Extra-heavy Angular Contact Ball Bearing

I. Product Overview​

Extra-Heavy-Duty Angular Contact Ball Bearings (abbreviated as EHDACBB) are a top-tier specialized category within the angular contact ball bearing family, designed exclusively for scenarios requiring extreme heavy-load transmission, super-strong impact resistance, and ultra-high rigidity support. Their core competitiveness lies in the triple core characteristics of "extreme heavy-load capacity + super-strong impact rigidity + long service life endurance" - through ultra-thick wall structure optimization (40%-60% thicker than heavy-duty models), ultra-large diameter rolling element design (30%-40% larger diameter than heavy-duty models), and multi-quantity arrangement (6-8 more than heavy-duty models), they achieve a basic dynamic load rating of 150kN-400kN and can withstand unidirectional axial loads equivalent to 120%-150% of the radial rated load (increasing with the contact angle). Adopting a combined design of "enhanced raceway curvature + ultra-high-strength materials + rigid alloy cages", their impact resistance is improved by over 80% compared to heavy-duty models, enabling stable resistance to instantaneous impacts of 3-3.5 times the rated load (e.g., material impact from large mining crushers, rolling impact from heavy metallurgical rolling mills). This completely solves the industry pain points of "load collapse, frequent failure, and extremely short service life" for extreme heavy-load equipment.​

The outer diameter of these bearings ranges from 150mm to 500mm, with an inner diameter spanning 80mm to 250mm and a basic static load rating of 100kN-300kN. The grease-lubricated limiting speed is 3,000-10,000 r/min (fully matching the "ultra-low-speed, ultra-high-pressure" operating characteristics of extreme heavy-load equipment, such as 4,000 r/min for large ball mills and 3,000 r/min for heavy forging equipment). Precision grades are mainly P6-P5 (P4 grade is optional for high-precision heavy-load scenarios such as heavy machine tool spindles). They are suitable for extreme heavy-load equipment including large mining crushers, heavy metallurgical rolling mills, heavy forging equipment, and extra-large port lifting equipment. The equipment downtime failure rate is reduced by 50% compared to heavy-duty models, and the service life under extreme heavy-load conditions is extended by over 100% compared to heavy-duty models, making them the "irreplaceable ultimate transmission component" in the extreme heavy-load field.​

Compared with heavy-duty angular contact ball bearings, exclusive optimizations for extreme heavy loads have been made in their structure, materials, and processes: inner and outer rings are made of 20Cr2Ni4A ultra-high-strength alloy carburized steel (surface hardness HRC 64-68, core hardness HRC 32-36), with deformation resistance and fatigue resistance improved by 60% compared to 20CrNiMo steel; cages are made of 42CrMo alloy steel (titanium alloy cages are optional for some extreme scenarios) to prevent cage fracture under extreme heavy loads; some models adopt a "triple-row rolling element symmetrical arrangement" or "strengthened raceway edge" design to further distribute extreme heavy-load pressure. With a coverage rate of over 80% in the extreme heavy-load field, they have become the core guarantee for supporting the stable operation of extreme heavy-load equipment.​

II. Core Structure and Design Features​

1. Precision Structural Composition​

The four core components of EHDACBB are deeply optimized to meet the requirements of "extreme heavy-load bearing, super-strong impact resistance, and stable force transmission", ensuring reliable operation under extreme heavy-load conditions:​

Inner and Outer Rings: Adopt an ultra-thick-walled rigid structure, with the wall thickness of inner and outer rings 40%-60% thicker than that of heavy-duty models (e.g., for a 7420 series bearing with an inner diameter of 100mm, the inner ring wall thickness increases from 6mm to 9.5mm, and the outer ring wall thickness from 7.5mm to 12mm). Finite element analysis is used to "locally thicken and strengthen" the raceway area (the wall thickness of the raceway area is 30% thicker than that of non-raceway areas), ensuring a deformation of ≤ 0.025mm under extreme heavy loads. The material used is 20Cr2Ni4A ultra-high-strength alloy carburized steel, which undergoes "integral forging + deep carburization (carburized layer depth 2-2.5mm) + vacuum quenching + ultra-precision grinding" processes. The surface hardness reaches HRC 64-68, the raceway surface roughness is Ra ≤ 0.06μm, and the roundness error is ≤ 2μm, ensuring uniform contact with rolling elements and avoiding cracks or fractures caused by local stress concentration.​

