Low-temperature plasma jet paint removal method

Abstract

The invention discloses a low-temperature plasma jet paint removal method, and relates to the technical field of paint removal of aviation parts, whole machine surfaces and the like, and the method comprises the following steps: 1, selecting the type and specification of a plasma jet generator according to the material, the shape size and the application scene of a part matrix; 2, proper process gas is selected according to main components of the paint layer; 3, selecting plasma jet paint removal process parameters according to the thickness and adhesion state of the paint layer and paint removal requirements; and fourthly, the surface of the part is scanned in a reciprocating mode in a handheld or mechanical arm clamping mode, and the paint layer removing effect is achieved. The conventional aviation paint on the surfaces of the metal base material part and the composite material base material part is effectively removed, and the maximum paint removal efficiency of a thin paint layer (the thickness is less than or equal to 0.3 mm) reaches about 1m < 2 > / h; and meanwhile, the plasma jet temperature and process parameters are controlled, so that damage to the matrix is effectively avoided.

Description

Technical Field

[0001] This invention discloses a low-temperature plasma jet paint removal method, which relates to the field of paint removal technology for aerospace parts, aircraft surfaces, etc. Background Technology

[0002] Traditional paint removal methods for aerospace components mainly fall into two categories: physical and chemical methods. Physical methods primarily include mechanical methods such as sandblasting and grinding; chemical methods mainly involve using chemical reagents to react with and dissolve the paint, thereby removing the paint layer from the surface of the parts. These traditional paint removal methods are labor-intensive, environmentally unfriendly, and can easily damage the base material of the parts. In recent years, emerging paint removal technologies mainly include laser paint removal technology. This technology utilizes the thermal energy and impact of a high-energy laser beam to remove the paint layer from the surface of metallic workpieces, achieving certain application results.

[0003] Publication number CN118002927A, publication date May 10, 2024, discloses a three-dimensional laser paint removal device and method for aircraft skin. The device includes a processing table. Inside the processing table's housing, from top to bottom, are arranged a laser, an industrial control and air-cooling device, and a computer control device. The top surface of the processing table is equipped with a horizontal and vertical electric slide rail assembly, which consists of a horizontal slide rail arranged along the X direction and a vertical slide rail arranged along the Y direction. A workpiece clamping table and a fixture are arranged sequentially on the horizontal and vertical electric slide rail assembly. The workpiece clamping table is covered with a glass protective cover. The air inlet and exhaust outlet of the glass protective cover are respectively connected to an inert gas filling mechanism and an exhaust gas collection mechanism via pipes. The rear end of the processing table is equipped with a vertical slide rail arranged along the Z direction. The front end of the upper part of the vertical slide rail is equipped with a dynamic focusing mechanism. The upper part of the vertical slide rail is also equipped with a display screen for the computer control device.

[0004] Publication number CN118768323A, published on October 15, 2024, discloses a method for cleaning aircraft skin based on a composite laser. The method includes: S1, constructing a composite laser paint removal device that outputs both continuous and pulsed lasers; S2, conducting a small-scale circular area cleaning simulation experiment on the aircraft skin using the composite laser paint removal device to determine the optimal paint removal parameters; S3, based on the optimal paint removal parameters, fitting a model relating the power density of the continuous laser to the cleaning depth; and S4, performing aircraft skin cleaning according to the model. Plasma technology is currently mainly used in the field of surface contaminant cleaning, and has no engineering application in the field of paint removal. Summary of the Invention

[0005] This invention replaces traditional paint removal methods with plasma jet paint removal technology, solving the problems of high labor intensity and high environmental pollution risk of traditional technologies; at the same time, based on low-temperature plasma technology, damage to the substrate material of parts can be avoided or reduced.

[0006] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: A low-temperature plasma jet paint removal method includes the following steps: Step 1: Select the type and specifications of the plasma jet generator based on the material, shape, size, and application scenario of the component substrate; Step 2: Select appropriate process gases based on the main components of the paint layer; Step 3: Select the plasma jet paint removal process parameters based on the thickness and adhesion of the paint layer and the paint removal requirements; Step 4: Use a handheld or robotic arm gripper to repeatedly scan the surface of the part to remove the paint layer.

