Analyzing yield strength tightening of bolt connection using intermittently working screwing tools e.g. nut runner, by measuring tightening torque and angle of rotation, then determining gradient and thresholds using measurement

摘要

The method involves measuring the torque and angle of rotation produced at time of bolt connection tightening, and calculating a gradient with a screw drop specific dynamic threshold range based on the measurements. The screw drop specific dynamic cut-off threshold, which slopes down from the gradient, is likewise measured. Bolt connection loosening is judged when the calculated gradient drops down to a specific absolute gradient threshold, upon running of a certain application into which both measured torque and angle of rotation are input.