Pre-maintenance pretreatment method and maintenance method of composite lightning protection component

Abstract

The invention relates to a pre-maintenance pretreatment method and a maintenance method of a composite lightning protection component. The pretreatment method before maintenance comprises the following steps: scanning a first area of the composite material lightning protection component by using laser with a first parameter so as to separate an interface between matrix resin and a reinforced fiber layer; the matrix resin and the metal net on the surface of the first area are removed, and the reinforced fiber layer below the metal net is reserved; carrying out ultrasonic vibration cleaning treatment on the composite material lightning protection component; and scanning the first area by using laser with a second parameter to remove residual pyrolysis products on the first area so as to obtain the maintained bonding surface. The laser treatment process not only can ensure the uniformity and consistency of a treatment area, has the characteristics of greenness, high efficiency and environmental protection, but also can accurately process different shapes according to a design scheme, and has the characteristics of being free, flexible, high in designability, high in adaptability and the like. According to the pretreatment method before maintenance, the parts are not prone to being damaged.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft structural component maintenance, and in particular to a pretreatment method before maintenance and a maintenance method for a composite material lightning protection component. Background Art

[0002] Fiber-reinforced composite materials have high specific strength and specific modulus, as well as excellent corrosion resistance and fatigue resistance. They are currently widely used in the aerospace field. For example, fiber-reinforced composite materials are gradually replacing aluminum alloys in the main load-bearing structures of aircraft (such as fuselage and wings) and secondary load-bearing structures (such as rudders and horizontal and vertical tails). Compared with traditional aluminum alloy materials, fiber-reinforced composite materials have lower thermal conductivity and electrical conductivity. It is difficult to avoid lightning strikes during the continuous operation of aircraft. The Joule heat generated by lightning will cause serious irreversible damage to composite components. Therefore, metal meshes, such as copper meshes, aluminum meshes, etc., are usually added to composite components as a lightning protection layer. The metal mesh can enhance the electrical conductivity of the component, so that most of the lightning current stays on the external structure and flows out quickly without causing serious damage to the composite components.

[0003] For composite components containing metal mesh, defects such as resin enrichment and resin depletion may occur during the manufacturing process due to improper pressure and temperature control in local areas. In order to avoid the scrapping of the entire high-value composite component, it is usually necessary to treat the defective area, the overall matrix resin and metal mesh, and perform subsequent repair work.

[0004] Traditional processing techniques for repairing bonding surfaces of composite components mainly include manual grinding and milling. For aircraft leading edge covers, air inlet lips, wingtip fairings, vertical tail root transition covers and other parts, they are high-value composite parts due to their large changes in three-dimensional curvature, high mold development costs, high labor costs and time costs. For the repair of high-value composite parts, refined processing is required. Traditional methods are prone to damage to parts and cause economic losses. Summary of the invention

[0005] Based on this, it is necessary to provide a pre-repair pretreatment method and a repair method for composite lightning protection components containing metal mesh.

[0006] One of the purposes of the present invention is to provide a pretreatment method for composite lightning protection components before maintenance, the scheme is as follows:

[0007] A pretreatment method for a composite lightning protection component before maintenance, the composite lightning protection component comprising a matrix resin, a reinforcing fiber layer and a metal mesh, the reinforcing fiber layer and the metal mesh are stacked and wrapped by the matrix resin; the pretreatment method before maintenance comprises the following steps:

[0008] Scanning a first area of ​​the composite lightning protection component using a laser with a first parameter to separate the interface between the matrix resin and the reinforcing fiber layer;

[0009] removing the matrix resin and the metal mesh on the surface of the first region, and retaining the reinforcing fiber layer under the metal mesh;

[0010] Performing ultrasonic vibration cleaning on the composite lightning protection component;

[0011] The first area is scanned using a laser with a second parameter to remove residual pyrolysis products on the first area to obtain a repair bonding surface.

[0012] In one embodiment, the first parameters include: a wavelength of 500 nm to 1200 nm, a power of 150 W to 300 W, a scanning speed of 3000 mm / s to 5000 mm / s, a line spacing of 0.04 mm to 0.06 mm, and a pulse width of 25 ns to 100 ns.

[0013] In one embodiment, the number of laser scans of the first parameter is 1 to 10 times;

[0014] In one embodiment, the laser of the first parameter is generated by one or more of a femtosecond laser, a picosecond laser, a Nd:YAG laser, a semiconductor laser and a fiber laser.

