Integrated nozzle based on air curtain type underwater facade laser additive repairing method

Abstract

The invention discloses an integrated nozzle based on an air curtain type underwater facade laser additive repairing method. The integrated nozzle comprises a nozzle body, a laser channel is formed in the center of the nozzle body, and a powder feeding channel is formed in the outer circumferential direction of the nozzle body; a cooling sleeve is arranged in the middle of the nozzle body, and a water-gas coupling sleeve is arranged on the lower portion of the nozzle body and located below the cooling sleeve. A plurality of fan-shaped openings are formed in the bottom of the water-gas coupling sleeve, and a gas outlet and a water flow outlet are formed in each fan-shaped opening in the radial direction; the gas outlets and the water flow outlets in the connected fan-shaped openings are alternately arranged, namely, one fan-shaped outlet is in an inner-side water and outer-side gas distribution mode, and the adjacent fan-shaped outlets are in an inner-side gas and outer-side water distribution mode; according to the air curtain type underwater laser additive repairing method, the air curtain type underwater laser additive repairing principle is utilized, in-situ repairing is conducted on the defects existing in the underwater vertical face position, traditional pumping-out repairing is avoided, the maintenance period is greatly shortened, and the repairing efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of laser remanufacturing and repair technology, specifically to an integrated nozzle based on an air curtain-type underwater facade laser additive repair method. Background Technology

[0002] With the rapid expansion of industries such as marine engineering, shipbuilding, and hydropower, the risk of damage to various underwater structural components—whether deep-sea oil platform pillars, hull plates, turbine blades, or hydropower station gates—is increasing exponentially during their service life. These components are immersed for extended periods in seawater (river water) rich in chloride ions, with high dissolved oxygen levels and dramatic temperature and salinity gradients, leading to a combination of chemical corrosion, electrochemical corrosion, cavitation erosion, and microbial corrosion. Simultaneously, periodic ocean currents, impacts from floating objects, anchor chain dragging, and the attachment of marine organisms further exacerbate surface wear and the initiation of fatigue cracks. Particularly noteworthy is that the vast majority of damage occurs on vertical surfaces. Traditional methods of manual grinding by divers or disassembly and reinstallation on land are not only inefficient and costly but also prone to secondary corrosion due to repeated wet-dry cycles. Statistics show that direct economic losses due to metal corrosion worldwide exceed US$2.5 trillion annually, accounting for approximately 3% to 4% of global GDP, with maintenance and replacement costs for underwater facilities accounting for over 35% of this. Therefore, developing in-situ, low-disturbance, and high-efficiency underwater repair technologies for underwater facade components has become a core requirement for extending the service life of critical infrastructure, reducing the total life cycle cost, and ensuring marine and energy security. Its engineering significance and economic value are self-evident.

[0003] Therefore, a new repair method is needed to achieve in-situ, rapid, and highly reliable underwater repair. To this end, this invention proposes an integrated nozzle specifically designed for repairing underwater facade defects. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes a nozzle specifically designed for underwater laser additive repair of facades. The nozzle is integrally machined from chromium-zirconium copper, an alloy that combines high thermal conductivity, excellent high-temperature strength, and resistance to thermal fatigue. It can rapidly dissipate heat under continuous laser radiation and high-temperature scouring of the molten pool, significantly extending the nozzle's lifespan.

[0005] The technical solution of the present invention is as follows: An integrated nozzle based on an air curtain-type underwater vertical laser additive repair method includes a nozzle body with a laser channel at its center and a powder feeding channel around its periphery. A cooling jacket is located in the middle of the nozzle body, and a water-gas coupling sleeve is located at the lower part of the nozzle body, below the cooling jacket. A water inlet and a gas inlet are located on the side of the water-gas coupling sleeve. Multiple fan-shaped openings are located at the bottom of the water-gas coupling sleeve, each fan-shaped opening having a gas outlet and a water outlet radially. The gas outlet and water outlet in adjacent fan-shaped openings are alternately arranged; that is, if one fan-shaped outlet has water on the inside and gas on the outside, then adjacent fan-shaped outlets have gas on the inside and water on the outside. The alternating arrangement of the gas outlet and water outlet ensures that a stable gas chamber can be formed on the entire circumference of the nozzle tip during deposition repair on a vertical surface.

