Method and device for wet laser cleaning of thick coatings on aircraft surfaces

Abstract

The application provides a kind of aircraft surface thick coating wet laser cleaning method and cleaning device, and cleaning method includes the following steps: deionized water, ethanol and TiO2 Powder are mixed according to certain proportion to prepare fireproof suspension liquid;Spray assembly is atomized with preset spray length The fireproof suspension liquid is sprayed onto the material matrix to form a spray area;Laser cleaning head emits laser beam to scan the material matrix to form a laser cleaning area, and the laser cleaning head can move in the preset direction to drive the laser cleaning area to move in the spray area, and clean the coating;Monitoring assembly monitors the laser cleaning area, and real-time controls the operating parameters of atomized spray assembly and laser cleaning head.The application can effectively solve the problem of coating powder spontaneous combustion during laser cleaning of metal-based coating, and the gasification and explosion of fireproof suspension liquid under the action of laser can improve the efficiency of laser cleaning by more than 50%.

Description

Technical Field

[0001] This invention relates to the field of laser cleaning processing technology, and more specifically, to a wet laser cleaning method and apparatus for thick coatings on aircraft surfaces. Background Technology

[0002] To achieve stealth capabilities and consistent surface quality, aircraft external skin structures typically undergo multi-layer coatings or paints after manufacturing to meet specific functional requirements such as aerodynamic consistency, high-temperature resistance, and abrasion resistance. Taking a titanium alloy stiffened outer skin panel as an example, after thermoforming and welding, the entire skin structure is ultimately coated with a high-temperature resistant, abrasion-resistant coating material with radar-specific properties. During subsequent aircraft service, this coating material often experiences localized peeling and wear due to various external factors. In such cases, the coating needs to be removed and recoated. Conventional coating removal methods typically involve mechanical grinding or sandblasting. The main problems with these methods are that mechanical grinding often damages the underlying substrate structure, causing scratches, while sandblasting is usually a large-area operation, making it difficult to precisely control the sandblasting range and removal depth, and it easily causes on-site sand contamination, making subsequent sand inclusion and cleaning very difficult.

[0003] Laser cleaning technology is simple to operate, uses fiber optic transmission, and achieves high surface cleanliness. It can effectively remove oil, rust, oxide layers, and other contaminants from material surfaces. At the same time, laser cleaning technology can control the damage to the substrate surface, making it an effective supplement to conventional removal methods.

[0004] Currently, the main problems encountered by laser cleaning in cleaning aircraft coatings are: first, the coating material is relatively thick, and conventional laser cleaning requires multiple scans, resulting in low cleaning efficiency; second, the powder generated during the coating cleaning process is highly flammable and can produce open flames, posing a serious safety hazard. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] The technical problem that this invention aims to solve is that existing laser cleaning technologies have low cleaning efficiency because the coating material is thick and requires multiple laser scans to clean aircraft coatings; moreover, the powder generated during the coating cleaning process is highly flammable and can produce open flames, posing a safety hazard.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a wet laser cleaning method for thick coatings on aircraft surfaces, used for cleaning coatings on a material substrate, the cleaning method comprising the following steps:

[0010] Step 1: Prepare a fire-retardant suspension according to the mass ratio of deionized water: ethanol: TiO2 powder = (3~9):(3~9):(1~3). Place the fire-retardant suspension in a glass container and stir it with a mechanical stirrer at a preset rotation speed to keep the TiO2 powder in a rotating state.

[0011] Step 2: The atomizing spray assembly sprays the fire-retardant suspension onto the material substrate at a preset spray length to form a spray area; the laser cleaning head emits a laser beam to scan the material substrate to form a laser cleaning area, and the laser cleaning head can move along a preset direction to drive the laser cleaning area to move within the spray area to clean the coating.

[0012] Step 3: The monitoring component monitors the laser cleaning area. The monitoring component includes a camera and an infrared thermometer. The infrared thermometer detects the temperature of the material substrate in the laser cleaning area in real time and adjusts the operating parameters of the atomizing spray component and the laser cleaning head in real time based on the temperature changes. The camera uses visual recognition technology to detect whether the material substrate is clean. If it is determined to be clean, the process ends; if it is determined to be not clean, Step 2 is repeated until it is determined to be clean.

