Water guide laser energy gradual processing quality regulation method based on high overlap filling

Abstract

A water guide laser energy gradual processing quality control method based on high overlap filling, the nickel-based superalloy material sample is fixed on the precision motion platform of the water guide laser processing system, the relative position of the precision motion platform and the nickel-based superalloy material sample is adjusted, the vertical distance between the lower surface of the sample and the water guide laser processing head is within the effective processing length range of the water guide laser coupling energy beam, then the processing parameters of the water guide laser are set through the control system, finally the high overlap filling scanning processing strategy under high power is adopted, the high laser power is selected in the water guide laser filling scanning processing, the high overlap rate filling interval meeting the energy gradual processing effect is selected for parameter control, the optimal high overlap rate filling interval is selected, finally the obtained process parameter combination is transferred to the water guide laser annular filling scanning processing for processing, the processing efficiency of the water guide laser in processing superalloy is ensured, and the processing quality is improved.

Description

Technical Field

[0001] This invention relates to the field of water-guided laser processing technology, specifically to a method for controlling the processing quality of water-guided laser energy gradient based on high overlap filling. Background Technology

[0002] Nickel-based superalloys are widely used as the main materials for hot-end components of aero-engines due to their excellent strength, corrosion resistance, and creep fatigue resistance under high-temperature conditions. To further improve the service life and performance of these hot-end components, it is often necessary to machine small-diameter, high-precision film cooling holes to enhance their cooling efficiency. However, current film cooling hole machining methods, such as electrical discharge machining, electrohydraulic beam machining, and ultrafast laser machining, struggle to simultaneously meet the requirements for both machining efficiency and quality.

[0003] Among them, electrical discharge machining has a significant thermal effect, making it difficult to avoid the occurrence of recast layers and microcracks; electrohydraulic beam machining suffers from problems such as electrolyte corrosion damage to the hole edge material; ultrafast laser machining produces high-quality holes but has low hole-making efficiency.

[0004] Water-guided laser processing technology, as an advanced processing technology, works by coupling a high-energy laser beam into a micro water jet. The laser energy is then uniformly transmitted to the surface of the material being processed through total internal reflection in the water jet, thus forming a micron-sized processing "tool" with a long working distance. It features minimal surface damage, high precision, small recast layer, and processing distance not limited by the laser focal depth, making it well-suited for processing high-temperature alloy film cooling holes. In existing water-guided laser processing of high-temperature alloys, the non-filling scanning processing method ([1] Zhao Chuang, Zhao Yugang, Zhao Dandan, et al. Study on the groove structure of water jet Inconel 718 alloy[J]. Chinese Mechanical Engineering, 2023, 34(20): 2403-2410.) or the low overlap rate (overlap rate ≤50%) filled scanning processing method ([2] Wang Shunshan, Qiao Hongchao, Cao Zhihe, et al. Experimental study on micro-hole process of nickel-based single crystal high-temperature alloy prepared by water-guided laser[J]. Chinese Laser, 2024, 51(16): 285-294.) is usually used for processing. It is not possible to balance the requirements of processing quality and processing efficiency of high-temperature alloys. Therefore, it is necessary to develop a new water-guided laser processing method for high-temperature alloys to improve processing quality while ensuring processing efficiency. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for controlling the quality of water-guided laser energy gradient processing based on high overlap filling, so as to improve the processing quality while ensuring the processing efficiency of water-guided laser processing of high-temperature alloys.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for controlling the quality of water-conducting laser energy gradient processing based on high overlap filling includes the following steps: 1) Nickel-based high-temperature alloy materials are selected as the processing objects. The surface of the high-temperature alloy materials is flat and without obvious defects; 2) Fix the nickel-based superalloy material sample on the precision motion platform of the water-guided laser processing system, and adjust the relative position of the precision motion platform and the nickel-based superalloy material sample so that the vertical distance between the lower surface of the sample and the water-guided laser processing head is within the effective processing length of the water-guided laser coupling energy beam. 3) Set the processing parameters of the water-guided laser through the control system, including laser power, repetition frequency, scanning speed, water beam pressure, and number of scans; 4) High-overlapping filling scanning processing strategy under high power: In water-guided laser filling scanning processing, high laser power is selected to ensure the processing efficiency of water-guided laser processing of high-temperature alloys. The high overlap rate filling spacing that meets the energy gradient processing effect is selected for parameter adjustment. Then, the optimal high overlap rate filling spacing is selected to improve the processing quality of high-temperature alloys. Finally, the obtained process parameter combination is transferred to water-guided laser ring filling scanning processing for processing of high-temperature alloy gas film cooling holes.

