Abstract
NAS 979 is a standard to evaluate accuracy of five-axis machining centers. Five-axis machining centers evaluate motion accuracy by to cut cone frustum in NAS 979. Geometric movement of five-axis machining center is determined by using form-shaping-function. This paper focuses to relationship between half apex angle and tilt angle of cone frustum. Movement of rotary axes can be divided into three types by relationship between magnitudes of half apex angle and tilt angle. Change velocity of rotary axis can choose by relationship between magnitudes of half apex angle and tilt angle. It became possible to determine command value, velocity, and acceleration of each axis mathematically, not experimentally.
