Rotary multi-beam additive manufacturing device based on short-wavelength composite laser

Abstract

The invention discloses a rotary multi-beam additive manufacturing device based on short-wavelength composite laser, and belongs to the field of laser additive manufacturing. The device comprises a blue light system, a green light system, a red light system, a rotating wheel disc system, a macroscopic morphology real-time monitoring system, a powder feeding device and a master control system. The blue light system generates a central Gaussian light spot, and the green light system is driven by a rotating wheel disc to rotate around a blue light optical axis to form an annular light spot, so that double-beam combined processing is realized; the red light system has the in-situ heat treatment function and the CCD monitoring function, and can regulate and control organization in real time and collect processing information. A material database is arranged in the master control system, and multi-laser parameters can be intelligently regulated and controlled according to workpiece materials. The method effectively solves the problem that high-reflection metal such as copper and aluminum is low in traditional infrared laser absorptivity, has the advantages of being controllable in energy distribution, good in machining stability, high in intelligent degree and the like, and is particularly suitable for high-performance additive manufacturing of the high-reflection metal.

Description

Technical Field

[0001] This invention relates to the field of laser additive manufacturing technology, and in particular to a rotating multibeam additive manufacturing device based on short-wavelength composite laser, which enables effective additive manufacturing of metals such as copper and aluminum that have high reflectivity to near-infrared lasers. Background Technology

[0002] Laser additive manufacturing technology is currently attracting much attention in the field of precision equipment manufacturing. However, copper, aluminum, and their alloys have an absorption rate of less than 5% for the mainstream 1070nm near-infrared laser used in industry, requiring a power of more than 3kW to initiate melting, and also resulting in significant spatter and a high risk of reflection damage. In contrast, copper's absorption rate for 450nm blue light increases to approximately 65%, reducing the melting threshold by 80%, and enabling the achievement of a stable molten pool at a power level of 1kW. Therefore, it has become the preferred light source for high-reflectivity metal additive manufacturing.

[0003] However, when using blue light as a single light source, the following problems exist:

[0004] (1) Uniform energy distribution: For commonly used Gaussian blue light sources, the energy density at the center is high, while the energy density at the edge is too low. During processing, the center is prone to burn-through and the edge is not fused, resulting in poor metallurgical bonding.

[0005] (2) Rapid temperature change rate: The characteristics of a single blue light point heat source result in highly concentrated heat input, causing the molten pool and its heat-affected zone to experience extremely rapid heating and cooling rates. This intense thermal cycle can easily introduce large residual stresses into the formed parts, increasing the risk of component deformation and cracking.

[0006] Currently, red-blue composite light is commonly used as a laser source. Blue light is responsible for initiating melting, while red light is responsible for deep melting, which then creates a keyhole, thereby increasing the absorption rate of the light source by the highly reflective metal. However, the absorption difference between red and blue light is as high as 60%, the temperature gradient from the center to the edge of the molten pool is steep, and the number of spatter particles is an order of magnitude higher than that of single infrared light. Moreover, infrared light requires more than 3kW of power, and the equipment cost and the risk of reflection damage remain prominent.

[0007] For blue-green light, firstly, both are short-wavelength light sources. During the combination, due to their similar wavelengths, the difference in copper's absorption rate is small, resulting in a decrease in the molten pool temperature gradient. Defects such as cold lips or incomplete fusion can be suppressed without additional beam shaping devices. Secondly, compared to near-infrared light, the absorption of short-wavelength lasers is less sensitive to surface conditions, making the processing more stable. As independently controllable light sources that can be efficiently absorbed, blue and green light form a smoother composite thermal field energy density, effectively stabilizing the molten pool and reducing spatter. Furthermore, the high-speed rotation of green light around blue light introduces tangential Marangoni convection on the molten pool surface, which stirs the molten pool, helps promote the formation of equiaxed crystals, accelerates bubble escape, and makes the element distribution more uniform. Finally, 3kW-level continuous green light sources are already commercially available, with a unit price comparable to blue light. Compared to red light, they have lower reflected energy and a lower probability of damage to optical devices.

