A method of manufacturing an aircraft cabin floor structure

Abstract

The application discloses a kind of manufacturing methods of aircraft passenger cabin floor structure, belong to aircraft passenger cabin floor manufacturing technical field, aircraft passenger cabin floor structure is mainly composed of carbon fiber and resin material, after a plurality of component units are spliced together, connection is carried out;The connecting portion of adjacent component units is provided with grid-shaped carbon fiber and chopped carbon fiber, part of chopped carbon fiber is dispersed in the area where the mesh of grid-shaped carbon fiber is located, the non-fiber occupying area of connecting portion is filled with resin material, the body of component unit is obtained after the gap of several layers of grid-shaped carbon fiber arranged at intervals is filled with resin material, and then heat pressing, cooling and shaping are carried out.The application can not only significantly reduce the connection strength difference of different areas of aircraft passenger cabin floor structure connecting portion, but also prevent the vertical connecting area of aircraft passenger cabin floor structure from appearing unfused defects, improve the joint strength and stability of aircraft passenger cabin floor structure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aircraft passenger cabin floor manufacturing, and particularly relates to a manufacturing method of an aircraft passenger cabin floor structure. BACKGROUND

[0002] At present, some aircraft have used thermoplastic composite materials as the skin of the fuselage, wings, pressure bulkheads, floors and interior decoration structures, which greatly reduces the weight compared with metal structures, and gradually replaces metal materials due to the characteristics of light weight, high strength and corrosion resistance.

[0003] For the thermoplastic composite aircraft passenger cabin floor structure, the current main method is to manufacture the floor structure through hot pressing forming process, and connect the floor structures through certain methods, including mechanical connection and glue connection. Among them, the mechanical connection is to connect the floor through fasteners such as bolts or rivets (such as the aircraft passenger cabin floor connection method disclosed in document CN217198627U), but the introduced metal connecting pieces will weaken the lightweight effect, the workload is heavy, the efficiency is low, and stress concentration is easy to cause; the actual application of the glue connection structure (such as the manufacturing method of the composite material aircraft floor disclosed in document CN220865650U) is faced with the problems of long curing period, poor connection strength, weak environmental interference resistance, and performance degradation due to factors such as humidity fluctuation and chemical corrosion. Research shows that the connection strength can be improved by setting fiber materials at the connection parts of the aircraft structure, but one of the current technical difficulties is that the uniformity of the fiber material at the connection part cannot be guaranteed in the process of continuous connection, and the connection strength of different areas of the connection part is greatly different. More importantly, the vertical connection area of the lap joint connection part (welding part) of the aircraft structure has always been the weak connection area of the whole joint, especially the vertical connection area is prone to exist unmelted defects. Therefore, it is necessary to develop a new manufacturing method of the aircraft passenger cabin floor structure. SUMMARY

[0004] At least to solve the problems mentioned in the background, the application aims to provide a manufacturing method of an aircraft passenger cabin floor structure.

[0005] The application adopts the following technical scheme.

[0006] A manufacturing method of an aircraft passenger cabin floor structure, the aircraft passenger cabin floor structure is mainly composed of carbon fibers and resin materials, a plurality of component units are spliced together and then connected; the connection part of adjacent component units is provided with a grid-shaped carbon fiber and a chopped carbon fiber, part of the chopped carbon fiber is dispersed in the area where the grid-shaped carbon fiber is located, and the non-fiber occupying area of the connection part is filled with resin material, and the component unit body is obtained by filling the gap of a plurality of layers of grid-shaped carbon fibers arranged at intervals with resin material, and then hot pressing, cooling and shaping.

[0007] In order to further improve the connection strength of the aircraft cabin floor structure, the connecting part 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 part, and the vertical protrusion is located above the platform area.

[0008] In order to effectively prevent the vertical connecting area of the aircraft cabin floor structure from appearing unfusion defects, a plurality of transverse protrusions and a plurality of vertical protrusions are arranged on the first component unit; a plurality of transverse clamping grooves and vertical clamping grooves are arranged on the second component unit, the transverse clamping grooves are used for matching the transverse protrusions, the vertical clamping grooves are used for matching the vertical protrusions, and a plurality of recesses are arranged on the platform area of the second component unit.

