Research of the influence of geometrical factors on rotary accuracy of high-precision spindle

As an important component of machine tools, spindle is the end part directly determining the quality of machined surfaces. It is essential to guarantee the spindle rotary accuracy for improving the machining quality. Spindle rotary accuracy is determined by bearing accuracy and other components´ geometric error. Firstly, a 5-DOF bearing model is applied to describe the position and orientation deviations between inner ring and outer ring. It is also used to describe bearings´ rotational error. Secondly, the distance of curvature centers of inside and outside raceways is calculated when the position and orientation of inner ring changes, in consideration of the dimensioned and form errors of the inner, outer rings and balls. Small Displacements Torsor (SDT) is used to describe machining error of spindle. Finally, geometric factors such as shaft machining error, bearing´s preload and the assembly angle are discussed.