Study on thrust force of ultrasonic-assisted vibration micro-hole drilling of titanium alloy

The thrust force dominates the chip formation and the inferior surface quality in micro-hole drilling titanium alloy. By employing the ultrasonic-assisted axial vibration drilling, a thrust force model was established based on the motion trajectories of the cutting edges both in the ultrasonic-assisted axial vibration drilling and the conventional drilling. The thrust force and the chip morphology were simulated through finite element simulation to compare with experimental data under the two machining methods. It was found that the mean value of the thrust force in ultrasonic-assisted axial vibration drilling dropped by about 9.5-20.8% compared with that in conventional drilling corresponding to the different duty cycle epsilon. The deviation of the thrust force between experimental results and the thrust force model was 15.4%. The results showed that the trend of the experimental thrust force was relatively in agreement with the thrust force model and the simulation results. According to the one-way ANOVA with F test, it was indicated that the feed rate and the ultrasonic amplitude played a significant role on the thrust force. The chips in ultrasonic-assisted vibration drilling were mainly with small sawtooth-shaped edges, and the length was shorter than that in conventional drilling.