1. Motor
The motor structure is loose, the bearing positioning device is loose, the iron core silicon steel piece is too loose, the bearing wear and lead to the decline of the support stiffness, can cause vibration. Mass eccentricity, rotor bending or mass distribution problems lead to uneven distribution of the rotor, resulting in excessive static and dynamic balance. In addition, in squirrel cage motor rotor cage cage fracture, resulting in unbalanced rotor by magnetic force and rotor rotational inertia force caused by vibration, the motor phase missing, the phase power supply imbalance and other reasons can also caused by vibration. Motor stator winding, due to the installation of operation quality problems, resulting in each phase winding resistance imbalance, thus resulting in the magnetic field is not uniform, resulting in unbalanced electromagnetic force, the electromagnetic force becomes exciting force caused by vibration.
2. Foundation and pump support
The contact fixed form between the driving device and the base is not good, the foundation and the motor system absorb, transmit, isolate the vibration ability difference, causes the foundation and the motor vibration to exceed the standard. Pump foundation looseness, or water pump in the installation process in the formation of elastic foundation, or due to oil blisters caused foundation stiffness decreased, the pump will produce vibration and phase difference 1800 another critical speed, thereby increasing the vibration frequency of the pump, if the frequency increases and some external factors frequency is close to or equal to, will make pump amplitude increase. In addition, the foundation anchor bolts loosening, resulting in constraint stiffness decreased, will make the motor vibration.
3. Coupling
Coupling bolt of the week to pitch side, the symmetry is broken; coupling extended section eccentric, eccentric force will be generated; coupling cone degree; coupling static balance and dynamic balance is not good; elastic pin coupling with the tight, elastic column pin lost elastic adjustment function caused by coupling may not well of; coupling and axial clearance is too large; mechanical coupling ring wear lead to coupling ring with performance degradation; coupling transmission quality of bolts each ranging from. These causes can cause vibration.
4. Centrifugal pump impeller
Centrifugal pump impeller mass eccentricity. The quality control is not good in the process of manufacturing, for example, the casting quality and the processing precision are not qualified; or the liquid is corrosive, the impeller flow channel is corroded, resulting in the eccentric impeller.
The number of blade, the outlet angle, the angle of wrap, the radial distance between the throat and the throat of the impeller are suitable for the centrifugal pump impeller.
Between the impeller and the pump body of the centrifugal pump, the stage between the sleeve and the spacer sleeve, the initial rub, gradually become mechanical friction and wear, these will increase the vibration of the centrifugal pump.
5. Transmission shaft and auxiliary parts
Shaft is a long pump, easy to cause the lack of axial stiffness, deflection is too large, the situation of poor straightness of the shaft, resulting in moving parts (transmission shaft) and static parts (sliding bearing or mouth ring) between the rub, the formation of vibration. In addition, the pump shaft is too long, the impact of the flow of water in the pool is greater, so that the vibration of the lower part of the pump to increase. The balance shaft end of the disc space is too large, or axial momentum of work channeling improper adjustment, cause the shaft low frequency shifting, cause bearing vibration. The eccentricity of the rotating shaft will cause the bending vibration of the shaft.
6. Pump selection and operation conditions
Each pump has its own rated point, the actual operating conditions and design conditions are in line with the pump's dynamic stability has an important influence. Pump operating conditions in the design is relatively stable, but under variable conditions in operation, due to the role of radial force in the impeller, the vibration has increased; single pump selection is improper, or two models do not match the pump in parallel. These will cause the pump vibration.
7. Bearing and lubrication
Bearing stiffness is too low, it will cause the first critical speed is reduced, causing vibration. In addition, the guide bearing performance close to poor wear resistance is poor, so, bearing clearance is too large, also easy to cause the vibration; and thrust bearing and other rolling bearing wear, the shaft of the vertical traverse vibration and bending vibration at the same time, increased. Improper selection of lubricating oil, deterioration, excessive content of impurities and lubrication pipeline caused by the lubrication failure, will cause the deterioration of the bearing conditions, causing vibration. Motor sliding bearing oil film of the self excitation will also produce vibration.
8. Pipe and its installation fixed
Pump outlet pipe support stiffness is not enough, too much deformation, cause the pipeline under pressure in the pump body, the pump body and the motor neutral damage; pipeline in the installation process in rivalry is too big, import and export pipeline and pump connection of the internal force enter, loosening of the export pipeline, constraint stiffness under reduced or even failure; outlet part of the fracture, debris got stuck impeller; unsmooth pipeline, such as the outlet air bag; water outlet valve plate falling off or not open; and a suction inlet, flow field, pressure fluctuation. These causes can directly or indirectly lead to pump and pipeline vibration.
9. Coordination between parts
The motor shaft and the pump shaft concentricity tolerance; motor and drive shaft connection at the use of the coupling, coupling concentricity tolerance; design gap between dynamic and static parts (such as Ye Lunyi and the mouth ring between the wear bigger; intermediate bearing bracket and the pump barrel body excessive clearance; sealing ring gap inappropriate, resulting in a unbalanced; sealing ring gap on the periphery of the uneven, such as mouth ring not groove or partition not groove occurs this situation. These adverse factors can cause vibration.
10. Factors of the pump itself
The non symmetric pressure field generated by the rotation of the impeller suction tank and the water inlet pipe; eddy current; and disappeared inside the impeller and volute, guide vane vortex; semi open vortex caused by vibration of the valve caused due to the limited number of impeller blades; the outlet pressure caused the uneven distribution of flow in the round; leaf removal; surge; the fluctuating pressure of flow; cavitation; water flow in the pump body, a pump friction and impact on the experience, such as front, the tongue and the guide vane flow impact caused by vibration; boiler feed pump for conveying high temperature water cavitation vibration; pump pressure pulsation, the main pump impeller sealing ring, pump clearance body sealing ring is too large, causing the pump body leakage loss, severe reflux, imbalance and pressure fluctuation caused by the axial force of the rotor, the vibration will increase. Also for conveying hot water pump, if the start of the pump before preheating uneven, or pump sliding pin shaft system is not normal, caused by thermal expansion of the pump group, violent vibration of the start-up phase of the evoked; pump body is released from the thermal expansion of the internal stress can not, it will cause changes in the stiffness of the shaft supporting system, when the change of stiffness and angular frequency into integral multiple relations, resonance occur.
