WO2024012610A1 - 一种激光增材制造用系统及增材制造方法 - Google Patents

一种激光增材制造用系统及增材制造方法 Download PDF

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Publication number
WO2024012610A1
WO2024012610A1 PCT/CN2023/121951 CN2023121951W WO2024012610A1 WO 2024012610 A1 WO2024012610 A1 WO 2024012610A1 CN 2023121951 W CN2023121951 W CN 2023121951W WO 2024012610 A1 WO2024012610 A1 WO 2024012610A1
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Prior art keywords
laser
blue
additive manufacturing
laser generator
powder
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PCT/CN2023/121951
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English (en)
French (fr)
Inventor
常成
闫星辰
卢冰文
高硕洪
董东东
刘敏
杨军红
郑江鹏
孙涛
Original Assignee
广东省科学院新材料研究所
广东粤港澳大湾区硬科技创新研究院
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Publication of WO2024012610A1 publication Critical patent/WO2024012610A1/zh

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/34—Laser welding for purposes other than joining
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20—Direct sintering or melting
    • B22F10/25—Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20—Direct sintering or melting
    • B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
    • B22F12/40—Radiation means
    • B22F12/41—Radiation means characterised by the type, e.g. laser or electron beam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
    • B22F12/40—Radiation means
    • B22F12/44—Radiation means characterised by the configuration of the radiation means
    • B22F12/45—Two or more
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y10/00—Processes of additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the present invention relates to the technical field of additive manufacturing, and specifically, to a system for laser additive manufacturing and an additive manufacturing method.
  • Laser additive manufacturing (LAM) technology which uses high-energy laser beams as energy sources, is a new manufacturing technology based on the principle of layered manufacturing and uses the method of layer-by-layer accumulation of materials to directly manufacture digital models into physical parts.
  • ASTM American Society for Testing and Materials
  • Additive manufacturing is the process of connecting materials to make objects based on three-dimensional model data. Compared with subtractive manufacturing, it is usually a layer-by-layer process. .
  • Additive manufacturing technology integrates multiple disciplines such as digital technology, manufacturing technology, laser technology, and new material technology.
  • the materials used in laser additive manufacturing technology have covered titanium alloys, high-temperature alloys, iron-based alloys, aluminum alloys, refractory alloys, amorphous alloys, ceramics and gradient materials.
  • laser additive manufacturing technology is classified according to its forming principles. The most representative ones are selective laser melting (SLM), which is characterized by powder bed laying, and laser three-dimensional forming (Laser Three-dimensional Forming), which is characterized by synchronous powder feeding. solid forming) technology.
  • SLM selective laser melting
  • Laser Three-dimensional Forming Laser Three-dimensional Forming
  • the most commonly used one at this stage is still the near-infrared laser in the 960-1100nm band as the processing source, which results in high-reflectivity metals with low red light absorption rate (such as: Gold, silver, copper, aluminum) are difficult to melt and form well.
  • the present invention is proposed .
  • the purpose of the present invention is to provide a system and additive manufacturing method for laser additive manufacturing, which not only solves the problem that simple infrared laser requires extremely high energy density when processing high reflectivity materials, but also solves the problem of low output energy of blue light laser. , the problem of not being able to melt the material and molten pool well.
  • the present invention is implemented as follows:
  • the present invention provides a system for laser additive manufacturing, which is used to form a red and blue laser composite processing optical path, including an infrared laser generator, an infrared light collimating lens, a blue laser generator, a blue light collimating lens, a two-way
  • the color mirror and focusing lens, the infrared laser generator, the infrared light collimating lens, the dichroic mirror and the focusing lens are connected through the optical fiber in sequence, and the blue laser generator, the blue light collimating lens, the dichroic mirror and the focusing lens are connected through the optical fiber in sequence.
  • Optical fiber is used for optical path connection;
  • the side of the dichroic mirror facing the infrared laser generator is coated with an infrared light-transmitting coating, and the side facing the blue laser generator is coated with a blue light total reflection coating;
  • the optical path output part of the focusing lens is used for external galvanometer system or cladding gun head.
  • the dichroic mirror is tilted, and the angle between the dichroic mirror and the horizontal plane is 30-45 degrees;
  • the infrared laser generator is located above the dichroic mirror, and the blue laser generator is located on one side of the dichroic mirror.
  • the blue laser generator is a low-power blue laser with four gallium nitride pump sources, and the blue laser generator and the focusing lens are configured to excite a Gaussian beam with energy from the blue laser generator. Parallel beams, and the two beams overlap at the half-peak height of the Gaussian beam.
  • the output multiple blue parallel laser beams are converged at a focusing lens that is 10 to 45° to the incident axis, and the convergence result is 1/3 to 2/3 of the beam diameter (i.e., a single beam of light (half-peak width and height), energy superposition will occur, so that the incident central axis converges into a nearly circular spot or rectangular spot with a diameter of 1 to 1.5 times the diameter of the original single blue light beam, and the concentrated blue light beam completely falls in the infrared Inside the laser.
  • the infrared laser generator is a YAG fiber laser.
  • the optical fiber is a double-clad active optical fiber.
  • a control system is also included, and the control system is connected to the infrared laser generator and the blue laser generator.
  • the present invention provides an additive manufacturing method, using the laser additive manufacturing system in any one of the aforementioned embodiments to perform additive manufacturing.
  • the spot size of the infrared laser generator is 1.2 to 2 times the combined size of the four blue laser beams.
  • the infrared laser generator maintains a continuous light emitting state during the laser processing.
  • the blue laser generator is turned off. /Light emission frequency is 1-10HZ;
  • the power of the infrared laser generator is 3000- 6000W
  • the power of the blue laser generator is 300-1000W
  • the laser spot diameter of the blue laser generator is 1-2mm;
  • the power of the infrared laser generator is 500-1000W
  • the power of the blue-light laser generator is 50-100W
  • the laser spot diameter of the blue-light laser generator is 30-50 ⁇ m.
  • Optional implementations include:
  • the three-dimensional modeling software is selected from at least one of UG, Solidworks and CATIA;
  • the powder to be processed is selected from at least one of copper and aluminum;
  • the powder to be processed is spherical particles.
  • the particle size of the powder to be processed is 15-72 ⁇ m; when used in powder-feeding additive equipment, the particle size of the powder to be processed is 90 -150 ⁇ m;
  • the powder to be processed is dried before being poured into the powder storage bin; more preferably, it is dried by vacuum drying, with the drying temperature controlled to be 120-200°C and the vacuum degree being -0.080 ⁇ -0.1MPa.
  • the invention has the following beneficial effects: after the infrared laser emitted by the infrared laser generator and the blue light laser emitted by the blue light laser generator pass through the infrared light collimating lens and the blue light collimating lens respectively, they are focused by the focusing lens after passing through the dichroic mirror. Infrared lasers and blue lasers of different wavelengths are coupled, but only the energy at the terminal output part is recombined.
  • the overall optical path system is simple and easy to implement, has low cost and has wide applicability. In laser additive manufacturing systems such as powder feeding type and powder spreading type, All can be promoted well.
