A device and method for water-guided laser-assisted laser-directed energy deposition

Abstract

This invention discloses a device and method for water-guided laser-assisted laser-directed energy deposition. The device includes: a water-guided laser processing system, a laser-directed energy deposition system, a worktable, and a control system. The water-guided laser processing system generates a laser jet beam to process microstructures on the deposition area of ​​a substrate or a workpiece with a highly reflective metallic material. The laser-directed energy deposition system deposits the highly reflective metallic material in the deposition area and manufactures the workpiece using a layer-by-layer deposition method. During the workpiece forming process, the worktable moves the workpiece up and down by driving the substrate. The control system is connected to the laser-directed energy deposition system, the water-guided laser processing system, and the worktable, alternately controlling the connected components. By generating microstructures on the workpiece surface using a water-guided laser, and utilizing the multiple reflections and absorptions of the laser within the microstructures, the laser absorptivity, surface roughness, and wettability are significantly improved, while the thermal conductivity of the material surface is reduced.

Description

Technical Field

[0001] This invention belongs to the field of laser additive manufacturing technology, and more specifically, relates to an apparatus and method for water-guided laser-assisted laser directional energy deposition. Background Technology

[0002] Laser direct energy deposition (LDED) is an additive manufacturing technology that can create large, complex metal parts requiring minimal or no machining through layer-by-layer deposition. Copper and aluminum alloys are commonly used metal materials in industry, and their application in complex parts is becoming increasingly widespread. However, LDED forming of highly reflective metals such as copper and aluminum alloys currently faces significant challenges: First, the reflectivity of the infrared fiber lasers most commonly used in LDED is very high, resulting in low laser energy utilization. Furthermore, reflected light can easily damage the laser and optical system lenses. In addition, the absorption rate of these highly reflective metals in the infrared laser band increases dramatically in the molten state, leading to a large difference in laser energy absorbed before and after melting, causing molten pool spatter and unstable processing quality. Second, the metals have extremely high thermal conductivity, resulting in a low temperature and weak flow driving force in the molten pool after laser treatment. The molten pool also has a short lifespan and solidifies quickly, causing poor wettability and insufficient molten pool spreading during LDED forming. This results in an uneven surface, metallurgical defects, and negatively impacts forming quality and efficiency.

[0003] To address the challenges and low efficiency of infrared laser processing of highly reflective metals, relevant research has been conducted both domestically and internationally. The most common method involves pre-depositing a layer of material with high laser absorption on the surface of the highly reflective metal. However, this method introduces impurities, altering the material's properties, and is unsuitable for layer-by-layer laser-directed energy deposition (LDED) manufacturing. A second method involves increasing the temperature of the highly reflective metal through auxiliary heating, leveraging the principle that laser absorption increases with temperature. However, under solid-state conditions, temperature has minimal impact on the laser absorption of highly reflective metals, failing to significantly improve absorption. A third method utilizes short-wavelength lasers such as blue or green light, taking advantage of the high absorption of this wavelength in highly reflective metals for LDED manufacturing. However, these lasers are currently underdeveloped, and achieving optimal laser power and beam quality is difficult, making them unsuitable for large-size parts and high-efficiency industrial applications. Furthermore, none of the above methods solve the problems of poor wettability and poor spreading during the LDED forming process of highly reflective metals, making it difficult to control the forming quality.

[0004] The paper "Influence of Laser Texturing Process on Infrared Laser Absorption Rate of Copper Surface" by Zhao Ying et al. from Wenzhou University uses laser etching to construct microstructures on the surface of copper plates, significantly improving the absorption rate of infrared lasers on the copper surface. However, this method uses lasers to directly etch in air, which is a dry etching process. During laser etching, the workpiece surface temperature is very high, leading to strong oxidation (oxygen content as high as 11.5%). The significant increase in laser absorption rate is a combined result of the oxide layer, deep trenches, and rough surface. When oxidation is not severe, the trench depth is small, the number of laser reflections and absorptions is limited, and the improvement in laser absorption rate is limited. Therefore, this technology still has shortcomings when applied to the layer-by-layer LDED forming technology: the laser absorption rate can only be significantly improved when deep trenches and strong oxidation coexist. At this time, the accumulation of oxide layers will cause a significant decrease in the various properties of the parts, especially the thermal conductivity, electrical conductivity and toughness. Secondly, due to the short focal depth of the laser focusing spot, the dry etching depth is small, and the trenches are small-angle trenches such as "V" shapes, so the number of times the laser is reflected and absorbed in them is less, which makes the improvement in laser absorption rate not high enough.

