A supersonic laser spraying device and method

Abstract

This invention discloses a supersonic laser spraying device and method, belonging to the field of laser spraying technology. The invention achieves coordinated laser transmission and supersonic powder flow through the cooperation of optical components such as output optical fibers, collimating lens groups, and converging lenses with a Laval nozzle structure. The method includes: multi-parameter closed-loop control, synchronously monitoring parameters such as molten pool temperature and powder flow divergence angle, constructing a process health index to trigger dynamic compensation of laser power, gas flow pressure, and powder feed rate; adaptive focus scanning, adjusting the focus position in real time through a laser displacement sensor, and switching operating modes in conjunction with the process health index; and lens anomaly diagnosis, constructing a health index using dual-wavelength transmittance and wavefront distortion, providing graded early warnings and linking powder feed rate adjustments. This solution can reduce coating defects and improve spraying accuracy and system stability.

Description

Technical Field

[0001] This invention relates to the field of laser spraying technology, specifically to a supersonic laser spraying device and method. Background Technology

[0002] Laser spraying technology, with its advantages of high coating bonding strength and small heat-affected zone, is widely used in surface strengthening and repair in aerospace, machinery manufacturing, and other fields. However, existing supersonic laser spraying processes face multiple technical bottlenecks in practical applications: on the one hand, the coupling of multiple parameters such as molten pool temperature fluctuations, powder flow divergence angle shifts, and element burn-off during the spraying process makes the coating prone to defects such as porosity and cracks; on the other hand, traditional devices lack dynamic control mechanisms, making it difficult to adapt to changes in the substrate surface morphology in real time, causing focal point position shifts and affecting coating uniformity; in addition, under prolonged high-power laser operation, thermal deformation and contamination of the optical lens can lead to beam quality degradation, and existing technologies lack effective real-time diagnostic methods, which can easily cause spraying failures.

[0003] Current mainstream supersonic laser spraying equipment suffers from three major technical shortcomings: First, parameter control relies on manual experience and preset settings, making it impossible to construct a process health assessment system based on real-time sensor data. This results in the melt pool temperature deviating from the ideal range (0.8-0.95 times the melting point), difficulty in maintaining the supersonic state of powder flow (Ma=2.0-2.5), and element burn-off rates often exceeding the 3% process threshold. Second, the lack of a focal point compensation mechanism means that when the substrate surface experiences height changes due to spraying accumulation or processing errors, the laser focus point cannot be dynamically adjusted, leading to a decrease in the accuracy of the intersection between the powder flow and the laser, and coating thickness fluctuations exceeding ±5μm. Third, the lag in optical system maintenance means that lens transmittance attenuation and wavefront distortion lack quantitative monitoring, often resulting in a sharp drop in power density (e.g., below 15kW / cm²) due to lens abnormalities, causing insufficient powder pre-activation and accumulation of unmelted particles. Summary of the Invention

[0004] The purpose of this invention is to solve the existing problems and to propose a supersonic laser spraying device and method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A supersonic laser spraying device, comprising:

[0007] Output fiber, collimating lens barrel, collimating lens group, converging lens, lens barrel, collimating and shaping lens group, conversion connector, air inlet nozzle, optical powder coupling channel, spray gun, end cap, powder inlet nozzle, powder buffer chamber, annular powder inlet channel;

[0008] The laser output head is provided with a collimating lens tube at one end, a lens tube at one end, a conversion connector at one end, a Laval cavity at one end, an end cap at one end, and a photosensitive coupling channel is opened inside the end cap.

[0009] The collimating lens tube is symmetrically provided with a collimating lens group at one end, and a converging lens that cooperates with the collimating lens group at one end of the lens tube. The collimating and shaping lens group is provided at the other end of the lens tube.

[0010] The conversion connector is also provided with an air inlet.

[0011] The end has a powder buffer chamber, a powder inlet nozzle that communicates with the outside, and an annular powder inlet channel that communicates with the photosensitive coupling channel.

[0012] The laser output head, collimating lens barrel, lens barrel, conversion connector, Laval cavity, end cap, and photosensitive coupling channel are interconnected.

[0013] Furthermore, the laser output head has a QBH, LOE, LOC, or Qplus structure;

[0014] The collimating lens tube is used to mount the collimating lens group and the converging lens;

[0015] The collimating lens group consists of 2-4 lenses and is used to collimate the diverging laser output from the laser output head.

