Sealing rings and vane bushings are generally made of non-ductive steel or tin bronze. The seal ring and vane bushing made of stainless steel have a long service life, but the quality of the processing and assembly is very high. Otherwise, it is easy to engage in the operation due to the slightly smaller clearance and the slightly more curved shaft. If it is made of tin bronze, it is easy to process, low in cost, and difficult to bite, but its anti-scouring performance is relatively poor.
After the newly machined seal ring and vane bushing are installed in position, the concentricity deviation from the impeller should be less than 0.04 mm. The radial clearance of the seal ring to the impeller varies with the inner diameter of the seal ring. The clearance between the seal ring and the pump casing is generally 0.03~0.05mm.
The gap between the vane bushing and the impeller hub is generally 0.40~0.45mm. An interference fit is used between the bushing and the vane, and the interference is 0.015~0.02mm, and it needs to be fastened with a set screw.
Measuring method and correction of shaft bending
1. Place the pump shaft on a dedicated rolling gantry or use a lathe or V-iron to support it.
2. The recorded values of each section should be measured 2~3 times. The reading error of the pump shaft to the wheel end face mark should be within 0.05mm. During the measurement, the angle of each rotation should be the same, and the direction of rotation should be consistent. When the rotor is rotated after the dial gauge is installed, it is generally recorded from the second point, and the value of the second point should be the same as the original number after one rotation.
