Composite laser shock peening equipment and turbine blade laser shock peening method

Abstract

The invention provides composite laser shock peening equipment and a turbine blade laser shock peening method. The composite laser shock peening equipment comprises a first laser, a second laser, a third laser and a fourth laser, wherein the first laser outputs large-energy laser shock with single pulse energy larger than 1J to a first target area; the second laser outputs small-energy laser shock with single pulse energy at dozens of to hundreds of mJ levels to a second target area; the movement system is used for clamping and moving the to-be-machined part to the first target area or the second target area; the water restraint loading system is used for applying a water restraint layer; and the control system is used for adjusting working parameters of the modules. The invention further provides a turbine blade composite laser shock peening method implemented through the equipment, and the problem that double requirements of improvement of deep residual compressive stress and improvement of high surface residual compressive stress cannot be considered in a single process mode is solved through a large-energy and small-energy composite laser shock peening process.

Description

Technical Field

[0001] This invention relates to the field of laser shock peening technology, and in particular to a composite laser shock peening device and a method for laser shock peening turbine blades. Background Technology

[0002] Laser shock peening technology, as an advanced method for strengthening metal surfaces, uses nanosecond-level pulse width and high power density laser pulses to act on the metal surface, forming plasma shock waves that induce plastic deformation. This generates residual compressive stress in the material surface and within a certain depth, and refines the grains, significantly improving the fatigue resistance, stress corrosion resistance, and friction and wear resistance of metal parts.

[0003] In current industrial applications, laser shock peening methods are mainly divided into two categories: high-energy processes with single pulse energy greater than 1 joule and a large spot diameter, and low-energy processes with single pulse energy in the tens to hundreds of millijoules range and a small spot diameter. High-energy processes can form a residual compressive stress layer with a depth of about 2 millimeters, suitable for strengthening larger and thicker metal parts; low-energy processes generate higher intensity residual compressive stress on the surface, but the depth of influence is usually limited to within 1 millimeter, making them more suitable for strengthening smaller or thinner parts. Existing laser shock peening equipment generally suffers from functional limitation, supporting only one of the high-energy or low-energy process modes.

[0004] However, in practical engineering, fatigue fracture of many critical components, such as turbine blades, is often caused by a combination of complex factors. For example, the tenon joint may simultaneously experience geometric stress concentration and crack initiation due to fretting wear. A single process mode cannot simultaneously address the dual requirements of mitigating stress concentration through deep residual compressive stress and enhancing resistance to fretting wear through high surface residual compressive stress and hardness, thus limiting the strengthening effect. Therefore, there is an urgent need to develop composite equipment that can flexibly adapt to different process requirements to address the pressing need for multi-mode laser shock strengthening of complex components. Summary of the Invention

[0005] This invention provides a composite laser shock strengthening device and a laser shock strengthening method for turbine blades. By flexibly adapting to high-energy and low-energy laser shock strengthening methods, it meets the multi-mode strengthening needs of complex components such as turbine blades, thereby improving the fatigue resistance and fretting wear resistance of the parts. This solves the problem that a single process mode cannot simultaneously meet the dual needs of improving deep residual compressive stress and increasing high surface residual compressive stress.

[0006] This invention provides a composite laser shock peening device, comprising:

[0007] The first laser is configured to output a high-energy laser shock with a single pulse energy greater than 1J to the first target area under the transmission of the first shock optical path. The second laser is configured to output a single pulse of low-energy laser energy in the tens to hundreds of mJ range to the second target region under the transmission of the second impact optical path. A motion system is used to clamp the part and drive the impact-strengthening area of ​​the part to pass sequentially through the first target area and / or the second target area. A water-constrained loading system is used to apply a water-constrained layer to the surface of the impact-strengthening area of ​​a part. The control system is communicatively connected to the first laser, the second laser, the motion system, and the water-constrained loading system. It controls the operating parameters of the first and second lasers, the trajectory of parts in the motion system, and the switching and pressure of the water-constrained loading system applying the water constraint layer.

[0008] In one embodiment of the present invention, the output wavelength of the first laser is 1064nm, and the output wavelength of the second laser is 1064nm or 532nm.

[0009] In one embodiment of the present invention, the first impact optical path of the first laser includes a laser transmission module, an energy adjustment module, a laser parameter monitoring module, and a focusing module; the second impact optical path of the second laser includes a laser transmission module, an energy adjustment module, a laser parameter monitoring module, and a focusing module.

[0010] In one embodiment of the present invention, the control system integrates video monitoring for observing the laser shock processing status, and the camera of the video monitoring performs filtering processing corresponding to the laser wavelengths of the first laser and the second laser.

[0011] The device proposed in this invention can be used to perform any of the following processes: High-energy laser shock blasting is applied to the reinforced areas of the parts individually; Low-energy laser shock blasting is applied to the reinforced areas of the part separately; High-energy laser shock blasting or low-energy laser shock blasting is performed on different areas of the same part; High-energy laser shock strengthening and low-energy laser shock strengthening are applied to the same area of ​​the same part.

[0012] This invention also provides a method for laser shock peening of turbine blades, which operates on the aforementioned equipment and includes the following steps: The strengthening region is determined based on the fatigue fracture location of the turbine blade, and the strengthening region at least covers the crack initiation region. Based on the mechanical properties of turbine blade materials, high-energy and low-energy laser shock strengthening parameters were designed respectively, and the power density of low-energy laser shock was higher than that of high-energy laser shock. High-energy laser shock blasting was applied to the reinforced areas of the turbine blades. Low-energy laser shock strengthening is applied to areas of turbine blades that have undergone high-energy laser shock strengthening. Post-processing is performed on the reinforced areas of the turbine blades.

[0013] In one embodiment of the present invention, the process parameters for high-energy laser shock peening include a single pulse energy greater than 1J, a spot diameter greater than 2mm, a pulse width of 15-20ns, and an overlap rate greater than 30%. The process parameters for low-energy laser shock peening include a single pulse energy less than 100mJ, a spot diameter of 0.3-0.5mm, a pulse width of 5-10ns, and an overlap rate greater than 30%. Furthermore, the power density of the low-energy laser is at least 15% higher than that of the high-energy laser.