[0005] Therefore, existing technologies suffer from low laser absorption rate, excessively rapid heat conduction, and the resulting low molten pool temperature, poor wettability, and poor molten pool spreading. Summary of the Invention

[0006] In view of the shortcomings of related technologies, the purpose of this invention is to provide a device and method for water-guided laser-assisted laser directional energy deposition, which aims to solve the problems of low laser absorption rate, excessively fast heat conduction, poor wettability, and poor molten pool spreading in the prior art.

[0007] To achieve the above objectives, the present invention provides a water-guided laser-assisted laser directional energy deposition apparatus, comprising: a water-guided laser processing system, a laser directional energy deposition system, a worktable, and a control system; The water-guided laser processing system is used to generate a laser jet beam to process microstructures on the deposition area of ​​a substrate surface or a workpiece with a highly reflective metallic material; the microstructures are trenches or pits, with a width of 30-100 μm, a depth of 50-300 μm, and an aspect ratio greater than or equal to 5. The laser-directed energy deposition system is used to deposit highly reflective metallic materials on the surface of a substrate, form a deposition layer in the deposition area, and manufacture processed parts by a layer-by-layer deposition method; The worktable is used to lift and lower the workpiece by driving the substrate during the workpiece forming process; The control system is connected to the laser-directed energy deposition system, the water-guided laser processing system, and the worktable, respectively, and is used to alternately control the connected components. The control system controls the water-guided laser processing system to perform water-guided laser processing on the substrate surface or the deposition layer area to generate microstructures. The control system controls the laser-directed energy deposition system to deposit a layer of highly reflective metal material on the substrate surface or the deposition layer area. The control system controls the worktable to descend by a distance equal to the thickness of the deposition layer after the laser-directed energy deposition system has deposited a layer of highly reflective metal material.

[0008] Optionally, the laser-directed energy deposition system includes: a laser deposition head, a first optical fiber, a continuous laser, a first motion mechanism, and a powder feeder; The continuous laser emits a continuous laser beam that is transmitted through the first optical fiber to the laser deposition head. The powder feeder delivers the highly reflective metal material powder to a preset position in the deposition area. After collimation, the laser beam is focused onto the deposition area on the substrate surface or the surface of the workpiece with the highly reflective metal material. The highly reflective metal material and the highly reflective metal material powder in the deposition area are melted to form a molten pool. After solidification, a deposition layer is formed in the deposition area. The first motion mechanism is used to drive the laser deposition head to move along a preset path and speed.

[0009] Optionally, the laser-directed energy deposition system further includes a water chiller, a powder recovery unit, and a negative pressure powder collection port; The water chiller is connected to the laser deposition head and is used to cool the laser deposition head; The powder recovery machine is connected to a negative pressure powder collection port, which is located on one side of the substrate. The powder recovery machine is used to collect unmelted high-reflectivity metal powder through the negative pressure powder collection port.

[0010] Optionally, the water-guided laser processing system includes: a pulsed laser, an optical path system, a water pump, a water delivery pipe, a water-guided laser processing head, and a second motion mechanism; The optical path system includes a beam expander and collimator and a focusing lens; The pulsed laser emits pulsed laser light, which is transmitted to the water-guided laser processing head through the optical path system; The water pump is connected to the water-guided laser processing head via the water supply pipe; The second motion mechanism is used to move the water-guided laser processing head to a designated position in space; The water-guided laser processing head generates a laser jet beam, which is transmitted to the deposition area on the substrate surface or the surface of the workpiece with highly reflective metal material, thereby creating microstructures.

[0011] Optionally, the pressure of the water flow provided by the water pump to the water-guided laser processing head can be adjusted to obtain microstructures with different cross-sectional shapes.

[0012] Optionally, the water-guided laser processing system further includes a high-pressure gas supply device; The high-pressure gas supply device includes a high-pressure gas cylinder, a gas pressure regulating valve, a gas delivery pipeline, and a gas nozzle; the gas nozzle is tightly fitted and positioned below the water-guided laser processing head; The high-pressure gas supply device is used to transport the gas from the high-pressure gas cylinder to the gas nozzle through the gas pipeline, and the gas protects the stable transmission of the laser jet beam when the water-guided laser processing head ejects the laser jet beam. The high-pressure air supply device is also used to dry the residual water stains on the surface of the workpiece with high-pressure airflow after the water-guided laser processing is completed.

[0013] Optional features also include a camera; The camera is positioned directly above the substrate to acquire the morphology of the microstructure and the surface morphology of the processed part after each deposition by the laser-directed energy deposition system.

