Productivity of high speed milling operations can be seriously limited by chatter occurrence. Several studies on this self-excited vibration can be found in the literature: simple models (1 or 2 dofs) are proposed, i.e. a lumped parameter model of the milling machine being excited by regenerative, timevarying cutting forces. In this study, a model of the milling machine is proposed: the machine frame and the spindle were modeled by an experimentally evaluated modal model, while the tool was modeled by a discrete modal approach, based on the continuous beam shape analytical eigenfunctions. The regenerative cutting force components lead to a set of Delay Differential Equations (DDEs) with periodic coefficients; DDEs were numerically integrated for different machining conditions. The stability lobe charts were evaluated using the semi-discretization method that was extended to n dofs models. Differences between the stability charts obtained by the lumped parameter models and the stability charts obtained by the proposed approach are pointed out. The stability predictions obtained by the models are compared to the results of several cutting tests accomplished on an instrumented numerically controlled (NC) milling machine.
A theoretical-experimental model of a milling machine tool for chatter prediction
CATANIA, GIUSEPPE;MANCINELLI, NICOLO'
2010
Abstract
Productivity of high speed milling operations can be seriously limited by chatter occurrence. Several studies on this self-excited vibration can be found in the literature: simple models (1 or 2 dofs) are proposed, i.e. a lumped parameter model of the milling machine being excited by regenerative, timevarying cutting forces. In this study, a model of the milling machine is proposed: the machine frame and the spindle were modeled by an experimentally evaluated modal model, while the tool was modeled by a discrete modal approach, based on the continuous beam shape analytical eigenfunctions. The regenerative cutting force components lead to a set of Delay Differential Equations (DDEs) with periodic coefficients; DDEs were numerically integrated for different machining conditions. The stability lobe charts were evaluated using the semi-discretization method that was extended to n dofs models. Differences between the stability charts obtained by the lumped parameter models and the stability charts obtained by the proposed approach are pointed out. The stability predictions obtained by the models are compared to the results of several cutting tests accomplished on an instrumented numerically controlled (NC) milling machine.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