[0016] The converging lens is used to convert the collimated laser into a converging beam;

[0017] The lens barrel is the lens barrel of a collimating and shaping lens group;

[0018] The collimating and shaping lens group is used to convert the converging laser into a collimated beam with a diameter of 2mm-10mm, and to collimate the laser into a flat-top beam.

[0019] The conversion connector is used to connect the lens barrel of the lens group to the Laval nozzle body at the rear;

[0020] The air inlet is used to inject high-pressure argon gas;

[0021] The photo-powder coupling channel is formed by connecting the end to the Laval nozzle via a thread and connecting the end to the Laval cavity, thus creating a powder buffer chamber and an annular powder inlet channel. The width of the annular powder inlet channel is 0.5mm-1.5mm, and the annular powder inlet channel is the photo-powder coupling channel for the sprayed powder of the Laval nozzle.

[0022] The Laval cavity is the main body of the Laval nozzle of the spray gun. The inner cavity has a Laval structure, and the diameter of the narrow-diameter component is 2mm-10mm. High-pressure argon gas forms a supersonic gas flow after passing through the narrow-diameter component.

[0023] The end cap is connected to the Laval nozzle via a thread;

[0024] The powder inlet nozzle injects spray powder using a powder feeder;

[0025] The powder buffer chamber is formed after the end is threadedly connected to the Laval nozzle and the end and the Laval chamber are in place.

[0026] The annular powder inlet channel is formed after the end is threadedly connected to the Laval nozzle and the end is connected to the Laval cavity.

[0027] A method for supersonic laser spraying includes the following steps:

[0028] S1. Multi-parameter closed-loop dynamic control: Simultaneously monitor the three-dimensional temperature distribution of the molten pool, the powder flow divergence angle and convergence point offset, and the element burn-off rate parameters to construct a process health index. Based on the control trigger conditions, through parameter optimization driven by digital twin, dynamic adjustment of laser power, coordinated control of airflow pressure, and intelligent compensation of powder feed are achieved to reduce coating defects.

[0029] S2. Adaptive laser focus scanning: Real-time monitoring of the distance change between the spray gun and the substrate surface, calculation of focus compensation displacement, adjustment of the axial position of the lens group by the piezoelectric ceramic actuator to correct the focus position, and linkage with the process health index system to switch different working modes according to coating thickness fluctuations.

[0030] S3. Real-time diagnosis of lens anomalies: By using dual-wavelength transmittance monitoring and thermal deformation wavefront diagnosis, a lens health index is constructed and graded responses are implemented. When a lens anomaly occurs, corresponding measures are taken, such as early warning, power reduction, and emergency shutdown. At the same time, the powder feeding amount will also be adjusted in conjunction with the lens health index.

[0031] Furthermore, the specific operation steps of S1 are as follows:

[0032] 101. Simultaneously monitor the molten pool temperature distribution, powder flow divergence angle and convergence point offset, and element burn-off rate;

[0033] 102. Calculate the Process Health Index (PHI), expressed as: PHI = 0.4 × |Temperature Fluctuation Rate| + 0.3 × Divergence Angle Deviation Rate + 0.3 × Burn-off Rate Deviation Rate; When PHI > 0.25 or element burn-off rate > 2.5%, control is triggered.

[0034] 103. Predicting porosity and bonding strength using a long short-term memory neural network model;

[0035] 104. The optimal laser power, gas flow pressure, and powder feeding rate are determined using an adaptive particle swarm optimization algorithm.

[0036] 15. Dynamic compensation execution:

[0037] The laser power is adjusted based on the difference between the average temperature of the molten pool and the target temperature, as well as the temperature curvature.

[0038] Adjust the airflow pressure according to the powder flow divergence angle and convergence point offset;

[0039] Adjust the powder feeding rate according to the element burn-off rate and porosity change rate.