[0013] Preferably, the operating parameters of the laser beam include: laser power, laser scanning width, laser scanning length, laser frequency, laser scanning speed, and travel speed.

[0014] Preferably, in step two, the operating parameters of the laser beam are set as follows: laser power is 1500W, laser scanning width K is 10mm, laser scanning length M is 100mm, laser frequency is 45KHz, laser scanning speed is 8000mm / s, and cleaning travel speed is 1.2m / min.

[0015] Preferably, the spray rate of the atomizing spray assembly is 5 ml / s to 25 ml / s.

[0016] Preferably, the preset rotation speed is 10 to 50 r / min.

[0017] Preferably, the laser cleaning head emits a laser beam to scan the material substrate with a preset scanning length M and a preset scanning width K, forming a laser cleaning area with a size of M×K; the atomizing spray assembly sprays the fire-retardant suspension onto the material substrate with a preset spray length S and a preset spray width H, forming a spray area with a size of S×H, wherein the preset scanning length M and the preset spray length S are perpendicular to the preset direction.

[0018] Preferably, the spray length S is greater than the preset scanning length M.

[0019] Preferably, the TiO2 powder has a particle size of less than 500 mesh.

[0020] Secondly, the present invention also provides a cleaning apparatus for implementing the wet laser cleaning method for thick coatings on machine surfaces as described in any of the above technical solutions. The cleaning apparatus includes: a frame, an atomizing spray assembly, a laser cleaning head, a monitoring assembly, a driving assembly, and a control assembly. The atomizing spray assembly is connected to the frame and is used to spray a fire-retardant suspension onto the material substrate to form a spray area. The laser cleaning head is connected to the frame and is used to emit a laser beam to scan the material substrate to form a laser cleaning area. The monitoring assembly includes a camera and an infrared thermometer connected to the frame. The infrared thermometer is used to detect the temperature of the material substrate in the laser cleaning area in real time. The camera is used to detect whether the material substrate is clean. The driving assembly is connected to the frame and is used to drive the frame to move in a preset direction. The control assembly is electrically connected to the driving assembly, the laser cleaning head, the monitoring assembly, and the atomizing spray assembly.

[0021] Preferably, the camera is a CCD camera.

[0022] (III) Beneficial Effects

[0023] The above-described technical solution of the present invention has at least the following advantages:

[0024] 1. The wet laser cleaning method for thick coatings on aircraft surfaces proposed in this invention involves mixing TiO2 powder as a combustion inhibitor with deionized water and ethanol to form a fire-retardant suspension, and then spraying the fire-retardant suspension onto the material substrate for wet laser cleaning. This method can suppress combustion and effectively solve the problem that the powder generated during the coating cleaning process is highly flammable and can produce open flames.

[0025] 2. In this invention, the wet medium formed by mixing TiO2 powder, deionized water and ethanol undergoes vaporization and explosion under the action of laser, which significantly improves the efficiency of laser cleaning. Compared with traditional dry laser cleaning, it significantly reduces the number of scans and improves efficiency by more than 50%.

[0026] 3. The wet laser cleaning method for thick coatings on aircraft surfaces provided by this invention, by using wet laser cleaning and adding TiO2 as a combustion inhibitor, makes it less likely for the laser beam to damage the material substrate during the laser cleaning process, and increases the ablation threshold by more than 30% under the same ablation conditions.

[0027] 4. The present invention also provides a cleaning device in which the monitoring component can adjust the operating parameters of the laser cleaning head and the atomizing spray component in real time according to the removal thickness, residue, spontaneous combustion of coating powder, and temperature change of the workpiece surface during laser cleaning, so as to realize automated cleaning of the material substrate. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic flowchart of a wet laser cleaning method for thick coatings on aircraft surfaces provided in an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the cleaning device provided in an embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram illustrating the implementation principle of the cleaning device provided in this embodiment of the invention.

