A novel identification technique of machine tool support stiffness under the variance of structural weight

Abstract

The preload-dependent stiffness of machine tool support was investigated in this study. A novel identification method of support stiffness has been proposed through the experimental modal analysis and finite element method. The support stiffness was identified with different machine weight during the assembling process of a machining center. Specifically, the structure weight increase of a machine tool in the assembly process causes its center of gravity to shift. Accordingly, the variance of support reaction affects the support stiffness. To explore the variance of support stiffness, the researchers of this study collaborated with a machine tool manufacturer. Impact testing was performed on each assembly stage. Additionally, finite element analysis was used to establish equations between the reaction force versus stiffness of supports under the structural weight variance. The obtained equations were used to predict the natural frequency and vibration mode of structures in various assembly stages. The maximum error between the experimental and simulated natural frequencies was 7.1%, and the minimum modal assurance criterion was 0.77. Finally, a modal analysis model that updates support stiffness automatically, which could be adopted by machine builders to develop new machine tool, is proposed.

Development of a Novel Dynamic Modeling Approach for a Three-Axis Machine Tool in Mechatronic Integration

“…A full-scale machine tool's finite element (FE) model is usually used to present the complete modal state of the machine tool. The model's millions of DOFs make computation costly and time-consuming [2], and it takes a long time to calibrate the FE model [3][4][5][6]. Therefore, a solution was developed to downscale the model by simplifying the high-order model to a model with lower DOFs but retained flexibility.…”