[0015] In one embodiment, the second parameters include: wavelength of 500 nm~1200 nm, power of 50W~100W, scanning speed of 2000mm / s~4000mm / s, line spacing of 0.01mm~0.03mm, and pulse width of 25ns~50ns.

[0016] In one embodiment, the number of laser scans of the second parameter is 1 to 10 times.

[0017] The laser of the second parameter is generated by one or more of a femtosecond laser, a picosecond laser, a Nd:YAG laser, a semiconductor laser and a fiber laser.

[0018] In one of the embodiments, before laser scanning, an ablation protection layer is disposed around the first region.

[0019] In one embodiment, the method of removing the matrix resin and the metal mesh on the surface of the first region includes removing them by clamping with a clamping tool.

[0020] In one embodiment, the ultrasonic vibration cleaning process includes:

[0021] The first ultrasonic cleaning is carried out at room temperature with an ultrasonic frequency of 20-40kHz and a cleaning time of 10-15 minutes;

[0022] The second ultrasonic cleaning is carried out at room temperature with an ultrasonic frequency of 100-120 kHz and a cleaning time of 8-15 min.

[0023] In one embodiment, the cleaning liquid for the ultrasonic vibration cleaning treatment is at least one of an alcohol solvent and a ketone solvent.

[0024] In one embodiment, the material of the base resin is at least one of epoxy resin, bismaleimide resin, polyimide, and cyanate resin.

[0025] In one embodiment, the material of the reinforcing fiber layer is at least one of carbon fiber, glass fiber, and basalt fiber.

[0026] In one embodiment, the material of the metal mesh is at least one of copper and its alloys, aluminum, iron and its alloys.

[0027] Another object of the present invention is to provide a repair method for composite material lightning protection components, the scheme is as follows:

[0028] A repair method for a composite material lightning protection component comprises the following steps:

[0029] The repair adhesive surface is obtained by processing the pre-repair pretreatment method described in any of the above embodiments;

[0030] A repair sheet is bonded on the repair bonding surface.

[0031] Compared with the traditional scheme, the pre-repair pretreatment method and maintenance method of the composite material lightning protection component have the following beneficial effects:

[0032] The pretreatment method and maintenance method of the composite lightning protection component before maintenance are to scan the first area of ​​the composite lightning protection component by adjusting the laser parameters, so that the interface between the matrix resin and the reinforcing fiber layer is separated, so that the matrix resin and the metal mesh on the surface of the first area are easily removed. Then the composite lightning protection component is subjected to ultrasonic vibration cleaning treatment to clean the residual pyrolytic carbon on the surface of the reinforcing fiber and the resin matrix fragments at the edge of the processing area, thereby reducing the difficulty of subsequent laser processing and the risk of damage to the fiber. The laser parameters are then adjusted to scan the first area to remove the residual pyrolysis products on the first area to obtain a clean and complete maintenance bonding surface. The laser processing process can not only ensure the uniformity and consistency of the processing area, and has the characteristics of being green, efficient and environmentally friendly, but also can accurately process different shapes according to the design plan, and has the characteristics of freedom, flexibility, strong designability and strong adaptability. The pretreatment method before maintenance is not easy to cause damage to parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a laser scanning area in a method for pre-treatment of a composite material lightning protection component before maintenance according to an embodiment;

[0034] Figure 2 Schematic diagram of laser process for stripping matrix resin with uneven thickness;

[0035] Figure 3 (a) is an electron microscope image of the fiber surface after step 3 of Example 1. Figure 3 (b) is an electron microscope image of the fiber surface after step 4 of Example 1. Figure 3 (c) is an electron microscope image of the fiber surface after step 5 of Example 1. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. The purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0037] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0038] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number or order of the indicated technical features.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0040] In order to reduce the damage caused by lightning strikes on aircraft, metal meshes, such as copper meshes and aluminum meshes, are usually added to composite components as a lightning protection layer. The metal mesh can enhance the electrical conductivity of the component, allowing most of the lightning current to stay on the external structure and flow out quickly without causing serious damage to the composite component.

[0041] The present invention provides a pretreatment method for composite lightning protection components containing metal mesh before maintenance. The composite lightning protection components are, for example, leading edge covers, air inlet lips, wing tip fairings, vertical tail root transition covers, etc. in aircraft.