[0014] In a second aspect, the present invention also provides a method for water-guided laser-assisted laser directed energy deposition, applied to the apparatus for water-guided laser-assisted laser directed energy deposition as described in any one of the first aspects, comprising: Based on the 3D CAD model of the workpiece, the workpiece is sliced ​​and a path is planned; Based on the path planning results, a laser jet beam is generated by a water-guided laser processing system to process microstructures on the deposition area of ​​the substrate surface or the surface of the workpiece with highly reflective metal material. Based on the path planning results, LDED shaping is performed in the generated microstructure region, and a highly reflective metallic material is deposited on the substrate surface using a laser directional energy deposition system to form a deposition layer in the deposition region. The worktable lowers the substrate and workpiece by a distance equal to the thickness of a deposition layer. Alternately control the laser-directed energy deposition system, the water-guided laser processing system, and the worktable to generate microstructures and deposit highly reflective metallic materials until the workpiece is completed.

[0015] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following beneficial effects: 1. This invention provides a water-guided laser-assisted laser-directed energy deposition (LDED) device. It employs water-guided laser processing technology to form microstructures 30-100 μm wide and 50-300 μm deep on highly reflective metal surfaces. The cross-sectional shape of the microstructures is controllable, allowing the continuous laser used in LDED to undergo multiple reflections and absorptions within the microstructures, significantly improving the laser absorption rate. This increases the absorption rate of infrared lasers in copper alloys from 5% to over 80%, and in aluminum alloys from 10% to over 90%. Simultaneously, the microstructures generated by this invention significantly reduce the thermal conductivity of the material surface, improve surface roughness and wettability, resulting in a larger molten pool size and better molten pool spreadability during LDED processing, thus improving the forming quality of highly reflective metals.

[0016] 2. This invention provides a device for water-guided laser-assisted laser directional energy deposition, which uses water-guided laser processing technology to process microstructures on the surface of a formed object. The process is simple, does not introduce impurity elements, and ensures that the material properties and part performance are not affected. Furthermore, the unmelted powder can be recycled using a recycling device.

[0017] 3. This invention provides a water-guided laser-assisted laser energy deposition (LDED) device that uses water flow to cool the LDED-formed parts, making the internal grains of the parts finer and more uniform, avoiding the coarse grains and excessive growth of columnar crystals caused by excessive temperature, and obtaining better part performance. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a water-guided laser-assisted laser directional energy deposition device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the water-guided laser processing head and gas nozzle provided in an embodiment of the present invention; Figure 3 This is a schematic flowchart of a water-guided laser-assisted laser-directed energy deposition method provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the processing of the three-dimensional letter part for the letter "HUST" provided in Embodiment 2 of the present invention; Figure 5 This is a schematic diagram of microstructures with different cross-sectional shapes and multiple reflections of laser light in the microstructures provided in the embodiments of the present invention.

[0019] In the diagram: 1. Laser deposition head; 2. First optical fiber; 3. Continuous laser; 4. First motion mechanism; 5. Water chiller; 6. Powder feeder; 7. Powder recovery machine; 8. Main control unit; 9. High-pressure gas cylinder; 10. Water pump; 11. Gas pressure regulating valve; 12. Pulsed laser; 13. Second optical fiber; 14. Second motion mechanism; 15. Water-guided laser processing head; 16. Optical path system; 17. Gas nozzle; 18. Water supply pipeline; 19. Gas supply pipeline; 2 0. Negative pressure powder collection port; 21. Camera; 22. Worktable; 23. Substrate; 24. Processed part; 25. Water inlet; 26. Gas inlet; 27. Water and gas outlet; 28. Area to be processed; 29. ​​Microstructure area; 30. Residual water stains; 31. Laser jet beam; 32. High-pressure airflow; 33. Unmelted powder; 34. "V" shaped microstructure; 35. "U" shaped microstructure; 36. Rectangular microstructure; 37. Trapezoidal microstructure. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0022] Example 1 A device for water-guided laser-assisted laser directional energy deposition includes: a water-guided laser processing system, a laser directional energy deposition system, a worktable, and a control system; The water-guided laser processing system is used to generate a laser jet beam to process microstructures on the deposition area of ​​a substrate surface or a workpiece with a highly reflective metallic material; the microstructures are trenches or pits, with a width of 30-100 μm, a depth of 50-300 μm, and an aspect ratio greater than or equal to 5. The laser-directed energy deposition system is used to deposit highly reflective metallic materials on the surface of a substrate, form a deposition layer in the deposition area, and manufacture processed parts by a layer-by-layer deposition method; The worktable is used to lift and lower the workpiece by driving the substrate during the workpiece forming process; The control system is connected to the laser-directed energy deposition system, the water-guided laser processing system, and the worktable, respectively, and is used to alternately control the connected components. The control system controls the water-guided laser processing system to perform water-guided laser processing on the substrate surface or the deposition layer area to generate microstructures. The control system controls the laser-directed energy deposition system to deposit a layer of highly reflective metal material on the substrate surface or the deposition layer area. The control system controls the worktable to descend by a distance equal to the thickness of the deposition layer after the laser-directed energy deposition system has deposited a layer of highly reflective metal material.

