In the threaded fasteners, the support surfaces of the bolts, foam gaskets screws and nuts can not be made very large (subject to material and process restrictions). To reduce the compressive stress of the bearing surface, the gasket is used to protect the surface of the joint.
In order to prevent loosening of the connection loops, foam gaskets the use of anti-loose spring washers and multi-toothed locking washers, round nut stop washers and saddles, corrugations and conical elastic washers.
Flat washers are mainly used to reduce the pressure, foam gaskets when some parts tighten the axial force is very large, easy to make the gasket into a dish, then you can use the material and improve the hardness to solve.
Spring gasket locking effect in general, foam gaskets important parts as little or no use, and the use of self-locking structure. For high-speed tightening (pneumatic or electric) spring washers, it is best to use surface treatment of the gasket, improve its wear performance, or easy to friction and heat burned or mouth, or even damage the surface of the connector. For sheet connections, foam gaskets spring washers should not be used. According to statistics, the spring washer in the car to use less and less.
For the spring washers, elastic washers, according to the national standard, foam gaskets generally choose GB699-1999 "high-quality carbon structural steel" in the 60, 70 steel and 65Mn steel.
China's flat washer standard a total of nine, from 2000 to 2002, respectively, approved the release of the GB / T97.3-2000, GB / T5286-2001, GB / T95-2002, GB / T96.1-2002, GB / T96.2 -2002, GB / T97.1-2002, GB / T97.2-2002, GB / T97.4-2002 and GB / T5287-2002 flat washers.
Liquid seal: With the rapid development of polymer organic synthesis industry, in recent years there have been liquid sealant, used in static seal; this new technology, foam gaskets usually called liquid seal. The principle of liquid seal is the use of liquid sealant adhesion, mobility and monomolecular membrane effect (the thinner the natural recovery of the membrane tend to), under appropriate pressure to make it like a gasket to play the same role. So the use of the sealant, also known as liquid washers.
Graphite plate seal: in people's impression, foam gaskets graphite is brittle material, lack of flexibility and toughness, but after special treatment of graphite, but it is soft texture, good elasticity. In this way, the thermal resistance and chemical stability of the graphite can be displayed in the gasket material; and the gasket has a small pressing force and the sealing effect is excellent. foam gaskets This kind of graphite can also be made with the belt, with the metal band with excellent performance of the winding washers. Graphite plate seals and graphite - metal spiral washers appear, is a major breakthrough in high temperature corrosion resistance seal. Such gaskets, foam gaskets foreign countries have been mass production and use.