Views: 458 Author: Site Editor Publish Time: 2021-06-11 Origin: Site
⒈The hydraulic oil is not clean and the contaminants are deposited causing the hydraulic valve spool to be stuck or act out of order.
⒉The hydraulic valve has been used for a long time. Due to wear, cavitation and other factors caused by the fit gap is too large, the internal leakage increases.
⒊The manufacturer's congenital quality problems.
When What are the general methods of repairing hydraulic valves?a hydraulic valve fails or malfunctions, most companies use a new component to restore the function of the hydraulic system, and the failed hydraulic valve becomes scrap. In fact, most parts of these hydraulic valves are still in good condition and can be partially repaired to restore function.
Correct maintenance of hydraulic valves can save acquisition costs. When replacing hydraulic valves, such as no spare parts, it takes a long time to order, and some imported valves are even difficult to buy, so the equipment may be shut down for a long time, while the repair can restore the operation of the equipment and even the entire production line, the economic benefits are considerable.
⒈Slide valve components of the spool and valve bore: when the two with clearance than the product drawings specify the assembly clearance value increased by 20% ~ 25%, the spool must be taken to increase the size of the method after the repair with research.
⒉Cone valve components of the spool and the valve seat: when the conical seat valve sealing surface contact is poor, because the cone valve can automatically compensate for the gap under the action of the elastic treasure, therefore, only need to grind repair.
⒊Valve components such as jamming, hair pulling, grooving, etc. should be repaired.
⒋Repair of pressure-regulating poppets.
⒌Replacement of seals, etc.
In the practice of hydraulic valve repair, the common repair methods are hydraulic valve cleaning, parts combination optional, repair size and restore accuracy.
Because 70% of the failures come from unclean oil, thus making the valve components are not clean inside, so disassembly and cleaning is one of the repair methods.
For the hydraulic oil pollution caused by oil deposits, or hydraulic oil in the granular impurities caused by the hydraulic valve spool stuck and other failures, generally by disassembly cleaning can be excluded, to restore the function of the hydraulic valve. Common cleaning processes include.
⒈Check and clean: remove the hydraulic valve surface dirt: use brushes, non-metallic scrapers, silk cloth to remove the hydraulic valve surface adhesion firm dirt, take care not to damage the hydraulic valve surface. In particular, do not scratch the mounting surface of the plate valve.
⒉Disassembly: before disassembly to master the structure of the hydraulic valve and the connection between the parts, disassembly to remember the relationship between the location of the parts, make appropriate markings. Do not force disassembly, so as not to damage the hydraulic valve.
⒊Cleaning: the valve body, spool and other parts on the tray of the cleaning box, heating soak, the compressed air into the bottom of the cleaning tank, through the bubble stirring effect, cleaning off the residual dirt, the conditions can be used ultrasonic cleaning.
⒋Fine washing: high pressure positioning cleaning with cleaning liquid, and finally drying with hot air. Conditional enterprises can use the existing cleaning agent, individual occasions can also use organic cleaning agents, such as diesel, gasoline. A this inorganic cleaning fluid is toxic, heating volatile can make people poisoned, should be used with caution: organic cleaning fluid is flammable, should pay attention to fire. When choosing a cleaning fluid, pay attention to its corrosiveness to avoid corrosion of the valve body. The cleaned parts should be stored with care to avoid rusting or re-pollution.
If the spool and body are uniformly worn and the working surface is not severely scratched or severely worn, the parts can be categorised according to the test results and repaired according to the recommended fit between the following table.
| Hydraulic valve bore and spool shape accuracy and fit clearance reference values | |||
| Types of hydraulic valves | Valve bore (spool) cylindricity, taper/mm | Surface roughness Ra/μm | Mating gap/mm |
| Low and medium pressure valves | 0.008-0.010 | 0.8-1.0 | 0.005-0.008 |
| High pressure valves | 0.005-0.008 | 0.4-0.8 | 0.003-0.005 |
| Servo valves | 0.001-0.002 | 0.05-0.2 | 0.001-0.003 |
If the spool and body are unevenly worn or the working surface is scratched, and the above method cannot restore the function of the hydraulic valve, the spool and body (the body with a small hole size and the spool with a large outside diameter) should be repaired, and the hole of the body should be reamed, ground or grinded, and the spool should be repaired by brushing and grinding to achieve a reasonable shape accuracy and fit accuracy.
The replacement parts method is to disassemble the spool that has lost its accuracy, measure and draw a parts diagram, check the wear or damage of the valve body guide hole or valve seat, and determine the repair processing size accordingly, and then process the new spool according to this size. This repair method is highly accurate, widely applicable, and can completely restore the original accuracy, suitable for enterprises with certain processing capabilities.
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