What are the regulations for qualified seals

(1) Good sealing performance It is the main requirement for seals or sealing devices, and it is the performance that the seal must have, otherwise it is not a seal or a fake seal. One of the key indicators of good sealing performance is that qualified seals (sealing devices) are installed in qualified four-column hydraulic parts (that is, their geometrical figure specifications *density, roughness, void value, etc. are all in compliance with the regulations), under the required standards (Temperature, working pressure, etc.) During operation, his seal is specified, and the leakage rate is zero or no leakage, and is relatively stable; whether there is zero leakage or no leakage, the decision is made according to the regulations. As far as the seal or its inability to do itself (not referring to the actual machine), its sealing performance is determined by several factors: on the one hand, the structure and cross-section of the seal (seal device) are fluid dynamics. , Elastic mechanics, oil slick and other basic theories. On the other hand, the choice of materials for seals is *, and there is also the best technology for manufacturing seals (sealing devices).

(2) Good reliability. It is a requirement for the required performance of the sealing device and the sealing device. If it is unstable, this will definitely reduce the effectiveness of the seal (seal device), and even make the seal ineffective. Therefore, the seal (sealing device) must have good reliability.

A. Have *chemical properties* First stipulate that the seal (seal device) must not have any chemical reaction with the sealed liquid and liquid working substance, and the seal (seal device) is not allowed to melt or corrode with the sealed liquid; No chemical reaction is allowed with other parts.

B. Physics reliability The seal (sealing device) is immersed in the liquid working substance, so it is not allowed to be solubilized, nor is it allowed to crack; it is not easy to cause deterioration tendency to the oxygen and sunlight; the seal (seal Device) After bearing the force in the hydraulic fittings (in the hydraulic transmission system), the permanent deformation must not be left behind, and there will be immediate or minor permanent deformation, and the seal (sealing device) will be affected by the physical elements. , He always maintains his original situation or maintains the original trend-physical reliability.

C. Reliability of the geometric figure position The seal (sealing device) is accurately installed in the channel of the effective part according to the machining process, and installed with another part to form a hydraulic fitting. During work, the seal (sealing device) cannot bear the force, which will cause distortion or extrusion, cutting or turning over, which will destroy the proper part of the original device in the part duct and destroy its tightness, so be sure to install it The geometric figure behind is stable.

(3) With fully automatic compensation and follow-up seals or sealing devices, as time increases, their wear rate will also increase. In order to ensure the actual effect of the seal, the seal (sealing device) should have a fully automatic follow-up compensation function. Some shaft seals, such as the seals of hydraulic cylinders in hydraulic cylinders, are usually due to the effect of wheel weight or their non-parallelism. The full circle cover map of the hydraulic cylinder and the seals installed in the cylinder sleeve will touch on the full circle. The contact level is unlikely to be the same, so the seal (seal device) should have followability, especially for the seal of the rotating shaft, which is more significant. Generally, the followability of the vulcanized rubber seal is less than 0. Mm.

(4) It should have a wide range of sealing pressure. Since the load of general hydraulic equipment is constantly changing when machinery and equipment is in operation, when he starts to work, his fluid material has been pressured from the bottom to the high pressure, so seals are required (Sealing device) Not only can it have excellent sealing performance at the bottom pressure, but at high pressure, the excellent sealing performance should still be reliable. At this stage, the working pressure of the seal (sealing device) is 0-40Mpa. If the working pressure of the seal is very high, usually some seals can seal the high pressure, and the bottom pressure cannot be sealed very well. At this time, the sealing system software uses two types of high-pressure and low-pressure seals to ensure that they are properly sealed.

(5) Have a wide range of integration temperature. Because hydraulic equipment often works in different natural environments, sometimes in cold temperate regions, and sometimes in high-temperature places, seals (sealing devices) must be integrated Office environment, workplace changes during work. That is to say, the seals (sealing devices) should have good performance in high temperature resistance. At this stage, some seals have a high temperature range of -200-250℃.

(6) Long life The so-called long life refers to the longest time for the sealing of the seal (seal device). If the sealing of the seal lasts for a long time, the seal (seal device) must always maintain its qualified original condition , That is, the original structure and shape, stable specifications, process performance, ductility and resilience, etc. This regulation is reflected in the following aspects.

A. The seal (sealing device) must have sufficient excellent structural mechanical properties. It has a certain degree of strength, resistance, cutting resistance, and tensile strength. It is not easy to destroy itself due to its bearing capacity. It is malleable and has the ability to fully deform.

B. The seal (sealing device) should have very good wear resistance. If it is a dynamic seal, when the seal (seal device) is working under operation, it has a relative speed with the sealing surface. If there is a relative speed, there will be friction and wear. If you want to prevent the seal (seal device) from being worn out To jeopardize the effective time of the seal, the friction factor of the seal (seal device) is small and the material is wear-resistant.

C. Not only reasonable configuration, but also production and processing specifications * quasi-stable (withstand force deformation, fatigue * complex)

(7) The structure is simple, effective, easy to manufacture, easy to install and disassemble, helpful for maintenance, disassembly, and high quality and low price.

(8) The seal (sealing device) must not have defects such as scratches, tears, scratches, burrs, vents, etc.

(9) It should have tolerance matching, standardization, integration and generalization.

(10) Possess the most qualitative performance. Considering that the seal (sealing device) must take into account both its performance and its price.

(11) The geometrical specifications of the seal (sealing device) are as small as possible, that is, the volume is as small as possible. It not only saves raw materials, but also reduces the size of hydraulic parts.