Abstract
This paper presents the results of theoretical and experimental investigations of a new process of rolling rods from scrap rail heads. First, the industrial applications of scrap railway rails and methods of their recycling are discussed, and then the concept of two-stage rolling of rods from heads cut off from scrap rails is proposed. In the first stage of the process, a rail head preform was rolled in a hexagonal pass of a longitudinal rolling mill. Then in the second stage, the hexagonal bar was skew rolled into a rod in a helical roll pass. Theoretical considerations were based on finite element numerical modelling. The rolling process was simulated under 3D deformation using Forge NxT v.1.1 software developed by Transvalor Company. Calculations were carried out to determine the material flow kinematics, strength, and thermal parameters of the process and to identify the phenomena that might constrain its implementation. The numerical results were verified in experimental tests, during which preforms and rods were formed from scrap rail heads. The tests were conducted in longitudinal and skew rolling mills. The results indicate that rods can be effectively formed from scrap rail heads in just two steps. Rods obtained using the proposed method can be used as full-featured, semifinished products for the manufacture of various types of machine parts.
Highlights
The large supply of used railway rails has spurred the search for effective methods of managing and processing railway scrap
In the case of traditional recycling of scrap railway rails, 80–90% of the total cost of processing 1 Mg of rails goes to the steelmaking process, in which scrap metal is processed back into steel, and 10–20% of the cost is associated with forming the recovered steel into a finished product [5,6]
Considering the limitations of longitudinal rolling of rods from scrap rail heads, we propose a new technology for rolling rods (Figure 1), which is implemented in only two stages [22,23]
Summary
The large supply of used railway rails has spurred the search for effective methods of managing and processing railway scrap. Depending on the required bar diameter and quality, longitudinal rolling processes are performed with the use of up to several roll passes. Ukrainian railways have been planning to establish special plants for rolling scrap rail heads into rods with diameters from φ 32 to φ 6.5 mm [21] The technology they want to use is based on longitudinal rolling, in which a system for calibrating groove passes allows to produce φ 32 mm rods in seven passes and φ 6.5 mm rods in 20 passes. Heads cut off from worn rails are compressed in a hexagonal pass of a longitudinal rolling mill (Figure 1a) This is done to obtain a relatively regular cross-sectional shape of the preform.
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