Patent ID: 7000486

Claim:
A method of automatically controlling a screw tool which carries out intermittent rotating strokes and includes a torque sensor ( 23 ) and a rotation angle sensor ( 33 ) comprising the steps of: carrying-out intermittent reciprocal strokes to rotate a screw tool while measuring the torque (M D ) in a torque mode (DMM), upon attaining a predetermined pre-torque (M F ) transitioning to a rotation angle mode (DWM) and thereby count-up the rotation angle (α) up to the end of the current stroke, and storing the rotation angle (α HE1 ) and torque (M HE1 ) values attained at the end of the current stroke, performing subsequent intermittent reciprocal strokes and during each continuing counting-up the rotation angle (α) when the torque (M D ) has reached a value corresponding to the torque (M HE ) at the end of the previous intermittent reciprocal stroke, and storing the rotation angle (α HE ) and torque (M HE ) values attained at the end of each subsequent reciprocal intermittent stroke, and terminating the screw process when the counted-up rotation angle has reached a target angle (α Z ).