Method and device for tightening screws

摘要

Screws are tightened to a certain pretension in several screw-in stages by means of a screwdriving device. The screwdriving device consists of a screwdriver with a pneumatically operated motor and an adjusting means. In preferably two screw-in stages, first of all a predetermined tightening torque (joining moment) is applied to the screw, and then the screw is tightened in a third and last screw-in stage right into the plastic region, in the course of which the adjusting means either turns the workpiece against the screw-in direction or turns the housing of the screwdriver in the screw-in direction through a predetermined angle.