A 2D Ultrasonic-Assisted Turning Tool With Function of In Situ Vibration Amplitude Self-Sensing

The attenuation and fluctuation of ultrasonic vibration amplitude caused by the change of cutting load have become crucial factors limiting the precision improvement of the 2D ultrasonic-assisted turning (2DUAT). Therefore, the precise control of ultrasonic amplitude is very critical for 2DUAT precision improvement. However, it is difficult to arrange external sensors since the contact between the tool and the workpiece. Here, a novel 2D sensing and actuating integrated ultrasonic turning tool (2DSAIUTT) is proposed. The sensing and actuating of 2D amplitude are realized simultaneously with a single longitudinal-bending hybrid transducer without external sensors. First, the structure of 2DSAIUTT is designed and its open-loop characteristics are tested. Then, a negative feedback decoupler is proposed to overcome the coupling between the longitudinal and bending self-sensing signals, by which the self-sensing error is reduced by 70.1%. Finally, a cutting experiment under variable depth-of-cuts (DOCs) is carried out. The results show that the amplitude control error under variable DOC load is less than ±0.156 μm. Moreover, the precision is 70.8% higher than that of traditional 2DUAT, and the surface roughness of stainless-steel turning reaches Sa0.127 μm. These advantages show that 2DSAIUTT has great potential in the field of ultra-precision machining.