A dual-spot parallel scanning additive manufacturing system and method

Abstract

This invention belongs to the field of laser additive manufacturing technology, specifically relating to a dual-spot parallel scanning additive manufacturing system and method. A laser generation unit dynamically distributes a laser beam to the first and second optical paths according to a preset energy ratio through polarization beam splitting. The spot generation unit uses two spatial light modulators to modulate the two beams into patterned spots and dot spots respectively. The filtering and imaging unit filters and images the two beams. The parallel scanning unit drives the dual spots to scan synchronously on a powder bed. The control unit performs model slicing and patterned region segmentation, and dynamically allocates energy and synchronously controls all units to work together based on the segmentation results. This achieves a single laser, dual optical paths, irregularly shaped spots, and parallel scanning, simultaneously balancing processing efficiency and forming accuracy, effectively solving the technical problem of traditional single-spot methods that struggle to achieve both efficiency and accuracy.

Description

Technical Field

[0001] This invention belongs to the field of laser additive manufacturing technology, specifically relating to a dual-spot parallel scanning additive manufacturing system and method. Background Technology

[0002] Currently, laser selective melting (SLM) technology mostly uses a single-shaped laser spot for layer-by-layer scanning. While the single Gaussian spot used in traditional SLM equipment can ensure processing accuracy, its point-by-point scanning method results in extremely low forming efficiency, making it difficult to meet the manufacturing needs of large-sized parts.

[0003] To improve efficiency, existing technologies have proposed using line or area spot beams to increase the cladding area per scan and thus shorten processing time. However, these solutions are essentially still single-path serial processing modes, meaning only one type of spot can be used for scanning at a time. This approach has technical drawbacks: if a large area spot is used to quickly fill the interior, the edge quality and dimensional accuracy of critical areas such as the part contour and fine features will significantly decrease due to the lack of energy concentration; if a small spot is used to ensure contour accuracy, the overall efficiency cannot be fundamentally improved. Furthermore, existing systems lack the ability to dynamically allocate energy based on regional characteristics, failing to intelligently and in real-time match the most suitable energy density to different areas during processing, making it difficult to simultaneously achieve both high efficiency and high precision.

[0004] Furthermore, if two different types of light spots are generated and controlled in parallel in one device, challenges arise regarding whether the two light spots can work together according to the characteristics of the processing area and the time consumption issue. Therefore, there is an urgent need for an additive manufacturing system that can integrate the advantages of different light spots and achieve parallel scanning and intelligent energy distribution. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a dual-spot parallel scanning additive manufacturing system and method, which solves the problem of how to generate and control two different types of light spots in parallel in one device, and enable them to work collaboratively according to the characteristics of the processing area, thereby achieving a balance between efficiency and accuracy in space and time.

[0006] The objective of this invention can be achieved through the following technical solution: a dual-spot parallel scanning additive manufacturing system, comprising: The laser generation unit is used to generate polarized light and shape it into a rectangular light spot, and dynamically distribute the rectangular light spot to the first and second optical paths, which are independent of each other, according to a preset energy distribution ratio. The light spot generation unit includes a first spatial light modulator and a second spatial light modulator. The first spatial light modulator is disposed in a first optical path to modulate a rectangular light spot into a patterned light spot, and the second spatial light modulator is disposed in a second optical path to modulate a rectangular light spot into a dotted light spot. The filtering imaging unit includes a first 4f imaging unit and a second 4f imaging unit. The first 4f imaging unit is disposed after the first spatial modulator and is used to filter and image the laser beam passing through the first optical path so that the patterned light spot is output in the form of parallel light. The second 4f imaging unit is disposed after the second spatial light modulator and is used to filter out the high-order diffraction light generated by the second optical path and retain only the zero-order point light spot. The parallel scanning unit includes a first parallel scanning unit and a second parallel scanning unit. The first scanning unit projects a patterned light spot onto the powder bed to perform patterned light spot scanning, and the second scanning unit projects a dotted light spot onto the powder bed to perform dotted light spot scanning. The forming execution unit includes a powder bed and an atmosphere system for laying metal powder layer by layer and receiving scanning of patterned light spots and dotted light spots under inert gas protection to melt and form the powder. The control unit is electrically connected to the laser generation unit, the spot generation unit, the filtering imaging unit, the parallel scanning unit, and the forming execution unit, respectively. It is used to slice and pattern the three-dimensional model, plan the scanning paths of two types of spots, calculate and instruct the laser generation unit to dynamically adjust the energy distribution ratio of the two optical paths based on the region segmentation results, and synchronously control the spot shape of the spot generation unit, the scanning action of the parallel scanning unit, and the powder spreading and lifting operation of the forming execution unit.

