Research On Ultrasonic Assisted Micro Drilling

At present，micro holes with diameter below0.2mm，depth-diameter ratiomore than ten, play an more and more important role in engine nozzle blade ofgas turbine microstructure hydrophobic surfaces and all kinds of micromachines key components. Ultrasonic assisted micro drilling (UAMD) is asignificant technology in processing this kind of micro holes. But still existproblems in the past research, such as, cutting force calculation is not accurate,microdrill is easy to break and life is short, micro hole quality is not high enough,the reasons are as follow,(1)kinematic analysis in UAMD is not enough，whichresult in calculation of cutting force is inaccurate;(2) there is no systematicresearch for the optimal processing parameters when drilling in difficultmachining materials, therefore, researchers need to find optimal processingparameters through experimental study.In this paper, firstly in view of kinematics，analyze the ultrasonic vibrationdrilling cutting track and thrust force and torque was calculated. Then, set up high-speed drilling and UAMD experiment system and drilling φ0.1mm microhole in304stainless. Finally the optimal processing parameters were obtainedrespectively. The main research of this thesis are as follows:(1)Trajectory equation on the cutting edge of the microdrill at any point isestablished and trajectory of cutting edge in UAMD is revealled. Than plotand compare the three-dimensional cutting trajectory of high-speed drill andUAMD, based on this, dynamic cutting thickness and average thickness ofcutting calculate method were put forward.(2) Proposed thrust force and torque analytic calculation method in UAMD,which is divided into three steps,“cutting edge decomposition—calculatecutting unit force—superimposed cutting unit force”. When calculate cuttingunit force three-dimensional oblique cutting model rectangular cutting model cutting unit working angle dynamic cutting thickness need to be combined. Bycalculating, thrust force and torque change trend in UAMD were obtained.(3) High-speed micro drilling experiment system were set up，in the system,conductφ0.1mm high-speed drilling single factor and orthogonal experiment,processing the measured experimental data (filtered, calibration,averaging) userange analysis and variance analysis. Obtain the optimal processing parametersin high-speed drilling.(4) By install ultrasonic vibration table and adjust the force measuringsystem，UAMD experimental system is established，which is in the basis ofhigh-speed drilling experimental system. In the system,φ0.1mm UAMD single factor and orthogonal experiment were conducted, processing the measuredexperimental data use range analysis and obtain the optimal combination ofexperimental level.(5) Using scanning electron microscope observe the micro hole orifice andwall，which manufactured by high-speed drilling and UAMD technology.Combined UAMD optimal combination of experimental level, obtain theoptimal processing parameters, verify the results of UAMD kinematic analysis.These research reveal UAMD cutting path which different from high-speeddrilling and propose cutting force calculate method which can calculate thethrust force and torque in any time. On this basis, design and conduct drillingexperiments, obtain the processing parameters, which provide guidance for theactual processing.