The Design And Application Of Ultrasonic Elliptical Vibration Device

Ultrasonic elliptical vibration cutting (UEVC) is a kind of cutting method, which attaching the high frequency vibration of cutting direction and chip flow direction on the top of the tool. It is an untraditional cutting method used in difficult cutting material and difficult cutting process.On the base of relative theories of UEVC, sandwich transducer was designed and made by PZT-8piezoceramics, and conical amplitude vibrator of half wavelength was designed. A suit of ultrasonic vibration equipment was built, which consisted of two signal generators and two vertical power amplifiers and two ultrasonic vibrators. According to modal analysis and structure optimism, the length of the amplitude vibrator is62.5mm, and the sympathetic vibration frequency and the amplifier coefficient are38781kHz and2.86respectively. The flange plat is27.5mm apart from the big surface.Resistance analysis equipment and laser vibration detector were used to measure the sympathetic frequency and amplitude of the ultrasonic vibrator. The offset between real frequency and theoretical one is0.27%and0.15%. The amplitude ranges from25nm to1500nm with the driving voltage varied from10V to500V. A formula was built to predict the amplitude. The actual measured elliptical locus matches well with the theoretical one, and the biggest offset is less than50nm.The influence law of cutting speed and elliptical vibration inclined angle and driving phase shift to the remained height of cutting surface was studied using Matlab. Experiments were designed to study the surface quality and cutting properties in UEVC cutting die steel NAK80and stainless steel S136and aluminum T6061. The conclusions drawn from the experiments are as follows:the lower is the speed, the tighter the elliptical vibration locus, and the better the surface quality; appropriate incline of elliptical locus help reduce the remaining height; surface quality can be improved when excitation voltage deviate90°slightly. UEVC can eliminate the crater wear in the rake face of NAK80and reduce the hard spots wear of flank surface. UEVC provides the cutting tool from crack in cutting S136. It can also suppress the chip stick and built-up edge in aluminum cutting.The tool vibrated in high frequency along the depth of cutting. As a result the vibration fills the deep groove in traditional cutting, and the surface outline in feed direction performs high-frequency vibration with tiny amplitude. The periodical cutting in and out of the workpiece caused by the high frequency vibration produces the cavatition, which can improve the friction and heat convection in cutting area. Therefore, UEVC improve the cutting ability and surface quality by reducing the stick of NAK80and the tremble of S136. The better cutting parameters are as follows:cutting speed is60-90r/min, and the cutting depth is25μm, the driving phase shift is75°, and the magnification time is50.