General Stiffness Analysis for Multi-Axis Machine Tool

The quality of multi-axis machining system is effectively affectted by the rigidity of flexible machine axes and joints, which is used to assemble the stiffness matrix at tool tip. In this paper, general stiffness model at tool tip is established for multiaxis series machine tool by principle of virtual-work and point transformation matrix. Through analysing the general stiffness characteristic, the formulation of local stiffness index is originally developed for multi-axis machine tool. It is shown that the rigidity of flexible machine axis has a significant effect on the quality of machine tool and it is necessary to take the rigidity of flexible machine axis into account. Additionally, sensitivity of mechanics parameter of flexible axis and spindle is discussed by one instance of a type of five-axis machine tool.