  • the infrared laser generator continues to emit light during operation, and the blue laser generator can be turned off/emit light with a lower frequency.
  • the pulsed laser uses a high-energy infrared laser to expand and maintain the shape and depth of the molten pool during the blue light turning-off process, ensuring that it can achieve effective melting and rapid forming while reducing the high energy consumption caused by the continuous output of blue light. It not only solves the problem that pure infrared laser requires extremely high energy density when processing high reflectivity materials, but also solves the problem that blue laser output energy is low and cannot melt the material and molten pool well.
  • Figure 1 is a schematic structural diagram of a system for laser additive manufacturing provided by an embodiment of the present invention
  • Figure 2 shows the laser energy distribution: (a) multiple small-sized blue lasers after recombination; (b) large-sized red lasers;
  • Figure 3 shows blue light/infrared laser pure copper additive manufacturing in Example 1: (a) surface after laser additive; (b) cross section after laser additive;
  • Figure 4 shows the additive manufacturing of 7075 aluminum alloy by blue/infrared laser in Example 2: (a) surface after laser additive; (b) cross section after laser additive;
  • Figure 5 shows the pure copper laser additive layer after processing in Example 3.
  • Figure 6 shows the laser additive layer of 7075 aluminum alloy after processing in Example 4.
  • Figure 7 shows Comparative Example 1 infrared laser additive nickel-based alloy coating on the surface of pure copper substrate
  • Figure 8 shows Comparative Example 2 blue laser additive 7075 aluminum alloy coating
  • Figure 9 shows the laser additive layer of 7075 aluminum alloy after processing in Comparative Example 3.
  • Figure 10 shows the pure copper laser additive layer after processing in Comparative Example 4.
  • Main component symbol description 001-infrared laser generator; 002-fiber; 0031-infrared light collimating lens; 0032-blue light collimating lens; 004-dichroic mirror; 005-blue light laser generator; 006-focusing lens.
  • an embodiment of the present invention provides a laser additive manufacturing system for forming a red and blue laser composite processing optical path, including an infrared laser generator 001, an infrared collimating lens 0031, a blue laser generator 005, and a blue laser
  • the collimating lens 0032, the dichroic mirror 004 and the focusing lens 006 couple the infrared laser and the blue laser of different wavelengths, but only recombine the energy at the terminal output part.
  • the infrared laser generator 001, the infrared collimating lens 0031, the dichroic mirror 004 and the focusing lens 006 are connected in turn through the optical fiber 002, and the blue laser generator 005, the blue light collimating lens 0032, the dichroic mirror 004
  • the optical path is connected to the focusing lens 006 through optical fibers in turn.
  • the side of the dichroic mirror 004 facing the infrared laser generator 001 is coated with an infrared light-transmitting coating to allow the infrared laser to pass through;
  • the side facing the blue laser generator 005 is coated with a blue light total reflection coating to allow the blue laser to reflect and Infrared laser coupling.
  • the overall optical path system is simple and easy to implement, has low cost and has wide applicability. It can be well promoted in laser additive manufacturing systems such as powder feeding type and powder spreading type.
  • the optical path output part of the focusing lens 006 is used to connect an external galvanometer system or a cladding gun head.
  • an external galvanometer system is selected, and for the powder-feeding additive system (LSF), an external galvanometer system is selected.
  • the external cladding gun head and other parts are common supporting systems for laser additive manufacturing systems.
  • the dichroic mirror 004 is tilted, and the angle between the dichroic mirror 004 and the horizontal plane is 30-45 degrees; the infrared laser generator 001 is located above the dichroic mirror 004, and the blue laser generator 005 Located on one side of dichroic mirror 004.
  • the alignment of the infrared laser generator 001 and the dichroic mirror 004, and the alignment of the blue laser generator 005 and the dichroic mirror 004 are both conventional methods.
  • the angle between the dichroic mirror 004 and the horizontal plane is controlled to be 30- 45 degrees is enough. Specifically, the angle between the dichroic mirror 004 and the horizontal plane may be 30 degrees, 35 degrees, 40 degrees, 45 degrees, etc.
  • the blue laser generator 005 is a low-power blue laser with four gallium nitride pump sources, and the blue laser generator 005 and the focusing lens 006 are configured to excite Gaussian energy from the blue laser generator 005
  • the higher energy density melts high-reflectivity materials while reducing the dilution rate and keyhole effect caused by the Gaussian beam, reducing the possibility of defects such as holes and cracks.
  • the following control method can be used to overlap the two beams at the half-peak height of the Gaussian beam: the output multiple blue parallel laser beams converge at a focusing lens that is 10 to 45° from the incident axis.
  • the result is that energy superposition will occur at 1/3 to 2/3 of the beam diameter (i.e., the half-peak width of a single beam of light), so that the incident central axis converges into a nearly 1 to 1.5 times the diameter of the original single blue light beam.
  • circular spot or rectangular spot, and make the concentrated blue light beam fall completely inside the infrared laser.
  • the 4-beam pulsed blue laser composite method proposed by the embodiment of the present invention not only does not require complicated coupling operations in the optical path system, but also obtains large processing size, high energy density and uniform distribution in the formable area.
  • Flat top laser This ensures that the high-reflectivity powder material to be processed can fully absorb the blue laser energy, causing it to melt quickly while reducing energy loss and reducing the damage caused by the blue laser to the optical fiber.
  • the infrared laser generator 001 can be, but is not limited to, a YAG fiber laser to improve its transmission in the optical fiber.
  • the transmission efficiency and beam quality are high, and the beam energy is Gaussian beam (TEM 00 ) to reduce manufacturing costs.
  • the optical fiber 002 can be, but is not limited to, a double-clad active optical fiber.
  • the use of a double-clad active optical fiber is beneficial to reducing the energy loss of the blue laser during transmission.
  • the good thermal conductivity system of optical fiber improves its heat dissipation efficiency and reduces the problem of fiber burning caused by excessive laser energy.
  • a control system is also included.
  • the control system is connected to the infrared laser generator 001 and the blue laser generator 005, and controls the operation of the infrared laser generator 001 and the blue laser generator 005 through an external control system.
  • Embodiments of the present invention provide an additive manufacturing method that uses the above-mentioned laser additive manufacturing system to perform additive manufacturing. By improving the red and blue laser composite processing optical path system, multi-mode laser energy distribution, laser processing efficiency and part molding are finally achieved. Improvements in quality and other aspects.
  • additive manufacturing methods include:
  • the powder to be processed is selected from at least one of copper and aluminum, which can be any one or more, suitable for the above-mentioned high reflectivity materials, and the powder purity is at least 99.0 wt.%.
  • the powder to be processed is spherical particles.
  • the particle size of the powder to be processed is 15-72 ⁇ m (15 ⁇ m, 20 ⁇ m, 40 ⁇ m, 60 ⁇ m, 72 ⁇ m, etc.); when used in powder-feeding additive equipment When in the equipment, the particle size of the powder to be processed is 90-150 ⁇ m (90 ⁇ m, 120 ⁇ m, 150 ⁇ m, etc.).
