| 摘要 |
PROBLEM TO BE SOLVED: To secure a stable running condition of a bearing by quickly discharging the lubricant used for the inside of the bearing. SOLUTION: A main spindle unit is provided with a lubrication unit 32 which supplies a small amount of lubricant to bearings 12a, 12b via a nozzle 30 at a delivery speed from 10 m/s to 100 m/s and with a delivery quantity from 0.0005μm<SP>3</SP>/shot to 0.01μm<SP>3</SP>/shot. At a position in contact with an end face of an outer race 17, there are provided a plurality of radially elongating grooves 34 formed at a plurality of circular positions with predetermined intervals, annular passages 37 formed on a side of the radial grooves 34 opposed to the outer race 17 so as to be almost concentric with the outer race 17, and communicating grooves 36 for communicating the annular passages 37 with the radial grooves 34. The annular passages 37 are connected to an oil outlet port 38. COPYRIGHT: (C)2003,JPO
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