JPH11325040A - Bolt fastening device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate fastening and removal of a large bolt, such as a foundation bolt for an iron tower, and to perform no removal of a nut used for fastening unless a specified tool is used. SOLUTION: A radial peripheral surface is formed in a tapered-off taper or a tapering-off curved surface and the peripheral surface thereof is formed as a rotary curved surface, and a nut 1 having a comparatively brittle tool mounting part on an outer periphery is threadedly engaged with a bolt 15. The body 13 of an axial force applying device 12 is threadedly mounted on the bolt 15 and by axially pressing the body 13 by a hydraulic device 14, the bolt is stressed and elongated. Only under a stress state, the nut 1 threadedly mounted on the bolt 15 is unfastened by a special tool mounted on a tool mounting part 3. Further, when the brittle tool mounting part 3 fits a tool therein and the nut is unfastened without using the axial force applying device 12, it is forded in a strength low enough to allow breakage thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening device for a large bolt such as a foundation bolt for fixing a leg of a tower of a high-voltage transmission line.

[0002]

2. Description of the Related Art Legs of a steel tower of a high-voltage transmission line are fixed to foundation concrete through large foundation bolts (anchor bolts). That is, the bolt holes in the legs are inserted into the foundation bolts protruding from the foundation concrete, and are fastened and fixed with nuts from above. However, since such a nut can be loosened and removed with a widely used spanner or the like, an accident in which the nut is loosened and the steel tower collapses occurs. In order to solve such a problem, a special nut which is difficult to remove with a normal wrench or the like has been proposed (Japanese Patent Application Laid-Open No. 7-219780). The nut body has a substantially trapezoidal outer cross section and a trapezoidal outer circumference. The nut body is different from the nut body by 180 degrees in the circumferential direction and the height H in the axial direction at the outer circumference of the nut body. It has a pair of slits formed at positions.

[0003]

However, when a tool is mounted on the special nut and a bolt is fastened, the shape and size of a portion where the tool is mounted on the nut are limited.
There is a limit in the rotational force for fastening or detaching the nut, and there is a problem that the larger the bolt, the more difficult the fastening and detaching operation becomes. Therefore, an object of the present invention is to provide a bolt fastening device that solves such a problem, and has the following configuration to achieve the object.

[0004]

According to the bolt fastening device of the present invention, a tool mounting portion having a tapered or tapered curved surface in the radial direction and a curved surface formed as a rotating surface, and having a relatively fragile outer periphery. 3 and an axial force applying device 12 screwed to a bolt 15 together with the nut 1, and the axial force applying device 12 is screwed to the bolt 15 to apply an axial force in a tightening direction. Only in this state, the nut 1 is fastened by the tool 8 mounted on the tool mounting portion 3 and the tightened nut 1 can be loosened, and the tool fitting portion 3 is provided with the axial force applying device. If a nut is loosened by inserting a tool into the nut without using the nut 12, the nut is formed to be fragile enough to be broken.

In a preferred embodiment of the fastening device, the tool mounting portion 3 has a projection 5 provided at an axial end 4 of the nut 1 or a hole 7 provided at an outer peripheral portion 6 of the nut 1. It is said. In another preferred embodiment of the fastening device, an axial force applying device 12 includes a cylindrical main body 13 screwed to a bolt 15 and a hydraulic device 1 for pressing the main body 13 in an axial direction.
4 is provided.

[0006]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a nut constituting a bolt fastening device of the present invention and a tool suitable for rotating the nut. The nut 1 has a trapezoidal outer periphery in the axial cross section, and an outer periphery is formed as a trapezoidal rotation curved surface. A relatively fragile tool mounting having an inner screw 2 in the center and a plurality of (four at 90 ° intervals in this example) columnar projections 5 at the end 4 on the small radius side at equal intervals. A part 3 is provided. An engaging portion 10 of a tool 8, which will be described later, is detachably engaged with the tool mounting portion 3. However, when a nut is fastened to a bolt without using an axial force applying device, which will be described later, or When it is loosened, it is fragile enough to break. Instead of providing the protruding portion 5 at the end portion 4, the tool mounting portion 3 may be formed by providing a plurality of circular holes 7 having a circular cross section as shown by a dotted line in the outer peripheral portion 6. The projection 5 may have a rectangular column shape such as a square or hexagonal cross section, and the hole 7 may have a square hole shape such as a square or hexagonal cross section.

[0007] The nut 1 may have a trapezoidal slope not formed in a straight line but in a curved surface slightly convex outward or a curved surface slightly concave inward. Further, the trapezoidal slope may be formed by a plurality of broken lines. In the present invention, these curved surfaces and FIG.
Include a straight line such as The tool 8 has an elongated flat-shaped handle 9 and a flat-shaped engaging portion 10 which is bifurcated and extends therefrom. An arc-shaped concave portion 11 having an inner diameter capable of engaging with the protrusion 5 is formed inside each of the distal ends of the engaging portion 10. In the case where a plurality of holes 7 indicated by dotted lines in FIG. 1 are provided as the tool mounting portion 3, a tool having a columnar tip having an outer diameter that can be inserted into the inner diameter of the hole 7 is used as a hooking portion. Can be used.

FIG. 2 shows a state in which a leg portion of a steel tower is fastened to or detached from a foundation bolt (hereinafter simply referred to as a bolt) by combining an axial force applying device constituting the bolt fastening device of the present invention and the nut 1 described above. It is a fragmentary perspective view. The axial force applying device 12 includes a cylindrical main body 13 screwed to the bolt 15.
And a hydraulic device 14 for pressing the main body 13 in the axial direction (upward in FIG. 2). The body 13 has an inner screw 1 whose radius is changed in a stepped shape, and which is screwed to a bolt 15 at the center thereof.
6 are formed. The outer periphery of the upper portion having a large radius is knurled to prevent slipping, and a plurality of rotation holes 17 are formed at equal intervals. The outer periphery of the lower portion having a small radius is slidable in the hydraulic device 14 in the axial direction. And it is mounted coaxially.

