Rolling Surface Of Wheels Research Articles

Analysis of the influence of brake pad material on the formation of defects on the rolling surface of railway wheels

The results of research and production experience in the field of identifying the causes and mechanisms of defects on the rolling surface of wheels of railway rolling stock are analysed. The article presents different views on the mechanism of influence of brake pad material on the occurrence of wheel surface defects caused by their frictional interaction with pads made of cast iron or composite material in the form of a composite rubber compound. It has been clearly shown that brake pads made of composite rubber compound damage the rolling surface of wheels to a greater extent and more often. This leads to the need to grind wheel sets and reduces their service life. The main cause of defects on the working surface of the wheels is the thermal load on the friction zone between the pad and the wheel during train braking. The temperature in this zone changes periodically and can reach 900 °C, while the self-ignition temperature of the rubber compound used to make the friction element of composite pads is 350-500 °C. The unacceptably high temperature in the friction zone between the composite pad and the wheel surface, which occurs during train braking, is due to the relatively low thermal conductivity of the composite rubber compound compared to the thermal conductivity of cast iron. Equipping the friction element of composite pads with cast iron inserts does not save the situation with regard to the low thermal conductivity of such pads in general and their tendency to damage the rolling surface of the wheels of vehicles. Recommendations have been proposed to improve the technical and economic performance of railway transport by improving the quality of brake pads for vehicles.

Determination of cutting modes when turning railway wheelsets used in heavy traffic

Increasing the durability of the cutting tool when restoring the profile of the rolling surface of railway wheels by controlling the vibrations of the machine-tool-part system. Vibrations arising during the turning of the rolling surface of wagon wheels under various cutting modes were studied. To do this, a matrix of experimental planning was built using the Box-Wilson method, according to which all factors change in turn (cutting depth, cutting speed, feed). After the experiment, a mathematical model is selected and the numerical values of the coefficients of this equation are estimated. In accordance with the power dependences accepted in the theory of cutting, a mathematical model was constructed for the experiments in the form of a logarithmic polynomial of the first degree series. Mathematical processing of measurement results using fractal dimension was carried out. The fractal dimension was determined by the normalized span method. A correspondence has been established between the durability of the he cutter and the intensity of its vibrations when turning railway wheels. A mathematical dependence of the fractal dimension on the cutting modes is obtained, which makes it possible to adjust the cutting speed or feed during the restoration of the rolling surface of the wheel in the presence of defects. Optimal cutting modes, which allow to achieve a given quality of the rolling surface of the wheel in the shortest possible time, give the highest value of fractal dimension. Defects in railway wheels such as sliders, bumps, and gouges lead to a decrease in fractal dimension. The determination of the fractal dimension in the process of turning wheelsets makes it possible to automatically adjust the cutting modes to ensure a given quality of the rolling surface of the wheel and the required durability of the cutting tool.

Studying the load of composite brake pads under high-temperature impact from the rolling surface of wheels

The object of the research is the processes of thermal stress, perception and redistribution of loads by the brake composite pad during braking of the car in operation. In the current conditions, wedge-dual wear of composite brake pads is observed in the braking systems of freight cars, the feature of which is the deterioration of the braking efficiency of freight trains. With this type of wear, both an increase in the load on the brake pad and an "underuse" of the amount of pressure on it can occur. A comprehensive thermal calculation was carried out for composite brake pads with uniform and wedge-dual wear. The results of the calculation showed that the amount of pressure on an abnormally worn pad is 23.3 % less than that acting on a pad with nominal values. It has been proven that the change in the pressure force on the composite pad with different values of the wear parameters during braking leads to a change in the braking force that occurs between the wheel and the rail during braking. The calculation of the strength of the composite brake pad with wedge-dual wear was carried out. The obtained results will make it possible to develop measures to modernize the elements of the brake lever transmission of freight cars. The field of practical use of the obtained results is car-building enterprises. The conditions for the practical use of the results are the brake lever transmissions of carriages of cars with a gauge of 1520 mm. The conducted studies prove the negative impact of wedge-dual wear not only on braking efficiency, but also on the strength of brake pads. This makes it necessary to create measures aimed at its elimination, which will contribute to increasing the level of train traffic safety and significantly reducing the operational costs of maintaining freight cars

Доңғалақ пен рельстің өзара әрекеттесу жүйесінің ағымдағы жағдайы

The article considers the current state of stable interaction of the wheel-rail system, one of the main and resource-intensive problems that has long remained acute in the field of railway transport. The types of wear between the wheel and the rail have been thoroughly studied, and the results are shown in a graph and diagram. It can be seen from the results that intensive wear of the rolling surface of wheels and rails on curved sections of the road prevails over other types of wear. So far, many proposals have been proposed and work has been done to prevent this wear and tear. However, the work done clearly showed that it was not possible to completely solve the problem of intensive wear of wheels and rails on curves. The costs of material resources associated with excessive wear of the wheel-rail system in the locomotive, wagon and road facilities, primarily on curved sections of the track, are at a fairly high level. Therefore, it is necessary to continue work on their reduction.