[0006] Furthermore, the cooling jacket is inverted conical in shape, with a water-cooling inlet on one side and a water-cooling outlet on the other. The inverted conical shape of the cooling jacket is because the powder path intersection area is located above the nozzle. This area experiences a significantly higher instantaneous heat flux density than other parts of the laser channel due to the dual heat input from laser irradiation and powder melting. Accordingly, extending the water-cooling channel at the corresponding location can enhance local heat exchange capacity, achieving more thorough and uniform cooling of the hot end of the nozzle.

[0007] Furthermore, after the outlet end of the powder feeding channel extends into the cooling jacket, it is connected to the laser channel, so that the laser channel and the powder feeding channel are coaxially coupled inside the nozzle.

[0008] Furthermore, each of the water inlets is connected to two adjacent water outlets via branch pipes; each of the gas inlets is connected to two adjacent gas outlets via branch pipes.

[0009] Furthermore, the water inlet and water outlet are connected by a water channel, and the gas inlet and gas outlet are connected by a gas channel. The cross-section of the water channel and the gas channel is fan-shaped, and the whole structure is a cone shape with a smaller top and a larger bottom. This structure can evenly disperse water or gas into a large arc range at the outlet, which facilitates the subsequent water-gas mixing and ejection.

[0010] The beneficial effects of this invention are as follows: 1) Utilizing the principle of underwater laser additive repair based on air curtain, in-situ repair is carried out on defects in the underwater facade, avoiding traditional desiccation repair, greatly reducing the maintenance cycle and improving repair efficiency.

[0011] 2) Through the synergistic effect of the "water-air" flow field, the flexibility and high energy utilization of the air curtain underwater additive manufacturing are preserved. The flow field is used to reduce the pressure difference and thus control the buoyancy interference on the air curtain. This overcomes the problems of instability and floating caused by the air curtain being affected by buoyancy under vertical working conditions. Finally, continuous, defect-free, high-quality laser additive repair is achieved on the underwater vertical surface. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the facade additive repair of the present invention; Figure 2 A front view of an integrated nozzle for laser additive repair of an underwater facade based on an air curtain system; Figure 3 A top view of an integrated nozzle for laser additive repair of an underwater facade based on an air curtain system; Figure 4 A bottom view of an integrated nozzle for laser additive repair of an underwater facade based on an air curtain system; Figure 5 This is a partial enlarged view of the integrated nozzle bottom view based on air curtain underwater facade laser additive repair; Figure 6 A cross-sectional view of an integrated nozzle for laser additive repair of an underwater facade based on an air curtain system; Figure 7 This is a partial enlarged view of the AA sectional view; Figure 8 A BB cross-sectional view of an integrated nozzle for laser additive repair of an underwater facade based on an air curtain system; Figure 9 This is a schematic diagram of the gas and water flow outlets; Figure 10 Axonometric drawing of nozzles for facade additive repair; Figure 11 Comparison of repair effects between the present invention and existing technologies; In the diagram: 1 is the laser channel, 2 is the powder feeding channel, 3 is the water cooling inlet, 4 is the water cooling outlet, 5 is the gas inlet, 6 is the water inlet, 7 is the gas outlet, and 8 is the water outlet. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings.

[0014] like Figure 1-10 As shown, an integrated nozzle for underwater facade laser additive repair based on an air curtain includes a laser channel 1; a powder feeding channel 2; a water-cooled inlet 3; a water-cooled outlet 4; a gas inlet 5; a water inlet 6; a gas outlet 7; and a water outlet 8. Among them, laser channel 1 is an optical path that runs through the entire nozzle. It guides the laser beam from the optical fiber or collimating lens directly to the workpiece surface with minimal loss and maximum coaxiality, and precisely intersects with the powder beam at the nozzle exit to form a molten pool. The inner wall of the channel has a protective gas flowing from top to bottom, which not only prevents the lens and molten pool from oxidizing, but also stabilizes the powder convergence point through airflow shaping. This is a key factor that determines the spot diameter, powder coupling efficiency and final repair quality.

[0015] The powder feeding channel 2 consists of four precision pipelines arranged along the outside or off-axis of the laser channel. It sprays the metal powder from the powder storage cylinder directly onto the center of the laser spot formed on the workpiece surface at a stable, uniform and controllable flow rate, so that the powder is instantly melted by the laser during flight and deposited into a layer. Cooling water is injected through water-cooling inlet 3, first filling the entire annular cavity, absorbing and carrying away a large amount of heat generated during the laser additive repair process, and then the heated water is discharged through water-cooling outlet 4, forming a continuous and stable closed water-cooling cycle.

