COMBINATION STRUCTURE FOR BOLT AND NUT ADDITIONALLY PROVIDED WITH PREVENTION OF LOOSENESS

PURPOSE: To provide a combination structure for a bolt and a nut additionally provided with prevention of looseness, absolutely eliminating looseness of the nut after it is once tightened to dispense with work of inspection, tightening, etc., till the lapse of time by metal fatigue. CONSTITUTION: By forming a hollow-shaped space part 3 over a prescribed length from the point end part of a bolt 1, a threaded part 4 of prescribed length from the bolt point end is formed in thin thickness, also to form a several number of streaks of slit parts over a prescribed length in an axially parallel direction in this part 4. On the other hand, a nut 6 is formed into a cap shape, and its space internal diameter H of a cap part 7 of this nut 6 is formed larger than an external diameter L of the bolt 1, also to form a frill-shaped rising part 8 in a space bottom part of the cap part 7 so that a point end inner side of the thin thickness threaded part 4 can be compressed toward the outside. A combination structure for the bolt and the nut, additionally provided with prevention of looseness, is thus formed.