Research on cross wedge rolling forming technology of railway axles

Abstract

This paper introduces a new forming method of railway axles: the square bloom is forged into a round axle billet by fast forging machine, then the round billet is rolled into the rough axle by the cross-wedge rolling machine. In order to prove the feasibility of this method, we have done an experimental trial of the technology on making scale-down Chinese railway freight axles with the scale ratio 1:1.4. The test result shows that the new method can double the productivity compared with the single forging method, save about 9% materials and improve shape accuracy of rough axle. Microstructure and mechanical properties of the axles formed by the new method have been tested and the test results show that the yield strength is greater than 345Mpa, the tensile strength is greater than 610Mpa, and the grain size reaches grade 8, which meets the standard requirements; The transverse and longitudinal impact toughness is greater than 21J, and the cross-sectional hardness distribution is uniform; The fatigue toughness test shows that the KQ value of the journal and shaft body in the deformation area of cross wedge rolling is slightly larger than that of the wheel seat, which indicates that the CWR process has no negative effect on fracture toughness of axles.