An improved method for tool point dynamics analysis using a bi-distributed joint interface model

The existing tool point dynamics analysis methods may lead to inaccurate predictions of frequency response function (FRF) in some cases since they ignored the collet geometry. This paper presents an improved method to better predict the contributions of collet geometry to FRF of cutting tool by introducing the effect of collet. The spindle-holder-collet-tool assembly is modeled as two distributed joint interfaces, i.e., collet-holder and collet-tool joint interfaces, rather than the existing single holder-tool joint interface without the effect of collet. Dynamics of the tool and the collet are analyzed using Euler-Bernoulli beam theory, and the tool-collet and holder-collet joint interfaces are separately treated as two distributed zero-thickness damped-elastic layers. The contact stiffness and damping properties of both joint interfaces are identified by minimizing the discrepancy between the measured and predicted tool point FRFs. The tool-collet assembly is supposed to rest on the resilient support provided by the spindle-holder assembly, whose dynamical property is analytically calculated by the receptance coupling substructure analysis (RCSA) method. Wider prediction capacity of the proposed method has been experimentally verified via the comparison with traditional method.