[0014] In one embodiment of the present invention, it further includes determining whether to attach an absorbent protective layer based on the processing requirements of the reinforced area of ​​the part, wherein the absorbent protective layer is made of black tape or aluminum foil.

[0015] In one embodiment of the present invention, the reinforced area of ​​the turbine blade is the tenon groove portion.

[0016] The beneficial effects of this invention are as follows: The composite laser shock peening device and the laser shock peening method for turbine blades proposed in this invention integrate high-energy and low-energy laser shock peening systems, motion systems, water-constrained loading systems, and control systems. This allows for the flexible implementation of multiple peening modes, addressing the multi-mode laser shock peening requirements of complex components. It can flexibly adapt to both high-energy and low-energy laser shock peening methods, meeting the multi-mode peening needs of complex components. Furthermore, this invention proposes a high- and low-energy composite peening method for turbine blades using the aforementioned device, simultaneously improving the fatigue performance and fretting wear resistance of turbine blades. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0018] In the attached diagram: Figure 1 This is a schematic diagram of the structure of a composite laser shock peening device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of an impact optical path provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the architecture of a control system provided in one embodiment of the present invention; Figure 4 This is a flowchart of a turbine blade size-energy composite laser shock strengthening method provided in one embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the turbine blade reinforcement region provided in one embodiment of the present invention; Figure 6 This is a comparison diagram of residual stress of turbine blades strengthened by different processes according to an embodiment of the present invention.

[0019] The attached figures are labeled as follows: 10. First laser; 20. Second laser; 30. Motion system; 40. Water-constrained loading system; 50. Control system; 51. Video monitoring; 60. Laser transmission module; 601. Base; 602. Light guide arm; 70. Laser parameter monitoring module; 80. Focusing module; 90. Focusing module; 100. Turbine blade; 101. Reinforced area; 102. Tenon and groove. Detailed Implementation

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0021] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0022] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0023] Traditional laser shock peening equipment typically has a single function, capable of only high-energy or low-energy processes. However, the fatigue fracture of many components (such as turbine blades) has complex causes, involving multiple fatigue modes, requiring a combination of strengthening methods to improve fatigue performance. This makes it difficult for existing equipment to simultaneously meet different process requirements, limiting its application scope and strengthening effect.

[0024] For this, please see Figures 1 to 6 , Figure 1 The composite laser shock peening device proposed in this application includes: The first laser 10 is configured to output a high-energy laser shock with a single pulse energy greater than 1J to the first target area under the transmission of the first shock optical path. The second laser 20 is configured to output a single pulse of low-energy laser energy in the tens to hundreds of mJ range to the second target region under the transmission of the second impact optical path. The motion system 30 is used to clamp the part and drive the impact-strengthening area of ​​the part to pass through the first target area and / or the second target area in sequence. Water-constrained loading system 40 is used to apply a water-constrained layer to the surface of the impact-strengthening area of ​​the part; The control system 50 is communicatively connected to the first laser 10, the second laser 20, the motion system 30, and the water constraint loading system 40, and controls the operating parameters of the first laser 10 and the second laser 20, the trajectory of the parts in the motion system 30, and the on / off state and pressure of the water constraint layer applied by the water constraint loading system 40.

[0025] For ease of understanding, the following explains some key terms in this embodiment: The first laser 10 and the first shock beam are configured to generate and guide a laser beam with a single pulse energy greater than 1J to perform high-energy laser shock blasting on a first target area of ​​the part. This high-energy laser shock blasting is typically used to pre-inflate residual compressive stress on the metal surface and at a certain depth, and can achieve a relatively deep residual compressive stress influence depth.

[0026] The second laser 20 and the second shock optical path are configured to generate and guide a laser beam with a single pulse energy in the range of tens to hundreds of mJ to perform low-energy laser shock blasting on a second target area of ​​the part. This low-energy laser shock blasting is typically used to generate high residual compressive stress on metal surfaces and can achieve surface grain refinement.

[0027] The motion system 30 is used to clamp the part to be processed and move it to a first target area or a second target area to facilitate laser shock strengthening operations at different energy levels. This system ensures that the laser shock is applied to the predetermined location on the part.

[0028] The water-constrained loading system 40 is used in laser shock processing to supply water to the surface of the workpiece through a water treatment device, thereby forming a water-constrained layer on the surface of the workpiece. This water-constrained layer can enhance the pressure of the plasma shock wave impacting the metal surface when the laser pulse is applied, thus improving the effect of laser shock strengthening.

[0029] The control system 50 is configured to communicate with the first laser 10, the second laser 20, the motion system 30, and the water-constrained loading system 40. This system is responsible for coordinating and managing the entire laser shock peening process, including setting the laser's operating parameters, planning the movement trajectory of the parts, controlling the application and pressure of the water-constrained layer, and integrating video monitoring 51 to observe the processing status and ensure the safety and quality of the processing.

[0030] This embodiment provides a composite laser shock peening device, the specific implementation of which is as follows: The first laser 10 and the first impact optical path are configured to output a high-energy laser impact with a single pulse energy greater than 1J to the first target region. For example, the first laser 10 can be an Nd:YAG laser, which is capable of generating high-energy laser pulses. The first impact optical path can consist of a series of mirrors, lenses, and beam shaping elements for transmitting the laser beam from the first laser 10 to the first target region and adjusting the size of the beam spot. This configuration allows for deep strengthening of large areas of parts or thick materials.

[0031] The second laser 20 and the second impact optical path are configured to output low-energy laser shocks with single-pulse energies in the tens to hundreds of mJ range to the second target region. For example, the second laser 20 can be an Nd:YAG laser or a fiber laser, which can generate laser pulses with low energy levels. The second impact optical path can consist of a mirror (as shown in the attached figure), a light guide arm (as shown in the attached figure), or an optical fiber (not shown in the attached figure), used to transmit the laser beam from the second laser 20 to the second target region and to focus the light spot. With this configuration, surface strengthening of specific areas of a part or materials with thinner thicknesses can be achieved.

