Double-beam laser-assisted cutting method based on single-beam laser-assisted cutting

Abstract

The invention provides a double-beam laser-assisted cutting method based on single-beam laser-assisted cutting, relates to the technical field of laser-assisted machining, and aims to determine physical properties of a material to be machined, a softening and cutting temperature range and a thermal repair temperature range of the material, perform temperature field simulation by using finite element software, determine a laser parameter range required by laser irradiation, and perform thermal repair on the material to be machined. A to-be-machined material is fixed to a numerical control milling machine through a clamp, a first laser source is adjusted, the surface temperature of the material is monitored in real time through an infrared sensor, and the first laser source is adjusted; the first laser beam irradiates the surface of a to-be-machined material, and the milling tool makes contact with the to-be-machined material for milling; and the surface temperature of the cut machined material is measured, a second laser source irradiates the surface of the machined material, laser is adjusted, infrared sensor equipment is used for monitoring the temperature in real time, and the second laser source irradiates the surface of the machined material for thermal repair.

Description

Technical Field

[0001] The present invention relates to the technical field of laser-assisted machining, and particularly to a dual-beam laser-assisted cutting method based on single-beam laser-assisted cutting. Background Art

[0002] Laser-assisted machining technology (Laser-Assisted Machining, abbreviated as LAM) generally has three major processing methods: traditional machining, special machining, and composite machining. Laser-assisted machining is a type of composite machining. It irradiates a laser beam on the surface of the material to be processed on the basis of traditional machining, and uses the high energy of the laser beam to locally heat and process the material, thereby improving the cutting conditions during the machining process and enhancing the machining quality. During the laser-assisted machining process, the heated material surface will increase its own plastic domain and reduce its hardness. Combining with traditional machining methods (such as turning, milling, grinding, drilling, etc.) can more easily perform material removal and subsequent related processing on the workpiece.

[0003] Taking the difficult-to-machine material nickel-based superalloy as an example, although the cutting performance of the material can be improved and the tool wear can be reduced with the assistance of laser, some defects may occur during the machining process. Local heating can cause cracks on the surface or inside of the material. The generation of thermal cracks will affect the fatigue life and crack resistance of the material; due to the action of high temperature, the material surface may react with oxygen in the air to form oxides. Under high temperature conditions, the oxidation reaction will intensify, resulting in an increase in the thickness of the oxide layer, an increase in surface roughness, and hardening or softening phenomena, which will affect the service performance of the final component and its long-term service life.

[0004] Dual-beam laser-assisted machining is a machining method evolved from single-beam laser-assisted machining. Through the secondary heating effect of the dual-beam laser, the surface damage and internal stress of the material to be processed can be repaired and released to a certain extent, realizing the densification and uniformization of the surface structure of the material, and then improving the fatigue life and surface quality of the material. Therefore, dual-beam laser-assisted machining can improve and refine single-beam laser-assisted machining, and the purpose of obtaining a high-quality surface of difficult-to-machine materials can be achieved by controlling the temperature range.

[0005] CN116945376A discloses a dual-laser-assisted machining and repair integrated tool, including a tool body for cutting the workpiece, a machining laser assembly for heating the area to be machined of the workpiece, and a repair laser assembly for heating the peak of the tool marks on the surface of the workpiece. Using high temperature to melt the peak of the tool marks, and flowing to the trough under the action of surface tension.

[0006] CN116833580A discloses an in-situ laser-assisted machining system based on beam shaping. It is used to shape Gaussian laser into a focused beam with specific dimensions, shape and energy distribution form according to the thermodynamic properties of the material to be machined, effectively suppressing surface and subsurface damage of the material to be machined and prolonging the tool life.

[0007] In summary, laser-assisted machining is a commonly used method in the machining of difficult-to-machine materials, but some damages and stress generation during the machining process will affect the fatigue life and surface quality of the material. Therefore, it is very necessary to develop a method that can simultaneously perform subsequent repair and enhance the surface quality and fatigue life of the material. Summary of the Invention

[0008] Aiming at the deficiencies of the prior art, the present invention provides a dual-beam laser-assisted cutting method based on single-beam laser-assisted cutting. After single-beam laser-assisted cutting, the surface defects of the machined surface are repaired by the second beam of laser. There may be thermal crack surface layer and residual stress in the shallow surface layer formed due to growth stress and thermal stress on the material surface after laser-assisted cutting, as well as residual stress of surface milling marks and surface pits generated during the milling process.