Rolling Elements (Steel Balls): Ultra-large diameter high-toughness steel balls are used, with a diameter 30%-40% larger than that of heavy-duty models (e.g., for a 7416 model bearing, the steel ball diameter increases from 19.05mm to 26mm). The quantity is 6-8 more than that of heavy-duty models (e.g., from 16 to 24 for the 7420 model). Extreme heavy-load pressure is distributed by increasing the contact area and adding load-bearing units. The material is GCr15SiMn ultra-high-toughness bearing steel (Si₃N₄ ceramic balls are optional for some extreme scenarios), processed through "vacuum melting + multi-stage precision forging + ultra-precision grinding". The impact toughness αk ≥ 30J/cm², the roundness error is ≤ 0.25μm, the surface roughness is Ra ≤ 0.04μm, and the wear resistance is improved by 50% compared to ordinary steel balls. For extreme corrosive scenarios (e.g., chemical extra-heavy-duty equipment), stainless steel balls (SUS440C) are optional, with acid and alkali corrosion resistance of over 95%.​

Cages: Ultra-high-strength rigid cages are used. Mainstream models adopt 42CrMo alloy steel cages - after "quenching and tempering (hardness HB 250-280) + surface nitriding" treatment, the tensile strength is ≥ 1000MPa, 40% higher than that of ordinary 40Cr steel, suitable for ultra-low-speed extreme heavy-load scenarios (rotational speed ≤ 8,000 r/min). For high-speed extreme heavy-load scenarios (rotational speed 8,000-10,000 r/min, such as heavy machine tool spindles), TC4 titanium alloy cages are used, which are 40% lighter than steel cages and have 30% improved fatigue resistance. The cage pockets adopt a "deep pocket + thickened wall design", with the pocket wall thickness 50% thicker than that of heavy-duty models. The clearance between pockets and steel balls is controlled at 0.2-0.3mm to prevent steel ball movement or cage deformation under extreme heavy loads, with an operating noise of ≤ 60dB.​

Sealing/Dust-Proof Structure (Optional): Equipped with extra-heavy-duty contact seals (suffix 2RS) or ultra-thick dust covers (suffix 2Z). The 2RS seals use nitrile rubber (NBR) thickened seal lips (thickness 1.5-2mm), combined with high-strength metal skeletons to enhance rigidity, achieving an IP65 dust and water resistance rating. They are suitable for extreme heavy-load scenarios with humidity and dust (e.g., large mining crushers, extra-large port equipment). The 2Z dust covers are made of 0.5-0.6mm thick cold-rolled steel plates, which are press-formed and interference-fitted with the outer ring (interference 0.03-0.05mm), providing good dust resistance and impact resistance. They are suitable for dry and dusty extreme heavy-load scenarios (e.g., heavy metallurgical rolling mills, gearboxes). All sealing structures feature enhanced rigidity design to prevent seal failure caused by extreme heavy-load vibration.​

2. Key Design Characteristics​

Extreme Heavy-Load Capacity: Through the coordinated design of ultra-thick-walled inner/outer rings and ultra-large diameter, multi-quantity rolling elements, the basic dynamic load rating covers 150kN-400kN (e.g., the basic dynamic load rating of the 7420 model bearing reaches 380kN, far exceeding the 180kN of the heavy-duty 7320 model). It can withstand unidirectional axial loads equivalent to 120%-150% of the radial rated load (120%-130% for 15° contact angle Type C, 130%-140% for 25° Type AC, and 140%-150% for 30° Type B). No additional extra-heavy-duty thrust bearings are required, simplifying the transmission structure of extreme heavy-load equipment and adapting to the composite load requirements of extreme heavy loads.​

Super-Strong Impact Resistance and High Rigidity: The combination of ultra-thick-walled structure and ultra-high-strength materials improves the radial rigidity of the bearing by over 90% compared to heavy-duty models, enabling stable resistance to instantaneous impacts of 3-3.5 times the rated load (e.g., 3.5 times the impact load when crushing hard rock with large mining crushers, 3 times the impact load when rolling thick steel plates with heavy metallurgical rolling mills). The raceway curvature coefficient is optimized to f=0.54-0.56 (f=0.53-0.55 for heavy-duty models), increasing the contact area between rolling elements and raceways, reducing contact stress (contact stress ≤ 2,800MPa under extreme heavy loads), avoiding raceway spalling or steel ball fragmentation, and significantly extending service life.​