  • vacuum drying is used for drying, the drying temperature is controlled to be 120-200°C, and the vacuum degree is -0.080 ⁇ -0.1MPa.
  • the drying temperature can be 120°C, 150°C, 170°C, 200°C, etc.
  • the vacuum degree can be -0.080MPa, -0.090MPa, -0.1MPa, etc.
  • the drying time is not limited.
  • 0.5 is generally selected. -3h.
  • the scan path is created by converting the information in the three-dimensional model into multiple slices and defining each slice as a cross-sectional layer of the part before manufacturing the entity using the above method.
  • the three-dimensional modeling software is selected from at least one of UG, Solidworks, and CATIA, and can be any of the above professional modeling software.
  • the powder storage bin is filled with inert gas for protection.
  • the high-purity inert gas can be, but is not limited to, nitrogen, argon, etc., with a purity of 99.999 vol.%.
  • the inert gas used during molding and manufacturing can be, but is not limited to, nitrogen, argon, etc., with a purity of 99.999 vol.%.
  • the powder-laying laser additive manufacturing method is often named selective laser melting (SLM), selective laser sintering (SLS), Direct Metal Laser-Sintering (DMLS), Laser Powder Bed Fusion (LPBF), etc.; powder-fed laser additive manufacturing methods are often named laser metal cladding deposition technology (LMD, Laser Metal Deposition), laser near net shaping technology (LENS, Laser Engineered Net Shaping), laser three-dimensional Forming technology (LSF, Laser Solid Forming), etc.
  • SLM selective laser melting
  • SLS selective laser sintering
  • DMLS Direct Metal Laser-Sintering
  • LPBF Laser Powder Bed Fusion
  • powder-fed laser additive manufacturing methods are often named laser metal cladding deposition technology (LMD, Laser Metal Deposition), laser near net shaping technology (LENS, Laser Engineered Net Shaping), laser three-dimensional Forming technology (LSF, Laser Solid Forming), etc.
  • the inventor has optimized the parameters of infrared laser generator 001 and blue laser generator 005:
  • the spot size of the infrared laser generator 001 is 1.2 to 2 times (such as 1.2 times, 1.5 times, 1.8 times, 2.0 times, etc.) of the combined size of the four blue laser beams to ensure the focus of the blue laser. Falling completely into the infrared laser allows the formed molten pool to maintain a stable shape.
  • the infrared laser generator 001 will maintain a continuous light-emitting state during the laser processing process.
  • the infrared laser generator 001 will maintain a continuous light-emitting state during the laser processing process, while the blue laser generator will maintain a continuous light-emitting state.
  • 005 can selectively combine 2 or 4 beams of light.
  • the blue laser generator 005 is preferably a pulsed laser with a low off/out frequency.
  • the off/out frequency is preferably 1-10HZ, that is, blue light will be emitted before each unmelted material is processed to ensure that the high reflectivity material can fully absorb the blue light and melt completely.
  • a high-energy infrared laser will expand and maintain the melt pool. The shape and depth ensure that it can achieve effective melting and rapid forming while reducing the high energy consumption caused by continuous blue light output.
  • the power of the infrared laser generator 001 is 3000-6000W (such as 3000W, 4000W, 5000W, 6000W, etc.), and the blue laser generator
  • the power of 005 is 300-1000W (such as 300W, 500W, 700W, 1000W, etc.); the power of infrared laser generator 001 is higher to ensure that there is enough energy to fully melt high reflectivity materials; the blue laser generator 005 is a low-power , to ensure that there is enough energy to fully melt the high-reflectivity material, and at the same time, the volume of the blue laser will not be too large due to the required energy density being too high.
  • the laser spot diameter of the blue laser generator 005 is 1-2mm (such as 1.0mm, 1.5mm, 2.0mm, etc.), so that the blue laser generator 005 has better beam quality and focus spot under the set power to prevent Because blue light is in fiber optic Energy loss during propagation prevents the high reflectivity material from being fully melted.
  • the spot size of the infrared laser generator 001 is 1.2 to 2 times the combined size of the four blue laser beams, and is adjusted according to the laser spot diameter of the blue laser generator 005.
  • the power of the infrared laser generator 001 is 500-1000W (such as 500W, 700W, 1000W, etc.), and the blue laser generator 005
  • the power is 50-100W (such as 50W, 80W, 100W, etc.)
  • the laser spot diameter of the blue laser generator 005 is 30-50 ⁇ m (such as 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, etc.).
  • the power of the generator is matched with the diameter of the laser spot to ensure good beam quality and focus spot under the set power, and to prevent the inability to fully melt high-reflectivity materials due to the energy loss of blue light during fiber propagation.
  • This embodiment provides an additive manufacturing method, using the laser additive manufacturing system in Figure 1 to perform additive manufacturing, as follows:
  • this embodiment provides a system for laser additive manufacturing, including an infrared laser generator 001, an infrared collimating lens 0031, a blue laser generator 005, a blue collimating lens 0032, and a dichroic mirror. 004 and focusing lens 006.
  • Infrared laser generator 001, infrared light collimating lens 0031, dichroic mirror 004 and focusing lens 006 are connected through optical fiber 002 (double-clad active fiber) in turn, blue laser generator 005, blue light collimating lens 0032, Dichroic mirror 004
  • the optical path is connected to the focusing lens 006 through optical fibers (double-clad active optical fibers).
  • the angle between the dichroic mirror 004 and the horizontal plane is 40°.
  • the blue laser generator 005 is a low-power blue laser with 4 gallium nitride as the pump source.
  • the blue laser generator 005 and the focusing lens 006 are configured to receive the signal from the blue laser.
  • the generator 005 excites a parallel beam with an energy of Gaussian beam (TEM 00 ), and the two beams overlap at the half-peak height of the Gaussian beam.
  • TEM 00 energy of Gaussian beam
  • the side of the dichroic mirror 004 facing the infrared laser generator 001 is coated with an infrared transparent film, and the side facing the blue laser generator 005 is coated with a blue light total reflection film to ensure that both the infrared laser and the blue laser can be effectively focused by the cladding gun. header output.
  • Infrared laser generator 001 uses an infrared laser generator with a rated power of 6000W, a wavelength of 1064nm, an energy form of Gaussian beam (TEM 00 ), an energy density distribution as shown in Figure 2(a), and a focusing diameter of 4mm.
  • Blue-ray laser generator 005 uses four blue-ray laser generators with a rated power of 1000W. Among them, a single focusing diameter is 1.8mm and the energy form is Gaussian beam (TEM 00 ). The spot diameter of the four laser beams after combining is about is 2.3mm, the wavelength is 450nm, and the energy density distribution is shown in (b) in Figure 2.
  • Infrared laser generator 001 is connected to an external Nd: YAG (neodymium-doped yttrium aluminum garnet laser) pump source, and blue laser generator 005 is connected to a GaN (gallium nitride) pump source. Then, connect the infrared laser generator 001 and the blue laser generator 005 is connected to the external motor control system, and the final optical path output part, that is, the focusing lens 006 is connected to the cladding gun head.
