for curved skin;

[0031] Figure 5 is a schematic diagram of a partial embodiment of the present invention using stepped drilling and vertical drilling to enlarge the initial hole;

[0032] Figure 6 is a schematic diagram of a partial embodiment of the coaxiality verification and fixed curved surface drilling jig of the present invention;

[0033] Figure 7 is a schematic diagram of a partial embodiment of the present invention for removing the reverse hole drill sleeve and the stepped pin;

[0034] Figure 8 is a partial schematic diagram of an embodiment of the invention providing a method for enlarging and boring skin holes using replaceable drill bushings.

[0035] In the diagram: 1. Skeleton; 2. Skin; 3. Frame; 4. Curved drill jig; 5. Replaceable drill bushing; 6. Temporary fastener; 7. Spring pin; 8. Reverse hole drill bushing; 9. Drill bit / reamer; 10. Washer; 11. Vertical drill; 12. Stepped pin. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0037] It is worth noting that the curved surface drill jig 4 described in this invention is a model of the curved surface drill jig 4 with the corresponding curvature established in CATIA based on the three-dimensional model of the surface skin 2 being processed, and then processed by a CNC machine tool, thereby ensuring the fit between the drill jig and the skin 2. Simultaneously, the normal direction of the drill bushing hole on the curved surface drill jig 4 is also processed by the CNC machine tool according to the theoretical normal direction of the hole, thereby ensuring the perpendicularity of the hole. Furthermore, the outer diameter of the reverse hole drill bushing 8 corresponds to the diameter of the final hole on the skeleton 1. The outer diameter of the replaceable drill bushing 5 corresponds to the hole diameter on the curved surface drill jig 4, while the inner diameter of the replaceable drill bushing 5 is determined according to the tool specifications in the processing and operation specifications of the relevant machine model, gradually increasing the final hole diameter required by the drawing and specifications based on the initial hole. In addition, the outer diameter of different parts of the stepped pin 12 corresponds to the inner diameter of the reverse hole drill bushing 8 and the inner diameter of the hole on the curved surface drill jig 4, thereby ensuring accuracy during verification and the quality of subsequent operation holes.

[0038] Example 1:

[0039] Referring to Figures 1-3, the present invention proposes the following technical solution:

[0040] The main steps in the replacement and assembly of the aircraft curved skin 2 include:

[0041] S1. Remove damaged skin 2 and reposition new skin 2: Remove the fasteners connecting skeleton 1 and damaged curved skin 2 and reposition skeleton 1 and new curved skin 2 according to the tooling of frame 3.

[0042] S2, Initial hole through reverse hole: Based on the final hole on the skeleton 1, the operable area on the template 3 uses the reverse hole drill sleeve 8 to make the initial hole on the new skin 2, and installs the temporary fastener 6 to clamp the skin 2 and the skeleton 1.

[0043] S3. Enlarging holes: Based on the initial holes made in the new skin 2, use a vertical drill and a step drill to enlarge all the initial holes, and install temporary fasteners 6 to clamp the skin 2 and the skeleton 1.

[0044] S4. Inspection: Use reverse hole drill sleeve 8, stepped pin 12, temporary fastener 6, etc. to position the curved surface drill jig 4 and verify the coaxiality and fix the curved surface drill jig 4.

[0045] S5. Expanding and reaming the final hole: According to the curved surface drill jig 4, use the replaceable drill sleeve 5 to expand and ream the final hole of the new skin 2, deburr it, and install temporary fasteners 6 to clamp the skin 2 and the skeleton 1.

[0046] S6. Complete hole making for skin 2: Change the position of curved surface drill jig 4, and press S4 to S5 to complete hole making operations in other areas of curved surface skin 2.

[0047] S7, Skin 2 countersink: After deburring, use the positioning pins / temporary fasteners 6 to reposition the skeleton 1 and skin 2 on the fixture 3 and countersink the fasteners.

