FASTENING TOOL

摘要

PROBLEM TO BE SOLVED: To provide a fastening tool capable of surely stopping rotation of a motor at seating time. SOLUTION: This fastening tool has a fastening determining part 21 for stopping the motor 1 by determining seating on the basis of fastening torque T estimated by a torque estimating part 14. The fastening determining part 21 calculates a torque variationΔT being a change rate of the fastening torque T and a coefficient of torque variationΔΔT being a change rate of the torque variationΔT; and determines it as seating when the fastening torque T exceeds predetermined lower limit torque T1 when the coefficient of torque variationΔΔT reaches negative from positive after an integrated value or an integral value of the coefficient of torque variationΔΔT in a section becoming continuously positive in the coefficient of torque variationΔΔT exceeds a predetermined threshold value C. The fastening tool also has a torque setting switch 23 for allowing a worker to freely set the lower limit torque T1. COPYRIGHT: (C)2005,JPO&NCIPI