Double-path auxiliary blowing optimization simulation and experiment method based on ultrafast laser

Abstract

The invention relates to the technical field of ultrafast laser processing, in particular to a double-path auxiliary blowing optimization simulation and experiment method based on ultrafast laser, which comprises the following steps: providing a coaxial blowing device and a paraxial supersonic blowing device; a laser deep hole machining program is divided into three stages: stage 1, machining a platform vertical to a hole axis, and only starting coaxial blowing; stage 2, removing the main body material to form a conical through hole, and cooperatively using coaxial continuous blowing and paraxial intermittent blowing; stage 3, hole outlet shaping is carried out; paraxial air tap parameters are optimized through finite element simulation, and two paths of airflow parameters are controlled in real time; the deep hole machining speed and quality can be remarkably improved, material loss in the machining process is reduced, stable airflow is provided within the diameter range of laser beams, a light path is kept clear, and laser energy is prevented from being shielded; paraxial blowing provides high-speed airflow through a supersonic nozzle, and dust and waste materials on the hole wall and the hole bottom are accurately removed.

Description

Technical Field

[0001] The invention relates to an ultrafast laser processing technology, in particular to a dual-path auxiliary air blowing technology used to improve the efficiency of femtosecond laser deep hole processing and reduce processing defects. Background Art

[0002] Femtosecond laser technology is widely used in precision material processing, such as microelectronic device manufacturing, precision mechanical parts processing, and medical device production, due to its extremely short pulse width and extremely high peak power. The main advantage of this technology is that it can greatly reduce the heat-affected zone and avoid thermal damage to the material, thereby achieving high-precision processing. However, when performing deep hole processing tasks, the main problem faced by the femtosecond laser processing process is how to solve the low processing efficiency. Because during the deep hole processing process, the plasma generated by the laser and the dust of the unevaporated material will hinder the laser beam and reduce its efficiency on the material.

[0003] In the prior art, although air blowing technology is used to remove dust and gas from the hole, the conventional single-channel air blowing system often cannot completely remove the residues at the bottom and wall of the hole, especially when processing deep holes or using high-power lasers. In addition, the existing air blowing system often cannot effectively perform cleaning operations without interfering with the laser path, which limits its application in complex and precision processing. To this end, we propose a dual-channel auxiliary air blowing optimization simulation and experimental method based on ultrafast laser. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an improved dual-path auxiliary air blowing system, aiming to optimize the efficiency and quality of femtosecond laser deep hole processing.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solution: a dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser, comprising the following steps:

[0006] Provide coaxial blowing device and side-axis supersonic blowing device;

[0007] The laser deep hole processing procedure is divided into three stages:

[0008] Stage 1: Machining the platform perpendicular to the hole axis, only coaxial blowing is enabled;

[0009] Stage 2: Remove the main material to form a tapered through hole, using coaxial continuous blowing and side-axis intermittent blowing in coordination;

[0010] Stage 3: Perform hole outlet modification while maintaining dual-channel blowing coordination;

[0011] Finite element simulation is used to optimize the parameters of the side-axle air nozzle, including:

[0012] a) Establishing a three-dimensional blade model including geometric features of air film holes;

[0013] b) Set the Mach number and pressure boundary conditions of supersonic airflow;

[0014] c) Simulate the flow field distribution under different nozzle distances (0.5-3mm) and angles (60-90°);

[0015] d) Selecting a parameter combination that produces a maximum negative pressure area;

[0016] Real-time control of two air flow parameters:

[0017] The coaxial blowing pressure is 0.1-0.5MPa;

[0018] The side-axis blowing air pressure is 0.4-0.6 MPa, and the outlet flow rate is 304-405 m / s.

[0019] In stage 2 and stage 3, the side-axis air blowing maintains an angle of 80-90° with the workpiece surface.

[0020] As a further technical solution of the present invention, the stage 1 specifically includes:

[0021] The initial platform layer is processed by a spiral scanning path, and the coaxial blowing flow rate is maintained at 0.8-1.2 L / min;

[0022] Control the laser focus to fluctuate within ±50μm on the material surface;

[0023] A nitrogen protective atmosphere was established with an oxygen content of <500ppm.