[0007] The water-guided laser processing system uses a fiber laser with a wavelength of 532 nm and a pulse width of 190 ns to generate a pulsed laser source. The maximum average power is 150 W, the maximum single pulse energy is 20 mJ, and the repetition frequency is adjustable from 6 to 20 kHz.

[0008] The water source used in the processing is deionized ultrapure water with an adjustable water pressure range of 0-50 MPa.

[0009] Coaxial gas-assisted processing is used, with helium as the gas source and the gas pressure adjustable from 0 to 0.7 MPa.

[0010] The energy gradient processing effect refers to the process in water-guided laser filling scanning where, due to the absorption of laser energy by the water flow, by selecting an appropriate filling spacing, when the water-guided laser coupled energy beam scans the trajectory close to the wall, high laser power is applied to the wall to ensure processing efficiency; when the water-guided laser coupled energy beam scans the trajectory away from the wall, low laser power is applied to the wall. By adjusting the wall surface processed under high laser power, processing quality is ensured.

[0011] The high overlap rate fill spacing refers to a fill spacing that is less than half the diameter of the water jet, satisfying a scan path overlap rate greater than 50%.

[0012] The specific parameters for the high-overlapping filling scanning processing strategy under high power in step 4) are: laser power 40-50W, optimal filling spacing 10 μm, 3 filling passes, laser pulse width 200 ns, repetition frequency 8 kHz, water jet pressure 20 MPa, jet diameter 80 μm, and scanning speed 0.5-2.0 mm / s.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1) This invention uses water-guided laser processing technology, which can realize the processing of high-temperature alloy gas film cooling holes with small surface damage, high precision and small recast layer.

[0014] 2) By using a high-overlapping-fill scanning processing strategy under high power, high laser power is selected to ensure the processing efficiency of water-guided laser processing of high-temperature alloys. At the same time, the optimal high-overlapping-rate filling spacing is selected through parameter optimization to improve the processing quality of high-temperature alloys. Ultimately, the processing quality is improved while ensuring the processing efficiency of high-temperature alloys.

[0015] 3) The method of the present invention is applicable to the processing of air film cooling holes on the surface of high-temperature alloys and has wide applicability and practicality. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the scanning path for water-guided laser linear filling scan and ring filling scan in Embodiment 1 of the present invention.

[0017] Figure 2 This is a SEM image of the surface of the high-temperature alloy microgroove obtained during the process of adjusting the filling spacing in Embodiment 1 of the present invention.

[0018] Figure 3 The image shows the inlet and outlet of the high-temperature alloy straight hole and its cross-section processed under the optimal filling spacing at high laser power in Embodiment 1 of the present invention.

[0019] Figure 4 The image shows the inlet and outlet of the high-temperature alloy oblique hole and its cross-section processed under the optimal filling spacing at high laser power in Embodiment 1 of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0021] Example 1: A method for controlling the quality of water-conducting laser energy gradient processing based on high overlap filling, comprising the following steps: 1) Select a nickel-based high-temperature alloy material sample with a smooth surface, mechanically polish its surface to reduce the surface roughness to Ra 0.1, and then immerse the sample in anhydrous ethanol solution and use ultrasonic cleaning for 15 min to ensure its smoothness and cleanliness. 2) Fix the sample on the precision motion platform of the water-guided laser processing system, adjust the relative position of the precision motion platform and the nickel-based high-temperature alloy material sample, and simultaneously adjust the pressure of the auxiliary gas so that the vertical distance between the lower surface of the sample and the water-guided laser processing head is within the effective processing length range of the water-guided laser coupling energy beam, so as to ensure that the water-guided laser coupling energy beam has the ability to process the high-temperature alloy material sample. The water-guided laser processing system uses a fiber laser with a wavelength of 532 nm and a pulse width of 190 ns to generate a pulsed laser source. The maximum average power is 150 W, the maximum single pulse energy is 20 mJ, and the repetition frequency is adjustable from 6 to 20 kHz.

[0022] 3) Use software to set processing parameters such as laser power, repetition frequency, scanning speed, water jet pressure, and number of scans. The laser power is selected as 50 W to ensure the processing efficiency of high-temperature alloy materials. The other process parameters are as follows: laser pulse width 200 ns, repetition frequency 8kHz, water jet pressure 20 MPa, jet diameter 80 μm, scanning speed 1.0 mm / s, and number of scans 1.

[0023] 4) Draw a straight line fill scan path as follows: Figure 1 As shown, there are 3 fill passes, and the fill spacing is selected with a high overlap rate, which are 5μm, 10μm, 15μm and 20μm respectively. Then the processing program is started. 5) After processing, microgrooves with different filling gaps were obtained. The surface morphology of the microgrooves was observed using a tungsten filament scanning electron microscope. The obtained SEM images are shown below. Figure 2 As shown, the optimal fill spacing was selected as 10μm; The water source used in the processing is deionized ultrapure water with an adjustable water pressure range of 0-50 MPa.

