Manufacturing method of aircraft passenger cabin floor structure

Abstract

The invention discloses a manufacturing method of an aircraft passenger cabin floor structure, and belongs to the technical field of aircraft passenger cabin floor manufacturing, the aircraft passenger cabin floor structure is mainly composed of carbon fibers and resin materials, and a plurality of component units are spliced together and then connected; latticed carbon fibers and chopped carbon fibers are arranged in the connecting parts of the adjacent component units, part of the chopped carbon fibers are dispersed in the areas where meshes of the latticed carbon fibers are located, and the non-fiber-occupied areas of the connecting parts are all filled with resin materials. The component unit body is prepared by filling gaps among a plurality of layers of latticed carbon fibers which are arranged at intervals with a resin material and then performing hot pressing and cooling shaping. The connection strength difference of different areas of the connection part of the airplane passenger cabin floor structure can be remarkably reduced, the incomplete fusion defect of the vertical connection area of the airplane passenger cabin floor structure can be prevented, and the joint strength and stability of the airplane passenger cabin floor structure are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft cabin floor manufacturing, and in particular relates to a manufacturing method of an aircraft cabin floor structure. Background Art

[0002] At present, some aircraft have used thermoplastic composite materials as structures such as fuselage skin, wings, pressure bulkheads, floors and interiors. Compared with metal structures, this structure is much lighter and is gradually replacing metal materials due to its light weight, high strength and corrosion resistance.

[0003] Currently, aircraft cabin floor structures made of thermoplastic composite materials are primarily manufactured through a hot press molding process and then joined together using various methods, including mechanical and adhesive bonding. Mechanical bonding involves fasteners such as bolts or rivets (e.g., the aircraft cabin floor connection method disclosed in CN217198627U). However, the introduction of metal connectors can weaken the lightweighting effect, resulting in heavy workload, low efficiency, and the potential for stress concentration. Adhesive bonding (e.g., the composite aircraft floor manufacturing method disclosed in CN220865650U) is often plagued by long curing cycles, poor connection strength, weak resistance to environmental interference, and susceptibility to performance degradation due to factors such as temperature and humidity fluctuations and chemical corrosion. Research has shown that the strength of aircraft structural joints can be improved by applying fiber materials to them. However, one of the current technical challenges is the inability to maintain uniform fiber material throughout the continuous joining process, resulting in significant variations in joint strength across different areas. Furthermore, the vertical connection area (weld area) of aircraft structural lap joints is often the weakest point in the joint, and this vertical connection area is particularly prone to lack of fusion defects. Therefore, it is necessary to develop a new manufacturing method for aircraft cabin floor structures. Summary of the Invention

[0004] In order to at least solve the problems mentioned in the background art, an object of the present invention is to provide a method for manufacturing an aircraft cabin floor structure.

[0005] The present invention adopts the following technical solutions.

[0006] A method for manufacturing an aircraft cabin floor structure, wherein the aircraft cabin floor structure is mainly composed of carbon fiber and resin materials, and multiple component units are spliced ​​together and then connected; grid-shaped carbon fibers and chopped carbon fibers are arranged in the connecting parts of adjacent component units, and some of the chopped carbon fibers are dispersed in the area where the mesh holes of the grid-shaped carbon fibers are located. The non-fiber occupying areas of the connecting parts are all filled with resin material. The component unit body is manufactured by filling the gaps between several layers of grid-shaped carbon fibers arranged at intervals with resin material, and then performing hot pressing and cooling to shape.

[0007] In order to further improve the connection strength of the aircraft cabin floor structure, the connection part also includes a transverse protrusion and a vertical protrusion growing on the component unit body. The transverse protrusion is located below the platform area of ​​the connection part, and the vertical protrusion is located above the platform area.

[0008] In order to effectively prevent the occurrence of unfused defects in the vertical connection area of ​​the aircraft cabin floor structure, a plurality of spaced-apart transverse protrusions and a plurality of vertical protrusions are provided on the first component unit; a plurality of spaced-apart transverse grooves and vertical grooves are provided on the second component unit, the transverse grooves are used to cooperate with the transverse protrusions, and the vertical grooves are used to cooperate with the vertical protrusions, and a plurality of spaced-apart pits are provided on the platform area of ​​the second component unit.

