Multi-spot synergistic laser shock peening device and method

Abstract

The application discloses a kind of multi-spot collaborative laser shock peening equipment and method, including sequentially arranged main laser, main galvanometer, diffractive beam splitting device DOE, acousto-optic modulator AOM, MEMS galvanometer, light splitting and combining mirror, field lens along laser transmission optical path, and the CCD camera, robot and workbench of cooperative work;The application is divided into multiple beam sub-laser by diffractive beam splitting device DOE, each sub-laser is regulated by power through each independent acousto-optic modulator AOM, each independent MEMS galvanometer regulates angle, and the sub-laser after regulation and CCD camera optical path are coaxial by light splitting and combining mirror, whether to hit deviation is judged by CCD camera, and the three are coordinated to make multiple beam sub-laser collaborative processing complex surface, avoid the position of traditional single beam laser inconveniently processing complex surface, especially recess, improve processing efficiency and precision.

Description

Technical Field

[0001] This invention belongs to the field of laser processing, and in particular relates to a multi-spot synergistic laser shock peening device and method. Background Technology

[0002] This patent pertains to the field of laser processing, specifically relating to the method, apparatus, and implementation process of multi-spot parallel laser shock peening (LSP) for complex curved surface components. Laser shock peening, also known as laser shot peening, is an advanced metal surface modification technology originating in the Battelle Laboratory in the United States in the 1970s. Due to its high controllability and deep strengthening effect, it has become a core anti-fatigue process in aerospace, nuclear energy, and high-end equipment manufacturing. Its core principle is: utilizing nanosecond-level high-energy short-pulse lasers (power density > 10^6 kilometres per second). 9 The laser energy is absorbed by an energy-absorbing layer (such as aluminum foil or black paint) when the metal surface is irradiated with W / cm², causing it to vaporize instantly and form a high-temperature (>10) layer. 7 Laser shock peening utilizes high-pressure (>1 GPa) plasma. Under the constraint of a confining layer (such as water or glass), the rapid expansion of the plasma generates a powerful shock wave that propagates into the material. When the pressure exceeds the material's dynamic yield strength, it induces non-uniform plastic deformation on the surface, ultimately forming a deep, high-amplitude residual compressive stress field within the material. Simultaneously, it refines the microstructure and increases surface hardness. Compared to traditional mechanical shot peening, laser shock peening can achieve a residual compressive stress layer depth of 1–2 mm (compared to only 0.1–0.3 mm for traditional shot peening), with more uniform stress distribution and greater controllability. It can precisely process difficult-to-machine areas such as grooves and small holes in complex components (e.g., aero-engine blades, gears, and nuclear power plant welds). This technology can significantly delay crack initiation, inhibit stress corrosion cracking, and greatly improve the fatigue life, impact resistance, and service stability of metal components, making it one of the key technologies for "life extension and efficiency improvement" in high-end equipment.

[0003] Currently, most existing laser shock peening equipment and processes on the market adopt a single-spot processing mode combined with a robot. This mode has inherent technical defects: a single spot can only process a local area of ​​the component at a time, resulting in low processing efficiency and difficulty in meeting the needs of large-scale mass production. For complex curved components such as aero-engine blades and curved shells, multiple clamping and adjustment of the processing posture are required, which not only increases clamping time and labor costs, but also easily affects the processing accuracy of the component due to accumulated clamping errors, resulting in poor consistency of surface performance after strengthening. In the processing of complex curved surface workpieces, existing technologies involve using multiple laser sources to address issues such as varying surface curvature and dispersed processing areas, avoiding stress imbalance and warping caused by single-point impact, and improving forming accuracy and processing efficiency. However, this approach has significant drawbacks. For example, multiple independent laser sources require multiple sets of high-power power supplies, cooling systems, and control hardware, resulting in high power consumption, significantly increased equipment purchase and maintenance costs, and the occupation of a large amount of space. At the same time, the consistency of parameters and timing synchronization of each independent laser source requires complex collaborative control algorithms, which can easily lead to fluctuations in processing quality due to differences in light sources and optical path drift. Furthermore, it is difficult to achieve flexible beam splitting and dynamic adaptation, and the adaptability to processing areas with abrupt changes in surface curvature is limited.

