Method for improving internal quality of main spar of unmanned aerial vehicle

Abstract

The invention belongs to the technical field of unmanned aerial vehicle manufacturing, and provides a method for improving the internal quality of a main spar of an unmanned aerial vehicle, which comprises the following steps: paving an M55J semi-prepreg on the outer surface of a core mold, and performing pre-compaction operation once every 3-5 layers; winding a layer of BOPP (Biaxially-oriented Polypropylene) belt and a layer of PET (Polyethylene Terephthalate) belt on the outer side of the M55J half prepreg in sequence; the outer side of the PET belt is wrapped with a layer of first breathable felt, and two pieces of resin-free glass cloth are laid on the outer side of the first breathable felt; hanging the core mold on a bracket vehicle on which a layer of demolding cloth, two layers of second breathable felts and a layer of vacuum bag film are laid in advance; a plurality of thermocouples are arranged in the core mold, and the two ends of the core mold are connected with vacuum pumping connectors; performing vacuum packaging by using a vacuum bag film which is laid on a bracket vehicle in advance; the outer side of the vacuum bag film is wrapped with two layers of second breathable felts and a layer of demolding cloth which are laid on the bracket vehicle in advance in the annular direction; two ends of the core mold are respectively connected with an oven, and curing parameters are set for curing. The internal quality of the main spar of the unmanned aerial vehicle can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of unmanned aerial vehicle manufacturing, and in particular relates to a method for improving the internal quality of a main wing beam of a unmanned aerial vehicle. Background Art

[0002] The main wing beam of the UAV is the main load-bearing element of the UAV wing structure. It is 20 meters long and bears most of the lift and overload during flight.

[0003] The main wing beam of the UAV manufactured by traditional methods has excessive internal defect sizes and a large number of defects, and the internal quality cannot meet the technical requirements for acceptance. The main reasons include the following: 1. The main wing beam of the UAV is too long, and there is a lack of an autoclave of sufficient length, so the autoclave cannot be used for pressurization during the curing of the main wing beam of the UAV; 2. The main wing beam of the UAV is made of M55J full prepreg, which has poor gas conductivity during the curing process and poor gas discharge effect inside the prepreg; 3. The traditional method uses BOPP tape to wrap once and PET tape to wrap twice. The number of wrappings is too many, the permeability is poor, and to a certain extent, the gas discharge in the prepreg is blocked; 4. The main wing beam of the aircraft is long, and the number of vacuum exhaust joints is small, resulting in poor gas conductivity in the vacuum bag, causing gas residue in the vacuum bag; 5. The core mold of the main wing beam of the UAV is too long (20 meters), and the thermocouples are only arranged at both ends of the core mold, and cannot be arranged in the middle of the core mold, resulting in a large temperature difference at different length positions of the core mold during the curing process, resulting in inconsistent curing rates at different length positions of the main wing beam of the UAV; 6. The core mold of the main wing beam of the UAV is long and heavy, and the heating rate of the core mold is much lower than the heating rate of the air in the oven, resulting in the curing speed of the outer skin of the main wing beam of the UAV being higher than that of the inside of the main wing beam of the UAV, which in turn makes it impossible to discharge the gas inside the main wing beam of the UAV.

[0004] Therefore, how to provide a method for improving the internal quality of the main wing beam of a UAV is a technical problem that people in this field urgently need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a method for improving the internal quality of the main wing beam of a UAV, so as to solve the above-mentioned problem and achieve the purpose of improving the internal quality of the main wing beam of a UAV.

