| 摘要 |
PURPOSE: A vacuum pump is provided to prevent a rotor from being damaged by reducing stress concentration in a finish portion of a screw. CONSTITUTION: A rotor of a vacuum pump is formed by: a spiral screw thread(5a) protruded into the surface of a rotor(5); a screw groove(5b) formed in an axial direction between two adjacent lines of the screw thread; and a finish portion(5d). Also, an inclined portion(5e) is formed along the height portion of the screw thread from the finish portion and reduced down to the screw groove. In the vacuum pump, the inclined portion forms the height of the screw thread for the screw groove concentrated in stress. Therefore, stress concentration is reduced on a screw thread root caused by the difference in thickness between portions having a screw thread and not. Also, the rotor is not damaged by a crack.
|