[0007] Preferably, the laser generation unit includes a randomly polarized laser, a beam expander for amplifying the laser, a homogenizing and shaping device for shaping, a rotating half-wave plate, and a polarizing reflector connected in sequence. The rotating half-wave plate includes a half-wave plate and an electrically adjustable rotating frame, used to adjust the energy distribution ratio of horizontally polarized light and vertically polarized light in the randomly polarized light. The polarizing reflector is used to separate the horizontally polarized light and the vertically polarized light into the first optical path and the second optical path, respectively.

[0008] Preferably, the second optical path is further provided with a first reflector and a second reflector. The first reflector and the second reflector are sequentially arranged after the polarizing reflector to adjust the direction of the vertically polarized light in the second optical path, so that the patterned light spot is incident on the second spatial light modulator at an angle of less than 15°.

[0009] Preferably, the first scanning unit includes a first galvanometer and a first field mirror, and the second scanning unit includes a second galvanometer and a second field mirror.

[0010] Preferably, the second optical path further includes a third reflecting mirror, which is used to receive the spot light from the second 4f imaging unit and reflect it into the second galvanometer.

[0011] Preferably, the first 4f imaging unit includes a first lens and a second lens; The second 4f imaging unit includes a third lens, an aperture stop, and a fourth lens. The aperture stop is placed between the third and fourth lenses. The third and fourth lenses are used to filter and image the laser beam. The aperture stop is used to filter out the higher-order light generated by optical diffraction after the light path passes through the second spatial light modulator, and only image the zero-order light.

[0012] A dual-spot parallel scanning additive manufacturing method, comprising the following steps: S1: Slice the 3D model, perform patterned region segmentation for each slice layer, plan the point spot scanning area and the patterned spot scanning area, calculate the energy distribution ratio required for the two optical paths, and generate two scanning paths for the two types of spots respectively. S2: The random polarization laser emits laser light, which is expanded by a beam expander to increase the beam diameter. Then, the Gaussian spot is transformed into a rectangular uniform spot by a homogenization and shaping device. The rotating half-wave plate is controlled to rotate to a set angle according to the energy distribution ratio. S3: The polarizing beam splitter dynamically distributes the laser to the first optical path and the second optical path. In the first optical path, the laser is modulated into a patterned spot of a preset shape; in the second optical path, the laser is modulated into a dotted spot. S4: After the patterned spot and the dot spot are imaged and filtered by the first 4f imaging unit and the second 4f imaging unit respectively, they are projected onto the powder bed by two independent first scanning units and second scanning units respectively, and the two units are driven to perform scanning synchronously to melt the metal powder in the corresponding area to form the current cladding layer. After the current layer is scanned, a new powder layer is laid, and the above steps are repeated until the part is manufactured.

[0013] Preferably, in S1, calculating the required energy distribution ratio between the two optical paths includes: calculating the required optimal laser power ratio based on the area ratio and material properties of the two scanning regions in the current layer, and using the optimal laser power ratio to allocate the energy distribution ratio between the first optical path and the second optical path.

[0014] Preferably, in S4, during the process of forming the current cladding layer, an inert gas is continuously provided to protect the metal powder from oxidation.

