Abstract: A screwing apparatus includes a motor for rotating a bit for rotating a screw, a torque detecting device for detecting torque of the bit, and a control device. The control device increases magnitude of fastening torque by applying slight vibration to a torque instruction to be transmitted to the motor after the screw which is to be fastened at a value of target fastening torque is seated on a workpiece, and turns off electric current to be supplied to the motor via the torque instruction when the torque of the bit feedback from the torque detecting device to the control device has attained to the value of the target fastening torque.

Abstract: A screwing apparatus includes a multi-phase motor and a control device. The motor rotates a bit, installed on the motor, for rotating a screw. The control device controls a rotational speed of the motor by calculating a rotational speed of the bit based on commutation signals outputted from sensors installed on the motor, and controls a torque value of the bit by outputting instructions to the motor so that the bit is rotated at a predetermined torque value.