Author(s)

FRANCO CONCLI, LORENZO FRACCAROLI

Abstract

Nowadays the use of gears has significantly increased due to new materials available and to the high variety of possible applications. The necessity to investigate the gears behavior in different conditions plays a pivotal role for the evolutionary process of this so widely used mechanical component. In addition, the miniaturization process that is still growing in most of the engineering fields brings the necessity to accurately analyze the material properties, and fatigue behavior of gears having reduced dimensions. In this framework, in this work an experimental analysis combined with theoretical calculation was used for describing the fatigue behavior of 2 mm module gears made of 39NiCrMo3. Single Tooth Bending Fatigue (STBF) tests were performed according on a tensile testing machine. Since the machine grippers were not suited for fatigue tests on gears, a dedicated test-tool was appositively manufactured to exploit the Wildhaber W5 property. Tests were performed at different loading levels following the stair-case approach. Test were performed with a ΔF of 100 N. The fatigue limit was computed using the statistic Dixon approach that allows a precise calculation of the fatigue limit also with a reduced number of experimental data. The results in terms of measured forces were converted into the corresponding stresses using the ISO 6336 approach. Thereafter, the results were compared with the one stated in the ISO standard for the same steel material.

Keywords

gears, STBF, 39NiCrMo3, fatigue