103 / 2021-03-30 14:44:08

Estimation of dynamic characteristics of rigid body foundation using FRF-based substructure decoupling

Substructure decoupling,Frequency response function,Machine tool foundation,Rigid body,Elastic support

Low frequency vibrations generated during machining of machine tools lead to the relative displacement between the cutting tool and the workpiece. It directly affects the accuracy and surface finish of the products. To reduce the vibrations, it is insufficient to analyze the dynamic characteristics of machine tool structure alone because its dynamic characteristics are affected by the machine tool foundation. However, it is difficult to theoretically obtain the dynamic characteristics of the foundation. In this study, we propose a method for estimating the dynamic characteristics of the machine tool foundation from measured vibration data. The procedure is based on using the frequency response function (FRF) based substructure decoupling technique. The technique obtains the FRF of the foundation by removing the FRF of the machine tool structure from the FRF of the coupled structure of the machine tool and the foundation. As a basic study, we model a machine tool structure and a foundation using two rigid bodies with elastic supports. Using an analytical and an experimental model, the proposed procedure is verified. The results show that for the analytical model, the FRFs of the foundation are accurately estimated with the proposed procedure. However, for the experimental model, the misregistration between the predetermined locations and the exact locations of the connecting locations of the machine tool structure and the foundation decreases the estimation accuracy.