[0024] Coaxial gas-assisted processing is used, with helium as the gas source and the gas pressure adjustable from 0 to 0.7 MPa.

[0025] The high overlap rate fill spacing refers to a fill spacing that is less than half the diameter of the water jet, satisfying a scan path overlap rate greater than 50%.

[0026] 6) Modify the scan path to perform ring-shaped filling scan processing, such as... Figure 1 As shown, with a fill spacing of 10 μm and 100 scans, and other process parameters remaining unchanged, the obtained SEM morphology of the inlet and outlet of the air film cooling hole and its cross-section is as follows. Figure 3 and Figure 4As shown. The final straight / inclined hole inlet and outlet and cross-sectional sidewall quality are high, with almost no chipping or breakage. The straight hole inlet diameter is 643.41 μm, the outlet diameter is 585.54 μm, and the taper is only 0.55°; the inclined hole inlet diameter is 664.03 μm, the outlet diameter is 616.72 μm, and the taper is only 0.33°.

[0027] In Example 2, the scanning speed in step 3) of Example 1 was adjusted to 0.5 mm / s, while other parameters remained unchanged. The resulting straight / oblique hole inlet and outlet and the quality of the cross-sectional sidewalls were similar to those in Example 1.

[0028] In Example 3, the scanning speed in step 3) of Example 1 was adjusted to 2.0 mm / s, while other parameters remained unchanged. The resulting straight / oblique hole inlet and outlet and the quality of the cross-sectional sidewalls were similar to those in Example 1.

[0029] Example 4: The laser power in step 3) of Example 1 was adjusted to 40 W, while other parameters remained unchanged. The resulting straight / oblique hole inlet and outlet and the quality of the cross-sectional sidewalls were similar to those in Example 1.

Claims

1. A method for controlling the quality of water-conducting laser energy gradient processing based on high overlap filling, comprising the following steps: 1) Nickel-based high-temperature alloy materials are selected as the processing objects, and the surface of the high-temperature alloy materials is flat; 2) Fix the nickel-based superalloy material sample on the precision motion platform of the water-guided laser processing system, and adjust the relative position of the precision motion platform and the nickel-based superalloy material sample so that the vertical distance between the lower surface of the sample and the water-guided laser processing head is within the effective processing length of the water-guided laser coupling energy beam. 3) Set the processing parameters of the water-guided laser through the control system, including laser power, repetition frequency, scanning speed, water beam pressure, and number of scans; 4) High-overlapping filling scanning processing strategy under high power: In water-guided laser filling scanning processing, high laser power is selected to ensure the processing efficiency of water-guided laser processing of high-temperature alloys. The high overlap rate filling spacing that meets the energy gradient processing effect is selected for parameter adjustment. Then, the optimal high overlap rate filling spacing is selected to improve the processing quality of high-temperature alloys. Finally, the obtained process parameter combination is transferred to water-guided laser ring filling scanning processing for processing of high-temperature alloy gas film cooling holes.

2. The method according to claim 1, characterized in that: The water-guided laser processing system uses a fiber laser with a wavelength of 532nm and a pulse width of 190ns to generate a pulsed laser source. The maximum average power is 150W, the maximum single pulse energy is 20mJ, and the repetition frequency is adjustable from 6 to 20KHz.

3. The method according to claim 1, characterized in that: The water source used in the processing is deionized ultrapure water with an adjustable water pressure range of 0-50 MPa.

4. The method according to claim 1, characterized in that: Coaxial gas-assisted processing is used, with helium as the gas source and the gas pressure adjustable from 0 to 0.7 MPa.

5. The method according to claim 1, characterized in that: The energy gradient processing effect refers to the process in water-guided laser filling scanning where, due to the absorption of laser energy by the water flow, the filling spacing is selected to achieve high laser power processing on the wall surface when the water-guided laser coupled energy beam scans the trajectory close to the wall surface, ensuring processing efficiency; and low laser power processing on the wall surface when the water-guided laser coupled energy beam scans the trajectory far from the wall surface. By adjusting the wall surface processed under high laser power, the processing quality is ensured.

6. The method according to claim 1, characterized in that: The high overlap rate fill spacing refers to a fill spacing that is less than half the diameter of the water jet, satisfying a scan path overlap rate greater than 50%.

7. The method according to claim 1, characterized in that: The specific parameters for the high-overlapping filling scanning processing strategy under high power in step 4) are: laser power 40-50 W, optimal filling spacing 10 μm, 3 filling passes, laser pulse width 200 ns, repetition frequency 8 kHz, water jet pressure 20 MPa, jet diameter 80 μm, and scanning speed 0.5-2.0 mm / s.

Images