Created on:2022-01-12 14:24

Clean all components of the hydraulic system before assembly

Clean all components of the hydraulic system before assembly

From the perspective of use, the primary condition for the normal operation of the hydraulic system is that the interior of the system must be clean. Before the operation of a new equipment or after an overhaul of an equipment, it is inevitable that the hydraulic system will be polluted. Although the hydraulic components pay great attention to the internal cleaning of the components, the new components may still contain pollutants such as burrs, cutting, flash, dust, welding slag and paint. Components may also be contaminated due to poor storage and handling. Rust, paint chips and dust may accumulate during the production of the oil tank. Although the oil tank is cleaned before use, many pollutants are difficult to see with the naked eye. During the installation of hoses, pipes and pipe joints, it is possible to bring pollutants into the system. Even new fluids contain some unexpected contaminants. Measures must be taken to filter out the pollutants as soon as possible, otherwise faults may occur soon after the equipment is put into operation, and the early faults are often very serious, and some components such as pumps and motors may be fatally damaged. The purpose of component cleaning and system flushing is to eliminate or minimize the early failure of the equipment. The goal of flushing is to improve the cleanliness of oil and keep it within the pollution tolerance of key hydraulic components in the system, so as to ensure the working reliability of hydraulic system and the service life of components.

Clean all components of the hydraulic system before assembly

After every process link of the processing, assembly and maintenance of hydraulic components, pollutants will inevitably remain. After the components whose cleanliness does not meet the requirements are installed into the system, under the action of system oil scouring and mechanical vibration, the inherent pollutants in the components will fall off from the adhered surface and enter the oil, causing additional pollution to the system. Therefore, cleaning measures must be taken before the components are assembled into the system to make the components meet the required cleanliness.

The common cleaning methods include immersion cleaning, motor scrubbing, ultrasonic cleaning, heating volatile matter and acid treatment. When in use, these methods can also be combined or cleaned in multiple steps, and cleaned in two or three adjacent cleaning tanks (machines) in turn. Due to the different cleaning pollution degree of each cleaning tank (machine), the formula and heating temperature of the "cleaning solution" are also different.

Solvent immersion cleaning is to immerse the cleaned parts into the cleaning tank with heating equipment (heating temperature is generally 35 ~ 85 ℃), and pass compressed air or steam into the cleaning solution to make the cleaning solution in dynamic state. The immersion time is 4 ~ 8h. For parts with serious oil contamination, manual wiping is also required during cleaning.

Motor scrubbing can use a soft brush to remove dirt to maintain the accuracy and low roughness of the components. For example, the mesh filter often uses a hard wire brush, which sometimes damages the filter element or changes the filtering accuracy. For the hydraulic valve body with high precision and low roughness, nylon pricking brush with abrasive ball is used to wash the end of the valve hole, the junction of the hole and the sinking groove. The brush head of the nylon prick removal brush is bonded by black nylon wire with a diameter of 0.3 ~ 0.6mm and green silicon carbide abrasive with a specification of M20.

Ultrasonic cleaning is to use the ultrasonic of appropriate power to shoot into the cleaning fluid to form a point like micro cavity. When the cavity expands to a certain extent, it suddenly bursts and forms a local vacuum. The surrounding fluid fills the vacuum at a high speed. The instantaneous pressure reaches thousands of atmospheres, with strong sound pressure and mechanical impact (i.e. cavitation), Peel off the contaminants on the surface of the parts placed in the cleaning solution. This method has the advantages of short cleaning time and good cleaning quality. It can also clean the parts with complex shape that cannot be cleaned by manual fork. Compared with manual work, the work efficiency is increased by more than 10 times and the cost is reduced. However, the filter has porous materials and can absorb sound waves, which may affect the cleaning effect.

The heating volatilization method is applicable to the treatment of some special pollutants, that is, substances that can volatilize after heating. At the same time, this method can not remove the residual carbon, ash and solid attachments in the hydraulic components.

The acid treatment method is to immerse the part surface in the solution with CrO3, H2SO4 and H2O after removing the pollutants, so as to produce a corrosion-resistant film on the surface. Different pickling solutions are used for different metal materials.

According to the rule that the cleanliness of system components is determined by the wetted indication area of the system, the focus of cleaning is the components with high total wetted indication area of the system. Therefore, the main objects of cleaning are hoses, oil pipes, hydraulic cylinders, filters, oil tanks and other components. The pumps and valves have been fully cleaned before leaving the factory, which has little impact on the pollution of the system.

The practice of most factories is: before assembly, the hard pipe shall be pickled, washed with water, dried and degreased; Hoses, joints and purchased components shall be dried after being cleaned with kerosene or gasoline.

The hose must be connected to the actuator after the pipeline is pickled and washed, and it shall be blown clean with clean compressed air before installation. If the hose is removed halfway, the hose connector shall be wrapped in time.

The joint body shall be cleaned with kerosene and dried with clean compressed air before installation. It is also necessary to seal the joint body with the raw material belt, and pay attention to two points when winding the raw material belt; Winding along the thread direction; The wrapped raw material belt shall have a thread length of 2-3 buckles from the end of the thread, otherwise the excess part will enter the system due to being cut off during tightening.

Before pipeline installation, large particle impurities inside shall be removed, and stones, rags and other sundries shall not be left in the pipeline. If the pipeline installation is interrupted for a long time, the pipe orifice shall be closed in time to prevent sundries from entering the system. In order to prevent the invasion of welding slag and iron oxide scale, it is recommended to adopt gas shielded welding such as argon arc welding for pipeline welding.

The hydraulic cylinder is installed in a separate pre cleaning oil tank system for cyclic impact cleaning with pre cleaning oil. The amount of oil required is at least 5 times of the capacity of the hydraulic cylinder. Generally, it can be cleaned after 5 times of repeated flushing.

After all parts are cleaned, put them into a clean site that is closed and easy to clean and keep clean. The air in the site should be filtered, and the air pressure in the site should be higher than the external air pressure to prevent the invasion of external dust.

During the transportation of hydraulic components and components, attention should be paid to dust and rain prevention. The hydraulic parts for long-distance transportation, especially those transported by sea, must be packaged with rainproof paper or plastic and put an appropriate amount of desiccant.

Home    Article    Clean all components of the hydraulic system before assembly