| 摘要 |
PURPOSE:To accomplish a high-regid and high-precision device with a short bearing span by providing a plurality of helical grooves at either of contact surfaces of a shaft and a sleeve, and furnishing herringbone grooves with a specific angle situated between them. CONSTITUTION:When current is supplied to a motor stator 27, the rotor 26 rotates a shaft 23, a table 25 and a disc 28 simultaneously. Thereby, helical grooves 23A, 23B, and herringbone groove 23C allow a lubricant 24 to generate a pumping pressure, and high-precision rotation is obtained contactlessly with a sleeve 21A. At this time, the helical grooves 23A, 23B are given an angle 15-45 deg. to the rotating direction so as to cause generation of pressure at the lubricant 24 existing because of rotation of the shaft 23. The herringbone groove 23C is given an angle 80-90 deg. to the rotating direction. Thereby, nearly all areas of the grooves are filled with lubricant 24 stably.
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