According to the investigation and analysis, it is concluded that the common failure forms of the large-scale pump guide bearings, and also analyzes the causes of these faults, and finds out how to choose the guide bearing and how to improve its reliability and durability according to the cause analysis. Enhance the sealing of metal oil lubrication bearings, the ability to drain water leakage increased, the pipe-type structure device used in non-metallic plain bearings, change pump units, design and manufacture of reasonable inlet flow, reasonable construction mode and correct installation mode, reduce the load on the guide bearing, can improve the reliability and durability of large-scale pump guide bearing.
There rotatable portion of the device receiving the pump and a balance wheel radial force acting in the cycle of rotation of the pump is large guide bearing, which is the main component of large pumps. With large pumps through a guide bearing, guide vane located inside the hub, a vertical common shape, there are two such large pumps, respectively, and non-metallic bearing babbitt bearing. If the guide bearing wear very large or have been severely damaged, it will not only cause large swings axis unit, severe vibration, but also lead to the occurrence of blade shell collision accident. Studies have shown that when the pump is running, many of which are due to the failure of the guide bearing failure caused. Seen in this light, pump reliability, running the length of time there are maintenance time and associated guide bearing.
2 Pump guide bearing characteristics and requirements of
2.1 guide bearing characteristics
generally non actual state, in the vertical pump assembly unit of work, the force on a balancing force in the radial direction, i.e. force is zero, the vertical pump guide load bearing likewise suffered zero . But usually because the design and manufacture of certain construction and installation errors caused by structural or unforeseen problems, then the effect will be the respective guide bearing portion of the radial force. Horizontal or inclined pump assembly, by a radial guide bearing member and the moving force own weight. Bearings are often placed underwater pressure, for guiding the bearing lubrication oil or water, which must be subjected to a good guide bearing wear, lubrication is possible in the case, installed on the respective sealing and drainage water leaking parts, this device can be prevented from flowing into the mixing water pump bearing. These hybrid water contains sediment, the sediment entering the lubricant inside the bearing, lubrication failure, bearing damage, and there is no cause in the short term bearing the desired effect.
2.2 Bearing Selection guide
Oil lubricated guide bearing metal typically comprising a set of horizontal pump case, and a tubular pump swash pump, using the guide bearing means must be sealed by a water-fly. When the selected unit time is not long, pure water can be lubricated guide bearing elastic metal. Sized pump impeller diameter not larger than 2.1m, it is preferable to use a non-metallic water lubricated guide bearing. High purity water can be selected within the water lubrication pump containing more impurities of the opposite water, should be used and the structure of the protective pipeline, to ensure the debris out of the bearing. The pump impeller diameter not less than 3.1m, it is necessary to use a metal oil-lubricated bearings; and its water seal must ensure a reliable seal.
2.3 guide bearing requirements
required pump guide bearing must have good reliability and durability. If the performance guide bearing is changed, in most cases is part of the pump with radial discontinuity zero rotation, the bearing structure is changed, the material selection is not a good lubricating condition is destroyed and other factors are related. Under certain operating conditions and are within the operating time, the bearing will not occur because of accidental damage or a failure occurs stop nature of the work, which is called guide bearing reliability, the reliability is also required of the respective bearing has a reasonable load-bearing capacity, good reliability of the leak-sealing means. Journal bearing material and will run along with the corresponding guide bearing wear occurs, of which there are some non-metallic materials will gradually harden, crack and other aging phenomenon.
Oil lubricated guide bearing metal 3 and its sealing means
using dilute oil-lubricated bearing babbitt cartridge using a sealing apparatus sealing and leakage discharge, in order to prevent the water pump is not entering the bearing. In general the bearing structure and comprises a helical slot Pitot type.
3.1 spiral trough guide bearing
spiral trough guide bearings are generally working oil basin, the main bearing, fixed oil basin and return tubing components. Work, the lubricating oil to the above movement, the working oil from the bowl out from below, through the aperture below the bearing body, by the aperture into the annular oil groove, rotation of the shaft journal 60 of the screw-like oil grooves 6 from the inner bearing surface to flow toward the top of the lubricating oil during the flow, it played a role of bearing lubrication. The remaining oil into the upper fixed oil basin, against its own gravity, the tubing is rotated back into the oil basin below, the formation of such a cycle, long cycle work.
3.2 Pitot bearing guide type
composition formula Pitot guide bearing and guide bearing almost spiral trough, there is a corresponding oil basin oil basin body does not move and the upper bearing, but the helical trough guide bearing lubricating oil except that circulation direction is reversed. Start from a lower portion of the lubricating oil of formula Pitot guide bearing, rotation of the upper portion of pressure to flow completion hosted fixed oil basin, relying on its own gravity back to a lower portion of the working oil basin, the working cycle, the oil bodies in motion process to lubricate the bearings.
3.3 the bearing seal
oil bearing positioned guide vanes hub which, for preventing water from the pump flows into the bearing, and the upper portion of the guide vanes is also provided with the protective tube a stationary, the protective tube extends into the pump elbow , the use of static sealing means between the protective tube and the elbow, to let the pump shaft and the inner lumen and not in contact with water . At the lower portion of the intermediate shaft and the impeller hub or the sealing means of the movement of the water. There are two forms of sealing. After sealing, the lower portion of the guide vane hub lumen of a small amount of leakage should be promptly discharged from the drain pump in vitro scoops, to avoid the water level rises to the upper bearing cover.
3.4 Babbit oil lubricated guide bearing characteristics
Babbit oil lubricated guide bearings have to withstand large load capacity, stable performance, the material has good wear and aging problems without merit, therefore, with good durability. But below the surface portion of the sealing leakage often increase rapidly, the submerged guide bearing, the bearing lubrication oil is destroyed, and the journal bearing damage and failure, which is one of its major drawbacks, and therefore has poor reliability. Through research, most large oil pump bearings are more or less the situation after flooding damage occurs, some 10 years took place more than 19 times. Cause seal leakage invade guide bearing has two aspects: one is the guide bearing long working hours, no check in the horizontal pipe has accumulated a lot of sediment, the pipeline is blocked, drainage will be greatly affected. The examination revealed that it is detached, the pump operation after some 34 years, deposition in the drainage guide bearing sediment accounted 2/34/5 cross pipe cross section; the other hand is easy to lose the water seal effect, increases the amount of leakage , drainage pipes than the capacity (in particular the sediment deposition) strong, it will cause the hub body cavity in the vane wheel accumulate large amounts of leakage, cover guide bearing .
(1) Large-scale pilot pump bearings is the most critical components, the bearing generally good reliability, durability resistance properties. Guide bearing is damaged, the pump will be a problem.
There is (2) a large water pump guide bearing these questions: a metal is to be submerged oil-lubricated bearings will be a large degree of damage; non-metallic bearing bearing wear is very bad.
Impeller diameter (3) and vertical pumps about 2.0m or less, and generally should be selected in a non-metallic water lubricated guide bearing. Water lubricated mainly used when pumping sediment large body of water, mainly to protect the structure of the tube to ensure that sediment can not enter the bearing. The pump impeller diameter not less than 3.1m, it is necessary to use a metal oil-lubricated bearings.
(4) arranged reasonable drainage seal leaking pipes, the rational design of a non-metallic water-lubricated guide bearing, the sealing performance of the metal corresponding increase in oil lubricated guide bearing, guide bearing as well as to reduce the loads, which can improve the well pump guide bearing reliability and durability.
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