Research On Preload Evolution Mechanism Of Space Angular Contact Ball Bearings

In order to meet needs for spacecrafts’ services, spacecraft mechanisms not only overcome the hostile space environment, and ensure their high work qualities, but also consider their maintenance difficulty on orbit, hence reliabilities of spacecraft mechanisms should be improved. As a precision supporting element, rolling bearings’ preload technology determines their stiffness, rotation accuracy and working life, and also influences the operational reliability of rotational joints, even the entire organization. Thus, a preload evolution of rolling bearings has a very important significance on working of bearings, rotational joints and entire organizations. Aiming at rolling bearings’ preload evolution mechanism coupled with multi-factors of the space environment, this paper set angular contact ball bearings as an example and conducted a study on analyzing their preload evolution with alternating temperatures, bearings’ loads, wear, assembly relations and tightening torques coupling, and several work were carried out as follows:1) Static analysis for rolling bearings: considering alternating temperatures, rolling bearings’ loads, wear and assembly relations, a mathematical model and static equilibrium equations were established, and the preload values were obtained by solving the equations.2) Preload analysis for single one rolling bearing: based on the static model of rolling bearing mentioned above, the paper analyzed preload variations influenced by alternating temperatures, rolling bearings’ loads, wear, assembly relations acting or coupling, and angular contact ball bearings were set an example to calculate the preload variations by numerical simulation.3) Mechanics analysis for a shaft-bearing system: a mechanical model of a shaft-bearing system was established with interference assembles to shaft and bearing fits and tightening torques coupling, then angular contact ball bearings were set an example to calculate the initial bearing preloads by numerical simulation.4) Preload test experiments for a shaft-bearing system: according to characteristics of the shaft-bearing system model mentioned above, a preload test trial was designed and tested. Initial preload was obtained with one-dimensional force sensor, and compared with numerical simulation results, to verify relationship between initial bearing preloads, tightening torques and interference assembles.In this paper, through analyzing preload evolution mechanism of rolling bearings coupled with alternating temperatures, bearings’ loads, wear, assembly relations and tightening torques, a preload evolution mechanism was revealed and its influence orders with multi-factors were confirmed. This provided a theoretical reference on the preload evolution of rolling bearings, and ascertained a scope of initial preload properly.