Adaptation to Ultra-Low-Speed, Extreme Heavy-Load Conditions: Although the grease-lubricated limiting speed (3,000-10,000 r/min) is lower than that of light/medium/heavy-duty models, it fully matches the "ultra-low-speed, ultra-high-pressure" operating characteristics of extreme heavy-load equipment - for example, the working speed of heavy metallurgical rolling mills is 5,000 r/min, large mining ball mills 4,000 r/min, and heavy forging equipment 3,000 r/min, all within the optimal speed range of this bearing. At the same time, an "ultra-large clearance design (Grade C4/C5)" is adopted to adapt to temperature rise during the operation of extreme heavy-load equipment (e.g., 100℃ temperature rise in metallurgical equipment), preventing bearing seizure caused by thermal expansion.​

Paired Installation and Ultra-High Rigidity Support: Three paired installation methods are supported: "back-to-back (DB), face-to-face (DF), and tandem (DT)", with extremely high installation precision requirements -​

DB installation (outer ring wide sides facing each other): The resistance to overturning torque is 70% higher than that of heavy-duty models, suitable for scenarios with large radial loads and requiring stable support (e.g., heavy machine tool spindles, backup rolls of heavy metallurgical rolling mills);​

DF installation (outer ring narrow sides facing each other): High axial stiffness, suitable for scenarios with large axial load fluctuations (e.g., extra-large port lifting equipment, large compressors);​

DT installation (outer ring wide side facing narrow side): Capable of withstanding larger unidirectional axial loads, suitable for scenarios with extremely large axial thrust (e.g., output shafts of large gearboxes).​

During paired installation, special high-precision tooling is required to ensure coaxiality (error ≤ 0.005mm) and ensure stable force transmission under extreme heavy loads.​

III. Main Product Models and Classification​

1. Classification by Contact Angle​

2. Classification by Precision Grade​

Grade P6: Dimensional tolerance ±8μm, geometric tolerance ±5μm. Suitable for general-precision extreme heavy-load scenarios (e.g., large mining crushers, extra-large port lifting equipment), with moderate cost and high cost-effectiveness, accounting for over 70% of the extreme heavy-load market share.​

Grade P5: Dimensional tolerance ±5μm, geometric tolerance ±3μm. Suitable for medium-precision extreme heavy-load scenarios (e.g., heavy metallurgical rolling mills, large compressors), it is the mainstream choice for extreme heavy-load equipment, accounting for approximately 20% of the market share.​

Grade P4: Dimensional tolerance ±3μm, geometric tolerance ±2μm. Suitable for high-precision extreme heavy-load scenarios (e.g., heavy machine tool spindles, precision heavy-load gearboxes), featuring excellent performance but higher cost, accounting for approximately 10% of the market share.​

3. Classification by Structure and Sealing Method​

Open Extra-Heavy-Duty Angular Contact Ball Bearings (No Suffix): No sealing/dust-proof structure, with light weight and good rigidity. Suitable for dry, clean extreme heavy-load scenarios with independent lubrication systems (e.g., heavy machine tool spindles with oil mist lubrication).​

Extra-Heavy-Duty Angular Contact Ball Bearings with Dust Covers (Suffix 2Z): Equipped with ultra-thick double-sided steel dust covers (thickness 0.5-0.6mm), providing good dust resistance and impact resistance. Suitable for dry and dusty extreme heavy-load scenarios (e.g., heavy metallurgical rolling mills, gearboxes).​

Sealed Extra-Heavy-Duty Angular Contact Ball Bearings (Suffix 2RS): Equipped with ultra-thick double-sided nitrile rubber seals (seal lip thickness 1.5-2mm), achieving an IP65 dust and water resistance rating. Suitable for humid, dusty extreme heavy-load scenarios (e.g., large mining crushers, port equipment), with rotational resistance slightly higher than that of 2Z models (increased by 15%-20%).​

Triple-Row Extra-Heavy-Duty Angular Contact Ball Bearings (Suffix A/B): Adopt a symmetrical arrangement of triple-row rolling elements, with radial and axial load-carrying capacity improved by over 120% compared to single-row models. Suitable for extreme heavy-load scenarios (e.g., main shafts of large crushers, heavy forging equipment), with models such as 3318A (90×190×64mm).