[0006] To achieve the above object, the present invention provides the following solution: A method for improving the internal quality of the main wing beam of a drone, comprising the following steps:

[0007] S1. Lay M55J semi-preg on the outer surface of the core mold, and perform pre-compaction operation every 3 to 5 layers;

[0008] S2. After all the M55J semi-pregs are laid, a layer of BOPP tape and a layer of PET tape are wrapped around the outside of the M55J semi-pregs in sequence;

[0009] S3, wrapping a first air-permeable felt around the outside of the PET tape, laying two resin-free glass cloths on the outside of the first air-permeable felt, and the two resin-free glass cloths are symmetrically arranged about the axis of the core mold;

[0010] S4, hanging the core mold on a bracket car on which a layer of demoulding cloth, two layers of second breathable felt and a layer of vacuum bag film are pre-laid;

[0011] S5. Arrange several thermocouples in the core mold and connect vacuum exhaust joints at both ends of the core mold;

[0012] S6, vacuum packaging using a vacuum bag film pre-laid on the carriage;

[0013] S7, wrapping two layers of second breathable felt and one layer of release cloth pre-laid on the bracket car around the outside of the vacuum bag film;

[0014] S8. Connect both ends of the core mold to an oven, set curing parameters, and perform curing.

[0015] Preferably, in step S2, the winding tension of the BOPP tape is 5 kg, and the winding tape distance is 4 mm; the winding tension of the PET tape is 4 kg, and the winding tape distance is 6 mm.

[0016] Preferably, in step S3, the length of the resin-free glass cloth is 1 / 4 of the circumference of the first air-permeable felt.

[0017] Preferably, in step S5, the thermocouples are respectively arranged inside the core mold, at both ends of the M55J semi-preg, and on the side walls of the core mold close to the M55J semi-preg.

[0018] Preferably, in step S5, the vacuum pumping connectors are arranged in a W-shaped arrangement with intervals.

[0019] Preferably, in step S9, the curing parameters include:

[0020] Temperature control method: mold temperature control; mold deviation: 5℃; mold space deviation: 20℃.

[0021] Preferably, in step S1, the core mold is a hollow structure, and a plurality of steel pipes are detachably connected to the core mold, and the plurality of steel pipes are respectively arranged parallel to the axis of the core mold;

[0022] A plurality of vent holes are respectively provided on both end surfaces of the core mold, and the vent holes are used to allow the plurality of steel pipes to pass through the core mold.

[0023] Preferably, one end and the middle of the steel pipe are respectively provided with thermocouple fixing grooves, and the thermocouple fixing grooves are used to fix the thermocouple on the steel pipe;

[0024] The surface of the thermocouple in the thermocouple fixing groove is covered with a heat insulating material.

[0025] Preferably, the wall thickness of the steel pipe is the same as the wall thickness of the core mold.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] 1. On the premise that the curing equipment is an oven, the internal quality of the main wing beam of the UAV is improved, and the size and number of internal defects of the product meet the technical requirements for acceptance, so that the main wing beam of the UAV can be delivered smoothly.

[0028] 2. The main wing beam material of the UAV was replaced with M55J semi-preg with better gas conductivity, which solved the problem of poor gas discharge effect inside the prepreg.

[0029] 3. The number of wrappings of the PET tape was changed from 2 to 1, which reduced the number of wrappings and enhanced the permeability, allowing the gas in the prepreg to be discharged smoothly.

[0030] 4. Two pieces of resin-free glass cloth can enhance the gas conductivity in the vacuum bag; the arrangement of the vacuum exhaust joint solves the problem of poor gas conductivity in the vacuum bag of the main wing beam of the drone and residual gas in the vacuum bag.

[0031] 5. Both ends of the core mold are connected to the oven respectively, so that hot air can circulate inside the core mold during the curing process, which can make the core mold evenly heated from the inside. Several thermocouples can simulate the temperature of the outer wall of the core mold. The set special curing parameters solve the problem of large temperature difference at different length positions of the core mold during the curing process and inconsistent curing rate at different length positions of the main wing beam of the UAV.

