Development and application of eccentric butterfly CSGO¾º²Â
In many Asia Pacific countries, due to the limitations of their own CSGO¾º²Â design and manufacturing level, as well as the influence of traditional textbooks, there is still a great prejudice against butterfly CSGO¾º²Âs. At the same time, the advanced developed industrial countries in Europe and America are vigorously promoting and actively using butterfly CSGO¾º²Âs.
Butterfly CSGO¾º²Â is not the same as it used to be.
The performance of butterfly CSGO¾º²Â is closely related to its development. In order to meet the requirements of various working conditions, butterfly CSGO¾º²Â has experienced the evolution from concentric to single eccentric, double eccentric and triple eccentric. The evolution of butterfly CSGO¾º²Â and the development and application of 3 eccentric butterfly CSGO¾º²Â are briefly introduced as follows:
1¡¢ Classification of butterfly CSGO¾º²Âs
1. Concentric butterfly CSGO¾º²Â
The structure feature of the butterfly CSGO¾º²Â is that the shaft center of the CSGO¾º²Â rod, the center of the butterfly plate and the center of the body are in the same position. The structure is simple and the manufacture is convenient. The common rubber lined butterfly CSGO¾º²Â belongs to this type. The disadvantage is that the butterfly plate and CSGO¾º²Â seat are always in the state of extrusion and scraping, with large resistance distance and fast wear. In order to overcome extrusion, scratch and ensure sealing performance, the CSGO¾º²Â seat is basically made of elastic materials such as rubber or polytetrafluoroethylene, but it is also limited by temperature in use. This is why people traditionally think that butterfly CSGO¾º²Âs are not resistant to high temperature.
2. Single eccentric butterfly CSGO¾º²Â
In order to solve the problem of extrusion between butterfly plate and CSGO¾º²Â seat of concentric butterfly CSGO¾º²Â, a single eccentric butterfly CSGO¾º²Â is produced. Its structural feature is that the shaft center of CSGO¾º²Â rod deviates from the center of butterfly plate, so that the upper and lower ends of butterfly plate no longer become rotary axis, disperse and reduce the excessive extrusion between upper and lower ends of butterfly plate and CSGO¾º²Â seat. However, due to the single eccentric structure in the whole process of CSGO¾º²Â opening and closing, the scraping phenomenon between butterfly plate and CSGO¾º²Â seat has not disappeared, and the application range is similar to that of concentric butterfly CSGO¾º²Â, so it is not used much.
3. Double eccentric butterfly CSGO¾º²Â
On the basis of single eccentric butterfly CSGO¾º²Â, the most widely used double eccentric butterfly CSGO¾º²Â is further improved. The structure feature is that the shaft center of the CSGO¾º²Â rod deviates from the center of the butterfly plate and the center of the body. The effect of double eccentricity makes the butterfly plate break away from the CSGO¾º²Â seat immediately after the CSGO¾º²Â is opened, which greatly eliminates the unnecessary excessive extrusion and scratch between the butterfly plate and the CSGO¾º²Â seat, reduces the opening resistance, reduces the wear and improves the service life of the CSGO¾º²Â seat. The large reduction of scraping, at the same time, the double eccentric butterfly CSGO¾º²Â can also use metal seat, which improves the application of butterfly CSGO¾º²Â in the field of high temperature. However, because the sealing principle belongs to position sealing structure, that is, the sealing surface of butterfly plate and CSGO¾º²Â seat is in line contact, and the elastic deformation caused by squeezing the CSGO¾º²Â seat through butterfly plate produces sealing effect. Therefore, the requirements for closing position are very high (especially for metal CSGO¾º²Â seat), and the pressure bearing capacity is low. This is why people traditionally think that butterfly CSGO¾º²Â is not resistant to high pressure and has large leakage.
4. Triple eccentric butterfly CSGO¾º²Â
To withstand high temperature, hard seal must be used, but the leakage is large; to zero leakage, soft seal must be used, but not resistant to high temperature. In order to overcome the contradiction of double eccentric butterfly CSGO¾º²Â, the third eccentricity of butterfly CSGO¾º²Â was carried out. The structural features of the structure are that the conical axis of the butterfly plate sealing surface is inclined to the cylinder axis of the body while the shaft center of the double eccentric CSGO¾º²Â rod is eccentric. That is to say, after the third eccentricity, the sealing section of the butterfly plate is no longer true circle, but ellipse, and the shape of its sealing surface is asymmetric, one side is inclined to the body center line, and the other side is parallel to the body center line.
??? The biggest feature of this third eccentricity is that it fundamentally changes the sealing structure. It is no longer a position seal, but a torque seal. That is to say, it does not rely on the elastic deformation of the CSGO¾º²Â seat, but completely depends on the contact surface pressure of the CSGO¾º²Â seat to achieve the sealing effect. Therefore, the problem of zero leakage of the metal CSGO¾º²Â seat is solved at one stroke. Because the contact surface pressure is proportional to the medium pressure, it is also resistant to high pressure and high temperature It's the edge.
Development of two and three eccentric butterfly CSGO¾º²Âs
Since the advent of the three eccentric disc CSGO¾º²Â, in order to meet the increasingly stringent requirements of working conditions, it has also experienced the process of self-improvement and continuous development. Even if the most basic zero leakage and three eccentric disc CSGO¾º²Â can be achieved in theory, it still depends on careful design and precise manufacturing.