| 摘要 |
PURPOSE:To automatically obtain a regular bolt tightening condition even in any bolt tightening environment of floating sleeper or the like by eliminating a conventional problematical point according to specifying snag torque generation timing, in a bolt tightening method for an impact wrench. CONSTITUTION:An impact sensor 31 for detecting a hammer 8 of an impact wrench detached from an impact shaft 9 and an angle sensor for measuring a rotational angle of the impact shaft 9 are provided, and by measuring an advance amount of the rotational angle of the impact shaft 9 at each time of generating impact force, torque of the impact shaft 9 is measured. From the point of time the measured torque leads to a preset snag torque value, the advance amount of the rotational angle of the impact shaft 9 is measured, and when this rotational angle advance amount reaches an expected rotational angle preset value, supply power to an electric motor 2 is interrupted, so as to stop rotation of the impact shaft 9. |
