Combined machining method and system based on water jet and laser dual-mode coupling

Abstract

The invention discloses a combined machining method and system based on water jet and laser dual-mode coupling. The method comprises the following steps: generating a stable high-pressure water jet; injecting a pulse laser beam into the water jet in a coupling manner, and conducting the pulse laser beam to the surface of a workpiece by using a total internal reflection principle; and laser parameters are controlled, so that double functions of a light guide medium and a restraint layer are realized at the same time by utilizing the water jet under the same or time-sequence-divided pulse action, and integrated operation of water-guided laser precision machining and laser shock peening is implemented on a workpiece. The system comprises a laser generating device, a water jet generating device, a light path coupling device, a monitoring control unit and a multi-axis motion platform. The problems of low efficiency, poor precision consistency and the like caused by separation of water-jet guided laser precision machining and laser shot peening strengthening procedures in the prior art are solved, and high-precision and high-efficiency water-jet guided laser machining and surface laser shot peening strengthening on complex parts in a single system are achieved.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, specifically to a composite processing method and system based on dual-mode coupling of water jet and laser, and more particularly to a composite processing method and system that utilizes the same water jet to simultaneously achieve laser conduction and plasma confinement. Background Technology

[0002] Water-guided laser processing technology is a method that uses micro-water jets as "optical waveguides" to conduct high-energy laser light for precision machining. Due to its advantages such as small heat-affected zone, narrow kerf, no pollution, and ability to process microstructures with high aspect ratios, it is widely used in precision micromachining in fields such as semiconductors, medical devices, and aerospace.

[0003] Laser shock peening is a surface engineering technique that uses high-power-density pulsed laser-induced high-pressure plasma shock waves to modify and strengthen the surface of metallic materials. This technique can introduce a deep and stable residual compressive stress layer on the material surface, significantly improving the fatigue resistance, wear resistance, and stress corrosion cracking resistance of metal parts. In this technique, a constraint layer (usually a flow layer) is typically applied to the workpiece surface to constrain the plasma expansion, thereby significantly increasing the pressure and duration of the shock wave.

[0004] Currently, the two technologies mentioned above are independent processes. In practical applications, it is often necessary to first use water-guided lasers to perform precision machining on parts (such as drilling and cutting), and then use laser impact peening technology to strengthen critical areas (such as hole edges and cuts) after machining. This separate process has many drawbacks: 1. Numerous steps, long production cycle, and low efficiency; 2. Requires two independent equipment systems, large footprint, and high investment and maintenance costs; 3. Errors are easily generated during the two clamping and positioning operations, resulting in a non-perfect match between the strengthened area and the processed area, affecting the consistency of the strengthening effect; 4. The overall process is complex and not conducive to automation integration. Therefore, there is an urgent need to develop a new technology and equipment that can integrate precision machining and surface strengthening functions to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, a composite processing method and system based on dual-mode coupling of water jet and laser is provided. This method combines the advantages of water-guided laser and laser shock peening technologies, using the same water jet to simultaneously achieve the dual functions of light guiding and constraint. Precision machining and surface strengthening of workpieces are completed synchronously on the same equipment and in the same process, thereby improving processing efficiency, accuracy consistency and process flexibility.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] On one hand, this invention provides a composite processing method based on dual-mode coupling of water jet and laser: utilizing the same high-pressure water jet, it synergistically achieves the dual functions of "light guiding medium" and "dynamic constraint layer" in both space and time. The high-pressure water jet is coaxial with the laser emitted by the pulsed laser generator. After optical path coupling, the high-pressure water jet produces total internal reflection of the laser beam, guiding the laser beam to the processing position. After reaching the processing position, the water jet forms a constraint layer for laser peening, completing dynamic constraint coupling with the laser beam, thereby achieving synchronous or temporal composite of water-guided laser precision machining and laser peening impact strengthening. The method specifically includes the following steps:

[0008] S1: Steady water jet generation

[0009] A stable, high-pressure micro-water jet is generated using a high-pressure water pump and a precision nozzle. To ensure efficient laser conduction and confinement, the water jet pressure is adjustable from 10 to 100 MPa, and the jet diameter ranges from 10 to 200 μm. Deionized water is used as the medium, with a conductivity of less than 5 μS / cm to minimize laser energy absorption.

[0010] S2: Laser-water jet coupling

[0011] A pulsed laser beam is coaxially injected into the incident end of a water jet via an optical coupling device. This device ensures that the laser beam enters the water jet at a specific incident angle and spot size to meet the critical angle condition for total internal reflection, thus completely confining the laser within the water jet and transmitting it to the workpiece surface with low loss in an "optical waveguide" mode.

