B-63322EN/03 NC FUNCTIONS 15.ACCURACY COMPENSATION FUNCTION
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15.7 CYCLIC SECOND PITCH ERROR COMPENSATION
When a rotary table is rotated using a gear, there are two cycles of the
occurrence of pitch errors: One cycle is the same as that of the rotation
of the rotary table while the other is the same as that of the rotation of
the gear for rotating the rotary table. To compensate for pitch errors of
these types, the compensation for the pitch error due to the rotation of
the gear is superimposed on the compensation for the pitch error per
rotation of the rotary table.
If the gear between the rotary table and the servo motor is of a single
stage, as shown in Fig. 15.7 (a), stored pitch error compensation is used
for the compensation for the pitch error of toothed wheel A and cyclic
second pitch error compensation is used for the pitch error of toothed
wheel B.
If there is a multiple-stage gear, as shown in Fig. 15.7 (b), stored pitch
error compensation is used for toothed wheel A and cyclic second pitch
error compensation is used for the cyclic pitch error that occurs in each
pitch error compensation interval of toothed wheel A.
Motor
Rotary table
Toothed wheel A
Toothed wheel B
Fig. 15.7 (a) Cyclic Second Pitch Error Compensation for a Single-Stage Gear
Motor
Rotary table
Toothed wheel A
Fig. 15.7 (b) Cyclic Second Pitch Error Compensation for a Multiple-Stage Gear