Stress–Strain Evolution and Process Parameter Effects in Radial–Axial Ring Rolling of Wind Turbine Bearing Inner Ring

The forming quality of large wind turbine main shaft bearing inner rings directly determines the service life and operational reliability of wind energy equipment. Yet the plastic deformation mechanism and stress–strain evolution of GCr15SiMn bearing inner rings during asymmetric cross-section radial–axial rolling remain poorly understood. Stress–strain curves from isothermal hot compression tests were used to build a three-dimensional finite element (FE) model of inner ring radial–axial rolling, validated by dedicated rolling experiments. The effects of drive roll rotational speed, initial rolling temperature, and radial–axial feed speeds on the stress and strain fields were systematically investigated. Results show that material flow velocity on the outer surface of the radial deformation zone is 100–200 mm/s higher than on the inner surface. The velocity difference between the upper and lower end faces in the axial deformation zone stays below 100 mm/s, confirming synchronous end-face forming. Peak equivalent stress reaches 81.5 MPa in the radial rolling stage and 75.6 MPa in the axial rolling stage. Standard deviation of stress (SDS) and plastic strain (SDP) quantify field uniformity; the most uniform distributions occur at 3.5 rad/s (SDS = 15.09) and 1100 °C (SDP = 4.18). These findings provide a theoretical basis for rolling process optimization and precision forming quality control of asymmetric cross-section wind turbine bearing inner rings.