Precise positioning arrangement for electrically driven tool holder

摘要

The arrangement serves several tools (2) distributed around the rim of a holder (1) on a shaft (3) rotated by an electric motor (4). Rotational angle sensors (5,6) are provided on the shaft and adjacent to marks on the rim of the holder respectively. A comparator (7) operates on signals (10,11) from the respective angle sensors with reference to a desired-value input (9). An error signal (8) is produced for adjustment of the drive to maintain the desired angular position of the shaft. A variant for a hydraulic drive incorporates a servovalve with similar control.