[0042] The composite lightning protection component includes a matrix resin, a reinforcing fiber layer and a metal mesh. The reinforcing fiber layer and the metal mesh are stacked and wrapped by the matrix resin.

[0043] Optionally, the material of the matrix resin may be, but is not limited to, at least one of epoxy resin, bismaleimide resin, polyimide, and cyanate resin.

[0044] Optionally, the material of the reinforcing fiber layer may be but is not limited to at least one of carbon fiber, glass fiber, and basalt fiber.

[0045] Optionally, the material of the metal mesh may be, but is not limited to, at least one of copper and its alloys, aluminum, iron and its alloys.

[0046] A pretreatment method for a composite material lightning protection component before maintenance in one embodiment comprises the following steps:

[0047] Step S1, such as Figure 1 As shown, a laser with a first parameter is used to scan a first area 110 of the composite lightning protection component to separate the interface between the matrix resin and the reinforced fiber layer.

[0048] In step S1, by properly adjusting the laser parameters, the interface temperature can be effectively controlled to reach the matrix decomposition threshold but not the fiber damage threshold, so as to achieve interface separation of heterogeneous materials and facilitate the removal of the matrix resin and metal mesh in the first region 110. This process involves photothermal-induced thermal ablation, micro-explosion, and thermal vibration effects, so only low laser energy is required to slightly decompose the tightly fitted interface to achieve the removal of the target material.

[0049] In step S1 , the laser preferably has parameters of low lateral and longitudinal overlap rates, low total laser energy density and high single pulse laser energy density.

[0050] Among them, the total energy density (Et) is calculated by the formula: Et = laser power / (scanning speed × line spacing).

[0051] The calculation formula for single pulse energy density (Es) is: Es=laser power / (frequency×spot area).

[0052] In step S1 , the laser adopts parameters such as medium power, high speed, high spacing, low frequency, and low pulse width to achieve lower horizontal and vertical overlap rates, lower total energy density, and higher single pulse energy density.

[0053] In some of the examples, in step S1, the laser used is a nanosecond laser. Further, the wavelength of the laser is 500 nm to 1200 nm. In some of the examples, in step S1, the wavelength of the laser is 1064 nm.

[0054] In some examples, in step S1, a nanosecond pulse laser is used for scanning. Further, a nanosecond infrared fiber pulse laser is used, including but not limited to a femtosecond laser, a picosecond laser, a Nd:YAG laser, a semiconductor laser, a fiber laser, and the like.

[0055] In step S1 , the laser scanning path filling includes but is not limited to parallel line filling, bow-shaped line filling, concentric circle filling, round-shaped line filling, Z-shaped line filling, etc.

[0056] In some of the examples, in step S1, the power of the laser used is 150W~300W, for example, 150W, 160W, 180W, 200W, 220W, 240W, 260W, 280W, 300W, etc., or a range between any two of the above values.

[0057] In some of the examples, in step S1, the scanning speed of the laser used is 3000mm / s~5000mm / s, for example, 3000mm / s, 3200mm / s, 3400mm / s, 3600mm / s, 3800mm / s, 4000mm / s, 4200mm / s, 4500mm / s, 4800mm / s, etc., or a range between any two of the above values.

[0058] In some of the examples, in step S1, the line spacing of the laser used is 0.04mm~0.06mm, for example, 0.04mm, 0.042mm, 0.044mm, 0.046mm, 0.048mm, 0.05mm, 0.052mm, 0.054mm, 0.056mm, 0.058mm, 0.06mm, etc., or a range between any two of the above values.

[0059] In some of the examples, in step S1, the pulse width of the laser used is 25 ns~100 ns, for example, 25ns, 30ns, 35ns, 40ns, 45ns, 50ns, 55ns, 60ns, 65ns, 70ns, 80ns, 90ns, 100ns, etc., or a range between any two of the above values.

[0060] In step S1 , the shape of the first area 110 may be, but is not limited to, circular, elliptical, rectangular, etc.

[0061] In some of the examples, in step S1, the number of laser scans is 1 to 10 times, for example, 1 time, 2 times, 4 times, 6 times, and 8 times.

[0062] Step S2, removing the matrix resin and the metal mesh on the surface of the first area 110, and retaining the reinforcing fiber layer under the metal mesh.

[0063] In some examples, the method of removing the matrix resin and the metal mesh on the surface of the first region 110 includes removing them by clamping with a clamping tool.

