| 摘要 |
PURPOSE:To raise the accuracy of tightening of bolt and nut, by using series-wound commutator motors, detecting that the rotation of all nut runners is almost stopped, rotating the nut runners further by a prescribed angle and then simultaneously cutting off the currents of the motors. CONSTITUTION:The currents of series-wound commutator motors 10, 20 are limited below a level corresponding to a bolt and nut tightening torque set by a torque setter 2. A signal is applied by the output of an AND circuit 3 to full shift control circuits 12, 22 for a rotation angle method since the output of the AND circuit is produced. Then, a signal is applied to thyristor circuits 11, 21 to rapidly rotate the motors. Rotation angle setters 19, 29 are put in operation for the rotation angle method. The output pulses of rotation angle detectors 18, 28 are counted to detect the rotation angles of the motors. When the counted values reach those set by the rotation angle setters 19, 29, gate shut-off circuits 17, 27 are energized to cut off the currents of the motors. |
