Dynamic characteristic analysis for machine tools based on concept of generalized manufacturing space

Aiming at studying the variation of the machine tools' dynamic characteristics in generalized manufacturing space, a concept of generalized modal and dynamic stiffness is put forward. Finite element method is employed to set up dynamic models for a three-axis gantry-type machine tool and a four-axis vertical machine tool. Modal and dynamic response analysis are carried out through out the whole manufacturing space with dynamic model modified method, in order to establish generalized modal function and stiffness map function respectively. By means of generalized modal analysis for three-axis gantry machine tool, the first five order natural frequencies of the machine tool through out the manufacturing space are obtained. The results show that the maximum change of natural frequencies can reach up to 25% during machining process, so complete modal information is obtained to provide data for performance optimization of machine tool. With the analysis of generalized dynamic stiffness for four-axis vertical machine tool, it can be concluded that the best working state in some frequency is not the best one for another, and then the theoretical support is present for the process optimization and accuracy promotion of machine tools.