[0048] S8. Complete the replacement and installation of skin 2: Remove the frame and install the final hole countersink and fasteners on the remaining areas of the frame 3 that cannot be operated, according to S2 to S6.

[0049] Among the steps of replacing and assembling the curved skin 2, the hole-making process of the new curved skin 2 is the most critical. The following example, taking the process of replacing the new skin 2 of a certain model of cargo door frame product, based on a row of 6.35mm final holes on a certain stringer of the frame 1, to make 6.35mm holes on the new skin 2, will further illustrate the assembly processing method of the most critical hole-making process of the present invention and the usage method of the replacement assembly device.

[0050] Referring to Figures 1-8, a method for replacing the curved surface skin 2 of an aircraft includes the following key steps:

[0051] 1. After removing the damaged skin 2 and the tooling frame 3, and repositioning the skeleton 1 and the new skin 2, according to the 6.35mm final hole on the stringer of the skeleton 1, use a reverse hole drill sleeve 8 with an outer diameter of 6.35mm and an inner diameter of 2.5mm to make all the corresponding 2.5mm guide holes on the new skin 2 and deburr them. Please refer to Figure 3. At the same time, use 2.5mm spring pins 7 / pullers to clamp the skin 2 and the skeleton 1.

[0052] 2. Remove the spring pin 7 / pull bracket, and on the basis of making 2.5mm guide holes in the new skin 2, use a 3.2mm vertical drill and a 2.5mm-3.2mm step cutter to enlarge all 2.5mm guide holes to 3.2mm and deburr them. Please refer to Figure 4. At the same time, use a 3.2mm spring pin 7 / pull bracket to clamp the skin 2 and the skeleton 1.

[0053] 3. Use a feeler gauge to check the gap between the skin 2 and the frame 1, as well as the gap between the curved drill jig 4 and the skin 2. Install the reverse hole drill sleeve 8 on the stringer of the frame 1, and insert the stepped pin 12 into the curved drill jig 4. Through the skin 2, the frame 1, and the reverse hole drill sleeve 8, ensure that the drill jig hole is coaxial with the stringer hole of the frame 1. Use temporary fasteners 6 to fix the curved drill jig 4. Please refer to Figure 6.

[0054] 4. After re-verifying the coaxiality of the drill hole and the stringer hole of the skeleton 1, check the fixation of the curved template and remove the reverse hole drill sleeve 8 and the stepped pin 12. Please refer to Figures 6 and 7.

[0055] 5. Using the replaceable drill bushing 5, enlarge the new skin 2 to 4.0mm-4.6mm-6.2mm according to the drill jig. Finally, use the replaceable drill bushing 5 to ream the new skin 2 to 6.35mm and deburr it. Install the 6.35mm temporary fastener 6 to clamp the skin 2 and the frame 1. Please refer to Figure 8.

[0056] 6. For the holes on the skin 2 corresponding to this stringer, repeat steps 3-5 to gradually enlarge the holes to 6.2mm, and finally ream the holes to 6.35mm and deburr them. Install temporary fasteners 6 with a specification of 6.35mm to clamp the skin 2 and the frame 1.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for replacing curved surface skin on an aircraft, characterized in that: S1: Remove the damaged skin (2) and reposition the new skin (2), remove the fasteners connecting the skeleton (1) and the damaged curved skin (2), and reposition the skeleton (1) and the new curved skin (2) according to the fixture (3); S2: Initial hole of reverse hole, according to the final hole on the skeleton (1) of the operable area on the frame (3), use the reverse hole drill sleeve (8) to make the initial hole on the new skin (2), and install temporary fasteners (6) to clamp the skin (2) and the skeleton (1). S3: Enlarge the holes. Based on the initial holes made in the new skin (2), use a vertical drill and a step drill to enlarge all the initial holes and install temporary fasteners (6) to clamp the skin (2) and the skeleton (1). S4: Check and use reverse hole drill bushing (8), stepped pin (12), temporary fastener (6) to position the curved surface drill jig (4) and verify the coaxiality and fix the curved surface drill jig (4); S5: Expand and ream the final hole. According to the curved surface drill jig (4), use the replaceable drill sleeve (5) to expand and ream the final hole of the new skin (2) and deburr it. Install temporary fasteners (6) to clamp the skin (2) and the skeleton (1). S6: Complete the hole making of the skin (2), change the position of the curved surface drill jig (4), and complete the hole making operation of other areas of the curved surface skin (2) according to S4-S5; S7: Skin (2) countersink, after deburring, use positioning pins or temporary fasteners (6) to reposition the skeleton (1) and skin (2) countersinks on the frame (3) tooling and install fasteners; S8: Complete the replacement and installation of the skin (2), remove it from the frame, and install the final hole countersink and fasteners of the curved skin (2) in the remaining area that cannot be operated on the frame (3) according to S2-S6.

