In the measurement of vibration in the process, often found bearing axial vibration is too large, the axial vibration amplitude of the vertical and horizontal vibration amplitude is often several times and even reach a few times, and the axial vibration is too large, and most occur in induced axial vibration of bearing crosses big reason to have the following several points.
1, rotor bending
The axial distance between the bearing and shaft neck is generally longer, and the rigidity of the material and the manufacturing quality and other factors, will inevitably make some static deflection of shaft. In operation, such as the rotor with the stator air gap between uneven, the rotor is subjected to periodic electromagnetic force or rotor under non uniform temperature field, can make the rotor in force ( thermal ) under the action of bending. Bending during rotation of the rotor, shaft deflection, axial bearing oil film bearing in the center along the axial direction with speed changes occurred in the cycle, thereby causing the bearing with shaft deflection, and then passed to the bearing seat, eventually leading to the axial vibration bearing. Vibration intensity is proportional to the same rotor bending degree, usually by the rotor bending caused by excessive vibration at the same time, also with the vertical and horizontal vibration is larger.
2, bearing company
In general, when the machine shaft deflection and axial vibration is inevitable, deflection during rotation of the rotor, trying to make the bearing and bearing corresponding deflection. But if the bearing cannot follow the shaft deflection, will aggravate the bearing axial vibration. If the unit at the time of installation, the bearing seat and the bottom of the table is not in contact with the requirements, the contact area is not up to above 75%, and the contact point of division and uneven, can directly cause bearing axial vibration. In the long-term operation of unit vibration will cause the connecting fastener tension relaxation, especially foundation bedplate bolt tensioning stress relaxation. Fastening bolt tension constant relaxation caused vibration amplitude variation with time gradually increased the consequences of the vibration, the more loose, the more loose more vibration.
3, bearing shell bearing interference amount is too large
Deflection during rotation of the rotor, bearing can follow shaft deflection and axial vibration is larger. But in maintenance, is often wrong, bearing force more can inhibit the bearing vibration, but easy to neglect the bearing cannot follow the shaft deflection of shaft vibration, will be passed directly to the bearing seat, but increasing the bearing axial vibration amplitude. Ascertain bearing cover bearing the tight force of some large, some small need some reasons, the need to distinguish between each bearing a location, environment and working conditions. Based on the analysis of rotor bearing for section, bearing and bearing shell, both interdependence between the Commonwealth, and is independent of the assembly, the unit normal work when the high speed rotation of the rotor must be oil film friction resistance function, and oil film bearing surface of the Ugyen movement and by the effect of friction drag.
4, unbalanced electromagnetic force and ventilation quantity balance
Pure bending caused directly by the rotor axial vibration exceed the standard situation does not see more, to make the rotor generate axial channeling analysis the reason, it is necessary to introduce two new concepts, i.e. electric magnetic balance and ventilation quantity balance.



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