1. shaft
Pumps with very long shafts are prone to insufficient shaft rigidity, too much deflection, and poor shaft straightness, causing friction between the moving part (drive shaft) and the static part (sliding bearing or mouth ring), resulting in vibration. In addition, the pump shaft is too long, which is greatly affected by the impact of the flowing water in the pool, which increases the vibration of the underwater part of the pump. Excessive clearance of the balance disc at the shaft end or improper adjustment of the axial working displacement will cause the shaft to move at low frequency and cause the bearing bush to vibrate. The eccentricity of the rotating shaft will cause bending vibration of the shaft.
2. the drive device frame and foundation
The fixed form of contact between the drive device frame and the foundation is not good, and the foundation and the motor system have poor ability to absorb, transmit, and isolate vibration, which causes the vibration of the foundation and the motor to exceed the standard. The foundation of the water pump is loose, or the water pump unit forms an elastic foundation during the installation process, or the foundation stiffness is weakened due to oil-soaked water bubbles, the water pump will produce another critical speed with a phase difference of 1800 from the vibration, which will increase the vibration frequency of the water pump. The frequency is close to or equal to the frequency of an external factor, which will increase the amplitude of the pump. In addition, the loosening of foundation anchor bolts results in a decrease in restraint rigidity and aggravated motor vibration.
3. the coupling
The circumferential spacing of the coupling connecting bolts is poor, and the symmetry is destroyed; the coupling extension section is eccentric, which will produce eccentric force; the coupling taper is out of tolerance; the coupling static or dynamic balance is not good; elasticity The fit between the pin and the coupling is too tight, so that the elastic pin loses its elastic adjustment function, causing the coupling to not be well aligned; the coupling gap between the coupling and the shaft is too large; the mechanical wear of the coupling rubber ring The coupling performance of the rubber ring is reduced; the quality of the transmission bolts used on the coupling is different from each other. These reasons will cause vibration.
4. the motor structural parts
The motor structural parts are loose, the bearing positioning device is loose, the iron core silicon steel sheet is too loose, and the bearing stiffness decreases due to wear, which will cause vibration. Mass eccentricity, uneven rotor mass distribution caused by rotor bending or mass distribution problems, resulting in excessive static and dynamic balance. In addition, the squirrel cage bar of the squirrel cage motor rotor is broken, causing the magnetic field force of the rotor and the rotating inertia force of the rotor to be unbalanced and causing vibration. The lack of phase of the motor and the unbalanced power supply of each phase can also cause vibration. In the stator winding of the motor, due to the operation quality problem of the installation process, the resistance between the phase windings is unbalanced, which results in the uneven magnetic field and unbalanced electromagnetic force. This electromagnetic force becomes an exciting force and causes vibration.
5. the bearing
If the rigidity of the bearing is too low, the first critical speed will decrease, causing vibration. In addition, poor performance of the guide bearing leads to poor wear resistance, poor fixation, excessive bearing gaps, and easy vibration; while the wear of thrust bearings and other rolling bearings will aggravate the longitudinal movement vibration and bending vibration of the shaft. . Lubrication failure caused by improper selection of lubricants, deterioration, excessive impurity content, and poor lubrication pipelines will cause deterioration of bearing conditions and cause vibration. The self-excitation of the oil film of the motor sliding bearing also produces vibration.
6. the impeller
The centrifugal pump impeller is eccentric in mass. The quality control in the impeller manufacturing process is not good, for example, the casting quality and machining accuracy are unqualified; or the conveyed liquid is corrosive, and the impeller flow path is eroded and corroded, causing the impeller to be eccentric. The number of blades of the centrifugal pump impeller, outlet angle, wrap angle, whether the radial distance between the throat tongue and the impeller outlet edge is appropriate, etc. Between the impeller mouth ring and the pump body mouth ring of the centrifugal pump, the interstage bushing and the diaphragm lining