[0024] As a further technical solution of the present invention, in the stage 2:

[0025] The side-axis air blowing adopts a pulse working mode, and the blowing cycle is 1 / 3-1 / 2 of the laser scanning cycle. It is set to execute a side-axis air blowing pulse after every 3-5 layers of material removal. The blowing pulse duration is 50-200ms, and the interval time is 300-500ms.

[0026] As a further technical solution of the present invention, the finite element simulation step further includes:

[0027] The k-ε turbulence model is used to calculate the high-speed airflow field;

[0028] The particle tracking module is used to simulate the movement trajectory of dust;

[0029] Quantitative indicators for evaluating the debris removal efficiency under different parameter combinations:

[0030] Emission efficiency η = (V_ejected / V_total) × 100%, where V_ejected is the volume of discharged dust and V_total is the total volume of generated dust.

[0031] As a further technical solution of the present invention, parameters are set for different materials:

[0032] Stainless steel material: coaxial air pressure 0.3-0.4MPa, side-axis flow rate 380±20m / s;

[0033] Aluminum alloy material: coaxial air pressure 0.2-0.3MPa, side-axis flow velocity 340±20m / s;

[0034] Titanium alloy material: coaxial air pressure 0.4-0.5MPa, paraxial flow velocity 400±20m / s.

[0035] As a further technical solution of the present invention, the processing quality monitoring step is also included:

[0036] The debris accumulation in the hole is monitored in real time by coaxial CCD, and the paraxial air blowing enhancement mode is triggered when the gray value change rate ΔG / Δt>5% / s;

[0037] The strengthening mode includes:

[0038] Increase the side-axle air pressure to 0.7-0.8MPa;

[0039] Shorten the blowing interval to 100-200ms;

[0040] Increase the nozzle swing range by ±5°.

[0041] As a further technical solution of the present invention, the generation of the supersonic airflow negative pressure zone includes:

[0042] A supersonic flow with a Mach number of 1.2-1.8 is formed in the extended section of the Lafayette nozzle;

[0043] Through the Bernoulli effect, a negative pressure zone of -10kPa to -30kPa is formed 2-5mm away from the outlet;

[0044] The suction effect generated by the pressure gradient is used to remove the residue at the bottom of the hole.

[0045] As a further technical solution of the present invention, a post-processing step is also included:

[0046] After completing the stage 3 process, perform a two-way combined purge:

[0047] Among them, the coaxial blowing is maintained at 0.2MPa, and the side-axis blowing operates at a frequency pulse of 0.5Hz, which lasts for 30-60 seconds until the temperature detected by the infrared sensor drops below 50℃.

[0048] The invention proposes a dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser, which has the following beneficial effects:

[0049] The present invention can significantly improve the speed and quality of deep hole processing, reduce material loss during processing, and improve the surface finish of the final product by adopting a dual-path structure of coaxial blowing and side-axis blowing. Coaxial blowing is mainly responsible for providing a stable airflow within the diameter range of the laser beam, keeping the optical path clear and avoiding shielding of the laser energy; side-axis blowing provides a high-speed airflow through a supersonic nozzle to accurately remove dust and waste from the hole wall and bottom. The dual-path blowing system achieves efficient cleaning of the processing area by precisely controlling the pressure and direction of the two-path airflow, while reducing interference with the laser path.

[0050] The coaxial air blowing of the present invention ensures that the airflow provides a stable cleaning effect near the laser action point by optimizing the nozzle design, thereby avoiding the shielding of the laser energy; the side-axis air blowing utilizes a supersonic nozzle to generate a high-speed airflow through the Rafale cavity structure, forming a negative pressure zone, which can effectively suck out the dust and residue at the bottom of the hole. The dual-channel air blowing system significantly improves the cleaning effect and processing efficiency of deep hole processing by working in coordination. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is the design principle diagram of the dual-channel auxiliary blowing structure.

[0052] Figure 2 This is a comparative schematic diagram for verifying the effect of the dual-channel auxiliary blowing system.

[0053] Figure 3 Schematic diagram of the laser spiral hole making process.

[0054] Figure 4 This is the design diagram of the coaxial blowing system.

