An improved thermal estimation model of the inverted planetary roller screw mechanism

Abstract

The inverted planetary roller screw mechanism has recently become competitive in the electro-mechanical actuation system due to its high load-carrying capacity and small assembly size. However, a significant amount of heat at the frictional contact interfaces and power loss inside the electrical machine can be naturally generated in a compact and high-load inverted planetary roller screw mechanism system. The conductive heat leads to the temperature rise of inverted planetary roller screw mechanism components that subsequently results in thermal drift and error as well as the actuation accuracy degradation. An analytical approach is applied to calculate the friction torque of the contact pairs and support bearings in the inverted planetary roller screw mechanism system. As the thermal load, heat generation is derived from the friction in nut-roller-screw section and bearings. Then, the heat generation and convection boundary conditions are formulated to facilitate thermal behavior analysis. Finally, using the finite element method, steady-state and transient thermal-mechanical coupling analyses are performed to estimate the temperature distribution and thermal expansion of the inverted planetary roller screw mechanism components. Computational results reveal that operating conditions of rotation speed and external load have significant influence on the thermal characteristics of the inverted planetary roller screw mechanism. This study can serve as a foundation for modeling temperature field and analyzing coupled thermal-mechanical response of inverted planetary roller screw mechanism in electro-mechanical actuation system, which can be useful in determining thermal error compensation.

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

“…However, the method of simplifying the threaded tooth structure to a cylinder still requires further evaluation. Qiao et al 52 developed a comprehensive thermal error model to evaluate the thermal characteristics of the inverted PRSM system, based on the frictional moment of the mechanism contact pair and the support bearing, as shown in Figure 5. The relationship between the maximum equilibrium temperature and frictional moment of the nut and screw shaft, as well as the influence of heat transfer coefficient and screw speed on thermal errors were studied.…”

Thermal Model and Thermal Analysis of the Dual Drive Sliding Feed System

“…Therefore, when the screw Essentially, the actuator of the dual drive sliding feed system is similar to the driving mechanism of the planetary roller screw. Therefore, the differential sliding friction torque of the dual drive sliding screw pair is modeled and analyzed utilizing the friction torque modeling method of the planetary roller screw [17]. Taking the j contact area of the screw and nut as an example, the differential sliding friction of the contact area is integrated, and the differential sliding friction moment of the j contact area M dj can be obtained as follows:…”

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.…”