Pulse laser in-situ impact type double-beam composite cladding head

Abstract

The invention belongs to the technical field of laser cladding and surface strengthening, and particularly relates to a pulse laser in-situ impact type double-beam composite cladding head which comprises a main beam channel connected with a continuous fiber laser or a long pulse laser and used for transmitting molten laser; the auxiliary light beam channel is connected with the high-frequency pulse laser and transmits pulse laser; the beam splitting and shaping module is used for realizing beam combination or paraxial output of the two paths of laser; the cooling channel is connected with the cooling system through a pipeline; and the powder feeding channel is used for coaxial or lateral powder feeding. According to the scheme, the stable molten pool is formed through the main light beam, the auxiliary light beam irradiates the molten pool in a set angle and pulse mode, transient impact and disturbance on the molten pool are achieved, strong convection in the molten pool is promoted, air hole escape is accelerated, grains are refined, the powder wettability is improved, and the compactness, uniformity and metallurgical bonding quality of a cladding layer are improved. The device has the characteristics of compact structure and independent and controllable light path, and is suitable for preparation of various functional coatings and surface strengthening of components.

Description

Technical Field

[0001] This invention belongs to the field of laser cladding and surface strengthening technology, specifically relating to a pulsed laser in-situ impact dual-beam composite cladding head. Background Technology

[0002] Laser cladding technology, as a high-energy beam surface modification method, has been widely used in aerospace, metallurgical equipment, mining machinery, shipbuilding engineering, and mold manufacturing. This technology rapidly melts alloy powder or wire with a high-energy-density laser beam and metallurgically bonds it to a metal substrate, thereby achieving surface strengthening, preparation of wear-resistant and corrosion-resistant coatings, and repair of damaged parts.

[0003] Although laser cladding technology is highly mature, existing cladding head structures still have the following significant shortcomings: 1. Uneven energy field of single beam: Traditional continuous laser or single-pulse laser cladding heads usually cannot simultaneously control the depth of the molten pool and the forming quality of the cladding layer, which leads to problems such as unstable forming, large surface ripples, overheating or insufficient melting depth of the cladding layer.

[0004] 2. Pores and inclusions in the molten pool are difficult to remove effectively: Due to the limited fluid dynamics of the molten pool, metal vapor and inclusions are difficult to escape fully, resulting in pores and inclusions in the cladding layer, which affects the density and service life of the coating.

[0005] 3. Prominent thermal stress and cracking issues: Continuous laser energy input is stable but the heat-affected zone is wide and the temperature gradient is large, which can easily induce cracks in highly heat-sensitive materials (such as high-hardness steel and nickel-based high-temperature alloys).

[0006] 4. Lack of in-situ control methods for the microstructure of the molten pool: Traditional cladding equipment focuses more on macroscopic energy input and lacks the ability to directly intervene in the transient flow, crystallization behavior and micro-strengthening mechanism inside the molten pool, making it difficult to achieve microstructure optimization such as fine grain strengthening and residual stress control.

[0007] To address the aforementioned shortcomings, technologies such as multi-beam composite cladding, ultrasonic-assisted cladding, and electromagnetic stirring cladding have emerged in recent years. However, these methods generally suffer from limitations such as complex structures, difficulties in integration, insufficient control precision, or excessively high costs, making it difficult to promote industrialization.

[0008] Therefore, there is an urgent need for a composite cladding head that is compact, flexible in control, has an adjustable energy field, and can improve the overall performance and preparation efficiency of the cladding layer. Summary of the Invention

[0009] To address the aforementioned problems in existing technologies, this solution provides a pulsed laser in-situ impact dual-beam composite cladding head. By integrating a continuous main beam and a high-frequency pulsed auxiliary beam within the same cladding head, it achieves coordinated control of the energy field, force field, and temperature field. This cladding head not only significantly improves the density, uniformity, and metallurgical bonding quality of the cladding layer, but also effectively reduces the width of the heat-affected zone, suppresses cracks, and performs in-situ micro-optimization of the molten pool microstructure.