[0009] A dual-beam laser-assisted cutting method based on single-beam laser-assisted cutting includes the following steps:

[0010] Step 1: Determine the physical properties of the material to be processed, its softening cutting temperature range and thermal repair temperature range;

[0011] Step 2: Use finite element software to perform temperature field simulation, temperature field simulation of the first beam of laser and temperature field simulation of thermal field superposition;

[0012] Step 3: Determine the range of laser parameters required for laser irradiation, specifically including laser power, laser moving rate, laser spot radius, irradiation angle of the laser beam and the distance between the laser and the material;

[0013] Step 4: Fix the material to be processed on the CNC milling machine through a fixture, adjust the first laser source, and use an infrared sensor to monitor the surface temperature of the material in real time. According to the temperature feedback, adjust the first laser source;

[0014] Step 5: The first beam of laser irradiates on the surface of the material to be processed;

[0015] Step 6: The local temperature at the irradiated part of the material to be processed rises, the plastic domain expands, and the hardness decreases;

[0016] Step 7: The milling tool contacts the material to be processed and performs milling;

[0017] Step 8: Measure the surface temperature of the machined material after cutting;

[0018] Step 9: Irradiate the surface of the machined material with the second laser source, adjust the power, focus, angle, and scanning speed of the laser, and use an infrared sensor device to monitor the temperature in real time;

[0019] Step 10: Irradiate the surface of the machined material with the second laser source for thermal repair.

[0020] The second laser source can be replaced by an electric arc, an ion beam, and an electron beam.

[0021] The beneficial effects produced by adopting the above technical solutions are as follows:

[0022] The present invention provides a dual-beam laser-assisted cutting method based on single-beam laser-assisted cutting. The present invention performs repair work on the surface of the material after cutting through a dual-beam laser-assisted processing technology to obtain a higher-quality machined surface. Heating and repairing the surface damage of the material is a process of using heating technology to repair or improve the damaged or deteriorated surface of the material. The present invention uses the heat provided by the laser beam to process the workpiece material in an integrated form that serves two different purposes: thermal softening and thermal repair. Temperature control during the heating process is very important. If the temperature is too high, it may cause further damage to the material and even deformation. At the same time, the length of the heating time also has a great influence. Too long or too short heating time will affect the repair effect of the material, and an appropriate time is helpful for surface repair. Laser heating mainly generates thermal stress and thermal energy stress release through the heat generated by the high energy of the laser to achieve the effect of repairing the surface damage of the material. By means of appropriate laser heating, the appearance and function of the material surface can be effectively repaired, its fatigue life can be improved, and its service life can be extended.

[0023] During laser-assisted cutting, due to the limitations and non-uniformity of the irradiation temperature, the change in temperature will cause thermal expansion of the material, generating thermal stress and causing tensile stress on the surface of the workpiece. During cutting, the tool contacts the workpiece and performs cutting, and the cutting force will act on the surface of the material. Among them, the tangential force and the normal force will generate a complex stress field, including tensile stress. At the same time, with the simultaneous progress of high temperature and cutting, the plastic deformation inside the material will cause the generation of tensile stress. These residual tensile stresses will cause surface damage and surface cracks on the material. The second high-energy laser beam provides non-uniform high-temperature energy. Due to the non-uniform surface temperature distribution, the surface of the material will undergo a certain deformation due to thermal expansion, but the degree of thermal expansion on the material surface will be larger than that inside, generating a temperature gradient and forming a temperature difference with the inside, which is prone to form thermal compressive stress. The generation of thermal compressive stress will inhibit the generation of damage such as microcracks and the release of residual tensile stress, which can effectively improve the performance of the material and reduce the risk of cracks and material failure. Description of the Drawings

[0024] Figure 1 This is the overall flowchart of the dual-beam laser-assisted cutting method of the present invention;

[0025] Figure 2 This is a schematic diagram of the dual-beam laser-assisted milling process of the present invention;

[0026] Among them, 1 - the first laser beam, 2 - the second laser beam;

[0027] Figure 3 This is a schematic diagram of the dual-beam laser-assisted milling process of the present invention;

[0028] Among them, (a) - the first laser beam irradiates on the surface of the material to be processed, (b) - laser-assisted cutting processing is carried out, (c) - the second laser beam irradiates on the defective surface of the processed material, (d) - the surface of the material after the experiment ends.

