Steam turbine shaft vibration and vibration - bearing the relation of knowledge

Shaft vibration of rotating shaft radial vibration and axial vibration of steam turbine unit now prevailing eddy current probe is used to measure. Have a high frequency current through the coil of the probe, produces the high frequency electromagnetic field and the measured surface of the rotor shaft neck induced current, translate into voltage. And the voltage change with shaft surface and the distance between the sensor and change, so that realize the measurement of shaft vibration. Shaft vibration displacement value is commonly used in said, the unit of micron. If the eddy current sensor fixed on the bearing, the acquisition is the relative vibration between the shaft and bearing; If the sensor fixed on the base, the acquisition of approximate considered absolute vibration of rotor vibration. The bearing vibration of vibration, also calls the bearing vibration. Generally obtained by contact velocity or acceleration sensor, usually fixed on the bearing cover directly or through magnetic adsorption on it, is sometimes called a shell vibration, vibration. Vibration measurement is given priority to with vertical direction and horizontal direction, axial vibration as a reference. Turbine and generator rotor is supported by bearings, the vibration of the rotor is bound to be passed to the bearing, so there is a connection, including amplitude, phase, frequency, etc. 1, and the size of the amplitude of the two relations. Axial vibration and tile vibration amplitude ratio relation with the stiffness of the bearing has a lot to do, usually, if the rigid support bearing seat ( Such as general floor bearing) That shaft vibration amplitude is about 3 ~ 6 times of the vibration. If support such as weak stiffness, the ratio will be reduced accordingly, can appear even the situation of the tile vibration is greater than the shaft vibration ( Such as the east steam 60 tile sets of low-pressure rotor bearing cylinder type) ; 2, phase relationship. Tile general for speed value of vibration and its phase front axle vibration displacement value of 90 °, the speed value transform for the displacement value, its phase Angle needs to increase to 90 °. If the vibration is caused by imbalance, uneven quality of phase and has a fixed shaft vibration phase, at the same time it has to do with tile boost phase has a similar relationship, it is because there is such a relationship, making it possible to field dynamic balancing vibration through the tile. 3, the relationship between the frequency. , has almost the same frequency component of the difference lies in the speed value integral into displacement values, lose part of the high frequency components, so in the rolling bearing, fan wheel, pump body, impeller and other complex mechanical vibration measurement, use vibration velocity values for failure analysis, because it can provide more abundant spectral information. The vibration of turbo-generator set is used more domestic relative axial vibration, it reflects the rotor relative to the support or the vibration of the cylinder block, the axial vibration of the rotor, said when the rotor rotation in a week, leave balance the displacement of the distance. Vibration is an absolute vibration, and reflect the bearing relative to the base vibration, etc. In the modern steam turbine vibration testing, axial vibration and vibration are necessary. If a relative small shaft vibration and tile rotor vibration is very big, means standing in a solid in the movement of the cylinder body coordinates, the rotation relative to the changes in displacement of the support system is small, the relative contact can be avoided; But the dynamic stress of rotor itself and the dynamic stress of bearing is still depends on the vibration of the cylinder body itself value. , the cylinder body and bearing vibration under the dynamic stress of rotor and components must be high, so any excessive axial vibration and tile vibration is unacceptable.