[0007] Preferably, in step one, the thermal sensitivity of the component substrate material is taken into account: metal materials have high resistance, and a high-power continuous power supply is used in conjunction with atmospheric pressure plasma jet; composite materials have relatively low processing temperature requirements, and a pulse power supply or high-frequency AC source dielectric barrier discharge generator is used to reduce heat input through a low duty cycle; the temperature is controlled by adjusting the gas flow rate and power density.

[0008] Preferably, the gas flow rate is 2-30 L / min; the power density is 0.5-5 W / cm³. 2 .

[0009] Preferably, in step one, the structural dimensions and geometry are adapted as follows: for large planar parts, the generator is selected as a multi-nozzle array or a large-area atmospheric pressure plasma jet to increase the coverage area, and the power supply is configured as a multi-channel independent control power supply with a single channel power ≤500W, and the matching frequency is used to maintain stable discharge; for complex curved surfaces / microstructures, the generator is selected as a small-size plasma jet, and the power supply is configured as a high-frequency pulse or microwave power supply.

[0010] Preferably, in step one, the scenario requirements are as follows: For industrial production lines, a continuous wave power supply is selected, coupled with a high-speed scanning atmospheric pressure plasma jet, with a processing speed ≥10m / min; the power supply has overload protection and an automatic matching network to adapt to continuous operation; for precision cleaning of aerospace components, a closed-loop control power supply is adopted, combined with optical detection to adjust plasma parameters in real time; for outdoor equipment mobile scenarios, a portable miniaturized plasma generator is used, equipped with a lithium battery power supply, and the generator and power supply meet the IP54 protection level and are equipped with an explosion-proof housing.

[0011] Preferably, in step two, based on the fact that the paint includes organic film-forming substances, fillers and additives, one of Ar and N2, O2 and CF4 are used as process gases for plasma generation.

[0012] Preferably, O2 and CF4 are used as auxiliary gases, which mainly react with the organic film-forming substances and fillers of the paint to remove them; N2 or Ar mainly serves as a carrier medium and generates physical impact to remove the fillers.

[0013] Preferably, the ratio of O2:CF4:Ar or N2 is 10%-30%:10%-30%:0%-10%:60%-90%.

[0014] Preferably, in step three, the paint removal process parameters are verified by adjusting the power, gas flow rate, and path scanning parameters to obtain more reasonable paint removal process parameters.

[0015] Preferably, the selection of process parameters mainly considers the following factors: Power selection: Considering the thickness and type of paint layer, for thick paint layers or high-adhesion paint layers, relatively high power is required to enhance plasma energy density, promote the decomposition of organic components by active particles, and remove inorganic fillers through physical bombardment; for thin paint layers or heat-sensitive substrates, lower power is used to reduce heat input and avoid substrate oxidation or damage; for composite coating structures, if the paint layer contains multiple layers, the power needs to be adjusted in stages, with high power to quickly remove the topcoat, and then reducing the power to treat the primer to prevent substrate damage; Gas flow rate: For the main gas flow, the flow rate range is 2-30L / min; Scanning parameters: The distance from the nozzle to the surface of the part mainly depends on the generator power. The higher the power, the higher the heat input and output. To avoid overheating damage to the part, the distance should be appropriately increased; The scanning speed of high-density paint should be appropriately reduced to extend the operation time and ensure sufficient reaction; High speed is selected for thin paint layers or continuous production lines to improve efficiency.

[0016] Preferably, in step four, the plasma generator nozzle is held by hand or by a robotic arm, and the nozzle is perpendicular to the surface of the part or at a certain angle to the surface of the part. The scanning motion is performed using parallel lines or spiral paths, and the spacing is based on the jet size to ensure uniform jet coverage. High-adhesion paint layers need to be processed multiple times, with a certain cooling time between each processing to prevent heat accumulation; or the repeated areas can be controlled by programming, and only key areas can be locally processed.

