Ultra-high-speed laser surface finishing method for complex surfaces assisted by vibrating rotating multiphase jet in a wide temperature range

Abstract

The present invention is a method for surface finishing and strengthening of complex surfaces by ultra-high-speed laser assisted by a vibrating and rotating multiphase jet in a wide temperature range. The method aims to solve the problems of corrosion rust and corrosion damage faced by landing gear journals when serving in complex and changeable environments such as high speed, high temperature and high salt fog, as well as the problem of complex curved surfaces. The finishing and strengthening method is as follows: 1. Jet cleaning is performed by impacting the journal-type workpiece with an abrasive gas jet; 2. The workpiece is fixed on an ultra-high-speed laser workbench; 3. A 3D curved surface model of the journal is constructed; 4. Laser finishing treatment is performed; 5. The laser finishing treatment in step 4 is repeated multiple times; 6. Laser nitriding treatment is performed multiple times in a nitrogen atmosphere; 7. Cleaning liquid is sprayed out from a nozzle to impact the journal; 8. Ultrasonic cleaning and drying are performed. The present invention uses a new ultra-high-speed laser surface finishing and strengthening process assisted by a vibrating and rotating multiphase jet in a wide temperature range to refine the surface structure of the journal, inhibit crack growth, and extend the service life of the journal component.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal surface treatment, and in particular relates to a vibrating rotating multiphase jet-assisted ultra-high-speed laser surface finishing and strengthening process within a wide temperature range. Background Art

[0002] With the rapid advancement of aerospace technology, cost reduction has become a major challenge for aerospace components, and component reuse is a key measure to reduce costs. Many precision components, such as landing gear journals and engine blades, are expensive to manufacture, require long production cycles, and are difficult to forge. Their failure can result in significant losses in manpower and resources. The landing gear system, a critical system for horizontal recovery of spacecraft, is the prerequisite and foundation for ensuring the vehicle's reusability. During retraction and extension, the entire landing gear rotates around the journal. The high loads and friction exerted by the journal often cause scratches and wear on the journal's working surface. Damaged material can accumulate in gaps, exacerbating the damage. In humid and acidic operating environments, corrosion is more likely to occur, leading to landing gear journal failure, resulting in aircraft damage and even flight accidents. Traditional cleaning processes only achieve a smooth surface finish on the journal, but corroded journals suffer from low strength and reduced serviceability, making them unsuitable for return to service. Therefore, it is urgent to develop a new type of polishing process to polish and repair the strengthened landing gear journal, so as to achieve the environmental protection measures based on the reuse of the landing gear journal and the subsequent surface coating of protective coating.

[0003] Ultra-high-speed laser finishing refers to a process that uses laser irradiation to clean the surface, removing contaminants from the substrate through processes such as thermal vibration and ablation. Compared to traditional finishing processes, laser finishing is contactless. It can achieve comprehensive, damage-free cleaning of precision workpieces and delicate areas, such as difficult-to-machine areas on landing gear journals. It also offers advantages such as high efficiency, environmental friendliness, and energy savings. During ultra-high-speed laser finishing, high-energy beam irradiation removes rust from the surface and repairs corrosion damage such as pores, furrows, and cracks. Significant temperature gradients and compositional supercooling enhance the corrosion and wear resistance of landing gear journals. Ultra-high-speed laser finishing methods vary in different temperature fields. At low laser flux, the absorbed laser energy heats the material, causing it to evaporate or sublimate. At high laser flux, the material typically transforms into a plasma. Ultra-high-speed laser finishing can be applied to different materials and contaminants across a wide temperature range, providing a wide range of applications.

[0004] A multiphase jet is a fluid system in which two or more different phases or compositions coexist with a distinct interface. This system utilizes an abrasive gas jet to introduce a liquid phase into the abrasive gas jet, impacting the rust layer on the landing gear journal, removing it from the surface. The multiphase jet process is coupled with vibration and rotation to release residual impact stress and enhance finishing performance. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of corrosion rust and corrosion damage faced by landing gear journals when serving in complex and changeable environments such as high speed, high temperature and high salt spray, as well as the complex curved surfaces of the smooth surface, and to provide a method for ultra-high-speed laser surface finishing and strengthening assisted by a vibrating rotating multiphase jet in a wide temperature range.

[0006] The present invention is applicable to the ultra-high-speed laser surface finishing and strengthening method for complex curved surfaces in a wide temperature range assisted by a vibrating rotating multiphase jet, and is implemented by the following steps:

[0007] 1. Fix the journal workpiece on a vibrating rotary table, then mix abrasive, water and activator to obtain liquid slurry. The vibrating rotary table drives the journal to vibrate and rotate. A multi-phase jet device is used to spray the liquid slurry through the nozzle to form an abrasive gas jet to impact the journal workpiece, obtaining a jet-cleaned journal.