[0040] Furthermore, the specific operation steps of S2 are as follows:

[0041] In the pre-activation step of the powder focusing within the flat-top laser beam, a dynamic focus compensation mechanism is added, including:

[0042] 201. Real-time surface topology monitoring: A laser displacement sensor is integrated at the end to measure the change in distance ΔH between the spray gun and the substrate surface in real time;

[0043] 202. Calculation of focus offset: Based on the distance change ΔH and the preset distance d of the powder convergence point, calculate the focus compensation displacement: ΔF=k1×ΔH×(d / d0), where k1=0.8 is the empirical compensation coefficient, d is the preset distance of the powder convergence point, which is set between 2mm and 10mm, d0=5mm reference distance, and ΔH is the distance change from the spray gun to the substrate surface;

[0044] 203. Dynamic Focus Adjustment: The axial position of the collimating and shaping lens assembly is adjusted via a piezoelectric ceramic actuator; Focus position correction formula: F new =F0+ΔF, where F0 is the initial focus position, F new Let ΔF be the new focus position after state adjustment, and ΔF be the calculated focus compensation displacement.

[0045] 204. Linkage with PHI system: When the process health index PHI > 0.2, the focus scanning system is activated. When the coating thickness fluctuation is < ±5μm, the system switches to energy-saving mode, i.e., the sampling frequency is reduced to 1kHz.

[0046] Furthermore, the specific operation steps of S3 are as follows:

[0047] 301. Calculate laser transmittance in real time using input power sensors and output power sensors;

[0048] 302. Real-time detection of the wavefront distortion of the laser beam using a wavefront sensor;

[0049] 303. Calculate the Lens Health Index (LHI) based on transmittance and wavefront distortion, and perform a graded response:

[0050] When LHI is in the range of 0.1 to 0.3, an optical system warning is triggered;

[0051] When LHI is in the range of 0.3 to 0.5, reduce the laser power and start compressed air dust removal;

[0052] When LHI is greater than 0.5, perform an emergency stop and locate the faulty lens;

[0053] 304. When LHI is greater than 0.3, the powder feeding amount will be automatically reduced; after the fault is cleared, the powder feeding amount will gradually return to the initial value.

[0054] Compared with the prior art, the beneficial effects of the present invention are:

[0055] (1) This invention fundamentally improves the quality of spray coatings through real-time fusion and dynamic adjustment of multi-dimensional sensor data. By using infrared thermal imagers, high-speed CCDs and other equipment to simultaneously monitor the molten pool temperature, powder flow morphology and element burn-off, the constructed process health index can accurately capture process abnormalities. When temperature fluctuations or burn-off rates exceed the standard, parameters such as laser power and airflow pressure will be automatically optimized.

[0056] (2) In this invention, the integrated laser displacement sensor and piezoelectric ceramic driving system can respond in real time to the minute undulations of the substrate surface, and control the focal position adjustment accuracy within ±0.5μm to ensure that the laser energy is uniformly applied to the powder flow. The lens health monitoring, through dual-wavelength transmittance detection and wavefront distortion analysis, can provide early warning of optical component abnormalities: when the lens performance deteriorates, the system will automatically reduce the powder feed and start dust removal to avoid coating failure caused by beam quality degradation;

[0057] (3) In this invention, the integrated design of the Laval nozzle and the annular narrow slit allows high-pressure argon gas to form a supersonic airflow. After the powder is uniformly dispersed in the powder buffer chamber, it is accelerated through the narrow slit, thus improving the utilization rate. The collimating and shaping lens group converts the laser into a flat-top beam, and with the adaptive focus adjustment, the powder heating efficiency is improved. This device realizes fully automated operation from parameter monitoring to fault response. Attached Figure Description

[0058] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings;

[0059] Figure 1 This is a structural diagram of a supersonic laser spraying device according to the present invention;

[0060] Figure 2 This is a flowchart of a supersonic laser spraying method according to the present invention.

[0061] Labeling explanation: 2-collimating lens barrel, 3-collimating lens group, 4-converging lens, 5-lens barrel, 6-collimating and shaping lens group, 7-conversion connector, 8-air inlet nozzle, 9-light powder coupling channel, 10-spray gun, 11-end, 12-powder inlet nozzle, 13-powder buffer chamber, 14-annular powder inlet channel. Detailed Implementation

[0062] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0063] It should be understood that the terms “comprising” and “including” used in this disclosure and claims indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0064] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this disclosure. As used in this disclosure and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this disclosure and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0065] like Figure 1 As shown, a supersonic laser spraying device includes:

[0066] The output optical fiber has a core diameter of 20um-1000um;

[0067] Laser output head 1 is a QBH structure (it can also be LOE, LOC or Qplus, etc.);

[0068] Collimating lens tube 2, used to mount collimating lens group 3 and converging lens 4;

[0069] Collimating lens group 3 consists of 2-4 lenses, and its function is to collimate the diverging laser output from laser output head 1;

[0070] The converging lens 4 is used to convert the collimated laser into a converging beam 8;

[0071] Lens tube 5 is the lens tube for collimating and shaping lens group 6;

[0072] The collimating and shaping lens group 6 is used to convert the focusing laser into a collimated beam with a smaller diameter of 2mm-10mm, and to collimate the laser into a flat-top beam.

