Establishing a pattern in the influence of two-layer greasing on the wear resistance of rails

Serhii Voronin,Volodymyr Stefanov,Viktor Pashchenko,Oleh Holovan,Oleksandr Kharkivskyi,Besir Asadov,Ivan Hrunyk,Oleh Zabula,Yurii Chernichenko,Dmytro Onopreichuk

doi:10.15587/1729-4061.2020.204201

Abstract

This paper reports the results of an experimental study into the influence of two-layer greasing, formed from the graphite powder and base molecules of industrial oil, on the durability of the side surface of a rail head. Thus, increasing the concentration of graphite powder in oil from 0 to 3 % under a load of 363‒646 N decreases a wear rate by 42‒29.7 %, respectively. The study procedure implied modeling the process of rolling friction at slippage using rollers at the SMC-2 friction machine. This particular type of friction occurs in the tribosystem wheel flange the side surface of a rail head in the curved track sections. The supply of oil applying an aerosol technique was also implied. Two independent factors were varied: the concentration of graphite powder in the industrial oil I-12A and an external load. The constant factors were the roller rotation frequency, which enabled stable slippage at the level of 20 %, and oil temperature, and the duration of each test. The results of the experiment have made it possible to derive a regression equation, which describes the wear pattern of a roller in the friction pair «roller‒roller» depending on the selected factors. At the final stage of this work, we calculated a rail resource in the curved track section. The results of calculating a railroad rail resource under conditions of increasing the concentration of graphite powder from 0 to 3 % at external loads from 363 to 646 N have demonstrated an increase in the rail resource from 40 to 61 %. The calculation was based on the obtained experimental data, which characterize the friction process between the side surface of a rail head and the wheel flange in a curved track section under the conditions of two-layer greasing at various loads. The two-layer greasing was formed through the aerosol application of oil onto the friction surface with a different concentration of graphite. The data obtained make it possible to predict the service life of rails in the curved track sections under conditions of two-layer greasing

Highlights

Hrunyk PhDRegional Branch «Lviv Railway» JSC «Ukrzaliznytsia» Hoholia str., 1, Lviv, Ukraine, 79007 V
The practical experience of railroad operation demonstrates that one of the main problems in the interaction between rolling stock and a track is the interaction between a wheel and a rail
A decrease in the wear of the friction pair «wheel-rail» at the concentration of graphite powder in the oil from 0 to 3 % is associated with the influence of two-layer greasing on the characteristics of friction (Fig. 2). This is due to the filling of the microscopic irregularities at the contact surface with a layer of solid antifriction additive, which is graphite. This process contributes to the increase in the actual contact area almost to the size of the contour, which leads to the uniform distribution of the external load and, the reduction of the specific pressure in the contact area «a wheel flange – the side surface of a rail head»

Summary

Hrunyk PhD

Regional Branch «Lviv Railway» JSC «Ukrzaliznytsia» Hoholia str., 1, Lviv, Ukraine, 79007 V. ***National Academy of the National Guard of Ukraine Zakhysnykiv Ukrainy sq., 3, Kharkіv, Ukraine, 61001

Introduction

Literature review and problem statement

The aim and objectives of the study

Results of studying the impact of two-layer greasing on the wear of rails

Findings

Conclusions