Fast swept sine cutting test for CNC lathes

To mitigate chatter vibration in high-speed high-precision machining, the structure of machine tools and the cutting conditions must be optimized. Therefore, it is necessary to analyze the dynamic characteristics of machine tools. Such analysis is frequently conducted with an excitation test using an impact hammer because of its convenience. However, the dynamic behavior in the cutting process is often different from that in the resting state. It is difficult to analyze machine tools during cutting because of the rotating spindle and discharged chips. Therefore, this study proposes a method called fast swept sine cutting (FSSC) for measuring dynamic behavior during the cutting process. In the method, the cutting force is the excitation force applied to the machine tool system. The sinusoidal excitation of a CNC lathe during the turning process is realized by using a workpiece that creates a sinusoidal cutting force. The proposed method allows the frequency response, including that at the resonance point, to be observed. The dynamic behavior observed using the proposed method is different from that observed using conventional impact testing. The frequency response function during the turning process is affected by the nonlinearity of the cutting system.