Receptance Coupling for Tool Point Dynamics Prediction on Machine Tools

Abstract

Chatter has been a primary obstacle to the successful implementation of high speed machining. The frequency response function(FRF) of the tool point is crucial for identification of chatter free cutting conditions. In order to quickly acquire the FRF of the different components combinations of machine tool, the assembly of machine tool was always decomposed into several parts, where the fluted portion of tool, however, was always treated as a uniform beam, and the associated discrepancy was ignored. This paper presents a new method to predict the dynamic response of the machine-spindle-holder-tool assembly using the receptance coupling substructure analysis technique, where the assembly is divided into three parts: machine-spindle, holder and tool shank, and tool's fluted portion. Impact testing is used to measure the receptance of machine-spindle, the Timoshenko beam model is employed to analyze the dynamics of holder and tool shank, and the finite element method(FEM) is used to calculate the receptance of the tool's fluted portion. The approximation of the fluted portion cross section using an equivalent diameter is also addressed. All the individual receptances are coupled by using substructure method. The predicted assembly receptance is experimentally verified for three different tool overhang lengths. The results also show that the equivalent diameter beam model reaches an acceptable accuracy. The proposed approach is helpful to predict the tool point dynamics rapidly in industry.