TURBO-MOLECULAR PUMP AND ITS ROTOR

PROBLEM TO BE SOLVED: To provide a turbo-molecular pump 1 which has sufficient absorption capability for kinetic energy emitted by a moving blade body 4 without bolting-out of the moving blade body and safety for the peripheral apparatuses even if the moving blade body 4 is broken down caused by an excessive vibration and an internal abnormal state. SOLUTION: A projecting part 4C of an approximately cylindrical shape is provided on the central part of the moving blade body 4, and a recessed part 6D such as to fit to the projecting part 4C is provided on a shaft part 6. The main shaft joining structure of the moving blade body 4 forms a rotor 2 with joining the moving blade 4 and the shaft part 6 by fitting the projecting part 4C and the recessed part 6D. In the constitution of the structure, the ratio of the outside diameter of the projecting part 4C relative to the outside diameter of the shaft part 6 is set to be not less than 0.4, and the ratio of the axial length of the projecting part 4C relative to the outside diameter of the projecting part 4C is set to be not less than 0.5. COPYRIGHT: (C)2004,JPO