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Rolling Mill Bearings

wd Cylindrical and tapered roller bearings for rolling mill
 
WD four-row cylindrical roller bearingsare used almost exclusively for the roll necks of rolling mill stands, calenders and roller presses. Their friction is low compared with other roller bearings. As they are normally mounted with an interference fit on the roll neck, they are particularly suitable for rolling mill applications where the rolling speed is high.
 
The low bearing cross section allows for relatively large roll neck diameters in comparison with the roll diameter. Since very many rollers can be incorporated, the radial load carrying capacity is exceptionally high.
 
WD four-row cylindrical roller bearings are only able to accommodate radial loads. They are therefore mounted together with deep groove or angular contact ball bearings, or with tapered roller bearings, either radial or thrust designs, which take up the axial loads.
 
Internal clearance：
WD four-row cylindrical roller bearings are normally produced with the C3 or C4 radial internal clearance required for rolling mill bearings. Bearings mounted with a loose fit on the roll necks generally have C2 radial internal clearance.
 
The clearance values, where standardized, conform to ISO 5753:1991 and are given in the following tables for bearings with cylindrical bore and bearings with tapered bore. They are valid for unmounted bearings under zero measuring load.
Tab1:
Radial internal clearance of WD cylindrical roller bearings with cylindrical bore:
Bore Radial internal clearance                
diameter
d		   C1 SPC2 C2 Normal C3 C4 C5
over incl. min max min max min max min max min max min max min max
mm µm                            
- 24 - - - - 0 25 20 45 35 60 50 75 65 90
24 30 5 15 10 25 0 25 20 45 35 60 50 75 70 95
30 40 5 15 12 25 5 30 25 50 45 70 60 85 80 105
                               
40 50 5 18 15 30 5 35 30 60 50 80 70 100 95 125
50 65 5 20 15 35 10 40 40 70 60 90 80 110 110 140
65 80 10 25 20 40 10 45 40 75 65 100 90 125 130 165
                               
80 100 10 30 25 45 15 50 50 85 75 110 105 140 155 190
100 120 10 30 25 50 15 55 50 90 85 125 125 165 180 220
120 140 10 35 30 60 15 60 60 105 100 145 145 190 200 245
                               
140 160 10 35 35 65 20 70 70 120 115 165 165 215 225 275
160 180 10 40 35 75 20 75 75 125 120 170 170 220 250 300
180 200 15 45 40 80 35 90 90 145 140 195 195 250 275 330
                               
200 225 15 50 45 90 45 105 105 165 160 220 220 280 305 365
225 250 15 50 50 100 45 110 110 175 170 235 235 300 330 395
250 280 20 55 55 110 55 125 125 195 190 260 260 330 370 440
                               
280 315 20 60 60 120 55 130 130 205 200 275 275 350 410 485
315 355 20 65 65 135 65 145 145 225 225 305 305 385 455 535
355 400 25 75 75 150 100 190 190 280 280 370 370 460 510 600
                               
400 450 25 85 85 170 110 210 210 310 310 410 410 510 565 665
450 500 25 95 95 190 110 220 220 330 330 440 440 550 625 735
500 560 25 105 105 210 120 240 240 360 360 480 480 600 690 810
                               
560 630 25 115 115 230 140 260 260 380 380 500 500 620 780 900
630 710 30 130 130 260 145 285 285 425 425 565 565 705 865 1005
710 800 35 145 145 290 150 310 310 470 470 630 630 790 975 1135
                               
800 900 40 160 160 320 180 350 350 520 520 690 690 860 1095 1265
900 1000 - - - - 200 390 390 580 580 770 770 960 1215 1405
1000 1120 - - - - 220 430 430 640 640 850 850 1060 1355 1565
                               
1120 1250 - - - - 230 470 470 710 710 950 950 1190 1510 1750
1250 1400 - - - - 270 530 530 790 790 1050 1050 1310 1680 1940
1400 1600 - - - - 330 610 610 890 890 1170 1170 1450 1920 2200
                               
1600 1800 - - - - 380 700 700 1020 1020 1340 1340 1660 2160 2480
1800 2000 - - - - 400 760 760 1120 1120 1480 1480 1840 2390 2760
                               

Tab 2:
Radial internal clearance of WD cylindrical roller bearings with tapered bore
Bore Radial internal clearance                
diameter
d		   C1 SPC2 C2 Normal C3 C4 C5
over incl. min max min max min max min max min max min max min max
mm µm                            
- 24 - - - - 15 40 30 55 40 65 50 75 70 95
24 30 15 25 25 35 20 45 35 60 45 70 55 80 75 100
30 40 15 25 25 40 20 45 40 65 55 80 70 95 90 115
                               
40 50 17 30 30 45 25 55 45 75 60 90 75 105 105 135
50 65 20 35 35 50 30 60 50 80 70 100 90 120 125 155
65 80 25 40 40 60 35 70 60 95 85 120 110 145 145 180
                               