[0064] Step S3, performing ultrasonic vibration cleaning treatment on the composite material lightning protection component.

[0065] Since the laser photothermal effect will produce a heat-affected zone at the edge of the processing area, causing some incompletely decomposed resin matrix to remain, the residual pyrolytic carbon on the surface of the reinforcing fiber and the resin matrix fragments at the edge of the processing area are cleaned by vibration. Based on this operation, the surface impurities are pre-cleaned and the metal mesh in the edge area is exposed to reduce the difficulty of laser processing of the second parameter and the risk of possible damage to the fiber.

[0066] Some examples of ultrasonic vibration cleaning processes include:

[0067] The first ultrasonic cleaning is carried out at room temperature using low-frequency ultrasound with a frequency of 20-40kHz and a cleaning time of 10-15 minutes;

[0068] The second ultrasonic cleaning uses high-frequency ultrasound at room temperature with a frequency of 100~120 kHz and a cleaning time of 8~15min.

[0069] The first ultrasonic cleaning removes large particles, such as resin particles on the heat-affected surface at the edge of the processing area. The second ultrasonic cleaning removes small particles of pyrolysis byproducts on the surface of the reinforcing fiber layer, such as carbon-based byproducts such as micron-sized pyrolysis carbon.

[0070] The cleaning liquid for ultrasonic vibration cleaning treatment may be, but is not limited to, an organic solvent such as an alcohol solvent, a ketone solvent, and specifically, anhydrous ethanol.

[0071] Step S4, using a laser with a second parameter to scan the first area 110 to remove the pyrolysis products remaining on the first area 110 to obtain a repair bonding surface.

[0072] In step S4, the laser parameters are preferably high lateral and vertical overlap rates and low total laser energy density.

[0073] In some of the examples, in step S4, the laser used is a nanosecond laser. Further, the wavelength of the laser is 500 nm to 1200 nm. In some of the examples, in step S4, the wavelength of the laser is 1064 nm.

[0074] In some of the examples, in step S4, a nanosecond pulse laser is used for scanning. Further, a nanosecond infrared fiber pulse laser is used, including but not limited to Nd:YAG laser, semiconductor laser, fiber laser, etc.

[0075] In step S4, the laser scanning path filling includes but is not limited to parallel line filling, bow-shaped line filling, concentric circle filling, round-shaped line filling, Z-shaped line filling, etc.

[0076] In some of the examples, in step S4, the power of the laser used is 50W~100W, for example, 50W, 55W, 60W, 65W, 70W, 75W, 80W, 85W, 90W, 95W, 100W, etc., or a range between any two of the above values.

[0077] In some of the examples, in step S4, the scanning speed of the laser used is 2000 mm / s~4000 mm / s, for example, 2200 mm / s, 2500 mm / s, 2800 mm / s, 3000 mm / s, 3200 mm / s, 3400 mm / s, 3600 mm / s, 3800 mm / s, 4000 mm / s, etc., or a range between any two of the above values.

[0078] In some of the examples, in step S4, the line spacing of the laser used is 0.01 mm to 0.03 mm, for example, 0.01 mm, 0.012 mm, 0.014 mm, 0.016 mm, 0.018 mm, 0.02 mm, 0.022 mm, 0.024 mm, 0.026 mm, 0.028 mm, 0.03 mm, etc., or a range between any two of the above values.

[0079] In some of the examples, in step S4, the pulse width of the laser used is 25 ns-50 ns, for example, 25 ns, 30 ns, 35 ns, 40 ns, 45 ns, 50 ns, etc., or a range between any two of the above values.

[0080] In step S4 , the shape of the first area 110 may be, but is not limited to, circular, elliptical, rectangular, etc.

[0081] In some of the examples, in step S4, the number of laser scans is 1 to 10 times, specifically, for example, 1 time, 2 times, 4 times, 6 times, and 8 times.

[0082] In some examples, before laser scanning, an ablation protection layer is provided at the periphery of the first region 110 (the second region 120) to prevent the flame generated in the subsequent processing from causing accidental damage to the non-processed region. The ablation protection layer may be, for example, a high-temperature fireproof tape.

[0083] In some of these examples, composite lightning protection components are cleaned by suction during laser scanning, for example by using a smoke purification device to adsorb the processing area to avoid accidental ablation of the material due to unstable flames.

