METHOD OF AND APPARATUS FOR CONTROLLING NUT RUNNER

摘要

The output shaft of a nut runner for tightening a fastener such as a bolt is first rotated with a lower torque at a higher speed. When the tightening torque of the output shaft reaches a preset switching torque, torque. When the tightening torque reaches the switching the lower-torque higher-speed rotation of the output shaft is interrupted, and thereafter the output shaft is rotated with a medium torque at a medium speed. When the tightening torque then reaches a preset snug torque, the medium-torque medium-speed rotation of the output shaft is interrupted, and thereafter the output shaft is rotated with a higher torque at a higher speed. When the tightening torque reaches a preset final torque, the higher-torque lower-speed rotation of the output shaft is stopped, thus completing the tightening of the fastener.