First, the lubrication method
The lubrication of the roller
bearings is basically the same as that of other rolling bearings. However, the working conditions of the roller bearings are rather harsh, and whether the working performance can be effectively exerted depends largely on the lubrication of the bearings.
The lubrication methods used for roll bearings are mainly grease lubrication and oil lubrication.
The grease-lubricated grease has a sealing function, the sealing structure and the lubrication facility are simple, and the grease is convenient to be replenished, so the roller bearings are generally grease-lubricated as long as the working conditions permit.
The oil lubrication has a strong cooling effect and can remove dirt and moisture from the bearing. Roller bearings use oil-lubricated lubrication methods such as pressure oil lubrication, fuel injection lubrication, oil mist lubrication and oil and gas lubrication.
Pressure oil lubrication is the most effective lubrication method for roller bearings at normal speed.
Injection lubrication is to lubricate the lubricating oil at a certain pressure through the injector mounted on one side of the bearing for lubrication. It is generally used in high-speed roller bearings, or where the pressure supply lubrication cannot meet the cooling requirements.
Spray lubrication is to spray dry compressed air containing oil mist into the bearing for lubrication. The use of less oil, due to the action of air, the cooling effect is very strong, mainly used for large roll bearings with high rolling speed and high rolling precision. Or for roller bearings that are not often removed in the bearing housing.
Pressure oil lubrication and fuel injection lubrication require the installation of inlet and outlet pipes, lubrication pumps, oil reservoirs, and sometimes oil coolers. Therefore, the cost is high, and general roller bearings are less used.
Second, the configuration type
(1), spherical roller bearing
The configuration of the early rolling mill
bearings on the rolling mill was different from the current one. At that time, two sets of spherical roller bearings were mainly installed side by side on the same roll neck. This configuration basically meets the production conditions at that time, and the rolling speed can reach 600 rpm. However, with the increase of speed, its shortcomings become more and more prominent: short bearing life, large consumption, low precision of finished products, severe wear of the roll neck, and large axial turbulence of the rolls.
(2), four-row cylindrical roller bearing + thrust bearing
The inner diameter of the cylindrical roller bearing is tightly matched with the roll neck and can withstand radial force. It has the advantages of large load capacity, high limit speed, high precision, separable inner and outer rings, interchangeable, easy processing, low production cost, convenient installation and disassembly, etc. The thrust bearing is subjected to axial force, and the specific structure type can be selected according to the characteristics of the rolling mill.
Heavy-duty low-speed, with thrust roller bearings, with a small axial clearance to withstand the thrust load. When the rolling speed is high, it is equipped with angular contact ball bearings, which not only has high speed limit, but also can control the axial play during operation. The rolls are tightly axially guided and can withstand typical axial load forces.
This type of bearing configuration not only has long bearing life, high reliability, but also has many advantages such as high precision and easy control of rolling products. Therefore, it is currently widely used in wire rod mills, sheet mills, foil mills and double support rolls. Support rolls for rolling mill cold rolling mills and hot rolling mills.
(3), four row tapered roller bearings
The tapered roller bearing can withstand both radial and axial forces without the need for a thrust bearing, so the mainframe is more compact. The inner diameter of the tapered roller bearing is loosely matched with the roll neck. It is very convenient to install and disassemble, but sometimes it will cause sliding creep due to the loose fit. Therefore, the inner diameter is often processed with a spiral oil groove.
This type of configuration is still widely used, such as the work rolls of four-high hot rolling mills and cold rolling mills, such as work rolls, blanking machines, and steel beam rolling mills.
