Ultrafast-continuous double-beam green light synergistic powder bed additive manufacturing equipment

Abstract

The invention belongs to the technical field of 3D printing, and particularly relates to ultrafast-continuous double-beam green light synergetic powder bed additive manufacturing equipment. The ultrafast-continuous double-beam green light synergetic powder bed additive manufacturing equipment comprises a high-energy green light laser and an ultrafast pulse green light laser; the beam combiner is used for carrying out beam combination on the laser; a scanning galvanometer system; the anti-reflection protection structure is arranged on a light path in the scanning galvanometer system and comprises an anti-reflection coating and a light path isolation module; a forming cylinder; and a powder supply system. According to the scheme, two green laser beams are adopted for cooperative machining, so that efficient forming of high-reflection metal and active suppression of internal defects are achieved at the same time. The first beam of high-energy green laser is responsible for melting powder by utilizing the advantages of short wavelength and high material absorptivity, forming a stable molten pool and completing basic forming. And the following second beam of ultrafast green laser impacts a fused region which is not completely solidified in a pulse form, so that grains are effectively refined, microcracks are inhibited, holes are compacted, and in-situ modification of the microstructure of the material is realized.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, specifically relating to an ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment. Background Technology

[0002] In 3D metal printing technology, traditional equipment using high-energy infrared lasers faces inherent technical bottlenecks in the manufacturing of high-reflectivity metallic materials (such as copper, gold, and their alloys). Due to the extremely high laser reflectivity of these materials in the infrared band, energy absorption efficiency is low and molten pool stability is poor, making the forming process difficult and resulting in densely formed parts. To improve the laser absorption rate of high-reflectivity materials, existing technologies have employed high-energy green laser equipment or dual-laser forging printing technology combining infrared and green lasers. While these methods have improved forming feasibility to some extent, they have not completely solved the problem of microscopic defects during the melting and solidification process, such as microcracks, porosity, and incomplete fusion. These defects significantly reduce the mechanical properties and fatigue life of the parts, making it difficult to meet the stringent requirements for internal quality and reliability of parts in high-end equipment such as aerospace and precision instruments under extreme operating conditions. Therefore, to overcome the current quality bottlenecks in additive manufacturing of high-reflectivity alloys and achieve direct forming of high-performance, high-reliability workpieces, there is an urgent need to develop a new type of composite manufacturing equipment that can effectively suppress defects and improve density and performance.

[0003] The manufacturing of high-reflectivity metallic materials mainly faces the following technical bottlenecks and inherent defects: 1. Infrared laser energy absorption rate is extremely low: When traditional high-energy infrared lasers (such as 1064nm wavelength) process highly reflective metals such as gold, silver, and copper, the initial reflectivity of the material to the laser is usually over 90%. This results in most of the laser energy being reflected and unable to effectively couple into the powder, causing not only extremely low energy utilization, but more seriously, making it difficult to form a molten pool and resulting in poor stability. This leads to a large number of unfused defects in the formed parts, and even makes continuous forming difficult.

[0004] 2. Processing Efficiency and Thermal Management Challenges of Single Green Laser: While using high-energy green lasers can significantly improve the absorption rate of laser light by materials, achieving the high power density required for deep penetration welding with a single green laser source faces economic and technical challenges, including low electro-optical conversion efficiency, high equipment costs, and high power consumption. Furthermore, its concentrated heat input, if not properly controlled in process parameters, can easily lead to spatter, keyhole collapse, and spheroidization, introducing porosity and stress concentration within the material.

[0005] 3. Insufficient Cooperative Defect Control in Infrared-Green Dual Laser Systems: While existing infrared-green dual laser technology (forging printing) combines the efficient melting and solidification of infrared lasers with the high absorption characteristics of green lasers, the coordinated control of these two different wavelengths in terms of timing and space is still imperfect. This mismatch leads to insufficient and unstable impact strengthening of the molten pool, and fails to effectively eliminate micro-defects such as microcracks and shrinkage cavities generated during solidification. Consequently, the fatigue life and mechanical properties of the manufactured parts still cannot meet the stringent requirements for internal quality and reliability under extreme conditions such as aerospace.

[0006] Therefore, it is necessary to design an ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment. Summary of the Invention

[0007] To address the aforementioned problems in existing technologies, this solution provides an ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment.

