Ntn Corporation

Teruyoshi Horiuchi

Junichi Hirata

An air turbine drive spindle capable of suppressing a pressure increase inside a through hole is provided. A spindle includes a rotary shaft and an outer circumferential member (a housing assembly, a cover and a nozzle plate). The rotary shaft is provided with a through hole. The outer circumferential member includes a bearing sleeve configured to surround at least a portion of an outer circumferential surface of the rotary shaft. The outer circumferential member includes a gas supply portion and a gas exhaust hole. The spindle includes a second gas exhaust portion (a first gas exhaust hole and a first gas flow passage). The second gas exhaust portion is independent of the gas exhaust hole and continuous to outside from a gas exhaust space.

Air turbine drive spindle

An air turbine drive spindle includes a rotary shaft, a bearing portion, a damper ring, a cover member, and at least one or more O rings. The bearing portion surrounds at least a portion of an outer circumferential surface of the rotary shaft. The damper ring is disposed at the outer circumferential side relative to the bearing portion with a gap being interposed therebetween. The cover member is disposed at the outer circumference side relative to the damper ring with a gap being interposed therebetween, and is configured to store the rotary shaft, the bearing portion, and the damper ring. At least one or more O rings are disposed in each of the gap and the gap.

There is provided a spindle device utilizing an externally pressurized gas bearing assembly, in which the center of a pulse disc of a rotary encoder can be adjusted to minimize an unbalance of the weight of the pulse disc and such unbalance can be adjusted easily to minimize fluctuation of the pulse disc during rotation and to achieve a highly precise detection of the rotational position consistent with the resolution of the rotary encoder. The spindle device includes an externally pressurized gas bearing assembly () for rotatably supporting a shaft (), a motor () for driving the shaft (), and a rotary encoder () for detecting a rotational position. A pulse disc () of the rotary encoder () is fixed on a mounting surface (S), arranged in the vicinity of one end of the shaft () and lying perpendicular to a central axis of the shaft (), by a fastening member () such as a bolt removably inserted through a fastening member inserting portion () provided in the pulse disc (). The mounting surface (S) is an end face of a mounting base () fixed to that end of the shaft (). This mounting base () is fixed to the shaft () by means of a plurality of radially extending set screws ().

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Iwata, Japan

Teruyoshi Horiuchi