[0055] Figure 5 It is a comparison table of technical effects and implementation principles. DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0057] Embodiment 1

[0058] Reference Figure 1-5 As shown, a dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser includes the following steps:

[0059] Provide coaxial blowing device and side-axis supersonic blowing device;

[0060] The laser deep hole processing procedure is divided into three stages:

[0061] Stage 1: Machining the platform perpendicular to the hole axis, only coaxial blowing is enabled;

[0062] Stage 2: Remove the main material to form a tapered through hole, using coaxial continuous blowing and side-axis intermittent blowing in coordination;

[0063] Stage 3: Perform hole outlet modification while maintaining dual-channel blowing coordination;

[0064] Finite element simulation is used to optimize the parameters of the side-axle air nozzle, including:

[0065] a) Establishing a three-dimensional blade model including geometric features of air film holes;

[0066] b) Set the Mach number and pressure boundary conditions of supersonic airflow;

[0067] c) Simulate the flow field distribution under different nozzle distances (0.5-3mm) and angles (60-90°);

[0068] d) Selecting a parameter combination that produces a maximum negative pressure area;

[0069] Real-time control of two air flow parameters:

[0070] Coaxial blowing pressure 0.1-0.5MPa;

[0071] The side-axis blowing pressure is 0.4-0.6MPa, and the outlet flow rate is 304-405m / s.

[0072] In stage 2 and stage 3, the side-axis air blowing maintains an angle of 80-90° with the workpiece surface.

[0073] Phase 1 specifically includes:

[0074] The initial platform layer was processed using a spiral scanning path, and the coaxial air flow rate was maintained at 0.8-1.2L / min;

[0075] Control the laser focus to fluctuate within ±50μm on the material surface;

[0076] A nitrogen protective atmosphere was established with an oxygen content of <500ppm.

[0077] In Phase 2:

[0078] The side-axis air blowing adopts a pulse working mode, and the blowing cycle is 1 / 3-1 / 2 of the laser scanning cycle. It is set to execute a side-axis air blowing pulse after every 3-5 layers of material removal. The blowing pulse duration is 50-200ms, and the interval time is 300-500ms.

[0079] The finite element simulation steps further include:

[0080] The k-ε turbulence model is used to calculate the high-speed airflow field;

[0081] The particle tracking module is used to simulate the movement trajectory of dust;

[0082] Quantitative indicators for evaluating the debris removal efficiency under different parameter combinations:

[0083] Emission efficiency η = (V_ejected / V_total) × 100%, where V_ejected is the volume of discharged dust and V_total is the total volume of generated dust.

[0084] Set parameters for different materials:

[0085] Stainless steel material: coaxial air pressure 0.3-0.4MPa, side-axis flow rate 380±20m / s;

[0086] Aluminum alloy material: coaxial air pressure 0.2-0.3MPa, side-axis flow velocity 340±20m / s;

[0087] Titanium alloy material: coaxial air pressure 0.4-0.5MPa, paraxial flow velocity 400±20m / s.

[0088] Also includes processing quality monitoring steps:

[0089] The debris accumulation in the hole is monitored in real time by coaxial CCD, and the paraxial air blowing enhancement mode is triggered when the gray value change rate ΔG / Δt>5% / s;

[0090] Among them, the enhanced mode includes:

[0091] Increase the side-axle air pressure to 0.7-0.8MPa;

[0092] Shorten the blowing interval to 100-200ms;

[0093] Increase the nozzle swing range by ±5°.

[0094] The generation of supersonic airflow negative pressure zone includes:

[0095] A supersonic flow with a Mach number of 1.2-1.8 is formed in the extended section of the Lafayette nozzle;

[0096] Through the Bernoulli effect, a negative pressure zone of -10kPa to -30kPa is formed 2-5mm away from the outlet;

[0097] The suction effect generated by the pressure gradient is used to remove the residue at the bottom of the hole.

[0098] Post-processing steps are also included:

[0099] After completing stage 3 processing, perform a two-way combined purge:

[0100] Among them, the coaxial blowing is maintained at 0.2MPa, and the side-axis blowing operates at a frequency pulse of 0.5Hz, which lasts for 30-60 seconds until the temperature detected by the infrared sensor drops below 50℃.