[0023] like Figure 1 As shown, the water-guided laser processing system includes: a pulsed laser 12, an optical path system 16, a water pump 10, a water supply pipe 18, a water-guided laser processing head 15, and a second motion mechanism 14. The pulsed laser 12 emits pulsed laser light, which is transmitted to the water-guided laser processing head 15 through the optical path system 16; The water pump 10 is connected to the water-guided laser processing head 15 through the water supply pipe 18; The second motion mechanism 14 is used to drive the water-guided laser processing head 15 to a designated position in space; The water-guided laser processing head 15 generates a laser jet beam, which is transmitted to the deposition area on the surface of the substrate 23 or the surface of the workpiece 24 with a highly reflective metallic material, thereby processing and generating microstructures.

[0024] In the process of water-guided laser processing of microstructures, the laser emitted from the pulsed laser passes through the optical path system and enters the water-guided laser processing head, coupling into the water jet to form a laser jet beam. The water-guided laser processing system performs water-guided laser processing on the corresponding deposition area on the substrate surface to produce microstructures with a width of 30-100 μm and a depth of 50-300 μm, with a depth-to-width ratio greater than or equal to 5:1. The microstructures can be trenches or pits; trenches can be arranged in parallel or intersecting patterns, and pits can be arranged in any manner. The cross-sections of the microstructures are all U-shaped, rectangular, or even trapezoidal with large angles and great depths. When using lower water flow pressure, the scouring effect of the water flow edge on the material is weaker, the material at the bottom center of the microstructure is eroded faster, and the edge erosion is slower, resulting in a "U"-shaped cross-section. When using medium water flow pressure, the scouring effect of the water flow on the microstructure is uniform, the material erosion rate at the bottom of the microstructure is uniform, and the cross-section is rectangular. When using higher water flow pressure, the water flow sputters after reaching the bottom of the microstructure, and the laser is scattered at the bottom of the microstructure and acts on the sidewalls of the microstructure, causing a certain degree of erosion of the material on the sidewalls of the microstructure. The cross-section of the microstructure is trapezoidal, narrow at the top and wide at the bottom.

[0025] Microstructures can significantly improve the laser absorption rate of high-reflectivity metal materials, reduce the thermal conductivity of the materials, and improve the surface wettability of the materials simply by increasing the number of laser reflections and absorptions in the grooves, without changing the chemical composition of the material surface. This effectively solves the problems of low laser energy utilization, poor processing quality, and low efficiency caused by the low laser absorption rate of high-reflectivity metals during LDED forming.

[0026] A laser-directed energy deposition system is used to deposit a layer of highly reflective metallic material in the microstructure area, forming the first deposition layer. The first deposition layer of the substrate and part is lowered by a stage by a distance equal to the thickness of the deposition layer. Then, the water-guided laser processing system processes the microstructure on the deposition area of ​​the first deposition layer to obtain a new microstructure. This process is repeated until a high-density, highly reflective material part is finally produced.

[0027] Furthermore, the water-guided laser processing system can be used alternately for microstructure processing and LDED deposition forming. Using the water-guided laser processing system to process microstructures online can improve the laser absorption rate of highly reflective metals, reduce the thermal conductivity of materials, and improve surface wettability. The water flow can also reduce heat accumulation during LDED forming and prevent workpiece surface oxidation, thereby improving the efficiency and quality of laser-directed energy deposition without changing the chemical composition of the materials.

[0028] The optical path system includes a beam expander and a focusing lens, which are used to collimate and focus the pulsed laser, respectively.

[0029] The second motion mechanism 14 is used to drive the water-guided laser processing head 15 and its optical path system to move along a specified path and speed. It can be a robotic arm or a multi-axis motion platform, etc.

[0030] Optionally, the pressure of the water flow provided by the water pump to the water-guided laser processing head can be adjusted to obtain microstructures with different cross-sectional shapes.

[0031] like Figure 5 As shown, microstructures with different cross-sectional shapes can be generated as needed, including: V-shaped microstructure 34, U-shaped microstructure 35, rectangular microstructure 36 and trapezoidal microstructure 37.

[0032] Among the four shapes of microstructures mentioned above, the V-shaped microstructure 34 has the fewest laser reflections and absorptions, resulting in the worst effect. The other three microstructures are generally used. Among them, the trapezoidal microstructure 37 is generally an inverted trapezoidal microstructure, which has the most laser reflections and absorptions and the best "light trapping" effect. However, it is easy to form holes during laser directional energy deposition, resulting in poor part density. Therefore, from the perspective of comprehensive effect, the U-shaped microstructure 35 and the rectangular microstructure 36 are preferred.

