METHOD FOR SELF-PROGRAMMING A POWER NUTRUNNER CONTROL SYSTEM DURING INITIAL TIGHTENING PROCESSES

摘要

A method for self-programming a power nutrunner control system by an initial low speed process for detection and calculation of the screw joint characteristics and by a following adaptation of one or more tightening parameters during a number of succeeding tightening processes, wherein a first preliminary target torque level (MPT) is set as a down shift point from a high speed running down phase to a slow final tightening phase. All tightening processes, the initial screw joint characteristic detecting process included, are performed to a desired final pretension level (MF). After having determined the characteristics of the actual type of screw joint, the rotation speed (v) and the preliminary torque target level (MPT) are stepped up, either with the speed increase first and the preliminary target step up thereafter or both at the same time, until the distance between the obtained angular position ( PHI ) of the joint at the end of the first tightening step and the angular position ( PHI F) obtained at the aimed pretension level (MF) is short enough to provide a satisfactory short overall cycle time for the tightening process without risking overtightening of the joint.