The Design of Rolling Bearing Mountings

Rollbending bearingsA counterbending force is generated by means ofhydraulic jacks. The counterbending force (max.345 kN per bearing location) is transmitted to the rollneck by spherical roller bearings FAG23980BK.MB.C5. The bearings ensure low-frictionroll rotation and accommodate misalignments resultingfrom shaft deflection.Preloading bearingsThe main bearings of roll 3 have to accommodate thedifference from the rolling forces from rolls 2 and 4. Inorder to avoid uncontrolled radial roll movements, themain bearings are preloaded with 100 kN via sphericalroller bearings FAG 23888K.MB.C5.Bearing dimensioningTwo cylindrical roller bearings FAG 522028.. mountedside by side have a dynamic load rating of 2 x2,160 kN. The load accommodated by the bearings iscalculated, depending on the load direction, from (rollweight + press-on force + counterbending force)/2.The dimensioning calculation is carried out for themost heavily loaded roll 2 which rotates at an averagespeed of 15 min –1 .The nominal life is approx. 77,000 hours. Due to thehigh bearing temperature, the attainable life, whichtakes into account the amount of load, lubricant filmthickness, lubricant additives, cleanliness in the lubricatinggap and bearing type, is only 42,000 hours.The required bearing life of 40,000 h is reached.Machining tolerancesMain bearings:Guiding bearing:Preloading bearing:Rollbending bearing:LubricationShaft to r6/housing to H6Shaft to g6/housing radiallyrelievedShaft tapered/ housing H7Shaft tapered/ housing to H7The bearings are lubricated with oil. The lubricant hasto meet very stringent requirements. Due to the lowspeed and the high operating temperature, no elastohydrodynamiclubricant film can form. As a result, thebearings always operate in the mixed-friction rangeand are exposed to the risk of increased wear. This conditionrequires particularly suitable and tested lubricatingoils.A central circulation lubrication system with recoolingsupplies all bearings with oil. Holes in the bearinghousings, circumferential grooves in the bearing outerrings and in the spacers as well as radial grooves in theouter faces feed the oil directly into the bearings.Lip seals in the housing covers prevent dirt particlesfrom penetrating into the bearings.a Main bearing arrangement (radial), at each end of all rolls:2 cylindrical roller bearingsb Main bearing arrangement (axial), at the drive end of all rolls:1 deep groove ball bearing 61996M.P65c Preloading bearing arrangement, each end of roll 3:1 spherical roller bearing 23888K.MB.C5d Rollbending bearing arrangement, each end of rolls 2 and 4:1 spherical roller bearing 23980BK.MB.C5d c b a25: Bearing arrangement of a plastic calender39 FAG