JP2000035027A - Bolt, nut, and fastening jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the easy removal of an object after fastening the object once with surplus work eliminated. SOLUTION: A head part 1a and nut 2 of a bolt 1 are formed into a truncated cone state having a large diameter on the seat surface side. Two wedgelike grooves 2a for applying force only in a fastening direction are formed on the head top surface of the nut 2. Consequently after an object is fastened once by simple structure, easy artificial removal can be impossible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bolts and nuts which cannot be easily removed manually once they are tightened during construction, such as bolts and nuts for fastening flanges of power transmission towers, and to a fastening jig. It is about tools.

[0002]

2. Description of the Related Art Normally, a bolt head and a nut are formed in a hexagonal column shape, and can be easily tightened or loosened with a spanner or a wrench. Moreover, even if it is formed in the shape of a polygonal pillar or a cylinder other than a hexagonal pillar, it can be tightened or loosened by forcibly grasping and rotating it with a pipe wrench or the like.

Various methods have been proposed and practiced for preventing such bolts and nuts from being loosened. This can be roughly divided into the following two methods. The first is a method of preventing loosening by adopting a double nut or incorporating a spring on the seat surface side of the nut. These methods take into account that loosening is performed again after tightening.

[0004] The other is a method for preventing loosening by deforming the bolt or nut after tightening the bolt and nut. This method does not consider removing once tightened. .

[0005]

By the way, for example, like a bolt and a nut for fastening a flange of a power transmission tower,
Once tightened at the time of construction, the former one of the above-described loosening prevention methods is not suitable unless it is semi-permanently removed. On the other hand, if the latter method is adopted,
Although it does not loosen easily, the structure is complicated and an extra operation of forcibly deforming the bolt or nut after tightening is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and does not require any extra work, and cannot be easily removed once tightened. It is intended to provide tools.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, according to the present invention, a head and a nut of a bolt are formed in a truncated cone shape having a large diameter on the seat surface side. And
In this way, once tightened, it cannot be easily removed using not only a spanner or wrench but also a pipe wrench.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The bolt of the present invention has a head formed in a truncated cone shape with a large diameter on the seat surface side. Are formed at two or more places.

Further, the nut of the present invention is formed in a truncated conical shape with a large diameter on the seat surface side. If necessary, a wedge-like shape is applied to the top surface only in the tightening direction. Groove
Two or more places are formed, or a hexagonal nut or a hexagonal column-shaped body provided with a through hole in the center is provided on the top surface through a thin portion.

Further, in the fastening jig of the present invention, a through hole is provided in a center portion of a hexagonal columnar body, and a wedge-shaped protrusion is formed on a seating surface to engage with a wedge-shaped groove formed on the top surface of the bolt or nut. A part is formed.

In the bolt and nut of the present invention, the seat surface side is formed in a large-diameter frusto-conical shape.
Since the seat surface has a large diameter, the force of the fastening tool can be applied in the fastening direction, and fastening can be performed. On the other hand, once tightened, the nut cannot be easily removed from the bolt since the force of the fastener cannot be applied in the loosening direction because the diameter of the top surface is small after the screw is once tightened.

[0012] In the bolt and nut of the present invention, a wedge-shaped groove, on which force acts only in the tightening direction, is formed on the top surface of the head.
When formed in more than one place, torque can be easily transmitted in the tightening direction. When the fastening jig of the present invention is used for this fastening, the fastening can be easily performed using a normal fastening tool such as a spanner.

In the nut according to the present invention, when a hexagonal nut or a hexagonal column having a through hole at the center is provided on the top surface of the head instead of the wedge-shaped groove through a thin portion, a wrench such as a spanner is used. Tightening can be easily performed using a normal tightening tool, and when a tightening torque greater than a specified torque is applied, the thin portion is sheared, and only the hexagon nut or hexagonal columnar body comes off, completing the tightening.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to one embodiment shown in FIGS. FIG. 1 shows a bolt according to claim 1 and a bolt according to claim 3.
FIG. 2 is an explanatory view of a state in which the flange is tightened by using the tightening jig of claim 5; FIG. 2 is an explanatory view of the nut of claim 3; It is explanatory drawing of the state which tightened the flange using the nut.

In FIGS. 1 and 2, reference numeral 1 denotes a bolt of the present invention, and a head 1a of the bolt is formed in a truncated conical shape having a large diameter on the seat surface side. Numeral 2 denotes a nut of the present invention, which is formed in a frusto-conical shape with a large diameter on the seat surface side, and has wedge-shaped grooves 2a on its top surface, for example, at two places where a force acts only in the tightening direction. Is formed.