[0008] Based on this, the present invention provides a rotating multi-beam additive manufacturing apparatus based on short-wavelength composite lasers. This apparatus includes a rotating device, a laser system, and an infrared laser heat treatment device. It integrates the absorption advantages of short-wavelength lasers and, for different materials to be processed, can adjust the ratio between light sources by accessing a database, effectively combining blue and green light sources to improve the quality of the laser source and thus enhance the performance of the welded parts. Furthermore, the addition of the infrared heat treatment device allows for in-situ heat treatment of the additive manufacturing area after additive manufacturing to regulate its microstructure and further improve its performance. This invention enables novel composite laser processing with flexible energy field control and intelligent process monitoring, bringing a technological breakthrough to the field of laser processing of highly reflective metals. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a rotating multibeam additive manufacturing device based on short-wavelength composite lasers to solve problems such as inflexible energy distribution control, low processing efficiency of high-reflectivity materials, and lack of intelligent monitoring throughout the entire process in traditional laser processing.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A rotating multibeam additive manufacturing apparatus based on short-wavelength composite lasers is characterized by comprising a blue-green light composite system, a rotating disk system, a red light system, a real-time macroscopic morphology monitoring system, and a central control system and information acquisition system. Wherein:

[0012] In the blue-green composite system, the blue light system is fixedly installed and is used to generate and output a blue Gaussian beam as the central spot. Its core components include a blue laser emitter (11) and a blue light tube (12). The tube is equipped with a laser collimating lens (121) and a plane lens (123) to generate a high-quality blue light beam. The green light system is installed on a driven rotating disk and is used to generate and output a green light beam. Its structure is similar to that of the blue light system, including a green laser emitter (21) and a green light tube (22) with built-in collimation (221) and plane lens (223). The rotating disk (8) drives the green light system to rotate around the optical axis of the blue light system, so that the green light beam (222) surrounds the blue central Gaussian beam (122) and forms a uniform ring spot through the focusing lens (4), realizing the composite energy field distribution of the center and the ring.

[0013] The rotating disk system (8) includes an active rotating disk (81) and a driven rotating disk (82) whose rotation trajectory is fixed by embedding. The motor drives the active rotating disk (81) to rotate, which in turn drives the driven rotating disk (82) to rotate around the central axis of the blue light tube. The rotation speed is adjusted by the control system to regulate the formation quality of the annular light spot.

[0014] The red light system is an innovative design with multiplexed optical paths, integrating heat treatment and monitoring functions. It includes a red laser emitter (31) and a red light-CCD recording composite device (32). This composite device not only has a lens group for red laser collimation (321) and focusing (324), but also integrates a single-sided transparent mirror (323), a reflector (328), and a CCD camera (325). The red laser (322) can perform in-situ heat treatment on the molten pool or the completed area to control the microstructure. At the same time, the reflected light signal (327) from the processing area (such as molten pool radiation and thermal radiation) is received by the CCD through the same optical path, realizing real-time monitoring of the processing status;

[0015] The macroscopic morphology real-time monitoring system (6) is independent of the red light system and is mainly used to monitor the contour and morphology of the additive parts from a macroscopic scale.

[0016] The overall control system and information acquisition system (9) is the brain of the entire device. It is electrically connected to all subsystems and sensors and has a rich database of material processing parameters. This system is responsible for controlling the power, frequency, red light heat treatment parameters, and rotation speed of each laser, and receives data from the CCD and monitoring system. Through algorithm processing, it realizes real-time feedback and closed-loop intelligent control of the processing process.

[0017] The rotating multibeam additive manufacturing device based on short-wavelength composite laser is characterized in that the blue-green composite system consists of two parts: the blue system (1) includes a blue laser emitter (11) and a blue laser tube (12), wherein a laser collimating lens (121) and a plane lens (123) are arranged sequentially along the optical path inside the blue laser tube (12) to focus the blue laser beam to form a high-energy-density Gaussian spot, so as to realize the rapid melting and keyhole formation of the metal powder to be processed; the green system (2) includes a green laser emitter (21) and a green laser tube (22), wherein a laser collimating lens (221) and a plane lens (223) are arranged sequentially along the optical path inside the green laser tube (22) to form a ring beam, wherein the two beams work together through a focusing lens (4) to act on the edge region of the molten pool, thereby improving the edge melting uniformity and introducing tangential heat flow, promoting the flow of the molten pool and the escape of gas.

[0018] The rotating multibeam additive manufacturing apparatus based on short-wavelength composite laser is characterized in that the red light system (3) is a composite optical structure, including a red laser emitter (31) and a red light-CCD recording composite device (32). The composite device integrates: a laser collimating lens (321) for collimating the red laser; a single-sided transparent lens (323) for guiding part of the reflected light to the CCD; a focusing lens (324) for focusing the laser; a CCD (325) for receiving the reflected molten pool information beam (327); and a reflecting lens (328) for changing the optical path; thereby realizing the simultaneous in-situ heat treatment and process monitoring.