[0012] S3: Composite Processing and Enhanced Execution

[0013] This is the core step of this method. By precisely controlling the parameters of the pulsed laser, two physical effects are synergistically or sequentially triggered on the workpiece surface:

[0014] 1. Precision machining effect: When the laser energy density exceeds the ablation threshold of the material, it can perform micron-scale cutting, drilling, or milling on the workpiece. In this process, the water jet plays a role in cooling and removing molten slag, achieving "cold machining".

[0015] 2. Impact Strengthening Effect: When the laser energy density is extremely high (but below the ablation threshold) or when the pulse width is adjusted so that the energy mainly acts on the generation of plasma, plasma will be instantaneously induced on the surface of the workpiece. At this time, the water jet surrounding it acts as an inertial confinement layer, strongly suppressing the expansion of the plasma, thereby efficiently converting the laser energy into mechanical energy, forming a high-intensity shock wave with a peak pressure of several GPa, causing plastic deformation of the material surface and introducing beneficial residual compressive stress.

[0016] The synergistic mode of the two physical effects described above can be a synchronous mode, where a single laser pulse simultaneously triggers ablation and shock waves, achieving instantaneous synchronization between processing and strengthening. Alternatively, it can be a sequential mode, where the system uses "low-energy, high-frequency" pulses alternately or in segments along the processing path for precision processing according to a preset program, and then uses "high-energy, low-frequency" pulses to perform shock strengthening on the processed area.

[0017] S4: Motion Trajectory and Process Planning

[0018] A multi-axis linkage motion platform is used to precisely control the relative motion between the workpiece and the water jet nozzle, and scan according to a preset three-dimensional trajectory to achieve selective composite processing of complex curved surfaces and structures.

[0019] On the other hand, this invention provides a composite processing system based on dual-mode coupling of water jet and laser. This system is a highly integrated mechatronics equipment, and its main components and innovations are as follows:

[0020] 1. Pulsed Laser Generator: Employing a solid-state laser or fiber laser with nanosecond-level pulse width, its core feature lies in its dual operating modes or wide-range energy modulation capability. It can output low-energy (0.1-100 mJ), high-repetition-rate (1-1000 Hz) pulses for processing, or high-energy (0.5-15 J), low-repetition-rate (1-100 Hz) pulses for enhancement, and can achieve rapid switching between the two modes.

[0021] 2. Water jet generation and supply module: This module includes a high-pressure water pump and nozzles. It is responsible for providing a stable water jet that meets the optical quality and pressure requirements.

[0022] 3. Optical path coupling module: including a beam expander, a focusing lens, and a coupling window. The focal length of the focusing lens is precisely calculated to ensure that its focal point is precisely coaxial with the center of the nozzle exit, ensuring that the laser beam is injected into the water jet with optimized parameters (such as beam waist diameter and divergence angle), maximizing total internal reflection efficiency, and ensuring that the laser energy is efficiently conducted;

[0023] 4. Multi-axis motion and control module: including high-precision CNC machine tools or industrial robots, used to execute complex motion trajectories.

[0024] Compared with existing technologies, this invention provides a composite processing method and system based on dual-mode coupling of water jet and laser, which has the following beneficial effects:

[0025] 1. Integration and high efficiency: It enables precision machining and surface strengthening to be completed simultaneously or sequentially in the same system and the same process, which greatly simplifies the process flow, reduces equipment investment and floor space, and improves production efficiency;

[0026] 2. High precision and consistency: The machining area and the strengthening area naturally overlap, completely eliminating secondary clamping and positioning errors, ensuring the accuracy and consistency of the strengthening effect, and is especially suitable for key load-bearing components with extremely high fatigue performance requirements;

[0027] 3. Performance improvement: Dynamic water jet confinement layers may generate higher shock wave pressures than traditional static water layers, potentially leading to better reinforcement effects;

[0028] 4. High process flexibility: By flexibly adjusting laser parameters (energy, frequency, pulse width), it is easy to switch between processing-oriented, strengthening-oriented, or synergistic modes to adapt to the processing needs of different materials and structures.

[0029] 5. Clean and environmentally friendly: Water jets can continuously remove slag and debris from the process and cool the processing area, making the entire process clean and pollution-free. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a composite processing method and system based on dual-mode coupling of water jet and laser according to the present invention;

[0031] Reference numerals: 10, Pulsed laser; 11, Pulsed laser beam; 20, Water jet generator; 21, High-pressure water jet; 22, High-pressure water pump; 23, Nozzle; 30, Optical path coupling device; 31, Beam expander; 32, Focusing lens; 33, Coupling window; 40, Workpiece; 50, Plasma; 51, Shock wave; 60, Motion control device. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0033] Example: Micro-pore Machining and Strengthening of Titanium Alloy Turbine Blades

[0034] 1. System Configuration

[0035] It employs an Nd:YAG pulsed laser (1064nm), a high-pressure water pump, and a five-axis linkage motion platform.

