JP5467581B2 - Anchor head rust prevention treatment equipment - Google Patents

Description

  The present invention relates to an apparatus for rust-proofing an anchor head using a lock bolt or a deformed steel bar (a steel bar with a thread cut in part or over its entire length) or the like as a tension material. .

In an anchor using a rock bolt or a deformed steel bar, there is a regulation that maintains the tension by preventing corrosion of a portion exposed to the ground, that is, an anchor head.
Then, as a stopper for a tension material (for example, a lock bolt or a deformed steel bar) to which tension is applied in the underground anchor, a nut is screwed into the ground-side tip portion (or a portion near the tip) of the tension material. .
In order to exert the function of the nut as a fastener for a long period of time, it is necessary to provide a rust preventive treatment device (an anticorrosion treatment device for the anchor head) that protects the nut and prevents corrosion of the bolt and nut thread. There is.

FIG. 7 shows an anchor head rust prevention apparatus according to the prior art. In FIG. 7, the anchor head 11 of the anchor 10 embedded in the underground G is exposed to the ground, and the bearing plate 12 and the washer 51 are fitted into the anchor head 11 and tightened with a nut 52.
In the prior art of FIG. 7, the cap 54 in which grease is injected into the hollow portion 53 is put on the anchor head 11 to perform rust prevention treatment.
Reference numeral 58 in FIG. 7 indicates a through hole formed at the top of the cap 54, and reference numeral 59 indicates a plug that closes the through hole 58.
However, the anchor head rust prevention treatment device shown in FIG. 7 requires a large number of parts and a large number of processes, and therefore requires a lot of labor and cost for the rust prevention treatment work of the anchor head. Have a problem.

In order to solve the problem that the rust prevention treatment work of the anchor head in the prior art requires a great deal of labor and cost, the present applicant provided a rust prevention treatment device as shown in FIG. 8 (see Patent Document 1). .
8 includes a hollow cap-shaped nut member 1 and a support plate 12 disposed below the hollow cap-shaped nut member 1, and the hollow portion 2 of the cap-shaped nut member 1 has a female screw. Part 3 is formed.
The female threaded portion 3 has a shape that is screwed with a male threaded portion formed on a tension member (including a lock bolt: anchor 10), and the lower end corner portion of the cap-shaped nut member 1 and the bearing plate 12 A sealing mechanism 6 is provided for sealing the boundary portion.
And the through-hole 4 which connects the top part of the said cap-shaped nut member 1 and the hollow part 2 is formed. Through-holes 4, the air vent when performing molten zinc plating in the hollow portion 2 of the cap shape nut member 1 as a main purpose, was formed. In the prior art, since the grease is applied to the hollow portion 2, the through hole 4 is used for air venting.

The prior art (Patent Document 1) shown in FIG. 8 has an effect of reducing the number of parts and greatly saves labor in the rust prevention treatment work of the anchor head as compared with the prior art shown in FIG. This is a very useful technology.
However, with increasing awareness of the environment in recent years, it has been required in various fields not to use oil-based lubricants (grease) as much as possible, so-called “grease-less”. And also in the field of rust prevention treatment of the anchor head, it is required not to use grease (greaseless).
Here, in the prior art shown in FIG. 8 (Patent Document 1), the hollow portion 2 of the cap-shaped nut member 1 is filled with grease so as to prevent corrosion of the anchor head. For this reason, it is impossible to meet the demand for grease-less. In the prior art of FIG. 8 (Patent Document 1), since the cap-shaped nut member 1 is filled with grease, if grease leaks from the cap-shaped nut member 1, the environment of the construction site of the underground anchor will be increased. It will have a serious adverse effect.

Registered Utility Model Publication No. 3083619

  The present invention has been proposed in view of the above-described problems of the prior art, and in order to allow a desired tension to act on the underground anchor for a long period of time, it is possible to reliably corrode the thread of the anchor head. An object of the present invention is to provide an anti-corrosion treatment apparatus for an anchor head that can be prevented, does not require the use of grease, and does not adversely affect the environment.