80 100 35 55 45 70 40 75 70 105 95 130 120 155 175 210
100 120 40 60 50 80 50 90 90 130 115 155 140 180 200 240
120 140 45 70 60 90 55 100 100 145 130 175 160 205 225 270
                               
140 160 50 75 65 100 60 110 110 160 145 195 180 230 255 305
160 180 55 85 75 110 75 125 125 175 160 210 195 245 280 330
180 200 60 90 80 120 85 140 140 195 180 235 220 275 305 360
                               
200 225 60 95 90 135 95 155 155 215 200 260 245 305 340 400
225 250 65 100 100 150 105 170 170 235 220 285 270 335 375 440
250 280 75 110 110 165 115 185 185 255 240 310 295 365 415 485
                               
280 315 80 120 120 180 130 205 205 280 265 340 325 400 465 540
315 355 90 135 135 200 145 225 225 305 290 370 355 435 515 595
355 400 100 150 150 225 165 255 255 345 330 420 405 495 580 670
                               
400 450 110 170 170 255 185 285 285 385 370 470 455 555 650 750
450 500 120 190 190 285 205 315 315 425 410 520 505 615 720 830
500 560 130 210 210 315 230 350 350 470 455 575 560 680 800 920
                               
560 630 140 230 230 345 260 380 380 500 500 620 620 740 900 1020
630 710 160 260 260 390 295 435 435 575 565 705 695 835 1005 1145
710 800 180 290 290 435 325 485 485 645 630 790 775 935 1125 1285
                               
800 900 200 320 320 480 370 540 540 710 700 870 860 1030 1265 1435
900 1000 - - 355 540 410 600 600 790 780 970 960 1150 - -
1000 1120 - - 395 600 455 665 665 875 865 1075 1065 1275 - -
                               
1120 1250 - - 440 670 490 730 730 970 960 1200 1200 1440 - -
1250 1400 - - 490 490 740 550 810 810 1070 1070 1330 1590 - -
1400 1600 - - 560 840 640 920 920 1200 1200 1480 1480 1760 - -
                               
1600 1800 - - 630 950 700 1020 1020 1340 1340 1660 1660 1980 - -
1800 2000 - - 700 1060 760 1120 1120 1480 1480 1840 1840 2200 - -
                               
 
Working temperature:
WD multi-row cylindrical roller bearings are subjected to a special heat treatment as standard so that they can be operated at temperatures up to +150 ℃ without any inadmissible dimensional changes occurring. To order, and against a surcharge, bearings can be dimensionally stabilised for operating temperatures up to +200 ℃ (designation suffix S1) or up to +250 ℃ (designation suffix S2). An advantage of this special heat treatment is that the bearings can be mounted with a greater degree of interference than is possible with standard bearings. For further information please contact the WD application engineering service.
 
Cages：
WD four-row cylindrical roller bearings, depending on size and also application, are produced with the following cages:
    Two or three double pronged machined brass cages
    Two double row window-type brass cages
    Four pronged machined brass cages
 
Minimum load：
In order to guarantee satisfactory operation, WD multi-row cylindrical roller bearings, like all ball and roller bearings, must always be subjected to a given minimum load, particularly if they are to operate at high speeds or are subjected to high accelerations or rapid changes in the direction of load. Under such conditions the inertia forces of the rollers and cage, and the friction in the lubricant, can have a detrimental effect on the rolling conditions in the bearing arrangement and may cause damaging sliding movements to occur between the rollers and the raceways.
 
The requisite minimum load to be applied to multi-row cylindrical roller bearings can be estimated using:
    
where
Frm = minimum radial load,kN
kr = minimum load factor(see product tables)
n = operating speed，r/min
dm = mean diameter of bearing
 
 = 0,5(d+D),mm
 
When starting up at low temperatures or when the lubricant is highly viscous, even greater loads may be required. The weights of the components supported by the bearing, together with the external forces, generally exceed the requisite minimum load. If this is not the case, the AWD multi-row cylindrical roller bearing must be subjected to an additional radial load.
 
     Equivalent dynamic bearing load: P = Fr
     Equivalent static bearing load: P0 = Fr
 
Mounting instructions：
Knowledge and experience are of particular importance where WD four-row cylindrical roller bearings are concerned. The individual components must be mounted in the correct order. Parts which belong together are marked with letters. In addition, all components of the bearing are marked with the same serial number, so that there is no risk of mixing components if several bearings are to be mounted at the same time. However, the inner rings and inner ring pairs are fully interchangeable and need not to have the same serial number as the outer ring(s).
 
In the majority of applications the load is of constant direction, so that approximately only a quarter of the outer ring is under load. For this reason, the side faces of the outer rings are divided into four zones indicated by I to IV. The markings for load zone I are also joined by a line across the outside surface of the outer rings.
 
When the bearing is mounted for the first time it is usual to position zone I in the direction of action of the load. Depending on the operating conditions, the outer rings should be turned through 90°after a period of service so that a new zone comes under load.
 
Detailed mounting instructions are also supplied with all bearings.

WD Precison Rolling Mill Bearings:four-row cylindrical roller bearings
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