When the motor rotor has only one correction surface, the allowable residual imbalance value of this motor rotor is the allowable residual imbalance value of this correction surface.
For the motor rotor with two correction surfaces I, II, the permissible residual unbalance values UperI and UperII are allowed to assign the residual unbalance value Uper to the I, I correction planes, because the motor rotor correction surface and the bearing arrangement Different spacing can be divided into four different conditions. The vertical machining center spindle assembly is usually in the following conditions (see Figure 1).

figure 1

S-- motor rotor quality center;
L-- spacing between bearings;
hI-- the distance between the calibration surface I and the center of the rotor mass;
hII-- the distance between the calibration surface II and the center of the rotor mass;
b=hI+hII-- The distance from the calibration plane I to the correction plane II.
When the motor rotor meets the following conditions:
The rotor mass of the motor is in the central part of the three-part distance between the bearings. When the two correction faces I, II clamp the two bearings on the outside of the two bearings: