JPH01246381A - Anticorrosive structure of bolt thread part - Google Patents

Abstract

PURPOSE:To isolate a bolt thread part from the external environment and to surely prevent the corrosion over a long period by closely covering the thread part of the bolt fastened by a nut with a packing material packed in the internal space of a cap. CONSTITUTION:Coupling plates 1 are connected by a bolt 2 and a nut 4. The packing material 6 such as ordinary mortar is prepared in the amt. sufficient to till the internal space of the cupped cap 5 having an engagement hole 5a wherein the bolt 2 can be screwed at its for position. A part of the material 6 is applied on the thread part 2a and the nut 4, the remainder is placed in the cap 5, the thread part 2a is screwed into the hole 5a until the cup 5 abuts in the coupling plate 1, and the material 6 is closely packed in the cap 5 to cover the thread part 2a and nut 4 with the material 6. As a result, the thread part 2a is perfectly isolated from the external environment, and the corrosion can be surely prevented over a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure for preventing corrosion of a threaded portion of a bolt that is fastened with a nut.

``Conventional technology'' Since the threaded part of a bolt is manufactured by cutting the shaft part,
The cross-sectional area of the bolt is the smallest at the threaded part, and its tensile strength (
The axial force) is determined by the cross-sectional area of the threaded portion. Therefore, as long as the threaded portions of bolts and nuts are intact and free from corrosion, there will be no problem in terms of strength even if there is a slight reduction in the cross section due to corrosion of the shaft or head.

Conventionally, this type of fastening structure using bolts and nuts has been
Although it is widely applied in various fields, consideration must be given depending on the environment in which the bolt is used (such as the place where it is used). for example,
Segment joint bolts for shield tunnels and mounting bolts for attaching facilities in basements, etc.
Since the environment in which these bolts are used is under adverse conditions such as water leakage or high humidity, special consideration is required to prevent bolt corrosion.

Conventionally, taking these points into consideration, weather-resistant steel is used for the bolt itself, or the surfaces of bolts, nuts, and washers are coated with anti-corrosion coatings by baking, gluing, painting, etc. method is adopted.

[Problems to be Solved by the Invention] However, with such conventional bolt corrosion prevention means, the following problems remain to be solved.

■ If weather-resistant steel is used for bolts, the service life will be extended compared to ordinary steel, but rusting is inevitable, and as a result, the threaded part of the nut will rust, making it difficult to remove it when replacing the bolt. Problems such as difficulty remaining.

■ On the other hand, with methods of coating the surfaces of bolts, nuts, washers, etc., the coating on the bolt threads or the female threads of the nut may be peeled off and damaged when the nut is tightened. Corrosion may occur in some places.

■ In addition, when such a coating method is applied, the outer diameter of the threaded part is expanded by the thickness of the coating, so the inner diameter of the nut must be increased accordingly. Countermeasures such as increasing the strength may have to be taken, and there is a risk that the desired strength will not be obtained.

Furthermore, even with such a coating method, if the threaded part of the bolt corrodes, the nut will often become rusty and will not rotate, and in this case, it cannot be removed without resorting to melting down the bolt head, so it is difficult to replace it. There was a problem that the work was time-consuming.

SUMMARY OF THE INVENTION It is an object of the present invention to effectively solve the problems in the prior art, and to provide a corrosion-protective structure for bolt threads that does not cause corrosion of the bolt threads.

"Means for Solving the Problems" In order to achieve the above object, the present invention provides a structure for preventing corrosion of a threaded portion of a bolt that is fastened with a nut, the threaded portion of the bolt being covered with the nut. The device is characterized by comprising a cap screwed onto the cap, and a filling material filled in the inner space surrounded by the cap so as to embed the inner space.

Further, in order to achieve the same object, the present invention provides a structure for preventing corrosion of a threaded portion of a bolt fastened with a nut, the structure being inserted into the outer periphery of the bolt threaded portion and from the nut and the upper end surface of the nut. A mold body having a texture that surrounds a protruding bolt thread part, a pressurizing nut that is screwed onto the bolt thread part and presses the mold body, and a filling state in which this inner space is embedded in the inner space of the mold body. It has a structure consisting of a filler packed in.

``Function'' In the anti-corrosion structure configured as described above, the threaded portion of the bolt to which the nut is tightened is covered with a filling material filled in the inner space of the cap or mold body, and is protected from the external environment. Since it is blocked, corrosion is reliably prevented over a long period of time.

"Example" Hereinafter, an example of the present invention will be described with reference to the drawings. Note that these drawings show an example in which the present invention is applied to prevent corrosion of joint bolts of segments, but the present invention is not limited to the case of corrosion-proofing the joint bolts shown in the illustrations, and may be applied to other joint bolts. Needless to say, it can also be applied to corrosion protection of bolt threads.

1 and 2 show a first embodiment of the present invention, and FIG. 1 is a sectional view showing a corrosion-protective structure of a bolt thread. In the figure, what is designated by the symbol l is a joint plate for connecting segments that is provided in segments (for example, concrete segments, etc.), and this joint plate 1 is provided with bolt insertion holes 1a. Into the bolt insertion hole 1a of this joint plate l, a bolt (11 hand bolt) 2 for interconnecting these joint plates l is inserted through a washer 3, and this bolt 2 has a threaded portion thereof. They are integrally tightened by a nut 4 screwed onto 2a.

A cap 5 is screwed onto the threaded portion 2a of the bolt 2 that protrudes beyond the upper end surface 4a of the nut 4 so as to cover the nut 4, and an inner space surrounded by the cap 5 The filling material 6 is filled in such a way as to fill this inner space.

As shown in FIG. 2, the cap 5 is formed into a bowl shape made of a corrosion-resistant material such as steel, aluminum, stainless steel, or plastic, and has a top surface that is fitted with a bolt 2. A hole 5a is formed. The height σ8 of this cap 5 is greater than the sum of the length of the washer 3 and the nut 4, and the inner diameter of the lower end opening is e.

is set larger than the outer diameter of the washer 3, and is formed so as to ensure a sufficient coating thickness of the filler 6 to protect the threaded portion 2a from corrosion.

In the illustrated example, the fitting hole 5a of the cap 5 has a shape that matches the pitch of the root diameter of the bolt threaded portion 2a, so that the cap 5 can be screwed into the bolt threaded portion 2a. . In addition, when the cap 5 is made of metal, in order to form the fitting hole 5a like this, the cap 5
Drill a hole in the top of the box, cut out the periphery with a chisel,
This cutout portion may be processed to match the pitch of the threaded portion 2a. Furthermore, if the cap 5 is made of resin, the entire cap 5 may be molded using resin.

On the other hand, as the filler 6 packed inside the cap 5, a material is selected that has appropriate fluidity during construction and has a viscosity that does not harden or flow out from the cap 5 after construction. Examples include ordinary mortar, air mortar, lightweight mortar, resin mortar, and oil-based materials (eg, grease).

Next, the operation of the anticorrosion structure of the present invention configured as described above will be explained.

As shown in FIG. 1, etc., in order to prevent corrosion of the threaded portions 2a of the bolts 2 that connect the joint plates 1 of the segments, first connect the joint plates 1 with the bolts 2 and nuts 4, and then enough to fill the space (i.e.
Prepare an amount of filler 6 (enough to cover the threaded part 2a, washer 3, and nut 4 with an appropriate thickness), apply some of it around the threaded part 2a and the nut 4, and apply the rest to the cap. Put it within 5. Next, when the threaded portion 2a is fitted into the fitting hole 5a of the cap 5 and rotated in the tightening direction, the circumference of the opening of the cap 5 is tightened.

The cap 5 is tightened until the edge comes into contact with the joint plate 1, and the filler 6 is fully packed inside the cap 5, so that the periphery of the threaded portion 2a and the nut 4 is covered with the filler 6. At this time, the remaining filler 6 that was put into the cap 5 leaked to the outside through the gap between the fitting hole 5a and the threaded part 2a, and the filler 6 was completely packed into the cap 5. becomes clear. Note that the portion exposed from the cap 5 may be prevented from corrosion by applying a conventional coating method or the like.

In this construction work, after connecting bolt 2 and nut 4,
This is a simple task of applying the filler 6 to the threaded portion 2a of the bolt 2 and the outer periphery of the nut 4, and tightening the cap 5 onto the threaded portion 2a with the filler 6 placed inside the cap 5. In this case, no special technology is required, and the cap 5 can be mass-produced, so that costs can be reduced.

As shown in FIG. 1, when the threaded portion 2a and the like are covered with the filler 6 packed into the internal space of the cap 5 (that is, in a corrosion-protected state), the threaded portion 2a surrounded by the cap 5 is filled with the filling material 6. Since the threaded portion 2a is covered with the material 6 and is completely isolated from the external environment, the threaded portion 2a will not corrode. Therefore, the service life of the bolt threaded portion 2a can be expected to be the same as that of the reinforcing bars of reinforced concrete.
The strength of the bolt 2 can be maintained over a long period of time.

In the embodiment, the filler 6 is stuffed into the cap 5 by tightening the cap 5, so the tightening force of the cap 5 is particularly low when a mortar-based material with adhesive strength is used as the filler 6. This has the advantage of pressurizing the mortar, increasing its adhesion and density, and improving its anticorrosion effect. In addition, with this configuration, if water leaks from the bolt insertion hole 1a due to a joint bolt of a N'Wold tunnel, etc., if the amount of water leakage is small and the water pressure is less than the tightening force of the cap 5, Its water-stopping effect can be expected.

Further, when corrosion-proofing bolts on an upper part such as a ceiling, since the cap 5 is screwed onto the bolt threaded portion 2a, there is an advantage that the filler material 6 is prevented from falling off.

By the way, if the bolt 2 needs to be replaced, the cap 5 and the filler 6 can be removed by hitting them with a chisel and a hammer, etc., and the bolt threaded portion 2a and nut 4 are free from rust. Therefore, Natsuto 4
It can be easily removed and its workability can be improved.

In addition, in order to prevent corrosion of the bolt 2 that has already been used to connect segments, etc. and whose surface has rusted, it is not necessary to remove the rust that has adhered to the surface, and the progress of corrosion can be stopped by just removing the floating rust. Therefore, it has the advantage of good workability.

FIG. 3 shows a second embodiment of the present invention, in which, instead of the cap 5 shown in FIG. 1, several screw grooves 5b are provided on the top surface.
A cap 5A having a fitting hole 5a is screwed onto a bolt threaded portion 2a, and a filler 6 is placed inside the cap 5A. Note that such a cap 5A is integrally molded, for example, from ceramics.

It should be noted that even with the anti-corrosion structure having such a configuration, substantially the same effects as those of the previous embodiment can be achieved.

Next, a third embodiment of the present invention will be described with reference to FIG.

The anti-corrosion structure of this embodiment includes a mold main body IO which is inserted into the outer periphery of the bolt threaded portion 2a and surrounds the nut 4 and the bolt threaded portion 2a protruding from the upper end surface of the nut 4, and a mold body IO which is inserted into the outer periphery of the bolt threaded portion 2a and which is inserted into the bolt threaded portion 2a. The basic structure consists of a pressurizing nut 11 that is fitted together and presses the mold body IO, and a filler 6 that is fully packed into the inner space of the mold body 10 so as to fill this inner space.

The mold body IO is made of steel, aluminum, stainless steel,
It is formed into a bowl shape from a corrosion-resistant material such as plastic, and has a bolt insertion hole 10a in its top surface.

Further, the pressurizing nut 11 connects the mold body lO to the threaded portion 2.
It is fixed when inserted around the outer periphery of a.

A female thread Ila is formed to be screwed into the threaded portion 2a.

On the other hand, as the filler 6 packed into the mold body 1O, the same filler as shown in FIG. 1 is used, so the explanation thereof will be omitted.

FIG. 5 shows a fourth embodiment of the present invention, in which a cylindrical mold body 10A is inserted into the outer periphery of the bolt 2 instead of the bowl-shaped mold body 10 shown in FIG.

In addition, in the case of such a configuration, the pressure nut 1
Since the filler 6 can be directly pressed by the filler 1 itself, the filler 6 can be pressurized well.

"Effects of the Invention" As explained above, the present invention provides the following excellent effects.

■ The threaded part of the bolt where the nut is tightened is covered by the cap screwed onto this threaded part or the filler packed in the inner space of the mold body and is shielded from the external environment. corrosion can be reliably prevented over a long period of time. In addition, the cap, mold body, filling material, etc. can be easily disassembled, and
Since the threaded portion and nut are not rusted, there is an advantage that bolt replacement can be easily performed.

(2) Furthermore, as described above, in order to prevent corrosion of already rusted bolts, it is not necessary to remove even the rust that has adhered to the surface, and the progress of corrosion can be stopped by just removing the floating rust, which has the advantage of good workability.

(2) Moreover, since the filler is prevented from falling off by the cap or the mold body, it is possible to improve the applicability to bolts attached to ceilings, etc., for example.

(2) Since the filler is pressurized by the tightening force of the cap or the pressurizing nut, it has the advantage of increasing its adhesion to the threaded portion and its density, thereby improving the anticorrosion effect.

■ Also, as mentioned above, if there is water leakage from the bolt hole, if the amount of water leakage is small and the water pressure is less than the tightening force of the cap or pressure nut, there is an advantage that the water can be stopped. .

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention; FIG. 1 is a cross-sectional view, FIG. 2 is a half-sectional view for explaining the cap, and FIG. 3 is a cross-sectional view of the present invention. 4 is a sectional view showing the second embodiment of the present invention, FIG. 4 is a sectional view showing the third embodiment of the present invention, and FIG.
The figure is a sectional view showing a fourth embodiment of the present invention. ■...Joint plate, la...Bolt insertion hole, 2...Bolt, 2a...Threaded part, 3
...Washer, 4...nut, 5.
... Cap, 5a ... Fitting hole, 5b.
...Thread groove, 6...Filling material, 10.10
A... Mold body, 10a... Bolt insertion hole in the mold body, II... Pressure nut, 11a.
...Female thread of the pressure nut.

Claims (1)

[Scope of Claims] 1) A structure for preventing corrosion of a threaded portion of a bolt that is fastened with a nut, which includes a cap screwed onto the threaded portion of the bolt so as to cover the nut, and a cap surrounded by the cap. The anti-corrosion structure of the bolt thread is made up of a filler material that is fully packed into the inner space of the bolt. 2) A mold body that has a structure to prevent corrosion of the threaded portion of the bolt when it is fastened with a nut, and is inserted into the outer periphery of the bolt threaded portion and surrounds the nut and the bolt threaded portion that protrudes from the upper end surface of the nut. a bolt threaded portion comprising: a pressurizing nut that is screwed onto the bolt threaded portion and presses the mold body; and a filler that is fully packed into the inner space of the mold body so as to embed the inner space. Anti-corrosion structure.