[0015] Preferably, in S3: The generation of the patterned light spot includes, according to the preset pattern information, the first spatial modulator adjusts the laser wave in advance to generate a patterned light spot with the set pattern; The generation of the spot involves: the laser is incident on the second spatial light modulator at an angle of less than 15° to generate a zero-order spot with a diameter of 5-50 μm.

[0016] The beneficial effects of this invention are as follows: By using parallel scanning of patterned light spots and dot light spots, large-area filling and fine contour scanning are achieved simultaneously, significantly shortening printing time. This is especially suitable for manufacturing large-sized parts. The dot light spot channel ensures the processing accuracy and surface quality of areas such as part contours, thin walls, and complex features. The patterned light spot channel allows for customized patterns, optimizing the molten pool morphology and reducing internal defects and residual stress. By dynamically adjusting the energy distribution of the two light paths through a rotating half-wave plate, the system can provide the most suitable energy input in real time according to the processing needs of different areas and materials, achieving optimal energy utilization and intelligent processing. The first spatial light modulator is programmable to generate arbitrary patterned light spots, enabling it to adapt to various complex scanning strategies and making it highly versatile. Attached Figure Description

[0017] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the device structure of the system of the present invention; Figure 2 This is a schematic diagram of each node in the execution process of the system of the present invention; Figure 3 This is a flowchart of the method steps of the present invention; Explanation of main component symbols In the picture: 1. Randomly polarized laser; 2. Beam expander; 3. Homogenization and shaping device; 4. Rotating half-wave plate; 5. Polarizing reflector prism; 6. First reflecting mirror; 7. Second reflecting mirror; 14. First 4f imaging unit; 9. Second 4f imaging unit; 10. Third reflecting mirror; 13. First spatial light modulator; 8. Second spatial light modulator; 15. First galvanometer; 16. First field mirror; 11. Second galvanometer; 12. Second field mirror; 17. Powder bed; 171. Molding cylinder; 172. Powder cylinder; 173. Powder spreading shaft; 18. Atmosphere system; 19. Computer. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0020] Please see Figures 1-3 This embodiment provides a dual-spot parallel scanning additive manufacturing system, including: The laser generation unit is used to generate polarized light and shape it into a rectangular light spot, and dynamically distribute the rectangular light spot to the first and second optical paths, which are independent of each other, according to a preset energy distribution ratio. The laser generation unit includes a random polarization laser 1, a beam expander 2 for amplifying the laser beam, a homogenization and shaping device 3 for shaping, a rotating half-wave plate 4, and a polarization reflecting prism 5 connected in sequence. A randomly polarized laser 1 serves as the system light source; a fiber laser or semiconductor laser can be selected. It emits high-power laser light with random polarization direction, providing the energy for processing. A beam expander 2 enlarges the laser beam diameter and reduces the divergence angle, preparing for subsequent homogenization and shaping. A homogenization and shaping device 3, which can be an aspherical lens, microlens array, birefringent lens, or optical waveguide, shapes the conventional circular Gaussian spot emitted by the laser into a rectangular uniform spot. This ensures that the shape and intensity distribution match the entrance of the liquid crystal spatial light modulator, improving energy utilization and modulation effect. The rotating half-wave plate 4 includes a half-wave plate and an electrically adjustable rotating frame. The electrically adjustable rotating frame is electrically connected to a control unit. The control unit precisely controls the rotation angle of the half-wave plate by controlling the electrically adjustable rotation, thereby dynamically adjusting the polarization direction of the laser. This allows for the distribution of laser power into the two optical paths as needed, and further adjusts the energy distribution ratio of horizontally polarized light and vertically polarized light in the randomly polarized light. The polarization beam splitter separates the light according to the polarization state. Typically, horizontally polarized light (P-beam) is transmitted into the first optical path (patterned spot), while vertically polarized light (S-beam) is reflected into the second optical path (spotted spot).

