Eight roller rolling back lining bearing inner ring damage reason analysis

A cold rolled sheet plant rolling mill equipment in eight roller rolling all five continuous planning, mill using backing bearings for 3 pl130m. Backing bearing is a kind of special thick outer ring, using the device in group in the stillness of the shaft become more supporting roller of roller mill rolling bearing. Backing bearings eliminate radial clearance after the end face of H value of 0. 005 mm, bearing factory is a factory group number, device shall not disturb the original number of group bearing, in the middle of the bearings on each shaft H value maximum, adjacent bearing outside diameter to 0. 002 mm additive, the whole bearing control in 0. Less than 005 mm, each batch of bearing clearance at 0. 04mm- 0. 07mm。 The bearing is 5 sets of bearings for a set of device on a spindle, the damage roll under 5 # frame, bearing damage in the both sides of the bearing. Smooth bearing using 220 # smooth gear oil, cooling use emulsion cooling, rolling product thickness is 0. 5 mm, width is 620 mm and 630 mm, 5 # mill 600 RPM ( Scrap sheet frame) , reduction in 3 to 5 between, bearing damage way below; Figure a figure 2 figure it is the group on both sides of the backing bearing inner ring is damaged, damaged condition the same on both sides, damage location is in figure 2 # 1 and # 5 bearing inner ring. Figure 2 is a set of backing bearings are assembled at the end of state. The scene to understand the billet bearing a total of 100 sets, the arrival of the damaged bearing on 15 days, in the 1 # and 5 # inner ring loading area at present large area of spalling, intermediate 2 # 3 # 4 # bearing inner ring without peeling, other bearing online using 2 wheel is not presented as a way of damage, the scene to understand the backing bearings with spindle constantly didn't check. Rolling plate width is different, each backing on the backup roll bearing number is 3 ~ 7. For request of rolled plate edge, adjustment of rolling strip shape as a result, each root on the backup roll from both ends to maximum mileage accept 2 sets of shaft force, commonly known as 'the phenomenon of cat ears'. The force difference how dozens to several times. The more a number of backup roll bearing the force difference is smaller. So the second and the fourth set of bearing the most easily damaged. Structural problem unable to prevent it. Better processing method is in the process of bearing manufacture and installation, matching each backup roll on several sets of bearing the cross section of high differential values of 'H' to each other, slightly in the middle of the request of several microns. For example in the third set of bearing 'H' slightly larger, on both sides of the bearing H a additive of a few microns. After the above understanding identifying damage of # 1 and # 5 bearing inner ring is due to the core shaft deflection out-of-tolerance as main elements form a large area of spalling and initiative of spindle stop measurement, repair regularly.