[0017] The beneficial effects of this invention are: I. This invention provides a low-temperature plasma jet paint removal method, which effectively removes conventional aerospace paint from the surfaces of metal substrate parts and composite substrate parts, achieving a maximum paint removal efficiency of 1m for thin paint layers (thickness ≤ 0.3mm). 2 Approximately / h; at the same time, the plasma jet temperature and process parameters are controlled to effectively avoid damage to the substrate.

[0018] II. The low-temperature plasma jet paint removal method provided by this invention achieves different paint removal effects by adjusting the proportion of process gas. Under conditions where the paint removal efficiency requirement is not high, air can be directly used to replace the special process gas, which can reduce the configuration requirements of gas cylinders, simplify the paint removal device, and reduce the paint removal cost. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0021] Example 1 like Figure 1 As shown, a low-temperature plasma jet paint removal method includes the following steps: Step 1: Select the type and specifications of the plasma jet generator based on the material, shape, size, and application scenario of the component substrate; Step 2: Select appropriate process gases based on the main components of the paint layer; Step 3: Select the plasma jet paint removal process parameters based on the thickness and adhesion of the paint layer and the paint removal requirements; Step 4: Use a handheld or robotic arm gripper to repeatedly scan the surface of the part to remove the paint layer.

[0022] Example 2 like Figure 1 As shown, a low-temperature plasma jet paint removal method includes the following steps: Step 1: Select the type and specifications of the plasma jet generator based on the material, shape, size, and application scenario of the component substrate; Step 2: Select appropriate process gases based on the main components of the paint layer; Step 3: Select the plasma jet paint removal process parameters based on the thickness and adhesion of the paint layer and the paint removal requirements; Step 4: Use a handheld or robotic arm gripper to repeatedly scan the surface of the part to remove the paint layer.

[0023] In step one, the thermal sensitivity of the component substrate material is taken into consideration: metal materials have high resistance, and a high-power continuous power supply is used in conjunction with atmospheric pressure plasma jet; composite materials have relatively low processing temperature requirements, and a pulse power supply or high-frequency AC source dielectric barrier discharge generator is used to reduce heat input through a low duty cycle; the temperature is controlled by adjusting the gas flow rate and power density.

[0024] The gas flow rate is 2-30 L / min; the power density is 0.5-5 W / cm³. 2 .

[0025] In step one, the structural dimensions and geometry are adapted as follows: for large planar parts, a multi-nozzle array or a large-area atmospheric pressure plasma jet is selected as the generator to increase the coverage area, and a multi-channel independently controlled power supply is configured with a single-channel power of ≤500W and a matching frequency to maintain stable discharge; for complex curved surfaces / microstructures, a small-size plasma jet is selected as the generator, and a high-frequency pulse or microwave power supply is configured.

[0026] In step one, the scenario requirements are as follows: For industrial production lines, a continuous wave power supply is selected, combined with a high-speed scanning atmospheric pressure plasma jet, with a processing speed ≥10m / min; the power supply has overload protection and an automatic matching network to adapt to continuous operation; for precision cleaning of aerospace components, a closed-loop control power supply is adopted, combined with optical detection to adjust plasma parameters in real time; for outdoor equipment mobile scenarios, a portable miniaturized plasma generator is used, equipped with a lithium battery power supply, and the generator and power supply meet the IP54 protection level and are equipped with an explosion-proof shell.

[0027] In step two, based on the fact that the paint includes organic film-forming substances, fillers and additives, one of Ar and N2, O2 and CF4 are used as process gases for plasma generation.

[0028] Among them, O2 and CF4 are used as auxiliary gases, and their main functions are to react with and remove the organic film-forming substances and fillers in the paint, respectively; N2 or Ar mainly serve as carrier media and generate physical impact to remove the fillers.

