Wear analysis of the offset type preloaded ball-screw operating at high speed

In a high-speed ball-screw transmission system, a preload is always applied in the ball-screw to avoid vibration and backlash during all linear transmission periods. However, the sliding wear is the main reason why the applied preload decreases or vanishes. This study presents a new two body abrasion model combining the kinematic theory describing the variations in the axial wear depths with the operating strokes, which is related to the preload directly. The contact shape of the contact asperities is considered to be an elliptic area with a different ellipticity ratio to simulate the grinding trace of a raceway. The total wear depth of the axis direction is dominated by the wear depth of an asperity, the contact ratio between the plastic and normal contact areas, and the wear frequency due to the relative speed of the two contact surfaces. The axial wear depth increases with a raising operating stroke, an increasing rotational speed, and a small ellipticity ratio for the contact shape. Analysis of the results indicates that a high ellipticity ratio of contacting asperities on a raceway can effectively reduce the increasing rate of wear in an offset type preloaded ball-screw when operating in a high rotational speed. (C) 2012 Elsevier B.V. All rights reserved.