[0021] The first optical path is set between the laser generation unit and the first scanning unit. The first optical path is provided with a first spatial modulator and a first 4f imaging unit 14 for generating patterned light spots. The second optical path is set between the laser generation unit and the second scanning unit. The second optical path is equipped with a second spatial modulator, a second scanning unit, a first reflector 6, a second reflector 7 and a third reflector 10, and is used to generate spotlights. The first and second optical paths here are used to describe the two paths through which the beam passes and to generate different patterns of the beam by passing through different devices. The first reflector 6 and the second reflector 7 are set in the second optical path. The first reflector 6 and the second reflector 7 are set after the polarizing reflector prism 5 to adjust the optical path direction of vertically polarized light in the second optical path, so that the patterned light spot is incident on the two spatial light modulators of the light spot generation unit at a direction of less than 15°. The light spot generation unit includes a first spatial light modulator 13 and a second spatial light modulator 8. The first spatial light modulator is disposed in a first optical path to modulate a rectangular light spot into a patterned light spot, and the second spatial light modulator 8 is disposed in a second optical path to modulate a rectangular light spot into a dotted light spot. The first spatial light modulator 13 and the second spatial light modulator 8 are liquid crystal spatial light modulators (SLMs). The first spatial light modulator 13 can be an amplitude-type light valve or a phase-type light valve. When an amplitude-type light valve is used, the control unit directly transmits the segmented pattern information to the light valve. When a phase-type light valve is used, a holographic phase image is calculated based on the pattern information and the built-in algorithm of the control unit. The holographic phase image is then loaded onto the light valve to generate a patterned light spot of arbitrary shape. The second spatial light modulator 8 uses a phase-type optical valve. The control unit calculates and generates a uniform phase map and loads it onto the optical valve to generate diffraction-limited spot light (5-50μm in diameter). The size of the spot light can be adjusted according to the required contour accuracy.

[0022] The filtering imaging unit includes a first 4f imaging unit 14 and a second 4f imaging unit 9. The first 4f imaging unit 14 is disposed after the first spatial modulator and is used to filter and image the laser beam passing through the first optical path so that the patterned light spot is output in the form of parallel light. The second 4f imaging unit 9 is disposed after the second spatial light modulator 8 and is used to filter out the high-order diffraction light generated by the second optical path and retain only the zero-order point light spot. The first 4f imaging unit 14, including a first lens and a second lens, is located after the first spatial light modulator 13. Its functions are: first, to filter and clean the light beam; and second, to image the pattern on the SLM onto the entrance of the scanning galvanometer, ensuring the pattern accuracy. The second 4f imaging unit 9 includes a third lens, an aperture stop, and a fourth lens. The aperture stop is placed between the third and fourth lenses at the focal plane. The third and fourth lenses are used to filter and image the laser beam. The aperture stop only allows the brightest, undeflected zero-order light (spot) to pass through, blocking other stray light and ensuring the energy concentration and quality of the spot. It is used to filter out the high-order light generated by optical diffraction after the light path passes through the second spatial light modulator 8, and only images the zero-order light. The second optical path is also provided with a third reflecting mirror 10, which is used to receive the spot light from the second 4f imaging unit 9 and reflect it into the second galvanometer 11. The parallel scanning unit includes a first parallel scanning unit and a second parallel scanning unit. The first scanning unit projects a patterned light spot onto the powder bed 17 to perform patterned light spot scanning, and the second scanning unit projects a dotted light spot onto the powder bed 17 to perform dotted light spot scanning. The first scanning unit includes a first galvanometer 15 and a first field mirror 16. The second scanning unit includes a second galvanometer 11 and a second field mirror 12. The first galvanometer 15 and the second galvanometer 11 are high-speed rotating mirrors, which are responsible for controlling the scanning path of the laser beam in the XY plane in the two beams respectively. The first field mirror 16 and the first galvanometer 15 work together, as do the second field mirror 12, to ensure that the laser beam is always vertically focused on the same plane of the powder bed 17 during the scanning process, forming a flat processing area and eliminating optical distortion. The forming execution unit includes a powder bed 17 and an atmosphere system 18, which are used to lay metal powder layer by layer and receive scanning of pattern spot and dot spot under the protection of inert gas to melt and form. The powder bed 17 includes a forming cylinder 171 (where the part is formed), a powder cylinder 172 (supplying new powder), and a powder spreading shaft 173 (laying a uniform powder layer), which is the area where the metal powder is melted and formed. The atmosphere system 18 is used to provide an inert protective gas (such as argon) to reduce the oxygen content in the printing chamber to an extremely low level, preventing the metal powder from oxidizing at high temperatures and affecting the performance of the part. The control unit can be a computer 19 or other electronic components with data processing and control functions. The control unit is electrically connected to the laser generation unit, the spot generation unit, the filtering imaging unit, the parallel scanning unit, and the forming execution unit, respectively. It is used to slice and pattern the three-dimensional model, plan the scanning paths of two types of spots, calculate and instruct the laser generation unit to dynamically adjust the energy distribution ratio of the two optical paths according to the region segmentation results, and synchronously control the spot shape of the spot generation unit, the scanning action of the parallel scanning unit, and the powder spreading and lifting operation of the forming execution unit.