[0101] This system adopts a unique coaxial and paraxial blowing structure, which can achieve efficient cleaning of the processing area by precisely controlling the pressure and direction of the two airflows, while minimizing interference with the laser path. The coaxial blowing structure optimizes the distance between the nozzle outlet and the blade surface by designing the focal length of the field lens and the taper of the nozzle, ensuring an effective blowing effect while avoiding interference with the workpiece; the paraxial blowing uses a supersonic nozzle, which consists of a contraction section and an expansion section. In the contraction section of the nozzle, the airflow is compressed, causing the airflow speed to gradually increase. When the airflow passes through the narrowest part of the nozzle (called the throat), the airflow speed reaches the speed of sound. In the expansion section of the nozzle, as the width of the nozzle gradually increases, the airflow speed is further increased and exceeds the speed of sound. At this time, the airflow speed is large, which can effectively blow away the splashes, and the disturbance to the surrounding gas can also be greatly reduced.

[0102] Coaxial air blowing is mainly responsible for providing a stable airflow within the diameter of the laser beam, helping to remove the smoke and gas generated directly at the laser action point, keeping the optical path clear, and preventing the laser energy from being shielded before reaching the workpiece surface.

[0103] The side-axis blowing is designed to provide auxiliary cleaning around the laser and deep in the hole. Using a supersonic nozzle based on the Rafael cavity structure, by setting a smaller nozzle diameter and higher air pressure, the side-axis blowing can more accurately remove dust and waste from the hole wall, especially at the bottom of the deep hole and the hard-to-reach area, and the air flow velocity is large at this time, which greatly reduces the disturbance of the surrounding gas. Due to the special structure of the supersonic nozzle, the air flow velocity at the outlet is very fast, which causes the air pressure in the area around the air flow to drop rapidly, forming a negative pressure zone. The formation of this negative pressure zone is related to the Bernoulli principle and the "inverse relationship between flow velocity and pressure" in fluid dynamics. According to the Bernoulli equation, when the flow velocity increases, the pressure decreases. Therefore, in the extended section of the supersonic nozzle, due to the sharp increase in air flow velocity, the static pressure around the nozzle outlet will drop significantly, forming a negative pressure zone. The negative pressure zone can suck out the dust and waste at the bottom and discharge them through the air flow.

[0104] In the laser spiral hole making process, the beam moves in the horizontal direction according to a specific scanning path, and the focal position moves from top to bottom along the hole axis. In order to ensure good forming under large incident angle conditions, the hole making process is divided into three stages: Stage 1 processes the platform perpendicular to the hole axis to suppress the influence of the incident angle; Stage 2 removes most of the material to form a through hole with a certain taper; Stage 3 realizes the modification of the air film hole outlet to reduce the hole taper.

[0105] In stage 1, since the hole is not too deep, the coaxial air blowing should play a role, providing the establishment of a protective atmosphere in the hole-making area, excellent cooling effect and a good slag removal environment; in stage 2 and stage 3, most of the material is removed, and a large amount of dust and waste are attached to the hole wall. At this time, the coordination of coaxial and side-axis air blowing should be strengthened. The coaxial air blowing is carried out when the laser is acting, and the side-axis air blowing negative pressure is set intermittently in the middle to suck out and blow away the dust and waste that is difficult to remove from the coaxial. During the process, the side-axis air nozzle should be as perpendicular to the surface of the processing object as possible. The specific air pressure and flow rate settings of the coaxial and side-axis are shown in the above content.

[0106] As for the specific side-axis placement angle and distance, since the blade surface has an arc, it can be explored through finite element simulation. To maximize the negative pressure, it can be seen from the Bernoulli equation that an increase in flow rate will lead to a decrease in static pressure, that is, negative pressure is generated, and the flow rate increases, and the negative pressure increases. The goal is to maximize the airflow velocity on the blade surface and generate the maximum negative pressure to suck out the dust and debris in the air film hole; the boundary conditions include the supersonic airflow characteristics of the air nozzle (such as Mach number, pressure, temperature), the geometric shape and surface characteristics of the blade, the position, size and shape of the air film hole, and environmental conditions (such as atmospheric pressure and temperature). By establishing a geometric model, meshing, setting a physical model and boundary conditions, simulating different angles and distances, running the simulation and analyzing the results, obtaining data such as airflow velocity and pressure distribution, and determining the air nozzle distance and angle that maximizes the airflow velocity and has the strongest negative pressure.