[0004] To address the problems of single-beam lasers being inconvenient for processing complex curved surfaces in a single operation, and the high energy consumption, large site requirements, and high costs associated with multiple lasers, there is an urgent need for a laser shock peening method that improves processing efficiency and precision to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-spot laser shock peening device and method, which avoids the problem that traditional single-beam lasers are inconvenient for processing complex curved surfaces in one operation, and improves processing efficiency and accuracy.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A multi-spot synergistic laser shock enhancement device includes, sequentially arranged along the laser transmission optical path, a main laser, a main galvanometer, a diffraction beam splitter (DOE), an acousto-optic modulator (AOM), a MEMS galvanometer, a beam splitter and combiner, a field mirror, and cooperating CCD cameras, a robot, and a worktable; wherein: The main laser is used to emit a laser beam; The master galvanometer is used to provide precise incident angle control for the DOE beam splitting device. A diffraction beam splitter (DOE) is used to split a laser beam incident from a master mirror into multiple spatially arranged sub-lasers. An acousto-optic modulator (AOM) is cascaded after each sub-laser beam is split by the diffraction beam splitter (DOE) to achieve independent energy adjustment of a single sub-laser beam. Each sub-laser beam after passing through the acousto-optic modulator AOM is connected to an independent MEMS mirror for adjusting the angle of a single laser beam. The beam splitter and beam combiner is used to integrate the sub-laser with the visual optical path of the CCD camera and allow it to be incident on the field lens after the sub-laser's angle is adjusted by the MEMS galvanometer. A field lens is used to focus a light beam onto the workpiece on the worktable. A CCD camera is connected to image processing software to process images acquired by the CCD camera and determine whether the sub-laser is misaligned.

[0007] As a further improvement, the main laser emission laser is split into 3-5 sub-lasers by the diffraction beam splitter (DOE), and the sub-lasers are arranged in a rectangular array with an angular spacing of 2°×2°.

[0008] As a further improvement, an FPGA control unit is also included. The FPGA control unit is electrically connected to the acousto-optic modulator (AOM) and is used to periodically sample the splitting energy of each sub-laser beam. The single-pulse energy error of each sub-laser beam is controlled by adjusting the radio frequency power of the acousto-optic modulator (AOM) in real time.

[0009] As a further improvement, the main laser emits a wavelength of 1064 nm, the CCD camera emits light at a wavelength of 500-700 nm, and the beam splitter has a transmittance of ≥95% for the 1064 nm wavelength band and a reflectance of ≥99% for the 532-800 nm wavelength band.

[0010] As a further improvement, the upper surface of the beam splitter and combiner is horizontal, and the lower surface is inclined at 45 degrees. The upper surface of the horizontal beam splitter and combiner faces the sub-laser after being controlled by the MEMS galvanometer, and the 45-degree inclined surface of the lower surface faces the field mirror. A CCD camera is placed on the side of the 45-degree inclined surface, so that the optical path of the CCD camera forms an angle of 45 degrees with the 45-degree inclined surface.

[0011] A strengthening method based on a multi-spot synergistic laser shock strengthening device includes the following steps: S1: The laser beam emitted by the main laser is angled by the main galvanometer and then incident on the diffraction beam splitter (DOE), which splits it into multiple sub-lasers. S2: Each sub-laser beam is incident on its cascaded acousto-optic modulator AOM. The FPGA control unit periodically samples the splitting energy of each sub-laser beam and adjusts the radio frequency power of the acousto-optic modulator AOM in real time to control the single-pulse energy error of each laser beam. S3: Each sub-laser beam after being modulated by the acousto-optic modulator (AOM) is passed through a corresponding MEMS galvanometer to adjust the emission angle of the sub-laser beam; S4: The sub-laser, after the MEMS galvanometer angle adjustment described in step 3, is incident on the beam splitter and combiner; the CCD camera takes pictures and acquires images before, during, and after laser processing, and observes whether the laser is misaligned using image processing software. If the offset is >50 µm, the corresponding MEMS galvanometer angle is individually corrected before the next laser pulse to form a pulse-level position closed loop; the sub-laser incident on the beam splitter and combiner and the CCD camera optical path are merged after passing through the beam splitter and combiner and incident on the field lens, and focused onto the workpiece by the field lens. S5: The robot control platform is responsible for macroscopic positioning, the main galvanometer performs coarse aiming, and the MEMS galvanometer performs fine scanning. Joint interpolation is completed through a three-level linkage coordinate system decoupling algorithm to achieve high-precision coordinated motion. S6: Implement parallel scanning of responsibility domains; based on the current cone angle of the multi-beam sub-lasers, the CAD surface of the workpiece is automatically divided into responsibility sub-domains of the corresponding number of sub-laser beams. Within each responsibility sub-domain, grid scanning is performed according to the set step distance. After the multi-beam sub-lasers have completed their respective responsibility sub-domain scanning simultaneously, the robot controls the worktable to perform quantitative micro-feeding and enter the next row of responsibility sub-domain scanning. S7: Perform pulse-level dual closed-loop verification; after each laser beam is emitted, complete the sub-laser splitting energy sampling and acousto-optic modulator (AOM) energy correction within 50 µs, as well as CCD camera image sampling, determining whether the sub-laser is offset and MEMS galvanometer angle correction; total closed-loop time <200 µs.