[0032] The motion system 30 is used to clamp and move parts to a first target area or a second target area. For example, the motion system 30 can employ a platform with multi-axis linkage, using a combination of a motor-driven slide and a rotatable platform to adjust the position of the part in three-dimensional space. The part is fixed on a fixture, which is then mounted on the motion system 30, allowing the part to be moved to different laser impact areas.

[0033] The water confinement loading system 40 is used to apply a water confinement layer by supplying water through a water treatment device. For example, the water treatment device may include a water tank, a water pump, and a water supply pipeline. The water pump draws water from the tank and delivers it through the water supply pipeline to a nozzle in a first or second target area, forming a water film or column on the surface of the part. This water film or column serves to confine the plasma during laser shock.

[0034] The control system 50 is configured to communicate with the first laser 10, the second laser 20, the motion system 30, and the water-constrained loading system 40. (See also...) Figure 3 The control system 50 can be a computer-based control platform that exchanges data and sends commands to various hardware modules via a programmable logic controller (PLC). For example, the control system 50 can set the pulse energy, pulse width, and frequency of the first laser 10, as well as the pulse energy, pulse width, and frequency of the second laser 20. Simultaneously, the control system 50 can plan the path and speed of the moving parts in the motion system 30, and, based on the clock signals controlling the first laser 10 and the second laser 20, coordinate with the motion system 30 to move the parts to be processed to the corresponding target area, and control the water supply switch and water pressure of the water constraint loading system 40. Furthermore, the control system 50 integrates video monitoring 51, for example, transmitting images to the control interface via a camera installed in the processing area, allowing operators to observe the laser impact processing status and ensure the safety of the processing process.

[0035] The composite laser shock peening equipment of this embodiment integrates both high-energy and low-energy laser shock peening functions, and, in conjunction with the motion system 30, water-constrained loading system 40, and control system 50, solves the problem of existing equipment having limited functionality and being unable to meet the strengthening needs of complex components (such as turbine blades 100) with multiple fatigue failure modes. Therefore, this equipment can perform composite laser shock peening on parts, achieving residual compressive stress pre-fabrication at different depths and intensities on the same equipment, thereby comprehensively improving the mechanical properties of parts, such as fatigue resistance, stress corrosion resistance, and fretting wear resistance, and extending their service life.

[0036] In some embodiments described above, a composite laser shock peening device is proposed, which integrates high-energy and low-energy laser shock capabilities and is equipped with a motion system 30, a water-constrained loading system 40, and a control system 50 to achieve flexible processing of parts. However, in practical applications, when the processing frequency exceeds 20Hz, the constraint layer cannot be established in time when using the direct water spraying method to form a water film. Therefore, a water-optical coaxial loading method is generally used to load the water constraint layer. Comparing the absorption rates of water for 1064nm and 532nm wavelength lasers, 532nm wavelength lasers are generally used when the processing frequency exceeds 20Hz. Low-energy lasers, due to their low single-pulse energy and small focused spot size, typically require processing frequencies exceeding 20Hz for processing efficiency.

[0037] In this regard, this application further proposes that the output wavelength of the first laser 10 is 1064nm and the output wavelength of the second laser 20 is 1064nm or 532nm.

[0038] Specifically, the first laser 10 is configured to output high-energy laser shock with a single pulse energy greater than 1J, and its output wavelength is set to 1064nm. The 1064nm wavelength is a typical output wavelength for industrial high-power lasers (such as Nd:YAG lasers). This wavelength has good absorption characteristics in various metallic materials, enabling efficient conversion of laser energy into plasma shock waves, thereby achieving deep, large-area shock strengthening effects. Choosing the 1064nm wavelength helps ensure that high-energy laser shock can achieve stable and effective strengthening depth and intensity on a wide range of metallic parts.

[0039] Meanwhile, the second laser 20 is configured to output low-energy laser shocks with single-pulse energy in the tens to hundreds of mJ range, and its output wavelength can be selected as 1064nm or 532nm. When the processing frequency of the second laser 20 is ≤20Hz, 1064nm is selected to maintain wavelength consistency with the first laser 10, which helps simplify the design and maintenance of the optical system. When the processing frequency of the second laser 20 is >20Hz, 532nm is selected. This wavelength is a frequency-doubled wavelength of 1064nm, has shorter wavelength characteristics, can achieve a coaxial water-optical mode, and the constraint layer can be easily established to ensure better strengthening effect.

[0040] Through the aforementioned technical solution, by specifying the output wavelength separately or flexibly for high-energy and low-energy laser shocks, this equipment can effectively guarantee the strengthening effect. The 1064nm wavelength ensures deep and effective strengthening of most metallic materials in high-energy shocks, while the choice between 1064nm or 532nm in low-energy shocks provides flexibility for different processing frequency requirements. In particular, the introduction of the 532nm wavelength allows the equipment to handle high repetition rates, ensuring both processing efficiency and shock effect. This optimized wavelength configuration enables the composite laser shock strengthening equipment to be applied more efficiently and precisely to various materials and strengthening scenarios, improving processing quality and process adaptability.

[0041] In composite laser shock peening equipment, it is necessary to simultaneously achieve both high-energy and low-energy laser shock peening to meet different strengthening requirements. However, without precise configuration of the two laser shock peening optical paths, it may be difficult to ensure accurate control of laser energy, stable output of laser spot quality, and real-time monitoring of the processing, thereby affecting the uniformity and reliability of the strengthening effect.

[0042] For this, please see Figure 1 This application further proposes that the first impact optical path of the first laser 10 includes a laser transmission module 60, an energy adjustment module, a laser parameter monitoring module 70, and a focusing module 80; the second impact optical path of the second laser 20 includes a laser transmission module 60, an energy adjustment module, a laser parameter monitoring module 70, and a focusing module 90.