[0010] The technical solution adopted in this invention is as follows: A pulsed laser in-situ impact dual-beam composite cladding head includes: The main beam channel connects to a continuous fiber laser or a long-pulse laser and transmits molten laser light to the molten pool for melting metal powder. The auxiliary beam channel connects to a high-frequency pulsed laser and transmits the pulsed laser to the molten pool; The beam splitting and shaping module is used to achieve beam combining or off-axis output of two laser beams; Cooling passages are connected to the cooling system via pipes; The powder feeding channel is located at the end of the main beam channel and is connected to the powder conveying system. It is used for coaxial or lateral powder feeding, and the powder feeding direction is the same as that of the melting laser.

[0011] Optional: The beam splitting and shaping module includes a beam splitter, fiber optic coupler, mirror, collimating lens, and focusing lens.

[0012] Optional: The lower end of the pulsed laser in-situ impact dual-beam composite cladding head faces the substrate, and the laser is projected onto the substrate to form the main beam molten pool area.

[0013] Optionally: A protective gas nozzle is provided obliquely above the substrate. The protective gas nozzle is connected to an inert gas source and is used to spray inert gas to isolate oxygen, stabilize the molten pool, and form a local protective environment.

[0014] Optional: When the substrate is carbon steel and wear-resistant Ni-based alloy powder is fused onto the carbon steel surface: the power of the molten laser is 800W, the energy of the pulsed laser is 150 mJ, the pulse width of the pulsed laser is 100 ps, ​​and the pulse frequency is 1000 Hz; the scanning speed of the dual-beam laser formed by combining the molten laser and the pulse frequency is 600 mm / min; the powder feeding speed is 10 g / min; the focused spot diameter is 1.2 mm; and the gas delivery speed using argon as a protective gas is 12 L / min.

[0015] Optional: The cooling system is a water-cooled cooling device or an air-cooled cooling device.

[0016] Optional: The frequency of the pulsed laser is 10 Hz to 1000 Hz, and the pulse width of the pulsed laser is 290 fs to 900 ps.

[0017] Optional applications of the pulsed laser in-situ impact dual-beam composite cladding head include: surface strengthening of high-hardness molds, repair of engineering machinery, and preparation of corrosion-resistant and wear-resistant coatings; High-hardness mold surface strengthening is achieved by high-frequency pulse impact, which improves the density and wear resistance of the cladding layer after the molten pool solidifies. Repairing construction machinery involves repairing shafts or rotary drilling gears that have suffered impact wear, thereby extending their service life. The preparation of corrosion-resistant and wear-resistant coatings is achieved by adjusting the dual-beam parameters to achieve dense cladding of Cr, Ni, or WC alloy powders.

[0018] The beneficial effects of this invention are as follows: 1. The cladding head structure of this solution is compact and highly controllable, which can significantly improve the cladding quality and efficiency, and meet the urgent needs of the equipment manufacturing industry for high-performance coatings.

[0019] 2. The dual-beam composite structure of this scheme: The main beam provides stable and controllable molten pool energy, and the auxiliary beam applies transient impact to the molten pool in a pulse manner, so as to form strong convection and micro-region pressure waves inside the molten pool, which is conducive to the escape of pores and grain refinement.

[0020] 3. This scheme realizes the in-situ impact enhancement mechanism: the rapid heating-cooling cycle caused by pulsed laser action generates instantaneous impact pressure on the surface of the molten pool, which improves grain distribution, promotes the wetting of cladding powder and removes inclusions.

[0021] 4. This solution achieves optical path integration and independent parameter control: The cladding head is equipped with a beam splitting control module, which allows the main beam and auxiliary beam to adjust their focal length, power, pulse width, frequency and scanning trajectory separately, adapting to various materials and working conditions.

[0022] 5. The structure of this scheme is suitable for functional gradient and composite cladding: the dual-beam structure can dynamically adjust energy and impact according to the changes in the deposition area, ensuring that the multilayer structure is dense and defect-free at the interface, and realizing the forming of gradient materials. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this scheme or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0024] Figure 1 This is a diagram showing the usage status of the pulsed laser in-situ impact dual-beam composite cladding head; Figure 2 This is a cross-sectional view of a pulsed laser in-situ impact dual-beam composite cladding head; Figure 3 This is a flowchart of the operation of a pulsed laser in-situ impact dual-beam composite cladding head.

