The impeller is the core component of the centrifugal fan. However, due to the long-term influence of the air flow and the wear and tear of impurities and dust in the gas, the service life of the impeller will be greatly reduced. The replacement of the impeller is not only costly, but also delays production. Life is what many manufacturers want to achieve, so how to improve the life of centrifugal fan impeller?
Methods to improve the life of centrifugal fan impeller
1. Blade plus welding lining
The material of the impeller is generally made of alloy steel 16Mn. During use, the blades at the inlet of the impeller and the blades near the root of the rear disc are more seriously worn. For this reason, welding linings can be added to the easily worn parts of the fan blades, which can greatly improve the blades. strength and prolong the service life of the impeller. The width of the reinforcing liner is generally about 1/3 of the average height of the blade, the thickness is thinner than that of the blade, and the material is the same as that of the blade.
2. Surfacing wear-resistant layer
For a centrifugal fan with serious wear, in addition to adding a reinforcing lining, a wear-resistant layer can also be built on the outside of the reinforcing lining to improve its service life. Surface surfacing welding is to select a certain surfacing electrode (or welding wire), and manual arc (or automatic welding) surfacing on the easily worn parts of the blade to improve the surface quality of the blade, to protect the blade and improve the life of the blade. The blade surfacing electrode generally uses D212 wear-resistant electrode, which is titanium calcium surfacing electrode, and the hardness of the surfacing layer is HRC53~55, or D707 tungsten carbide surfacing electrode, and the surfacing metal contains 40~50% tungsten. Layer hardness HRC≥65.
3. Other methods
(1) Applying anti-wear coatings: At present, the main anti-wear coatings include resin anti-corrosion and wear-resistant coatings, rubber anti-corrosion and wear-resistant coatings, quartz and water glass and ceramic anti-corrosion and wear-resistant materials.
(2) Surface spray welding (spraying): The spray welding process is a process of spraying and melting self-fluxing alloy powder on the surface of the workpiece with a heat source to form a dense spray welding layer. The surface hardness of spray welding is HRC55~70.
Technical requirements for centrifugal fan impellers
In order to improve the service life of the centrifugal fan impeller without changing the performance of the fan after the strengthening measures are carried out, it is required that the impeller should meet the following basic technical requirements:
1. When the blade is welded with a lining plate, it is required that the root of the blade is broken at 6×45° and then welded. After the blade is welded, the reinforcing lining plate is welded.
2. The blade surfacing wear layer requires a width of 10mm, a thickness of 3~4mm, and an interval of 10mm, which can resist the erosion of the soot medium in multiple directions and enhance the wear resistance of the blade.
3. After the blade is reinforced, the end face runout of the front disc of the impeller is required to be ≤4.5mm.
4. After the blade is strengthened, the end face runout of the rear disc of the impeller is required to be ≤4mm, and the flatness of the rear disc should be ≤8mm.
5. After the blade is reinforced, it is required that the runout of the air inlet diameter to the main shaft should be ≤3mm.
6. The impeller is calibrated by static and dynamic balance. The outside of the front disc and the rear disc is the calibration plane. The balance weight block should not be more than two on the same correction plane, and the phase difference between them should not be greater than 90°. The distance between the edge and the outer edge of the impeller correction surface is 10mm, and the counterweight is chamfered around it.
