The Vibrations of Radial-Drilling Machines under Test and Working Conditions:

Machine-tool chatter is essentially a problem of dynamic instability. A drilling machine under working conditions can be regarded as a dynamic system which for certain values of its system parameters becomes unstable and bursts into oscillations. The system parameters are determined by the static and dynamic characteristics of the machine-tool structure, the geometric shape of the drill, certain features of the work-piece material and the working conditions, and it is the interrelation of these which results in chatter or chatter-free machining. The paper commences with a discussion of the dynamic characteristics of radial-drilling machines. This is followed by an experimental investigation of the behaviour of these machines under working conditions, and finally a theory of drilling chatter is developed. The results of this theory are presented in the form of a stability chart which shows those drill speeds at which, for given values of the system parameters, chatter-free drilling is ensured. Although the...