[0009] The manufacturing method of the aircraft cabin floor structure comprises the following steps:

[0010] Step 1: according to the design requirements, the grid-shaped carbon fiber is cut and placed and fixed on the component unit mold;

[0011] Step 2: add molten resin into the component unit mold, after the molten resin impregnates the carbon fiber, cool and shape to obtain the component unit prepreg;

[0012] Step 3: heat press the obtained component unit prepreg, after demolding and cooling, carry out finishing processing to obtain the component unit;

[0013] Step 4: first, fix the second component unit in place, then lay the resin particles with chopped carbon fiber in the recesses on the second component unit, and pour a certain amount of molten resin into the clamping grooves; then, fix the first component unit in place, the vertical protrusions on the first component unit are matched in the vertical clamping grooves on the second component unit, the transverse protrusions on the first component unit are matched in the transverse clamping grooves on the second component unit, and the platform area on the first component unit covers the resin particles;

[0014] Step 5: use ultrasonic welding equipment to weld, and connect the plurality of first component units and the plurality of second component units together;

[0015] Step 6: post-treat the welded workpiece to obtain the aircraft cabin floor structure.

[0016] In order to further reduce the connection strength difference of different areas of the connection part of the aircraft passenger cabin floor structure, the step of finishing the second component unit in step 3 comprises: first processing a cross-bar slot in the platform area of the second component unit, then widening the intersection of the cross-bar slot into a pit, the depth of the cross-bar slot is not greater than 1 / 3 of the diameter of the resin particles, the width of the cross-bar slot is not greater than 1 / 3 of the diameter of the resin particles, and the width of the pit is not greater than 2 / 3 of the diameter of the resin particles; and processing a clamping groove on the second component unit.

[0017] Preferably, the platform area of the second component unit has a middle area and two edge areas, and the diameter of the resin particles in the middle area is greater than that in the edge area. The step of finishing the first component unit comprises: using machining to cut a plurality of horizontally arranged protrusions and a plurality of vertically arranged protrusions on the first component unit.

[0018] 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-bar slot are both 0.3mm, and the width of the pit is 0.5mm.

[0019] In the present application, the preparation step of the grid-shaped carbon fiber comprises: first pouring a layer of resin material with a thickness not exceeding 1mm on the laid grid-shaped carbon fiber fabric, and punching a hole in the non-fiber area of the thin sheet structure formed after the resin material is cured to obtain the grid-shaped carbon fiber.

[0020] Preferably, in the process of hot pressing, first, the initial pressure is 0.5-2.0 MPa, and the pressure is maintained for 5-10 minutes, and then the pressure is 2.0-4.0 MPa, and the pressure is maintained for 1-3 hours.

[0021] Beneficial effects: the scheme provided by the present application can not only significantly reduce the connection strength difference of different areas of the connection part of the aircraft passenger cabin floor structure, but also prevent the vertical connection area of the aircraft passenger cabin floor structure from having un-fusion defects, greatly improve the joint strength and stability of the aircraft passenger cabin floor structure, and realize the rapid forming of the passenger cabin floor structure. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a three-dimensional schematic view of the first component unit in Example 1.

[0023] Figure 2 It is a three-dimensional schematic view of the second component unit in Example 1.

[0024] Figure 3 It is a downward schematic view of the second component unit in Example 1.

[0025] Figure 4 Partial view of the grid-like carbon fiber of Example 1

[0026] In the figure: second component unit 1, vertical clamping slot 2, first vertical connecting area 3, inner side edge area 4, middle area 5, outer side edge area 6, second vertical connecting area 7, platform area 8, dimple 9, cross-shaped slot 10, vertical protrusion 11, first component unit 12, through hole 13, grid-like carbon fiber fabric 14, sheet-like structure 15, horizontal clamping slot 16, horizontal protrusion 17. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the scope of protection of the present application. In the present application, the short-cut carbon fiber (model 01299, brand Dongyiyang).