[0023] As shown in the figure, the specific execution process of each device in the system includes: In the laser generation unit, the random polarization laser 1 generates a random polarization laser, the beam expander 22 expands the laser radius, and then the homogenization and shaping device 3 shapes the laser beam into a rectangular spot that matches the entrance size of the subsequent liquid crystal spatial light modulator. Then, the rotating half-wave plate 4 distributes two laser beams of different horizontal and vertical polarization based on the calculated energy distribution ratio. The horizontal and vertical polarization beams are then distributed to the first and second optical paths, respectively, by the polarization reflecting prism 5. Then, in the second optical path, the vertically polarized light passes sequentially through: the first reflecting mirror 6, the second reflecting mirror 7, the second spatial light modulator 8, the second 4f imaging unit 9, and the third reflecting mirror. After passing through the second optical path, the vertically polarized light generates a modulated dot spot. In the first optical path, the horizontally polarized light passes sequentially through the first spatial light modulator 13 and the first 4f imaging unit 14. After passing through the first optical path, the horizontally polarized light generates a modulated pattern spot. Subsequently, the patterned light spot enters the first scanning unit, which projects the patterned light spot into the powder bed 17 to perform patterned light spot scanning; the dot light spot enters the second scanning unit, which projects the dot light spot into the powder bed 17 to perform dot light spot scanning. The scanning actions of the two beams of light are performed simultaneously. Under the irradiation of two laser beams, the metal powder located on the powder bed 17 is instantly melted, cooled and solidified to form the solid cross section of the current layer, thus completing the current layer.

[0024] The system utilizes a single laser, dual optical paths, irregularly shaped spots, and parallel scanning. Specifically, it uses a single laser to generate two independently controllable laser beams through polarization beam splitting technology, which are then shaped into light spots with different energy distributions (a planar patterned light spot and a dotted high-energy light spot). Two scanning systems are then used to process these spots simultaneously on a powder bed 17, thereby achieving high-efficiency and high-quality dual-beam laser selective melting additive manufacturing.

[0025] A dual-spot parallel scanning additive manufacturing method, comprising the following steps: S1: Slice the 3D model, perform patterned region segmentation for each slice layer, plan the point spot scanning area and the patterned spot scanning area, calculate the energy distribution ratio required for the two optical paths, and generate two scanning paths for the two types of spots respectively. This includes using computer 19 to perform the following sub-steps: 3D model slicing: Import the 3D CAD model of the part into the system, discretize it along the Z-axis (construction direction), and divide it into a series of 2D thin layers of specific thickness.

