Forming of rail car axles in a CNC skew rolling mill

Abstract

AbstractThis study relates to an innovative method for forming rail car axles by skew rolling in a CNC 3-roll mill. The rolling mill was constructed at the Lublin University of Technology. The use of this machine makes it possible to produce elongated axisymmetric parts that are up to 55 mm in diameter and up to 1000 mm in length. Experimental rolling tests are performed (in 1:5 scale) using this machine. Two types of axles are analysed: one manufactured in accordance with North American standards (AAR Class E) and one manufactured in compliance with European standards (BA302). Diameters of produced axles have a dimensional accuracy of ± 0.4 mm. Produced axles are free from internal cracks, and their surface defects (shallow helical grooves) can easily be removed by machining. The major shortcoming of the proposed method is the presence of chucking allowance. To eliminate this allowance, it is proposed that the forming process should be performed in two operations: rolling extrusion and skew rolling. Results of a numerical analysis were performed using the Simufact.Forming program confirms that rail car axles can be formed by the proposed method.