The anchor head rust prevention apparatus (100) of the present invention includes a hollow cap-shaped nut member (cap nut 1) and a bearing plate (12) disposed below the cap-shaped nut member (cap nut 1).
An internal thread portion (3) is formed over the entire circumference in the radially inner circumferential direction of the hollow portion (2) of the cap-shaped nut member (1), and the internal thread portion (3) is a tension material. (10: tendon, uncurtain dong: including rock bolts and deformed steel bars)
The inner space (2) of the cap-shaped nut member (1) is closed on the top (1t) side (of the cap-shaped nut member 1),
Between the lower end corner portion (1b) of the cap-shaped nut member (1) and the bearing plate (12), a packing (50) made of a flexible material (for example, resin) is interposed,
The cap-shaped nut member (1) includes a cast iron hollow member (1F) in which a female thread portion (3) is formed radially inward, and an aluminum hollow member (1F) in which the cast iron hollow member (1F) is cast. 1A),
On the surface of the internal thread portion (3) and the radially outer surface (1Fs) formed in the cast iron hollow member (1F), an alumina layer and / or an aluminum layer is diffused into cast iron at a low temperature (700 ° C. or less). An alloy layer (Fe—Al layer: 1fa) formed is formed.

And the cap-shaped nut member (1) of this invention used with the rust prevention processing apparatus (100) of such an anchor head is formed in the hollow, The circumferential direction inside the radial direction of a hollow part (2) A female threaded portion (3) is formed over the entire circumference, and the female threaded portion (3) is screwed with a male threaded portion formed on a tension material (10: tendon, uncurtain dong: including lock bolt and deformed steel bar). In the cap-shaped nut member (1) for anchor head rust prevention treatment having a shape to
The internal space (2) (of the cap-shaped nut member 1) is closed on the top (1t) side (of the cap-shaped nut member 1),
(The cap-shaped nut member 1) is a cast iron hollow member (1F) having a female thread portion (3) formed radially inward, and an aluminum hollow member (1A) in which the cast iron hollow member (1F) is cast. )
On the surface of the internal thread portion (3) and the radially outer surface (1Fs) formed in the cast iron hollow member (1F), an alumina layer and / or an aluminum layer is diffused into cast iron at a low temperature (700 ° C. or less). An alloy layer (Fe—Al layer: 1fa) formed is formed.

And in order to manufacture the cap-shaped nut member (1) used with the antirust processing apparatus (100) of the anchor head mentioned above, the manufacturing method of the present invention comprises:
A step (S1) of performing molten aluminum plating on the surface (the female thread portion 3 and the radially outer surface 1Fs) of the cast iron hollow member (1F) having the female thread portion (3) formed radially inward;
A step (S2) of removing excess aluminum from the surface of the cast iron hollow member (1F);
After the excess aluminum is removed, the alumina layer and / or the aluminum layer is diffused at a low temperature (700 ° C. or less) on the surface of the cast iron hollow member (1F) (the internal thread portion 3 and the radially outer surface 1Fs). (Second diffusion) to form an alloy layer (Fe-Al layer: 1fa) (S3);
A step (S4) of casting the cast iron hollow member (1F) having an alloy layer (Fe-Al layer: 1fa) formed on the surface (the female thread portion 3 and the radially outer surface 1Fs) with aluminum (S4);
It is characterized by having.

According to the present invention having the above-described configuration, an alumina layer and / or an aluminum layer is formed on the cast iron at a low temperature (700 ° C. or lower) on the surface of the internal thread portion (3) formed on the cast iron hollow member (1F). Since the alloy layer (Fe-Al layer: 1fa) that has been subjected to diffusion treatment is formed, the alloy layer (1fa) has excellent corrosion resistance (for example, about five times that of molten aluminum plating). The tension material (10: tendon) screwed into the female thread portion (3) is prevented from corroding.
Therefore, the rust prevention treatment of the anchor head (11) can be performed without using grease, and the rust prevention treatment of the so-called “grease-less” anchor head which is environmentally friendly can be realized.
Then, according to the present invention there is no need to fill the grease, and flows out the grease from the cap-shaped nut member (1), there is no fear adversely affect the facilities Engineering site surrounding environment.

