BOLT/NUT FASTENING STRUCTURE AND NUT WITH RETURN STOP MECHANISM

To provide a bolt/nut fastening structure which can easily release tightening when the necessity for releasing the tightening arises, and can reuse a bolt and a nut as much as possible.SOLUTION: A ratchet wheel part 20 having an outer tooth ratchet wheel 22 of a bolt 2a is arranged, an inner tooth ratchet wheel part 11 composed of four divided parts 15 which are divided by a slit 13 having an inner tooth ratchet wheel 16 engaged with an outer tooth ratchet wheel 22 is arranged at one side of a return stop nut 1a, a fastening nut 3 is screwed to a male screw part 21 at the bolt 2a, a fastening object 5 is fastened between a head part 23 and the fastening nut 3 via washers 4, 4, and on the other hand, the return stop nut 1a is screwed to a male screw part 32 of the fastening nut 3, thus preventing the loosening of the fastening nut 3 by making the outer tooth ratchet wheel 22 and the inner tooth ratchet wheel 16 engaged with each other. The engagement is released by elastically deforming the divided part 14 to the outside, and the screwing of the nut 1a with the return stop mechanism can be easily released.SELECTED DRAWING: Figure 1 【課題】締め込みを解除する必要が生じた場合、容易に解除できるとともに、ボルト・ナットを極力再利用することができるボルト・ナットの締結構造を提供する。【解決手段】ボルト2aの外歯爪車22を有する外歯爪車部20を設けるとともに、戻り止めナット1aの一側に外歯爪車22に噛み合う内歯爪車16を備えたスリット13によって分分割された４つの分割部15からなる内歯爪車部11を設け、ボルト2ａに雄ねじ部21に締め付けナット3を螺合させ、ワッシャ4,4を介して頭部23と締め付けナット3との間で締結対象物5を締め付ける一方、締め付けナット3の雄ねじ部32に戻り止めナット1ａを螺合させて、外歯爪車22と、内歯爪車16とを噛み合わせることによって、締め付けナット3の弛みを防止するようにし、分割部14を外側に弾性変形させることによって噛み合いを解除して、容易に戻り止め機構付きナット1aの螺合を解除できるようにした。【選択図】 図１