[0029] Figure 4 This is a schematic diagram of the workpiece surface before and after the irradiation of the second laser beam of the present invention;

[0030] Among them, (a) - a schematic diagram of the workpiece surface before irradiation, (b) - a schematic diagram of the workpiece surface after irradiation;

[0031] Figure 5 This is a diagram of the residual stress release direction after the irradiation of the second laser beam of the present invention;

[0032] Among them, (a) - the direction of the surface residual stress after the first laser beam-assisted processing, (b) - the distribution direction of the residual stress on the material surface after the irradiation of the second laser beam. Specific embodiments

[0033] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0034] In this embodiment, milling is taken as an example. This method uses dual-beam lasers for assisted processing. The dual-beam laser composite cutting technology is a "force-thermal-light" multi-energy field coupling and collaborative manufacturing technology, which reveals the typical construction mechanism of the composite energy field for microscopic material migration and removal, and realizes the efficient suppression of cracks in the processed surface layer and subsurface layer and the repair of other surface defects under the action of a small-gradient uniform temperature field. The schematic diagram of its processing process is as Figure 2 shown. The first laser beam irradiates on the surface of the material to be processed to expand the plastic domain of the material, and then traditional cutting methods such as milling are used for processing; the second laser beam irradiates on the surface of the processed material to repair the defects on the surface of the processed material. The two laser beams irradiate on the material surface simultaneously to form a processing and repair integrated system, improving the fatigue life of the processed material, improving the surface defects after processing, and increasing its service life.

[0035] A dual-beam laser-assisted cutting method based on single-beam laser-assisted cutting. In this embodiment, as shown in the flowchart Figure 1 shown below, it includes the following steps:

[0036] Step 1: Determine the physical properties of the material to be processed, as well as its softening removal temperature range and thermal repair temperature range;

[0037] In this embodiment, the nickel-based superalloy GH4169 material is taken as an example. The melting point of the GH4169 nickel-based superalloy is approximately 1300°C - 1350°C, the softening removal temperature range is 800°C - 1100°C, and the temperature range for thermal repair of the surface is 1000°C - 1150°C.

[0038] Step 2: Use finite element software to perform temperature field simulation, including the temperature field simulation of the first laser beam and the temperature field simulation of the thermal field superposition;

[0039] Step 3: Determine the range of laser parameters required for laser irradiation, specifically including laser power, laser moving rate, laser spot radius, irradiation angle of the laser beam, and the distance between the laser and the material;

[0040] Step 4: Fix the material to be processed on a CNC milling machine through a fixture, adjust the first laser source, adjust its power, focus, angle, scanning speed, and use an infrared sensor to monitor the surface temperature of the material in real time to avoid the temperature exceeding the melting point of the material. According to the temperature feedback, adjust the first laser source;

[0041] In this embodiment, a large piece of superalloy material is cut into a plate with dimensions of 100mm × 50mm × 20mm through professional wire cutting technology and fixed on a CNC milling machine, and program coding is performed on the milling machine; after optimizing the process parameters in the early stage, better processing parameters are determined: the heating temperature is about 800°C, the laser power range is 400W - 550W, the laser moving rate is 90mm / min, and the laser spot radius is 1mm.

[0042] Step 5: The first laser beam irradiates the surface of the material to be processed;

[0043] Step 6: The local temperature at the irradiated area of the material to be processed rises, the plastic region expands, and the hardness decreases;

[0044] Step 7: The milling cutter contacts the material to be processed and performs milling; during the process of high-energy laser irradiation, the plastic region of the material to be processed expands, making the cutting process easier to cut, the tool cuts more smoothly, and the cutting force is reduced compared to traditional milling.

