Spherical roller bearings feature double-row rollers and a spherical outer ring raceway. Their notable features include self-aligning, ability to withstand heavy radial loads and limited axial loads, and tolerance for a certain angular deviation of the inner ring relative to the outer ring (generally no more than 3°-5°). They are widely used in large rotating machinery such as mining machinery, papermaking machinery, and metallurgical equipment. These bearings consist of an inner ring, an outer ring, double-row symmetrical spherical rollers, and a cage. The drum-shaped rollers mate with the spherical outer ring raceway, ensuring the bearing maintains optimal operation despite shaft misalignment or shaft deflection. A mining machinery plant demonstrated that using spherical roller bearings in the main shaft support of a jaw crusher reduced the equipment’s failure rate by 40% and extended its service life by 1.5 times.
The materials used in spherical roller bearings must meet high strength and wear resistance requirements. The inner and outer rings are typically made of high-carbon chromium bearing steel (GCr15SiMn). After forging and heat treatment, the hardness reaches 58-62 HRC, ensuring sufficient load capacity and fatigue life. The rollers are made of the same material, cold-formed and then precision-ground to a surface roughness of Ra0.1μm. The roller profile must precisely match the spherical raceway of the outer ring to ensure even load distribution. The cage is typically made of brass (such as H62) or stamped steel. Brass cages offer excellent toughness and wear resistance, making them suitable for high-speed operation. Steel cages are more cost-effective and are suitable for low-speed, heavy-load conditions. A metallurgical equipment manufacturer has increased the dynamic load rating of its spherical roller bearings by 15% through the use of high-quality bearing steel and optimized heat treatment processes, meeting the heavy-load requirements of rolling mills.
The machining process for spherical roller bearings is complex and requires high precision. The inner ring machining process includes: forging → annealing → rough turning → heat treatment → finish turning → grinding → superfinishing. The inner ring raceway is a double-row tapered surface, which requires form grinding on a dedicated grinder to ensure symmetry and angular accuracy of the two rows of raceways. The outer ring raceway is spherical, and a spherical grinding wheel is used during grinding to control the curvature radius error within 0.01mm. The roller machining is a critical step, requiring cold heading, polishing, heat treatment, rough grinding, and finish grinding. The roller diameter tolerance is controlled to G2, with a cylindricity not exceeding 0.001mm. The drum is set according to the bearing size, generally 0.01-0.05mm. The precision machining workshop of a certain bearing group uses a five-axis linkage grinder to process the outer ring spherical raceway of spherical roller bearings, controlling the spherical surface error within 0.005mm and ensuring a perfect fit between the roller and the raceway.
The accuracy grade of spherical roller bearings is closely related to their application. According to the GB/T 307.1 standard, spherical roller bearings are classified into grades 0, 6, 5, 4, and 2, with grade 0 being the standard grade and grade 2 being the highest accuracy grade. Common industrial equipment, such as conveyor belts, typically uses grade 0 bearings to meet basic operating requirements. High-precision rotating equipment, such as the roller supports in papermaking machines, requires grade 6 or 5 bearings to control vibration and noise. Radial bearing clearance is a critical parameter and is classified into six grades: C1, C2, C0, C3, C4, and C5. C0 is the base clearance. Heavy-load applications require larger clearances (C3 and C4) to compensate for thermal expansion and installation errors. High-speed applications require smaller clearances (C1 and C2) to reduce vibration and heat generation. A papermaking machinery plant uses grade 5 precision spherical roller bearings with C3 clearance in the pressure roller shaft system, which reduces the operating noise of the equipment to below 85 decibels and significantly improves the flatness of the paper.
The installation and maintenance of spherical roller bearings are crucial to their optimal performance. Proper installation techniques are crucial. For tight-fitting inner rings, hot oil heating (80-100°C) can be used for shrink-fit installation to avoid damage to the bearing caused by hard knocks. The outer ring and bearing seat typically have a transition fit or clearance fit. During installation, ensure that the outer ring can move freely within the bearing seat to ensure proper alignment. Bearing temperature, vibration, and lubrication conditions should be regularly checked during operation. During normal operation, the temperature should not exceed 70°C, and the vibration velocity should be controlled below 11.2 mm/s. Grease or oil lubrication is recommended. Grease lubrication is suitable for low-speed applications and uses lithium-based grease. Oil lubrication is suitable for high-speed or high-temperature applications and uses total-loss system oil or specialized bearing oil. By establishing a comprehensive maintenance procedure for spherical roller bearings, regularly changing grease, and monitoring operating parameters, a cement production line has extended the average bearing life by 30% and increased the overall efficiency of the equipment to over 90%. As large-scale machinery develops towards high loads and high speeds, the design and manufacturing technology of spherical roller bearings continues to advance. The application of new materials and structures will further enhance their performance and provide more reliable support for the stable operation of industrial equipment.