[0084] Taking the infrared nanosecond pulse laser with a wavelength of 1064 nm as an example, according to the Planck equation, the energy of a single photon in the λ=1064 nm band is about 1.17 eV, which is difficult to directly destroy the CC bond (3.45 eV) and CO bond (3.38 eV) in the resin (such as but not limited to epoxy resin). Therefore, most of the laser energy directly penetrates the surface resin and acts on the surface of the reinforcing fiber (such as but not limited to carbon fiber). This unique interaction mode helps to separate the two heterogeneous materials from the inside.

[0085] The use of lasers with specific wavelengths can achieve directional micro-heating at the interface between the metal mesh, resin matrix and fiber. At the same time, the pyrolysis steam will produce micro-explosions due to internal space limitations, promoting the peeling between the metal mesh, resin matrix and fiber. In addition, there are huge differences in the physical properties of the three materials, resin matrix, metal mesh and fiber, and vibrations caused by thermal expansion will also occur at the interface to be separated.

[0086] In summary, in terms of mechanism, the peeling mechanism used in the present invention is mainly the complex synergistic effect of thermal ablation, micro-explosion and thermal vibration. Based on the above laser-material interaction mechanism, the present invention only needs to pyrolyze and remove a trace amount of interface resin to achieve the synchronous peeling of resin and metal mesh.

[0087] The significance of adopting one-time stripping is that the adhesive repair pays great attention to the surface quality of the exposed fiber, including surface cleanliness and fiber integrity. Excessive pyrolysis reaction makes it difficult to ensure the surface quality of the fiber. For example, using high laser energy to burn a large amount of resin will cause fiber damage and generate a large amount of impurities. Therefore, the one-time stripping process reduces the difficulty of subsequent cleaning, reduces the overall process energy consumption, and ensures the consistency of fiber surface quality.

[0088] The bonding mechanism is often used to explain the relationship between the physical and chemical properties of the surface and the bonding performance. Among them, mechanical interlocking, wetting and adsorption, and chemical bonding are the three most common bonding theories.

[0089] The study found that when the resin on the surface of the composite lightning protection component was completely removed by laser, the complete fiber bundles were exposed, and a directional fiber monofilament arrangement texture (gully-like texture) and a fiber multifilament weaving texture (equidistantly spaced pit texture) were obtained, forming an ordered surface pattern structure.

[0090] Laser treatment can promote mechanical interlocking. After laser treatment, a periodic structure (LIPSS) is formed on the surface of the composite lightning protection component. The high aspect ratio linear grooves formed by the gaps between the fiber monofilaments have a longitudinal length of about 2.1 mm, that is, the length of the weaving area; the maximum lateral gap width is 6 μm and the minimum can reach 0.8 μm (submicron level). In addition, the resin-rich area at the equidistant fiber weaving is laser ablated to form a cavity with a depth of about 67.8 μm (micron level).

[0091] Laser treatment can promote the wetting and adsorption effect. After laser treatment, the pits formed on the surface of the composite lightning protection component are filled with adhesive during bonding, playing a "micron-level anchoring role", and the gaps between the fibers are infiltrated by the adhesive, playing a "sub-micron-level mechanical interlocking role".

[0092] However, the surface structure formed by traditional pneumatic grinding has poor uniformity, and there are a lot of resin residues and fiber breakage. Its mechanical locking and wetting adsorption effects are weaker than the above-mentioned laser processing process.

[0093] The above-mentioned pre-repair method of the composite lightning protection component scans the first area 110 of the composite lightning protection component by adjusting the laser parameters, so that the interface between the matrix resin and the reinforcing fiber layer is separated, so that the matrix resin and the metal mesh on the surface of the first area 110 are easily removed. Then the composite lightning protection component is subjected to ultrasonic vibration cleaning treatment to clean the residual pyrolytic carbon on the surface of the reinforcing fiber and the resin matrix fragments at the edge of the processing area, thereby reducing the difficulty of subsequent laser processing and the risk of damage to the fiber. The laser parameters are then adjusted to scan the first area 110 to remove the residual pyrolysis products on the first area 110, and a clean and complete repair bonding surface is obtained. The laser processing process can not only ensure the uniformity and consistency of the processing area, and has the characteristics of green, high efficiency and environmental protection, but also can accurately process different shapes according to the design scheme, and has the characteristics of freedom, flexibility, strong designability and strong adaptability. The above-mentioned pre-repair method is not easy to cause damage to parts.

