ボルト・ナット結合体のゆるみに関する研究(第2報) : 軸方向荷重の増減によるゆるみ機構の解明

概要

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One of the authors proposed iri the first report that the torsion of bolt threads which is induced by axial loading is one of the causes of the loosening of a bolt-nut unit under repeated tensile loads. In this paper, in the first place, the self-induced torsion of bolt threads is studied. It is clarified, however, that the torsional moment induced by axial loading is too small amount to cause loosening in the bolt size of the experiment. So, in the next place, another cause of loosening is studied. Axial loading and unloading may produce elastic contraction and expan-sion of the bolt and the nut, accompanying elastic torsion of the bolt shank, which induce the loosening rotation of the nut on the surface of the clamped plate. Above mentioned loosening mechanism is analyzed theoretically under some assumptions, considering loci of slip on the surfaces of the nut threads and the clamped plate. The theoretical values of loosening angle are about one half of the experimental ones, but the characteristic tendency of loosening angle vs. number of repeated cycles shows faily good agreement with the experiment.
公益社団法人精密工学会の論文
1985-08-05