Repair method of electromagnetic reversing valve

Common faults of valve core: the valve is not sensitive or has no action, vibration and noise, the valve core is stuck, the contact between the valve core and the valve body is poor, and the sealing is not strict, etc

Causes of failure: excessive fit clearance caused by wear, cavitation and other factors, leakage of hydraulic system and deposition of hydraulic oil precipitate, resulting in abnormal operation or clamping of solenoid directional valve spool

1. Repair of valve core

Cleaning of electromagnetic reversing valve

Disassembly and cleaning is a basic repair method for the maintenance of the electromagnetic directional valve. For the electromagnetic directional valve fault caused by oil pollution or granular impurities in the hydraulic oil, the disassembly and cleaning can generally eliminate the fault and restore the function of the electromagnetic directional valve

(1) disassembly: the parts of the solenoid directional valve are mostly connected by bolts, which are not

It is difficult, but it should be noted that it is not allowed to knock or use sharp tools to depict, so as to avoid damaging the mating surface of the valve.

(2) cleaning: check the dirt deposition of valve body, valve core and other parts, and put the valve body, valve core and other parts in a clean cleaning box and soak them with washing gasoline or kerosene. On the premise of not damaging the working surface, clean the dirt with clean cloth and silk. For the dirt with long deposition time and firm adhesion, it can be cleaned with non-metallic scraper to avoid scratching the mating surface.

(3) fine cleaning: use the cleaning oil absorbed by the leather bag to clean. The cleaned parts can be dried with compressed air; if there is no condition, they can also be dried naturally. Do not use cotton yarn to wipe, so as not to stick dust or fiber and other pollutants on the parts. Keep properly after drying to avoid rusting or re contamination

(4) assembly: assemble according to the assembly diagram of electromagnetic directional valve or the assembly relationship of parts recorded during disassembly. The original seal has been deformed in order to compensate the seal clearance in use, so it should be replaced with a new one during assembly

2. Parts grinding and repair

When the failure of the valve is caused by the matching accuracy not meeting the requirements, disassemble and clean the valve first, check and measure all parts. The matching hole of the valve body shall be measured with the inner diameter dial indicator, and the measurement data shall be accurate to 0.01mm. The valve core mainly detects the matching surface with the valve body, and the measurement data shall be accurate to 0.01mm with the outer diameter dial indicator. If the valve core and the valve body are evenly worn, and the working surface is not seriously scratched or partially severely worn, the valve body mating hole shall be grinded first, and the valve core shall be grinded according to the size of the grinded valve core, so as to reach a reasonable fit clearance for reassembly. The fit clearance is generally 0.005-0.008mm

3. Grinding of valve body mating hole

For the valve body of the failed solenoid directional valve, if the working surface of the valve body mating hole is not seriously scratched or partially severely worn, it can be grinded and repaired. The method is to use a cast iron rod, make it into the valve body matching hole size as the grinding rod, and then evenly apply the grinding paste (carborundum) on the grinding rod, and repeatedly grind to meet the repair requirements. The valve body mating hole finish is generally Ra0.4

4. Grinding of spool valve element

The processing precision of the valve element is high and the material is hard, so it can not be processed by itself. If there is a failure valve of the same model, we can select a working surface without wear through measurement, and can grind the valve core matching with the valve body to form a valve that can be used. If we can't find this kind of valve core, we can also use the original valve core for electroplating to compensate the surface thickness. After that, according to the size of the matching hole of the valve body, the valve core is finely ground to the matching size with an external grinder, and then it is ground.