[0043] The laser transmission module 60 is used to efficiently and stably transmit the laser beam emitted by the laser to the target area. This module can be implemented in various forms. For example, for high-energy lasers, a series of high-reflectivity mirrors can be used to achieve high-energy-density laser transmission; for lower-energy lasers, an optical fiber transmission system can be used to achieve a flexible and compact optical path; and other methods can be employed as shown in the attached diagram. Figure 2 The illustrated light guide arm 602 structure, by mounting the light guide arm 602 on a base 601 equipped with an optical path receiving and guiding structure, and utilizing the multi-degree-of-freedom adjustment channel of the light guide arm 602, allows for flexible and stable adjustment of the laser's optical path output direction and position. The energy adjustment module is used to precisely adjust the single-pulse energy of the output laser according to preset process parameters. This can be achieved through a combination of a half-wave plate and a polarization beam splitter, or an electro-optic modulator, ensuring that the laser energy can be finely controlled according to the material to be processed and the required strengthening depth. The laser parameter monitoring module 70 is responsible for real-time monitoring of key laser beam parameters, such as energy, pulse width, and beam quality. This module typically includes sensors such as an energy meter, oscilloscope, and beam analyzer, and feeds the monitoring data back to the control system 50 for timely adjustment and optimization of the laser impact process.

[0044] For the high-energy laser impact of the first laser 10, the focusing module 80 configured in its first impact optical path is mainly used to flexibly adjust the size and focal position of the laser spot. This module is usually composed of a movable lens group or a zoom lens, which can adjust the laser beam to a suitable focal length and spot diameter according to the size and shape of the strengthening region 101 to achieve different process requirements. For the low-energy laser impact of the second laser 20, the focusing module 90 configured in its second impact optical path is designed to focus the laser beam into an extremely small spot to obtain extremely high power density. This module usually uses a focusing lens with a short focal length to achieve fine, high-intensity impact strengthening of small areas or specific defect locations with a small focused spot.

[0045] Through the above technical solution, specialized and optimized shock beam modules are configured for the first laser 10 and the second laser 20, respectively, enabling independent and precise control of high-energy and low-energy laser shocks. The laser transmission module 60 ensures effective laser energy transmission, the energy adjustment module allows for precise adjustment of laser energy according to process requirements, and the laser parameter monitoring module 70 provides real-time feedback, ensuring the stability of the processing. In particular, the focusing module 80, used for high-energy shocks, can flexibly adjust the spot size to adapt to different process requirements; while the focusing module 90, used for low-energy shocks, can achieve a small spot with high power density, ensuring precise strengthening of localized areas. This configuration significantly improves the adaptability, processing accuracy, and reliability of the strengthening effect of the composite laser shock strengthening equipment to different strengthening needs, thereby more effectively solving the problem of fatigue fracture in parts and extending their service life.

[0046] In some embodiments described above in this application, a composite laser shock peening device is proposed, wherein the motion system 30 is used to clamp and move parts to a first target area or a second target area. However, in practical applications, how to efficiently and flexibly schedule and position parts between laser shock peening areas of different energies to adapt to different processing requirements and improve overall production efficiency is a problem that needs to be solved.

[0047] In this regard, this application further proposes that the motion system 30 uses one set of robotic arms to move the part to the first target area or the second target area, or uses two sets of robotic arms to move the part to the first target area and the second target area respectively.

[0048] Specifically, when the motion system 30 employs a robotic arm, this arm is typically a multi-joint robot, such as a six-axis robot, with a gripper at its end capable of stably holding the part to be processed. Through preset motion trajectories and programmed control, the robotic arm can pick up the part from the loading position and precisely move and position it to a first target area for high-energy laser shock blasting, or to a second target area for low-energy laser shock blasting. After completing the processing of one area, the robotic arm can move the part again, positioning it in another area for subsequent processing, or moving it to the unloading position. This configuration makes the equipment structure relatively compact and cost-effective, suitable for scenarios where processing cycle requirements are not high or where different stages of shock blasting are required for the same part.

[0049] On the other hand, when the motion system 30 employs two sets of robotic arms, the equipment is equipped with two independent robotic arm systems, each specifically responsible for the handling and positioning of parts in a particular processing area. For example, the first set of robotic arms can be responsible for moving parts from the loading area to the first target area and removing them after processing; the second set of robotic arms is independently responsible for moving parts from the loading area (or intermediate buffer area) to the second target area and removing them after processing. These two sets of robotic arms can work in parallel without interfering with each other. For example, while the first target area is undergoing high-energy laser shock blasting, the second target area can simultaneously perform low-energy laser shock blasting on different parts or different parts of the same part. This configuration typically requires a more complex control system 50 to coordinate the movements of the two sets of robotic arms to avoid collisions and ensure a smooth processing flow.

[0050] Through the above technical solution, the motion system 30 can flexibly choose to use one or two robotic arms to move parts according to actual processing needs. When using one robotic arm, sequential movement and positioning of parts between the first and second target areas can be achieved, effectively reducing equipment costs and complexity. When using two robotic arms, parallel processing of parts in the two target areas can be achieved, that is, laser shock strengthening can be performed on different parts or different parts of the same part simultaneously in the first and second target areas, thereby significantly improving the overall processing efficiency and production throughput of the equipment, and effectively solving the technical problem of efficient and flexible scheduling and positioning of parts in composite laser shock strengthening equipment. This configuration allows the equipment to better adapt to diverse production needs and optimizes the processing flow.

[0051] In some embodiments described above in this application, a composite laser shock peening device is proposed, wherein the water-constrained loading system 40 is used to apply a water-constrained layer by supplying water through a water treatment device. However, in practical applications, this device usually needs to perform laser shock peening simultaneously or alternately in two different target areas. How to efficiently, flexibly, and reliably provide a stable water supply for the water-constrained layer to these two target areas to adapt to different processing needs and production scales is a problem that needs to be solved.

[0052] In this regard, this application further proposes that the water treatment equipment uses one water purifier to supply water to the parts to be processed in two target areas in two separate ways, or uses two water purifiers to supply water to the parts to be processed in two target areas respectively.

[0053] Specifically, a water purifier is a core component of water treatment equipment. Its main function is to purify, filter, deaerate, and pressurize tap water or circulating water according to the water quality and pressure requirements of the laser shock osmosis method, ensuring that the supplied water source meets the conditions for the formation of the water confinement layer. For example, a water purifier may include components such as a reverse osmosis membrane, ion exchange resin, precision filter, and booster pump to provide a high-purity, bubble-free, and pressure-stable water flow.

