Effects of misaligned rails on the friction force-displacement curves of a linear ball bearing system in low-speed operation

This paper investigates the effects of misaligned rails on the friction force-displacement curves of a linear ball bearing system (which consists of two sets of deep groove type non-recirculating linear ball bearings, a table and a bed). Experiments showed that the measured friction force-displacement curves, of the linear ball bearing system, with aligned rails were rectangular-shaped hysteresis loops, while the corresponding curves with misaligned rails were trapezoidal-shaped hysteresis loops. In addition, the hysteresis loop area increased as the distance between table side rails decreased. Next, calculations for the total friction force expression due to differential slip and elastic hysteresis loss, including the effects of the misaligned rails, are presented. It was confirmed that the calculated total friction force-displacement curves closely matched the measured friction force-displacement curves for both the aligned and misaligned rail cases.