How is the elasticity of welded metal bellows calculated?

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Since this type of seal does not use a spring and the elastic force is entirely generated by the bellows, its elasticity must be taken into account during the design of the bellows. Generally, the elasticity of the bellows is designed to be low; when a certain level of resilience is required, the compression amount of the bellows must be increased appropriately. After operating for a considerable length of time, if the sealing surface wears out, the bellows compensate automatically, and the loss in elasticity is not significant, ensuring that there is always a sufficient pressure ratio at the sealing surface. To ensure sufficient elasticity, the compression amount is around 10 mm. It must not be less than 6mm. During operation, the deformation of each wave should be kept small; to ensure a certain degree of compression, the wave number must be increased appropriately while maintaining the wave spacing. The normal wavenumber is typically set between 16 and 20; higher temperatures and pressures require a higher wavenumber. The spring rate of a bellows is a function of its geometry and material, and is commonly calculated using the following formula. file:///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml2668/wps2.png Where k is the elasticity of the bellows, in N/mm ； E — Elastic modulus of the material at operating temperature, N/mm2 ； t — waveplate thickness, mm ； n——bellows wavenumber ； d1, d2 —— are the inner and outer diameters of the bellows, in mm ； B — Width of the bellows, in mm. The formula B=(d2-d1)/2 does not take into account factors such as the cross-sectional shape of the waveplate, and therefore there is a certain degree of error. In practical work, its elasticity can be measured using a spring dynamometer. The calculation of the elasticity of ordinary springs can be found in general books on \"mechanical parts\", so it will not be explained here.