[0107] Through the above technology, the present invention can significantly improve the speed and quality of deep hole processing, reduce material loss during processing, and improve the surface finish of the final product. Compared with the use of a single airflow path, the airflow is blown in separately from the coaxial direction or the paraxial direction of the laser head. The airflow path is single and it is impossible to take into account the cleaning of the laser path and the removal of dust in the hole at the same time. The single-path blowing system often cannot effectively remove dust and residues at the bottom of the deep hole. Especially in high-power laser processing, dust and plasma will seriously hinder the penetration effect of the laser. The present invention adopts a dual-path structure of coaxial blowing and paraxial blowing. Coaxial blowing is mainly responsible for providing a stable airflow within the diameter range of the laser beam, keeping the optical path clear and avoiding the shielding of the laser energy; the paraxial blowing provides a high-speed airflow through a supersonic nozzle to accurately remove dust and waste from the hole wall and the bottom of the hole. The dual-path blowing system achieves efficient cleaning of the processing area by precisely controlling the pressure and direction of the two-path airflow, while reducing interference with the laser path. In terms of working principle, a single-channel air blowing system can usually only provide airflow in a single direction, and the airflow speed and pressure are limited, and it is unable to effectively remove dust and residues in deep holes. Especially in deep hole processing, a single-channel air blowing system is often unable to completely discharge dust and residues, resulting in low processing efficiency and poor hole wall quality. The coaxial air blowing of the present invention optimizes the nozzle design to ensure that the airflow provides a stable cleaning effect near the laser action point to avoid the shielding of the laser energy; the side-axis air blowing utilizes a supersonic nozzle to generate a high-speed airflow through the Rafale cavity structure to form a negative pressure zone, which can effectively suck out dust and residues at the bottom of the hole. The dual-channel air blowing system significantly improves the cleaning effect and processing efficiency of deep hole processing by working in coordination. These improvements make the present invention have broad application prospects in high-precision processing fields (such as aerospace, precision machinery and microelectronics manufacturing).

[0108] Embodiment 2

[0109] In a laser processing system containing a femtosecond laser (pulse width 290fs, repetition rate 100kHz, power adjustable to 20W), a coaxial air nozzle and a supersonic side-axis air nozzle are set. The coaxial air nozzle is mainly responsible for providing sufficient airflow to keep the laser path clear, while the side-axis air nozzle is responsible for accurately removing dust and residues in the hole. The air pressure of the coaxial and side-axis air blowing and their relative positions are adjusted to optimize the airflow effect during the processing. The coaxial air blowing pressure is set to 0.1-0.5MPa; the side-axis air blowing pressure is set to 0.4-0.6MPa, and the average velocity of the outlet air flow is 304-405m / s. By conducting processing experiments on different materials (such as stainless steel, aluminum and titanium alloy), the effect of dual-path air blowing on improving processing speed and quality is evaluated. For stainless steel, the processing speed of the single-channel air blowing system is 0.8mm / min, and the dual-channel auxiliary air blowing system is increased to 1.5mm / min, an increase of 87.5%; the surface roughness processed by the single-channel air blowing system is 1.2μm, and the surface roughness processed by the dual-channel auxiliary air blowing system is reduced to 0.5μm, a reduction of 58.3%; the incidence of processing defects (such as hole wall cracks, residue residue, etc.) of the single-channel air blowing system is 15%, and the incidence of processing defects of the dual-channel auxiliary air blowing system is reduced to 5%, a reduction ratio of 66.7%. For aluminum, the processing speed of the single-channel air blowing system is 1.2mm / min, and the dual-channel auxiliary air blowing system is increased to 2.3mm / min, an increase of 91.7%; the surface roughness processed by the single-channel air blowing system is 0.9μm, and the surface roughness processed by the dual-channel auxiliary air blowing system is reduced to 0.4μm, a reduction of 55.6%; the incidence of processing defects (such as hole wall cracks, residue residue, etc.) of the single-channel air blowing system is 12%, and the incidence of processing defects of the dual-channel auxiliary air blowing system is reduced to 4%, a reduction ratio of 66.7%. For titanium alloy, the processing speed of the single-channel air blowing system is 0.6mm / min, and the dual-channel auxiliary air blowing system is increased to 1.1mm / min, an increase of 83.3%; the surface roughness processed by the single-channel air blowing system is 1.5μm, and the surface roughness processed by the dual-channel auxiliary air blowing system is reduced to 0.7μm, a reduction of 53.3%; the incidence rate of processing defects (such as hole wall cracks, residue residue, etc.) of the single-channel air blowing system is 18%, and the incidence rate of processing defects of the dual-channel auxiliary air blowing system is reduced to 6%, a reduction ratio of 66.7%.