  • Nd YAG (neodymium-doped yttrium aluminum garnet laser) pump source
  • GaN gallium nitride
  • Table 1 shows the absorption of light in different wavelength bands by different types of high reflectivity powder materials.
  • the absorption rate of the powder material for the combined infrared/blue laser is the highest, exceeding the absorption of the single waveband light by the powder material.
  • the infrared/blue laser composite processing proposed in this embodiment is used.
  • the system performs additive manufacturing of pure copper parts.
  • the pure copper additive manufacturing process performed on the surface of the copper substrate in Example 1 is as follows: the power of a single blue laser used is 650W, the light output/off frequency is 5HZ, the red laser power is 2000W, the scanning speed is 10mm/s, and the powder feeding speed is 1.5g/min.
  • Figure 3 shows the processed laser additive layer. Its surface quality is good and there are only a few holes in the cross section, indicating that the red and blue light composite processing proposed in this embodiment has good application prospects.
  • the 7075 aluminum alloy additive manufacturing process performed on the surface of the aluminum alloy substrate is as follows: the single blue laser power used is 850W, the light output/off frequency is 4HZ, the red laser power is 1500W, the scanning speed is 10mm/s, and the powder feeding speed is 1.5g. /min.
  • Figure 4 shows the processed 7075 aluminum alloy laser additive layer.
  • the surface quality of the single-pass deposition layer is good, with only a few holes in the cross section. Affected by the infrared laser Gaussian beam, the deposition layer is deep, ensuring the interface with the matrix.
  • the good combination solves the current problems of difficult aluminum alloy welding, poor fusion, and difficulty in additive manufacturing.
  • the pure copper additive manufacturing process performed on the surface of the copper substrate is as follows: the power of a single blue laser used is 700W, the light output/off frequency is 4HZ, the spot diameter after focusing the four beams is 2.88mm, the red laser power is 1200W, and the scanning The speed is 8mm/s, and the powder feeding speed is 2.5g/min.
  • Figure 5 shows the processed pure copper laser additive layer.
  • the surface quality after multi-layer cladding is good, with no obvious cracks or poor welding.
  • the 7075 aluminum alloy additive manufacturing process performed on the surface of the aluminum alloy substrate is as follows: the single blue laser power used is 750W, the light output/off frequency is 3HZ, the red laser power is 1800W, the scanning speed is 6mm/s, and the powder feeding speed is 2.1g. /min.
  • Figure 6 shows the processed 7075 aluminum alloy laser additive layer.
  • the single-layer deposition thickness can reach 0.3 ⁇ 0.5mm. There are no cracks or holes on the macro surface, and the molding quality is good.
  • Embodiment 1 The only difference from Embodiment 1 is that the blue laser generator 005 is turned off and only the infrared laser generator 001 is used.
  • the specific parameters used are: infrared laser power 2000W, scanning speed 5mm/s, and powder feeding speed 1.5g/min.
  • Figure 7 shows the laser-added Ni625/Ni60A layer after processing on the pure copper surface. Large-area cracks and holes appeared throughout the coating, and there were even cracks from the top of the coating to the substrate, indicating that only infrared laser was used to It is not suitable for laser additive processing on the surface of pure copper substrate.
