Study Of Performance And Technique For Magnetic Field-Assistant Machining Of Nickel-based Superalloys

Nickel-based superalloys are widely used in aerospace,submarines,petrochemical industry and other fields because of its ability of retaining high mechanical and chemical properties at high temperatures.However,they are regarded as difficult to cut materials.Their low thermal conductivity will cause higher cutting temperatures during the cutting process,frequent vibration during the machining process will also reduce the stability of the system and worsens the surface quality and machining performance.In this paper,magnetic field is introduced to the cutting of nickel-based superalloys in order to alter material properties in-situ and in real time,reducing the machining vibration by using the eddy current damping effect.By doing this,the thermal conductivity will be increase and the stability of cutting will be improved.Consequently,cutting of nickel-based superalloys with high precision and low damage will be achieved.In this paper,the following researches are carried out on the magnetic field-assisted cutting of nickel-based superalloys:Firstly,the interaction between the magnetic field and the nickel-based superalloy during the machining process is analyzed.The eddy current damping model and the orthogonal cutting model under the action of the magnetic field are established.The simulation results show that the induced eddy current inside the rotating workpiece,showing the skin effect.The eddy current power dissipation caused by the eddy current damping effect is positively correlated with the magnetic field intensity and spindle speed.At the same time,the dynamic cutting process shows that,with the improvement of the thermal conductivity of materials,the degree of sawtoothing of chips is reduced,the cutting force was much more stable,and the surface roughness of the machined is significantly improved.Furthermore,the feasibility experiment study of magnetic field assisted cutting of nickel-based superalloys was carried out.The experimental results show that under the same cutting conditions,the application of the magnetic field has significantly improved the chip morphology and continuity,the surface roughness can be reduced by up to 44%,the surface P-V value is reduced by 49 %,and the surface ductility is improved,resulting in a better surface finishing of machined surface.At the same time,the application of the magnetic field makes the thrust cutting force more stable.When the magnetic field intensity is 0.02 T,the maximum vibration peak amplitude of the feed force is reduced by 78%,which proves the superiority of the magnetic field-assisted machining.Finally,a full factor experiment is used to explore the influence of different process parameters on the surface quality in the machining of nickel-based superalloys.The experimental results show that the surface roughness will be significantly reduced with the application of the magnetic field,increase with the decrease of the cutting speed,and decrease with the decrease of the feed speed.Then,the regression model between process parameters and surface roughness was established based on the Back Propagation Neural Network.The optimal process parameter combination was obtained by Firefly Algorithm(FA),and the accuracy and validation of the optimization results are validated by experiments.