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On the balance of couplings
Jun 29, 2017

Coupling for various reasons, the center of mass or inertial spindle and its axis of rotation does not coincide, in operation will produce unbalanced centrifugal inertia force, the phenomenon of centrifugal inertia force and dynamic deflection (vibration type), called unbalance phenomenon of rotors, is bound to cause the vibration of shafting, which affects the normal work and service life of the machine, so it must pay attention to it. The degree of imbalance (unbalance u) is usually expressed by the product Mr of the rotor's mass m and centroid to the rotor axis of rotation, called the mass-diameter product. It is also useful to express the mass of the unit mass, called the eccentric distance E (not the eccentricity of the geometrical sense). Mr is a relative quantity of the rotor mass, and the eccentric distance e is an absolute quantity independent of the rotor mass. The former is more intuitive, commonly used in the specific rotor balance operation, the latter is used to measure the balance of the rotor or the accuracy of the balance test, the balance of the level of the coupling standard that e to evaluate. For the flexible rotor, the En Kun Mn is used for the vibration type eccentricity (nth order mode), and the UN and MN are respectively the nth and the order modal mass.

In order to correct or minimize the unbalance of the coupling, the appropriate level of balance should be chosen as required, and after the product is manufactured and installed on the machine, on the balance (correction) plane specified in the coupling, by adding or reducing the appropriate quality method to achieve the balance level requirement. This process is called balance correction, the short term balance.