The history of the development of seals

Update:31-05-2019
Summary:

The seal is a material or a part that prevents fluid or […]

The seal is a material or a part that prevents fluid or solid particles from leaking from adjacent joint faces and prevents external impurities such as dust and moisture from intruding into the interior of the machine. The storage temperature of the seal is preferably below  to avoid high temperature aging of the seal. Although the rubber-plastic seal is small, its role has made it a basic component and accessory in the national economy, such as national defense, chemical, petroleum, coal, transportation and machinery manufacturing. It plays a very important role in the development of the national economy. In recent years, with the rapid economic growth, the rubber and plastic seal manufacturing industry has maintained a double-digit growth.

The data shows that in 2011, China's rubber and plastic seal manufacturing industry scale  the above enterprises (according to the statistical statistics of the National Bureau of Statistics, sales income of more than 20 million yuan to achieve a total industrial output value of nearly 10 billion, an increase of more than 20% year-on-year. Currently, China Rubber There are more than 150 enterprises in the plastic seal manufacturing industry annual income of 20 million yuan. The domestic rubber sealing industry generally shows the development situation of small enterprises and low technical level. From the perspective of enterprise economic types, private and foreign capital Enterprises account for more than 95% of the industry's main economic types.

At the same time, enterprises are basically concentrated in East China. From the perspective of the number of enterprises, sales revenue and asset size, East China has a considerable share and market concentration is high. Choose the right seal material and hydraulic oil, and adapt to the working temperature. The compatibility of the oil and the geometric position of the seal relative to the sliding parts are highly concentric. The material is as hard as chrome and the surface roughness is fine. Extend the service life. The oil seal used for hydraulic pumps and motor journals not only requires the roughness of the sliding surface to be within 0.25m of Ra, but It is required to apply hard chrome on its surface.

In the specific use, it is necessary to adjust the radial spring force of the lip of the oil seal to make it tightly elastic, and also to protect it with a mounting sleeve or shim. Sealing ring, so as to prevent the lip from rolling and twisting, causing the spring to slip out. The inner surface of the hydraulic cylinder is usually rolled, which not only improves the surface roughness, but also makes the surface cold-hardened, which is beneficial to extend the sealing ring. In addition, the pressure used, the length and type of the sliding surface have a great influence on the service life. Therefore, the "fixed inspection" time should be determined according to these conditions. The sealing surface is required to be in good lubrication and prevent intrusion of dirt. It is also a necessary condition to reach the specified cleaning level of the oil and the correct installation method.

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