  • Example 2 The only difference from Example 2 is that the infrared laser generator 001 is turned off, and only the blue laser generator 005 is used to perform laser additive 7075 aluminum alloy coating.
  • the specific parameters used are: blue laser power 750W, scanning speed 20mm/ s, powder feeding speed 1.5g/min.
  • Figure 8 shows the surface quality of the 7075 aluminum alloy and the internal defects of the coating after using only blue light additive. Although the visual inspection results of the surface quality of the processed aluminum alloy coating were acceptable, the metallographic inspection found that the coating was full of A large number of holes, indicating It is not suitable to only use blue light laser to perform laser additive processing on the surface of aluminum alloy substrate.
  • Example 1 The only difference from Example 1 is that the 7075 aluminum alloy additive manufacturing process performed on the surface of the aluminum alloy substrate is: the single blue laser power used is 350W, the light output/off frequency is 4HZ, and the red laser power is 1000W.
  • the scanning speed is 10mm/s and the powder feeding speed is 2.5g/min.
  • Figure 9 shows the processed 7075 aluminum alloy laser additive layer. Due to the low input energy and too fast scanning speed, obvious cracking occurred after depositing a single layer of 7075 aluminum alloy layer.
  • Example 1 The only difference from Example 1 is that the pure copper alloy additive manufacturing process performed on the surface of the copper alloy substrate is: the single blue laser power used is 11000W, the light output/off frequency is 4HZ, and the red laser power is 5100W.
  • the scanning speed is 6mm/s and the powder feeding speed is 2.5g/min.
  • Figure 10 shows the processed pure copper laser additive layer. Due to the input energy being too high and the scanning speed being too low, a large number of pores appeared after the pure copper layer was deposited, indicating that reasonable process selection is based on the material. Manufacturing results are very important.

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Abstract

一种激光增材制造用系统及增材制造方法，涉及增材制造技术领域。激光增材制造用系统包括红外激光发生器（001）、红外光准直透镜（0031）、蓝光激光发生器（005）、蓝光准直透镜（0032）、二向色镜（004）和聚焦透镜（006），其他部分均为激光增材制造系统的常见配套系统。采用多波长光束进行复合加工的思路，即采用多束低功率的脉冲式蓝光激光在焦点处进行合束处理以提高实际加工面积、激光输出的能量密度，在减少蓝光激光在光纤中的能量损失率、提升高反射材料对激光吸收率的同时，使用大光斑的红外激光对其熔池进行扩大和维持，以达到提高增材效率、降低能耗等目的。

Description

一种激光增材制造用系统及增材制造方法 技术领域：
本发明涉及增材制造技术领域，具体而言，涉及一种激光增材制造用系统及增材制造方法。
背景技术：
利用高能激光束作为能量源的激光增材制造技术(Laser additive manufacturing,LAM)是基于分层制造原理，采用材料逐层累加的方法，直接将数字化模型制造为实体零件的一种新型制造技术。美国材料与试验协会(ASTM)F42国际委员会给出了增材制造的定义：增材制造是依据三维模型数据将材料连接制作成物体的过程，相对于减法制造，它通常是逐层累加的过程。增材制造技术集成了数字化技术、制造技术、激光技术以及新材料技术等多个学科技术，可以直接将CAD数字模型快速而精密地制造成三维实体零件，实现真正的“自由制造”。与传统制造技术相比，增材制造技术具有柔性高、无模具、周期短、不受零件结构和材料限制等一系列优点，在航天航空、汽车、电子、医疗、军工等领域得到了广泛应用。
目前，激光增材制造技术所应用的材料已涵盖钛合金、高温合金、铁基合金、铝合金、难熔合金、非晶合金、陶瓷以及梯度材料等，在航空航天领域中高性能复杂构件和生物制造领域中多孔复杂结构制造具有显著优势。激光增材制造技术按照其成形原理进行分类，最具代表性的为以粉床铺粉为技术特征的激光选区熔化(Selective laser melting,SLM)和以同步送粉为技术特征的激光立体成形(Laser solid forming)技术。但不论是哪种激光增材制造技术，现阶段采用最多的仍是以960-1100nm波段的近红外激光做为加工源，这就导致对红光吸收率较低的高反射率金属(如：金、银、铜、铝)难以得到较好熔化及成形。
为解决该问题，在激光增材制造加工系统的构建方面提出了使用对激光吸收率较高的短波长(450nm)蓝光激光作为激光增材制造的能量源，但由于光纤对蓝光激光的吸收率高，导致其在经过光纤耦合后将会形成至少15％的能量损失且易烧毁光纤。现有技术也有采用蓝光/红光2种激光光路的方式集成了双波长激光，以通过振镜调节实现大尺寸红光预热，小尺寸蓝光精细加工的效果。但是红蓝激光在使用同一振镜进行光路调节时将避免不了对蓝光激光产生干涉，无法实现预期效果。并且，所产生的蓝色激光能量密度仍是以高斯模(TEM00)为主，无法降低激光增材过程中产生的匙孔效应，仍有较多气孔和裂纹的形成。
因此，为了解决高反射率金属材料对红外激光吸收率低导致的加工困难，蓝色激光在持续传输过程中对光纤的损伤问题，以及高斯单模激光容易产生的匙孔现象，特提出本发明。
