Experimental comparison between the Stribeck curves of water lubricated rubber bearing with straight and spiral grooves

Purpose The research purpose of this paper is to obtain a transition process of lubrication condition of water-lubricated rubber bearing (WLRB) by investigating Stribeck curve of WLRB with either straight grooves or spiral grooves using a comparison experiment and providing guidance for structure optimization and application extension of WLRB. Design/methodology/approach This study tested the Stribeck curve of WLRB with either straight or spiral grooves using a comparison experiment; the variables used are rotary speed and external load. Findings Stribeck curves of WLRB with straight or spiral grooves under varied load are obtained with the experiments, and the speed turning points when the lubrication condition of WLRB transit are acquired. Research results indicate that the transition of the speed turning point for lubrication condition of WLRB with spiral grooves is smaller than that of WLRB with straight grooves. Besides, it was found that within the whole speed range, the friction coefficient of WLRB with straight grooves decreases with the increase in load under the same speed. However, Stribeck curves of WLRB with spiral grooves show that the coefficient increases first and then decreases with the increase in load and finally comes to a steady value. Under the same rotary speed and external load, the friction coefficient of WLRB with spiral grooves is smaller than that of WLRB with straight grooves, claiming that the WLRB with spiral grooves has better lubrication properties. Originality/value By testing the Stribeck curve of WLRB with straight grooves or spiral grooves using the comparison experiment, lubrication properties of the WLRB are obtained. The transition mechanism of the lubrication condition for WLRB is acquired, revealing the effects of speed and load on the lubrication property. The research offers a scientific basis for the structure optimization of WLRB.