Research on the Modeling of Bending-Torsional Coupling and Vibration Characteristics of Planetary Roller Screw Mechanism

A general bending-torsional coupling dynamic model of the planetary roller screw mechanism is developed by the lumped mass method in this paper to analyze the vibration characteristics. Firstly, the components of the planetary roller screw mechanism are treated as lumped mass, and the meshing relationships are expressed by the spring element. Secondly, the natural vibration characteristics of the planetary roller screw mechanism are analyzed, and four vibration modes based on the bending-torsional coupling dynamic model are summarized: carrier mode, torsional mode, transverse mode and roller mode. This reveals the vibration characteristics when the two kinds of meshing pairs (thread pair and gear pair) come into meshing synchronously. Then, the relationships between the structural parameters and the natural frequency of each vibration mode are discussed. Finally, the matrix equation is simplified according to the characteristics of vibration mode, and the analytic expressions of natural frequency under carrier mode and roller mode are obtained.