[0019] The rotating multibeam additive manufacturing device based on short-wavelength composite laser is characterized in that the rotating disk system (8) includes an active rotating disk (81) and a driven rotating disk (82) whose rotation trajectory is fixed by embedding. The motor drives the active rotating disk (81) to rotate, which in turn drives the driven rotating disk (82) to rotate around the central axis of the blue light tube. The rotation speed can be adjusted by the control system to control the formation quality of the annular light spot.

[0020] The rotary multibeam additive manufacturing device based on short-wavelength composite laser is characterized in that the additive manufacturing powder feeding system (7) is a coaxial powder feeding device, and its working state is controlled separately by the overall control system. The amount of powder fed can be controlled independently. Four powder feeding pipes (71) are evenly distributed along the axial direction of the machine box. The metal powder to be processed is fed into the pipe through inert gas and then uniformly and stably transported to the powder head.

[0021] The rotating multibeam additive manufacturing device based on short-wavelength composite laser is characterized in that the overall control system and information acquisition system (9) have a built-in material processing parameter database, which can automatically retrieve and set the power ratio of blue light and green light, the rotation speed of the rotating wheel system (8) and the processing parameters of the red light system (3) according to the input workpiece material type.

[0022] The method of using the rotating multibeam additive manufacturing apparatus based on short-wavelength composite laser is characterized by comprising the following operating steps:

[0023] Step 1: Based on the material type and processing requirements, the system (9) calls its built-in material processing parameter database to automatically match and output an optimized combination of process parameters, including but not limited to: the power and power ratio of the blue light system (1) and the green light system (2), the rotation speed of the rotary disk system (8), the heat treatment power and scanning speed of the red light system (3), and the carrier gas flow rate and powder feeding rate of the additive powder feeding device (7).

[0024] Step 2: Start the blue light system (1) and the green light system (2). The green light system (2) rotates around the blue light center beam under the drive of the rotating wheel system (8). The composite light spot acts on the additive area (51) of the processing platform (5). The coaxial powder feeding device (7) feeds the metal powder into the molten pool through four channels to complete the single-layer deposition. The blue light center spot realizes the rapid melting of the powder and the keyhole effect, while the rotating green light ring spot is used to preheat the powder, stabilize the edge of the molten pool and drive the flow of the molten pool to improve the forming quality and reduce defects.

[0025] Step 3: During the processing, the red light system (3) performs in-situ heat treatment on the additive area (52) to achieve microstructure control and stress annealing of the cladding layer. At the same time, the CCD (325) integrated in the system collects the thermal radiation and morphology information of the molten pool and heat-affected zone in real time (327) and feeds the data back to the main control system (4).

[0026] Step 4: The macroscopic morphology real-time monitoring system (6) synchronously monitors the processing morphology and acquires macroscopic morphology data such as layer thickness, warpage deformation and contour deviation of the additive part in real time. The overall control system (9) integrates multi-source feedback data from the red light system CCD and the macroscopic monitoring system, and dynamically adjusts key parameters such as the power and ratio of blue light / green light, the rotation speed of the rotating wheel, and the powder feeding rate through the built-in control algorithm to achieve closed-loop intelligent control and high-quality forming of the processing process.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. Precise and Controllable Energy Distribution: By combining a central Gaussian beam of blue light with a rotating ring-shaped green light beam, a highly flexible and adjustable energy distribution field is created. The blue light serves as the central heat source, providing the main melting energy, while the rotating green light not only expands the heating area but also allows for precise control of the molten pool flow by adjusting the rotation speed and power ratio. This composite energy field effectively improves the molten pool convection mode, promotes bubble escape and impurity floatation, and significantly reduces defects such as porosity and incomplete fusion, making it particularly suitable for processing highly reflective materials sensitive to heat input.

[0029] 2. High-efficiency processing of highly reflective materials: Short-wavelength lasers such as blue / green light have higher absorption rates for highly reflective metals like copper and aluminum, significantly improving processing efficiency and energy utilization. Taking pure copper as an example, its absorption rate for 450nm blue light can reach over 65%, far exceeding the less than 10% absorption rate for 1064nm infrared lasers. This inherent absorption advantage significantly reduces the melting threshold during processing, while also significantly improving processing stability and reducing spatter, providing a reliable technical foundation for the precision processing of highly reflective materials.

