A common cause of pressure pneumatic valve failure

in the agricultural machinery hydraulic system, pneumatic pressure valve is a type of the element, apply more pressure pneumatic valve sudden failure will directly affect the normal operation of the machinery and equipment, this paper points the reason of the pressure of the pneumatic valve failure and pressure of the pneumatic valve testing methods are introduced. 。 A common cause of failure ( Hydraulic pneumatic valve core and valve body is constantly produced when use wear, makes parts change size, shape and surface quality. ( Balance spring in hydraulic pneumatic valve, pneumatic valve core and valve seat, in the long-term work under variable load, fatigue and cracks, caused by spring, pneumatic valve seat sealing surface spalling, broken or damaged. ( In the process of the hydraulic pneumatic valve parts processing in the process of using the residual stress and residual load stress, more than the yield strength of material, parts parts deformation. ( In the hydraulic oil mixed with water or too much acid, after using a long time, the corrosion of hydraulic pneumatic valve parts, make its loss of accuracy. ( Pneumatic valve core and valve suites liquid unbalanced radial force, pressure to eventually make the pneumatic valve core clamping phenomenon in a pneumatic valve set inside wall. ( When hydraulic pneumatic valve manufacture or repair, did not meet the technical requirements; Improper safekeeping or parts, corrosion, mixed with dirt and so on. 。 Test method for pressure pneumatic valve including overflow pneumatic valve, pneumatic vacuum pneumatic valve and sequence valve, etc. , in this paper, the overflow pneumatic valve as an example to show pressure pneumatic valve test items and test methods. Pressure of the pneumatic valve test can be done on the special test bench, can also be carried out comprehensive experiment platform. ( Provision and pressure stability test. Regulating subjects the regulation of pneumatic valve handwheel from full open to full close, to fully open again, see from pressure gauge pressure rise and fall as well as the regulating scope. Gauge pressure should be steady rise and fall, regulating range shall meet the rules regulating range, at the highest pressure, the pressure pulsation value shall not exceed the specified value. ( The leakage test. Adjust the pneumatic valve to adjust the handwheel to the fully closed position, pneumatic valve for regulating the overflow security is the highest pressure pneumatic valve, and then try to adjust the adjustment of the pneumatic valve handwheel, make participants pneumatic valve leakage within the overflow mouth measurement. ( Unloading stress test. Will overflow tank remote control of pneumatic valve mouth, make participants pneumatic valve through a flow test, measuring the overflow of the pneumatic valve in and out of the oil inlet pressure, the difference is the subjects of pneumatic valve and pressure. ( The pressure loss test. Regulating subjects the regulation of pneumatic valve handwheel to loosen completely, and make the subjects of pneumatic valve through the test flow, the overflow of the pneumatic valve is measured by the pressure gauge in and out of the oil inlet pressure, the difference is the subjects of pneumatic valve pressure loss. ( On-off characteristic test. Pneumatic valve to close the overflow safety, regulate the subjects pneumatic valve to the highest pressure, pneumatic valve regulating the overflow security system gradually step-down, when subjects to pneumatic valve closure pressure measured subjects flow capacity of pneumatic valve. Pneumatic valve regulating the overflow safety, starting from the subjects of pneumatic valve does not overflow, make the system pressure rise gradually, as to the subjects of pneumatic valve opening pressure, measured by flow capacity of pneumatic valve.