자기베어링이 적용된 미세홀 가공용 드릴링 스핀들 개발

Abstract

For special materials such as tempered glass, ceramics and silicon, micro-holes less than 1 mm in diameter are generally machined through drilling using high speed spindles, but their productivity is very low due to slow machining speed. Further, when a plurality of fine holes are machined on a large-area wafer, if the machining drill is damaged and any machining failure occurs, the entire wafer becomes defective and the cost loss becomes large. In the field, maintenance costs are very high because drills are replaced periodically to avoid these defects. Applying a magnetic bearing to the spindle for micro-hole machining eliminates friction and wear between the bearing and the rotor, eliminating the need for bearing maintenance. In addition, the control current of the magnetic bearings can monitor the drill abrasion and machining conditions to prevent unconditional drill replacement, thus reducing maintenance cost and preventing machining failure. In this paper, we designed and fabricated 80 000 r/min micro-hole machining spindle equipped with magnetic bearings, and presented rotational and machining test results.