[0073] The adapter 7 is used to connect the lens barrel 5 of the lens group to the rear Laval nozzle body;

[0074] Inlet nozzle 8 is used to inject high-pressure argon gas;

[0075] After the end 11 of the photo-coupling channel 9 is connected to the Laval nozzle by a thread, and the end 11 and the Laval cavity 10 are connected in place, a powder buffer cavity 13 and an annular powder inlet channel 14 are formed. The width of the annular powder inlet channel is 0.5mm-1.5mm. This narrow slit is the photo-coupling channel for the sprayed powder of the Laval nozzle.

[0076] The Laval cavity 10 is the main body of the Laval nozzle of the spray gun. Its inner cavity has a Laval structure, and the diameter of its narrow-diameter component can be 2mm-10mm. High-pressure argon gas forms a supersonic gas flow after passing through the narrow-diameter component.

[0077] End 11 is threadedly connected to the Laval nozzle;

[0078] Powder inlet nozzle 12 allows the powder dispenser to inject coating powder through the powder inlet nozzle;

[0079] The powder buffer chamber 13 is formed after the end 11 is threadedly connected to the Laval nozzle and after the end 11 and the Laval chamber 10 are connected in place.

[0080] The annular powder inlet channel 14 is also formed after the end 11 is connected to the Laval nozzle by a thread and the end 11 and the Laval cavity 10 are connected in place.

[0081] The connection relationship includes: a collimating lens tube 2 is provided at one end of the laser output head 1, a lens tube 5 is provided at one end of the collimating lens tube 2, a conversion connector 7 is provided at one end of the lens tube 5, a Laval cavity 10 is provided at one end of the conversion connector 7, an end cap 11 is provided at one end of the Laval cavity 10, and a photosensitive coupling channel 9 is opened in the end cap 11; a collimating lens group 3 is symmetrically provided in one end of the collimating lens tube 2, a converging lens 4 that cooperates with the collimating lens group 3 is provided at one end of the lens tube 5, and a collimating and shaping lens group 6 is provided in the other end of the lens tube 5; an air inlet 8 is also provided on the conversion connector 7; a powder buffer cavity 13 is opened in the end cap 11, a powder inlet 12 that communicates with the outside is opened on the powder buffer cavity 13, and an annular powder inlet channel 14 that communicates with the photosensitive coupling channel 9 is also opened in the powder buffer cavity 13; the laser output head 1, collimating lens tube 2, lens tube 5, conversion connector 7, Laval cavity 10, end cap 11 and photosensitive coupling channel 9 are interconnected;

[0082] The laser optical path includes: output fiber → laser output head 1 → collimating lens barrel 2 → collimating lens group 3 → converging lens 4 → lens barrel 5 → collimating and shaping lens group 6 → flat top beam;

[0083] The gas-powder co-processing module includes: gas flow path: air inlet 8 → conversion connector 7 → Laval cavity 10 → annular powder inlet channel 14, i.e., photo-powder coupling channel 9;

[0084] Powder flow path: powder inlet nozzle 12 → powder buffer chamber 13 → annular powder inlet channel 14 → throat of Laval chamber 10;

[0085] The pre-activation process of powder focusing within the flat-top laser beam is as follows: the diverging laser output from the laser output head 1 is collimated into a parallel beam using collimating lens group 3 and converging lens 4; the parallel beam is converted into a quasi-flat-top beam with a diameter of 2–10 mm using collimating and shaping lens group 6; a powder convergence point is set inside the nozzle outlet end (2–10 mm from the end face) to allow the supersonic powder flow to converge with the flat-top beam within the closed cavity; the flat-top beam uniformly heats the powder flow with a power density of 15–30 kW / cm² to ensure that the particle surface temperature reaches 0.8–0.95 times the melting point (temperature difference < 50 K).

