In the hydraulic system, the air in the oil will be separated and a large number of bubbles will be formed if the pressure is lower than the air pressure at the working temperature of the oil; when the pressure is further reduced to the saturated vapor pressure at the working temperature of the oil, the oil will rapidly vaporize and produce a large number of bubbles. These bubbles are mixed in the oil, resulting in cavitation, so that the oil filled in pipes or hydraulic components turn into a discontinuous state, this phenomenon is generally known as the cavitation phenomenon.
Cavitation occurs at the inlet and outlet of the hydraulic pump. When the oil flows through the narrow channel of the manual hydraulic valve port, the liquid flow rate increases, the pressure drops sharply, and the cavitation phenomenon appears. Hydraulic pump installation height is too high, oil suction pipe diameter is too small, oil absorption resistance is too large, or hydraulic pump speed is too high, inadequate oil absorption, etc., are likely to cause cavitation.
Cavitation occurs in hydraulic system, the bubble with the oil flow to the high pressure area, under high pressure air bubbles will quickly break down, the liquid around to fill this hole at high speed, the liquid in the high-speed collision and form local hydraulic impact, the local temperature and pressure increased sharply, caused a strong vibration and noise.
Pipe wall and element surface near bubble condensation, due to the long-term impact of hydraulic shock and high temperature, as well as the strong corrosion of the gas in the oil, so that the metal element and particles of the wall surface are spalling, the corrosion on the surface of the cavitation phenomenon called gas etching.
In order to prevent cavitation and gas etching, the following measures can be taken:
1.Reduce the flow of small holes and gaps in the pressure drop, the general hope that the pressure ratio before and after the gap is p1/p2<3.5.
2.To correctly determine the diameter of hydraulic pump suction pipe in the pipe, limit the flow of liquid, reduce the suction height of hydraulic pump, reduce the pressure loss in the pipe joint oil pipeline, a good seal, the auxiliary pump for high-pressure cartridge hand pump.
3.The entire pipeline system should be as straight as possible, avoid sharp bends and local narrow.
4.Improve gas etching resistance of components.