Distribution characteristics of static stiffness for 6-UPS parallel machine tool

Abstract

To estimate the static stiffness of a cross-linked stewart type(BJ-04-02(A)) parallel machine tool, its distribution characteristics of the static stiffness in a workspace is researched. An analytical expression of a static stiffness matrix containing pose(position and orientation) is derived by combining two rotation transformation matrices based on Euler angles and rotation around a spatial axis. The distribution characteristics of the static stiffness in the workspace are revealed in the aspects of the distribution characteristics of the static stiffness in a given layer for a given orientation, the variations of the static stiffness with the coordinate z for a given orientation, the variations of the static stiffness with tilting directions and tilting angles. The distribution figures of the static stiffness in the workspace are obtained. The results show that the distributions of the static stiffness in different layers are similar and the static stiffness increases with the coordinate z and the translational stiffness is influenced slightly by tilting directions and tilting angles.