[0008] 2. Fix the journal after jet cleaning on the ultra-high-speed laser workbench and adjust the distance between the laser gun head and the journal;

[0009] 3. Construct a 3D surface model of the journal according to the size of the journal. Import the 3D surface model of the journal into the laser robot system to generate a 3D surface laser path, so that the laser gun head is perpendicular to the section of the journal surface.

[0010] 4. Laser finishing: Under a protective gas atmosphere, first control the laser power to 80-90W, the laser repetition frequency to 90kHz, and the laser scanning speed to 7000-9000mm / s to perform high-power and high-speed scanning laser finishing on the journal. Then control the laser power to 50-53W, the laser repetition frequency to 80kHz, and the laser scanning speed to 4000-6000mm / s to perform low-power and low-speed scanning laser finishing. After air cooling (rapid cooling and recrystallization), the journal after laser finishing is obtained.

[0011] 5. Repeat the laser polishing process in step 4 several times;

[0012] 6. Under a nitrogen atmosphere, the laser power is controlled to be 80-90W, the laser repetition frequency is 90kHz, and the laser scanning speed is 7000-9000mm / s to perform laser nitriding treatment on the journal multiple times to obtain a nitrided journal;

[0013] 7. Fix the nitrided journal on a vibrating rotary table, which drives the journal to vibrate and rotate. A multiphase jet device is used to spray cleaning liquid through a nozzle to impact the journal, thereby obtaining a journal with a ceramic layer-passivation layer gradient protective layer.

[0014] 8. Ultrasonic cleaning is performed on the journal with the ceramic layer-passivation layer gradient protective layer, and the journal after enhanced cleaning is obtained after drying, thereby completing the ultra-high-speed laser surface finishing enhancement method assisted by the vibration rotating multiphase jet in a wide temperature range.

[0015] Compared with existing technologies, the present invention's vibrating rotating multiphase jet-assisted ultra-high-speed laser surface finishing and strengthening method has the following beneficial effects:

[0016] After finishing and strengthening, the present invention removes the corroded rust layer on the journal, achieving a significant finishing effect. The composite finishing process, primarily based on ultrahigh-speed laser finishing, is environmentally friendly and has a wide range of applicability. The novel ultrahigh-speed laser surface finishing and strengthening process, assisted by a vibrating, rotating multiphase jet within a wide temperature range, refines the journal surface structure, inhibits crack growth, and extends the service life of the journal component. It also improves the journal's mechanical properties, including fatigue resistance and wear resistance. A gradient protective layer structure, combining a ceramic layer and a passivation layer, is achieved on the journal surface, significantly enhancing the journal's corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A diagram of a 3D curved surface model of a journal constructed in the embodiment;

[0018] Figure 2 This is a process flow chart of the ultra-high-speed laser surface finishing and strengthening method for complex curved surfaces in a wide temperature range assisted by a vibrating rotating multiphase jet;

[0019] Figure 3 The left picture is before the smooth and clean strengthening treatment, and the right picture is after the smooth and clean strengthening treatment. DETAILED DESCRIPTION

[0020] Specific embodiment 1: This embodiment is applicable to the ultra-high-speed laser surface finishing and strengthening method assisted by a vibrating rotating multiphase jet in a wide temperature range on complex curved surfaces, and is implemented in the following steps:

[0021] 1. Fix the journal workpiece on a vibrating rotary table, then mix abrasive, water and activator to obtain liquid slurry. The vibrating rotary table drives the journal to vibrate and rotate. A multi-phase jet device is used to spray the liquid slurry through the nozzle to form an abrasive gas jet to impact the journal workpiece, obtaining a jet-cleaned journal.

[0022] 2. Fix the journal after jet cleaning on the ultra-high-speed laser workbench and adjust the distance between the laser gun head and the journal;

[0023] 3. Construct a 3D surface model of the journal according to the size of the journal. Import the 3D surface model of the journal into the laser robot system to generate a 3D surface laser path, so that the laser gun head is perpendicular to the section of the journal surface.

[0024] 4. Laser finishing: Under a protective gas atmosphere, first control the laser power to 80-90W, the laser repetition frequency to 90kHz, and the laser scanning speed to 7000-9000mm / s to perform high-power and high-speed scanning laser finishing on the journal. Then control the laser power to 50-53W, the laser repetition frequency to 80kHz, and the laser scanning speed to 4000-6000mm / s to perform low-power and low-speed scanning laser finishing. After air cooling, the journal after laser finishing is obtained.