[0086] The powder buffer chamber uniform flow-narrow slit acceleration synergistic powder delivery process includes: high-pressure argon gas (pressure 1.5–2.5 MPa) is injected into the powder buffer chamber 13 through the air inlet 8, forming a swirling flow field (flow velocity 50–80 m / s); the coating powder is injected into the powder buffer chamber 13 through the powder inlet 12 and is uniformly dispersed in the swirling flow field (agglomeration rate <3%); the powder is accelerated into the nozzle through the annular powder inlet channel 14 (width 0.5–1.5 mm), reaching supersonic speed (Ma=2.0–2.5) at the throat; the powder flow converges into a dense stream with a diameter ≤1 mm (divergence angle <5°) inside the nozzle outlet, improving powder utilization.

[0087] refer to Figure 2 A supersonic laser spraying method includes the following steps:

[0088] Step 1: Multi-parameter closed-loop dynamic control, synchronously monitor the three-dimensional temperature distribution of the molten pool, the powder flow divergence angle and convergence point offset, and the element burn-off rate parameters to construct a process health index. Based on the control trigger conditions, through parameter optimization driven by digital twin, dynamic adjustment of laser power, coordinated control of airflow pressure, and intelligent compensation of powder feed are achieved to reduce coating defects.

[0089] Multi-source sensor signal acquisition and feature fusion:

[0090] Simultaneous monitoring of three core parameters: Infrared thermal imager acquiring the three-dimensional temperature distribution of the molten pool. (Spatial resolution 0.1 mm, sampling rate 10 kHz); High-speed CCD measurement of powder flow divergence angle and convergence point offset (Accuracy ±0.05mm); Elemental burn-off rate detected by plasma spectrometry Calculated using the 358.1 nm spectral line intensity of iron: η = k × (integral of observed spectral intensity - integral of reference spectral intensity) / integral of reference spectral intensity (coefficient k = 0.15, integration wavelength range 358 ± 5 nm);

[0091] Construction Process Health Index (PHI): In the formula, The temperature of the molten pool (acquired by an infrared thermal imager). Reference temperature (standard value), reference value: (Standard divergence angle) The element burn-off rate (detected by plasma spectroscopy); (Maximum allowable burn-off rate); Control trigger conditions: or ;

[0092] Digital twin-driven parameter optimization for real-time prediction of coating defects: Input parameters: laser power P, airflow pressure p, powder feeding rate Vf;

[0093] The pre-trained long short-term memory neural network outputs a predicted value: porosity prediction. Combined with intensity prediction values ; where LSTM is a prediction function based on a long short-term memory neural network;

[0094] Adaptive Particle Swarm Optimization (APSO) for finding optimal parameters: Objective function: Minimize Where J is the objective function used to optimize the parameters;

[0095] Constraints: ; ; Output the globally optimal parameter set: ;

[0096] Multi-channel decoupling compensation implementation: Dynamic laser power adjustment (suppressing hot cracks): Coefficients: K1 = 100 W / ℃, K3 = 0.05 × P max ;parameter: T represents the average temperature of the molten pool. avg The average temperature of the molten pool, Lap T Temperature curvature (unit: K / mm²);

[0097] Airflow and pressure coordinated control (stabilizing powder flow): Δp = K2 × θ + K4 × (Δd / d0) × p maxWhere θ is the powder flow divergence angle, Δp is the airflow pressure adjustment, and Δd and d0 are the convergence point offset and standard convergence distance, respectively; p max Maximum airflow pressure; Coefficients: K2=0.3MPa / °, K4=0.2; Reference value: d0=5mm (reference distance); Intelligent compensation for powder feeding (to prevent element burn-off): ΔVf=-K5×η×Vf+K6×dφ / dt; where ΔVf is the powder feeding compensation amount; Coefficients: K5=1.8, K6=0.08g / (s·% / s); Parameter: dφ / dt is the porosity change rate (% / s).

[0098] Step 2: Adaptive laser focus scanning, real-time monitoring of the distance change between the spray gun and the substrate surface, calculation of focus compensation displacement, adjustment of the axial position of the lens group by the piezoelectric ceramic actuator to correct the focus position, and linkage with the process health index system to switch different working modes according to coating thickness fluctuations;

[0099] In the powder pre-activation step of focusing within the flat-top laser beam, a dynamic focus compensation mechanism is added:

[0100] 201. Real-time surface topology monitoring: A laser displacement sensor (1μm resolution) is integrated at the end 11 to measure the change in distance ΔH between the spray gun and the substrate surface in real time (sampling frequency 5kHz).

