Hydraulic system common problems and treatment solutions
Dec 09, 2022
A. Causes of hydraulic system leakage
1, caused by defects in design and manufacture.
2, shock and vibration caused by loose pipe joints.
3, dynamic seals and mating parts wear each other (hydraulic cylinders in particular).
4, high oil temperature and rubber seals and hydraulic oil incompatibility and deterioration. The following is a combination of the above aspects to discuss the measures to control leakage.
Second, the control of hydraulic system leakage control program
Program 1: design and manufacturing defects in the solution: 1, the choice of hydraulic components outside the supporting often plays a decisive role in the leakage of hydraulic systems. This determines our technical staff in the design of new products, the improvement of old products, cylinders, pumps, valves, seals, hydraulic auxiliary parts and other choices, in line with the good selection of the best, the best selection of the principle of prudence, there is a comparison.
2, reasonable design of the installation surface and sealing surface: when the valve or pipeline fixed in the installation surface, in order to get a satisfactory initial seal and prevent the seal was extruded groove and be worn, the installation surface to be straight, sealing surface requirements for finishing, surface roughness to reach 0.8μm, flatness to reach 0.01/100mm. surface can not have radial scratches, the connection screw preload to be large enough to prevent the surface 3. In the manufacturing and transportation process, the key surface should be prevented from bumping and scratching. At the same time, the assembly and commissioning process should be strictly monitored to ensure the quality of the assembly. 4, the leakage of some hydraulic systems should not be taken lightly and must be eliminated.
Programme 2: Reduce shock and vibration: In order to reduce the leakage of the hydraulic system caused by loose pipe joints subjected to shock and vibration, the following measures can be taken: 1. use shock-absorbing brackets to fix all pipes in order to absorb shock and vibration; 2. use low-impact valves or accumulators to reduce shock; 3. properly arrange pressure control valves to protect all components of the system; 4. minimise the number of pipe joints used. 5. Use straight threaded joints, tees and elbows instead of tapered threaded joints; 6. Use return blocks instead of individual piping as far as possible; 7. Specify the torque of the bolts and the torque of the plugs used during installation for the maximum pressure used to prevent the union surface and seals from being eaten away; 8. Install pipe joints correctly.
Option 3: Reducing wear on dynamic seals: Most dynamic seals are precisely designed to ensure long periods of relatively leak-free operation if they are machined properly, installed correctly and used appropriately. From a design point of view, designers can use the following measures to extend the life of dynamic seals: 1. eliminate side loads on the piston rod and drive shaft seals; 2. protect the piston rod with dust rings, shields and rubber sleeves to prevent impurities such as abrasives and dust from entering; 3. design and select suitable filtering devices and easy-to-clean tanks to prevent the accumulation of dust in the oil; 4. make the speed of the piston rod and shaft as low as possible low.
Option 4: Requirements for static seals: static seals prevent oil leakage between rigid fixed surfaces. Reasonable design of seal groove dimensions and tolerances so that after installation the seal is deformed to a certain squeeze in order to fill microscopic depressions in the mating surface and to raise the internal stress of the seal above the pressure being sealed. When the part stiffness or bolt preload is not large enough, the mating surface will separate under oil pressure, causing a gap or increasing the gap that may exist from the start due to the sealing surface not being flat enough. With the movement of the mating surfaces, the static seal becomes a dynamic seal. The rough mating surfaces will wear the seal and the shifting gap will eat away at the seal edges.
Option 5: Controlling oil temperature to prevent seal deterioration: Premature deterioration of hydraulic seals can be caused by a variety of factors, one important one being high oil temperature. For every 10°C rise in temperature, the life of the hydraulic seal will be halved, so the efficient hydraulic system should be reasonably designed or a forced cooling device should be set up to keep the optimum fluid temperature below 65°C; construction machinery is not allowed to exceed 80°C. Another factor may be the compatibility of the fluid used with the sealing material, and the hydraulic fluid and hydraulic seal type and material should be selected according to the instruction manual or relevant handbook to solve the compatibility problems and extend the service life of the hydraulic seals.
