Stiffness analysis and optimization of a hybrid machine tool based on the stiffness matrix

The stiffness of a hybrid machine tool using a redundantly actuated parallel mechanism was analyzed by considering the deformation of the straight rolling slide-way pair and bearings. Stiffness assembly theory was used to develop the stiffness matrix for the machine tool. The impact of the straight rolling guide-way pair on the whole machine was also analyzed to optimizate design of the weakest part of the machine tool. The analysis results show that the position stiffness is symmetric along the x, y and z directions within a specified workspace, with the best position stiffness along the z direction and the worst along the x direction. The results also show that the straight rolling guide-way pair significantly affects the whole machine stiffness.