Introduction
Spherical roller bearings are a critical component in equipment used in heavy industry. Their reliability, service life and ability to withstand high loads determine the efficiency of production processes. This article provides the technical basis, selection, installation and use of spherical roller bearings, to ensure high production reliability.
Fundamental Principles
Spherical roller bearings are developed for use in conditions of significant radial, axial and combined loads. Their design includes rollers with curved surfaces, which are located between the inner and outer rings and the housing. This design allows for compensation of shaft misalignment, reducing the influence of vibrations and deviations.
The main physical principles include three-dimensional loading, load distribution on rollers, influence of thermal expansion and change of friction coefficient at different temperatures. In addition, the influence of different types of loads (radial, axial, combined) should be considered during design.
Technical parameters and standards
Spherical roller bearings must comply with standards such as ISO 281, ISO 76, ISO 492, DIN 51825, IEC 60947-2, as well as national Ukrainian standards, namely DSTU 2245:2006, DSTU 2246:2006 and DSTU 2247:2006. They must be certified according to CE and UkrSEPRO.
Main parameters include:
- Maximum load: up to 1000 kN;
- Maximum rotational speed: up to 3000 rpm;
- Operating temperature: from -40 °C to +120 °C;
- Mean Time Between Failures (MTBF): up to 50 000 h;
- Friction coefficient: up to 0,01;
- Allowable deviation of the axis: up to 0,05 mm;
- Material: high-quality steel (40Cr, 42CrMo).
Selection and Calculation
Selection of a spherical roller bearing depends on the following criteria:
- Load type (radial, axial, combined);
- Maximum loads;
- Rotational speed;
- Temperature regime;
- Material of the node;
- Distance between supports;
- Service life.
Formula for calculation of load:
F = (P_r * K_r) + (P_a * K_a) de:
- F — general load;
- P_r — radial load;
- K_r — radial load factor;
- P_a — axial load;
- K_a — axial load factor.
The calculation is performed using a selection table:
| Load type | Coefficient (K) | Maximum Load (kN) |
|---|---|---|
| Radial | 1.0 | 1000 |
| Axial | 0.5 | 500 |
| Combined | 0.75 | 750 |
Best Practices for Installation and Commissioning
Installation of spherical roller bearings shall be carried out in accordance with the following recommendations:
- Use of special tools for installation, such as pressing tools, measuring devices and templates;
- Absence of worn surfaces on shafts and housings;
- Use of the appropriate type of lubricant (lubricated grease, hydraulic oil line);
- Temperature control of the bearing after installation;
- Use of the appropriate shaft connection and ring bearing;
- Measurement of axis deviation;
- Adjustment performed using test loads.
Root Cause Analysis and Failure Causes
The most common causes of failure of spherical roller bearings include:
- Incorrect installation;
- Insufficient lubrication level;
- Overload;
- High temperature;
- Surface wear;
- Incorrect shaft connection.
Visual signs of failure:
- Increased temperature;
- Increase in shaft runout;
- Noise during operation;
- Roller wear;
- Lack of lubricant.
Failure Prediction and Condition Monitoring
For the prediction of failures in spherical roller bearings, the following methods are used:
- Temperature control using temperature sensors;
- Vibration analysis using vibration sensors;
- Lubricant level monitoring;
- Diagnosis using measuring devices for wear analysis;
- Control of service life using operating time.
These methods allow detecting deviations at an early stage and performing maintenance before critical failures occur.
Comparison table
The following is a comparative table of three types of spherical roller bearings:
| Model | Maximum Load (kN) | Maximum speed (rpm) | Temperature (°C) | Coefficient of friction | Price (USD) |
|---|---|---|---|---|---|
| UNITEC-D 7218 | 1000 | 3000 | -40 to +120 | 0.01 | 120 |
| UNITEC-D 7220 | 1200 | 3500 | -30 to +100 | 0.012 | 150 |
| UNITEC-D 7222 | 1500 | 4000 | -20 to +80 | 0.015 | 200 |
Conclusion and Proposal
Spherical roller bearings from UNITEC-D GmbH comply with the requirements of ISO, DIN, DSTU standards and are certified CE and UkrSEPRO. They provide reliability, stability and efficiency in harsh production conditions.
For complete information about our range of spherical roller bearings and other components, visit our e-catalog: https://www.unitecd.com/e-catalog/
List of references
- ISO 281:2017 — Standards for bearings;
- ISO 76:2016 — Methodology for Determining Friction;
- DSTU 2245:2006 — Technical specifications for bearings;
- DSTU 2246:2006 — Technical specifications for conformity;
- DSTU 2247:2006 — Technical specifications for production.
