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As several commonly used types, plunger pumps are important devices in electronic equipment and hydraulic systems. They have various advantages such as high rated pressure, good structure, easy operation, high efficiency, and convenient flow adjustment. So today, I will introduce to you the working principle of the plunger pump, the structure of the plunger pump and how to carry out the daily maintenance of the plunger pump.How the plunger pump worksThe plunger pump is an important device in the hydraulic system. It relies on the reciprocating movement of the plunger in the cylinder to change the volume of the sealed working chamber to realize oil absorption and oil pressure. The plunger pump has the advantages of high rated pressure, compact structure, high efficiency and convenient flow adjustment, and is widely used in high pressure, large flow and flow adjustment occasions, such as hydraulic presses, engineering machinery and ships.The plunger pump is a kind of reciprocating pump, which belongs to the volume pump. Its plunger is driven by the eccentric rotation of the pump shaft to reciprocate. Its suction and discharge valves are one-way valves. When the plunger is pulled outward, the pressure in the working chamber decreases, and the outlet valve closes. When the pressure is lower than the inlet pressure, the inlet valve opens and the liquid enters; when the plunger is pushed inward, the pressure in the working chamber increases, and the inlet valve closes. When the pressure is higher than the outlet pressure, The outlet valve opens and the liquid is discharged. When the drive shaft drives the cylinder to rotate, the swash plate pulls or pushes back the plunger from the cylinder to complete the oil suction and discharge process. The oil in the working chamber formed by the plunger and the cylinder hole communicates with the suction chamber and the oil discharge chamber of the pump respectively through the oil distribution plate. The variable mechanism is used to change the inclination angle of the swash plate, and the displacement of the pump can be changed by adjusting the inclination angle of the swash plate.Piston pump structurePiston pumps are divided into two representative structural forms: axial piston pumps and radial piston pumps; since radial piston pumps are a new type of high-efficiency pump with relatively high technical content, with the continuous development of hydraulic technology, Radial piston pumps will inevitably become an important part of the application field of piston pumps.Piston pump maintenanceThe swash plate axial piston pump generally adopts the form of cylinder rotation and end face flow distribution. A friction pair consisting of a bimetal plate and a steel oil distribution plate is inlaid on the end surface of the cylinder body, and most of them adopt the method of plane flow distribution, so the maintenance is relatively convenient. The oil distribution plate is one of the key components of the axial piston pump. When the pump is working, on the one hand, the high-pressure oil in the working chamber pushes the cylinder to the oil distribution plate; on the other hand, the oil film pressure between the oil distribution plate and the cylinder forms a The hydraulic reverse thrust of the cylinder keeps the cylinder away from the oil distribution plate. The design hydraulic pressure Fn of the cylinder to the oil distribution plate is slightly greater than the hydraulic reverse thrust Ff of the oil distribution plate to the cylinder, that is, Fn/Ff=1.05~1.1, so that the pump works normally and maintains a high volumetric efficiency.

advantage:1. The range of high and low temperature resistance is greatly enhanced, the low temperature can reach -200°C, and the high temperature can reach about 300°C, which is unimaginable for the previous forms of sealing.2. The coefficient of friction is lower. Although the sealing material of the gray ring and step seal may be the same as that of Variseal, the coefficient of friction is lower, but the coefficient of friction of the same material will be lower, especially when the working pressure is high. , the difference is very significant.3. Longer service life, if the material is commonly used by Variseal: the storage life of filled PTFE and stainless steel is theoretically unlimited, and the service life is longer than other forms of seals, and it is also unlimited under some working conditions Period, which is very important for some special-purpose cylinders.4. Resistant to high pressure and ultra-high pressure. Generally, standard designed pan-seal rings can withstand a pressure of 20-30MPa. By changing the design parameters, it is easy to withstand a pressure of more than 100MPa.5. Under high and low pressure, the leakage is small. Variseal rings can have good sealing performance under high and low pressure, while other forms of sealing are either good in high pressure resistance or low pressure resistance, and it is difficult or even impossible to have good high pressure resistance and low pressure resistance at the same time. achieve.6. The installation groove is small, and the standard size of the installation groove is the same as that of O-rings of the same level.shortcoming: 1. The installation groove is generally open or semi-open, especially for small-diameter cylinders, which must be open or semi-open, which may increase the cost for the design, manufacture and installation of the cylinder.2. The manufacturing process of seals is turning forming, the production efficiency is low, and the manufacturing cost is higher than that of ordinary seals, so the purchase cost of seals will be higher.Typical application conditions:1. High temperature sealingModern industrial cylinders require high-temperature cylinder seals in many places, such as pressure casting cylinders, metallurgical cylinders, kiln cylinders, automotive engine seals, etc., and the maximum temperature reaches about 300°C.2. Cryogenic sealingLiquefied nitrogen, liquefied petroleum gas, liquefied carbon dioxide, liquefied oxygen, etc. are sealed, and the lowest temperature can reach -200°C.3. High pressure sealingSuper-large tonnage presses, high-pressure water cutting machines, air compressors, etc., with a maximum pressure of 400MPa.4. High-speed sealingHigh-speed shaft, the speed can reach 30-40 meters per second. High-speed reciprocating oil cylinder, the telescopic speed can reach 15-20 meters per second.5. Special working medium sealHigh temperature water vapor, sea water, brake fluid, acid and alkali, etc.6. Low frictionA typical example is a servo cylinder.7. Long life sealWind power variable pitch cylinder, building shock absorption cylinder.8. Long oil cylinder sealTypical examples are crane cylinders and stacker cylinders.9. Hygienic and safe sealingAt present, the sealing of food and medicine contact has basically adopted the Pansythen ring.10. Quick response cylinderThe installation groove of the seal is small, the structural parts of the oil cylinder can be lighter, and the frictional resistance is small at the same time, which can greatly improve the dynamic performance of the oil cylinder and create a better quick-response oil cylinder.

