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The deep-hole boring machine rebuilt with a CW6163×3000 lathe is a special device for machining hydraulic cylinders. When working, clamping cylinders often suffer from clamping failure, stuffy cars, etc. Excessive leaks are the main reason for the system. Internal leakage in the hydraulic drive is unavoidable. If the internal leakage exceeds the allowable range, the system will operate abnormally, shorten its life, and even cause the system to malfunction. The relative movement parts of the pump, valve, and cylinder of the system must have a certain clearance. To ensure that no serious internal leakage occurs, some parts should be fitted with seals in addition to the proper clearance, if the hydraulic components are seriously worn or the seals fail. It will cause excessive internal leakage. From the actual situation of the scene, the main reason for the occurrence of excessive internal leakage is: oil pollution heat and hydraulic shock.
1, oil pollution
There is a certain gap between the moving surfaces of the hydraulic components of the system. When the solid contaminants in the oil flow into the gap along with the liquid flow, the surfaces of the parts are contaminated and worn. As the surface wears, the auxiliary clearance increases and the internal leakage increases. The critical particle size of element contamination and wear is an important parameter for assessing the degree of element contamination, and is also the basis for selecting the filtration system. The particle size is larger than the gap and does not easily enter the gap. Smaller particles can enter the gap and can generate slight wear, and the particle size and clearance Near or equal, once in the gap, it will cause serious wear or scratches on the surface of the seal.
During the overhaul, it was found that some oil filters of the trampoline hydraulic system were damaged or lost, and the oil filtering accuracy was too low to allow the solid particles to be effectively controlled. When sludge is deposited on the bottom of the tank, when it is refueled in the tank, it often causes system contamination, aggravates component wear, increases internal leakage, and causes system failure.
2, oil heating
The leak caused by the heating of the clamping system is mainly due to the decrease of the viscosity of the oil and the deterioration of the oil caused by the heat, hardening of the seal ring, and expansion. The depth of oil at the on-site depth measurement borehole pump station is 40-50°C in winter and 60-70°C in summer. Relevant data shows that when the oil temperature rises by 8°C, the life of the fluid should be reduced by half. For example, if the number 20 oil rises from 20°C to 80°C, the leakage will increase by 21.4 times due to the decrease of viscosity, and the leakage of the oil with larger viscosity 30th will increase by 13.3 times. In addition, the increase in temperature causes the normal gap to become smaller, which tends to increase the wear due to deformation of the hairpin, eventually making the gap larger and increasing the leakage amount.
3, hydraulic shock
Excessive leakage caused by hydraulic shock is also more prominent. In practice, when the operator changes the flow caused by the valve when changing parts or power, the system often produces a sharp pressure change, resulting in system vibration, noise, Loose connections, broken seals and leaks.
Second, fault prevention
1, control the hydraulic oil pollution
Strengthen equipment maintenance and regularly check hydraulic oil. Before changing oil, carefully clean the hydraulic system. Many deep hole concrete hydraulic systems, between two major overhauls, never had the system changed oil, which is often an accident hazard.
In terms of oil filtering, the oil filter is required to have appropriate filtering accuracy and contamination capacity. Some deep-hole oil filter screens have low filtration accuracy and solid particles are not effectively controlled, resulting in increased wear of the relative moving parts and increased leakage. Therefore, the oil filter must meet the requirements of filtration accuracy, and it must be cleaned frequently. If the oil filter is partially blocked, the clamping speed will be slow or the clamp will not be tight. If the oil filter is blocked or the relief valve is stuck, the pressure of the system will be too high until the system is destroyed.
2, heat and hydraulic shock control
During the overhaul, it was found that the seals of the deep-hole bore were severely aged. This was mainly due to system heating. The temperature of the hydraulic oil was increased. After clamping the cylinder, the reversing valve (M type) was stopped at the middle position. Stopping the pump not only saves power, but also allows the oil temperature in the pump station to cool rapidly to normal temperature.
Due to the reasons of stopping the pump, changing the workpiece, etc., the system is subjected to more shocks and the correct operation of the system is especially important. Do not try to find out the cause of a failure in the clamping system, but not to find out the reason, but quickly change the direction of the valve, the result can only be the system stagnated after the oscillation, the reason is that the hydraulic shock makes the overflow valve too late to respond, it will make the system produce Impact action. Repeated impact, due to higher pressure and system heat, the seal is damaged, leakage increases, so the clamp is not tight. The correct method is to make the pump station run several times before clamping the oil cylinder. Observe whether the system is abnormal. If there is no abnormality, then slowly operate the valve to start clamping. This will greatly extend the life of the system.
Deep hole boring machine hydraulic clamping system failure and prevention
First, the cause of the failure