JP2940869B1 - Bolt and nut removal prevention structure - Google Patents

Abstract

An object of the present invention is to provide a bolt / nut removal preventing structure in which rotation of a fixing nut is accurately prevented at a stage after bolting and joining of an object to be fixed. SOLUTION: A stopper nut 6 fitted to a bolt 3 next to a fixing nut 5, a main body portion 6a into which an opening end side portion 7a of a cover cylinder 7 is idlely fitted,
When the cover operating member 7b on the inner rear side of the cover cylinder 7 is fitted with the passive portion 6b, the stopper nut 6 is turned when the cover cylinder 7 is turned to tighten the main body portion 6a to the fixing nut 5. Vulnerable part 6 between main part 6a and passive part 6b
It is broken at c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt / nut removal prevention structure which disables rotation of a fixing nut after tightening and prohibits disassembly or disengagement of a fixing object.

[0002]

2. Description of the Related Art There has been reported an unrest situation in which an installation bolt of a power transmission tower or a rail fixing bolt of a shinkansen is removed by a person other than an authorized administrator. This happens because in the conventional bolted joint structure, the nut fitted to the head of the bolt or the shaft of the bolt is exposed unprotected, and an outsider can easily attach the bolt or nut. Because it can be turned.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a bolt / nut removal preventing structure in which rotation of a fixing nut is accurately prevented at a stage after bolting of an object to be fixed. That is.

[0004]

Means for Solving the Problems Hereinafter, with reference to the reference numerals in the accompanying drawings, in the structure for preventing removal of bolts and nuts according to the present invention, the bolts and nuts are inserted into the through holes 2 and 2 of the fixing objects 1 and 1. The fixing nut 5 and the stopper nut 6 are sequentially fitted to the shaft portion 4 of the bolt 3, and the stopper nut 6 is fitted to the opening end side portion 7 a of the cover cylinder 7 so as to be able to rotate freely. Main part 6 to be tightened
a, while being not fitted to the shaft portion 4 of the bolt 3, being fitted to the drive operation portion 7 b on the inner side of the cover cylinder 7,
A cover cylinder 7 and a passive part 6b that rotates integrally,
The strength of the fragile portion 6c is set such that the stopper nut 6 is broken at the fragile portion 6c between the main portion 6a and the passive portion 6b when the main body portion 6a is tightened to the fixing nut 5 by turning the cover cylinder 7. Do.

[0005] In use, the shaft 4 of the bolt 3 is inserted from one side of the through holes 2 and 2 of the objects 1 and 1, and the fixing nut 5 is fitted to the shaft 4 protruding to the other side. The two fixing objects 1 and 1 are joined by bolting. The main body portion 6a of the stopper nut 6 is further screw-fitted to the bolt shaft portion 4 protruding from the fixing nut 5, and the cover cylinder 7 fitted to the stopper nut 6 is turned by a rotary operating tool such as a spanner or a torque wrench. Then, the stopper nut 6 is fastened to the fixing nut 5 by six. At this time, the rotational force from the cover cylinder 7 is transmitted from the drive operation portion 7b to the passive portion 6b of the stopper nut 6. When the main portion 6a of the stopper nut 6 is tightened to the fixing nut 5 with a required torque, a break occurs in the weak portion 6c, and the stopper nut 6 is divided into the main portion 6a and the passive portion 6b.

After this separation, the passive portion 6b of the stopper nut 6 which is not screwed into the shaft portion 4 of the bolt 3
Rotates integrally with the cover cylinder 7, but the cover cylinder only idles with respect to the main body 6 a of the stopper nut 6, and the transmission of rotational force from the cover cylinder 7 to the main body 6 a Will be shut off. Therefore, an outsider can use the cover 7
Is turned, the main part 6a of the stopper nut 6 is kept in the original tightening position, and even if an outsider tries to turn the fixing nut 5, the bolt shaft 4 of the fixing nut 5 is turned. Is stopped by the stopper nut 6. Thus, the bolt 3 and the fixing nut 5
Unauthorized removal is prevented.