[0012] As a further improvement, the workflow of step S4 includes the following steps: S41: The CCD camera emits a photographing optical path with a wavelength of 500-700 nm. The beam splitter and beam combiner has high reflectivity in the 532-800 nm band. The photographing optical path enters the field lens through the beam splitter and beam combiner and is then projected onto the workpiece surface of the worktable to photograph and acquire the initial mark point state of the workpiece. S42: The sub-laser wavelength is 1064 nm. After the angle is adjusted by the MEMS galvanometer, the sub-laser is incident on the beam splitter and beam combiner. The beam splitter and beam combiner has high transmittance for the 1064 nm laser. After being highly transmitted by the beam splitter and beam combiner, the laser is directly incident on the field mirror and finally projected onto the surface of the workpiece. S43: The sub-laser is projected onto the surface of the workpiece to generate a light cluster. The light in the light cluster with a wavelength of 532-800nm ​​returns along the original projection path, and after being refracted by the beam splitter and beam combiner, it is transmitted to the CCD camera to obtain the status of the marked point during the process. S44: The CCD camera emits the imaging light path again, which is refracted onto the surface of the workpiece by the beam splitter and beam combiner to capture and obtain the final mark point status of the workpiece. S45: The image processing software analyzes and processes the initial, intermediate, and final states of the acquired marker points to determine whether the laser projection has shifted. When the shift exceeds 50 µm, the angle of the corresponding MEMS galvanometer is adjusted individually before the next laser pulse is emitted to correct the laser projection position.

[0013] As a further improvement, in step S5, the robot control platform is responsible for macroscopic positioning at the level of ≥100 mm; the main galvanometer is a φ30 mm dual-axis large galvanometer, responsible for coarse aiming within a range of ±25°; the MEMS galvanometer performs fine scanning within a range of ±15°; and the three-level coordinate system decoupling algorithm completes joint interpolation within 1 ms.

[0014] As a further improvement, in step S2, the FPGA control unit samples 1-3% of the split energy of each sub-laser beam at a period of 10-15µs, and adjusts the radio frequency power of the acousto-optic modulator AOM in real time to make the single-pulse energy error of each sub-laser beam <2%.

[0015] As a further improvement, in step S6, grid scanning is performed in each responsible sub-domain at a step size of 0.1 mm. After multiple sub-lasers synchronously complete the scanning of their respective responsible sub-domains, the robot controls the worktable to feed micro-feed by 2 mm and enter the next row of responsible sub-domains for scanning.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention splits the laser beam into multiple sub-lasers using a diffraction beam splitter (DOE). Each sub-laser has its power controlled by its own independent acousto-optic modulator (AOM) and its angle controlled by its own independent MEMS galvanometer. The controlled sub-lasers and the optical path of the CCD camera are coaxially connected through a beam splitter and combiner. The CCD camera determines whether the beam is misaligned. The three coordinate to enable the multi-beam lasers to process complex curved surfaces in a coordinated manner, avoiding the inconvenience of traditional single-beam lasers in processing complex curved surfaces, especially concave areas, thus improving processing efficiency and accuracy.

[0017] This invention controls the power of sub-lasers by controlling an acousto-optic modulator (AOM), adjusts the angle and position of sub-lasers by a MEMS galvanometer, and uses a CCD camera to take pictures to determine whether the laser hits the workpiece at the correct position. This allows the power and position of each sub-laser to be independently controlled, enabling each sub-laser to work independently or in coordination.

[0018] This invention uses an FPGA control unit to periodically sample the sub-laser splitting energy and adjust the acousto-optic modulator (AOM) RF power in real time. This allows for rapid correction of the single-pulse energy error of each sub-laser beam, ensuring energy consistency across beams and improving processing accuracy. It achieves precise and dynamic closed-loop control of the sub-laser single-pulse energy.

