Design calculation of elastic components of mechanical seal-

Design and calculation of elastic components of mechanical seal

　2017-09-04　　

Design calculation of elastic components of mechanical seal:

The function of the elastic element in the mechanical seal: On the one hand, a certain pre-tightening force is generated on the end face of the seal, so that the end face of the seal can maintain a good combination when starting, stopping or when the medium pressure fluctuates. On the other hand, it is used to overcome the friction between the auxiliary sealing ring and the shaft and move the compensation ring axially to compensate for the gap formed after the end face of the seal is worn. In addition, it can cushion the vibration caused by the beating of the shaft (or sleeve).

The elastic components used in modern mechanical seals mainly include springs and bellows. There are various types of springs such as cylindrical spiral compression springs, disc springs, wave leaf springs, rectangular springs and metal diaphragm springs, among which cylindrical spiral compression springs are the most widely used. The types of bellows include metal bellows (welded metal bellows and hydraulic metal bellows), PTFE bellows and rubber bellows. Bellows are often used in special conditions such as high temperature, low temperature, and strong corrosion.

The design calculation of cylindrical spiral compression spring is to first calculate the spring force according to the product of the selected spring specific pressure and the contact area of u200bu200bthe end surface

Then calculate and check the torsional stress according to the spring material and the assumed spring diameter D, spring wire diameter 4 and number of working turns d. At the same time, the allowable limit load of the spring is the working load of each spring.

The schematic diagram of the cylindrical spiral compression spring is shown in Figure 2-12, and the calculation items and formulas are listed in Table 2-9.

Figure 2-12 Schematic diagram of cylindrical spiral compression spring

Table 2-9 Calculation parameters of cylindrical spiral spring

The recommended values u200bu200bof the main parameters of cylindrical spiral compression springs are shown in Table 2-10

Table 2-10 Recommended values u200bu200bof main parameters of cylindrical spiral compression springs

If you want to design cylindrical spiral compression springs, you can refer to the fourth volume cylindrical spiral compression spring design section of the Mechanical Design Manual (Chemical Industry Press). This section has detailed design requirements and steps.

In mechanical seals, the working shrinkage (deformation) of the spring will gradually decrease with the wear of the end face of the seal, reducing the spring force. In order to ensure the necessary spring specific pressure, the drop value shall not exceed 10%~20% of the initial value.

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