Dynamic Modeling and Analysis of Intermittent Turning Process

Abstract

Increasing attention has been paid to the intermittent cutting process in modern metal machining industry. Research has been done in this thesis to develop a system model which can describe the intermittent turning process more precisely. In the development of the system model, the intermittent turning process is mathematically formulated and analyzed as a system associated with three periods, namely, the impact, cutting, and noncutting periods. The main methodologies used in this investigation are (1) applying modern control theory to perform dynamic cutting analysis in the cutting and noncutting periods, (2) employing wave propagation theory to study the impact force during the impact period, and (3) using numerical simulation and finite element method to examine the impact process and its effect on the machining performance. In this thesis, emphasis is focused on the effect of impact on the tool motion and the effect of the workpiece damping on the machining performance. The research results indicate that the impact between cutting tool and workpiece at the every beginning of each cutting period is the main cause leading to mechanical failures of tool during the intermittent machining. Laboratory experiments have been conducted, and the obtained results show a general, good agreement with the results predicted by the developed system model. An attempt has been made to construct a stability boundary map, which could be useful in practical applications.