Features of restoring the rolling profile of wheels coming into turning during repair

The main objective of the performed studies was to improve the durability and operability of railroad wheels and make lower the costs of acquiring new ones by means of an innovative technology development for wheel profile rehabilitation and further restoration of physical and mechanical properties of the rim metal and improvement its structure. The information consists the facts about the nature of wheel pairs damage in operation, machine-tool equipment and cutting tools, used to restore the surface, based on the analysis of which a new rational technology for repair of wheel pairs on the rolling surface profile with subsequent restoration of the original operational properties is collected. A new method of wheel rolling surface profile restoration has been developed, which includes highperformance plunge grinding and subsequent induction heating (thermocycling), resulting in the formation of structures that lead to increasing of hardness and formation of compressive stresses, which has a positive effect on the efficiency of wheel rolling surface operation. This increases wheel life and safe operation of rail rolling stock. The implementation of the wheel profile recovery method with the help of highperformance plunge grinding and induction heating of wheels will lead to increased efficiency of railway rolling stock and reduce the need for the purchase of new wheelsets.

Stand for accelerated tests of rail vehicles wheelsets

Tests and research can be greatly accelerated by applying a multi-point load to the test wheel. The aim of this work is to substantiate rational parameters of the stand for accelerated life tests of railway wheelsets, in which a multi-point load applies to the rolling surface of the test wheel. On the basis of the laws of the theory of elasticity, we performed analytical calculations of the contact stresses created by the rolling bodies of the load mechanism of the test stand. Research has shown that the dependence of the contact stresses on the wheel rolling surface on the ball’s diameter is nonlinear. The decrease in stress is due to an increase in the contact area. We obtained the analytical and graphical dependencies, which make it possible to evaluate the influence of the parameters of the stand for accelerated life tests of railway wheelsets on contact stresses on the wheel rolling surface, taking into account the shape and dimensions of this surface. The authors have proposed a stand design for accelerated life tests of railway wheelsets. The use of a stand with the parameters justified in this work will reduce the test duration by 10-15 times.

Badanie zmęczenia metalu koła pojazdu szynowego z uwzględnieniem intensywności zużycia powierzchni tocznej

The article overviews scientific research studies that examine the interaction between railway vehicle wheel and rail, and the phenomena of wear on wheel rolling surface. Unique experimental research has been conducted, in which regularity of weariness on rolling surface of exploitable locomotive wheel and phenomena of metal fatigue on wheel were researched. A hypothesis is made, that according to the differences in weariness intensity of wheel rolling surface it is possible to determine the start of metal fatigue. The inequality of wear intensity of different locomotive wheels is assessed by the Sharpe ratio, adapting it to describe the wheel wear intensity criteria. Based on the results of research, the authors propose a simplified and reliable methodology for determining metal fatigue on locomotive wheels at initial stages. The uneven wear on rolling surface of different wheels of wheelset inevitably changes the values of Sharpe ratio, which can accurately describe the conditions in which the critical metal fatigue on wheels begins to emerge.

Analysis of Freight Wagon Wheel Failure Detection in Lithuanian Railways

The authors of this paper analyze the freight wagon wheel rolling surface damage detection process in Lithuanian Railways. The wagons were selected for this study in consideration of the Wheel Impact Load Detector (WILD) database. The results gained by experimental measurements of wheel rolling surface defects were compared with the data recorded by WILD. Distribution of failures of wheel types and dependence of the influence of the wheel-set location in a wagon on the occurrence of different defects of wheels was defined. The authors examined the reliability of WILD read-outs and wheel defect types influence on the dynamic coefficient value. Finally, basic conclusions and recommendations are given.

The distribution of residual stresses in railroad wheels after electrocontact strengthening of the rolling surface

A procedure for the quality control of residual stresses in the rims of rolled wheels and locomotive tires via the ultrasound method using electromagnetic–acoustic excitation–reception of elastic waves is described. The results of the determination of residual stresses in surface-strengthened rims and pressed-on tires prior to strengthening and after electrocontact strengthening of the rolling surface of wheels are given.

THE METHOD OF ASSESSING PROFILES OF THE ROLLING STOCK WHEELS

The criteria of grounding for the choice of railway wheel rolling surface profile are proposed.

Investigation of dynamic models of independently rotating wheels of wagons

Abstract The article deals with the modelling of independently rotating wheels (IRW) systems for wagons. The research work of the intensity of rolling stock wheels rims and flanges is observed. The main performance objectives of IRW are to reduce winding of wheel‐sets, to enable railway rolling stocks to achieve higher speeds, to decrease wear of rail and wheel rolling surface, to improve the performance on railway curves and to reduce lateral displacement on rails. IRW with profiled tread are examined and the mathematical model of these IRW is created. Finally, the peculiarities of the stability and wearing characteristics of such IRW systems are presented.

INVESTIGATION OF DYNAMIC MODELS OF INDEPENDENTLY ROTATING WHEELS OF WAGONS

The article deals with the modelling of independently rotating wheels (IRW) systems for wagons. The research work of the intensity of rolling stock wheels rims and flanges is observed. The main performance objectives of IRW are to reduce winding of wheel‐sets, to enable railway rolling stocks to achieve higher speeds, to decrease wear of rail and wheel rolling surface, to improve the performance on railway curves and to reduce lateral displacement on rails. IRW with profiled tread are examined and the mathematical model of these IRW is created. Finally, the peculiarities of the stability and wearing characteristics of such IRW systems are presented.