TECHNICAL SPECIFICATIONS
Cylindrical rollers backup rolls, have full complement of cylindrical rollers, and have no pin. The outer ring’ hardness is usually customized, depending on clients’ needs; they have lamellar or lip protections and external seals sheets which are mainly used for hot rolled sheets flattering machines. They are also available with axial roller or needle roller cages (NNTRAX version).
Outer ring and inner ring
are made of 100Cr6 (UNI 3097) hardened steel, steel with the best resistance to wear due to fatigue. The surface hardness that can be achieved for these parts is 60 + 2 HRc. If requested, the hardness of the outer ring can be reduced to 53 HRc for those bearings used for very thin sheets levelling. The outer ring usually has a crowning radius (which changes depending on the size) that allows a better distribution of loads. For the outer rings of large thicknesses, 100CrMo7.3 (UNI 3097) hardened steel is used.
On request, special hardening treatments are performed, such as bainitic hardening, which is necessary in those applications in which impacts make the application too burdensome for the structure of the traditionally treated outer ring. The inner ring has holes and groove for periodic internal relubrication. The full complement rollers ensures the highest possible load capacities. The sealing system can be either with screens formed by metal elastic rings or by radial seals in steel with sliding part in traditional rubber (NBR) or special rubber for high temperatures or resistant to various solvents (FKM). The dimensional and running accuracy of these bearings is generally according to class P0 (DIN 620) but can be brought up to P6 or P5. Stainless steel executions are available on request.
The cylindrical roller backup rolls are built with two or more full complement crowns of cylindrical rollers separated by spacers integrated into the outer ring. The large load capacities, both dynamic and static, of this type of back-up rollers ensure that they are used in large quantities in those steel sheet levelling or straightening machines that work continuously and in severe operating conditions. These bearings also ensure good axial load capacities suitable for counteracting the axial thrusts that are inevitably generated in the above-mentioned applications.