Rolling mill rolls and roll bearings are an important part of the rolling mill. In rolling production, the roll is in direct contact with the rolled metal, which is prone to plastic deformation of the metal. Therefore, the roll is the main deforming part of the rolling mill. The roll is supported by various bearings. The quality and life of the roll and the roll bearing are related to the quality of the rolling mill product. , Production efficiency and production cost are directly related. Therefore, the use and maintenance of rolling bearings and damage treatment are very important.
Rolling bearings are used to support rolling bearings. Compared with general-purpose bearings, rolling bearings have the following characteristics
1. Withstand high unit pressure
Because the outer dimensions of the housing are restricted, it must not exceed the minimum diameter of the roller body, and because the length of the neck is short, the unit load of the bearing is relatively large. The unit pressure of general rolling bearings is as high as 2000-4800Mpa, which is 2 to 5 times that of general bearings, and the pv value (the product of unit pressure and linear velocity) is 3-20 times that of general bearings.
2. The operating speed varies greatly
Different rolling mills have different operating speed requirements, and the speed difference is still very large. For example, the export speed of the modern six-stand cold casting rolling mill reaches 42m/s, the exit speed of the high-speed wire rod mill reaches 100m/s, and the speed of the low-speed rolling mill is only 0.2m/s. Obviously, rolling mills of different speeds should use different types of bearings.
3. Poor working conditions
During hot rolling, the roll must be cooled with water, and sewage, iron oxide scraps, etc. are easily immersed in the bearing. The cold rolling mill adopts process smoothing agent (emulsion, etc.) to smooth and cool the material of the roll and rolling piece, and the smoothing agent cannot be mixed with the bearing emulsion liquid. This requires high sealing of the bearing.
Therefore, the requirements for rolling bearings are large load capacity, small impact coefficient, impact resistance, and operation at different speeds. The structure requires the radial size to be as small as possible (in order to select a large neck diameter), and have excellent smoothness and cooling. condition. If necessary, remove the roll bearings from the rolling mill for inspection and maintenance to obtain the maximum roll bearing life. The maintenance and maintenance frequency of the bearing need to be adjusted according to the working conditions of the rolling mill, which varies with the working conditions.
The protection process of rolling bearings
1. Bearing cleaning
In the process of cleaning the bearing, all shedding, stagnant water, residual smoothing agent and other dirt that cause bearing wear must be removed. The size of the bearing to be cleaned and the number of bearings determine the cleaning method and cleaning agent selected for cleaning the bearing.
2. Lubricate the bearings
Use gear lubricants with excellent viscosity-temperature properties, oxidation stability, rust resistance, and wear resistance to lubricate bearings. The filling amount of grease is preferably 2/3 or 1/3 of the space between the bearing and the bearing housing.
