Bearings - 2019-10-02
NSK has developed its latest four-row tapered roller bearings for rolling mills to offer a number of class-leading performance and environmental benefits. The work roll bearings use newly developed, water-resistant grease that is fully sealed into the confines of the bearing. With the new bearings, service life is typically doubled in challenging conditions such as those where there is a high risk of water penetration. In addition, the sealed design means that grease consumption is far less than that exhibited by a conventional ‘open’ bearing, while the risk of contaminating the environment is greatly reduced.
NSK’s new long-life, four-row, sealed tapered roller bearings with new AQGRD grease deliver on a primary demand of rolling mill applications: the requirement for work roll bearings that last. Rolling mills typically use pairs of work rolls to roll slabs of steel or other metals into specific shapes, such as sheets. This work is particularly demanding on the bearings, which have to bear heavy loads at high speeds and temperatures, and endure constant exposure to water sprays and metal particles.
These severe operating conditions can lead to premature bearing failure due to flaws such as flaking. Flaking occurs when fatigue causes small pieces of bearing material to separate from the smooth surface of the raceway. This effect creates coarse regions that eventually make the bearing inoperable.
The principal innovation designed to help combat such issues is the newly developed AQGRD water-resistant grease. Optimised grease composition creates a thicker oil film and protective layer between the raceway and rollers, inhibiting direct contact without lubrication, as well as preventing corrosion. Rust prevention is important as harmful defects such as flaking, which compromise bearing life, stem from areas of corrosion. Ultimately, longer service life reduces maintenance costs and increases operational efficiency. Moreover, since the bearings need less frequent replacement, they help to minimise carbon footprint and resource consumption.
Aside from the long service life benefits, reduced material and energy consumption will also result in relation to the replacement cycles of conventional bearings, which in turn helps to lower CO2 emissions.
Moving forward, NSK will continue developing and manufacturing products geared toward realising a sustainable society.
Picture 1) NSK’s new sealed four-row tapered roller bearing for work rolls in rolling mills
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