Bearing Force Monitoring in a Three-Shift Production Environment

Abstract

Premature failure of machine tool spindle bearings is a major problem in production that can result in enormous loss in production and spindle rehabilitation cost. The bearing internal contact force tends to change when the spindle is subjected to abnormal operating conditions. In this paper, the complicated variations in the condition of a grinding spindle in a three-shift production line were studied with a focus on examining the relative magnitudes of the main components of the race/roller contact force, e.g., the bearing initial preload, thermally induced preload, and grinding load, over an extended period of time. The results show that, a stable operating condition was achieved and that the dominant contact force component is the thermal preload. Significant preload variations were observed between shifts when the spindle was restarted. Excessive thermal preload which grew to a value of more than nine limes of the initial preload was also observed. Consequently, excessive preload is likely to be the main cause of premature fatigue failures. The study also indicates that the bearing preload provides a consistent index for monitoring bearing condition with a view to preventive maintenance.

Presented at the 50th Annual Meeting in Chicago, Illinois May 14–19, 1995

Notes

Presented at the 50th Annual Meeting in Chicago, Illinois May 14–19, 1995