Theoretical and Experimental Modelling of the Tribological Behaviour Aspects of Contact Elements in the Precessional Gearing (Pg)

Abstract

This paper deals with the theoretical-experimental model of the tribological behavior of the contact elements in precessional gears (PG) in the functions of conjugate profiles of linear velocities “convex-concave” or “convex-convex” for the corresponding geometric parameters (ρki, r, ρki – r) and the values of the kinematic force parameters (VE1, VE2, Vai) for each concrete position of the ki points. The calculation of the constructive-functional and kinematic parameters of the “roller-shoe” and “roller-roller” elements of the tribocouple were adjusted for the experimental verification tests on the SMT-1 installation and adapted to the specific test conditions of the tribocouples with conformal contact of gear teeth made of plastics, which will be subjected to sliding friction and rolling processes of the concrete tribocouple elements.

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

“…As a result of the previously conducted theoretical study [6,7], an algorithm was developed for the possible selection of metal and plastic materials for the "satellite (Z2) -immobile central wheel (Z1)" and "satellite (Z3) -mobile central wheel (Z4) couplings". According to this algorithm, the selection of combinations of metal and plastic materials in different versions of the couplings (steel-steel; steel-plastic; plastic-plastic) was argued, considering the ensurance of the tribological compatibility [8][9][10][11][12]:…”

“…When the constructive parameters vary, the geometry of the contact can be changed and, as a consequence, optimal values of the radii of curvature can be obtained from a tribological point of view. A variant of the precessional gear "immobile central wheel Z1 -satellite Z2"with concrete values of the constructive parameters δ, θ, β, Zg, Zg-Zb±1, subjected to tribomodeling [7], is presented in (fig. 2) where the values of the geometric parameters of the conjugated tooth profiles (𝜌 𝑘 𝑖 , 𝑟, 𝜌 𝑘 𝑖 -𝑟), the peripheral and sliding velocities(𝑉 𝐸 1 , 𝑉 𝐸 12 , 𝑉 𝑎 𝑖 ) for each position of the ki points are obtained when the contact moves on the tooth profiles, depending on the rotation angle Ψ ki of the crank shaft.…”

“…Resulting from ensuring the optimal tribological behavior, through the theoretical research previously carried out by the authors [6,7], the methodological premises for the possible selection of material couplings in combinations were argued: "steel/steel", "plastic/plastic" and "steel/plastic".…”