Numerical control milling machine’s spindle systme vibrates under a non-harmonic force power with intricate changes

and that

the stiffness of spindle rolling bearing which is closely related to the characteristic of vibration is not a fixed value

but a function of load.By dint of finite element model of spindle system which is based on analysis of finite element software ANSYS

mode of a certain numberical control milling machine’s spindle system with the transient response theory and bearing dynamic stiffness theory is bult.With the loading datasheets and analysis of transient response in a certain milling condition

conclusion that lower order natural frequency

vibration shape

the maximal compositive deformation and the mode of spnidle system are not constant is deduced

and the design of spindle system should be caculated on the basis of dynamic stiffness of rolling bearing and dynamic mode of spindle system.