[0101] 203. Calculation of focal offset: Based on the distance change ΔH and the preset distance d (2-10mm) of the powder convergence point, calculate the focal compensation displacement: ΔF=k1×ΔH×(d / d0), where k1=0.8 is the empirical compensation coefficient, d0=5mm reference distance, and ΔH is the distance change from the spray gun to the substrate surface (measured in real time by the laser displacement sensor, reflecting the surface topology change).

[0102] 203. Dynamic Focus Adjustment: The axial position of the collimating and shaping lens group 6 is adjusted via a piezoelectric ceramic actuator, with a displacement accuracy of ±0.5μm and a response time of <1ms; Focus position correction formula: F new =F0+ΔF, where F0 is the initial focus position, F new Let ΔF be the new focus position after state adjustment, and ΔF be the calculated focus compensation displacement.

[0103] 204. Linkage with PHI system: When the process health index PHI > 0.2, activate the focus scanning system; when the coating thickness fluctuation is < ±5μm, switch to energy-saving mode (sampling frequency reduced to 1kHz).

[0104] Step 3: Real-time diagnosis of lens anomalies. By using dual-wavelength transmittance monitoring and thermal deformation wavefront diagnosis, a lens health index is constructed and graded responses are implemented. When a lens anomaly occurs, corresponding measures are taken, such as early warning, power reduction, and emergency shutdown. At the same time, the powder delivery amount will also be adjusted in conjunction with the lens health index.

[0105] 301. Dual-wavelength transmittance monitoring: A reference optical sensor (wavelength 635nm) is added at the inlet of laser output head 1; a monitoring optical sensor (wavelength 1064nm) is added at the outlet of the flat-top beam; transmittance T is calculated in real time. ratio :T ratio =(P out / P in )×(λ ref / λ main ), where P out and P in These represent the output power measured by the monitoring optical sensor (wavelength 1064nm), i.e., the laser power after passing through the system, and the input power measured by the reference optical sensor (wavelength 635nm), which is the initial power of the laser before entering the system. λ ref =635nm is the reference wavelength, λ main =1064nm is the main laser wavelength).

[0106] 302. Thermal Deformation Wavefront Diagnosis: A Shaker-Hartmann wavefront sensor is integrated within the conversion connector 7;

[0107] Analysis of beam wavefront distortion: in These are the observed sub-aperture phase and the reference sub-aperture phase, respectively. N=128, and the unit nm represents the number of sub-apertures.

[0108] 303. Abnormal Index Fusion and Three-Level Early Warning: Constructing the Lens Health Index (LHI): LHI = 0.6 × (1 - T) ratio )+0.4×(WFE / 50);

[0109] See the graded response table for graded responses:

[0110]

[0111] 304. Powder Feeding Linkage: When LHI > 0.3, automatically reduce the powder feeding amount by 30% (to prevent the generation of unmelted particles); after troubleshooting, gradually restore according to Vf recovery = Vf0 × [1 - 0.5 × (LHIhistory)], where Vf0 is the initial baseline powder feeding speed and LHIhistory is the last recorded (or relevant historical period) Lens Health Index (LHI) value before troubleshooting.