[0009] The manufacturing method of the aircraft cabin floor structure of the present invention comprises the following steps: Step 1: Cut the grid-shaped carbon fiber according to the design requirements and place and fix the grid-shaped carbon fiber on the component unit mold; Step 2: adding molten resin into the component unit mold, impregnating the carbon fiber with the molten resin, and cooling and shaping the molten resin to obtain a component unit prepreg; Step 3, hot pressing the obtained component unit prepreg, demoulding and cooling it, and then performing fine processing to obtain the component unit; Step 4: First, the second component unit is positioned and fixed, and then resin pellets with chopped carbon fibers are laid in the recesses on the second component unit, and a set amount of molten resin is poured into the slots. Next, the first component unit is positioned, with the vertical protrusions on the first component unit fitting into the vertical slots on the second component unit, and the horizontal protrusions on the first component unit fitting into the horizontal slots on the second component unit, with the platform area on the first component unit covering the resin pellets. Step 5, using ultrasonic welding equipment to weld the plurality of first component units and the plurality of second component units together; Step 6: Post-process the welded workpiece to obtain the aircraft cabin floor structure.

[0010] In order to further reduce the difference in connection strength between different areas of the aircraft cabin floor structure connection part, in step 3, the step of fine processing of the second component unit includes: first processing a cross-shaped groove in the platform area of ​​the second component unit, and then widening the intersection of the cross-shaped groove into a pit, the depth of the cross-shaped groove is not greater than 1 / 3 of the diameter of the resin particle, the width of the cross-shaped groove is not greater than 1 / 3 of the diameter of the resin particle, and the width of the pit is not greater than 2 / 3 of the diameter of the resin particle; and processing a card groove on the second component unit.

[0011] Preferably, the platform area of ​​the second component unit has a central area and two side areas, and the resin particles in the central area have a larger diameter than the resin particles in the side areas. The step of fine-machining the first component unit includes: machining a plurality of spaced-apart transverse protrusions and a plurality of vertical protrusions on the first component unit.

[0012] Preferably, the diameter of the resin particles in the middle area is 1.2~1.3mm, the diameter of the resin particles in the edge area is 0.9~1mm, the width of the middle area is 10~15mm, and the width of each edge area is 3~4mm; the depth and width of the cross-shaped groove are both 0.3mm, and the width of the pit is 0.5mm.

[0013] In the present invention, the preparation steps of the grid-like carbon fiber are as follows: first, a layer of resin material with a thickness not exceeding 1 mm is poured on the laid grid-like carbon fiber fabric, and holes are punched through the non-fiber area on the sheet-like structure formed after the resin material is cured to obtain the grid-like carbon fiber.

[0014] Preferably, during the hot pressing process, the pressure is maintained at an initial pressure of 0.5-2.0 MPa for 5-10 minutes, and then maintained at a pressure of 2.0-4.0 MPa for 1-3 hours.

[0015] Beneficial effects: The solution provided by the present invention can not only significantly reduce the difference in connection strength between different areas of the aircraft cabin floor structure connection parts, but also prevent the occurrence of unfused defects in the vertical connection areas of the aircraft cabin floor structure, greatly improve the joint strength and stability of the aircraft cabin floor structure, and realize the rapid prototyping of the cabin floor structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a three-dimensional schematic diagram of the first component unit in Example 1; Figure 2 This is a three-dimensional schematic diagram of the second component unit in Example 1; Figure 3 This is a top view schematic diagram of the second component unit in Example 1; Figure 4 A partial schematic diagram of the grid-like carbon fibers in Example 1; In the figure: second component unit 1, vertical slot 2, first vertical connection area 3, inner braid area 4, middle area 5, outer edge area 6, second vertical connection area 7, platform area 8, pit 9, cross-shaped groove 10, vertical protrusion 11, first component unit 12, through hole 13, grid-like carbon fiber fabric 14, thin sheet structure 15, transverse slot 16, transverse protrusion 17. DETAILED DESCRIPTION

[0017] The following, in conjunction with the accompanying drawings, clearly and completely describes the technical solutions of the present invention. Obviously, the embodiments described here are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort fall within the scope of protection of the present invention. In the present invention, chopped carbon fiber (model 01299, brand Dongyi Yang) is used.

