In the paper the press fitting process of a railway wheel on its axle has been studied. The press fitting process of a railway wheel is still to day a topic for scientific research. The final aim is to design the mating contact surfaces of wheel and axle in order to minimise the damage of the wheel seat and of the wheel bore during the relatively frequent operations of press fitting and removal of the wheel from its seating. Although only an extensive and accurate experimental test campaign may give a reliable contribution to solve the addressed problem, in this paper a preliminary and important contribution has been given to understand the phenomenon of the press fitting (and removal) of a wheel on (from) its axle. The influence of the geometric and physical mechanical parameters (friction, lubricant viscosity/contact surfaces roughness) on the stress conditions during the press fitting phase has been investigated on the basis of a FEM analysis. An experimental validation of the FEM model (related to the removal of a wheel from its seating) has been performed. The relationship between the press fit design variables and the performance indexes have been approximated by using response surfaces. The optimisation of the design of a wheel and axle in the contact zone (wheel bore and wheel seat on the axle) has been performed. The optimisation has been carried out by taking into account robustness, i.e. the sensitivity of the performances indexes to the value of the interference between wheel bore and axle. By defining in a correct manner the values of the design variables it is possible to obtain a reduced sensitivity to the machining tolerances (interference), and at the same time a reduction of the axial thrust and reduced stresses both in the axle and in the wheel. Plastic deformation on the axle can be eliminated (or dramatically reduced) by employing the steel 30 NiCrMoV12.
A railway wheelset optimally designed for cold press fitting
Optimierung eines Eisenbahn-Radsatzes für Kaltpresspassung
2004
6 Seiten, 8 Bilder, 3 Tabellen, 21 Quellen
Conference paper
English