[0025] 5. Repeat the laser polishing process in step 4 several times;

[0026] 6. Under a nitrogen atmosphere, the laser power is controlled to be 80-90W, the laser repetition frequency is 90kHz, and the laser scanning speed is 7000-9000mm / s to perform laser nitriding treatment on the journal multiple times to obtain a nitrided journal;

[0027] 7. Fix the nitrided journal on a vibrating rotary table, which drives the journal to vibrate and rotate. A multiphase jet device is used to spray cleaning liquid through a nozzle to impact the journal, thereby obtaining a journal with a ceramic layer-passivation layer gradient protective layer.

[0028] 8. Ultrasonic cleaning is performed on the journal with the ceramic layer-passivation layer gradient protective layer, and the journal after enhanced cleaning is obtained after drying, thereby completing the ultra-high-speed laser surface finishing enhancement method assisted by the vibration rotating multiphase jet in a wide temperature range.

[0029] This embodiment is based on 3D model construction and uses a vibrating rotating multiphase jet assisted ultra-high-speed laser to clean the corroded rust layer of the landing gear journal in a wide temperature range, repair the surface corrosion damage such as pores, furrows, cracks, etc. generated during its service, and enhance the corrosion resistance and wear resistance of the landing gear journal; build a gradient protective layer of ceramic layer-passivation layer on the surface of the landing gear journal, further extending its service life after recycling.

[0030] This embodiment combines ultra-high-speed laser cleaning with multi-phase jet to achieve composite cleaning, thereby reducing costs and improving cleaning efficiency.

[0031] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the mass concentration of the abrasive in the liquid slurry in step 1 is 5% to 8%, and the average particle size of the abrasive is 1.0 μm.

[0032] Specific embodiment three: The difference between this embodiment and specific embodiment one or two is that in step one, the vibrating rotary workbench drives the journal to vibrate and rotate, and the vibration frequency is controlled to be 25-35 Hz and the rotation speed is 500-1500 r / min.

[0033] Specific embodiment 4: The difference between this embodiment and any one of specific embodiments 1 to 3 is that in step 1, the injection pressure of the abrasive gas jet is controlled to be 2-2.5 MPa.

[0034] Specific embodiment 5: This embodiment differs from any one of specific embodiments 1 to 4 in that the protective gas in step 4 is argon.

[0035] Specific embodiment six: The difference between this embodiment and any one of specific embodiments one to five is that in step four, the laser power is first controlled to 80-90W, the laser repetition frequency is 90kHz, and the laser scanning speed is 8000mm / s to perform high-power and high-speed scanning laser polishing treatment on the journal, and then the laser power is controlled to 50-53W, the laser repetition frequency is 80kHz, and the laser scanning speed is 5000mm / s to perform low-power and low-speed scanning laser polishing treatment.

[0036] Specific embodiment 7: The difference between this embodiment and specific embodiments 1 to 6 is that the laser polishing process is repeated 2 to 3 times in step 5.

[0037] Specific embodiment eight: The difference between this embodiment and any one of specific embodiments one to seven is that in step six, the laser power is controlled to be 80-90W, the laser repetition frequency is 90kHz, and the laser scanning speed is 8000mm / s under nitrogen atmosphere to perform laser nitriding treatment on the journal.

[0038] Specific embodiment 9: The difference between this embodiment and specific embodiment 8 is that in step 6, the laser nitriding treatment is performed 1 to 3 times.

[0039] Specific embodiment 10: The difference between this embodiment and any one of specific embodiments 1 to 9 is that in step 7, the spray pressure of the spray cleaning liquid is controlled to be 2-2.5 MPa.

[0040] Example: This example is applicable to a method for ultra-high-speed laser surface finishing and strengthening of complex curved surfaces in a wide temperature range assisted by a vibrating rotating multiphase jet, and is implemented in the following steps:

[0041] 1. Fix the journal on a vibrating rotary table, then mix the abrasive, water and activator (sodium dodecylbenzene sulfonate) to obtain a liquid slurry. The mass concentration of the abrasive in the liquid slurry is 6%, and the average particle size of the abrasive is 1.0 μm (i.e., the abrasive particle size is 10,000 mesh). The vibrating rotary table drives the journal to vibrate and rotate, and the vibration frequency is controlled to be 30 Hz and the rotation speed is 1000 r / min. A multiphase jet device is used to use a high-pressure gas jet to carry the liquid slurry to impact the journal. The jet pressure is controlled to be 2 MPa, the target distance is 10 mm, and the impact angle is 45° to obtain the journal after jet cleaning.