[0019] This invention achieves macroscopic positioning control via robot control, macroscopic angle and position adjustment via main galvanometer, and fine-tuning of angle and position via MEMS galvanometer, thus enabling decoupled control of the macro-micro-robot three-level coordinate system. This allows for joint interpolation of the robot, main galvanometer, and MEMS galvanometer within 1 ms, ensuring that every position of the workpiece can be scanned.

[0020] This invention combines the incident sub-laser and the CCD camera's optical path using a beam splitter and combiner, and then focuses the light onto the workpiece through the field lens. The CCD camera captures images before, during, and after laser processing to detect laser misalignment, allowing for individual correction of the corresponding MEMS galvanometer, thus forming a pulse-level position closed loop. This demonstrates how applying the concepts of coaxial vision and feature point position closed loops from machine vision to laser enhancement enables continuous monitoring of laser misalignment and rapid correction.

[0021] This invention places the upper surface of the horizontal plane of the beam splitter and beam combiner directly in front of the sub-laser controlled by the MEMS galvanometer, and the 45-degree inclined surface of the lower surface directly in front of the field mirror. The CCD camera is placed on the side of the 45-degree inclined surface of the beam splitter and beam combiner. This can improve the imaging clarity and detection accuracy while ensuring coaxial vision, and at the same time simplify the optical path layout and adapt to the high-precision requirements of laser processing. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of one of the sub-laser optical paths of the present invention; Figure 2 This is a coaxial visual schematic diagram of the present invention; In the figure: 1-Main laser, 2-Main galvanometer, 3-Diffraction beam splitter (DOE), 31-DOE layout, 4-Acousto-optic modulator (AOM), 5-MEMS galvanometer, 6-Beam splitter and combiner, 7-CCD camera, 8-Field lens, 9-Robot, 10-Stage. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The following is combined with Figures 1-2 This invention describes a multi-spot laser shock peening device and method.

[0025] like Figure 1 As shown, a multi-spot synergistic laser shock enhancement device includes a main laser 1, a main galvanometer 2, a diffraction beam splitter 3, an acousto-optic modulator 4, a MEMS galvanometer 5, a beam splitter and combiner 6, a field mirror 8, and a CCD camera 7, a robot 9, and a worktable 10 arranged sequentially along the laser transmission optical path; wherein: the main laser 1 is used to emit a laser beam; the main galvanometer 2 is used to provide precise incident angle control for the beam splitting by the diffraction beam splitter 3; the diffraction beam splitter 3 is used to split the laser incident by the main galvanometer 2 into multiple spatially arranged sub-lasers; the acousto-optic modulator 4 is cascaded with an independent acousto-optic modulator after each sub-laser after beam splitting by the diffraction beam splitter 3. AOM4 is used to achieve independent energy adjustment of a single sub-laser beam; MEMS galvanometer 5, after passing through the acousto-optic modulator AOM4, connects to an independent MEMS galvanometer 5 to adjust the angle of the single sub-laser beam, preferably a two-dimensional MEMS galvanometer; beam splitter and combiner 6, after the sub-laser beams are angled by the MEMS galvanometer 5, enters the beam splitter and combiner 6, to achieve coaxial integration of the regulated sub-laser beam path with the visual beam path of the CCD camera 7 and incident on the field lens 8; field lens 8 is used to focus the beam and project it onto the workpiece on the worktable 10; CCD camera 7 is signal-connected to image processing software to process the image acquired by the CCD camera 7 and determine whether the sub-laser beams are misaligned. This invention controls the power of the sub-lasers by controlling the acousto-optic modulator AOM4, adjusts the angle and position of the sub-lasers by the MEMS galvanometer 5, and uses the CCD camera 7 to take pictures to determine whether the laser has hit the accurate position of the workpiece, enabling independent control of the power and position of each sub-laser beam, allowing each sub-laser beam to work independently or in coordination.

[0026] In a preferred embodiment of the present invention, the main laser 1 emits laser light that is split into 3-5 sub-lasers via the diffraction beam splitter DOE 3, preferably into 5 sub-lasers, with each sub-laser arranged in a 2°×2° rectangular array at an angular interval, as shown in the DOE layout 31 in the figure.

[0027] In a preferred embodiment of the present invention, an FPGA control unit is further included. The FPGA control unit is electrically connected to the acousto-optic modulator AOM4 and is used to periodically sample the splitting energy of each sub-laser beam. By adjusting the radio frequency power of the acousto-optic modulator AOM4 in real time, the single-pulse energy error of each sub-laser beam can be controlled. This enables rapid correction of the single-pulse energy error of each sub-laser beam, ensures the consistency of energy of each sub-laser beam, improves processing accuracy, and achieves precise and dynamic closed-loop control of the single-pulse energy of the sub-lasers.

