THERMAL ANALYSIS AND OPTIMIZTION ON STEEL-WORM WHEEL WITH THE COATING

摘要

The steel worm wheel with thin coating is proposed to reduce the cost and the size in heavy-duty drive. The coating includes manganese phosphate conversion coating on the wheel and the copper galvanization on the worm. The intention of the coating is to improve the ability of the running-in and anti-scuffing of the steel worm wheel. The conversion coating on the specimen with the same material and surface treatment as the worm is obtained by dipping into the zinc and manganese/iron phosphate baths. The friction test on the specimens shows that the coating can reduce the friction of sliding contact and hold some lubricant in its porosity. At the same time, the bulk temperature in the specimen with coating is lower than that of bronze-alloy specimen under the same sliding velocity and pressure. In order to improve thermal performance of the steel worm gearing, a thermal model of worm gearing in steady state is established. Then, the temperature distribution on the steel wheel is analyzed using FEM software. Finally, On the basis of the analysis results, the structural modification on the steel wheel is presented to decrease the bulk temperature and heat stress.