[0029] Among them, O2:CF4:Ar or N2 = 10%-30%: 0%-10%: 60%-90%.

[0030] In step three, the paint removal process is verified by adjusting the power, gas flow rate, and path scanning parameters to obtain more reasonable paint removal process parameters.

[0031] The selection of process parameters mainly considers the following factors: Power selection: Considering the thickness and type of paint layer, for thick paint layers or high-adhesion paint layers, relatively high power is required to enhance plasma energy density, promote the decomposition of organic components by active particles, and remove inorganic fillers through physical bombardment; for thin paint layers or heat-sensitive substrates, lower power is used to reduce heat input and avoid substrate oxidation or damage; for composite coating structures, if the paint layer contains multiple layers, the power needs to be adjusted in stages, with high power to quickly remove the topcoat, and then reducing the power to treat the primer to prevent substrate damage; Gas flow rate: For the main gas flow, the flow rate range is 2-30L / min; Scanning parameters: The distance from the nozzle to the surface of the part mainly depends on the generator power. The higher the power, the higher the heat input and output. To avoid overheating damage to the part, the distance should be appropriately increased; for high-density paint, the scanning speed should be appropriately reduced to extend the operation time and ensure sufficient reaction; for thin paint layers or continuous production lines, high speed is selected to improve efficiency.

[0032] In step four, the plasma generator nozzle is held by hand or by a robotic arm, and the nozzle is perpendicular to the surface of the part or at a certain angle to the surface of the part. The scanning motion is performed using parallel lines or spiral paths. The spacing is based on the jet size to ensure uniform jet coverage. High-adhesion paint layers need to be processed multiple times, with a certain cooling time interval between each processing to prevent heat accumulation. Alternatively, the repeated areas can be controlled by programming, and only key areas can be locally processed.

[0033] Example 3 A low-temperature plasma jet paint removal method includes the following steps: Step 1: Select the plasma generator and power supply type according to the substrate material, shape and size of the components and the needs of the scenario, as shown in Table 1. Consider the following factors when selecting: (1) Consider the thermal sensitivity of the substrate material: Metal materials (such as steel and aluminum alloys) have higher resistance, so a high-power continuous power supply (such as radio frequency or microwave power supply) can be selected in conjunction with atmospheric pressure plasma jet (APPJ) to improve the processing efficiency; Composite materials have relatively low processing temperature requirements, generally not exceeding 130℃, so a pulse power supply or high-frequency AC source dielectric barrier discharge (DBD) generator can be used to reduce heat input by using a low duty cycle (10%-30%). Adjust the gas flow rate (2-30L / min) and power density (0.5-5W / cm³) to further reduce the heat input. 2(2) Structural size and geometric adaptation: For large-size planar parts, the generator is selected with a multi-nozzle array or a large-area APPJ to increase the coverage. The power supply is configured with a multi-channel independent control power supply with a single channel power of ≤500W and a matching frequency to maintain stable discharge. For complex curved surfaces / microstructures, the generator is selected with a small-size plasma jet (large length-to-diameter ratio). The power supply is configured with a high-frequency pulse or microwave power supply. The generator is portable and easy to integrate. (3) Scenario requirements: For industrial production lines, a continuous wave power supply (power 1-5kW) is selected, combined with a high-speed scanning APPJ, with a processing speed ≥10m / min. The power supply must have overload protection and an automatic matching network (AMN) to adapt to continuous operation. For precision cleaning of aerospace parts, a closed-loop control power supply (small feedback response time) is adopted, combined with optical detection to adjust plasma parameters in real time. For outdoor equipment mobile scenarios, a portable miniaturized plasma generator is selected, equipped with a lithium battery power supply (≤300W). The generator and power supply meet the IP54 protection level and use an explosion-proof shell.

