A New Cross Wedge Rolling Process for Producing Rail Axles

Abstract

Rail axles are large-size parts produced in large batches. Currently, these parts are produced by metal forming techniques such as rotary forging, open die forging with hydraulic presses and open die hammer forging (minimum ram weight: 3 Mg). Nevertheless, not only are the above methods far from being efficient, they also lack accuracy (open die forging). As a result, new techniques for producing rail axles are constantly developed. One of such alternative techniques is based on the use of cross wedge rolling (CWR), which is the subject of the present study. An innovative roll design for producing rail axles by CWR is proposed. The rolls are provided with three pairs of wedge tools that act simultaneously on the workpiece and form the part in one revolution of the rolls, i.e., during 20 s. The numerical modelling of a CWR process with the proposed roll design reveals that the solution can be used to produce railway axles with the desired geometry. This technique, however, requires relatively high loads and torques. To decrease the force parameters, the forming process was modified and ran in two operations. The first operation consists in forming the central step of the workpiece while the other one involves the formation of steps on the ends of the workpiece. The results of the new simulation show a significant decrease in the loads and torques, which is caused, among others, by reducing the nominal diameter of the rolls from 1600 mm to 1200 mm. The numerical findings can be used to design a rolling mill for producing rail axles.

A Comparative Analysis of Forming Railway Axles in 3- and 4-Roll Rolling Mills

“…Numerical simulations were performed using the commercial simulation program Simufact.Forming. This program had been effectively used before for analyzing both cross and skew-rolling processes [11,12,14,[24][25][26]. The numerical results obtained showed a high level of agreement with experimental findings.…”

“…It was also observed that the multi-wedge rolling process is more difficult to conduct due to difficulties related to removing cross sectional ovalization, especially when rolling hollow axles. In effect, a two-stage rolling process for railway axles was developed [11], in which the central step is formed first, and then end steps are rolled by the other pair of rolls. This solution allows reducing the diameter of the rolls to 1200 mm, which also causes a significant decrease in torque.…”

Numerical analysis of the cross-wedge rolling process of a railway axle

“…Dlatego poszukuje się alternatywnych rozwiązań. Jedno z nich, opracowane na Politechnice Lubelskiej [8], polega na walcowaniu osi w dwóch etapach. Najpierw kształtowany jest stopień centralny, a następnie (drugą parą walców) -stopnie skrajne.…”

Forming of rail car axles in a CNC skew rolling mill

“…Results of the rolling tests performed in 1:5 scale by Peng et al [7] and Zheng et al [8] demonstrated that the production of rail car axles by the multi-wedge cross-rolling method is difficult due to significant inaccuracies in product shape and the problem with removing the ovalisation of the cross section of the product (in the case of hollow axles). According to Pater and Tomczak [9], an alternative to multi-wedge cross-rolling is a CWR process that is performed in two operations. The first operation involves forming a step in the centre of the workpiece, while the other involves forming steps on the shaft ends using a different set of tools.…”