Here, according to the prior art, when hot-dip aluminum plating is performed, a so-called “water pool” is formed, or due to the presence of excess aluminum on the surface of the female screw portion (3), The internal thread portion (3) is difficult to mesh with the external thread portion (10m) of the tension member (10: tendon), and the tension member (10) is difficult to enter the cap-shaped nut member (1) (so-called "sludge" state). Problem).
On the other hand, according to the present invention, the alumina layer and / or the aluminum layer diffuses into the cast iron at a low temperature (700 ° C. or less) on the surface of the internal thread portion (3) formed in the cast iron hollow member (1F). When forming the treated alloy layer (Fe-Al layer: 1fa), the surface of the cast iron hollow member (1F) is subjected to hot-dip aluminum plating to remove excess aluminum, and then the cast iron hollow member (1F). On this surface, the alumina layer and / or the aluminum layer is subjected to diffusion treatment (secondary diffusion) at a low temperature (700 ° C. or lower) to form an alloy layer (Fe—Al layer: 1fa). Therefore, in the present invention, no “hot water pool” is formed in the female screw portion (3), and there is no surplus aluminum. Therefore, it is prevented that the tension member (10) is difficult to enter the cap-shaped nut member (1) (becomes a so-called “spray” state).

Here, according to the present invention, rust resistance and corrosion resistance are ensured by the alloy layer (Fe-Al layer: 1fa) formed on the surface of the cast iron hollow member (1F). It is not necessary to fill the inner space of the cap-shaped nut member (1). Therefore, the top (1t) side (of the cap-shaped nut member 1) is closed, and no through-hole is provided in the cap-shaped nut member top (1t) as in the above-described prior art.
Therefore, compared with a prior art, possibility that rainwater will penetrate | invade inside a cap-shaped nut member (1) is low, and the rust prevention property of an anchor head (11) further improves.

Further, in the present invention, a flexible material (for example, resin) packing (50) is interposed between the lower end corner portion (1b) of the cap-shaped nut member (1) and the bearing plate (12). Therefore, it is possible to prevent rainwater from entering from the boundary between the lower end corner portion (1b) of the cap-shaped nut member (1) and the bearing plate (12). And by interposing the packing (50) made of a flexible material, the cap-shaped nut member (1) is in good contact with the bearing plate (12).
At the same time, since the packing (50) is made of a flexible material and can be appropriately deformed, when the cap-shaped nut member (1) is tightened, the lower end corner portion of the cap-shaped nut member (1) (1b) and / or the bearing plate (12) can be prevented from being damaged.

As described above, according to the present invention, the aluminum hollow member (1A) casts the cast iron hollow member (1F). Here, if the alloy layer is also formed on the outer surface in the radial direction of the cast iron hollow member (1F), cast iron even if the aluminum hollow member (1A) casts the cast iron hollow member (1F). Electrolytic corrosion at the connection between aluminum and aluminum is prevented.
As a result, casting of the cast iron hollow member (1F) with the aluminum hollow member (1A) is reliably performed.

In the case where an external impact is applied to the cap-shaped nut member, if the resin or paint is only applied to the outer surface of the cap-shaped nut member on a normal casting, the cap-shaped nut member is exposed by the impact. There is a problem that the resin on the surface is broken or the coating is peeled off, the corrosion resistance is lowered, and the rust prevention or corrosion prevention of the anchor head is lowered.
On the other hand, in the present invention, even if an external impact acts on the cap-shaped nut member (1) by casting the cast iron hollow member (1F) with aluminum, the aluminum hollow member (1A) The casted hollow member (1F) screwed into the tension member (10) is not affected by the impacted portion only, and the anticorrosion property of the anchor head in the present invention has a problem. It does not occur.

