Prediction of the press-fit curve in the assembly of a railway axle and wheel

Abstract

A methodology for the prediction of the press-fit curve in the assembly of a railway axle and wheel is described. It starts from friction measurements on samples taken directly from the two components. A new apparatus, adaptable to a common axial testing machine, was developed for this aim: it permits the contact pressure and sliding speed to be varied in order to change the lubrication condition of the contact surfaces. Two calculation models are then proposed to predict the press-fit curves. They take the results of the friction measurements as input data, together with the wheelset geometry, the design interference and the material characteristics. The first one is a finite element method (FEM) model, which is very accurate but difficult to use, which also allows the effect of the wheel seat chamfer and the oil injection grove to be assessed. The second one is a simplified analytical model based on the theory of axisymmetric bodies, which works on an approximate wheel geometry; nevertheless, it gives results in good agreement with those of the FEM model and with the experimental press-fit curves of the examined wheelsets. Moreover, the simplified model is very fast and easy to use, thus constituting a powerful and useful tool for the design of new wheelsets.