Hydraulic equipment damage caused by the impact of seals

Mechanical processing industry, hydraulic transmission is widely used, such as lathes and other types of semi-automatic hydraulic transmission . These machines during use , such as the impact of frequent , reptiles and other faults , diagnostic repair, often in the hydraulic control components ( such as various types of pumps, valves ) can not find the cause of the malfunction , resulting in maintenance trouble. The final such failure or normally found on the actuator causes the cylinder piston sealing element due to severe wear . Such phenomena especially "O" ring seal see more .
Example 1: a CE7120 hydraulic copying lathe, turret profiling occurs in the work cited by the sword turn longitudinal feed line cutting die cutter , resulting knife fight , scrap living phenomenon frequently, the machine does not work.
Inspection and Maintenance : Check no fault of the hydraulic control components , maintenance work temporarily into the blind spot. Overhauling vertical turret tank, found that the piston seal "O" ring seal has been polished cylindrical , cylindrical piston also found substandard size requirements ( genus machine tool manufacturing reasons ) , the diameter direction is less than standard size 0.8mm, piston and cylinder body clearance large, causing vertical cylinder two chambers communicate channeling oil . Maintenance, and replacement of the piston passing "O" -ring after the die cutter machine troubleshooting. Analysis of the reasons cited in the profiling tool holder in place of the instantaneous line of the sword , the whole holder to receive a momentum F ', the force is decomposed F'1 a horizontal force acting on the cylinder piston rod longitudinal direction , at the same time , the solenoid valve 34E1-25B work turned vertical cylinder rod chamber pressure oil chamber connected rodless return oil control valve , the piston rod chamber by the force F by the two partially completed , one for F'1, the other is F1 = A1P1, where A1 is rodless chamber force area , then F = F'1 + F1. Under normal circumstances , the piston under the action of the force F rod chamber began to move , as incompressible hydraulic oil , hydraulic oil pressure rodless abrupt increase cavity to form a back pressure piston , the piston control valve according to the force balance it is set to go steady speed knife . The moment due % F'1 role in longitudinal cylinder chamber pressure P2 will be greater than P1. In practice, the two-chamber cylinder gap channeling due to the P2> P1 moments, hydraulic fluid from the high pressure zone with rod chamber rod chamber to the low pressure area flow trends , liquidity , once produced , P2 reduced , P1 rises , F1 increase large , unbalanced force piston , the piston driven turret quickly moves to the rod chamber . And moments later, the end result of profiling tool slide downward acting on the piston in the cylinder longitudinal horizontal thrust F'1 disappear on their own fast-moving piston end , take the knife stabilized turret , plastic seal red knife phenomenon ends.
Example 2: a CB3463-1 semi-automatic programmable hexagon turret lathes, during use , the emergence of the turret feed rate can not adjust the failure phenomenon , globe valve 2 is closed there is still crawling, pediment , and has been to bottom of the tank to stop the machine does not work properly .
Inspection and Maintenance : Inspect all hydraulic control components , especially the governor components have not found any problems. Replace some of the control valve , the failure persists . After dismantling the cylinder after the discovery piston "O" ring seal badly worn , so that the two chambers of hydraulic oil cylinder channeling each year. Analysis of the reasons , because "O" -ring wear, cylinder rod chamber and the rod chamber gap increases interoperability, when closing valve control valve 3 or 2:00 , it means cutting off the cylinder rod chamber oil return road. Theoretically , the pressure oil into the cylinder rod chamber when the piston is formed without a force F , the piston rod chamber to move the trend, as the cylinder rod chamber back to the oil off the rapid formation of the oil cavity back pressure , so that the force balance across the piston stationary ,truck seal F a = F no time , no fluid pressure chamber due to the piston force different size and different, that is, P a > P no . In practice, a gap is formed due to the two chambers communicate with each cylinder , the cylinder chamber with pressure oil from the high pressure region to the low flow area trends , mobile one generation, a lower chamber pressure P , P without elevated ends of the thrust acting on the piston F No > F Yes, loss of balance piston rod chamber to move to find a new balance . And so forth, the piston has been moved to an external force barrier to stop. The phenomenon of the maintenance work to the machine brought great impact , replace the cylinder piston "O" ring seal , the machine fault elimination , running back to normal.