JPH1073118A - Bolt and nut - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the loosening of two nuts with rotating in the same direction in the conventional double nuts having a screw groove of same direction when a vibration and an outer force for rotating the nut is applied in one direction. SOLUTION: This bolt and nut are composed of a bolt 1 consisting of a head part 2 and an underhead male screw part 3 adjacent to the head part 2 and a reverse male screw part 4 whose outer diameter is smaller than the inner diameter of the underhead male screw part 3 and adjacent to the underhead male screw part 3 in reverse twist to the underhead male screw part 3 and a large diameter nut 5 screwed with the underhead male screw part 3 and a small diameter nut 6 screwed with the reverse male screw part 4. As the bolt 1 and nuts 5, 6 tightened like above can not be loosened unwillingly unless the large diameter nut 5 is turned in a counter clockwise after turning and loosening the small diameter nut 6 in a clockwise in viewing from the upper side and unless turning the nuts 5, 6 intentionally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt and a nut which do not inadvertently loosen once tightened.

[0002]

2. Description of the Related Art Conventionally, when a bolt is passed through two or more articles and fastened with a nut, a double nut composed of two nuts is used to prevent loosening.

[0003]

However, since the conventional double nut has the same thread groove direction, two nuts move in the same direction when vibration or an external force acting to turn the nut in one direction acts. It could rotate and become loose, and was not perfect as a stop.

[0004]

According to the present invention, as a means for solving the above-mentioned problems, a head, an externally threaded portion under the neck following the head and an outer diameter are defined as an inner diameter of the externally threaded portion under the neck. From a smaller bolt with a male screw part under the neck and a reverse male screw part following the male screw part under the neck in a reverse twist, a large diameter nut screwed into the male screw part under the neck, and a small diameter nut screwed into the reverse male screw part Since a large-diameter nut is screwed into a male screw part under the neck of the male screw part that protrudes through the through hole of the article to which the bolt is tightened, and then tightened, a small-diameter nut is screwed into the reverse male screw part and the large-diameter nut is screwed. When the nut is tightened, the large-diameter nut and the small-diameter nut are reverse-torsioned, so even if vibration or external force is applied to turn both nuts in one direction, the other nut will tighten if one nut tries to loosen. And two nuts Without loosening inadvertently secure tightening can be carried out.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.

In the figure, reference numeral 1 denotes a bolt comprising a hexagonal head 2, a right-handed male screw portion 3 under the neck, and a left-handed reverse male screw portion 4 having an outer diameter smaller than the inner diameter of the male screw product 3 under the neck. Then, the male threads 3 and 4 are passed through the insertion holes c and d of the objects a and b to be tightened, and the large-diameter nut 5 is screwed into the male thread 3 under the protruding part and tightened. 4 is screwed in the opposite direction with the small diameter nut 6 and fastened to the large diameter nut 5.

In this case, the large-diameter nut 5 cannot be screwed unless the length of the male thread portion 3 under the neck is longer than the total thickness of the tightened objects a and b.
If the thickness is not shorter than the total thickness of the small-diameter nut 5 and the large-diameter nut 5, the small-diameter nut 6 cannot be tightened until it abuts against the large-diameter nut 5.

The bolt 1 and the nuts 5, 6 tightened in this way are first loosened by turning the small diameter nut 6 clockwise as viewed from above, and then loosened unless the large diameter nut 5 is turned counterclockwise. Because it is not possible, intentionally nut 5,
If it is not turned, it cannot be loosened, and there is no risk of inadvertent loosening.

The head 2 of the bolt 1 and the nuts 5, 6
Is not limited to a hexagon.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

[Explanation of symbols]

 1: Bolt 2: Head 3: Male thread under the neck 4: Reverse male thread 5: Large nut 6: Small nut

Claims (1)

[Claims] 1. A head portion, a male thread portion under the neck following the head portion, and an external diameter smaller than the inner diameter of the male thread portion under the neck, and a reverse male thread portion following the male thread portion under the neck in a reverse twist with the male thread portion under the neck. And a large-diameter nut screwed into the male screw portion under the neck, and a small-diameter nut screwed into the reverse male screw portion.