这是描述信息

 | Pumps, reducers, castings

这是描述信息

Analysis of the causes of pump vibration and its elimination measures

Description:Vibration is an important indicator for evaluating the operational reliability of pump units. The hazards of excessive vibration are mainly caused by vibration, which can cause the pump unit to fail to operate normally; cause vibration of the motor and pipeline, causing damage to the machine; causing damage to bearings and other parts; causing loose connection parts, base cracks or motor damage; The pipe or valve connected to the pump is loose and damaged; vibration noise is formed.

Answer:
Vibration is an important indicator for evaluating the operational reliability of pump units. The hazards of excessive vibration are mainly caused by vibration, which can cause the pump unit to fail to operate normally; cause vibration of the motor and pipeline, causing damage to the machine; causing damage to bearings and other parts; causing loose connection parts, base cracks or motor damage; The pipe or valve connected to the pump is loose and damaged; vibration noise is formed.
 
The causes of pump vibration are manifold. The shaft of the pump is generally directly connected to the shaft of the drive motor, so that the dynamic performance of the pump and the dynamic performance of the motor interfere with each other; the high-speed rotating parts have many, the dynamic and static balance can meet the requirements; the components that interact with the fluid are greatly affected by the water flow condition; The complexity of fluid motion itself is also a factor limiting the stability of pump dynamic performance.
1 Analysis of the causes of pump vibration
1.1 Motor
The structural parts of the motor are loose, the bearing positioning device is loose, the iron core silicon steel sheet is too loose, and the bearing stiffness is reduced due to wear, which may cause vibration. Mass eccentricity, uneven rotor mass distribution caused by rotor bending or mass distribution problems, resulting in static and dynamic balance exceeding the standard. In addition, the squirrel-cage motor rotor has a broken cage cage, which causes the magnetic force of the rotor and the rotational inertia of the rotor to be unbalanced, causing vibration, the motor is out of phase, and the power supply of each phase is unbalanced. Due to the operational quality problems of the installation process, the stator windings of the motor cause an imbalance in the resistance between the windings of the respective phases, resulting in a non-uniform magnetic field generated, resulting in an unbalanced electromagnetic force, which becomes an exciting force to cause vibration.
1.2 Foundation and pump bracket
The contact fixing form adopted between the driving device frame and the foundation is not good, and the basic and motor systems have poor absorption, transmission and isolation vibration, which causes the vibration of the foundation and the motor to exceed the standard. If the pump foundation is loose, or the pump unit forms an elastic foundation during the installation process, or the base stiffness is weakened due to oil immersion blisters, the pump will generate another critical speed with a phase difference of 1800 from the vibration, thereby increasing the pump vibration frequency. The frequency is close to or equal to the frequency of an external factor, which increases the amplitude of the pump. In addition, the looseness of the foundation anchor bolts leads to a decrease in the constraint stiffness and an increase in the vibration of the motor.
1.3 Coupling
The circumferential spacing of the coupling bolts is poor, the symmetry is broken; the coupling is extended with the eccentricity, and the eccentric force will be generated; the coupling cone is out of tolerance; the coupling static balance or dynamic balance is not good; The cooperation between the pin and the coupling is too tight, so that the elastic pin loses the elastic adjustment function, so that the coupling is not well centered; the coupling clearance between the coupling and the shaft is too large; the mechanical wear of the coupling apron is caused by Coupling aprons have reduced mating performance; the quality of the drive bolts used on the couplings varies from one another. These causes vibration.
1.4 Impeller
