65 Comparative Research on Static Stiffness between Vertical Machining Centers with Two Typical Pillars

In this paper, the authors compare the differences between two main types of pillar on vertical machining center: the box-type pillar and the seated-position pillar - through three aspects: first the structural differences, second the deformation to bear 3D external load; third the stress analysis based on the whole vertical machining center. Through the comparison, the conclusions can be obtained as: the bottom surface size of the pillar largely affects the static stiffness of the pillar; the X directional static stiffness of seated-position pillar is much higher than the box-type one; yet in Y Direction, the latter is a little higher than the former; the circular angle design on horizontal ribs of the pillar inner space can reduce the stress concentration on it.