| 摘要 |
PROBLEM TO BE SOLVED: To provide a planetary roller screw device having low friction on a sliding surface and excellent operation efficiency in conversion of rotary motion to axial linear motion. SOLUTION: A planetary roller screw device is provided with a screw shaft 1 having a screw groove 1a formed on an outer circumference surface, a nut 2 having a screw groove 2a opposing to the screw groove 1a of the screw shaft 1 formed on an inner circumference surface, a roller row comprising a plurality of rollers 3 rollably put between both screw grooves 1a, 2a, and two gears 4, 4 fitted on the nut 2. Oil pockets comprising a lot of minute hollow parts are formed on at least one sliding surface of the screw groove 1a of the screw shaft 1, a screw groove 2a of the nut 2 and rolling surfaces 3a of the rollers 3. Arithmetical mean roughness Ra of a surface on which the oil pockets are formed is set to 0.4μm or less. COPYRIGHT: (C)2008,JPO&INPIT
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