[0036] 2. Parameter Settings

[0037] Water jet: pressure 50MPa, diameter 100μm, deionized water.

[0038] Laser: Pulse width 15ns. Drilling stage: Single pulse energy 10mJ, frequency 100Hz. Strengthening stage: Single pulse energy 5J, frequency 10Hz.

[0039] 3. Technological Process

[0040] The system first uses a high repetition rate, low energy laser pulse mode for drilling. After drilling is complete, the laser switches to a low repetition rate, high energy mode, and the spray gun scans along the hole perimeter to perform impact strengthening on the hole edges.

[0041] 4. Result Verification

[0042] Simultaneously complete the machining of micro-holes with a diameter of 100μm (roundness error ≤1.5%), and achieve a residual compressive stress of -650 MPa around the hole (28% improvement compared to traditional processes).

Claims

1. A composite processing method based on dual-mode coupling of water jet and laser, characterized in that, Includes the following steps: S1: A stable high-pressure water jet (21) is generated by the water jet generating device (20) and guided to the surface of the workpiece (40); S2: The pulsed laser beam (11) generated by the pulsed laser (10) is coaxially injected into the incident end of the high-pressure water jet (21) by the optical path coupling device (30), so that the pulsed laser beam (11) is transmitted in the high-pressure water jet (21) by total internal reflection effect; S3: The output parameters of the pulsed laser (10) are controlled so that the laser energy reaching the surface of the workpiece (40) produces the following effects: removing the surface material of the workpiece (40) to achieve precision machining; inducing the generation of plasma (50), the high-pressure water jet (21) acts as a constraint layer to constrain the expansion of the plasma (50), forming a high-intensity shock wave (51) that acts on the surface of the workpiece (40) to achieve impact strengthening; S4: The relative movement of the workpiece (40) and the high-pressure water jet (21) is controlled by the motion control device (60) to perform composite processing according to a predetermined path.

2. The composite processing method based on dual-mode coupling of water jet and laser according to claim 1, characterized in that, In step S1, the pressure of the high-pressure water jet (21) is 10-100MPa and the jet diameter is 10-200μm; the high-pressure water jet (21) is deionized water with a conductivity of less than 5μS / cm.

3. The composite processing method based on dual-mode coupling of water jet and laser as described in claim 1, characterized in that, In step S2, the wavelength of the pulsed laser beam (11) is 1064nm, 532nm or 355nm, and the pulse width is 1-100ns.

4. The composite processing method based on dual-mode coupling of water jet and laser according to claim 1, characterized in that, In step S3, the output parameters of the pulsed laser (10) are controlled as follows: when precision machining is the main purpose, the single pulse energy is 0.1mJ-100mJ and the repetition frequency is 1-1000Hz; when shock strengthening is the main purpose, the single pulse energy is 0.5J-15J and the repetition frequency is 1-100Hz; the pulsed laser (10) can switch between the two output modes according to the processing requirements or the energy can be modulated by an external modulator.

5. The composite processing method based on dual-mode coupling of water jet and laser according to claim 1, characterized in that, In step S3, the precision machining and impact strengthening can be performed simultaneously or in stages according to a set time sequence.

6. A composite processing system based on dual-mode coupling of water jet and laser for implementing the method of any one of claims 1-5, characterized in that, include: A pulsed laser (10) is used to generate a high-energy pulsed laser beam (11); a water jet generating device (20) is used to generate a stable high-pressure water jet (21); and an optical path coupling device (30) is disposed between the pulsed laser (10) and the water jet generating device (20) for precisely coaxially coupling the pulsed laser beam (11) into the high-pressure water jet (21). A motion control device (60) is used to carry and control the workpiece (40) or the water jet generating device (20) to perform multi-axis motion.

7. A composite processing system based on dual-mode coupling of water jet and laser as described in claim 6, characterized in that, The water jet generating device (20) includes a high-pressure water pump (22) and a nozzle (23).

8. A composite processing system based on dual-mode coupling of water jet and laser as described in claim 6, characterized in that, The optical path coupling device (30) includes a beam expander (31), a focusing lens (32) and a coupling window (33) arranged in sequence. The focal point of the focusing lens (32) is coaxial with the outlet of the nozzle (23) of the water jet generating device.

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