Product Description
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.
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, NEWORLD backing bearings have lubrication holes and some have one or more annular grooves in the inner ring.
Designs and variants
NEWORLD 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 bearings
● Double row tapered roller bearings
Cylindrical roller backing bearings
NEWORLD cylindrical roller backing bearings are available in several designs and variants. The major differences between the bearings are:
● The number of roller rows (two or three)
● Bearing design with cage(s) or full complement of roller sets
● The outer ring configuration
◌ With/without integral flange(s)
● The inner ring configuration
◌ With/without integral flange(s)
◌ With/without flange ring(s)
◌ With/without guide ring(s)
◌ Bore with/without annular groove(s) and lubrication hole(s)
◌ Bore with/without lubrication hole(s)
● Open or sealed design
◌ NBR, HNBR or FKM contact seal on both sides
◌ Fey-ring seal on both sides
◌ Gap-type seal on both sides
Axial guidance
Backing bearings with integral flanges or flange rings on both the inner and outer rings can take some axial load and can provide axial guidance. Other backing bearings require thrust washers between the outer ring side faces and the support saddles (fig. 2).
Needle roller backing bearings
Features
● are based on full complement (no cage) needle roller bearings (fig. 3)
● incorporate an outer ring without a flange
● incorporate an inner ring with two integral flanges and lubrication holes
● are the smallest within the NEWORLD assortment, providing a low cross-sectional height
Tapered roller backing bearings
Features
● are based on double row tapered roller bearings, TDO design (back-to-back arrangement, fig. 4)
● are sealed on both sides with a stamped sheet steel washer
● have lubrication grooves in the small side faces of the inner rings
● accommodate axial and heavy radial loads
Cages
Cages
NEWORLD backing bearings, if not a full complement of rollers, are fitted with one, two or three of the cages
Cylindrical roller backing bearings
● are fitted with machined metal cages, double prong-type and/or prong-type, ring or roller centred (fig. 5, fig. 6)
Tapered roller backing bearings
● are fitted with two stamped steel cages, window-type, roller centred (fig. 7)
Temperature limits
The permissible operating temperature for backing bearings can be limited by:
● the dimensional stability of the bearing rings and rollers
● the cage(s)
● the seals
Where temperatures outside the permissible range are expected, contact NEWORLD.
Bearing rings and rollers
NEWORLD backing bearings are heat stabilized up to:
● 150 °C (300 °F) where based on cylindrical or tapered roller bearings
● 120 °C (250 °F) where based on needle roller bearings
Cages
Metal cages can be used at the same operating temperatures as the bearing rings and rollers.
Seals
The permissible operating temperature for seals depends on the seal material:
● NBR: –40 to +100 °C (–40 to +210 °F)
Temperatures up to 120 °C (250 °F) can be tolerated for brief periods.
● FKM: –30 to +200 °C (–20 to +390 °F)
Temperatures up to 230 °C (445 °F) can be tolerated for brief periods.
● HNBR: –40 to +150 °C (–40 to +300 °F)
● Fey-ring seals can be used at the same operating temperatures as the bearing rings and rollers.
Typically, temperature peaks are at the seal lip.
