Water pumps in the long-term operation process, there will often be water pump bearing frame bearing chamber wear, bearing wear, cracks in the pump body rupture, pump cavitation, scouring wear and so on. After the above problems, the traditional solution is to patch welding or brush plating after machining repair, but both have certain disadvantages: the thermal stress generated by the high temperature of the patch welding can not be eliminated, easy to cause material damage, resulting in bending or fracture of the parts; and brush plating by the thickness of the coating is limited, easy to flake off, and the above two methods are metal to metal repair, can not change the "hard-to-hard" fit relationship, the pump body will be damaged. The above two methods are using metal to repair metal, can not change the "hard to hard" relationship, in the combined effect of the forces, will still cause wear and tear again. Contemporary western countries for the above problems more use of polymer composite repair method, which has a strong adhesive force, excellent compressive strength and other comprehensive performance. Application of polymer material repair, can be free of disassembly and machining. Neither welding thermal stress impact, repair thickness is not limited, while the product has the metal material does not have the concessions, can absorb the impact of the equipment vibration, to avoid the possibility of wear and tear again, and greatly extend the service life of the equipment components, for the enterprise to save a lot of downtime, create great economic value.
Static balance of the impeller
Water pump rotor working at high speed, if its mass is not balanced, the rotation will produce a large centrifugal force, resulting in water pump vibration or damage. The balance of the rotor is achieved through the mass balance of its components (including shafts, impellers, bushings, balance disks, etc.), so the new replacement of the impeller should be static balance calibration work. Specific methods are:
(1) the impeller mounted on the false shaft, put on the static balance test bench has been adjusted level. There are two tracks on the test bench, and the dummy shaft can roll freely on it.
(2)Mark the impeller on the heavy side. If the mass of the impeller is not balanced, the heavier side is always automatically turned down. In the symmetrical position of the heavy place (i.e., the lighter side) to increase the weight of the block (with the surface of the sticky or with a clamp to increase or decrease the iron sheet), until the impeller can be in any position can be stopped until.
(3) Weigh the mass of the weighted block. Not in the lighter side of the impeller to add weight, but in the heavier side by reducing the weight of the method to achieve the balance of the impeller. Weight reduction, available milling machine milling or grinding wheel (when the removal is not large), but note that the depth of milling or grinding shall not exceed 1/3 of the thickness of the impeller cover. impeller after static balancing, static balancing allowable deviation value shall not exceed the value of the outer diameter of the impeller and the product of 0.025g/mm. For example, the impeller diameter of 200mm, the allowable deviation is 5g.
Coupling disassembly
(1) when removing the coupling, can not be directly hit with a hammer and should be padded with a copper rod, and should be played at the hub of the coupling can not be played at the outer edge of the coupling, because this is very easy to be broken. The best way is to disassemble the coupling with a captive. For small and medium-sized pumps, because of its fit with a small amount of interference, so the coupling is very easy to take down. For larger pumps, the coupling and shaft with a large interference, so the coupling must be heated when disassembled. (2) When assembling the coupling, pay attention to the serial number of the key (for couplings with more than two keys). If a brass rod is used for hammering, attention must be paid to the part of the hammering. For example, knocking the shaft hole at the end of the surface, easy to cause the shrinkage of the shaft hole, so that the shaft can not go through; knocking the outer edge of the wheel, it is easy to destroy the straightness of the end face, in the future with a ruler to find the correctness of the accuracy of the measurement will be affected. For couplings with a large amount of excess, it should be heated before loading.
(3) Coupling pins, nuts, washers and rubber gaskets must ensure that their respective specifications, the same size, so as not to affect the dynamic balance of the coupling. Coupling bolts and the corresponding coupling pin hole should be marked accordingly to prevent misinstallation.
(4) the coupling and the shaft are generally used with the transition fit, there may be a small amount of interference, there may also be a small amount of clearance, the hub longer coupling, can be used with a looser transition fit, because of its longer shaft hole, due to the surface machining of the rough and uneven, in the assembly of the natural part of the overfill. If it is found that the fit between the coupling and the shaft is too loose, which affects the concentricity of the hole and the shaft, then it should be patch welded. Spackling or padding copper skin on the shaft is a stopgap measure and can not be used as an ideal method.