JP2000104720A - Tamperproof cover for bolt or nut - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent tampering release of bolts or nuts. SOLUTION: This tamperproof cover 1 for bolts or nuts has a conic outer form and an internally hexagonal socket 2 fitting closely on a hexagonal bolt head or hexagonal nut 4 to cover it. When pressed on the hexagonal nut 4, by way of example, the tamperproof cover 1 fixes to it tightly. The outer conical surface causes any tool such as wrenches trying to grip and turn the tamperproof cover 1 to slip on it to thereby prevent removal of the tamperproof cover 1 and loosening of the hexagonal nut 4 as well. An expedient in such a manner prevents tampering release of bolts or nuts with reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In the present invention, it is necessary to strictly prevent removal of bolts or nuts, such as bolts and nuts connecting the legs of the main pillar of a power transmission tower to the foundation side. The present invention relates to a bolt or nut extraction prevention cover for preventing a bolt or nut from being artificially extracted at a location.

[0002]

2. Description of the Related Art For example, legs of main pillars of power transmission towers are generally connected to foundation-side steel columns embedded in foundation concrete with bolts and nuts. For example, when a steel pipe is used as the main pillar, the flanges welded and fixed to the respective end faces of the main pillar made of steel pipe and the base-side iron pole are fastened and fixed with a large number of bolts and nuts. Conventionally, bolts and nuts for these connections are usually provided with a lock, but no special measures are taken against artificial bolt or nut removal.

[0003]

Recently, an accident in which a tower of an existing transmission line collapsed occurred. The cause of the accident was not merely an accident, but as described above, the legs of the main pillar of the transmission tower and the base side. There is a suspicion that the bolt connecting the steel pole was artificially removed. In addition, other than the power transmission tower, if bolts or nuts are removed, there is a possibility that serious consequences may be caused. Therefore, it is desired to prevent the bolt or nut from being reliably removed. The prevention of nut removal and the prevention of bolt removal are usually substantially the same. For example, when a base plate of a machine is fastened and fixed to a foundation bolt embedded in a concrete foundation, only the removal of the nut is prevented.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is not merely intended to prevent a bolt or a nut from being loosened, but also a bolt or a nut that can be prevented from being artificially removed. It is intended to provide a protective cover.

[0005]

A bolt or nut pull-out preventing cover according to the present invention which solves the above-mentioned problem has a conical outer shape, and is tightly fitted inside a hexagonal bolt head or nut. It is characterized by having a hexagonal recess covering the head of the hexagon bolt or the hexagon nut.

A second aspect of the present invention is characterized in that a groove extending in the depth direction of the recess is formed at the corner of the hexagonal recess in the bolt or nut removal prevention cover of the first aspect.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to an embodiment shown in FIGS. FIG. 1 is a longitudinal sectional view (BB sectional view of FIG. 2) of a use state of a bolt or nut pull-out prevention cover (hereinafter abbreviated as pull-out prevention cover) 1 according to an embodiment of the present invention, and FIG. A-
It is A sectional drawing. As shown in the figure, the extraction preventing cover 1 has a conical outer shape, and has a hexagonal recessed portion inside which is tightly fitted to a hexagonal bolt head or hexagonal nut to cover the hexagonal bolt head or hexagonal nut. 2. The extraction prevention cover 1 can be manufactured by processing steel, an aluminum alloy, or the like, or by molding a resin such as a thermosetting or thermoplastic resin.

In the illustrated example, it is substantially impossible to artificially remove a hexagonal nut (hereinafter simply referred to as a nut) 4 screwed and fastened to the bolt 3 (thus, it is impossible to remove the bolt 3). The hexagonal recess 2 of the anti-extraction cover 1 is fitted to the nut 4. The hexagonal recess 2 is machined in accordance with the hexagonal shape of the nut 4, but the interval between the opposite sides is set slightly smaller than the interval between the opposite sides of the target nut 4, and the hexagonal recess 2 is tightly fitted to the nut 4 and firmly fixed. I am trying to be.