[0008] The technical solution adopted in this invention is as follows: An ultrafast, continuous dual-beam green light synergistic powder bed additive manufacturing apparatus includes: The laser source includes a high-energy green laser and an ultrafast pulsed green laser; the high-energy green laser is used to emit continuous or long pulsed laser light, and the ultrafast pulsed green laser is used to emit ultrashort pulsed laser light. A beam combiner is placed on the light-emitting side of the laser source and is used to combine the laser beams emitted from a high-energy green laser and an ultrafast pulsed green laser. The scanning galvanometer system is located on the light-emitting side of the beam combiner and includes an X-axis galvanometer, a Y-axis galvanometer, and a field mirror. An anti-reflection protection structure is disposed in the optical path within the scanning galvanometer system and includes an anti-reflection coating and an optical path isolation module; the anti-reflection coating is disposed on the light-emitting side of both the X-axis galvanometer and the Y-axis galvanometer, and the optical path isolation module is disposed in the optical path of the ultrashort pulse laser and is used to absorb or deflect excess reflected light; The forming cylinder is located below the scanning galvanometer system; the light emitted from the scanning galvanometer system is directed towards the powder bed plane inside the forming cylinder. The powder supply system is located at the forming cylinder and is used to evenly spread a powder layer inside the forming cylinder.

[0009] Optional: It also includes a synchronization control unit, which is electrically connected to the laser source and the scanning galvanometer system to control the start and stop of the laser source and the deflection of the scanning galvanometer system.

[0010] Optionally: The synchronization control unit performs precise timing management of the laser source, first using a high-energy green laser to melt and solidify to form a molten pool, and then using an ultrafast pulsed green laser to impact and strengthen the molten pool.

[0011] Optional: The high-energy green laser emits a beam faster than the ultrafast pulsed green laser, and the time interval is Δt; when setting Δt, it should be ensured that the molten pool is in a high-temperature plastic state, but has not yet reached the critical stage of complete solidification.

[0012] Optional features: Powder layer particle size of 15-53μm, powder layer thickness of 30-80μm per layer; ultrafast laser parameters are generally between 5-70W, scanning speed of 500-8000mm / s; repetition rate of 10-100kHz.

[0013] Optionally: The motor controlling the deflection of the X-axis galvanometer and the motor controlling the deflection of the Y-axis galvanometer are electrically connected to the synchronization control unit, and the deflection angle of both is controlled by the synchronization control unit to drive the merged dual beams to move along a predetermined trajectory on the powder bed plane.

[0014] Optionally: An equipment main frame is provided above the forming cylinder, and the scanning galvanometer system is detachably mounted on the equipment main frame.

[0015] Optional: Field mirrors are provided on the light-emitting sides of both the X-axis and Y-axis galvanometers, and an anti-reflection coating is provided on the surface of each field mirror.

[0016] Optional: The anti-reflective coating is a high-reflective coating for the 532nm ultrafast green light wavelength.

[0017] Optional: The optical path isolation module is a Faraday isolator or an absorber.

[0018] The beneficial effects of this invention are as follows: 1. This scheme employs dual-beam green laser processing to simultaneously achieve efficient forming of highly reflective metals and active suppression of internal defects. The first high-energy green laser, utilizing its short wavelength and high material absorption rate, melts the powder, forming a stable molten pool and completing the basic forming. The subsequent second ultrafast green laser pulses impact the not-yet-fully-solidified molten zone, inducing high-intensity stress waves that effectively refine grains, suppress microcracks, and compact pores, achieving in-situ modification of the material's microstructure. Throughout the process, an intelligent synchronous control system ensures precise timing and spatial coordination between the two beams. Simultaneously, a dedicated anti-reflection optical path design isolates diffuse reflection from the ultrafast laser, guaranteeing the stability and reliability of the equipment under prolonged high-power processing, ultimately producing a dense, defect-free, high-performance metal component in one step.

[0019] 2. Compared with existing technologies, this invention fundamentally solves the problem of low energy coupling efficiency of high-reflectivity metals to infrared lasers by employing a dual green laser collaborative system, significantly improving the material absorption rate and ensuring stable melting and dense forming of high-reflectivity metals. Based on this, the system utilizes ultrafast green lasers to simultaneously impact-strengthen the melting zone, generating a forging effect through induced stress waves. This actively heals microcracks, eliminates porosity, and refines grains, thereby simultaneously improving the density and mechanical properties of the component during the forming process. Furthermore, the anti-reflection protection structure integrated into the scanning galvanometer system effectively blocks the diffuse reflection return path of the ultrafast laser, ensuring long-term stable operation of the equipment under high-power conditions. Through precise timing and spatial coordination of the dual beams by the synchronous control unit, a highly stable and repeatable "melting-strengthening" process is achieved, ultimately overcoming the bottleneck of traditional technologies that struggle to form or produce insufficient forming quality. This provides a novel manufacturing solution for aerospace and other fields, enabling the one-time forming of high-performance, high-reflectivity metal components. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this scheme or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0021] Figure 1 This is a schematic diagram of the powder bed additive manufacturing equipment with ultrafast-continuous dual-beam green light synergy in this scheme; Figure 2 This is a schematic diagram of an X-axis galvanometer; Figure 3 This is a schematic diagram of a Y-axis galvanometer.

