There are many factors that affect the performance of the seals, the most common is the temperature, the higher the pressure, the greater the effect of temperature on the performance of the seal, but other factors also occupy part of the proportion, the lower edge of the force to the user to explain the impact of the hydraulic support seals The top ten factors.
1) Piston rod quenching hardness HRC55-60, chromium plating thickness 30-501m, piston rod electroplating after grinding to eliminate the grinding spiral traces.
2) Speed oil film thickness is related to reciprocating speed. If the speed is too high, the oil film will be thickened and the cattle will leak easily; if the speed is too low, less than 0.05m/s, the oil film will be too thin and the friction will increase, which will lead to “crawling”.
3) Frictional resistance The frictional resistance of the seal and moving parts varies. The frictional resistance is maximum at start-up (dry friction). When the proper speed is reached, a continuous oil film is formed between the friction pairs, and the frictional resistance decreases. When the frictional pairing movement speed is too high, the oil film becomes thicker and the frictional resistance increases.
4) Changes in temperature oil temperature affect oil viscosity, oil film thickness and sealing performance. In order to ensure good sealing performance, the working temperature of the hydraulic system should stabilize 40-80C.
5) Cleanliness The contamination control of the liquid oil is generally NAS grade, ie the concentration of the dirt particles with a diameter larger than &101m must be smaller than 3mg/100ml.
6) Contact pressure The contact pressure must be moderate in order to form a thin layer of continuous oil film. If the contact pressure is too small, the oil film is thick and easy to leak. If the contact pressure is too large and the oil film is too thin, it may cause dry friction and shorten the service life of the seal.
7) Surface roughness The surface roughness of the piston and piston rod is generally 0.8, the roughness of the seal mounting groove, side 1.6, bottom surface R3.
8) The hydraulic pressure of the hydraulic pressure cylinder can make the deformation of seals reach the sealing effect, but it also increases the wear of the sliding surface, causes heat, promotes the temperature rise of the system and further increases the sliding resistance. Therefore, it is necessary to strictly control the pressure in actual use. This is also the need to ensure the service life of the seal. For example, the service life of a 16MPa seal in a 16MPa hydraulic system is two years; in a 21MPa hydraulic system, it is shortened to two months; in a hydraulic system using 31.5MPa, the service life is only two days.
9) Medium To meet various requirements, different additives have been added to the hydraulic oil. The compatibility and service life of the additive sealant will have a major impact, and the proper sealing material must be selected according to the oil product.
10) The interstitial gap mainly refers to the fitting clearance of the sealing mounting groove or the sliding surface of the seal on the low pressure side. Under the action of hydraulic pressure, the seal will produce deformation and plastic flow, and the root of the seal tends to be squeezed into the fit clearance. In order to ensure the performance, accuracy and life of the hydraulic cylinder, the sealing structure is often provided with a guide element. The gap between the front and back of the seal friction pair differs depending on the pressure, the condition, the type of seal, and the material.
