The working temperature of the hydraulic system of the shield machine is usually 30~55 ℃. At this time, the viscosity, lubrication and wear resistance of the oil are the best, and the efficiency of the hydraulic system is the highest. When the system temperature exceeds 65 ℃, the viscosity of the oil drops significantly, which will lead to increased system leakage, damage to the sliding oil film of components such as the reversing valve, and increase the wear of components, leading to a faster rise in system temperature. When the oil temperature reaches above 80 ℃, the operating state of the components will change abnormally, and even the phenomenon of "jamming" may occur, affecting the normal operation of the system.
The service life of shield machine hydraulic system is not only related to the performance of hydraulic equipment, but also to the viscosity and cleanliness of hydraulic oil in hydraulic equipment. In order to ensure the use of its functions and the normal and reliable operation of the hydraulic system, it is necessary to control the hydraulic oil pollution. Here are some control points:
1. Control the operating temperature: the operating temperature shall be detected in real time to monitor the temperature higher than the index. The ambient temperature of shield fluid operation is generally high, and the viscosity of grease will decrease with the temperature, resulting in a great decline in the efficiency of machinery and the performance of machinery. Too low temperature will also have a considerable impact on the oil absorption resistance, which will produce noise. The oil temperature is controlled through the temperature control of the circulating cooling water inside and outside the shield. 2. Guarantee of cleanliness during use: During the assembly and commissioning of shield fluid, all hydraulic valve blocks and other components shall be cleaned as necessary and tested to be qualified. After the oil tank and pipeline are contaminated with dust, iron chipping, welding slag and other pollutants, conduct pickling and polishing and other treatment processes; During the construction, samples shall be taken regularly to determine the treatment scheme through technical analysis. 3. Renewal of grease: In the process of use, it is necessary to replace the contaminated grease. Sampling data analysis is required, appearance observation is conducted, and the laboratory determines its indicators. Through a series of data analysis such as viscosity and water content, it is necessary to decide whether to replace the hydraulic oil. For replacement, the old oil shall be drained and the equipment shall be cleaned before adding qualified oil. 4. Real time detection of service conditions: During the operation, online particle monitoring is adopted, and relevant equipment is used for monitoring. The oil quality can be obviously detected. Through data analysis and processing, when the pollution reaches a certain level, the alarm system will give an alarm. If necessary, it will be replaced to ensure that the equipment works under normal data parameters.