[0032] The labels for the attached figures are as follows:

[0033] 10. Material substrate; 20. Coating; 1. Frame; 2. Atomizing spray assembly; 3. Laser cleaning head; 4. Monitoring assembly; 5. Control assembly; 6. Fireproof suspension; 7. Spraying area; 8. Laser cleaning area. Detailed Implementation

[0034] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0035] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be located directly on or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component.

[0036] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate that the device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or the number of technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. The specific implementation of this invention will be described in more detail below with reference to specific embodiments:

[0038] like Figure 2 and Figure 3As shown, this embodiment of the invention provides a cleaning device for cleaning a coating 20 on a material substrate 10, wherein the coating 20 is mainly a metal-based (Fe, Ni, etc.) coating material with a thickness of 0.1 to 2 mm, and the coating 20 covers the upper surface (aerodynamic surface of an aircraft) of the material substrate 10. The cleaning device includes: a frame 1, an atomizing spray assembly 2, a laser cleaning head 3, a monitoring assembly 4, a drive assembly (not shown), and a control assembly 5. The atomizing spray assembly 2 is connected to the frame 1 and is used to spray the fire-retardant suspension 6 onto the material substrate 10 to form a spray area 7. The laser cleaning head is connected to the frame and is used to emit a laser beam to scan the material substrate to form a laser cleaning area 8. The monitoring assembly 4 includes a camera and an infrared thermometer connected to the frame 1. The infrared thermometer is used to detect the temperature of the material substrate 10 in the laser cleaning area 8 in real time. The camera is used to detect whether the material substrate 10 is clean. The drive assembly is connected to the frame 1 and is used to drive the frame 1 to move in a preset direction. The control assembly 5 is electrically connected to the drive assembly, the laser cleaning head 3, the monitoring assembly 4, and the atomizing spray assembly 2. Specifically, the atomizing spray assembly 2 has a suction spray function, its main purpose being to spray the fire-retardant suspension 6 from the nozzle of the atomizing spray assembly 2 in the form of atomized water vapor. The spray rate of the atomizing spray assembly 2 is adjustable within the range of 5ml / S to 25ml / S. The spray area 7 generated by the atomizing spray assembly 2 can be approximated as a rectangular area, which is located in front of the laser cleaning area 8. The laser cleaning head 3 is a high-power two-dimensional scanning laser cleaning head, capable of laser scanning and editing two-dimensional graphics. The selected laser is a 2000W-level nanosecond pulse laser, and the laser cleaning head 3 can achieve graphic editing within a size range of 180mm x 40mm. The scanning speed of the laser cleaning head 3 is adjustable within the range of 1000mm / S to 10000mm / S. The atomizing spray assembly 2, the laser cleaning head 3, and the monitoring assembly 4 are connected as a whole by a mechanical connecting rod on the frame 1, and move synchronously along a preset direction during the laser cleaning process.

[0039] In one embodiment, the camera is a CCD camera. The camera uses visual recognition technology to detect whether the material substrate 10 is clean. This visual recognition technology is well known to those skilled in the art and will not be described in detail here. Specifically, it may include laser ranging technology (used to detect the cleaning thickness of the coating) and image recognition technology, etc.

[0040] like Figure 1 As shown, the present invention also provides a wet laser cleaning method for thick coatings on aircraft surfaces, used to clean coatings 20 on a material substrate 10. The cleaning method includes the following steps:

[0041] Step 1: Prepare a fire-retardant suspension according to the mass ratio of deionized water: ethanol: TiO2 powder = (3-9):(3-9):(1-3). Place the fire-retardant suspension 6 in a glass container and stir it mechanically at a preset rotation speed to keep the TiO2 powder in a rotating state. TiO2 powder is an inorganic oxide that can act as a combustion stabilizer and ablation-resistant material, and it is also a good combustion inhibitor, slowing down the combustion rate. Mix the TiO2 powder with deionized water and ethanol to form the fire-retardant suspension 6, and spray the fire-retardant suspension 6 onto the material substrate 10 to form a wet cleaning medium. Use a wet method for laser cleaning, which makes it less likely for the laser beam to damage the material substrate 10 during the laser cleaning process. Furthermore, the vaporization and explosion effects of the wet medium under laser action significantly improve the laser cleaning efficiency, significantly reducing the number of scans compared to traditional dry laser cleaning, and increasing efficiency by more than 50%.

