The edge effect is caused by poor use of confinement systems, different roll aspect ratios, operating conditions and other factors, which result in uneven pressure distribution between the two crushing rolls along the roll width direction, affecting the overall roll crushing process. To reduce the edge effect, this paper investigates the simulation of the edge effect and parameter optimisation in the roll-crushing process of ore materials based on the discrete element method (DEM). Firstly, the parameters of the iron ore crushing model are experimentally calibrated, and the working process of HPGR is simulated by DEM. Secondly, the effects of roll speed, roll gap, roll diameter and roll width on edge effect and crushing effect of HPGR are analysed by the one-factor experiment. Finally, the roll pressure optimisation model is established based on the Response Surface Methodology (RSM) to obtain the optimal roll pressure parameters. The results show that, with the roll speed and roll diameter increase, the edge effect also increases, the roll gap shows the opposite trend, and the roll width has less influence. The change in roll diameter has the greatest influence on the crushing effect, roll gap is second, and roll speed and roll width have less influence on the crushing effect. When the feed particles are iron ore with a particle size of 32 mm, the optimisation results show that the edge effect and crushing effect of HPGR are significantly improved when the roll speed is 1.25 rad/s, the roll gap is 38 mm, the roll diameter is 2000 mm and the roll width is 742 mm.

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.

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.

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.