1, the body
of a rotor dynamics research, refers to an amount of unbalance (even the centrifugal force and the centrifugal force, see the relative motion) generated during rotation of the rotor is determined to be eliminated and the position and size of the operation. Unbalance causes lateral vibration of the rotor, the rotor and unnecessary dynamic load, which is not conducive to normal operation of the rotor. So, most of the rotor should be balanced. Manufacture or maintenance in the machine, balancing becomes a process. 
unbalance amount generated when the rotor rotates because the center of mass of each micro-segment is not strictly due to the rotor axis of rotation. Due to the centrifugal force of each micro-segment deviation of the centroid axis of revolution generated perpendicular to the axis of revolution. May be synthesized by the centrifugal force-based synthesis of a small number concentration, which is still a direction perpendicular to the axis. In general, to use at least two acting respectively on the cross-section of concentration can represent two original centrifugal system. If the two forces concentrate formed just couple, the original unbalance amount when the rotor is not rotating and is undetectable measured; is rotated, the force couple and cause interference before the formation of lateral vibration of the rotor. The effect of this imbalance can only be perceived and measured in a dynamic rotation, so the need for balancing. On the other hand the static balance refers to the mass of the rotor when can be regarded as a very concentrated so thin disk perpendicular to the pivot axis, excluding the thickness of the rotation can be carried out without balance. A rotor which is placed horizontally practice, be biased towards the side of the force of gravity down to the bottom, try to adjust the position of the centroid of the rotor by, so positioned on the axis of revolution.
After measuring the position and size of the imbalance, or it will be removed directly, or in the direction of its symmetry and coupled to its corresponding mass to balance its effect, i.e., by complete or counterweight to the movable weight balance.
The mass of the rotor and deformation distribution of the balancing and balancing flexible rotor balancing is divided into rigid rotor.
Balancing the rigid rotor
for operating speed much lower than the critical speed of the rotor, unbalance due to the deformation is small. Such rigid treatment can rotor, balancing may be performed at a low speed, called the rigid rotor balancing. Rigid rotor balancing is performed, the amount of unbalance centrifugal inertia forces cause each micro-segment may be reduced to two arbitrarily selected cross section up, the two surfaces for corresponding correctionPositive (de-emphasis or weight) to complete the balancing. To find the two sections of the unbalance position and size of the balancing machine can be used. Balancing machines commonly divided into soft and hard-bearing support two categories, the former detecting the vibration caused by unbalance; rotor unbalance force detecting the latter in the support. Rigid rotor balancing issues have been resolved better. Currently, the International Organization for Standardization (ISO) has defined various types of rigid rotor balancing accuracy.
Balancing the flexible rotor
Supercritical rotor rotation speeds at startup and braking, the rotational speed must pass through the critical speed, then the amount of unbalance will produce significant deformation of the rotor. If each of the segmented rotor center of mass offset from the axis of rotation has a significant effect on the deformation, the rotor can not be processed by the rigid rotor, it referred to the corresponding balancing flexible rotor balancing.
There are two methods:
① Method modes. The amount of unbalance for each order of natural vibration mode of the rotor decomposition. If the rotational speed when approaching a critical speed balancing, the primary natural vibration mode of the protrusion on each other in order. By detecting the vibration mode, it can be found to eliminate this phase imbalance correction mass required component size and position should be placed. Stepwise performed, you can complete balancing.
② influence coefficient method. We selected a number of positive school and several measurements on the surface of the rotor and multiple operation to correct. A vibration measurement face of a correction due to the correction amount per unit surface at a certain speed impact is a factor. Determined by measurement or calculation the influence coefficient, can unbalance vibration caused by the vibration is determined for each measurement plane are limited to a magnitude below a front schools should add weight (weight or to) the position and size. On the basis of these two methods is also on the development of other methods, such as modal round method.
2, with FIG.
surface of the rotor in two while correcting the balance of the correction, the corrected residual unbalance, in order to ensure that the rotor is within a predetermined range of dynamic unbalance amount allowable for balancing and said two-sided balance.