Cologno Monzese, Italy
Cologno Monzese, Italy

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Aggogeri F.,University of Brescia | Merlo A.,Centro Studi Industriali | Mazzola M.,University of Brescia
International Journal of Machine Tools and Manufacture | Year: 2010

This paper aims to study innovative structure solutions for Ultra High Precision (UHP) Machine Tools (MT) within machining applications at micro/mesoscale level (10-10 000 μm range). There are many aspects that can affect the accuracy of UHP machining performance. The most important issues are related to the static, dynamic and thermal behaviour of the machines. This paper shows a complete study and thermal testing validation on a set of prototypes (plates and beam) based on sandwiches with core made of metal foam (open cells) material impregnated by phase change materials. The proposed multifunctional structure (which provides high stiffness to weight ratio, good damping properties together with thermal stability) consists of a machine tool part, a beam (Z-axis) of a precision milling machine. The authors have designed, realised and tested prototypes developing thermal trials and then evaluating the experimental data. The trials consisted to test the prototype thermal stability when the environmental temperature varies in a specified range (20-50 °C), in order to assess the PCM proprieties to absorb heat and maintain performances for a long duration. Furthermore, a numerical-experimental validation through finite element analysis on the beam prototype is presented. © 2009 Elsevier Ltd. All rights reserved.

Bakker O.J.,University of Nottingham | Popov A.A.,University of Nottingham | Salvi E.,Centro Studi Industriali | Merlo A.,Centro Studi Industriali | Ratchev S.M.,University of Nottingham
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture | Year: 2011

In this paper the dynamical behaviour of a flexible part and an actively controlled fixture system is studied. Four active clamps are used for the control of the part-fixture system. Advanced finite element (FE) analyses have been carried out to model the part and the adaptive clamps. An accurate small-sized model of the part is established using the Craig-Bampton reduction method. A second-order model has been established for the adaptive clamps on the basis of the FE model. The supports and part-fixture contacts are modelled as spring-dashpot elements. Piezoelectric actuators are utilized to provide the forces required for the adaptive clamping scheme. A model-based control architecture has been incorporated and proportional-integral (PI) controllers are established for the individual clamps. After investigating the performance of the controllers for dynamic compensation, analysis shows that PI control can be used effectively to minimize the reaction forces on the supports, induced by deflection caused by machining forces.

Borboni A.,University of Brescia | Aggogeri F.,University of Brescia | Merlo A.,Centro Studi Industriali | Pellegrini N.,University of Brescia | Amici C.,University of Brescia
International Journal of Advanced Robotic Systems | Year: 2015

This study proposes a novel adaptive fixturing device based on active clamping systems for smart micropositioning of thin-walled precision parts. The modular architecture and the structure flexibility make the system suitable for various industrial applications. The proposed device is realized as a Parallel Kinematic Machine (PKM), opportunely sensorized and controlled, able to perform automatic error-free workpiece clamping procedures, drastically reducing the overall fixturing set-up time. The paper describes the kinematics and dynamics of this mechatronic system. A first campaign of experimental trails has been carried out on the prototype, obtaining promising results. © 2015 The Author(s).

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