Warm skew rolling of bearing steel balls using multiple impression tools

This paper presents considerations regarding skew rolling of bearing balls. The skew rolling process for producing 44.4 mm diameter balls made of 100Cr6 bearing steel is analyzed both theoretically and experimentally. Numerical simulations were performed by the finite element method using the Forge NxT simulation software. Experiments were conducted under laboratory conditions with the use of a skew rolling mill. The numerical model was validated by comparing FEM and experimental force characteristics. Thermal parameters of the rolling process and the state of strain in produced balls were analyzed. The quality of produced balls was evaluated too. The experimentally obtained balls were subjected to metallographic examination. The metallographic examination and hardness measurements of the warm-rolled balls generally showed no significant changes in the spheroidized structure of the bearing steel. The only changes with respect to microstructure and hardness were observed in the area of connectors between the balls.(c) 2022 CIRP.