[0018] Example 1: Combination Figures 1 to 4 As shown, the aircraft cabin floor structure is formed by splicing together multiple component units and then connecting them. The aircraft cabin floor structure is mainly composed of carbon fiber and resin materials. The component unit has a platform area 8, a first vertical connection area 3 and a second vertical connection area 7. The connection parts of adjacent component units are provided with grid-like carbon fibers and chopped carbon fibers. Some of the chopped carbon fibers are dispersed in the area where the mesh holes of the grid-like carbon fibers are located. The non-fiber occupying areas of the connection parts are filled with resin material. The component unit body is made by filling the gaps between several layers of grid-like carbon fibers arranged at intervals with resin material, and then performing hot pressing and cooling to shape. Among them, the connecting portion also includes a transverse protrusion 17 and a vertical protrusion 11 growing on the component unit body, the transverse protrusion 17 is located below the platform area 8 of the connecting portion, and the vertical protrusion 11 is located above the platform area 8; a plurality of transverse protrusions 17 and a plurality of vertical protrusions 11 arranged at intervals are provided on the first component unit 12; a plurality of transverse card grooves 16 and vertical card grooves 2 are provided at intervals on the second component unit 1 (the first vertical connection area 3 on the second component unit 1 is provided with a vertical card groove 2, and the second vertical connection area 7 on the second component unit 1 is provided with a transverse card groove 16), the transverse card groove 16 is used to match the transverse protrusion 17, and the vertical card groove 2 is used to match The vertical protrusions 11 are combined, and a plurality of pits 9 are arranged at intervals on the platform area 8 of the second component unit 1; the platform area 8 of the second component unit 1 has a central area 5 and two side areas (including an inner weaving area 4 and an outer side area 6), and the diameter of the resin particles in the central area 5 is larger than the diameter of the resin particles in the side areas; the diameter of the resin particles in the central area 5 is 1.2~1.3mm, the diameter of the resin particles in the side areas is 0.9~1mm, the width of the central area 5 is 10~15mm, and the width of each side area is 3~4mm; the depth and width of the cross-shaped groove 10 are both 0.3mm, and the width of the pit 9 is 0.5mm.

[0019] The manufacturing method of the aircraft cabin floor structure in this embodiment includes the following steps: Step 1: Cut the grid-shaped carbon fiber according to the design requirements and place and fix the grid-shaped carbon fiber on the component unit mold; The steps for preparing the grid-like carbon fiber are as follows: first, a layer of resin material with a thickness not exceeding 1 mm is poured on the laid grid-like carbon fiber fabric 14, and holes 13 are punched through the non-fiber area of ​​the sheet-like structure 15 formed after the resin material is cured to obtain a grid-like carbon fiber. This grid-like carbon fiber has a sheet structure similar to paper; the grid-like carbon fiber fabric 14 is pre-woven according to the size requirements; Step 2: adding molten resin into the component unit mold, impregnating the carbon fiber with the molten resin, and cooling and shaping the molten resin to obtain a component unit prepreg; Step 3: hot pressing the obtained component unit prepreg, demolding and cooling it, and then finishing it to obtain the component unit; during the hot pressing process, the pressure is first maintained at an initial pressure of 0.5-2.0 MPa for 5-10 minutes, and then maintained at a pressure of 2.0-4.0 MPa for 1-3 hours; In this step, the step of fine-machining the second component unit 1 includes: first machining a cross-shaped groove 10 on the platform area 8 of the second component unit 1, and then widening the intersection of the cross-shaped groove 10 into a pit 9, wherein the depth of the cross-shaped groove 10 is no more than 1 / 3 of the diameter of the resin particle, the width of the cross-shaped groove 10 is no more than 1 / 3 of the diameter of the resin particle, and the width of the pit 9 is no more than 2 / 3 of the diameter of the resin particle; and machining a card groove on the second component unit 1; Step 4: First, position and secure the second component unit 1. Then, lay resin pellets containing chopped carbon fibers in the recess 9 on the second component unit 1, and pour a set amount of molten resin into the slot (the amount of resin used is 1 / 2 to 2 / 3 of the slot volume). Next, position the first component unit 12 (the second component unit 1 is located below the first component unit 12), ensuring that the vertical protrusion 11 on the first component unit 12 fits (snaps into) the vertical slot 2 on the second component unit 1, and the horizontal protrusion 17 on the first component unit 12 fits (snaps into) the horizontal slot 16 on the second component unit 1, and the platform area 8 on the first component unit 12 covers the resin pellets. Step 5: Using ultrasonic welding equipment to weld together the plurality of first component units 12 and the plurality of second component units 1. Before welding, the component units need to be placed in an environment of 80-100°C and vacuum dried for 2-4 hours. During the welding process, the resin melts and connects and reshapes each other, and then cools and solidifies into shape. Step 6: Post-process the welded workpiece, including using a CNC lathe to precisely machine the workpiece to remove excess material and polish it to a uniform surface roughness to obtain the aircraft cabin floor structure.

[0020] In this embodiment, the preparation method of resin particles is as follows: a twin-screw extruder is used to melt the resin raw material, and short-cut fibers are added and stirred evenly. The amount of short-cut fibers used is 15% of the total volume of the resin particles. After shearing and coating by the twin-screw extruder, particles of corresponding particle size are obtained by a pelletizer.

