A theoretical and experimental investigation of the tool-tip vibration and its influence upon surface generation in single-point diamond turning

This paper presents a theoretical and experimental investigation of the influence of tool-tip vibration on surface generation in single point diamond turning (SPDT). Although it is well known that the relative vibration between the tool and the workpiece plays an important role in the surface generation in single-point diamond turning, most of the prior work has been focused on studying the relative tool-work vibration in the infeed (thrust force) direction while the significant contribution of the effect of the tool-tip vibration in the cutting force direction has been overlooked. In the present study, two characteristic peaks (twin peaks) are identified and found to be corresponding to the tool-tip vibrations by power spectrum density (PSD) analyses. The vibrations possess the features of small amplitude but high frequency. A physical model is proposed to capture the dominant factor based on the characteristic and it reveals that the twin peaks are attributed by the impact between the tool tip and workpiece and the process damping effect. Hence, a geometric model of surface roughness is proposed to take account of tool-tip vibration and it is verified through a series of experiments. The simulation results have been found to agree well with the experimental results.