[0028] In a preferred embodiment of the present invention, the main laser 1 emits a laser wavelength of 1064 nm, the CCD camera 7 emits light with a wavelength of 500-700 nm, and the beam splitter 6 has a transmittance of ≥95% for the 1064 nm band laser and a reflectance of ≥99% for the 532-800 nm band.

[0029] In a preferred embodiment of the present invention, the upper surface of the beam splitter and beam combiner 6 is horizontal, and the lower surface is inclined at 45 degrees. The upper surface of the horizontal beam splitter and beam combiner 6 faces the sub-laser after being controlled by the MEMS galvanometer 5, and the 45-degree inclined surface of the lower surface faces the field mirror 8. A CCD camera 7 is placed on the side of the 45-degree inclined surface, such that the optical path of the CCD camera 7 forms an angle of 45 degrees with the 45-degree inclined surface.

[0030] The strengthening method of the above-mentioned multi-spot synergistic laser shock peening equipment includes the following steps: S1: The laser beam emitted by the main laser 1 is angled by the main galvanometer 2 and then incident on the diffraction beam splitter DOE3, which splits it into multiple sub-lasers. S2: Each sub-laser beam is incident on its cascaded acousto-optic modulator AOM4. The FPGA control unit periodically samples the splitting energy of each sub-laser beam and adjusts the RF power of the acousto-optic modulator AOM4 in real time to control the single-pulse energy error of each sub-laser beam. In a preferred embodiment of the present invention, the FPGA control unit periodically samples 1-3% of the splitting energy of each sub-laser beam at 10-15µs, preferably 10µs, preferably 1% of the splitting energy. By adjusting the RF power of the acousto-optic modulator AOM4 in real time, the single-pulse energy error of each sub-laser beam is made <2%.

[0031] S3: Each sub-laser beam adjusted by the acousto-optic modulator AOM4 is passed through the corresponding MEMS galvanometer 5 to adjust the emission angle of the sub-laser beam; S4: The sub-laser, after its angle is adjusted by the MEMS galvanometer 5 as described in step 3, is incident on the beam splitter and combiner 6; the CCD camera 7 takes pictures and acquires images before, during, and after laser processing, and observes whether the laser is misaligned using image processing software. If the offset is >50 µm, the corresponding angle of the MEMS galvanometer 5 is individually corrected before the next laser pulse to form a pulse-level position closed loop; the sub-laser incident on the beam splitter and combiner 6 and the optical paths of the CCD camera 7 are merged after passing through the beam splitter and combiner 6 and incident on the field lens 8, and focused onto the workpiece by the field lens 8; S5: Three-level linkage path planning; the robot 9 controls the worktable 10 for macroscopic positioning, the main galvanometer 2 performs coarse aiming, and the MEMS galvanometer 5 performs fine scanning. Joint interpolation is achieved through a three-level linkage coordinate system decoupling algorithm, realizing high-precision coordinated motion. In a preferred embodiment of the invention, the robot 9 controls the worktable 10 for macroscopic positioning at the ≥100 mm level; the main galvanometer 2 is a φ30mm dual-axis large galvanometer, responsible for coarse aiming within a ±25° range; the MEMS galvanometer 5 performs fine scanning within a ±15° range; the three-level coordinate system decoupling algorithm completes joint interpolation within 1 ms. In summary, the robot 9 controls macroscopic positioning, the main galvanometer 2 adjusts macroscopic angles and positions, and the MEMS galvanometer 5 performs fine-tuning of angles and positions, achieving macro-micro-robot three-level coordinate system linkage decoupling control, ensuring that every position of the workpiece can be scanned.

[0032] S6: Perform parallel scanning of responsibility domains; based on the current cone angle of the multi-beam sub-lasers, the CAD surface of the workpiece is automatically divided into responsibility sub-domains with the corresponding number of sub-laser beams. Within each responsibility sub-domain, grid scanning is performed at a set step distance. After the multi-beam sub-lasers synchronously complete their respective responsibility sub-domain scanning, the robot 9 controls the worktable 10 to perform quantitative micro-feeding to enter the next row of responsibility sub-domain scanning. In a preferred embodiment of the present invention, grid scanning is performed within each responsibility sub-domain at a step distance of 0.1mm. After the multi-beam sub-lasers synchronously complete their respective responsibility sub-domain scanning, the robot 9 controls the worktable 10 to perform micro-feeding of 2mm to enter the next row of responsibility sub-domain scanning.