[0030] 3. Integrated in-situ processing and monitoring: The red laser system combines heat treatment and microstructure monitoring functions, enabling simultaneous "processing-treatment-monitoring". During processing, the red laser can perform in-situ heat treatment on the completed area, achieving grain refinement and stress relief by controlling the scanning speed and power; at the same time, the integrated CCD monitors the processing status and quality changes in real time by acquiring the molten pool radiation signal and thermal radiation distribution.

[0031] 4. High intelligence and adaptability: The overall control system has a built-in material database, which can automatically match the optimal parameters according to the processing object and make dynamic adjustments through real-time feedback, which greatly reduces the difficulty of operation and the dependence on the operator's experience. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the main optical path of a rotating multibeam additive manufacturing device based on short-wavelength composite laser provided by the present invention;

[0033] Figure 2 This is a schematic diagram of the rotating disk structure of a rotating multibeam additive manufacturing device based on short-wavelength composite laser provided by the present invention;

[0034] Figure 3 This is a schematic diagram of the overall structure of a rotating multibeam additive manufacturing device based on short-wavelength composite laser provided by the present invention.

[0035] Figure 4 This is a schematic diagram of the red light-CCD recording composite device of a rotating multibeam additive manufacturing device based on short-wavelength composite laser provided by the present invention;

[0036] Explanation of numbering in the diagram: 1. Blue light system; 11. Blue laser emitter; 12. Blue light tube; 121. Laser collimating lens; 122. Blue light beam; 123. Planar lens; 2. Green light system; 21. Green laser emitter; 22. Green light tube; 221. Laser collimating lens; 222. Green light beam; 223. Planar lens; 3. Red light system; 31. Red laser emitter; 32. Red light-CCD recording composite device; 321. Laser collimating lens; 322. 323. Red light beam; 324. Single-sided light-transmitting lens; 325. Focusing lens; 326. CCD; 327. Laser collimating lens; 328. Microscopic information beam; 329. Reflecting lens; 4. Focusing lens; 5. Processing platform; 51. Area to be processed; 52. Processed area; 6. Real-time macroscopic morphology monitoring system; 7. Coaxial powder feeding device for additive manufacturing; 8. Rotary wheel system; 81. Active rotating wheel; 82. Driven rotating wheel; 9. Overall control system and information acquisition system. Detailed Implementation

[0037] This invention relates to a rotating multibeam additive manufacturing apparatus based on short-wavelength composite lasers. The invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] Figure 3 This is a specific embodiment of the present invention. The figure shows a rotating multi-beam additive manufacturing device based on short-wavelength composite laser. The additive manufacturing is carried out using 5-series aluminum alloy as an example. The aluminum alloy is selected for additive manufacturing through the interface of the main control system (9). The system automatically retrieves the recommended parameters from the database: blue light system (1) power 800W, green light system (2) power 600W, rotating wheel (8) speed 60rpm, red light system (3) for interlayer heat treatment, power 150W. At the start of processing, the central blue light (122) pre-melts the powder, and the rotating green light ring (222) heats and keeps the periphery of the molten pool, promoting powder melting and reducing porosity. After each layer is completed, the red light beam (322) scans and heats the current layer to refine the grains. The CCD (325) monitors the brightness and morphology of the molten pool in real time, and the data is fed back to the main control system (9). The system fine-tunes the power according to the algorithm to ensure process stability. Finally, an aluminum alloy sample with high density and uniform structure is obtained.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A rotating multibeam additive manufacturing apparatus based on short-wavelength composite laser, characterized in that, include: The blue-green composite system consists of a blue system (1) and a green system (2). The blue system (1) includes a blue laser emitter (11) and a blue lens barrel (12) with built-in laser collimating lens (121) and plane lens (123), which can form a high-energy-density Gaussian spot to quickly melt the metal powder to be processed and form a keyhole. The green system (2) includes a green laser emitter (21) and a green lens barrel (22) with built-in laser collimating lens (221) and plane lens (223), which can form a ring beam. The two beams work together at the edge of the molten pool through a focusing lens (4) to improve the edge melting uniformity, introduce tangential heat flow, and promote the flow of the molten pool and the escape of gas. The red system (3) is a composite optical structure, including a red laser emitter (31) and a red-CCD recording composite device (32). Its core function is to perform in-situ heat treatment on the newly formed additive region (52), refine the grains by controlling the heat input, and adjust the temperature. The distribution of precipitated phases and the elimination of residual stress are controlled to optimize the microstructure and mechanical properties of the cladding layer. At the same time, the red light-CCD recording composite device (32) has a built-in laser collimating lens (321), a single-sided transparent lens (323), a focusing lens (324), a CCD (325), and a reflecting lens (328), which can realize in-situ heat treatment and process monitoring simultaneously (CCD receives the radiation information beam of the molten pool (327)). The macroscopic morphology real-time monitoring system (6) is used to monitor the macroscopic contour morphology and forming size of the additive part in real time. The additive powder feeding device (7) is used for powder feeding operation in the additive manufacturing process. The overall control system and information acquisition system (9) are electrically connected to the blue light system (1), the green light system (2), the red light system (3), the macroscopic morphology real-time monitoring system (6), and the rotating disk system (8), which can integrate and control various laser parameters, motion parameters, and powder feeding parameters, and collect and process data from various monitoring systems to realize closed-loop intelligent control of the processing process.

