Conception of a Three Roll Cross Rolling Process of Hollow Rail Axles

Abstract

Rail axles are large-size elements produced in batches consisting of thousands of elements.1,2) Currently the main technologies applied in production of such elements are open die forging and forging on swaging machines. In order to decrease the mass of rail axles whole parts are replaced with hollow ones. Due to the class of work performed by those elements (bending) their strength properties are not significantly influenced. Currently hollow rail axles are manufactured in the joint process of piercing sleeves in a skew rolling mill and forging in swaging machines.3) Many research facilities seek new, highly efficient methods of manufacturing hollow rail axles. Rolling appears to be particularly auspicious.4) Cross-wedge rolling (CWR) technology research appears to be the most advanced. Firstly the limitations to the process of CWR of hollow elements were determined, mainly: excessive ovalisation of the cross-section, uncontrollable slip, rupture or crushing of the rolled step.5,6) Then the parameters at which the rolling process is mostly uninterrupted were determined using numerical simulations and experimental testing.7–9) It allowed one to develop new, effective methods of manufacturing sleeves10) and valves11) using CWR. However, due to the significant length of the rail axles (over 2 m) the wedge tools need to be large as well. It was estimated that applying the classic rolling variant would Conception of a Three Roll Cross Rolling Process of Hollow Rail Axles