[0045] In this embodiment, the material to be processed is fixed on a milling machine with a fixture, and a subtractive machining process of double-beam laser-assisted milling of nickel-based superalloy is carried out. The spindle speed is 1600 r / min, the feed per tooth is 0.03 mm / z, the milling depth is 0.3 mm, and the milling width is 6 mm for milling processing. As Figure 3 (a) shows, the first laser beam is irradiated on the material surface, and the temperature is adjusted by controlling factors such as laser power, and the temperature is adjusted to about 800 °C and irradiated on the surface of the material to be processed. Figure 3 (b) A four-edge cemented carbide milling cutter is used for milling cutting.

[0046] Step 8: Measure the surface temperature of the machined material after cutting;

[0047] Step 9: Irradiate the second laser source on the surface of the machined material, adjust the power, focus, angle, and scanning speed of the laser, and use an infrared sensor device to monitor the temperature in real time;

[0048] In this embodiment, as Figure 3 (c) shows, using the second laser beam, through position and power adjustment, it is irradiated on the surface of the material processed by the milling cutter at the same time, and the temperature is controlled at about 1000 °C. Figure 3 (d) Obtain the surface of the material after machining and repair.

[0049] Step 10: Irradiate the second laser source on the surface of the processed material for thermal repair. As Figure 4 shown, Figure 4 (a) is a schematic diagram of surface defects after the first laser-assisted cutting, Figure 4 (b) is the uneven temperature difference generated by the second laser, forming a compressive stress on the surface, the previous residual tensile stress is released, and defects such as cracks are repaired. After cooling for a certain time, when the surface temperature of the material drops back to room temperature, the surface of the processed material is finally obtained. As Figure 5 shown is a schematic diagram of the distribution of residual stresses before and after the second laser irradiation, Figure 5 (a) is the distribution direction of the surface residual stress after the first laser irradiation and cutting, Figure 5 (b) is the distribution of the residual stress of the second laser irradiated on the surface of the processed material. The uneven high-temperature energy is likely to generate a thermal compressive stress, which will release the residual tensile stress, thereby reducing the magnitude of the residual stress.

[0050] The second laser source can be replaced by an electric arc, an ion beam, and an electron beam.

[0051] The above description is only a preferred embodiment of the present disclosure and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) disclosed in the embodiments of the present disclosure that have similar functions.

Claims

1. A double-beam laser-assisted cutting method based on single-beam laser-assisted cutting, characterized in that: The following steps are involved: Step 1: Determine the physical properties of the material to be processed and its softening and removal temperature range and thermal repair temperature range; Step 2: Use finite element software to simulate the temperature field, the temperature field simulation of the first laser beam and the temperature field simulation of the thermal field superposition; Step 3: Determine the laser parameter range required for laser irradiation; Step 4: Fix the material to be processed on the CNC milling machine through a fixture and adjust the first laser source; Step 5: The first laser beam is irradiated on the surface of the material to be processed; Step 6: The local temperature of the irradiated part of the material to be processed increases, the plastic domain expands, and the hardness decreases; Step 7: The milling tool contacts the material to be processed and performs milling; Step 8: Measure the surface temperature of the processed material after cutting; Step 9: Irradiate the second laser source onto the surface of the processed material, adjust the laser power, focus, angle, scanning speed, and use infrared sensor equipment to monitor the temperature in real time; Step 10: Irradiate the second laser source onto the processed material surface for thermal repair.

2. The double-beam laser-assisted cutting method based on single-beam laser-assisted cutting according to claim 1, characterized in that: The laser parameter range in step 3 specifically includes laser power, laser moving speed, laser spot radius, laser beam irradiation angle and distance between the laser and the material.

3. The double-beam laser-assisted cutting method based on single-beam laser-assisted cutting according to claim 1, characterized in that: Specifically, step 4 includes: using an infrared sensor to monitor the surface temperature of the material in real time, and adjusting the first laser source according to the temperature feedback.

4. The double-beam laser-assisted cutting method based on single-beam laser-assisted cutting according to claim 1, characterized in that: The second laser source can be replaced by an arc, an ion beam or an electron beam.

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