Some rotational system volumes are too large to have suitable dynamic balancing machine for bearing in operation. Some small factories are not qualified to make use of dynamic balancing machine for balancing. Achieved balance in dynamic balancing machine suffers damaged for heat or hysteresis stretching distortion since some working environments of solid of rotation are high temperature or high electromagnetic fields. Reassemble solid of rotation that is already balanced becomes unbalanced caused by transportation or maintenance. All of these circumstances need dynamic balancing solution at locale. Spot dynamic balancing includes single static balance and dynamic balance for soft solid of rotation.

Static balancing operation is very simple. Firstly, attach bearing in solid of rotation (It’s better to have little distance between bearing and adjustment surface), install transducer on larger vibration direction (usually horizontal) and connect vibration measuring instrument, record vibration response when solid of rotation in working rotate speed, high reading recorded as X, corresponded tested amount of unbalance, U, and existing the relationship U=kx, for rigidity solid of rotation, no matter soft or hard bearing k is a constant in fixed rotate speed, so the relationship U=kx still exits. In order to calculate angle (or phase) of vector x, we can adopt rotor two-time method for measuring and calculating. That means, install a checkout mass M(g) in arbitrary location of solid of rotation’s radius and then record vibration response when solid of rotation working in the same rotate speed, high reading is x1, obviously, x1 occurred under the common function between the amount of unbalance U and checkout U1=MR, that is kx1=U+Ut. Dislocate checkout mass M(g) to 180&rodm, record vibration response again after resetting until it works in the same rotate speed, high reading is X2, should exists kx2=U-Ut. So it’s easy to solve vector equation by taking use of graphic method.

For those two-side balance solid or rotation, it should be applied spot dynamic balance testing instrument which can measure phase, thus, it need set prospective signal generator in solid of rotation. Usually, adopt photoelectricity usually. Sometimes, use in-phase flashlight sprang by vibration signal located in bearing. For human’s visual pause phenomenon, we will observe that solid of rotation stay at static status. Require setting angle marks like 0°, 90°, 180°… in adjustment surface in advance so that to observe angle between 0° angle mark and fixed location (such as horizontal direction) under synchronized circumstance.

With the prospective signal, we can assure complex amplitude XL and XR of vibration response in bearing, compute the amount of unbalance according to coefficient affecting law. We usually don’t know system’ s rigidity or mass matrix when conducting spot dynamic balance, as well as hard to ensure bearing rigidity or damping characteristics which use to predigest dynamic rigidity matrix further. Here, we can compute system’s dynamic soft matrix via this experiment, calculate rigidity matrix through calculating inverse matrix. Such method named as affecting coefficient law which is widely applied in balancing multi-adjustment-surface of soft solid of rotation.

It’s more convenient for adopting plural calculation in affecting coefficient law, its coefficient matrix element is plural too, as a result, we can consider damping influence, not like soft or hard bearing dynamic balancing machine by reducing bearing damping, which ignored in separating location. If the matrix element value of influence coefficient is number, it should be tested under fixed rotate speed. When rotate speed change, the influence coefficient matrix changes too.