[0026] Patterned region segmentation: For each slice layer, the algorithm automatically decomposes its geometry into different processing regions. Typically, regions with high precision requirements, such as contours, edges, fine features, and supporting structures, are divided into point spot scanning areas.

[0027] Large solid areas, filled areas, and other regions with high efficiency requirements are designated as patterned light spot scanning areas.

[0028] Scan path planning: Generate the optimal scan path for each of the two types of light spots.

[0029] Plan high-precision contour tracking or filling paths for point light spots.

[0030] To plan a scanning path that maximizes the coverage area for patterned light spots, the pattern itself (such as strip, grid, or multi-spot pattern) can also be part of the path.

[0031] The calculation of the required energy allocation ratio between the two optical paths includes: calculating the required optimal laser power ratio based on the area ratio and material properties of the two scanning regions in the current layer, and using the optimal laser power ratio to allocate the energy allocation ratio between the first and second optical paths; S2: The random polarization laser 1 emits laser light, which is expanded by the beam expander 2 to enlarge the beam diameter. Then, the Gaussian spot is transformed into a rectangular uniform spot by the homogenization and shaping device 3. The rotating half-wave plate 4 is controlled to rotate to a set angle according to the energy distribution ratio. Laser emission and shaping: The random polarization laser 1 emits laser light, which is expanded by the beam expander 2 to enlarge the beam diameter, and then the Gaussian spot is transformed into a rectangular uniform spot by the homogenization and shaping device 3.

[0032] Dynamic energy distribution: Based on the calculation results of step S1, computer 19 drives the electric rotating frame of rotating half-wave plate 4 to rotate to a specific angle, thereby preset the polarization direction of the laser and determining the power ratio after subsequent beam splitting. S3: The polarizing beam splitter dynamically distributes the laser to the first optical path and the second optical path. In the first optical path, the laser is modulated into a patterned spot of a preset shape; in the second optical path, the laser is modulated into a dotted spot. The generation of the patterned light spot includes, according to the preset pattern information, the first spatial modulator adjusts the laser wave in advance to generate a patterned light spot with the set pattern; The generation of the spot includes: the laser is incident on the second spatial light modulator 8 at an angle of less than 15° to generate a zero-order spot with a diameter of 5-50 μm; Specifically, it includes: Polarization beam splitting: A laser beam, after polarization adjustment, is incident on a polarization beam splitter and separated into two independent beams. First optical path (S-ray): Transmitted into the patterned light spot channel.

[0033] Second optical path (P-beam): Reflected into the spot channel.

[0034] Patterned light spot generation: The first beam of light illuminates the first liquid crystal spatial light modulator (SLM). Based on the preset pattern information sent by the computer 19, the SLM modulates the laser wavefront to generate a corresponding customized patterned light spot.

[0035] Spot generation: After being adjusted by the first reflecting mirror 6 and the second reflecting mirror 7, the second beam of light is incident on the second spatial light modulator 8 at an angle of less than 15°, which is set to generate a zero-order spot. S4: After the patterned spot and the dot spot are imaged and filtered by the first 4f imaging unit 14 and the second 4f imaging unit 9 respectively, they are projected onto the powder bed 17 by two independent first scanning units and second scanning units, and the two units are driven to perform scanning synchronously to melt the metal powder in the corresponding area and form the current cladding layer. The light beam enters the second 4f imaging unit 9, where the aperture in the second 4f imaging unit 9 filters out the useless higher-order light generated by diffraction, retaining only the pure, energy-concentrated zero-order point spot. Beam delivery and imaging: The patterned light spot is imaged and filtered by the first 4f imaging unit 14 and then accurately projected onto the entrance of the first galvanometer 15. After the spot light is imaged by the second 4f imaging unit 9, it is accurately projected onto the entrance of the second galvanometer 11; synchronous scanning: computer 19 synchronously drives the two galvanometer systems.

