| abstract |
Tightening torque is appropriately managed by a simple means. An electric rotating tool ( 40 ) has a brushless DC motor ( 2 ), an inverter circuit part ( 3 ), and a control circuit part ( 4 ). The control circuit part ( 4 ) has a current detecting circuit ( 18 ), which detects a motor current I, a rotation number detecting circuit ( 17 ), which detects the number of rotations of the motor (N), and a computing part ( 19 ), which calculates first tightening torque (T 1 ) based on the detection information of the motor current (I) and calculates second tightening torque (T 2 ) based on the number of rotations of the motor (N). The computing part ( 19 ) estimates tightening torque Tave based on the estimate value of the first tightening torque (T 1 ) or the second tightening torque (T 2 ). The computing part ( 19 ) stops driving the motor ( 2 ) when the estimated tightening torque Tave exceeds a set value Tset. |