| 摘要 |
PURPOSE:To alleviate a shock to a worker when screw releasing time by increasing a peak current cut level at screw releasing reverse turning time as compared with normal turning time. CONSTITUTION:A timer 12 outputs an L level during a predetermined period T when a power source switch 8 is turned ON. In the meantime, a motor current iM is suppressed to a set value iC or lower by the operations of a current detector 20 and a peak current cutting circuit 17. When a timer period T is elapsed, the output of the timer 12 becomes an H level, and when the motor current iM then arrives at the breaking level i2, a motor current breaker 18 operates. The peak current cut value in the detector 20 is set 10-30% higher than that at clamping time at screw releasing reverse rotating time as compared with the normal turning time. |
