Research On The Technology Of Ultrasonic Torsional Vibration Assisted Milling Titanium

With the development of aerospace industry, the requirement of difficult-to-cut materialsuch as titanium alloy is constantly increasing. However, traditional machining methods aredifficult to achieve high quality and efficient processing requirements, so the compositeprocessing method, which is called ultrasonic torsional vibration assisted milling (UTVM),was studied by experiment and finite element analysis methods when machining titaniumalloys. The cutting force, cutting temperature, residual stress and surface quality were studiedon UTVM, effects of ultrasonic vibration parameters and milling parameters on UTVMtitanium were discussed, so this study can help to achieve titanium alloy high quality andefficient processing.The trajectory of UTVM was analyzed, and the motion equation of tool nose relative toworkpiece was developed. Net cutting time ratio with different ultrasonic frequencys,amplitudes and cutting speeds was quantitatively studied. A detailed analysis of critical finiteelement theory for vibration cutting was carried out, and a three-dimensional model of millingprocess with workpiece ultrasonic vibration in the feed direction was developed. Thepulse-type cutting process of vibration milling was simulated.Based on results of finite element simulation and cutting force experiment, theseinfluences of process parameters (vibration frequency, amplitude, milling speed, feed pertooth) on the instantaneous value of cutting force in feed direction and the average cuttingforce in three directions were discussed. It is found that simulation results were agreed withexperimental results after milling force experiments.Finite element models of calculating temperature fields and residual stresses onmachined surface for ultrasonic vibration milling were developed. Cutter temperature fieldsand residual stresses on machined surface with or without ultrasonic vibration condition weresimulated, and the influences of processing parameters on cutting temperature and surfaceresidual stress were studied. In order to improve surface quality of milled surfaces of titanium alloy, the effects ofprocessing parameters on surface quality machined by side blades in UTVM wereinvestigated. Based on a series of UTVM experiments, the significance of these effects ofeach factor and interactive factors of processing parameters on surface roughness was studiedby variance analysis and response surface methodology. Processing parameters wereoptimized and prediction model of surface roughness was established.