NSK has developed new long-life, spherical roller bearings for use in vibrating machinery at mining facilities (Fig.). Vibration-intensive equipment is often used at mining facilities: vibrating conveyors, screens and other processing and separating equipment, which, for example, are used to separate ores and minerals. The bearings in this equipment usually have a shorter lifetime than the bearings in other machines. This is therefore undesirable because the equipment is often integrated in a chain of processing operations and if one machine fails, the entire production or at least one production line can grind to a standstill.
1 Innovative product features
NSK has therefore developed spherical roller bearings especially for this application; these have a much longer lifetime in the specific unfavourable application conditions with dirt, high mechanical loads and continuous vibrations. To achieve this goal, several innovative product features have been combined. These include a special surface on the raceway of the outer ring, which is used to control the slippage action of the rollers. The curvature factor between the raceway and spherical roller has also been optimized. This reduces both slippage and the accompanying initiation stress between the roller and the contact surfaces of the outer and inner ring raceways. The result is a reduction in damage due to surface fatigue. These new advances in bearing technology give the new, long-life bearings a service life more than twice that of the current bearing types. NSK has succeeded in optimizing load distribution by reducing the internal radial clearance to 2/3 of that of ISO standard bearings and restricting bearing tolerances. The bearing outer dimension tolerance in relation to bore dimension tolerance is set at 1/2 that of ISO standard bearings.
The new spherical roller bearings come in 22 sizes with outer diameters ranging from 90-400 mm. They reduce the maintenance requirement of processing plants and reduce the time the operator must allow for unplanned downtime. So the new bearings usually pay for themselves in a short time, even when retrofitted to installed equipment.
NSK Deutschland GmbH, Ratingen (D),
Tel.: +49 2102 481-0, www.nskeurope.de