[0025] In the diagram: 1-Main beam channel; 2-Auxiliary beam channel; 3-Beam splitting and shaping module; 4-Powder conveying system; 5-Dual beam optical path; 6-Main beam molten pool area; 7-Protective gas nozzle; 8-Cooling system; 9-Powder feeding channel; 10-Cooling channel. Detailed Implementation

[0026] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only a part of the embodiments, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this solution without creative effort are within the protection scope of this solution.

[0027] Example like Figures 1 to 3 As shown in the figure, this embodiment designs a pulsed laser in-situ impact type dual-beam composite cladding head (hereinafter referred to as cladding head). The cladding head includes a main beam channel 1, an auxiliary beam channel 2, a beam splitting and shaping module 3, a cooling channel 10, a powder feeding channel 10 and other structures.

[0028] Main beam channel 1 is located inside the cladding head. Main beam channel 1 is connected to a continuous fiber laser or a long-pulse laser and transmits the molten laser for melting metal powder to the molten pool (see [link]). Figure 2 In the case of laser (laser1), the molten laser is used as the main energy source for the formation of the molten pool.

[0029] Auxiliary beam channel 2 is also located inside the cladding head. Auxiliary beam channel 2 is connected to a high-frequency pulsed laser and transmits pulsed laser light to the molten pool (see [link]). Figure 2 The laser (laser2) in the laser system provides pulsed impact energy. The frequency of the pulsed laser can be 10 Hz to 1000 Hz, and the pulse width can be 290 fs to 900 ps.

[0030] The beam splitter and shaping module 3 is located in the middle of the cladding head and is used to combine or output the two laser beams, the molten laser and the pulsed laser, in a cross-axis manner. The beam splitter and shaping module 3 includes a beam splitter, an optical fiber coupler, a reflector, a collimating lens, and a focusing lens.

[0031] The inlet of the cooling channel 10 is located on the side of the cladding head and is connected to the cooling system 8 via a pipe. When the cooling system 8 is a water-cooled cooling device, the two are connected in a loop; when the cooling system 8 is an air-cooled cooling device, the air outlet of the air-cooled cooling device is connected to the inlet of the cooling channel 10, and the outlet of the cooling channel 10 can be located at the lower end of the cladding head and discharge the cooled air into the air.

[0032] The powder feeding channel is located at the lower part of the cladding head and at the end of the main beam channel 1. The inlet of the powder feeding channel is connected to the powder conveying system 4, and the outlet of the powder feeding channel faces the belt processing part. The powder feeding channel is used for coaxial or lateral powder feeding, and the powder feeding direction is the same as that of the melting laser.

[0033] When in use, the lower end of the cladding head faces the substrate, and the laser is projected onto the substrate to form the main beam molten pool area 6.

[0034] A protective gas nozzle 7 is provided obliquely above the substrate. The protective gas nozzle 7 is connected to an inert gas source and is used to spray inert gas to isolate oxygen, stabilize the molten pool and form a local protective environment.

[0035] The application scenarios of the cladding head in this embodiment include: 1. High-hardness mold surface strengthening High-hardness mold surface strengthening is achieved by high-frequency pulse impact, which improves the density and wear resistance of the cladding layer after the molten pool solidifies.

[0036] 2. Repair of construction machinery Repairing construction machinery involves repairing shafts or rotary drilling gears that have been subjected to impact and wear, thereby extending their service life.

[0037] 3. Preparation of corrosion-resistant and wear-resistant coatings; The preparation of corrosion-resistant and wear-resistant coatings is achieved by adjusting the dual-beam parameters to achieve dense cladding of Cr, Ni, or WC alloy powders.

[0038] Examples of using cladding heads to prepare corrosion-resistant and wear-resistant coatings are as follows: When the substrate is carbon steel and wear-resistant Ni-based alloy powder is fused onto the carbon steel surface: the power of the melting laser is 800 W, the energy of the pulsed laser is 150 mJ, the pulse width of the pulsed laser is 100 ps, ​​and the pulse frequency is 1000 Hz; the scanning speed of the dual-beam laser formed by combining the melting laser and the pulse frequency is 600 mm / min; the powder feeding speed is 10 g / min; the focused spot diameter is 1.2 mm; and the gas delivery speed using argon as a protective gas is 12 L / min.