[0022] In the diagram: 1-High-energy green laser; 2-Ultrafast pulsed green laser; 3-Beam combiner; 4-Scanning galvanometer system; 41-X-axis galvanometer; 43-Y-axis galvanometer; 43-Field mirror; 5-Synchronization control unit; 6-Shaping cylinder; 7-Powder supply system; 8-Main frame of equipment; 9-Anti-reflection coating; 10-Optical path isolation module; 11-Beam expander. Detailed Implementation

[0023] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only a part of the embodiments, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this solution without creative effort are within the protection scope of this solution.

[0024] Example like Figures 1 to 3As shown, this embodiment designs an ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment, including components such as a laser light source, a beam combiner 3, a beam expander 11, a scanning galvanometer system 4, a forming cylinder 6, a powder supply system 7, and a synchronous control unit 5.

[0025] The laser source includes a high-energy green laser 1 and an ultrafast pulsed green laser 2. The high-energy green laser 1 emits continuous or long-pulse laser light, while the ultrafast pulsed green laser 2 emits ultrashort-pulse laser light. This is achieved by combining green lasers of the same wavelength but different modes. Specifically, a combination of a continuous / long-pulse high-energy green laser 1 and a pulsed ultrafast green laser is employed. This is the foundation for achieving both "efficient melting and solidification" and "in-situ impact strengthening." Using dual lasers in the same green wavelength band (e.g., 532nm) solves the fundamental problem of low infrared laser absorption by highly reflective materials while avoiding the optical path complexity and collaborative control challenges associated with multiple wavelengths. This is the core physical carrier that distinguishes this solution from all existing technologies.

[0026] The beam combiner 3 is located on the light-emitting side of the laser source and is used to combine the lasers emitted from the high-energy green laser 1 and the ultrafast pulsed green laser 2.

[0027] The beam expander 11 is located on the light-emitting side of the beam combiner 3 and is used to expand the laser beam.

[0028] The scanning galvanometer system 4 is located on the light-emitting side of the beam expander 11 and also on the light-emitting side of the beam combiner 3. The scanning galvanometer system 4 includes an X-axis galvanometer 41, a Y-axis galvanometer, and a field mirror 43. The motors controlling the deflection of the X-axis galvanometer 41 and the motors controlling the deflection of the Y-axis galvanometer are electrically connected to the synchronization control unit 5, and the synchronization control unit 5 controls the deflection angle of both to drive the combined dual beams to move along a predetermined trajectory on the powder bed plane.

[0029] An anti-reflection protection structure is installed in the optical path of the scanning galvanometer system 4, and includes an anti-reflection coating 9 and an optical path isolation module 10. The anti-reflection coating 9 is installed on the light-emitting side of both the X-axis galvanometer 41 and the Y-axis galvanometer. Field mirrors 43 are installed on the light-emitting sides of both the X-axis galvanometer 41 and the Y-axis galvanometer, and each field mirror 43 has an anti-reflection coating 9 on its surface. The anti-reflection coating 9 is generally a high-reflection coating for the 532nm ultrafast green light wavelength. The optical path isolation module 10 is installed in the optical path of the ultrashort pulse laser and is used to absorb or deflect excess reflected light. The optical path isolation module 10 is generally a Faraday isolator or an absorber. This anti-reflection protection structure directly solves the technical bottleneck of laser damage caused by diffuse reflection in dual lasers, especially high-power ultrafast lasers, under "follower mode." It is crucial for ensuring that this equipment can achieve stable and reliable long-term high-power operation, and has extremely high engineering practical value and protective necessity.

[0030] The forming cylinder 6 is located below the scanning galvanometer system 4; the emitted light from the scanning galvanometer system 4 is directed towards the powder bed plane inside the forming cylinder 6. The powder supply system 7 is located at the forming cylinder 6 and is used to uniformly spread a powder layer inside the forming cylinder 6. The particle size of the powder layer is 15-53μm, and the thickness of one layer is 30-80 micrometers; the ultrafast laser parameters are generally between 5-70W, the scanning speed is 500-8000mm / s, and the repetition rate is 10-100kHz.

