A dynamic stiffness model for high-speed ball screw pair with the mass center of screw nut considered

Abstract

The development of accurate dynamic stiffness models is a key aspect in the design process of ball screws. However, variations in the nut center of mass position can affect the dynamic stiffness, which makes it difficult to develop a stiffness model. To address this issue, this paper considers the variation of the nut center of mass position and the approach between the ball screw beam unit stiffness matrix and the nut interface element stiffness matrix. Then, based on Timoshenko beam theory and a concentrated mass parameter method, a dynamic stiffness model for a high-speed ball screw pair considering the variation of the nut center of mass position is developed. Finally, the feasibility of the dynamic stiffness matrix of the high-speed ball screw pairs is verified through the inherent frequencies obtained from experiments and simulations of the ball screw pair in the free state and compared with the classical finite element method to verify the importance of this method and to provide a theoretical basis for its dynamic design and structural optimisation.

Keywords

• ball screw
• center of mass
• timoshenko beam theory
• concentrated mass parameter method
• dynamic stiffness