[0007]

In the embodiment shown in FIGS. 1 and 2, the outer shape of the main portion 6a of the stopper nut 6 is circular, and the outer shape of the passive portion 6b is hexagonal.
Correspondingly, the opening end side portion 7a of the cover cylinder 7 is formed in a cylindrical shape, and the drive operation portion 7b on the inner rear side is formed in a hexagonal cylinder shape. Fragile part 6c of nut 6 for stopper
Is constituted by an annular groove, and the required breaking limit strength is set by changing the depth of the groove. The outer peripheral side of the drive operation portion 7b of the cover cylinder 7 is formed as a passive cylinder portion 7c having a hexagonal cross section into which a rotary operation tool such as a box spanner or a torque wrench is fitted. An extended cylindrical portion 7d that covers most of the adjacent fixing nuts 5 is formed in the opening end side portion 7 of the cover cylinder 7, making it difficult or impossible to access the fixing nut 5 itself.

At the front edge of the main portion 6a of the stopper nut 6, there is formed a tapered portion 6d whose diameter decreases toward the front end. The front end edge 7e of the opening end side portion 7 of the cover body 7 is crimped by pressing toward the tapered portion 6d. The stopper nut 6 and the cover cylinder 7 are separated from the stopper cylinder 6 by the stopper cylinder 6. It is assembled so that it is not removed. In the embodiment shown in FIG. 3, the cover body 7 is formed as a hexagonal cap nut type. Unlike this embodiment, the cover cylinder 7 does not have an extension cylinder portion, and the fixing nut 5 adjacent thereto is entirely exposed. The front end edge portion 7e of the opening end side portion 7a of the cover body 7 is crimped toward the tapered portion 6d of the main body portion 6a of the stopper nut 6 similarly to the above embodiment, and the stopper nut 6 and the cover cylinder are formed. 7 is assembled inseparably.

[0009]

According to the bolt / nut removal prevention structure of the present invention configured as described above, the stopper nut 6
When the stopper nut 6 is turned through the cover cylinder 7 fitted to the nut and the stopper nut 6 is tightened to the fixing nut 5 by a required torque, the stopper nut 6 breaks at the weak portion 6c, and the fixing nut 6 5 and a passive part 6b connected to the cover body 6.
Therefore, the main body portion 6a is fixedly held at a position where the main body portion 6a is fastened to the fixing nut 5. Therefore, the movement of the fixing nut 5 to be removed by rotation is completely prevented by the main portion 6a of the stopper nut 6, and the fixing nut 5 and the bolt 3 are properly protected from unauthorized removal.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a bolt / nut removal prevention structure according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a longitudinal sectional view of a bolt / nut removal preventing structure according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing object 2 Fixing object through hole 3 Bolt 4 Bolt shaft part 5 Fixing nut 6 Stopper nut 7 Cover cylinder

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16B 41/00 F16B 31/02

Claims (1)

(57) [Claims] 1. A fixing nut 5 and a stopper nut 6 are sequentially fitted to a shaft portion 4 of a bolt 3 inserted into the through holes 2 and 2 of the fixing objects 1 and 1, and the stopper nut 6 is
An opening end side portion 7a of the cover cylinder 7 is fitted so as to be able to rotate idly, and a main portion 6a which is fastened to the fixing nut 5;
The cover cylinder 7 is not fitted to the shaft portion 4 of the bolt 3, but is fitted to the drive operation section 7 b on the inner side of the cover cylinder 7, and is constituted by a passive portion 6 b that rotates integrally with the cover cylinder 7. When the main part 6a is tightened to the fixing nut 5 by turning the bolt, the strength of the fragile part 6c is set such that the stopper nut 6 is broken at the fragile part 6c between the main part 6a and the passive part 6b. Nut removal prevention structure.