[0016] Gas inlet 5 is used to transport gas, and water inlet 6 is used to transport water into the interior.

[0017] The gas outlet 7 is mainly used to isolate the external water environment from the interference of the internal flow field, while the water outlet 8 is used to add a ring flow field. By increasing the flow velocity, the pressure gradient in the vertical direction is reduced, thereby reducing buoyancy and suppressing interference with the air curtain.

[0018] The underwater facade environment requires the area to be repaired to remain relatively dry throughout the laser deposition process. To this end, eight mixed jet outlets (fan-shaped outlets) are first arranged coaxially around the laser channel 1. Each outlet is composed of an air channel and a water channel that cross each other. The buoyancy of the air curtain can be finely adjusted by each of the eight jet outlets, thereby significantly extending the stabilization time of the molten pool in the fluctuating environment. At the same time, an external water pump continuously pressurizes the cool water at a lower temperature into the water cooling channel from the water cooling inlet 3 below. The water flow spreads and quickly fills the entire annular water cooling cavity, uniformly cooling the laser channel and the surrounding structure. The heated cooling water then flows out from the water cooling outlet 4 above and returns to the external heat dissipation device, forming a continuous and stable closed water cooling cycle to ensure that the deposition area is always in a relatively dry and temperature-controllable state.

[0019] When the laser enters through the channel opening of laser channel 1, it couples with the powder output from the surrounding powder feeding pipes 2 inside the laser channel. The powder is then emitted along with the protective gas of the laser channel through the powder-carrying gas in the powder pipe. At the same time, the coaxial "gas-liquid" coupling layer distributed on the outside is continuously generated, forming a natural protective barrier that prevents external water from entering the molten pool due to pulsation, thus creating a stable dry environment for laser additive repair.

[0020] The laser and protective gas are emitted from laser channel 1. Powder is transported to the laser channel by powder-carrying gas in powder-feeding channel 2 and coupled with the laser. The powder then enters the molten pool and is captured, thus realizing the additive repair process. Since the repair environment is underwater, the area to be repaired needs to be kept relatively dry. This patent is based on air curtain underwater laser additive technology. On this basis, a coaxially distributed "water-air" coupling structure is added around the main channel, and the outlet faces outward. This can prevent water pulsation when the airflow is emitted, further ensuring the stability of the dry area.

[0021] Basic principle: When the nozzle remains horizontal, the fan-shaped outlets are radially distributed, meaning the gas inlet 5 and water inlet 6 are alternately distributed. Through internal channels, each fan-shaped outlet forms a structure with a water outlet 8 and a gas inlet 7 along the radial direction. After continuous ejection from the central air curtain, it naturally floats upwards due to buoyancy caused by the density difference, making it difficult to form a stable air chamber in front of the nozzle. Therefore, an annular slit water flow channel is set around the air curtain: when the water flow velocity is sufficiently high, according to the Bernoulli effect, the static pressure in the high-speed zone decreases, partially offsetting the vertical pressure gradient caused by water depth differences, thus significantly weakening buoyancy and allowing the air curtain to maintain stable horizontal movement over a longer distance, providing a continuous localized dry environment for the cladding zone. Simultaneously, the continuous air ejection from the fan-shaped outlets forms a second air curtain, effectively isolating external water and suppressing its disturbance to the internal flow field. Furthermore, the fan-shaped channels are arranged coaxially alternately: if a fan-shaped outlet has an "inner water, outer air" distribution, then the adjacent fan-shaped outlets must have an "inner air, outer water" distribution, further preventing external water from entering the dry environment. Both water-gas configurations allow for independent control of the local dry zone morphology at their respective outlets. Thanks to the aforementioned dual-medium coupling layer, the system achieves stable characteristics under steady-state operation, including constant spatial location, clear boundaries, and fluctuation amplitude approaching zero. Example

