How to reduce the vibration and noise of the hydraulic system of CNC machine tools?

(1) Improvement of hydraulic system structure

In the process of controlling the hydraulic system of CNC machine tools, attention should be paid to the use of low-noise hydraulic components. Through research, it is found that the old hydraulic pumps are mostly piston pumps or gear pumps, and their noise vibration and noise are much larger than those of vane pumps. , the rated pressure is also very high, so many hydraulic systems of CNC machine tools still use plunger pumps or gear pumps. In this case, it is necessary to improve the rated pressure of the vane pump, at least to ensure that the rated pressure is about 20MPa, so as to reduce vibration with noise. Second, control the number of hydraulic pumps. Through research, it is found that when the number of hydraulic pumps is reduced, the vibration and noise will also be reduced. Therefore, it is necessary to control the number of hydraulic pumps. In traditional hydraulic systems, multiple hydraulic pumps are needed to adjust flow and pressure. The pump flow and pressure can be adjusted proportionally to reduce the number of hydraulic pumps.

Furthermore, when the accumulator is applied, noise is easy to appear under the action of pressure pulsation. In order to eliminate the noise, the accumulator can be applied. Although the capacity of the accumulator is small, its inertia is relatively small and the response is very good. Sensitive, in the process of using the accumulator, the frequency of the accumulator should be controlled at about tens of hertz in order to reduce the pressure pulsation. Finally, do a good job of setting the shock absorber and filter. Generally speaking, there are many forms of shock absorbers, and the applicable shock absorbers include high frequency pressure shock absorbers and micro-perforated liquid shock absorbers. Common filters in practical use are hydraulic filters, and the application of these devices can minimize vibration and noise.

(2) Improvement of the installation method of the hydraulic device

In order to do a good job in vibration and noise control, it is necessary to further improve the installation method of the hydraulic device. You can start from the following two aspects: First, install a suitable hydraulic pump. In the process of installing the hydraulic pump and the electric motor, the axiality error of the two should not exceed 0.02mm, and the flexible coupling should be used in them. In the process of installing the hydraulic pump, if the pump and the motor are installed on the fuel tank cover, it is necessary to install anti-vibration materials and sound-absorbing materials on the fuel tank cover. The equipment is used in it, and only in this way can the design be reasonable. Second, pipe installation. It is also a very important job to do a good job of pipeline installation. In order to do a good job of anti-vibration and noise elimination, you can use hoses to connect, and appropriately shorten the length of the pipeline, improve the rigidity of the pipeline, and avoid resonance between the pipelines. At the same time, in the process of sealing, vertical sealing should be the main priority. For valve components, attention should be paid to the application of springs in actual use, and attention should be paid to the use of sealing gaskets to prevent vibration and noise caused by the inclusion of air in the oil pipe. . In addition, the bending degree of the pipe should be well controlled, the maximum should not exceed 30 degrees, and the radius of curvature of the elbow should be more than five times the diameter of the pipe.

(3) Choose the right oil

In the process of preventing and controlling vibration and noise of the hydraulic system, attention should also be paid to the selection of oil and to avoid oil pollution. In the process of selecting oil, avoid choosing oil with high viscosity. If such oil is applied, it will bring a certain large suction resistance to the hydraulic pump, which will cause noise. Therefore, the oil should be controlled. The viscosity of the oil ensures that the oil has good defoaming ability. Although this method requires a lot of capital investment, its later effect is better, which can not only prolong the operating life of the equipment, but also reduce the damage to the hydraulic pump and components. Through research, it is found that the anti-wear hydraulic oil has a higher freezing point and a better overall effect. Therefore, it is best to choose anti-wear hydraulic oil. At the same time, no matter how good the oil is polluted, it cannot play its due role. Once the oil is polluted, the filter screen in the fuel tank will be blocked, which will also cause the oil pump to fail to absorb oil smoothly, which will also affect the oil return. It brings noise and vibration. In view of this situation, it is necessary for relevant staff to clean the oil tank frequently. During the oil filling process, a filter or screen can be applied to it, so that the oil can be filtered again and the quality of the oil can be improved. It is also necessary to set a partition at the bottom of the oil. Under the action of the partition, the oil in the oil return area will leave impurities in the oil return area under the action of precipitation, which effectively prevents the oil from flowing back to the oil absorption area. in the area.

(4) Avoid hydraulic shock

In the process of preventing hydraulic shock, you can start from the following two aspects:

First, the hydraulic shock when the valve port is suddenly closed. In the process of solving such problems, the closing speed of the reversing valve should be appropriately reduced. As the closing speed of the reversing valve decreases, the reversing time will increase. After the braking reversing time is higher than 0.2s, the impact pressure will decrease. will drop, so an adjustable reversing valve can be applied to the hydraulic system. Since the flow rate is also a factor that causes vibration and noise, it is also necessary to control the flow rate in the process of preventing hydraulic shock. It is best to control the flow rate of the pipeline below 4.5m per second. At the same time, control the length of the pipeline, try not to choose the pipeline with curvature, and use the hose as the main pipeline. In order to minimize hydraulic shock, it is best to properly control the liquid flow rate before the spool valve is closed, which is also an effective way to effectively reduce hydraulic shock.

Second, hydraulic shock occurs when moving parts brake and decelerate. When preventing such shocks, first of all, you can set up a responsive and flexible safety valve at the inlet and outlet of the hydraulic cylinder, preferably a direct-acting safety valve, and control its pressure well, the only way to avoid pressure The impact of being too high. Secondly, the deceleration valve should be used as the key point of application, so as to avoid unnecessary shock caused by the slow closing of the oil circuit, and at the same time, the speed of the moving parts should be controlled well, and its speed should be controlled below 10m per minute. Furthermore, in order to avoid excessive hydraulic shock, it is better to set a certain buffer device on the upper part of the hydraulic cylinder, which can not only prevent the oil discharge speed in the hydraulic cylinder from being too fast, but also control the running speed of the hydraulic cylinder to avoid excessive shock. , In addition, the balance valve and the back pressure valve should be installed in the hydraulic cylinder, which can not only reduce the hydraulic flow speed to the greatest extent, but also effectively avoid the forward rush, which is also an effective way to increase the back pressure. Finally, it is necessary to apply the reversing valve with damping effect, mainly with large damping, and close the one-way throttle valve, and control the lubrication pressure to avoid excessive lubrication pressure. In the process of reducing hydraulic shock, it is also necessary to control the clearance of the hydraulic cylinder to prevent excessive clearance or unreasonable sealing from affecting the normal operation of the hydraulic system. Good and suitable seals are the only way to avoid adverse events to the greatest extent.

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