  Furthermore, according to the present invention, since the cap-shaped nut member (1) also has a function of imparting a tensile force to the tension member (10), the number of members and parts required for the rust prevention treatment of the anchor head is reduced. Thus, labor and cost can be reduced.

It is sectional drawing which shows embodiment of this invention. It is a longitudinal cross-sectional view of the cap-shaped nut member in FIG. It is an elevation view of the cap-shaped nut member in FIG. It is a top view of the cap shape nut member 1 in FIG. It is the O section expanded sectional view of FIG. It is a manufacturing-process figure of the cap-shaped nut member shown in FIGS. It is sectional drawing which shows a prior art. It is sectional drawing of the prior art different from FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
In FIG. 1, an anchor head rust preventive treatment apparatus denoted by reference numeral 100 as a whole is composed of a hollow cap-shaped nut member (hereinafter referred to as “cap nut”) 1, a bearing plate 12, and a flexible material. A packing 50 is provided.
The bearing plate 12 is placed on the upper surface of the structure 200 constructed on the ground G.

In FIG. 2, the cap nut 1 has a cast iron hollow member 1F and an aluminum hollow member 1A encasing the cast iron hollow member 1F. In the hollow part 2 of the hollow member 1F made of cast iron, a female thread part 3 is formed over the entire area of the inner peripheral surface.
A female screw 3 f formed in the female screw portion 3 is formed so as to be screwed with a male screw 10 m formed in a tension material (for example, a lock bolt) 10.

In the illustrated embodiment, the hollow portion 2 is provided in substantially the entire region in the axial direction of the cast iron hollow member 1F (the vertical direction in FIGS. 1, 2, and 5), and in the hollow portion 2 of the cast iron hollow member 1F. A female thread portion 3 is formed over the entire area of the inner peripheral surface.
However, the hollow portion 2 may be formed only on a part of the bearing plate 12 side (the lower side in FIGS. 1, 2, and 5) in the axial direction of the cast iron hollow member 1F.
Further, the female screw portion 3 may not be formed in the entire area of the hollow portion 2 but may be formed only in a part on the side of the bearing plate 12 in the axial direction of the cast iron hollow member 1F.
In other words, the regions where the hollow portion 2 and the female screw portion 3 are formed can be set as appropriate.

The cast iron hollow member 1F has a cylindrical shape as a whole, and a flange 1Ff is formed at the lower end in FIG. The outer edge of the lower surface of the flange 1Ff is chamfered 1Fc.
On the outer peripheral surface of the cast iron hollow member 1F, annular protrusions 1Fd are formed at four positions in the axial direction (vertical direction in FIG. 2) in FIG. Although not clearly shown, a so-called “R” is formed at the corner of the annular protrusion 1Fd.
The flange 1Ff and the annular protrusion 1Fd of the cast iron hollow member 1F are displaced in the axial direction of the aluminum hollow member 1A (vertical direction in FIG. 2) by the cast iron hollow member 1F embedded in the aluminum hollow member 1A. It is provided to prevent this.

