RKB Guidelines for Mounting Four-Row Cylindrical Roller Bearings Poster0 pages

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MOUNTING GUIDELINES FOR

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RKB FOUR-ROW CYLINDRICAL ROLLER BEARINGS IN ROLLING MILL APPLICATIONS

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BEARING INDUSTRIES

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1 - Loose flange rings

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2 - Outer rings

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3 - Cages

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4 - Rollers

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5 - Central spacer

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6 - Inner rings

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RKB multi-row cylindrical roller bearings are used almost exclusively to support the roll necks of back-

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up rolls in rolling mill machinery. They are designed with well-balanced cross-sections to provide the

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highest possible radial load carrying capacity within the bearing envelope.

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In order to properly meet application requirements, RKB multi-row cylindrical roller bearings are

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produced in several designs and executions that basically differ in the number of inner and outer rings,

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in the number of loose or integral flanges on the outer ring, in the cage type, in the number of rollers and

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related arrangement in cage pocket.

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Multi-row cylindrical roller bearings can accommodate only radial loads and tolerate moderate to high

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mill speeds; possible axial loads have to be accommodated by other types of bearings (deep groove

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ball bearings, angular contact ball bearings, tapered roller bearings, tapered roller thrust bearings, or

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spherical thrust roller bearings).

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RKB four-row cylindrical roller bearings are of separable design, which considerably simplifies mounting,

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inspection and maintenance operations.

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Both inner rings (designation L) and outer ring assemblies (designation R) are interchangeable, this

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being helpful for quick roll replacement.

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Outer ring assemblies, consisting of outer rings, rollers, and cages, can be mounted independently of

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inner rings, or all bearing components can be mounted separately.

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The mounting of the bearing onto the roll neck has to be in accordance with the mounting instructions

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supplied with the rolling mill machinery design.

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PRELIMINARY OPERATIONS

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-

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—L

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Prior to mounting, measure the chock bore diameter in four equally spaced planes normal to the

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bore axis of symmetry (a, b, c, d) and in each plane in four directions offset at 45° (1, 2, 3, 4). These

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measurements have to be properly recorded.

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Measure the shaft diameter in four planes (or three, according to the neck shape) normal to the

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shaft axis of symmetry (a, b, c, d) and in each plane in four directions offset at 45° (1, 2, 3, 4). These

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measurements have to be properly recorded.

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Bore and shaft shape deviations are highly recommended to be measured as well. Record all these

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measurements in a measuring report.

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Properly lubricate bearing components according to the lubricant suggested in the rolling mill

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machinery design.

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For easy mounting, be sure that the chock and the shaft are clean and lubricated; this will reduce the

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wear and corrosion of the assembly elements during operation.

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MOUNTING OF INNER RINGS ONTO THE ROLL NECK

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Push the labyrinth ring or backing ring (heated in an oil

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bath) onto the roll neck until it abuts the roll body face

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without a gap.

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Heat the inner rings in an oil bath or, if available, using an

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induction coil.

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When the inner rings are heated in an oil bath, use a

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thermostatto avoid excessively high heating temperature.

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Wipe off the oil in the bores and from the faces of the

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bearing inner rings after they are removed from the oil

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bath.

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If the roll neck end is not shaped to guide the inner

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rings (stepped sections), we highly recommend using a

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mounting sleeve.

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In case of small bearings, manually push the inner rings

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(heated in an oil bath) on the roll neck.

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In case of large bearings, use mounting grippers, which

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have to carry the rings always with their axis in a horizontal

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position.

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For inner rings heated using an induction coil, push

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STEP I

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manually or using an appropriate lifting device the coil

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together with the bearing inner ring onto the roll neck.

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WARNING!

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After using an induction coil, bearing inner rings and

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roll necks remain magnetized and have to be properly

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demagnetized. This can be done by pulling the induction

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coil itself over the mounted part with the current switched

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on and slowly removing to a distance of 1-2 meters from the

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parts.

