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Form Analysis of Hydraulic System LeakageThe leakage of the hydraulic system is the phenomenon that the working medium flowing or temporarily stored in the hydraulic components and the system cavity flows from the high pressure cavity to the low pressure cavity or from the system to the outside of the system through the non-working channel. Leakage is a common phenomenon in metallurgical hydraulic equipment. Leakage may occur in all links from power components to actuators, which is determined by the nature of hydraulic transmission. However, once the leakage exceeds the allowable range, it becomes a leakage failure, which is not allowed and must be effectively controlled.Hydraulic system leakage can be divided into fixed seal leakage and moving seal leakage according to the leakage location. Fixed seal leakage mainly includes leakage of the sealing surface of the valve and valve block, leakage at the connection of the oil cylinder port, leakage at the connection of the motor oil port, and leakage at the connection of the oil pump inlet and outlet; leakage of the moving seal mainly includes leakage of the pump spindle, motor Spindle leakage, extended valve stem leakage and hydraulic cylinder piston rod leakage, etc.According to the form of oil leakage, it can be divided into internal leakage and external leakage. External leakage mainly refers to the leakage of hydraulic oil from the inside of the system to the external environment; internal leakage refers to the flow of hydraulic oil from the high pressure side to the low pressure side inside the system due to the existence of pressure differences between the high and low pressure sides of the system and the failure of seals. Among them, due to factors such as many internal leakage incentives, wide distribution of related components, and difficulty in direct monitoring, coupled with the fact that internal leakage is the main factor affecting the working efficiency of the hydraulic system, excessive internal leakage will cause fluctuations in the control accuracy and efficiency of the hydraulic system. The stability and reliability are reduced, and even the original design function is lost. Internal leakage has become the top priority of hydraulic system prevention and control.

1. Hydraulic seal O-ringThe seal with a circular cross-section can achieve sealing by eliminating the gap by pre-compression, and can automatically increase the contact stress between the seal and the sealing surface as the pressure increases, thereby improving the sealing effect. It can be used for static sealing of high-pressure end faces and cylindrical surfaces, and can also be used for low-pressure reciprocating dynamic sealing of low-pressure moving speed. Inexpensive, simple, good sealing, automatic compensation after wear and tear.2. Various sealing gaskets for hydraulic sealingCombined sealing gasket is a combined sealing gasket made of oil-resistant rubber inner ring and steel outer ring, which is easy to install and reliable in sealing. It is mostly used for end face sealing of threaded pipe joints, etc.3. Sealant for hydraulic sealsThe sealant has fluidity and can fill the gap between the two joint surfaces, and it can seal and prevent leakage under a certain tightening force. According to the nature of the film formed between the two bonding surfaces, it can be divided into four types: dry adhesion type, dry peelable type, non-dry sticky type and semi-dry viscoelastic type. It is divided into two categories: liquid sealant and anaerobic sealant.After dry peelable coating, the solvent volatilizes quickly to form an elastic film, which is easy to peel off from the adhesive. It has good vibration resistance, but it is easy to volatilize and is difficult to use on a large area.The non-drying sticky sealant does not dry for a long time after application, and always maintains viscoelasticity. Therefore, it has good detachability, high vibration resistance and impact resistance, and is suitable for large-area coating.The semi-dry viscoelastic type is between the above two and has the advantages of both.Anaerobic sealants are suitable for pressure-resistant sealing of some small surfaces such as threaded pipe joints, which can prevent impact loosening and leak-proof.The application method of liquid sealant and anaerobic sealant is: pretreatment (remove oil, rust, decontamination) → coating (coating 0.06-0.1mm) → drying → fastening.

Construction machinery anti-icing dust ring introductionTechnical application:This technology can scrape off hard objects such as ice slag and cement solidification attached to the piston rod of construction machinery, avoid damage to the cylinder seal by hard objects, and prolong the life of the oil cylinder.Technical points:1. Polyoxymethylene is used as the base material, which has high hardness, small friction coefficient and good wear resistance.2. O-shaped spring provides preload.3. Double lip structure.Technical advantages:1. The hardness of the matrix material is relatively high, which can scrape off hard objects such as cement slag and ice slag attached to the piston rod;2. The O-shaped sheet spring has a large resilience, and the lip is close to the piston rod to scrape off the dust particles in the general environment.3. The matrix material has a small friction coefficient and good wear resistance, which can prolong the service life of the dust seal.4. The double-lip structure scrapes dust more cleanly.

Advantages of mechanical seal relative to packing seal: ①Reliable sealing During long-term operation, the sealing state is very stable and the leakage is very small. According to rough statistics, the leakage is generally only 1/100 of the soft packing seal; ②Long service life can reach 1-2 years or longer in oil and water medium, and can reach more than half a year in chemical medium; ③Small frictional power consumption The frictional power of the mechanical seal is only 10% to 50% of that of the soft packing seal; ④ The shaft or sleeve is basically free from wear; ⑤The long maintenance cycle can automatically compensate after the end face is worn, and under normal circumstances, no frequent maintenance is required; ⑥ Good vibration resistance, insensitive to the vibration and deflection of the rotating shaft and the deflection of the shaft to the sealing chamber; ⑦ Wide range of application Mechanical seals can be used for low temperature, high temperature, vacuum, high pressure, different speeds, and various corrosive media and media containing abrasive particles. The disadvantages of mechanical seals relative to packing seals are: ①Complicated structure, high requirements for manufacturing and processing; ②Installation and replacement are cumbersome, and workers are required to have a certain level of installation skills; ③ It is difficult to deal with accidental accidents; ④ High one-time investment.