2. The method for replacing curved surface skin of an aircraft according to claim 1, characterized in that: In S4, feeler gauges are used to check the gap between the skin (2) and the frame (1) and the gap between the curved drill jig (4) and the skin (2). A reverse hole drill sleeve (8) is installed on the stringer of the frame (1), and a stepped pin (12) is inserted into the curved drill jig (4). Temporary fasteners (6) are used to fix the curved drill jig (4) by ensuring that the drill jig hole is coaxial with the stringer hole of the frame (1) through the skin (2), the frame (1), and the reverse hole drill sleeve (8).

3. The method for replacing curved surface skin of an aircraft according to claim 1, characterized in that: The inner diameter of the replaceable drill sleeve (5) is determined according to the tool specifications in the processing specifications and operation specifications of the relevant machine model, and the final hole diameter required by the drawing and specifications is gradually increased based on the initial hole.

4. The method for replacing curved surface skin of an aircraft according to claim 1, characterized in that: The curved surface drill jig (4) is a model of the curved surface drill jig (4) with the corresponding curvature established in CATIA based on the three-dimensional model of the surface skin (2) to be processed, and then processed by a CNC machine tool.

5. The method for replacing curved surface skin of an aircraft according to claim 1, characterized in that: The normal direction of the drill bushing hole on the curved surface drill jig (4) is processed by a CNC machine tool according to the theoretical normal direction of the hole to ensure the perpendicularity of the hole.

6. A replacement device for curved surface skin (2) of an aircraft, characterized in that: The skin (2) replacement device includes a curved drill jig (4), a reverse hole drill sleeve (8), and a replaceable drill sleeve (5). The side of the curved drill jig (4) close to the skin (2) is completely fitted with the skin (2). The curved drill jig (4) is provided with a drill sleeve hole, which is perpendicular to the mating surface of the curved drill jig (4) and the skin (2). The outer diameter of the reverse hole drill sleeve (8) is adapted to the diameter of the final hole on the skeleton (1) part. The outer diameter of the replaceable drill sleeve (5) is adapted to the diameter of the drill sleeve hole.

7. The aircraft exterior curved skin (2) replacement device according to claim 6, characterized in that: The number of drill bushing holes is at least 3. The drill bushing holes are arranged adjacently and symmetrically. The positional spacing between the drill bushing holes is consistent with the positional spacing of the holes on the aircraft frame (1).

8. The aircraft exterior curved skin (2) replacement device according to claim 7, characterized in that: The skin (2) replacement device also includes a stepped pin (12), the maximum diameter of which is adapted to the inner diameter of the drill jig hole.

9. The aircraft exterior curved skin (2) replacement device according to claim 8, characterized in that: The skin (2) replacement device also includes a temporary fastener (6), a spring pin (7), and a washer (10), which are used to clamp the aircraft frame (1) and the skin (2).

10. The aircraft exterior curved skin (2) replacement device according to claim 9, characterized in that: The replaceable drill sleeve (5) includes several different inner diameter specifications, which realizes the gradual enlargement of the curved skin (2) hole.

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