Common problems and solutions of coupling

Release time：2019-02-21

Common problems and solutions of coupling:

Equilibrium level

(1) the balance level of any coupling component is determined by the square and square root values of the possible peaks of the eccentricity at the center of gravity position between the principal axis of inertia of the coupling and the axis of rotation. Its unevenness is expressed in microns.

(2) the potential unbalance factors of coupling components were introduced above. The calculation examples are shown in the steps to determine the balance level of various types of coupling components and calculate the balance.

(3) the coupling balance level standard classification table under the table, on the equilibrium surface position on rotation axis of the inertial principal axis line of the offset to the peak value of root mean square microns, said its value is calculated on AGMA method coupling balance standard ranks coupling balance on the balance of the inertial principal axis line displacement (RMS) coupling balance level displacement on the surface of the inertial principal axis line in the balance (RMS)

Balance problems

Coupling make its center of mass for a variety of reasons or the inertial principal axis and axis misalignment, the operation will generate unbalanced centrifugal inertia force, the centrifugal inertia coupling force and dynamic deflection (modal) phenomenon, known as the imbalance of the rotor, this imbalance is bound to cause the vibration of shaft system, which affects the normal work and service life of the machine, and therefore must be addressed to it. The degree of unbalance (U) is usually expressed as the product of the mass m of the rotor and the distance r from the center of mass to the axis of rotation of the rotor, Mr, which is called the mass diameter product. It is also expressed in terms of the mass diameter product per unit mass, called eccentricity e (not geometric eccentricity). Mr Is a relative quantity related to the mass of the rotor, while eccentricity e is a perfect quantity independent of the mass of the rotor. The former is more intuitive and is often used for the balance operation of a given rotor, while the latter is used to measure the balance of the rotor or to detect the balance accuracy. The balance grade standard of the coupling is evaluated according to e. For a flexible rotor, the vibration mode eccentricity (mode of the NTH order) en=Un/mn, where Un and mn are the NTH mode mode and mode mass respectively.

In order to correct or greatly reduce the unbalance of the coupling, the appropriate balance grade should be selected according to the need, and after the product is manufactured and installed on the machine, the balance (correction) plane specified by the coupling should be added or reduced to meet the balance grade requirements. This process is called balance correction, or balance for short.

Relative displacement

The relative displacement of the two shafts connected by the coupling is caused by various factors such as manufacturing error, installation error, deformation of the shaft under load, base deformation, bearing wear, temperature change (thermal expansion, cold contraction), and relative motion of the components. In general, the relative displacement of the two axes is unavoidable, but the displacement direction generated by the shafting transmission under different working conditions, namely axial (x), radial (y), angular (a) and the magnitude of displacement are different. Only the flexible coupling can compensate the relative displacement of two axes, so it is widely used in practice. Rigid coupling does not have the compensation performance, the application scope is limited, therefore the consumption is very small.