PEFORMANCE OF TOUCHDOWN BEARINGS FOR TURBO MOLECULAR PUMPS

摘要

Recently, high vacuum environments are required for various highly technical and precision industrial areas. A turbo molecular pump is a high vacuum device designed to achieve approximately 10~(-8)Pa, which consists of several components including high-speed magnetic bearings. In the event that electric power is cut off from the magnetic bearing for any unexpected reason, load capacity is immediately lost. The rotor and the stator then make contact with each other resulting in complete failure of the pump. In order to protect the pump and magnetic bearings, auxiliary landing bearings (touchdown bearings) are incorporated into the pump design. NSK investigated the shaft behavior of the pump, and by determining the amount of load applied to the bearing, we developed specifications for a more durable and thermal stress resistant auxiliary landing bearing.