[0034] Table 1. Generator Type Selection

[0035] Step 2: Based on the characteristic that paint contains a large amount of organic film-forming substances and inorganic substances such as fillers and additives, gases such as O2, CF4, Ar, or N2 are used as the process gases for plasma generation. Among them, O2... 2、 CF4, as an auxiliary gas, primarily reacts with and removes organic film-forming substances and fillers (such as metal oxides) in the paint. N2 or Ar gas mainly serves as a carrier medium and can generate physical impact to remove inorganic substances such as fillers. The basic ratio of various gases is O2:CF4:Ar or N2 = 10%:10%:80%, with adjustments made according to the generator type. For auxiliary gases (such as O2, CF4, Ar, and N2), further adjustments are made. 2、 CF4: Adding 10%-30% O2 can enhance the oxidative decomposition of organic paint layers; CF4 is used to etch inorganic fillers (such as metal oxides), but the proportion needs to be controlled; for metal substrates, inert gas (argon) is preferred to reduce oxidation; for non-conductive substrates, air plasma is preferred to balance cost and active particle generation.

[0036] Step 3: By adjusting the power, gas flow rate, path scanning parameters, etc., the paint removal verification is carried out to obtain a more reasonable paint removal process parameter, as shown in Table 2. The selection of process parameters mainly considers the following factors: (1) Power selection: Considering the thickness and type of paint layer, for thick paint layers (>200μm) or high adhesion paint layers, relatively high power (800W) is required to enhance plasma energy density, promote the decomposition of organic components by active particles (such as oxygen free radicals), and remove inorganic fillers by physical bombardment; for thin paint layers (<100μm) or heat-sensitive substrates, lower power (200-500W) is used to reduce heat input and avoid substrate oxidation or damage; for composite coating structures, if the paint layer contains multiple layers (such as primer + topcoat), the power needs to be adjusted in stages. After the topcoat is removed quickly with high power, the power is reduced to treat the primer to prevent substrate damage. (2) Gas flow rate: For the main gas flow (such as argon, air), the flow rate range is 2-30L / min. Too low a flow rate will cause the jet to be unstable, while too high a flow rate will cool the plasma and reduce the concentration of active particles. (3) Scanning parameters: The distance from the nozzle to the surface of the part mainly depends on the power of the generator. The higher the power, the higher the heat input and output. In order to avoid overheating damage to the part, the distance should be increased appropriately. The scanning speed of high-density paint should be reduced appropriately (0.3-1m / min) and the operation time should be extended to ensure sufficient reaction. For thin paint layers or continuous production lines, high speed (1-2m / min) should be selected to improve efficiency.

[0037] Table 2. Jet plasma paint removal process parameters

[0038] Step 4: Using a handheld or robotic arm clamping method, the plasma generator nozzle is perpendicular to the surface of the part or at a certain angle to the surface of the part, and a scanning motion is performed. The scanning path uses parallel lines or spiral paths, and the spacing is based on the jet size to ensure uniform jet coverage (coverage rate > 90%). High-adhesion paint layers need to be treated multiple times (2-3 times), with a certain cooling time between each time to prevent heat accumulation; or the repeated area can be controlled by programming, and only key areas can be locally treated.

[0039] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A low-temperature plasma jet paint removal method, characterized in that, Includes the following steps: Step 1: Select the type and specifications of the plasma jet generator based on the material, shape, size, and application scenario of the component substrate; Step 2: Select appropriate process gases based on the main components of the paint layer; Step 3: Select the plasma jet paint removal process parameters based on the thickness and adhesion of the paint layer and the paint removal requirements; Step 4: Use a handheld or robotic arm gripper to repeatedly scan the surface of the part to remove the paint layer.

2. The low-temperature plasma jet paint removal method according to claim 1, characterized in that: In step one, the thermal sensitivity of the component substrate material is taken into account: Metallic materials have high toughness, so a high-power continuous power supply is used in conjunction with atmospheric pressure plasma jets; composite materials have relatively lower processing temperature requirements, so a pulse power supply or a high-frequency AC source dielectric barrier discharge generator is used to reduce heat input through a low duty cycle; and the temperature is controlled by adjusting the gas flow rate and power density.

