Patent ID: 8985237
Filing Date: 2015-03-24
Classification: B25B

Abstract:
1. A power screwdriver comprising: a drive for driving a tool spindle; a controller for controlling said drive; a first sensor for monitoring a rotation speed or a torque; and a second sensor for monitoring a switch-off criterion, said second sensor being coupled to said controller for switching off said drive when said switch-off criterion is reached, wherein said controller is programmed such that when fastening one screw connection: (a) said drive is first of all accelerated until said rotation speed has reached a specific first rotation speed; (b) if said rotation speed then falls by at least a specific amount within a specific time increment, or said torque rises by at least a specific amount within a specific time increment, said drive is braked until said rotation speed has reached a specific second rotation speed, which is lower than said first rotation speed; (c) after step (b), said drive is then controlled at said second rotation speed for a specific time; (d) after step (c), said drive is accelerated again at most until said rotation speed reaches said first rotation speed.