1 Impeller mass eccentricity. The quality control in the impeller manufacturing process is not good. For example, the casting quality and processing accuracy are unqualified; or the liquid conveyed is corrosive, and the impeller flow path is corroded and corroded, resulting in eccentricity of the impeller. 2 The number of blades of the impeller, the exit angle, the wrap angle, the radial distance between the throat tongue and the exit edge of the impeller are appropriate. 3 In use, between the impeller ring and the pump body ring, between the interstage bushing and the diaphragm bushing, from the initial rubbing, gradually become mechanical friction and wear, which will aggravate the vibration of the pump.
1.5 drive shaft and its accessories
A pump with a long shaft is prone to insufficient shaft stiffness, too large deflection, and poor straightness of the shaft system, causing friction between the moving member (drive shaft) and the static member (sliding bearing or ring) to form vibration. In addition, the pump shaft is too long, which is greatly affected by the impact of the flowing water in the pool, so that the vibration of the underwater part of the pump is increased. If the balance disc clearance at the shaft end is too large, or the axial work movement is improperly adjusted, the shaft will be low frequency and the bearing bush will vibrate. The eccentricity of the rotating shaft causes bending vibration of the shaft.
1.6 Pump selection and variable operating conditions
Each pump has its own rated operating point. Whether the actual operating conditions are consistent with the design conditions has an important impact on the dynamic stability of the pump. The pump runs stably under the design conditions, but when operating under variable conditions, the vibration is increased due to the radial force generated in the impeller; the single pump is not properly selected, or the two models are not matched. in parallel. These will cause the pump to vibrate.
1.7 Bearings and lubrication
The stiffness of the bearing is too low, causing the first critical speed to decrease, causing vibration. In addition, poor performance of the guide bearing results in poor wear resistance, poor fixing, excessive bearing clearance, and easy to cause vibration; and the wear of thrust bearings and other rolling bearings will cause the longitudinal turbulent vibration and bending vibration of the shaft to increase. . Improper selection of lubricating oil, deterioration, excessive impurity content and poor lubrication of the lubrication pipe will cause the bearing condition to deteriorate and cause vibration. The self-excitation of the oil film of the motor sliding bearing also generates vibration.
1.8 pipe and its installation and fixed
The outlet pipe bracket of the pump is not rigid enough, and the deformation is too large, causing the pipe to be pressed down on the pump body, which makes the pump body and the motor have a neutral damage; the pipe is too strong during the installation process, and the inlet pipe is connected to the pump. The stress is large; the inlet and outlet pipelines are loose, the restraint stiffness is reduced or even failed; the outlet flow passages are all broken, the debris is stuck to the impeller; the pipeline is not smooth, such as the outlet has airbags; the outlet valve is off or not opened; the inlet has Intake, uneven flow field, pressure fluctuations. These causes direct or indirect vibrations in the pump and piping.
1.9 Matching between parts
The motor shaft and the pump shaft are out of concentricity; the coupling is used at the connection between the motor and the drive shaft, and the concentricity of the coupling is out of tolerance; the design between the moving and static parts (such as between the impeller and the ring) The wear of the gap becomes large; the gap between the intermediate bearing bracket and the pump cylinder exceeds the standard; the gap of the seal ring is not suitable, resulting in an imbalance; the gap around the seal ring is not uniform, such as the mouth ring is not the person slot or the partition is not the person slot, This happens. These unfavorable factors can cause vibration.
1.10 Factors of the pump itself
The asymmetric pressure field generated when the impeller rotates; the vortex of the suction pool and the inlet pipe; the occurrence and disappearance of the vortex inside the impeller and the volute and the guide vane; the vibration caused by the vortex caused by the valve half opening; due to the limited number of impeller blades Uneven distribution of outlet pressure; outflow in the impeller; asthma
发送反馈
历史记录

Scan the QR code to read on your phone

Next article: None

Hangzhou Haiyu Machinery Co., Ltd.

ADD: Linpu Town, Xiaoshan District, Hangzhou, Zhejiang, China

TEL:86 -571 - 82462740

MOBIEL:13506715592

FAX:86-571-82421008

Username used for comment:
客户留言
Description:
.

2019 All Rights Reserved Hangzhou Haiyu Machinery Co., Ltd  浙江ICP备0000000号  Powered by www.300.cn