[0033] S7: Perform pulse-level dual-loop verification; after each laser beam is emitted, complete the sub-laser splitting energy sampling and acousto-optic modulator AOM 4 energy correction within 50 µs, as well as CCD camera 7 image sampling, determining whether the sub-laser is offset, and MEMS galvanometer 5 angle correction; the total closed-loop time is <200 µs, which refers to the complete closed-loop cycle from the laser pulse emission to the next pulse emission. The purpose of dual-loop verification is to confirm whether the energy and position of the sub-laser meet the processing requirements through a cyclic process of "sampling-judgment-energy and position closed-loop correction". If not, adjust immediately to ensure the accuracy and consistency of each laser impact.

[0034] In a preferred embodiment of the present invention, such as Figure 2 As shown, the upper surface of the beam splitter / combiner 6 is horizontal, and the lower surface is inclined at a 45-degree angle. The upper surface of the horizontal beam splitter / combiner 6 faces the sub-laser after being controlled by the MEMS galvanometer 5, and the 45-degree inclined surface of the lower surface faces the field mirror 8. A CCD camera 7 is placed on the side of the 45-degree inclined surface, so that the optical path of the CCD camera 7 forms a 45-degree angle with the 45-degree inclined surface. The workflow of step S4 includes the following steps: S41: The CCD camera 7 emits an imaging optical path with a wavelength of 500-700 nm. The beam splitter / combiner 6 has high reflectivity in the 532-800 nm band. The imaging optical path enters the field mirror 8 through the beam splitter / combiner 6 and is then projected onto the workpiece surface of the worktable 10 to capture and obtain the initial marking point state of the workpiece; S42: The sub-laser wavelength is 1064 nm. The sub-laser, after its angle is adjusted by the MEMS galvanometer 5, is incident on the beam splitter and combiner 6. The beam splitter and combiner 6 has high transmittance for 1064nm lasers. After being highly transmitted by the beam splitter and combiner 6, the laser is directly incident on the field mirror 8 and finally projected onto the workpiece surface; S43: The sub-laser is projected onto the workpiece surface to generate a light cluster. The light in the light cluster with wavelengths of 532-800nm ​​returns along the original projection light path, is refracted by the beam splitter and combiner 6, and is transmitted to the CCD camera 7 to obtain the state of the marker points during the process; S44: The CCD camera 7 emits an imaging light path again, which is refracted by the beam splitter and combiner 6 onto the workpiece surface to capture and obtain the final state of the marker points on the workpiece; S45: The image processing software analyzes and processes the acquired initial state of the marker points, the state of the marker points during the process, and the final state of the marker points to determine whether the laser projection is offset. When the offset is greater than 50 µm, the angle of the corresponding MEMS galvanometer 5 is adjusted individually before the next laser pulse is emitted to correct the laser projection position.

[0035] This invention employs the concept of coaxial vision. When the light from the CCD camera 7 (wavelength 532-800nm) is incident on the beam splitter / combiner 6, the beam splitter / combiner 6 exhibits high transmittance for light in the 1064nm band and high reflectivity for light in the 532-800nm ​​band. Therefore, the light emitted by the CCD camera 7 is reflected by the beam splitter / combiner 6, while the sub-laser with a wavelength of 1064nm emitted by the MEMS galvanometer 5 on the upper surface of the beam splitter / combiner 6 is highly transmitted through it. Consequently, the sub-laser emitted by the MEMS galvanometer 5 passes perpendicularly through the beam splitter / combiner 6. When the light from the CCD camera 7, positioned to the side, is incident on the beam splitter / combiner 6, it is reflected into a vertically downward light path. At this point, the light paths of the CCD camera 7 and the sub-laser overlap within the distance from the beam splitter / combiner 6 to scene 8, achieving the application of coaxial vision, improving imaging clarity and detection accuracy, while simplifying the optical path layout and adapting to the high-precision requirements of laser processing.

[0036] This invention splits the laser beam into multiple sub-lasers using a diffraction beam splitter (DOE3). Each sub-laser has its power controlled by its own independent acousto-optic modulator (AOM4) and its angle controlled by its own independent MEMS galvanometer (MEMS galvanometer 5). The controlled sub-lasers are coaxial with the optical path of the CCD camera (7), and the CCD camera (7) determines whether the beam is misaligned. The three coordinate to enable the multi-beam sub-lasers to process complex curved surfaces in a coordinated manner, avoiding the inconvenience of processing complex curved surfaces, especially concave areas, in a single operation using a traditional single-beam laser, thus improving processing efficiency and accuracy.