[0032] 6. Two layers of breathable felt and one layer of demoulding cloth are wrapped around the outside of the vacuum bag, which plays a heat-insulating role during the curing process, preventing the hot air in the oven from heating the outer skin of the main wing spar, so that the inner layer of the main wing spar of the drone cures before the outer skin, solving the problem that the outer skin of the main wing spar of the drone cures faster than the inside of the main wing spar of the drone, resulting in the inability to discharge the gas inside the main wing spar of the drone. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a schematic diagram of the curing state of the present invention;

[0035] Figure 2 It is a radial cross-sectional schematic diagram of the core mold in the solidified state of the present invention;

[0036] Figure 3 It is a schematic diagram of the core mold of the present invention;

[0037] Figure 4 is a schematic diagram of a steel pipe of the present invention;

[0038] Among them, 1. core mold; 2. M55J semi-preg; 3. BOPP tape; 4. PET tape; 5. first breathable felt; 6. resin-free glass cloth; 7. vacuum bag film; 8. second breathable felt; 9. demoulding cloth; 10. bracket car; 11. thermocouple; 12. steel pipe; 13. blowing duct; 14. suction duct; 15. oven; 101. vent; 1201. thermocouple fixing groove; 1501. air inlet; 1502. air outlet. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Reference Figure 1-Figure 4 The present invention provides a method for improving the internal quality of the main wing beam of an unmanned aerial vehicle, comprising the following steps:

[0042] S1, laying M55J semi-preg 2 on the outer surface of the core mold 1, and performing a pre-compacting operation every 3 to 5 layers;

[0043] In step S1, the M55J semi-preg 2 is a prepreg in which the resin film is only coated on one side of the carbon fiber. The gas conductivity of the M55J semi-preg 2 during the curing process is better than that of the conventionally used M55J full prepreg, which can effectively solve the problem of poor gas discharge effect inside the prepreg.

[0044] S2. After all the M55J semi-pregs 2 are laid, a layer of BOPP tape 3 and a layer of PET tape 4 are successively wrapped around the outside of the M55J semi-pregs 2;

[0045] S3, wrapping a first air-permeable felt 5 around the outside of the PET tape 4, laying two resin-free glass cloths 6 on the outside of the first air-permeable felt 5, and the two resin-free glass cloths 6 are symmetrically arranged about the axis of the core mold 1;

[0046] In step S3, after the first air-permeable felt 5 is wrapped, it is fixed with a pressure-sensitive tape, and after the resin-free glass cloth 6 is laid, it is also fixed with a pressure-sensitive tape.

[0047] S4, hanging the core mold 1 on a bracket 10 on which a layer of release cloth 9, two layers of second breathable felt 8 and a layer of vacuum bag film 7 are pre-laid;

[0048] S5. Arrange a plurality of thermocouples 11 in the core mold 1, and connect vacuum exhaust joints at both ends of the core mold 1;

[0049] In step S5, a vacuum measuring joint (not shown in the figure) needs to be arranged. The vacuum measuring joint is evenly arranged at intervals of 2 to 3 meters along the axial direction of the core mold 1, and the vacuum measuring joint should be arranged as far away from the vacuum exhaust joint as possible.

[0050] S6, vacuum packaging is performed using the vacuum bag film 7 pre-laid on the bracket vehicle 10;

[0051] In step S6, after the vacuum bag film 7 is wrapped around the main wing beam of the drone, a sealing tape is used to achieve vacuum packaging. After that, the vacuum-packaged parts are connected to a vacuum system (not shown in the figure) for vacuum treatment, the vacuum degree must be not less than 0.092MPa, and the air tightness is checked to ensure that there is no leakage during subsequent operations.

[0052] S7, wrapping two layers of second breathable felt 8 and a layer of release cloth 9 pre-laid on the bracket 10 around the outside of the vacuum bag film 7;

[0053] In step S7, the vacuum bag film 7 is wrapped with two layers of the second air-permeable felt 8 and the release cloth 9, and then fixed with a pressure-sensitive tape.

[0054] The function of the second breathable felt 8 and the release cloth 9 is to prevent the hot air in the oven 15 from blowing directly to the vacuum bag film 7 during the curing process, so as to avoid the problem that the gas inside the main wing beam of the drone cannot be discharged due to the curing speed of the outer skin of the drone main wing beam being higher than that of the inside of the drone main wing beam.

[0055] S8. Both ends of the core mold 1 are connected to the oven 15, and curing parameters are set to perform curing.

