Recently, near-net-shape rolling has emerged as a key manufacturing technology for producing high-precision, fatigue-resistant bearing rings with irregular cross-sections, particularly for the production of Wind Turbine Shaft Bearings (WTSBs). The deformation behavior of the material during this rolling process is governed by temperature and rolling speed. Therefore, based on a thermomechanical coupled analysis, a simulation model for the deformation process of GCr15SiMn profiled rings during variable-speed rolling was developed in this study. The model was experimentally validated, confirming a dimensional error of less than 3‰. And then, the distribution of strain and temperature were analyzed during the rolling of the profiled ring. As the initial temperature increased from 1040 °C to 1160 °C, the standard deviation of strain (SDP) decreased from 6.12 to 4.05. Correspondingly, the standard deviation of temperature (SDT) was raised from 4.32 to 4.74. When the drive roll speed was increased from 2.5 rad/s to 4.0 rad/s, the SDP was reduced from 4.24 to 3.42. In addition, the SDT decreased from 4.42 to 3.21. The research indicates that SDP is primarily affected by initial temperature, whereas SDT is significantly influenced by drive roller speed. On the one hand, this study provides a clearly defined optimization framework, parameter ranges for achieving optimal uniformity in GCr15SiMn material (temperature of 1100–1130 °C, speed of 3.0–3.5 rad/s), and their anticipated benefits (an SDP reduction of 32% and an SDT reduction of 15%). On the other hand, it also establishes quantifiable industrial control targets, defining key quality assurance values (SDP ≤ 5.0, SDT ≤ 4.5). The rolling stability and precision can be improved through the selection of optimized rolling temperatures and speeds. This finding provides a theoretical foundation and technical framework for improving the rolling process stability of profiled cross-section bearing rings. Furthermore, this study is of positive significance for reducing the manufacturing costs of high-performance WTSBs.

As wind turbines trend toward larger sizes, higher rotational speeds, and extended service lives, higher demands are emerging for the dimensional accuracy, mechanical properties, and service reliability of the main shaft bearings. The hot bulging process is a critical process in bearing ring manufacturing. The stress–strain and dimensional evolution during the hot bulging process are crucial for the fatigue life and dimensional accuracy of rings with non-circular cross-sections. Therefore, based on the residual stress field from rolling as an initial condition, this paper established a coupled finite element model for the entire rolling-to-bulging process of GCr15SiMn bearing steel rings and verified the accuracy of the model. A stepwise rotation hot bulging process was innovatively designed. The stresses, strains, and deformation rates of the rings were thoroughly evaluated at different steps of the bulging process. Additionally, the effect of the bulge amount on the stress–strain uniformity and dimensional accuracy of the fabricated rings was also evaluated. Results indicate that based on the stepwise rotation hot bulging process conducted at 870–930 °C, when the first-step bulging amount is 1.50 mm, the secondary and third-step amounts are both 0.50 mm, and the bulging speed is 1.00 mm/s, while the roundness error of ring #3 stabilizes within 0.28–0.35 mm. The standard deviation of the axial equivalent strain was decreased by 92%, and the stress peak was also decreased by 39%. Above all, the stepwise rotation hot bulging process is an effective approach to improve the distribution uniformity of the stress–strain and the dimensional consistency of the bearing rings. This paper provides theoretical foundations and process guidance for the precision forming of large wind turbine bearing rings with non-standard sections.