关键词: 超声振动, 微量润滑, 纳米流体, 钛合金, 车削加工

Abstract: By combining the ultrasonic vibration assisted cutting with nanofluid MQL, ultrasonic vibration assisted turning experiments were conducted for titanium alloys with different vibration directions and cutting speeds. The synergistic mechanism among diamond, graphene, diamond/graphene composite nanofluids and ultrasonic vibration was analysed. The results show that all modes of ultrasonic vibration may reduce the main cutting force and increase the compressive residual stress, but the ultrasonic vibration in depth of cut direction may enlarge surface roughness. During the ultrasonic vibration assisted cutting, graphene nanosheets may generate interlayer shear effect and enhance heat transfer, thus reducing the cutting forces, decreasing the values of surface roughness, and increasing the compressive residual stresses. The dominant effects of diamond nanoparticles are scratching and polishing under the conditions of high-speed cutting and vibrations in feed direction, which may reduce the values of surface roughness of Ra to 50%. Diamond/graphene composite nanofluid exhibites balanced performances and reduces the main cutting force and surface roughness than that of palm oil in all three cutting modes, namely the speed-depth of cut direction elliptical ultrasonic vibration-assisted low-speed cutting, the speed-depth of cut direction elliptical ultrasonic vibration-assisted high-speed cutting and the speed-feed direction elliptical ultrasonic vibration-assisted cutting. The maximum reductions of main cutting force and Ra were both larger than 20%.

Key words: ultrasonic vibration, minimum quantity lubrication(MQL), nanofluid, titanium alloy, turning