[0110] Embodiment 3

[0111] Reference Figure 5 As shown, as another preferred embodiment of the present invention, the difference from embodiment 1 is that:

[0112] Select the fractal scanning strategy based on the material type:

[0113] Among them, stainless steel adopts a hexagonal honeycomb path with a single layer repeated 2-3 times;

[0114] Titanium alloy uses a spiral involute path with an interlayer rotation angle of 15°-30°;

[0115] And the molten pool area change rate ΔS / Δt is calculated in real time. When ΔS / Δt>0.5mm 2 / s automatically switches to the ring compensation path;

[0116] Among them, the path compensation algorithm: P_corr = k1·(T_m-T_0)+k2·(V_e-V_0);

[0117] Where:

[0118] T_m is the real-time molten pool temperature, T_0 is the reference temperature, Ve is the actual blowing speed, V_0 is the set blowing speed, k1 = 0.05-0.1 mm / °C, k2 = 0.2-0.3 mm / (m / s).

[0119] Also includes IR feedback regulation:

[0120] The temperature distribution at the bottom of the hole is monitored in real time through the coaxial optical fiber integrated infrared temperature measurement module, and the temperature gradient model is established at the same time:

[0121] The ratio of the center temperature T_c to the edge temperature T_e is R = T_c / T_e;

[0122] When R>1.5, nozzle swing compensation is triggered:

[0123] Among them, the swing frequency is 1-3Hz, and the swing amplitude is ±3° to ±8°;

[0124] Then dynamically adjust the Lafarge nozzle contraction ratio according to temperature feedback:

[0125] When the contraction ratio β=0.6-0.8, the corresponding negative pressure range is -15kPa to -25kPa, and the adjustment rate does not exceed 0.1β / s.

[0126] Through fractal scanning path design, just like bees use hexagonal honeycomb structures to build nests to efficiently utilize space, fractal scanning paths (honeycomb or spiral involute) disperse laser heat through specific geometric shapes. For example:

[0127] Stainless steel processing uses a hexagonal path (similar to a honeycomb) to scan layer by layer, and each layer is repeated 2-3 times. The heat is evenly dispersed to avoid local overheating and material deformation.

[0128] Titanium alloy processing uses a spiral involute path, rotating 15°-30° during each layer scan, just like using a spiral line to "bypass" the internal stress of the material and reduce the roughness of the hole wall.

[0129] In conjunction with the dynamic compensation mechanism for the molten pool, the size change of the molten pool (the liquid area after the metal is melted by the laser) is monitored in real time through a high-speed camera: if the molten pool suddenly becomes larger (for example, impurities in the material cause uneven heat absorption), the system will switch to a circular path within 0.2 seconds to automatically compensate for the error. The parameters in the compensation formula (such as temperature difference and blowing speed difference) are like "correction coefficients", telling the machine how many millimeters of the path radius need to be adjusted to offset the error. At the same time, in conjunction with temperature gradient monitoring and feedback, during laser processing, an infrared thermometer (similar to a thermal imager) is used to monitor the temperature distribution at the bottom of the hole in real time. When the center temperature is 1.5 times higher than the edge temperature (for example, 1800℃ in the center vs. 1200℃ at the edge), the system determines that the temperature is uneven and may cause cracks, and automatically triggers the nozzle to swing. The nozzle swings left and right at ±3°-8° at a frequency of 1-3Hz, allowing the airflow to cover a wider area and balance the temperature difference.

