Determination Du Centre De Raideur Pour Les Machines-Outils - Application Au Tournage

TL;DR

This paper presents a method to determine the stiffness center of a machine tool through static characterization, aiding in understanding its dynamic behavior during turning operations and predicting tool vibrations.

Contribution

It introduces an experimental protocol to compute the stiffness and flexibility matrices, revealing the tool's movement patterns and their relation to vibrations during machining.

Findings

Identified the stiffness center and principal directions of stiffness.

Observed elliptical tool movements linked to vibrations.

Proposed application of method to high-speed machining.

Abstract

The determination of the stiffness center of a machine tool is a major element for knowing the dynamic behavior of this one. This stiffness center can be obtained from a static characterization of the machine tool. For an operation of turning, we present an experimental protocol to determine the stiffness matrix, then by inversion, the associated flexibility matrix. This step makes it possible to establish the privileged directions of the movement associated with the maximum and minimal stiffness as well as the stiffness center. Through this step, it is observed that, at the time of an operation of turning, the movement of the point of the tool is carried out according to an ellipse located in a tilted average plan compared to the machine spindle. This movement is linked with the self-excited vibrations. This analysis could be exploited and transposed in the case of the High Speed Machining. It will make it possible to predict various aspects of machining related to the behavior of the tool in the process of cut.