With the electrification of generator sets, electric locomotives, new energy vehicles, and other industries, AC motors subject bearings to an electric field environment, leading to galvanic corrosion due to the use of variable frequency power supply drives. The phenomenon of bearing discharge breakdown in subway traction motors is a critical issue in understanding the relationship between shaft current strength and the extent of bearing damage. This paper analyzes the mechanism of impulse discharge that leads to galvanic corrosion damage in bearings at a microscopic level and conducts electric thermal coupling simulations of the traction motor bearing discharge breakdown process. It examines the temperature rise associated with lubricant film discharge breakdown during the dynamic operation of the bearing and investigates how breakdown channel parameters and operational conditions affect the temperature rise in the micro-region of bearing lubrication. Ultimately, the results of the electric thermal coupling simulation are validated through experimental tests. This study revealed that in an electric field environment, the load-bearing area of the outer ring experiences significantly more severe corrosion damage than the inner ring, whereas non-bearing areas remain unaffected by electrolytic corrosion. When the inner ring reaches a speed of 4500_rpm, the maximum widths of electrolytic corrosion pits for the outer and inner rings are measured at 89 um and 51 um, respectively. Additionally, the highest recorded temperatures for the breakdown channels in the outer and inner rings are 932 °C and 802 °C, respectively. Furthermore, as the inner ring speed increases, both the width of the electrolytic corrosion pits and the temperature of the breakdown channels rise. Specifically, at inner ring speeds of 2500_rpm, 3500_rpm, and 4500_rpm, the widths of the electrolytic pits in the outer ring raceway load zone were measured at 34 um, 56 um, and 89 um, respectively. The highest temperatures of the lubrication film breakdown channels were recorded as 612 °C, 788 °C, and 932 °C, respectively. This study provides a theoretical basis and data support for the protective and maintenance practices of traction motor bearings.

Excavators are critical equipment in mining, construction, and other fields. The four-point contact slewing bearings used in their slewing mechanisms operate under harsh conditions such as heavy loads and impacts. Furthermore, the bearing rings are prone to elliptical deformation after installation, making them susceptible to premature failure. To address this issue, this paper establishes a mechanical bearing model to investigate the load distribution among balls and the fatigue life of the bearing under elliptical deformation of the rings. It systematically analyzes the influence of key design parameters. The research finds that elliptical deformation of the rings leads to contact angle deviation and a reduction in load-bearing balls, resulting in severe degradation of bearing fatigue life; therefore, its occurrence must be strictly controlled. Designing with a groove curvature radius coefficient within the range of 0.51 to 0.52 achieves an optimal balance between fatigue life and the four-point contact geometry of the balls. There exists an “optimal clearance” that maximizes bearing fatigue life; when considering significant elliptical deformation, the clearance design should be appropriately increased. Increasing the design contact angle enhances load capacity and helps mitigate the effects of elliptical deformation. However, an excessively large contact angle can cause ellipse truncation in the raceway contact zone; thus, the contact angle should be designed based on practical conditions. Increasing the number of balls can improve the influence of ovality on load distribution and enhance the bearing’s fatigue life. This study provides a theoretical reference for the design of high-reliability slewing bearings for excavators.

In response to the increasing demands for cage strength and operational stability of ball bearings in new energy vehicle motors operating under high-speed and light-load conditions, this paper focuses on the 6207 deep groove ball bearing as the research subject. It systematically analyzes the influence of various structural parameters of the crown-type cage, including profile radius, side beam thickness, claw length, and claw radius, on its eccentricity. Furthermore, the paper explores the mechanism by which eccentricity affects the dynamic performance of the cage. By establishing a rigid–flexible coupled dynamics model and conducting simulation analyses, the results indicate that the claw ends of the crown-type cage pockets are the regions of maximum deformation, while the pocket bottom experiences the highest equivalent stress, identifying it as a critical location for fracture failure. The research demonstrates that the impact of eccentricity on performance is non-monotonic: a reduction in eccentricity can significantly diminish the collision force between the balls and the cage, decrease vibration amplitude, and lower equivalent stress; concurrently, the maximum cage deformation and vibration acceleration level increase correspondingly. Additionally, the centrifugal force acting on the cage itself significantly elevates the equivalent stress. Therefore, the optimal design of the crown-type cage necessitates a comprehensive trade-off among multiple objectives, including strength and stability. It is essential to avoid inappropriate eccentricity design that may arise from the pursuit of a single performance indicator (such as friction reduction or weight reduction), thereby providing a theoretical foundation for the refined design of high-performance bearing cages.