Research On Key Technology Of Ultrasonic Vibration Rounding With Flat End Milling Cutter

Machining technology in the 21 st century has put forward the requirements of high speed and high efficiency in cutting,it also puts forward higher requirements for the quality of cutting tools.The rounding process of cutting tool can eliminate the microdefects of cutting edge and edge surface by improving the profile,micro-shape and structure of cutting edge.Thus,the cutting performance of the tool is improved,the tool life is prolonged and the quality of the machined surface is improved.Therefore,the rounding of cutting edge is the basis of realizing high speed and high efficiency cutting and it is of great significance to study and optimize the rounding mechanism of cutting edge for improving the existing cutting tool condition.Based on the vertical rotary rounding method,a new type of ultrasonic vibration rounding was proposed to improve the rounding efficiency and effect.The discrete element method was introduced into the cutter blade rounding process,the rounding process of ordinary tool edge and ultrasonic vibration rounding process were simulated and analyzed by discrete element software EDEM(Engineering discrete element method),the cutting edge rounding experiment of the tool was carried out by using the self-made ultrasonic vibration passivator,and the cutting experiment of the passivated tool was carried out.The research contents include the influence of rounding time and tool speed on tool edge wear;at the same time,the cutting edge,edge condition and rounding radius of milling cutters passivated by rotary rounding and ultrasonic vibration were compared to verify the advanced of ultrasonic vibration rounding;and the cutting performance of cutters treated by different methods was observed to test the rounding effect.The main research work includes:(1)Based on the basic characteristics of tool planetary motion rounding and the basic principle of discrete element and Hertz contact theory,a simulation model of tool general rotary rounding and ultrasonic vibration rotary rounding was established by using discrete element software EDEM.By discrete element simulation,the effects of rounding time and tool speed on the motion of sic particles,the tangential cumulative energy of tool edge,the normal cumulative energy of tool edge and the amount of tool wear were studied and contrast analysis of two types of rounding,verify the advantage in the ultrasonic vibration passive way.(2)By means of coordinate transformation,the mathematical model of tool motion trajectory in common rounding and ultrasonic vibration rounding was established,and the trajectory simulation was carried out with MATLAB software.The simulation results show that the moving path of the milling cutter in ultrasonic vibration rounding is more complex,which leads to more frequent contact between the milling cutter and the passivated abrasive and improves the rounding efficiency.According to the design requirement and index of ultrasonic vibration rounding machine,an ultrasonic vibration rounding device is designed.It mainly includes a set of ultrasonic device,a set of planetary gear train mechanism and aluminum frame.At the same time,it selects the driving motor,designs and verifies the rotation shaft,key and gear,and uses Workbench to conduct static simulation and modal analysis of aluminum frame.(3)The rounding experiment was carried out by turning on and off the ultrasonic vibration device with the carbide milling cutter with a diameter of 6mm.Through Keyence depth microscope and metallographic microscope the results show that under the ultrasonic vibration rounding mode,the morphology of the milling cutter blade is better,and the rounding efficiency of the blunt radius of the cutting edge is higher.(4)With the help of Cr12 MoV die steel which dodge structure in hardened state as the processing workpiece,the milling experiments of carbide milling cutters without rounding,ordinary rounding and ultrasonic rounding were carried out respectively,cutting force was measured in real time by Kistler 9265 B three-way dynamometer.Through data analysis,it was found that the milling cutter with ultrasonic vibration rounding had more stable cutting force in milling and less cutting force,cutting force in three directions was reduced by about twice,it showed that the milling cutter after ultrasonic rounding had better performance and better rounding effect.By means of simulation,mechanical design and comparative experiments,this paper verifies the feasibility and advance of ultrasonic vibration rounding system,reveals the mechanism of rotary rounding and provides a basis for optimizing the rounding effect of milling cutter blade,laying a foundation for realizing high-speed and efficient cutting.