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The Instruction of RCB Oil Film Bearing

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Update time : 2017-08-22 17:21:01
Oil film bearing is also known as liquid lubricated bearing. It makes use of liquid lubrication to form a integrated pressure film between the roll shaft and oil film bearing to separate the two working surfaces, and not have direct metallic contact, to achieve liquid lubrication state. It is widely used in rolling mill bearing.
Oil film bearing is a kind of sliding bearing with ideal matched parameters including  main surface machining precision, surface roughness and other related parameters. Its main features are large loading capacity, long service  life, small structure dimension , low friction coefficient, and great anti-shock resistance.
1 Overhauling and cleaning of oil film bearing
The cleaning condition of bearing parts is very important for the bearing running. whether picking up from warehouse or disassembly to make maintenance , it should clean the bearing components by cleaning solvent. The components must be thoroughly rinsed before assembly, especially the components with oil way. It must thoroughly rinse all the components disassembled from the roll-box of finish rolling mill, then blow-dried them, and carefully inspect whether there is any damage or abrasion to make sure whether it can be reused.
2 Assembly and inspection of oil film bearing
It should  strictly examine each key assembly dimensions of roll-box (expect geometric tolerance) before the bearing installation. The component, which is inconformity  to the drawing requirements, can not be used. The wall thickness of oil film bearing is very thin,  if the oil film bearing is pressed into the inner bore of eccentric bushing,  under the pressure effect, the oil film bearing may have creasing phenomenon, and  also have adhesion  between the outer surface of the bearing and the bore of eccentric bushing. In  order to reduce this phenomenon,  it could decrease  the magnitude of  interference by heating the eccentric bushing and  freezing the oil film bearing before assembly.
2.1    Assembly of eccentric bushing and oil film bearing:
  • Firstly, examine the pairing marks, and then completely discompose the spare parts of eccentric bushing. It should pull out the pin first and then dismantle the bolt.
  • Inspect each matching dimension of eccentric bushing. Inspect whether there is high spot on the surface of inner and outer bore of eccentric bushing by vision. If there is high spot, smoothing it by filing. Whether there is burr and scratch on each surface and chamfer,  if any, remove by fine sandpaper and clean the big and little end by detergent, especially the oil holes,  and blow-dry it by compressed air.
  • After cleaning the eccentric bushing, put it into the oven to heat it for 3 or 4 hours. The heating temperature of the eccentric bushing is 120° for 170 roll-box, 130° for 230 roll-box, and 170° for 280 roll-box.
  • Put the two pieces of oil film bearings into special conical fixture after assembly, and enclose into low temperature test chamber, the cooling temperature is 80° below zero, and the cooling time is 3 or 4 hours.  Or when the temperature of eccentric bushing is approaching the heating temperature, put the oil film bearing into the special conical fixture and cooling them together in the dry ice bunker or liquid nitrogen, when the heating time of eccentric bushing is over, at the same time put the oil film bearing into liquid nitrogen to cool it for 10 minutes.
  • Take out the eccentric bushing and place it according to the picture below
  • Put the tooling on the eccentric bushing, and ensure that the marking line on the guide sleeve is aligned with the scribed line on the eccentric bushing
 

 
  • Take out the oil film bearing from liquid nitrogen by pair, and  put it into the guide sleeve quickly, and install it into eccentric bushing by bar molding at the same time to align the scribed line, distinguish the two sides of loading and non-loading. The oil supply hole of eccentric bushing should be aligned to assemble the non-loading  bearing bushing, as shown below:
  • Slowly hang the roll shaft into the eccentric bushing to assemble them, which could avoid the shaft shoulder damage the oil film bearing. Before assembly, lubricating the inner surface of oil film bearing and the matching surface of  roll shaft  by clean lubricating oil Mobil 525.
2.2    Inspect the radial clearance of oil film bearing
Take the radial clearance inspection of oil film bearing in roll box 285 as example. Place the roll box horizontally,  install the tolling and dial indicator in place, insert the 600mm long iron rod into the bolt hole of the little end of the roll shaft, and lift it with the moment 440N.m. The value of dial indicator is the radial clearance of oil film bearing (the gauge stand should place on the support plate). The picture as below:
The picture for the radial clearance inspection of oil film bearing
 
2.2    Points for attention
  • Examine the clearance between the outer diameter of eccentric bush and the face-plate bore diameter, if it is greater than 0.15mm, then the eccentric bush could not be used to match with the face-plate. Measure it individually, and scrapped or not by the result.
  • Strictly control the assembly dimensions of double lip seal of the roll shaft, and  ensure the effect of oil and water sealing to reach the using requirement.
  • Examine the wear pattern of oil film bearing. It the wear extent occupies more than 1/3 of the full-length, there are much more scratch points on the surface, and partial abrasion is seriously, the alloy coating fell off completely, and the metal came out, please replace the oil film bearing timely.
  • Synthetically control the various indicators of the lubricating oil on line, especially the viscosity, impurity containing, water content etc.
  • It required to fill the data in the assembly record faithfully, including the conditions such as components reusing, the distance between eccentric bush and face-plate, the clearance of oil film bearing, idle running etc. The contents should be in detail and comprehensive in order to check back for future.
RCB Bearing is established in 2002 accumulating more than 15 years of experience, RCB Bearing is now a leading business enhancement solutions company providing high quality bearings(including angular contact ball bearing, taper roller bearing, spherical roller bearing, cylindrical roller bearing, automobile bearing, slewing bearing, deep groove ball bearing, rolling mill bearing etc.), power transmission and related products.