Evaluation of machine tools with position-dependent milling stability based on Kriging model

- An approach predicting position-dependent milling stabilities is proposed.
- The approach relies on the modal fitting, substructure coupling and Kriging theory.
- The Kriging model predicts relationships between positions and modal parameters.
- Using reorganized position-dependent tool tip FRFs to predict milling stabilities.
- The approach adapts to different tool-holder systems and benefits process planning.

Machine tool's milling stability is a function of the frequency response function (FRF) at the tool tip, which varies with the position changes of the moving components within the machine tool work volume. The approach to obtain stability lobe diagram avoiding chatter vibrations is generally based on some specific positions, resulting in an incomprehensive and inaccurate chatter prediction. This paper presents a new method to rapidly evaluate the position-dependent milling stability of machine tools. In this method, position combinations of the moving components are arranged to perform the impact testing, and then the corresponding identified FRFs at the tip of machine tool frame-holder base are acquired to identify the modal parameters, with which a Kriging model is developed to describe the relationship between positions and modal parameters. Consequently, based on the modal fitting technique, tip FRFs of machine tool frame-holder base at any position in the whole working space can be reorganized. And such tip FRFs are further adopted to calculate the tool tip FRFs with the identified contact parameters of the holder-tool system using the receptance coupling substructure analysis (RCSA) technique. Then, the milling stability at different positions can be assessed. Furthermore, the proposed method is applied to a vertical machining center, and its accuracy for predicting the milling stability in entire work volume is validated through chatter tests.