[0094] Furthermore, the present invention also provides a method for repairing a composite material lightning protection component.

[0095] A repair method for a composite material lightning protection component of an embodiment includes the following steps:

[0096] The repair adhesive surface is obtained by processing through any of the pre-repair pretreatment methods in the above examples;

[0097] A repair sheet is bonded on the repair bonding surface.

[0098] The following specific examples are provided to further illustrate the present invention. The present invention provides the following specific examples for a better understanding of the present invention, but is not limited to the specific implementation methods and does not limit the protection scope of the present invention.

[0099] Example 1

[0100] This embodiment provides a pretreatment method for composite lightning protection components before maintenance, comprising the following steps:

[0101] Step 1, preparation.

[0102] According to the maintenance design, high temperature fireproof tape is affixed around the target processing area on the surface of the composite lightning protection component.

[0103] Step 2: removing the matrix resin and the metal mesh in the first area 110 .

[0104] A 1064nm nanosecond flat-top fiber laser is used to scan the first region 110 of the composite lightning protection component. The matrix resin and the metal mesh on the surface of the first region 110 are removed, and the reinforcing fiber layer under the metal mesh is retained. The laser power is 200 W, the scanning speed is 4000 mm / s, the line spacing is 0.05 mm, and the pulse width is 50 ns.

[0105] like Figure 2 As shown in the figure, for the epoxy resin matrix, the transmission depth of the 1064 nm laser used in the experiment is as high as 0.9 m, so it is suitable for resin layers of different thicknesses, avoiding the influence of the thickness difference of the resin layer on the treatment effect.

[0106] Step 3: removing the matrix resin and the metal mesh on the surface of the first area 110 .

[0107] After the laser scanning is completed, the metal mesh and the resin layer on the first area 110 are completely peeled off from the surface of the composite lightning protection component using tweezers. Figure 3 As shown in (a), a large amount of resin, pyrolysis products and other residues remain on the fiber surface, and the pyrolysis products include carbon deposits, pyrolysis oil and the like.

[0108] Step 4: Perform ultrasonic vibration cleaning on the composite lightning protection components. Immerse the composite lightning protection components in anhydrous ethanol. Perform the first ultrasonic cleaning at room temperature using low-frequency ultrasound at a frequency of 30 kHz for 12 minutes. Perform the second ultrasonic cleaning at room temperature using high-frequency ultrasound at a frequency of 110 kHz for 12 minutes. Figure 3 As shown in (b), the residue on the fiber surface is significantly reduced.

[0109] Step 5: Laser clean the residue on the surface of the area to be bonded.

[0110] A 1064nm nanosecond flat-top fiber laser is used to scan the first area 110 of the composite lightning protection component. The power is 50 W, the scanning speed is 3000 mm / s, the line spacing is 0.02 mm, and the pulse width is 25 ns. A small amount of residual resin and pyrolysis products on the fiber surface are removed, such as carbon deposits, pyrolysis oil, etc. Figure 3 As shown in (c), a clean, complete and undamaged fiber surface to be bonded is obtained.

[0111] Pneumatic grinding has the following disadvantages:

[0112] The metal material used in lightning protection nets has high hardness and toughness. The hardness, toughness and grid structure of the material increase the difficulty of grinding. It is difficult for general grinding tools to evenly process all areas, especially grid intersections and corners. It is highly dependent on the proficiency of manual operation, and it is difficult to ensure the accuracy, uniformity and consistency of processing dimensions, which affects the maintenance effect. In addition, pneumatic grinding is inefficient, which increases the cycle and cost of composite material manufacturing.

[0113] Milling has the following disadvantages:

[0114] Inevitably, a large amount of dust is generated, which is harmful to the health of operators and the environment. Milling is a contact machining method. Mechanical action can cause a large number of fibers in composite parts to break, which can easily cause interface failure on the bonding surface, leading to debonding and other problems, and poor maintenance results. In addition, contact machining is prone to tool wear, which not only reduces machining accuracy, but also increases additional costs and time costs.

