The causes of the problem of the oil film bearing
DF 1 seal structure working principle of the backup roll neck cone rotation with oil film bearings taper sleeve, relative to each other during operation, Bushing and bearing etc relatively static, two of DF sealing lip on the face side of the backup roll sealing water and prevent iron oxide into the oil film bearing, the face of the medial near the taper sleeve to prevent oil leakage; Water seal of the first line of defense is to prevent a large amount of cooling water and oxide into; Aluminum ring, is the second line of defense by centrifugal force to jilt water maze (waterproof); The key DF seal constitute the third line of defense, really played an import to prevent cooling water and lubricating oil leakage, to ensure that the taper sleeve between the bushing and the formation of the dynamic pressure of oil film, in order to ensure the safe operation of oil film bearing.
Cause analysis, I plant at the beginning of the production, the oil film bearing running in good condition, because with parts related dimension precision is good, but with longer duration of use, for various reasons caused the roll neck seal did not run in ideal condition, the various problems gradually emerge: our factory roughing backup roll of oil film bearing is reversing mill, axial force at runtime channeling move than finishing mill is more outstanding, the operation condition of the additional roughing mill when rolling condition is extremely bad, such as the material thickness of the blank, causes the crude oil film bearing in rolling bearing roller axial forces are generated at runtime dynamic, rolling roll shaft shoulder and end face, the spacing between the bearing are designed to provide the data of 905 mm, the field measurement data of 82 mm - 82 mm, momentum is larger than design value range, caused the backup roll roll neck seal failure and water seal pressure is too large, heavily damaged seal aluminum ring rubber nails, can't play a role to jilt water, water seal lip seal is damaged, a large number of cooling water in, DF seal can not effectively prevent water from entering the oil film bearing.
Roughing backup roll gap of the connecting rod bearing wear head is too big, is beyond the standard, the rolling roll shaft shoulder and bearing transverse spacing between 905 mm cannot control accuracy, caused the increase of the axial force up momentum, aluminum ring wear rubber nails, not with the backup roll synchronous rotation, cannot to jilt water, water seal lip compression of abnormal wear and tear, cooling water directly into the internal of the oil film bearing. Roughing at run time, the oil film bearing bearing roller of roller surface depressions, is caused by the residual oxides, caused in the process of rolling bearing roller uneven, the axial force. Our backup roll structure in the original design of the oil film bearing, there are some defects in the work side installed double row tapered bearing, the drive side is not installed double row tapered bearing, so drive side bearing axial channeling move under the condition of the connecting rod head wear, cannot be effectively controlled.
Countermeasures and measures to solve above problems some measures: between backup roll bearing seat connecting rod rod head and join this groove wear repair, measured on a regular basis, to ensure that the two bearing seat within the scope of center distance of 2980 mm. The oil film bearing in suit when backup roll, hydraulic lock, lock nut ring process size control, cannot make backup roll roll neck cone and the oil film bearing in the taper sleeve too tightly on the cone, when installing a key anti-rotating locating bolt, when positioning to rotate the appropriate distance in the opposite direction. The backup roll bearing seat sealing the upper end cover, install the additional seal, to slow the cooling water of the roll neck seal rush shoot directly.