[0028] Example 1: Combination Figures 1 to 4As shown, the aircraft cabin floor structure is connected after being spliced together by a plurality of component units, the aircraft cabin floor structure is mainly composed of carbon fiber and resin material, the component unit has a platform area 8, a first vertical connecting area 3 and a second vertical connecting area 7, the connecting part of adjacent component units is provided with grid-shaped carbon fiber and chopped carbon fiber, part of the chopped carbon fiber is dispersed in the area where the mesh of the grid-shaped carbon fiber is located, the non-fiber occupying area of the connecting part is filled with resin material, and the body of the component unit is prepared by filling the gaps of several layers of grid-shaped carbon fiber arranged at intervals with resin material, and then heat pressing, cooling and shaping. Among them, the connecting part further includes a horizontal protrusion 17 and a vertical protrusion 11 grown on the body of the component unit, the horizontal protrusion 17 is located below the platform area 8 of the connecting part, and the vertical protrusion 11 is located above the platform area 8; A plurality of horizontally arranged horizontal protrusions 17 and a plurality of vertical protrusions 11 are arranged on the first component unit 12; A plurality of horizontal slots 16 and vertical slots 2 are arranged on the second component unit 1 (the first vertical connecting area 3 on the second component unit 1 is provided with a vertical slot 2, and the second vertical connecting area 7 on the second component unit 1 is provided with a horizontal slot 16), the horizontal slot 16 is used to cooperate with the horizontal protrusion 17, the vertical slot 2 is used to cooperate with the vertical protrusion 11, and a plurality of recesses 9 are arranged on the platform area 8 of the second component unit 1; The platform area 8 of the second component unit 1 has a middle area 5 and two edge areas (including an inner edge area 4 and an outer edge area 6), the resin particle diameter of the middle area 5 is larger than that of the edge area; The resin particle diameter of the middle area 5 is 1.2-1.3mm, the resin particle diameter of the edge area is 0.9-1mm, the width of the middle area 5 is 10-15mm, and the width of each edge area is 3-4mm; The depth and width of the cross-shaped slot 10 are both 0.3mm, and the width of the recess 9 is 0.5mm.

[0029] The manufacturing method of the aircraft cabin floor structure in this embodiment includes the following steps:

[0030] 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;

[0031] Among them, the preparation steps of the grid-shaped carbon fiber are as follows: first, pour a layer of resin material with a thickness not exceeding 1mm on the laid grid-shaped carbon fiber fabric 14, and punch a through hole 13 in the non-fiber area of the sheet-shaped structure 15 formed after the resin material is cured, to obtain the grid-shaped carbon fiber, which is a sheet structure similar to paper; The grid-shaped carbon fiber fabric 14 is pre-programmed according to the size requirements;

[0032] Step 2: Add molten resin to the component unit mold, and after the molten resin impregnates the carbon fiber, cool and shape to obtain a component unit prepreg;

[0033] Step 3, hot press forming is performed on the obtained component unit pre-preg, and after demolding and cooling, finishing is performed to obtain the component unit; during the hot press forming, first, pressure is maintained at an initial pressure of 0.5-2.0 MPa for 5-10 minutes, and then pressure is maintained at a pressure of 2.0-4.0 MPa for 1-3 hours;

[0034] In this step, the finishing step of the second component unit 1 includes: first, a cross-shaped strip-shaped groove 10 is processed on the platform area 8 of the second component unit 1, and then the intersection of the cross-shaped strip-shaped groove 10 is widened into a pit 9, the depth of the cross-shaped strip-shaped groove 10 is not greater than 1 / 3 of the diameter of the resin particles, the width of the cross-shaped strip-shaped groove 10 is not greater than 1 / 3 of the diameter of the resin particles, and the width of the pit 9 is not greater than 2 / 3 of the diameter of the resin particles; and a clamping groove is processed on the second component unit 1.

[0035] Step 4, first, the second component unit 1 is positioned and fixed, then resin particles with chopped carbon fibers are laid in the pit 9 on the second component unit 1, and a set amount of molten resin is poured into the clamping groove (the amount of cover resin is 1 / 2-2 / 3 of the volume of the clamping groove); then, the first component unit 12 is positioned (the second component unit 1 is located below the first component unit 12), and it is ensured that the vertical protrusions 11 on the first component unit 12 are fitted (clamped) into the vertical clamping grooves 2 on the second component unit 1, the horizontal protrusions 17 on the first component unit 12 are fitted (clamped) into the horizontal clamping grooves 16 on the second component unit 1, and the platform area 8 on the first component unit 12 covers the resin particles.

[0036] Step 5, welding is performed using an ultrasonic welding device to connect multiple first component units 12 and multiple second component units 1 together, and before welding, the component units need to be vacuum dried at 80-100 ℃ for 2-4 h; during the welding process, the resin is melted and re-shaped to be connected to each other and solidified to form a shape after cooling;

[0037] Step 6, post-processing is performed on the welded workpiece, including precise machining to remove excess material and polishing to the same surface roughness using a numerical control lathe, to obtain an aircraft passenger cabin floor structure.

