Adaptive Active Control of Machine-Tool Vibration in a Lathe - Analysis and Experiments

Sammanfattning: In the turning operation the relative dynamic motion between cutting tool and workpiece, or vibration, is a frequent problem, which affects the result of the machining, and in particular, the surface finish. Tool life is also influenced by vibration. Noise in the working environment frequently occurs as a result of dynamic motion between the cutting tool and the workpiece. The research study includes the analysis of the statistical and dynamic properties of tool vibration in external turning, a foundation in optimal and adaptive signal processing that enables the active control of tool vibration in a lathe. It was found that the adaptive feedback control enables a broad-band attenuation of the tool vibrations, and is able to reduce the vibration level by almost 40 dB simultaneously at 1.5 kHz and 3 kHz. Further, the adaptive control reduced the acoustic noise level and it enabled a broad-band attenuation of the sound pressure in the frequency band 1.5 kHz to 25 kHz, with up to approximately 35 dB sound pressure level at 3 kHz. A significant improvement in the workpiece surface was also observed with the adaptive control.