[0130] The contraction ratio of the Rafale nozzle is then dynamically adjusted according to temperature feedback, and the airflow speed is changed by adjusting the "throat thickness" of the nozzle (contraction ratio 0.6-0.8). For example, when the contraction ratio is increased, the airflow speed increases and the negative pressure increases (from -15kPa to -25kPa), which sucks away debris more efficiently like a vacuum cleaner. The adjustment rate is limited to 0.1β / second (the contraction ratio can be adjusted by up to 10% per second) to avoid debris residue caused by sudden changes in airflow. Through fractal scanning path design and airflow control technology, laser processing can both "draw accurately" and "suck cleanly", ultimately achieving high-precision, damage-free deep hole processing.

[0131] By designing hexagonal honeycomb paths and spiral involute paths for stainless steel and titanium alloys respectively, the laser heat input can be effectively dispersed. For example, the use of a hexagonal path for stainless steel can reduce the heat affected zone by 18%-25%, and the spiral involute design of titanium alloy can reduce material splashing by more than 35%, which is particularly suitable for the processing of precision parts such as aircraft engine blades. The dual mechanism of molten pool area change rate monitoring + algorithm compensation can dynamically correct the processing error. When the abnormal expansion of the molten pool area is detected (ΔS / Δt>0.5mm² / s), the system can switch to the annular compensation path within 0.2 seconds to control the aperture error within ±5μm, which is 40% higher than the traditional fixed path processing accuracy. The temperature coefficient (k1) and airflow coefficient (k2) in the P_corr compensation formula realize the closed-loop control of the temperature field and airflow. After testing, the algorithm can reduce the taper deviation of deep holes to within 0.8°, which is particularly suitable for the processing of heat-sensitive materials such as high-temperature alloys.

[0132] Through the 3-5μm wavelength infrared temperature measurement module, the temperature distribution at the bottom of the hole can be accurately obtained through the processing smoke. When the temperature difference ratio R between the center and the edge is detected to be greater than 1.5 (typical value occurs in nickel-based alloy processing), the system automatically triggers the nozzle to swing, which improves the temperature uniformity by 60% and avoids the formation of microcracks in the hole wall. The combined control of nozzle swing and contraction ratio adjustment can maintain a stable negative pressure zone. Experimental data show that when the nozzle swings at 1-3Hz, the negative pressure fluctuation range drops from ±8kPa to ±2kPa. Combined with the adjustment rate of the contraction ratio of 0.1β / s, it can ensure that the chip discharge efficiency continues to be greater than 92%. The mapping relationship between the negative pressure range and the contraction ratio (β=0.6-0.8 corresponds to -15 to -25kPa) enables the system to automatically match the optimal parameters according to the material properties. For example, when processing titanium alloys, the contraction ratio is automatically adjusted to 0.75, which increases the processing efficiency by 30% compared to the fixed parameter solution.

[0133] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser, characterized in that: The following steps are involved: Provide coaxial blowing device and side-axis supersonic blowing device; The laser deep hole processing procedure is divided into three stages: Stage 1: Machining the platform perpendicular to the hole axis, only coaxial blowing is enabled; Stage 2: Remove the main material to form a tapered through hole, using coaxial continuous blowing and side-axis intermittent blowing in coordination; Stage 3: Perform hole outlet modification while maintaining dual-channel blowing coordination; Finite element simulation is used to optimize the parameters of the side-axle air nozzle, including: a) Establishing a three-dimensional blade model including geometric features of air film holes; b) Set the Mach number and pressure boundary conditions of supersonic airflow; c) Simulate the flow field distribution under different nozzle distances (0.5-3mm) and angles (60-90°); d) selecting a parameter combination that produces a maximum negative pressure area; Real-time control of two air flow parameters: The coaxial blowing pressure is 0.1-0.5MPa; The side-axis blowing air pressure is 0.4-0.6 MPa, and the outlet flow rate is 304-405 m / s. In stage 2 and stage 3, the side-axis air blowing maintains an angle of 80-90° with the workpiece surface.

2. The dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser according to claim 1 is characterized in that: The stage 1 specifically includes: The initial platform layer is processed by a spiral scanning path, and the coaxial blowing flow rate is maintained at 0.8-1.2 L / min; Control the laser focus to fluctuate within ±50μm on the material surface; A nitrogen protective atmosphere was established with an oxygen content of <500ppm.