2. The rotating multibeam additive manufacturing apparatus based on short-wavelength composite laser according to claim 1, characterized in that, The additive manufacturing powder feeding system (7) is a coaxial powder feeding device. Its working status is controlled separately by the main control system (9), and the amount of powder fed can be controlled independently. The four powder feeding pipes (71) are evenly distributed along the axial direction of the machine box. The metal powder to be processed is fed into the pipes by inert gas and then evenly and stably transported to the powder head.

3. The rotating multibeam additive manufacturing apparatus based on short-wavelength composite laser according to claim 1, characterized in that, The rotating disk system (8) includes an active rotating disk (81) and a driven rotating disk (82) whose rotation trajectory is fixed by embedding. The motor drives the active rotating disk (81) to rotate, which in turn drives the driven rotating disk (82) to rotate around the central axis of the blue light tube. The motor drives precise speed control to adapt to the processing requirements of different materials and regulate the formation quality of the annular light spot.

4. The rotating multibeam additive manufacturing apparatus based on short-wavelength composite laser according to claim 1, characterized in that, The overall control system and information acquisition system (9) have a built-in material processing parameter database, which can automatically retrieve and set the power ratio of blue light and green light, the rotation speed of the rotating wheel system (8) and the processing parameters of the red light system (3) according to the input workpiece material type.

5. The method of using the rotating multibeam additive manufacturing apparatus based on short-wavelength composite laser according to claim 1, characterized in that, The following steps are included: Step 1: Based on the material type and processing requirements, the system (9) calls its built-in material processing parameter database to automatically match and output an optimized combination of process parameters, including but not limited to: the power and power ratio of the blue light system (1) and the green light system (2), the rotation speed of the rotary disk system (8), the heat treatment power and scanning speed of the red light system (3), and the carrier gas flow rate and powder feeding rate of the additive powder feeding device (7). Step 2: Start the blue light system (1) and the green light system (2). The green light system (2) rotates around the blue light center beam under the drive of the rotating wheel system (8). The composite light spot acts on the additive area (51) of the processing platform (5). The coaxial powder feeding device (7) feeds the metal powder into the molten pool through four channels to complete the single-layer deposition. The blue light center spot realizes the rapid melting of the powder and the keyhole effect, while the rotating green light ring spot is used to preheat the powder, stabilize the edge of the molten pool and drive the flow of the molten pool to improve the forming quality and reduce defects. Step 3: During the processing, the red light system (3) performs in-situ heat treatment on the additive area (52) to achieve microstructure control and stress annealing of the cladding layer. The CCD (325) integrated in the system collects the thermal radiation and morphology information of the molten pool and heat-affected zone in real time (327) and feeds the data back to the main control system (9). Step 4: The macroscopic morphology real-time monitoring system (6) synchronously monitors the processing morphology and acquires macroscopic data such as the layer thickness, warpage deformation and contour deviation of the additive parts in real time. The overall control system (9) integrates multi-source feedback data from the red light system CCD and the macroscopic monitoring system, and dynamically adjusts key parameters such as the power and ratio of blue light / green light, the rotation speed of the rotating wheel, and the powder feeding rate through the built-in control algorithm to achieve closed-loop intelligent control and high-quality forming of the processing process.

Images