Variseal seal and comparison with O and U ringsVariseal, the word comes from the transliteration of "Variseal", which means composite seal and combined seal, usually refers to spring energy storage seal, and is the abbreviation of spring variseal (spring composite seal)."Fanseal" itself is a transliteration of "composite seal", so there is no need to add the word "seal" after "Fanseal". If you call it according to the custom, you can add this word. Of course, it is better to directly say "spring energy seal" according to Chinese.The figure on the right shows the typical structure of Variseal, which is divided into two different parts, the inner and outer parts. The outer seal body is made of special functional plastic, and the inner part is made of stainless steel spring made of special material.The materials of the seal body and the spring are different due to different working conditions and working media. Generally, the materials of the seal body include: pure tetrafluoroethylene, filled tetrafluoroethylene, ultra-high molecular weight polyethylene, polyimide, polyether ether ketone, etc. The materials of stainless steel springs generally include SUS301, SUS304, SUS316 and SUS718.The external seal body is in contact with the two surfaces to be sealed and acts as a seal, so it requires low friction coefficient, high strength, wear resistance, working medium resistance, and high temperature or low temperature resistance in the working environment.The internal stainless steel spring provides pressure for the external seal body, so that the seal lip is always tightly pressed against the sealing contact surface to prevent leakage, especially when the internal pressure is low, zero pressure or even negative pressure, The spring is the only source of sealing pressure. The requirements for the spring are relatively simple: high and low temperature resistance to the environment, corrosion resistance, and relatively constant elastic force. Although these requirements are not many, they are not easy to achieve. The material, process and shape of the spring have high requirements.Variseal is a sealing form developed in recent years. Like the combined seals such as Gray ring and Step seal, it fully utilizes the superior performance of each component material, so that the overall performance far exceeds any single material seal. Compared with previous seals in various forms, it has both significant advantages and obvious defects.

Everyone should have heard of the panseal seal, which is a kind of sealing part with excellent use effect. Today, the editor will share with you some knowledge about Pansyphon. Do you know what are the characteristics of the use of pansyphon? What are the components of a panseal? The following is an introduction to the description of the use characteristics of the universal plug seal and the detailed introduction of its components.[Composite composition and application characteristics of pan-seal seals]Panseal (full name: Panseal spring tension energy storage support seal, also known as spring tension seal, spring energy storage seal) is a seal made of polytetrafluoroethylene or other high-performance materials with special springs inside. The force plus the system fluid pressure pushes the sealing lip (surface) out and gently presses the metal surface to be sealed to generate a very good sealing effect. The actuation effect of the spring can overcome the slight eccentricity of the metal mating surface and the wear of the sealing lip, while maintaining the expected sealing performance continuously. It can be used in oil, water, steam, air, solvents, medicines, food, acid and alkali, chemical solutions, etc.As the main material of pan-seal housing, PTFE has better chemical resistance than perfluoroelastomer, and is a sealing material with good heat resistance. It can be applied to most chemical fluids, solvents, hydraulic oils, and lubricating oils. Its expansion is very small, so it can exert its sealing performance for a long time. Various special springs are used to overcome the elasticity of Teflon or other high-performance rubber plastics Problems, developed to replace the vast majority of seals used in static or dynamic (reciprocating or rotary motion). Description of the use characteristics of the pan-seal ring and detailed introduction of the components Reasonable shell material and support spring plus professional seal design can make the pan-seal seal use temperature range from -200°C to 260°C and pressure from vacuum to ultra-high pressure 200Mpa, the line speed is as high as 15m/s, so it can be applied to various high and low temperature corrosive fluids and other occasions.Universal seals can be made according to AS568A standard O-ring grooves (such as radial shaft seals, piston seals, axial face seals, etc.), completely replacing general-purpose O-rings, or our company can provide reasonable groove designs. Panseal can maintain good sealing performance for a long time because it does not suffer from swelling. For example, mechanical shaft seals used in high-temperature corrosive environments in petrochemical processes, the common cause of leakage is not only the uneven wear of the sliding ring, but also the cracking damage of the O-ring. After changing to a pan-seal, the rubber softening and swelling can be completely improved. , surface roughness, wear and other problems, thus greatly improving the service life of the mechanical shaft seal. Panseal is suitable for both dynamic and static applications. In addition to the above-mentioned sealing applications in high-temperature corrosive environments, it has low sealing lip friction coefficient, stable sealing contact pressure, high pressure resistance, and allows large radial deflection and groove size errors. Therefore, it is very suitable for the seal of the air hydraulic cylinder, replacing the U-shaped or V-shaped compression to obtain excellent sealing performance and service life.Product features: The sealing performance is not affected by insufficient lubrication when starting, effectively reducing wear and friction resistance. Through the combination of different sealing materials and springs, different sealing forces can be displayed to meet various application requirements. It is processed by dieless CNC with high dimensional progress, especially suitable for large quantities and various seals. Chemical corrosion resistance and heat resistance are far superior to commonly used rubber seals. Dimensions are stable, and there is no problem of sealing performance degradation caused by volume expansion or shrinkage. Compact structure fits in standard O-ring grooves. Because the sealing material is polytetrafluoroethylene or other high-performance materials, it is very clean and will not pollute, and the friction coefficient is extremely low, even in extremely low-speed applications, and there is no stick-slip effect. The starting friction resistance is small, even if the machine stops for a long time or runs intermittently, it can maintain low starting force performance.