The surface of the internal thread portion 3 formed on the inner peripheral surface of the cast iron hollow member 1F and the outer peripheral surface of the cast iron hollow member 1F are subjected to molten aluminum plating.
Here, when the molten aluminum plating process is performed, an aluminum layer is formed, but the thickness of the aluminum layer is not uniform. Therefore, conventionally, it has been difficult to apply molten aluminum plating to precision parts such as screws.
On the other hand, in the illustrated embodiment, the thickness dimension (film thickness) of the formed aluminum layer can be made uniform by re-heat-treating the one that has been subjected to the molten aluminum plating at a temperature of 700 ° C. or lower. . For this reason, it is possible to form an aluminum layer on the surface of a precision part such as a screw by performing a heat treatment again at 700 ° C. or lower after the molten aluminum plating process.
In general, when steel is heated to 500 ° C. or higher, oxidation is accelerated, and it rapidly scales and corrodes. When the molten aluminum plating treatment is performed, aluminum diffuses and permeates into the steel to form an alloy layer (Fe—Al layer), and an aluminum oxide film (alumina film) is formed on the surface. The alumina coating and the alloy layer (Fe—Al layer) having a melting point of about 1160 ° C. prevent oxygen from entering. Therefore, after re-heat treatment at 700 ° C. or lower after the hot-dip aluminum plating treatment, excess aluminum is removed, making it less likely to corrode by about 7.5 times the corrosion rate compared with hot-dip galvanization, and the estimated life years Has about 16 times the corrosion resistance and is excellent in corrosion resistance.

In FIG. 3, the aluminum hollow member 1A is entirely cylindrical, and a hexagonal portion 16 is formed on the lower end side in FIG.
The hemispherical top 1t of the aluminum hollow member 1A is not provided with a through-hole that has been formed in the prior art, but is closed.

In FIG. 2, a through hole 1 </ b> Ah whose diameter is larger than the diameter of the valley of the female screw part 3 is formed in the lower end surface of the aluminum hollow member 1 </ b> A.
A flat surface portion 1Bt is formed at the lower end of the aluminum hollow member 1A. A corner portion 1b is formed on the outer side in the radial direction of the flat surface portion 1Bt, and the corner portion 1b is smoothly finished so as to have a spherical shape (a part of the spherical surface: hereinafter the same). .
The spherical spherical corner portion 1b is in contact with the tapered surface (tapered portion 52) of the packing 50 as shown in FIG.
At the same time, the spherical spherical corner portion 1b also has a function of arranging the cap nut 1 so that the central axis of the cap nut 1 and the axial direction of the lock bolt 10 coincide with each other at an appropriate position on the bearing plate 12.

FIG. 5 shows the O portion in FIG. 1 in an enlarged manner.
In FIG. 5, the packing 50 has a cylindrical portion 51 and a tapered portion 52. The dimension of the taper portion 52 in the radial direction (left-right direction in FIG. 5) gradually increases as the distance from the cylindrical portion 51 increases (as it extends upward in FIG. 5).
In FIG. 5, the axial dimension of the cylindrical portion 51 is represented by the symbol H ₅₀ , the outer diameter of the cylindrical portion 51 is represented by the symbol D ₅₀ , the taper angle at the tapered portion 52 is represented by the symbol α, and the thickness of the packing 50 is represented by the symbol t. .
At the center of the Bearing plate 12, through holes 12h are formed, the inner diameter of the through hole 12h is set to a value obtained by adding a predetermined tolerance (loose fit) to the outer diameter D ₅₀ of the cylindrical portion 51 .

The outer diameter D50 of the cylindrical portion 51 of the packing ₅₀ is set so that the packing 50 can be easily inserted into the through hole 12h of the bearing plate 12 and the sealing performance can be maintained.
In FIG. 5, chamfering is formed in the upper part of the through hole 12 h of the bearing plate 12. In the through hole 12 h, the axial dimension (vertical dimension in FIG. 5) other than the chamfered portion is indicated by a symbol H ₁₂ , and the dimension H ₁₂ is the axial dimension H in the cylindrical portion 51 of the packing 50. Roughly equal to ₅₀ .
The chamfering angle β in the chamfer formed in the upper portion of the through hole 12 h of the bearing plate 12 is equal to the taper angle α in the tapered portion 52 of the packing 50.

The packing 50 is made of a flexible material (for example, a hard resin). When the cap nut 1 is tightened, the packing 50 is suitably deformed and is in good contact with the cap nut 1 and the bearing plate 12.
Accordingly, it is possible to prevent water from entering from the boundary between the cap nut 1 and the bearing plate 12 and to ensure the rust prevention performance of the head of the lock bolt 10 over a long period of time.