[0033] The pulsed laser can be an infrared laser, a green laser, or an ultraviolet laser, and the pulse width can be nanosecond, picosecond, or femtosecond.

[0034] When the pulsed laser used is a femtosecond laser or a picosecond laser, the laser emitted by the pulsed laser 12 is directly injected into the optical path system 16, or, depending on the positional relationship between the laser 12 and the optical path system 16, the laser is injected into the optical path system 16 through a reflector; when the pulsed laser 12 used is a nanosecond laser, the water-guided laser processing system also includes a second optical fiber 13, through which the laser is transmitted to the optical path system 16.

[0035] Furthermore, the pulsed laser is preferably a green nanosecond laser. The wavelength is chosen because water has a low absorption rate of green light, resulting in higher transmission efficiency in water compared to other wavelengths. The pulse width is chosen to be nanosecond because nanosecond lasers have lower peak power than picosecond or femtosecond lasers, making them less prone to water breakdown and enabling more efficient transmission in water. Additionally, nanosecond lasers offer higher average power and processing efficiency at the same price point.

[0036] Optionally, the water-guided laser processing system further includes a high-pressure gas supply device; The high-pressure gas supply device includes a high-pressure gas cylinder 9, a gas pressure regulating valve 11, a gas transmission pipeline 19, and a gas nozzle 17; the gas nozzle 17 is closely fitted and disposed below the water-guided laser processing head 15; The high-pressure gas supply device is used to transport the gas from the high-pressure gas cylinder 9 to the gas nozzle 17 through the gas pipeline 19. When the gas is ejected from the water-guided laser processing head 15, it protects the stable transmission of the laser jet beam. The high-pressure air supply device is also used to dry the residual water stains on the surface of the workpiece with high-pressure airflow after the water-guided laser processing is completed.

[0037] When processing microstructures using a water-guided laser processing system, the gas pressure regulating valve 11 is adjusted to increase the airflow pressure, making it a low-speed airflow. This forms a coaxial rotating gas film on the surface of the laser jet to protect the stability of the water jet. After processing one layer of microstructure, the laser jet is turned off, and the gas pressure regulating valve 11 is adjusted to increase the airflow pressure, making it a high-speed airflow. The high-speed airflow is used to dry the water stains on the workpiece surface, preparing for LDED forming. During LDED forming, the airflow is turned off.

[0038] Preferably, the high-pressure gas supply device can be implemented in various ways. In addition to the gas blowing device mentioned above, it can also achieve the above functions using a gas compressor, a gas pressure regulating valve, a gas pipe, and a gas nozzle. The high-pressure gas supply device can supply high-pressure argon, helium, nitrogen, or air.

[0039] like Figure 1As shown, the laser-directed energy deposition system includes: a laser deposition head 1, a first optical fiber 2, a continuous laser 3, a first motion mechanism 4, and a powder feeder 6; The continuous laser 3 emits a continuous laser beam that is transmitted to the laser deposition head through the first optical fiber 2. The powder feeder 6 delivers the highly reflective metal material powder to a preset position in the deposition area. After collimation, the laser beam is focused onto the deposition area on the surface of the substrate 23 or the surface of the workpiece 24 with the highly reflective metal material. The highly reflective metal material and the highly reflective metal material powder in the deposition area are melted to form a molten pool and a deposition layer is formed in the deposition area. The first motion mechanism 4 is used to drive the laser deposition head 1 to move along a preset path and speed.

[0040] The continuous laser emitted by the continuous laser 3 is transmitted to the laser deposition head 1 through the first optical fiber 2. After collimation, it is focused onto the deposition area on the surface of the substrate 23 or the surface of the workpiece 24 with a highly reflective metallic material. The highly reflective metallic material and its powder in the deposition area are melted to form a molten pool. Through the melting and solidification process in the deposition area, a deposition layer is formed, completing the laser-directed energy deposition forming. After each layer is processed, the worktable 22 lowers the substrate and workpiece by the thickness of one deposition layer. The powder recovery machine 7 uses negative pressure to collect the unmelted powder through the negative pressure powder collection port 20 for recycling, and then proceeds to the next layer. During the processing, the camera 21 can acquire the morphology of the microstructure area and the morphology of the deposition layer formed by the laser deposition system. The main control unit 8 is equipped with control software, which is connected to the worktable 22, the laser-directed energy deposition system, and the water-guided laser processing system to coordinate the subsystems to complete the overall forming of the part.

