There are many possible failures in the hydraulic system. Most of the failures during use are caused by improper selection of oil, contaminated oil, air entering the system, and excessive oil temperature. The following analyzes several issues that should be paid special attention to in the daily maintenance and management of anchor rigs:
1. The selection of hydraulic system oil. Generally speaking, hydraulic oil should meet the following requirements: it must not contain steam, air and other impurities that are easy to vaporize and produce vaporization; it has good lubrication performance and high liquid film, high degree of chemical stability, suitable viscosity and good viscosity-temperature performance. The hydraulic oil of anchor rig is recommended to use blue or thick hydraulic oil. If the source is difficult, use 30# industrial machinery oil in summer and 20# mechanical oil in winter.
2. The hazards of hydraulic system oil pollution and preventive measures Hydraulic system pollution is a major cause of hydraulic failure. Contaminants mixed into the system will accelerate the wear, wear, burn, and even damage of the hydraulic parts, or cause the valve to malfunction or cause noise. Contaminants can block the orifices or throttle gaps of hydraulic components, change the working performance of the hydraulic system, cause movement disorders or even complete failure, and cause malfunctions and accidents. Dust particles in the hydraulic cylinder will accelerate the damage of the seals, and the strain on the inner surface of the cylinder will increase the leakage, insufficient thrust or unstable movement, crawling, slowing of speed, and abnormal sound and vibration.
It may also cause the filter screen to be clogged, the hydraulic pump is difficult to suck oil, and the oil return is not smooth, resulting in cavitation, vibration and noise. Therefore, management must be strengthened to prevent oil contamination and ensure the safe and reliable operation of the hydraulic system.
The hazards of oil pollution to the hydraulic system: block hydraulic components, such as the matching gap between the relative moving parts of pumps and valve components, block the throttle holes, damping holes and valve ports in the hydraulic components, and make the components unable to work normally. Dirt enters the matching gap between the relative moving parts of the hydraulic component, which will scratch the mating surface, destroy the accuracy and surface roughness of the mating surface, accelerate wear, increase component leakage, and sometimes cause the valve core to jam, causing the component to move unsuccessfully. Over dirt in the oil causes the oil pump to suck oil.
(1) The oil filter screen is blocked, causing excessive oil suction resistance, causing the oil pump to not work normally, causing noise and vibration; dirt in the oil will deteriorate the oil. Moisture mixed in the oil will emulsify the oil, reduce the oil's lubricating performance, increase the acid value of the oil, shorten the service life of the components and increase leakage.
(2) Measures to prevent oil contamination. Many of the common faults in hydraulic systems are caused by dirty oil. Therefore, keeping the oil clean is an important aspect of maintaining hydraulic equipment. The measures to prevent oil contamination are as follows: the area around the oil tank should be kept clean, and the oil tank should be covered and sealed; the oil in the oil tank should be replaced regularly, and the oil should generally be changed after 1000 hours of cumulative work. When filling oil, you should pass a filter above 120 mesh; check and clean the filter regularly; clean the hydraulic components with kerosene regularly and unblock the pipeline; regularly check the pipe joints and sealing devices between the pipeline and the components.
3. The hazards and preventive measures of air entering the hydraulic system. The compressibility of the oil used in the hydraulic system is very small, but the compressibility of low-pressure air is very large, about 10,000 times that of the oil, even if the system contains a small amount of air, It also has a great impact and can cause system failures.
(1) The hazard of air entering the hydraulic system. The hydraulic pressure generates noise, and the air dissolved in the oil will escape from the oil when the pressure is low, generating bubbles and forming cavitation; in the high pressure area, under the impact of the pressure oil, the bubble skin is broken and rises sharply, which makes the system produce noise. When the gasification in the oil is rapidly pressurized, a large amount of heat will be released, causing local overheating and damaging the hydraulic components and hydraulic oil. The air in the oil is highly compressible, causing the working components to crawl and vibrate, which destroys the stability of the work. A large number of air bubbles mixed in the oil will deteriorate the oil, reduce the service life of the oil, and increase the wear of the components.
(2) Measures to prevent air from entering the hydraulic system. According to the different reasons why air enters the hydraulic system, pay attention to the following points in use and maintenance. Check the oil level in the oil tank frequently, and keep enough oil in the oil tank.
4. Maintain from the appearance, such as whether the joints are loose, whether there is oil leakage, whether there are cracks in the pipeline, etc. And you have to check before starting the pump, such as whether the oil is added according to the regulations, and whether the oil temperature is normal. Operate for more than 20 minutes under load (especially in winter); pump start and check after start, when the pump is started, the method of start and stop shall be used to start to increase the oil temperature, so that the running device can operate flexibly before entering normal use. After the pump is started, check whether there are any undesirable phenomena such as cavitation, overheating, and air bubbles.