| 摘要 |
PURPOSE:To maintain the accuracy of rotation by preventing the deforming of outer races of both ball bearings between which an inner protrusion of an outer peripheral wall is axially interposed under pressure by following up radially outward displacement of the protrusion due to thermal expansion and the looseness of stationary preload due to the deformation. CONSTITUTION:An inner protrusion 22a is formed on an inner periphery of a rotor hub 22. Upper and lower ends of the protrusion 22a are respectively formed at upward and downward sectionally converging annular protrusions 22a1 and 22a2. Inner peripheries of inner races 18a and 20a of upper and lower ball bearings 18 and 20 are adhesively fixed to an outer periphery of a stationary shaft 16. The outer peripheries of outer races 18b and 20b are adhesively fixed to an inner periphery of a rotor hub 22 in a state that a lower end face 18b1 of the race 18b of the bearing 18 and an upper end face 20b1 of the race 20b of the bearing 20 are respectively brought into linear contact only with the protrusions 22a1 and 22a2. Thus, a stationary preload of a direction indicated by one-dot chain lines is applied to the bearings 18 and 20. |
