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Manufacturer of various types of compensators, metal bellows expansion joints, and corrugated metal hoses
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2018
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Design and selection of metal bellows
In the application of bellows, the conditions given by the system (whole machine) or subsystem (component) are the main basis for the design and selection of bellows. The general given design conditions are as follows:
Basis for design and selection of metal bellows
In the application of bellows, the conditions given by the system (whole machine) or subsystem (component) are the main basis for the design and selection of bellows. The general given design conditions are as follows:
(1) Maximum spatial dimensions or diameter
(2) Nature and size of workload
(3) Working displacement
(4) Operating temperature range
(5) Nature of the working medium
(6) Accuracy requirements
(7) Service life
Contents and principles of metal bellows design and selection
The main contents of bellows design and selection are: selecting the material, structural form, geometric size parameters and performance parameters of the bellows according to the known conditions given by the system. In the selection process, the system's requirements for the use of bellows should be met, and efforts should be made to achieve advanced and reasonable structures. Optimize the design if conditions permit. Practice has proved that the design and selection of bellows is very important. If the design and selection are unreasonable, the quality of the bellows manufacturing will not meet the use requirements no matter how high it is.
1. Material selection
According to the known conditions such as the purpose of the bellows, the type and size of the load, the accuracy requirements, the working medium, the working temperature and the service life, and considering the forming and welding processability of the material, a suitable material is selected. The material selection also needs to consider its market source.
2. Determine the structural type
(1) Select the corrugation shape
Choose a more reasonable corrugation shape based on the purpose, performance, use requirements of the bellows, and the performance and manufacturing characteristics of various waveforms. In general, most people choose U-shaped corrugations.
(2) Determine the number of bellows layers
The number of layers of the bellows is determined according to the purpose of the bellows, working pressure, rigidity, working medium and other factors. In the case of high working pressure, multi-layer bellows are generally selected. For multi-layer bellows, the number of layers and single-layer wall thickness need to be reasonably selected.
(3) Preliminary assessment of whether to use with other elastic elements
In some cases, bellows are used in parallel with coil springs: to improve measurement accuracy; when the working pressure is relatively high; when there is impact load.
(4) Select the structural type of both ends of the bellows
When selecting the structural type of the two ends of the bellows, it is necessary to consider the forming process, welding process of the two end structures and the structural limitations of the entire 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 during operation, it is necessary to consider adding a guide device. For example, bellows for valves are generally equipped with a guide device.
(6) Consider whether a reinforcement ring is needed
In order to meet the requirements of higher working pressure, the bellows can be reinforced with a reinforcing ring, or a multi-layer structure, or a combination of the two structures. The reinforcing ring is a local reinforcement, and the multi-layer structure is an overall reinforcement.
3. Design, calculation and selection of bellows structural parameters
The performance of the bellows depends on its structure. The main structural parameters of the bellows include the inner diameter, outer diameter, wall thickness, wave pitch, wave thickness, number of corrugations, number of layers, the size of the matching parts at both ends, effective length, total length, etc. In general, users of bellows should select bellows from relevant standards and product samples of manufacturing units, rather than designing new products. This can reduce the problems in the development process, while also reducing manufacturing costs and shortening the manufacturing cycle.
4. Design and calculate the performance parameters of the bellows
After the main structural dimension parameters of the bellows are initially determined through design calculation or selection, the performance parameters of the bellows are designed and calculated. If the performance parameters of the bellows cannot meet the technical requirements, the geometric dimension parameters of the bellows should be appropriately corrected. The uses of bellows are different, and their technical requirements are also different. When designing, corresponding design methods should be formulated according to different requirements. The main requirements for bellows used for measurement are usually stiffness, strength and elastic properties. Although a variety of bellows with different geometric shapes and dimensional parameters can meet the same stiffness requirements, the stress values generated in these bellows are different. Those solutions that can meet the stiffness requirements and generate less stress during operation are reasonable. The reduction of stress not only increases the safety factor, but also reduces the influence of material elasticity on hysteresis, aftereffect, fatigue, etc., thereby improving the accuracy and working reliability of the bellows.
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Address: 398 Bailong Road, Louzhuang Town, Jiangyan District, Taizhou City, Jiangsu Province
Chairman: Yuan Wenbao
Phone number: 860523-88608579
Fax: 86 0523-88607688
Website:www.jshuixin.com.cn
E-mail:jsjymajun@hotmail.com
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