[0042] Step 2: The atomizing spray assembly 2 sprays the fireproof suspension 6 onto the material substrate 10 at a preset spray length to form a spray area 7; the laser cleaning head 3 emits a laser beam 31 to scan the material substrate 10 to form a laser cleaning area 8, and the laser cleaning head 3 can move along a preset direction to drive the laser cleaning area 8 to move within the spray area 7 to clean the coating 20.

[0043] Step 3: The monitoring component 4 monitors the laser cleaning area 8. The monitoring component 4 includes a camera and an infrared thermometer. The infrared thermometer detects the temperature of the material substrate 10 in the laser cleaning area 8 in real time and adjusts the operating parameters of the atomizing spray component 2 and the laser cleaning head 3 in real time according to the temperature change. The camera uses visual recognition technology to detect whether the material substrate 10 is clean. If it is determined to be clean, the process ends; if it is determined to be not clean, the above step 2 is repeated until it is determined to be clean.

[0044] In one embodiment, the operating parameters of the laser beam 31 include: laser power, laser scanning width, laser scanning length, laser frequency, laser scanning speed, and travel speed.

[0045] In one embodiment, in step two, the operating parameters of the laser beam 31 are set as follows: laser power is 1500W, laser scanning width K is 10mm, laser scanning length M is 100mm, laser frequency is 45KHz, laser scanning speed is 8000mm / S, and cleaning travel speed is 1.2m / min.

[0046] In one embodiment, the spray rate of the atomizing spray component 2 is 5 ml / s to 25 ml / s.

[0047] In one embodiment, the preset rotation speed is 10 to 50 r / min.

[0048] In one embodiment, the laser cleaning head 3 emits a laser beam 31 to scan the material substrate 10 with a preset scanning length M and a preset scanning width K, forming a laser cleaning area 8 with a size of M×K; the atomizing spray assembly sprays the fireproof suspension 6 onto the material substrate 10 with a preset spray length S and a preset spray width H, forming a spray area 7 with a size of S×H, wherein the preset scanning length M and the preset spray length S are perpendicular to a preset direction.

[0049] In one embodiment, the spray length S is greater than the preset scanning length M, so that the spray area 7 can completely cover the laser cleaning area 8.

[0050] In one embodiment, the TiO2 powder has a particle size of less than 500 mesh.

[0051] The following is a specific embodiment provided by the present invention:

[0052] The substrate 10 is a 2mm thick TC4 titanium alloy, and the coating 20 is mainly composed of Fe and Ni metals, with a thickness of approximately 1.5mm. The cleaning laser is a domestically produced 2000W pulsed laser with a pulse width of 130ns and a laser frequency of 10–50kHz.

[0053] First, prepare the fire retardant suspension 6 by mixing deionized water, industrial ethanol, and TiO2 powder (800 mesh) in a mass ratio of 3:3:1. Place the prepared fire retardant suspension 6 in a glass container and stir it mechanically at a rotation speed of 30 r / min to keep the TiO2 powder in a rotating state.