The hydraulic device 14 has an annular cylinder 18 disposed around the lower periphery of the main body 13 and an annular piston 19 mounted in the cylinder 18 and moving up and down. The cylinder 18 is provided with a pipe connection part 20 for connecting a hydraulic pipe. A cylindrical support 21 is connected to a lower portion of the cylinder 18.
A part of the support 21 is cut out so as to form an opening 22, and a nut 1 can be rotated by inserting a tool from the opening 22 as described later.

Next, the operation of the bolt fastening device according to the present invention will be described with reference to FIG. 2. The bolt 15 buried in the foundation concrete 23 is inserted into a bolt hole of the installation base 24 in the leg of the steel tower. The hydraulic connection from the hydraulic control device is connected to the piping connection section 20 of the hydraulic device 14. To fasten the bolt in this state, first, the nut 1 is temporarily screwed to the bolt 15 while rotating by hand. Next, the body 13 of the axial force applying device 12 is rotated by hand and screwed to the bolt 15 so as to cover the nut 1, and stopped at a position where the bottom of the support 21 contacts the upper surface of the installation base 24. If necessary, a rod-shaped tool is inserted into the hole 17, and the main body 1 is rotated so that the bottom of the support 21 is strongly pressed against the upper surface of the installation base 24.

Next, when a hydraulic pressure is supplied from a hydraulic control device (not shown) and a lifting force is applied to the piston 19 of the hydraulic device 14, the main body 13 tightens the bolt 15 (that is, the bolt 15).
In the axial direction). Then, the bolt 15 is stretched to form a gap between the nut 1 and the installation base 24, so that the tool 8 is inserted through the opening 22 of the support 21, and the engaging portion 10 is engaged with the tool mounting portion 3 of the nut 1. And attach it. Then, by rotating the tool 8 in a direction in which the nut 1 is tightened, the nut 1 is fastened to the bolt 15 with a predetermined axial force. When one nut 1 is fastened, the axial force applying device 12 is removed from the bolt 15 and the operation proceeds to the next bolt fastening operation. Alternatively, by using a plurality of axial force applying devices 12, nuts can be fastened to a plurality of bolts in parallel and with a uniform fastening force.

Next, the nut 1 fastened as described above
In order to detach the bolt from the bolt 15, the body 13 of the axial force applying device 12 is first turned by hand so as to cover the nut 1 and screwed onto the bolt 15 in the same manner as in the above-described fastening operation.
1 stops at a position where the bottom portion contacts the upper surface of the installation base 24. Next, when a hydraulic pressure is supplied from the hydraulic control device to apply a lifting force to the piston 19 of the hydraulic device 14 to tighten the bolt 15, the bolt 15 is stretched and a gap is generated between the nut 1 and the installation base 24. Then, the tool 8 is inserted through the opening 22 of the support 21, the engaging portion 10 is engaged with the tool mounting portion 3 of the nut 1, and the tool 8 is rotated to loosen the nut 1. Next, the axial force applying device 1
Remove 2 and loosen nut 1 by hand to detach. In addition,
The tool fitting portion 3 of the nut 1 is connected to the axial force applying device 12.
When a nut is loosened by fitting an appropriate tool into the nut without using the nut, the nut is formed to be weak enough to be damaged.

[0013]

According to the bolt fastening device of the present invention, since the outer peripheral surface of the nut is formed as a tapered or tapered curved surface and as a rotating curved surface, it cannot be gripped by a normal tool. Moreover, nuts cannot be fastened or removed without using an axial force application device together with a specific tool, so it is necessary to effectively prevent loosening and removal of nuts at the foundation of the high-voltage power transmission tower. Can be. In addition, even a large nut can be easily fastened or detached. Further, the bolt can be fastened with a predetermined axial force by the axial force applying device.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a nut constituting a bolt fastening device of the present invention and a tool attached to the nut.

FIG. 2 is a partially broken perspective view showing a state in which bolts are fastened or detached using the nut and the axial force applying device of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nut 2 Internal screw 3 Tool mounting part 4 End part 5 Projection part 6 Outer part 7 Hole part 8 Tool 9 Handle part 10 Engagement part 11 Concave part 12 Axial force applying device 13 Main body 14 Hydraulic device 15 Bolt 16 Internal screw 17 Hole part 18 Cylinder 19 Piston 20 Piping connection 21 Support 22 Opening 23 Foundation concrete 24 Installation base

Claims (3)

[Claims] 1. A peripheral surface in a radial direction is a tapered or tapered curved surface, and the peripheral surface is formed as a rotating curved surface,
A nut 1 having a relatively fragile tool mounting portion 3 on its outer periphery, and an axial force applying device 12 screwed to a bolt 15 together with the nut 1, and the axial force applying device 12 is screwed to the bolt 15. The nut 1 is fastened by the tool 8 mounted on the tool mounting portion 3 and the fastened nut 1 can be loosened only when the axial force is applied in the direction in which the tool is tightened. When the tool 3 is inserted into the part 3 to loosen the nut without using the axial force applying device 12,
A bolt fastening device characterized in that it is formed fragile enough to break. 2. The tool mounting portion according to claim 1, wherein the tool mounting portion is a protrusion provided on an axial end portion of the nut, or a hole provided on an outer peripheral portion of the nut. Bolt fastening device. 3. An axial force applying device according to claim 1, wherein the axial force applying device includes a cylindrical main body screwed to the bolt, and a hydraulic device for pressing the main body in the axial direction. The bolt fastening device as described in the above.