Spherical roller bearing – Construction , Application
Introduction to Spherical roller bearing –
A spherical roller bearing is a rolling-element bearing that permits rotation with low friction, and permits angular misalignment. Typically these bearings support a rotating shaft in the bore of the inner ring that may be misaligned in respect to the outer ring. The misalignment is possible due to the spherical internal shape of the outer ring and spherical rollers.Despite what their name may imply, spherical roller bearings are not truly spherical in shape. The rolling elements of spherical roller bearings are mainly cylindrical in shape, but have a profile that makes them appear like cylinders that have been slightly over-inflated.
Spherical roller bearings consist of an inner ring with two raceways inclined at an angle to the bearing axis, an outer ring with a common spherical raceway, spherical rollers, cages and, in certain designs, also internal guide rings or center rings. The bearings can also be sealed.
Designs of spherical roller bearing :
Single-row spherical roller bearing (barrel bearing)
Most spherical roller bearings are designed with two rows of rollers, allowing them to take very heavy radial loads and heavy axial loads. There are also designs with one row of rollers, suitable for lower radial loads and virtually no axial load. These are also called “barrel roller bearings” or “Tonnenlager” and are typically available in the 202- and 203-series.
The internal design of the bearing is not standardised by ISO, so it varies between different manufacturers and different series. Some features that may or may not exist in different bearings are:
- lubrication features in inner or outer ring
- central flange
- guide ring or center ring
- integrated seals
Bearing rings and rolling elements can be made of a number of different materials, but the most common is “chrome steel”, (High carbon chromium) a material with approximately 1.5% chrome content. Such “chrome steel” has been standardized by a number of authorities, and there are therefore a number of similar materials, such as: AISI 52100 (USA), 100CR6 (Germany), SUJ2 (Japan) and GCR15 (China).
Some common materials for bearing cages:
- sheet steel (stamped or laser-cut)
- polyamide (injection molded)
- brass (stamped or machined)
- steel (machined).
Dimensions of Spherical Roller Bearing :
External dimensions of spherical roller bearings are standardised by ISO in the standard ISO 15:1998. Some of the common series of spherical roller bearings are: 213, 222, 223, 230, 231, 232, 238, 239, 240, 241, 248, 249.
Spherical bearings are used in countless industrial applications, where there are heavy loads, moderate speeds and possibly misalignment. Some common application areas are:
- wind turbines
- continuous casting machines
- material handling
- mechanical fans and blowers
- mining and construction equipment
- pulp and paper processing equipment
- marine propulsion and offshore drilling
- off-road vehicles.
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