To reduce the oscillation and noise outbreak of the hydraulic system in the machining center, and prevent the expansion of noise, the machining center factory teaches you to do a good job in prevention and improvement from the following aspects:
Vibration and noise in the hydraulic system of the machining center
（1） Improvement of hydraulic system structure
In the process of operating the hydraulic system in machining centers, attention should be paid to the use of low-noise hydraulic components. After discussion, it was found that old-fashioned hydraulic pumps are mainly plunger pumps or gear pumps, and their noise oscillation and noise are much larger than blade pumps, and the additional pressure is also very high. Therefore, many machining center hydraulic systems still use plunger pumps or gear pumps. To address this situation, it is necessary to improve the additional pressure of blade pumps, at least ensuring that their additional pressure is around 20MPa, in order to reduce oscillation and noise. Secondly, control the number of hydraulic pumps well. After discussion, it was found that when the number of hydraulic pumps is reduced, oscillation and noise will also be reduced. Therefore, it is necessary to control the number of hydraulic pumps well. In traditional hydraulic systems, multiple hydraulic pumps are required to regulate flow and pressure. To ensure that the flow and pressure of hydraulic pumps are proportional, pressure and flow can be adjusted to reduce the number of hydraulic pumps. Furthermore, when using an accumulator, it is easy to generate noise under pressure pulsation. To eliminate noise, the accumulator can be used. Although the accumulator has a small capacity, its inertia is relatively small, and the response is also very active. During the use of an accumulator, the frequency should be controlled at around tens of hertz to reduce pressure pulsation. Finally, do a good job in setting up vibration dampers and filters. Generally speaking, there are many methods for vibration dampers, and the ones that can be used include high-frequency pressure dampers and micro perforated liquid dampers. The commonly used filters in practice are hydraulic filters, and the use of these devices can minimize vibration reduction and noise to the greatest extent possible.
（2） Improvement of Hydraulic Equipment Equipment Methods
In order to control oscillation and noise effectively, the machining center also needs to further improve the methods of hydraulic equipment and equipment, and can start from the following two aspects: the top, the suitable hydraulic pump for the equipment. During the process of installing hydraulic pumps and motors, it should be ensured that the axial error between the two does not exceed 0.02mm, and flexible couplings should be used between them. In the process of equipping hydraulic pumps, if the pump and motor equipment are on the oil tank cover, it is necessary to provide anti vibration and noise reduction materials on the oil tank cover, and combine them with practice to use equipment with good oil absorption height and density. Only in this way can the planning be ensured to be reasonable. Secondly, pipeline equipment. Doing a good job in pipeline equipment is also a very important task. In order to do a good job in vibration prevention and noise elimination, flexible hoses can be used to complete the connection, and the length of the pipeline can be appropriately shortened to improve its rigidity and prevent resonance between pipelines. During the sealing process, straight sealing should be the main method. For valve components, attention should be paid to the use of tension springs in practical use, and attention should be paid to the use of encrypted sealing gaskets to prevent oscillation and noise caused by air mixing in the oil pipe. In addition, it is necessary to control the curvature of the pipeline well, with a maximum of 30 degrees, and the curvature radius of the elbow should be more than five times the diameter of the pipeline.
（3） Selecting suitable fluids
In the process of hydraulic system oscillation and noise prevention, the machining center should also pay attention to the selection of oil and prevent oil contamination. In the process of selecting oil, it is necessary to prevent selecting oil with high viscosity. If such oil is used, it will bring certain large suction resistance to the hydraulic pump, which will cause noise. Therefore, the viscosity of the oil should be controlled to ensure that it has good defoaming ability. Although this approach requires a lot of capital investment, its later effect is good, not only can it extend the service life of the equipment, but also reduce the harm to the hydraulic pump and components. After discussion, it was found that the anti wear hydraulic oil has a higher pour point and better overall effect. Therefore, it is best to choose anti wear hydraulic oil. No matter how good the oil is contaminated, it will not be able to function properly in the future. Once the oil is contaminated, it will present a situation where the filter screen in the oil tank is blocked, which will also cause the oil pump to be unable to suck oil smoothly, and will also affect the oil return, causing noise and oscillation. In response to this situation, relevant personnel need to regularly clean the oil tank. During the oil filling process, the filter or filter screen can be used to filter the oil again, improve the quality of the oil, and a partition should be set up at the bottom of the oil. Under the effect of the partition, the oil in the return area will leave impurities in the return area due to the sedimentation effect, effectively preventing the oil from flowing back into the suction area.
（4） Prevent hydraulic impact
In the process of preventing hydraulic impact, machining centers can start from the following two aspects: first, hydraulic impact when the valve port suddenly closes. In the process of solving such problems, the closing speed of the directional valve should be appropriately reduced. As the closing speed of the directional valve decreases, the reversing time will increase. After the braking reversing time exceeds 0.2 seconds, the impact pressure will decrease. Therefore, adjustable directional valves can be used in hydraulic systems. Due to the fact that flow velocity is also a factor that causes oscillation and noise, it is necessary to control the flow velocity well in the process of preventing hydraulic impact. It is best to control the pipeline flow velocity below 4.5 meters per second. Control the length of the pipeline together, avoid selecting pipes with bends as much as possible, and prioritize hoses. To minimize hydraulic impact, it is best to properly control the liquid flow rate before the slide valve is closed, which is also a useful method for reducing hydraulic impact. Secondly, hydraulic impact occurs when the moving parts brake and decelerate. When preventing such impacts, the first priority is to set up responsive and flexible safety valves at the inlet and outlet of the hydraulic cylinder. It is best to use direct action safety valves and control their pressure well to prevent impacts caused by excessive pressure. Secondly, the deceleration valve should be used as a key point to prevent unnecessary impacts caused by slow oil circuit closure. At the same time, the speed of moving parts should be controlled well, and its speed should be controlled below 10m per minute. Furthermore, to prevent excessive hydraulic impact, it is best to install a certain buffer device on the upper part of the hydraulic cylinder. This can not only prevent the oil discharge speed in the hydraulic cylinder from being too fast, but also control the operating speed of the hydraulic cylinder to prevent excessive impact. In addition, balance valves and backpressure valves should be installed in the hydraulic cylinder to not only reduce the hydraulic activity speed to the greatest extent possible, but also effectively prevent forward impact. This is also a useful method to increase backpressure pressure. Ultimately, it is necessary to use directional valves with damping effects, mainly with large damping, and to close the one-way throttle valve and control the smooth pressure well to prevent excessive smooth pressure. In the process of reducing hydraulic impact, it is also necessary to control the clearance of the hydraulic cylinder body to prevent excessive clearance or unreasonable sealing from affecting the normal operation of the hydraulic system. To prevent such incidents, it is best to use new pistons and set appropriate sealing components, as long as this is done to prevent the occurrence of adverse events to the greatest extent possible.
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