[0041] In this embodiment, the powder material used is a highly reflective metal material. The powder material is used as the raw material for LDED forming. After the LDED deposits a layer of material, some unmelted powder will remain in the processing area. The powder is collected by a powder recycling machine for reuse after subsequent processing. After the powder is collected, the microstructure processing begins.

[0042] Furthermore, the water chiller 5 is connected to the laser deposition head 1 to cool the laser deposition head 1.

[0043] Preferably, the continuous laser 3 can emit a continuous power range of 500~20000W and a power density of 1.0×10⁻⁶. 5 ~1.5×10 5 W / cm 2 The continuous laser light is delivered to the laser deposition head via optical fiber.

[0044] Preferably, the first motion mechanism 4 can be a robotic arm or a multi-axis motion platform, etc. The first motion mechanism 4 and the second motion mechanism 14 can respectively drive the laser deposition head 1 and the water-guided laser processing head 15 to move in space, perform laser directional energy deposition processing and water-guided laser processing, and prevent the water-guided laser processing head 15 from interfering with the laser deposition head 1.

[0045] In another implementation, the powder material used is filament, and a filament feeding mechanism is used to transport the raw material filament to the laser-acting area. Using metal filament as the raw material for LDED forming, after the LDED deposits a layer of material, microstructure processing can be performed directly.

[0046] This invention employs a water-guided laser processing system to fabricate microstructures with a width of 30-100 μm, a depth of 50-300 μm, and an aspect ratio greater than or equal to 5:1 on the surface of the workpiece requiring energy deposition. Through multiple reflections and absorptions of the laser within the microstructures, the laser absorptivity is significantly improved, thereby increasing the efficiency of laser-directed energy deposition (LDED). Simultaneously, the deeper microstructures significantly reduce the thermal conductivity of the material surface, improving surface roughness and wettability. This invention solves the technical problems of low laser absorptivity, excessively rapid thermal conduction, and the resulting low melt pool temperature, poor wettability, and poor melt pool spreading in existing technologies. It achieves the beneficial effects of increasing laser absorptivity, reducing the thermal conductivity of the deposited material surface, improving the efficiency of laser-directed energy deposition, improving surface roughness and wettability, resulting in larger melt pool sizes and better melt pool spreading during laser-directed energy deposition, and improving the forming quality of high-reflectivity metals in LDED.

[0047] Example 2 like Figure 3 As shown, the present invention also provides a water-guided laser-assisted laser directional energy deposition method, comprising: S1. Based on the 3D CAD model of the workpiece, slice the workpiece and plan its path; S2. Based on the path planning results, a laser jet beam is generated by the water-guided laser processing system to process microstructures on the deposition area of ​​the substrate surface or the surface of the workpiece with highly reflective metal material. S3. Based on the path planning results, perform LDED shaping in the generated microstructure area, and deposit a highly reflective metallic material on the substrate surface using a laser directional energy deposition system to form a deposition layer in the deposition area. S4. The worktable lowers the substrate and workpiece by a distance equal to the thickness of a deposition layer. S5. Alternately control the laser-directed energy deposition system, the water-guided laser processing system, and the worktable to generate microstructures and deposit highly reflective metallic materials until the processing of the workpiece is completed.

[0048] Taking the 3D lettering component of the word "HUST" as an example, the specific process is as follows: S101. Based on the 3D CAD model of the part, the 3D part is sliced ​​into multiple layers, and each layer is partitioned to generate the water-guided laser processing path and code, and the laser directional energy deposition path and code for the area to be processed within each layer. For example... Figure 4 As shown in (a) in the figure.

[0049] S102. Based on the water-guided laser processing path and code generated in step S101, the main control unit 8 controls the water-guided laser processing system to start. At this time, the laser is transmitted through the water jet to form a laser jet beam 31, which acts on the surface of the substrate or part. Using predetermined process parameters and paths, the microstructure on the surface of the substrate 23 or the workpiece 24 is processed using water-guided laser processing technology to obtain the microstructure region 29, such as... Figure 4 As shown in (b); S103. After the first layer of water-guided laser processing of the microstructure is completed, the water jet and laser are turned off. The gas pressure regulating valve 11 is adjusted to increase the airflow pressure of the protective airflow, obtaining a high-pressure airflow 32. The high-pressure airflow 32 is used to dry the water stains 30 on the surface of the workpiece, preparing for LDED forming. Figure 4 As shown in (c); S104. The laser-directed energy deposition system is started, and laser-directed energy deposition is performed according to the laser-directed energy deposition path and process parameters generated in step S101, such as... Figure 4 As shown in (d); S105. After completing the laser-directed energy deposition (EDA) of the current layer, the stage 22 lowers the substrate 23 and the workpiece 24 by 0.3 mm, and the powder recovery machine is activated. Unmelted powder is collected through the negative pressure powder collection port 20 using negative pressure for recycling. Figure 4 (e) in the middle; S106. Repeat steps S102 to S105 until the final layer is formed, obtaining the processed part 24, as shown. Figure 4 (g) in the middle.

