Groove Design For Cutting Nickel-based Superalloy With High Efficiency And Research On Chip Breaking Mechanism

Inconel 718 is a difficult material to process,but its excellent properties make it widely used in many fields such as aerospace and electric power.This alloy has become one of the popular materials due to its excellent thermal stability,excellent fatigue resistance,excellent corrosion resistance and oxidation resistance.However,in the process of machining Inconel 718,due to the characteristics of complex crystal structure,the stress and strain are concentrated in the first deformation zone of cutting,which further leads to large cutting force and unstable fluctuation.Moreover,its poor thermal conductivity and high temperature of knife-chip contact interface lead to greater plasticity of the material and the chip is difficult to break.Therefore,when cutting nickel-based superalloy Inconel 718,how to make the chip efficient break is particularly important.Firstly,by analyzing the fracture mechanism of chip,the formation process,curling and breaking process of chip are studied,and the formation reason of sawtooth chip is analyzed.Through the theoretical calculation of the parameters of the tool and the tool groove,the chip control ability of different chip cutting groove cutting tools was explored,and the tool wear degree under different chip cutting groove cutting tools and different cutting parameters was analyzed.The thermal deformation behavior of Inconel 718 at high strain rate and high temperature,including the effect of temperature and strain rate on the yield stress,was investigated by separated Hopkinson pressure bar(SHPB)experiment.The parameters of JC constitutive model were calculated according to the results of SHPB experiment,and the constitutive model of Inconel 718 was established.Through high speed cutting experiments,the cutting ability of different chip cutting groove tools is compared.By comparing the cutting force and chip morphology in the cutting process,the performance of different cutting tools was studied.The experiment shows that the circular arc chip-breaking groove tool has the best cutting ability and chip control ability.The cutting process is simulated by finite element simulation,and the equivalent stress,strain rate and temperature in the cutting process are analyzed.The simulation results show that the cutting performance of the circular arc chip cutting groove tool is the best,and the chip has a larger curling radius and cutting temperature.Through orthogonal experimental design,with the chip break slot width L,tip band width b_r and chip break groove depth H as optimization factors,and the yield stress,strain rate,cutting temperature and cutting force of processed materials as evaluation indexes,the optimized chip break slot size parameters were obtained.According to the cutting experiment results,the tool wear morphology was observed and the type and stage of the tool wear were analyzed.Combined with the finite element simulation,the influence law of different chip groove cutting tools and different cutting parameters on the tool wear degree was studied with the tool surface wear amount and the tool surface wear distribution area as the main evaluation basis.The stress on the tool surface is mainly concentrated on the tool tip and the back part of the tool.The cutting speed has the greatest influence on the wear degree of the tool.