[0112] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method using a supersonic laser spraying device, characterized in that, The device includes a laser output head (1), one end of which is provided with a collimating lens tube (2), and the other end of which is provided with a lens tube (5). A conversion connector (7) is provided at one end of the conversion connector (7), and a Laval cavity (10) is provided at one end of the Laval cavity (10). An end cap (11) is provided at one end of the end cap (11), and a photosensitive coupling channel (9) is opened within the end cap (11). The collimating lens tube (2) is used to install the collimating lens assembly (3) and the converging lens (4). The lens tube (5) is the lens of the collimating and shaping lens assembly (6). The collimating lens group (3) is used to collimate the diverging laser output from the laser output head (1); the converging lens (4) is used to convert the collimated laser into a converging beam; the collimating and shaping lens group (6) is used to convert the converging beam into a collimated beam and collimate the laser into a flat-top beam; the conversion connector (7) is provided with an air inlet (8); after the end (11) and the Laval cavity (10) are connected in place, a powder buffer cavity (13) and an annular powder inlet channel (14) are formed; the powder buffer cavity (13) is provided with a powder inlet (12) communicating with the outside. The method includes the following steps: S1. Multi-parameter closed-loop dynamic control: Simultaneously monitor the three-dimensional temperature distribution of the molten pool, the powder flow divergence angle and convergence point offset, and the element burn-off rate parameters to construct a process health index. Based on the control trigger conditions, through parameter optimization driven by digital twin, dynamic adjustment of laser power, coordinated control of airflow pressure, and intelligent compensation of powder feed are achieved to reduce coating defects. S2. Adaptive laser focus scanning: Real-time monitoring of the distance change between the spray gun and the substrate surface, calculation of focus compensation displacement, adjustment of the axial position of the lens group by the piezoelectric ceramic actuator to correct the focus position, and linkage with the process health index system to switch working modes according to coating thickness fluctuations. S3. Real-time diagnosis of lens anomalies: By using dual-wavelength transmittance monitoring and thermal deformation wavefront diagnosis, a lens health index is constructed and graded responses are implemented. When a lens anomaly occurs, measures such as early warning, power reduction, and emergency shutdown are taken. At the same time, the powder feeding amount is adjusted in conjunction with the lens health index.

2. The method according to claim 1, characterized in that: The laser output head (1) has a QBH, LOE, LOC or Qplus structure; the collimating lens group (3) consists of 2-4 lenses; The collimating and shaping lens group (6) is used to convert the converging beam into a collimated beam with a diameter of 2mm-10mm; The air inlet (8) is used to inject argon gas; the argon gas forms a supersonic gas flow after passing through the narrow-diameter component of the Laval cavity, and the diameter of the narrow-diameter component is 2mm-10mm; The width of the annular powder inlet channel (14) is 0.5mm-1.5mm; The end (11) is connected to the Laval nozzle by a thread; The powder inlet (12) injects the coating powder using a powder feeder.

3. The method according to claim 1, characterized in that, The specific operation steps of S1 are as follows:

101. Simultaneously monitor the molten pool temperature distribution, powder flow divergence angle and convergence point offset, and element burn-off rate; 102. Calculate the Process Health Index (PHI), expressed as: PHI = 0.4 × |Temperature Fluctuation Rate| + 0.3 × Divergence Angle Deviation Rate + 0.3 × Burn-off Rate Deviation Rate; When PHI > 0.25 or element burn-off rate > 2.5%, control is triggered.

103. Predicting porosity and bonding strength using a long short-term memory neural network model; 104. The optimal laser power, gas flow pressure, and powder feeding rate are determined using an adaptive particle swarm optimization algorithm.

105. Dynamic compensation execution: Adjust the laser power according to the difference between the average temperature of the molten pool and the target temperature and the temperature curvature; adjust the airflow pressure according to the powder flow divergence angle and the convergence point offset; adjust the powder feed rate according to the element burn-off rate and the porosity change rate.

4. The method according to claim 3, characterized in that, The specific operation steps of S2 are as follows:

201. Real-time surface topology monitoring: A laser displacement sensor is integrated at the end (11) to measure the change in distance ΔH between the spray gun and the substrate surface in real time; 202. Calculation of focus offset: Based on the distance change ΔH and the preset distance d of the powder convergence point, calculate the focus compensation displacement: ΔF=k1×ΔH×(d / d0), where k1=0.8 is the empirical compensation coefficient, d is the preset distance of the powder convergence point, which is set between 2mm and 10mm, d0=5mm, and ΔH is the distance change from the spray gun to the substrate surface; 203. Dynamic focus adjustment: Adjust the axial position of the collimating and shaping lens group (6) by means of a piezoelectric ceramic actuator; Focus position correction formula: F new =F0+ΔF, where F0 is the initial focus position, F new The new focal position is the dynamically adjusted position, and ΔF is the calculated focal compensation displacement.

204. Linkage with PHI system: When the process health index PHI > 0.2, the focus scanning system is activated. When the coating thickness fluctuation is less than 5μm, it switches to energy-saving mode, that is, the sampling frequency is reduced to 1kHz.

5. The method according to claim 4, characterized in that, The specific operation steps of S3 are as follows:

301. Calculate laser transmittance in real time using input power sensors and output power sensors; 302. Real-time detection of the wavefront distortion of the laser beam using a wavefront sensor; 303. Calculate the Lens Health Index (LHI) based on transmittance and wavefront distortion, and perform a graded response.

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