In order to study the influence of the joint part on precision stability of a machine tool

according to the characteristics of the column fastening joint surface of the precise vertical machine tool

the fastening joint surface feature with original error is measured. Then

the NURBS mathematical method is used to model the curve surface

and the 3D assembly model including the geometric surface feature error is created. Based on the joint characteristic error model

the boundary constraint load conditions from 500N to 8500N with gradual change is set. Based on the analysis of the non-uniform variation characteristics of stress field of non-uniform contact joint with characteristic error

the results show that there is a three-stage variation law in the joint region. It includes a large slope linear change stage

a curve change stage

and a small slope linear change stage. In particular

this variation characteristic is rooted in the nonlinear variation characteristic of the non-uniform contact of the high points

and it is verified that the geometric feature error of the geometric surface has a significant influence on the accuracy stability of the micron precision motion system.