Common repair method of centrifugal pump impeller
The centrifugal pump will be gradually worn and corroded due to the erosion of sediment, water flow, and corrosion of the medium. The surface of the blade often forms grooves or streaks, or is damaged by cavitation, and the blade has honeycomb holes or even perforations. If the blade is cast with air holes, sand holes or slag inclusions, air holes or even cracks are likely to appear on the surface after operation.
There are many methods for repairing the impeller of the water pump. There are many methods for repairing the impeller cavitation, such as ARC polymer composite material coating, powder spraying (welding), epoxy resin coating, and rubber and nylon composite material repair, etc. Using stainless steel inlay, surfacing and so on. The use of epoxy resin polymer coating has the advantages of simple construction method, low price and so on, and the effect is good.
By optimizing the ratio and adjusting the performance indexes of the materials in a targeted manner, it shows high-strength adhesion and toughness to absorb impact energy, and has high strength and hardness against cavitation and abrasion damage.
Common repair methods:
1. Copper wire repair method
For pinhole-shaped cavitation, as long as the holes are not connected into pieces, you can use copper wire to penetrate the pinhole and file with a file. Before treatment, first remove the rust and dirt on the surface of the blade with a polisher, then use oxygen-acetylene flame to blow off the impurities in the air hole, and then fill the hole with the appropriate thickness of copper wire, and at the same time hit with a sharp hand hammer to remove the copper The wire is squeezed and squeezed into the hole and finally flattened with a file.
2. Gas welding repair method
Put the impeller on a charcoal fire and heat it to 400-500℃, hang tin at the repair welding place, and then use an oxygen-acetylene flame to melt the brass wire into the groove or hole to be repaired. Remove the charcoal fire after welding and use asbestos The board is covered with heat insulation to allow the blades to cool slowly to avoid cracks. After welding, use a file to process and trim according to the original contour.
3. Quick steel repair method
Rapid steel is a cement-like adhesive repair agent before curing. After curing, it has high strength, high hardness, no shrinkage, and no rust. It is suitable for filling pores, cracks, sand holes, etc. that occur in metal materials such as steel and iron. Repair, with strong bonding effect. Before repairing, clean and roughen the floating rust and dirt around the area to be repaired. Take out the colloid in the instant steel plastic tube, knead the two materials of different colors of the inner core and the outer skin of the colloid quickly and fully into one color (about 1~2min) by hand, it is better to achieve heat and softness. Before the instant steel colloid should be solidified, it is firmly adhered to the repaired place, and it is compacted several times as the colloid is solidified (hand or tool) to enhance the adhesion of the glue to the blade. After the hardened steel is hardened, file it with a file.
4. Epoxy resin repair method
Take appropriate amount of epoxy resin, ethylenediamine, dibutyl phthalate, and acetone in a glass vessel according to the mixing ratio and order, mix and mix well. Pay attention to the viscosity of the adhesive when stirring, and add an appropriate amount of acetone. The prepared epoxy resin should be used up within 20-30min. Dip the epoxy resin with a wool brush, brush the surface of the trachoma and stomata on the surface of the blade, use a pointed cone to gently squeeze out the air bubbles between the trachoma and the stomata, apply as much as possible, and at the same time use a scraper real. After the epoxy resin is cured for 1-2h, then apply 2-3 times. Make sure that the surface of the blade is smooth and smooth during the final application. After painting, the impeller is placed in an environment of 20-30°C and a relatively low relative humidity, and slowly cured for 48h. After the epoxy resin is fully cured, use a file or polisher to trim the contours of the impeller and the protrusions on the surface layer.
5. Surfacing repair method
Before surfacing, grind the cavitation erosion parts with a grinder to clean the rust and debris on the surface until the bright metal body is exposed, so that the surfacing layer and the blade are more firmly combined. After cleaning, place the impeller in a charcoal fire for preheating. Use welding rods or stainless steel welding rods with the same material as the blades, without peeling or damaging, keep dry and remove moisture, so as to avoid air holes in the surfacing. During surfacing welding, round-trip welding is required, and layered cross-pressure welding can also be adopted. The amount of surfacing welding should be small each time to prevent the blades from being heated and concentrated and generating stress and deformation. After repair welding, use a polisher to trim the blades. After the repair, the impeller must be tested for static balance. In order to prevent the impeller from rotating at high speed, the centrifugal force is generated due to the imbalance of the additional weight and the pump vibrates.
