くさびを用いたボルト締結体のゆるみ防止法

抄録

Possibilities of fatigue failure and self-loosening of bolted joints increase if the clamping force would be reduced. Therefore, controlling clamping force and preventing clamping force loss are always required in service.
Two methods for preventing decrease in clamping force on bolted joint have been developed in this study. Two types of wedge are used to prevent the self-loosening in these methods. One type of the wedges is a tapered plate and another type is a conical wedge. These wedges are inserted to either a tapered groove or a conical hole which has been made in a bolt tip after a bolted joint was tightened. The vibration tests have been practiced to confirm usefulness of these methods. And then, the tensile tests and FEM analysis of bolted joints have also been achieved to check the strength of bolted joints.
It has been verified that these methods are useful for prevention of self-loosening on bolted joints. However the proposed methods have decreased the tensile strength of bolted joints due to providing internal groove or hole in a bolt. FEM analysis has revealed that the proposed method make the principal stresses at the roots of the threads except for the first thread of bolt and the bottom of conical hole increase.