[0042] 2. Fix the journal after jet cleaning on the ultra-high-speed laser workbench, move the laser gun head a short distance to the outer end of the journal, ensure that the laser power is stable when the laser scans the journal workpiece, and adjust the distance from the laser gun head to the journal to 8 cm to ensure the uniformity of the ultra-high-speed laser beam;

[0043] 3. Construct a 3D surface model of the journal according to the size of the journal. Import the 3D surface model of the journal into the laser robot system to generate a 3D surface laser path, so that the laser gun head is perpendicular to the section of the journal surface.

[0044] 4. Laser polishing: In an argon atmosphere, first control the laser power to 90W, the laser repetition frequency to 90kHz, and the laser scanning speed to 8000mm / s to perform high-power and high-speed scanning laser polishing on the journal. The high heat concentration of the heat source is used to quickly heat the contamination layer and the corrosion layer, resulting in a chemical reaction, so that the contamination layer, impurity particles and corrosion layer are separated from the journal surface.

[0045] Then, the laser power is controlled to 50W, the laser repetition frequency is 80kHz, and the laser scanning speed is 5000mm / s to perform low-power and low-speed scanning laser finishing treatment to release residual stress and reduce the surface roughness of the journal. The air cooling treatment utilizes rapid cooling (cooling) recrystallization to improve the hardness, wear resistance, and corrosion resistance of the journal, thereby obtaining a journal after laser finishing treatment;

[0046] 5. Repeat the laser finishing process in step 4 twice, and the corrosion damage on the journal surface is basically smooth and complete;

[0047] 6. Under nitrogen atmosphere, laser power was controlled at 90W, laser repetition frequency at 90kHz, and laser scanning speed at 8000mm / s to perform laser nitriding treatment on the journal twice, generating a ceramic layer in situ to achieve the effect of refining the grains, improving the mechanical properties and corrosion resistance of the journal, and obtaining the nitrided journal;

[0048] 7. Fix the nitrided journal on a vibrating rotary table, which drives the journal to vibrate and rotate. Then, a corrosion inhibitor (phenolic resin), a passivator (citric acid) and water are mixed to obtain a cleaning liquid. A multiphase jet device is used to use a high-pressure gas jet to carry the cleaning liquid to impact the journal, thereby removing residual stress and forming a passivation film on the journal surface, thereby obtaining a journal with a ceramic layer-passivation layer gradient protective layer.

[0049] 8. Ultrasonic cleaning is performed on the journal with the ceramic layer-passivation layer gradient protective layer, and the journal after enhanced cleaning is obtained after drying, thereby completing the ultra-high-speed laser surface finishing enhancement method assisted by the vibration rotating multiphase jet in a wide temperature range.

[0050] According to the corrosion situation, the finish grade is divided into A, B, C and D. The standards are as follows:

[0051] Finish grade standards

[0052] Finish grade describe A-level Smooth surface with almost no corrosion rust layer Class B The surface is basically smooth, but there are a few rust spots C-level There is a more obvious rust layer on the surface, but the distribution is less D-Class The surface is relatively rough and covered with a large amount of corrosive rust

[0053] The smoothness rating of the journal obtained in this embodiment is A. Figure 3 It can be seen from the electron microscope image that after the polishing and strengthening treatment of this embodiment, the surface structure of the journal workpiece is refined and there is no rust spot on the workpiece surface.

[0054] The present invention provides a surface finishing process for the complex curved surface of the landing gear journal, a new composite surface finishing and strengthening process that uses a vibrating rotating multiphase jet in a wide temperature range to assist ultra-high-speed laser finishing. The finishing effect is obvious and the process is environmentally friendly and pollution-free. It not only solves the problems brought by traditional processes and realizes the gradient protection of the ceramic layer-passivation layer, but also further improves the original corrosion resistance and wear resistance of the component, extends its service life, and realizes comprehensive finishing and reuse environmentally friendly measures.

Claims

1. A method for ultra-high-speed laser surface finishing and strengthening assisted by a vibrating rotating multiphase jet in a wide temperature range suitable for complex curved surfaces, characterized by The vibrating rotating multiphase jet-assisted ultra-high-speed laser surface finishing method is implemented by the following steps:

1. Fix the journal workpiece on a vibrating rotary table, then mix abrasive, water and activator to obtain liquid slurry. The vibrating rotary table drives the journal to vibrate and rotate. A multi-phase jet device is used to spray the liquid slurry through the nozzle to form an abrasive gas jet to impact the journal workpiece, obtaining a jet-cleaned journal.

