Development of a safety visualization mechanism for bolt looseness

Abstract

Bolts are loosened by various external forces applied to them and due to their aging degradation. Bolt looseness has caused an unending stream of serious accidents and disasters. In order to prevent accidents due to bolt looseness, visual inspection is still important and indispensable at present. On the other hand, though periodic inspection of some mechanical equipment has been obligated by law, most daily inspection before starting operation and the like are reliant on visual inspection. Inspection in this mode can detect bolt omission and other major changes, but cannot detect minor bolt looseness. Suitably, the visual inspection cannot grasp as far as progress in bolt looseness, either. In view of this, as time advances, bolt looseness develops, which often leads to serious accidents. In this research, a mechanism for the precisely visualization of an imperceptible bolt looseness and the grasp of the degree of bolt looseness was developed. Apart from the requisite inspection of bolts, this mechanism can confirm the progress in bolt looseness, and detect the bolt looseness over the preset amount of the minimum permissible bolt looseness through the behavior of the axial force detecting pin. The visualization mechanism is composed of positive components, and is formed to be safety confirmation type, so that it can precisely transmit and alert bolt looseness. Featured by the preciseness and efficiency in bolt looseness checking, the visualization mechanism is intended to prevent accidents.