A Multiscale Accuracy Degradation Prediction Method of Planetary Roller Screw Mechanism Based on Fractal Theory Considering Thread Surface Roughness

Abstract

The wear problems are vital to the planetary roller screw mechanism (PRSM) as they have a great influence on transmission accuracy, working efficiency, and service life. However, the wear characteristics of the PRSM have been rarely investigated in the past. In this paper, a multiscale adhesive wear model is established by incorporating the effective wear coefficient and considering the thread surface roughness. The variation of surface roughness is characterized by the two-dimension Majumdar–Bhushan (MB) function. The multi-asperity contact regimes are used to estimate microcontact mechanics of the rough interface. Moreover, the influences of surface roughness, material properties, and working conditions on the wear depth and precision loss of the PRSM are studied in detail. The results reveal that as the surface roughness increases, the total actual contact area, wear depth, and precision loss rate rise. In addition, the adhesive wear increases with the growth of the axial load, and decreases with the increase in the material hardness and material elastic modulus ratio to a certain extent. The investigation opens up a theoretical methodology to predict the wear volume and precision loss with regard to thread surface roughness, which lays the foundation for the design, manufacturing, and application of the PRSM.

Review on errors and transmission characteristics of the planetary roller screw mechanism

“…In addition, there have been lots of articles that focused on the modeling of mixed lubrication and lubricating oil viscosity. [103][104][105][106][107][108][109] However, previous lubrication studies ignored the effect of entrainment angle. Zhou et al 110 developed a transient mixed-EHL model that considers threedimensional surface roughness and discretionary entrainment velocity.…”

“…In addition, there have been lots of articles that focused on the modeling of mixed lubrication and lubricating oil viscosity. 103–109…”

Meshing characteristics analysis of planetary roller screw mechanism with misalignment

“…In the last decades, extensive researches on PRSM have mainly focused on kinematic analysis, 9,10 friction efficiency, 11,12 thermal characteristics analysis, 13,14 load distribution, 15,16 fault diagnosis, 17–19 and so on. For contact positions, Jones and Velinsky 20 obtained the locations of the PRSM contact points by utilizing the principle of conjugate surfaces and analyzed the principal radii of curvature at the contact points and the angle between the principal axes.…”

Design and Dynamic Analysis of the Recirculating Planetary Roller Screw Mechanism

“…The PRSM transmission system is quite efficient, highly reliable, and has strong bearing capacity [1,2]. It is strategically important and promising for aero electromechanical actuation (EMA) systems [3,4], the medical industry [5], CNC machine tools [6], and robotics [7,8]. The recirculating planetary roller screw mechanism (RPRSM) is a common type of the PRSM used for small stroke range, limited space, and high precision applications.…”