Sliding bearing vibration reason, mechanism of total solution!

Sliding bearing vibration reason, mechanism of total solution! 2020 - 10 - 14 sliding bearing is usually said that the plane of the bearing, its form is simple, the contact area is large, if good lubrication, anti-wear performance will be very good, will be a long bearing life. Sliding bearing of the bearing capacity is big, high rotary precision, impact resistant effects of lubricating film, thus obtained widespread application in engineering. In this paper, the share of sliding bearing vibration fault reasons, the vibration mechanism, vibration method, etc. Sliding bearing depending on the direction of the load can be divided into: thrust bearing and radial sliding bearing; According to the principle of lubricating oil film formation divided into: dynamic pressure bearing and static pressure sliding bearing; According to different structure forms can be divided into: integral sliding bearing sliding bearing and subdivision. 1. Reasons of forming breakdown of sliding bearing sliding bearing fault causes mainly include: bearing shell design, improper installation; Exceeding the speed limit, overload operation or in the lubricating oil containing impurities; In high temperature, high speed and high load operation conditions, journal and bearing shell material thermal expansion occurs, the bearing clearance disappear, direct contact between the metal; Under the action of alternating load, bearing surface reciprocating action of tensile stress and compressive stress and shear stress, which in the bearing surface, small cracks in continuously running state, the final formation of fatigue damage; Under the large amplitude caused by the long running out; Improper operation of the coupling causes such as time synchronization is not stable, and so on. 2. Sliding bearing vibration fault type slide bearing vibration fault has a variety of forms, including bearing fit clearance is too large; The oil film vortex and oil film oscillation, friction; As well as the common bearing wear, tile burning, fatigue failure such as spun out of the crack. 3. Sliding bearing fault vibration mechanism of sliding bearing vibration caused by many reasons, most of them are caused by other mechanical problems, such as stiffness of the rotor imbalance, problems, etc. Sliding bearing itself caused by vibration, mainly caused by improper fit clearance stiffness is reduced, and the oil film problems caused by the improper design, installation. Oil vortex vortex of oil film is composed of radial sliding bearing oil film force produced by a vortex. When the rotor shaft neck when running stability of the sliding bearing, bearing oil film force R W and load balance each other, the rotor axis in an equilibrium position O1. If the rotor disturbance from equilibrium position is moved to the O2 points, after change of oil film force R′ Together with the load W F is zero, no longer common. Resultant force F can be decomposed into radial and tangent up two component, the radial force component Fr and the direction of displacement of the shaft neck, trying to push the shaft neck back to the original balance position O1, is a kind of elastic restoring force; The tangential component of the Fu and shaft neck displacement perpendicular to the direction of its drive shaft neck O1 continue to rotate around the equilibrium position, which produces eddy, the vortex motion is called oil film vortex, Fu said eddy momentum. If journal of vortex dynamics is less than the oil film damping force, the axial vortex axis trajectory is convergent, which is formed by the vortex will decrease; If the vortex power equal to the oil film damping force, the axis path to expand and become no longer closed graph, vortex is stable; If the vortex dynamics over damping force, the axis trajectory is discrete, the vortex is unstable. Vortex motion of the steering and rotor at the same time, the direction of rotation is positive precession; On the other hand, for the precession. Theoretical calculation show that the rotation of the oil film vortex frequency & Omega; Is equal to the rotor rotation frequency & omega; Half of that & Omega; =ω; / 2, so the oil film vortex theory is also known as half speed vortex. In practice, the oil film vortex vibration frequency is about 0. 42 ~ 0. 48 speed frequency, i. e. , & Omega; = ( 0. 42 ~ 0. 48) ω 。 The oil film oscillation with the rotor rotating frequency & omega; （ The rotational speed n) Rise ceaselessly, the oil film vortex frequency of vortex & Omega; Is also rising, when the rotor rotational speed n up to the first critical speed nk1 near twice, that is to say, when the oil film vortex frequency is equal to the natural frequency of the rotor bearing system, namely & Omega; =ω; K1, the rotor bearing system will be a strong resonance, oil film oscillation that is said. Oil film oscillation happens, even if the speed continues to rise, but not according to the vortex frequency of vortex ratio ( Ω /ω ） The law of the constant rise, is still the & omega; K1, tightly grabbed the first natural frequency of the rotor critical speed no longer change. Oil film vortex and the oil film oscillation is a kind of self-excited vibration, that is to say, maintain the vibration energy is by the rotor bearing system ( Contain oil) In itself, it can constantly provide a great deal of energy, and have nothing to do with the outside world. So, the oil film oscillation also has severity, sudden and sometimes a discontinuous roar, etc. Use more tilting tile bearing for large unit, the theoretical calculation shows that, in the case of ignoring quality of tile and pivot friction, tilting cross stiffness of the bearing is zero, could not produce the oil film vortex and the oil film oscillation. Because of its segment can swing freely, can automatically adjust to the through the axis of the oil film force, thus with load line, eliminates the tangential oil film force component, fundamentally eliminate the driver of the vortex. However, because often appears in be used actually some do not tally with the design conditions, such as improper protection have friction, bearing force, lubricating oil viscosity is too large, and so on, so the tilting tile bearing oil film oscillation may occur. As for other types of bearings, such as round pantile, oval watts, leaf oil wedge, oil bearing, as long as it is to belong to high speed light load, is possible oil film vortex and the oil film oscillation. （ Source: coal chemical knowledge library)