Motor built-in type main spindle device

摘要

PROBLEM TO BE SOLVED: To provide a main spindle device of a motor built-in system, capable of suppressing temperature rise of bearings and a rotary shaft due to heat generated by a rotor, preventing seizure of the bearing, and improving processing accuracy.SOLUTION: In a main spindle device of a motor built-in system, an outer peripheral annular groove 76 is formed on an outer peripheral surface of a rotary shaft 12 between a front side bearing 50 and a position where a rotor 20 is fitted onto the rotary shaft 12 in an axial direction. A carbon fiber composite material 73, which has a heat transfer coefficient smaller than that of the rotary shaft 12, is arranged in the outer peripheral annular groove 76.SELECTED DRAWING: Figure 3