Next, a method for manufacturing the cap nut 1 will be described with reference to the process chart of FIG.
First, as a pretreatment in step S1 of FIG. 6, a cast iron hollow member is subjected to internal thread processing to produce a cast iron hollow member (internal thread processed cast iron hollow member) 1F having an internal thread portion 3. Then, the cast iron hollow member 1F subjected to the female thread is degreased, pickled, and dried.
In the first step (step S1), a molten aluminum plating process is performed on the radially inner and outer surfaces (or the entire surface) of the cast iron hollow member 1F that has been internally threaded.

Next, in the second step shown in step S2 of FIG. 6, surplus aluminum is removed from the radially inner and outer surfaces of the cast iron hollow member 1F subjected to the molten aluminum plating process.
By removing excess aluminum from the surface of the cast iron hollow member 1F, the shape and accuracy of the internal thread 3f of the cast iron hollow member 1F are maintained. At the same time, the so-called “water pool” is prevented from being formed in the eye screw portion 3.
Or it prevents that the internal thread part 3 becomes difficult to mesh with the external thread part 10m of the lock bolt 10, and maintains the state in which the lock bolt 10 enters the cap nut 1 easily. It is prevented from becoming difficult to enter (so-called “swift” state).

Next, in the third step shown in step S3 of FIG. 6, the surface of the cast iron hollow member 1F from which excess aluminum has been removed is reheated at 700 ° C. or lower. In other words, the outer peripheral surface of the surface and cast iron hollow member 1F of the female screw portion 3 formed on the inner peripheral surface of the cast iron hollow member 1F, diffusion process alumina layer and / or the aluminum layer at a low temperature (700 ° C. or less) By doing so, an alloy layer (Fe-Al layer: 1fa) is formed.
By performing the molten aluminum plating treatment, aluminum diffuses and penetrates into the steel to form an alloy layer (Fe—Al layer) 1fa, and an aluminum oxide (alumina) film is formed on the surface. The alumina coating and the alloy layer having a melting point of about 1160 ° C. prevent oxygen from entering, and can prevent oxidation or rusting of the surface of the internal thread portion 3 and the outer peripheral surface of the cast iron hollow member 1F.
Further, the surface of the cast iron hollow member 1F from which excess aluminum has been removed is re-heated at 700 ° C. or less, so that excess aluminum is removed, the film thickness of the aluminum plating becomes uniform, and the threads are smoothly screwed together. Is possible.

In the fourth step shown in step S4 of FIG. 6, a cast iron hollow member 1F having an alloy layer (Fe—Al layer) 1fa formed on the surface is cast with aluminum so as to have an outer shape as shown in FIG. Wrapping.
As described above, the lower edge of the flange 1Ff is chamfered 1Fc, and the corners of the annular protrusion 1Fd are rounded. Therefore, when casting the cast iron hollow member 1F with aluminum, the flange It is possible to prevent the formation of voids (so-called “nests”) in which no aluminum exists in the lower edge of 1Ff and the annular protrusion 1Fd.

Next, with reference to FIG.1 and FIG.5, the rust prevention process of the anchor head by the rust prevention apparatus using the cap nut 1 is demonstrated.
In FIG. 1, a sleeve 210 is interposed in a through hole 201 drilled in a structure 200.
A predetermined amount of the anchor head 11 of the lock bolt 10 is exposed from the through hole 201 with the sleeve 210 interposed.

In the rust prevention treatment of the anchor head, the bearing plate 12 is prepared, and the packing 50 is inserted into the through hole 12 h of the bearing plate 12.
Then, the bearing plate 12 in which the packing 50 is fitted is placed on the through hole 201 in the structure 200. At this time, the center of the through hole 12h of the bearing plate 12 and the axial center of the lock bolt 10 are substantially matched.
Next, the cap nut 1 is put on the anchor head 11 of the lock bolt 10, and the female screw of the female screw portion 3 of the cap nut 1 is screwed onto the male screw of the lock bolt 10.