[0021] In one application scheme: the thickness of the component unit obtained is 8mm; the thickness of the grid carbon fiber is 0.5mm, the side length of each grid of the grid carbon fiber is 10mm, the diameter of the grid carbon fiber tow is 0.1mm, and the diameter of the through hole of the grid carbon fiber is 5mm; the resin material is polyetheretherketone; the diameter of the resin particles used in the middle area 5 is 1.2mm, the diameter of the resin particles used in the edge area is 1mm, the width of the middle area 5 is 12mm, and the width of each edge area is 4mm; the depth and width of the cross-shaped groove 10 are both 0.3mm, the width of the pit 9 is 0.5mm, and the spacing between adjacent edges of the parallel grooves of the cross-shaped groove 10 is 5mm; the depth of the cross-shaped groove 10 is 1 / 3 of the diameter of the resin particle, the width of the cross-shaped groove 10 is 1 / 3 of the diameter of the resin particle, the width of each card slot is 2mm, the length of each card slot is 20mm, and the height of the card slot is 4mm; in step 5, the workpiece is preheated to 150 The temperature was kept constant at ℃, the welding tool head was perpendicular to the workpiece surface, the effective working surface diameter of the welding tool head was 30 mm, the downward pressure of the welding tool head was 0.8 mm (relative to the initial surface of the workpiece), the welding amplitude was 60 μm, the welding pressure was 0.2 MPa, and the welding speed was 15 mm / s; during the hot pressing process, the pressure was first maintained at an initial pressure of 1 MPa for 6 minutes, and then at a pressure of 3 MPa for 2 hours.

[0022] Comparative Example 1, a method for manufacturing an aircraft cabin floor structure, differs from Example 1 in that: the component unit adopts an integrally molded structure. When manufacturing the component unit, all carbon fiber tows are first laid in the mold with a spacing of 10 mm between the carbon fiber tows. Then, the molten resin material is poured as a whole and molded, and the protrusions and grooves are finely processed.

[0023] Comparative Example 2 is a method for manufacturing an aircraft cabin floor structure. The difference between Example 1 and Example 1 is that the cross-shaped grooves and pits in the platform area are omitted, and the process of pouring molten resin into the slots is omitted; the component unit adopts an integrated molding structure. When manufacturing the component unit, a grid-shaped carbon fiber fabric is first laid in the mold, and then the molten resin material is poured as a whole and compression molded, and finally fine-processed.

[0024] Comparative Example 3, a method for manufacturing an aircraft cabin floor structure, differs from Example 1 in that: the horizontal protrusions 17, vertical protrusions 11 and corresponding slots on the component unit are omitted, and the process of pouring molten resin into the slots is omitted; the component unit adopts an integrally molded structure. When manufacturing the component unit, a grid-shaped carbon fiber fabric is first laid in the mold, and then the molten resin material is poured as a whole and molded, and finally fine-processed.

[0025] Mechanical properties tests were performed on the aircraft cabin floor structure specimens prepared in Example 1 and the comparative example. The results were as follows: the tensile strength of the specimen joint in Example 1 was 29.67 MPa, the tensile strength of the specimen joint in Comparative Example 1 was 21.82 MPa, the tensile strength of the specimen joint in Comparative Example 2 was 17.36 MPa, and the tensile strength of the specimen joint in Comparative Example 3 was 14.5 MPa.

[0026] Mechanical properties of different parts of the aircraft cabin floor structure samples prepared in Example 1 and the comparative example were tested. Specifically, samples were randomly cut / intersected from the same sample (the cutting direction was the length direction of the vertical card slot 2, that is, Figure 2 The results for small specimens with a width of 10 mm (in the left and right directions) were as follows: the maximum difference in joint tensile strength among the five small specimens in Example 1 was 0.2 MPa, compared to 0.8 MPa among the five small specimens in Comparative Example 1, 1.3 MPa among the five small specimens in Comparative Example 2, and 1.9 MPa among the five small specimens in Comparative Example 3. This shows that the solution in Example 1 significantly reduces the difference in joint strength between different areas of the aircraft cabin floor structure connection. Defect inspection of aircraft cabin floor structure specimens produced in Example 1 and the comparative example revealed that: None of the five specimens in Example 1 showed any lack of fusion defects; however, three lack of fusion defects were found in the vertical connection areas of the five specimens in Comparative Example 1; four lack of fusion defects were found in two of the five specimens in Comparative Example 2; and eight lack of fusion defects were found in ten of the five specimens in Comparative Example 3. Analysis indicates that the specific multilayer structure and platform structure employed in Example 1, combined with the pouring of molten resin into the slots, allow for smoother flow and reshaping of the surface material in the unit connection areas during welding under the specific welding pressure. In contrast, the comparative example exhibits an uneven and uncontrollable flow field in the unit connection areas, making lack of fusion defects more likely to occur.

