Backing bearings for cluster mills
Backing bearings have been specially developed for cold rolling mills of the cluster type, but can also be used for other applications, e.g. straightening or bending machines. Backing bearings are roller bearings having a particularly thick-walled outer ring and can be mounted on stationary support shafts to form back-up or straightening rolls. The forces from the work rolls are transmitted via the support shaft and a system of support saddles to the roll or machine stands. Fig 1 shows the arrangement of the backing bearings on the eight support shafts of a 20-roll mill.
SKF backing bearings for cluster mills are produced in many designs but are generally based on double or three-row cylindrical roller bearings. Single row needle roller bearing and double row tapered roller bearing designs are also available. The logarithmic contact profile between rollers and raceways produces a vastly improved stress distribution under all load conditions as well as when the bearing is misaligned under load. An optimised finish on all surfaces in contact serves to enhance lubrication conditions. As lubricant is supplied to the bearings via the support shaft, SKF backing bearings have lubrication holes and some have one or more annular grooves in the inner ring.