Modeling and optimization of turning process for thin-walled parts and slender tools

In the last decades, the effort of several researches was focused on the study and improvement of chip removal process in order to achieve an optimal compromise between accuracy and manufacturing costs. Despite several progress were made in that field, some machining process are still critic. Two of them are deep boring process and thin wall components turning. The presence of high compliance elements in the cutting system (i.e. tool in case of boring process and workpiece in case of thin wall components turning) lead to static deflection, responsible of geometrical errors, and unstable vibrations (i.e. chatter) that dramatically compromises workpiece surface quality and decrease tool life. In both of cases, the employment of suitable cutting parameters may mitigate the issue, but, at the same time, is correlated to a consistent decreasing of the productivity. For this reason, approaches that aim at modify cutting system response were developed in order to guarantee tolerance required and chatter stability. In this research three different solutions have been evaluated and developed. An active boring bar was designed in order to effectively damp vibrations in deep boring process. The focus of the research was focused on the strategy of integration of the actuator on the tool body, found to be crucial even if not yet addressed in literature. Designed active boring bar was realized and testes in order to demonstrate its effectiveness in chatter mitigation. For what concerns thin wall components turning, a strategy to detect the optimal support configuration, in order to guarantee tolerance required and chatter stability, was implemented and numerically evaluated. Finally, the effectiveness of passive devices (i.e. Tuned Mass Dampers) on chatter mitigation was evaluated. In the first part of the activity, an experimental procedure was followed in order to correctly design Tuned Mass Dampers (TMDs). Once their effectiveness was experimentally demonstrated, a model able to predict TMDs effect on workpiece dynamic response was developed in order to provide a support tool for Tuned Mass Damper design. This model was validated according with the experimental results collected in the first part of the activity.