[0056] According to a further optimization scheme, in step S2, the winding tension of the BOPP tape 3 is 5 kg, the winding tape distance is 4 mm, and the winding tension of the PET tape 4 is 4 kg, and the winding tape distance is 6 mm.

[0057] According to a further optimization scheme, in step S3 , the length of the resin-free glass cloth 6 is 1 / 4 of the circumference of the first air felt 5 .

[0058] like Figure 2 As shown, the role of laying the resin-free glass cloth 6 is to enhance the gas conductivity within the vacuum bag film 7.

[0059] To further optimize the solution, in step S5, the thermocouples 11 are respectively arranged inside the core mold 1, at both ends of the M55J semi-preg 2, and on the side walls of the core mold 1 close to the M55J semi-preg 2.

[0060] To further optimize the solution, in step S5, the vacuum exhaust connectors are arranged in a W-shape with an interval of 1 meter.

[0061] Further optimizing the scheme, in step S9, the curing parameters include:

[0062] Temperature control method: mold temperature control; mold deviation: 15℃; mold space deviation: 20℃.

[0063] Further optimizing the scheme, in step S1, the core mold 1 is a hollow structure, and a plurality of steel pipes 12 are detachably connected to the core mold 1, and the plurality of steel pipes 12 are respectively arranged parallel to the axis of the core mold 1;

[0064] A plurality of vent holes 101 are respectively provided on both end surfaces of the core mold 1 , and the plurality of vent holes 101 are used to allow a plurality of steel pipes 12 to pass through the core mold 1 .

[0065] According to a further optimization scheme, a thermocouple fixing groove 1201 is respectively provided at one end and the middle of the steel pipe 12, and the thermocouple fixing groove 1201 is used to fix the thermocouple 11 on the steel pipe 12;

[0066] The surface of the thermocouple 11 in the thermocouple fixing groove 1201 is covered with a heat insulating material.

[0067] To further optimize the solution, the method of arranging the thermocouple 11 inside the core mold 1 is:

[0068] First, the thermocouple 11 is inserted into the end opening of the steel pipe 12 and fixed in the thermocouple fixing groove 1201. The thermocouple 11 is closely attached to the inner wall of the steel pipe 12 and covered with a heat insulating material. Figure 1 As shown, one end of a plurality of steel pipes 12 fixedly connected with thermocouples 11 is respectively inserted into the interior of the core mold 1 through the vent holes 101 at both ends of the core mold 1. Since the thermocouples 11 are arranged at the ends and the middle of the steel pipe 12, by matching the lengths of the steel pipe 12 and the core mold 1, the effect of evenly arranging the plurality of thermocouples 11 at equal intervals inside the core mold 1 along the axial direction of the core mold 1 can be achieved.

[0069] Further optimization scheme, such as Figure 1As shown, a blowing duct 13 and a suction duct 14 are provided in the oven 15. After the second breathable felt 8 and the demoulding cloth 9 are wrapped on the outside of the vacuum bag film 7, the two ends of the core mold 1 are connected to the blowing duct 13 and the suction duct 14 respectively, and the other end of the blowing duct 13 is connected to the air inlet 1501 inside the oven 15; the suction duct 14 is connected to the air outlet 1502 inside the oven 15. The oven 15 is started, so that hot air enters into the core mold 1 through the blowing duct 13 and the vent 101, and is discharged from the vent 101 on the other side of the core mold 1, and enters into the air outlet 1502 through the suction duct 14, thereby forming a hot air flow in the core mold 1.

[0070] According to a further optimization scheme, the wall thickness of the steel pipe 12 is the same as the wall thickness of the core mold 1 .

[0071] like Figure 1 As shown, the purpose of having the wall thickness of the steel pipe 12 being the same as or close to the wall thickness of the core mold 1 is to make the time for heat to be conducted from the inside of the core mold 1 to the inner wall of the steel pipe 12 close to the time for heat to be conducted from the inside of the core mold 1 to the outer wall of the core mold 1, thereby making the temperature of the thermocouple 11 close to the inner wall of the steel pipe 12 close to the temperature of the outer wall of the core mold 1.