IV. Applicable Industries and Typical Applications
The extra-heavy angular contact ball bearings leverage their core advantages of "extremely heavy load-bearing capacity and extremely strong shock resistance rigidity" and are widely applied in ultra-extremely heavy industrial fields. Typical scenarios include:
Metallurgical Industry: Supporting rollers of metallurgical heavy rolling machines (compatible with 7420C/P5 model, 15° contact angle to bear radial rolling loads, basic rated dynamic load 380kN, suitable for 5000r/min working speed of the rolling machine), Vibrating shaft of continuous casting machine (compatible with 7418AC/2Z model, 25° contact angle to balance radial and axial vibration loads, dust cover to resist steel slag dust), Conveyor rollers for steel billet heating furnaces (compatible with 7416B/P6 model, 30° contact angle to bear axial conveying thrust, suitable for 4000r/min speed).
Mining Machinery Industry: Main shaft of jaw crushers (compatible with 7422B/P5 model, 30° contact angle to bear axial crushing impact, capable of handling 3.5 times the rated load in an instant impact), Eccentric shaft of cone crushers (compatible with 7420AC/2RS model, 25° contact angle to balance radial and axial eccentric loads, IP65 seal to resist mineral dust and water vapor), Transmission shaft of large ball mills (compatible with 7424C/P6 model, 15° contact angle to bear radial grinding loads, oversized clearance design to adapt to temperature rise of 100℃).
Heavy Machine Tool Industry: Main shaft of heavy lathes (compatible with 7420AC/P4 model, 25° contact angle for paired DB installation, strong anti-overturning torque to ensure machining accuracy ±0.008mm at 8000r/min), Floor-mounted milling and boring machine main shaft (compatible with 7424B/P4 model, 30° contact angle to bear axial milling force, high rigidity structure to ensure ultra-extremely heavy cutting stability), Feed axis of heavy gantry milling machines (compatible with 7418C/P5 model, 15° contact angle to bear radial feed loads, suitable for 6000r/min speed).
Port and Lifting Industry: Rotating mechanism of ultra-large portal cranes at ports (compatible with 7426C/P6 model, 15° contact angle to bear radial return load, suitable for 6000r/min speed), Lifting mechanism of super-large container cranes (compatible with 7424AC/2RS model, 25° contact angle to balance radial and axial lifting loads, IP65 seal to resist seawater moisture), Drive shaft of heavy forklifts (compatible with 7416B/P6 model, 30° contact angle to bear axial drive thrust, shock resistance suitable for forklift full-load starting impact).
General Extra-Heavy Machinery Industry: Output shaft of large gearboxes (compatible with 7430C/P5 model, 15° contact angle to bear radial gear loads, basic rated dynamic load 400kN, suitable for 5000r/min speed), Super-large compressor rotors (compatible with 7428AC/P5 model, 25° contact angle to balance radial electromagnetic force and axial gas thrust), Crankshafts of heavy forging equipment (compatible with 7432B/P6 model, 30° contact angle to bear axial forging impact, high rigidity structure to avoid bearing failure due to crankshaft bending).

V. Summary of Product Advantages
Superior load-bearing capacity for extreme heavy-duty applications, suitable for top-level working conditions: 150kN - 400kN basic rated dynamic load, combined with an axial load ratio of 120% - 150%, can stably meet the extreme heavy-duty requirements of industries such as metallurgy and mining, avoiding the problem of insufficient load-bearing capacity of medium-sized and small models, and is the "ultimate transmission guarantee" for extreme heavy-duty equipment.
Super strong impact resistance and high rigidity, significantly extended service life: Ultra-thick wall structure + ultra-high strength material + optimized raceway design, the impact resistance is improved by 80% compared to heavy-duty models, capable of withstanding instantaneous impacts of 3 - 3.5 times the rated load; under extreme heavy-duty working conditions, the service life is extended by more than 100% compared to heavy-duty models, reducing equipment downtime failure rate by 50%, significantly reducing operation and maintenance costs.
Compatible with ultra-low speed extreme heavy-duty applications, with extremely high performance matching: 3000 - 10000 r/min grease lubrication limit speed, perfectly matching the "ultra-low speed, ultra-high pressure" operating characteristics of extreme heavy-duty equipment, without sacrificing load-bearing capacity for the pursuit of high rotational speed, the performance is highly compatible with the requirements of the working conditions.
Diverse structures, wide coverage of scenarios: Supports single row / three row structures, various contact angles and sealing methods, suitable for extreme heavy-duty scenarios in industries such as metallurgy, mining, heavy machine tools, and port lifting, with a coverage rate of over 80%, and has strong versatility.
Top-level optimization of material and process, ultimate reliability: 20Cr2Ni

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