Abstract: In order to solve the problems of poor wear resistance and low fatigue strength of bronze worm wheel, new functional coating on the steel worm wheel is investigated. After the elastic contact analysis, tooth wear and bulk temperature on the worm gearing, the relational model between the material properties and stress, wear ratio and temperature on the tooth is established. A method is presented to evaluate the meshing performance, wear resistance, and anti-scuffing of worm gearing. Superfine manganese phosphate conversion coating and ferrous sulfide solid lubricant coating are formed on the surface of 20Cr steel by means of new processes. The tribological properties of the coatings are investigated on a friction and wear test machine. The steel worm gearings with the two coatings are tested on the transmission test-bed. The experimental results show that the steel worm gear with the coatings can reduce the running-in time, and improve the transmission efficiency and anti-scuffing capacity. The approach is very useful to the substituion of steel worm gearing for bronze worm gearing.

Key words: Coating, Friction and wear, Steel worm wheel, Transmission performance test, Worm gearing