In FIGS. 1 and 5, two surfaces of a hexagonal portion 16 at the lower end of the aluminum hollow member 1 </ b> A in the cap nut 1 are aligned with two surfaces of a tool (not shown) such as a torque wrench so that the specified tensile force of the lock bolt 10 is obtained. The cap nut 1 is tightened with the tool (not shown) until the corresponding tightening torque is reached.
By tightening the cap nut 1, a tensile force acts on the lock bolt 10, and the cap nut 1 is pressed against the bearing plate 12 with the packing 50 interposed. Then, the center axis of the cap nut 1 coincides with the center axis of the lock bolt 10. (So-called “centering” is done.)
At that time, the packing 50 made of a flexible member is deformed to completely seal the boundary portion between the cap nut 1 and the bearing plate 12, and rainwater enters from the boundary portion. To prevent.
Thereby, the construction of the rust prevention treatment of the anchor head is completed.

Here, the alloy layer (Fe—Al layer) 1fa described above has extremely excellent corrosion resistance (for example, corrosion resistance about five times that of molten aluminum plating).
Therefore, even if grease is not enclosed in the cap nut 1, corrosion of the head 11 of the lock bolt 10 screwed with the female screw portion 3 can be prevented. As a result, the rust prevention treatment of the anchor head can be performed in an environmentally friendly manner that does not use grease (so-called “grease-less”).
Since rust processing apparatus 100 according to the illustrated embodiment is "greaseless", never grease from the cap nut 1 flows out, there is no adverse effect due to grease flows out to the facilities Engineering site surrounding environment .

Further, since the rust preventive treatment apparatus 100 according to the illustrated embodiment is “grease-less” and it is not necessary to fill the internal space of the cap nut 1 with grease, the cap nut 1 is filled with grease on the top 1t side. There is no need to form a through hole. As a result, in the illustrated embodiment, the top 1t side of the cap nut 1 is closed, and no through hole as in the prior art is formed.
Since it is not necessary to form a through hole on the top 1t side of the cap nut 1, labor and cost for manufacturing the cap nut 1 can be saved. Further, since no through hole is formed on the top 1t side of the cap nut 1, in the illustrated embodiment, rainwater can enter the cap nut 1 as compared with the cap nut of the prior art (Patent Document 1). The rust prevention property of the anchor head 11 is further improved.

In the illustrated embodiment, when the alloy layer (Fe—Al) layer 1fa is formed on the surface of the internal thread portion 3 formed on the cast iron hollow member 1F, hot aluminum plating is applied to the surface of the cast iron hollow member 1F. Then, excess aluminum is removed from the surface, and the alumina layer and / or the aluminum layer is subjected to diffusion treatment (secondary diffusion) at a low temperature (700 ° C. or less) on the surface of the cast iron hollow member 1F, and the alloy A layer (Fe—Al layer) 1fa is formed.
Therefore, the so-called “hot water pool” is prevented from being formed due to the presence of surplus aluminum on the surface of the female screw portion 3. Then, the internal thread portion 3 does not easily engage with the external thread portion 10m of the lock bolt 10, and the external thread portion 10m of the lock bolt 10 becomes difficult to enter the cap nut 1 (a so-called "slip" state). ) There is nothing.

Further, in the illustrated embodiment, since a flexible resin packing 50 is interposed between the lower end corner portion 1b of the cap nut 1 and the bearing plate 12, the cap nut 1 is tightened. By applying a tensile force to the lock bolt 10, the packing 50 is compressed and deformed, and is crimped to a boundary portion between the cap nut 1 and the bearing plate 12 to be sealed.
Therefore, it is possible to reliably prevent rainwater from entering from the boundary portion between the cap nut 1 and the bearing plate 12.
Further, since the packing 50 is interposed, when the cap nut 1 is tightened and a tensile force is applied to the lock bolt 10, the lower end corner 1b of the cap nut 1 and / or the bearing plate 12 may be damaged. Is prevented.

