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Bearing bush is one of the most important parts in the compressor, in the heart of the compressor, because the bearing bush bears a lot of alternating load, uneven force, impact force, it is easy to damage.
Bearing bush is one of the most important parts in the compressor, in the heart of the compressor, because the bearing bush bears a lot of alternating load, uneven force, impact force, it is easy to damage.
The common faults of bearing bush are burning tile, alloy shedding and cracking, bearing bush abrasion and severe wear. Attention to bearing bush lubrication maintenance, lubricating oil selection, bearing bush installation clearance adjustment is an effective method to reduce bearing bush failure. In order to ensure the long-term stable operation of the compressor, correct diagnosis and maintenance of bearing bush faults is one of the important links to maintain the compressor.
Failure analysis
Generally, there is no lubricating oil between the bearing bush and the crankshaft neck, insufficient lubricating oil or other reasons, and no lubricating oil film is formed or the lubricating oil film is destroyed. There are several reasons that may lead to burning tiles:
1.The lubricating oil in the lubrication system is seriously insufficient
When lubricating oil is seriously insufficient, the temperature of the friction surface of crankshaft journal and bearing bush will rise rapidly and burn tile will occur. The main reasons for the serious shortage of lubricating oil are: serious blockage of lubricating oil filter, blockage of oil pipeline or serious oil leakage, damage of oil pump, rupture of oil pipe joint or failure to add lubricating oil in time.
2.The assembly clearance of crankshaft journal and bearing bush does not meet the requirements
The gap affects the formation of lubricating oil film. If the gap is too small, the oil is not easy to enter the friction surface between the journal and the bearing bush, and the lubricating oil film cannot be formed. If the gap is too large, the thickness of the lubricating oil film is reduced, the friction surface can not be completely separated, the possibility of burning tile will increase. At the same time, too large clearance will also increase the vibration and impact of crankshaft journal and bearing bush, leading to the rupture of lubricant film.
3.the grinding repair of the crankshaft damaged the journal surface wear resistance layer and fatigue resistance layer
Crankshaft journal generally through good heat treatment, with high wear resistance layer and fatigue resistance layer, if the crankshaft grinding repair after the occurrence of tile failure, the crankshaft will lose the original high wear resistance layer and fatigue resistance layer, so that the occurrence of tile failure quickly.
4.Oil deterioration
If the lubricating oil is not pure or the lubricating oil is deteriorated due to the use of too long and other reasons, the lubricating oil film is not easy to form, so that the occurrence of tile failure.
Bearing bush alloy peeling and cracking
The friction surface of crankshaft journal and bearing bush without oil film isolation, will be more frequent direct contact, the microscopic raised part of the crankshaft journal and bearing bush under the action of mutual movement will produce fatigue cracks, and oil infiltration cracks will produce hydraulic effect, accelerate the crack expansion, resulting in alloy particles from the surface of the bearing bush faster.
The direct contact of friction surface leads to the increase of bearing bush temperature and the decrease of fatigue strength of bearing bush alloy layer, which further accelerates the generation and shedding of cracks in bearing bush alloy. Bearing bush alloy shedding will lead to the increase of crankshaft journal and bearing bush clearance, oil pressure drop and abnormal sound.
Busbar scrape
Generally in the case of instantaneous lack of oil between bearing bush and shaft neck or instantaneous rupture of lubricating oil film, bearing bush abrasion occurs, which is characterized by the appearance of scratch marks on the surface of bearing bush and shaft neck. In general, severe wear of bearing bush occurs in the case of repeated instantaneous lack of oil.
Phenomena and exclusions
In the operation of the air compressor, the burning tile and the connecting rod big Babbitt layer are burned or shed, which increases the temperature of the bearing bush, produces high temperature ablative and Babbitt alloy melting.
Burning tile symptoms: bearing temperature is high, current is large, compressor noise is large.
Troubleshooting: oil change, scraping, bushing change.
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