Bellows are tubular elastic sensing elements connected by folding corrugated sheets in the direction of bending and expansion. Bellows are widely used in devices and meters. Their main purpose is to serve as a measuring element of pressure measuring devices to convert pressure into displacement or force. The bellows has a thinner wall and higher sensitivity, the measurement range is from tens of Pascals to tens of MPa. Its open end is fixed, the sealed end is in a free state, and an auxiliary helical spring or tongue is used to increase elasticity. During operation, it stretches along the length of the pipe under the action of internal pressure, causing the movable end to produce a displacement that is in a certain dependence on the pressure. The movable end sets the pointer in motion, directly indicating the pressure. The bellows is often combined with a displacement sensor, forming a pressure sensor whose output signal is electricity, and is sometimes used as an insulating component. Since the expansion of the bellows requires a greater change in volume, its response speed is lower than that of the Bourdon tube. Bellows are suitable for low pressure measurement.
Bellows mainly include metal bellows, corrugated expansion joints, corrugated heat exchange tubes, membrane capsules and metal hoses. Metal corrugated pipes are mainly used to compensate for thermal deformation of pipelines, absorb shock and deformation of pipeline settlement. They are widely used in petrochemical, instrument making, aerospace, chemical, electric power, water, metallurgy and other industries. Corrugated pipes made of plastic and other materials play an indispensable role in media transportation, electrical wiring, machine tools, household appliances and other fields.
Bellows: An elastic component for measuring pressure in pressure measuring instruments. It is a cylindrical thin-walled corrugated shell with many transverse corrugations. The corrugated tube is elastic and can produce displacement under the action of pressure, axial force, lateral force or bending moment. Bellows are widely used in instruments and meters. Their main purpose is to serve as a measuring element of pressure measuring devices to convert pressure into displacement or force. The bellows has a thinner wall and higher sensitivity, the measurement range is from tens of Pascals to tens of MPa. In addition, bellows can also be used as sealing insulating elements to separate two media or prevent harmful liquids from entering the measuring part of the device. It can also be used as a compensating element, using the variability of its volume to compensate for the temperature error of the device. Sometimes it is also used as an elastic connecting joint between two parts. Corrugated pipes can be divided into metal corrugated pipes and non-metal corrugated pipes according to their constituent materials, and according to the structure - into single-layer and multi-layer; Single-layer corrugated pipes are widely used. Multi-layer corrugated pipes have high strength, good durability and low loads and are used for important measurements. Bellows materials are commonly bronze, brass, stainless steel, monel alloys and inconel alloys.
Technical Parameters
Load-bearing capacity
The various expected load values acting on metal bellows and other elastic components, such as concentrated force F, pressure p and moment M, etc. When using elastic elements such as metal bellows, in addition to the value of the applied load, the direction and location of the load must also be specified. For compressive loads, it must also be specified whether the elastic element withstands the pressure of the inner cavity or the pressure of the outer cavity.
The maximum load value or full scale value that metal bellows and other elastic components can withstand under normal operating conditions. This is usually the expected design value or the design value revised after actual testing of a prototype product.
The load-bearing capacity of a particular elastic element product where the rated load is allowed to be exceeded momentarily or during testing without damage, failure or instability. For elastic-sensitive instrument components, the overload capacity is usually limited to 125% of the rated load. Bellows components used in engineering are usually limited to 150% of the rated load. According to engineering requirements, when a large safety margin is required, the elastic element used stipulates that overload is not allowed, so the load must be less than or equal to the nominal