In addition, in the illustrated embodiment, the aluminum hollow member 1A encloses the cast iron hollow member 1F. And since the said alloy layer (Fe-Al layer) 1fa is formed also in the radial direction outer surface of the cast iron hollow member 1F, even if the aluminum hollow member 1A casts the cast iron hollow member 1F. In addition, electrolytic corrosion at the connecting portion between cast iron and aluminum is prevented.
As a result, casting of the cast iron hollow member 1F by the aluminum hollow member 1A is reliably performed, and the anchor head is also rust-proofed.

  Further, by casting the cast iron hollow member 1F with aluminum, even if an external impact is applied to the aluminum hollow member 1A for some reason, the portion where the impact is applied is only recessed, and the lock is locked. The cast iron hollow member 1F screwed with the bolt 10 is not affected, and the anticorrosion property of the anchor head in the embodiment is maintained. The resin on the outer surface of the cap-shaped nut member is damaged by the impact, as in the case where resin or coating is applied to the outer surface of the cap-shaped nut member, or the coating is peeled off, and the corrosion resistance is reduced. The problem that the rust prevention or anticorrosion property of the head is lowered does not exist in the illustrated embodiment.

  Furthermore, according to the illustrated embodiment, the cap nut 1 also has a function as a device for applying a tensile force to the lock bolt 10, so that members and parts required for the rust prevention treatment of the anchor head This also has the effect of reducing necessary labor and costs.

  The illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Cap shape nut member / Cap nut 1A ... Cast iron hollow member 1B ... Aluminum hollow member 1fa ... Alloy layer 2 ... Hollow part 3 ... Female thread part 10 ... Tension Material / anchor / lock bolt 11 ... anchor head 12 ... bearing plate 16 ... hexagonal part 50 ... packing 200 ... structure G ... ground

Claims (3)

A hollow cap-shaped nut member, and a bearing plate disposed below the hollow cap-shaped nut member,
A female screw portion is formed over the entire circumference in the radially inner circumferential direction of the hollow portion of the cap-shaped nut member, and the female screw portion is configured to be screwed with a male screw portion formed in the tension member. Yes,
The inner space of the cap-shaped nut member is closed on the top side,
Between the bottom corner portion of the cap-shaped nut member and the bearing plate, a packing made of a flexible material is interposed,
The cap-shaped nut member has a cast iron hollow member in which a female thread portion is formed radially inward, and an aluminum hollow member in which the cast iron hollow member is cast,
An anchor characterized in that an alloy layer in which an alumina layer and / or an aluminum layer is diffused in cast iron at a low temperature is formed on the surface of the internal thread portion formed on the hollow member made of cast iron and on the radially outer surface. Anti-rust treatment equipment for the head. It is formed in a hollow shape, and a female screw portion is formed over the entire circumference in the radial direction inside the hollow portion, and the female screw portion has a shape that engages with a male screw portion formed in a tension member. In the cap-shaped nut member for anchor head rust prevention treatment,
The interior space is closed on the top side,
A hollow member made of cast iron in which a female screw portion is formed radially inward, and a hollow member made of aluminum in which the cast iron hollow member is cast;
An alloy layer in which an alumina layer and / or an aluminum layer is diffused in cast iron at a low temperature is formed on the surface and the radially outer surface of the female screw portion formed in the cast iron hollow member. Cap-shaped nut member. A step of applying molten aluminum plating to the surface of a hollow member made of cast iron in which a female screw portion is formed radially inwardly;
Removing excess aluminum from the surface of the cast iron hollow member;
After removing excess aluminum, a step of diffusing the alumina layer and / or the aluminum layer at a low temperature on the surface of the cast iron hollow member to form an alloy layer;
Casting the cast iron hollow member having an alloy layer formed on the surface thereof with aluminum;
The manufacturing method of the cap-shaped nut member characterized by having.

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