Self-excited vibratory drilling: A dimensionless parameter approach for guiding experiments

Abstract

Drilling assisted by axial vibrations at a low frequency is a promising machining process because, by naturally fragmenting chips, it can improve both productivity by cancelling stripping operations and workpiece quality by decreasing negative effects due to chip friction. Based on a theory of self-excited vibrations, a drilling device has been developed in the authors' laboratory. This technology is very compact and can be used on every conventional machine tool. However, experiments on these tools are quite difficult and long because of the numerous parameters influencing the vibrations. Therefore, in order to guide the experiments a dimensionless approach has been used to choose the cutting conditions and vibratory tool-holder properties. This approach permits the number of tests to be reduced since the machining process can be entirely described with only three dimensionless parameters instead of nine physical parameters. This paper presents the first experimental results on this new technology. In addition it shows the way that the dimensionless approach had been applied and validated to guide the experiments.