Multifunctional structure solutions for Ultra High Precision (UHP) machine tools

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 pm 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 degrees 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. (C) 2009 Elsevier Ltd. All rights reserved.