Cavitation phenomenon in engineering machinery

by:HMB     2021-01-28
In the maintenance of drivers, often find a diesel engine cylinder liner especially with thrust side have cellular cavity, variable speed control valve in unpick and wash, such as distributing valve hydraulic valve, found with the surface blackening and scratches and small hole, this is actually a cavitation phenomenon. The harm of the cavitation, hydraulic components of high precision and small fitting clearance of relative motion parts, can cause with surface blackening after produce cavitation appear even small pit, make stem jamming, pressure imbalance, serious when not working. Cylinder liner cavitation phenomenon happened is lighter, the partial surface cleaner or like after polishing. Cavitation phenomenon is heavy, the shape of the cylinder liner will appear darker irregular pits, like cylinder liner surface been corrosion; If serious cavitation phenomenon to a certain extent, cylinder liner can punch, the cooling fluid into the cylinder in the body and the engine a serious accident. Causes of cavitation analysis: 1, the oil bubble resistance is poor, easy vaporization and bubble formation, it is easy to cause cavitation. 2, the oil level is too high, the oil by mechanical agitation and easy to produce foam; Oil level is too low, working pump suction air, increase the probability of air or water vapor to form the air bubbles in the oil. 3, the oil temperature is too high, oil evaporation, evaporation, water bubble and an increase in air bubble, cavitation rate increase. 4, the oil change the frequency of the direct impact on the formation of air bubbles and the rupture velocity, pressure changes the position with high frequency, fast cavitation. 5, when cooling water is contained in the corrosion medium and acid radical ion, etc. , make corrosion and the joint action of cavitation, accelerate the speed of cavitation damage. 6, shooting the hydraulic system of air and water, the more produce cavitation range more widely. 7, the piston and cylinder liner, and various hydraulic valve with vice gap is larger, the vibration intensity is big, the cavitation. 8, due to cavitation is rooted in vibration, the vibration strength and structural stiffness is directly related to. Low stiffness caused by cavitation phenomenon. 9, has a large influence on cylinder liner cavitation is the radiator pressure cap and thermostat, a good radiator cover pressure can maintain cooling fluid pressure than the vapor pressure is high, thus can reduce the generation of cavitation. 10 poor working conditions, engineering machinery, diesel engine, in particular, maximum explosion pressure is big, cause lateral knock force increases accordingly, that cause cavitation.
and everybody know together in front of the cavitation and its causes, as here together to understand how to prevent cavitation. 1, choose the oil to ensure the quality of product and suitable viscosity, gas when must pay attention to clean, do not take into the water and impurities; Add cooling water, not contain corrosive medium in the water. 2, oil dipstick in strict accordance with the standards, construction machinery of all kinds of oil oil dipstick all graduated with upper and lower limits, control the normal oil level of the oil to reduce cavitation. 3, to prevent the oil temperature is too high, working duration is too long, should stop cooling, if it is other reasons, should carry on the analysis, troubleshooting. Too little oil does not open, such as cooling water or outer and inner leakage, etc. , should be ruled out in time. 4, the decrease of hydraulic impact, the hydraulic control valve, distributing valve shoulds not be too fast too hard, and throttle also shoulds not be too frequently, in order to reduce the hydraulic shock. 5, maintain the normal clearance, the sports surfaces when manufacturing or repairing, according to the assembly tolerance limit assembly can reduce the influence of cavitation. Such as the cavitation phenomenon, has only with gold paper polishing to remove carbon, must not with general fine sandpaper. 6, keep the hydraulic system clean, prevent air and moisture into the regular cleaning magnetic filter. Replacement of all kinds of filter, keep the oil clean. Pay attention to check the oil level, oil and oil color, if it is found that there are water droplets in the hydraulic system, the oil into a milky white or the oil bubble shaped should carefully analyze the source of the water and air in time, check the oil cooler and sealing of the pump inlet. 7, reduce the vibration of the cylinder, increase the rigidity of the cylinder, the purchase of wall thickness of 0. 08 D( D) cylinder diameter Above the cylinder, the cavitation phenomenon is rare,. 8, correct maintenance of the cooling system, ensure the radiator pressure cap in good condition and work properly, thus reducing the generation of cavitation; Keeps the temperature of the cooling system in a proper range, in order to reduce the bubble burst of energy, using the right amount of coolant additives, inhibition of corrosion effect.
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