Improve the ability of superpressure pneumatic valve erosion wear resistance

the superhigh pressure technology has been widely used in hard materials, chemical industry, petrochemical industry, processing technology, such as static pressure processing, ultra-high static pressure extruding, powder metallurgy, metal forming, and geophysical and geological mechanics research and other fields. Due to the wide use of high pressure technology, ultra-high pressure system in the ultrahigh pressure pneumatic valve performance directly affect the reliability of the whole system work, security, efficiency and service life. In those should be frequent supercharging pressure relief system is particularly important. Main failure causes of superpressure pneumatic valve cavitation and erosion wear, and there are many influence factors of cavitation and erosion, the main factors have the material mechanical properties, fluid mechanics and environmental impact. To improve the pneumatic valve of cavitation and erosion wear resistance can be used many methods.
in order to improve ultrahigh pressure pneumatic valve of erosion wear resistance, usually choose corrosion resistant material. 1) high hardness of materials. (2) acid corrosion protective film material. (3) the yield point is high, the stability is good material. (4) high fatigue strength of materials. To improve the material performance, one is using alloying, 2 it is to adopt the proper heat treatment. Alloying method is by changing the chemical composition of steel, the development of new materials of various kinds of special performance. Heat treatment is not change the chemical composition of steel, but the steel under solid state with different heating, heat preservation and cooling, in order to change the organization structure of steel, improve the performance of materials.
choosing superpressure pneumatic valve flow components material, flow rate should be considered, The highest working pressure, gravity is different also. Under the high pressure ( MPa above, selects the high hardness and good red hardness materials, such as tool steel or hard alloy. Under low pressure, - MPa, asking the material has good plasticity and toughness, and high hardness. Such as the HIP company superhigh pressure pneumatic valve, needle work pressure for MPa austenitic stainless steel, working pressure for the MPa using markov shape precipitation hardening stainless steel - PH。 In foreign countries, used to withstand the cavitation of component materials, pneumatic disc and seat multi-purpose martensitic stainless steel and tool steel, such as pneumatic seat with chrome alloy steel and stainless steel substrate. With the successful development of industrial ceramics technology, have appeared in the ceramic material of pneumatic valve. Ceramic materials at low Angle of attack with high erosion resistance (), but because of the pneumatic valve needle taper is reduced, its strength is reduced, the seat of the pneumatic valve needle and pneumatic force also decreases, and affect the reliability of the seal. Therefore, when choosing ceramic materials pneumatic valve needle, not only to consider the magnitude of the taper at the same time to consider the strength.
adopts new structure: ( Using the general ultrahigh pressure tight seal unloading pneumatic valve is working, pneumatic disc under medium pressure was an upward thrust, the higher the pressure in the system by the upward thrust, the greater the sealing surface pressure than the lower. And at the instant of the closed control pressure pneumatic valve, to produce very big impact, pneumatic valve seat sealing surface easily damaged and reduce the service life of pneumatic valve. Self-tightening type pneumatic seat ultrahigh pressure relief valve may be substituted, the pneumatic valve pneumatic disc is not directly affected by dielectric flushing, reduces the erosion wear. Pneumatic valve is closed, the disc only by small spring elastic effect, make the pneumatic disc on the impact of the pneumatic valve seat is small, the sealing surface is not easy to damage, and increases the service life of pneumatic valve. Due to its simple structure, reliable operation, can guarantee the stability of the pneumatic valve work under ultra-high pressure. ( The wedge pneumatic disc from the mechanics analysis, because the cone pneumatic valve is a cantilever beam, under the impact of the high speed fluid, prone to vibration and fatigue fracture under the high frequency vibration. Wedge structure of the pneumatic valve, as shown in the figure the pneumatic valve core for a slope cutting cylindrical pneumatic valve core and form, this kind of shape analysis from the Angle of mechanics, the equivalent of a simply supported beam, due to its lower close to pneumatic pneumatic valve seat valve, so the vibration of the pneumatic valve is small or difficult to vibration, and compared with the pneumatic valve tapered wedge pneumatic valve in the process of operation stability is good. In addition, pneumatic valve seat and the pneumatic valve outlet design written venturi nozzle shape, can reduce the cavitation erosion and flash vaporization. In front of the pneumatic valve or pneumatic valve after the current limit hole, can absorb part of the pressure drop, reduce the pressure drop after former pneumatic valve pneumatic valve, cavitation can be abated. If there is a flash phenomenon, is not easy to adopt the bottom near side flow. With new structure is to improve the super high pressure relief is an effective means of pneumatic valve hydraulic pneumatic valve life. However, the higher the pressure, structure should be more simple.
in order to prolong the service life of superpressure pneumatic valve, consider the working environment. ( Avoid pneumatic valve work under small open degree, if small pneumatic valve open needle lift or open slow, work in a small open degrees throttling small gap, serious erosion, appropriately increase the pitch of locking mechanism, enlarging the opening speed and lift, increases the job opening, make the throttle gap is big, scour is abate, can improve the service life. ( Avoid pneumatic valve working under high temperature medium, medium temperature had a great influence on the life of the pneumatic valve, medium temperature is higher, the shorter the life of the pneumatic valve, the longer the vice. Therefore in the discharge pressure pneumatic valve and cooling device, also can obviously improve the service life of pneumatic valve. ( Under different working pressure, the use of corresponding pressure sealing, choose suitable sealing pressure, using a torque wrench to tighten, or realize the automation of pneumatic valve control, so that you can avoid pneumatic valve needle in extrusion was not flush with pneumatic valve seat wear and damage. ( Filter high pressure medium and cleaning filter regularly, and application in liquid filter to filter. Often when using, should be appropriate to shorten the cycle. Regular cleaning tank, replace the new medium at the same time, according to the actual situation of equipment work can shorten the cleaning and oil change period. ( When installing or replace needle pneumatic valve to the proper cleaning. To avoid into sundry, accelerate pneumatic valve needle wear and tear.