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• After cooling down, the rolling bearing inner rings should

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abut the labyrinth ring without a gap.

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• Inner rings of smaller bearings can be mounted without a

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gap between them by pushing a mounting sleeve against

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the ring face while the rings cool down.

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• After mounting onto the roll neck,itis highly recommended

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to measure the raceway diameters of the inner rings

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carrying out the same procedure for measuring the shaft

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diameter.

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MOUNTING OF THE CHOCK ONTO THE ROLL NECK

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STEP

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Check if the labyrinth ring and the inner rings have been fitted onto the roll neck.

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Mount the seal neighboring the shaft shoulder onto the chock.

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Carry in a horizontal position the pre-assembled chock (complete with outer ring assembly and bearings which should

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take the axial loads) to the roll neck by means of a crane.

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Align the chock as closely as possible with the roll neck so that the chock can be easily pushed onto the roll neck.

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Carefully push the pre-assembled chock onto the roll neck so that no score marks are produced on the rollers or inner

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ring raceways.

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Mount the axial clamping and the sealing system onto the shaft and make sure that it is properly adjusted and secured.

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MOUNTING OF OUTER RINGS INTO THE CHOCK

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1

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STEP

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LARGE SIZE BEARINGS

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• Fasten the roll-side cover onto the chock.

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• Place the chock with its bore axis in horizontal

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position.

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• Be sure that the outer rings have their axis aligned

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with the chock bore axis.

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• Insert the rings into the chock using a beam

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suspended in ropes or cables.

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SMALL AND MEDIUM SIZE BEARINGS

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Fasten the roll-side cover onto the chock.

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Place the chock on level supports with bore axis in

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vertical position.

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In case of small bearings, manually insert the outer

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rings into the chock.

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In case of medium bearings, insert the outer rings

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into the chock by means of a special clamping/

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lifting device or, when the bearing is provided with

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threaded holes for eye bolts, by means of ropes,

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cables or chains attached to the crane hook.

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On initial mounting, place the outer ring marked zone in the load direction and mark the position on the top

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of the chock.

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Carefully place the desired load zones of the outer rings in the same direction.

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Make sure that adjacent parts abut each other completely and check the seating of the outer ring against

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the cover shoulder or loose flange with a feeler gauge.

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If need be, mount the bearing which should take the axial loads.

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DISMOUNTING

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Dismounting of RKB four-row cylindrical roller bearings from the roll neck encompasses two distinct phases:

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1) Withdrawal of the chock from the inner rings

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• Remove the axial clamping and the sealing system from the roll neck.

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• Carefully remove the chock from the roll neck as a complete unit.

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• When only the rolls are replaced, mount the chock onto the new roll neck only after the inner rings have been

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installed on it.

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• Dismount bearing components for inspection in the reverse order of mounting and using the same equipment.

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2) Extraction of the inner rings from the roll neck

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• If the inner rings are mounted with tight fit on the roll neck, use the same induction coil as for mounting.

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• Quickly heat the inner rings in order to release the tight fit.

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RKB GX DESIGN

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The RKB new generation four-row cylindrical roller bearings GX type introduce optimized features such as

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the double window-type cage, the alternate long/short roller arrangement and the inner ring with higher

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chamfer on the raceway.

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To improve bearing lubrication there are annular grooves and lubrication holes on the outer rings and

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lubrication grooves in their side faces.

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The special GX type configuration alternating long and short rollers has been introduced to get a better load

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distribution and reduce the edge contact pressure typical of standard designs.

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Another important feature introduced by the RKB GX configuration is the higher chamfer angle and length on

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the inner ring raceway, specific for each different geometry.

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The controlled drop of rollers, obtained through the double window-type cage and the new dimension of the

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inner ring chamfer, permits a quicker and more efficient mounting with a much lower incidence of bearing

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damages.

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Standard design:

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not controlled drop of rollers

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RKB GX design:

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controlled drop of rollers

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WWW.RKBBEARINGS.COM

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Engineered in Switzerland

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Technological Bearings

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