发明内容：
本发明的目的在于提供一种激光增材制造用系统及增材制造方法，既解决了单纯的红外激光加工高反射率材料时需要极高能量密度的问题，同时也解决了蓝光激光输出能量低，无法使材料及熔池得到较好熔化的问题。
本发明是这样实现的：
第一方面，本发明提供一种激光增材制造用系统，用于形成红蓝激光复合加工光路，包括红外激光发生器、红外光准直透镜、蓝光激光发生器、蓝光准直透镜、二向色镜和聚焦透镜，红外激光发生器、红外光准直透镜、二向色镜和聚焦透镜依次通过光纤进行光路连接，蓝光激光发生器、蓝光准直透镜、二向色镜和聚焦透镜依次通过光纤进行光路连接；
二向色镜朝向红外激光发生器的一面镀有红外透光膜层，朝向蓝光激光发生器的一面镀有蓝光全反膜；
聚焦透镜的光路输出部分用于外接振镜系统或熔覆枪头。
在可选的实施方式中，二向色镜倾斜设置，且二向色镜与水平面的夹角为30-45度；
红外激光发生器位于二向色镜的上方，蓝光激光发生器位于二向色镜的一侧。
在可选的实施方式中，蓝光激光发生器为4个氮化镓作为泵浦源的低功率蓝光激光器，蓝光激光发生器和聚焦透镜被配置成从蓝光激光发生器激发出能量为高斯光束的平行光束，且两两光束间在高斯光束半峰高处进行重合。
在可选的实施方式中，输出的多束蓝色平行激光在与入射轴呈10～45°的聚焦透镜处发生汇聚，汇聚结果为光束直径的1/3～2/3(即单束光的半峰宽高处)将发生能量叠加，以使入射中轴处汇聚成1个原单束蓝光直径1～1.5倍的一个近圆形光斑或矩形光斑，并使汇聚的蓝光光束完全落在红外激光的内部。
在可选的实施方式中，红外激光发生器为YAG光纤激光器。
在可选的实施方式中，光纤为双包层有源光纤。
在可选的实施方式中，还包括控制系统，控制系统与红外激光发生器和蓝光激光发生器连接。
第二方面，本发明提供一种增材制造方法，利用前述实施方式中任一项的激光增材制造用系统进行增材制造。
在可选的实施方式中，红外激光发生器的光斑尺寸为4束蓝光激光合束后尺寸的1.2～2倍，红外激光发生器在激光加工过程中保持持续出光状态，蓝光激光发生器的关/出光频率为1-10HZ；
优选地，激光增材制造用系统用于送粉式增材设备中时，红外激光发生器的功率为3000- 6000W，蓝光激光发生器的功率为300-1000W；蓝光激光发生器的激光光斑直径为1-2mm；
优选地，激光增材制造用系统用于铺粉式增材设备中时，红外激光发生器的功率为500-1000W，蓝光激光发生器的功率为50-100W，蓝光激光发生器的激光光斑直径为30-50μm。
在可选的实施方式中，包括：
根据目标零件使用三维建模软件建立3D模型，将虚拟模型导入增材制造的控制系统中进行零件扫描路径的生成；
将待加工粉末倒入储粉仓中，等待高能激光束的增材制造成形；
在惰性气体的保护下，使用激光增材制造用系统对高反射率金属粉末进行所期望零件的成形制造；
优选地，三维建模软件选自UG、Solidworks和CATIA中的至少一种；
优选地，待加工粉末选自铜和铝中的至少一种；
优选地，待加工粉末为球形颗粒，用于铺粉式增材设备时，待加工粉末的粒径为15-72μm；用于送粉式增材设备中时，待加工粉末的粒径为90-150μm；
优选地，待加工粉末在倒入储粉仓之前进行干燥；更优选地，采用真空干燥的方式进行干燥，控制干燥温度为120-200℃，真空度为-0.080～-0.1MPa。
本发明具有以下有益效果：红外激光发生器发出的红外激光和蓝光激光发生器发出的蓝光激光分别经过红外光准直透镜和蓝光准直透镜后，经过二向色镜后利用聚焦透镜聚焦，将不同波长的红外激光和蓝光激光进行耦合，但是仅为终端输出部位的能量复合，整体光路系统简单易实现、成本低、适用性广，在送粉式和铺粉式等激光增材制造系统中都可以得到很好地推广。红外激光发生器在工作过程中持续出光，蓝光激光发生器可以为关/出光频率较低 的脉冲式激光，在蓝光关光过程中则由高能量的红外激光扩大并维持熔池的形状和深度，保证其可以实现有效熔化和快速成形的同时，降低持续输出蓝光带来的高能耗，既解决了单纯的红外激光加工高反射率材料时需要极高能量密度的问题，同时也解决了蓝光激光输出能量低，无法使材料及熔池得到较好熔化的问题。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，应当理解，以下附图仅示出了本发明的某些实施例，因此不应被看作是对范围的限定，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他相关的附图。
图1为本发明实施例提供的激光增材制造用系统结构示意图；
图2为激光能量分布：(a)复合后的多个小尺寸蓝光激光；(b)大尺寸红光激光；
图3为实施例1蓝光/红外激光纯铜增材制造：(a)激光增材后表面；(b)激光增材后截面；
图4为实施例2蓝光/红外激光7075铝合金增材制造：(a)激光增材后表面；(b)激光增材后截面；
图5为实施例3加工后的纯铜激光增材层；
图6为实施例4加工后的7075铝合金激光增材层；
图7为对比例1红外激光在纯铜基体表面增材镍基合金涂层；
图8为对比例2蓝光激光增材7075铝合金涂层；
图9为对比例3加工后的7075铝合金激光增材层；
图10为对比例4加工后的纯铜激光增材层。
主要元件符号说明：001-红外激光发生器；002-光纤；0031-红外光准直透镜；0032-蓝光准直透镜；004-二向色镜；005-蓝光激光发生器；006-聚焦透镜。
具体实施方式：
为使本发明实施例的目的、技术方案和优点更加清楚，下面将对本发明实施例中的技术方案进行清楚、完整地描述。实施例中未注明具体条件者，按照常规条件或制造商建议的条件进行。所用试剂或仪器未注明生产厂商者，均为可以通过市售购买获得的常规产品。
请参照图1，本发明实施例提供一种激光增材制造用系统，用于形成红蓝激光复合加工光路，包括红外激光发生器001、红外光准直透镜0031、蓝光激光发生器005、蓝光准直透镜0032、二向色镜004和聚焦透镜006，将不同波长的红外激光和蓝光激光进行耦合，但是仅为终端输出部位的能量复合。
具体地，红外激光发生器001、红外光准直透镜0031、二向色镜004和聚焦透镜006依次通过光纤002进行光路连接，蓝光激光发生器005、蓝光准直透镜0032、二向色镜004和聚焦透镜006依次通过光纤进行光路连接。二向色镜004朝向红外激光发生器001的一面镀有红外透光膜层，以使红外激光透过；朝向蓝光激光发生器005的一面镀有蓝光全反膜，以使蓝光激光都反射与红外激光耦合。为终端输出部位的能量复合，整体光路系统简单易实现、成本低、适用性广，在送粉式和铺粉式等激光增材制造系统中都可以得到很好地推广。
进一步地，聚焦透镜006的光路输出部分用于外接振镜系统或熔覆枪头，对于铺粉式增材系统(SLM)选择外接振镜系统，而对于送粉式增材系统(LSF)选择外接熔覆枪头，其他部分均为激光增材制造系统的常见配套系统。
在一些实施例中，二向色镜004倾斜设置，且二向色镜004与水平面的夹角为30-45度；红外激光发生器001位于二向色镜004的上方，蓝光激光发生器005位于二向色镜004的一侧。红外激光发生器001与二向色镜004的对齐方式，以及蓝光激光发生器005与二向色镜004的对齐方式，均为常规方式，控制二向色镜004与水平面的夹角为30-45度即可。具体地，二向色镜004与水平面的夹角可以为30度、35度、40度、45度等。
在一些实施例中，蓝光激光发生器005为4个氮化镓作为泵浦源的低功率蓝光激光器，蓝光激光发生器005和聚焦透镜006被配置成从蓝光激光发生器005激发出能量为高斯光束(TEM00)的平行光束，且两两光束间在高斯光束半峰高处进行重合，以便4束蓝光激光在经过聚焦透镜006合束后呈现近似平顶激光的能量密度分布，保证其以较高能量密度熔化高反射率材料的同时，降低了高斯光束带来的稀释率和匙孔效应，减少孔洞、裂纹等缺陷形成的可能。
在一些实施例中，两两光束间在高斯光束半峰高处进行重合可以采用如下控制手段：输出的多束蓝色平行激光在与入射轴呈10～45°的聚焦透镜处发生汇聚，汇聚结果为光束直径的1/3～2/3(即单束光的半峰宽高处)将发生能量叠加，以使入射中轴处汇聚成1个原单束蓝光直径1～1.5倍的一个近圆形光斑或矩形光斑，并使汇聚的蓝光光束完全落在红外激光的内部。
