Application of Centralized Lubrication on Roller Screen
Introduction
The Roller screen is mainly used in places where materials need to be classified, such as coal mines, mineral processing plants, and power plants. It is the main screening equipment in the coal conveying system. After screening, the coal and shale smaller than the sieve holes fall below the Roller screen, while the coal and shale larger than the sieve holes move forward on the sieve surface. During the transportation process, a large amount of dust is formed, so the working environment of the equipment is harsh. When the Roller screen is operating, there is significant vibration, and each shaft has a large working load, so each bearing also bears a large load. Such a working environment is very unfavorable for the shafts and bearings, affecting the service life of the bearings and causing damage. Moreover, the Roller screen has many bearing housings, so timely protection and lubrication of each bearing is extremely important.
Roller screen centralized lubrication system
The roller screen adopts a single-line progressive centralized lubrication system. Its main components include a lubrication pump, an oil filter, an oil supply pipe, branch pipelines, a main distributor, various level distributors, and an electrical control box. The main function of the lubrication pump is to store lubricating grease and transfer the stored lubricating grease to each lubrication point; the distributor is the foundation and important component of the system, which can maintain system pressure and supply sufficient lubricating grease to each lubrication point; the main function of the supply pipe and branch pipelines is to connect the lubrication pump with the distributor, and the distributor with the lubrication points; the main function of the oil filter is to filter impurities and ensure the supply of clean oil; the main function of the electrical control box is to control the lubrication pump to work according to the predetermined cycle, and has functions such as monitoring and alarming the system pressure and level, and displaying the system working status.
The lubrication pump outputs lubricating grease, which is transformed from one-way oil supply to multi-way oil output by the first-level distributor. These multi-way outputs are then divided into more branch oil paths by the second-level distributor; according to the need, additional third-level, fourth-level, fifth-level… multi-level distributors can be added, thus forming a single-line progressive oil path, which can supply lubricating grease to hundreds of lubrication points.
Roller screen single-line centralized lubrication system
(1) “Point-to-point” lubrication: Each distributor corresponds to one or several lubrication points, and each distributor is independent. It can be adjusted individually for the flow rate of each distributor or monitored separately according to the needs of the lubrication points;
(2) Only one main oil supply pipeline is required, the piping is simple, the cost is low, and the lubrication system can be increased or reduced as needed;
(3) Generally, a lubrication pump injects lubricating grease into the main pipeline and distributes it evenly to each lubrication point through the distributors;
(4) In all lubrication points, if a blockage occurs at any one point, an alarm can be triggered through various types of signal devices. Therefore, monitoring the operation of just one master distributor can achieve monitoring of the entire system;
(5) For complex structures, difficult-to-remove, and important lubrication points, automatic refilling can be achieved to reduce the labor intensity of workers.
Modification of the Roller Screen Bearing Housing
The traditional bearing housing has its oil injection points located above the housing. Oil cups or connectors are installed to facilitate oil injection. If the pipelines are installed on the sealing cover of the bearing housing or on the side plate of the roller screen, although it is convenient for connection, if the roller screen malfunctions or undergoes maintenance or component replacement, the sealing cover and the side plate must be removed, which causes a lot of trouble and increases the workload. Moreover, the lower part of the roller screen is fixed and cannot be disassembled. Therefore, the lubrication system pipelines should be arranged at the lower part of the roller screen.
In the design of the bearing housing, in addition to retaining the original oil injection ports above, there are also oil injection ports designed at the bottom of the bearing housing. The upper oil injection port is a backup port and can be manually injected with oil. The lower part is equipped with a pipe connector to connect the lubrication system.
Problems to be noted in the centralized lubrication system
(1) Before formal use, it is essential to remove air from the system. Because air entering the system will not only cause the lubricating grease to deteriorate and generate noise, but also cause cavitation on the metal surfaces of the lubrication points. Therefore, ensure the good sealing of the system to prevent dust and air from entering.
(2) Strictly ensure the cleanliness of the pipelines and that the grease added to the storage tank is free of impurities. This is to prevent wear of the piston in the pump, blockage of the filter, and jamming of the distributor. The filter element should be inspected and cleaned regularly to avoid blockage and jamming of the distributor; in dusty, humid, and harsh environments, the distributor should be equipped with a protective cover.
(3) Do not mix lubricating greases of different brands or models. Because different lubricating greases may undergo chemical reactions, damaging the components of the lubrication pump and causing damage to the lubrication pump.
(4) All lubrication pipelines must be filled with lubricating grease before installation (especially the branch pipelines), ensuring that they can provide timely lubrication after the system is running. If the lubrication equipment is not used for a long time, the lubricating pump and all pipelines should be cleaned of the lubricating grease to avoid affecting the normal operation of the system due to deteriorated lubricating grease. The viscosity, rust prevention, oxidation resistance, and defoaming properties of the lubricating grease decrease, and insoluble components such as oil residues and resinous substances are produced, which will affect the system performance.
(5) Regularly check all lubrication points and replace deteriorated lubricating grease in time. Regularly check all lubrication points to see if new lubricating grease appears or if there is any lubricating grease. If there is no lubricating grease, it indicates a fault, and the fault should be checked and eliminated before continuing to use.
(6) The oil pump should be kept clean to prevent dirt from entering the oil storage tank to ensure the normal operation of the oil pump; when adding oil to the oil storage tank, it must be added from the filling port, filtered, and then enter the oil storage tank, and the filter screen should be cleaned regularly.
Conclusion
The centralized lubrication oil injection is applied to the Roller screen, achieving excellent results. It reduces the maintenance time for the roller screen bearings, lowers the labor intensity of workers, improves work efficiency, increases the maintenance time for other components of the roller screen, and effectively reduces the wear between various rotating elements. The centralized lubrication operation is simple, has high safety, no pollution, high cleanliness, and high lubrication quality.
