On-line control of machine tool vibration during turning operation

The paper describes a control system designed to improve the surface finish during turning by reducing the vibration of the machine tool. Vibration control is achieved by sensing the relative vibration between the tool and the work-piece, generating a force which tends to neutralize the excitation. The control system consists of an optical sensor for measuring the relative displacement between the tool and the work-piece, and a tool actuator for the control action, the optical sensor being made from a bunch of bifurcated optical fibers, whilst the tool actuator is an electromagnetic device. The control system has been tested experimentally during turning under various cutting conditions. The improvement in surface finish is verified by comparing two identical surfaces, one machined with and the other without the designed feedback- control device. Results indicate that the amplitude of vibration decreases by 33% whilst the resulting improvement in the surface finish is about 22%. The control device developed is quite simple and can be used in an industrial environment.