[0039] Under the above conditions, the cladding layer has significantly reduced porosity, the microstructure changes from coarse columnar crystals to fine equiaxed crystals, the surface hardness increases by 10%–30%, the porosity decreases by 50%–70%, and the fatigue limit increases by 5%–20%.

[0040] The table below compares the mechanical properties of the products processed by the cladding head under the above conditions:

[0041] Furthermore, for different material systems, such as iron-based, nickel-based, and cobalt-based, the molding quality can be controlled by adjusting the main laser beam power, scanning speed, auxiliary laser energy, and time interval.

[0042] In this embodiment, the cladding head forms a stable molten pool through the main beam, while the auxiliary beam irradiates the molten pool at a set angle and in a pulsed manner, achieving transient impact and disturbance to the molten pool. The periodic impact pressure generated by the pulsed auxiliary beam can promote strong convection inside the molten pool, accelerate the escape of pores, refine grains, and improve powder wettability, thereby significantly improving the density, uniformity, and metallurgical bonding quality of the cladding layer.

[0043] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation; it is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom remain within the scope of this technology.

Claims

1. A pulsed laser in-situ impact dual-beam composite cladding head, characterized in that: include: The main beam channel (1) is connected to a continuous fiber laser or a long pulse laser and transmits a molten laser to the molten pool for melting metal powder. Auxiliary beam channel (2) is connected to a high-frequency pulsed laser and transmits pulsed laser to the molten pool; The beam splitting and shaping module (3) is used to realize the beam combining or off-axis output of two lasers; The cooling channel (10) is connected to the cooling system (8) via a pipe; The powder feeding channel is located at the end of the main beam channel (1) and is connected to the powder conveying system (4). It is used for coaxial or lateral powder feeding, and the powder feeding direction is the same as that of the melting laser.

2. The pulsed laser in-situ impact dual-beam composite cladding head according to claim 1, characterized in that: The beam splitting and shaping module (3) includes a beam splitter, an optical fiber coupler, a mirror, a collimating lens, and a focusing lens.

3. The pulsed laser in-situ impact dual-beam composite cladding head according to claim 1, characterized in that: The lower end of the pulsed laser in-situ impact dual-beam composite cladding head faces the substrate, and the laser is projected onto the substrate to form the main beam molten pool area (6).

4. The pulsed laser in-situ impact dual-beam composite cladding head according to claim 3, characterized in that: A protective gas nozzle (7) is provided obliquely above the substrate. The protective gas nozzle (7) is connected to an inert gas source and is used to spray inert gas to isolate oxygen, stabilize the molten pool and form a local protective environment.

5. The pulsed laser in-situ impact dual-beam composite cladding head according to claim 4, characterized in that: When the substrate is carbon steel and wear-resistant Ni-based alloy powder is fused onto the surface of the carbon steel: the power of the melting laser is 800 W, the energy of the pulsed laser is 150 mJ, the pulse width of the pulsed laser is 100 ps, ​​and the pulse frequency is 1000 Hz; the scanning speed of the dual-beam laser formed by combining the melting laser and the pulse frequency is 600 mm / min; the powder feeding speed is 10 g / min; the focused spot diameter is 1.2 mm; and the gas supply speed using argon as a protective gas is 12 L / min.

6. The pulsed laser in-situ impact dual-beam composite cladding head according to claim 1, characterized in that: The cooling system (8) is a water-cooled cooling device or an air-cooled cooling device.

7. The pulsed laser in-situ impact dual-beam composite cladding head according to claim 1, characterized in that: The frequency of pulsed lasers is 10 Hz to 1000 Hz, and the pulse width is 290 fs to 900 ps.

8. The pulsed laser in-situ impact dual-beam composite cladding head according to claim 1, characterized in that: Applications of pulsed laser in-situ impact dual-beam composite cladding head include: surface strengthening of high-hardness molds, repair of engineering machinery, and preparation of corrosion-resistant and wear-resistant coatings; High-hardness mold surface strengthening is achieved by high-frequency pulse impact, which improves the density and wear resistance of the cladding layer after the molten pool solidifies. Repairing construction machinery involves repairing shafts or rotary drilling gears that have suffered impact wear, thereby extending their service life. The preparation of corrosion-resistant and wear-resistant coatings is achieved by adjusting the dual-beam parameters to achieve dense cladding of Cr, Ni, or WC alloy powders.

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