Floating Roller Ball Bearings – A New Approach for Floating Bearings in High Speed Applications

摘要

Common bearing systems for machine tool main spindles use cylindrical roller bearings or elastically mounted spindle bearings to compensate the thermal expansion of the rotating shaft. Under certain loads both solutions reach their limit of functionality or show specific disadvantages. As a new approach to floating bearings in high speed applications this paper introduces the floating roller ball bearing. The bearing concept uses a new roller design which combines the advantages of both the line contact of a cylindrical roller bearing and the elastically mounted multipoint contact of a four-contact- point bearing. Thereby the line contact on the inner ring provides a high stiffness and the elastically mounted multi-point-contact on the outer ring prevents the roller to clamp between the inner and the outer ring. The kinematic behaviour of the bearing under different loads and operation conditions can be determined by a new calculation method. The model allows the tilting and skewing of the roller including an adapted determination of the Hertzian contact. By the application of a known local EHL friction model the roller’s axis of rotation can be determined.