Causes and elimination methods of vibration and noise of hydroforming machine

Causes and elimination methods of vibration and noise of hydroforming machine

1. The origin of vibration and noise

There are many reasons for the vibration and noise of hydraulic forming machines, including mechanical systems, hydraulic pumps for hydraulic forming machines, hydraulic valves and piping. Vibration and Noise of Mechanical Systems The vibration and noise of mechanical systems are primarily caused by the mechanical transmission system that drives the hydraulic pump of hydraulic forming machines. The following are the first aspects.

1) Unbalance of the reversing body In practical applications, most of the motors are driven by the hydraulic pump of the hydroforming machine driven by the coupling. It is very difficult to make the reversing body completely balanced, if the imbalance is too large , it will attack the tortuous vibration of the larger shaft when the reversal occurs, and the noise will be attacked.

2) Inappropriate device The hydraulic system often causes vibration and noise due to problems on the device. If the system piping is poorly supported and the basic disadvantages or the hydraulic pump of the hydroforming machine is not concentric with the motor shaft, and the coupling is loose, these will cause large vibration and noise.

2. Hydroforming machine Hydraulic pump (hydraulic motor) is usually the most important hydraulic component in the whole hydraulic system. The cause of vibration and noise in hydraulic pump is due to mechanical vibration and another The aspect is caused by the accumulation of changes in the liquid pressure flow.

1) Cycle change of hydraulic pump pressure and flow in hydroforming machine

Hydraulic forming machine hydraulic pump gears, blades and dampers in the process of oil absorption, pressure oil, so that the corresponding operation during the periodic flow and pressure process, so that the corresponding operating chamber attack cycle flow and pressure changes, In turn, the flow rate and pressure pulsation of the pump are caused, and the components of the hydraulic pump of the hydroforming machine are vibrated, and the vibration of the component causes the vibration of the air that is touched by the touch, and the sound pressure wave of the noise is transmitted.

2) Cavitation of hydraulic pump of hydraulic forming machine

When the hydraulic pump of the hydroforming machine is working, if the resistance of the hydraulic oil suction pipe is too large, at this moment, the hydraulic oil is too late to fill the suction chamber of the pump, forming part of the vacuum in the suction chamber to form a negative pressure. If this pressure just reaches the air of the oil When the pressure is not separated, the air dissolved in the oil will be separated and formed into a bubble of free state. As the pump moves, the oil with bubbles is transferred to the high pressure zone, and the bubble is subjected to high pressure at this moment. And shrinking, breaking and disappearing, constitutes a high part of the high frequency pressure shock

3) Mechanical vibration in hydraulic pump of hydraulic forming machine

The hydraulic pump of the hydroforming machine is composed of many parts. Because of the manufacturing error of the parts, the improper operation of the parts may cause vibration and noise of the hydraulic system. 3. Vibration of the hydraulic valve and noise of the noise of the hydraulic valve. , the use of conditions and other specific conditions vary. According to the reasons for its onset, it can be roughly divided into two categories: mechanical sound and fluid sound.

(1) Mechanical sound Most hydraulic valves are composed of valve core, valve body, regulating parts, fasteners, seals, etc. It is the external force to make the valve core move and the valve core moves to the corresponding position to make the liquid Flow changes, satisfactory job requirements. During this process, the mechanical touch of the movable parts within the valve is aggravated by noise.

(2) Fluid sound Because the hydraulic valve is saving, reversing, and overflowing, the flow, direction and back pressure of the liquid flow in the valve body are variously changed, causing the wall of the valve member and the pipe to vibrate, and then the noise is attacked. According to the reasons of its onset pressure vibration, it can be divided into cavitation sound, flowing sound, hydraulic shock sound and vibration sound. Vibration and noise of the pipeline This is primarily due to the interaction of the vibration of hydraulic components such as pumps and valves on the pipeline. Studies have shown that when the length of the pipeline is exactly equal to an integral multiple of half the wavelength of the vibration pressure, the pipeline will have strong high frequency noise.

In addition, the external source may also cause the pipeline to resonate; and when the cross-sectional area of the pipeline is suddenly changed (rapidly expanding and shrinking or sharply turning), the liquid flow between them will change, and turbulence will occur and noise will be emitted.

Preventing the oil from mixing into the air The hydraulic system tends to have less noise at the beginning of the work. After a certain time, the noise increases. If the hydraulic oil in the fuel tank is investigated at this moment, the hydraulic oil can be found to be yellow. This is mainly because of the oil. Mixed with small bubbles, so it changes color. Regarding this situation, the method is adopted from two aspects first, and the first is to fundamentally solve the problem of preventing air from entering. The second is to quickly remove the air mixed into the oil body.

specific method

1 pump suction pipe joint seal is strict to prevent inhalation of air;

2 Reasonably plan the fuel tank. Preventing the occurrence of cavitation in the hydraulic valve The occurrence of cavitation in the hydraulic valve is primarily to minimize the oil absorption resistance of the pump. Commonly used methods include selecting a larger diameter suction pipe and a large-capacity oil suction filter to prevent the oil filter from being blocked; the pumping height of the pump should be as small as possible.

Prevent the occurrence of turbulence and swirl in the pipeline

When planning the hydraulic system pipeline, the pipeline section should be prevented from expanding or shortening as much as possible; if the elbow is selected, the radius of curvature should be more than five times the diameter of the pipeline. These methods can effectively prevent turbulence and rotation in the pipeline. The onset of the flow.

Use an accumulator or muffler to absorb pressure pulsations in the pipe

Pressure pulsations in the pipeline are the primary cause of systemic vibration and noise. The accumulator is provided in the hydraulic circuit to absorb the vibration effectively, and the vibration is also effectively reduced by providing the damper adjacent to the vibration portion.

Prevent system resonance

In the hydraulic system, the vibration source often occurs (such as hydraulic pump hydraulic pump, hydraulic motor, motor, etc.) causing resonance in the bottom plate, pipeline, etc.; or the resonance of components such as pumps, valves, etc., constitutes a large noise. With regard to this phenomenon, the natural vibration frequency of the pipe can be modified by changing the length of the pipe, and the device orientation of some valves can be modified to eliminate it.

Barrier vibration

Regarding the primary vibration source (pump, motor) in the hydraulic system, it is often necessary to install a rubber pad or a spring to block it from the bottom plate (or the fuel tank), and also to use a method of mounting the vibration source on the bottom plate and blocking the entire system. These can all receive good vibration and noise reduction effects.