[0037] The above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and are not intended to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.

Claims

1. A multi-spot synergistic laser shock enhancement device, characterized in that, The system includes, sequentially arranged along the laser transmission optical path, a main laser (1), a main galvanometer (2), a diffraction beam splitter (DOE) (3), an acousto-optic modulator (AOM) (4), a MEMS galvanometer (5), a beam splitter and combiner (6), a field mirror (8), and cooperating components such as a CCD camera (7), a robot (9), and a worktable (10); among which: The main laser (1) is used to emit a laser beam; The master galvanometer (2) is used to provide precise incident angle control for the beam splitting of the diffraction beam splitter DOE (3); A diffraction beam splitter (DOE) (3) is used to split the laser incident by the main galvanometer (2) into multiple spatially arranged sub-lasers; An acousto-optic modulator AOM (4) is cascaded with an independent acousto-optic modulator AOM (4) after each sub-laser beam is split by the diffraction beam splitter DOE (3) to achieve independent energy adjustment of a single sub-laser beam; Each sub-laser beam after passing through the acousto-optic modulator AOM (4) is connected to an independent MEMS mirror (5) for adjusting the angle of a single laser beam. The sub-laser, after its angle is adjusted by the MEMS galvanometer (5), is injected into the beam splitter (6) to achieve coaxial integration of the adjusted sub-laser optical path with the visual optical path of the CCD camera (7) and incident on the field lens (8). Field lens (8) is used to focus the light beam and direct it onto the workpiece on the worktable (10); The CCD camera (7) is connected to the image processing software signal and is used to process the images acquired by the CCD camera (7) and determine whether the sub-laser is off-target. Robot (9) is used to drive and control the movement of the workbench (10).

2. The multi-spot synergistic laser shock enhancement device according to claim 1, characterized in that, The main laser (1) emits laser light which is split into 3-5 sub-lasers by the diffraction beam splitter (DOE) (3), and the sub-lasers are arranged in a rectangular array with an angular spacing of 2°×2°.

3. The multi-spot synergistic laser shock enhancement device according to claim 1, characterized in that, It also includes an FPGA control unit, which is electrically connected to the acousto-optic modulator AOM (4) and is used to periodically sample the splitting energy of each sub-laser. By adjusting the radio frequency power of the acousto-optic modulator AOM (4) in real time, the single-pulse energy error of each sub-laser is controlled.

4. The multi-spot synergistic laser shock enhancement device according to claim 1, characterized in that, The main laser (1) emits a laser wavelength of 1064 nm, the CCD camera (7) emits light with a wavelength of 500-700 nm, and the beam splitter (6) has a transmittance of ≥95% for the 1064 nm band laser and a reflectance of ≥99% for the 532-800 nm band laser.

5. The multi-spot synergistic laser shock enhancement device according to claim 4, characterized in that, The upper surface of the beam splitter (6) is horizontal, and the lower surface is inclined at 45 degrees. The upper surface of the horizontal beam splitter (6) faces the sub-laser after being controlled by the MEMS galvanometer (5), and the 45-degree inclined surface of the lower surface faces the field mirror (8). A CCD camera (7) is placed on the side of the 45-degree inclined surface, so that the optical path of the CCD camera (7) forms an angle of 45 degrees with the 45-degree inclined surface.

