Hydraulic system is the bloodline of modern continuous production line, and its importance is self-evident. When the system runs for a period of time, oil pollution will inevitably occur. It is understood that more than 90% of the failures of hydraulic and pneumatic systems in the industry are caused by pollution, such as scratches and leakage of hydraulic cylinders, pressure fluctuations caused by cylinder operation, and valve oil Road blockage, actuator blockage, hydraulic component loss acceleration (filter element, pump), etc. So how to effectively deal with pollution is a key factor to ensure the normal operation of the hydraulic system.
The contaminants of hydraulic oil are mainly composed of metal wear debris from hydraulic cylinder body wear, seal wear debris, water and dust particles. The source of pollution is the seal, and there are three reasons for the pollution.
1. Failure of hydraulic cylinder seal.
At present, the seals commonly used in domestic hydraulic cylinders are traditional nitrile rubber (NBR) or polyester polyurethane (PU) standard Yx rings as the sealing ring. The main problems in use are: ①Material hydrolysis failure, such as hydraulic Commonly used polyester polyurethane cylinder. ②The seal wears and fails. When the hydraulic cylinder is worn, the water and dust in the air will enter the hydraulic cylinder through the worn dust ring, which is often not a cause for concern.
On-site maintenance personnel often pay little attention to the wear of hydraulic cylinder seals, and slight wear will not cause too much attention. Even if they are replaced, they will only replace some of the seals, and ignore the overall changes. The integral seal is no longer suitable for the sealing groove of the original hydraulic cylinder. The seals of each part of a hydraulic cylinder are very important. They complement each other, interact and restrict each other, and form an organic whole.
2. The seal of the hydraulic pipe joint fails.
The pipe joint sealing of the hydraulic system mainly adopts O-rings and combined washers. O-rings are mostly fluorine rubber O-rings, and most of the combined seals are combined seals of nitrile rubber and metal. However, ordinary domestic fluororubber O-rings have low dimensional accuracy, poor temperature resistance, compression resistance and corrosion resistance, and are prone to installation damage, excessive extrusion deformation, chemical corrosion, and thermal corrosion during installation and use. The generated debris will enter the hydraulic system with the hydraulic oil to cause pollution. Combined gaskets are processed by molds, with low dimensional accuracy, rough surface, and poor pressure-bearing performance. Under local high-pressure load conditions, they are prone to failure and collapse, losing a lot of hydraulic oil, and their debris will also pollute the hydraulic system.
3. Secondary pollution occurs during maintenance.
In the process of on-site maintenance, maintenance personnel do not pay attention to on-site cleaning, and bring dust and debris into the system when replacing oil pipes, valves and hydraulic cylinders, so that pollutants have more chances to enter the system.
Therefore, improving the variable seal, adopting more reasonable sealing materials, improving the sealing accuracy, and changing the variable seal structure not only solve the leakage problem, but also prevent the entry of pollutants.
Aiming at the pollution control problem of the hydraulic system, the hydraulic cylinder seal and pipeline seal of the system are surveyed and analyzed, the complete hydraulic system seal is improved, and the international advanced sealing material and processing technology are adopted to upgrade the hydraulic system of the cold rolling mill. , Including the cylinder block seals of important hydraulic cylinders and pipeline seals, all seals are customized according to the specific conditions of the equipment.
1. Seal upgrade of hydraulic cylinder.
① Material upgrade.
The polyether polyurethane material with low friction coefficient is used to replace the traditional polyester polyurethane. The seal is the vulnerable part in the hydraulic cylinder. Its own friction coefficient, anti-wear, anti-hydrolysis, anti-aging, anti-extrusion and other properties determine its sealing effect, environmental adaptability, and wear and abrasion to the cylinder. The amount of debris generated is closely related to the life cycle of the seal.
②The size is accurately controlled and the interference is adjusted reasonably.
At present, almost all domestic seal rings adopt the method of mold processing, and the hydraulic cylinder is constantly worn in various degrees during the movement, which affects the service life of the cylinder body.
Internationally advanced turning processing technology is widely used in the production of rubber seals used in repairs. According to the wear of hydraulic cylinders, tailored clothing can achieve high requirements for seal dimensional accuracy.
2. Upgrade of pipe joint sealing.
Imported DuPont VITON fluoroelastomer materials are used to process O-rings by turning technology, which solves the problems of material anti-aging, anti-extrusion, anti-corrosion ability, and poor processing accuracy, improves the service life of O-rings, and reduces fuel consumption.
②Upgraded combination washer.
The combined washer of polyether polyurethane 2Cr13 is used, and the pressure resistance can reach 100MPa, which solves the problem of rough processing and pressure difference of the original gasket.
In addition to the above leakage prevention and leakage prevention measures, daily maintenance and management should be strengthened, short-term planned inspection system should be implemented, and the quality and quantity of each scheduled annual repair should be guaranteed, and maintenance and operation personnel should be trained and theoretically studied. In this way, the pollution source control of the hydraulic system will definitely achieve good results, reduce the loss of hydraulic oil, and reduce the production cost.
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