In this embodiment, the hexagonal recess 2
At each of the corners, for example, a semicircular groove 5 extending in the depth direction of the recess (the longitudinal direction of the bolt 3) is formed. When the groove 5 is provided in each corner as described above, the removal prevention cover 1
When the inner surface 2a of the hexagonal recess 2 is pressed against the outer peripheral surface 4a of the nut 4 by being press-fitted into the nut 4, the outer peripheral surface 4a of the nut 4 is easily elastically compressed and deformed. A repulsive force of compression can be exerted, a strong frictional force is generated, and the pull-out prevention cover 1 can be firmly fixed to the nut 4.

When the hexagonal recess 2 is press-fitted into the nut 4, the above-mentioned pull-out preventing cover 1 is tightly fitted to the nut 4 and firmly fixed thereto. And the removal prevention cover 1
Since the outer peripheral surface of this is a conical surface, even if it is gripped and turned with a tool such as a wrench, it cannot be slid and turned. Therefore, the removal prevention cover 1 can be removed and the nut 4 can also be turned. I can't do it. Therefore, the nut 4 and the bolt 3 cannot be practically removed.

In this embodiment, the nut 4 screwed to the bolt 3 is exposed, and the exposed nut 4 cannot be turned to prevent the bolt 3 from being removed. When the head of the bolt is exposed, the pull-out prevention cover 1 is put on the head of the hexagonal bolt so that the bolt cannot be turned. In the above embodiment, when the bolt 3 is an embedded bolt, the nut 4 is simply prevented from being pulled out.

The outer shape of the pull-out preventing cover is usually a truncated conical shape in which the vertex side of the conical shape is cut off horizontally as shown in the figure, but it is assumed that the outer shape is a normal conical shape excluding the vertex side. Not excluded.

In the above-described embodiment, for example, when the legs of the main pillar of the transmission tower are joined to the foundation-side steel pillar embedded in the foundation concrete with bolts and nuts, that is, both are made of steel pipe. It is assumed that the flanges welded and fixed to the respective end faces of the main pillar and the foundation-side steel pole are fastened and fixed with a large number of bolts and nuts. Can be applied to various facilities that cause

[0014]

The bolt or nut removal prevention cover of the present invention has a conical outer shape, and is tightly fitted inside the hexagonal bolt head or hexagonal nut to fit the hexagonal bolt head or hexagonal nut inside. Is press-fitted into the head of a hexagon bolt or a hexagon nut, it is firmly fixed to the head or nut of the bolt and cannot be easily removed. And since the outer peripheral surface is a circumferential surface, even if it grips and turns it with a tool such as a wrench, it cannot be slid and turned, so that the bolt or nut cannot be turned, and It is possible to reliably prevent the removal of a bolt or nut.

According to the second aspect of the present invention, since the hexagonal recess is provided with a groove in the corner, when the anti-extraction cover is pressed into the bolt head or the nut, each inner surface of the hexagonal recess is radially outward. The pull-out prevention cover is tightly fitted to the bolt head or nut by the strong repulsive force of the elastic compression, and the pull-out prevention cover is firmly attached to the bolt head or nut by strong frictional force. Can be fixed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view (BB sectional view of FIG. 2) of a use state in which a bolt or nut removal prevention cover of one embodiment of the present invention is covered with a nut.

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

[Explanation of symbols]

1 Extraction prevention cover (bolt or nut extraction prevention cover) 2 Hexagonal recess 2a Inner surface (of hexagonal recess) 3 Bolt 4 Nut 4a Outer peripheral surface 5 Groove

Claims (2)

[Claims] 1. A hexagonal recess (2) having a conical outer shape and having a hexagonal bolt head or hexagonal nut tightly fitted to cover the hexagonal bolt head or hexagonal nut inside. A cover for preventing removal of bolts or nuts. 2. The bolt or nut pull-out prevention cover according to claim 1, wherein a groove (5) extending in a depth direction of the recess is formed at a corner of the hexagonal recess (2).