Numerical and experimental investigations on the effect of mandrel feeding speed for high-speed rail bearing inner ring

In this paper, the effect of mandrel feeding speed was investigated numerically and experimentally for the inner ring of high-speed rail bearing made of GCr15. Firstly, the cold ring rolling process is simulated systematically using nonlinear finite element software package of ABAQUS. Nonlinear constitutive equation was employed to study rolling torque for material GCr15. Secondly, the effect of mandrel feeding speed modes on rolling torque was presented to find an optimized feeding speed mode. To verify the numerical results, cold ring rolling experiment was carried out. The agreement of the roundness of the inner ring and rolling torque between predicted and experimental is good. In addition, the metallographic experiment of the bearing ring before and after cold ring rolling was conducted to obtain microstructure of the part. The scanning electron microscope (SEM) technique was used to capture the sample before and after the process. It was observed that there were a small amount of spherical cementites and lamellar pearlites, and black carbide particles distributed uniformly in the inner ring, where the grains were significantly refined after cold ring rolling. Good agreement between experimental observation and numerical predictions indicated that the procedures were useful in capture the effect of the mandrel feeding speed for the high-speed rail bearing inner ring of cold ring rolling.