Shear-thickening polishing of inner raceway surface of bearing and suppression of edge effect

Abstract

Shear-thickening polishing is a non-traditional finishing method that uses the shear thickening effect by impacting the non-Newtonian fluid over the machining surface. As a result, it forms a velocity gradient that increases viscosity sharply, producing a flexible fixed abrasive tool to remove the material. Shear-thickening polishing is applied for finishing the outer surface of the rotary workpiece in previous work. The material removal distribution on the inner surface is completely different from those on the outer surface due to the different structure. The thickened slurry tends to form a relatively dense boundary layer on the surface, resulting in a decrease in the polishing quality and efficiency. The present study investigates the effect of impact angle of slurry and polishing velocity on polishing quality to obtain the uniform surface morphology of the ring's inner surface by the shear-thickening polishing process. The inner raceway of the outer ring of the tapered roller bearing 30203 was taken as the machining object. The numerical material removal model of raceway surface was built according to the rheological performance of shear-thickening slurry. A mathematical geometric model is used to explore the real impact angle of slurry. The model was able to accurately predict the experimental conditions, and the results of the simulation were in good agreement with the model's predictions. In the fixture, a guide block was introduced to guide the flow of the slurry, ensuring consistent material removal across the whole surface. The optimal experimental results show that the average surface roughness measured by Ra reduces from 300 nm to 42.9 nm in 30 minutes, which further drops to 11.16 nm in 90 minutes with a variance of 0.58 nm 2 . The conclusion could be drawn from the studies of this paper that uniform inner raceway surface of bearing is achievable through properly designed STP process.