Development of an improved wheel profile for a freight car. Theoretical justification
With the increasing loads on the axle and speeds, the increase in wear resistance and resistance to contact fatigue of the wheels is of particular importance. In part, this result was achieved using a standard profile according to GOST 10791-2011 with the use of more efficient spring suspension. A further reduction in the wear rate of both the rolling surface and the flange can be achieved by developing a new wheel profile. The authors have developed a technique that allows, based on theoretical calculations and experimental observations, to make the choice of the shape of the wheel profile, consistent with the profiles of the rails. The results of measurements of the wheels of cars of the model 12-9853 installed on bogies 18-9855 were used as the initial data, which were under controlled operation. The profile development consisted of four main stages: the choice of baseline data, the choice of the curvature of the rolling surface, the choice of the curvature of the transition section to the throttle, and the choice of the flange thickness and radius of the throttle in the transition zone to the rolling surface. The technique was used to develop a new wheel profile that differs from the profile according to GOST 10791-2011 in that the rolling surface is made with three conjugate radii, respectively from the wheel to the flange: 500, 325 and 87.5 mm. The flange throttle radius of the developed profile is 17 mm, the angle of inclination of the flange to the horizontal is 68°, and the thickness of the flange is 32.5 mm. A part of the wheel surface from the wheel to the outer part of the rim fully complies with GOST 10791-2011. Calculations showed that the contact zone of the wheel with the VNITsTT profile relative to the rail is shifted from the center to the flange and the contact area is larger. It was found that for the VNITsTT wheel profile the ratio of the semi-axes of the ellipse of contact spots is lower than for the profile according to GOST 10791-2011.