Stem and the ball joint and the stem and the valve body should be in contact with an anti-static mechanism to prevent electrostatic accumulation in the sphere. Stem safety design should be prevented under the pressure of work was "blowing out" to prevent the blowout of the stem of the annular ring handle ring to reduce the friction coefficient.
The characteristics of the traditional stem processing technology
1. The traditional stem thread helical flying knife, thread accuracy is not allowed; the use of traditional chip-free rolling easy to damage rolling mold, easy deformation, distortion.
2. Polish part of the grinding machine using the accuracy is not high, long time-consuming,
3. Inverted parts of the folder twice with U-turn pull down the seal, poor concentricity, inverted seal easy to leak.
4. The end of the mill indexing machine indexing, slow processing, multi-process, time-consuming.
Valve stem manufacturing process features:
1. The new stem thread self-extrusion, high thread strength, accuracy standards.
2. Threaded parts and polished rod parts of the concentric, overcome the long-troubling domestic thread rolling process easily twisted, fragile rolling wire mold problems.
3. polished rod parts to achieve the mirror effect, easy opening and closing, good sealing.
4. Inverted parts of a CNC molding technology, high precision, inverted off sealing performance.
5. The end of the T-slot using forging molding process, high efficiency, low cost.
6. Set of stem production technology reached the international advanced level.
In the strong corrosion, volatile and harmful process conditions, once the stem seal is damaged, strong corrosion, volatile and harmful process media leak from the stem of the control valve will cause serious environmental and personal safety as a result of. The use of bellows stem seal form is a way to solve the above problems. Bellows are generally made of stainless steel. This special bonnet structure protects the stuffing box of the control valve from fluid contact. Once the bellows is broken, the stuffing box structure above the bellows prevents the serious consequences of rupture of the bellows. In engineering practice, the choice of bellows seal should take full account of the bellows seal pressure rating will decrease with increasing temperature, the fluid can not have solid particles exist, and the bellows material longest cycle of action life . Stainless steel is not resistant to corrosion in some of the strong corrosive process sites, such as the process medium is wet chlorine, the chlorine gas contained in the wet chlorine stainless steel bellows will soon be corroded.
In progress, the development of science and technology is also getting faster and faster, the new valve stem manufacturing technology to reduce costs, improve work efficiency, more in line with the requirements of the modernization. In addition, the bellows shut-off valve manufacturers suggest that the choice of stem material is also an important work in its production process, I hope do not ignore this important factor.
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