[0031] The synchronization control unit 5 is electrically connected to the laser source and the scanning galvanometer system 4 to control the start and stop of the laser source and the deflection of the scanning galvanometer system 4. The synchronization control unit 5 performs precise timing management of the laser source, first using a high-energy green laser 1 to form a molten pool, and then using an ultrafast pulsed green laser 2 to perform impact strengthening on the molten pool. Through the synchronization control unit 5, the emission timing, scanning path, and spatial following interval of the two laser beams are precisely set and controlled. This is the brain and nerve center for realizing the process concept of "immediate impact strengthening after melting and solidification." It ensures that the impact of the ultrafast laser can act on the molten zone, which is still in its optimal plastic state, directly guaranteeing the achievement of microstructure modification, elimination of internal defects (such as microcracks and porosity), and improvement of the mechanical properties of the parts.

[0032] The high-energy green laser 1 emits its beam faster than the ultrafast pulsed green laser 2, with a time interval of Δt. When setting Δt, it should be ensured that the molten pool is in a high-temperature plastic state, but has not yet completely solidified, at a critical stage. The selection of Δt is directly related to the thermophysical properties of the material (such as solidification rate and high-temperature plasticity window). The power and scanning speed of the molten beam determine the size, temperature, and duration of the molten pool, thus constraining the available Δt window. The pulse energy, pulse width, and repetition frequency of the impact beam must be matched with Δt to ensure sufficient impact energy is injected at the correct time, achieving effective grain refinement and defect repair. This temporal coordination ensures that the impact strengthening effect is precisely applied to the stage where the material's microstructure is most susceptible to plastic deformation and defect healing, which is key to improving the density and mechanical properties of the component. The parameter ranges and combinations can be further optimized experimentally and constitute an important part of the process claims.

[0033] for example: For metals with high thermal conductivity (such as pure copper): Δt is usually short, about 0.1 – 0.5 s. The melting beam has a high power (such as 800W) to overcome the high thermal conductivity and form a molten pool; the shock beam uses high energy and short pulse width (5-70W) to generate high-intensity stress waves.

[0034] For high-temperature alloys (such as Inconel 718): Δt can be appropriately extended to 0.5-1s. The melting beam uses medium power (such as 500W) to achieve a stable molten pool; the impact beam uses medium power and higher frequency (5-30W) for continuous micro-forging.

[0035] For titanium alloys (such as Ti-6Al-4V): the Δt range is usually 1-2s. The melting beam power is moderate (such as 400W); the shock beam uses lower power and higher repetition frequency (0-25W) to refine the grains.

[0036] An equipment main frame 8 is provided above the forming cylinder 6, and the scanning galvanometer system 4 is detachably mounted on the equipment main frame 8.

[0037] The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment employs an integrated "melting-impact" composite manufacturing process. First, high-energy green light is used to selectively melt and solidify the current powder layer. Then, within a specific time window before the material is fully solidified, ultrafast green light is used to scan and impact the same area. This method integrates the traditionally separate processes of "forming" and subsequent "modification" into a single manufacturing cycle, achieving a paradigm shift from "passively accepting defects" to "actively suppressing defects," representing a significant technological innovation for obtaining high-performance components.

[0038] Furthermore, the device in this embodiment possesses a high degree of modularity and compatibility, enabling its integration into existing manufacturing systems in various forms. In particular, it can be effectively integrated with mainstream selective laser melting (SLM) equipment to form a wide range of embodiments. The following are application examples of the device in this embodiment: Example 1. Modular add-on integration (for upgrading existing SLM equipment) This solution is suitable for upgrading the functionality of in-service infrared SLM equipment. The core is the integration of the green ultrafast laser shock strengthening module of this invention as an independent unit. This module includes an ultrafast green laser, an anti-reflection scanning mirror, and a synchronization controller, installed in a "bypass" configuration. During operation, after the original equipment's infrared melting laser completes each layer scan, the control system of this additional module receives the scanning path and trigger signal from the host, driving the ultrafast laser to synchronously shock strengthen the newly formed melting layer. This solution retains the original equipment's main body to the greatest extent possible; the main modifications are in the optical path interface and control signal connection, achieving low-cost functional expansion and performance improvement.

[0039] Example 2. Integrated Embedded Design (for New SLM Device Design) This solution is designed for new equipment development, integrating dual green lasers (high-energy continuous / long-pulse green laser + ultrafast pulse green laser), beam combining optical path, anti-reflection scanning system, and unified controller as core subsystems during the design phase. The optical paths of the two lasers are precisely coupled internally via a custom-designed beam combiner 3, and scanned by the same set of high-precision galvanometers. The synchronization control unit 5 is deeply integrated into the overall equipment control, enabling nanosecond-level coordinated control of the dual laser power, timing, and path. This approach achieves optimized optical path efficiency and spatial layout, representing the highest performance and most stable implementation.

