| abstract |
(57) [Abstract] [Problem] To improve the life (seizure life) and rotation torque of a bearing used under high-speed rotation, reduce the rotation torque without reducing the life of the bearing, and further increase the price. Provide maintained rolling bearings. SOLUTION: The rolling bearing of the present invention is used at an inner ring 12 having an inner diameter of 6 mm or more and 10 mm or less and a rotation speed of 25,000 rpm or more and 60,000 rpm or less. 4 or at least one of raceways 1 of inner ring 12 The radius of curvature of 1, 13 is 52.5% or more 5 of the diameter of ball 15 The grease is a synthetic oil having a base oil kinematic viscosity at 40 ° C. of 25 mm 2 / s or more and 100 mm 2 / s or less as a base oil, and a urea compound as a thickener. |