Vacuum bellows type

vacuum bellows concept

The so-called vacuum bellows refers to the axisymmetric tubular shell, whose generatrix is corrugated and has certain bendability, so it is also called flexible pipe or flexible pipe. Because of its geometric characteristics, the bellows can change its axial length under the action of pressure, axial force, transverse force and bending moment. Under the action of tensile force, the length of bellows is extended; under the action of compression force, the length of bellows becomes shorter. The length or bending capacity of bellows is determined by the value and direction of force and the performance parameters of bellows. It is different from the smooth tube (plate tube) in that it has not only certain strength and stiffness, but also large flexibility and high fatigue resistance. These properties make the bellows have a very wide range of applications

vacuum bellows basic types

According to the shape of the wave, vacuum bellows can be divided into spiral bellows and annular bellows: spiral bellows is a tube-shaped shell with spirally arranged waves, and there is a helix angle between the corrugations and the corrugations, and all the corrugations can be connected by a spiral line; the annular bellows is a closed circular pipe-shaped shell with corrugated between its waves It is composed of circular corrugations in series.

Because of the same waveform, annular bellows can be divided into U-shaped, C-shaped, S-shaped, V-shaped and q-shaped bellows. In order to improve the bearing capacity, the multi-layer (mostly double-layer and three-layer) bellows and the bellows with stiffeners in the middle are continuously developed.

According to the material, bellows can be divided into metal bellows and non-metallic bellows. Metal bellows include metal bellows, bellows expansion joints and metal corrugated hose. Metal bellows are mainly used as a component of bellows elastic components. According to the processing technology, it can be divided into hydraulic forming bellows, welding forming bellows, electrodeposited bellows, nuclear rubber forming bellows, spinning forming bellows, pressing forming bellows and mechanical expanding bellows, etc.

Non metallic bellows include quartz bellows, rubber bellows, polyester bellows and plastic bellows. Nonmetallic bellows have the advantages of corrosion resistance, heat resistance and aging resistance. Among them, the bellows made of quartz, rubber, polyester and PTFE in plastic bellows are generally used as part of elastic components, mainly to complete measurement, connection, compensation, sensing, sealing, shock absorption and other functions. The plastic corrugated pipe introduced in this chapter refers to a new type of plastic pipe used for piping, transportation, water supply and drainage, installation and other applications.