[0050] Throughout the processing, camera 21 captures surface morphology photos of the workpiece 24 during each layer of water-guided laser processing and after laser-directed energy deposition processing. The main control computer 8 then determines whether the next layer can be formed. Camera 21 can also collect surface morphology data to provide a basis for adjusting process parameters.

[0051] Furthermore, in this embodiment, the continuous laser 3 is a continuous fiber laser with an output laser wavelength of 1064nm and a maximum output power of 6000W.

[0052] Furthermore, the pulsed laser 12 in this embodiment is a nanosecond pulsed laser with an output laser wavelength of 1064nm, a maximum average power of 200W, a pulse frequency of 10-50kHz, and a maximum pulse energy of 10mJ.

[0053] Furthermore, the process parameters for water-guided laser processing are as follows: average laser power of 40W, pulse frequency of 20kHz, scanning speed of 50mm / s, scanning spacing of 0.06mm, water flow pressure of 5MPa, and the processed microstructure is a rectangular cross-section, parallel groove with a groove width of 50μm and a depth of 100μm. Furthermore, the parameters used for laser-directed energy deposition are: laser power of 6000W, scanning speed of 600mm / min, spot diameter of 1mm, powder feeding rate of 10g / min, and scanning spacing of 0.6mm.

[0054] Example 3 This embodiment uses laser-directed energy deposition (LDED) to manufacture AlSi10Mg aluminum alloy as an example, with the part being a large heat sink. The process includes the following steps: S201. Based on the 3D CAD model of the part, the 3D part is sliced ​​into multiple layers, and the path and code of the water-guided laser processing microstructure and the laser directional energy deposition path and code are generated for each layer.

[0055] S202. According to the water-guided laser processing path and code generated in step S201, the main control computer 8 controls the water-guided laser processing system to perform microstructure processing on the surface of the substrate 23 or the processing part 24 using predetermined process parameters. The microstructure is processed in the area where LDED forming is required, thereby improving the laser absorption rate, reducing the thermal conductivity, and enhancing the surface wettability of the area. S203. After the microstructure processing of this layer is completed, the laser jet beam of the water-guided laser system is turned off, and the control system controls the gas pressure regulating valve to increase the airflow pressure and speed to blow away the residual water stains on the workpiece and substrate surface, preparing for LDED forming.

[0056] S204. The laser-directed energy deposition system is started, and the LDED forming of this layer begins according to the laser-directed energy deposition path and process parameters generated in step S201.

[0057] S205. After completing the laser-directed energy deposition of the current layer, the worktable 22 lowers the substrate 23 and the workpiece 24 by 0.3mm.

[0058] S206. Repeat steps S202 to S205 until the last layer is formed.

[0059] Throughout the processing, camera 21 captures surface morphology photos of the workpiece 24 during each layer of water-guided laser processing and after laser-directed energy deposition processing. The main control computer 8 then determines whether the next layer can be formed. Camera 21 can also collect surface morphology data to provide a basis for adjusting process parameters.

[0060] Furthermore, in this embodiment, the continuous laser 3 is a continuous fiber laser with an output laser wavelength of 1064nm and a maximum output power of 10000W.

[0061] Furthermore, the pulsed laser 12 in this embodiment is a green nanosecond laser with an output laser wavelength of 532nm, a maximum average power of 40W, a pulse frequency of 10-50kHz, and a maximum pulse energy of 2mJ.

[0062] Furthermore, in this embodiment, the AlSi10Mg material used is a wire, which is fed to the laser-acting area by a wire feeding mechanism.

[0063] Furthermore, the process parameters for water-guided laser processing are as follows: average laser power of 30W, pulse frequency of 20kHz, scanning speed of 50mm / s, scanning interval of 0.06mm, water flow pressure of 10MPa, and the processed microstructure is a trapezoidal cross-section with intersecting grooves; the parameters for laser directional energy deposition are as follows: laser power of 6000W, scanning speed of 600mm / min, spot diameter of 1mm, wire feed rate of 0.1m / min, and scanning interval of 0.6mm.