[0054] When a water treatment system uses a single water generator to supply water to two target areas for processing parts, one water generator is responsible for both processing and supplying the water source. This water generator uses internal or external diversion devices, such as diversion valves, manifolds, or independent pumping circuits, to split the treated water into two streams, delivering them to the first and second target areas respectively. This approach allows the two target areas to share the same water treatment unit, offering advantages in equipment cost and floor space, and is particularly suitable for scenarios where the two target areas do not require completely independent or simultaneous high-intensity water supply.

[0055] When the water treatment equipment uses two water generators to supply water to the parts to be processed in two target areas respectively, the equipment is equipped with two independent water generators. Each water generator is dedicated to supplying water to one target area; for example, one water generator serves the first target area and the other serves the second target area, providing the treated water required for the water constraint layer. This configuration provides a high degree of independence and flexibility, allowing for independent control and optimization of water quality, water pressure, and flow rate in each target area. It also improves system redundancy; even if one water generator fails, the other can continue to operate, ensuring partial production capacity.

[0056] Through the above technical solutions, the water-constrained loading system 40 can flexibly select the configuration of water treatment equipment according to actual processing needs and production scale. When using one water generator to supply water from two sources, the initial investment and operating costs of the equipment can be effectively reduced, while saving space, making it suitable for cost- and space-sensitive composite processing scenarios. When using two water generators to supply water separately, completely independent and controllable water sources can be provided for two target areas, thereby achieving more precise process control and higher processing efficiency, especially suitable for scenarios that require simultaneous high-intensity processing or have different strict requirements for water quality and pressure. This selectable configuration significantly improves the adaptability, reliability, and economy of the composite laser shock peening equipment in terms of water constraint layer supply, ensuring the stable application of the water constraint layer under different processing modes, and thus guaranteeing the uniformity and consistency of the laser shock peening effect.

[0057] In composite laser shock peening equipment, a video monitoring system is typically integrated to monitor the laser shock processing status in real time. However, during the laser shock peening process, the high-energy laser beams emitted by the first laser 10 and the second laser 20, as well as the plasma emission and scattered light generated by their interaction with the workpiece, produce strong background light. This intense light may directly enter the camera, causing overexposure and blurring of the image, and may even damage the camera's photosensitive element. This severely affects the effective observation of the processing area by the video monitoring system, making it difficult for operators or the control system 50 to accurately judge the processing status and effect.

[0058] To address this, this application proposes an improved video monitoring solution 51. The control system integrates a video monitoring system 51 for observing the laser impact processing status. The camera in the video monitoring system 51 performs filtering processing corresponding to the laser wavelengths of the first laser 10 and the second laser 20. Specifically, the camera is the core component of the video monitoring system 51, its function being to convert real-time image information of the laser impact processing area into electrical signals and transmit them to the control system 50 for display and analysis. The camera is typically installed near the processing area and protected by an optical window or protective cover to avoid direct damage from the laser or splashes. Filtering processing refers to introducing an optical filter into the imaging optical path of the camera. This filter can selectively transmit or block light of specific wavelengths. Specifically, the filter is designed to effectively block or significantly attenuate the laser wavelengths (e.g., 1064nm or 532nm) emitted by the first laser 10 and the second laser 20, while allowing other wavelengths of visible light to pass through.

[0059] By employing the aforementioned technical solution, filtering the laser wavelengths corresponding to the first laser 10 and the second laser 20 on the camera of the video surveillance 51 effectively filters out the strong laser beams and scattered light generated during the laser shock process. This avoids problems such as image overexposure and blurring caused by strong light irradiation and protects the camera's photosensitive element from damage. This enables the control system 50 to obtain clear and accurate real-time images of the processing area, greatly improving the effectiveness and reliability of the video surveillance 51 system in observing the laser shock processing status. Based on these high-quality images, operators or the control system 50 can more accurately determine the application of the water constraint layer, the formation process of the laser shock points, and the overall state of the processing area, thereby achieving refined monitoring and timely adjustment of the composite laser shock strengthening process, ensuring processing quality and equipment operational safety.

[0060] In some of the embodiments described above in this application, a composite laser shock peening device is proposed, capable of providing both high-energy and low-energy laser shocks. However, in practical applications, how to efficiently and accurately utilize this device to achieve the best strengthening effect for the specific needs of complex parts remains a challenge. Without a systematic process flow, improper selection of the strengthening area 101 and unreasonable design of process parameters may occur, thereby affecting the uniformity, depth, and surface integrity of the strengthening effect, and failing to fully realize the advantages of the composite laser shock peening device.

[0061] For this, please see Figure 4 This application proposes a laser shock blasting method for turbine blades 100, implemented using the aforementioned equipment, comprising the following steps: determining the strengthening region 101 of the turbine blade 100 based on the fatigue fracture location, wherein the strengthening region 101 at least covers the crack initiation region; designing high-energy and low-energy laser shock blasting method parameters based on the mechanical properties of the turbine blade 100 material, wherein the power density of the low-energy laser shock blasting is higher than that of the high-energy laser shock blasting; performing high-energy laser shock blasting on the strengthening region 101 of the turbine blade 100; performing low-energy laser shock blasting on the region strengthened by high-energy laser shock blasting; and performing post-processing on the strengthening region 101 of the turbine blade 100.

[0062] In this process, the strengthening region 101 of the turbine blade 100 is determined based on the fatigue fracture location, and the strengthening region 101 at least covers the crack initiation region. This step aims to accurately locate the area of ​​the component most prone to fatigue failure. Specifically, potential fatigue fracture locations can be identified through structural analysis, stress concentration area assessment, and fatigue testing of the turbine blade 100. The determination of the strengthening region 101 should ensure that it completely covers or extends beyond the crack initiation region, i.e., the microscopic or macroscopic region where fatigue cracks are most likely to initiate and propagate. This is the basis for ensuring that laser shock peening can act on the most critical parts, fundamentally improving the fatigue resistance of the turbine blade 100.

