Design and type selection of the hottest metal bel

2022-09-20
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Design and selection of metal bellows

basis for design and selection of metal bellows

in the application of bellows, the given conditions of the system (complete machine) or subsystem (component) are the main basis for the design and selection of bellows. Generally, the given design conditions are as follows:

(1) maximum space size or path

(2) nature and size of working load

(3) working displacement

(4) working temperature range

(5) nature of working medium

(6) accuracy requirements

(7) Service life

contents and principles of design and type selection of metal bellows

the main contents of design and type selection of bellows are: select the material, structural mode, geometric dimension parameters and performance parameters of bellows according to the known conditions given by the system. In the process of model selection, the requirements of the system for the use of bellows should be fully met, and the structure should be advanced and reasonable. It is best to optimize the design if conditions permit. Practice has proved that the design and type selection of bellows is very important. If the design and type selection are unreasonable, no matter how high the quality of bellows manufacturing is, the unprocessed surface of 1 cutting parts and accessories of universal testing machine should be primed and painted, which can not meet the use requirements

1. material selection

according to the use of bellows, load type and size, accuracy requirements, working medium, working temperature, service life and other known conditions, and consider the forming and welding processability of materials. Choose a suitable material. The market source should also be considered in the selection of materials

2. determine the structural type

(1) select the corrugated shape

select a more reasonable corrugated shape according to the use, performance, use requirements, performance and manufacturing characteristics of various waveforms of the corrugated pipe. In general, most choose U-shaped ripple, etc

(2) determine the number of layers of bellows

determine the number of layers of bellows according to the use of bellows, working pressure, stiffness, working medium and other factors. Under the condition that those with high working pressure not only have the advantages of raw materials, they generally choose corrugated pipes with multi-layer structure. For multi-layer corrugated pipes, it is necessary to reasonably select the number of layers and single-layer wall thickness

(3) preliminarily evaluate whether it should be used in conjunction with other elastic elements

in some cases, the bellows is used in parallel with the coil spring, which are: to improve the measurement accuracy; Occasions with high working pressure; There is impact load

(4) select the structural type of both ends of the bellows

select the structural type of both ends of the bellows, taking into account the forming process, welding process and the structural limitations of the whole system

(5) consider whether a guide device is needed

when the effective length of the bellows is relatively long, in order to avoid columnar instability in the working process, it should be considered to add a guide device. For example, bellows for valves are generally equipped with guiding devices

(6) consider whether to need a stiffening ring

in order to meet the use requirements of higher working pressure, the bellows can be strengthened with a stiffening ring, or a multi-layer structure, or a combination of these two structures can be applied. The reinforcing ring is locally strengthened, and the multi-layer structure is integrally strengthened

3. design, calculate and select the structural parameters of the bellows

ripple F. the test results can output the data situation in Excel format. The performance of the bellows depends on the structure of the bellows. The main structural parameters of the bellows include inner diameter, outer diameter, wall thickness, wave distance, wave thickness, number of corrugations, number of layers, the size of the mating parts at both ends, effective length, total length, etc. In general, users of bellows should choose bellows from relevant standards and product samples of manufacturing units, rather than designing new products. This can minimize the problems in the development, reduce the manufacturing cost and shorten the manufacturing cycle

4. Design and calculate the performance parameters of bellows

design and calculate the performance parameters of bellows after the main structural size parameters of bellows are preliminarily determined through design calculation or type selection. If the performance parameters of the bellows cannot meet the technical requirements, the geometric dimension parameters of the bellows shall be properly corrected. The technical requirements of bellows are different due to their different uses. Corresponding design methods should be formulated according to different requirements during design. The main requirements of bellows for measurement are stiffness, strength and elastic properties. Although various bellows with different geometric shapes and size parameters can meet the same stiffness requirements, the stress values generated in these bellows are different. Those schemes that can meet the stiffness requirements and produce the least stress during operation are the most reasonable. The reduction of stress not only improves the safety factor, but also reduces the influence of material elasticity on hysteresis, aftereffect, fatigue, etc., thus improving the accuracy and working reliability of bellows

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