需要说明的是，本发明实施例提出的4束脉冲式蓝光激光复合方法不仅不需要在光路系统中进行繁复的耦合操作，而且在可成形区域得到加工尺寸大、能量密度高且分布均匀的近平顶激光。保证了待加工的高反射率粉体材料可充分吸收蓝光激光能量，使其快速熔化的同时，降低了能量损耗，减轻了蓝光激光对光纤的损害作用。
进一步地，红外激光发生器001可以但不限于YAG光纤激光器，以提升其在光纤中的传 导效率和光束质量，光束能量为高斯光束(TEM00)，以降低制造成本。
在一些实施例中，光纤002可以但不限于双包层有源光纤，采用双包层有源光纤，一方面有利于降低蓝光激光在传输过程中发生的能量损耗，另一方面通过双包层光纤良好的导热系统，提升了其散热效率，减少因激光能量过高而出现的光纤烧损问题。
在一些实施例中，还包括控制系统，控制系统与红外激光发生器001和蓝光激光发生器005连接，通过外置控制系统控制红外激光发生器001和蓝光激光发生器005工作。
本发明实施例提供一种增材制造方法，利用上述激光增材制造用系统进行增材制造，通过改进红蓝激光复合加工光路系统，以最终实现多模激光能量分布、激光加工效率及零件成型质量等多方面的提升。
具体而言，增材制造方法包括：
S1、待加工粉末前处理
将待加工粉末放入真空干燥箱中进行干燥，以去除粉末中的杂质，满足工艺要求。
在一些实施例中，待加工粉末选自铜和铝中的至少一种，可以为任意一种或几种，适合于上述高反射率材料，粉末纯度至少为99.0wt.％。
进一步地，待加工粉末为球形颗粒，用于铺粉式增材设备时，待加工粉末的粒径为15-72μm(15μm、20μm、40μm、60μm、72μm等)；用于送粉式增材设备中时，待加工粉末的粒径为90-150μm(90μm、120μm、150μm等)。
在一些实施例中，采用真空干燥的方式进行干燥，控制干燥温度为120-200℃，真空度为-0.080～-0.1MPa。具体地，干燥温度可以为120℃、150℃、170℃、200℃等，真空度为-0.080MPa、-0.090MPa、-0.1MPa等，干燥时间不限，根据所选择粉末，一般选择为0.5-3h。
S2、生成零件扫描路径
根据目标零件使用三维建模软件建立3D模型，将虚拟模型导入增材制造的控制系统中进行零件扫描路径的生成。具体地，扫描路径是通过将三维模型中的信息转换为多个切片，并将每个切片限定为所述零件的横截面层后采用上述方法制造实体。
在一些实施例中，三维建模软件选自UG、Solidworks和CATIA中的至少一种，可以为以上任意一种专业建模软件。
S3、成形制造
将待加工粉末倒入储粉仓中，等待高能激光束的增材制造成形；在惰性气体的保护下，使用激光增材制造用系统对高反射率金属粉末进行所期望零件的成形制造，具体的成形原理可以参照现有技术。
在一些实施例中，储粉仓是充满惰性气体进行保护的，高纯惰性气体可以但不限于为氮气、氩气等，纯度为99.999vol.％。成形制造时所使用的惰性气体可以但不限于氮气、氩气等，纯度为99.999vol.％。
需要说明的是，零件是通过激光增材制造的技术加工而成的，由于铺粉式、送粉式的激光增材制造系统在国内外的命名方法不同，涉及到以下激光增材制造的工艺均可使用本发明实施例的光路系统及制造方法，铺粉式激光增材制造方法常被命名为选择性激光熔化(Selective laser melting，SLM)、选择性激光烧结(Selective laser sintering，SLS)、直接金属激光烧结成型技术(Direct Metal Laser-Sintering，DMLS)、激光粉末床熔融成形(Laser Powder Bed Fusion，LPBF)等；送粉式的激光增材制造方法常被命名为激光金属熔覆沉积技术(LMD,Laser Metal Deposition)、激光近净成型技术(LENS,Laser Engineered Net Shaping)、激光立体 成形技术(LSF，Laser Solid Forming)等。
发明人对红外激光发生器001和蓝光激光发生器005的参数进行了优化：
在一些实施例中，红外激光发生器001的光斑尺寸为4束蓝光激光合束后尺寸的1.2～2倍(如1.2倍、1.5倍、1.8倍、2.0倍等)，以保证蓝光激光的焦点完全落在红外激光中，使得形成的熔池可以保持稳定形状。
为保证高反射率材料的充分熔化和高质量成形，红外激光发生器001在激光加工过程中保持持续出光状态，红外激光发生器001在激光加工过程中将保持持续出光状态，而蓝光激光发生器005可选择性的有2束光还是4束光进行复合。为降低能耗，提升蓝光激光发生器的质量及寿命，蓝光激光发生器005优选为关/出光频率较低的脉冲式激光，根据扫描速度的快慢和单道成形长度，关/出光频率优选为1-10HZ，即每加工到一次未熔材料前都会出蓝光，以保证高反射率材料可以充分吸收蓝光并完全熔化，而在蓝光关光过程中则由高能量的红外激光扩大并维持熔池的形状和深度，保证其可以实现有效熔化和快速成形的同时，降低持续输出蓝光带来的高能耗。
在一些实施例中，激光增材制造用系统用于送粉式增材设备中时，红外激光发生器001的功率为3000-6000W(如3000W、4000W、5000W、6000W等)，蓝光激光发生器005的功率为300-1000W(如300W、500W、700W、1000W等)；红外激光发生器001的功率较高，以保证有足够的能量充分熔化高反射率材料；蓝光激光发生器005是低功率，以保证有足够的能量充分熔化高反射率材料的同时，不会因为所需的能量密度过高导致蓝光激光器的体积过大。蓝光激光发生器005的激光光斑直径为1-2mm(如1.0mm、1.5mm、2.0mm等)，以使蓝光激光发生器005在所设定功率下具有较好的光束质量和焦点光斑，防止由于蓝光在光纤 传播过程中的能量损失而无法充分熔化高反射率材料。红外激光发生器001的光斑尺寸为4束蓝光激光合束后尺寸的1.2～2倍，根据蓝光激光发生器005的激光光斑直径进行调整。
在另外的实施例中，激光增材制造用系统用于铺粉式增材设备中时，红外激光发生器001的功率为500-1000W(如500W、700W、1000W等)，蓝光激光发生器005的功率为50-100W(如50W、80W、100W等)，蓝光激光发生器005的激光光斑直径为30-50μm(如30μm、40μm、50μm等)。利用发生器的功率和激光光斑直径配合，以保证在所设定功率下具有较好的光束质量和焦点光斑，防止由于蓝光在光纤传播过程中的能量损失而无法充分熔化高反射率材料。
需要补充的是，无论是送粉式增材设备还是铺粉式增材设备，都是采用大功率大尺寸的红外激光在蓝光激光将高反射率材料充分熔化后，发挥出了扩大熔池，稳定熔池形貌的作用。既解决了单纯的红外激光加工高反射率材料时需要的极高能量密度，同时也解决了蓝光激光输出能量低，无法使材料及熔池得到较好熔化的窘境，扩大了激光增材制造系统的使用范畴。
以下结合实施例对本发明的特征和性能作进一步的详细描述。
实施例1
本实施例提供一种增材制造方法，利用图1中的激光增材制造用系统进行增材制造，具体如下：
如图1所示，本实施例提供的一种激光增材制造用系统，包括红外激光发生器001、红外光准直透镜0031、蓝光激光发生器005、蓝光准直透镜0032、二向色镜004和聚焦透镜006。红外激光发生器001、红外光准直透镜0031、二向色镜004和聚焦透镜006依次通过光纤002(双包层有源光纤)进行光路连接，蓝光激光发生器005、蓝光准直透镜0032、二向色镜004 和聚焦透镜006依次通过光纤(双包层有源光纤)进行光路连接。
二向色镜004与水平面的夹角为40°，蓝光激光发生器005为4个氮化镓作为泵浦源的低功率蓝光激光器，蓝光激光发生器005和聚焦透镜006被配置成从蓝光激光发生器005激发出能量为高斯光束(TEM00)的平行光束，且两两光束间在高斯光束半峰高处进行重合。二向色镜004朝向红外激光发生器001一面镀有红外透光膜层，朝向蓝光激光发生器005一面镀有蓝光全反膜，保证红外激光和蓝光激光都可以在有效聚焦后被熔覆枪头输出。
红外激光发生器001使用的是额定功率6000W，波长1064nm，能量形式为高斯光束(TEM00)，能量密度分布如图2中(a)所示，聚焦直径为4mm的红外激光发生器。
蓝光激光发生器005使用的是4个额定功率为1000W，其中，单个聚焦直径为1.8mm，能量形式为高斯光束(TEM00)的蓝光激光发生器，4束激光在合束后的光斑直径约为2.3mm，波长为450nm，能量密度分布如图2中(b)所示。
