| 摘要 |
PURPOSE:To make the critical speed of a rotor as to its synchronous vibration sufficiently higher than its number of rotation available so as to make it possible to rotate a rotating member at extremely high speed by forming the rotating member from aluminium alloy in order to achieve weight reduction. CONSTITUTION:A sleeve 1 is formed of aluminium alloy and a metal film 11 which has abrasion resistance is provided on its inner peripheral face. A shaft 3 is also formed of aluminium alloy and a metal film 12 of abrasion resistance is formed on its outer peripheral face. The metal films 11, 12 of different materials are provided because if the metal film 11 formed on the sleeve 1 and the metal film 12 formed on the shaft 3 are of the same material then galling and/or seizure tends to occur. Thus, by forming the sleeve 1 from aluminium alloy, the rotor including a sleeve 1 and polygon mirror 6 can be made to weigh less. The critical speed of the rotor decided by its synchronous vibration can thus be made sufficiently higher than its number of rotation available. |
