Research on modeling and identification of machine tool joint dynamic characteristics

Abstract

The dynamic characteristics of a joint affect the machine tool operations notably. In this paper, an improved approach is proposed to identify the dynamic stiffness of the joint and to construct a relevant dynamic model. The theoretical dynamic model assembled of two beams is built using the frequency response functions. The identification formulas are derived based on the mechanical equilibrium condition and the displacement compatibility condition to describe the relationship between the assembled structures and substructures. Then an inconsistent equation containing the identification relationship is developed. The equivalent value of the dynamic stiffness is extracted employing the least square method. In the identification process, a part of frequency response functions, which is difficult to be measured, is considered as an intermediate variable to avoid introducing errors. According to the results, the calculated dynamic responses of the assembly show better agreement with the experimental measured data in comparison with the results derived from a typical method, which validates the feasibility. And the results demonstrate higher accuracy of the proposed method.