红外激光发生器001外接Nd：YAG(掺钕钇铝石榴石激光器)泵浦源，蓝光激光发生器005外接GaN(氮化镓)泵浦源，之后将红外激光发生器001和蓝光激光发生器005与外接电机控制系统进行连结，最终的光路输出部分，即聚焦透镜006与熔覆枪头进行连结。本实施例未提及的操作步骤可以参照上述说明书的内容。
表1显示了不同种高反射率粉末材料对不同波段光的吸收情况。
表1.多种高反射率材料在不同波段照射下的吸收率

可以看出，粉末材料对红外/蓝光激光复合后的吸收率是最高的，均都超过了粉体材料对单种波段光的吸收情况，之后，采用本实施例提出的红外/蓝光激光复合加工系统进行纯铜件的增材制造。
实施例1中在铜基板表面进行的纯铜增材制造工艺为：使用的单个蓝光激光功率为650W，出/关光频率为5HZ，红光激光功率2000W，扫描速度10mm/s，送粉速度1.5g/min。
图3展示了加工后的激光增材层，其表面质量良好，截面中仅有少量孔洞，表明使用本实施例提出的红蓝光复合加工具有良好的应用前景。
实施例2
采用与实施例1相同的光路系统，不同之处在于以下参数控制：
在铝合金基板表面进行的7075铝合金增材制造工艺为：使用的单个蓝光激光功率为850W，出/关光频率为4HZ，红光激光功率1500W，扫描速度10mm/s，送粉速度1.5g/min。
图4展示了加工后的7075铝合金激光增材层，其单道沉积层表面质量良好，截面中仅有少量孔洞，受到红外激光高斯光束的影响，沉积层较深，保证了与基体界面的良好结合，很好地解决了铝合金焊接难、熔合差、增材不易等现状。
实施例3
采用与实施例1相同的光路系统，不同之处在于以下参数控制：
在铜基板表面进行的纯铜增材制造工艺为：使用的单个蓝光激光功率为700W，出/关光频率为4HZ，4束光聚焦后的光斑直径为2.88mm，红光激光功率1200W，扫描速度8mm/s，送粉速度2.5g/min。
图5展示了加工后的纯铜激光增材层，多层熔覆后的表面质量良好，无明显裂纹或焊合不好等问题。
实施例4
采用与实施例1相同的光路系统，不同之处在于以下参数控制：
在铝合金基板表面进行的7075铝合金增材制造工艺为：使用的单个蓝光激光功率为750W，出/关光频率为3HZ，红光激光功率1800W，扫描速度6mm/s，送粉速度2.1g/min。
图6展示了加工后的7075铝合金激光增材层，单层沉积厚度可达0.3～0.5mm，宏观表面无裂纹、孔洞，成型质量较好。
对比例1
与实施例1不同之处仅在于：关闭蓝光激光发生器005，仅采用红外激光发生器001，使用的具体参数为：红外激光功率2000W，扫描速度5mm/s，送粉速度1.5g/min。
图7展示了在纯铜表面加工后的激光增材Ni625/Ni60A层，涂层整体出现了大面积裂纹和孔洞，甚至有裂纹会从涂层顶部一直裂到基体处，表明仅采用红外激光在纯铜基体表面进行激光增材是不合适的。
对比例2
与实施例2不同之处仅在于：关闭红外激光发生器001，仅采用蓝光激光发生器005，进行激光增材7075铝合金涂层，使用的具体参数为：蓝光激光功率750W，扫描速度20mm/s，送粉速度1.5g/min。
图8展示了仅使用蓝光增材后的7075铝合金表面质量及涂层内部缺陷情况，尽管加工后的铝合金涂层表面质量目视检测结果尚可，但通过金相检测发现涂层中充满大量孔洞，表明 仅采用蓝光激光在铝合金基体表面进行激光增材是不合适的。
对比例3
与实施例1的不同之处仅在于：在铝合金基板表面进行的7075铝合金增材制造工艺为：使用的单个蓝光激光功率为350W，出/关光频率为4HZ，红光激光功率1000W，扫描速度10mm/s，送粉速度2.5g/min。
图9展示了加工后的7075铝合金激光增材层，由于所输入的能量较低、扫描速度过快，导致沉积单层7075铝合金层后出现了明显开裂现象。
对比例4
与实施例1的不同之处仅在于：在铜合金基板表面进行的纯铜合金增材制造工艺为：使用的单个蓝光激光功率为11000W，出/关光频率为4HZ，红光激光功率5100W，扫描速度6mm/s，送粉速度2.5g/min。
图10展示了加工后的纯铜激光增材层，由于所输入的能量过高、扫描速度过低，导致沉积纯铜层后出现了大量的气孔，表明根据材料进行合理的工艺选择对增材制造结果是十分重要的。
以上仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种激光增材制造用系统，用于形成红蓝激光复合加工光路，其特征在于，包括红外激光发生器、红外光准直透镜、蓝光激光发生器、蓝光准直透镜、二向色镜和聚焦透镜，所述红外激光发生器、所述红外光准直透镜、所述二向色镜和所述聚焦透镜依次通过光纤进行光路连接，所述蓝光激光发生器、所述蓝光准直透镜、所述二向色镜和所述聚焦透镜依次通过光纤进行光路连接；
    所述二向色镜朝向所述红外激光发生器的一面镀有红外透光膜层，朝向所述蓝光激光发生器的一面镀有蓝光全反膜；
    所述聚焦透镜的光路输出部分用于外接振镜系统或熔覆枪头。
  2. 根据权利要求1所述的激光增材制造用系统，其特征在于，所述二向色镜倾斜设置，且所述二向色镜与水平面的夹角为30-45度；
    所述红外激光发生器位于所述二向色镜的上方，所述蓝光激光发生器位于所述二向色镜的一侧。
  3. 根据权利要求2所述的激光增材制造用系统，其特征在于，所述蓝光激光发生器为4个氮化镓作为泵浦源的低功率蓝光激光器，所述蓝光激光发生器和所述聚焦透镜被配置成从所述蓝光激光发生器激发出能量为高斯光束的平行光束，且两两光束间在高斯光束半峰高处进行重合。
  4. 根据权利要求3所述的激光增材制造用系统，其特征在于，输出的多束蓝色平行激光在与入射轴呈10～45°的聚焦透镜处发生汇聚，汇聚结果为光束直径的1/3～2/3将发生能量叠加，以使入射中轴处汇聚成1个原单束蓝光直径1～1.5倍的一个近圆形光斑或矩形光斑，并使汇 聚的蓝光光束完全落在红外激光的内部。
  5. 根据权利要求1-4中任一项所述的激光增材制造用系统，其特征在于，所述红外激光发生器为YAG光纤激光器。
  6. 根据权利要求5所述的激光增材制造用系统，其特征在于，所述光纤为双包层有源光纤。
  7. 根据权利要求5所述的激光增材制造用系统，其特征在于，还包括控制系统，所述控制系统与所述红外激光发生器和所述蓝光激光发生器连接。
  8. 一种增材制造方法，其特征在于，利用权利要求1-7中任一项所述的激光增材制造用系统进行增材制造。
  9. 根据权利要求8所述的增材制造方法，其特征在于，所述红外激光发生器的光斑尺寸为4束蓝光激光合束后尺寸的1.2～2倍，所述红外激光发生器在激光加工过程中保持持续出光状态，所述蓝光激光发生器的关/出光频率为1-10HZ；
    优选地，所述激光增材制造用系统用于送粉式增材设备中时，所述红外激光发生器的功率为3000-6000W，所述蓝光激光发生器的功率为300-1000W；所述蓝光激光发生器的激光光斑直径为1-2mm；
    优选地，所述激光增材制造用系统用于铺粉式增材设备中时，所述红外激光发生器的功率为500-1000W，所述蓝光激光发生器的功率为50-100W，所述蓝光激光发生器的激光光斑直径为30-50μm。
  10. 根据权利要求9所述的增材制造方法，其特征在于，包括：
    根据目标零件使用三维建模软件建立3D模型，将虚拟模型导入增材制造的控制系统中进行零件扫描路径的生成；
    将待加工粉末倒入储粉仓中，等待高能激光束的增材制造成形；
    在惰性气体的保护下，使用所述激光增材制造用系统对高反射率金属粉末进行所期望零件的成形制造；
    优选地，所述三维建模软件选自UG、Solidworks和CATIA中的至少一种；
    优选地，所述待加工粉末选自铜和铝中的至少一种；
    优选地，所述待加工粉末为球形颗粒，用于铺粉式增材设备时，所述待加工粉末的粒径为15-72μm；用于送粉式增材设备中时，所述待加工粉末的粒径为90-150μm；
    优选地，待加工粉末在倒入储粉仓之前进行干燥；更优选地，采用真空干燥的方式进行干燥，控制干燥温度为120-200℃，真空度为-0.080～-0.1MPa。
PCT/CN2023/121951 2023-02-20 2023-09-27 一种激光增材制造用系统及增材制造方法 WO2024012610A1 (zh)

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