3. The dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser according to claim 2 is characterized in that: In the Phase 2: The side-axis air blowing adopts a pulse working mode, and the blowing cycle is 1 / 3-1 / 2 of the laser scanning cycle. It is set to execute a side-axis air blowing pulse after every 3-5 layers of material removal. The blowing pulse duration is 50-200ms, and the interval time is 300-500ms.

4. The dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser according to claim 3 is characterized in that: The finite element simulation step further comprises: The k-ε turbulence model is used to calculate the high-speed airflow field; The particle tracking module is used to simulate the movement trajectory of dust; Quantitative indicators for evaluating the debris removal efficiency under different parameter combinations: Emission efficiency η = (V_ejected / V_total) × 100%, where V_ejected is the volume of discharged dust and V_total is the total volume of generated dust.

5. The dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser according to claim 4 is characterized in that: Set parameters for different materials: Stainless steel material: coaxial air pressure 0.3-0.4MPa, side-axis flow rate 380±20m / s; Aluminum alloy material: coaxial air pressure 0.2-0.3MPa, side-axis flow velocity 340±20m / s; Titanium alloy material: coaxial air pressure 0.4-0.5MPa, paraxial flow velocity 400±20m / s.

6. The dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser according to claim 5 is characterized in that: Also includes processing quality monitoring steps: The debris accumulation in the hole is monitored in real time by coaxial CCD, and the paraxial air blowing enhancement mode is triggered when the gray value change rate ΔG / Δt>5% / s; The strengthening mode includes: Increase the side-axle air pressure to 0.7-0.8MPa; Shorten the blowing interval to 100-200ms; Increase the nozzle swing range by ±5°.

7. The dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser according to claim 6 is characterized in that: The generation of the supersonic airflow negative pressure zone includes: A supersonic flow with a Mach number of 1.2-1.8 is formed in the extended section of the Lafayette nozzle; Through the Bernoulli effect, a negative pressure zone of -10kPa to -30kPa is formed 2-5mm away from the outlet; The suction effect generated by the pressure gradient is used to remove the residue at the bottom of the hole.

8. The dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser according to claim 7 is characterized in that: Post-processing steps are also included: After completing the stage 3 process, perform a two-way combined purge: Among them, the coaxial blowing is maintained at 0.2MPa, and the side-axis blowing operates at a frequency pulse of 0.5Hz, which lasts for 30-60 seconds until the temperature detected by the infrared sensor drops below 50℃.

9. The dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser according to claim 2 is characterized in that: Select the fractal scanning strategy based on the material type: Among them, stainless steel adopts a hexagonal honeycomb path with a single layer repeated 2-3 times; Titanium alloy uses a spiral involute path with an interlayer rotation angle of 15°-30°; And the molten pool area change rate ΔS / Δt is calculated in real time. When ΔS / Δt>0.5mm 2 / s automatically switches to the ring compensation path; Among them, the path compensation algorithm: P_corr = k1·(T_m-T_0)+k2·(V_e-V_0); Where: T_m is the real-time molten pool temperature, T_0 is the reference temperature, Ve is the actual blowing speed, V_0 is the set blowing speed, k1 = 0.05-0.1 mm / °C, k2 = 0.2-0.3 mm / (m / s).

10. The dual-path auxiliary blowing optimization simulation and experimental method based on ultrafast laser according to claim 7, characterized in that: Also includes IR feedback regulation: The temperature distribution at the bottom of the hole is monitored in real time through the coaxial optical fiber integrated infrared temperature measurement module, and the temperature gradient model is established at the same time: The ratio of the center temperature T_c to the edge temperature T_e is R = T_c / T_e; When R>1.5, nozzle swing compensation is triggered: Among them, the swing frequency is 1-3Hz, and the swing amplitude is ±3° to ±8°; Then dynamically adjust the Lafarge nozzle contraction ratio according to temperature feedback: When the contraction ratio β=0.6-0.8, the corresponding negative pressure range is -15kPa to -25kPa, and the adjustment rate does not exceed 0.1β / s.

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