Bezrukavyi N. Increasing the freight cars wheelsets’ life by improving wheel profiles

The dissertation is devoted to the problem of freight cars wheelsets resource increase by the improvement of interaction with a track which is reached by perfection of wheel rim profiles. Development of wear-resistant wheel profiles for freight cars of perspective design including ones with the increased axial loading is done. The first section analyzes the main problems of interaction between rolling stock and railway track typical for domestic railway network. A review of works devoted to improving the shape of wheel rim profiles has been performed. The advanced world experience in optimizing the shape of wheel profiles is analyzed. It is shown that further improvement of the shape of the freight cars wheel profile can solve a number of problems associated with improving the interaction of freight cars and track. In the second section the research on influence of freight car bogies technical conditions on their dynamic characteristics and processes of interaction with a track is executed. The main parameters characterizing the technical conditions of the car bogie are analyzed. A spatial mathematical model of the interaction of the car and the arbitrary shaped track is developed, which allows to take into account the change of car technical condition parameters in operation for standard and prospective cars, as well as the possibility of single-point, two-point and conformal contact phases. The motion of cars with standard 18-100 type bogies, as well as with the same bogies equipped with complex modernization elements. Standard dynamic parameters of the car, indicators of wear intensity and interaction between the wheel and the rail were studied. The dependencies of the studied indicators on the motion speed are received in accordance with the simulation results. The analysis of the obtained results is performed and it is established that the wheelset wear has the greatest influence on the dynamic characteristics of the "car-track" system. It is shown that the use of 18-100 type bogies complex modernization allows not only to reduce its elements and components wear, but also to reduce the negative impact of these wear on the car dynamic qualities. The third section analyzes the influence of the shape of the freight car wheel profiles on their interaction with the track. The analysis of contact wheel/rail interaction for different profiles of rim rolling surfaces at their different mutual displacements is performed. Possible types of contact are analyzed and ways of wheel profiles optimization are chosen. The results of experimental researches of wheel wear-resistant profiles application efficiency are presented. The conducted operational researches of freight cars with different bogie designs and initial wheel profiles testify that the use of the wear-resistant ITM-73 profile allowed to reduce wheel wear intensity up to more than 2 – 2.5 times in comparison with a standard profile, and ITM-73-01 profile use gives the wear reduction up to more than four times. The analysis of the possibility of increasing the service life of wheelsets by reducing technological wear when using a new repair ITM-73-01 wheel profile is done. The analysis of technological wear influence on a wheelset resource is carried out, the basic factors influencing its value are established. The dependences of the wheelset technological wear on the geometric parameters of the worn wheel profiles at their turning with different profiles are constructed. Application of the ITM-73-01 profile at wheels turning both on ridges wear and surface defects allows to remove a smaller layer of metal that essentially increases a resource of a wheel. The fourth section is related to solving the problem of updating the domestic railways freight fleet in order to improve vehicles dynamic qualities, increase running gear life, reduce rolling stock and track wear. This section presents the results of research to improve the existing wear-resistant profiles shape and assess their use impact in different design bogies for freight cars of the new generation on their dynamic qualities and interaction with the track. New ITM-73-02 wheel profile with conformal contact for the rails P65 type has been developed. The impact of the new wear-resistant profile use in the 18-7020 type bogies on the vehicle dynamic characteristics and its interaction with the track is evaluated. According to the results of the study, it is shown that the use of the ITM-73-02 wheel profile according to forecast simulations meet the requirements on wheel wear intensity for prospective freight cars. For new bogies of 18-9817 model (with increased axle load up to 25 tons) the wheel profile ITM-73-03 is proposed, the use of which will significantly improve the process of interaction between the vehicle and the track and significantly reduce ridge wear.