[0022] This invention employs a water-air mixing and central air curtain coupling isolation scheme to achieve the repair of defects in underwater facade components: Secure the nozzle to the sleeve of the laser cladding equipment lens assembly using four set screws, ensuring the correct focus. Add argon gas as the central gas curtain in the laser channel, and connect powder pipes to the four peripheral powder delivery channels to transport powder for defect repair. When the nozzle is actually working in a horizontal position, the water cooling inlet should be located at the bottom and the water cooling outlet should be located at the top. The cooling water flowing out of the water chiller is directed into the lower water cooling inlet and then connected to the upper outlet to the water flow inlet of the water chiller, thus forming a cooling cycle. Each water inlet and gas inlet is connected to the corresponding water source and gas source, respectively, so that the "water-gas" flow rate at each mixed jet outlet can be precisely controlled during actual operation. After installation, iron-based alloy powder is added to the powder feeder, while argon is still used as the powder carrier. Oxidation occurs in the molten pool on the wall. The laser power is 1600W, the scanning speed is 10mm / s, the powder feeding rate is 1r / min, the central air curtain is 1000L / h, and the "water-air" is 1L / min and 3L / min respectively, so as to realize laser additive repair of underwater facade components.

[0023] The core technology of this invention is a coaxial fan-shaped structure with eight rings distributed together, and each fan-shaped structure contains a double-layer "water-air" mixture coupled with a central air curtain for isolation. 1) Central gas curtain: The laser channel and the powder feeding channel are coaxially coupled inside the nozzle. Argon gas at a certain flow rate carries metal powder out of the nozzle, forming a local dry cavity underwater, which isolates water from the interference of laser energy absorption, molten pool cooling and powder transportation.

[0024] 2) Water-Air Coupling Layer: A water-air coupling structure is added around the main channel, where each fan-shaped outlet consists of an air outlet and a water outlet. Furthermore, the gas and water at each inlet / outlet and outlet can be independently and adjustable in terms of flow rate and pressure, allowing for precise adjustment of the air curtain thickness, velocity distribution, and zoning. This independent coupling control mechanism allows for the repair of defects at different underwater inclination angles, expanding the repair range and better meeting practical needs.

[0025] like Figure 11 As shown, the left side shows the repair result of the existing technology. The repair layer is grayish-black overall, and the surface overlap is uneven, indicating that the air chamber is unstable and the water entering the molten pool from the outside causes the repair process to be unstable. The right side shows the effect of underwater facade repair using the present invention. It can be seen that the surface is smoother and more polished, with a silvery-white effect, indicating that the air chamber formed at the front end of the nozzle is stable during facade deposition repair, achieving the expected effect.

Claims

1. An integrated nozzle based on an air curtain-type underwater facade laser additive repair method, comprising a nozzle body, wherein a laser channel (1) is provided at the center of the nozzle body and a powder feeding channel (2) is provided in the outer circumferential direction; characterized in that, The nozzle body is provided with a cooling jacket in the middle, and a water-gas coupling sleeve is provided at the lower part of the nozzle body and below the cooling jacket; the water-gas coupling sleeve is provided with a water inlet (6) and a gas inlet (5) on the side; the bottom of the water-gas coupling sleeve is provided with multiple fan-shaped openings, and each fan-shaped opening is provided with a gas outlet (7) and a water outlet (8) in the radial direction; and the gas outlet (7) and water outlet (8) in adjacent fan-shaped openings are alternately arranged, that is, a fan-shaped outlet is distributed with water on the inside and gas on the outside, and the adjacent fan-shaped outlets are distributed with gas on the inside and water on the outside.

2. The integrated nozzle according to claim 1, based on an air curtain-type underwater facade laser additive repair method, is characterized in that, The cooling jacket is inverted cone shape, with a water cooling inlet (3) on one side and a water cooling outlet (4) on the other side.

3. The integrated nozzle according to claim 1, based on an air curtain-type underwater facade laser additive repair method, is characterized in that... After the outlet end of the powder feeding channel (2) extends into the cooling jacket, it is connected to the laser channel (1), so that the laser channel (1) and the powder feeding channel (2) are coaxially coupled inside the nozzle.

4. The integrated nozzle according to claim 1, based on an air curtain-type underwater facade laser additive repair method, is characterized in that... Each water inlet (6) is connected to two adjacent water outlets (8) via branch pipes; each gas inlet (5) is connected to two adjacent gas outlets (7) via branch pipes.

5. The integrated nozzle according to claim 1, based on an air curtain-type underwater facade laser additive repair method, is characterized in that... The water inlet (6) and the water outlet (8) are connected by a water channel, and the gas inlet (5) and the gas outlet (7) are connected by a gas channel. The cross-sections of the water channel and the gas channel are fan-shaped, and the whole is cone-shaped with a smaller top and a larger bottom.

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