Design And Selection Of Metal Corrugated Pipe

In the application of metal corrugated pipe, the conditions given by the system (the whole machine) or subsystems (components) are the main basis for the design and selection of the bellows. Generally given design conditions have the following items:

(1) Maximum space size or diameter

(2) The nature and size of the working load

(3) Work displacement

(4) Operating temperature range

(5) The nature of the working medium

(6) Precision requirements

(7) Service life

The main content of metal corrugated pipe design and selection is: according to the known conditions given by the system to select the material of the bellows, structural penalty, geometric size parameters and performance parameters. In the selection process, the system's requirements for the use of bellows should be fully satisfied, and the structure should be advanced and reasonable. It is best to optimize the design when possible. Practice has proved that the design and selection of the bellows is very important. If the design and selection are unreasonable, the quality of the bellows manufacturing will not meet the requirements of use, no matter how high.

1. Material selection

According to the purpose of the metal corrugated pipe, the type and size of the load, the accuracy requirements, the working medium, the working temperature and the service life and other known conditions, and the forming of the material and the welding processability are considered. Choose a suitable material. The choice of materials must also consider their market sources.

2. Determine the structure type

Choose the corrugated shape

Choose a more reasonable corrugated shape according to factors such as the purpose, performance, use requirements of the corrugated pipe, and the performance and manufacturing characteristics of various waveforms. In general, U-shaped corrugations are mostly selected.

Determine the number of bellows layers

Determine the number of layers of the bellows according to factors such as the purpose of the bellows, working pressure, stiffness, and working medium. In the case of high working pressure, the multi-layer structure of the corrugated pipe is generally selected. For the multi-layer corrugated pipe, the number of layers and the single-layer wall thickness should be selected reasonably.

Preliminarily assess whether to combine with other elastic elements

In some cases, the bellows and the coil spring are used in parallel. These cases are: In order to improve the measurement accuracy; the working pressure is relatively high; the impact load.

Select the structure type of the two ends of the bellows

To select the structure type of the two ends of the bellows, it is necessary to consider the forming process of the two ends structure, the welding process and the structural restrictions of the entire system.

Consider whether a guiding device is needed

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

Consider whether to use reinforced ring

In order to meet the requirements of higher working pressure, the bellows can be reinforced with a reinforcing ring, or a multi-layer structure can be used, or a combination of these two structures can be used. The strengthening ring is partially strengthened, and the multi-layer structure is integrally strengthened.

3. Design calculation and selection of structural parameters of metal corrugated pipe

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 matching parts at both ends, effective length, total length, etc. . In general, users of bellows should choose bellows from the relevant standards and product samples of the manufacturer, rather than designing new products. This can minimize the problems in development, while reducing manufacturing costs and shortening the manufacturing cycle.

4. Design and calculate the performance parameters of metal corrugated pipe

After the main structural size parameters of the bellows are initially determined by 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 size parameters of the bellows should be appropriately modified. Different uses of bellows have different technical requirements. Corresponding design methods should be formulated according to different requirements during design. The bellows used for measurement usually mainly require stiffness, strength and elasticity. Although a variety of bellows with different geometric shapes and size parameters can meet the same rigidity requirements, the stress values generated in these bellows are different. Those solutions that can not only meet the rigidity requirements, but also produce the least stress during work 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., thereby improving the accuracy and working reliability of the corrugated pipe China.

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