Author： FOSHAN BOWAH VACUUM EQUIPMENT CO.,LTD
Vacuum bellows can be divided into two categories: spiral bellows and annular bellows according to the shape of the wave. All the corrugations can be connected by a spiral line; the annular corrugated pipe is a tubular shell with a closed circular corrugation, and its corrugations and corrugations are connected by a series of annular corrugations. The annular bellows can be divided into U-shaped, C-shaped, S-shaped, V-shaped, and Q-shaped bellows due to the nature of the waveform. In order to improve the bearing capacity, multi-layer (mostly double-layer and three-layer) corrugated pipes and corrugated pipes with reinforcing ribs in the middle have been continuously developed.
Metal bellows components have a wide temperature range and are generally given before the design and manufacture of elastic components. Some special-purpose bellows pass through liquid oxygen (-196℃) or lower-temperature liquid nitrogen in the inner cavity, and the pressure resistance is up to 25MPa. Large-scale corrugated expansion joints (nominal diameter sometimes exceeding lm) used for pipe network system connection require a pressure bearing of 4MPa, temperature resistance of 400°C, and a certain corrosion resistance stability. The temperature adaptability of the elastic element depends on the temperature resistance of the elastic material used. Therefore, according to the operating temperature range of the elastic element, the elastic material with appropriate temperature performance parameters can be selected to process and manufacture qualified bellows components.
Various expected load values act on metal bellows and other elastic elements, such as concentrated force F, pressure p, and moment M, etc. When metal bellows-like elastic elements are used, in addition to the given load value, the action direction and action position of the load must also be given. For pressure loads, also specify whether the elastic element is subjected to inner cavity pressure or outer cavity pressure.
The maximum load value or full-scale value that the metal bellows and other elastic components are allowed to use under normal working conditions. It is usually an expected design value or a revised design value after the actual testing of the product prototype.
There are two states when the elastic element is under working; one is to work under a certain load and displacement, and keep the load and displacement always unchanged or rarely change, which is called static work; the other is the use of load and displacement. Continuous cycle to and fro alternately. The element is in cyclic operation. Due to different operating conditions, the modes of component damage or failure are also different. The elastic-sensitive element of the instrument works within the elastic range, basically in a static working state, and has a long service life, generally reaching tens of thousands to hundreds of thousands of times. The bellows components used in engineering sometimes work in the elastic-plastic range or in the state of alternating stress, and the life span is only hundreds of dry times. The components must be given an allowable working life when they are cyclically working, and the number of cycles, time, and frequency must be specified.
The rated life of the elastic element is the expected service life determined when the element is designed, and it is required that the element is not allowed to fatigue, damage, or fail during this period.