Most foreign oil seal lip pieces adopt moulded threaded type

At present, most foreign oil seal lip pieces adopt moulded threaded type, while domestically, the tued threaded type is basically adopted.. However, due to its complex structure, large pressing force and low life span, it is rarely used. By tuing the thread on the end surface, the follow-up type of the shaft is improved, so that the sealing performance, especially the static sealing, can be greatly improved. 

This kind of oil seal was developed in the 1980s and is called the first Five-generation products. The second generation is Japan's Arai company invented a paste type seal, which is to paste a layer of PTFE film on the side of the original rubber sealing lip to improve the rubber sealing performance. However, due to the complex bonding process and high cost, the performance is improved. Not many and cannot be widely adopted. Until 1975, the American Mather company first proposed a wide lip structure of PTFE seal, called the fourth generation product, that is, the PTFE material is first pressed into a circular sheet, then pulled into a ho shape, and then clamped in the metal.  

 In the shell, there is a layer of rubber elastic sheet in the middle. Because PTFE has high self-lubricating properties, the lips are not easy to bu out. It uses the function of the thread groove to make a layer of oil film on the shaft surface receive the thrust of the thread groove, thereby preventing the oil film from leaking outward.PTFE was first used in the military industry and was not used for static sealing elements until the 1950s. 

The seal of this new structure is obviously different from the previous Gas Top Protectorsrubber seals, not only the structure is simple, no coil spring is needed, and the contact area with the shaft is wide, generally 3~4mm. However, the inner wall of the lip of this type of seal is smooth and the oil sealing effect is not good. Therefore, a dynamic seal with a 'reverse-rotating thread groove' engraved on the inner wall of the lip appeared. 

The first generation of PTFE seals was made of PTFE rods by tuing or pressing into products similar to rubber seals, but it quickly failed. Beginning in the 1970s, some large foreign companies imagined using PTFE to replace rubber to make lip seals. Later, the company introduced the third-generation seal, which uses PTFE material to draw a ho-shaped membrane, covered with a spring leaf, wrapped a coil spring, and used it to load the lip. The emergence of the fifth generation of products has made a qualitative leap in the lip-shaped rotary seal