TIGHTENING TORQUE INSPECTION DEVICE FOR BOLT AND TIGHTENING TORQUE INSPECTION METHOD

• Main Authors: TAKAHASHI YOTARO, OKUHIRA MASAHITO, KIKUZAWA TAMOTSU
• Format: Patent
• Language: English
• Published: 18.06.2009
• Subjects: HAND TOOLS; MANIPULATORS; PERFORMING OPERATIONS; PORTABLE POWER-DRIVEN TOOLS; TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FORFASTENING, CONNECTING, DISENGAGING OR HOLDING; TRANSPORTING

PROBLEM TO BE SOLVED: To provide a tightening torque inspection device capable of correctly detecting a tightening torque for a bolt wherein a head return phenomenon takes place. SOLUTION: A control calculation part is provided with a means for inputting data about dimension and material characteristics of a shank part of the bolt, a means for calculating a spring constant K of torsion of the shank part of the bolt based on the input data and a means (a step S12) for calculating a torque gradient line. This control calculation part is provided with a means (a step S13) for determining that the torque gradient line is shifted over an inflection point for a torque gradient line having a small inclination and its inclination is stabled, a means (a step S14) for determining whether the inclination of the torque gradient line exceeding the inclination point is smaller than an inclination of a reference gradient line Z obtained by multiplying the spring constant K by a safety factor A which is smaller than 1 or not, a means (a step S15) for calculating an estimation value of the tightening torque around the inflection point based on the torque gradient line when the inclination of the torque gradient line is determined to be smaller than the inclination of the reference gradient line Z. COPYRIGHT: (C)2009,JPO&INPIT