抄録
Machine tool spindles are forced a preload in order to improve the stiffness. However, actual preload changes are not clear though the spindle might be damaged when preload becomes excessive by the rise in heat by the rotation. In this report, a trial that the states of the spindles under the rotation are clarified by measuring an axial natural frequency of the spindle that actually rotates. Two spindles with different kinds of preload methods, fixed position preload and fixed force preload, were examined.
