Theoretical Contributions on the Selection of Possible Tribological Couples of Materials for the Manufacture of Precessional Transmissions

Abstract

Selecting gear materials is a great challenge for engineers. Gear teeth are subject to difficult and severe loading conditions. Simultaneous action of alternating normal and tangential dynamic stresses occurs, contact deformations accompanied by sliding friction. Gears are subject to increased requirements in terms of strength, geometric accuracy, dimensional stability, and durability. For the manufacture of gears, especially from thermoplastic materials, a theoretical argumentation of the materials is needed. An extensive study of thermoplastic materials, around the world needs to be done and the most efficient tribological couples to be chosen in terms of heat transfer from the gear zone, operation with or without lubrication, and gear life. In this paper, a theoretical synthesis of the Steel / Plastic, Plastic / Plastic, Plastic/Steel tribological couples is made, which were used in conformist and non-conformist experiments. Therefore, selected tribological couples are supposed to be used in the Precessional Transmissions applications.

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]:…”

“…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".…”