Influence of Materials on Dry Friction and Wear Performance of Harmonic Reducer Circular Spline

Abstract

Ductile iron and alloy steel are mostly used as the circular spline materials of harmonic reducers. The study of the differences in wear resistance of different circular spline materials is a strong basis for the design of high-precision and long-life harmonic reducers. The dry friction behaviors under room temperature of two ductile iron (low-load SHF and high-load SHG) alloys and steel (40Cr) circular spline materials were studied with a quantitative analysis of the alloy composition, microstructure, hardness and wear resistance. The results showed that the microstructures of SHF, SHG and 40Cr were graphite nodules within a tempered sorbite matrix, graphite nodules within a pearlite matrix and tempered sorbite, respectively. The hardness was inversely proportional to the wear resistance. The wear resistance of ductile iron was better than that of 40Cr, with SHF having the best wear resistance. The microstructure of the SHF and SHG ductile iron had a length of 8.1 μm, 5.9 μm (Ti, V, Mo)/C and Cu/Mg second-phase particles. Compared with tempered sorbite, the self-lubricating layer formed by the graphite nodules can effectively reduce wear. The proportion and average diameter of the SHF graphite were 1.2% and 30.9% higher, respectively, than those of the SHG graphite, providing a higher graphite spalling probability and longer graphite lubrication distance.