2. Fix the journal after jet cleaning on the ultra-high-speed laser workbench and adjust the distance between the laser gun head and the journal; 3. Construct a 3D surface model of the journal according to the size of the journal. Import the 3D surface model of the journal into the laser robot system to generate a 3D surface laser path, so that the laser gun head is perpendicular to the section of the journal surface.

4. Laser finishing: Under a protective gas atmosphere, first control the laser power to 80-90W, the laser repetition frequency to 90kHz, and the laser scanning speed to 7000-9000mm / s to perform high-power and high-speed scanning laser finishing on the journal. Then control the laser power to 50-53W, the laser repetition frequency to 80kHz, and the laser scanning speed to 4000-6000mm / s to perform low-power and low-speed scanning laser finishing. After air cooling, the journal after laser finishing is obtained.

5. Repeat the laser polishing process in step 4 several times; 6. Under a nitrogen atmosphere, the laser power is controlled to be 80-90W, the laser repetition frequency is 90kHz, and the laser scanning speed is 7000-9000mm / s to perform laser nitriding treatment on the journal multiple times to obtain a nitrided journal; 7. Fix the nitrided journal on a vibrating rotary table, which drives the journal to vibrate and rotate. A multiphase jet device is used to spray cleaning liquid through a nozzle to impact the journal, thereby obtaining a journal with a ceramic layer-passivation layer gradient protective layer.

8. Ultrasonic cleaning is performed on the journal with the ceramic layer-passivation layer gradient protective layer, and the journal after enhanced cleaning is obtained after drying, thereby completing the ultra-high-speed laser surface finishing enhancement method assisted by the vibration rotating multiphase jet in a wide temperature range.

2. The method for surface finishing and strengthening of complex curved surfaces by vibrating rotating multiphase jet assisted ultra-high-speed laser in a wide temperature range according to claim 1 is characterized in that The mass concentration of the abrasive in the liquid slurry in step 1 is 5% to 8%, and the average particle size of the abrasive is 1.0 μm.

3. The method for surface finishing and strengthening of complex curved surfaces by vibrating rotating multiphase jet assisted ultra-high-speed laser in a wide temperature range according to claim 1 is characterized in that In step 1, the vibrating rotary worktable drives the journal to vibrate and rotate, and the vibration frequency is controlled to be 25 to 35 Hz and the rotation speed is 500 to 1500 r / min.

4. The method for surface finishing and strengthening of complex curved surfaces by vibrating rotating multiphase jet assisted ultra-high-speed laser in a wide temperature range according to claim 1 is characterized in that In step 1, the injection pressure of the abrasive gas jet is controlled to be 2 to 2.5 MPa.

5. The method for surface finishing and strengthening of complex curved surfaces by vibrating rotating multiphase jet assisted ultra-high-speed laser in a wide temperature range according to claim 1 is characterized in that The protective gas described in step 4 is argon.

6. The method for surface finishing and strengthening of complex curved surfaces by vibrating rotating multiphase jet assisted ultra-high-speed laser in a wide temperature range according to claim 1 is characterized in that In step 4, first control the laser power to 80-90W, the laser repetition frequency to 90kHz, and the laser scanning speed to 8000mm / s to perform high-power and high-speed scanning laser polishing on the journal, and then control the laser power to 50-53W, the laser repetition frequency to 80kHz, and the laser scanning speed to 5000mm / s to perform low-power and low-speed scanning laser polishing.

7. The method for surface finishing and strengthening of complex curved surfaces by vibrating rotating multiphase jet assisted ultra-high-speed laser in a wide temperature range according to claim 1 is characterized in that Repeat the laser polishing process 2 to 3 times in step 5.

8. The method for surface finishing and strengthening of complex curved surfaces by vibrating rotating multiphase jet assisted ultra-high-speed laser in a wide temperature range according to claim 1 is characterized in that In step six, under a nitrogen atmosphere, the laser power is controlled to be 80-90 W, the laser repetition frequency is controlled to be 90 kHz, and the laser scanning speed is controlled to be 8000 mm / s to perform laser nitriding treatment on the journal.

9. The method for surface finishing and strengthening of complex curved surfaces by ultra-high-speed laser assisted by a vibrating rotating multiphase jet in a wide temperature range according to claim 8, characterized in that In step six, laser nitriding treatment is performed 1 to 3 times.

10. The method for surface finishing and strengthening of complex curved surfaces by vibrating rotating multiphase jet assisted ultra-high-speed laser in a wide temperature range according to claim 1, characterized in that In step seven, the spray pressure of the cleaning liquid is controlled to be 2-2.5 MPa.

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