This work is concerned with the improvement of dynamic performance of machine tools by attaching a viscoelastic vibration absorber.
In order to find the chatter characteristics and a position of a lathe where vibration amplitude is largest, modal testing was performed. The equivalent mass and stiffness for the chatter mode were calculated from the direct transfer function measured at tool post. The elastic modulus and loss factor of a viscoelastic material were obtained from excitation tests as functions of frequency and prestrain. With this information, the optimum tuning ratio and the optimum damping for the vibration absorber were achieved by adjusting the geometrical shape and magnitude of prestrain of the viscoelastic material.
The magnitude of the transfer function of the tool post is efficiently suppressed around the chatter frequency by using the optimized viscoelastic vibration absorber. It is also shown that the viscoelastic vibration absorber can be used in a case where the natural frequency of the lathe responsible for the chatter changes with moving of the tool post along the bed. The capability of the viscoelastic vibration absorber is also confirmed while cutting is actually performed.
