Causes of vibration and noise of hydraulic cylinders

The hydraulic cylinder will emit some vibrations, noises and other inductions during the working process. These are all normal. However, everyone is puzzled about the causes. Why these inductions are caused? Let me introduce you:

　　 1. There are many sources of vibration and noise in the hydraulic cylinder, which generally include mechanical systems, hydraulic pumps, hydraulic valves and pipelines. Vibration and noise of the mechanical system Vibration and noise of the mechanical system are mainly caused by the mechanical transmission system that drives the hydraulic pump, mainly in the following aspects:

1. The unbalance of the rotating body of the hydraulic cylinder In practical applications, most of the motors drive the hydraulic pump through the coupling. It is very difficult to achieve complete dynamic balance of these rotating bodies. If the unbalance force is too large, it will During the rotation, large bending vibration of the rotating shaft is generated and noise is generated.

　　2. Improper installation of hydraulic cylinders often causes vibration and noise due to installation problems. Such as poor system pipe support and foundation defects, or the hydraulic pump and the motor shaft are not concentric, and the coupling is loose, these will cause greater vibration and noise.

　　 2. The hydraulic pump (hydraulic motor) is usually the main hydraulic component that generates vibration and noise in the entire hydraulic cylinder system. The reason for the vibration and noise is, on the one hand, mechanical vibration, and on the other hand, the accumulation and change of liquid pressure and flow.

　　1. Periodic changes of hydraulic cylinder pump pressure and flow

The gears, vanes and plugs of the hydraulic cylinder pump make the corresponding work generate periodic flow and pressure during the process of sucking and pressing the oil, causing the corresponding working chamber to produce periodic flow and pressure changes, which in turn causes The flow and pressure pulsation of the pump cause the components of the hydraulic pump to vibrate, and the vibration of the components causes the air in contact with it to vibrate with density changes, and the sound pressure waves that generate noise are transmitted out.

　　2. Cavitation of hydraulic cylinder pump

　　 When the hydraulic oil cylinder pump is working, if the resistance of the hydraulic oil suction pipe is too large, at this time, it is too late to fill the oil suction cavity of the pump, causing a partial vacuum in the oil suction cavity and forming a negative pressure. If this pressure just reaches the air separation pressure of the oil, the air originally dissolved in the oil will be precipitated in a large amount, forming free bubbles. As the pump rotates, the oil with bubbles is transferred to the high pressure zone. At this time, the bubbles shrink due to high pressure, break and disappear, forming a high local high frequency pressure shock.

　　3. The mechanical vibration in the hydraulic cylinder pump is composed of many parts. Due to the manufacturing errors of the parts, improper assembly may cause the vibration and noise of the hydraulic system.

　　 3. Vibration and noise of hydraulic cylinder valves The noise generated by hydraulic valves varies with the type of valve, usage conditions and other specific conditions. According to the reason, it can be roughly divided into two categories: mechanical sound and fluid sound.

1. Mechanical sound. Most hydraulic cylinder valves are composed of spool, valve body, control parts, fasteners, seals and other parts. It uses external force to make the spool move, and the spool moves to the corresponding position to make the fluid The flow changes to meet job requirements. In this process, the mechanical contact of the movable parts in the valve generates noise.

　　2. Fluid sound. When the hydraulic cylinder valve is throttling, reversing, or overflowing, various changes occur in the flow, direction and back pressure of the fluid flow in the valve body, resulting in vibrations on the wall of the valve and the pipeline, thereby generating noise. According to the causes of pressure vibration, it can be divided into cavitation sound, flow sound, hydraulic shock sound and shock sound. Pipeline vibration and noise are mainly caused by the interaction of pumps, valves and other hydraulic components on the pipeline. Studies have shown that when the length of the pipeline is exactly an integer multiple of half the wavelength of the vibration pressure, the pipeline will produce strong high-frequency noise.

　　Four. In addition, external seismic sources may also cause pipeline resonance, and when the cross-sectional area of the pipeline changes suddenly (rapid expansion and contraction or sharp turns), the liquid flow in it will change, which is easy to produce turbulence and cause noise.

5. Preventing air from being mixed into the oil. The hydraulic cylinder system tends to have low noise during a period of time at the beginning of operation. After a certain period of time, the noise increases. If you observe the hydraulic oil in the oil tank at this time, you can find that the hydraulic oil has turned yellow. The color is changed due to the tiny bubbles mixed in the oil. For this situation, measures are mainly taken from two aspects. One is to solve it fundamentally to prevent air from entering. The second is to remove the air mixed into the oil body as soon as possible.

　　 The above is the reason that the hydraulic cylinder will produce vibration and noise during work. This phenomenon is normal during work. You don’t have to worry about accidents in the equipment.