[0072] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0073] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for improving the internal quality of the main wing beam of an unmanned aerial vehicle, characterized in that , including the following steps: S1, laying M55J semi-preg (2) on the outer surface of the core mold (1), and performing a pre-compacting operation every 3 to 5 layers; S2. After all the M55J semi-pregs (2) are laid, a layer of BOPP tape (3) and a layer of PET tape (4) are successively wrapped around the outer side of the M55J semi-pregs (2); S3, wrapping a first air-permeable felt (5) around the outside of the PET tape (4), laying two pieces of resin-free glass cloth (6) on the outside of the first air-permeable felt (5), the two pieces of resin-free glass cloth (6) being symmetrically arranged about the axis of the core mold (1); S4, hanging the core mold (1) on a carriage (10) on which a layer of demoulding cloth (9), two layers of second breathable felt (8) and a layer of vacuum bag film (7) are pre-laid; S5. Arrange a plurality of thermocouples (11) in the core mold (1), and connect vacuum exhaust joints at both ends of the core mold (1); S6, performing vacuum packaging using a vacuum bag film (7) pre-laid on a carriage (10); S7, wrapping two layers of second air-permeable felt (8) and a layer of release cloth (9) pre-laid on a carriage (10) around the outside of the vacuum bag film (7); S8. Both ends of the core mold (1) are connected to an oven (15) respectively, and curing parameters are set to perform curing.

2. A method for improving the internal quality of the main wing beam of an unmanned aerial vehicle according to claim 1, characterized in that: In step S2, the winding tension of the BOPP tape (3) is 5 kg, and the winding tape distance is 4 mm; the winding tension of the PET tape (4) is 4 kg, and the winding tape distance is 6 mm.

3. The method for improving the internal quality of the main wing beam of an unmanned aerial vehicle according to claim 1, characterized in that: In step S3, the length of the resin-free glass cloth (6) is 1 / 4 of the circumference of the first air-permeable felt (5).

4. The method for improving the internal quality of the main wing beam of an unmanned aerial vehicle according to claim 1, characterized in that: In step S5, the thermocouples (11) are respectively arranged inside the core mold (1), at both ends of the M55J semi-preg (2), and on the side walls of both ends of the core mold (1) close to the M55J semi-preg (2).

5. The method for improving the internal quality of the main wing beam of an unmanned aerial vehicle according to claim 1, characterized in that: In step S5, the vacuum exhaust joints are arranged in a W-shape with an interval of 1 meter.

6. The method for improving the internal quality of the main wing beam of an unmanned aerial vehicle according to claim 1, characterized in that: In step S9, the curing parameters include: Temperature control method: mold temperature control; mold deviation: 15℃; mold space deviation: 20℃.

7. The method for improving the internal quality of the main wing beam of an unmanned aerial vehicle according to claim 1, characterized in that: In step S1, the core mold (1) is a hollow structure, and a plurality of steel pipes (12) are detachably connected to the core mold (1), and the plurality of steel pipes (12) are respectively arranged parallel to the axis of the core mold (1); A plurality of vent holes (101) are respectively provided on both end surfaces of the core mold (1), and the plurality of vent holes (101) are used to allow the plurality of steel pipes (12) to pass through the core mold (1).

8. The method for improving the internal quality of the main wing beam of an unmanned aerial vehicle according to claim 7, characterized in that: One end and the middle of the steel pipe (12) are respectively provided with thermocouple fixing grooves (1201), and the thermocouple fixing grooves (1201) are used to fix the thermocouple (11) on the steel pipe (12); The surface of the thermocouple (11) in the thermocouple fixing groove (1201) is covered with a heat insulating material.

9. A method for improving the internal quality of the main wing beam of an unmanned aerial vehicle according to claim 8, characterized in that: The wall thickness of the steel pipe (12) is the same as the wall thickness of the core mold (1).

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