Analysis, treatment and prevention of the most com

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Analysis, treatment and prevention of common rotating machinery vibration faults

Abstract: This paper summarizes the causes, hazards, inspection, treatment and prevention of common rotating machinery vibration faults, which can be used as a reference for equipment management technicians. Key words: turnaround; Vibration fault; reason; analysis; handle; In the view of comprehensive cost in the whole life cycle, classification number: tb123 document identification code: there are usually four reasons for the vibration of B rotary machine: imbalance, resonance, misalignment and mechanical failure. Tang Peide served as chairman of the Implementation Committee Rotor unbalance is the most common cause of vibration, such as poor rotor manufacturing, accumulation of foreign matters on rotor blades, poor motor rotor balance, etc. Another reason for large vibration caused by imbalance is poor stiffness or resonance of the equipment base. Keys and keyways are another cause of unbalanced vibration. Thermal bending of the rotating shaft is another phenomenon that causes rotor imbalance. Generally, the unbalanced vibration caused by thermal bending changes slightly with the change of load. However, if the equipment foundation resonates with its rotation, severe vibration is likely to occur. Therefore, the key to prevention is that the material of the rotating shaft must meet the requirements; Second, the transfer machine base must be solid and reliable. 2. The resonance frequency in the resonance system depends on the number of degrees of freedom; Resonance frequency is determined by mass, stiffness and attenuation coefficient. The resonance frequency of the rotor support shall be far away from any excitation frequency. For new devices, consult the manufacturer for the required foundation stiffness to achieve this purpose. For existing devices with the same resonance frequency and speed, there are two options to minimize the exciting force or change the resonance frequency. The latter can be achieved by increasing the stiffness and mass of the system. When dealing with resonance, it is best to change the resonance frequency. Resonance may also be caused by misalignment or mechanical and electrical failures. The resonance frequency of harmonic at rotating speed is also easy to cause faults. They may also be induced by misalignment or mechanical and electrical faults. However, compared with the problems at the same frequency, the problems caused by these resonances are not common. 3. Misalignment may cause radial and axial exciting forces at the speed and twice the speed. However, it must not be concluded that there is no alignment problem because there is no one or two of the above phenomena. At the same time, the thermal expansion of the unit should be considered, and 1 Mm gap. 4. Mechanical failure, poor coupling, bearing and lubrication with poor quality, and unstable support are all the reasons for the excitation forces with different frequencies and amplitudes. (1) Poor quality couplings are mainly manifested in poor casting quality, deflection and burr of connecting screw holes, and rubber washers are quickly damaged, which changes the coupling from soft connection to hard connection, causing vibration and wear. (2) The replacement of radial bearings is generally simple. In order to avoid vibration, when replacing a new bearing, the outer ring of the bearing should be checked for contact coloring, and the bearing seat should be treated if necessary. (3) Axial fluctuation is another cause of vibration problems of rotating machinery, including couplings and bearings. Generally, the axial thrust of the rotating machine is constrained by the thrust bearing. However, if the axial alignment is poor and the rotor rubs axially, severe axial vibration may occur. (4) The bearing is weak, that is, the four legs are not on the same plane. When the rotating machine is bolted at these four points, if the bearings are misaligned, it will inevitably cause severe vibration. Therefore, when the machine is installed, several fastening points should be tightened symmetrically with appropriate torque first. Then loosen one fastening point at a time, and measure the vertical deformation of this point with a micrometer that still keeps rapid growth for many years. If the vertical deformation is greater than 05mm, shims should be added at the foot of this support, and its thickness is equal to the deformation. Repeat the above process until the vertical deformation of each point is less than 0.05mm when loosening. (5) The problem of rotating machine base and foundation may be the direct cause of excessive vibration. Therefore, the anchor bolts must have sufficient strength, and the concrete foundation must be solid without holes. During the transfer operation, the anchor bolts should be frequently checked for looseness and fracture, and eliminated in time. At the same time, check whether the supporting of the auxiliary connecting equipment of the transfer machine is firm. In addition, the vibration of water pump caused by cavitation is also a common phenomenon. In addition, the radial friction between the rotor and stator is also easy to cause vibration, which is the vibration induced by the excitation frequency. Therefore, during the assembly of the rotating machine, attention must be paid to the dynamic and static clearance because the tensile test is not convenient for testing. In addition, large axial flow fans have surge, and steam turbines have bearing oil film oscillation. In short, after being familiar with the common causes of rotating machine vibration faults, you can also use various vibration meters to deal with and prevent vibration

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