Reduction of Sticking in a Linear-Guideway Type Recirculating Ball Bearing

This paper deals with the reduction of sticking in a linear-guideway type recirculating ball bearing (linear bearing), which is the significant increase in the required driving force for a linear bearing in a back-and-forth short stroke operation. First, the driving force of a linear bearing with five carriage-body types (A-E, having different dimensions and shapes) under rolling moment load was measured. Simultaneously, the ball's position in the load zone was observed. The experimental results showed that regardless of the carriage-body types, the increasing rate of the driving force and the interspace (space between balls around the center of the load zone on the raised side) decreases and sticking tends to hardly occur as the maximum linear velocity and the stroke length increase. Also, the occurrence of sticking was affected by the carriage-body types. Finally, to examine the relationship of carriage-body types, carriage-body deformation, and the occurrence of sticking, the carriage-body deformation (caused by preloading and tightening torque of bolts) was calculated by finite element method (FEM). The FEM results showed that carriage-body type, which is more deformable, had a tendency to reduce sticking.