[0054] Then, the material substrate 10 is placed within the reach of the laser cleaning, and the laser focus position is adjusted within ±5mm. The field of view of the CCD camera in the monitoring component 4 and the test area of ​​the infrared thermometer are adjusted so that the monitoring area is located inside the laser cleaning area 8. Next, the laser cleaning parameters of the laser beam are set: laser power 1500W, laser scanning width K is 10mm, length M is 100mm, laser frequency 45KHz, laser scanning speed 8000mm / S, and cleaning travel speed 1.2m / min. The spray rate of the atomizing spray component 2 is 10ml / S. Finally, the control component 5 is turned on to carry out the laser cleaning operation. After the laser cleaning is completed, the surface roughness, ablation condition, and coating removal condition of the workpiece are inspected. After processing, the titanium alloy surface coating is completely removed, the substrate surface has a bright white metallic luster, and the surface is smooth without ablation or pits.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wet laser cleaning method for thick coatings on aircraft surfaces, used for cleaning coatings on a material substrate, characterized in that, The cleaning method comprises the following steps: Step one, prepare a fireproof suspension according to the mass ratio of deionized water: ethanol: TiO2 powder=(3~9):(3~9):(1~3), store the fireproof suspension in a glass container and stir it at a preset rotation rate using mechanical stirring to keep the TiO2 powder in a rotating state; Step two, spray the fireproof suspension onto the material substrate to form a spraying area at a preset spraying length using the atomizing spraying assembly; a laser cleaning head emits a laser beam to scan the material substrate to form a laser cleaning area, and the laser cleaning head can move along a preset direction to drive the laser cleaning area to move within the spraying area to clean the coating; Step three, monitor the laser cleaning area using a monitoring assembly, which comprises a camera and an infrared thermometer; the infrared thermometer detects the temperature of the material substrate in the laser cleaning area in real time and adjusts the operating parameters of the atomizing spraying assembly and the laser cleaning head in real time according to the change in the temperature; the camera detects whether the material substrate is clean or not through visual recognition technology; if it is determined that the material substrate is clean, the process ends; if it is determined that the material substrate is not clean, repeat step two until it is determined that the material substrate is clean.

2. The method of claim 1, wherein the thickness of the coating is at least 0.5 mm. The operating parameters of the laser beam include laser power, laser scanning width, laser scanning length, laser frequency, laser scanning speed, and moving speed.

3. The method of claim 2, wherein the laser cleaning is performed with a wet laser cleaning process. In step two, the operating parameters of the laser beam are set as follows: laser power is 1500 W, laser scanning width K is 10 mm, laser scanning length M is 100 mm, laser frequency is 45 KHz, laser scanning speed is 8000 mm / S, and cleaning moving speed is 1.2 m / min. ​ 4. The method of wet laser cleaning of thick coatings on aircraft surfaces of claim 1, wherein, The spraying rate of the atomizing spraying assembly is 5 ml / S~25 ml / S.

5. The method of claim 1, wherein the thickness of the coating is at least 0.5 mm. The preset rotation rate is 10~50 r / min.

6. The method of wet laser cleaning of thick coatings on aircraft surfaces of claim 1, wherein, The laser cleaning head emits a laser beam to scan the material substrate at a preset scanning length M and a preset scanning width K to form a laser cleaning area with a size of M×K; the atomizing spraying assembly sprays the fireproof suspension onto the material substrate at a preset spraying length S and a preset spraying width H to form a spraying area with a size of S×H, wherein the preset scanning length M and the preset spraying length S are perpendicular to the preset direction.

7. The method of wet laser cleaning of thick coatings on aircraft surfaces of claim 6, wherein, The spraying length S is greater than the preset scanning length M.

8. The method of wet laser cleaning of thick coatings on aircraft surfaces of claim 1 wherein, The particle size of the TiO2 powder is less than 500 mesh.

9. A cleaning device for carrying out the method of wet laser cleaning of thick coatings on the surface of an aircraft according to any one of claims 1 to 8, characterized in that The cleaning device comprises: a rack; an atomizing spraying assembly connected to the rack for spraying a fireproof suspension onto the material substrate to form a spraying area; a laser cleaning head connected to the rack for emitting a laser beam to scan the material substrate to form a laser cleaning area; a monitoring assembly comprising a camera and an infrared thermometer connected to the rack, wherein the infrared thermometer is used to detect the temperature of the material substrate in the laser cleaning area in real time, and the camera is used to detect whether the material substrate is clean or not. A driving assembly is connected to the frame and used to drive the frame to move along a preset direction. A control assembly is electrically connected to the driving assembly, the laser cleaning head, the monitoring assembly and the atomizing spraying assembly.

10. The cleaning apparatus of claim 9, wherein The camera is a CCD camera.

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