Rotating machinery axial vibration of 5 big reason and mechanism analysis, the expansion of learning!

Everybody know that, in addition to attack the radial vibration in rotating machinery operation, axial vibration often attack. Radial vibration is the attack on the vertical direction and degree of vibration. Axial vibration is refers to the bearing body including the circle and the circle, the circle between the body and the outer body, or between the ring body and the ring body on device has simple structure, roller and vibration provoked. Related to the radial vibration and axial vibration disposal to compare difficult, so we can say this article. So what is the main reason of axial vibration? Excessive vibration force and bearing rigidity is poor. Radial vibration provoked the axial vibration analysis there are two conditions: a bearing seat is equipped with a bearing and a bearing seat is equipped with two bearings. In a bearing seat is equipped with a bearing bush intuitively, and the axial vibration of the bearing should be provoked by the axial movement due to the rotation. But in practice, there is a layer of oil film between the rotor and bearing. Rotor axial movement of the oil film after being transferred to bush, it is difficult to make up and the axial vibration of the bearing. Practice units attack the axial vibration is mostly due to the radial vibration force provoked. From the Angle of dynamics analysis, the radial force and axial vibration is not in the same direction, should not be provoked axial vibration. But, after thinking elastic bearing supporting, radial force will indirectly caused the axial vibration. The above graphs, stop now. Based on the assumption that there is a rotor on the order of unbalanced force, rotor deflection presents the first mode, as shown in figure ( 一) Shown below. T1 time, on both sides of the rotor bearing bearing center tend to be the outside; T2 hour, on both sides of the rotor bearing bearing center tend to be inside. Different time, bearing bearing center cyclical change, cause bearing along the axial runout. First-order flexure, on both sides of the bearing axial swing in the opposite direction. Under the action of second order flexural vibration, as shown in figure ( b） Shown below, on both sides of the bearing axial vibration in phase. If the bearing stiffness is very big, thus provoking axial vibration is small, can neglect. If the elastic bearing, the radial vibration will stir up the indirect and the axial vibration of the bearing. Within A bearing seat is equipped with two axle bush above, assume that A and B on both sides of the vertical vibration in phase, if the support stiffness is also the same on both sides of A, B, then the radial vibration not provoke axial vibration. If A and B on both sides of the vertical vibration reverse phase, or of A and B on both sides of the vertical vibration in phase, but the support stiffness asymmetry, on both sides of the two conditions will incur and the axial vibration of the bearing. The axial vibration of two kinds of situations attack, often along with larger radial vibration. Consequently, when the axial vibration, if radial vibration is big, the disposal of best method is to first reduce the radial vibration. After engineering theory indicate that the radial vibration decrease 10%, axial vibration reducing percentage may be higher. This kind of situation, reduce the vibration force is much smaller than the progress of bearing stiffness workload, and the effect is much more obvious. The lack of bearing stiffness provoked the axial vibration analysis sometimes bearing vertical and degree of vibration alleviation, still have large axial vibration. This is mostly due to the bearing stiffness provoked by a lack of itself. Bearing seat and bedplate, bedplate and root joint looseness, separating surface contact between the loose not average, secondary grouting, walking at the bottom of the table mat iron may induce axial vibration. This kind of fault disposal necessary separation unit overhaul to stop. Other factors caused by excessive axial vibration analysis of the rotor center bias rotor center bias is larger, the coupling bolt connection, will be greater sway degrees by the journal, as shown in the above. As the rotation of the shaft, the oil film pressure can attack a cyclical change, serious when will incur and the axial vibration of the bearing. As shown in the above loads spherical bearing, spherical bearing surface for convex spherical surface, the bearing cover and the bearing of the bearing for concave spherical appearance. This kind of bearing has a function. Trunnion tilt, the bearing can automatically adjust the Angle of the center line of the bearing, the axle bush sharply between surface and shaft neck has been sticking to the axial good contacts. However, when the interference between the spherical tile and tile is bigger, the pillow will pin bearing, lose the function, resulting in a larger axial vibration. Axial axial vibration analysis of resonance provoked some often appear on the generator bearing frequency to 2 times the frequency of the axial vibration. Electromagnetic vibration force are key elements of double frequency induced vibration. Bearing stiffness is normal, and the natural frequency of vibration of the bearing is mostly higher than two times the working speed, the electromagnetic vibration force does not induce twice the frequency of the vibration significantly. However, when the bearing seat and counter or connections between the bedplate and foundation stiffness is poorer, and the natural frequency of vibration of the bearing could fall into two times full speed frequency. Under the action of electromagnetic vibration force of the generator, from housing, has a substantial two axial resonant frequency doubling. Appear this kind of condition, demand check link stiffness, reducing the rotor of the bearing bias and static son, check and adjust the rotor of the generator of the air gap between the average sex, etc.