6. A strengthening method based on the multi-spot synergistic laser shock strengthening device according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: The laser beam emitted by the main laser (1) is adjusted at an angle by the main galvanometer (2) and then incident on the diffraction beam splitter DOE (3), which splits it into multiple sub-lasers; S2: Each sub-laser beam is incident on its cascaded acousto-optic modulator AOM (4), and the FPGA control unit periodically samples the splitting energy of each sub-laser beam, adjusts the radio frequency power of the acousto-optic modulator AOM (4) in real time, and controls the single pulse energy error of each sub-laser beam. S3: Each sub-laser beam after being adjusted by the acousto-optic modulator AOM (4) is passed through the corresponding MEMS galvanometer (5) to adjust the emission angle of the sub-laser beam; S4: The sub-laser, after the angle adjustment of the MEMS galvanometer (5) in step 3, is incident on the beam splitter and combiner (6); the CCD camera (7) takes pictures and collects images before, during and after laser processing, and observes whether the laser is misaligned through image processing software. If the offset is >50 µm, the corresponding angle of the MEMS galvanometer (5) is individually corrected before the next laser pulse to form a pulse-level position closed loop; the sub-laser incident on the beam splitter and combiner (6) and the optical path of the CCD camera (7) are merged after passing through the beam splitter and combiner (6) and incident on the field lens (8), and focused onto the workpiece by the field lens (8); S5: The robot (9) controls the workbench (10) to perform macroscopic positioning, the main galvanometer (2) performs coarse aiming, and the MEMS galvanometer (5) performs fine scanning. The joint interpolation is completed through the three-level linkage coordinate system decoupling algorithm to achieve high-precision coordinated motion. S6: Implement parallel scanning of responsibility domains; based on the current cone angle of the multi-beam sub-lasers, the CAD surface of the workpiece is automatically divided into responsibility sub-domains with the corresponding number of sub-laser beams. Within each responsibility sub-domain, grid scanning is performed according to the set step distance. After the multi-beam sub-lasers have completed their respective responsibility sub-domain scanning simultaneously, the robot (9) controls the worktable (10) to perform quantitative micro-feeding and enter the next row of responsibility sub-domain scanning. S7: Perform pulse-level double closed-loop verification; after each laser beam is emitted, complete the sub-laser splitting energy sampling and acousto-optic modulator AOM (4) energy correction within 50 µs, as well as CCD camera (7) image sampling, judgment of whether the sub-laser is offset and MEMS galvanometer (5) angle correction; the total closed-loop time is <200 µs.

7. The strengthening method of the multi-spot synergistic laser shock strengthening device according to claim 6, characterized in that, The workflow of step S4 includes the following steps: S41: The CCD camera (7) emits a photographing optical path with a wavelength of 500-700 nm. The beam splitter (6) has high reflectivity in the 532-800 nm band. The photographing optical path enters the field lens (8) through the beam splitter (6) and is then projected onto the workpiece surface of the worktable (10) to photograph and obtain the initial marking point state of the workpiece. S42: The sub-laser wavelength is 1064 nm. The sub-laser is incident on the beam splitter and beam combiner (6) after the angle is adjusted by the MEMS galvanometer (5). The beam splitter and beam combiner (6) has high transmittance for 1064 nm laser. After being highly transmitted by the beam splitter and beam combiner (6), it is directly incident on the field mirror (8) and finally projected onto the surface of the workpiece. S43: The sub-laser is projected onto the surface of the workpiece to generate a light cluster. The light in the light cluster with a wavelength of 532-800nm ​​returns along the original projection path, and after being refracted by the beam splitter and beam combiner (6), it is transmitted to the CCD camera (7) to obtain the status of the marked point during the process. S44: The CCD camera (7) emits a photographing light path again, which is refracted onto the surface of the workpiece by the beam splitter (6) to photograph and obtain the final mark point status of the workpiece. S45: The image processing software analyzes and processes the initial, intermediate and final states of the acquired marker points to determine whether the laser projection is offset. When the offset is greater than 50 µm, the angle of the corresponding MEMS galvanometer (5) is adjusted separately before the next laser pulse is emitted to correct the laser projection position.

8. The strengthening method of the multi-spot synergistic laser shock strengthening device according to claim 6, characterized in that, In step S5, the robot (9) controls the workbench (10) to perform macroscopic positioning at the level of ≥100 mm; the main galvanometer (2) is a φ30 mm dual-axis large galvanometer, which is responsible for coarse aiming within the range of ±25°; the MEMS galvanometer (5) performs fine scanning within the range of ±15°; and the three-level coordinate system decoupling algorithm completes joint interpolation within 1 ms.

9. The strengthening method of the multi-spot synergistic laser shock strengthening device according to claim 6, characterized in that, In step S2, the FPGA control unit samples 1-3% of the split energy of each sub-laser beam at a period of 10-15µs, and adjusts the radio frequency power of the acousto-optic modulator AOM (4) in real time to make the single pulse energy error of each sub-laser beam <2%.

10. The strengthening method of the multi-spot synergistic laser shock strengthening device according to claim 6, characterized in that, In step S6, grid scanning is performed in each responsible sub-domain at a step distance of 0.1 mm. After multiple sub-lasers complete their respective responsible sub-domain scanning simultaneously, the robot (9) controls the worktable (10) to feed 2 mm and enter the next row of responsible sub-domain scanning.

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