[0040] Example 3. Multi-station hybrid manufacturing integration On more complex hybrid manufacturing platforms, this invention can be integrated as a standalone "laser shock annealing station" into multi-laser, multi-station systems. For example, in a flexible manufacturing unit comprising an infrared SLM station, an additive / subtractive manufacturing station, and the shock annealing station of this invention, parts can be transferred between different stations according to a program. Basic forming is first completed at the SLM station, and then the parts are automatically transferred to the shock annealing station for full-coverage or localized strengthening treatment. This separate integration provides significant process flexibility, especially suitable for large components or complex parts requiring localized strengthening.

[0041] All the above integration examples share the core anti-reflection optical path design and synchronous tracking control method in this embodiment, ensuring that the synergistic effect of "fusion-strengthening" can be stably achieved regardless of the hardware integration form used. This provides a complete and continuous technical path for upgrading existing equipment to new high-end equipment, greatly expanding the application scenarios and market coverage of this patented technology.

[0042] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation; it is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom remain within the scope of this technology.

Claims

1. A powder bed additive manufacturing device with ultrafast-continuous dual-beam green light synergy, characterized in that: include: The laser source includes a high-energy green laser (1) and an ultrafast pulsed green laser (2); the high-energy green laser (1) is used to emit continuous or long pulsed laser light, and the ultrafast pulsed green laser (2) is used to emit ultrashort pulsed laser light. A beam combiner (3) is set on the light-emitting side of the laser source and is used to combine the lasers emitted by the high-energy green laser (1) and the ultrafast pulsed green laser (2). The scanning galvanometer system (4) is located on the light-emitting side of the beam combiner (3) and includes an X-axis galvanometer (41), a Y-axis galvanometer and a field lens (43). An anti-reflection protection structure is set in the optical path of the scanning galvanometer system (4) and includes an anti-reflection coating (9) and an optical path isolation module (10); the anti-reflection coating (9) is provided on the light-emitting side of the X-axis galvanometer (41) and the Y-axis galvanometer, and the optical path isolation module (10) is set in the optical path of the ultrashort pulse laser and is used to absorb or deflect excess reflected light; The forming cylinder (6) is located below the scanning galvanometer system (4); the emitted light from the scanning galvanometer system (4) points towards the powder bed plane inside the forming cylinder (6); The powder supply system (7) is located at the forming cylinder (6) and is used to evenly spread the powder layer into the forming cylinder (6).

2. The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment according to claim 1, characterized in that: It also includes a synchronization control unit (5), which is electrically connected to the laser source and the scanning galvanometer system (4) to control the start and stop of the laser source and the deflection of the scanning galvanometer system (4).

3. The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment according to claim 2, characterized in that: The synchronous control unit (5) performs precise timing management of the laser source. First, a high-energy green laser (1) is used to melt and solidify the molten pool, and then an ultrafast pulsed green laser (2) is used to impact and strengthen the molten pool.

4. The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment according to claim 3, characterized in that: The high-energy green laser (1) emits a beam faster than the ultrafast pulsed green laser (2), and the time interval is Δt. When setting Δt, it should be ensured that the molten pool is in a high-temperature plastic state, but has not yet reached the critical stage of complete solidification.

5. The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment according to claim 4, characterized in that: The powder layer has a particle size of 15-53μm and a thickness of 30-80μm for one layer; the ultrafast laser parameters are generally between 5-70W, the scanning speed is 500-8000mm / s, and the repetition rate is 10-100kHz.

6. The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment according to claim 2, characterized in that: The motor controlling the deflection of the X-axis galvanometer (41) and the motor controlling the deflection of the Y-axis galvanometer are electrically connected to the synchronous control unit (5), and the deflection angle of the two is controlled by the synchronous control unit (5) to drive the merged double beam to move along a predetermined trajectory on the powder bed plane.

7. The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment according to claim 1, characterized in that: An equipment main frame (8) is provided above the forming cylinder (6), and the scanning galvanometer system (4) is detachably mounted on the equipment main frame (8).

8. The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment according to claim 1, characterized in that: Field mirrors (43) are provided on the light-emitting side of the X-axis galvanometer (41) and the light-emitting side of the Y-axis galvanometer, and an anti-reflection coating (9) is provided on the surface of each field mirror (43).

9. The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment according to claim 8, characterized in that: The anti-reflective coating (9) is a high-reflective coating for ultrafast green light wavelengths of 532nm.

10. The ultrafast-continuous dual-beam green light synergistic powder bed additive manufacturing equipment according to claim 1, characterized in that: The optical path isolation module (10) is a Faraday isolator or absorber.

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