[0036] The first galvanometer 15 and the first field mirror 16 drive the patterned light spot to scan along a predetermined path on the powder bed 17.

[0037] The second galvanometer 11 and the second field mirror 12 drive the spot light to scan along another predetermined path on the powder bed 17.

[0038] The scanning action of the two beams of light is carried out simultaneously, melting the area they are responsible for respectively.

[0039] Layer cladding: Under the irradiation of two laser beams, the metal powder on the powder bed 17 is instantly melted, cooled, and solidified to form the solid cross-section of the current layer. The atmosphere system 18 continuously provides inert gas protection to prevent oxidation; After the current layer is completed: the powder spreading shaft 173 pushes the powder in the powder cylinder 172 to the top of the forming cylinder 171, spreading a new layer of metal powder, and the forming cylinder 171 descends: the forming cylinder 171 descends by the height of one layer thickness.

[0040] Iterative loop: The system repeats S1 to S4, processes the data of the next layer and performs processing, and so on, until the entire 3D part is manufactured.

[0041] The beneficial effects of this method are: By using parallel scanning of patterned light spots and dot light spots, large-area filling and fine contour scanning can be performed simultaneously, significantly shortening printing time, which is especially suitable for manufacturing large-sized parts.

[0042] The dot-spot channel ensures the machining accuracy and surface quality of areas such as part contours, thin walls, and complex features; the patterned spot channel allows for customized patterns, optimizes the molten pool morphology, and reduces internal defects and residual stress.

[0043] By dynamically adjusting the energy distribution of the two beams by rotating a half-wave plate, the most suitable energy input can be provided in real time according to the processing needs of different regions and materials, thus achieving optimal energy utilization and intelligent processing.

[0044] The first spatial light modulator is programmable to generate arbitrary patterned light spots, enabling it to adapt to various complex scanning strategies and making it highly versatile.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A dual-spot parallel scanning additive manufacturing system, characterized by: include: The laser generation unit is used to generate polarized light and shape it into a rectangular light spot, and dynamically distribute the rectangular light spot to the first and second optical paths, which are independent of each other, according to a preset energy distribution ratio. The light spot generation unit includes a first spatial light modulator and a second spatial light modulator. The first spatial light modulator is disposed in a first optical path to modulate a rectangular light spot into a patterned light spot, and the second spatial light modulator is disposed in a second optical path to modulate a rectangular light spot into a dotted light spot. The filtering imaging unit includes a first 4f imaging unit and a second 4f imaging unit. The first 4f imaging unit is disposed after the first spatial modulator and is used to filter and image the laser beam passing through the first optical path so that the patterned light spot is output in the form of parallel light. The second 4f imaging unit is disposed after the second spatial light modulator and is used to filter out the high-order diffraction light generated by the second optical path and retain only the zero-order point light spot. The parallel scanning unit includes a first parallel scanning unit and a second parallel scanning unit. The first scanning unit projects a patterned light spot onto the powder bed to perform patterned light spot scanning, and the second scanning unit projects a dotted light spot onto the powder bed to perform dotted light spot scanning. The forming execution unit includes a powder bed and an atmosphere system for laying metal powder layer by layer and receiving scanning of patterned light spots and dotted light spots under inert gas protection to melt and form the powder. The control unit is electrically connected to the laser generation unit, the spot generation unit, the filtering imaging unit, the parallel scanning unit, and the forming execution unit, respectively. It is used to slice and pattern the three-dimensional model, plan the scanning paths of two types of spots, calculate and instruct the laser generation unit to dynamically adjust the energy distribution ratio of the two optical paths based on the region segmentation results, and synchronously control the spot shape of the spot generation unit, the scanning action of the parallel scanning unit, and the powder spreading and lifting operation of the forming execution unit.

