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Analysis of technical characteristics of metal plane sealing pneumatic butterfly valve
Metal plane sealing pneumatic butterfly valve is a kind of pneumatic butterfly valve, so what are its technical characteristics? The following small valves are analyzed from the characteristics, structure and working principle of the metal plane sealed pneumatic butterfly valve:
metal flat sealpneumaticbutterflyvalvespecialty
(1) The lever type opening and closing structure is adopted, so that the relative sliding between the sealing pairs is small and the relative wear is reduced.
(2) The actuator adopts a connecting rod booster mechanism. When the butterfly valve is in the closed state of this mechanism, the driving device can output a large torque, and has self-locking performance, and the work is safe and reliable.
(3) It adopts metal flat sealing structure, which has strong corrosion resistance and wear resistance, is suitable for high temperature environment, and has a long service life.
(4) The key components are optimized so that the total valve opening and closing times can reach more than 1×106 times.
(5) thevalveThe control system adopts non-contact electromagnetic reed switch, which is not limited by environmental conditions, and the signal is sensitive and accurate. It can realize remote control, pneumatic control and automatic control, and can also realize unmanned operation when it is matched with equipment.
Structure and working principle
1 Lever type opening and closing structure
Lever type opening and closing structure. When the butterfly valve is closed, the main shaft and the lever are fastened with a taper pin, and they rotate counterclockwise around point o. The lever drives the butterfly plate ab with a pin with a hole, and the butterfly plate is pushed by the compression spring to be fixed on the fulcrum n of the lever. Turn and turn. When the top b of the butterfly plate is fully in contact with the sealing surface of the valve body, the seal is achieved. The opening process is just the opposite. During the opening and closing process, the relative sliding between the sealing pairs is very small, which reduces the relative wear. In the closed state, it is an axial pressure seal, changing the traditional external force extrusion seal.
2-link booster actuator
Connecting rod booster actuator, the piston moves to the right under the action of air source pressure, the piston rod drives the power arm to slide in the box, and the connecting rod drives the rocker to rotate clockwise to output torque. And the length (h) of the connecting rod and the rocker is the same, which is equal to the distance from the center of the box body groove to the center of the output. The tank wall of the box bears the lateral thrust f, and the component force p drives the rocker to rotate. According to the force analysis, it can be known that:
p=q/cosαα=sin-1(1-sinβ)
m twist=phcos(90-α-β)=qhsin(α+β)/cos(α+β)
It can be seen from the above formula that when the β angle decreases and the α angle increases, the m torsion value increases accordingly. When β=0°, α=90° (the butterfly valve is in the closed state), the driving device outputs a large torque, but the torque during the opening and closing process is small. This characteristic just contains the operating torque curve of the butterfly valve on the curve, which meets the sealing torque required by the butterfly valve in the closed or open state.
3 plane sealing structure
In the past, the sealing pair of pneumatic butterfly valves generally used a spherical seal, and the sealing pressure was the radial extrusion force. The sealing interference cannot be adjusted arbitrarily, and the sealing performance depends on the interference of the sealing material. Therefore, the sealing material and its The amount of interference is very important. In the work, especially in the molecular sieve pre-purification process, the switching valve works in the range of 10-200 ° C. When using rubber sealing rings, the linear expansion coefficient of the rubber is very large, which is greatly affected by temperature changes, and the interference is difficult to be accurate. Sure. If the interference is large, not only the friction will be increased, but also the phenomenon of “edge gnawing” and “tongue turning” will often appear, which will make the seal invalid, and leakage will occur if the interference is small. Even if the interference is selected reasonably, and this kind of valve switches frequently, it will fail due to wear after a period of operation. If non-rubber sealing materials are used, according to the current data, their elastic deformation is very small, the radial seal interference is difficult to control, the manufacture is quite complicated, and the cost is high. At the same time, for rubber sealing materials, the constant temperature changes will cause premature aging of the rubber sealing ring due to temperature fatigue damage. For large-caliber pneumatic butterfly valves equipped with large-scale air separation equipment, it is very difficult to replace the sealing ring.
The new type of sealed pneumatic butterfly valve adopts a metal flat sealing structure. The valve disc is made of stainless steel surfacing hard alloy as a non-wearing part, and the valve seat sealing ring is made of copper-based alloy or stainless steel surfacing instead of cobalt alloy. They have strong corrosion resistance and Wear resistance, wide temperature range, can be used for a long time between -40 ~ 300 ℃, so the service life is much longer than that of rubber seals.
Since the movement mechanism of the valve plate is in the form of a lever, when the valve plate is closed, the valve plate and the valve seat form a flat contact seal, and then the lever is equivalent to a cam mechanism. If the main shaft continues to rotate, the valve plate continues to move forward to achieve a force balance. , when there is working medium pressure, it can also realize self-sealing, which ensures the reliability of sealing. When the entire sealing surface is worn, it also has the feature of automatically compensating for the amount of seal wear, thereby prolonging the service life.
Because the valve adopts a reasonable structure, its service performance is better than other domestic valves, and it has been able to replace similar foreign products.
The above is the analysis of the technical characteristics of the metal flat seal pneumatic butterfly valve brought to you by the small valve, and I hope it will be helpful to you.
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