[0063] Based on the mechanical properties of the blade material, parameters for high-energy and low-energy laser shock peening methods were designed separately, with the power density of low-energy laser shock peening being higher than that of high-energy laser shock peening. This step emphasizes the customization and refinement of process parameter design. The mechanical properties of the blade material, such as yield strength, tensile strength, hardness, and toughness, directly affect its response to laser shock. Therefore, it is necessary to design process parameters such as single-pulse energy, spot diameter, pulse width, overlap rate, and number of impacts separately for different material characteristics and considering the different mechanisms of action of high-energy laser shock peening (usually used to achieve deeper residual compressive stress and improve fatigue resistance) and low-energy laser shock peening (usually used to achieve high-strength surface strengthening and grain refinement, and improve fretting wear resistance). Low-energy laser shock peening, by focusing energy into a smaller spot size, generates higher power density in a local area, achieving higher surface hardness and more significant surface residual compressive stress, which is particularly crucial for resisting fretting wear.

[0064] High-energy laser shock peening is performed on the strengthening region 101 of the turbine blade 100; low-energy laser shock peening is then performed on the region that has undergone high-energy laser shock peening. This step is the core execution link of laser shock peening. After determining the strengthening region 101 and designing the process parameters, a composite laser shock peening device is used to shock the designated area of ​​the part.

[0065] Post-processing is performed on the reinforced area 101 of the turbine blade 100. This post-processing is a crucial step in ensuring the reinforcement effect and the final quality of the turbine blade 100. After laser shock peening, the part surface may have water stains, a slight oxide layer, or minor ablation marks. Post-processing may include, but is not limited to: cleaning (such as ultrasonic cleaning or deionized water cleaning) to remove surface residues; light surface polishing or grinding to improve surface roughness; and necessary quality inspections (such as residual stress testing, surface morphology inspection, and hardness testing) to verify the reinforcement effect and surface integrity. This step aims to eliminate potential negative impacts and ensure that the part meets the requirements for subsequent assembly and use.

[0066] Through the above technical solution, this application systematically addresses the challenges faced in the composite laser shock strengthening process of turbine blades. First, by precisely defining the strengthening region 101 and covering the crack initiation area, it ensures that the laser shock energy acts on the most critical fatigue-sensitive parts, suppressing crack initiation at its source. Second, by customizing the high- and low-energy laser shock process parameters according to the mechanical properties of the blade material, it meets the different strengthening effect requirements of the turbine blades. This refined parameter design fully leverages the advantages of different lasers in the composite laser shock strengthening equipment, avoiding the limitations of single-energy shocks. Finally, by implementing necessary post-processing on the strengthened region 101, the surface quality and overall performance of the turbine blades are further optimized. Overall, this process makes the application of composite laser shock strengthening equipment more efficient and precise, significantly improving the fatigue resistance and service life of parts, and ensuring the reliability and stability of the strengthening effect.

[0067] This application further proposes process parameters for high-energy laser shock peening, including single-pulse energy greater than 1J, spot diameter greater than 2mm, pulse width 15-30ns, and overlap rate greater than 30%, and process parameters for low-energy laser shock peening, including single-pulse energy less than 100mJ, spot diameter 0.3-0.5mm, pulse width 5-10ns, and overlap rate greater than 30%, and the power density of low-energy laser is at least 15% higher than that of high-energy laser.

[0068] Specifically, for high-energy laser shock peening, the single-pulse energy is greater than 1J, and the spot diameter is greater than 2mm. The high-energy pulse and large spot diameter can induce deeper residual compressive stress within the material, effectively suppressing the initiation and propagation of fatigue cracks. The pulse width is 15-30ns. Laser pulses within this range can effectively form plasma on the material surface and generate shock waves of appropriate duration, ensuring that energy is fully transferred into the material, forming a deep and stable residual compressive stress field. The overlap rate is greater than 30%, ensuring effective coverage and overlap between adjacent impact areas, thereby forming a continuous and uniform residual compressive stress layer within the entire strengthened region 101, avoiding unstrengthened areas 101 or uneven strengthening.

[0069] For low-energy laser shock peening, the single-pulse energy is less than 100 mJ, the spot diameter is 0.3-0.5 mm, and the pulse width is 5-10 ns. The low-energy, small-spot, and short-pulse-width pulsed laser acts on the material surface, resulting in a shallow influence layer and a short shock wave propagation distance. This leads to high-intensity residual compressive stress and increased hardness on the surface. Simultaneously, a remelted layer is formed on the surface, further enhancing the surface material's hardness and improving its resistance to fretting wear. An overlap rate greater than 30% is also crucial for low-energy shock peening, ensuring complete coverage and uniformity of the finely strengthened area 101, especially when dealing with complex geometries or microscopic defects. Furthermore, the power density of the low-energy laser is explicitly required to be at least 15% higher than that of the high-energy laser. This is because high-energy peening increases the material's surface hardness and yield strength; therefore, when performing low-energy peening on top of this, the power density needs to be increased accordingly to ensure that a certain degree of plastic deformation still occurs, thereby generating residual compressive stress.

[0070] Through the above technical solutions, the specific process parameters for high-energy laser shock peening and low-energy laser shock peening are precisely defined, enabling the two different energy levels of laser shock peening to each perform their respective functions and exert their unique strengthening advantages, significantly improving the surface hardness, wear resistance, and crack initiation resistance of materials. This refined parameter design allows the composite laser shock peening method to provide more precise and efficient strengthening strategies for different failure mechanisms of parts, thereby significantly improving the overall performance and service reliability of parts, and effectively avoiding problems such as poor strengthening effect or local over-strength / under-strength caused by improper parameter design.

[0071] This application further proposes that, during high-energy laser shock peening, the presence or absence of an absorption protective layer should be determined based on the processing requirements of the blade strengthening area, with the absorption protective layer being either black tape or aluminum foil; and that no absorption protective layer should be used for low-energy laser shock peening.