[0038] In this embodiment, the preparation method of the resin particles is as follows: a double-screw extruder is used to melt the resin raw material, chopped fibers are added and stirred uniformly, the amount of the chopped fibers is 15% of the total volume of the resin particles, and after shearing and coating by the double-screw extruder, a granulator is used to obtain particles with a corresponding particle size.

[0039] In one application: the thickness of the prepared component unit is 8 mm; the thickness of the grid-shaped carbon fiber is 0.5 mm, the length of each grid of the grid-shaped carbon fiber is 10 mm, the diameter of the tows of the grid-shaped carbon fiber is 0.1 mm, and the diameter of the through holes of the grid-shaped carbon fiber is 5 mm; the resin material is polyether ether ketone; the diameter of the resin particles used in the middle region 5 is 1.2 mm, the diameter of the resin particles used in the edge region is 1 mm, the width of the middle region 5 is 12 mm, and the width of each edge region is 4 mm; the depth and width of the cross-shaped grooves 10 are both 0.3 mm, the width of the dimples 9 is 0.5 mm, and the distance between the adjacent edges of the parallel grooves of the cross-shaped grooves 10 is 5 mm; the depth of the cross-shaped grooves 10 is 1 / 3 of the diameter of the resin particles, the width of the cross-shaped grooves 10 is 1 / 3 of the diameter of the resin particles, the width of each clamping groove is 2 mm, the length of each clamping groove is 20 mm, and the height of each clamping groove is 4 mm; in step 5, the workpiece is preheated to 150°C and kept at a constant temperature, the welding tool head is perpendicular to the surface of the workpiece, the effective working surface diameter of the welding tool head is 30 mm, the amount of depression of the welding tool head is 0.8 mm (relative to the initial surface of the workpiece), the welding amplitude is 60 μm, the welding pressure is 0.2 MPa, and the welding speed is 15 mm / s; in the hot press forming process, the initial pressure is first kept at 1 MPa for 6 minutes, and then the pressure is kept at 3 MPa for 2 hours.

[0040] Comparative Example 1 is a method for manufacturing an aircraft passenger cabin floor structure, which is different from Example 1 in that the component unit adopts an integrally formed structure, and when the component unit is prepared, all the carbon fiber tows are first laid in the mold with a spacing of 10 mm, then the molten resin material is integrally poured and molded, and the protrusions and clamping grooves are finally finished.

[0041] Comparative Example 2 is a method for manufacturing an aircraft passenger cabin floor structure, which is different from Example 1 in that the cross-shaped grooves and dimples of the platform region are omitted, and the process of pouring molten resin into the clamping grooves is omitted; the component unit adopts an integrally formed structure, and when the component unit is prepared, the grid-shaped carbon fiber fabric is first laid in the mold, then the molten resin material is integrally poured and molded, and finally finished.

[0042] Comparative Example 3 is a method for manufacturing an aircraft passenger cabin floor structure, which is different from Example 1 in that the horizontal protrusions 17, vertical protrusions 11 and corresponding clamping grooves on the component unit are omitted, and the process of pouring molten resin into the clamping grooves is omitted; the component unit adopts an integrally formed structure, and when the component unit is prepared, the grid-shaped carbon fiber fabric is first laid in the mold, then the molten resin material is integrally poured and molded, and finally finished.

[0043] 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.

[0044] 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.

[0045] 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, with some of the chopped carbon fibers 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 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. The connection part also includes a transverse protrusion and a vertical protrusion grown on the component unit body, with the transverse protrusion being located below the platform area of ​​the connection part, and the vertical protrusion being located above the platform area. The steps of the manufacturing method 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.

2. The method for manufacturing an aircraft cabin floor structure according to claim 1, 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.

3. The method for manufacturing an aircraft cabin floor structure according to claim 2, 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.

4. The method for manufacturing an aircraft cabin floor structure according to claim 3, wherein: 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.

5. The method for manufacturing an aircraft cabin floor structure according to claim 4, 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.

6. The method for manufacturing an aircraft cabin floor structure according to any one of claims 1 to 5, 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.

7. The method for manufacturing an aircraft cabin floor structure according to claim 6, 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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