Research On Micro Rotary Ultrasonic Machining Mechanisms And Related Technology

Micro rotary ultrasonic machining (μRUM) is a novel non-traditionalhybrid process which combines the advantages of ultrasonic machiningand grinding. Researches prove that it could maintain the properties ofwork piece and have no demands for the conductivity of work piece, so ithas been widely used in the machining of hard-brittle materials. But theuncertain processing mechanisms limit further application of this method.Firstly, a constant feed μRUM set-up has been established in thispaper. Beside this, the measurement system and acquisition software forthrust force are also developed.A novel model for the prediction of the material removal rate ofμRUM under the ductile removal mode has been proposed whichconsidering the influence of the spindle rotation on the removal shape.Accuracy of the MRR model has been verified. The result indicates thatthe calculated results fit well with the experimental results under low feedrate while the error increases under higher feed rate. The reason for thisphenomenon is the removal mode has changed with the increasing of thefeed rate.Investigation on the thrust force in the processing of SiC ceramic hasbeen conducted. The influences of spindle speed, feed rate and ultrasonicvibration amplitude on the thrust force are studied. Besides that, the thrust force signals are analyzed in the frequency domain and it has beendisclosed that both low and high frequency signals could be detectedduring μRUM. The low frequency signal might be aroused due to tooldeflection and tool rotation while the high frequency signal probablycaused by the vibration of the ultrasonic system. After that, empiricalformulas of thrust force RMS value, cycle of low frequency force signal,cutting depths are deducted. Finally, different tool wear types and effectsof thrust force on tool wear types have been discussed.Furthermore, response surface experiments are conducted to study thethrust force and its components in the machining of titanium alloy. Rolesof machining parameters in the thrust force RMS value, cycle of lowfrequency force single, cutting depths have been analyzed. A FEM methodis also used to predict the theoretical thrust force with the help ofCOMSOL Multiphysics. Results indicate that prediction results fit wellwith the experimental results which prove the accuracy of the cutting depthcalculation method.Finally, this paper describes the preliminary design work of themulti-functional micro ultrasonic rotary machine. The mechanical structureand the servo control scheme are established. PMAC is chosen for lowerPC of the system and CNC system based on the LabVIEW has beencompleted;...