Key tips: the main measures to control the pollution of hydraulic oil: (1) the viscosity of the oil is reduced, the oil film destruction of the active part and the friction resistance increase, causing the system heating and the crawling of the actuator (such as the hydraulic cylinder). The decrease of oil viscosity can lead to an increase in leakage and a significant reduction in the efficiency of the system.
In order to ensure that the hydraulic system works normally, reliably, reduce faults and prolong life, effective measures must be taken to control oil pollution.
1. Control the temperature of oil
High oil temperature often brings the following adverse effects to the hydraulic system.
(1) the viscosity of the oil decreases, which causes the oil film damage and frictional resistance of the active parts to increase, causing the system to generate heat and the executive elements (such as hydraulic cylinders) to crawl. The decrease of oil viscosity can lead to an increase in leakage and a significant reduction in the efficiency of the system.
(2) when the viscosity of the oil decreases, the characteristics of the throttle will change, which will make the piston speed unstable.
(3) the high oil temperature causes the thermal expansion of the machine parts, which makes the clearance between the movement pairs change, resulting in the inactivity or the card death, and reduces the performance and precision of the work.
(4) when the oil temperature exceeds 55 degrees Celsius, the oil oxidation is aggravated and the service life shortens. According to the data, the service life of oil is shortened by half when the temperature exceeds 55 degrees Celsius, and the service life of oil is shortened by half. Therefore, the machines for different uses and different working conditions are used. There should be different allowable working temperature. The normal working temperature of the hydraulic system of construction machinery is 35-55 degrees Celsius, the highest is 70 degrees Celsius.
2. Control the precision of filtering
In order to control the contamination degree of oil, according to the different requirements of the system and components, the oil filter is set up in the oil suction port, pressure pipeline and servo speed valve, in order to control the particulate pollutants in the liquid, so that the performance of the hydraulic system can be depended and work stable. The filtering accuracy of oil filters is generally selected according to the components with the greatest sensitivity to filtering accuracy in the system.
3. Strengthen the maintenance and management of the field
Strengthening site maintenance management is an effective measure to prevent external contaminants from invading the system and filtering pollutants in the system.
(1) check the cleanliness of oil
When the equipment management department inspecting the cleanliness of the equipment, the cleanliness of the oil, oil tank and oil filter should be checked at the same time, and the three grading system of the cleanliness of the hydraulic equipment should be set up. The hydraulic system for the key equipment should be checked.
(2) establishing the first level maintenance system of the hydraulic system
The equipment management department should increase the specific maintenance contents of the hydraulic device when formulating the maintenance contents at the first level.
(3) regular sampling and testing of oil liquid
The oil sample should be extracted regularly and quantitatively, and the size and quantity of the impurity particles in the unit volume oil sample or weight should be checked, and the qualitative and quantitative analysis should be made in order to determine whether the oil needs to be replaced.
A, oil sampling time: the hydraulic equipment that has stipulated the oil exchange cycle can sample the oil that is being used one week before the oil change; the new oil liquid should be sampled after continuous work of 1000h; the oil used in the large precision hydraulic equipment in the enterprise should be sampled after the use of 600H.
B, when taking oil samples, first of all, clean up the oil containers, and do not allow dirty containers to ensure accurate data.
When the hydraulic system is not working (in the state of rest), the same quantity of oil can be taken in the upper, middle and lower parts of the tank, and the test can be carried out after mixing. When the hydraulic system is working, the oil sample can be taken at the total back of the oil pipe in the system; the number of oil samples required for the laboratory is generally 300-500mL/ times; Laboratory tests are carried out to fill in the test results and store the equipment files.
4. Regular cleaning
Another effective way to control oil contamination is to remove filters, filter cartridges, fuel tanks, oil pipes and internal fouling regularly. In assembling and disassembling components and tubing, attention should also be paid to cleaning. All oil ports must be sealed with plugs or plastic sheets to prevent dirt from intruding into the system.
5. Filter oil regularly and control the duration of its use
The life or replacement period of the oil is dependent on a number of factors, including the environmental conditions and maintenance of the equipment, the filtration accuracy of the hydraulic system oil, and the allowable pollution level. Oil, water, dust, metal wear and so on will make the oil liquid into mixed liquid containing a variety of pollutants. If it is not changed in time, it will affect the normal work of the system and cause the accident.
Filtration is an important means to control oil contamination. It is a method to compel impurity particles in oil. After multiple forced filtration of oil, the impurity particles can be controlled within the required range, so the precision of the forced filtration oil should be made to all kinds of hydraulic equipment to ensure the cleanliness of the oil.
Whether the oil change depends on the degree of contamination of the oil, there are 3 ways to determine the oil changing period.
(1) visual oil exchange method. It is based on the experience of the maintenance personnel, according to the regular changes in some oil liquid (such as oil black, stinky, milk white, etc.), decide whether to change the oil.
(2) regular oil transfer. According to the environmental conditions, working conditions of the equipment and the oil changing cycle of the used oil 名媛直播, they will be replaced at the expiration date. This method is applicable to enterprises with more hydraulic equipment.
(3) sampling method. The oil is sampled and tested regularly to determine the necessary items (such as viscosity, acid value, moisture, particle size and content as well as corrosion) and to compare the actual measurement value of the oil quality to the standard oil degradation standard and determine that the oil should not be changed. Sampling time: the hydraulic system for general engineering machinery should be carried out one week before the oil exchange period. The hydraulic system of key equipment (such as TBM full section boring machine, etc.) should be sampled every 500 hours and the test results should be filled in the equipment technical file. Sampling and testing methods are applicable to key equipment and large hydraulic equipment.
When changing the oil, we must pay attention to cleanliness and prevent the stolen goods from invading the hydraulic system.
The replacement of the new oil or the added new oil must be the oil used in this system. After testing, it is confirmed that the oil quality has reached the specified performance index and can be added.
In order to keep the new oil clean, replace the old oil inside the main tank and the main tank, and clean the oil tank, filter screen and hose. When oil is refueling, the oil must be filtered to replace the worn and damaged strainer.
The amount of oil added to the oil tank of the oil mark position, refueling method is: first refueling to the oil tank top oil line, the oil pump motor, the oil supply to the system pipes, oil to the oil tank line, and then start the motor, so many times, until the oil is kept in the oil line.
