Influence of initial braking velocity and braking frequency on tribological performance of non-asbestos brake shoe

摘要

Purpose - The purpose of this paper is to find the influence of the initial braking velocity and braking frequency on the tribological performance of the non-asbestos brake shoe used in mine hoisters during some continuous emergency brakings. Design/methodology/approach - The tribological performance experiments of the WSM-3 non-asbestos brake shoe braking on the 16 Mn steel are investigated on the X-DM friction tester, by simulating continuous emergency brakings of a mine hoister ten times. Three kinds of tribological indexes: friction coefficient, its stability coefficient, and wearing rate are considered to score the tribological performance of the brake shoe. Findings - When the initial braking velocity increases, the mean friction coefficient of the brake shoe decreases at first, then rises, and falls again finally. But when the braking frequency exceeds seven times, the falling process of the friction coefficient at low-velocity period does not appear again. Second, when the initial braking velocity is no higher than 10 m/s, the mean friction coefficient rises with the braking frequency increasing. But when the velocity exceeds 10 m/s, the mean friction coefficient rises with the braking frequency increasing at first, then falls. Third, when the initial braking velocity is no higher than 12.5 m/s, the friction coefficient of the brake shoe has quite a favorable stability with the coefficient is no bigger than 75 percent. But when the velocity exceeds 12.5 m/s, the stability of the friction coefficient is diminishing obviously. Fourth, the wearing rate of the brake shoe increases quickly, during the process that the velocity rising from 10 to 12.5 m/s, but increases much more slowly after that period. Originality/value - The paper investigates the tribological performance of the WSM-3 non-asbestos brake shoe during some continuous emergency brakings and finds that, when the initial braking velocity is no higher than 12.5 m/s and the braking frequency is no more than seven times, the WSM-3 non-asbestos brake shoe has quite a high friction coefficient, a good friction stability, and a low-wearing rate, which indicate that it is very appropriate for using in the disk brake of mine hoisters in China.