3. The low-temperature plasma jet paint removal method according to claim 2, characterized in that: Gas flow rate: 2-30 L / min; Power density: 0.5-5 W / cm³ 2 .

4. The low-temperature plasma jet paint removal method according to claim 3, characterized in that: In step one, structural dimensions and geometric adaptation are as follows: For large planar parts, a multi-nozzle array or a large-area atmospheric pressure plasma jet is selected as the generator to increase the coverage area, and a multi-channel independently controlled power supply is configured with a single-channel power of ≤500W and a matching frequency to maintain stable discharge; for complex curved surfaces / microstructures, a small-size plasma jet is selected as the generator, and a high-frequency pulse or microwave power supply is configured.

5. The low-temperature plasma jet paint removal method according to claim 4, characterized in that: In step one, the scenario requirements are as follows: For industrial production lines, a continuous wave power supply is selected, combined with a high-speed scanning atmospheric pressure plasma jet, with a processing speed ≥10m / min; the power supply has overload protection and an automatic matching network to adapt to continuous operation; for precision cleaning of aerospace components, a closed-loop control power supply is adopted, combined with optical detection to adjust plasma parameters in real time; for outdoor equipment mobile scenarios, a portable miniaturized plasma generator is used, equipped with a lithium battery power supply, and the generator and power supply meet the IP54 protection level and are equipped with an explosion-proof housing.

6. The low-temperature plasma jet paint removal method according to claim 5, characterized in that: In step two, based on the fact that the paint includes organic film-forming substances, fillers and additives, one of Ar and N2, O2 and CF4 are used as process gases for plasma generation.

7. The low-temperature plasma jet paint removal method according to claim 6, characterized in that: O2 and CF4 serve as auxiliary gases, primarily reacting with and removing the organic film-forming substances and fillers in the paint, respectively; N2 or Ar mainly act as a carrier medium, generating physical impact to remove the fillers.

8. The low-temperature plasma jet paint removal method according to claim 7, characterized in that: O2:CF4:Ar or N2 = 10%-30%: 0%-10%: 60%-90%.

9. The low-temperature plasma jet paint removal method according to claim 8, characterized in that: In step three, the paint removal process is verified by adjusting the power, gas flow rate, and path scanning parameters to obtain more reasonable paint removal process parameters.

10. The low-temperature plasma jet paint removal method according to claim 9, characterized in that: The selection of process parameters mainly considers the following factors: Power selection: Considering the thickness and type of paint layer, for thick paint layers or high-adhesion paint layers, relatively high power is required to enhance plasma energy density, promote the decomposition of organic components by active particles, and remove inorganic fillers through physical bombardment; for thin paint layers or heat-sensitive substrates, lower power is used to reduce heat input and avoid substrate oxidation or damage; for composite coating structures, if the paint layer contains multiple layers, the power needs to be adjusted in stages, with high power to quickly remove the topcoat, and then the power is reduced to treat the primer to prevent damage to the substrate; Gas flow rate: For the main airflow, the flow rate range is 2-30L / min; Scanning parameters: The distance from the nozzle to the surface of the part mainly depends on the generator power. The higher the power, the higher the heat input and output. To avoid overheating damage to the part, the distance should be increased appropriately; The scanning speed of high-density paint should be reduced appropriately, and the operation time should be extended to ensure full reflection; For thin paint layers or continuous production lines, high speed should be selected to improve efficiency.

11. The low-temperature plasma jet paint removal method according to claim 10, characterized in that: In step four, the plasma generator nozzle is held by hand or by a robotic arm, and the nozzle is perpendicular to the surface of the part or at a certain angle to the surface of the part. The scanning motion is performed using parallel lines or spiral paths. The spacing is based on the jet size to ensure uniform jet coverage. High-adhesion paint layers need to be treated multiple times, with a certain cooling time between each treatment to prevent heat accumulation. Alternatively, the repeated areas can be controlled by programming, and only key areas can be treated locally.

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