Abstract: A bolt and nut fastening structure and method include a nut and a bolt screwed onto the nut, an inner screw of the nut being provided to be inclined at a required angle against a central axis line of the nut, and the method of fastening the same. In an initial stage of fastening the bolt and the nut, axial force in the bolt is generated when a part of a bearing surface of the inner screw of the nut seats on a part of a screw of the bolt due to rotation of the nut. Then the axial force is also enlarged proportionally to an increase in rotation angle of the nut to enlarge the seating area.

Abstract: The present invention has been made to solve the above problems, and accordingly an object thereof is to provide a looseness preventive nut which does not loosen even if vibrations are applied, and can be used as a single nut. In at least a first embodiment, the invention provides a looseness preventive nut 1 which is a nut threadedly engaging with a bolt 10, the nut being configured so that a lateral groove 3 extending in the radial direction in the range such that at least a part of a threaded portion 2 is cut, preferably in the range beyond the centerline C of the nut, is formed at a position slightly lower than a substantially middle point of the nut in the height direction.

Abstract: The present invention has been made to solve the above problems, and accordingly an object thereof is to provide a looseness preventive nut which does not loosen even if vibrations are applied, and can be used as a single nut. In at least a first embodiment, the invention provides a looseness preventive nut 1 which is a nut threadedly engaging with a bolt 10, the nut being configured so that a lateral groove 3 extending in the radial direction in the range such that at least a part of a threaded portion 2 is cut, preferably in the range beyond the centerline C of the nut, is formed at a position slightly lower than a substantially middle point of the nut in the height direction.