Research on cutting force and surface integrity of TC18 titanium alloy by longitudinal ultrasonic vibration assisted milling

In order to study the influence of spindle speed and amplitude on the surface integrity, TC18 titanium alloy samples were milled by the process of conventional milling and longitudinal ultrasonic vibration assisted milling. The experimental data were obtained by dynamometer, thermometer, scanning electron microscope, X-ray diffractometer, and three-dimensional surface topography instrument for observation and analysis. The results show that the spindle speed has a significant effect on the cutting force, cutting temperature, surface morphology, and surface residual stress. Compared with conventional milling, the surface micro-texture produced by longitudinal ultrasonic vibration assisted milling is more regular, and the cutting force and cutting temperature can be reduced by 34.1% and 19.5%, respectively. Then, the surface residual compressive stress and surface roughness can be increased by 50.9% and 163.88%, respectively. In addition, a certain depth of plastic deformation layer can be formed under the surface of ultrasonic vibration machining, and the depth of deformation layer increases with the increase of amplitude, and when the amplitude is 4 mu m, the depth of plastic deformation can reach about 5.2 mu m. This study lays a theoretical foundation for further research and optimization of ultrasonic milling technology for difficult machining materials.