Bellows type load cell, also known as curved beam structure sensor, adopts metal bellows welding and sealing form. When the use environment is very harsh, if the sensor is not effectively and reliably sealed, the sensor will fail in a short time. In order to ensure that the sensor can work normally and stably for a long time in this environment, many companies' products generally use fully sealed metal bellows. This fully sealed method is a very effective solution, ensuring the reliability and long-term stability of the sensor.
The metal bellows is an important component of the sensor, which plays a role of sealing and protection. It is one of the most commonly used elastic sensitive components. It is an axially symmetrical cylindrical thin-walled tubular shell with multiple transverse corrugations. Due to its geometric shape, it can elongate or shorten along the axis under the action of pressure or axial force, resulting in large displacements. Or output a concentrated force. If a transverse force that produces a bending moment is applied to it, a corresponding displacement can be produced in the axial plane.
Types and corrugated shapes of metal bellows
Metal corrugated pipes can be divided into integral corrugated pipes pressed from thin-walled cylindrical pipe blanks (the pipe blanks can be drawn seamless pipes, or they can be rolled into cylinders from sheets and then welded along longitudinal straight seams ) and a welded bellows made of metal diaphragms with a certain corrugated surface that are welded to each other along its inner and outer edges.
Metal corrugated pipes can be divided into ring corrugated pipes and spiral corrugated pipes according to the distribution of corrugations. According to the number of layers, it can be divided into single-layer corrugated pipe and multi-layer corrugated pipe. When the total thickness is the same, multi-layer corrugated pipes have higher strength, lower rigidity, lower working stress and longer service life than single-layer corrugated pipes. Especially for bellows that need to work in some special strong corrosive media, different materials can be used for each layer. The layer in contact with the corrosive medium can be made of corrosion-resistant materials, and other layers can be made of materials with good elastic properties.
Basic properties of metal corrugated pipes
3.1   Elastic properties
The relationship between the input parameter and the output parameter is called the characteristic of the elastic element. If the input parameter is the pressure p, the output parameter is the displacement W. The relationship between p and W is the characteristic of the component, expressed in mathematical form: W=f(p), f represents the functional relationship between the two. Elastic properties can be linear or nonlinear (decreasing or increasing). The linear relationship between the two is a linear characteristic. For nonlinear characteristics, if as the load increases, the displacement generated by the unit load becomes smaller and smaller, it is a tapering characteristic. On the contrary, as the load increases, the displacement generated by the unit load becomes larger and larger, which is a tapering characteristic. Increasing characteristics
Bellows are important basic components in aviation, aerospace, chemical industry, shipbuilding, nuclear engineering and various instruments and regulating accessories. It produces corresponding displacement under the action of external loads (such as uniform force, axial force, lateral force and bending moment, etc.) and can be used as elastic sensitive components, mechanical seal components, media isolation components, connecting components and temperature compensation components. .
Bellows are widely used in instrumentation. The main purpose is to serve as a measuring element of pressure measuring instruments to convert pressure into displacement or force. The bellows has a thinner wall and higher sensitivity, with a measurement range of tens of Pascals to tens of MPa. In addition, bellows can also be used as sealing isolation elements to separate two media or prevent harmful fluids from entering the measuring part of the device. It can also be used as a compensation element, using the variability of its volume to compensate for the temperature error of the instrument. Sometimes it is also used as an elastic connection joint between two parts. Corrugated pipes can be divided into single layer and multi-layer according to their structure. Single-layer corrugated pipes are widely used. Multi-layer corrugated pipes have high strength, good durability and low stress, and are used in important measurements. The materials of metal bellows are generally bronze, brass, stainless steel, Monel alloy, etc.
The development trend of bellows and its components focuses on the development of elastic materials, design calculations, technology and equipment, and detection technology.