In the last decades, unstable vibrations originated in the milling process, often referred to as chatter vibrations, have collected the interest of several researches, mainly driven by the detrimental effect this phenomenon generates on productivity, surface finishing and tool wear. Although several approaches and techniques have been developed nowadays, their industrial application is still limited by the required expertise, time-consuming procedures or relevant interventions on the machine tool structures. This research is focused on the investigation and design of active fixtures to mitigate chatter vibrations in milling, considering that this kind of devices could represent an appealing industrial alternative, due to the fact that they can be directly retrofitted to different machine tools and applied to different machining operations. The aim of this thesis was to improve the performance of intelligent active fixtures by carefully addressing the specific design challenges, both in terms of mechanical design and control aspects. The main focus was put in extending the device bandwidth in accordance with the requirements of a general chatter mitigation application, where chatter frequencies can easily reach and exceed several kilohertz. In particular, specific design guidelines and simplified modeling strategies, aimed at supporting the definition of an adequate mechanical design, are presented and discussed along with the selection of suitable actuation devices capable of granting the needed reliability, even when operated at high frequencies in demanding dynamic applications. Moreover, this work presents the development of a novel control strategy aimed at exploiting low-frequency excitation to disrupt chatter vibrations, without requiring the further extension of the device bandwidth nor the preliminary system identification and modelling, as generally needed for renowned model-based control techniques.

On the development of active fixtures for the mitigation of chatter vibrations in milling / Lorenzo Sallese. - (2017).

On the development of active fixtures for the mitigation of chatter vibrations in milling

SALLESE, LORENZO
2017

Abstract

In the last decades, unstable vibrations originated in the milling process, often referred to as chatter vibrations, have collected the interest of several researches, mainly driven by the detrimental effect this phenomenon generates on productivity, surface finishing and tool wear. Although several approaches and techniques have been developed nowadays, their industrial application is still limited by the required expertise, time-consuming procedures or relevant interventions on the machine tool structures. This research is focused on the investigation and design of active fixtures to mitigate chatter vibrations in milling, considering that this kind of devices could represent an appealing industrial alternative, due to the fact that they can be directly retrofitted to different machine tools and applied to different machining operations. The aim of this thesis was to improve the performance of intelligent active fixtures by carefully addressing the specific design challenges, both in terms of mechanical design and control aspects. The main focus was put in extending the device bandwidth in accordance with the requirements of a general chatter mitigation application, where chatter frequencies can easily reach and exceed several kilohertz. In particular, specific design guidelines and simplified modeling strategies, aimed at supporting the definition of an adequate mechanical design, are presented and discussed along with the selection of suitable actuation devices capable of granting the needed reliability, even when operated at high frequencies in demanding dynamic applications. Moreover, this work presents the development of a novel control strategy aimed at exploiting low-frequency excitation to disrupt chatter vibrations, without requiring the further extension of the device bandwidth nor the preliminary system identification and modelling, as generally needed for renowned model-based control techniques.
2017
Antonio Scippa
ITALIA
Lorenzo Sallese
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Descrizione: Tesi di Dottorato Lorenzo Sallese
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1081178
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