[0064] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for water-guided laser-assisted laser directional energy deposition, characterized in that, include: Water-guided laser processing system, laser directional energy deposition system, worktable and control system; The water-guided laser processing system is used to generate a laser jet beam to process microstructures on the deposition area of ​​a substrate surface or a workpiece with a highly reflective metallic material; the microstructures are trenches or pits, with a width of 30-100 μm, a depth of 50-300 μm, and an aspect ratio greater than or equal to 5. The laser-directed energy deposition system is used to deposit highly reflective metallic materials on the surface of a substrate, form a deposition layer in the deposition area, and manufacture processed parts by a layer-by-layer deposition method; The worktable is used to lift and lower the workpiece by driving the substrate during the workpiece forming process; The control system is connected to the laser-directed energy deposition system, the water-guided laser processing system, and the worktable respectively, and is used to alternately control the connected components. The control system controls the water-guided laser processing system to perform water-guided laser processing on the substrate surface or the deposition layer area to generate microstructures. The control system controls the laser-directed energy deposition system to deposit a layer of highly reflective metal material on the substrate surface or the deposition layer area. The control system controls the worktable to descend by a distance equal to the thickness of the deposition layer after the laser-directed energy deposition system has deposited a layer of highly reflective metal material. The water-guided laser processing system includes: a pulsed laser, an optical path system, a water pump, a water supply pipeline, a water-guided laser processing head, and a second motion mechanism; The optical path system includes a beam expander and collimator and a focusing lens; The pulsed laser emits pulsed laser light, which is transmitted to the water-guided laser processing head through the optical path system; The water pump is connected to the water-guided laser processing head via the water supply pipe; The second motion mechanism is used to move the water-guided laser processing head to a designated position in space; The water-guided laser processing head generates a laser jet beam, which is transmitted to the deposition area on the substrate surface or the surface of the workpiece with highly reflective metal material to process and generate microstructures. The water-guided laser processing system also includes a high-pressure gas supply device; The high-pressure gas supply device includes a high-pressure gas cylinder, a gas pressure regulating valve, a gas delivery pipeline, and a gas nozzle; the gas nozzle is tightly fitted and positioned below the water-guided laser processing head; The high-pressure gas supply device is used to transport the gas from the high-pressure gas cylinder to the gas nozzle through the gas pipeline, and the gas protects the stable transmission of the laser jet beam when the water-guided laser processing head ejects the laser jet beam. The high-pressure air supply device is also used to dry the residual water stains on the surface of the workpiece with high-pressure airflow after the water-guided laser processing is completed.

2. The apparatus as claimed in claim 1, characterized in that, The laser-directed energy deposition system includes: a laser deposition head, a first optical fiber, a continuous laser, a first motion mechanism, and a powder feeder; The continuous laser emits a continuous laser beam that is transmitted through the first optical fiber to the laser deposition head. The powder feeder delivers the highly reflective metal material powder to a preset position in the deposition area. After collimation, the laser beam is focused onto the deposition area on the substrate surface or the surface of the workpiece with the highly reflective metal material. The highly reflective metal material and the highly reflective metal material powder in the deposition area are melted to form a molten pool. After solidification, a deposition layer is formed in the deposition area. The first motion mechanism is used to drive the laser deposition head to move along a preset path and speed.

3. The apparatus as described in claim 2, characterized in that, The laser-directed energy deposition system also includes a water chiller, a powder recovery machine, and a negative pressure powder collection port; The water chiller is connected to the laser deposition head and is used to cool the laser deposition head; The powder recovery machine is connected to a negative pressure powder collection port, which is located on one side of the substrate. The powder recovery machine is used to collect unmelted high-reflectivity metal powder through the negative pressure powder collection port.

4. The apparatus as claimed in claim 1, characterized in that, The pressure of the water flow supplied by the water pump to the water-guided laser processing head can be adjusted to obtain microstructures with different cross-sectional shapes.

5. The apparatus as claimed in claim 1, characterized in that, It also includes cameras; The camera is positioned directly above the substrate to acquire the morphology of the microstructure and the surface morphology of the processed part after each deposition by the laser-directed energy deposition system.

6. A method for water-guided laser-assisted laser-directed energy deposition, characterized in that, The apparatus for water-guided laser-assisted laser directional energy deposition as described in any one of claims 1-5 comprises: Based on the 3D CAD model of the workpiece, the workpiece is sliced ​​and a path is planned; Based on the path planning results, a laser jet beam is generated by a water-guided laser processing system to process microstructures on the deposition area of ​​the substrate surface or the surface of the workpiece with highly reflective metal material. Based on the path planning results, LDED shaping is performed in the generated microstructure region, and a highly reflective metallic material is deposited on the substrate surface using a laser directional energy deposition system to form a deposition layer in the deposition region. The worktable lowers the substrate and workpiece by a distance equal to the thickness of a deposition layer. Alternately control the laser-directed energy deposition system, the water-guided laser processing system, and the worktable to generate microstructures and deposit highly reflective metallic materials until the workpiece is completed.

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