Development of Harmonic Excitation technique for Machine Tool stability analysis

Abstract

<p>The project described in this thesis was to establish the instrumentation and technique for analysing stability of machine-tools against chatter by harmonic excitation. To test out the technique, two sets of experiments were performed on centre lathes:</p> <p>1) comparison of cutting stability with tour different types of boring bars, and</p> <p>2) comparison of cutting stability of a tool oriented in seven orientations in a single plane perpendicular to the spindle axis.</p> <p>The electro-dynamic exciter was used in 1) while an electro-magnetic exciter was used in 2) Data of the excitation tests were used to compute and plot the cross-receptances which indicate the limit width of cut together with the chatter frequency and the modal shapes which identify the main masses and springs of the structure. The contribution of the individual modes to the resulting degree of stability can also be obtained. Cutting tests were conducted to provide some means of checking the reliability of the excitation test results. In this report also included are the theory of vibration, theory of chatter and specification of various parts of instrumentation.</p>