2. A dual spot parallel scanning additive manufacturing system according to claim 1, wherein: The laser generation unit includes a randomly polarized laser, a beam expander for amplifying the laser beam, a homogenizing and shaping device for shaping, a rotating half-wave plate, and a polarizing reflector connected in sequence. The rotating half-wave plate includes a half-wave plate and an electrically adjustable rotating frame, used to adjust the energy distribution ratio of horizontally polarized light and vertically polarized light in the randomly polarized light. The polarizing reflector is used to separate the horizontally polarized light and the vertically polarized light into the first optical path and the second optical path, respectively.

3. A dual spot parallel scanning additive manufacturing system according to claim 2, wherein: The second optical path is also provided with a first reflector and a second reflector. The first reflector and the second reflector are arranged sequentially after the polarizing reflector to adjust the direction of the vertically polarized light in the second optical path, so that the patterned light spot is incident on the second spatial light modulator at an angle of less than 15°.

4. A dual spot parallel scanning additive manufacturing system according to claim 3, wherein: The first scanning unit includes a first galvanometer and a first field mirror, and the second scanning unit includes a second galvanometer and a second field mirror.

5. A dual spot parallel scanning additive manufacturing system according to claim 4, wherein: The second optical path also includes a third reflecting mirror, which is used to receive the spot light from the second 4f imaging unit and reflect it into the second galvanometer.

6. The dual spot parallel scanning additive manufacturing system of claim 1, wherein: The first 4f imaging unit includes a first lens and a second lens; The second 4f imaging unit includes a third lens, an aperture stop, and a fourth lens. The aperture stop is placed between the third and fourth lenses. The third and fourth lenses are used to filter and image the laser beam. The aperture stop is used to filter out the higher-order light generated by optical diffraction after the light path passes through the second spatial light modulator, and only image the zero-order light.

7. A dual-spot parallel scanning additive manufacturing method, applied to a dual-spot parallel scanning additive manufacturing system as described in any one of claims 1-6, the method comprising the following steps: S1: Slice the 3D model, perform patterned region segmentation for each slice layer, plan the point spot scanning area and the patterned spot scanning area, calculate the energy distribution ratio required for the two optical paths, and generate two scanning paths for the two types of spots respectively. S2: The random polarization laser emits laser light, which is expanded by a beam expander to increase the beam diameter. Then, the Gaussian spot is transformed into a rectangular uniform spot by a homogenization and shaping device. The rotating half-wave plate is controlled to rotate to a set angle according to the energy distribution ratio. S3: The polarizing beam splitter dynamically distributes the laser to the first optical path and the second optical path. In the first optical path, the laser is modulated into a patterned spot of a preset shape; in the second optical path, the laser is modulated into a dotted spot. S4: After the patterned spot and the dot spot are imaged and filtered by the first 4f imaging unit and the second 4f imaging unit respectively, they are projected onto the powder bed by two independent first scanning units and second scanning units respectively, and the two units are driven to perform scanning synchronously to melt the metal powder in the corresponding area to form the current cladding layer. After the current layer is scanned, a new powder layer is laid, and the above steps are repeated until the part is manufactured.

8. A two-beam parallel scanning additive manufacturing method according to claim 7, wherein: In S1, the calculation of the required energy distribution ratio between the two optical paths includes: calculating the required optimal laser power ratio based on the area ratio and material properties of the two scanning regions in the current layer, and using the optimal laser power ratio to allocate the energy distribution ratio between the first and second optical paths.

9. A dual spot parallel scanning additive manufacturing method according to claim 6, wherein: In S4, during the formation of the current cladding layer, an inert gas is continuously supplied to protect the metal powder from oxidation.

10. The dual-spot parallel scanning additive manufacturing method of claim 6, wherein: In S3: The generation of the patterned light spot includes, according to the preset pattern information, the first spatial modulator adjusts the laser wave in advance to generate a patterned light spot with the set pattern; The generation of the spot involves: the laser is incident on the second spatial light modulator at an angle of less than 15° to generate a zero-order spot with a diameter of 5-50 μm.

Images