Reference numeral 3 denotes a tightening jig of the present invention for easily tightening the nut 2 described above. The tightening jig has a hexagonal column shape so that it can be easily tightened by a spanner, for example, and has a screw 1 of a bolt 1 at the center. A through hole 3b having a diameter slightly larger than the outer diameter is provided, and a wedge-shaped protrusion 3a that engages with the wedge-shaped groove 2a is formed on the seat surface.

The bolt 1, the nut 2, and the tightening jig 3 of the present invention are configured as described above.
A case in which the flanges 5a and 5b are fastened to each other by using the nut 2, the fastening jig 3, and the spring washer 4 for preventing loosening will be described.

First, holes 5a provided in the flanges 5a and 5b
a, 5ba are overlapped concentrically, and these holes 5aa, 5ba
The shaft portion 1b of the bolt 1 is passed through ba. Next, the spring washer 4, the nut 2, and the tightening jig 3 are sequentially fitted to the shaft portion 1b of the bolt 1 protruding from the flange 5a, and temporarily tightened by artificial means.

In the above state, the nut 2 is tightened with the tightening jig 3 using a spanner while the head 1a of the bolt 1 is fixed. At the time of this tightening, the head 1a of the bolt 1 has a large diameter on the bearing surface side, so that a force can be applied in the tightening direction, and the bolt 1 can be fixed. Also, at the time of tightening, the wedge-shaped groove 2a provided on the top of the nut 2 engages with the wedge-shaped protrusion 3a provided on the seating surface of the tightening jig 3, so that the tightening jig 3 is tightened using a wrench. As a result, the nut 2 is inevitably tightened.

After the fastening is completed, only the fastening jig 3 can be easily removed as shown in FIG. In such a tightened state, the force of the fastener cannot be applied to the head 1a and the nut 2 of the bolt 1 in the loosening direction.
After tightening, the nut 2 cannot be removed from the bolt 1.

The bolt 1 of the present invention is not limited to the above-described structure, and may have two or more wedge-shaped grooves formed on the top surface of the head, like the nut 2, so that a force acts only in the tightening direction. . With this configuration, the bolt can be easily fixed at the time of tightening.

Further, the nut 2 is not limited to the above-described configuration.
Similar to the bolt 1 described above, a bolt without a wedge-shaped groove on the top surface may be used. However, in this case, since the hexagon nut 3 of the present invention cannot be used at the time of tightening, the tightening becomes slightly more difficult than when the wedge-shaped groove 2a is formed.

As shown in FIG. 3, instead of the nut 2 described above, a nut having a hexagonal nut 6c provided on a top surface of a truncated conical portion 6a having a large diameter on the seat surface via a thin portion 6b. 6 may be used. When this nut 6 is used, it can be easily tightened with a normal wrench. When a tightening torque exceeding a specified torque is applied to the hexagon nut 6c, the thin portion 6b is sheared, and the hexagon nut is tightened. When only 6c comes off, the tightening is completed.

In such a tightened state, since the head 1a of the bolt 1 and the nut 6 cannot exert the force of the fastener in the loosening direction, the nut 6 is removed from the bolt 1 after the tightening. Can not do. Needless to say, instead of the hexagon nut 6c, a hexagonal column having a through hole at the center may be provided.

In the above embodiment, the spring washer 4 was tightened in combination with a spring washer 4 to prevent loosening due to vibration or the like. Are not required.

[0026]

As described above, according to the present invention,
With a simple structure, once tightened, it cannot be easily and artificially removed. Also, bolts and nuts of the present invention,
Since the fastening jig has a simple structure, it can be manufactured not only by machining but also by forging.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a state in which a flange is tightened with a bolt and a nut according to claim 1 using a tightening jig according to claim 5;

FIG. 2 is an explanatory view of a nut according to claim 3;

FIG. 3 is an explanatory view of a state in which a flange is tightened by using the bolt of claim 1 and the nut of claim 4;

[Explanation of symbols]

 Reference Signs List 1 bolt 1a head 2 nut 2a wedge-shaped groove 3 fastening jig 3a wedge-shaped protrusion 3b through hole 6 nut 6b thin-walled portion 6c hexagon nut

Claims (5)

[Claims] 1. A bolt, wherein the head has a frusto-conical shape with a large diameter on the seat surface side. 2. A nut characterized in that the seat surface side is formed in a large diameter frusto-conical shape. 3. The bolt according to claim 1, wherein two or more wedge-shaped grooves are formed on the top surface of the head so that a force acts only in a tightening direction. 4. The nut according to claim 2, wherein a hexagonal nut or a hexagonal column having a through-hole at the center is provided on the top surface through a thin portion. 5. A fastening jig comprising: a through hole provided in a center portion of a hexagonal columnar body; and a wedge-shaped protrusion engaging with the wedge-shaped groove according to claim 2 formed on a seating surface.