KINEMATICS OF THE BALL SCREW MECHANISM

This paper studies the kinematics of the Ball Screw Mechanism (BSM) wi th the aim of developing a foundation for understanding the motion of the balls and their contact patterns with the contacting elements. It is shown that there is always slip between the balls and the nut or sc rew, and therefore, the no-slip condition assumed in the BSM literatur e is not attainable. The effect of contact deformation on the motion o f the balls is also studied and is used to develop the pattern of the constant sliding lines of contact between the ball and the screw or th e nut. The results have applications in efficiency analysis, design, w ear evaluation and finite element modeling of the BSM.