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This paper presents results of a study aimed at developing a technique for processing scrap
railway rails into useful products. Specifically, a die forging process for producing a
scaffolding joint coupler (see Fig. 1) from a rail web is investigated. The scaffolding joint
coupler under analysis is a fixed cruciform joint used for mounting scaffolding tubes at an
angle of 90°. The joint consists of 3 parts: a central part for ensuring a perpendicular position
of the tubes and two clamps which are bolted with the central part and fasten the connected
tubes together. An analysis of the geometry and shape of the central part of the scaffolding
joint coupler demonstrates that this element can be formed from a rail web. The proposed
manufacturing method is based on open die forging.
The designed manufacturing process is verified via numerical modelling in Deform 3D.
The billet material is assigned the properties of the R200 grade steel. The dies are modelled as
rigid bodies. The temperature of the billet is set equal to 1150°C and the temperature of the
tools is set equal to 150°C. The workpiece is discretized using 4-node tetragonal elements.
Contact relations between the tools and the workpiece are described by a constant friction
model with the friction factor m set equal to 0.3. The coefficient of heat exchange between the
tools and the workpiece is set equal to 5 kW/m2K while that between the workpiece and the
environment is set equal to 0.2 kW/m2K.
Metal flow kinematics, effective strains and temperatures are analysed in the simulations.
Table 1 shows the changes in shape of the workpiece during the forging process. Although the
die cavity is filled with the material as required, it can be observed that a relatively significant
amount of flash is created, which leads to increased wear. Due to the fact that the geometry of
the workpiece depends on the rail web dimensions, it is difficult to reduce the amount of flash.
Length is the only dimension of the workpiece that can be modified. However, a reduction in
length of the rail web would cause underfill, which would – in turn – make the forged part by
unsuitable in terms of quality. An analysis of the temperature distributions shows that the
temperature drops occurring toward the end of the forging process are insignificant and do not
exceed the lower limit for hot working. The highest strains are located around the forged part,
in the flash gap. The strains in the forged part are much lower.
The results demonstrate that scarp railway rails can be processed into full-value products
for the construction industry. It is also worth mentioning that scrap rails can be used for
producing a wide variety of parts such as balls, which has been investigated in many studies
[2, 3].
