| Nickel-based superalloy is widely used as aircraft engine parts, chemical processing, pressure vessels, steam turbine power plants etc. Its properties such as creep and corrosion resistance, as well as the abilities to maintain high strength-to-weight ratio, are vital for the economic exploitation of aerospace engines. But due to peculiar characteristics such as lower thermal conductivity,work hardening, presence of abrasive carbide particles,hardness, affinity to react with tool material etc makes it difficult to machine. In order to realize high speed and high efficient cutting of nickel-based superalloy, the tool wear mechanism on the cutting process is studied emphasizedly. Theoretical analysis, numerical simulation and experimental verification are applied in this research. The major research works are included as follows:1.Based on heat transfer theory and energy method, calorimetric method and temperature compensation were designed based on high-speed milling cutting heat test. The temperature variations of the water and the surroundings during the closed high-speed milling were then measured, and the cutting heat in the chip was calculated and compensated. The cutting temperature, cutting heat, cutting heat in the chip were calculated, and the effect of cutting speed,feed rate and tool wear on the power of chip and the cutting force,cutting heat distribution and the cutting temperature etc were studied. The cutting heat distribution of nickel-based superalloy was compared to carbon steel. The temperature distribution of in orthogonal cutting was simulated by FEM simulation. Based on the FEM simulation and the analytical method, the heat distribution in chip,workpiece and tool in different cutting speeds was investigated. The result of FEM simulation and analytical method accorded with the experimental results.2. The tool life and tool wear mechanism of carbide tools, ceramic tools and PCBN during high speed cutting nickel-based superalloy were studied. The effect of tool material, cutting conditions, workpiece material etc on tool life were investigated, and the empirical formula of tool life on high speed turning and milling GH4169 were established. The tool wear morphology and wear mechanism were studied by SEM, EDS and x-ray diffraction analysis on the tool rake face, flank face,chip and notch wear location. A method was proposed to monitor tool wear based on the cutting force.3.The chip morphology and chip deformation mechanism of high speed cutting nickel-based superalloy were studied. A cantilever chip edge shock model was established to calculate the impact force, impact pressure and impact frequency of chip edge on tool edge. Their effect on notch wear formation was studied. The measurement of the actual position of notch wear proved that only serrated chip edge and cutting burr can effect the notch wear position.4. Based on the above analysis and experimental basis, the impact fatigue characteristics of ceramic materials was analyzed and the temperature pulse calculation in the notch wear location was calculated. On the basis of theoretical analyses and calculations of high speed continuous impact force and tool notch surface temperature acted upon by burr and serrated chip edge, a notch wear model of low stress value and temperature impact fatigue was established. Saw-tooth-shaped burr and fin-shaped chip edge continuously impact the flank face and rake face at high speed and high frequency, which results in a V-shaped notch wear. The role of bonding is to change the direction of the impact stress, and accelerate the micro-crack initiating and propagating. The impact test of separate cutting burr was carried to investigate whether side cutting burr could create notch. A new cutting test-bed was devised to deburr and a lot of experiments were done in deburring cutting and normal cutting. The results of the experiments proved the correctness of the notch wear model. The method to suppress notch wear was proposed too.
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