Particularities of Tribological Behavior of the Contact Elements of the Precessional Gear, Made of Metallic and Plastic Materials

Abstract

For the first time, the gear contacts of the precessional transmission were subjected to experimental research, on tribomodels, using metallic (steel 40Cr) and polymeric (POM) material couplings in various combinations: steel 40Cr/steel 40Cr, POM/POM and POM/steel 40Cr. The experiments were carried out in conditions without contact lubrication and lubrication (MULTIS EP2). The samples - model, in the form of cylindrical rollers were manufactured from tested materials, with the dimensions established from the conditions of ensuring the geometric and kinematic equivalence of the contact of the precessional gear. The research methodology consists in the loading of the contact in steps with the normal force (Fn) for periods of time determined by the stabilization of the tribological characteristics, especially the temperature T generated by the friction process. The tribological behavior of the contact was determined by the evolutions in time of: the frictional torque (Mf), the temperature in the contact area (T), the friction force (Ffr) and the summary friction coefficient (fƩ). The purpose of the research was to experimentally establish the influence of the geometry and kinematics of the contact on the friction process and the tribological behavior of the couplings of materials under study, in the operating conditions of the contact without lubrication and with lubrication. The results of testing on tribomodels, according to the methodology proposed by experimental research, can be successfully applied to the design stage of Precessional Transmission (PT) gears.