[0115] The present invention can achieve the following beneficial effects:

[0116] 1. Non-contact laser processing avoids the dust generated by traditional manual grinding, and is green, efficient and environmentally friendly;

[0117] 2. Based on multiple synergistic effects, the target material is stripped and removed, and the entire process only needs to adjust the laser parameters without any auxiliary means, which significantly reduces the overall energy consumption of the process and has the characteristics of energy saving and high efficiency;

[0118] 3. Slightly decompose the interface to achieve material stripping and removal, avoiding the by-products produced by resin pyrolysis, and obtaining excellent surface quality (including cleanliness and integrity) to be bonded;

[0119] 4. The oxygen-free thermal decomposition mode is achieved by penetrating the surface resin matrix and heating the internal interface, so that the structure of the fiber surface after treatment is intact and undamaged;

[0120] 5. The laser treatment method retains the fiber micron and submicron structure, enhances the mechanical interlocking and wetting adsorption effects, and improves the bonding effect after repair;

[0121] 6. Laser technology can accurately process different shapes, such as circles, ovals, rectangles, etc. according to the design plan. It has the advantages of freedom, flexibility, strong designability and strong adaptability.

[0122] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0123] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A pretreatment method for a composite lightning protection component before maintenance, wherein the composite lightning protection component comprises a matrix resin, a reinforcing fiber layer and a metal mesh, wherein the reinforcing fiber layer and the metal mesh are stacked and wrapped by the matrix resin; characterized in that: The pre-repair pretreatment method comprises the following steps: Scanning a first area of ​​the composite lightning protection component using a laser with a first parameter to separate the interface between the matrix resin and the reinforcing fiber layer; removing the matrix resin and the metal mesh on the surface of the first region, and retaining the reinforcing fiber layer under the metal mesh; Performing ultrasonic vibration cleaning on the composite material lightning protection component; The first area is scanned using a laser with a second parameter to remove residual pyrolysis products on the first area to obtain a repair bonding surface.

2. The pre-treatment method before maintenance according to claim 1, characterized in that: The first parameters include: wavelength of 500nm~1200nm, power of 150W~300W, scanning speed of 3000mm / s~5000mm / s, line spacing of 0.04mm~0.06mm, and pulse width of 25ns~100ns.

3. The pre-treatment method before maintenance according to claim 2, characterized in that: The pre-repair pretreatment method meets at least one of the following characteristics (1) to (2): (1) The number of laser scans of the first parameter is 1 to 10 times; (2) The laser with the first parameter is generated by one or more of a femtosecond laser, a picosecond laser, a Nd:YAG laser, a semiconductor laser and a fiber laser.

4. The pre-treatment method before maintenance according to claim 1, characterized in that: The second parameters include: wavelength of 500nm~1200nm, power of 50W~100W, scanning speed of 2000mm / s~4000mm / s, line spacing of 0.01mm~0.03mm, and pulse width of 25ns~50ns.

5. The pre-treatment method before maintenance according to claim 4, characterized in that: The pre-repair pretreatment method meets at least one of the following characteristics (1) to (2): (1) The number of laser scans of the second parameter is 1 to 10 times; (2) The laser of the second parameter is generated by one or more of Nd:YAG laser, semiconductor laser and fiber laser.

6. The pre-repair pretreatment method according to any one of claims 1 to 5, characterized in that: Before laser scanning, an ablation protection layer is arranged around the periphery of the first region.

7. The pre-treatment method before maintenance according to any one of claims 1 to 5, characterized in that: The method of removing the matrix resin and the metal mesh on the surface of the first region includes removing them by clamping with a clamping tool.

8. The pre-repair pretreatment method according to any one of claims 1 to 5, characterized in that: The ultrasonic vibration cleaning process comprises: The first ultrasonic cleaning is carried out at room temperature with an ultrasonic frequency of 20-40kHz and a cleaning time of 10-15 minutes; The second ultrasonic cleaning is carried out at room temperature with an ultrasonic frequency of 100 to 120 kHz and a cleaning time of 8 to 15 minutes; and / or The cleaning liquid for the ultrasonic vibration cleaning treatment is at least one of an alcohol solvent and a ketone solvent.

9. The pre-repair pretreatment method according to any one of claims 1 to 5, characterized in that: The material of the matrix resin is at least one of epoxy resin, bismaleimide resin, polyimide and cyanate resin; and / or The material of the reinforcing fiber layer is at least one of carbon fiber, glass fiber, and basalt fiber; and / or The material of the metal mesh is at least one of copper and its alloys, aluminum, iron and their alloys.

10. A method for repairing a composite material lightning protection component, characterized in that: The following steps are involved: The repair adhesive surface is obtained by processing the repair pretreatment method according to any one of claims 1 to 9; A repair sheet is bonded on the repair bonding surface.

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