[0072] Specifically, the absorbing protective layer is mainly used to protect the surface of the part from direct laser ablation and to enhance the absorption efficiency of laser energy, thereby ensuring the stable generation of plasma shock waves. Depending on the blade processing requirements, black tape or aluminum foil can be used as the absorbing protective layer during high-energy intensive impact to meet surface roughness requirements. However, the absorbing protective layer is not used during low-energy intensive impact because low-energy intensive impact requires a small spot size and high frequency laser to directly interact with the blade surface to generate a remelted layer, further increasing surface hardness.

[0073] Please see the appendix Figure 5 This application further proposes that in the above-mentioned process method, the reinforced area 101 of the turbine blade 100 is the tenon groove 102 part.

[0074] Turbine blade 100 is a critical rotating component in core power units such as aero-engines and gas turbines. Its operating environment is extreme, subjected to high temperature, high pressure, high-speed airflow impact, and complex alternating loads, making it highly susceptible to fatigue damage. The tenon groove 102 is a key structural element connecting the turbine blade 100 to the rotor disk. Its complex geometry and severe stress concentration make it one of the areas most prone to fatigue crack initiation and propagation. Furthermore, fretting wear also exists in this area, often a significant cause of fracture failure. Laser shock peening requires consideration of both factors and targeted strengthening.

[0075] Furthermore, strengthening the tenon groove 102 requires precise control of the laser impact position and parameters to ensure sufficient residual compressive stress in this high-stress area, thereby effectively suppressing the initiation and propagation of fatigue cracks. This typically necessitates a precise assessment of stress distribution using methods such as finite element analysis, and the precise positioning and scanning of the laser spot achieved through the motion system 30.

[0076] By applying the above technical solution to the tenon 102 part of the key component turbine blade 100, the composite laser shock strengthening method can achieve a highly targeted strengthening effect and effectively solve the problems of fatigue failure and fretting wear in high stress concentration areas.

[0077] The following example will provide a more detailed explanation of the above technical solution: As a critical load-bearing component, the turbine blade 100's tenon 102 is prone to fatigue fracture during service due to stress concentration and fretting wear. Traditional laser shock peening equipment typically only provides single high-energy or low-energy shock peening functions, making it difficult to comprehensively address the complex fatigue failure issues at the tenon 102 of the turbine blade 100. For example, high-energy shock peening can generate a deep residual compressive stress layer, effectively improving stress concentration, but its improvement on surface fretting wear is limited; while low-energy shock peening can improve surface hardness and residual compressive stress, its impact depth is shallow. To address this limitation of equipment simplification and effectively improve the fatigue performance of the turbine blade 100, a composite laser shock peening equipment is used for appropriate treatment.

[0078] This composite laser shock blasting equipment integrates multiple functions, enabling high-energy and / or low-energy composite laser shock blasting of turbine blades 100. Specifically, the equipment includes a first laser 10 and its matching first shock optical path. The first laser 10 is configured to output a high-energy laser shock with a single pulse energy greater than 1J to a first target area. The first shock optical path includes a laser transmission module 60, an energy adjustment module, a laser parameter monitoring module 70, and a focusing module 80 to ensure stable transmission and precise control of the high-energy laser. Simultaneously, the equipment also includes a second laser 20 and its matching second shock optical path. The second laser 20 is configured to output a low-energy laser shock with a single pulse energy in the hundreds of mJ range to a second target area. The second shock optical path also includes a laser transmission module 60, an energy adjustment module, a laser parameter monitoring module 70, and a focusing module 90 to achieve fine focusing of the low-energy laser. For example, the first laser 10 can output a laser with a wavelength of 1064nm, while the second laser 20 can output a laser with a wavelength of 1064nm or 532nm to adapt to different process requirements.

[0079] To achieve precise machining of the turbine blade 100, the equipment is equipped with a motion system 30. This motion system 30 uses a robotic arm to grip the turbine blade 100 and precisely move it to a first target area or a second target area. Through the coordinated movement of the robotic arm, different reinforcement areas 101 of the turbine blade 100 can be sequentially subjected to high-energy or low-energy laser shock treatment, or even undergo combined treatment in the same area.

[0080] A water confinement layer is indispensable in laser shock peening. Therefore, the equipment also includes a water confinement loading system 40, which supplies water to the turbine blades 100 to be processed in the first and second target areas via a water generator to apply the water confinement layer. The presence of the water confinement layer can effectively increase the shock wave pressure of the laser-induced plasma, thereby enhancing the strengthening effect.

[0081] The entire operation of the equipment is managed by a central control system 50. This control system 50 communicates with the first laser 10, the second laser 20, the motion system 30, and the water-constrained loading system 40 to achieve precise control of all key parameters. The control system 50 can control the operating parameters of the first laser 10 and the second laser 20, such as laser energy, pulse width, and frequency; control the trajectory of the turbine blades 100 in the motion system 30 to ensure that the laser impact covers the preset reinforcement area 101; and control the on / off switching and pressure of the water-constrained loading system 40 to apply the water constraint layer. In addition, the control system 50 also integrates a video monitoring function 51, which uses cameras equipped with corresponding laser wavelength filtering to observe the laser impact processing status in real time, ensuring the safety and quality of the processing.

[0082] In practical applications, such as strengthening the tenon 102 portion of the GH4169 turbine blade 100, the control system 50 first designs the parameters for high-energy and low-energy laser shock blasting strengthening methods based on the mechanical properties of the blade material. For example, the process parameters for high-energy laser shock blasting strengthening are set as follows: single-pulse energy 7J, spot diameter 3mm, pulse width 20ns, and overlap rate 50%; the process parameters for low-energy laser shock blasting strengthening are set as follows: single-pulse energy 80mJ, spot diameter 0.4mm, pulse width 10ns, and overlap rate 50%. The control system 50 ensures that the power density of the low-energy laser is at least 15% higher than that of the high-energy laser to accommodate the hardening of the surface material after high-energy strengthening.