Claims

1. A method for manufacturing an aircraft cabin floor structure, mainly composed of carbon fiber and resin materials, characterized by: A plurality of component units are connected together, and grid-like carbon fibers and chopped carbon fibers are arranged in the connection parts of adjacent component units. Part of the chopped carbon fibers are dispersed in the area where the mesh holes of the grid-like carbon fibers are located, and the non-fiber occupying areas of the connection parts are filled with resin materials. The component unit body is made by filling the gaps between several layers of grid-like carbon fibers arranged at intervals with resin materials, and then hot pressing and cooling to shape them.

2. The method for manufacturing an aircraft cabin floor structure according to claim 1, characterized in that: The connecting portion further comprises a transverse protrusion and a vertical protrusion grown on the component unit body, the transverse protrusion is located below the platform area of ​​the connecting portion, and the vertical protrusion is located above the platform area.

3. The method for manufacturing an aircraft cabin floor structure according to claim 2, characterized in that: A plurality of spaced-apart transverse protrusions and a plurality of vertical protrusions are provided on the first component unit; a plurality of spaced-apart transverse slots and a plurality of vertical slots are provided on the second component unit, the transverse slots are used to cooperate with the transverse protrusions, and the vertical slots are used to cooperate with the vertical protrusions, and a plurality of spaced-apart pits are provided on the platform area of ​​the second component unit.

4. The method for manufacturing an aircraft cabin floor structure according to claim 3, characterized in that the steps include: Step 1: Cut the grid-shaped carbon fiber according to the design requirements and place and fix the grid-shaped carbon fiber on the component unit mold; Step 2: adding molten resin into the component unit mold, impregnating the carbon fiber with the molten resin, and cooling and shaping the molten resin to obtain a component unit prepreg; Step 3, hot pressing the obtained component unit prepreg, demoulding and cooling it, and then performing fine processing to obtain the component unit; Step 4: First, the second component unit is positioned and fixed, and then resin pellets with chopped carbon fibers are laid in the recesses on the second component unit, and a set amount of molten resin is poured into the slots. Next, the first component unit is positioned, with the vertical protrusions on the first component unit fitting into the vertical slots on the second component unit, and the horizontal protrusions on the first component unit fitting into the horizontal slots on the second component unit, with the platform area on the first component unit covering the resin pellets. Step 5, using ultrasonic welding equipment to weld the plurality of first component units and the plurality of second component units together; Step 6: Post-process the welded workpiece to obtain the aircraft cabin floor structure.

5. The method for manufacturing an aircraft cabin floor structure according to claim 4, characterized in that: In step 3, the step of fine processing the second component unit includes: first processing a cross-shaped groove in the platform area of ​​the second component unit, and then widening the intersection of the cross-shaped groove into a pit, the depth of the cross-shaped groove is not greater than 1 / 3 of the diameter of the resin particle, the width of the cross-shaped groove is not greater than 1 / 3 of the diameter of the resin particle, and the width of the pit is not greater than 2 / 3 of the diameter of the resin particle; and processing a card groove on the second component unit.

6. The method for manufacturing an aircraft cabin floor structure according to claim 5, characterized in that: The platform region of the second component unit has a central region and two side regions, and the resin particle diameter of the central region is larger than the resin particle diameter of the side regions.

7. The method for manufacturing an aircraft cabin floor structure according to claim 6, characterized in that: The diameter of the resin particles in the middle area is 1.2~1.3mm, the diameter of the resin particles in the edge area is 0.9~1mm, the width of the middle area is 10~15mm, and the width of each edge area is 3~4mm; the depth and width of the cross-shaped groove are both 0.3mm, and the width of the pit is 0.5mm.

8. The method for manufacturing an aircraft cabin floor structure according to any one of claims 1 to 7, characterized in that: The preparation steps of the grid-like carbon fiber are as follows: first, a layer of resin material with a thickness of no more than 1 mm is poured on the laid grid-like carbon fiber fabric, and holes are punched in the non-fiber area on the sheet-like structure formed after the resin material is cured to obtain the grid-like carbon fiber.

9. The method for manufacturing an aircraft cabin floor structure according to claim 8, characterized in that: During the hot pressing process, the initial pressure is maintained at 0.5-2.0 MPa for 5-10 minutes, and then at 2.0-4.0 MPa for 1-3 hours.

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