Maintenance Scheme of Water Pump

During the long-term operation of water pumps, wear of bearing chamber, bearing position, crack rupture of pump body, cavitation and erosion of water pumps often occur. After the above problems occur, the traditional solution of enterprises is repairing or repairing after brush plating, but both of them have some drawbacks: the thermal stress caused by high temperature of repairing welding can not be completely eliminated, which can easily cause material damage and lead to bending or fracture of parts; while brush plating is limited by the thickness of coating, easy to peel off, and the above two methods are repairing metal with metal, which can not change the “hard”. For the “hard” coordination relationship, under the combined action of various forces, it will still cause re-wear. In contemporary western countries, polymer composites are mostly used to repair the above problems. They have super adhesion, excellent compressive strength and other comprehensive properties. It can be repaired with high polymer materials without disassembly and machining. There is no effect of repair welding thermal stress and repair thickness is not limited. At the same time, the metal material of the product does not have the retreat ability, which can absorb the shock and vibration of the equipment, avoid the possibility of re-wear, and greatly prolong the service life of equipment components, save a lot of downtime for enterprises, and create huge economic value.

Static Balance of Impeller


When the pump rotor works at high speed, if its mass is not balanced, a large centrifugal force will be generated when it rotates, which will cause vibration or damage of the pump. The balance of the rotor is achieved by the mass balance of its components (including shaft, impeller, sleeve, balance disk, etc.). Therefore, the static balance check of the newly installed impeller should be carried out. Specific methods are:


(1) Install the impeller on the false axle and place it on the static balance test bench with the adjusted level. There are two tracks on the test bench, on which the false axle can roll freely.


(2) Mark on the heavier side of the impeller. If the impeller mass is unbalanced, the heavier side will always automatically turn below. In the symmetrical position (i.e. the lighter side) where the emphasis is placed, add heavy blocks (using surface sticking or clamping to increase or decrease iron sheets) until the impeller can stop at any position.


(3) weigh the weight of the weighting block. The balance of the impeller is achieved by reducing the weight on the heavier side rather than on the lighter side of the impeller. When reducing weight, milling machine or grinding wheel can be used (when removal is not large), but attention should be paid to the depth of milling or grinding should not exceed 1/3 of the thickness of impeller cover plate. After static balancing, the allowable deviation of static balancing should not exceed the product of outer diameter of impeller and 0.025 g/mm. For example, an impeller with a diameter of 200 mm has an allowable deviation of 5 g.


Dismantling and assembling of coupling


(1) When removing the coupling, the copper rod should be padded instead of hammer, and the hub of the coupling should be hit instead of the outer edge of the coupling, because it is very easy to be damaged here. The best way is to dismantle the coupling with a captive. For small and medium-sized pumps, the coupling is easy to take down because of its small interference. For larger pumps, the coupling and shaft fit have larger interference, so the coupling must be heated when disassembled. (2) When assembling coupling, attention should be paid to the serial number of key (for coupling with more than two keys). When striking with a copper rod, attention must be paid to the striking part. For example, when tapping the end face of the shaft hole, it is easy to cause the shaft hole to shrink, so that the shaft can not pass through; when tapping the outer edge of the wheel, it is easy to destroy the flatness of the end face, which will affect the accuracy of the measurement in the future when the plunger is used to align. For the coupling with larger interference, it should be heated and installed again.


(3) The pins, nuts, washers and rubber pads of the coupling must be kept in accordance with their specifications and sizes so as to avoid affecting the dynamic balance of the coupling. Corresponding markings should be made on the coupling bolts and the corresponding coupling pin holes in order to prevent misalignment.


(4) Transitional fit is generally used for coupling and shaft. There may be a small amount of interference or a small amount of clearance. Looser transition fit can be used for coupling with longer hub. Because of its long shaft hole and rough surface processing, some interference will occur naturally after assembly. If it is found that the fit between coupling and shaft is too loose, which affects the concentricity of holes and shafts, it should be repaired. It is an expedient measure to dot the axle or pad the copper sheet, which can not be used as an ideal method.