[0083] Subsequently, the motion system 30 clamps the turbine blade 100 and moves it to the first target area. The control system 50 retrieves a preset high-energy laser shock blasting strengthening processing path and controls the water-constrained loading system 40 to apply a water-constrained layer. The first laser 10 performs high-energy laser shock blasting strengthening on the strengthening area 101 of the tenon 102 of the turbine blade 100 according to the path to generate a deeper residual compressive stress layer and improve stress concentration. After the high-energy strengthening is completed, the motion system 30 moves the turbine blade 100 to the second target area. The control system 50 retrieves a preset low-energy laser shock blasting strengthening processing path and again controls the water-constrained loading system 40 to apply a water-constrained layer. The second laser 20 performs low-energy laser shock blasting strengthening on the strengthened area 101 of the tenon 102 of the turbine blade 100 that has completed high-energy strengthening to form higher residual compressive stress and hardness on the surface, improving resistance to fretting wear. The entire processing process is monitored in real time by the video monitoring system 51.

[0084] Compared to existing technologies with only single-function laser shock blasting equipment, this composite equipment integrates high- and low-energy laser shock blasting functions and coordinates them under a unified control system 50, enabling multi-dimensional and refined strengthening of complex parts on a single platform. This integrated design not only significantly reduces the equipment's footprint and manufacturing costs, but more importantly, it allows for flexible selection and combination of high- and low-energy shock blasting processes based on the failure mechanisms of different areas of the part, thereby comprehensively improving the fatigue life of the part and solving complex strengthening needs that cannot be addressed by a single device. After processing, the control system 50 can also coordinate subsequent post-processing steps such as cleaning or polishing.

[0085] Appendix Figure 6The influence of different laser shock peening methods on the residual stress distribution of GH4169 turbine blades is visually demonstrated. The synergistic advantages of the composite process in improving fatigue life are verified by comparing residual stress test results with those of a single process. The figure includes residual stress curves for a single high-energy process, a single low-energy process, and a composite process of high and low energy, with differences presented through depth-stress curves. The curve for a single high-energy process (such as the 7J energy in the example) shows a deeper residual compressive stress layer, reaching approximately 2 mm, but with a relatively low surface stress peak. A single low-energy process (such as 80 mJ energy) shows a higher surface stress peak and a shallower influence layer, approximately 1 mm. The composite process curve combines the characteristics of both, exhibiting a higher compressive stress peak in the surface region while maintaining a strong compressive stress distribution in the deeper region, reflecting the synergistic effect of the high-energy-then-low-energy processing sequence.

[0086] Multiple processes can be flexibly integrated through composite laser shock peening equipment. (Attached) Figure 6 The data in the figures verify the rationality of the process parameter design in the embodiments of this application. For example, the requirement that the power density of low energy should be more than 15% higher than that of high energy ensures that plastic deformation can still be induced after initial strengthening. It also reflects the reliability of the automated control system 50, such as coordinating the movement of the robotic arm, laser parameters, and the application of the water constraint layer through preset paths, thereby ensuring the repeatability and accuracy of the composite process. The curves in the attached figures confirm the effectiveness of the composite process in solving the fatigue problem of the tenon and groove 102 of the turbine blade 100. High-energy strengthening suppresses crack initiation caused by stress concentration, while low-energy strengthening improves the resistance to fretting wear through the surface remelting layer. The combination of the two extends the blade's service life to a greater extent. This not only enhances the credibility of the beneficial effects of the invention in a visual form but also provides data support for the composite development of laser shock strengthening technology. It shows that compared with traditional single processes, the composite method can optimize the residual stress distribution more comprehensively, and is especially suitable for components with extremely high fatigue performance requirements.

[0087] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A composite laser shock peening device, characterized in that, include: A first laser, wherein the laser of the first laser is configured to output a high-energy laser shock with a single pulse energy greater than 1J to a first target region under the transmission of a first shock optical path; The second laser is configured to output a low-energy laser shock with a single pulse energy in the tens to hundreds of mJ range to the second target region under the transmission of the second shock optical path. A motion system for clamping a part and driving the impact-strengthening area of ​​the part to pass sequentially through a first target area and / or a second target area; A water-constrained loading system is used to apply a water-constrained layer to the surface of the impact-strengthening area of ​​the part. The control system is communicatively connected to the first laser, the second laser, the motion system, and the water constraint loading system, and controls the operating parameters of the first laser and the second laser, the trajectory of the parts in the motion system, and the switching and pressure of the water constraint layer applied by the water constraint loading system.

2. The device according to claim 1, characterized in that, The first laser has an output wavelength of 1064nm, and the second laser has an output wavelength of 1064nm or 532nm.

3. The device according to claim 1, characterized in that, The control system integrates video monitoring for observing the laser shock processing status. The camera of the video monitoring system has been filtered to correspond to the laser wavelengths of the first laser and the second laser.

4. A method for laser shock peening of turbine blades, using the equipment described in any one of claims 1-3, characterized in that, Includes the following steps: The strengthening region is determined based on the fatigue fracture location of the turbine blade, and the strengthening region at least covers the crack initiation region. Based on the mechanical properties of turbine blade materials, high-energy and low-energy laser shock strengthening parameters were designed respectively, and the power density of low-energy laser shock was higher than that of high-energy laser shock. High-energy laser shock blasting was applied to the reinforced areas of the turbine blades. Low-energy laser shock strengthening is applied to areas of turbine blades that have undergone high-energy laser shock strengthening. Post-processing is performed on the reinforced areas of the turbine blades.

5. The method according to claim 4, characterized in that, The process parameters for high-energy laser shock peening include single-pulse energy greater than 1J, spot diameter greater than 2mm, pulse width 15-30ns, and overlap rate greater than 30%.

6. The method according to claim 4, characterized in that, The process parameters for low-energy laser shock peening include single-pulse energy less than 100 mJ, spot diameter 0.3-0.5 mm, pulse width 5-10 ns, and overlap rate greater than 30%.

7. The method according to claim 4, characterized in that, The power density of low-energy lasers is at least 15% higher than that of high-energy lasers.

8. The method according to claim 4, characterized in that, The process of high-energy laser shock peening includes determining whether to apply an absorption protective layer based on the processing requirements of the turbine blade strengthening area; the absorption protective layer uses black tape or aluminum foil. The process of low-energy laser shock peening does not have an absorption protective layer.

9. The method according to claim 4, characterized in that, The reinforced area of ​​the turbine blade is the tenon groove.

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